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You, Sin-Wook,Kim, Il-Ho,Choi, Soon-Mok,Seo, Won-Seon Hindawi Limited 2013 Journal of nanomaterials Vol.2013 No.-
<P>Mg2+<I>x</I>Si0.7Sn0.3Sb<I>m</I>(0≤x≤0.2,m=0or 0.01) solid solutions have been successfully prepared by mechanical alloying and hot pressing as a solid-state synthesis route. All specimens were identified as phases with antifluorite structure and showed n-type conduction. The electrical conductivity of Mg-excess solid solutions was enhanced due to increased electron concentrations. The absolute values of the Seebeck coefficient varied substantially with Sb doping and excess Mg, which was attributed to the change in carrier concentration. The onset temperature of bipolar conduction was shifted higher with Sb doping and excess Mg. The lowest thermal conductivity of 1.3 W/mK was obtained for Mg2Si0.7Sn0.3Sb0.01. A maximum<I>ZT</I>of 0.64 was achieved at 723 K for Mg2.2Si0.7Sn0.3Sb0.01.</P>
Thermoelectric Properties of Mg2Si1−xGex Prepared by Using a Solid-state Reaction
Sin-Wook You,김일호 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.5
Mg2Si1−xGex (0 x 1) solid solutions have been successfully prepared by using a solid-statereaction and hot pressing. The electrical conduction changed from n-type to p-type at room temperaturewhen x 0.7 due to the intrinsic properties of Mg2Ge. For all specimens, the electricalconductivity increased and the absolute value of the Seebeck coefficient decreased with increasingtemperature. The thermal conductivity was reduced by phonon scattering due to solute Ge atoms. Mg2Si0.7Ge0.3 and Mg2Si0.5Ge0.5 had low thermal conductivities of 2.2−3.5 W/mK at all temperaturesexamined. An improvement in the thermoelectric figure of merit is expected when the carrierconcentration is optimized by using effective doping.
Sin-Wook You,Dong-Kil Shin,김일호 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.64 No.9
Sb-doped Mg2Si1−xGex solid solutions were successfully prepared by using a solid-state reactionand hot pressing. In the case of the undoped Mg2Si1−xGex specimens, the electrical conductionchanged from n-type to p-type at room temperature for x 0.7 due to the intrinsic propertiesof Mg2Ge. The electrical conductivity rapidly increased with increasing temperature, indicatinga non-degenerate semiconducting behavior, and decreased with increasing Ge content. However,the Sb-doped Mg2Si1−xGex specimens showed n-type conduction, and the carrier concentrationwas increased from 4.0 × 1017 to 3.2 × 1021 cm−3 by doping with Sb atoms, which acted asdonors. The absolute value of the Seebeck coefficient increased with increasing temperature, andthe Seebeck coefficient ranged from −131 to −259 μV/K for the Sb-doped specimens. Sb dopingreduced the thermal conductivities of the Mg2Si1−xGex solid solutions at temperatures above 723K. Mg2Si0.5Ge0.5:Sb0.02 exhibited a maximum dimensionless figure-of-merit of 0.56 at 823 K.
의식이 명료한 다발성 외상환자에게 전신 전산화단층촬영이 반드시 필요한가?
문유호 ( You Ho Mun ),김윤정 ( Yun Jeong Kim ),신수정 ( Soo Jeong Shin,),박동찬 ( Dong Chan Park ),박신율 ( Sin Ryul Park ),류현욱 ( Hyun Wook Ryu ),서강석 ( Kang Suk Seo ),박정배 ( Jung Bae Park ),정제명 ( Jae Myung Chung ),배지 대한외상학회 2010 大韓外傷學會誌 Vol.23 No.2
Purpose: Whole-body CT is a very attractive diagnostic tool to clinicians, especially, in trauma. It is generally accepted that trauma patients who are not alert require whole-body CT. However, in alert trauma patients, the usefulness is questionable. Methods: This study was a retrospective review of the medical records of 146 patients with blunt multiple trauma who underwent whole body CT scanning for a trauma workup from March 1, 2008 to February 28, 2009. We classified the patients into two groups by patients` mental status (alert group: 110 patients, not-alert group: 36 patients). In the alert group, we compared the patients` evidence of injury (present illness, physical examination, neurological examination) with the CT findings. Results: One hundred forty six(146) patients underwent whole-body CT. The mean age was 44.6±18.9 years. One hundred four (104, 71.2%) were men, and the injury severity score was 14.0±10.38. In the not-alert group, the ratios of abnormal CT findings were relatively high: head 23/36(63.9%), neck 3/6(50.0%), chest 16/36(44.4%) and abdomen 9/36(25%). In the alert group, patients with no evidence of injury were rare (head 1, chest 6 and abdomen 2). Nine(9) patients did not need any intervention or surgery. Conclusion: Whole-body CT has various disadvantages, such as radiation, contrast induced nephropathy and high medical costs. In multiple trauma patients, if they are alert and have no evidence of injury, they rarely have abnormal CT findings, and mostly do not need invasive treatment. Therefore, we should be cautious in performing whole-body CT in alert multiple trauma patients. (J Korean Soc Traumatol 2010;23:89-95)
Thermoelectric Properties of Skutterudite InyCo4−xFexSb12
Kwan-Ho Park,Sin-Wook You,어순철,김일호,최순목,서원선 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.10
In-filled and Fe-doped CoSb3 (InyCo4−xFexSb12) skutterudites were prepared by encapsulated induction melting and hot pressing, and their thermoelectric and transport properties were examined. A single δ-phase was successfully obtained by subsequent annealing at 823 K for 24 h, but it decomposed to FeSb2 and Sb when x = 1.5. The Hall and the Seebeck coefficients of the InyCo4−xFexSb12 samples had positive signs, indicating p-type conduction by holes. The electrical conductivity was increased by Fe doping, but the thermal conductivity was decreased by In filling due to phonon scattering. The thermoelectric properties were improved by In filling and Fe doping, and were closely related to the optimum carrier concentration and phonon scattering.
Mobile IP 에서의 핸드 오프 지연 시간 감소 기법
유승연 ( Seung-yeon You ),이장수 ( Jang-su Lee ),이성주 ( Sung-ju Lee ),신홍중 ( Hong-joong Sin ),유승환 ( Seung-hwan Yoo ),이상혁 ( Sang-hyuck Lee ),김승욱 ( Seung-wook Kim ),김성천 ( Sung-chun Kim ) 한국정보처리학회 2007 한국정보처리학회 학술대회논문집 Vol.14 No.2
무선랜에서는 작은 셀 크기로 인해 노드들의 이동에 따른 빈번한 핸드오프가 이루어진다. 그래서 무선랜에서는 지속적인 통신 서비스를 제공하기 위한 방법으로 모바일 아이피와 같은 방법을 개발하고 있다. 모바일 아이피는 모바일 노드가 한 장소에서 다른 장소로 이동할 때 IP 주소의 변경 없이도 이동할 수 있도록 해준다. 그러나 모바일 아이피는 긴 시간의 등록과정과 연결 재설정 때문에 시간지연이나 패킷 손실과 같은 오버헤드를 발생시킨다. 따라서 무선랜의 QOS(Quality Of Service)를 향상시키기 위해서 Mobile IP 의 핸드오프 시간을 줄여야만 한다. 본 논문은 이러한 문제를 해결하기 위해 핸드오프 지연 시간을 감소시키는 기법을 제안한다. 제안기법의 기본 아이디어는 모바일 노드의 이동 네트워크를 예상하여, 미리 패킷 포워딩을 수행하는데 있다. 우리는 각 모바일 노드들에게 connection proxy table 정보를 추가하였다. 그리고 이 테이블 정보를 이용함으로써 모바일 노드들은 홈에이전트와 포린에이전트에 COA(Care of address)를 미리 등록하는 것이 가능해졌다. 그 결과로 이동 노드들은 홈 네트워크를 완전히 벗어나지 않고도 핸드오프가 이루어져 지속적인 서비스가 가능하였다. 본 논문에서 제안하는 기법이 기존 Mobile IP 와 비교해 볼 때 핸드오프가 이루어지는 동안 비 연결 시간을 줄일 수 있다는 것을 실험결과를 통해서 확인할 수 있었다.
배관용 보온재의 난연 성능 시험방법에 따른 최대 발열량 분석
유우준(Woo Jun You),박정욱(Jung Wook Park),신연제(Yeon Je Sin),박형규(Hyeong Gyu Park),임옥근(Ohk Kun Lim) 한국화재소방학회 2020 한국화재소방학회논문지 Vol.34 No.1
본 연구에서는 보온재의 설치 상태를 고려한 ISO 20632와 NFPA 274 시험 기준에 따른 발열량 산출 결과를 분석하였다. 이를 위해서 보온재 총 6종(은박 발포폴리에틸렌(PE(S)), 무은박 발포폴리에틸렌폼(PE(N)), 고무발포(Rubber), 일본-폴리에틸렌폼(PE(J)), 일본-폴리우레탄폼(PU(J)) 그리고 일본-스티로폼(ST(J)))에 대해서 EN 13501-1과 화재성장 곡선에 따른 난연 등급을 구분하였다. 그 결과 PU(J), PE(J) 그리고 PE(N)는 Class E 및 Ultra-fast, NFPA 274 시험기준에 의한 PE(S)는 Class D 및 Fast, ISO 20632에 의한 PE(S)는 Class C 및 Slow, 그리고 Rubber와 ST(J)는 Class B 및 Slow로 나타났다. 하지만, 난연 등급 평가 기준인 최대 발열량에 대한 시간평균 기울기는 시험 방법에 따라서 동일 보온재에 대하여 다르게 나타났으며, 보다 정확한 원인을 분석하기 위한 기초 연구가 필요한 것으로 판단된다. In this study, the heat release rate of pipe insulation is analyzed by considering the installation status in accordance with the standards ISO 20632 and NFPA 274. The flame retardation rate was evaluated for six types of test samples: polyethylene foam covered with beaten silver (PE(S)), PE foam tapped (PE(N)), elastomeric closed cell thermal insulation (rubber), Japanese PE foam (PE(J)), Japanese polyurethane foam (PU(J)), and Japanese styro form (ST(J)) by EN 13501-1 and fire growth curve. The results show that PU(J), PE(J), and PE(N) were Class E and ultra-fast, NFPA 274 test standards for Class D and Fast, and PE(S) by ISO 20632 were Class C and Slow, and Rubber and ST(J) were Classes and Low. However, the changes in the time-averaged maximum heat release rate for each test standard (ISO 20632 and NFPA 274) to evaluate the flame retardation rate differed among identical materials. This means that the fundamental study is necessary to analyze the more accurate reasons.
밀폐유도용해로 제조된 2원계 Skutterudite CoSb<sub>3</sub>의 열전특성
유신욱,정재용,어순철,김일호,You, Sin-Wook,Jung, Jae-Yong,Ur, Soon-Chul,Kim, Il-Ho 한국재료학회 2006 한국재료학회지 Vol.16 No.5
Binary skutterudite $CoSb_3$ compounds were prepared by the encapsulated induction melting (EIM) process, and their thermoelectric, microstructural and mechanical properties were examined. Single-phase ${\delta}-CoSb_3$ was successfully produced by the EIM and subsequent heat treatment at 773 K-873 K for 24 hours in vacuum. Seebeck coefficient increased with increasing heat treatment temperature up to 673 K, showing the positive signs in the range of measuring temperature. However, the samples heat-treated at 773 K-873 K showed negative Seebeck coefficient from room temperature to 400 K, while it showed positive signs above 400 K. Electrical resistivity decreased with increasing temperature, showing typical semiconducting conductivity. Thermal conductivity decreased drastically with increasing heat-treatment temperature. This is closely related with the phase transition to ${\delta}-CoSb_3$.
김호정,이병철,김경욱,전하영,이인환,최대섭,강유미,권학중,신경철 대한소화기학회 1998 대한소화기학회지 Vol.31 No.1
Duplication cysts are spherical or elongated hollow structures which possess a coat of smooth muscle and a mucous membrane similar to some part of the alimentary canal, and they are intimately attached to some portion of the alimentary tube. They may appear at any level from the tongue to the anus and are more commonly found in relation to the small intestine than any other part of the gastrointestinal tract. Duplication cysts of the stomach are uncommon, making up only 4 to 5% of all gastrointestinal duplications. However, they may be associated with a variety of complications such as bleeding, obstruction, or perforation. These lesions should therefore be surgically repaired or removed whenever feasible.