• 한국화재소방학회논문지
• /
• 제26권5호
• /
• pp.13-20
• /
• 2012

매년 많은 소방공무원들이 화재나 고온 조건 등에 노출되어 화상으로 고통 받고 있어, 화상 예측에 대한 연구를 통해 화상을 방지할 수 있는 방법의 개발이 매우 중요하다. 그러나 피부조직의 비선형성, 혈류에 의한 열전달 분석의 불확실성 등 인체 내부의 복잡한 물리현상으로 인해 화상에 대한 연구는 매우 부족한 것이 실정이며, 특히 국내의 경우는 이에 대한 연구가 전무한 실정이다. 본 연구에서는 특히 심각한 화상을 유발할 수 있는 돌발화염(80 kW/$m^2$ 이상의 고열 유속 조건)하에서의 2도 화상 발생에 대한 예측을 수행하였다. 생체 열전달 방정식(Bio-heat transfer)을 이용하여 지배방정식을 유도하였으며, 유한차분법(Finite Difference Method)을 활용하여 화상에 대한 예측을 수행하는 수치해석 접근법을 사용하였다. 기존의 여러 연구결과로부터 인체 피부의 열물성치를 정리하였고, 그것을 바탕으로 계산을 수행하였다. 기존의 낮은 열유속에 대한 화상 실험 결과와 예측 결과를 비교하여 가장 오차가 적은 열물성치 모델을 파악하였고, 그 결과를 바탕으로 고열유속의 돌발화염에서의 2도 화상발생 노출시간을 예측하여 제시하였다.

• Animal cells and systems
• /
• 제16권3호
• /
• pp.207-214
• /
• 2012

Burns are one of the most devastating forms of trauma and wound healing is a complex and multicellular process, which is executed and regulated by signaling networks involving numerous growth factors, cytokines, and chemokines. Recombinant human granulocyte macrophage colony-stimulating factor (rhGM-CSF) was specifically produced from rice cell culture through use of a recombinant technique in our laboratory. The effect of rhGM-CSF on promotion of deep second-degree burn wound healing on the back skin of a hamster model was evaluated through a randomized and double-blind trial. As macroscopic results, hamster skins of the experimental groups showed earlier recovery by new epidermis than the control groups. Immunohistochemical reactions of proliferating cell nuclear antigen and transforming growth factor-b1, which are indicators of cell proliferation, were more active in the experimental group, compared with the control group. On electron microscopy, basal cells in the epidermis of the experimental group showed oval nuclei, prominent nucleoli, numerous mitochondria and abundant free ribosomes. In addition, fibroblasts contained well-developed rough endoplasmic reticulum with dilated cisternae. Bundles of collagen fibrils filled the extracellular spaces. Particularly, ultrastructural features indicating active metabolism for regeneration of injured skin at 15 days after burn injury, including abundant euchromatin, plentiful free ribosomes, and numerous mitochondria, were observed. These findings suggest that use of rhGM-CSF could result in accelerated deep second-degree burn wound healing in animal models.

• 한국자동차공학회논문집
• /
• 제4권2호
• /
• pp.221-229
• /
• 1996

The engine speed fluctuation at idle operation mainly comes from cyclic variation of combustion in SI engine. In the present study, engineering model that is representing the cyclic variation of combustion was proposed for the sub-model of the engine cycle simulation. From the observed behaviors of the mass burn rates, probability density functions for the parameters of Wiebe function were defined. The mass burn rate of each cycle is obtained by Monte Cralo perturbation method with the probability function. The simulation results shows that trends of cylinder pressure variation and imep distribution follow up with those of experimental results at idle condition.

• 한국가스학회지
• /
• 제13권3호
• /
• pp.43-48
• /
• 2009

The energetic and environmental problems have been getting serious after the revolution of modern industry. Therefore, demand of gas as an eco-friendly energy source is increasing. With the demand of gas, the use of gas is also increased, so injury and loss of life by the fire have been increasing every year. Hence the influence on flame caused by Vapor Cloud Explosion in enclosure of experimental booth was calculated by using the API regulations. And the accident damage was estimated by applying the influence on the adjacent structures and people into the PROBIT model. According to the probit analysis, the spot which is 5meter away from the flame has nearly 100% of the damage probability by the first-degree burn, 27.8% of the damage probability by the second-degree burn and 14.5% of the death probability by the fire.

• 한국자동차공학회논문집
• /
• 제7권8호
• /
• pp.24-33
• /
• 1999

This paper investigate the effects of the variations of engine operation condition in the flame kernel formation and developmnet . A model for calculating the initial kernel development in spark ignition engines is formualted. It considered input of electrical energy, combustion energy release and heat transfer to the spark plyg, cylinder head, and unburned mixture. The model also takes into accounts strain rate of initial kernel and residual gas fraction. The breakdown process and the subsequent electrical power input initially control the kernel growth while intermediate growth is mainly dominated by diffusion or conduction. Then, the flame propagates by the chemical energy and turbulent flame expansion. Flame kernel development also influenced by engine operating conditions, for example, EGR rate, air-fuel ration and intake manifold pressure.

• 한국원자력학회:학술대회논문집
• /
• 한국원자력학회 2001년도 춘계학술발표회요약집
• /
• pp.335-335
• /
• 2001

• Experimental and Molecular Medicine
• /
• 제50권12호
• /
• pp.3.1-3.14
• /
• 2018

Type 1 diabetes mellitus (T1DM) is a pathological condition associated with osteopenia. $WNT/{\beta}$-catenin signaling is implicated in this process. Trabecular and cortical bone respond differently to $WNT/{\beta}$-catenin signaling in healthy mice. We investigated whether this signaling has different effects on trabecular and cortical bone in T1DM. We first established a streptozotocin-induced T1DM mouse model and then constitutively activated ${\beta}$-catenin in osteoblasts in the setting of T1DM (T1-CA). The extent of bone loss was greater in trabecular bone than that in cortical bone in T1DM mice, and this difference was consistent with the reduction in the expression of ${\beta}$-catenin signaling in the two bone compartments. Further experiments demonstrated that in T1DM mice, trabecular bone showed lower levels of insulin-like growth factor-1 receptor (IGF-1R) than the levels in cortical bone, leading to lower $WNT/{\beta}$-catenin signaling activity through the inhibition of the IGF-1R/Akt/glycogen synthase kinase $3{\beta}$ ($GSK3{\beta}$) pathway. After ${\beta}$-catenin was activated in T1-CA mice, the bone mass and bone strength increased to substantially greater extents in trabecular bone than those in cortical bone. In addition, the cortical bone of the T1-CA mice displayed an unexpected increase in bone porosity, with increased bone resorption. The downregulated expression of WNT16 might be responsible for these cortical bone changes. In conclusion, we found that although the activation of $WNT/{\beta}$-catenin signaling increased the trabecular bone mass and bone strength in T1DM mice, it also increased the cortical bone porosity, impairing the bone strength. These findings should be considered in the future treatment of T1DM-related osteopenia.

• International Journal of Automotive Technology
• /
• 제6권6호
• /
• pp.591-598
• /
• 2005

A three-way catalyst system of a natural gas vehicle (NGV) has characteristics of higher fuel consumption and higher thermal load than a lean-bum catalyst system. To meet stringent emission standards in the future, NGV with the lean-bum engine may need a catalyst system to reduce the amounts of HC, CO and NOx emission, although natural gas system has low emission characteristics. We conducted experiments to evaluate the conversion efficiency of the NOx reduction catalyst for the lean-burn natural gas engine. The NOx reduction catalysts were prepared with the ${\gamma}-Al_{2}O_3$ washcoat including Ba based on Pt, Pd and Rh precious metal. In the experiments, effective parameters were space velocity, spike duration of the rich condition, and the temperature of flowing model gas. From the results of the experiments, we found that the temperature for maximum NOx reduction was around $450^{\circ}C$, and the space velocity for optimum NOx reduction was around $30,000\;h^{-1}$ And we developed an evaluation model of the NOx reduction catalyst to evaluate the conversion performance of each other catalysts.

• 한국학교ㆍ지역보건교육학회지
• /
• 제20권1호
• /
• pp.85-95
• /
• 2019

Objectives: This study is to examine the influences of three sub-factors of resilience on academic burn out among a group of university students, with low resilience, majored in public health. Methods: The survey was made during January 1 to 13, 2017 and after checking the resilience scores of 166 respondents and the questionnaires of 115 respondents, whose scores were less than 195, an average score of Korea, were selected and analyzed using AMOS. Results: The average resilience and academic burn-out scores were 173 and 2.96, respectively. The goodness-of-fit of proposed model showed RMSEA=0.068, GFI=0.916, NFI=0.901, IFI=0.963, CFI=0.962 so, final measurement model was selected. The analysis of the suggested model showed that among three sub-factors of resilience, only self-control ability had a negative(-) effect on academic burnout and two others were shown to have no effects. Conclusion: By researching and introducing a education method that could enhance self-control ability, it would effectively reduce academic burnout in university students with low resilience and majored in public health.

• International Journal of Korean Welding Society
• /
• 제1권2호
• /
• pp.30-35
• /
• 2001

Nowadays, repair welding on in-service natural gas pipeline is a matter of primary concern of gas company. The main purpose of this study is to investigate the effects of welding conditions on the allowable heat input for crack-free welds and welds without burn-through onto in-service natural gas pipeline. First of all, single pass weld bead on plates of the various thickness was deposited to evaluate the penetration of weld metal, the depth of heat affected zone and the hardness of repair weld under various welding conditions. Also, finite element analysis has been conducted to validate experimental results of bead-on plate welds and to develop appropriate model for repair welding. The welding experiments of bead-on-plate weld confirmed the influence of plate thickness, heat input and welding process on safety. And, the finite element model was demonstrated by comparing experimental results. The agreement between the computed and measured values was shown to be generally good. Therefore, It is possible to predict the safety of repair welding under various welding conditions with experimental results and finite element analysis model.