• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.86-87
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• 2005

The combustion characteristics of the D.I. diesel engine are largely dependent on the air-fuel ratio and the gas exchange process. The main factors are the shape of combustion chamber, fuel injection system, air flow inside the cylinder, intake air mass flow rate and so forth. Because these factors affect the combustion in a mutual and combined manner, it is very important to clearly understand the correlation of these factors in order to provide the combustion improvement plans. In this paper, we studied the performance and the gas exchange process of marine four-stroke engine using the engine cycle simulation. Also, we predicted briefly turbocharger engine matching.

• Journal of Advanced Marine Engineering and Technology
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• 제13권3호
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• pp.64-71
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• 1989

In this paper, a computer program for simulation of 4 cycle diesel engines including intake and exhaust manifold system is developed. The wave action theory is applied for optimization of the intake and exhaust manifold system. The calculation results of this computer program is finely accurate and agreed well with experimental results. Accordingly, it is recognized that the developed computer program can be utillized very usefully for the design of intake and manifold system. And then, influential factors of the engine performance in the design of intake manifold is numerically investigated by the calculation only. As the results it is concluded that the inertia one of the dynamic effects on the intake and exhaust maninfold affects mainly the engine performance and the pulsation one is a side effect.

• 연구논문집
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• 통권25호
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• pp.77-90
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• 1995

For improving performance of heat pump system, researcher has adapted 2-stage economizer cycle and developed a high-efficiency screw compressor, new working medium(non-azeotropic mixed refrigerant) and counterflow heat exchangers operating with a small temperature difference. Target of this study is development of high performance heat pump system with the 2-stage economizer system using the non-azeotropic mixed refrigerant. For the purpose of excuting target, we constucted computer simulation programs, compared and examed various types of cycle and non-azeotropic mixture. Based on the results from computer simulation we selected optimum mixtures and reflected design and production process of performance test equipment with the 1-stage econmizer system. In order to accomplish the final target, design and production of the 2-stage economizer system, we performed pilot test using the 1-stage economizer performance test system and finally design and production of the 2-stage economizer system.

• Journal of Mechanical Science and Technology
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• 제14권5호
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• pp.569-581
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• 2000

A cycle simulation program is developed and its predictions are compared with the test bed measurements of a direct injection (DI) diesel engine. It is based on the mass and energy conservation equations with phenomenological models for diesel combustion. Two modeling approaches for combustion have been tested; a multi-zone model by Hiroyasu et al (1976) and the other one coupled with an in-cylinder flow model. The results of the two combustion models are compared with the measured imep, pressure trace and NOx and soot emissions over a range of the engine loads and speeds. A parametric study is performed for the fuel injection timing and pressure, the swirl ratio, and the squish area. The calculation results agree with the measured data, and with intuitive understanding of the general operating characteristics of a DI diesel engine.

• 한국자동차공학회논문집
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• 제4권4호
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• pp.58-71
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• 1996

A model which calculates the hydrocarbon emissions from spark ignition engines is presented The model contains the formation of HC emissions due to both crevices around piston ring top land and oil films on the cylinder wall. The model also considers in-cylinder oxidation and exhaust port oxidation of desorbed HC from crevices and oil films after combustion process. The HC emissions model utilizes the results of SI engine cycle simulation. The model predicts well the trends of HC emissions from the engines when varying engine parameters.

• 오토저널
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• 제8권2호
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• pp.31-42
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• 1986

The prediction of performance, exhaust emissions and EGR effect is made by the SI engine cycle simulation. In this simulation several models are employed - two zome, thermodynamic combustion, mass fraction burned, heat transfer, chemical equilibrium, chemical kinetics for NOx, laminar flame speed for ignition delay. The chemical species in burned gas considered are 13 species-CO$_{2}$, CO, $O_{2}$, H$_{2}$O, H$_{2}$,OH, H, O, N$_{2}$, NO$_{2}$, N, Ar - and the cylinder pressure, burned and unburned zone temperature and composition of gas are calculated at each crank angle through the compression, ignition delay, combustion and expansion process. To check the validity of the model, experimental study is done for measuring emissions, combustion pressure and engine output. The predicted values for pressure and emissions show qualitative agreement with the measured data and the EGR effect also shows similar tendency.

• 한국태양에너지학회 논문집
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• 제23권4호
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• pp.63-70
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• 2003

It is very important to improve the insulation performance of curtain wall anchoring unit since it is composed of materials with high thermal conductivity, such as aluminium, steel and so on. This study aims to evaluate the heating energy performance and economical efficiency of various alternatives which are different in position and material of insulation. As results, alternative of inserting the urethane washer & pad and coating the anchoring unit with urethane foam can improve the heating energy performance and L.C.C(Life Cycle Cost) by 6.33% and 0.95%, respectively, as compared with the existing case.

• Journal of Welding and Joining
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• 제12권2호
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• pp.76-86
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• 1994

Spot welding behavior of galvanized steel has been studied using both numerical and experimental techniques. The model that used to calculate temperature distribution within weldment is two-dimensional axis-symmetric finite difference method, and nugget sizes of specimen welded in condition of welding current and time has been estimated by experiment Results have shown that nugget sizes are increased in proportion to welding current and time, but the growth rate of nugget is decreased. Shear-tensile strength tests have shown interface fracture when welding current is 7, 9KA, welding time is 8-14cycle and 11KA, 8-10cycle respectively, but above 7, 9KA fracture shows button type. In button fracture, shear-tensile strengths have been proportional to nugget sizes.

• Industrial Engineering and Management Systems
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• 제9권1호
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• pp.28-40
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• 2010

One of the most important objectives of the schedules in a container terminal is to minimize the ship operation time, which consists of discharging and loading operation times. Recently, dual cycling techniques have been used for improving terminal operations, especially for reducing the total empty trips of handling equipment. The main focus of this study is to reduce the empty trip times of yard trucks with minimum delays for ship operations. A heuristic algorithm, modified from a previous algorithm, is proposed to solve this problem. A simulation study is conducted to evaluate the effect of different types of discharging and loading schedules and different locating methods for discharging containers in terms of the performance of the system, including the percentage of the dual cycle operations of yard trucks.

• 한국자동차공학회논문집
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• 제15권1호
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• pp.133-138
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• 2007

The balance shaft housing in the recent engines tends to have the high cycle fatigue crack caused by increased engine power. In this paper, a CAE procedure is introduced to predict the durability of the balance shaft housing. The procedure is performed through two analysis steps. In the first step, the multibody dynamic simulation is used to obtain more accurate loading boundary conditions applied to the finite element model for the following step. Next, the finite element analysis is performed to predict the durability of the balance shaft housing through the calculation of the safety factor. Through this CAE procedure, the revised balance shaft housing was developed to improve the durability. And the durability of the housing was confirmed experimentally.