• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
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• pp.139.1-139.1
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• 2013

Graphene and graphene oxide (GO) have been modified with palladium nanoparticles (Pd NPs) to develop high performance catalysts for the Sonogashira cross coupling reaction. To understand catalytic performance of Pd NPs on graphene (Pd/G) and Pd NPs on GO (Pd/GO), we monitored their morphological and electronic structural changes before/after Sonogashira reaction using FT-IR, XRD, XPS, and XAFS. Here, we demonstrate that both Pd/G and Pd/GO show high catalytic efficiency toward the Sonogashira reaction, but only Pd/GO revealed excellent recyclability. The remarkable catalytic efficiency of both catalysts is attributed to the high degree of the Pd NP dispersions on supports and thus smaller Pd NPs can provide highly reactive low coordinated Pd atoms. However, we attributed the excellent recyclability of Pd/GO to the presence of oxygen functionalities on GO, which can provide nucleation sites for the detached Pd atoms during the Sonogashira reaction and prevent agglomeration of the Pd NPs since the oxygen functional groups are very reactive to mobile Pd adatoms.

• 반도체디스플레이기술학회지
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• 제20권3호
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• pp.45-50
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• 2021

The adjustment of lens magnification can make the degree of precision in pattern measurement be improved, but several problems such as high cost, smaller field of view and stage error accumulation are followed. In this paper, a method for precisely measuring patterns is proposed based on gradient transition vector, in order to solve these problems. The performance of our method is evaluated using pattern images with several directions. Also, it is compared with previous methods based on edge and gray-level moment. It is judged that the proposed method outperforms consistent pattern width results, and so could be applied to automation processes for measurement and inspection of precise and complexed patterns in IT, BT industry products.

• 천문학회보
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• 제44권2호
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• pp.57.3-57.3
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• 2019

Space applications of the motion have been served with DC motors for decades. But their functionality with a gearbox and lubricants and their weights are always an issue for its application. A piezo-motor has an advantage on the direct driving with higher accuracy, smaller size, and no-EMI. We use the piezo-motor to rotate a filter wheel directly in a balloon-borne coronagraph launched on September 2019. The piezo-motor works well in a temperature range from -10 to 40 Celsius with high reliability and high positioning / tilt accuracy (~0.1degree) with a photo-encoder. We verify its functionality for 7 days. In this talk, we report the design, test processes of the filter wheel including its balloon flight result.

• 무역학회지
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• 제46권6호
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• pp.1-19
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• 2021

This paper examines the impact of sanitary and phytosanitary standards (SPS) and technical barriers to trade (TBT) on Korean exports, taking global value chains (GVC) participation into consideration. Using product-level import data from 2000 to 2014, we find heterogeneous effects of importers' SPS and TBT on Korean exports depending on the degree and position of GVC participation. According to the results, trade restrictive effects of SPS and TBT are smaller for industries that are more deeply involved in GVC. However, trade restrictive effects are greater for industries located at a relatively upstream production stage in GVC.

• 대한치과교정학회지
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• 제35권3호
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• pp.163-173
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• 2005

본 연구는 안면비대칭 환자에서 경조직의 비대칭 정도와 연조직 비대칭 정도의 차이를 3차원적으로 밝히고자 시행되었다. 안면비대칭으로 보이는 성인 남녀 34명을 대상으로 두경부 전산단층사진을 촬영하고 3차원 입체영상으로 재구성한 후 기준평면에 대해 비대칭을 나타내는 5개의 계측항목을 경조직에 설정하고, 이에 대응하는 연조직 계측항목을 각각 설정한 후 3차원 계측을 시행하고 경조직과 연조직의 계측항목간 차이를 비교하였다. 이부편위측과 반대측간의 계측치 차이를 비교한 결과, 경조직과 연조직 모두에서 좌우측 계측치간에 통계적으로 유의한 차이가 관찰되었으며 경조직과 연조직의 비대칭 계측항목을 비교한 결과, 6개의 계측항목 모두에서 통계적으로 유의한 차이를 나타내었다. 이부편위를 나타내는 chin deviation, 하악지와 하악골체를 나타내는 frontal ramal inclination difference, frontal corpus inclination difference 항목은 경조직의 비대칭 정도에 비하여 연조직 비대칭 정도가 작게 나타난 반면, 입술경사를 나타내는 lip cheilion height difference, lip canting은 maxillary height difference, occlusal plane canting보다 크게 나타나 입술부위의 비대칭 정도는 하부 경조직의 비대칭 정도보다 큰 것으로 나타났다. 안면비대칭자에서 경조직과 연조직간 비대칭 정도 차이를 규명한 본 연구 결과는 안면비대칭 평가 시 경조직 외에 연조직 계측항목을 이용한 비대칭 분석도 필요함을 시사하였다.

• 한국정보처리학회논문지
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• 제5권5호
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• pp.1311-1319
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• 1998

망의 활용율을 높이고 서비스의 질을 최대한 만족시키기 위하여 피드백을 사용하여 적응적으로 가용한 대역폭을 제공하여 주는 방법과 그 효과에 대한 연구가 활발히 진행 중이다. 이러한 연구는 점 대 점 연결에 적용하기 위한 것으로 시작하여 최근에는 멀티캐스트 서비스를 요구하는 트래픽 전송이 증가함에 따라 점 대 다중점에 적용하는 연구로 확장되고 있다. 피드백에 의해 트래픽을 제어하는 경우 전파 지연이 클수록 제어의 효율성이 떨어지게 되는데 특히 역량 및 폭주 정도가 각각인 다수의 경로 및 수신원이 존재하는 점 대 다중점 연결의 경우는 송신원으로부터의 거리에 따라 수신원들이 송신원에 미칠 수 있는 영향력이 달라질 수 있어 폭주에 반응하는 제어 방법에 따라 공정성의 문제가 야기될 수 있다. 그런데 이와 같이 전파 지연 차이에 의하여 각 수신자가 겪는 서비스 불공정성에 영향을 미칠 수 있는 제어 방법 요인에 대하여서는 연구된 바가 미진하다. 이에 본 연구에서는 시뮬레이션을 통하여 ATM(Asynchronous Transfer Mode)과 같은 고속망의 점 대 다중점 연결에서 폭주가 일어났을 경우 피드백 발생 간격과 스위치에서의 피드백 통합 시기 및 송신원의 출력율 감소폭 조정 정도가 송신원으로부터의 전파 지연차가 큰 경로상에 놓은 수신원간의 불공정성에 어떠한 영향을 미치는지 살펴보았다. 시뮬레이션 결과, 피드백 통합 시기에 따라 불공정성 정도가 달라지고 특히 피드백 간격의 크기가 적을 때 피드백 통합 시기에 따른 불공정성 정도 차가 큼을 볼 수 있었다. 또한 폭주시 송신원의 출력율 감소폭에 따라서도 불공정성 정도가 달라지는데 감소폭을 크게 해 주었을 경우 송신원의 평균 ACR(Allowed Cell Rate) 값은 낮아지고 불공정성은 더욱 심화되었다.

• 한국산림과학회지
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• 제71권1호
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• pp.40-44
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• 1985

본(本) 조사(調査)는 낙엽송(落葉松) 인공성림지(人工成林地)에서, 간벌(間伐)이 가(加)해진 임분(林分)과 가(加)해지지 않은 고정표본구(固定標本區)에서 임목(林木) 개체간(個體間)의 생장상관(生長相關)을 가지고 개체간(個體間)의 경쟁효과(競爭効果)를 알아 보기 위하여 실시(實施)하였다. 1) 조사(調査)는 흉고부위(胸高部位)에서 increment borer에 의하여 채취(採取)된 core에서 연년생장(連年生長)과 총생장(總生長)을 조사(調査)하고 이에 의하여 인접임목개체간(隣接林木個體間)의 상관관계(相關關係)를 계산(計算)해서 확인(確認)하였다. 2) 경쟁효과(競爭効果)의 추정방법(推定方法)은 (1)$^rA_iA_j$, (2)$^rA_i\sum\limits_{k=1}^{n}A_k$, (3)$^rA_i\sum\limits_{k=1}^{n}A_k/R{_k}^2$을 사용(使用)했으며 이 방법(方法) 중(中)에서 $^rA-A_j$가 실용적(實用的)이었다. 3) 상관관계(相關關係)에 사용(使用)된 생장량(生長量)은 반경(半徑)과 단면적(斷面績)의 총생장량(總生長量)을 이용하였으며, 이들 생장량(生長量)의 상관(相關)에서 경쟁(競爭)이 일어나는 정도(程度)를 추정(推定)했다. 4) 식재후(植栽後) 10년까지는 상호경쟁(相互競爭)이 일어나지 않고 인접개체간(隣接個體間)의 상관(相關)은 높은 정(正)의 상관(相關)을 나타냈다. 5) 10년(年) 이후는 매년(每年) 상호(相互) 경쟁(競爭)이 일어나기 시작하다가 13~14년경(年頃)에는 심한 경쟁(競爭)이 일어나고 있는데, 이는 상관계수(相關係數)가 급격히 낮은 수치(數値)로 떨어짐으로써 알 수 있다. 6) 간벌림(間伐林)의 간벌후(間伐後)의 생장(生長)은 인접임목간(隣接林木間)에 제약(制約)없이 정상적(正常的)인 생장(生長)을 나타냈다.

• 대한간호학회지
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• 제26권2호
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• pp.271-280
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• 1996

The purpose of this study was to determine the effect of periodic walking during hindlimb suspension on the mass, relative weight, fiber type distribution and cross-sectional area of Type I and II fibers in the developing Type II plantaris muscle. To examine the effectiveness of periodic walking on mass and fiber size, the hindlimbs of young female Wistar rats were suspended (HS group) and half of these rats walked on a treadmill for 45 min／day(15 min every 4 hours) at 5 meters／min at a 15 degree grade(HS-W group) After seven days of hindlimb suspension, the plantaris muscle wet weight was 28.40％ significantly smaller（P＜0.005） and relative plantaris muscle weight was 26.97％ smaller compared with those of control rats（P＜0.05）. The plantaris muscle wet weight and the relative plantaris muscle weight increased by 46.60％ and 49.23％ respectively with periodic walking, moreover. the plantaris muscle wet weight and the relative plantaris muscle weight of the HS-W rats recovered to the level of the control rats. No change was observed in fiber type percentage of the developing plantaris muscle following one week of hindlimb suspension or periodic walking during hindlimb suspension. Type I and II fiber cross-sectional areas of the developing plantaris muscle were 42.51％ and 43. 68％ lower in the HS group than in the control group（p＜0.0001）, Type I and II fiber cross-sectional areas of the developing plantaris were 30.82％ and 45.97％ greater in the HS-W group than in the HS group（p＜0.0001）, whereas Type I and II fiber cross-sectional area of HS-W group were less than those of the control group（P＜0.0001） The results suggest that periodic walking can attenuate developing plantaris muscle atrophy induced by hindlimb suspension.

• 대한치과교정학회지
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• 제24권1호
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• pp.161-180
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• 1994

This study was performed to investigate the midline having the least difference between the right and left structure among the lines that had been used in the submentovertex analysis and secondarily to know the distribution of asymmetry and it's degree existed normal persons and asymmetric patients. The subjects consisted of 40 normal adult patients and 40 asymmetric adult patients. The computerized analyses from submentovertex cepholometric radiograph were carried out. The results were as follows : 1. The right and left difference of the perpendicular bisecting line between right and left foramen spinosum was larger than the other midlines in the anterior area and it was decreased gradually as it progressed posteriorly. Specially the difference of this line was the smallest in the area where there was foramen spinosum. 2. The right and left difference of the perpendicular line through crista gali to the line between right and left foramen spinosum was smaller than the other midlines in the anterior area and it was increased gradually as it progressed posteriorly. 3. The right and left difference of the line between crista gali and anterior process of atlas was constant and smaller than the other midlines. 4. Asymmetry was a common finding in both normal and asymmetry group and left or right dominance of asymmetry was not statistically singnificant. 5. When the analyses were undertaken after submentovertex radiogram was divided into cranial base, upper face and lower face, the more inferior part showed relative asymmetry than the more superior part.

• 대한기계학회논문집B
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• 제20권7호
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• pp.2277-2288
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• 1996

This study was performed to analyze the cooling effect of heated ribs which are frequently used for cooling of electronic parts, using the numerical method. To prevent the excessive pressure drop due to turbulence promoters for the enhancement of heat transfer rate especially, the effect of the angle of turbulence promoter was investigated by the numerical analysis. Heat transfer rate with turbulence promoters with rectangular cross-section increased by 13% in average, but the coefficient of pressure drop increased by 1.68 times than that without them. In the present study, triangular cross-sectional shape turbulence promoters were suggested and numerically tested. Pressure drop of turbulence promoter with the 30 degree triangular cross-sectional shape decreased by 30% from that of rectangular cross-section promoters while heat transfer rate was almost the same. While with 4 turbulence promoters, the heat transfer rate increased by 21%, the pressure drop increased 4 times. It means that the higher capacity of cooling fan should be needed. With the triangular cross-sectional shape, the size of vortex region at the rear of promoters became considerably smaller, so pressure drop became smaller. The effect of the change of cross-sectional shape was not found in the flow pattern near the ribs, so that heat transfer characteristics in the ribs were not changed.