• 전기전자학회논문지
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• 제23권1호
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• pp.254-260
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• 2019

본 논문에서는 양방향 dc-to-dc 컨버터의 고장원인, 고장영향, 고장 결과를 파악하기 위한 failure mode and effect analysis(FMEA)와 양방향 컨버터의 위험도를 고려한 fault-tree analysis(FTA)를 통해 고장률을 예측한다. 전기차의 구동전압을 효율적으로 상승시키기 위해 인버터 앞단에 부착되는 양방향 컨버터는 배터리 전력을 dc-link 커패시터로 방전시키는 승압모드와 회생전력을 배터리로 충전시키는 강압모드를 가진다. 양방향 컨버터의 동작 특성을 고려한 FMEA 결과를 바탕으로 컨버터의 위험도를 고려한 고장나무를 설계한다. 전기차 MCU용에 맞는 설계 파라메타를 설정하고 출력전압 리플과 인덕터 전류 리플에 따른 커패시터와 인덕터의 부품 고장률을 분석한다. 또한 동작 온도에 따른 주요부품의 고장률을 MIL-HDBK-217F를 이용하여 구한다. 마지막으로 부품 고장률을 고장나무의 기본 사상의 고장률로 반영하여 컨버터 고장률과 평균고장시간을 예측한다.

• 한국가금학회지
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• 제35권3호
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• pp.275-281
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• 2008

산란계 사료에 lycopene을 첨가 급여하여 생산된 계란의 난황 중에 전이된 lycopene의 함량을 급여 기간별로 확인하고, lycopene 함유 계란의 난황색, 난중, 난각 강도, 난황고, 난백고, 난황 직경, 난황 계수와 Haugh Unit(호우 유닛) 등 계란의 각종 품질 특성과 이들 계란의 장기 보존에 따른 품질의 변화상을 조사하여 다음과 같은 결과를 얻었다. 1. 결과 lycopene 처리군의 계란 중 lycopene 농도는 난황액 1 gram 당 각각 약 1.56 ${\mu}g$과 1.57 ${\mu}g$ 이었으며, 대조군의 계란에는 lycopene의 함량이 없는 것으로 나타났다. 2. 사양 시험 2주경의 처리군의 난황 중 lycopene 함량 수준(23.4 ${\mu}g$)은 4주경의 수준(23.6 ${\mu}g$)과 유사하였다. 즉, 동일수준의 lycopene 첨가 사료를 지속적으로 급여하여도 난황 내 lycopene의 함량은 급여 기간의 경과에 따라 누적적으로 증가되지 않는 것으로 나타났다. 3. Lycopene 첨가군의 난황색 (P<0.01)은 대조군에 비하여 유의적으로 높은 수치를 보였다. 이외에도 처리군간에 통계적 유의성은 인정되지 않았으나 lycopene 첨가군의 난황고(P<0.08), 난황 직경(P<0.19), 난각 견실도(P<0.19), 호우 유닛(P<0.34), 난백고(P<0.33)도 대조군에 비하여 다소 높은 수치를 보였다. 각 처리군간에 난중의 차이는 없는 것으로 나타났다. 4. 계란을 실온에서 4주간 보관시킨 후, 이들의 품질을 측정한 결과, Lycopene 처리군의 난황색(EYC)은 대조군에 비하여 유의적으로 높았으나(P<0.01), 그 이외의 항목에서는 유의적 차이가 없었다. 저장 4주 후의 첨가군의 난백고와 난황고는 대조군 보다 크고 난황 직경(EYD)은 대조군보다 작게 나타났다. 이 현상은 첨가군의 호우유닛 수치를 대조군보다 크게 하는 데 영향을 미친 것으로 추정된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.3458-3463
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• 2007

Leakage would happen because of the damage of high temperature and high-pressure valve in nuclear power plant. condition based prevention maintenance is essential by using the suitable method based on local condition. Energy loss prevention can prevent from an accurate test, Local actually and ability. The methods of test for high energy fluid leakage at present are analysis of ${\Delta}$T, AE(Acoustic Emission) analysis, and thermal image. The result for test of AC (Main steam) system in YNG 2 Unit reveals that the AE occurred clearly in leakage situation, but thermal image didn't occur. It is identified that leakage is occurred when the orifice located front and back of valve operates. It shows that making a impatient judgment by using the single method if it is leakage is containing uncertainty. So I think that using the Multi-Measuring method is more sound judgment than Single-Measuring method.

• 대한간호학회지
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• 제29권2호
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• pp.346-360
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• 1999

The purpose of this research was to identify nursing interventions performed by hospital nurses in Korea. The sample consisted of 311 nurses working in three hospitals. The Nursing Interventions Use Questionnaire developed by the Iowa Intervention Project team was used for data collection. The instrument was translated to Korean using the method of back-translation. Eighteen interventions were performed at least daily. Interventions in the Physiological : Basic domain were most frequently used at least daily. No interventions in the Family and Behavioral domains were used by nurses at least once a day. The most frequently used interventions was Documentation, followed by the interventions Medication : Parenteral, Intravenous(IV) Insertion, Temperature Control, and Shift Report. The intervention performed least often was Reproductive Technology Management. Nurses working in intensive care units on the whole performed interventions most often, while nurses working in obstetric, gynecological, and pediatric units performed them least often. The nurses working in intensive care unit, medical and surgical care units performed the interventions in the Physiological : Basic domain more often than the nurses working in obstetric, gynecological, and pediatric units. The nurses working in obstetric, gynecological, and pediatric units used the interventions in the Family domain more often than the nurses working in the other three units. This study contributes to the documentation of nursrs' work in Korea. Further study will be needed to validate nursing activities of each NIC intervention.

• Nuclear Engineering and Technology
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• 제46권3호
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• pp.431-438
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• 2014

The effect of various pH agents on the corrosion behavior of carbon steel was investigated under a simulated secondary water chemistry condition of a pressurized water reactor (PWR) in a laboratory, and the steel's corrosion performance was compared with the field data obtained from Uljin NPP unit 2 reactor. All tests were carried out at temperatures of $50^{\circ}C-250^{\circ}C$and pH of 8.5 - 10. The pH at a given temperature was controlled by adding different agents. Laboratory data indicate that the corrosion rate of carbon steel decreased as the pH increased under the test conditions and the highest corrosion rate was measured at $150^{\circ}C$. This high corrosion rate may be related to high dissolution and instability of Fe oxide ($Fe_3O_4$) at $150^{\circ}C$. It was also found that an addition of ethanolamine (ETA) to ammonia was more effectivefor anticorrosion than ammonia alone, and that mixed treatment reduced 50% of iron or more at pHs of 9.5 or higher, especially in the steam generator (SG) and the moisture separator & re-heater (MSR).

• Food Science and Biotechnology
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• 제15권2호
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• pp.196-201
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• 2006

Freeze concentration of milk was carried out thorough the controlled recrystallization of ice in a multi-stage freeze concentrator. Artificial temperature control was used to induce ice recrystallization via a heat and cold shock process. In each stage of freeze concentration, the recrystallization time was fixed at 1, 2, 4, and 8 hr to compare the solute concentrate, yield, Brix, ice crystal size, and freezing point at each experimental condition. Higher concentrations of milk solids were seen with increased durations of recrystallization time, and a maximum total solids in the final product of 32.7% was obtained with a ripening time of 8 hr in a second stage process. Milk solid yield decreased according to the solute concentration and recrystallization time. The results of Brix and ice crystal size showed a positive correlation with recrystallizaiton time. These results suggest the possibility of freeze concentration being of practical use in the dairy industry.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.439-441
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• 2007

The seoul metropolitan subway has installed 8 lines and about 500 stations to transport 5 million passengers everyday. The underground air pollution level in the subway stations is very severe status, which is very harmful to the commutators and its personals. Although subway roles as such a massive and huge transportation system, the subway doesn't adapt yet any real-time air monitoring system. They have only some hand-held type detector equipments for monitoring air pollution. Therefore subway passengers are exposed to the harmful air pollution environment. The most harmful environmental parameters among the air pollution are known as the dust and sound noise dB level in the subway station. Because the dust is consisted of very small particles, we can't see them easily in dark condition on the platform, but it is very harmful. The monitoring system for air pollution is developed using embedded system attached with 6 different environmental sensors. This system monitors air pollution of dust sound noise, gas, temperature, humidity, inflammable gas, toxic gas in the subway ?station. The sensor unit of the ARM-CPU board and sensor transmits real time environmental data to the main server using Zigbee wireless communication module and TCP/IP network. The main control server receives and displays the real-time environmental data, and it send alarms to the personals when high level value.

• 한국기계가공학회지
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• 제11권2호
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• pp.47-54
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• 2012

An oxygen sensor installed in vehicle exhaust systems enables to measure the amount of oxygen in the exhaust gas, in which the measured data are collected and analyzed in ECU(Engine Control Unit). The oxygen sensor is exposed to the high speed exhaust gas at high temperature circumstance, so that protection caps are required not only to protect the susceptible measuring part, but also to provide the real time measurement without time delay. In this study, a new oxygen sensor with one protection cap was proposed, and the CFD analysis was carried out in order to compare the performance characteristics, such as flow speed and ratio of AOA(Age of Air), for the conventional and new oxygen sensor. The numerical results of CFD analysis provided the flow speed of 1.34m/s and the ratio of AOA of 3.43. The similar features obtained from the numerical results showed that the new oxygen sensor guarantees the same performance characteristics of the conventional ones.

• Parasites, Hosts and Diseases
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• 제44권1호
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• pp.67-72
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• 2006

Anthropophilic Culicoides were investigated in a rural community endemic for Mansonella perstans in Ijebu North area of western Nigeria between December 2003 and October 2004. Three hundred and fifty-nine adults of Culicoides fulvithorax collected by human bait in the morning were dissected for Mansonella perstans larvae, and $1.95\%$of infection rate was found. Seasonal abundance of C. fulvithorax was investigated by monthly biting rates, and showed that higher prevalence was observed in rainy season, with peak in September. Culicoides prevalence was positively correlated with rainfall and relative humidity, but not temperature. Human perceptions on the behavior of these biting midges were determined by interviewing 854 self-selected villagers, of which $86.5\%$ of the interviewees confessed having experienced Culicoides bites. Between 76.5 and $99.1\%$ of the various age groups complained body reactions to Culicoides bites. Itching was the most frequent body reaction. No interviewees associated Culicoides with transmission of any parasitic infections. The results showed need to adequately control Culicoides in the community.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2005년도 동계학술발표대회 논문집
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• pp.141-147
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• 2005

Although the importance of good conservation of historic sites including ancient royal tombs is wet] aware, still not much attention has been paid for the facilities and systems to preserve those historic sites, which includes precious artifacts as wall paints and carved works, etc. Even the general understanding about the environment of the underground space of tombs is not satisfactory. In the present study, vibration levels due to the operation of an HVAC system to maintain the desired indoor temperature and humidity are investigated experimentally. According to the measured data, the level of vibration inside the present model tomb with the indoor unit inside, showed order of magnitude less values than the Swiss Standards, but still higher than the value suggested by German standards, which is, zero. For the vibration level depends not only on the system design, but also on the installation methods, further study will be pursued for cases including different ways of installation.