• Journal of Welding and Joining
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• 제28권6호
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• pp.35-39
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• 2010

Generally, ceramic material is very difficult to machine due to high strength and hardness. However, ceramic material can be machined at high temperature by plastic flow as metallic material due to the deterioration of the grain boundary glassy phase. Recently, a new method was developed to execute cutting process with CBN cutting tool by local heating of surface with laser. There are various parameters in LAM because it is a complex process with laser treatment and machining. During laser assisted machining, high power results in reducing of cutting force and increasing tool life, but excessive power brings oxidation of the surface. The effect of laser power, feed rate, cutting depth and etc. were investigated on the life of cutting tool. Chips were observed to find out suitable machining conditions. Chips of SSN had more flow-types than HIPSN. It means SSN is easier to machining. The life of cutting tool was increased with increasing laser power and decreasing feed rate and cutting depth.

• 한국콘텐츠학회논문지
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• 제21권8호
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• pp.403-412
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• 2021

모바일 앱의 수가 기하급수적으로 늘어남에 따라 앱 개발과정에서 이루어지는 테스트의 자동화가 중요해지고 있다. 앱을 출시하기까지 다양한 유형의 테스트를 통해 반복적인 검증이 이루어지는데, 다양한 유형의 테스트 중 GUI 테스트를 중심으로 본 연구는 진행되었다. 안드로이드의 GUI 테스트 자동화 툴을 개발하기 위해서 안드로이드 앱 테스트의 UI Control 16가지와 Material Design Guideline에 대해서 기초 자료를 수집하였다. 그 후 기존 GUI 테스트 자동화 툴에 대해서 스크린 캡처 테스트 기반 2가지 툴과 소스코드 분석 테스트기반 4가지 툴 분석을 하였다. 분석을 통해 기존의 GUI 테스트 자동화 툴들은 시각적 설계, 인터페이스 사용 용이성, 컴포넌트 배치에 대해서는 고려하지 않고 있다는 점을 파악하였다. 이러한 기존 툴의 미비점을 보완하고자 새로운 GUI 테스트 자동화 툴 개발 방법으로 컴포넌트 선정이나 관리 분석 그리고 컴포넌트별 소스코드 예시로 탐색 메뉴나 버튼, 아이템 그룹화나 리스트에 관한 방법을 제시하였다. 본 연구는 GUI 테스트의 새로운 개발 방향을 제시함으로써 개발사의 안정적인 앱 배포에 기여할 수 있다는 점에서 의의가 있다.

• 한국정밀공학회지
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• 제12권1호
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• pp.87-96
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• 1995

A new fungivle material named Epoxy-Granite composite is applied to the column structure of drilling center in order to investigate the advanced dynamic charateristics comparing with a conventional cast iron material. The dimensions of new column structure are adjusted to keep the same stiffness (EI value) and the manufacturing conditions are formulated based on the preceeding research experience about the development of Epoxy-Granite structural material. The two kinds of experiments are set up, one of which is for the measurement of natural mode and frequency using experimental modal analysis, and the other one is for the measurement of vibration amplitude during idling operation of a machine tool. The comparison of maximum accelerance values at each natural frequency of bending mode shows a Epoxy-Granite column have larger modal damping ratios(over 2times) than a cast iron column. The vibration amplitude of Epoxy-Granite column measrued on the bed, motor base, and top of column are also much smaller (up to 12%) than the case of cast iron column. It is therefore confirmed that a Epoxy-Granite material exhibits a good anti- vibrational propderty even if it is used under the actual operational environments of machine tool as a practical structural element.

• 소성∙가공
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• 제18권1호
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• pp.26-38
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• 2009

It was reported that the semi-solid forming process has many advantages over the conventional forming process, such as a long die life, good mechanical properties and energy savings. It is very important, however, to control liquid segregation to gain mechanical property improvement of materials. During forming process, rheology material has complex characteristics, thixotropic behavior. Also, difference of velocity between solid and liquid in the semi-solid state material makes a liquid segregation and specific stress variation. Therefore, it is difficult for a numerical simulation of the rheology process to be performed. General plastic or fluid dynamic analysis is not suitable for the behavior of rheology material. The behavior and stress of solid particle in the rheology material during forging process is affected by viscosity, temperature and solid fraction. In this study, compression experiments of aluminum alloy were performed under each other tool shape which is rectangle shape(square array), rectangle shape(hexagonal array), and free shape tool. In addition, the dynamics behavior compare with Okano equation to power law model which is viscosity equation.

• 한국정밀공학회지
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• 제14권8호
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• pp.73-81
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• 1997

The hard turning process defined as a single point turning of materials harder than $H_{R}$C 58 differs from conventional turning because of hardness of the work materials and cutting toos needed in the process. In hard turning, tool life is very short, of the order of a few minutes, during which the cutting tool is subjected to the extremes of stress and temperature. In this regard, it is well known that CBN tool is proper for this process in spite of expensive cost. In this research, we studied the feasibility of the use of the low cost cutting tool such as a aTiN coated tool. To this end, a new cooling system was designed with an air-oil method for reducing tool temperature, which is based on the principle of air vortex flow. That is, the outlet temperature of the air becomes aver 20 .deg. C lower than atmosphere temperature by entering pressurized air of 5kgf/c $m^{2}$ into the inlet. This cooled air ejected to the top of the cutting tool lowered tool temperature, which reduced the wear of a TiN coated tool by the 30% of CBN tool life with respect to the same cutting length.h.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2003년도 추계학술대회논문집
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• pp.21-24
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• 2003

In hot forming process of the backward end-bulkhead of a pressure hull, the blank diameter and the tool clearance are the critical factors which influence wrinkling defect, forming load and shape completeness of the product. Two F.E.A softwares with the elasto-plastic material model and rigid plastic model were utilized to predict the occurrence of wrinkling defect. Tool clearance was determined by considering the increase of blank thickness, die strength and the stretching effect. Heat treatment condition after the hot forming to recover the original properties of the material was estabilished by specimen-based heat treating experiment.

• 대한기계학회논문집
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• 제17권5호
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• pp.1041-1053
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• 1993

본 연구에서는 2차원 절삭중 공구가 공작물로 들어가는 과정에서의 칩형성의 천이적 행동을 실험적으로 연구하고 이 결과를 이용하여 자기추진 로타리 공구를 사용 한 절삭중 발생한 칩의 삼각화 과정을 규명하는 이론적인 모델을 제안하고 이의 타당 성을 실험결과로 입증하려 한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.117-120
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• 1995

In this machining process, variation in cutting forces results in relative displacements between the tool and the workpiece leading to tool vibration. Also there is a demand to change the depth of cut very frequently. A soluion for both cases is to develop a system which has the ability to reposition a cutting tool to a very small level, i.e., micron. This ppaper presents the development of a micropositioning system (MPS) using a magnetostrictive material. The deveoped MPS is implemented to a lathe and subjected to static and machining test. The results show that the MPS has good potential for machining application

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.131-134
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• 1995

The high efficiency and accuracy in machining the die material can be abtained in high speed machining, so it is necessary to analyze the mechanism of high speed cutting process : cutting force, flank wear. The tool dynomometer with high natural frequency is newly developed. With this device, the mechanism of high speed cutting process is investigated according to speed and feedate.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.183-188
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• 2002

Co-cured composite materials has its own characteristics, so its thermal expansion is different each other. The selection of tool material for co-cured composite part in high temperature more over $350^{circ}F$ and 50 Psi pressure have to consider part thermal expansion, size, shape, and economic aspect in production line. So it is important choose tooling material in manufacturing composite parts. We called the tool for airplane composite parts as BAJ (Bonding Assembly Jig). Composite parts are cured on the BAJ in autoclave. BAJ have to stable at high temperature over $350^{circ}F$ and 50 Psi pressure, Considering composite parts' dimensional tolerance compare to heat up in autoclave. This paper come from the results of the experiment at the composite parts production line and review other aircraft company's method for tooling This is for the engineer engaged in composite parts manufacturing.