• 한국생산제조학회지
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• 제24권6호
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• pp.653-659
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• 2015

The aim of this study is to develop a technique for the accelerated life test of the capacitor in a propulsion control device of a traction inverter used for a high-speed train. Using this technique, the accelerated life test can possibly estimate the life cycle of a capacitor under various temperature conditions and irregularly applied voltage. The accelerated life test is conducted for the capacitor of the traction inverter. The common proceedings of this test are selection of failure mechanism, determination of accelerated stress, range determination of the accelerated stress, determination of the test condition, and distribution and determination of the sample. From this result, the continuous applied voltage was not considered for the acceleration factors anymore. Therefore, the final result having an acceleration factor of 9.4 (= 13,626/1,445) was observed. Furthermore, the life-shortening acceleration effect for the irregular applied voltage condition can be applied to various situations.

• 항공우주기술
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• 제10권1호
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• pp.1-12
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• 2011

발사체에서 추진제는 발사체 전체 중량의 대부분을 차지하는 것으로 추진제의 탑재량 오차 및 잔류량의 오차는 발사성능에 매우 큰 영향을 미치게 된다. 즉, 발사체의 총추력 오차를 발생시키게 된다. 그러므로 추진제 잔류량을 최소화하는 것이 발사체 성능을 최적화 하는 방법이다. 이에 대한 방법으로 지금까지 연구된 것은 발사체에 능동제어 개념을 도입해서 추진제를 완전 소진시키는 방법과 추진제 잔류량을 최소화하기 위해 확률적인 방법으로 연료의 추가탑재량을 계산하는 방법이 연구되어졌다. 본 연구에서는 한국형 발사체 개발에 본 개념을 적용하여 추진제 잔류량을 최소화하기 위해 탑재해야할 연료 추가탑재량과 그때 남는 추진제 잔류량을 예측해 보았다.

• 대한조선학회 특별논문집
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• 대한조선학회 2007년도 특별논문집
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• pp.89-93
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• 2007

The Boil-off gas (BOG) generation during the voyage is inevitable since Natural Gas (NG) in normally liquefied below -160 degree C in atmosphere condition and small heat ingress due to relatively hot outside keeps evaporating continuously. The one of major issue in LNG carriers is to handle generated BOG from cargo tank. The generated BOG affects to increase the cargo tank pressure and Gas Management System (GMS) for LNG carriers is closely related to cargo tank pressure maintenance. Economically, BOG is generally used as fuel in LNG carrier. Newly developed GMS for LNG carrier in boiler propulsion system, VaCo System, not only accomplish automatic control in GMS but also ensure safer operation.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1227-1232
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• 2008

High-speed train of push-pull type called as G7 train has been developed and chosen as the model of KTX-II which will be operated on Honam Line nexr year. However, the EMU-type high-speed train appeared to be the recent trend that foreign markets have shown. Also, in the near future, a great number of new train sets are needed to accommodate the increased passengers in our country. Thus, development of the high-speed EMU was decided, planned, and started. In the development, included were almost all fundamental key technologies such as noise and vibration reduction in a passenger cabin, running characteristics, aerodynamic analysis, crashworthiness evaluation, EMI/EMC analysis, design of the cooling system for the propulsion control system, enhanced performance of transformer and switching converters, synchronous traction motor with permanent magnets, new design of front nose and ergonomic interiors, application of advanced information technology(IT) and smart sensors and the cost reduction of construction of railway bridges, etc. Each key technologies are carried out as sub-project independently but under the supervision of a project. The project will develop the high advanced level of technologies and provide necessary know-why's and support the team in charge of the development of the high-speed EMU, Hyundai Rotem Co. Ltd. The high-speed EMU will be successfully developed with the support of the project.

• 한국기계가공학회지
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• 제12권6호
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• pp.125-131
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• 2013

This study was carried out to develop a diesel engine for marine propulsion. This marine diesel engine was developed based on a 500Ps vehicle diesel engine. Many main parts, such as the intercooler, radiator, and engine controller were designed for the marine diesel engine. The intercooler was designed to be of sea water cooling type; inlet air is cooled by sea water. Engine coolant is cooled by sea water in the radiator too. The water cooling heat exchanger has high cooling performance. In the cooling system, consists of the intercooler and the radiator, the sea water passes through the intercooler and then the radiator, in sequence. This process is very effective compared to the reverse method in which sea water passes through the radiator and then the intercooler, in sequence. The control performance of the engine controller and the fuel injection rate were improved using an engine speed controller. This system was tested on an engine dynamometer and an exhaust gas analyzer using the marine diesel engine test method. Test results show that the 500Ps marine diesel engine satisfied the IMO NOx regulations; Tier II.

• 항공우주기술
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• 제9권1호
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• pp.125-132
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• 2010

추진제가 배출되는 동안 추진제탱크를 적정 압력으로 유지하기 위해 필요한 가압가스의 질유량 및 총소모량을 파악하는 것은 가압제어시스템의 설계 및 가압제 저장탱크의 무게를 산출하는데 있어 매우 중요하다. 특히 극저온 추진제탱크의 경우 얼리지 내부의 가압가스는 외부와의 열전달에 의해 비체적이 감소하므로 더욱 많은 추진제탱크의 압력을 유지하기 위해 더 많은 가압가스를 필요로 한다. 이에 추진제탱크 얼리지 해석을 위한 기본모델을 만들어 얼리지 내부와 탱크벽면의 온도분포, 가압가스 소모량, 얼리지 내부에서 유입된 가압가스의 에너지 분포를 예측하였다. 현재 시험을 통한 프로그램의 수정보완이 진행되었으나, 본 자료에서는 기본적인 해석모델의 설명에 중점을 두었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제10권6호
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• pp.730-740
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• 2018

Hydrofoil is the direct component to generate thrust for underwater glider. It is significant to improve propulsion efficiency of hydrofoil. This study optimizes the shape of a hydrofoil using Free-Form Deformation (FFD) parametric approach and Surrogate-based Optimization (SBO) algorithm. FFD approach performs a volume outside the hydrofoil and the position changes of control points in the volume parameterize hydrofoil's geometric shape. SBO with adaptive parallel sampling method is regarded as a promising approach for CFD-based optimization. Combination of existing sampling methods is being widely used recently. This paper chooses several well-known methods for combination. Investigations are implemented to figure out how many and which methods should be included and the best combination strategy is provided. As the hydrofoil can be stretched from airfoil, the optimizations are carried out on a 2D airfoil and a 3D hydrofoil, respectively. The lift-drag ratios are compared among optimized and original hydrofoils. Results show that both lift-drag-ratios of optimized hydrofoils improve more than 90%. Besides, this paper preliminarily explores the optimization of hydrofoil with root-tip-ratio. Results show that optimizing 3D hydrofoil directly achieves slightly better results than 2D airfoil.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 1999년도 유체기계 연구개발 발표회 논문집
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• pp.301-308
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• 1999

The present study investigates numerically particle laden flow through compressor cascades and a rocket nozzle. Engines are affected by various particles which are suspending in the atmosphere. Especially in the case of aircraft aviating in volcanic, industrial and desert region including many particles, each components of engine system are damaged severely. That damage modes are erosion of compressor blading and rotor path components, partial or total blockage of cooling passage and engine control system degradation. Numerical prediction and experimental data, erosion rates are predicted for two materials - ceramic, soft metal - on compressor blade surface. Aluminum oxide ($Al_2O_3$) Particles included in solid rocket propelant make ablative the rocket motor nozzle and imped the expansion processes of propulsion. By the definition of particle deposition efficiency, characteristics of particles impaction are considered quantitatively Stoke number is defined over the various particle sizes and particle trajectories are treated by Lagrangian approach. Particle stability is considered by definition of Weber number in rocket nozzle and particle breakup and evaporation is simulated in a rocket nozzle.

• 전력전자학회논문지
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• 제16권4호
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• pp.326-333
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• 2011

본 논문에서는 Plug-in Hybrid Electric Vehicles (PHEVs)의 배터리 충전을 위해 필요한 추가적인 충전기 없이, 구동모터의 인덕턴스와 구동 드라이버인 3상 인버터를 이용하는 배터리 충전 기법들을 소개한다. 모터의 코일을 승압용 에너지 저장장치로 사용하고 인버터 스위치 제어를 통해 부스트 컨버터로 동작되도록 하여 추가적인 충전기를 제거함으로써, 충전장치가 차지하는 부피, 무게 및 단가를 저감할 수 있다. PHEVs의 시스템 구조와 제어기 구성에 따라 분류된 다양한 배터리 충전 기법들을 비교분석하고 시뮬레이션 결과를 통해 검증한다.

• 전기학회논문지
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• 제62권2호
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• pp.288-292
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• 2013

This paper presents the result of life-cycle cost (LCC) estimation for domestic products propulsion control system (motor block unit) of KTX-1 considering periodic maintenance. Life cycle costing is one of the most effective approaches for the cost analysis of long-life systems such as the KTX-1. Life cycle costing includes the cost of concept design, development, manufacture, operation, maintenance and disposal. To estimate LCC for domestic products motor block unit, it was analyzed physical breakdown structure (PBS) on motor unit in view of maintenance cost and unit cost etc. As a results, life cycle cost on motor block unit increased moderately expect for periodical time when major parts are replaced at the same time. hereafter this results will be reflected in the domestic products being developed.