• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.1674-1678
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• 2008

본 연구에서는 심장의 세포 변화에서부터 혈류 순환의 시스템 변화까지 일련의 과정을 시뮬레이션 할 수 있는 통합모델을 개발하였다. 본 통합 모델을 이용하여 대동맥의 탄성도 변화 따른 Pulse Wave Velocity를 추정하였으며 심근의 수축 Mechanics의 변화를 시뮬레이션 하였다. 심장은 단순한 구 형상으로 모델링 되었다. 특히 동맥순환의 특성인 Wave propagation 과 Wave deflection의 현상을 모델링하기 위해 기존 모델에서 사용된 동맥계 순환 모델을 수정하였다. 즉 기존의 동맥 모델을 1차원의 운동방정식과 연속방정식을 기반으로 하는 Distributed arterial model로 대체하였다. Distributed arterial model은 혈액의 점성에 의한 에너지 손실, 혈관의 점탄성 효과 그리고 분지 되는 혈관에서의 에너지 손실을 포함하는 정교한 동맥 순환 모델이다. 정교한 동맥계 순환 모델의 동맥 탄성도 값을 조절함으로써 탄성도 변화에 대한 PWV를 계산 할 수 있었다. 이러한 수치적 방법을 사용하여 노화에 따른 동맥벽 탄성도의 저하가 심근세포의 Cross-bridge 동역학에 미치는 영향을 시뮬레이션 하였다.

• International Journal of Reliability and Applications
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• 제8권1호
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• pp.111-124
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• 2007

In this paper, we apply insightful statistical reliability tools to manage and seek improvements in the strengths of Oriented Strand Board (OSB). As a part of the OSB manufacturing process, the product undergoes destructive testing at various intervals to determine compliance with customers' specifications. Workers perform these tests on sampled cross sections of the OSB panel to measure the tensile strength, also called internal bond (IB), in pounds per square inches until failure. Additional stiffness strength tests include parallel and perpendicular elasticity indices (EI), which are taken from cross sectional samples of the OSB panel in the parallel and perpendicular directions with respect to the orientation of the wood strands. We explore both graphically and statistically these "pressure-to-failures" of OSB. Also, we briefly comment on reducing sources of variability in the IB and EI of OSB.

• Steel and Composite Structures
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• 제29권4호
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• pp.483-491
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• 2018

Timoshenko beam model is widely exploited in the literature to examine the mechanical behavior of stubby beam-like components. Timoshenko beam theory is well-known to require the shear correction factor in order to recognize the nonuniform shear distribution at a section. While a variety of shear correction factors are appeared in the literature so far, there is still no consensus on the most appropriate form of the shear correction factor. The Saint-Venant's flexure problem is first revisited in the frame work of the classical theory of elasticity and a highly accurate approximate closed-form solution is presented employing the extended Kantorovich method. The resulted approximate solution for the elasticity field is then employed to introduce two shear correction factors consistent with the Cowper's and energy approaches. The mathematical form of the proposed shear correction factors are then simplified and compared with the results available in the literature over an extended range of Poisson's and aspect ratios. The proposed shear correction factors do not exhibit implausible issue of negative values and do not result in numerical instabilities too. Based on the comprehensive discussion on the shear correction factors, a piecewise definition of shear correction factor is introduced for rectangular cross-sections having excellent agreement with the numerical results in the literature for both shallow and deep cross-sections.

• 한국의류학회지
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• 제28권8호
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• pp.1153-1164
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• 2004

The purpose of this study was to knitted nine kinds of single knit and examined mechanical properties and hand to provide the fact that knit, tuck and miss stitch applied to various structure have an effect on hand of weft knitted fabrics. It was good to use tuck stitch rather than miss stitch to increase elasticity of knitted fabrics. As tuck stitch and miss stitch were double or triple overlaps, tensile resilence(RT) decreased by increase of friction contacted among stitch. As cross tuck stitch and cross miss stitch were knitted double or triple, bending rigidity(B), hysteresis of bending moment(2HB) and shearing(G) properties increased by jamming of stitch. As tuck stitch and miss stitch were overlap, thickness increased and they became thicker than miss stitch. Also, as they became thicker by these tuck stitch and miss stitch, compressional energy(WC) increased. It appeared that coefficient of friction(MIU) of cross tuck stitch was larger than coefficient of cross miss stitch. Mean deviation of surface roughness(SMD) had a tendency to be larger as tuck stitch and miss stitch increased. As cross tuck stitch and cross miss stitch were overlaps double or triple, KOSHI and FUKURAMI increased, total hand value(TIV) and NUMERI appeared high in double cross tuck stitch and double cross miss stitch.

• 한국지반공학회논문집
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• 제23권8호
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• pp.59-68
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• 2007

사질토의 직교 이방 탄성계수를 실험적 방법과 개별 요소법을 이용하여 측정하고 결과를 정량적으로 비교-분석하였다. 실내 시험에서는 미소 응력 제어 반복재하시험과 벤더 엘리먼트의 측정 결과를 조합하여 탄성 특성을 구하였으며, 개별 요소법에서는 실내 시험 방법과 상응하는 반복재하시험을 모사하였다. 축 방향 및 전단방향에 관련된 탄성 특성의 비교 결과는 제한된 조건에서도 개별 요소법이 복잡한 실내 시험 과정을 모사할 수 있음을 보여주었다. 방사 방향 재하시험 결과에서 나타난 두 방법 간 차이의 비교 분석 결과는 개별 요소법이 실내 시험으로 구한 개별 측정치의 정량적 타당성을 확인하는데 충분히 활용될 수 있음을 보여준다.

• 자원ㆍ환경경제연구
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• 제22권2호
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• pp.251-279
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• 2013

석유제품은 1997년 이후 석유가격자유화가 시행됨에 따라 1990년대 중반을 기점으로 규제가격에서 시장가격으로 전환된 반면, 전력은 계속 규제가격으로 남아 있다. 이러한 가격규제제도의 차이는 최근에 관찰되고 있는 석유와 전력의 수요행태의 차이, 즉 전력수요의 지속적 증가와 석유소비 정체를 가져온 주요 요인으로 볼 수 있다. 이를 확인하기 위하여 본고에서는 석유제품과 전력의 수요추정식을 바탕으로 1981년부터 2011년 사이 월별 데이터를 10년의 표본기간으로 나누어 1년씩 이동시키는 이동회귀분석(rolling regression)을 통해 탄력성의 변화를 추적했고, 다음과 같은 결과를 확인할 수 있었다. 첫째, 1990년대 중반 이후 휘발유와 경유의 가격탄력성은 더 탄력적으로 변화한 반면, 가정용과 산업용 전력의 가격탄력성은 오히려 더 비탄력적으로 변화하였다. 둘째, 생산(소득)탄력성의 경우에는 석유제품과 전력에서 뚜렷한 패턴차이를 보이지 않고 있으며, 1990년대를 기준으로 나눈 시기별로도 특이한 변화가 나타나지도 않고 있다. 셋째, 휘발유와 경유 간에만 교차탄력성이 유의적으로 추정되었으며, 1990년대 중반 이전에는 휘발유의 교차탄력성이 의미를 가지는 반면, 1990년대 중반 이후에는 경유의 교차 탄력성이 의미를 가지는 것으로 나타났다.

• 대한가정학회지
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• 제27권4호
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• pp.21-39
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• 1989

This paper is to determine the clothing and footwear of urban household consumption expenditures and an analysis of historical data from relevant literature. Particularly, time-series and cross sectional analysis techniques are adopted in analysing the patterns of clothing and footwear consumption expenditures of urban households. Finally, this paper estimates consumption expenditures in the future by comparing these revealed data with the Korea and Japan. Annual Report on the family Income and Expenditure Survey and M.R.A. in S.P.S.S. were used. The results can be summarized as follows: 1. The proportion of the clothing and footwear expenditure has decreased with the increase of income in urban household during 1976-1987. 2.1) Household consumption function by Income group, the Lower group is higher than the other group. 2) Household consumption function by Occupation of household head. Income elasticity estimation in administrative managerial workers is higher than the other group. 3) Household consumption function by Family size. Income elasticity estimation in 6 Persons is higher than the other group. But 4 Persons is higher in 1986. 4) Household consumption function by Age of household head. Income elasticity estimation in 50 Years and over is higher than the other group. 3. Comparison of characteristics of clothing and footwear consumption expenditures in Korea and Japan were M.R.A. Generally, the priority correlation order for Korea is Outwear, Sweaters and Shirt, Other clothing. For Japan, the order is Sweaters and Shirts, Underwear, Services.

• Management Science and Financial Engineering
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• 제20권1호
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• pp.11-16
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• 2014

Extending from Grossman and Stiglitz (1980), we provide an asset pricing model of a synchronously traded cross-listed pair under information asymmetry. Following Garbade and Silber (1983), the model further embraces multi-market price discovery in a dynamic framework. The implications are as follows: The price sensitivity of holdings is higher for informed traders than for uninformed traders; the largest cross-border price spread occurs in the absence of arbitrageurs; price discovery is more likely in markets with a larger population of informed traders; and parity convergence accelerates with a higher price elasticity of demand of arbitrageurs.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제14권2호
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• pp.67-78
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• 2010

An elastic field composed of symmetric cross-ply laminated material is analyzed in roller guided panel. The plane stress elasticity problem is formulated in terms of two displacement parameters with mixed boundary conditions. The numerical solution for two displacement parameters is obtained using a finite element method considering a panel of glass/epoxy laminated composite. Some components of stress and displacement at different sections of panel are displayed. The results makes sure that the formulation developed in this study can be applied to analyze the characteristics of elastic field made of laminated composite under any boundary conditions.

• Steel and Composite Structures
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• 제2권3호
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• pp.195-208
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• 2002

Elasticity solutions to the boundary-value problems of dynamic response under transverse asymmetric load of cross-ply shallow cylindrical panels are presented. The shell panel is simply supported along all four sides and has finite length. The highly coupled partial differential equations are reduced to ordinary differential equations with constant coefficients by means of trigonometric function expansion in the circumferential and axial directions. The resulting ordinary differential equations are solved by Galerkin finite element method. Numerical examples are presented for two (0/90 deg.) and three (0/90/0 deg.) laminations under dynamic loading.