• 대한기계학회논문집
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• 제15권2호
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• pp.436-444
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• 1991

A computational method has been developed to analyze the bone-remodeling induced by external fixator. The method was based on the Finite Element Method (FEM) in combination with numerical formulation of adaptive bone-remodeling theories. As a feed-back control variable, compressive strain and effective stress were used to determine the surface remodeling and internal (density) remodeling respectively. Surface remodeling and internal remodeling were combined at each time step to predict the rel situation. A noticeable shape and density change were detected at the region between two pins and density change was decreased with time increment. At final time step, the shape and density distribution were converged closely to its original intact bone model. Similar change was detected in stress distribution. The altered stress distribution due to the pin and external fixator converged to the intact stress distribution with time.

• Agricultural and Biosystems Engineering
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• 제6권2호
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• pp.70-76
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• 2005

Seed, stem and sprout of F. tataricum were separately milled using the ultra fine mill under the same condition to investigate the effect of roasting or extruding on the particle size, microstructure and water solubility of dietary fiber. The mean particle size of MR (roasting) is increased in stem and sprout, and that of ME (extruding) is increased in seed, compared to that of control. The microscopic views of seed show that control has the spherical shape but ME the larger and irregular shape, and those of stem and sprout show that control has the needle like shape but ME more rounded shape. Water solubility index of ME is much higher than that of control or MR in seed, stem and sprout. It shows that seed, stem and sprout are damaged more in extruding than in roasting, and the starch and cell wall structure must be destroyed to change the water insoluble dietary fiber into the water soluble dietary fiber.

• 열처리공학회지
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• 제5권3호
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• pp.149-156
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• 1992

Transformation behavior and reversible shape memory effct of Ti-Ni-Cu alloys with various Cu content has been investigated by means of electrical resistivity measurement, differential scanning calorimetry. X-ray diffraction and strain gage sensor. The transformation sequence in Ti-Ni-Cu alloys substituted by Cu for Ni up to 5at.% occurs to $B2{\leftrightarrow}B19^{\prime}$ and it proceeds in two stages by addition of 10 at.%Cu. i.e. $B2{\leftrightarrow}B19{\leftrightarrow}B19^{\prime}$. But the content of Cu increases up to 20at.%, it has been transformed in one stage ; $B2{\leftrightarrow}B19$. The shape change of Ti-40Ni-10Cu alloy which was constrain aged in circular form bended in $B2{\leftrightarrow}B19$ transformation but it spreaded out in $B19{\leftrightarrow}B19^{\prime}$ transformation. The amount of reversible shape change (${\Delta}{\varepsilon}$) of Ti-47Ni-3Cu alloy constrain aged at $400^{\circ}C$ after solution treatment has a maximum value of about $5.6{\times}10^{-3}$, but that of cold rolled and constrain aged specimens exhibits a little value independent of Cu concentrations.

• 한국기계가공학회지
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• 제20권9호
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• pp.76-83
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• 2021

This study examines the characteristics of spraying conditions based on the change in standoff distance during fine particle spraying while measuring the surface roughness, maximum depth, and maximum width of the sprayed surface. The processing shape of the sprayed surface is analyzed to understand the effects of injection pressure, nozzle diameter, standoff distance, processing shape, processing cycle, processing speed, and injection particles, which are the main factors of fine particle injection processing. Based on the derived characteristics, we attempt to determine the interrelationships of these major factors. The standoff distance is set as a variable factor and a spray machining experiment using a hexagonal shape (from among polygons) instead of square and circular shapes is conducted. Results reveal that research on the characteristics of spraying conditions could be expanded based on changes in the shapes of workpieces.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 1992년도 춘계학술대회 논문집 92
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• pp.11-26
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• 1992

In this research, a numerical algorithm has been developed, which can be applied to the large deformation and large displacement contact problems between angle change have been proposed considering the change in geometric shape and rate of contact force. A set of linear simultaneous equations is constructed by adding the geometric shape change and contact conditions to the original stiffness matrix. A new method to determine time increment has been proposed based on Euler method, in which the condition to prevent the contact bodies from penetrating and overrunning each other has been taken into consideration. Practical application to contact problem is extrusion in which bodies are sliding along the contact boundary.

• 열처리공학회지
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• 제5권3호
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• pp.179-185
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• 1992

The shape memory effect results from the martensite transfomation of each individual grain. Thus it is necessary to study the texture and its variation. In this study the change of texture during thermal cycling and it's effect on shape memory ability are investigated. The major component of the rolling texture in the parent phase is identified (001) [110], and minor components are (112) [110], (111) [112], {hkl}<100> fiber texture is developed at $45^{\circ}$ from rolling direction. In the case of martensite phase, it is estimated that the major component is (011) [100] and the minor components are (105) [501], (010) [101] and (100) [001]. According to thermal cycling. severity of texture, especially (001) [110] component in parent phase and (011) [100] component in martensite phase are increased. The shape memory ability is increased with increase of thermal cycles and also increased as the direction of specimen approach to $45^{\circ}$ from rolling direction. After first thermal cycling the temperature of transformation can be define clearly and Ms and As are raised by thermal cycling.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2003년도 춘계학술대회 논문집
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• pp.1549-1552
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• 2003

The front-end side members of automobiles absorb most of the energy in a front-end collision. The front-end side members are required to have a high stiffness together with easiness to collapse sequentially to absorb more impact energy. The axial static collapse test (5mm/mim) was conducted by using UTM with respect to the single hat shaped section members which are the standard section shape of the spot welded section members, to the single cap shaped section members, to the double cap shaped section members and to the double hat shaped section members whose section shape are changed in order to give more stiffness. As a result of test, the energy absorbing characteristic was analyzed for different section shapes. That is, it was analyzed that the change of section shape influenced the absorbing energy, the mean collapse load and the maximum collapse load, and that the relation between the change of section shape and the collapse mode.

• 한국지능시스템학회논문지
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• 제15권1호
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• pp.48-52
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• 2005

본 논문에서는 음성의 스펙트럼 형태는 유지하면서 음성을 기계적인 음성으로 변환시키기는 실시간 음성 변환 방법을 제안하였다. 이러한 목적을 위하여 LPC 분석 및 합성 방법을 사용하여 변환된 음성의 스펙트럼은 유지하였고 합성된 음성의 피치는 자유롭게 변경되도록 하였다. 제안된 방법에서는 변환된 음성이 보다 자연스럽게 들리게 하기 위하여 여기 신호 발생기에 이득 정합 방법을 적용하였다. 제안된 방법의 성능을 평가하기 위하여 음성 변환 실험을 수행하였다. 실험 결과에서 원 음성 신호는 원 화자의 신원을 알기가 어려운 기계적인 음성 신호로 바뀌는 것을 알 수 있었고 피치의 심한 변화에도 변환된 음성의 의미는 정확히 전달될 수 있었다. 제안된 시스템은 시스템의 실시간으로 구현될 수 있는지 확인하기 위하여 TI TMS320C6711DSK 보드를 사용하여 구현되었다.

• 한국자동차공학회논문집
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• 제25권2호
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• pp.242-249
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• 2017

In this study, the relationship between the shape of a passenger airbag and the possibility of injury is analyzed using the Taguchi method. The optimal shape combination is proposed for a design guideline that can reduce the possibility of injury to the dummy. The airbag FE model for analysis is obtained using a CAD system that can change the shape through several independent variables. The widths of the left / right, top / bottom, and back / forth direction of the airbag shape are set as the design factors, and the effect of the combination injury probability according to the shape is analyzed. The minimum geometric combinations are obtained using the orthogonal array method. The signal to noise ratio is calculated and the optimal shape combination is obtained through sensitivity analysis. The obtained optimal shape combination is compared with the possibility of injury of the initial airbag shape to confirm improved airbag performance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.1260-1265
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• 2001

It is important to model the mechanical structure precisely and reasonably in predicting the dynamic characteristics, controlling the vibration, and designing the structural dynamics. In the finite element modeling, the errors can be contained from the physical parameters, the approximation of the boundary conditions, and the element modeling, From the dynamic test. more precise dynamic characteristics can be obtained. Model updating using parameter modification is appropriate when the design parameter is used to analyze the input parameter like finite element method. Finite element analysis for free-free-free-free(FFFF) and clamped-free-free-free(CFFF) plate with uniform area and shape change are carried out as model updating examples, Mass and stiffness matrices are updated by comparing test and analytical modal frequencies. The result shows that the updated frequencies become closer to the test frequencies.