• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.3
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• pp.284-291
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• 1997

A hydrogen liquefaction equipment by direct cooling has been designed and built at KIST. Cool-down characteristics and liquefaction performance of the equipment have been investigated. The hydrogen liquefaction equipment consists of a GM refrigerator, a liquefaction velssel, a radiation shield and a cryostat. It is found that the hydrogen starts to be liquefied in the liquefaction vessel after 40~50 minutes of cool-down from the gas state of 270K. The effect of natural convection phenomena of charged gas in liquefaction vessel on the cool-down characteristics is evaluated by comparing with those in vacuum of liquefaction vessel. It is seen that the cool-down time of a liquefaction vessel is substantially increased in vacuum environment of liquefaction vessel. The experiments have been performed for 1~5 atm of hydrogen pressure to investigate the influence of hydrogen pressure on the liquefaction rate and figure of merit(FOM). It is found that both liquefaction rate and FOM are increased as the charged hydrogen pressure is increased.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.9 no.3
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• pp.389-400
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• 1997

A thermodynamic cycle analysis is performed for refrigerator-precooled Linde-Hampson hydrogen liquefiers, including catalysts for the ortho-to-para(o-p) conversion. three different configurations of the liquefying system, depending upon the method of the o-p conversion, are selected for the analysis. After some simple and justifiable models are introduced, a general analysis program to predict the liquid yield and the figure of merit(FOM) is developed with incorporating the commercial computer code for the hydrogen properties. The discussion is focused on the effect of the two primary design parameters-the precooling temperature and the high pressrure of hydrogen. When the precooling temperature is in the range between 45 and 60 K, the optimal high pressure for the maximal liquid yield is found to be in the range between 100 to 140 bar, regardless of the o-p conversion. However, the FOM can be maximized at slightly smaller values of high pressures. It is remarkable to observe that the lower precooling temperatures are favorable since both the liquid yield and the FOM can be obtained without compressing hygrogen to extremely high pressures.

• Korean Journal of Veterinary Service
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• v.30 no.1
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• pp.155-164
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• 2007

This study was conducted to investigate the prevalence of canine heartworm infections, canine brucellosis and hematologic values from 153 free roaming dogs in the area of Gwangju city from March to November 2006. Nineteen (12.4%) of 153 samples tested with modified Knott's technique showed positive reaction for microfilariae. Polymerase chain reaction using specific primers for D immitis amplified the expected product from all samples of 19 microfilaremic canine blood samples as determined by the modified Knott's test for microfilariae. The seasonal infection rates of microfilariae were higher in the spring season (10/19, 52.6%) than in the other seasons. The major hematological findings in microfilaremic dogs were mild leukocytosis and mild monocytosis. A total of 100 dogs randomly selected from 153 free roaming dogs were negative for canine brucellosis by serological test using immunochromatographic antibody test kit.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07a
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• pp.80-83
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• 2003

In this paper, the programming characteristics of the multi-bit devices based on SONOS structure are investigated. Our devices have been fabricated by $0.35\;{\mu}m$ complementary metal-oxide-semiconductor (CMOS) process with LOCOS isolation. In order to achieve the two-bits per cell operation, charges must be locally trapped in the nitride layer above the channel near the junction. Channel hot electron (CHE) injection for programming can operate in multi-bit using localized trap in nitride film. CHE injection in our devices is achieved with the single power supply of 5 V. To demonstrate CHE injection, substrate current (Isub) and one-shot programming curve were investigated. The multi-bit operation which stores two-bit per cell is investigated with a reverse read scheme. Also, hot hole injection for fast erasing is used. Due to the ultra-thin gate dielectrics, our results show many advantages which are simpler process, better scalability and lower programming voltage compared to any other two-bit storage flash memory. This fabricated structure and programming characteristics are shown to be the most promising for the multi-bit flash memory.

• Korean Journal of Veterinary Service
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• v.36 no.3
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• pp.187-192
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• 2013

For the monitoring of six viral disease (CIV: canine influenzavirus, CPIV: canine parainfluenzavirus, CHV: canine herpesvirus, CPV2: canine parvovirus type 2, CCoV: canine coronavirus, CNV: canine norovirus) inspections, a total of 300 samples were collected nasal or feces from the companion dogs of animal hospital (n=98) and the abandoned dogs of animal shelters (n=202) in Gwangju, Korea. Using PCR and RT-PCR, CPV2, CPIV and CHV were detected in 55 (18.3%), 11 (3.7%), 1 (0.3%), respectively. CPV2 was highly detected in May, October and November. and CPIV was highly detected in November. But those agents were not detected the virus in March and July. Based on the results of the investigation continuous monitoring for companion and abandoned dogs will be required.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.109-112
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• 2012

원자력발전소는 타 산업시설에 비해 화재발생 가능성이 낮으나 방사성물질 누출가능성을 최소화하기 위하여 심층방어와 다중방호 설계를 통한 안전성확보가 매우 중요하다. 이를 위해 국내에서는 화재위험도분석(FHA)과 안전정지능력분석(SSA) 및 화재 확률론적안전성분석(Fire PSA)을 수행하고 있으며, 이 중 화재 PSA는 주요 화재구역 선별, 구역별 화재발생빈도 및 기기손상확률 계산, 화재사고 경위분석 및 화재취약성 파악 등을 분석한다. 본 논문에서는 미국 원자력규제위원회(USNRC)와 전력연구소(EPRI)가 공동 연구개발한 화재 PSA 방법론인 NUREG/CR-6850 기법을 적용하여, 화재 PSA에 필요한 화재점화빈도(Fire Ignition Frequency)를 정량적으로 계산하였다. 정확한 결과값을 도출하기 위해 매크로를 이용한 프로그램인 FIFA(Fire Ignition Frequency Analyzer)를 개발하였으며, 향후 국내 원전 화재 PSA 분석업무에 유용하게 사용될 수 있을 것으로 기대된다.

• Korean Journal of Veterinary Service
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• v.28 no.3
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• pp.235-243
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• 2005

This surveies were carried out to investigate the residual levels of fluoroquinolones in chicken and quail eggs by bioassay and HPLC method. The eggs of 240 samples collected from market and farm in Gwangju Metropolitan city were examined from May to December in 2003. Residual antibiotic materials were detected from 47 samples of the 240 eggs by bioassay. Of the 240 eggs assayed, ciprofloxacin, danofloxacin, norfloxacin, ofloxacin, orbifloxacin and perfloxacin were not detected but enrofloxacin was detected from 5 samples in 228 chicken eggs and 1 sample in 12 quail eggs using HPLC with fluorescence detector by multi-residue method. 2 sample eggs in 6 sample which were detected by HPLC were not positive with bioassay. The average residual concentration of enrofloxacin was 0.494 mg/kg in 6 positive samples. The highest residual concentration of enrofloxacin was 1.83mg/kg.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.02a
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• pp.331-331
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• 2012

With the NAND Flash scaling down, it becomes more and more difficult to follow Moore's law to continue the scaling due to physical limitations. Recently, three-dimensional (3D) flash memories have introduced as an ideal solution for ultra-high-density data storage. In 3D flash memory, as the process reason, we need to use poly-Si TFTs instead of conventional transistors. So, after combining charge trap flash (CTF) structure and poly-Si TFTs, the emerging device SONOS-TFTs has also suffered from some reliability problem such as hot carrier degradation, charge-trapping-induced parasitic capacitance and resistance which both create interface traps. Charge pumping method is a useful tool to investigate the degradation phenomenon related to interface trap creation. However, the curves for charge pumping current in SONOS TFTs were far from ideal, which previously due to the fabrication process or some unknown traps. It needs an optimization and the important geometrical effect should be eliminated. In spite of its importance, it is still not deeply studied. In our work, base-level sweep model was applied in SONOS TFTs, and the nonideal charge pumping current was optimized by adjusting the gate pulse transition time. As a result, after the optimizing, an improved charge pumping current curve is obtained.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.182-185
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• 2003

Temperature distribution and cooling load in binary current lead are analized, occurring fault current at DC Reactor type superconductor fault current limiter. It is assumed that Normal operating current is 300 A and fault current is 3000 A. Unsteady-state temperature distribution and cooling load of brass current lead optimized for 300 A and 1000 A are calculated by numerical method with TDMA. In the result of calculation, temperature increase in the brass current lead optimized for 300 A is higher than that in the brass current lead optimized for 1000 A, but the temperature increase in the brass current lead optimized for 300 A is not serious. Moreover, increase of cooling load in the brass current lead optimized for 300 A is higher than that in the brass current lead optimized for 1000 A, but normal cooling load in the brass current lead optimized for 300 A is lower than that in the brass current lead optimized for 1000 A. Therefore, designing current lead in superconductor fault current limiter had better to optimize for normal operating current.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.7
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• pp.485-490
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• 2007

The LNG BOG re-liquefaction system for LNG carriers was designed based on the Claude refrigeration cycle and the thermodynamic analysis was carried out in order to find the design point of the three heat exchangers constituting the system. The thermodynamic analysis revealed that the system state could be defined by the three cold endpoint temperatures of the three-pass heat exchanger. Hence the iso-lines of the specific liquefaction work, taken as the performance indicator, were presented in terms of those three temperatures and discussed. The system was found most economical when those three temperatures approached a single temperature of $-140^{\circ}C$ and thus this system state could be taken as the design point for the heat exchangers.