• 한국철도학회:학술대회논문집
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• 한국철도학회 2002년도 춘계학술대회 논문집
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• pp.503-508
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• 2002

In this study, the relation between the mtation which are usually caused by the creep of the contact wire, the bar geometry and the forces(wire tensions) for the triangle-shaped distribution bar and straight-shaped one in dependent tensioning device system is reviewed. According to the result a rotation of distribution bar in triangle-shaped one modifies the distribution of the tensions between the three wires hooked in a distribution bar. On the contrary, a rotation on the straight-shaped one leads to no tension distribution change. Therefore, to use the straight-shaped distribution bar instead of triangle-shaped one is recommended. In addition, the design contents of the distribution bar which will be used in electrification of Gyeongbu line are described in this paper.

• 한국건축시공학회지
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• 제15권5호
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• pp.465-471
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• 2015

철근콘크리트 기둥에서 횡 보강근의 시공성 및 구속효과를 향상시키기 위하여 본 연구에서는 내부 크로스타이의 대체로서 V형 띠철근의 배근방법을 제시하였다. 제시된 V형 띠철근의 부착응력-미끄러짐 관계를 파악하기 위하여 콘크리트 강도 및 V형 띠철근의 절곡각도와 묻힘길이를 주요변수로 35개의 직접인발 실험체를 제작하였다. V형 띠철근의 부착강도는 절곡각도가 $60^{\circ}$ 이하에서 CEB-FIP 기준 식보다 높게 있었다. V형 띠철근의 시공성 및 부착거동을 고려하면, V형 띠철근의 최적 절곡각도 및 묻힘길이는 각각 $45^{\circ}$와 $6d_b$ 이상으로 제시될 수 있었는데, 여기서 $d_b$는 띠철근 직경이다.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.58-59
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• 2017

Through the case study, we surveyed the performance of a CNC-T BAR system on irregular-shaped building construction project. By CNC T-BAR system, we mean a surface curvature control system has been used in aircraft and ship manufacturing by controlling entire surface points on shape. For the past 10 year, the number of irregularly-shaped building design and construction project has been increased, and also the studies on irregular-shaped construction methods have been conducted. However, the previous studies did not review on the performance of the CNC T-BAR system. We collected construction-completed cases in Korea, which applied the CNC T-BAR system, and we studied its performance by comparing with a segment system in terms of construction duration and its quality. The result shows that the CNC T-BAR system can shorten the construction duration comparing with segment-assembly system while maintaining high quality. The CNC T-BAR system is expected to apply on the more number of irregularly-shape building construction project.

• 소성∙가공
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• 제8권4호
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• pp.331-339
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• 1999

In this study, to analyze the shaped drawing process from round bar, the practical conical die with considering die radius and bearing was defined by a mathematical expression, and also a simple technique for initial mesh generation to the shaped drawing process was proposed. The drawing of rectangular section from round bar, one of the shaped drawing process, has been simulated by using non-steady state 3D rigid plastic finite element method in order to evaluate the influence of semi-die angle and reduction in area to corner filling. Other process variables such as friction constant, rectangular ratio, die radius and bearing length were fixed during the simulation. An artificial neural network has been introduced to obtain the optimal process conditions which gave rise to a fast simulation.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.454-457
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• 2006

This study presents a strut-and-tie model for the development of headed bars in an exterior beam-column joint with transverse reinforcements. The tensile force of a headed bar is considered to be developed by head bearing together with bond along a bonded length as a partial embedment length. The model requires construction of struts with biaxially compressed nodal zones for head bearing and fan-shaped stress fields against neighboring nodal zones for bond stresses along the bonded length. Due to the existence of transverse reinforcements, the fan-shaped stress fields are divided into direct and indirect fan-shaped stress fields. A required development length and head size of a headed bar can be optimally designed by adjusting a proportion between a bond contribution and bearing contribution.

• 한국재료학회지
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• 제18권7호
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• pp.362-366
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• 2008

The precipitation behavior in Mg-6 wt%Zn-1 wt%Y alloy annealed at different temperatures of $200^{\circ}C$ and $400^{\circ}C$ has been characterized by high resolution transmission electron microscope. When the alloy is annealed at $200^{\circ}C$ for 6 hr, the plate- and the rod-shaped ${\beta}_2'$ phases are precipitated in the matrix. The orientation relationship of plate-shaped precipitates with the matrix exhibits a [$11{\bar{2}}0]{\beta}_2$ || [$10{\bar{1}}0$]Mg, $(0001){\beta}_2'$ || (0001)Mg. While the rod-shaped precipitates have two kinds of the orientation relationships with the matrix, i.e. $[11{\bar{2}}0]{\beta}_2'$||[0001] Mg, $(0001){\beta}_2'||(11{\bar{2}}0)$ Mg and $[11{\bar{2}}0]{\beta}_2'$||[0001] Mg, $({\bar{1}}106){\beta}_2'||(10{\bar{1}}0)$ Mg. With increasing annealing time at $200^{\circ}C$ the ${\beta}_1'$ phases are also precipitated in the matrix and the orientation relationship exhibits a $[010]{\beta}_1'$ || [0001]Mg, $(603){\beta}_1'$ || ($01{\bar{1}}0$)Mg between the ${\beta}_1'$ precipitate and the matrix. The icosahedral phases are precipitated in the alloy annealed at $400^{\circ}C$ and exhibit a $[I2]_I$ || [0001]Mg relationship with the matrix.

• 복식
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• 제27권
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• pp.17-26
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• 1996

This thesis is to study the original form of Buckles of our country in ancient times On the upper garment bound the leather belts that was hanged a hook that shaped of animal form at the end. The background of Buckles was originated from those northern mounted normadic groups which was Scythe style costume culture. In Korea through the antique records and tombs bequests the styles of Buckles was divided into three groups horse-shaped tiger-shaped bar-shaped Buckle. These styles were influened by scythe style and developed greatly and trasmitted to Japan.

• 항공우주시스템공학회지
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• 제15권6호
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• pp.1-9
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• 2021

In this study, a new design of an extension-type actuator (ExACT) is proposed based on a chevron structure with displacement amplification mechanisms by local heating. ExACT comprises diamond-shaped displacement amplification structures (DASs) containing axially oriented V-shaped chevron beams, a support bar that restricts lateral heat deformation, and a loading slot for thin-film heaters. On heating the thin film heater, the diamond-shaped DASs undergo thermal expansion. However, lateral expansion is restricted by the support bar, leading to displacement amplification in the axial direction. The performance parameters of ExACT such as temperature distribution and extended displacement is calculated using thermo-mechanical analysis methods with the finite element method (FEM) tool. Subsequently, the ExACTs are fabricated using a polymer-based 3D printer capable of reproducing complex structures, and the performance of ExACTs is evaluated under various temperature conditions. Finally, the performance evaluation results were compared with those of the FEM analysis.

• 대한치과보철학회지
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• 제45권4호
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• pp.431-443
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• 2007

Statement of problem: Injuries along with discomfort may result on the oral mucosa when non-rigid material is used as the major connector in construction of RPD, since nonrigid major connectors transmit unstable forces throughout the appliance. Titanium which recently draws attention as a substitute of Co-Cr had a difficulty in fabricating due to high melting temperature but the development of casting technique makes it possible to apply to the clinical case. Purpose: The purpose of this study was to investigate the rigidity and the castability of titanium upper major connector by design and make a comparison with Co-Cr major connectors which are widely used in clinical cases now. Material and methods: Casting was done using CP-Ti(Grage 2) (Kobe still Co., Japan) for the experimental groups, and 4 various designs namely palatal strap, U-shaped bar, A-P strap, and complete palatal plate were casted and 5 of each designs were included in each group. For the experimental group, Universal testing machine (Model 4502; Instron, Canton, Mass) was used to apply vertical torsional force vertically to the horizontal plane of major connector. In the second experiment, Vertical compressive force was applied to the horizontal plane of major connector. As a comparative group, Co-Cr major connector was equally manufactured and underwent the same experimental procedures Strain rate was measured after constant loading for one minute duration, and statistical analysis was done with SPSS ver.10.0 for WIN(SPSS. Inc. USA). From the one-way ANOVA and variance analysis (P=0.05), Scheffe's multiple comparison test implemented. Results: 1. Least amount of strain was observed with complete palatal plate followed by A-P bar, palatal bar, and the U-shaped bar having most amount of strain. 2. In all designs of titanium major connector, less strain rate was observed under compressive loading than under torsional loading showing more resistance to lateral force. 3. For titanium major connector, less strain rate was observed when the force is applied to the first premolar area rather than to the second molar area indicating more strength with shorter length of lever. 4. In Comparison of Co-Cr major connector with titanium major connector, palatal strap and U-shaped bar designs showed higher strength under torsional force that is statically significant, and under compressive force, no significant difference was observed expert for U-shaped bar. 5. In titanium major connector, complete palatal plate showed lowest success rate in casting when compared with the Co-Cr major connector. Conclusion: Above results prove that when using titanium for major connector, only with designs capable of generating rigidity can the major connector have almost equal amount of rigidity as Co-Cr major connector and show lower success rate in casting when compared with the Co-Cr major connector.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1998년도 춘계학술대회논문집
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• pp.205-209
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• 1998

Unlike the drawing of round section from round bar, the shaped drawing like polygonal section is known to have influence not only drawing stress but also comer filling. Therefore, this study analyze the drawing process of suqare rod from round bar using nonsteady state rigid-plastic FEM. To investigate effects of process variables of the drawing process of square rod from round bar, FE-simulations with variety of reduction in area and semi-die angle for a given frictional condition have been conduction. By this results, it has to suggest optimal process condition on the drawing stress and the comer filling. In addition, it has determined forming limit considering necking and bulging.