• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.956-961
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• 2003

Recently, environmental pollution has become a significant problem in industry and many researches have been investigated in order to preserve the environment. Environmentally conscious machining and technology have more and more important position in machining process. In the milling process, the cutting fluid has greatly bad influence on the environment. In this study, the machining of blade parts(12Cr steel) using the cutting fluid, compressed cold air and oil mist etc., also, the productivity and the surface topography was improved by using new end-mil tool considering tool material and shape.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 추계학술대회 논문집
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• pp.907-910
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• 1997

With increasing the needs for micro and precision parts, micro machining technology has been studied to fabricate a small part with high density such as electronics, optics, communications, and medicine industry more than before. But there are many problems to be solved requiring a high-level technology. So this research presents the new method to fabricate a small part through applying chemical mechanical micro machining (C3M) for the Al wafer. Al(thickness I ,u m) was sputtered on the Si substrate. Al is widely used as a lightweight material. However form defect such as burr has a bad effect on products. To improve machinability of ductile material, oxide layer was formed on the surface of AI wafcr before grooving by chemical reaction with HN03(10wt%). And then workpieces were machined to compare conventional micro-machining process with newly suggested method at different machining condition such as load and feed rate. To evaluate whether or not the machinability was improved by the effect of chemical condition, such as the size, the width of grooves 'and burr generation were measured. Finally, it is confirmed that C3M is one of the feasible tools for micro machining with the aid of effect of the chemical reaction.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.135-138
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• 1995

Recently, most of advanced materials used a wide industry field commonly have the characteristics of difficulty-to-cut materials. The cutting of difficulty-ro-cut materials have a variable optimum cutting conditions and methods according to materials. Above all,it is important of understanding to machinability of each materials. Especially, superalloy with Elevated Temperature Strength like as Incone1718 was used in nuclear power equipment and jet engine parts. This research shows a machining characteristics of Heat-Resistant alloy for high efficiency cutting through cutting force,tool wear and cutting temperature in SUS304 and Incone1718.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.308-311
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• 2004

Nowadays, plastic industry has needed to produce parts that require high precision and quality. To make a high precision and quality part, before injection molding, plastic material is investigated about their properties such as shrinkage, warpage, etc. In this study, experiments were conducted with PA6(polyamid) to figure out shrinkage behavior according to three type aspect ratio of samples. The injection speed that affects on shear rate, molecular orientation within plastic part was determined as main variable of experiment. As a result of experimental study, part shrinkage had a tendency to be decreased by increasing injection speed and aspect ratio of samples.

• 한국기계가공학회지
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• 제12권3호
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• pp.81-88
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• 2013

Recently, energy-saving technology is rapidly becoming a crucial issue for mankind due to the depletion of natural resources. From this perspective, every automobile manufactures are trying to develop light materials and to validate safety with environmental consideration. In this study, we developed clutch connector tube which is the parts of power transferring clutch with light materials to substitude for existing general steel materials. We also verified that the general steel materials can be replaced with nylon, fiberglass, stainless and plastic materials or not. As a result, we verified that the mixture of glass and nylon composite material can substitude the general steel.

• 한국기계가공학회지
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• 제3권3호
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• pp.46-51
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• 2004

Nowadays, plastic industry has needed to produce parts that require high precision and quality. To make a high precision and quality part, before injection molding, plastic material in investigated about their properties such as shrinkage, warpage, etc. In this study, experiments were conducted with PP(polypiopylene) to figure out shrinkage behavior according to three type aspect ratio of samples. The injection speed that affects on shear late, molecular orientation within plastic part was determined as main variable of experiment. As a result of experimental study, part shrinkage had a tendency to be decreased by increasing injection speed and aspect ratio of samples.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.279-282
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• 2002

With the development of industrial society, the interest of new material is growing even in machining center. Composite materials in the new materials are superior to the metals In measure stability of strength, modulus and heat, moreover when mould is prepared, it can be done net shape manufacturing so it can be used widely in all sorts of machine parts, interior materials of car structural construct ions, the space aerial industry, ship materials, sports goods and so on. Therefore in this study, the property of processing drill on CFRP in composite materials by experimental study and some problems were examined.

• Nuclear Engineering and Technology
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• 제47권7호
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• pp.895-906
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• 2015

Background: Mitigation of primary water stress corrosion cracking (PWSCC) is a significant issue in the nuclear industry. Advanced nickel-based alloys with lower susceptibility have been adopted, although they do not seem to be entirely immune from PWSCC during normal operation. With regard to structural integrity assessments of the relevant components, an accurate evaluation of crack growth rate (CGR) is important. Methods: For the present study, the extended finite element method was adopted from among diverse meshless methods because of its advantages in arbitrary crack analysis. A user-subroutine based on the strain rate damage model was developed and incorporated into the crack growth evaluation. Results: The proposed method was verified by using the well-known Alloy 600 material with a reference CGR curve. The analyzed CGR curve of the alternative Alloy 690 material was then newly estimated by applying the proven method over a practical range of stress intensity factors. Conclusion: Reliable CGR curves were obtained without complex environmental facilities or a high degree of experimental effort. The proposed method may be used to assess the PWSCC resistance of nuclear components subjected to high residual stresses such as those resulting from dissimilar metal welding parts.

• 한국안전학회지
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• 제38권3호
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• pp.10-19
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• 2023

Fall accidents account for the highest accident fatality rate in the construction industry. In addition, wearing and using a safety belt is the most realistic and important preventive measure to reduce fall accidents. Safety belts are protective devices worn by individual workers; they prevent workers from falling and allow for time to rescue the workers. However, the legal standards for safety belts only stipulate the materials, specifications, and strength of parts; there is no provision for an auxiliary rope fixing method to fix the safety belts safely. Due to this reason, workers in industrial sites arbitrarily fix and use the auxiliary rope. Currently, the most used method to fix the auxiliary rope is to tie a knot, which significantly lowers the strength of the material compared to the standard strength. Moreover, many construction sites are located outdoors, so the strength of the materials used in the auxiliary rope is inevitably reduced due to various external environmental conditions. Therefore, to solve this problem, this study was conducted to evaluate the strength of the material of the auxiliary rope for fixing the safety belt and the knot-tying method for the auxiliary rope. In this study, the exposure conditions for the effects of temperature and moisture were set to reflect the characteristics of the construction industry. The results of this study are expected to be used for standards establishment and the safe use of the auxiliary rope for safety belts in actual field applications.

• 한국산업융합학회 논문집
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• 제23권6_1호
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• pp.881-888
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• 2020

A butterfly valve is a valve that adjusts flow rate by rotating a disc for about 90° with respect to the axis that is perpendicular to the flow path from the center of its body. This valve can be manufactured for low-temperature, high-temperature and high-pressure conditions because there are few restrictions on the used materials. However, the development of valves that can be used in a 600℃ environment is subject to many constraints. In this study, the butterfly valve's stability was evaluated by a fluid-structured interaction analysis, thermal-structure interaction analysis, and seismic analysis for the development of valves that can be used in high-temperature environments. When the reverse-pressure was applied to the valve in the structural analysis, the stress was low in the body and seat compared to the normal pressure. Compared with the allowable strength of the material for the parts of the valve system, the minimum safety factor was approximately 1.4, so the valve was stable. As a result of applying the design pressures of 0.5 MPa and 600℃ under the load conditions in the thermal-structural analysis, the safety factor in the valve body was about 3.4 when the normal pressure was applied and about 2.7 when the reverse pressure was applied. The stability of the fluid-structure interaction analysis was determined to be stable compared to the 600℃ yield strength of the material, and about 2.2 for the 40° open-angle disc for the valve body. In seismic analysis, the maximum value of the valve's stress value was about 9% to 11% when the seismic load was applied compared to the general structural analysis. Based on the results of this study, the structural stability and design feasibility of high-temperature valves that can be used in cogeneration plants and other power plants are presented.