• 대한조선학회논문집
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• 제28권1호
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• pp.125-138
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• 1991

본 연구에서는 이상화구조요소법(理想化構造要素法)을 적용하여 좌초시(坐礁時) 이중저구조(二重底構造)의 손상(損傷) 및 강도(强度)를 효율적으로 해석할 수 있는 방법을 개발하였다. 또한 좌초사고(坐礁事故) 발생시에 이중저구조(二重底構造)의 내저판(內底板)이 손상을 받지 않기 위해 필요한 최소한도의 이중저높이, 즉 유효이중저(有效二重底) 높이의 결정법도 제안하였다. 이중저구조모델에 대한 기존의 실험(實驗) 및 탄소성대변형(彈塑性大變形) 유한요소해석(有限要素解析) 결과와 본해석법에 의한 해석결과를 비교하여 본해석법의 정도(精度)와 효율성(效率性)을 확인하였다. 다음으로, 본 해석법을 이중선각(二重船殼) 구조설계개념(構造設計槪念)을 바탕으로 설계된 4만톤급 정유운반성(精油運搬船)의 좌초문제(坐礁問題)에 적용하여 이중저구조의 수직부재(垂直部材) 간격 및 판두께와 이중저높이 등이 좌초시(坐礁時) 손상(損傷)에너지 흡수능력에 미치는 영향을 고찰하였으며, 또한 이들결과를 바탕으로 각 설계인자의 변화에 따른 최소이중저(最小二重底) 높이를 계산하였다.

• Selected Papers of The Society of Naval Architects of Korea
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• 제1권1호
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• pp.76-90
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• 1993

A new propeller series is developed using the newly developed blade section (KH 18 section) which has better cavitation characteristics and higher lift-drag ratio at wade angle-of-attack range than a conventional section. The radial patch distribution of the new series propellers is variable stance they were designed adaptively to a typical wake distribution. Basic geometric particulars of the series propellers. such as chord length, thickness, skew and rake distributions, are determined on the basis of recent full scale propeller geometric data. The series is developed for propellers having 4 blades, and blade area ratios of 0.3, 0.45, 0.6 and 0.75. Mean pitch ratios are varied as 0.5, 0.6, 0.7, 0.95 and 1.1 for each blade area ratio. The new propeller series consists of 20 propellers and is named as the KD(KRISO-DAEWOO)-propeller series. Propeller open-water tests are performed at the towing tank, and cavitation observation tests and fluctuating pressure tests are carried out at the cavitation tunnel of KRISO. $B_{p}-\delta$ curves, which can be used to select the optimum propeller diameter at the preliminary design stage, are derived from a regression analysis of the propeller open-water test results. The KD-cavitation chart is derived from the cavitation observation test results by choosing the local maximum lift coefficient and the local cavitation number as parameters. The cavity extent predicted by the KD-cavitation chart would be more accurate compared to that by an existing cavitation charts, such as the Burrll's cavitation chart, since the former is derived from the cavitation observation test results in a typical ship's wake, while the lather is derived from the test results in a uniform flow.

• 전산구조공학
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• 제4권4호
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• pp.125-133
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• 1991

구조응답이나 상태함수가 음함수(implicit function)형태로 주어지는 복잡한 구조물의 설계감도해석 및 신뢰성해석을 효율적으로 수행할 수 있는 방법을 개발하기 위하여, 먼저 확률 유한요소법을 사용한 확정론적 감도해석 방법을 정식화하고, 이를 바탕으로 MVFOSM, AFOSM 및 SORM등의 2차 모우먼트 방법에 의한 신뢰성 해석을 수행하였으며, 또한 신뢰성에 기초한 최적설계를 수행하는 경우에 필요한 확률론적 설계감도해석 방법을 제시하였다. 수치해석 예로서 박판 구조물의 평면응력문제와 판굽힘문제에 대한 해석을 수행하였는데, 초기 항복이 발생하는 경우를 파괴상태로 정의하였으며, 외부하중, 항복응력, 판두께, 탄성계수 및 Poisson비 등을 확률변수로 다루었다. 모든 경우에 있어서, 본 논문에서 제시한 방법으로 구한 구조응답의 분산이나 파괴확률이 Monte Carlo simulation의 결과와 잘 일치함을 알 수 있었으며, 또한 신뢰성설계시, 확률론적 감도해석결과로부터 확률변수들의 상대적 중요도를 파악할 수 있을 뿐만 아니라, 설계변수(혹은 확률변수)의 평균 혹은 분산계수의 변화에 따른 신뢰성지수의 변화량을 미리 예측할 수도 있다.

• 한국태양에너지학회 논문집
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• 제31권1호
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• pp.37-43
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• 2011

In this paper, the optimized doping condition of crystalline silicon solar cells with $156{\times}156\;mm^2$ area was studied. To optimize the drive-in temperature in the doping process, the other conditions except variable drive-in temperature were fixed. These conditions were obtained in previous studies. After etching$7\;{\mu}m$ of the surface to form the pyramidal structure, the silicon nitride deposited by the PECVD had 75~80nm thickness and 2 to 2.1 for a refractive index. The silver and aluminium electrodes for front and back sheet, respectively, were formed by screen-printing method, followed by firing in 400-425-450-550-$850^{\circ}C$ five-zone temperature conditions to make the ohmic contact. Drive-in temperature was changed in range of $830^{\circ}C$ to $890^{\circ}C$to obtain the sheet resistance $30{\sim}70\;{\Omega}/{\box}$ with $10\;\Omega}/{\box}$ intervals. Solar cell made in $890^{\circ}C$ as the drive-in temperature revealed 17.1% conversion efficiency which is best in this study. This solar cells showed $34.4\;mA/cm^2$ of the current density, 627 mV of the open circuit voltage and 79.3% of the fill factor.

• 한국임상수의학회지
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• 제23권1호
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• pp.55-60
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• 2006

Aucuba japonica has variable pharmacological effects such as hepatoprotective, choleretic, hemodynamic, antimicrobial, and anti-inflammatory activities. This study was performed to investigate the effects of Aucuba japonica extract on oral wound healing. Aucubin was extracted from Aucuba japonica, and injected on either side of buccal mucosa of male mice. Artificial full thickness wounds were made on the site with 1.5 mm biopsy punch under sterile technique. The specimens had taken on day 1, 3, and 5 with 4 mm biopsy punch. Light microscopic examination and quantitative histologic analysis were performed for reepithelization, inflammatory cell infiltration. Reepithelization of the aucubin (0.1%) group was earlier than the control group. And the number of inflammatory cells of the aucubin group was lesser than the control group. In view of the results so far achieved, the aucubin extracted from Aucuba japonica may be useful for oral wound healing and it can be applied as a topical agent on the oral wound. Further research should be performed on the mechanism of aucubin on oral wound healing and proper formulation for effective topical agents.

• 한국지진공학회논문집
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• 제16권2호
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• pp.25-33
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• 2012

본 연구에서는 내력벽 시스템에 대하여 연결보의 단부에 적용이 가능한 박판형 금속감쇠기의 성능을 실험을 통하여 규명하고자 하였다. 박판형 금속감쇠기의 박판 두께와 길이를 변수로 하여 5개 시험체를 제작하였으며, 층간변위비 5%까지 반복하여 횡력을 가력하였다. 실험결과, 금속 박판에 좌굴발생 후 소성변형이 발생하면서 에너지 발산이 이루어졌으며, 기존의 일반 콘크리트 시험체보다 에너지 발산량이 크게 나타났다. 박판의 길이가 짧을수록 전단내력의 값은 증가하였으나 발산에너지의 양의 증가는 크게 나타나지 않았다. 실험 내력을 탄성좌굴해석과 비교한 결과, 해석에 의한 내력은 내력곡선 선형영역의 최대값을 적절히 예측함을 알 수 있었다.

• 대한치과보철학회지
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• 제18권1호
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• pp.37-47
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• 1980

The purpose of this study was to investigate the stresses in different proximal margins and to measure, quantitatively, the effect of different modifications in the design of preparations on the stresses using two-dimensional photoelasticity. Photoelastic stress analysis is based on the phenomenon, exhibited by most transparent solids, of becoming birefringent, or doubly refracting, when strained. Two birefringent materials were used in this study, PSM-1 and PSM-5 in .standard sheet ($10'{\times}10'{\times}\frac{1}{4}'$ thickness), PSM-1(polyester) was used for constructing the substructure, and PSM-5(epoxy resin) was used in making the restorations to be investigated. Two birefringent materials were used in the construction of composite photoelastic model. Seven variable models were constructed. The peripheral dimensions of all model were constant and the models represent an occlusomesial section of a lower posterior molar. Model 1 represents the knife edge margin (shoulderless), Model 2 represents the chamfer, Model 3 represents a rounded shoulder(no sharp angle between the axial wall and gingival floor), Model 4 represents a flat shoulder (axial wall is a $90^{\circ}$ angle to the gingival wall), Model 5 represents $+15^{\circ}$ angulation, Model 6 has a $-15^{\circ}$ angulation, and Model 7 is the same as Model 4 except that it has a $45^{\circ}$ bevel. Improved artificial stone was used to represent dental cement in luting the composite photoelastic model. Static loading procedures(100 pounds) were used at preplanned sites. The results were as follows; 1. The stresses in the proximal portion of all tested models were compressive in nature when the proximal shoulders were loaded vertically on the same proximal marginal ridge. 2. The round and chamfered preparations were the optimum designs in proximoocclusal restorations. They showed the lowest stress concentration factor, i.e. 2.16 and 2.23, respectively. The knife edged shoulder had the highest value, K=5.39. Round type shoulder geometry experiments reduced the stress concentration factor (S.C.F.) 3. The gingival portion of proximal shoulder geometry was a critical location for stress concentration.

• 한국구조물진단유지관리공학회 논문집
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• 제10권6호
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• pp.197-204
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• 2006

최근 시공의 합리화와 경제성의 목적으로 한 다양한 연구가 진행되고 있다. 철근 콘크리트 기둥과 철골 보로 이루어진 RCS 구조의 개발에 대한 연구 역시 활발해지고 있다. RCS 구조 보-기둥 접합부 패널존의 저항기구는 내부패널에서 외부패널로 응력이 전달될 때 직교보의 영향을 받지만, 기존연구에는 직교보의 영향을 고려하지 않고 있다. 본 연구에서는 웨브, 플랜지, 직교보의 두께, FBP의 유뮤등 다양한 변수들을 가지는 5개의 철근콘크리트 기둥과 철골보로 이루어진 보-기둥 내부접합부 실험체의 실험을 통해 직교보들의 영향과 구조적 성능을 조사하고자 한다. 이러한 실험결과들로부터, 보-기둥 접합부의 직교보가 전단내력과 구조성능을 향상시키는데 효과적이라는 것을 알 수 있다.

• 한국표면공학회지
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• 제53권1호
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• pp.9-14
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• 2020

CuS (copper sulfide) thin films having the same thickness of 100nm were deposited on the glass substrates using by radio frequency (RF) magnetron sputtering method. RF powers were applied as a process variable for the growth of CuS thin films. The structural and optical properties of CuS thin films deposited under different power conditions (40-100W) were studied. XRD analysis revealed that all CuS thin films had hexagonal crystal structure with the preferential growth of (110) planes. As the sputtering power increased, the relative intensity of the peak with respect to the (110) planes decreased. The peaks of the two bands (264cm^-1 and 474cm^-1) indicated in the Raman spectrum exactly matched the typical spectral values of the covellite (CuS). The size and shape of the grains constituting the surface of the CuS thin films deposited under the power condition ranging from 40W to 80W hardly changed. However, the spacing between crystal grains tended to increase in proportion to the increase in sputtering power. The maximum transmittance of CuS thin films grown at 40W to 80W ranged from 50 % to 51 % based on 580nm wavelength, and showed a relatively small decrease of 48% at 100W. The band gap energy of the CuS thin films decreased from 2.62eV (at 40W) to 2.56eV (at 100W) as the sputtering power increased.

• 한국정보통신학회논문지
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• 제17권12호
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• pp.2914-2920
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• 2013

본 논문은 동시진공증발법으로 제작된 시편을 $500^{\circ}C$에서 열처리한 시편은 기공이 많이 발생되어 결정결함이 발생 되었어 열처리 시 Se분위기하에서 실행을 해야 된다는 것을 알 수가 있었다. 기판온도를 $430^{\circ}C$, $460^{\circ}C$, $480^{\circ}C$, $500^{\circ}C$로 변화주어 제작된 시편을 열처리 한 결과 결정입자 크기가 증가되어 밀도가 향상되었다. 그리고 XRD 분석결과, 열처리 후에 Cu2Se상이 제거되었으며 열처리 전 후의 흡수지수는 큰 변화가 없었다. 이것은 흡수지수는 열처리보다 시편 두께에 의해 결정된다는 것을 알 수가 있었다.