• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.8
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• pp.996-1008
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• 1997

This paper describes a methodology and results for the analysis of a small steam injected gas turbine cogeneration system. A performance analysis program for the gas turbine engine is utilized with modifications required for the model of steam injection and the heat recovery steam generator (HRSG). The object of simulation is a simple cycle gas turbine engine under development which adopts a centrifugal compressor. The analysis is based on the off-design operation of the gas turbine and the compressor performance map is utilized. Analyses are carried out with the injection ratio as the main parameter. The effect of steam injection on the power and efficiency of gas turbine and cogeneration capacity is investigated. Also presented is the variation in the main operating parameters inside the HRSG. Remarkable reduction in NOx generation by steam injection is confirmed. In addition, it is observed that for the 100% power operation the temperature of the cooled first nozzle blade decreases by 100.deg. C at full steam injection, which seems to have a favorable effect on the engine life time.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.126-132
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• 2011

Fatigue cracks of the turbocharger are often observed for high performance engines under thermal shock tests. Maximum exhaust gas temperature of recently developed gasoline engines could reach approximately $950^{\circ}C$. It's very important to estimate transient temperature histories during thermal shock cycles to predict the stress and the fatigue life of the turbocharger. With these temperature profiles, temperature-dependent material properties and boundary conditions, we could identify critical locations by the application of finite element simulation technologies. In this paper, we applied the reliable analysis approach to the actual turbocharger to predict the weak locations due to the repetitions of plastic strains and compared the results with the crack locations under physical engine test.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.92-98
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• 2013

There are lots of studies about hybrid electric vehicles (HEVs) because of the global warming and energy problems. Series and parallel HEVs are the common types of many developing hybrid vehicle types. Series HEV uses engine only as the generator for the battery but parallel HEV utilizes engine for driving and generating of the vehicle. In this paper, backward simulations based on dynamic programming were conducted for the fuel economy analysis of two different types of hybrid transit buses depending on driving cycles. It is shown that there is a relation between the type of HEV and the characteristics of driving cycles. Regarding the aggressiveness, the series hybrid bus is more efficient than the parallel system on highly aggressive driving cycle. On the other hand, the parallel hybrid bus is more efficient than the series system on low aggressive driving cycle. Based on this results of the paper, it is expected to choose more efficient type of the hybrid buses according to the driving cycle.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.2
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• pp.161-168
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• 2015

Recently, due to various environmental problems such as global warming, increases of international oil prices, exhaustion of resource, a paradigm of world automobile market is rapidly changing from conventional vehicles using internal combustion engine to eco-friendly vehicles using electric power such as EV, HEV, PHEV and FCEV. Generally, in order to measure fuel consumption and pollutant emissions of cars, chassis dynamometer tests are performed on various driving cycles before actual driving test. There are many driving cycles for performance evaluation of conventional vehicles. However, there is a lack of researches on driving cycle for EV. In this study, the urban driving cycle for performance evaluation of electric vehicles was developed. This study is composed of two parts. In the part 1, the urban driving cycle 'GUDC-EV(Gwacheon-city Urban Driving Cycle for Electric Vehicles)' was developed by using driving data, which were obtained through actual driving experiment, and statistic analysis with chronological table. In this paper part 2, in order to verify the developed driving cycle GUDC-EV, virtual EV platforms were configured and simulations were performed with actual driving data using In addition, simulation results were compared with existing driving cycles such as FTP-72, NEDC and Japan 10-15.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.6
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• pp.839-845
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• 2021

In this study, it shows the efficiency of each refrigerant through simulation method for ORC (Organic Rankine Cycle) power generation that converts waste heat discarded by ship exhaust into electricity for the purpose of reducing CO₂ emission and increasing ship waste heat recovery. by Simulation was performed with waste heat from the exhaust gas which is relatively high temperature and cooling sea water which is relatively low temperature from ships. As a result of the sea water cooling ORC power generating system, efficiency of the working fluid with R717 is highest as a 2.86 % and the next working fluid is R152a, R134a, R143a and R125a.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.5
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• pp.313-320
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• 2011

For a steam Rankine cycle to recover waste heat from the exhaust gas of an Internal combustion engine, a swash plate type of expander as a power conversion unit has been designed. Numerical simulation has been carried out to estimate the performance of the designed expander. With the steam pressure and temperature of 35 bar and $300^{\circ}C$ at the expander inlet, respectively, the expander was estimated to produce the shaft power output of about 2.67 kW from the exhaust gas waste heat of 25.2 kW. The expander output increased almost linearly with the amount of exhaust gas waste heat in the range of from 5~40 kW, and the expander and Rankine cycle efficiencies showed gradual decreases in the ranges of 72.2%~69.5% and 10.8%~10.4%, respectively.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.705-708
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• 2011

Ejector system can induce the secondary flow or affect the secondary chamber pressure by both shear stress and pressure drop which are generated in the primary jet boundary. Ejectors are widely used in a range of applications such as a turbine-based combined-cycle propulsion system and a high altitude test facility for rocket engine, pressure recovery system, desalination plant and ejector ramjet etc. The primary interest of this study is to set up an design procedure on the configuration and operating condition of multi-ejector for the various high altitude simulation.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.298-300
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• 2006

산업현장에서 로봇의 사용이 크게 늘게 됨으로서 로봇의 배치와 움직임의 조정을 효율적으로 하는 것이 중요해 졌다. 이를 위해 가상의 공간에서 시뮬레이션 하는 오프라인 프로그래밍이 사용되고 있다. 본 논문에서는 오프라인 프로그래밍 기반의 시뮬레이션 엔진을 설계, 구현하였다. 복수의 로봇 시뮬레이션이 정적/동적인 상황에서 이루어 질 수 있도록 이벤트/사이클 혼합 방식을 사용하였다.

• Transactions of the Korean Society of Automotive Engineers
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• v.3 no.2
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• pp.30-41
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• 1995

Gear rattle is a source of vibration and noise in automotive gearbox casing and generally occurs at or near system resonant frequencies. The neutral gear rattle of the gearbox. is affected by the stiffness and hysteresis torque in the clutch disk and drag torque determining balancing point of the clutch disk operating range. The experiment is carried out in the pre-damper type clutch and a manual transmission of a automobile equipped for inline four-sylinder four-cycle 1.5L MPI engine and the computer simulation is executed by 5th order Runge-Kutta method. The results of the simulation analysis and experimental studies show the dynamic behavior of clutch and a phenomenon of the neutral gear rattle with respect to drag torque and torsional characteristics of the clutch.

• Plant Journal
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• v.10 no.2
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• pp.38-47
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• 2014

Renewable Portfolio Standards was introduced into the system in Korea in 2012. Interest in the unutilized and renewable energy sources is increasing. and these being actively investigated. An organic rankine cycle has emerged as an alternative in order to take advantage of bio-gas engine heat of sewage treatment plants whose capacity is 1500 kW. The organic rankine cycle power system was simulated by a simulator which is a commercial program of power plant design and performance analysis. The biogas engine is operated by $460^{\circ}C$ and 2.7 kg/s flow rate in the sewage treatment plant. Working fluids(R-601a, R-123, R-245fa) are selected to use in ORC power system in this temperature range. It was the isopentane that is the best performance among three working fluids. It could be obtained net power of 163.1 kW and efficiency of 13.66% from isopentane in the simulation.