• The Optical Journal
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• s.102
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• pp.52-55
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• 2006

본 고의 내용은 가공부의 분위기를 제어하고 가공장치 전체를 벨자(챔버)로 씌워 밀폐하고 그 안에서 가공하는 새로운 벨자형의 폴리싱 장치에 관한 것이다. 필자들이 고안, 시작한 밀폐 벨자형 폴리싱 장치는 벨자내에 각종 가스를 투입함과 동시에 일정 압력 하에서 또는 벨자내를 감압(진공)함으로서 가공부 전체의 분위기를 일정 조건으로 제어하는 것이 가능하다. 이 장치를 적용하여 다양한 가공환경 분위기 하에서 SiC와 사파이어 등의 어려운 가공 재료를 포함하는 각종 기능성 재료의 가공을 시험한 가공 특성을 소개함과 동시에 가공 메커니즘에 대해서 고찰하기로 한다. 한편, 본 원고의 번역에는 (주)그린광학의 김동균 부장이 도움을 주셨다.

• Journal of the korean Society of Automotive Engineers
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• v.10 no.6
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• pp.61-71
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• 1988

본 논문에서는 Laser Rayleigh Pyrometer에 의한 광학계의 개조와 측정기술을 발전시켜 지금까지의 측정이 불가능한 밀폐용기내에서 분출화염의 온도측정을 시도하여 분출화염에 의한 착화나 소염의 연구에 중요한 자료를 얻고자 하는데 있다. 밀폐용기내에서의 온도측정은 대기개방형에서와 같이 Laser의 에너지를 증대시키기 위해 이용한는 다중반사 Mirror가 사용될 수 없을 뿐만 아니라 약한 Rayleigh산란빛에 의하여 입사창이란 Laser Trap으로 발생하는 강한 배경광 및 분출화염 뿐만 아니고 착화된 화염에서 대량의 화학발광은 피할 수 없다. 본 논문은 이와 같은 영향을 제거하는데 노력하여 밀폐용기내의 연소장에서 온도를 측정하였으며 또 측정가능성을 시사하였다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.3
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• pp.1021-1029
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• 1991

본 연구에서는 2차원 정사각형 밀폐공간내에서 흡수 및 방사하는 회기체에 대 한 자연대류-복사 열전달을 P-1 및 P-3 근사법을 이용하고 수치해석을 통하여 유동 및 열전달 특성을 연구하였고 Plank 수, 광학두께 및 벽방사율의 영향을 조사하였다. 또한 P-3 근사해와 비교함으로써 P-1 근사해의 적용범위를 고찰하였다.

• Journal of the Korean Vacuum Society
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• v.21 no.1
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• pp.1-5
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• 2012

The measurement device of internal pressures of small components sealed hermetically was developed. The internal pressure of a sample measured with this device was 43.151 kPa, and the expanded uncertainty ($\kappa$=2) was 741 Pa. The resultant measurement ability of internal pressures in small vacuum components, which had been almost impossible previously, shows the possibility of internal vacuum detection of hermetically sealed parts.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.111-111
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• 1994

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.11
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• pp.991-998
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• 2013

A numerical study is carried out for natural convection in an enclosure with an inner hot cylinder at the center. The top wall is cold, the bottom and both side walls of the enclosure are adiabatic, and the cylinder is heated. The bottom wall is heated locally at the middle. The ratio (w) is defined by as the width of the bottom wall to that of the heated local area. The immersed boundary method (IBM) is used to model an inner circular cylinder based on the finite volume method (FVM). This study investigates the effect of w on natural convection in an enclosure with an inner heated cylinder for Rayleigh numbers of $10^6$. At $6Ra=10^6$, thermal and flow fields show time-dependent characteristics after their full development.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.4
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• pp.73-78
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• 2020

The main reasons that ignite the propellant in the process of producing solid rocket motor are worker mistakes, wrong working process, mechanical defects, impact, friction, electrostatic and short circuits. In the past decades, many accidents have occurred in the process of producing solid rocket motor, accidents investigation have confirmed that the sensitivity of electrostatic is very high under specific condition. In this paper, we analyzed overseas accident cases and measured the sensitivity of electrostatic in the situation of confinement and pressure load by considering the manufacturing process. As a result of the test, the sensitivity of propellant was increased in the situation of confinement and pressure load and the propellant reacted more sensitively to electrostatic in the situation of confinement than pressure load.

• Journal of the Korean Society of Food Science and Nutrition
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• v.17 no.2
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• pp.158-163
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• 1988

The changes of the physico-chemical properties and fatty acid compositions of cooked soybean oil, 30 min at $180{\pm}5^{\circ}C$, were investigated to compare the antixidative effects of some antioxidants such as BHA, ${\alpha}-tocopherol$ and sesamol according to various storage conditions(room temperature, room temperature with a air tight in the dark and low temperature with air tight) for 4 weeks. The order of antioxidative effects according to different storage conditions was low temperature with air tight, room temperature with air tight in the dark and room temperature. Acid values, peroxide values and carbonyl values of soybean oil stored under low temperature with air tight after ${\alpha}-tocopherol$ treatment were similar to those of soybean oil stored under room temperature after BHA treatment. The relative contents of linoleic acid and linolenic acid decreased during storage, wheras those of oleic acid and palmitic acid increased. The contents of linoleic acid in soybean oil treated with ${\alpha}-tocopherol$ and BHA under low temperature with air tight storage were $53.61{\sim}50.29%$ and $53.78{\sim}50.68%$, respectively. These contents were very high in comparison with those in untreated oil under room temperature storage, $52.09{\sim}43.96%$.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.2
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• pp.232-237
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• 2018

According to the MAIIF report, from 1998 to 2009, 101 incidents involving entering enclosed spaces aboard ships resulted in 93 deaths and 96 casualties. IMO has therefore amended the Recommendations for entering Enclosed Spaces Entry and SOLAS 1974 Convention Chapter 3 Regulation 19, which mandates enclosed spaces entry and rescue drill on a regular basis. The training of entering such enclosed spaces should be practical, recognizing all possible risks of entering enclosed spaces aboard ships, while also considering the safety of trainees during the training. Recently, educational contents utilizing virtual reality (VR) have been applied in various fields to improve education and training effects, and these methods have proven to have advantages in actual and repetitive learning without being limited to physical space. In this study, the effectiveness, characteristics and differentiation of training of entering enclosed spaces aboard ships using VR were compared with traditional class room lectures through quantitative evaluation and questionnaires of training participants. Through the evaluation and questionnaire, it was found that participants using VR understood and learned the required training elements better than the control group, all of whom were trained through the normal class room lecture. Moreover, participants reported to display preference for training with the help of VR. As a result of the study, it was confirmed that the learning effects of VR onboard training can be used as an effective training method, especially by using video and other types of simulators.

• Conservation Science in Museum
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• v.3
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• pp.71-78
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• 2001

The airtightness of museum cases in museums was measured by using CO₂ tracing gas, but it has been pointed that it has a problem with measuring the airtightness of a museum case which has a hole inside before it is used or while is being used. So studies tried to come up with alternatives which make it possible to measure the airtightness of a museum case before it is used or while it is being used if necessary by indirectly measuring the airtightness of the museum case without changing its form. Indirect measuring is done by measuring the change of Art-sorb weight and the change of temperature and humidity inside the museum case. Experiments were made for 12 days with three builtin wall case installed at the same place without turning on the lights but with Art-sorb and the data logger of temperature and humidity put into museum case. The change rate was produced with the change of temperature and humidity inside the museum case divided by that of those around museum case. As a result, the temperature change rate of museum case A(0.67) was lower than that of museum case B(0.69) or museum case C(0.79). The humidity change rate of museum case A(0.12) was lower than that of museum case B(0.19) or museum case C(0.72) showing that its airtightness was the best. Also in the direct airtightness measurement by CO₂ tracing gas, the air exchange rate was compared with the humidity change rate by Art-sorb in the indirect measurement.