• 한국주조공학회지
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• 제35권3호
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• pp.62-66
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• 2015

Tape casting is an important forming operation used to prepare flat sheets in the various industries. In this study, Doctor Blade tape casting of In-based low melting point alloy was carried out. The purpose of this investigation was to determine the possibility of applying the Doctor Blade tape casting process to the manufacture of low melting point alloy sheets that can be used as thermal fusible parts of battery safety systems. In-based molten alloy that has a melting point of $95^{\circ}C$ was produced; it's viscosity was measured at various temperatures. The molten alloy was used as a slip in the caster of the Doctor Blade tape casting system. The effects of the molten alloy temperatures and carrier speeds on the produced sheet shape were observed. For the casting conditions of 1.5 cm slip height, $120^{\circ}C$ slip temperature, 0.05 mm blade gap and 60 m/min. carrier speed, an In-based alloy thin tape well shaped with 0.16 mm uniform thickness was continuously produced.

• 한국안전학회지
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• 제24권4호
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• pp.82-89
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• 2009

Unlike concrete bridge, steel bridge resists external force by forming thin plate. Thus, because steel girder bridge has big slenderness ratio, buckling is a major design factor. Plate girder consists of flange and web plate. Because of economic views, web plate that resists shear forces is made by more thinner plate. Thus, web plate has much risk for buckling. The objective of this study is to analyze the buckling behaviors of plate girder and to present the proper reinforcement location of longitudinal stiffeners. Various parametric study according to the change of web height, transverse stiffeners and load condition are examined.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 제2회 박판성형심포지엄 논문집 박판성형기술의 현재와 미래
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• pp.171-182
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• 1998

An automated surface-strain measuring system using the image processing technique is developed in the present study, which consists of the hardware to capture and to display digital images, and the software to calculate the 3D informations of grid points from two views. New or improved algorithms the mapping and establishing correspondence of grid points and elements, the camera calibration, and the subpixel measurement of grid points, are implemented. As an application of the present system the surface-strains of deformed blanks in the limitting dome height test, the square cup deep-drawing and punch stretching to obtain the forming limit diagram are measured. The results are compared with those obtained by conventional manual methods.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2005년도 춘계학술대회 논문집
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• pp.258-261
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• 2005

In this paper, experimental and numerical attempts are made fur application of powder metallurgy forming technology to making the cylinder block of a hydraulic pump of which height reaches nearly 70 mm and is ten times larger than the wall thickness. Leak tests with several compositions are carried out in order to find allowable powder composition to prevent leak under high pressure in service and CAE techniques are applied to finding proper process conditions. Through the research, the possibility of the powder formed cylinder block that is very competitive from the point of both cost and mass production has been shown, even though its thickness exceeds the recommended limit considering heterogeneous density distribution caused by the friction between a powder compact and dies.

• 소성∙가공
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• 제32권6호
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• pp.376-383
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• 2023

The torsion bar, which is a steering torque sensor, is mounted between the steering pinion and the input shaft in the IPA(input pinion assembly). Accurate torque measurement is important to improve the sense of operation, and the straightness of the torsion bar can affect torque measurement. In this study, the amount of bending was measured and the exact shape was analyzed regarding the bending phenomenon in the press-fitting process for torsion bars. The effect of alignment error was analyzed through finite element forming analysis. Process data analysis was conducted for the double-end press fit model. If there is an alignment error of about 10% of the serration tooth height, the indentation load is reduced by about 10%. If there is an alignment error, the torsion bar is rotated.

• Wind and Structures
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• 제30권5호
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• pp.525-532
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• 2020

This work numerically investigates the effects of Reynolds number Re_D (= 100 - 150), cross-sectional aspect ratio AR = ( 0.25 -1.0), and attack angle α (= 0° - 90°) on the forces, Strouhal number, and wake of an elliptical cylinder, where Re_D is based on the freestream velocity and cylinder cross-section height normal to the freestream flow, AR is the ratio of the minor axis to the major axis of the elliptical cylinder, and α is the angle between the cylinder major axis and the incoming flow. At Re_D = 100, two distinct wake structures are identified, namely 'Steady wake' (pattern I) and 'Karman wake followed by a steady wake (pattern II)' when AR and α are varied in the ranges specified. When Re_D is increased to 150, an additional wake pattern, 'Karman wake followed by secondary wake (pattern III)' materializes. Pattern I is characterized by two steady bubbles forming behind the cylinder. Pattern II features Karman vortex street immediately behind the cylinder, with the vortex street transmuting to two steady shear layers downstream. Inflection angle α_i = 32°, 37.5° and 45° are identified for AR = 0.25, 0.5 and 0.75, respectively, where the wake asymmetry is the greatest. The α_i effectively distinguishes the dependence on α and AR of force and vortex shedding frequency at either Re_D. In Pattern III, the Karman street forming behind the cylinder is modified to a secondary vortex street. At a given AR and α, Re_D = 150 renders higher fluctuating lift and Strouhal number than Re_D = 100.

• Asian Journal of Atmospheric Environment
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• 제10권3호
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• pp.156-161
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• 2016

In order to deal with current environmental issues and their backgrounds, further development of current teaching methods and tools are essential. The result of questionnaire performed in this study indicates that the effect and the change of the perception of power generation in Japan after the great disaster of East Japan have caused many students (both high school and college students) to become interested in the energy situation. In the present study, we made an attempt to develop a model instrument of a thermal power plant that can be applied as a teaching tool for understanding of air pollutant forming as well as power generation. Our novel model tool consists of a body (30 cm width, 21 cm depth, and 41 cm height), a combustion chamber, two motors, a boiler, a voltmeter, and a chimney for measurement of exhaust gas. Using our novel hand-made power plant, we carried out some model experiments with learners (i.e. high school and college students). Through model experiments, students can be experienced not only about power generation but also about generation of air pollutants. In order to estimate the applicability of our novel instrument as an educational tool, we carried out the questionnaires before and after model experiments. More than 80% of educatees reported that it was very useful as a teaching tool for energy and environmental education. The results of questionnaires indicated that learners achieved a very deep understanding of the principles of power generation and the forming of air pollutants.

• 지질공학
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• 제25권4호
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• pp.613-621
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• 2015

건축 구조물 붕괴 사고가 발생했을 때, 건물 내에 있는 사람들의 긴급구호를 위해 가장 먼저 해야 할 일은 인명이 매몰되어 있는 위치(이하 매몰 공동이라 칭함)를 찾는 일이다. 그러나 붕괴된 건물의 잔해물 내에 위치한 매몰 공동을 일반적인 탐색 방법으로 찾는 것은 불가능하다. 이에 대한 해결방법으로 본 연구에서는, 붕괴시뮬레이션을 통하여 건축 구조물 붕괴 시 지하층에 형성되는 매몰 공동을 평가하였다. 붕괴 시뮬레이션에 사용되는 매몰 공동 유형에 영향을 미치는 인자로는 건축 구조물 층고, 내부 벽체의 유/무로 설정하였다. 시뮬레이션 결과, 지하벽체가 없고 고층 건물일수록 동일한 지진하중에서 큰 면적으로 붕괴가 발생하여 매몰 공동 형성에 불리한 것으로 나타났다. 또한, 매몰 공동이 형성될 경우 건물 외벽 부근이나 코너 부분에 형성될 가능성이 높은 것으로 나타났다.

• 융복합기술연구소 논문집
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• 제2권1호
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• pp.38-42
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• 2012

A scroll compressor used in the air conditioning in automobile consists of the fixed scroll and the orbiting scroll. Temperature gradient in the scroll compressor during the operation induces the thermal expansion of two scrolls. Therefore, the gap between scrolls in the initial stage is regarded as an important variable in structural design of the scroll compressor. The coupled thermal-stress analysis was carried out for the scrolls of a scroll compressor. The temperatures of major points of two scrolls in the steady states were referred by the literature of C. Lin. The sequentially coupled thermal-stress analysis is utilized to the heat transfer analysis and the thermal expansion analysis. In the thermal expansion analysis, the contact analysis was considered between the fixed and the orbiting scrolls in order to obtain the penetration distance and the contact pressure between two scrolls. The range of deformation was from 44 to $76{\mu}m$ according to the height of the scroll. The maximum penetration distance of $60{\mu}m$ occurred at the top surface of the fixed scroll in the center of the scroll parts.

• 한국안전학회지
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• 제30권6호
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• pp.94-101
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• 2015

When a severe disaster such as a building collapse occurs, a first priority for rapid rescue is to find a location where people are highly expected to be buried but alive. It is, however, very difficult to correctly designate the location of such cavities by conventional geophysical survey due to a pile of debris of building members. In this study, location of possible lifeguard cavities were evaluated through a series of simulations of building collapse by explosion depending on the height of the building, a structure of basement floor and a location of explosion. Three types of building structure: five-story, ten-story and fifteen-story were prepared as a model for the simulation. As a results, in the case of low building, only basement floor partially collapsed. On the other hand, in the case of high building, a collapsed range on the inside of the building increased and lifeguard spaces were formed only in the lateral side or corner of the building. In addition, when a wall exists in the basement floor, the possibility that cavities could be formed increased compared to the cases without wall. However, for the fifteen-story building case, no possible lifeguard cavity was found. It is noted that for a high rise building, the height of building more affect forming of safeguard cavity than the structure of the basement floor.