• Proceedings of the KSME Conference
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• 2000.04b
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• pp.240-245
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• 2000

In this study, thickness, density and effective thermal conductivity of frost forming on the horizontal cylinder were measured with various air temperature and humidity. Reynolds number and temperature of cooling surface are controlled 17300 and $-l5^{\circ}C$ respectively. In each case of air temperature $5^{\circ}C,\;10^{\circ}C,\;15^{\circ}C,$ varying absolute humidity, experiments were executed. In measuring frost surface temperature and thickness of frost layer, infrared thermocouples and CCD camera were used. Frost was gathered from cylinder to measure mass of frost layer. Experimental data showed that the thickness and effective thermal conductivity of the frost layer increase with respect to time. Thickness of frost layer increase with humidity increasing, and density of frost layer increase with air temperature rising. Frost growth with air temperature and density of frost layer with humidity are affected by whether dew point is below or above freezing point.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1533-1535
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• 1994

The Monte-Carlo simulation was used to define the physical mechanisms of the initiation phase of pseudo-spark discharge. The pseudo-spark discharge employing the hollow cathode geometry is accompanied by very fast current rising and intense charged particle beams. In this model, time-dependent continuity equation for the electrons and ions were solved consistently with Poisson's equation for the electric field in a two-dimensional, sysmmetrically cylinderical geometry. From the simulation, a sequence of physical mechanisms that cause the rapid current rise associated with the onset of pseudo-spark discharge mode were identified.

• Journal of the Korean Institute of Intelligent Systems
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• v.4 no.1
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• pp.35-49
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• 1994

It is well known that, for nominimum phase systems, a conventional linear controller of PID type or an adaptive controller of this structure shows limitation in achieving a satisfactory performance under tight specifications. In this paper, we combine a neuro-controller with a PI-controller with off-line learning capability provided by the Genetic Algorithm to propose a novel neuro-controller to control nonminimum phase systems effectively. The simulation results show that our proposed model is more efficient with faster rising time and less undershoot effect when the performances of the proposed controller and a conventional form are compared.

• International Journal of Naval Architecture and Ocean Engineering
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• v.1 no.2
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• pp.57-63
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• 2009

Numerical simulations have been carried out on the flooding system of a dry located at the south coasts of Iran. The main goals of seawater flow haracteristics in the intake channels conditions of the flooding system are imposed in the modeling. The upstream boundary condition is the tidal fluctuations of sea water level. At the downstream, the gradually rising water surface elevation in the dry described in a transient boundary condition. The numerical results are compared with available laboratory a good agreement is obtained. The seawater discharge through the flooding system and the required time to filling up the dry dock is determined at the worst case. The water current velocity and pressure on the rigid boundaries are discussed.

• Journal of Life Science
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• v.10 no.2
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• pp.33-38
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• 2000

Maekmoondong-Tang is prescription recorded on Zang‘s ${ulcorner}$Synopsis of the Golden Chamber${\lrcorner}$ for the first time. It can be used in abnormal rising of qi, asthma, swelling throat ect. So it is observed influence of Maekmoondong-Tang on respiratory aspect of allergic asthma patient, we have significant result and report it. We used egg-white and ovalbmuin (OVA) to induce asthma in experimental animals for observe what maekmoondong-Tang have an effect on asthma. And it is observed respiratory aspect and obtained next conclusions. 1. Number of total respiration in group that is prescribed Maekmoondong-Tang slightly increased than in control group. 2. Number of abnormal respiration in group that is prescribed Maekmoondong-Tang decreased than in control group significantly.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.52 no.9
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• pp.383-387
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• 2003

In this paper, we have studied about optimal transmission efficiency characteristics of pulse energy in a coal plant for removing environmental polluted gas. The electrical efficiency of pulse power systems depends on impedance of the reactor. To obtain high efficiency, we used MPC(Magnetic pulse compressor) as the power switch and tested their characteristics as electrode length of the reactor and charging voltage of capacitor, As results, we obtained a compressed pulse such as pulse voltage of 10㎸, rising time 200ns and pulse width of 500ns. With increasing electrode length, the load impedance was decreased but the electrical efficiency was increased.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.1
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• pp.93-99
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• 2009

In this paper, transient voltage response of Polmer Electrolyte Membrane Fuel Cell (PEMFC) stack is analyzed and voltage dynamic characteristic is modeled for optimal design of power conditioning system (PCS). According that the load is changed, the corresponding operating voltage of fuel cell stack is also varied with a certain deep and rising time due to the chemical and mechanical responses. This transient behavior can affect on the operation with respect of PI gain in controller, duty ratio, capacitor of capacitor and so on. So in this paper the detailed theoretical analysis of transient voltage dynamics is explained and the methodology of dynamic modeling is introduced. In addition, the validity and feasibility of the proposed dynamic model is verified by experimental results under various load conditions.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2008.05a
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• pp.297-300
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• 2008

This paper presents the behaviors of transient and conventional grounding impedances of a deep-driven ground rods associated with the injection point of lightning impulse currents. The transient impedance of deep-driven ground rods under lightning impulse currents were higher than the static ground resistance. The transient grounding impedances strongly depend on the injection point and size of grounding electrodes and the rising time of impulse current. Reduction of ground system inductance is an important factor to lightning surge protection.

• Management & Information Systems Review
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• v.21
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• pp.1-27
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• 2007

government is rising interest about CRM gradually. At this of time presenting visible effect, this study grasped success factors through the concept arrangement and the existing literature about CRM. The capacity of CRM and the result of CRM (interest of local department which is a variable, a specialty manpower, business cooperation between department, evaluation and compensation, system integration level that is special variable, possibility of system extension, ease of system use) analyzed to local government employee how affects through actual proof analysis.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1172-1179
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• 2010

Since HEMP has the very short rising time and propagates widespreadly with several tens of kV/m, it threatens most of systems in its cover range. Therefore, it is important to research coupling mechanism into systems and establish countermeasures for the HEMP to protect systems effectively. This paper analyzed characteristics and trends of currents to be induced at the load of a line which is located over ground with different conditions such as polarization, incidence angle, line length and height etc. We applied double exponential waveform as the HEMP shape and used BLT method to analyze the coupling route into the line. Also, we compared the simulation data of chain matrix modeling to verify reliability of BLT modeling. In the result, two data is almost agreed.