• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2000.11a
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• pp.179-182
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• 2000

This paper investigates characteristics of spiral charge for charge simulation method to calculate electric fields of spiral conductor bundles with spiral rods in 765 kV transmission line. We finds the simulating spiral charge as constant charge density give less potential calculation error than sinusoidal charge density. When a spiral rod is simulated as spiral charge, we also knows two spiral charge can simulate spiral rod best.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.15-16
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• 2005

In this study, the characteristics of NOx reduction by using charge air moisturizer system were evaluated by engine performance simulation in medium speed diesel engines. The results of performance simulation were verified by experimental results of single cylinder medium speed diesel engine equipped with charge air moisturizer system. Performance simulation was carried out to evaluate charge air moisturizer system of turbocharged diesel engine, HYUNDAI HiMSEN 9H25/33 engine. Those results show 50% NOx reduction at dew point $80^{\circ}C$ and charge air pressure 4bar.

• Journal of Korean Elementary Science Education
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• v.34 no.4
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• pp.357-371
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• 2015

Even after learning electric current, elementary school students have various non-scientific conceptions and difficulties. Because flow of charge is not visible. Also elementary school students do not learn theory but phenomena, so they cannot transfer theoretical perspective to new situation. In this research, we have designed instruction based on PhET simulation visualizing flow of electric charge and applied it to 37 science-gifted students in elementary school for measuring conceptual understanding. As a result, six out of the seven Hake gains of question set are high gain and just one is middle gain because the students have understood the flow pattern of the charge through circuit elements such as light bulbs, wire, as well as battery with PhET simulation and it gives a chance to create various questions spontaneously about electric current. Also they become able to do spontaneous mental simulation without PhET simulation about flow of charges. This research, suggest that developed materials using PhET simulation could be used as not only program for gifted students in elementary school, but also the electrical circuit section in an elementary science curriculum.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.3
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• pp.378-387
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• 2009

The shaped charge consists of the cast or pressed explosive and the metal liner. The pressure formed in detonation wave is so high that the liner is collapsed and the jet of high temperature, pressure and velocity is produced. The jet penetrates the target. In this paper, the simulation for optimization of flexible linear shaped charge(FLSC) was carried out by AUTODYNE program. Based on the results of simulation, we made a prototype of FLSC and evaluated penetration performance, flexibility and its application. The test result of prototype was compared with that of simulation.

• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.233-236
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• 2006

A 3-D numerical simulation of a buried-channel CCD (Charge Coupled Device) with a deep depletion has been performed to investigate its electrical and physical behaviors. Results are presented for a deep depletion CCD (EEV CCD12; JET-X CCD) fabricated on a high-resistivity $(1.5k\Omega-cm)\;65{\mu}m$ thick epi-layer, on a $550{\mu}m$ thick p+ substrate, which is optimized for X-ray detection. Accurate predictions of the Potential minimum and barrier height of a CCD Pixel as a function of mobile electrons are found to give good charge transfer. The depletion depth approximation as a function of gate and substrate bias voltage provided average errors of less than 6%, compared with the results estimated from X-ray detection efficiency measurements. The result obtained from the transient simulation of signal charge movement is also presented based on 3-Dimensional analysis.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.4
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• pp.31-36
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• 2001

This paper investigates characteristics of spiral charge for 3 dimensional charge simulation method to calculate electric fields of special conductor bundles with spiral rods in 765kV transmission line. We finds the simulating spiral charge as constant charge density give less potential calculation error than sinusoidal charge falsity. When a spiral rod is simulated as spiral charge, we also knows two spiral charge can simulate spiral rod best.

• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.290-292
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• 1994

This paper presents a methodology for the electric field analysis of substation. For the electric field analysis of substation, the electrodes(substation busbars) must be represented by finite line with nonlinear charge density. In the case of dividing finite line into uniform segments, a large number of variables have to be used to obtain the accuracy within a desired tolerance. To deal with the problem, nonuniform charge arrangement modeling method is suggested. To reduce potential calculation errors, the linear charge density function is considered particularly for the segment charge model ling. If the charge arrangement is improper, the accuracy not improved regardless of increment in the number of segments. This paper proposes an optimal charge arrangement method through potential error analysis. And, the optimal charge arrangement function is formulated by a lot of simulation results.

• Journal of Energy Engineering
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• v.24 no.3
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• pp.61-66
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• 2015

Homogeneous charge compression ignition (HCCI) engine combines the combustion characteristics of a compression ignition engine and a spark ignition engine. HCCI engines take advantage of the high compression ratio and heat release rate and thus exhibit high efficiency found in compression ignition engines. In modern research, simulation has be come a powerful tool as it saves time and also economical when compared to experimental study. Engine simulation has been developed to predict the performance of a homogeneous charge compression ignition engine. The effects of compression ratio, cylinder pressure, rate of pressure rise, flame temperature, rate of heat release, and mass fraction burned were simulated. The simulation and analysis show several meaningful results. The objective of the present study is to develop a combustion characteristics model for a homogeneous charge compression ignition engine running with isooctane as a fuel and effect of compression ratio.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.5
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• pp.387-396
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• 2009

The life and performance of lithium battery are greatly influenced by the formation process which is essential in the process of manufacture. Charge/discharge system for the lithium battery are required for the formation process. To simulate such a system in a conventional method takes very long time and requires huge memory space to save data files. So the simulation may be impossible with a general-purpose PC. In this paper, the lithium battery is modelled to a resistor-capacitor serial circuit and the lithium battery charge/discharge system is analyzed and simulated by using state space averaging method. As a result, the simulation time is reduced dramatically and the simulation of the lithium battery charge/discharge system becomes possible on a general-purpose PC within 3 hours. Also, both the charge/discharge characteristics and the time required to charge/discharge of the lithium battery charge/discharge system can be observed. To verify the propriety of resistor-capacitor serial circuit modeling method for lithium battery and the validity of the analysis and simulation based on state space averaging, the lithium battery charge/discharge system is composed and experimentations are carried out.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.5
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• pp.486-493
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• 2000

A theoretical model for the transient performance of vapor-compression air-conditioning system has been developed to evaluate the influence of the refrigerant charge on the system performance. A set of mass and energy equations for the simulation of the heat exchangers and the capillary tube and a polytropic compression model for the compressor are used. The present model successfully predicts the transient behavior of the vapor-compression air-conditioner from the startup. As the refrigerant charge is increased, both the evaporating and condensing pressures increase gradually, and the cooling rate and the COP show a maximum in the range of 0.75-0.8 kg of refrigerant charge. This amount of refrigerant mass is determined to be the optimum charge of the model system. Also, the effect of outdoor air temperature on the optimum refrigerant charge is discussed.