Abstract: Harnessing energy from alternative energy source has been recorded since early history. Renewable energy is abundantly found anywhere, free of cost and has non-polluting characteristics. However, these energy sources are based on the weather condition and possess inherited intermittent nature, which hinders stable power supply. Combining multiple renewable energy resources can be a possible solution to overcome defects, which not only provides reliable power but also leads to reduction in required storage capacity. Although an oversized hybrid system satisfies the load demand, it can be unnecessarily expensive. An undersized hybrid system is economical, but may not be able to meet the load demand. The optimal sizing of the renewable energy power system depends on the mathematical model of system components. This paper summarizes the mathematical modeling of various renewable energy system particularly PV, wind, hydro and storage devices. Because of the nonlinear power characteristics, wind and PV system require special techniques to extract maximum power. Hybrid system has complex control system due to integration of two (or more) different power sources. The complexity of system increases with maximum power point tracking (MPPT) techniques employed in their subsystems. This paper also summarizes mathematical modeling of various MPPT techniques for hybrid renewable energy systems.

Abstract: Unmanned Aerial Vehicles (UAVs) have been developed to perform various military and civilian applications, such as reconnaissance, attack missions, surveillance of pipelines, and interplanetary exploration. The present research is motivated by the need to develop a fast adaptable UAV design technologies for agile, fuel efficient, and flexible structures that are capable of adapting and operating in any environments. The objective of this research is to develop adaptive design technologies by investigating current design methods and knowledge of deployable technologies in the area of engineering design and manufacturing. More specifically, this research seeks to identify one truss lattice with the optimal elastic performance for deployable UAV wing design according to the Hashin & Shtrikman theoretical bounds. We propose three lattice designs — 3D Kagome structure, 3D pyramidal structure and the hexagonal diamond structure. The proposed lattice structure designs are fabricated using an Objet 350 3D printer while the material chosen is a polypropylene-like photopolymer called Objet DurusWhite RGD430. Based on compression testing, the proposed inflatable wing design will combine the advantages of compliant mechanisms and deployable structures to maximize flexibilities of movement in UAV design and development.

Abstract: The pressing needs of energy, water and other resource conservation worldwide is a major engineering challenge. In manufacturing, developing green technologies (from process and tooling to the entire enterprise) is one way to insure that future manufacturing systems are sustainable. To do this, innovation in advanced manufacturing is needed. The basic requirements of green technology are discussed along with methods and tools to insure they are effectively applied and their impacts measured. For situations in which the manufacturing environmental burden is less than the burden for the use of the product leveraging is proposed to insure a total life cycle impact reduction. Examples of several green technologies are presented.

Abstract: In this paper, a total of 57 micro and nano scale hybrid manufacturing processes are reviewed. These processes are categorized in terms of process timing and process type. Process timing is one of the most important aspects of manufacturing, and three different process schemes — concurrent, main/assistive (M/S) separate, and main/main (M/M) separate — are considered. The process type is categorized as either geometrically additive or subtractive, and all hybrid processes are categorized into combinations of additive, subtractive, and assistive process. Features and advantages are described for each of these classifications. Machining is found to be the most common process for both micro and nano-scale hybrid manufacturing. Of micro scale hybrid manufacturing schemes, 74.4% use assistive processes as a secondary process because the main purpose of most micro scale hybrid manufacturing is to improve the quality of the process. In nano scale manufacturing, 61.5% of hybrid manufacturing schemes employ assistive processes, since these processes typically focus on the fabrication of parts that are difficult to fabricate using a single, existing process. Based on a summary of published work, future trends in hybrid manufacturing at the micro and nano scale are suggested.

Abstract: In metal forming, lubricants are still used to prevent corrosion, to reduce friction, wear and tool load as well as to protect the workpieces and intermediates. In economic and ecological points of view, the challenge is the avoidance of lubricant usage. Within this article we define the term of dry metal forming, a technology which contributes an approach to establish green technology in mass production. Regarding this, the benefits of this technology are shown. Three different approaches exist to achieve a dry forming process: ceramic tools, self-lubricating coating systems and hard material coatings. Concerning this matter, the state of research in dry metal forming is reviewed within this paper.

Abstract: The International Journal of Precision Engineering and Manufacturing-Green Technology (IJPEM-GT) was inaugurated in order to foster knowledge sharing and collaboration of researchers in the field of “green manufacturing.” While emerging technologies can be evaluated by business points of view such as Hype Cycle of Gartner, in this paper, journals and research areas in green manufacturing were evaluated by using research databases such as Web of Science and Journal Citation Report. Using impact factor and the number of published papers as key parameters, journals in subjects of Engineering-Mechanical, Engineering-Manufacturing, Engineering-Environmental, and Energy and Fuels were compared. From the point of researchers, the H-Index and the number of published papers were evaluated for journals and technologies in green manufacturing. The H-Index of journals or research areas was proportional to logarithm of the number of papers, and linear trend lines were observed from the data. The journals in green technology show higher gradient in the trend line compared with the journals in manufacturing and environmental areas. In addition, a Four Stage Model (early-emerging-developed-saturated stages) of technology development was proposed.

Abstract: We present a continuous fabrication method to make bio-inspired water collecting surface by using roll type photolithography for potential applications to real time air monitoring system. In this study, the carapace of the stenocara beetle was mimicked to achieve water collection from air, using a molding process involving micro-/nanofabrication techniques and roll type photolithography. We fabricated a super-hydrophilic surface on top of a super-hydrophobic surface and used two different setups to demonstrate water collection, a thermoelectric module and a humidifier. Also, the optimized geometric design for water collection was found from 16 different test samples. Detection of mercury is shown as a feasible practical application of such surfaces.

Abstract: Using multi-characteristic information fusion based on a BP (back propagation) NN (neural network) of the plume and spatters to monitor the high-power disk laser welding of type 304 austenitic stainless steel is presented. An ultraviolet and visible sensitive highspeed video camera was used to capture the dynamic images of laser welding plume and spatters during laser welding. The number and area of spatters, and the area, height, tilt angle and centroid of plume were calculated by using image processing technology and defined as the characteristic parameters of plume and spatters, which were used as inputs of the neural network. The weld bead width was considered as a parameter reflecting the welding status, which was used as output of the neural network. Relations of plume and spatters with laser welding status was established by a BP neural network and experimental results showed that the proposed method could effectively estimate the high-power disk laser welding status when the laser power ranged from 2 kW to 10 kW.

Abstract: Owing to mounting environmental issues, coupled with public pressure and stringent regulations, firms and companies have to alter their ways of developing new products. Three key areas i.e. end-of-life (EOL) management, green supply chain and sustainable manufacturing have to be considered during design stage. The purpose of this paper is to propose a framework based on axiomatic design (AD) principles to facilitate sustainable product development by aiding the decision making process in the abovementioned key areas. Several examples have been provided in this paper to demonstrate the application of crisp and fuzzy AD approaches with the aim of assisting analysis and/or decision making process. Results show that axiomatic design principles are able to guide designer/engineer in selecting functional embodiment that facilitates product recovery and fuzzy axiomatic design approach can be effective when dealing with problems concerning green supplier selection and optimization of manufacturing solution. Hence, a framework for sustainable product realization is proposed in the last section of this paper with a vision of providing guideline for companies in designing and developing products that are less harmful to the environment.

Abstract: This paper investigates characteristics of the TRB such as displacements, contact forces between roller and inner ring, outer ring and flange, contact angle between roller and flange, load distribution along roller, and stiffness matrix, when the TRB is subjected to combined radial and moment loads. Understanding of these characteristics deserves attention for developing more sustainable TRBs. To this end, a five-degree-of-freedom model of TRB is employed. Unlike other studies, this paper takes TRB displacements as unknown variables and determines them by iteratively solving the roller and bearing equilibrium equations. A new formula for load variation in rollers is also presented by using an integration technique. The developed method is validated by comparing preliminary results with those from a reference program. The characteristics of TRBs subjected to combined radial and moment loads are simulated as a function of roller profile and rotational speed.

Abstract: Hall sensor array is used to measure the position of a magnet array and needs compensation of errors caused by manufacturing tolerances as well as harmonic components of the magnetic flux of the magnet array. This paper presents a 2D hall sensor array to measure the position of a magnet matrix by filtering harmonic components. First, 1D sensor array to filter out arbitrary number of harmonic signals is proposed and extended to 2D sensor array for the position measurement of a magnet matrix. A 2D hall sensor array for filtering both fundamental and 2nd harmonic components of the magnetic flux and its conditioning circuit board are built to measure the position of the magnet matrix for a planar motor. Finally, performances of filtering harmonics and measuring position of the magnet matrix are experimentally verified with a XY linear motion stage. The proposed 2D hall sensor array is compatible to a sine encoder and is directly applicable to commercial motion controllers.

Abstract: This work studies the effect of PEDOT:PSS on electrical, optical and mechanical properties of ITO glass. Various thickness PEDOT:PSS films are deposited on ITO glass by spin coating. The sheet resistance, transmittance, surface roughness, residual stress, friction, and critical load of the coated specimens are tested in sequence. We find that PEDOT:PSS films not only improve the electric performance but also increase the adhesion of ITO glass. The experimental results show that the PEDOT:PSS film improves the surface roughness and then results in a lower electric resistance. It also increases the adhesion and reduces the residual stress of the ITO films. Furthermore, only 1% transmittance is lost due to the PEDOT:PSS film, showing the potential in the applications of organic photovoltaic cells and light-emitting diodes.

Abstract: This study was performed to investigate the joining possibility and characteristics of the dissimilar joint between carbon fiber reinforced plastics (CFRP) and amorphous polyethylene terephthalate (PET) plastic using a continuous wave (cw) diode laser with a line-shaped beam. Tensile shear test results demonstrated that strong lap joints with a maximum load of 3200 N could be produced under some proper conditions, and base amorphous PET plastic sheet was elongated without fracture. It was confirmed from SEM observation that the dissimilar lap joint was tightly bonded near the joint interface between two materials, and simultaneously integrated by the interdiffusion and mixing process at the joint interface of two materials through rapid melting, solidification and cooling during laser joining. Through high speed video camera observation, the joining phenomena generating in the laser irradiated part during laser joining of CFRP to PET was obviously identified. Consequently, it was revealed that strong dissimilar lap joint of CFRP to engineering plastic could be possible by a direct laser irradiation without adhesive bonds or mechanical fasteners.

Abstract: Air-breathing proton exchange membrane fuel cells (AB-PEMFCs) can reduce the cost, complexity, noise, volume, and weight of fuel cells and can enhance their reliability. However, such cells are still typically characterized by low output power densities. In this study, to overcome the inherent weaknesses of low power density and oxygen concentration without mobility loss, we have adopted a microscale synthetic jet air breather (a crucial balance-of-plant device), which supplies air to the cathode side of the flow field of a planar AB-PEMFC. A synthetic jet air breather consists of a PZT diaphragm actuator, small cylindrical cavity, inlet and outlet channels, and a pump body. The flow rate of the fabricated synthetic jet air breather is more than 400 cc/min at 550 Hz with a power consumption of less than 0.3 W. An AB-PEMFC equipped with a microscale-synthetic jet air breather shows higher performance and stability, obtaining a maximum power density of 188 mW/cm2 at 400 mA/cm2.

Abstract: The globalization of suppliers and personalization of customers require new manufacturing strategy for environmental issues, region’s special regulation and energy besides manufacturing factors from manufacturers. In this study, green factory is defined as a manufacturing floor that reduces waste elements such as extra work, energy, time and cost through quickly responding to external uncontrollable changes like a regulation, due date and supply. Therefore, the green factory should respond by establishing and implementing strategies for controlling their production volumes, changing their dispatch rules, adjusting their work schedules, increasing and decreasing the number of their machines and workers based on their own internal data and capacities, and other measures. To achieve such objective, manufacturing companies should realize a manufacturing intelligence that can visualize their shop-floor data, and detect and solve problems at the business planning level. In this study, an agile operations management (AOM) system that can quickly respond to field problems was developed for manufacturing intelligence. The AOM system refers to a system that collects internal data, monitors such data in real time, immediately detects problems, if any, and provides solutions to the detected issues within the shortest time.

Abstract: The manufacture of helical pinion gears has involved machining processes such as hobbing and shaving to achieve the required dimensional accuracy. However, these conventional processes have some disadvantages such as excessive material loss, low productivity, high-energy consumption, and high carbon emissions. To overcome these problems, a cold extrusion process is applied to the manufacture of helical gears. In this study, we analyze the environmental effects of the cold extrusion process, designed for the sustainable production of helical gears. We quantitatively analyze the environmental effects of the conventional machining and cold extrusion processes, using the Life Cycle Assessment technique in accordance with ISO 14000. This analysis includes the energy consumption and carbon emissions for a helical gear manufactured using the conventional machining processes and those of single- and double-type gears manufactured using the cold extrusion process. Moreover, the material properties of the extruded helical gears are compared with the conventionally machined gears. In conclusion, the extruded gears exhibited a higher strength while consuming less energy during their manufacture than the gears manufactured using the conventional machining processes. Further, this alternative process is more cost effective as it generates less waste and exhibits high productivity compared to the conventional machining processes.

Abstract: Chemical mechanical planarization (CMP) is an essential manufacturing process in semiconductor fabrication. Chipmakers continue to adopt CMP for device planarization or surface finishing of substrate materials. Evaluating the environmental impact of the CMP process may contribute to the greening of the semiconductor process. In this paper, we propose a mathematical model-based evaluation method to determine the environmental burden of the CMP process. We adopted our previously reported material removal rate (MRR) model for CMP and modified it to incorporate the effect of the slurry flow rate and process temperature. The established model was compared with the experimental results. The environmental burden of the CMP process was evaluated by converting the electric energy consumption, slurry consumption, and ultrapure water (UPW) consumption into their carbon dioxide equivalents (CDEs). The results showed that the slurry consumption strongly impacted the CDE of the CMP process. The results of this study may help optimize the process parameters for a sustainable CMP process.

Abstract: Ultrasonic imprinting is a novel process in which micro-patterns can be replicated on thermoplastic polymer with short processing time and low energy consumption. Ultrasonic imprinting uses ultrasonic vibration energy to soften thermoplastic polymer, and to replicate micro-patterns on the softened polymer surface from a patterned horn or mold. In this study, a new patterning method based on ultrasonic imprinting is proposed to develop composite micro-patterns using a simply-patterned mold. The proposed patterning technology uses repetitive ultrasonic imprinting in which a patterned replica is imprinted repeatedly on a rotated position. To implement this process for the development of composite micro-patterns, two-step repetitive imprinting with 90° rotation was performed using a prism-patterned mold, from which pyramid patterns can be developed. This repetitive imprinting was then further applied to fabricate composite micro-patterns that contain prism and pyramid micropatterns on a single polymer film.

Abstract: In this study, effect of fiber morphology on orientation is evaluated. Therefore, intersection angle for chopped strand, fiber length, and structure of fiber mat is changed to make the corresponding specimens and the relationship between compression ratio and fiber orientation is derived. Factors for controlling flow of glass fiber are glass fiber and matrix. 3 types of specimens, they are heated in oven as blank. Secondary hot press is applied. During compression molding, flow of test specimen is restricted to longitudinal direction. Measurement area for fiber orientation is 50 mm × 50 mm area in length of molded part, and the image is processed to confirm fiber orientation function. Fiber orientation function value, which is an indicator for directionality of fiber, is increased along with longer fiber length and higher compression ratio. Higher needle punching number induces tangling of fibers, and less fiber orientation function can be achieved. Fewer needles punching number results the less interference between fibers and fiber orientation function is increased accordingly. Fiber orientation angle, an indicator for fiber directionality in composite, can be empirically estimated according to compression ratio and fiber morphology using the derived equations.

Abstract: The gas diffusion layer (GDL) is an important component of proton-exchange membrane fuel cells (PEMFCs) that participate in the interplay of the transport of different species. During the assembly of PEMFCs, mechanical pressure is applied to the solid boundary of bipolar plates to reduce the porosity of the adjacent GDL, especially under land areas. This variation in porosity reduces reactant consumption in the catalyst layer and primarily causes non-uniform current density in PEMFCs. To compensate for the loss of porosity in the GDL, a composite porous diffusion layer was used as a GDL with higher porosity in the under-land areas of the GDL than that in the under-channel areas. A numerical simulation was conducted to investigate the effect of the positional variation of porosity on the performance of the PEMFC. The overall performance of the cell was investigated through a polarization plot, and the local mass transport of the reactant species was evaluated at the two reaction sites. The introduction of the proposed composite porous GDL improved the performance of the PEMFC by enhancing the transport of the reactant species to and from the reaction site.

Abstract: The influence of the area difference between the current collector and the thin-film-processed cathode on the performance evaluation of the solid oxide fuel cell (SOFC) is investigated. Two 2 cm by 2 cm anode supported SOFCs with a 1 cm by 1 cm cathode (Cell-1.0) and a 1.5 cm by 1.5 cm cathode (Cell-2.25) are fabricated and the performances are measured in a button cell test set-up with a cathode current collection area of 1 cm by 1 cm. Significantly different cell power outputs are measured. The total power output of the Cell-2.25 is 1.35~1.68 times to that of the Cell-1.0. The discrepancy is considered to originate from two major reasons: 1. limited lateral conduction and 2. thin thickness of the cathode. The cell performance can be overestimated when the smaller area is chosen, or underestimated when the larger area is chosen as the active area between the current collection area and the cathode area. The present study identifies another important factor to be considered to exactly assess the performance of the SOFC implementing thin-film-processed electrode.

Abstract: This study considers the performance of a direct methanol fuel cell (DMFC) unit for the various compression ratios of a gas diffusion layer (GDL) on the cathode side. A performance of fuel cells is significantly influenced by the compression ratio of the GDL. The compression ratio of the GDL can be directly controlled by the concentration compression force at the central area of the cell and gasket thickness. The balancing of the compression ratio is an important factor to increase the unit cell performance of DMFCs. In this study, the performance test of the unit cell for varying compression ratio of a GDL on the cathode side is carried out. We describe how the compression ratio affects the stack performance by the variation of compression force for two different kinds of current collectors, which directly compresses the central area of the unit cell with varying gasket thickness. This study also suggests a method to show the effect of mass transport loss by amplitude of voltage fluctuation and the unit cell relationship between the pressure drop information and the peak power of the unit cell.

Abstract: An effective and reliable fabrication approach for silver nanostructure arrays was developed using UV nanoimprint with a lift-off resist and a Si-based etch mask for enhanced plasmonic resonance-driven device performance. Since a tapered nanopillar array is imprinted on the resist, by coating it with a Si-based etch mask layer and carrying out the etching procedure, a reverse-tapered nanohole array for metal deposition can be crated. Compared to the conventional lift-off process, a more tolerable window of life off process conditions is possible, and dot patterns with high-aspect-ratio thickness profiles and no rabbit ears can be fabricated. Simulation results corresponding to dot diameters of 150, 235, and 265 nm (twice those in their period) were qualitatively in good agreement with experimental results in terms of transmittance. This suggests that the proposed technique is a fairly reliable and accessible fabrication strategy for applications.

Abstract: End-of-life vehicles (ELVs) are important recycling sources, and there are several recycling stages, including dismantling, shredding, and treatment of the automotive shredder residues (ASR). The legal recycling rate should be at least 95% by 2015. To achieve this, a unified system to monitor the recycling of ELV parts and to calculate practical recycling rates is required. This paper describes a web-based monitoring system equipped with the databases for a standard parts list, dismantling & recycling, and standard recycling rate. The system effectively collects dismantling & recycling data, and it calculates a part’s recycling rate based on the collected data. It also facilitates the estimation of a reasonable recycling rate for unreported parts by utilizing a standard recycling rate and respective ratio of treatment. The system is designed and implemented in a Windows® environment, as part of a research project sponsored by the Ministry of Environment of Korea.

Abstract: The integrated material flow analysis methodology uses bottom-up flow analysis for primary and secondary resources and top-down flow analysis for the distribution structure. By combining the advantages of the top-down and bottom-up methods, the integrated material flow analysis Methodology can overcome the limitations of each method. Using the IMFAM, this study investigated the material flow of terbium in 2011, in Korea. Terbium was used to produce 3-wevelength fluorescent lamps, liquid crystal display back light unit, plasma display panel and so on. 7,239 kg of terbium was required to produce the intermediate product in Korea. Among total terbium used to produce intermediate products, 2,592 kg the part of the fluorescent lamp, 4,984 kg the part of flat panel display, which were used, 107 kg, was exported and 46 was put in collect stage. In the part of the 3-wevelength fluorescent lamp, terbium’s use was expected to gradually increase for needs of consumers. But in the part of flat panel display, terbium’s use is expected to gradually decrease. The use of terbium is expected to decrease in others. This MFA results represent the materials flow of terbium in Korea and can be used to predict demand through investigations on the demand industry.

Abstract: Slurry containing SiC powder and oil is used to cut ingots with a wire in a solar cell wafering process. The slurry, which is generally recycled due to its high price, produces a residue known as sludge during the recycling process. The sludge is mainly composed of SiC, Si, and oil. This study proposed a method to remove Si and oil from sludge to obtain a high-purity SiC powder of approximately 98.5% in an economically feasible manner. Additionally, this study utilized the recycled SiC powder to develop a porous SiC ceramic heat sink with thermal conductivity of about 10W/mK and showed that the heat sink can be used as an efficient apparatus to release heat of electronics.

Abstract: Localized charge transfer reactions induced by the external bias were observed near the electrode-electrolyte interfaces by Kevin probe microscopy. Spatially resolved potential measurements revealed the localized charge accumulation and rearrangement driven by the external bias, which were ascribed to oxidation and reduction of the oxide surface. This in situ measurement of charge distribution with spatial information under controlled environments can be particularly useful in investigating the charge transfer reactions on the surfaces of functional materials and enhance our understanding of many electronic and electrochemical devices.

Abstract: The influence of fabrication processes on the LIBS (Laser Induced Breakdown Spectroscopy) spectra of major and minor chemical constituents in CuIn1-xGaxSe2 (CIGS) absorber films produced by co-sputtering and co-evaporation techniques on Mo-coated soda lime glass (SLG) is reported It was found that the ablation rate per pulse of CIGS layers fabricated by the co-sputtering technique is higher than those fabricated by the co-evaporation technique, resulting in higher LIBS signal intensities of the constituent elements The examination of surface morphology of irradiated surfaces and changes in LIBS signal intensities revealed evidences of elemental fractionation for the CIGS films fabricated by co-sputtering technique but not for those by co-evaporation technique From x-ray diffraction measurements, it was confirmed that the differences in the ablation and spectroscopic characteristics of the two different types of CIGS absorber films were contributed to the differences in crystalline properties Furthermore, it was demonstrated that LIBS can effectively determine a depth profile of sodium concentration in CIGS thin films, diffused from SLG

Abstract: Recently, efficient use of energy resources has become a very critical issue in most industries due to various reasons such as the high price of energy resources and environmental problems. The printed circuit board (PCB) industry is known as one of the major manufacturing industries that consumes a moderately large amount of electricity. Of all PCB manufacturing processes, the photolithography process is the most complicated. The photolithography process consists of: 1) a lamination process; 2) an exposure process; and, 3) a development process. Particularly, the lamination process appears to consume the most energy among the entire PCB manufacturing processes. This is due to the use of high temperatures and high pressures in that process which are required to employ photo sensitive dry film resist-coating on the panel. In addition, the PCB panel quality after the lamination process is highly dependent on conditions of three main operating parameters, temperature, pressure, and conveyor belt speed. In this research, we employ designed experiments and model-building techniques to obtain optimal settings of the three main operating parameters which will simultaneously minimize energy consumption while maximizing the probability of creating a non-defective PCB panel during the lamination process.