• Composites Research
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• 제14권1호
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• pp.15-21
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• 2001

고강성 카본 섬유 복합재료의 높은 비강성을 이용하여 가압 롤러를 설계·제작하였다. 롤러 제작을 위한 최적의 적층 순서는 유한요소해석을 통해 얻어졌으며, 고무코팅층의 형상은 롤러의 축 길이를 따라 필름에 가해지는 균일 압력에 대해 계산되어진 변형에 근거하여 결정하였다. 제작된 가압 롤러의 정적 변형을 해석결과와 실험적으로 비교하였으며, 그것의 동적 독성은 진동 시험을 통하여 측정하였다.

• 대한기계학회논문집
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• 제18권8호
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• pp.2053-2061
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• 1994

The static and fatigue tensile tests have been conduted to predict the fatigue life of 8-harness satin woven and plain woven carbon/epoxy composite plates containing a circular hole. A fatigue residual strength degradation model, based on the assumption that the residual strength for unnotched specimen decreases monotonically, has been applied to predict statistically the fatigue life of materials used in this study. To determine the parameters(c, b and K) of the residual strength degradation model, the minimization technique and the maximum likelihood method are used. Agreement of the converted ultimate strength by using the minimization technique with the static ultimate strength is reasonably good. Therefore, the minimization technique is more adjustable in the determination of the parameter and the prediction of the fatigue life than the maximum likelihood method.

• International Journal of Automotive Technology
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• 제4권4호
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• pp.203-211
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• 2003

This paper describes a method for a falling weight impact test to estimate the impact energy absorbing characteristics and impact strength of CFRP (Carbon-fiber reinforced plastics) laminate plates based on considerations of stress wave propagation theory, which were converted to measurements of load and displacement verses time. The delamination area of impacted specimens for the different ply orientations was measured with an ultrasonic C-scanner to determine the correlation between impact energy and delamination area. The energy absorbed by a quasi-isotropic specimen having four interfaces was higher than that of orthotropic laminates with two interfaces. The more interfaces, the greater the energy absorbed. The absorbed energy of a hybrid specimen embedding GFRP (Glass-fiber reinforced plastics) layer was higher than that of normal specimens. Also, a falling weight impact tester was built to evaluate the characteristics and impact strength of CFRPs.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2013년도 제44회 동계 정기학술대회 초록집
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• pp.160-160
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• 2013

Dye-sensitized solar cells (DSSCs) have attracted much attention because of their moderate light-to-electricity conversion efficiency, easy fabrication, and low cost. At present, platinum (Pt) is used as a counter electrode in DSSCs. However, it is found that Pt dissolves in iodide electrolyte solutions and creates chemical compound such as PtI4 and H2PtI6. Carbon based materials are one of candidates for a counter electrode of DSSCs. We prepare two types of graphite oxides by different chemical treatments; original graphite oxide, hydrazine treated graphite oxide. Each graphite oxide and magnesium nitrate dispersed in deionized water are prepared as solutions for electrophoretic deposition (EPD). Each graphite oxide electrode is deposited on fluorine-doped tin oxide (FTO) substrate by EPD method. Structural and electrochemical properties of each electrode are investigated by field-emission scanning electron microscopy and electrochemical impedance spectroscopy, respectively.

• 한국펄프종이공학회:학술대회논문집
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• 한국펄프종이공학회 2011년도 춘계학술발표회 논문집
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• pp.243-249
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• 2011

In the world, burning fossil fuels such as oil, petroleum, gasoline has created the global warming due to especially carbon dioxide gas emission. Therefore, these fossil fuels must be replaced by eco-friendly feadstocks. The wood pellets are one of valuable alternative fuels that can replace oil-based fuels within a short period of time. Unfortunately, there are no enough forest biomass for wood pellets in Korea. Nevertheless, Korea government has been trying to use most of forest biomass generated from the National Forest Management Operation. This does not make sense in an economic point of view.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 춘계학술대회 논문집
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• pp.181-185
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• 1996

Rapid prototyping is becoming an increasingly importnat techniuqe involved in the design cycles of modern industry. The majority of the rapid prototyping systems currently available use photo-reactive resins and waxes as the raw materials. The models produced by these systems often have relatively poor mechanical and physical properties and as such have a limited application to the production of advance prototypes but are excellently suited to the manufacture of engineering prototyes. This work identifies the need to produed near production grade advance prototypes from a variety of metals and a novel prototyping process based on the techniques of selective laser sintering and conventional machining is proposed. The integration of a carbon dioxide laser and a conventional machine tool to create the opto-mechanical by multi-layer sintering and some of the problems involved are also discussed.

• 한국레이저가공학회지
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• 제2권1호
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• pp.61-67
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• 1999

This study introduces the new concept in the evaluation criteria of the $CO_2$ laser Tailored Blank weldability, The materials used are 0.7mm, 1.5mm thick low carbon automotive galvanized steels. Welding tests were conducted for both similar thickness(0.7mm-0.7mm, 1.5mm-1.5mm) and dissimilar thickness(0.7mm-1.5mm) cases. The criteria developed for optimum welding conditions were based on relationship between results of die press forming test, weld transverse tensile test Erichsen test and weld penetration measurements. Application of the developed criteria(fracture ratio, strength ratio and D/To) in obtaining optimum welding condition revealed that a weld which satisfied any of the criteria did not fracture during actual die press test.

• 한국기계가공학회지
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• 제3권3호
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• pp.52-57
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• 2004

Many kinds of gases, such as erosion gas, dilution gas, and toxic gas have been used in manufacturing process of LCD at semiconductor. In order to increase accumulation rate of manufacturing process, high degree of purity in these gases and minimized metalllic dust are required. All wetted stainless steel surface must be 316L electro-polished with $0254{\mu}m$ in average. Based on the AES analysis, Cr/Fe 11 and $Cr_2O_3$ thickness $25{\AA}$ are measured Molybdenum and silicon contaminants which is characteristic of stainless steel and oxygen were found on the surface.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1995년도 추계학술대회 논문집
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• pp.60-63
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• 1995

The behavior of the work materials in the chip-tool interface in extremely high strain rates and temperatures is more that of viscous liquids than that of normal solid metals. In these circumstances the principles of fluid mechanics can be invoked to describe the metal flow in the neighborhood of the cutting edge. In the present paper an Eulerian finite element model is presented that simulates metal flow in the vicinity of the cutting edge when machining a low carbon steel with carbide cutting tool. The work material is assumed to obey visco-plastic (Bingham solid) constitutive law and Von Mises criterion. Heat generation is included in the model, assuming adiabatic conditions within each element. the mechanical and thermal properties of the work material are accepted to vary with the temperature. The model is based on the virtual work-stream function formulation, emphasis is given on analyzing the formation of the stagnant metal zone ahead of the cutting edge. The model predicts flow field characteristics such as material velocity effective stress and strain-rate distributions as well as built-up layer configuration

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 춘계 학술논문 발표대회
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• pp.182-183
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• 2017

This research identifies radon gas absorption mechanism by adsorption materials, replacing gypsum board with radon emissions, the density and absorption rates of magnesium were carried out using vermiculite, anthracite, powdered active carbon, bentonite, illite, diatomite as a basic study on the fire resistance type of radon Gas reduction type with absorption and decomposition. As a result of the experiment, diatomite showed the lowest density, and the highestt value was the highest. For the absorption rate, bentonite showed the highest absorption rate, and the anthracite showed the lowest absorption rate.