• 한국해양공학회지
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• 제20권6호
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• pp.123-129
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• 2006

The mechanical properties of bellows, such as the extensibility and the strength can be changed depending on the shape. For the shipbuilding material, it is desirable that the fatigue life is long due to the elastic property and the reduction of thermal stress in piping system. Nowadays, the domestic production and design of bellows are based on the E.J.M.A. Code. Therefore, the design standard is in need because of much errors and lack of detailed analysis. In this study, it is attempted to find out the optimal shape of U-type bellows using the finite element analysis. The design factors, mountain height, length, thickness, and the number of convolutions are considered and the proper values are chosen for the simulation. The results shaw that as the number of convolutions reduces, the volume decreases while the stress increases. However, as the number of convolutions increases, the volume increases above the standard volume and the stress obviously increases. In addition, the effect of the thickness of bellows on the stress is very large. Both of the mass and stress are decreasing at a certain lower value region. Also, we investigated shape optimization with considering maximum stress distribution tendency.

• 치과방사선
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• 제28권2호
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• pp.329-338
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• 1998

The authors examined the condylar position and shape of condylar process from the transcranial radiographs and polytomographs of the 130 temporomandibular joints of 65 patients who complained symptoms of temporomandibular disorder and the followings were obtained; 1. The age and sex distribution of the 65 patients showed peak incidence in 2nd decade (27.7％) followed by 3rd (18.5％) and 4th decade (18.5％) and female predominance (87.7％). 2. In polytomography 64 joints (49.2％) showed consistent condylar position from lateral to medial and 39 joints (30.0％) of them showed agreement with those of transcranial radiographs. Among the 66 joints (50.8％) which showed changes in condylar position. 48 joints (36.9％) showed agreement with lateral and central tomographic and transcranial radiographic position. 41 joints (31.5％) showed disagreement in condylar position between the polytomographic and transcranial radiographic images. 3. When the condylar position was classified as anterior, central and posterior. the posterior position was the most frequent position, that is . 42.3％ of the transcranial radiography and 42.3％.49.2％ and 38.5％ of the lateral, central and medial polytomographic radiographs. 4. In polytomography 84 joints (64.6％) showed consistent condylar shape from lateral to medial and 74 joints (56.9％) of them showed agreement with those of transcranial radiographs. Among the 46 joints (35.4％) which showed changes in condylar shape. 40 joints (30.1％) showed agreement with lateral and central tomographic and transcranial radiographic shape. 41 joints (31.5％) showed disagreement in condylar shape between the polytomographic and transcranial radiographic images.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회(1)
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• pp.105-106
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• 2005

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2017년도 추계학술논문요약집
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• pp.105-106
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• 2017

• 한국패류학회지
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• 제31권1호
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• pp.61-67
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• 2015

The occurrence of 'algal bloom', caused by the mass proliferation of phytoplankton, causes serious problems in streams and lakes in Korea. Therefore, in this study, the phytoplankton filter-feeding trait of Unio douglasiae, a type of freshwater clam, was used to reduce the algal bloom in outdoor water tanks during the summer. This involved the construction of a U. douglasiae cultivation apparatus, wherein 1,000 clams were divided into 8 rectangular baskets arranged in the shape of an empty square. The control tank was manufactured in exactly the same shape within the water tank, but without the addition of clams. The algal bloom-reducing effect of U. douglasiae was confirmed by the measurement of (and comparing between) the water quality at the center and periphery of the test and control cultivation apparatus. Water quality measurements included the measurement of water temperature, pH, turbidity, dissolved oxygen (DO) content, and chlorophyll-${\alpha}$ concentrations; the water quality was measured twice a month between June and November 2014.The results of these analyses did not show a significant difference in water quality (temperature, pH, turbidity, DO) between the center and periphery of the test and control tanks. However, the chlorophyll-${\alpha}$ concentration was observed to be much lower at the center of the test tank compared to that at the center and periphery of the control tank, as well as at the periphery of the test tank. This was believed to be a result of the U. douglasiae surrounding the center of the test tank, which prevented the influx of plankton from the periphery. Accordingly, the results of these analyses suggest the possibility that U. douglasiae cultivation could reduce the proliferation of algal blooms in lakes and streams during the summer. In particular, these results indicate possible improvements in U. douglasiae activity (reduction in algal blooms) by their effective arrangement in the water bodies.

• 기록학연구
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• 제23호
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• pp.257-297
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• 2010

미국 정부는 생산하고, 수집하고, 보관하는 정보를 비밀로 분류 관리하는 오랜 역사를 가지고 있다. 독립 이전 식민지 시기에는 특별한 법적 권위 없이 주로 관례적으로 정보에 대한 비밀유지와 접근 제한을 공공연히 행했고, 미국 최초의 헌법으로 간주되는 연맹규약 (Articles of Confederation)의 제정과 연이어 미국헌법 (United States Constitution)이 수립되면서 부터는 명명된 입법적 권위에 기대어 기록의 비밀유지가 행해졌다. 그러나 미국의 비밀기록 체계가 그 기본적인 틀이 형성되기 시작한 것은 미국이 1차 세계대전에 가담하면서 부터였고, 중요한 군사적 외교적 비밀문서의 급증이라는 현실적 요구의 반영이기도 했다. 2차 세계대전을 겪으면서 원자력 개발과 이후 소련과의 냉전체제의 성립은 미국으로 하여금 비밀기록 체계를 한층 강화시키는 계기가 되었고, 이때의 구상은 현재 미국의 비밀기록관리의 정착으로 이어진다. 미국의 비밀기록관리 체제는 특화된 전문 법안 없이 현재까지 냉전시기에 제정된 비밀기록관련 입법적 근거와 일련의 변화를 거듭하는 대통령령(Executive Order)에 의해 관리된다고 볼 수 있다. 이 글은 미국 초기의 역사에서부터 냉전시기까지 미국의 전반적인 비밀기록관리체제를 검토하고자 한다. 이를 위해 미국의 비밀기록관리의 역사를 세 시기로 구분하여 고찰한다: 비밀기록관리의 전통 수립 시기(식민지 시대 ~ 1차 세계대전 직전); 비밀기록 관리체제의 구축 시기 (1차 세계대전 ~ 2차 세계대전 직전); 비밀기록 관리체제의 현재적 구상 시기 (2차 세계대전 ~ 냉전시기). 이러한 시기 구분의 척도는 각 시기가 비밀기록 관련 법령들과 비밀기록관리의 실제 적용방식에 있어 드러낸 차별성이다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 1996년도 춘계학술발표회논문집(3)
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• pp.213-218
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• 1996

Characteristics of high density U-Mo alloy powder prepared by centrifugal atomization have been examined. The results indicate that the majority of the atomized U-Mo alloy particles has a smooth surface and frequently near-perfect spheroidal shape with few satellites attached. The size distribution of atomized U-Mo alloy powder shows the mono-modal size distribution seen in ligament disintegration mechanism. All phases of atomized alloy powder below 150$\mu\textrm{m}$ irrespectively to particle size are found to be ${\gamma}$-U (cubic structure) phases with isotropic structure and not to be U$_2$Mo phase at all. The microstructure of atomized U-Mo alloy particulates has micro-crystalline structure with non-dendritic gram supersaturated with Mo element. Also the grain size of ${\gamma}$ -U tends to decrease with the decrease of the powder diameter.

• 한국통신학회논문지
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• 제10권4호
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• pp.159-167
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• 1985

男性話者가 發音한 韓國語 母音/아, 에, 이, 오, 우/의 聲門波를 직접 抽出하여 音聲에 따라 성문파가 각각 다르다는 것을 확인하였다. 具現한 5가지의 성문파로 母音을 다시 合成하여 聲門波形이 音聲合成에 미치는 영향을 波形的으로 비교하였다. 상문파의 모양, 개방시간과 폐쇄기간에 따라 合成音聲波形은 變化가 있었으며, 聲門波形이 合成音質向上의 중요 factor로 作用함을 알 수 있었다.

• 대한수학회지
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• 제41권3호
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• pp.535-565
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• 2004

In this paper we consider the notion of ξ-invariant or (equation omitted)-invariant real hypersurfaces in a complex two-plane Grassmannian $G_2$( $C^{m+2}$) and prove that there do not exist such kinds of real hypersurfaces in $G_2$( $C^{m+2}$) with parallel second fundamental tensor on a distribution ζ defined by ζ = ξ U(equation omitted), where(equation omitted) = Span ｛ξ$_1$, ξ$_2$, ξ$_3$｝.X>｝.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.488-491
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• 2004

Numerical analysis of the three dimensional turbulent flow field in a complex valve shape is carried out to confirm the flow field whether the designed valve shape is good or not. The simulation of the incompressible flow in a constant flowrate control valve is performed by using the commercial code, FLUENT/UNS 6.0. The results of flow field show the designed valve has some problems, therefore these will be good data for new valve design.