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본차이나 소지용 인산칼슘 분말의 제조 및 적용에 관한 연구
김윤성,김준이,유중환,김형태,Kim, Yun-Sung,Kim, Juny,Yoo, Jung-Whan,Kim, Hyung-Tae 한국세라믹학회 2004 한국세라믹학회지 Vol.41 No.12
Calcium phosphate powders have been prepared by using $Ca(OH)_2\;and\;H_{3}PO_4$ solution under various conditions such as pH, calcination temperature, and reaction time. ${\beta}-TCP({\beta}-tricalcium phosphate)$and HAp(hydroxyapatite) were synthesized at pH=5.21 and pH > 7.62, respectively. From XRD results, $Ca(OH)_2\;and\;H_{3}PO_4$ solution reacted quickly to form HAp, which was structurally stable up to 16h. Calcination temperature having good crystallinity is revealed to be at $1200^{\circ}C$. SEM analysis showed that ${\beta}-TCP$ and HAp with needle type were synthesized at pH 5.21 and pH 7.62, respectively. However, at pH 9.16, tiny and homogeneous HAp having sphere was prepared and rearranged to show needle morphology. HAp synthesized at pH 9.16 was utilized as bonechina body and calcined. The sample was analyzed its crystallinity, water absorbtion, color, and shape to check physical properties. 수용액의 pH, 소성온도, 반응시간 등을 변화한 조건하에서 $Ca(OH)_2$와 $H_{3}PO_4$ 수용액을 이용하여 인산칼슘계 화합물을 제조하였다. 산성분위기(pH=5.21)에서는 ${\beta}-TCP({\beta}-tricalcium phosphate)$가, pH>7.62에서는 HAp(hydroxyapatite)가 주 결정상으로 관찰되었다. XRD 분석결과, $Ca(OH)_2$와 $H_{3}PO_4$는 빠르게 반응(5분이내)하여 HAp를 생성하였고, 반응 16시간까지 안정적으로 구조를 유지하였다. 우수한 결정성을 나타내는 소성온도는 $1200^{\circ}C$로 관찰되었다. 주사전자현미경(SEM)에 의한 미세구조 관찰 결과, pH가 5.21일 경우 침상 형태의 ${\beta}-TCP$ 입자가, pH 7.62에서는 침상 형태의 HAp가 합성되었다. 그러나 pH 9.16에서는 매우 작고 균일한 구형의 HAp 입자들이 생성되었고, 다시 작은 입자들이 침상으로 재배열된 형상을 관찰할 수 있었다. 합성된 HAp(pH 9.16)를 본차이나 소지에 일정량 혼합하여 본차이나 물성, 즉 결정성, 흡수율, 색도, 파단면의 형상을 측정${\cdot}$분석하였다.
김윤성,정용재,Kim, Yun-Sung,Chung, Yong-Chae 한국세라믹학회 2002 한국세라믹학회지 Vol.39 No.5
본 연구에서는 PVD 공정으로 Si 양자점 형성시 증착조건의 변화가 증착된 양자점 크기와 분포에 미치는 영향을 Monte Carlo법을 응용한 전산모사를 통하여 정량적으로 분석하였다. 전산모사시 PVD 공정에서 일반적으로 제어가 가능한 기판온도, 증착시간, 가스압력과 타겟-기판거리를 공정변수로 선택하였다. 계산 겨로가 증착속도가 0.05 nm/sec이고 기판온도 490${\circ}$, 증착시간 7 sec, 가스압력 3 mTorr, 타겟-기판거리가 8 cm일때 증착 밀도가 $1{\times}10^{12}cm^{-2}$인 Si 양자점 형성이 가능할 것으로 예측되었다. In this study, the effect of the processing parameters in PVD process on the size and the distribution of deposited Si quantum dots was quantitatively investigated by computational simulation utilizing Monte Carlo method. The processing parameters, substrate temperature, deposition time, gas pressure and target-substrate distance were selected as variables since those parameters are often selected as variables in PVD experiments. It is predicted that the density of $1{\times}10^{12}cm^{-2}$ Si quantum dots can be deposited on the substrate when the deposition rate is 0.05 nm/sec at the substrate temperature of 490${\circ}$, deposition time of 7 sec, gas pressure of 3 mTorr and target-substrate distance of 8 cm.
임의형태의 장애물 경계정보를 이용한 최소거리 우회경로 탐색 알고리즘
김윤성,박수현,Kim, Yun-Sung,Park, Soo-Hyun 한국시뮬레이션학회 2010 한국시뮬레이션학회 논문지 Vol.19 No.4
Currently used shortest path search algorithms involve graphs with vertices and weighted edges between each vertex. However, when finding the shortest path with a randomly shaped obstacle(an island, for instance) positioned in between the starting point and the destination, using such algorithms involves high memory inefficiency and is significantly time consuming - all positions in the map should be considered as vertices and every line connecting any of the two adjacent vertices should be considered an edge. Therefore, we propose a new method for finding the shortest path in such conditions without using weighted graphs. This algorithm will allow finding the shortest obstacle bypass given only the positions of the obstacle boundary, the starting point and the destination. When the row and column size of the minimum boundary rectangle to include an obstacle is m and n, respectively, the proposed algorithm has the maximum time complexity, O(mn). This performance shows the proposed algorithm is very efficient comparing with the currently used algorithms.
김윤성 ( Yun Sung Kim ),김현숙 ( Hyun Sook Kim ) 대한내과학회 2015 대한내과학회지 Vol.89 No.6
Ultrasonography (US) is a cost effective diagnostic imaging tool suitable for routine clinical use. High frequency US is a well-established method for both the diagnosis and monitoring of inflammatory arthritis, capable of detecting a wide range of joint pathologies, including effusion, synovitis, and extra-articular abnormalities. However, to ensure an accurate diagnosis, it is also important to consider periarticular disorders that could clinically mimic joint pathology. Such a diagnosis requires special attention to be paid to the periarticular structures, include the tendon, ligament, muscle, and bursa. Due to the close proximity of these structures to potentially affected joints, periarticular inflammation is often clinically misdiagnosed as articular in origin. In these cases, the processes driving pathology are the result of localized inflammation that is secondary to inflammatory arthritis, such as excessive friction or direct trauma. Therefore, when using US to diagnose inflammatory arthritis, it is important to understand the causative pathology of the periarticular disorders, as well as their clinical presentation. (Korean J Med 2015;89:620-631)
PFC용 Boost 컨버터의 금속분말 인덕터에 관한 연구
김윤성(Yun-Sung Kim),안태영(Tae-Young Ahn),장평우(Pyung-Woo Jang),정인범(In-Bum Jeong),최광보(Gwang-Bo Choi) 전력전자학회 2001 전력전자학술대회 논문집 Vol.2001 No.7
In this paper, the experiment and simulation results of the Boost converter for PFC(power factor correction) using metal powder inductor are presented. The metal powder inductor used in the experiment was composed of Ni-Fe-Mo, Ni-Fe, Fe-Si-Al compound respectively. The performance of the 500W class PFC rectifier with the average current mode control and the 300W class PFC rectifier with the variable frequency control, are evaluated.
쌍롤 연속주조 알루미늄 합금 압연 판재의 브레이징 열처리 시 재결정 조직에 미치는 중간 어닐링 온도 및 최종 압연율의 영향
김윤성 ( Yun Sung Kim ),권해욱 ( Hae Wook Kwon ),박종우 ( Jong Woo Park ),김동진 ( Dong Jin Kim ) 대한금속재료학회(구 대한금속학회) 2013 대한금속·재료학회지 Vol.51 No.4
This study investigated the effects of intermediate annealing temperature and final reduction ratio on the recrystallization structure of a twin-roll continuous cast and cold rolled Al alloy after brazing heat treatment. The grain structure after brazing heat treatment of the intermediate-annealed specimen at a lower temperature of 410℃ was coarser than that at a higher temperature of 470℃. The dispersoids of nanometer size particles, which had been absent in the as-cast specimen, were precipitated during the intermediate annealing and significantly influenced the recrystallized grain structure during brazing heat treatment. Even though the grain size of the specimen rolled with a lower final reduction ratio of 30% was a little finer than that with a higher one of 40% after the intermediate annealing, the former was much coarser than the latter after the brazing heat treatment.
Telecom Power용 PFC 회로의 최적설계를 위한 Topology 특성분석 및 성능비교
김윤성(Yun-Sung Kim),정호철(Ho-Chul Jung),정동욱(Dong-Wook Jung),이병국(Byoung-Kuk Lee) 전력전자학회 2011 전력전자학술대회 논문집 Vol.2011 No.7
본 논문은 중, 고용량 통신용 정류기에 적합한 고효율 PFC Topology를 선정하여 특성 및 성능을 비교한다. 선정회로는 Conventional Average Current Mode PFC, Back-To-Back Bridgeless PFC, Semi-Bridgeless PFC, Interleaved PFC 이다. 통신용 1U 표준사이즈의 2㎾ PFC 정류기 제작 및 시험을 통해 각 Topology의 성능 차이점을 확인한다.