• 한국공작기계학회논문집
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• 제10권4호
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• pp.91-96
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• 2001

In this paper, an investigation was performed on the dynamic interlaminar fracture toughness of CFRP(carbon filber rein-forcement plastics). Specimens used in this experiments are CF/PEEK laminated plates. In this experiments, Split Hopkin-sons Bar(SHPE) tes was apply to dynamic and notched flexure test. The model II fracture toughness of each unidirectional CFRP was estimated by the analyzed deflection of the specimen and J-integral with the measured impulsive load and reac-tions at the supported points. As an experimental results the vibration amplitude of [$0^{\circ}_10 /F_4 0^{\circ}_10 $] j-aminates appear more than that of [$0^{\circ}_10 /F_2 0^{\circ}_10 $ laminates for the j-integral and displacement velocity at a measuring point. Also, it is thought that the dynamic fracture toughness of two kind specimen(CF/PEEK) with the crease of displacement velocity becomes great at a measuring point with in the range of measurement.

• 한국유체기계학회 논문집
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• 제17권5호
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• pp.72-77
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• 2014

Because of overload working condition of sintering cooler, the cooler fan often suffers the break or damage of rotor blade and fixing shaft. Therefore, internal flow characteristics of a steelworks sintering cooler fan by the duct shape of the cooler fan outlet, such as duct outlet opening ratio, duct height and dividing wall shape on the duct outlet flow pattern are examined in detail. The results show that relatively short duct wall height and attachment of dividing wall shape improves flow patterns considerably.

• Tribology and Lubricants
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• 제14권3호
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• pp.74-80
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• 1998

The morphologies of the wear particles are directly indicative of wear process occuring in the machine. The analysis of wear particle morphology can therefore provide very early detection of a fault and can also ofen facilitate a dignosis. For this work, the neural network was applied to identify friction coefficient through four shape parameters (50% volumetric diameter, aspect, roundness and reflectivity) of wear debris generated from the machine. The averages of these parameters were used as inputs to the network. It is shown that collect identification of friction coefficient depends on the ranges of these shape parameters learned. The various kinds of the wear debris had a different pattern characteristics and recognized relation between the friction condition and materials very well by neural network. We discuss how the network determines difference in wear debris feature, and this approach can be applied for machine condition monitoring and fault diagnosis.

• 한국안전학회지
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• 제13권4호
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• pp.41-48
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• 1998

In this paper, an investigation was performed on the dynamic interlaminar fracture toughness of CFRP(carbon fiber reinforcement plastics) composite laminates. Composite laminates used in this experimentation are CF/EPOXY and CF/PEEK laminated plates. In the experiments, Split Hopkinson's Bar(SHPE) test was applied to dynamic and notched flexure test. The mode Ⅱ fracture toughness of each unidirectional CFRP was estimated by the analyzed deflection of the specimen and J-integral with the measured impulsive load and reactions at the supported points. As an experimental result, the vibration amplitude of CF/PEEK laminates appear more than that of CF/EPOXY laminates for the J-integral and displacement velocity at a measuring point. Also, it is thought that the dynamic fracture toughness of two kind specimens(CFRP/EPOXY and CF/PEEK) with the in crease of displacement velocity becomes a little greater at a measuring point within the range of measurement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.96-100
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• 1997

The shadow moire is one of the optical techniques which is able to give contour lines of an object with respect to a master grating plane. The moire patterns are issued from the superposition of a master grating and its shadow projected on the surface of an object. In case of the classical shadow moire method, the sensitivity was a few tenths millimeters. generally, it is difficult to use a phase shift method in shadow moire because it is impossible to obtain uniform phase shifts on the whole field. But in this study we use the fact that if the depth of object is much less than the distance between the observer and the master grating, and the object is displaced perpendicularly to the grating plane, phase shifts are almost uniform. Finally we obtained a better resolution by using a phase shift procedure and applied the phase shifting shadow moire to three dimensional shape measurement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.675-678
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• 2001

In this paper, an investigation was performed on the dynamic interlaminar fracture toughness of CFRP(carbon fiber reinforcement plastics). Specimens used in this experiment are CF/EPOXY laminated plates. In this experiments, Split Hopkinson s Bar test was applied to dynamic and notched flexure test. The mode II fracture toughness of each unidirectional CFRP was estimated by the analyzed deflection of the specimen and J-integral with the measured impulsive load and reactions at the supported points. As an experimental result, the vibration amplitude of 〔$0_{10}F_4/0_{10}$〕laminates appear more than that of 〔0_{10}/F_2/0_{10}$〕laminates for the J-integral and displacement velocity at a measuring point. Also, it is thought that the dynamic fracture toughness of two kind specimen with the increase of displacement velocity becomes great at a measuring point with in range of measurement.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.1017-1020
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• 2002

The pure Ti is taken annealing process for one hour at 90$0^{\circ}C$. The pure Ti is sufficient for ASTM B348 Grade2. The rolling mill roll the Ti-8Ta-3Nb(wt%) which became vacuum melting in arc furnace until the length is about 45mm and the thickness is about 6.05mm. Then it is made 6mm$\times$6mm$\times$44mm by wire cutting with EDM and it is made ∮ 6mm by rough cutting with the general purpose lathe. The machining accuracy of implant parts in the dental and medical science are decided by dimension, shpe, straightness, surface roughness. It is difficult to cut for the Ti alloy. It is caused problems of straight degree and surface roughness to the Ti alloy have many cases which length is smaller than diameter in cutting. Total 24 specimens different kind of 4 alloies are used in experiment to gain a cutting property. According to the cutting velocity, cutting depth, cutting temperature, feed and clearance angle experiments are performed. Conclusively it is expected that cutting depth of 0.5mm, feed velocity of 0.07mm/rev and cutting velocity of 80m/min could make a suitable result.

• 전자공학회논문지D
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• 제34D권7호
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• pp.56-61
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• 1997

I $n_{0.53}$G $a_{0.47}$As/I $n_{0.52}$A $l_{0.48}$As pseudomorphic high electron mobility transistor (P-HEMT) structures were grown on semi-insulating InP substrates by molecular beam epitzxy method. The hall effect measuremetn was used to measure the electrical properties and the photoluminescence (PL) measurement was used to measure the electrical properties and the photoluminescence(PL) measurement for optical propety. By the cross-sectional transmission electron microscopy (XTEM) investigation of the V and X shape defects including slip with angle of 60.deg. C and 120.deg. C to surface in the sampel, the defects formation mecahnism in the I $n_{0.52}$A $l_{0.48}$As epilayers on InP substrates could be explained with the different thermal expansion coefficients between I $n_{0.52}$A $l_{0.48}$As epilayers and InP substrate.d InP substrate.

• 한국통신학회논문지
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• 제16권8호
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• pp.719-731
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• 1991

본 논문은 일반형의 개통형전자총의 전자 빔 궤도를 비교적 신속 편리하게 해석할 수 있는 computer simulation의 한 방법을 소개하는 것으로써 전극의 구조와 인가전압등을 입력하면 빔 전류, cutoff 전압, 빔 직경 그리고 궤적도가 출력으로 얻어진다. 계산속도를 증가시키기 위해서 공간전위의 계산에는 전극공간을 여러개로 분할하고 요구되는 정도에 따라서 각기 다른 격자크기를 할당하였으며 유한차분법으로 계산하도록 하였다. 몇 가지의 model을 선정하여 본 방법으로 빔 궤적도를 simulation 시켰는데 그 결과는 전극의 집속기구를 명확하게 제시해줄 수 있었으며 본 방식으로 구해진 빔 전류, cutoff 전압, 빔 직경등은 실지의 측정실험에서 얻어진 결과와 실험오차 내의 정확도로써 잘 일치되었다. 이 방법을 적용하면 설계자로 하여금 실지로 전자관을 제작하지 않고서도 전극의 구조변화에 따른 영향을 정확히 파악 할 수 있는 까닭에 전자총의 설계나 개선작업에 유용하게 적용될 수가 있을 것이다.

• 한국건설관리학회:학술대회논문집
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• 한국건설관리학회 2007년도 정기학술발표대회 논문집
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• pp.347-352
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• 2007

건설 산업의 숙련공 부족현상, 고령화 문제, 임금 상승으로 인한 채산성 악화, 품질의 균일성 및 안전성 확보 등은 향후 국내 건설 산업이 해결해야 할 당면 과제이다. 이러한 문제를 해결하기 위한 하나의 기술적인 접근방법으로써 국${\cdot}$내외에서는 건설 자동화에 대한 연구가 활발히 진행 중에 있으며, 최근 국내에서는 토공사 작업의 안전성을 확보하기 위해 백호(backhoe)를 대상으로 지능형 굴삭로봇을 개발하기 위한 연구가 진행 중에 있다. 본 연구에서는 지능형 굴삭 로봇을 개발하기 위해 필수적으로 요구되는 기반기술 중 실시간 지반형상 인식 및 토공량 자동산출을 위한 최신 요소기술을 분석하고 최적 대안을 제시하였으며, 이를 위해 국내외 문헌고찰 및 다양한 최신요소 기술의 분석을 통해 지반형상을 실시간으로 인식할 수 있는 5가지 요소기술들에 대한 분석을 선행하였다. 또한 로컬영역의 실시간 지반형상 인식 및 토공량 자동 산출을 위해 3차원 모델링 장비가 갖추어야할 주요 고려요소를 분석하고, AHP 기법을 이용하여 주요 고려요소별 가중치를 산정하고 각 요소기술별 선호지수를 도출하였다. 도출된 선호지수를 바탕으로 최신 요소기술 간의 우선순위를 선정함으로써 3차원 모델링 장비에 적용 가능한 최적 대안을 선정하였다.