• 한국전산구조공학회논문집
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• 제15권3호
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• pp.433-440
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• 2002

본 연구에서는 균일한 인장과 굽힘을 받는 반무한 평판내의 분기균열에 대하여 해석하였다. 중첩의 원리를 이용하여 인장과 굽힘을 받는 분기균열에 대하여 응력 및 모멘트 확대계수를 해석하였다. 응력확대계수는 유한요소법과 J 기저 상호매개적분을 이용하여 해석하였고, 모멘트확대계수는 균열선단의 모멘트로부터 모멘트외삽을 이용하여 계산하였다 무차원화된 응력확대계수와 모멘트확대계수에 대한 수치해석 결과는 분기균열 길이와 주균열의 비, 그리고 분기균열각의 함수로 나타내었다.

• Structural Engineering and Mechanics
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• 제37권1호
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• pp.95-110
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• 2011

This paper presents a tri-uniform bond stress model for predicting the lap splice strength of reinforcing bar at the critical bond splitting failure. The proposed bond distribution model consists of three zones, namely, splitting zone, post-splitting zone and yielding zone. In each zone, the bond stress is assumed to be constant. The models for bond strength in each zone are adopted from previous studies. Combining the equilibrium, strain-slip relation and the bond strength model in each zone, the steel stress-slip model can be derived, which can be used in the nonlinear frame analysis of the column. The proposed model is applied to derive explicit equations for predicting the strength of the lap splice strengthened by fiber reinforced polymer (FRP) in both elastic and post-yield ranges. For design purpose, a procedure to calculate the required FRP thickness and the number of FRP sheets is also presented. A parametric investigation was conducted to study the relation between lap splice strength and lap splice length, number and thickness of FRP sheets and the ratio of concrete cover to bar diameter. The study shows that the lap splice strength can be enhanced by increasing one of these parameters: lap splice length, number or thickness of FRP sheets and concrete cover to bar diameter ratio. Verification of the model has been conducted using experimental data available in literature.

• 대한의용생체공학회:의공학회지
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• 제43권1호
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• pp.35-44
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• 2022

Immersed boundary-Lattice Boltzmann Method (IB-LBM) is used for the analysis of flow over the circular cylinder in the concept of fluid-structure interaction analysis (FSI). Recently, IB-LBM has shown the enormous possibility for the application of various biomedical engineering fields, such as the movement of a human body or the behavior of the blood cells and/or particle-based drug delivery system in blood vessels. In order for the numerical analysis of the interaction between fluid and solid object, immersed boundary method and lattice Boltzmann method are coupled to analyze the flow over a cylinder for low Reynolds laminar flow (Re=10, 20, 40 and 100) with Zhu-He boundary condition at the boundary. With the developed IB-LBM, the flow around the cylinder in the uniform flow is analyzed for the laminar flow and the drag and lift coefficients and recirculation length are compared to the previous results.

• 한국지역사회생활과학회지
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• 제17권3호
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• pp.15-28
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• 2006

This study is on the kindergarten uniforms in Changwon, south Gyeongsang province. The first part of this research is on whether or not students should wear uniforms and how often they should wear uniforms. The research also deals with what types of uniforms are required, how much they should cost and their size. Fifty one preschools including kindergarten and nursery were targeted for this research. The second part of the research is on the discrepancy of the labeled size and the actual size of the child. The results of the first part are as follows: A total of 46 out of 51 places adopted uniforms for their children. Sports wear style is the most popular for spring, fall and summer uniforms. For wearing frequency of kindergarten uniforms, 26 (61%) places allowed the students to wear uniforms for special events such as picnics or observation trips 17(34%) places had the students wear their uniforms on a daily basis and 2 3 times only wearing a week.'rho preschool children interviewed for this study were from 2 to 5 in lull age. However, sizes with high frequency rates were 9 to 11 and the supplied sizes of uniforms were from 5 to 17. The results of the second part are as follows: The bust girth and the shoulder width of upper garments of uniforms are bigger than children's physical size, while clothes length and sleeve length are relatively shorter. Also the bust girth of upper garments of uniforms differs in the size depending on each preschool. The waist girth and the total length of lower garments of uniforms are made smaller than children's physical sizes, while hip girth is relatively larger. In the case of lower garments, the rest parts of cloth length are smaller than upper garments of uniforms. Also, the waist girth and hip width of uniforms are smaller than those of lower garments In summer garments, while thigh width is similar in both cases. The waist width is made too small. Described in the above excluding the waist width, the rest parts are relatively larger than children's physical sizes, but shorter in the length. Due to the length, children at age 7 may wear uniforms in the level of 17. Since summer uniforms touch the students' bare skin, the rest parts excluding clothes length are shorter than these of the spring and fall uniforms. In the case of clothes length, it seems to be due to different designs. The waist width of lower garments in all the uniforms tested in this study is too small for children, requiring them to be made in a larger size.

• Elastomers and Composites
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• 제49권4호
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• pp.275-283
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• 2014

건축용 접착제로 활용되고 있는 부틸고무는 주로 시트의 형태로 사용된다. 본 연구에서는 컴퓨터 해석을 통해 부틸고무 시트 압출용 다이를 설계하였다. 압출용 다이의 내부는 크게 매니폴드와 랜드로 나뉜다. 매니폴드는 다이중앙에서 유입되는 재료가 폭 방향으로 흐름이 이루어 지도록 하는 역할을 한다. 랜드는 재료가 흐름 방향으로 균일하게 흐르게 하여 균일한 두께의 시트가 성형되도록 한다. 다이는 매니폴드와 랜드 외에도 아일랜드를 설치하여 흐름의 안정을 주도록 하는 경우가 많다. 본 연구에서는 컴퓨터 해석을 통하여 다이에서 매니폴드의 각도와 길이, 랜드 길이 그리고 아일랜드를 설계 변수로 하여 다이 출구에서 다이 폭 방향으로 균일한 흐름이 형성되도록 하는 최적의 다이형상을 연구하였다.

• 한국가정과교육학회지
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• 제19권2호
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• pp.103-114
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• 2007

본 연구의 목적은 여자 고등학생의 교복변형에 대한 학생의 태도를 분석함으로써 청소년들의 교복변형행동에 영향을 미치는 요인을 파악하고, 청소년들에게 만족스러우면서도 유행흐름에 부합하는 교복을 제안할 수 있도록 기여하는데 있다. 본 연구의 결과를 요약하면 다음과 같다. 첫째, 학생의 교복착용에 대한 태도를 살펴본 결과, 교복착용에 대해서는 찬성하는 것으로 나타났으며, 찬성의 이유로는 또래집단과의 동질성을 들었다. 둘째, 교복만족에 대한 학생의 태도를 분석한 결과 대체로 만족이 불만족보다 높은 것으로 나타났으며, 특히 디자인에 대한 만족도가 높았다. 셋째, 교복변형경험을 묻는 질문에서 대부분의 학생이 교복변형 경험이 있는 것으로 분석되었으며, 교복 상의의 경우 주로 품과 길이를 줄여 입으며, 하의의 경우 스커트 길이를 늘이고 주름을 뜯어 늘여 입는 것으로 분석되었다. 넷째, 심층면접을 통해 교복변형의 원인을 조사한 결과, 크게 미적욕구 충족을 위한 변형, 유행을 따라가기 위한 변형, 맞음새를 위한 변형, 실용성을 위한 변형으로 분류되었으며, 미적욕구충족을 위해 변형한다는 의견이 가장 많았고, 맞음새를 위한 변형, 유행을 따르기 위한 변형 순으로 나타났다. 교복 디자인시 고려사항으로는 '맞음새'를 가장 많이 선택하였으며, '디자인', '활동성' 순이었다. 이상과 같이 각급 학교에서는 학생의 의견을 교복선정에 적극 활용하여 학생들의 교복변형을 줄이고, 학생뿐 아니라 교사 학부모들도 모두가 만족하는 교복을 만들기 위한 다각적인 노력이 필요하리라 여겨진다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 1997년도 제15회 KOSCO SYMPOSIUM 논문집
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• pp.103-112
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• 1997

In the combustion of the pulverized coal compared with that of liquid fuel or gaseous fuel, serious pollutants such as ash, $NO_x$ and $SO_x$ are released to surroundings. The objective of this study is the reduction of such pollutants in the combustion process. The modeling of cyclone combustor which uses the method of two stage combustion was carried out. The main burner length, scattering angle and air/fuel ratio were considered as parameters. The results show that the shorter the main burner length is, the less the amounts of coals which exit the combustor directly are, but the scattered input of coal is required anyway in order to collect all ashes. It is recommended that the shorter the main burner length is, the less the scattering angle is. And in the case of the scattered input compared with no scattering, the temperature in the combustor is more uniform and the amount of volatile is more reduced.

• Structural Engineering and Mechanics
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• 제63권3호
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• pp.385-400
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• 2017

This paper presents an experimental study on the behavior of axially-loaded steel RHS (rectangular hollow section) compression members that are partially reinforced along their lengths with welded steel plates. 28 slender column tests were carried out to investigate the effects of the slenderness ratio of the unreinforced member and the ratio of the reinforced length of the member to its entire length. In addition to the slender column tests, 14 stub-column tests were conducted to determine the basic mechanical properties of the test specimens under uniform compression. Test results show that both the compressive strength and stiffness of an RHS member can be increased significantly compared to its unreinforced counterpart even when only the central quarter of the member is reinforced. Based on the limited test data, it can be concluded that partial reinforcement is, in general, more effective in members with larger slenderness ratios. A simple design expression is also proposed to predict the compressive strength of RHS columns partially reinforced along their length with welded steel plates by modifying the provisions of AISC 360-10 to account for the partial reinforcement.

• International Journal of Aeronautical and Space Sciences
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• 제9권1호
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• pp.1-30
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• 2008

When the stagnation temperature of a perfect gas increases, the specific heats and their ratio do not remain constant any more and start to vary with this temperature. The gas remains perfect; its state equation remains always valid, except, it is named in more by calorically imperfect gas. The aim of this work is to trace the profiles of the supersonic axisymmetric Minimum Length Nozzle to have a uniform and parallel flow at the exit section, when the stagnation temperature is taken into account, lower than the dissociation threshold of the molecules, and to have for each exit Mach number and stagnation temperature shape of nozzle. The method of characteristics is used with the algorithm of the second order finite differences method. The form of the nozzle has a point of deflection and an initial angle of expansion. The comparison is made with the calorically perfect gas. The application is for air.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2001년도 가을 학술발표회 논문집
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• pp.175-182
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• 2001

Effective length factor approach for framed column design has long played an important design-aid role. This approach, however, is effective only when the columns are in the form of prismatic or uniform cross sections. Structural engineers who have to design or analyse framed columns with variable cross sections need some means to do their job. By using the finite element method, the stability analysis of the isolated compression members with variable cross sections and that of the framed columns are performed. The parameters considered in the stability analysis are taper and sectional property parameters of the columns, the second moment of inertia ratio of beam to column, and beam span to column height ratio. On the basis of the stability analysis results, effective length factor formulas for the columns with variable sections are derived.