• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.59-62
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• 1992

Power system fault transient signals are highly distorted due to the presence of high frequency components in the voltage and current signals and an exponentially decaying dc-offset component in the current signals. Modern protective relays have to make reliable fast decisions about the nature of a fault in the presence of such transients. To use a dc-offset removing filter makes relay algorithms much fast and reliable for detecting a fault. In this paper, several dc-offset removing filters are described, and characteristics of them are compared.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.719-723
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• 2002

The purpose of this study is to suggest the correlation of single-number ratings for sound insulation by floor impact. As a assessment method of impact sound insulation. we selected the IIC contour of ISO, A weighted sound level. Inverse A-weighting curve and L-Index of japanese industrial standard. And we estimated the single-number ratings by application the measured data of impact sound level to each method. The results showed that the coefficients of determination between each two single-number ratings were very high (more than 0.9169). And In the condition of same assessment method, the coefficient of determination for light-weight impact sound was higher than that for heavy-weight impact sound.

• The Korean Journal of Food And Nutrition
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• v.21 no.2
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• pp.143-147
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• 2008

To develop a new anti-wrinkle agent from medicinal plants, this study investigated the optimal conditions for extracting elastase inhibitor from Rheum undulatum L. Maximal extraction occurred by using 70% methanol at $50^{\circ}C$ for 24 hr; the elastase inhibitory activity was 60.4%($IC_{50}:6.7{\times}10^3{\mu}g/m{\ell}$). Systematic solvent extraction, thin layer chromatography, silica gel column chromatography, Sephadex LH-20 column chromatography, and reverse-phase high performance liquid chromatography were used in the partial purification of the elastase inhibitor. The compound was soluble in dimethylsulfoxide, methanol, and ethanol, and had maximum absorption spectra at 231.5 nm and 275.5 nm.

• Korean Journal of Plant Taxonomy
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• v.38 no.1
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• pp.17-29
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• 2008

Phylogenetic relationships were examined for 17 taxa of Lycoris by RAPD analysis. The length of the amplified DNA fragments ranged from 300 bp to 1,700 bp. 57 scorable RAPD markers were observed from PCR reactions with five random oligoprimers. The analysis by UPGMA sepatated the examined taxa of Lycoris into were clusters. First group was comprised of ten taxa of L. chinensis var. sinuolata, L. sanguinea var. koreana, L. uydoensis, L. flavescens, L. radiata var. pumila, L. radiata, L. squamigera, L. chejuensis, L. aurea and L. guangxiensis, second group of L. haywardii, L. sprengeri, L. rosea, L. straminea and L. houdyshii, third group of outgroup of Narcissus tazetta var. chinensis and Crinum asiaticum var. japonicum. From the viewpoint of cytological characters such as polyploidy and karyotype, the RAPD analysis was very useful to show the relationship among the intraspecific taxa of Lycoris.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1249-1255
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• 2008

1530nm band has been studied as pump wavelength for long-wavelength-band erbium-doped fiber amplifier (L-band EDFA). The pump source is built using a tunable light source and cascaded conventional-band (C-band) EDFA. The L-band EDFA uses a forward pumping scheme. Within the 1530nm band, 1545nm pump demonstrates 0.45dB/mW gain coefficient, which is twice better than that of conventional 1480nm pumped EDFA. The noise figure of 1530nm pump is at worst 6.36dB, which is 0.75dB higher than that of 1480nm pumped EDFA. Such high gain coefficient indicates that the L-band EDFA consumes low power.

• Journal of Animal Environmental Science
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• v.8 no.3
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• pp.135-144
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• 2002

A computer simulation was carried out to investigate the optimum capacity of liquid manure tank spreader which is used as a tractor attachment. Soil physical properties, such as soil moisture content, bulk density, soil hardness and soil types were measured in the 10 major rice production area for computer simulation. Mathematical model which include soil physical properties and vehicle factor was used for computer simulation. Most of the soil type of the investigated area was sandy clay loam. Soil moisture content ranged between 30 and 40% mostly. Soil bulk density was in the range of 1,500 to 1,700 kg/$m^3$. Soil hardness ranged between 1 to 18 $cm^2$. Soil hardness incorporate the effects of many soil physical properties such as soil moisture content, soil type and soil bulk density, and so the range of soil hardness is greater than any other physical properties. The capacity of liquid manure tank spreader was above 3,000 kg$_{f}$ for the most of the investigated areas, and mostly in the range of 4,000 to 6,000 $kg_f$ depending upon the slip. But for the soft soil area such as Andong and Asan, the tractor itself has mobility problem and shows no pulling force for some places. For this area, the capacity of liquid manure tank spreader ranged between 1,000 and 2,000 $kg_f$ mostly, so the capacity of liquid manure tank spreader should be designed as a small capacity trailer compared to the other area.mpared to the other area.

• The Korean Journal of Malacology
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• v.11 no.1
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• pp.1-20
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• 1995

1993년 7월부터 1994년 5월까지 제주도 차귀도 4개 지점 조간대의 대형저서무척추동물의 분포와 군집구조에 관한 연구결과는 다음과 같다. 1. 차귀도 조간대에 분포하는 대형무척추동물은 총 9문, 17강, 35목, 75과, 146종이었다.2. 계절별 출현종수는 춘계에 124종, 하계 113종, 추계 99종, 동계에 86종이었다.3. 조간대 상부구역의 제1우점종은 좁쌀무늬총알고둥(N. exigua), 제2우점은 거북선(P. mitalla). (N.japonica),울타리고둥(M. labio), 중부구역은 배무래기(N. schrenkii), 밤고둥(C. argyrostoma lischkei), 울타리고둥, 깜장각시고둥(M. perplexa), 검은따개비(T. squamosa japonica)가 지점에 따라 제1, 제2우점종을 이루었다. 하부구역은 밤고둥, 검은따개비, 줄군부 (L. coreanica), 거북손, 굵은줄격판담치(S. virgatus)가 지점에 따라 우점하였으며, 상부구역 우점종의 군집우점지수는 매우 높았다.4. 조간대 하부구역의 종다양성은 상부구역이나 중부구역에 비하여 컸고 계절별 출현종수에 유의성이 있었으나 상부구역이나 중부구역에는 없었다.5. 종다양도지수와 균등도에는 상. 중. 하 구역별유의성은 없었고 풍부도에서는 상부구역에서 유의하였다.6. 제주 미기록종으로 부채넓적이끼벌레(D. su-bovoidea), 딱지조개(P. japonica), 목주림고둥(T. guerinii), 전촉수갯지렁이(A. validus), 바다거미(L. hilgendorfi)가 채집되었다.

• The Korean Journal of Applied Statistics
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• v.4 no.2
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• pp.157-170
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• 1991

This article is concerned with the goodness - of - fit test for exponentiality when both the scale and location parameters are unknown. A test procedure based on the $L_1$-norm of discrepancy between the cumulative distribution function and the empirical distribution function is proposed, and the critical values of the test statistic are obtained by Monte Carlo simulations. Also the null distributions of the proposed test statistic are presented for small sample sizes. The power of tests under certain alternative distributions is investigated to compare the proposed test statistic with the well-known EDF test statistics. Our Monte Carlo power studies reveal that the proposed test statistic has good power properties, for moderate-to-large sample sizes, in comparison to other statistics although it is a conservative test.

• Journal of Korean Society of Water and Wastewater
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• v.32 no.2
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• pp.183-192
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• 2018

Applicability of corrosion inhibitor was evaluated using pilot scale water distribution pipe simulator. Calcium hydroxide was used as corrosion inhibitor and the corrosion indices of the water were investigated. Corrosion indices, Langelier saturation index (LI) increased by 0.8 and calcium carbonate precipitation potential (CCPP) increased by 9.8 mg/L. This indicated that corrosivity of water decreased by corrosion inhibitor and the effects lasted for 18 days. Optimum calcium hydroxide dose was found to be 3~5 mg/L for corrosion inhibition. We suggest that monitoring of CCPP as well as LI need to be conducted to control corrosivity of water.

• The Korean Journal of Applied Statistics
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• v.6 no.2
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• pp.289-302
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• 1993

A goodness-of-fit test for the two-parameter exponential distribution, for use with the singly Type I and Type II right censored samples, is proposed. The test statistic is based on the $L_1$-norm of discrepancy between the cumulative distribution function and the empirical distribution function. To deal with the unknown parameters problem, the K- transformation is considered and modified to be applied to the censored samples. Rosenblatt's transformation is extended to the cases of Type I and Type II censored samples, in order to transform the censored samples into the complete ones. The critial values of the test statistic are obtained by Monte Carlo simulations for some finite sample sizes. The power studies are conducted to compare the proposed test with the Pettitt(1977) test for exponentiality with censored samples. It appears that the proposed test has relatively good power properties for moderate and large sample sizes.