• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.3
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• pp.1684-1691
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• 2015

For performance improvement and compactness, usage of enhanced tube is inevitable. However, studies on enhanced tubes for generator is very limited. In this study, pool boiling tests were conducted for 7 heat transfer tubes. Test range covered pressure 7.38~101.3 kPa and heat flux $20{\sim}40kW/m^2$. Results show that boiling heat transfer coefficient increases as pressure or heat flux increases. Under atmospheric condition, high heat transfer coefficients were obtained for notched fin and low fin tubes(225% and 202% of the 19.0 mm smooth tube, which yielded the lowest heat transfer coefficient). As pressure decreased, high heat transfer coefficients were obtained for a low fin tube(290% and 288% of the 19.0 mm smooth tube at 12.34 and 7.38 kPa).

• Journal of Chest Surgery
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• v.29 no.10
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• pp.1066-1075
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• 1996

To compare the efficacy of cardiac preservation, we examined purine metabolites during 24 hours of cold storage($0^{\circ}C$) of the Korean ongrel dog hearts after using three different types of cardioplegic solutions. The hypothermic arrest with total cardiopulmonAry bypass method was employed in 51. Thomas solution(575) and blood cardioplegic solution(BCPS) preservation cases. Specimens were analyzed for levels of adenine nucleotides and their precursors by high performance liquid chromatography. The ATP content in the UW(University of Wisconsin) solution group tends to be higher than that of the combined hypothermic arrest group(575 and BCPS groups) after 2,4,8, and 12 hours of preservation respectively, but there were no significant differences between 575 and BCPS groups. The ADP contents in the UWS and BCPS groups were higher than that of the 575 group at 4,8, 12, and 24 hours, but the difference was not statistically significant between UWS and BCPS groups. The AMP contents did not change significantly in the three groups. The adenosine, Inosine, and hypoxanthine concentrations increased progressively, but the lev l of xanthine was very low in the three groups.

• Journal of IKEEE
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• v.22 no.2
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• pp.258-265
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• 2018

This paper proposes an algorithm for reducing the starting current when the single-phase induction motor starts and analyzes its operation. Generally, the single-phase induction motors require several starters to generate the starting torque due to their structural characteristics. In this paper, a capacitor-start / capacitor-run method of the single-phase induction motor is basically adopted. This conventional method is efficient and has a large starting torque, but it generates about 5 ~ 6 times of inrush current at startup. As a result, the freezer starting device and peripheral devices are damaged and life time may be reduced. To reduce the inrush current, the current control algorithm based on the virtual dq model is presented to control the starting current. In addition, it validates the proposed algorithm through experiments to smooth transit from start-up operation to the rated operating region.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.1
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• pp.1-10
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• 2020

This study deals with the fabrication and thermal characterization of planar heating elements attached to the backside of the reflector used in the electrodeless lamp of a freezer. We tried to solve the problem of the local heat generation of the linear heating element that occurs about 50℃. The homogeneous dispersion and manufacturing excellence of the planar heating element produced were confirmed through SEM and EDS. In addition, the test specimens was prepared according to the change in the ratio of carbon fiber to the basis weight of the planar heating element, and a sample having a basis weight of 50g/㎡ having a content ratio of carbon fiber of 70% was selected. That sample showed low surface resistance of 4.3Ω/sq and high temperature of about 81℃ at 6V. Durability was confirmed by performing repeated bending evaluation of 3000 cycles for the sample. Large area test specimens were prepared to be applied to the actual reflector, insulated by EVA film and analyzed for their thermal characteristics. From 13V application, the temperature of the linear heating element was higher than 50℃ and the average temperature of 68℃ was maximum at 18V.

• Journal of Korean Society of societal Security
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• v.3 no.1
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• pp.43-50
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• 2010

Sliding accidents on the road have a high percentage by road freezing, especially, they often have appeared at bridges and Tunnel of freezing areas. Thus, the stability of road operations is enhanced by preventing partial freezing phenomenon. According to the geothermal snow melting system analysis, a pattern of thermal conductivity is found out; pavement materials of concrete and asphalt where the system is buried. The heat transfer simulation is essential when the geothermal snow melting system is applied according to heating exchanger pipe placed in the lower pavements. The model tests are conducted on low temperature in freezer using the manufactured test model which is equal to pavement materials. Many variables are discovered from numerical analyses under the same conditions with model test.

• The Korean Journal of Mycology
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• v.43 no.4
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• pp.286-289
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• 2015

Clubroot, caused by the obligate parasite Plasmodiophora brassicae, is a severe soilborne disease of Brassicaceae. Storage of clubroot gall is important for studies on pathogenicity and race identification. As the current storage method has been used for more than 100 years, a new storage method should be developed and the most efficient way maintaining pathogenicity should be determined. Effects of storage conditions with different storage periods on pathogenicity in galls of kimchi cabbage were examined in a greenhouse. The experiments were performed under six conditions and four temperatures in order to determine the most effective storage conditions for maintenance of pathogenicity. The most effective conditions for clubroot gall storage was the storage of whole gall at $-70^{\circ}C$ or storage of filtrate at the same temperature through eight layers of gauze after homogenization of the galls.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.7
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• pp.360-365
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• 2017

Recently, development efforts of triple-effect absorption chiller have been increased in order to improve the efficiency of double-effect absorption chiller. However, triple-effect absorption chiller has some disadvantages, including high corrosion characteristic of LiBr solution at high temperature of $200^{\circ}C$. Moreover, it is necessary to develop new components for operation under high pressure of 2 bars even though COP is increased to 1.6 or 1.7. The objective of this study was to introduce a new system by combining double effect absorption chiller with single effect absorption chiller with multi-generators using bypass flow of LiBr dilute solution to $3^{rd}$ generator to overcome the disadvantages of triple-effect chiller and improve energy efficiency. Results indicate that the new absorption cycle had a much higher efficiency than double-effect chiller system, showing significant improvement when bypass solution flow rate of 25% was applied to the $3^{rd}$ generator using the main dilute solution of the absorber. The COP of the new chiller system was found to be 1.438, which was 21.7% higher than that (1.18) of the present double-effect system. The COP was decreased when solution by-pass rate to the $3^{rd}$ generator was increased. In addition, lower cooling water temperature caused higher COP. Therefore, the multi-generator system with by-pass solution might be an excellent chiller alternative to triple-effect absorption chiller with higher efficiency.

• 기계와재료
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• v.22 no.3
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• pp.120-129
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• 2010

획기적으로 선명한 영상의 구현, 휴대 용이성 및 정확한 온도분포의 구현이 가능한 초점면 배열 방식의 적외선 검출기는 탐지도 및 분해능 향상을 위해 액체질소 온도수준의 극저온냉각을 요구한다. 냉동기의 저온부에 적외선 검출기를 직접 부착하는 일체형 스터링 극저온냉동기는 효율적인 적외선 검출기의 냉각이 가능할 뿐 만 아니라, 소형/경량화가 용이하여, 기동 및 휴대용 열상장비용 극저온냉각을 위해 많이 활용되고 있다. 적외선 검출기 냉각용 즉저온냉동기는 다양한 열/진동/충격/전자파 등의 운용환경조건에서 검출기를 액체질소 온도수준으로 냉각/유지할 수 있어야 하며, 안정적인 시스템의 운용을 위한 충분한 신뢰성이 확보되어야 한다. 본 고에서는 민군 겸용기술사업을 통해 국내에서 개발된 열상장비 냉각용 일체형 스터링냉동기의 기술적 특징 및 환경/신뢰성 시험 결과를 소개하고자 한다.

• THE HEALTH and ORGANIC FARMING
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• no.231
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• pp.1-12
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• 2006

제28회 한국유기농업대회 준비돌입/환경호르몬으로부터 자유로워질수 있는 길/우리의 산야초/연속 강우에 따른 과일나무 잎의 갈변에 대하여/벼 멀칭재배의 이론과 기술/김제지평선축제, 성공적으로 개최돼/신태인 유기농 포도축제 성료/질병 예방을 위한 식사/일본,고령화와 웰빙 붐으로 건강식품시장 '폭발'/스위스,유기농가 급속 확산/LA,'건강빵'경쟁 후끈~후끈/일본,학교급식용 중국산 냉동가지 풋콩에서 잔류농약 검출/두가지 비료로 유기농작물의 고품질 다수확 생산을 체계적으로 보다 쉽게 하는 방법/전남도, 전국 최초 '친환경축산 5개년 종합계획'수립/배추 노균병 어떤 병인가?/고추.방울토마토 증수/중국 박람회 및 유기농장 연수기/"유기가공식품" 인증 법제화 추진/국내외 친환경 농축산물의 생산 및 인증 실태/친환경 유기낙농의 정착 방안/9월중 새식구 명단/농촌진흥청,토양전자지도,휴대폰 영농정보 제공/친환경인증기관협의회 출범/친환경농자재'목록공시제'시행/충주시,친환경바이오농업 확대 추진/제주,친환경농업 발전전략 심포지엄 개최/유기 및 일반 농산물의 품질 비교에 관한 연구/유기질 비료의 이해

• KOREAN POULTRY JOURNAL
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• v.41 no.7
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• pp.79-81
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• 2009

2008년 4월에는 국내에서 3차 고병원성 조류인플루엔자(HPAI)가 발병하여 일시적으로 육계업계가 큰 어려움을 겪었다. 다행히 병아리 렌더링을 추진하는 등 업계의 자율적인 공급 감축 노력과 HPAI에 감염된 닭은 시중에 유통되지 않는다는 적극적인 홍보 덕분에 닭고기 소비가 단기간에 회복되어, 2008년 7월부터 8월까지(여름철 복 경기) 육계 가격은 강세로 돌아섰다. 2008년 하반기에는 국제 곡물 상승에 따른 사료가격 인상분이 육계 가격에 반영되어 높은 가격이 책정되었다. 이와 더불어 2008년 12월 22일부터 닭고기에 대한 음식점원산지표시제가 의무적으로 시행됨에 따라 국내산 닭고기에 대한 수요가 급격히 증가하였다. 이에 2008년 말부터 2009년 6월 현재까지 육계 가격은 높게 형성되고 있다. 여기에 수입량과 냉동 비축 부족 그리고 일시적인 신종 인플루엔자 발생 등도 높은 육계 가격 유지에 한 몫을 하고 있다. 그러나 병아리 가격이 사상 최고치(800원)를 기록하며 최근까지 강세를 보임에 따라 육용 종계 도태가 지연되는 것이 문제이다. 이 때문에 오히려 국내 닭고기 생산은 2008년보다 증가하고 있기 때문이다. 이 글에서는 위와 같은 상황들이 향후 여름철 복 경기와 하반기 육계 시장에 어떠한 영향을 미칠 것인가를 분석하여 하반기 육계 경기를 전망해 보고자 한다.