• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1751-1753
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• 2002

Arc phenomena occur in the air, must be more diverse than vacuum and SF6. An air arc interruption method has been used in low rated voltage circuit breakers such as ACB, MCCB and MCB. Most of them have the arc chamber composed of arc chutes and lateral walls that made of many kinds of materials. Therefore, the criterion of material selection is necessary for breaking capacity improvement. So, we selected some contact and lateral wall materials, and carried out short circuit tests. Especially, some parameters of arc plasma properties were very different each polymeric wall material.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 C
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• pp.1665-1667
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• 2003

Recently, a breaking capacity increases with breaking method using gas pressure from ablation materials in low voltage circuit breakers. In this paper, we investigated arc quenching materials with spectroscopic method. Especially, Hydrogen spectrum was investigated because its dielectric characteristics are better than other gases. We selected two arc quenching materials, UP and PA6, that use in circuit breakers. They had hydrogen spectrums, but PA6 was better than UP in the qualitative aspect.

• 한국지반공학회논문집
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• 제22권6호
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• pp.15-26
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• 2006

말뚝의 지지력과 거동을 예측하기 위하여 다양한 연구들이 수행되었음에도 불구하고, 메커니즘에 대한 전반적인 이해가 아직까지 미흡한 실정이다. 이는 많은 인자들이 서로 복잡한 연관성을 맺으며 말뚝의 거동에 영향을 미치기 때문이다. 따라서 지반조건과 말뚝조건 및 항타조건 등 과 관련된 많은 인자들 가운데 지지력에 중요한 영향을 미치는 인자들을 도출하기 어려우며, 또한 인자들 간의 복잡한 연관성을 지지력 공식에 적합하게 고려하기란 매우 어렵다. 본 연구에서는 항타말뚝들에 대한 동재하시험으로부터 선단 및 주면 지지력을 포함한 지지력을 예측하기 위하여 인공신경망이 적용되었다. 첫째로, 신경망 모델링에 근거한 민감도 분석를 통하여 지지력에 대한 각 영향인자들의 영향이 검토되었다. 둘째로, 지지력 예측을 위한 최적의 인공신경망 모델을 도출하기 위하여 인공신경망과 유전자 알고리즘으로 구성된 설계기법이 적용되었다. 이를 통해 토사지반에 관입된 항타말뚝의 지지력을 산정할 수 있는 최적의 인공신경망 모델을 제안하고자 하였다. 사용된 설계기법을 통하여 적합한 입력층 조합, 은닉층 노드수과 각 층 사이의 연결구조를 도출하였다. 도출된 인공신경망 모델을 적용함으로써 항타말뚝의 지지력을 간단하며 신뢰성 있게 예측할 수 있음을 알 수 있다.

• 한국환경보건학회지
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• 제37권1호
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• pp.50-56
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• 2011

The adsorption capacity of charcoal is a function of the airborne concentration of the target chemical. To evaluate the adsorption capacity of charcoal packed in the cartridges of air purifying respirators, breakthrough tests were conducted with carbon tetrachloride for three commercial cartridges (3M models #7251, #6000 and AX) at 25, 50, 100, 250 and 500 ppm. Adsorption capacities were calculated using a mass transfer balance equation derived from the curve fitting to the breakthrough curves obtained experimentally. Carbon micropore volumes were estimated by iteration to fit the Dubinin/Radushkevich (D/R) adsorption isotherm. They were 0.6566, 0.5727 and 0.3087 g/cc for #7251, #6000 and the AX cartridge, respectively. Above 100 ppm (at high challenge concentrations), #7251 and #6000 showed higher adsorption capacities. However, as the challenge concentration decreased, the adsorption capacities of #7251 and #6000 sharply dropped. On the other hand, the adsorption capacity of the AX cartridge showed little change with the decrease of the challenge concentration. Thus, the AX showed a higher adsorption capacity than #7251 and #6000 at the 5-50 ppm level. It is concluded that service-life tests of cartridges and adsorption capacity tests of charcoal should be conducted at challenge concentration levels reflecting actual working environmental conditions. Alternatively, it is recommended to use the D/R adsorption isotherm to extrapolate adsorption capacity at low concentration levels from the high concentration levels at which breakthrough tests are conducted, at a minimum of two different concentration levels.

• 한국가스학회지
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• 제20권4호
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• pp.78-84
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• 2016

대용량 알루미늄 라이너의 제작을 위해 역 드로잉 공정을 적용하였고, 최적의 역 드로잉 공정 설계에 대한 연구를 수행하였다. $350^{\circ}C$의 어닐링된 Al6061의 인장시험 및 해석을 수행하여 라이너 성형 해석을 위한 대변형률에서의 유동응력 및 연성파괴지수를 구하였다. 역드로잉 공정의 유한요소해석을 수행하여 금형의 형상, 블랭크 홀딩력, 드로잉비, 금형간의 간격, 부분가열영향에 대해 분석하였다. 유한요소해석을 통해 주름 및 파단을 방지하는 최적의 조건을 도출하여 시제품을 제작하였으나, 드로잉된 컵의 끝부분에서 부분적인 파단이 발생하였다. 하지만 후속공정을 적용하기 위한 충분한 길이가 확보되어 플로우 포밍, 스피닝 공정을 적용하여 최종제품을 제작하였다.

• 품질경영학회지
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• 제47권4호
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• pp.847-859
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• 2019

Purpose: The companies must be located in the area, scale up, create jobs, and return to the local economy. This paper attempted to analyze empirically the relationship between regional context and entrepreneurial orientation(EO) in the region of Korea. Methods: This paper analyzed survey data and regional statistics. We measured EO by region and then examined which regional context affect EO. Regional contexts were measured by population, economic size, budget size, firm size, innovation capacity, and education level. EO was measured by innovativeness, risk taking, proactiveness, autonomy, competitive aggressiveness, and need for achievement. Results: EO was high in the region where the budget size per thousand population, the number of manufacturers per thousand population, the number of new corporations per thousand population, the number of R&D personnel per thousand population, and the number of students of higher education institutions per thousand population were high. Conclusion: The implications of this paper are that regional context affect EO, and there are differences in budget scale, firm size, innovation capacity, and education level. In regions with many investment resources for innovation and startups and manufacturers, the number of R&D personnel and students of higher education institutions (future R&D personnel), in particular, determines EO.

• 대한기계학회논문집A
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• 제36권10호
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• pp.1131-1137
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• 2012

해저배관은 부력과 외부 충격을 방지하기 위하여 1.2~4m의 매설 깊이로 설치되어 운영된다. 해저배관은 수압과 토하중에 의한 외압으로부터 소성붕괴에 대한 저항성을 가져야한다. 해저배관에 수압과 토하중으로 발생하는 원주응력을 유한요소해석으로 파악하여 배관의 건전성에 미치는 영향을 평가하였다. 내압은 외압에 의한 소성붕괴 저항성을 향상시켜 소성붕괴 발생 깊이를 증가시켰다 동일 수심에서는 매설 깊이 증가에 따라 원주응력은 증가하나, 동일 매설 깊이에서는 수심이 증가함에 따라 배관에서 발생하는 원주응력은 감소한다.

• 한국산업보건학회지
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• 제9권2호
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• pp.19-31
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• 1999

Most breakthrough tests are conducted at higher concentration levels compared to those in the field of air-purifying respirator applications. For example, typical challenge concentrations for breakthrough tests agains tcarbon tetrachloride are ranged between 250-1000 ppm although applicable concentrations range for air-purifying cartridge is 5-50 ppm for carbon tetrachloride. However, no guarantee has been made that isotherms derived from the experiment at high challenge concentrations could estimate adsorption capacity at the lower concentration range where workers wear usually air-purifying respirators. Three models of adsorption isotherms (Freundlich, Langmuir and Dubinin/Radushkevich(D/R) isotherms) that have been commonly applied for respirator cartridge testing were evaluated. Adsorption capacity at each challenge concentration was calculated from the Reaction Kinetic equation fitted for the breakthrough data. These data were used for derivation of three isotherms. In general, the D/R isotherm has given the best agreement between estimated adsorption capacities and experimentally measured. If the challenge concentration of 100 ppm is included for derivation of models, Freundlich and D/R models could succes sfully produced good estimations for adsorption capacities at 50 ppm level. Estimated adsorption capacities by both models ranged in 94 - 109 % of the experimentally measured. However, Langmuir model gives underes timation in all cases.

• 설비공학논문집
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• 제18권2호
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• pp.158-162
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• 2006

Micro gas turbine (MGT) has received attention recently as a small-scale distributed power source. Due to many advantages such as their small size, low maintenance cost and minimal vibrations during operation, they are expected to become widespread in a wide range of applications. The exhaust heat emitted by the MGT is in the form of an exhaust gas that is about $270^{\circ}C$ which is an extremely clean gas. Korea Gas Corporation (KOGAS) has researched performance characteristics of a cogeneration system combining 28kW class MGT and 13 USRT class absorption hot and chilled water generator in the local condition. The present results of this study can be summarized as follows: (1) in heating mode, the total efficiency of cogen. system is about $65\%$ and heating capacity is 33kW at 25kW MGP power (2) in cooling mode, COP is about 0.6 at 22kW MGT power.

• 대한안전경영과학회지
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• 제23권1호
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• pp.81-94
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• 2021

In SMEs, technological innovation is recognized as an important tool in terms of sustainable growth. This study analyzed the determinants of technological innovation by using the information of the corporate panel DB composed of local SMEs. The internal factors were added with technological innovation capacity and production capacity and the industrial cluster environment was first applied to external factors. Also, whether the industrial cluster environment influences technological innovation through R&D capabilities, the mediating effect was tested with the Sobel Test. Among the internal and external factors, the most important determinant was marketing ability, and a policy was proposed to develop measures to increase R&D capability with mediating effect. Among the technological innovation variables, which are dependent variables, the most determinant factor was the proportion of new product sales. For this, it is considered that additional research such as longitudinal research with the concept of repetition and parallax using the corporate panel DB is necessary.