• Journal of the Korean Electrochemical Society
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• v.13 no.3
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• pp.169-174
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• 2010

Sulfur cathodes were prepared by ball milling method with different types of electronic conductors and binders in different ball milling time. The sulfur cell with a cathode prepared in 45 min ball milling time gave an initial discharge capacity of 794mAh/g with Super-P as an electronic conductor and poly(vinylidene fluoride) as a binder. The cathode with multi-walled carbon nanotube as an electronic conductor showed an initial discharge capacity of 944 mAh/g and a discharge capacity of 300 mAh/g after 20 cycles. Cathodes with poly(ethylene oxide) and poly(vinylidene fluoride) as binders showed different cycle performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.05a
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• pp.168-171
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• 2002

In this study. a solid-state laser system adopting a sequential discharge method in which three flashlamps are turned on sequently was designed and fabricated to examine the pulse width and the pulse shape of the laser beams depending upon the changes in the lamp turn-on time. That is, this study shows a technology that makes it possible to make various pulse shapes by turning on three flashlamps sequently with the aid of a PIC one-chip microprocessor. With this technique, the lamp turn-on delay time can be varied more diversely from a to lamp and the real-time control is possible with an external keyboard, enabling various pulse shapes. In addition, longer pulses can be more widely used for industrial processing and lots of medical purposes.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.1
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• pp.9-20
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• 2019

The primary objective of this study was to analyze the delivery ratio using Hydrological Simulation Program - Fortran (HSPF) in Okdong-cheon watershed. Model parameters related to hydrology and water quality were calibrated and validated by comparing model predictions with the 8-day interval filed data collected for ten years from the Korea Ministry of Environment. The results indicated that hydrology and water quality parameters appeared to be reasonably comparable to the field data. The pollutant delivery loads of the watershed in 2015 were simulated using the HSPF model. The delivery ratios of each subwatershed were also estimated by the simple ratio calculation of pollutant discharge load and pollutant delivery load. Coefficients of the regression equation between the delivery ratio and specific discharge were also computed using the delivery ratio. Based on the results, multiple regression analysis was performed using the discharge and the physical characteristics of the subwatershed such as the area. The equation of delivery ratio derived in this study is only for the Okdong-cheon watershed, so the larger studies are needed to apply the findings to other watersheds.

• International Journal of Air-Conditioning and Refrigeration
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• v.15 no.3
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• pp.101-107
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• 2007

Indoor air quality becomes of a concern recently in view of human health. This study investigates the air diffusion performance and the air change efficiency of a classroom, when outdoor air is introduced in two different ways in addition to the heating/cooling operation of a ceiling-mounted heat pump. A CFD analysis has been performed to investigate the effect of the discharge angle of the air jets from the heat pump for both parallel and series types of outdoor air system. It is observed that the series type creates more uniform indoor environment compared to the parallel type in general. It can be concluded the discharge angle should not be larger than 40o for the parallel type, in order not to generate thermal stratification in the room.

• Progress in Superconductivity and Cryogenics
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• v.4 no.1
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• pp.105-109
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• 2002

The short-term AC breakdown strength of laminated polypropylene insulating Paper (PPLP) has been studied for cold dielectric of high temperature superconductivity power cables. The design and operating conditions of the electrode system for studying of short-term breakdown strength of one-layer and multi-layer PPLP samples are discussed in liquid nitrogen(LN2) state. The influence of various operating factors (geometry and dimension of electrodes, speed of tested voltage, thickness of test sample) on the value of short-term AC breakdown strength at cryogenic temperature has been established.

• Proceedings of the KIEE Conference
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• 2015.07a
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• pp.1160-1161
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• 2015

In order to analyze and diagnosis on Location of partial discharge in underground distribution cable, partial discharges were measured using eletromagnetic sensors, oscilloscope, PDMS system at on-site underground multi-circuit switches. Throughout the analysis using 3-phase simultaneous pulse analysis and pulse polarity comparison of circuits, it is possible to separate noises and PD pulses and to find out the location of the pulses.

• Proceedings of the KIPE Conference
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• 2006.06a
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• pp.413-416
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• 2006

The power source of an AC-PDP fur sustainer circuit is operated in high-voltage and high frequency switching during the process required to achieve the gas discharge current to generate light in a PDP panel. Since PDP has the characteristics of a pure capacitive load, the displacement current that occurs during charge and discharge generates considerable reactive power. An auxiliary circuitry called Energy Recovery Circuit (ERC) reduces the capacitive displacement current. However, this auxiliary topology also bears high stress in its components. In this paper, a multilevel voltage wave shaping sustainer circuit with auxiliary ERC characteristics for an AC-PDP driver is proposed. A comparative analysis and experimental results are presented.

• The KSFM Journal of Fluid Machinery
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• v.8 no.6 s.33
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• pp.33-39
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• 2005

A thermal vapor compressor in which the subsonic/supersonic flow appears simultaneously, has been accurately designed through the CFD analysis for the various shape parameters such as the primary nozzle shape, converging duct shape, mixing tube diameter, and so on. The performance of the developed thermal vapor compressor has been experimentally verified to be installed in a Multi Effect Desalination(MED) plant as an important element. In this paper, the effects of each parameter are discussed on the basis of CFD results and the experimental results for various boundary conditions(motive pressure, suction pressure, and discharge pressure) are presented in compared with CFD results. The two results show a good agreement with each other within 2 % accuracy with regard to the entrainment ratio.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.05b
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• pp.115-119
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• 2004

This paper is investigated about the effect of vibration of the water surface for hydrogen gas generation by non-thermal plasma. The vibration of the water surface is more powerful with increasing applied voltage. In this experimental reactor which is made of multi-needle and plate, the maximum acquired hydrogen production rate is about 6.8[ml/sec]. Although the generation of hydrogen gas is increased with elevating time, it is saturated after specific time due to the volume of reactor and the saturation of taylor cone.

• Proceedings of the KSRS Conference
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• 2002.10a
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• pp.454-459
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• 2002

We have developed a new method to visualize river networks in tropical rain forests from JERS-1 SAR images. This method compresses river information in an original SAR image to a small image displaying wide rivers as dark objects in real size and narrower rivers as bright objects showing brightness level as an indicator of the discharge. We applied this method to 476 images of Amazon forests, 13 observations for path 415 data and 11 observations for path 416 data between 1993 and 1997. We confirmed that a change observed in a preliminary experiment was certainly a part of seasonal changes. The changes roughly correspond to the monthly precipitation changes. Through a simple digital analysis although qualitative, we also detected subtle but consistent regional differences among minor tributaries that belong to a major tributary basin.