• 한국항해항만학회지
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• 제33권3호
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• pp.235-240
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• 2009

해안철근콘크리트 구조물은 해수 또는 비래염분에 의하여 철근이 부식하게 되고 결과적으로 콘크리트에 균열로 발전하여 성능을 다하게 된다. 본 연구에서는 염해에 대한 해안 철근콘크리트 구조물의 내구성능 평가를 위하여 수치해석에 의한 결정론적 방법이 아니라 확률론에 입각한 성능평가를 위하여 확률론적 시뮬레이션 수법을 구축하였다. 시뮬레이션 수법으로는 몬테카를로법이 적용되었으며, 파괴확률에 대한 설계확률변수(표면염화물 농도, 초기 함유 염소이온농도, 철근의 피복두께, 염소이온 확산계수) 및 각각의 변동계수의 영향을 평가하였다. Fick의 확산방정식을 이용한 해석결과, 해안에서의 거리의 차 및 확산계수의 차에 의한 영향은 컸으며 상대적으로 변동계수의 영향은 그다지 높지 않다는 것을 알 수 있었다.

• 스마트미디어저널
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• 제5권1호
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• pp.114-121
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• 2016

현재 각 의료기관들은 의료정보화 사업을 꾸준히 진행 하고 있다. 의료기관에서 운영하고 있는 대표적인 시스템으로는 전자의무기록, 처방전달시스템 등이 있으며, 의료법에서 전자서명을 허용함으로써 의료정보를 관리함에 있어 비용절감 및 진료정보의 공유가 가능하게 되었고, 공인인증서를 활용한 의료솔루션 사용이 확산되어 가고 있다. 이러한 현실에서 인증서의 역할은 어느 무엇보다 중요하다고 할 수 있지만, 대부분 개인 인증서 관리에는 매우 적극적인 반면, 의료솔루션 등 업무와 관련된 인증서 관리에 대해서는 소홀한 것이 사실일 것이다. 업무용 인증서의 경우 업무PC에 보관하는 경우가 다수이며 이는 보안에 취약할 수밖에 없다. 이에 대한 해결책으로 인증서 서버가 존재하나 별도서버의 구축이 필요하여 중소병원의 경우 비용에 대한 부담이 적지 않을 것으로 판단된다. 본 논문에서는 추가비용을 최소화하여 별도의 인증서 서버를 구축하지 않고 인증서 파일을 BLOB로 저장하여 현재의 자원을 활용한 인증서 관리 및 보안에 효과적인 시스템을 설계 및 구현 하고자 한다.

• 한국실내디자인학회논문집
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• 제18호
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• pp.81-86
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• 1999

The purpose of this study is to find out to meaning and practical use of 'Anbang' of which unique roles and function has not been changed till now since Chosun dynasty. The Study has been carried out by selecting 27 novels in which the word 'Anbang' mentioned frequently and analyzing the sentences with 'Anbang' . The major finding were summarized as follows: 1. Since Chosun dynasty till now, 'Anbang' in most important space for Korean in residential area its meaning and practical use had not been changed. 2. The meaning of Anbang could be categorized into two parts; One was general symbolic meaning which was perceived mentally in general and the other was specific symbolic meaning which was varied by uses. In case of general symbolic meaning 'Anbang' implied a space with light turned on late at night, a very special space from the point of interior decoration and size, a space to keep very important stuffs and a space to deal with very important business. In case of specific symbolic meaning during Chosun dynasty, 'Anbang' was used as a pronoun to imply a mistress as major occupant was a mistress. Since then, gradually, 'Anbang' was used as a pronoun to imply married couple as married couple becomes major occupant. 3. The practical use of 'Anbang' cold be categorized into two; One was routine usage and the other was exceptional usage. The typical routine use were sleeping, dining family gathering, visitor greeting, clothes changing and sewing. The exceptional use were a Sebae(new year's bow), Pyebaek(make a deep bow and offer her gifts to her parents-in-law) and patient curing.

• Tribology and Lubricants
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• 제30권6호
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• pp.337-342
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• 2014

The reduction of drag torque is an important research issue in terms of improving transmission efficiency. Drag torque in a wet clutch occurs because of the viscous drag generated by the transmission fluid in a narrow gap (clearance) between the friction plate and a separate plate. The objective of this paper is to observe the effects of the friction plate area and the clearance on the drag torque using finite element simulation. The two-phase flow of air and oil fluid is considered and modeled for the simulation. The simulation analysis reveals that as the rotational speed increases, the drag torque generally increases to a critical point and then decreases sharply at a high speed regime. The clearance between the two plates plays an important role in controlling drag torque peak. An increase in the clearance causes a decrease in shear stress; thus, the drag torque also decreases according to Newton's law of viscosity. An observation of the effect of the area of contact between transmission fluid and friction plate shows that the drag torque increases with the contact area. The flow vectors inside the flow channel present clear evidence that the velocity of the fluid flows is faster with a larger friction plate, that is, in the case of a larger contact area. Therefore, the optimum size of the friction plate should be determined carefully, considering both the clutch performance and drag reduction. It is expected that the results from this study can be very useful as a database for clutch design and to predict the drag torque for the initial design with respect to various clutch parameters.

• 한국정밀공학회지
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• 제1권3호
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• pp.85-94
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• 1984

The WILDHABER-NOVIKOV gear, one of the circular arc gears, has the large contact area between the convex and concave profiled mating teeth, moves from one end of the tooth to the other axially making a face contact. Hence it provides a large load capacity than the Involute gear and still satisfying the law of gearing. In order to analyze the gear stress, a photoelastic investigation was carried out. Photo elastic model of the WILDHABER-NOVIKOV gears were made of Araldite CT200 in this investigation. For both the many teeth gear and the few teeth gear segments, External gears of all addendum type WILDHABER-NOVIKOV gear and the involute gear were tested. Included were the models with various profile raddi at the same pressure angle 20 .deg. and module 13.5. The flank stresses and fillet stresses of these gears were observed in each case and compared with those of gears. From this investigation, the following results were obtained. A. In the case of having many teeth gear: As the profile radius is increased, the fillet stresses of the WILDHABER-NOVIKOV gear become the same or less than that of the INVOLUTE gea, and the flank stress becomes smaller than that of the INVOLUTE gear. Therefore the better design condition is satisfied with a large profile radius. B. IN the case of having a few teeth gear: As the profile radius is increased the flank stress of WILDHABER-NOVIKOV gear becomes smaller than that of the INVOLUTE gear, but the fillet stresses become larger than that of the INVOLUTE gear. Therefore the larger design condition is satisfied with small profile radius.

• 대한기계학회논문집B
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• 제30권3호
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• pp.278-286
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• 2006

Experiments were conducted to estimate the performance of drag force type vertical axis wind turbine with an opening-shutting rotor. It was operated by the difference in drag force generated on both sides of the blades. The rotational speed was measured by a tachometer in a wind tunnel and the tunnel wind speed was measured by using a pilot-static tube and a micro manometer. The performance test for a prototype was accomplished by calculating power, power coefficient, torque coefficient from the measurement of torque and rpm by a dynamometer controller. Various design parameters, such as the number of blades(B), blade aspect ratio(W/R), angle of blades$(\alpha)$ and drag coefficient acting on a blade, were considered for optimal conditions. At the experiment of miniature model, maximum efficiency was found at N=15, $\alpha=60^{\circ}$ and W/R=0.32. The measured test variables were power, torque, rotational speed, and wind speeds. The data presented are in the form of power and torque coefficients as a function of tip-speed ratio V/U. Maximum power was found in case of $\Omega=0.33$, when the power and torque coefficient were 0.14 and 0.37 respectively. Comparing model test with prototype test, similarity law by advance ratio for vertical axis wind turbine was confirmed.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2017년도 학술발표회
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• pp.329-329
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• 2017

In this study attempted to evaluate the stability of the protection methods by examining hydraulic characteristics of the area around the point in which marine cable protector is installed such as surf zone occurrence point of shore-end submarine cables suitable for coastal marine environmental conditions, flow rate t the tope of the protector and maximum wave height, and to provide basic data for the selection of the optimal protection method. In performing hydraulic model experiments, the topography of submarine cable installation location was reproduced in 2-D sectional channel, and models appropriate for experimental scale and similitude law were produced and installed for each condition of submarine cables and protectors. Since the topography and submarine cable protectors were reproduced and installed in 2-D sectional channel, the exact reproduction of surf and transformation in shallow water zone was possible, and thus the physical properties could be clearly analyzed. For stability review, an experiment to examine the stability was conducted using a wave maker with 50-year frequency design waves as target, and wave height and cycles were applied based on the approximate lowest low water level(Approx. L.L.W), which is the most dangerous in submarine cable protection methods. As for experimental time, typhoon passing time in summer (about 3 hours) was applied, and wave patterns and deviation ratio of the submarine cable protector were investigated after making irregular waves corresponding to design waves. In addition, current meter and wave height meter were installed at the installation location of the submarine cable protector, and the flow rates and wave height at the top of the protector were measured and analyzed to review hydraulic properties.

• Journal of the Optical Society of Korea
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• 제17권4호
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• pp.336-343
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• 2013

Recently various types of driver assistance systems have been used for automobiles. In 2008, the U.S Congress passed a law which required that most cars be equipped with devices to warn objects behind the vehicle. Because of that, market of rear view cameras is expected to rise dramatically. Therefore many suppliers try to provide a wide angle camera for car makers. But a high distortion is caused by the wide angle might result in lower image quality. In order to improve the image quality, normally we use an algorithm to correct a distortion. Though we can improve the distorted image by correction algorithm, we must pay more cost to use it. In this paper, we propose a new optical system reducing a distortion in contrast to a conventional lens without cost. In other words, we can see only an area of interest. That is similar to reducing a field of view. Using a new optical system, we can get a less distorted image. In order to view an area of interest, we introduce an off axis optical system having refractive surfaces and reflective surfaces. In this paper, we describe the results of design and, evaluation of an off axis wide angle compact imaging system. In comparison to conventional wide angle lens, we can get the improvement of MTF, distortion, and lateral color aberrations. And we also can reduce a total cost because we don't need the outer apparatus or bracket to mount on the car.

• 복식문화연구
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• 제27권5호
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• pp.415-432
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• 2019

The purpose of the present study was to generate a list of business ethics components according to business area for small and medium-sized fashion companies. Based on the literature review, 21 components of business ethics components were identified within five business areas. Ten CEOs(Chief Executive Officers) each participated in an in-depth interview, sharing ethical and unethical cases from their own businesses. Constant comparative analysis was used to generate important business ethics components from those cases. In results, important business ethics components for each business area are: 1) using human-friendly materials, strengthening sustainable technologies, using vegan materials, concerning safe process, and reducing waste in the material production and sourcing area, 2) enhancing an efficiency in design, developing recycle/reuse designs, avoiding to copy designs, and using messages for public interest in the product design area, 3) concerning fair-trade, reducing harmful substance, saving energy, and using ethical supply channels in the distribution and logistics area, 4) acquiring certifications, promoting consumer protection, avoiding exaggerative/false advertisements, and promoting social contributions in the management and marketing area, and 5) promoting workers' rights, complying with the law, and investing on employee educations in the labor management area. All of the ethical and unethical cases of the ten companies have involved aspects of the 21 components, thereby enhancing understandings on how each issue is being seriously considered and/or handled in the small and medium-sized fashion companies. Study findings may provide a basis for development of a research model for quantitative studies and/or educational programs related to business ethics in the fashion industry.

• 한국정보통신학회논문지
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• 제25권10호
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• pp.1403-1408
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• 2021

AI 프로세서를 FPGA 기반으로 구현하는 연구가 최근 활발하게 진행되고 있다. Deep Convolutional Neural Networks (CNN) 는 AI 프로세서가 수행하는 기본적인 연산 구조로서 매우 방대한 양의 곱셈을 필요로 한다. CNN 추론 연산에서 사용되는 곱셈 계수는 상수라는 점과 FPGA 은 특정 계수에 맞춰진 곱셈기 설계가 용이하다는 점에 착안하여 곱셈기를 최적화 구현할 수 있는 방법을 제안한다. 본 방법은 2의 보수와 분배법칙을 활용하여 곱셈 계수에서 값이 1인 비트의 개수를 최소화하여 필요한 적층 덧셈기의 개수를 절감한다. CNN 을 FPGA 에 구현한 실제 예제에 본 방법을 적용해본 결과 로직 사용량은 최대 30.2%까지, 신호 전달 지연은 최대 22%까지 줄어들었다. ASIC 전용 칩으로 구현할 경우에도 하드웨어 면적은 최대 35%까지, 신호 전달 지연은 최대 19.2%까지 줄어드는 것으로 나타났다.