• Journal of Advanced Marine Engineering and Technology
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• 제27권2호
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• pp.299-304
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• 2003

Static mixer consists of a straight pipe of circular cross section into which individual elements are inserted to cut, fold, twist and re-combine the mixing fluid. The number of elements and their shape required in any application depend on the complexity of the mixing process. The objectives of this study are to develop a new static mixer and to perform the experimental investigation of pressure drop in order to evaluate the performance of the new one. The mixing fluid used is Glycerin. The pressure drop is measured using a hydraulic manometer and the correlation of Z-factor is suggested as a function of Re. The Z-factors of SSC and YNU mixer are about 40% lower than and 4% higher than that of the Sulzer one.

• Coupled systems mechanics
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• 제6권1호
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• pp.55-74
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• 2017

The evaluation of torsional effects on multistory buildings remains an open issue, despite considerable research efforts and numerous publications. In this study, a large number of multiple test structures are considered with normally distributed topological attributes, in order to quantify the statistically derived relationships between the torsional criteria and response parameters. The linear regression analysis results, depict that the center of twist and the ratio of torsion (ROT) index proved numerically to be the most reliable criteria for the prediction of the modal rotation and displacements, however the residuals distribution and R-squared derived for the ductility demands prediction, was not constant and low respectively. Thus, the assessment of the torsional parameters' contribution to the nonlinear structural response was investigated using artificial neural networks. Utilizing the connection weights approach, the Center of Strength, Torsional Stiffness and the Base Shear Torque curves were found to exhibit the highest impact numerically, while all the other torsional indices' contribution was investigated and quantified.

• 한국안전학회지
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• 제12권4호
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• pp.220-229
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• 1997

곡선보(curved beam)의 등분포 하중하에서 평면내(in-plane)와 평면의(out-of-plane)의 좌굴(buckling)을 해석하는데 differential quadrature method (DQM)을 이용하여 다양한 경계조건(boundary conditions)과 굽힘각(opening angles)에 따른 입계하중(critical loads)을 계산하였다. DQM의 해석결과는 해석적 해답(exact solution) 또는 다른 수지해석 결과와 비교하였으며, DQM은 적은 요소(grid points)를 사용하여 정확한 해석결과를 보여주었다. 두 경계조건(고정-고정, 고정-단순지지)하에서 새로운 결과를 또한 제시하였다.

• 한국소음진동공학회논문집
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• 제20권5호
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• pp.492-501
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• 2010

Equations of motion of thin-walled composite H-type cross-section beams incorporating a number of nonclassical effects of transverse shear and primary and secondary warping, and anisotropy of constituent materials are derived. The vibrational characteristics of a composite thin-walled beam exhibiting the circumferentially asymmetric stiffness system(CAS) and the circumferentially uniform stiffness system(CUS) are exploited in connection with the bending-transverse shear coupling and the bending-twist coupling resulting from directional properties of fiber reinforced composite materials.

• 호남수학학술지
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• 제32권1호
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• pp.45-51
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• 2010

Let A be an abelian variety defined over a number field K and let L be a cyclic extension of K with Galois group G = <${\sigma}$> of order n. Let III(A/K) and III(A/L) denote, respectively, the Tate-Shafarevich groups of A over K and of A over L. Assume III(A/L) is finite. Let M(x) be a companion matrix of 1+x+${\cdots}$+$x^{n-1}$ and let $A^x$ be the twist of $A^{n-1}$ defined by $f^{-1}{\circ}f^{\sigma}$ = M(x) where $f:A^{n-1}{\rightarrow}A^x$ is an isomorphism defined over L. In this paper we compute [III(A/K)][III($A^x$/K)]/[III(A/L)] in terms of cohomology, where [X] is the order of an finite abelian group X.

• 산업공학
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• 제11권2호
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• pp.93-106
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• 1998

This paper suggests a stereo vision-based algorithm for the 3-dimensional inspection of a crimped terminal. The crimped terminal is one of wire harness assemblies which transmit current or signals between a pair of electrical or electronic assemblies. Four types of nonconformities considered includes terminal rolling, band up/down, twist, and crimp height. To obtain stereo image correspondence, an algorithm using Hough transform is proposed. Coordinate transform is then applied to evaluate the degree of 3-dimensional nonconformities. The algorithm has been successfully tested on a number of real specimens collected from a wire harness factory. The test results show the feasibility of the proposed algorithm.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 춘계학술대회 논문집
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• pp.357-360
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• 2008

In roll forming process, a sheet metal is continuously progressively formed into a product with required cross-section and longitudinal shape, such as a circular tube with required diameter, wall-thickness and straightness, by passing through a series of forming rolls in arranged in tandem. In this process, each pair of forming rolls installed in a forming machine play a particular role in making up the required cross-section and longitudinal shape of the product. In recent years, that process is often applied to the bumper rail in the automotive industries. In this study, a optimal SILL SIDE manufacturing technology, model deign and proper roll-pass sequences can be suggested by forming number of roll-pass and bending angle. And also effects of the process parameters on the final shape formed by roll forming defects were evaluated.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.821-825
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• 2000

Drawing is one of the oldest metal forming operations and has major industrial significance. This process allows excellent surface finishes and closely controlled dimensions to be obtained in long products that have constant cross sections. In drawing of the high carbon steel wire, exit speeds of several hundreds meters per minute are very common. Drawing is usually conducted at room temperature using a number of passes or reductions through consequently located dies. In multi-stage drawing process like this, temperature rise in each pass affects the mechanical properties of final product such as bend, twist and tensile strength. In this paper, therefore, to estimate the wire temperature in multi-stage wire drawing process, wire temperature prediction method was mathematically proposed. Using this method, temperature rise at deformation zone as well as temperature drop between die exit and the next die inlet were calculated.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2009년도 추계학술대회 논문집
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• pp.297-300
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• 2009

The roll forming process is often used to manufacture long, thin-walled products such as a pipe. The final cross-section is a comparatively simple open-channel, a closed tube section or a complex profile with several bends. In recent years, that process is often applied to the bumper beam in the automotive industries. In this study, a optimal Center Floor Cross Member manufacturing technology, model deign and proper roll-pass sequences can be suggested by forming number of roll-pass and bending angle, and also effects of the process parameters on the final shape formed by roll forming defects were evaluated.

• 헤리티지:역사와 과학
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• 제51권4호
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• pp.84-107
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• 2018

첨모직은 표면에 짧은 파일이 나타나는 것으로 조선시대 후기에는 첨모직 깔개를 지칭하는 용어로 채담이 사용되었으며, 20세기 초에는 융전과 단통, 양탄자 등으로 불리었다. 조선 말기 이후의 여러 문헌이나 신문기사, 그리고 각종 사진자료를 통해 첨모직 깔개가 왕실뿐만 아니라 일반인도 사용하였고 당시 국내에서 제작하였다는 것이 확인되었다. 본 연구에서는 조선 말기 이후의 첨모직 깔개 6점을 실물 조사하였는데 5점은 페르시아매듭의 컷파일이며 1점은 루프파일의 기법으로 제작되었다. 컷파일의 깔개는 크기가 가로 72~98 ${\times}$ 세로 150~156cm의 직사각형이며, 나비, 사슴, 호랑이, 그리고 십장생 등의 주 무늬를 중앙에 배치하고 卍자를 가장자리에 배치하였다. 컷파일의 소재는 지경사는 모두 면사이며 지위사는 3점은 면사, 1점은 모사, 그리고 1점은 면사와 비스코스레이온의 혼섬사이다. 지위사는 4점이 S꼬임의 실 여러 올을 합쳐 Z방향으로 합사한 실을 사용했다. 파일위사는 4~6가지의 색이 사용되었는데 홍색을 제외하고 모두 염색을 하지 않은 자연색 그대로의 모섬유가 사용되었다. 그리고 S나 Z꼬임의 모사를 2올 이상 합하여 반대방향으로 꼬임을 주었는데 굵기에 맞춰 올수를 합하였다. 깔개의 위아래 가장자리는 위사를 6올 이상 넣고 남은 지경사는 몇 올씩을 한데 묶어서 정리하였으며, 좌우 가장자리는 3올 이상의 면사를 가운데 놓고 수평으로 감아 마치 둥근 막대처럼 만들며, 가장자리에서 2~3번째 지경사를 징거서 튼튼하게 고정하였다. 루프파일은 경사방향으로 고리를 만든 경첨모직이며 지경사와 지위사는 면사, 파일경사는 모사로 추정된다. 소재의 성분 분석이 가능했던 깔개는 3점으로 파일위사는 판단이 불명한 것을 제외하고 염소와 비미종 양으로 판명되어 첨모직 깔개에 다양한 종류의 동물털이 사용되었을 가능성이 있다고 본다. 본 연구에서 조사한 6점의 깔개는 1800년대 말부터 1900년대 초에 제작되었다고 추정된다. 깔개의 정확한 제작지는 확인할 수 없었으나 당시 국내에서 첨모직 깔개를 제작하고 있다는 문헌기록과 깔개의 문양의 조형성을 고려한다면 우리나라에서 제작된 것으로 본다.