• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.04b
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• pp.179-182
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• 2004

ZnO varistor for transmission class arrester$({\Phi}65{\times}20mm)$ of 10kA(Class 3) grade was recently developed in korea and is tested for the properties by switching surge operating duty test to know the line discharge class and complex surge property in electric properties. To find out changing rate of residual voltage before and after lightning impulse residual voltage testing, the sample is cool to room temperature after finishing switching surge operating duty test, and the rate is good as 1.0~1.7%. The element had been considered as applicable ZnO varistor for electricity transmission from the test results of state conterl, switching surge operating duty, thermal stability and above test. But various test should be required for actual application because this is a part of the to be needed for application.

• Journal of Korea Society of Industrial Information Systems
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• v.20 no.3
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• pp.11-18
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• 2015

Stress is one of the major causes threatening the mental and physical health of human today. In this paper, we analyzed the heart rate variability(HRV), galvanic skin response(GSR), and skin temperature data measured from the university subjects before and after the class to examine the influence on bio-signal in stress environment. Thirty subjects from university students (aged between 21 and 27 years; mean=22.31, STD=1.45) took part in this study. From the experiment results, RMSSD(p=0.033), LF peak(p=0.003), VLF(p=0.045) were statistically significant from those of the control group(p<0.05) of HRV both in time and frequency domain. We observed that mean skin conductivity after the class(mean=5.993(uS), SD=3.406) is higher than that before the class(mean=3.039(uS), SD=2.628) by 97.2% on average and the skin temperature after the class($34.835{\pm}0.305$) is slightly higher than that before the class($34.471{\pm}0.281$) by 1.055% on average. The results in this research could be used to examine the autonomic response in clinical stress related research.

• Korean Journal of Remote Sensing
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• v.27 no.3
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• pp.289-301
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• 2011

In this paper an attempt has been made to classify Asia land cover considering climatic and vegetative characteristics. The sub-class clustering based on the 13 MODIS land cover classes (except water) over Asia was performed with the climate map and the NOVI derived from SPOT 5 VGT D10 data. The unsupervised classification for the sub-class clustering was performed in each land cover class, and total 74 clusters were determined over the study area. Via these clusters, the annual variations (from 1999 to 2007) of precipitation rate and temperature were analyzed as an example by a simple linear regression model. The various annual variations (negative or positive pattern) were represented for each cluster because of the various climate zones and NOVI annual cycles. Therefore, the detailed land cover map as the classification result by the sub-class clustering in this study can be useful information in modelling works for requiring the detailed climatic and vegetative information as a boundary condition.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.6
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• pp.52-62
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• 2006

The flora of vascular plants around Chunji and Sochunji in Mt. Baekdu was listed 120 taxa; 31 families, 81 genera, 97 species, 1 subspecies, 21 varieties and 1 form. About endangered wild plants, 2 taxa (Paeonia obovata, Rhododendron aureum) are in class II. 12 taxa were listed as rare and endangered plants; Disporum ovale, Lilium davuricum, Saxifraga punctata, Rosa marretii, Cnidium tachiroei, Bupleurum euphorbioides, Halenia corniculata, Gentiana jamesii, Pedicularis verticillata, etc. 10 taxa were listed as Korean endemic plants; Lilium amabile, Aconitum pseudolaeve var. erectum, Oxytropis anertii for. alba, Valeriana officinalis var. latifolia, Cardamine resedifolia var. morii, Homopteryx nakaiana, Saussurea alpicola, Ligularia jamesii, etc. Specific plants by floral region were total 47 taxa; 3 taxa (Paeonia obovata, Rhododendron aureum, Pedicularis verticillata) in class V, 15 taxa (Lycopodium annotinum, Alnus maximowiczii, Saxifraga punctata, Petasites saxatile, etc.) in class IV, 5 taxa (Spiraea salicifolia, Sanguisorba hakusanensis, Acer ukurunduense, Campanula glomerata var. dahurica, Cacalia adenostyloides) in class III, 18 taxa (Lycopodium chinense, Disporum ovale, Ceologlossum viride var. bracteatum, Betula ermani, Aruncus dioicus var. kamtschaticus, Filipendula multijuga, Geranium eriostemon, Cnidium tachiroei, Ligularia stenocephala, etc.) in class II, 6 taxa (Pinus koraiensis, Cimicifuga simplex, Sanguisorba tenuifolia var. alba, Senecio nemorensis, Cacalia hastata subsp. orientalis, Cirsium pendulum) in class I. Peculiar flora around Chunji is thought to be made by the environmental factors such as wind, temperature and rainfall that influence the plants' growth.

• Proceedings of the KIPE Conference
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• 2007.07a
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• pp.271-273
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• 2007

본 논문에서는 TV나 Audio등에 사용되는 2채널 30W급 Class-D amplifier를 동부하이텍의 0.35um BD350BA 공정을 사용하여 디지털 방식의 Class-D amplifier 출력단 구동에 적합하도록 설계하였다. 출력단은 Bootstrap 전원을 사용한 N-N type의 30V LDMOS 내장형이며 각각 $250m{\Omega}$의 턴 온 저항을 갖게 설계 되었다. THD+N 특성개선을 위한 Dead time 및 Delay 조정회로를 내장하였으며 보호회로로는 Over current, Over temperature, UVLO 가 있다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.431-436
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• 2014

In this paper, temperature change properties on the 210kW-class Interior Permanent Magnet Synchronous Motor (IPMSM) are performed with the cooling performance of a water cooling device through the thermal characteristic analysis of the IPMSM considering a real driving pattern of urban railway vehicles. First, the thermal analysis modeling of 210kW-class IPMSM, which is an alternative to the conventional induction motor, and its water cooling device is conducted. Next, the thermal characteristic analysis of the IPMSM considering a real driving pattern of urban railway vehicles is performed using 2-Dimensional FEM tool. Finally, the calculated characteristic results are analyzed. Consequently, it is confirmed that the internal temperature of the 210kW-class IPMSM may be lowered to about 42~52% by maintaining the coolant flow rate of the water cooling device (Cross sectional shape of the pipe has 220mm width and 10mm height) for 0.2kg/s level.

• Progress in Superconductivity and Cryogenics
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• v.7 no.4
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• pp.24-27
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• 2005

Development of a 600 kJ class Superconducting Magnetic Energy Storage (SMES) system is being in progress by Korea Electrotechnology Research Institute(KERI). High temperature superconducting (HTS) wires are going to be used for the windings for the SMES system is presented in this paper. We considered BSCCO-2223 wire for the HTS windings and the operating temperature of the winding was decided to be 20 K which will be accomplished by conduction cooling method using cyro-coolers. Auto-Tuning Niching Genetic Algorithm was adopted for an optimization method of the HTS magnets in the SMES system. The objective function of the optimal process was minimizing total amount of the HTS wire. As a result, we obtained output parameters for optimization design of 600 kJ class SMES under several constrained conditions. These HTS windings are going to be applied to the SMES system whose purpose is stabilization of the power grid.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.63 no.4
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• pp.327-332
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• 2014

In this paper, the temperature distribution according to the property change of the insulating oil of the power transformer and max temperature were predicted through the ductility interpretation which heat-flow is coupled. By using CFD (Computation Fluid Dynamics) for the interpretation, the temperature distribution of 154kV the class single phase power transformer was predicted. The power loss causing the temperature rise of the transformer was changed to the heat source and we used as the input value for the heat-flow analysis. The temperature distribution was predicted according to the change of the density, specific heat, thermal conductivity and viscosity, that is the ingredient having an effect on the temperature rise of the transformer oil. The mineral oil of 4 kinds used in domestic and international based on the interpreted result was selected and the temperature distribution according to each load and Hot Spot temperature was predicted.

• Proceedings of the KWS Conference
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• 2004.05a
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• pp.138-140
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• 2004

In case of applying offshore standard of some class societies, the required impact test temperature is lower than that of class rule to be applied for general commercial ship. This study is performed to consider whether the impact value to be required at offshore standard of BV can be obtained or not under SAW method, 1 run both side welding, to be mainly used for butt joint of plates at domestic ship builder.

• Progress in Superconductivity and Cryogenics
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• v.8 no.2
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• pp.37-42
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• 2006

A research on several characteristics such as volume breakdown and surface discharge of insulators for a termination of power transmission class HTS cable was performed. We investigated the surface discharge of glass fiber reinforced plastic (GFRP) under air, cryogenic nitrogen gas and nitrogen gas media. The breakdown characteristics of these media were studied. Experimental results revealed that flashover voltage greatly depends on pressure, temperature, the kinds of insulating media and voltages, but it is slightly affected by shape and material of electrode. The breakdown voltage of liquid nitrogen, cryogenic nitrogen gas and nitrogen gas deeply depends on the shape and dimension of electrode, kinds of voltages and pressure. Moreover, the breakdown voltage of cryogenic nitrogen gas and flashover voltage of GFRP in the cryogenic nitrogen gas is also influenced by temperature and vapour-mist density of the gas.