• 전력전자학회논문지
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• 제17권2호
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• pp.114-120
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• 2012

Recently, integrated electric propulsion system has been vigorously adopted into naval vessels. To enhance effectiveness and efficiency of power management in these propulsion systems, this paper investigates necessity of energy storage devices and their operation strategies. By introducing the energy storage devices, engine can operate at higher efficiency point and accordingly costs for fuel and maintenance are significantly reduced. In addition, transient performance can also be improved with support of the devices and it leads to stable operation of shipboard power bus. To validate the proposal of this paper, computer simulation has been conducted with real load data of existing electric propulsion system.

• 동력기계공학회지
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• 제9권1호
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• pp.50-56
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• 2005

The corrosion experiment was performed for 120 hours on the specimens in the natural seawater tank with four steps of the loaded torsional stress. The surface corrosion pattern of SCM440 area was showed global corrosion and narrow pitting, that was cause by galvanic corrosion between friction welded IN713LC and SCM440. But corrosion does not proceeded from IN713LC area. Initially, the average relative electrode potential and corrosion current were decreased suddenly, by and large, it was stabilized gradually tend to decreasing with the elapse of the immersion time. The corrosion rate was decreased by increasing the load stress, but 200 MPa specimen was showed most large value.

• 동력기계공학회지
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• 제14권1호
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• pp.11-15
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• 2010

Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions from the diesel engines are recognized as main cause which has a great influence on environment. In this study, the potential of biodiesel fuel and oxygenated fuel(ethylene glycol mono-n-butyl ether; EGBE) was investigated as an effective method of decreasing the smoke emission. The smoke emission of blending fuel(EGBE 0~20 vol-%) was reduced in comparison with diesel fuel and it was reduced approximately 64% at 2000 rpm, full load in the 20% of blending rate. On the contrary NOx emissions from biodiesel fuel and EGBE blended fuel were increased compared with diesel fuel. Torque and brake specific energy consumption(BSEC) didn't have large differences.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1999년도 제30회 추계학술대회
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• pp.318-322
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• 1999

An analytical study about dynamic behavior of center pivot rocker arm type valve train system equipped with roller of diesel engine is developed. At first, a mathematical model for the dynamic analysis has been set up using the lumped parameter method. In that model, valve spring is divided as some mass elemehts so as to simulate spring surging, Then, how the design parameters, such as valve mass, rocker arm inertia, valve spring stiffness, and initial load on valve spring, affect valve dynamic behavior especially in the valve close area is scrutinized.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.105-111
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• 2003

The valve train system of engines has long been a sensitive area with respect to wear performance because of the high contact loads and surface sliding speeds encountered. In particular, wear problems of load-carrying components in relative motion, such as cam and tappet in valve train system have made troubles. To overcome these problems, combination of proper materials is important, as well as selecting of high wear performance materials. This paper presents the experimental result of friction and wear properties of ca/tappet materials. To investigate friction and wear properties for several combinations of materials, using commonplace tribometer(Plint 77, reciprocating type), we make a selection of a optimum material combination.

• 한국자동차공학회논문집
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• 제2권5호
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• pp.30-40
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• 1994

The direct-injection stratified-charge engine has the advantages of higher thermal efficiency and less CO and $NO_x$ emission levels than conventional spark ignition engines. However, its actual utilization is prevented by high unburned hydrocarbon emission levels during light-load operations. In this paper, fundamental studies were carried out using a pancake type constant volume bomb. The effects of intensification of local premixing by tangential and radial fuel injection were examined experimentally. Unburned hydrocarbon emission levels with radial fuel injection were shown to be lower than those of tangential fuel injection cases. The stratification and mixing process of fuel jet and combustion process were observed by schlieren photography.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.347-351
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• 2004

The cryogenic test facility is developed for test of deep groove ball bearings, floating ring seals, materials (steel & copper) for High Pressure Turbopump of liquid rocket engine (LRE). The cryogenic bearing test is performed to evaluate the flow rate of cooling water and the load-carrying capacity of bearings. The cryogenic seal test is performed to evaluate the determination of magnitude of leakages through the seal, a time variation of this magnitude. The test of the materials Pair is performed to evaluate its fitness for operation in the liquid oxygen medium.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.132-139
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• 2004

This study aims to analyze operating performance of a micro gas turbine with the aid of detailed measurements of various system parameters. In addition to embedded measurements, parameters such as exhaust temperatures, engine inlet temperatures and fuel flow rates are measured Variations in measured data and estimated performance parameters are analyzed. Those data are processed to calculate losses along the power transmission line and the net gas turbine performance (power and efficiency based on the gas turbine shaft end) is isolated from the overall system performance. On the basis of the measured data, analytical approach is tried to estimate design characteristic and performance parameters such as component efficiencies and unmeasured temperatures.

• 한국태양에너지학회 논문집
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• 제23권4호
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• pp.11-20
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• 2003

This study aims to develop the program for active solar heating system design & analysis. The program, named ASOLis, is consisted of three user's interface like as system input/output, library, and utilities and used TRNSYS as a calculation engine for the system analysis. ASOLis simplifies user's input data through the database and can design 37 different types of solar systems. Solar system is configurated by two separated parts "solar thermal collecting part" and "load supplying part". Due to the user-friendly layout, all design parameters can be changed quickly and easily for the influence on system efficiency. For the reliability, ASOLis compared with experimental result. As a result, ASOLis is expected to be used as a vital tool for the design and analysis of active solar heating system.

• 소성∙가공
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• 제9권6호
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• pp.644-652
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• 2000

Tube hydroforming is recently drawing attention of automotive industries due to its several advantages over conventional methods. It can produce wide range of products such as subframes, engine cradles, and exhaust manifolds with cheaper production cost by reducing overall number of processes. h successful tube hydroforming depends on the reasonable combination of the internal pressure and axial load at the tube ends. This paper deals with the optimal process design of hydroforming process using the genetic algorithm and neural network. An optimization technique is used in order to minimize the tube thickness variation by determining the optimal loading path in the tube expansion forming and the tube T-shape forming process.