• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.472-479
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• 2006

Recently, various methods have been developed to improve the performance of gas turbines for combined cycle power plants. This paper especially focused on the gas turbine with a reheat process. The purpose of this study is to analyze performance characteristics of a reheat-cycle gas turbine on both a design point and off-design operations. Results of the parametric study of this model show how operating and design parameters influence on the performance of the gas turbine. Moreover, possibilities for the analysis of off-design performance based on a self-generated compressor performance characteristic map are presented.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2005.11a
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• pp.220-223
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• 2005

System design parameters of gas generator cycle liquid rocket engines were investigated and compared in the present study. Characteristic velocity of combustor, pressure drop of combustor injector, exit pressure of pump, pump efficiency and specific power of turbine were considered as a system design parameter. The result shows the characteristic velocity is in the range of 1700-1770 m/s, pressure drop of combustor injector, 4-10 bar, pump exit pressure ratio to combustion pressure, 120-230%, pump efficiency, 60-80%, specific power of turbine, $0.28-0.58MW{\cdot}s/kg$.

• Journal of Advanced Marine Engineering and Technology
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• v.22 no.6
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• pp.792-799
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• 1998

Further improvement of existing $H_{2}O/LiBr$ absorption refrigeration machine is absolutely neces-sary to promote the utilization of gas-cooling system Among various methods to improve the per-formance of the absorption refrigeration machine this research has focused on the use of a new working fluid that has better properties than the existing $H_{2}O/LiBr$ working fluid. In the series of the research, $H_{2}O/LiBr+HO{(CH_{2})}_{3}OH$ system was selected as the most promisable candidate. The absorption refrigeration machine is water-cooled double-effect, $H_{2}O/LiBr+HO{(CH_{2})}_{3}OH$ sys-tem with series flow type. In this study we found out the characteristic of new working solution through the cycle simulation and compared the result with that of LiBr solution to evaluate. Theoptimum designs and operating conditions were determined based on the operating constraints and the coefficient of performance. Results demonstrate that new working fluid subsrantially increases COP by as much as 10% and has a wider working range with 8% higher crystallization limits compared to the conventional $H_{2}O/LiBr$.

• Journal of Korean Society for Atmospheric Environment
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• v.26 no.4
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• pp.403-411
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• 2010

Recently, emission tests for heavy-duty vehicles have been conducted by heavy-duty engine dynamometer. But, it contains weaknesses that present inconveniences to install and uninstall engines and limitations to reflect on practical characteristics for vehicle driving. On the other hand, chassis dynamometer test is able to differentiate characteristics of real driving patterns due to the reason that vehicles can be examined by utilizing chassis dynamometer. This study aimed at comparing the characteristic of emitting regulatory substances of urban buses on Heavy-duty chassis dynamometer. The characteristic was analyzed based on vehicle speed by using both domestic and overseas developed heavy-duty vehicle test modes. As a result, this work attempted to investigate possibilities to take advantage of Heavy-duty vehicle test modes as a method to manage emissions from heavy-duty vehicles.

• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.190-192
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• 2003

Single phase induction motor is used widely in various electronic appliances by advantage that is simple structure and a low-cost. As high starting torque characteristic is mostly used capacitor run single phase induction motor. In this paper, it is applied that speed controller of Capacitor run single phase induction motor of digital way used general microprocessor, and phase control method used average voltage. Torque get non-linearity to domain of low speed. Unstable domain of low speed is applied of integral cycle control. so it is wide that Speed control domain. Also, PID controller is used to improve characteristic of fast response. The validity of proposed method is verified from simulation and experiment result

• Journal of Advanced Marine Engineering and Technology
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• v.18 no.2
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• pp.97-103
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• 1994

This paper describes briefly the simulation program for predicting the performance of a high speed turbocharged four cycle diesel engine. The wave phenomena in the intake and exhaust systems are calculated by the characteristic method. The combustion process in the power cycle is represented by the heat release pattern which is given by the Wiebe's function or the pattern based on measured values. Turbocharger matching for the engine is described by utilizing the characteristic maps of both the compressor and turbine, which are obtained from quasi-steady states. A comparison of experimental and calculated results shows a good agreement. Then the influences of the intake system, the period of valve overlap and the characteristics of the turbine are numerically investigated by the simulation.

• Journal of ILASS-Korea
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• v.4 no.3
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• pp.24-31
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• 1999

The engine performance and combustion characteristics of methanol blended fuel of spark ignition engine were discussed on the basics of experimental investigation. The effects of methanol blending fuel on combustion in cylinder were investigated under various conditions of engine cycle and blending fuel on combustion in cylinder were investigated tinder various conditions of engine cycle and blending ratios. The results showed thai the engine performance was influenced by the methanol blending ratio and the variations of operating conditions test engine. The increase of fuel temperature brought on the improvement of combustion characteristics such as cylinder pressure. the rate of pressure rise and heat release in an engine. The burning rate of fuel-air mixture, the exhaust emissions and the other characteristics of performance were discussed also.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.490-499
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• 1989

These days the closed cycle gas turbine attracts considerable attention due to : (1) The possibility of directly coupling the closed cycle gas turbine with a high temperature gas cooled reactor ; (2) the economical use of dry coolers to reduce the thermal charge of the environment ; and (3) the reduction of pollution and energy consumption, by replacing the domestic hearth by a central heating and power station. In this paper, we selected the optimal cycle from the characteristic of thermodynamic cycle for the optimal design of closed CO$_{2}$ gas turbine cycle usuable in nuclear energy power plant. Also the effects of between the parameters and thermal efficiency were investigated by computer simulation. These results and design data will be added to basics in optimal designing closed CO$_{2}$ cycle gas turbine plant.

• Journal of Korean Society of Transportation
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• v.28 no.3
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• pp.19-28
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• 2010

Almost domestic cycleways have been established without characteristic of land uses. These cycleways can always not provide optimal condition for safety and convenience not to speak of efficiency. This research having a purpose to accomplish more safety and convenience has tried to classify cycleways detail and to analyze cycleways types by land uses. It verified the difference among the characteristic of traffic on the land uses using the Chi-square test, and found the land use that had the strongest characteristic. Finally, it has proposed the suitable cycleway types to land uses.

• Journal of the Korean Society for Heat Treatment
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• v.7 no.3
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• pp.184-189
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• 1994

The heat treatment charaterristic of SCM 440 and B 16 steels has been investigated in various condition(A, B and C) to the effect of heat treatment on mechanical properties, and the following results were obtained. 1. We are obtained a good nitriding characteristic in bainitic structure than other heat treatment cycle in our experiment. 2. Fatigue characteristic has shown in order of B)C)A condition as heat treatment cycle. 3. The effective hardening depth and fatigue characteristic has been excellented in B 16 than SCM 440 after the nitriding and Q. T for Band C condition. 4. Nitriding depth has been increased in addition of Cr, V and the nitriding efficiency is increased as easiness of banite formation to wide range of cooling rate by addition of Mo. 5. The depth of compound layer in parallel surface, notched slop plane and notched bottom has been varied to the nitriding depth of 5, 4 and 3 ${\mu}$ in relatively uniform pattern after 10h nitriding treatment for SCM 440 into A condition.