• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.4
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• pp.34-39
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• 2016

Arrhenius kinetic constants, the activation energy and the pre-exponential factor, of energetic material $BKNO_3$ are estimated using Differential Scanning Calorimetry (DSC). Different from the conventional way, the activation energy was estimated more precisely through DSC aging trial, and the consumed fraction by heat was calculated by comparing the integration of heat flow. We suggested the condition of accelerated aging test for the energetic material $BKNO_3$ and reconsidered the meaning of the thermal accelerated aging.

• Proceedings of the Korean Institute of Industrial Safety Conference
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• 2000.06a
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• pp.120-123
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• 2000

최근 첨단 과학기술의 급속한 발전에 따라 각종 화학물질이 여러분야에서 제조되고 또한 취급되고 있다. 이들 화학물질은 그 합성, 정제 및 사용법 등에 대해서는 각종 문헌에 잘 기재되어 있으나 그 위험성에 대해서는 충분히 파악되어 있지 않았거나 발표되어 있지 않은 것이 많아 대상이 되는 반응조건 이나 제조조건을 변경해야하는 경우 제조자 스스로 결정해야 하는 경우가 많아 뜻하지 않은 재해가 발생하는 예가 증가하고 있다. 따라서 본 연구에서는 의약품 및 농약 등 합성시 중간체로서 널리 사용되고 있으나 구조적인 특성상 열에 매우 불안정하여 산안법상 위험물중 폭발성물질로 분류되어 있는 니트로페닐하이드라진에 대한 열분해 특성을 시차주사열량계(DSC) 및 가속 속도열량계(ARC) 이용하여 그 위험성을 평가하였다. (중략)

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.172-178
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• 2017

Thermal property is one of the important characteristic in the field of energetic materials. As the energy material is released during decomposition, DSC(Differential Scanning Calorimetry) is frequently used for the thermal analysis. In case of the dynamic DSC measurements, thermal dynamic change like melting is prevented from the thermal property measurements. And due to the predicting kg scale, the conditions of the heat exchange with the environment significantly is changed. In this study, As the method to resolve the problem, we predict the thermal aging property using the AKTS thermokinetic program from DSC measurements which performed isothermal method. Predicting the thermal aging properties from ARC(Accelerating Rate Calorimetry) measurement, we compare two results.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.559-559
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• 2013

KSTAR (Korea Superconducting Tokamak Advanced Research) 장치는 차세대 에너지원 중의 하나인 핵융합로를 위한 과학기술 기반을 마련하기 위해 개발된 중형급 토카막 실험장치로서 토카막 운전 영역의 확장과 안정성 확보, 정상상태 운전 도달을 위한 방법 연구, 최적화된 플라즈마 상태와 연속 운전 실현 등을 주요 목표로 하고 있다. 이를 위해 핵융합 반응에 의한 점화조건과 가까운 상태로 플라즈마를 가열해주어야 하며, 토카막 장치의 저항가열 이외에도 외부에서 추가 가열이 반드시 필요하다. 중성 입자빔 입사 장치는 현재 토카막에서 사용되고 있는 가열장치 중 가장 신뢰성있는 추가 가열 장치라 할 수 있으며 한국 원자력연구원에서는 1997년부터 KSTAR 토카막 실험 장치에 사용될 중성 입자빔 입사 장치를 개발해왔었다. 중성빔 입사 장치는 크게 이온원, 진공함, 열량계, 진공 펌프, 중성화 장치, 이온덤프와 전자석으로 이루어져 있으며, 이중 이온원은 중성빔의 성능을 좌우하는 핵심적인 장치라 할 수 있다. 최근 한국원자력연구원에서는 2 MW 중성 입자빔 입사장치용 이온원 개발을 완료하여 KSTAR 토카막 장치에 설치하였으며, 2013년 현재 KSTAR에는 총 두 개의 이온원이 장착되어 최대 약 3 MW 이상의 중수소 중성 입자빔을 입사하여 KSTAR 토카막 실험의 H-mode 달성과 운전 시나리오 연구에 많은 기여를 하고 있다. 한국원자력연구원에서 최초로 개발된 이온원은 미국 TFTR 장치에서 사용되었던 US LPIS (Long Pulse Ion Source)를 기본으로 하여 국내 개발을 수행하였다. 이 온원은 크게 플라즈마를 발생시키는 플라즈마 발생부와 발생된 이온을 인출 및 가속시키는 가속부로 구성되는데, 개발과정에서 가장 먼저 KSTAR의 장주기 운전에 적합하도록 플라즈마 방전부와 가속부의 냉각회로를 요구되는 열부하에 맞게 설계 수정하였다. 그 후 플라즈마 방전부는 방전 시간과 안정성, 플라즈마 밀도의 균일도, 정격 운전, 방전 효율 등을 고려하여 수정 보완하며 개발을 진행하여왔다. 가속부의 경우 국내 제작기술의 한계를 극복하기 위해 빔 인출그리드를 TFTR의 US LPIS 모델의 슬릿형 그리드 타입에서 원형 인출구 타입으로 변경하였으며, 이후 가속 전극의 고전압 내전력 문제, 빔 인출 전류와 전력, 인출 빔의 광학적 질(quality), 빔 인출 시간 동안의 안정성 등을 위해 그리드의 크기와 간격, 모양 등을 변경하여 개발을 수 행하여 왔다. 이 논문은 한국원자력연구원에서 개발이 진행되어 왔던 이온원들을 시간적으로 되짚어 보면서 현재까지의 성과와 문제점, 그리고 앞으로의 개발 방향에 대해 논의하고자 한다.

• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.2
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• pp.59-65
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• 2018

We conducted an isothermal slow cook-off(ISCO) test for an aluminized explosive containing AP. The sample bulged before the run-away reaction, and therefore we were unable to obtain the ISCO data. However, these phenomena did not occur for a certain AP grade, which means that the quality of the AP exerted a significant effect on the thermal stability of the explosive formulation. In this study, we investigated the thermal stability difference between a good and bad AP grade. First, we characterized the thermal properties of all APs by Differential Scanning Calorimeter(DSC) and correlated them to the ISCO phenomena. In addition to the DSC study and ISCO test, we also investigated and calculated the SADT and self-heating rate by the ARC of the different AP qualities to interpret the thermal stability of the explosive formulation. Moreover, we investigated the impurity of the AP and a preparation method to remove the included impurity and crystallization. Finally, we implemented qualification methods to identify the quality of AP by DSC using a high-pressure crucible.

• Journal of the Korean Institute of Gas
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• v.17 no.4
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• pp.1-8
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• 2013

The aim of this study is to assess thermal hazards of polystyrene polymerization process by bulk polymerization with accelerating rate calorimeter(ARC) and Multimax reactor system(MM). From this study, we found out that the polymerization process should be operated at reaction temperature of $120^{\circ}C{\sim}130^{\circ}C$. At reaction temperature over $130^{\circ}C$, there was a runaway reaction hazard due to the temperature control failure following a viscosity increase of reaction products. With a cooling failure of a reactor in the early stage of process operation at the reaction temperature ($120^{\circ}C{\sim}130^{\circ}C$), there was a high thermal hazard of burst of a reactor's rupture disk or explosion of a reactor caused by the rapid rise of temperature and pressure to $340^{\circ}C$, 5.3 bar respectively within 30 - 50 minutes.

• Journal of the Korean Electrochemical Society
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• v.12 no.3
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• pp.239-244
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• 2009

This paper aims to report the effect of surface treatment on graphite and its effect on the improvement of $Al_2O_3$ and $nano-Li_4Ti_5O_{12}$. The structure and property of surface treatment on graphite were determined by scanning electron microscopy, transmission electron microscopy and electrochemical property and safety were determined by charge/discharge cycler, accelerating rate calorimeter. The composite with different metallic oxide exhibited the first efficiency of 82.5% and specific capacity of 350 mAh/g. Although the composite showed same efficiency and specific capacity at first cycle, surface treatment on graphite by $nano-Li_4Ti_5O_{12}$ exhibited a higher charge/discharge rate, cycle life and thermal stability.

• Korean Journal of Community Nutrition
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• v.21 no.6
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• pp.520-532
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• 2016

Objectives: The objective of this study was to assess energy expenditure and metabolic cost (METs) of walking activities of college students and to compare treadmill based walking with self-selected hallway walking. Methods: Thirty subjects (mean age $23.4{\pm}1.6years$) completed eight walking activities. Five treadmill walking activities (TW2.4, TW3.2, TW4.0, TW4.8, TW5.6) were followed by three self-selected hallway walking activities, namely, walk as if you were walking and talking with a friend: HWL (leisurely), walk as if you were hurrying across the street at a cross-walk: HWB (brisk) and walk as fast as you can but do not run: HWF (fast) were performed by each subject. Energy expenditure was measured using a portable metabolic system and accelerometers. Results: Except for HWF (fast) activity, energy expenditures of all other walking activities measured were higher in male than in female subjects. The lowest energy expenditure and METs were observed in TW2.4 ($3.65{\pm}0.84kcal/min$ and $2.88{\pm}0.26METs$ in male), HWL (leisurely) ($2.85{\pm}0.70kcal/min$ and $3.20{\pm}0.57METs$ in female), and the highest rates were observed in HWF (fast) ($7.72{\pm}2.81kcal/min$, $5.84{\pm}1.84METs$ in male, $6.65{\pm}1.57kcal/min$, $7.13{\pm}0.68METs$ in female). Regarding the comparison of treadmill-based walking activities and self-selected walking, the energy expenditure of HWL (leisurely) was not significantly different from that of TW2.4. In case of male, no significant difference was observed between energy costs of HWB (brisk), HWF (fast) and TW5.6 activities, whereas in female, energy expenditures during HWB (brisk) and HWF (fast) were significantly different from that of TW5.6. Conclusions: In this study, we observed that energy expenditure from self-selected walking activities of college students was comparable with treadmill-based activities at specific speeds. Our results suggested that a practicing leisurely or brisk walking for a minimum of 150 minutes per week by both male and female college students enable them to meet recommendations from the Physical activity guide for Koreans.

• Journal of the Korean Dietetic Association
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• v.23 no.1
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• pp.78-93
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• 2017

The purposes of this study were to assess energy expenditure of eight walking activities in normal weight and overweight or obese high school students and to evaluate the accuracy of two accelerometers worn on the ankle and waist. Thirty-five (male 17, female 18) healthy high school students participated in this study. They were classified into normal weight (n=21) and overweight or obese (n=14) groups. The subjects completed five treadmill walking activities (TW2.4, TW3.2, TW4.0, TW4.8, TW5.6), followed by three self-selected hallway walking activities (walk as if walking and talking with a friend: HWL, walk as if hurrying across the street at a cross-walk: HWB, walk as fast as you can but do not run: HWF). Energy expenditure and metabolic equivalents (METs) were measured using a portable indirect calorimeter, and predicted energy expenditures and METs were derived from two accelerometers placed on the ankle and waist. Measured energy expenditures per body weight (kg) of eight walking activities were significantly higher in the normal weight group than in the obese group and significantly higher in female than male. The ankle accelerometer overestimated energy expenditures and METs (bias 49.4~105.5%), whereas the waist accelerometer underestimated energy expenditures and METs (bias -30.3~-85.8). Except for HWF (fast) activity, METs of seven activities were moderate intensity based on Compendium METs intensity categories. HWF (fast) activity was vigorous intensity. METs from the ankle accelerometer were vigorous intensity except TW2.4 activity (moderate intensity). METs from the waist accelerometer were low intensity (TW2.4, TW3.2, TW4.0, TW4.8, HWL) and moderate intensity (TW5.6, HWB, HWF). Physical activity guidelines were developed based on measured physical activity level of high school students. Further studies should investigate the effects of body composition in larger subjects.