Abstract: In this paper, the offshore wind farms have been designed by using WindPRO with the help of real wind data measurements at Jeju Costal area by calculating the annual energy production for exact economic evaluation. In order to achieve benefit of wind farm, the annual revenue for power generation have been calculated with SMP and REC value. And construction cost has derived from the real wind farm project case. Also O&M cost has been estimated by OMCE (Operating & Maintenance Cost Estimator) to get accurate cost of wind farm. Economic evaluation of wind farms have been performed by comparing above parameters. In addition, sensitivity analysis calculating the effect of these factors has also been carried out.

Abstract: Biodiesel is technically competitive with it and offers technical advantages over conventional petroleum diesel fuel. Biodiesel is an environment friendly alternative liquid fuel that can be used in any diesel engine without modification. In this study, (dP/dCA)max and heat release, emission characteristics with different fuel injection timings are compared between diesel fuel and biodiesel in the D.I. diesel engine with T/C. The engine was operated at five different fuel injection timings from BTDC 6deg to 14deg at 2deg intervals and with four different loads at engine speed of 1800rpm. The experiments in a test engine showed that ranges between low and high of (dP/dCA)max got narrower, as the engine load increased, BD blend rate increased, and fuel injection timing was delayed. Cumulative heat release increased with the advanced fuel injection timing. NOX emissions decreased with the delays of fuel injection timing.

Abstract: The numerical analysis by using CFX 11.0 commercial code was done for prediction of fluid flow and thermal field in the vertical heat exchanger. The present experimental studies were also conducted to investigate the effects of circulating solid particles on the fluid flow and temperatures in the fluidized bed vertical shell and tube type heat exchanger with counterflow, at which the solid particles of glasses (3 mmΦ) were used in the fluidized bed with a smooth tube. The effect of circulation on the distance(L) of tube inlet and baffle plate was also examined. The present experimental and numerical results showed that the particles in the distance (Ds) of 15 mm showed a more efficient circulation without stacked the space and the LMTD(Log Mean Temperature Difference) in the fluidized bed type was much lower than that in the typical type shell and tube heat exchanger.

Abstract: A numerical procedure is described for predicting the dynamic structural responses of tension leg platforms(TLPs) in current and waves. The developed numerical approach is based on a combination of the three dimensional source distribution method and the dynamic structural analysis method, in which the superstructure of the TLPs is assumed to be flexible instead of rigid. The hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural damping are included in the dynamic structural analysis. The equations of motion of a whole structure are formulated using element-fixed coordinate systems which have the origin at the nodes of the each hull element and move parallel to a space-fixed coordinate system. The dynamic structural responses of a TLP were analyzed in the case of including the current or not including the one in waves and the effects of current on the TLP were investigated.

Abstract: In the present study, process optimization for thermal-sprayed Ni-based alloy coating has been performed using Taguchi method and analysis of variance(ANOVA). Ni-based alloy coatings were fabricated by flame spray process on steel substrate, and the hardness test and wear test were performed. Experiments were designed as per Taguchi`s L9 orthogonal array and tests were conducted with different Oxygen gas flow, Acetylene gas flow, Powder feed rate and Spray distance. Multi response signal to noise ratio (MRSN) was calculated for the response variables and the optimum combination level of factors was obtained simultaneously using Taguchi`s parametric design.

Abstract: In this paper, the authors propose a new approach to control a barge type surface vessel. It is based on the Dynamic Positioning System(DPS) design. The main role of barge ship is to carry and supply the materials to the floating units and other places. To carry out this job, it should be positioned in the specified area. However sometimes the thrust systems are installed on it, and in general the rope control by mooring winch system is used. It may be difficult to compare the control performances of two types. If we consider this problem in point of usefulness, we can easily find out that the winch control system is more useful and applicable to the real field than the thrust control system except a special use. Therefore, in this paper we consider a DPS design problem which can be extended to the many application fields. The goal of this paper is twofold. First, the sliding mode controller (SMC) for positioning the our vessel is proposed. Especially, in this paper, a robust stability condition is given based on descriptor system representation. In the result, the sliding mode control law guarantees to keep the vessel in the defined area in the presence of environmental disturbances. And second, the thrust allocation problem is solved by using redistributed pseudo-inverse (RPI) algorithm to determine the thrust force and direction of each individual actuator. The proposed approach has been simulated with a supply vessel model and found work well.

Abstract: 공기 양수 펌프는 재생 에너지 분야, 부식 및 마모 특성의 유체의 활용 등 높은 신뢰성과 낮은 유지보수 비용을 필요로 하는 분야에서 그 사용이 증대되고 있다. 본 연구에서는 소형 공기 양수 펌프의 성능 평가 및 기초 데이터를 얻기 위한 연구로, D=0.012~0.019m, L=0.933m인 배관의 침수 깊이(β=0.55,0.60,0.65,0.70)에 따른 수치해석을 수행하였다. 수치 해석 및 실험 결과는 유사성을 뛰었으며, 펌프의 사양과 효율은 공기의 질량 유속비, 침수 깊이비와 양수 배관의 길이에 관한 함수로 나타났다. 그리고 최대물과 공기 질량 유속의 비는 각 배관에서 서로 다른 침수 깊이의 비로 나타났으며, 공기 양수 펌프의 최대 효율이 발생 되는 운전조건은 슬러그(slug)와 슬러그 교반 정도(slug-churn flow regime)에 따라 나타남을 알 수 있었다.

Abstract: A scroll expander has been designed to produce a shaft power from a R134a Rankine cycle for electricity generation. Heat was supplied to the Rankine cycle through a heat exchanger, which received heat from another cycle of water. In the water cycle, water was heated up in a boiler using biogenic solid fuel. The designed scroll expander was a horizontal type, and a trochoidal oil pump was employed for oil supply to bearings and Oldham-ring keys. For axial compliance, a back pressure chamber was created on the backside of the orbiting scroll base plate. Numerical study has been carried out to estimate the performance of the designed scroll expander. The expander was estimated to produce the shaft power of about 2.9 kW from a heat supply of 36 kW, when the temperature of R134a was and at the evaporator and condenser of the Rankine cycle, respectively. The expander efficiency was about 70.5%. When the amount of heat supply varied in the ranges of 7.5~55 kW, the expander efficiency changed in the range of 45.6~70.5%, showing a peak efficiency of 70.5% at the design shaft speed.

Abstract: This paper describes an analysis on performance of R744-R404A cascade refrigeration system with internal heat exchanger to optimize the design for the operating parameters of the system. The operating parameters considered in this study include subcooling and superheating degree, internal heat exchanger and compression efficiency, evaporating and condensing temperature in the R744 low- and R404A high-temperature cycle and temperature difference of cascade heat exchanger. The main results are summarized as follows : COP of cascade refrigeration system increases with the increasing of compression efficiency, but decreases with the increasing temperature difference of cascade heat exchanger. Also, the COP increases with the increasing of internal heat exchanger efficiency in high-temperature cycle, but decreases with that in low-temperature cycle. Therefore, internal heat exchanger efficiency, compressor efficiency and temperature difference of cascade heat exchanger on R744-R404A cascade refrigeration system have an effect on the COP of this system.

Abstract: Recently we have a growing interest in environmental pollution and alternative energy. Diesel engine is generally used to produce the power on the ground and the sea. However, the combustion characteristics are changed on account of the wear of fuel system and the altered ambient condition of the combustion chamber by the increment of the engine operation hour. Therefore combustion characteristics on fuel injection timing are experimentally investigated to find out the optimum fuel injection timing in the case of the aged diesel engine using biodiesel blend oil. Cylinder pressure, rate of pressure rise, rate of heat release and combustion gas temperature are risen by the advancing fuel injection timing, while the exhaust gas temperature and soot emission level are decreased by the advancing of fuel injection timing. The least specific fuel oil consumption is indicated at BTDC CA on the 75%load and at 1800rpm.

Abstract: The authors suggest the algorithm for the static analysis of a three dimensional solid structure by using the finite element-transfer stiffness coefficient method (FE-TSCM) and the hexahedral element of the finite element method (FEM). MATLAB codes were made by both FE-TSCM and FEM for the static analysis of three dimensional solid structure. They were applied to the static analyses of a very thick plate structure and a three dimensional solid structure. In this paper, as we compare the results of FE-TSCM with those of FEM, we confirm that FE-TSCM introducing the hexahedral element for the static analysis of a three dimensional solid structure is very effective from the viewpoint of the computational accuracy, speed, and storage.

Abstract: In unmanned vehicles` navigation, the shapes of obstacles are generally irregular and complex. The motion of vehicles based on the range sensor system such as ultrasonic sensors or laser sensors can be unstable due to the irregular shape of the obstacles. In this case, to generate stable trajectory of unmanned vehicles equipped with range sensors, we need an approach that can simplify an obstacle`s irregular shape information. In this paper, we propose the trajectory generation algorithm that an vehicle can stably navigate in the environments where irregular shaped obstacles are scattered. The proposed method is verified through the analysis of vehicle`s trail and direction data acquired by simulations and implementations.

Abstract: Roll forming process is one of the most widely used processes in the world for forming metals such as a furniture drawer guide or an up and down slide guide. It can manufacture goods of the uniform cross section on a large scale throughout the continuous processing. In the domestic design and manufacture, roll forming process for production is taking most of the method of 2-point under rail slide. However, this method is vulnerable to the structural strength and stiffness is not suitable for high load conditions. Therefore, through systematic study of high load, low noise 3-point ball type of under rail slide its own design and manufacturing technology is the need to build. In this paper, to make center member of 3-point ball-type under rail slide for the refrigerator doors, the roll forming modeling and simulation are performed. Tensile test is performed about SCP-1 1/2H for determine the mechanical properties of materials. Modeling and simulation of roll forming is used MSC.MARC software of a dedicated analysis program used by rigid plastic finite element method. Interference between the roll and the final shape are predicted from the results of the simulation.

Abstract: ：In this paper, the bending characteristics of the corrugated plates is analyzed. The trapezoidally, triangularlly and sinusoidally corrugated plates are considered. The corrugated plate is treated as an orthotropic plate that has different flexural properties in two perpendicular directions. The equivalent bending and twisting rigidities for the equivalent orthotropic plates are derived. The equivalent flexural rigidities are estimated under the following postulations: (1) The angle of continuously corrugated plate is not changed after the deformation. (2) When the pure bending moment is applied in corrugated direction of the plate, the its plane is in pure bending. Several numerical examples are analyzed with the proposed method and compared with published results. **†김영완(교신저자) : 전남대학교 기계자동차공학부E-mail : wannkim@jnu.ac.kr, Tel : 061-659-7285 *정 강 : 전남대학교 기계자동차공학부**†Y. W. Kim(corresponding author) : Department of Mechanical & Automotive Engineering, Chonnam National University.E-mail : wannkim@jnu.ac.kr, Tel : 061-659-7285 *K. Jung : Department of Mechanical & Automotive Engineering, Chonnam National University.

Abstract: The steady three-dimensional computational thermal flow analysis using standard k- turbulence model was carried out to investigate the heat transfer characteristics of a cabin cooler for a commercial vehicle The heat exchanging method of this cabin cooler is to use the cooling effect of a thermoelectric module In view of the results so far achieved, the air system resistance of a cabin cooler is about 124 Pa as a static pressure, and then the operating point of a cross-flow fan considering in this study is formed in the comparatively low flowrate region The air temperature difference obtained from the cold part of an thermoelectric module is about , and the cooling water temperature difference obtained from the hot part of an thermoelectric module is about

Abstract: The steady three-dimensional numerical analysis on the thermal flow using standard k- turbulence model was carried out to investigate the air cooling effect of a cooler on the cabin for a commercial vehicle. Here, the heat exchanging method of this cabin cooler uses the cooling effect of a thermoelectric module. In consequence, the air system resistance of a cooler within the cabin is about 12.1 Pa as a static pressure, and then the operating point of a virtual cross-flow fan considering in this study is formed in the comparatively low flowrate region. The discharging air temperature of a cooler is about . Moreover, the air cooling temperature difference obtained under the outdoor cabin temperature of shows about in a driver resting space and about in the front of a driver`s seat including the space of a driver`s foot.

Abstract: In this paper, the algorithm for the static analysis of an axisymmetric cylindrical shell by using the finite element-transfer stiffness coefficient method (FE-TSCM) is suggested. TE-TSCM combining both the modeling procedure of the finite element method (FEM) and the transfer procedure of the transfer stiffness coefficient method (TSCM) has the advantages of FEM and TSCM. After computational programs are made by both FE-TSCM and FEM for the stress analysis of the axisymmetric cylindrical shell, we compare the numerical results by FE-TSCM with those of FEM for two computational models in order to confirm the trust of FE-TSCM. *최명수(교신저자) : 전남대학교 해양경찰학과 E-mail : engine@chonnam.ac.kr, Tel : 061-659-7183 **여동준 : 전남대학교 해양기술학부 *M. S. Choi(corresponding author) : Department of Maritime Police Science, Chonnam National University. E-mail : engine@chonnam.ac.kr, Tel : 061-659-7183 **D. J. Yeo : Faculty of Marine Technology, Chonnam National University. 1. 서 론 액체 또는 가스를 운반하거나 저장하는데 사용되 는 파이프(pipe) 및 압력 용기 그리고 우주 항공 구 조물 등에서 쉽게 찾아볼 수 있는 원통형 셸 구조물 은 공학적으로 중요한 구조물로써, 안전성을 확보하 기 위해 설계 시에 응력해석이 수행되어야 한다. 현재, 셸 구조물의 응력해석을 위해 다양한 소프트 웨어들이 개발되어 있고, 이 소프트웨어들의 내부 알 고리즘을 분석해 보면 거의 대부분 유한요소법(finite element method)이 기본 알고리즘으로 채택되어 있 다. 유한요소법은 복잡한 구조물의 해석을 기본적인 요소들의 결합으로 단순화하여 모델링하고 이를 해 석하므로 전산 알고리즘이 단순하다는 것이 장점이 다. 그러나 대규모 자유도를 갖는 복잡한 구조물에 대해 해석을 수행할 경우에는 계산 시간이 아주 길 어지고 대용량의 컴퓨터 메모리를 필요로 하는 취약 점이 있다. 저자들은 유한요소-전달강성계수법(finite elementtransfer stiffness coefficient method) 을 개발하여 평판 구조물과 솔리드(solid) 구조물의 정적 및 동적 해석에 적용하여 그 유효성을 확인해 왔다. 이 방법 은 유한요소법의 모델링 과정과 전달강성계수법 (transfer stiffness coefficient method)의 강성계수 의 전달 과정을 조합하여 해석을 수행하는 방법으로 서 유한요소법과 전달강성계수법의 장점을 공유하는 특징이 있다. 그러나 해석기법으로서 완전한 독자성 및 신뢰성을 확보하기 위해서는 다양한 구조물에 대 한 일반적인 해석이 가능해야하므로, 본 연구에서 저 자들은 원통형 셸의 응력해석에 유한요소-전달강성 계수법을 도입하는 연구를 수행하게 되었다. 원통형 셸이 구조적으로 축대칭이고, 하중도 축대 칭인 경우에는 응력해석을 효과적으로 수행할 수 있 다. 따라서 이 논문에서는 축대칭 원통형 셸을 해석 대상으로 유한요소-전달강성계수법을 이용하여 응력 해석을 수행하고, 유한요소법과의 수치 계산 결과의 비교를 통해 유한요소-전달강성계수법의 신뢰성을 확인한다.

Abstract: The geothermal energy is one of the renewable energy sources which can contribute in accomplishing a vision and goal of the national plan on energy for a government suggestion. Especially, the geothermal energy is evaluated as the nearly unlimited resources. The yearly underground temperature distribution by depth is very important to the design of air-conditioning system which uses a geothermal energy. Furthermore, there has no data for comparisons to numerical analysis. In this study, the yearly underground temperature is measured under the depth of 2 m in Tongyeong, and these data are compared with numerical analysis results for checking the accuracy. The results showed that the experimental temperature and numerical results had a good agreements and these results will be utilized to predict a performance of air-conditioning system for using a geothermal energy.

Abstract: The numerical analysis by using CFX 11.0 commercial code was done for prediction of fluid flow and thermal field in the vertical heat exchanger. The present experimental studies were also conducted to investigate the effects of circulating solid particles on the fluid flow and temperatures in the fluidized bed vertical shell and tube type heat exchanger with counterflow, at which the solid particles of glasses (3 ) were used in the fluidized bed with a smooth tube. The effect of circulation on the distance(L) of tube inlet and baffle plate was also examined. The present experimental and numerical results showed that the particles in the distance (Ds) of 15 mm showed a more efficient circulation without stacked the space and the LMTD(Log Mean Temperature Difference) in the fluidized bed type was much lower than that in the typical type shell and tube heat exchanger.

Abstract: 본 논문은 작업공간상에서 로봇 운동과 힘의 통합제어를 구현할 수 있는 플랫폼의 구현에 초점을 두고 있다. 조립 또는 디버링 같은 접촉작업에서의 매니플레이터 효율성 제고나 친 인간 환경에서의 휴머노이드 로봇의 안정성을 위해서는 종래의 PID 제어나 관절공간상에서의 CTM(Computed Torque Method) 제어 보다는 작업공간상에서의 운동과 힘의 통합제어를 실시해야 한다. 이것을 위해서는 작업공간상에서의 엔드 이펙트(end-effector, E-E)에 대한 동역학식과 자코비안(jacobian)을 도출해야 하며 이를 위해서는 각종 동적파라미터의 정확한 동정이 중요하다. 본 논문에서는 3D CAD 모델링, MATLAB, 동역학 시뮬레이터를 활용하여 로봇 모델링, 동역학식과 동적 파라미터 추출, 운동과 힘의 실시간 통합제어 시뮬레이션등을 쉽고 일관 되게 진행할 수 있는 플랫폼을 구현하였고 적용예로써 JS-10로봇을 택해서 그 효용성을 입증하였다.

Abstract: 본 논문에서는 항내에서 저속으로 운동(항해)하는 선박의 운동제어문제에 대해 고려하고 있다. 항내에서는 특히 그 운동속도가 느리므로 일반 항해에서와는 달이 저주파대역에서의 운동특성이 중요하다. 대부분의 중대형선박이 항내에서 터그보트에 의해 접안시설로 이동하게 된다. 이러한 사실을 고려하여 대상선박이 4기의 터그보트에 의해 제어되는 선박의 제어계 설계문제에 대해 고찰하고 있다. 주요 연구내용은 크게 두가지로 구분된다. 첫째 비선형특성이 강하게 포함되어있는 선박운동특성을 고려하여 비선형관측기를 설계한다. 이것은 특히 저주파수 대역에서 선박의 위치와 속도 등 제어신호를 계산하는데 필요한 정보를 추정하는데 유효한 방법으로 잘 알려져 있다. 이를 기반으로 외란 등에 강인한 슬라이딩모드 제어기를 설계한다. 결과적으로 비선형관측기를 포함한 슬라이딩모드제어기의 유용성을 시뮬레이션을 통해 검증하였으며 이 결과는 실험을 위한 유용한 기초자료로 활용될 것이다.

Abstract: Torque Generator is a product which has function to transform hydraulic energy to mechanical energy of torque and rotating speed, and be used for direction change device of agricultural machines. This study proposes failure analysis and test analysis on torque generator and introduces a process that reliability of a product is enhanced by design improvement. And also it presents improvements of maximum output torque by modifying design and surface treatment. Lastly it verifies reliability improvement by analyzing test results of before and after life test. *†정동수(교신저자) : 한국기계연구원 시스템신뢰성연구실 E-mail : jds667@kimm.re.kr, Tel : 042-861-7154 **이용범, 박종원 : 한국기계연구원 시스템신뢰성연구실 *†D. S. Jung(corresponding author) : Department of System Reliability, Korea Institute of Machinery and Marterials. E-mail : jds667@kimm.re.kr, Tel : 042-861-7154 **Y. B. Lee and J. W. Park : Department of System Reliability, Korea Institute of Machinery and Marterials. 1. 서 론 토크 발생기는 차량의 파워 스티어링 시스템에 적 용되는 유압 핵심부품으로써 방향제어 및 액추에이 터 기능을 수행한다. 펌프에서 공급되는 유압 에너지 를 토크 및 회전속도의 기계적인 에너지로 변환하는 기능을 갖는 제품으로써 이앙기와 같은 농기계의 방 향 전환 장치, 선박의 조타 시스템, 대형 수문의 개 폐 시스템 등 산업 전반에 적용된다. 본 연구에서의 토크 발생기는 조향 축과 조향 바 퀴 간에 기계 장치로 연결되어 있는 유압-기계 방식 으로써 조향 축의 토크를 증폭하여 바퀴에 전달한다. 농업 경작, 건설 현장 등의 열악한 작업조건에서 사 용되는 장비에 적용되기 때문에 제품의 신뢰성을 확 보하기 위해서는 부하변동에 따른 제반 조건을 고려 한 시험평가를 수행해야 한다. 국내 중소기업의 연구 기반을 고려하고, 현실적으로 제품의 생산, 판매에만 집중하고 있는 업계의 현실로 볼 때, 신뢰성 분석 및 시험을 위한 고급 인력 및 장비 확보를 위해서는 많 은 간접비용이 투자되어야 하므로 중소기업이 독자 적으로 추진하기가 어려운 실정이다. 신뢰성 시험평가는 현장의 작업환경에서 직면하는 다양한 시험조건을 재현하고 시험결과를 평가할 수 있는 평가기준을 제시하고 있기 때문에 기존의 시험 규격들과 차별화된다. 평가항목들은 현장고장 및 고 장모드 분석을 통하여 고장에 영향을 미치거나 평가 에 필요한 시험항목들로 선정되며 크게 성능시험, 수 명시험, 그리고 환경시험으로 구분된다. 이러한 시 험평가는 고장재현을 통하여 고장개선이 가능하기 때문에 제품의 신뢰성을 향상시키는 효과도 있다. 본 연구에서는 토크 발생기에 대하여 고장분석 및 시험평가를 제안하고 설계개선을 통하여 제품의 신 뢰성이 향상되는 전체의 과정을 소개한다. 마지막으 로, 수명시험 전ᆞ후의 시험결과를 분석하여 신뢰성 향상을 입증한다.

Abstract: This paper presents an analysis on the induction heating of ring flange for wind farm. Ring flange is used for the connection of poles when building a column of wind power plant. Heat treatment of ring flange with the diameter of has been considered. For analysis on the induction heating, FEA is used. Firstly, electromagnetic filed analysis was performed to get the induction current distribution on the steel, After that, heat transfer analysis was performed using the magnetic filed analysis results. for more precise analysis, some measurement for permeability has been performed and the measurement data was used during the analysis. From the analysis, we get the temperature distribution on the ring flange.

Abstract: It is being accelerated to develop environment-friendly vehicles to solve problems on the energy and environment of earth. The electric driving motor commonly installed in these vehicles has the excellent control capability such as fast response and accurate generation to torque control command. Especially, in-wheel motor has the additional merit such as independently driving each wheel in vehicle. Recently, being developed various control algorithm to enhance the safety and stability of vehicle motion using actively the merits of in-wheel motor. In addition to that, being issued the possibility of enhancing the ride comfort and attitude of vehicle motion such as pitching and rolling. In this paper, investigate the theoretical relationship between the braking/driving force and the motion of sprung mass of vehicle and propose the control method to enhance the ride comfort and attitude of vehicle motion. The proposed control method is proved through the simulation with vehicle model provided by TruckSim software which is commercial one and specializes in vehicle dynamics.

Abstract: In this study, the numerical simulation and basin model test have been performed to evaluate sea worthiness and resistance performance for a small pre-planning three type of leisure boats which are U, V, Y shapes of hull forms. As a well known commercial CFD code, Maxsurf, was applied for modeling hull forms used as the solver of motion analysis. Also the model resistance test was carried out to estimate the effective power of boat in the basin tank. Numerical simulation and model test results show that Y-shaped hull is better than the other types in terms of heave and pitch motion, having a key effect on a boat sea worthiness. But V-type hull is more efficiency than others cases in resistance performance.

Abstract: Centrifugal compressors are widely used and each operating condition is different. However, it cannot be manufactured according to the every operating condition. In the this study, performance of compressor was evaluated with various rotational speeds of impeller and various stagger angles of diffuser in order to apply a typical model widely. A centrifugal compressor was designed and manufactured based on the design point. On this machines, an experiment was conducted and the performance was predicted at off-design point. The performance prediction was validated with the experimental result and the numerical result. Although the isentropic efficiency on the prediction was slightly lower than that on the experimental result due to the heat loss in the experiment, the pressure ratio was predicted well and also the predicted results were matched well with the numerical results. When the rotational speed of the impeller and the stagger angle of the diffuser were changed together, the compressor can be worked in the high efficiency region and avoided operating in the stall region.

Abstract: Active magnetic bearings(AMBs) present a technology which has many advantages compared to traditional bearing concepts. However, they require backup bearings in order to prevent damages in the event of a system failure. In this study, the dynamics of an AMB supported rotor during impact on backup bearings is studied employing a detailed simulation model. The backup bearings are modeled using an accurate ball bearing model, and the model for a flexible rotor system is described using the finite element approach with the component mode synthesis. Not only the influence of the support stiffness, clearance and friction coefficient on the rotor orbit, but also bearing load are compared for various rotor system parameters. Comparing these results it is shown that the optimum backup bearing system can be applicable for a specific rotor system.

Abstract: The reliability qualification test is essential in order to ensure the life time of the product under the normal operation conditions when a new product is developed. The reliability qualification test period has an important impact on the development time of new product. Therefore, some researches to reduce the test time of reliability qualification test have been actively studied. Generally, accelerated life test is well known as one method that can save the test time of the reliability qualification test. This test is conducted under the higher stress condition than normal condition. So we need to investigate what factor affects to the higher stress condition. This paper shows the relationship between the acceleration factor and reliability qualification test period. Especially, we focused on the method to obtain effective acceleration factors under the high temperature condition. Through some experiments for a refrigerator`s compressor, we were able to confirm how to increase acceleration factors and how to reduce the reliability qualification test period with minimum samples.

Abstract: Novel mechanisms for Energy Recovery Devices are proposed to diminish the pressure loss in the high-pressure reverse-osmosis system. In the beginning, the state-of-the-art in the design of Energy Recovery Devices is reviewed and the features of each model are investigated. The direct-coupled axial piston pump(APP) and axial piston motor(APM) showed 39% energy recovery at operating pressure of reverse osmosis desalination systems, 60 bar. Meanwhile, the developed PM2D model, in which APM pistons are arranged parallel to those of APP, is more compact and showed higher efficiency in a preliminary test. Loss-reduction mechanisms employing rod piston and double raw valve port are additionally proposed to enhance the efficiency and durability of the device.