• Nuclear Engineering and Technology
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• 제52권1호
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• pp.37-50
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• 2020

A passive containment cooling system (PCCS) has been developed as advanced safety feature for innovative power reactor (iPOWER). Passive systems are inherently less stable than active systems and the PCCS encountered the flashing-induced instability previously identified. The objective of this study is to develop stability maps for flashing-induced instability using MARS (Multi-dimensional Analysis of Reactor Safety) code. Firstly, we conducted a series of sensitivity analysis to see the effects of time step size, nodalization, and alternative MARS user options on the onset of flashing-induced instability. The riser nodalization strongly affects the prediction of flashing in a long riser of the PCCS, while time step size and alternative user options do not. Based on the sensitivity analysis, a standard input and an analysis methodology were set up to develop the stability maps of PCCS. We found out that the calculated equilibrium quality at the exit of the riser as a stability boundary above 5 kW/㎡ was approximately 1.2%, which was in good agreement with Furuya's results. However, in case of a very low heat flux condition, the onset of instability occurred at the lower equilibrium quality. In addition, it was confirmed that inlet throttling reduces the unstable region.

• 대한통합의학회지
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• 제8권4호
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• pp.191-202
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• 2020

Purpose : The purpose of this study is to examine the effect of the segmental mobilization technique of the lower back on the characteristics of the muscles and limited of stability of chronic backache patients. Methods : The subjects of the study were 30 chronic back pain patients who were divided into groups of 15, a manual therapy group (Group I) and a spinal decompression therapy group (Group II), via random assignation. The subjects had 15 minutes of superficial heat therapy, 15 minutes of interference wave therapy, and 5 minutes of ultrasound therapy for conservative physical therapy. Additionally, manual therapy and spinal decompression therapy were administered to each group for 30 minutes, 5 times a week for 8 weeks. Before intervention, the characteristics of the muscles and limited of stability of the muscles were analyzed. After 8 weeks of intervention, the above items were re-measured in the same manner and analyzed between groups. Results : The results of comparative analysis of the characteristics of the muscles and limited of stability between groups showed that there were statistically significant differences. The manual therapy group (Group I) showed significant differences in characteristics of the muscles compared to the spinal decompression therapy group (Group II). The manual therapy group (Group I) showed significant differences in limited of stability compared to the spinal decompression therapy group (Group II). Conclusion : The result confirmed that manual therapy was more effective in the characteristics of the muscles and limited of stability. Based on this study, additional studies are necessary on the effect of various techniques of manual therapy on muscle activity and muscle thickness in chronic back pain patients. In order to develop an effective manual therapy program, studies using a variety of evaluations are needed.

• 대한기계학회논문집B
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• 제34권4호
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• pp.399-408
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• 2010

질소 희석된 프로판 층류 부상 화염에서 화염진동 불안정성과 화염 곡률 효과를 살펴보기 위하여 실험적 연구를 수행하였다. 화염 진동은 총 3가지 영역으로 열손실에 의한 진동, 열손실 및 부력이 혼재된 진동, 그리고 열손실 및 루이스 수에 의한 영향이 혼재된 진동으로 구분되었다. 순수 열손실에 의한 진동은 루이스 수에 의한 진동과 부력에 의한 수력학적 불안정성과 관련이 없으며 연료 루이스 수에 관계없이 모든 부상화염 조건에서 관찰되었다. 화염의 시간에 따른 부상높이 변화에 대한 FFT분석을 통해 화염진동 불안정성의 실험적 증거와 특성을 명확히 제시하였고, 부상 화염의 열손실에 의한 자기진동의 메커니즘에 대한 시나리오를 논의한다.

• Journal of Microbiology and Biotechnology
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• 제15권5호
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• pp.965-970
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• 2005

In our previous study [14], we found that heat-shock exposure did not stimulate the neutral trehalase activity in Sacchromyces cerevisiae KNU5377, but did in ATCC24858. Consequently, the trehalose content in KNU5377 became 2.6 times higher than that in ATCC24858. Because trehalose has been shown to stabilize the structure and function of some macromolecules, the present work was focused to elucidate the relationship between trehalose content of these strains and thermal stabilities of whole cells, through differential scanning calorimetry (DSC), and to predict critical targets calculated from the hyperthermic cell killing rates. These analyses showed that the prominent DSC transition of both strains gave identical $T_m$ (transition temperature) values in exponentially growing cells, and that the $T_m$ values of critical targets was about $3^{\circ}C$ higher in KNU5377 than in ATCC24858. Both heat-shocked KNU5377 and ATCC24858 cells displayed similar shifts in their DSC transition profiles. On the other hand, the $T_m$ value of the critical target of KNU5377 was decreased by $2.1^{\circ}C$, which was still higher than ATCC24858 showing no changes. In view of these results, the intrinsic thermotolerance of KNU5377 did not appear to result from the stability of entire cellular components, but rather possibly from that of particular macromolecules, including critical targets, even though it should be investigated in more details. Although the trehalose levels in heat-shocked cells are significantly different, as described in our previous study [14], the overall pattern of thermal stabilities and their predicted critical targets in two heat-shocked strains seemed to be identical. These data suggest that the trehalose levels examined before and after heat shock of exponentially growing cells are not closely correlated with the stabilities of whole cells and/or critical targets in both yeast strains.

• 대한한방소아과학회지
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• 제14권2호
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• pp.133-140
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• 2000

Purpose : Posterior Neck Pain and Back Pain are common diseases in human daily life. For reducting symptom and treatment of these diseases, many methods have been used and studied until now. The mechanisms of Ceragem Master Heat Bed(R)(Ceragem Co. Seoul, Korea) are infrared-heat therapy from natural nephrite and pressure therapy by up-down movement of natural nephrite ball. Through this study, authors would evaluate the clinical effectiveness of Ceragem Master Heat Bed(CMHB) on relieving posterior neck pain and back pain. Materials and methods : From 12-01-2000 to 01-13-2001, posterior neck pain and back pain patients were selected for experiment group(23patients) and control group(14patients). In both group, Visual Analog Scale(VAS) of pre-treatment stage is above 5 points. Experiment group were cared with acupuncture therapy, buhang therapy and CMHB. Control group were managed with only acupuncture therapy and buhang therapy. They were treated more than three times at least. At pre-treatment and post-treatment stage, we measured VAS for individual patients, and then compared effect of treatment in experiment group and in control group. Statistical analysis was preformed using SAS program. Results : In this study, a mean difference of VAS between pre-treatment and post-treatment stage was large in experiment(CMHB) group more than in control group(p〈0.01). Conclusion : Experiment(CMHB) group was more effective pain relief than control group in the treatment of posterior neck pain and back pain. CMHB was available for stimultaneous application of heat therapy and pressure massage together that gave another effects of mental stability and fatigue recovery. As the results of this study, CMHB could be used as a helpful treatment modality for posterior neck pain and back pain.

• 한국전자통신학회논문지
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• 제13권1호
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• pp.265-276
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• 2018

지상에 고정된 기기로 감시하기 어려운 대기 하층의 관측 사각 지역에서 유용한 관측 및 자료 분석 기술을 개발하였다. 상층 기상 관측에 사용되는 UHF 라디오존데를 UAV에 탑재하여 기온과 상대습도의 연직 자료를 원격 수집하여 10 m 기상 타워에서 측정한 자료와 비교하였다. 검증된 연직 분포로부터 외삽된 지표 기온과 총체 전달 방법을 이용하여 대기 안정도 변화에 따른 현열 플럭스를 추정하였다. 지상에서 3차원 초음파 풍속계로 측정한 현열 플럭스와 비교한 결과는 원격탐사로 산출되는 현열 플럭스에 허용되는 오차 범위 30%보다 작은 23% 이내의 오차를 보였다. UAV 관측 현열 플럭스로부터 추정한 대기경계층 고도는 대기 오염 확산 모델에 유용한 자료를 실시간, 경제적으로 제공할 수 있다.

• 복식문화연구
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• 제25권6호
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• pp.880-892
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• 2017

In this study, the appearance change and the heat moisture transfer properties of knitted fabric by yarn shrinkage were examined to obtain useful data on the development of thermo-sensitive functional materials. Eleven types of knitted fabric were knitted using highly bulky acrylic-blended yarn. After shrinking the specimens using dry heat treatment, the appearance change and thickness were measured. An HEC simulator was adopted for measuring the heat moisture transfer properties of specimens by yarn shrinkage. When holes were arranged vertically in the mesh structure, the specimens with 2,500 and 5,000 holes showed high percent change of hole area, appearance, and thickness. When holes were diagonally arranged in the mesh structure, the percent change of hole area in the specimen with 1,250 holes was larger than the one with 2,500 holes. However, the dimensional stability of the specimen with 2,500 holes was better because of its smaller appearance and thickness change. In the tuck structure, the percent change of hole area in the specimen with 625 and 416 holes was relatively large compared with the appearance and thickness change. Furthermore, the hole size in the tuck structure was smaller than that in the mesh structure but the percent change of hole area was larger. Therefore, it was proved that the tuck structure is more suitable than the mesh structure for developing thermo-sensitive functional materials. Heat moisture transfer property test verified that the change of hole area by yarn shrinkage enabled obtaining the thermal effect due to the distinct temperature difference in the inner layer.

• 한국가스학회지
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• 제15권2호
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• pp.82-87
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• 2011

열매체유는 화학공장의 가열시스템, 열교환 시스템, 가스플랜트 공정, 사출성형 시스템 및 펄프제지 공정 등에 사용된다. 열매체유는 고열이나 산화분해에 아주 안정하고 저항성이 있으며, 누출이나 방출의 경우 점화원을 만나면 쉽게 발화한다. 본 논문은 열메체유의 신유와 사용유에 대해 인화성과 열적 안정성을 고찰하였다. 열매체유의 인화성은 인화점과 자연발화점을 측정하여 평가하였고, 열적안정성은 열안정성시험기와 시차주사열량기를 사용하여 평가하였다. 실험결과로부터 열매체유의 적절한 사용과 취급과 관련된 안전대책 수립을 위해 화재 위험 특성을 제시하였다.

• 한국식품조리과학회지
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• 제10권1호
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• pp.63-70
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• 1994

Oleoresin, 6-gingerol and 6,10-gingerol: 6-paradol= 1 : 1 mixture were extracted from ginger (Zingi-her of ficinale Roscoe) and changes of its antioxidant activity by heat-treatment were studed. Oleoresin was extracted with Ethanol-Ether and 6,10-gingerol : 6-paradol(1 : 1) and 6-gingerol were extracted with Hexane and Hexan : Ether= 1 : 1, respectively, and identified on the Thin-layer Chromatograpy (TLC) plate with the solvent system of Hexane Ether(1 : 4, v/v). And oleoresin was heat-treated during 0, 10, 30, 60, 120 minutes, and 6-gingercl and 6,10-gingerol . 6-paradol=1 : 1 were heat-treated during 0, 5, 10, 20, 40 minutes, respectively, at 140$^{\circ}C$ dry oven. To compare with antioxidant activity, oleoresins were added into soybean oil at 3fo level, 6-gingerol and 6,10-gingerol : 6-paradol= 1 : 1 at 0.1% level, BHT and TBHQ at 0.02% level, respectively. All the substrates treated were stored in a incubator at 45 2$^{\circ}C$ condition. The oxidative stability was estimated by the analysises of peroxide value and conjugated diene value during storage. The results were as follows: Antioxidant activity of oleoresins were considerably high and by heat-treatment were not decreased. 6-paradol was not show the antioxidant activity. 6,10-gingerol : 6-paradol=1 : 1 provided poor protection for soybean oil. Antioxidant activity of 6-gingerol was higher than 6,10-gingerol : 6-paradol=1 : 1 and by heat-treat-ment antioxidant activity was directly decreased. Relative antioxidant effectiveness(RAE) of each antio-xidant was compared. RhR was found to decrease as follow : TBHQ>oleoresin》BHT TBHQ》BHT>6-gingerol》6,10-gingerol : 6-paradol=1 : 1.

• Advances in nano research
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• 제16권4호
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• pp.341-352
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• 2024

This study investigates the heat and mass transfer characteristics of a MoS₂ nanoparticle suspension in ethylene glycol over a porous stretching sheet. MoS₂ nanoparticles are known for their exceptional thermal and chemical stability which makes it convenient for enhancing the energy and mass transport properties of base fluids. Ethylene glycol, a common coolant in various industrial applications is utilized as the suspending medium due to its superior heat transfer properties. The effects of variable thermal conductivity, variable mass diffusivity, thermal radiation and thermophoresis which are crucial parameters in affecting the transport phenomena of nanofluids are taken into consideration. The governing partial differential equations representing the conservation of momentum, energy, and concentration are reduced to a set of nonlinear ordinary differential equations using appropriate similarity transformations. R software and MATLAB-bvp5c are used to compute the solutions. The impact of key parameters, including the nanoparticle volume fraction, magnetic field, Prandtl number, and thermophoresis parameter on the flow, heat and mass transfer rates is systematically examined. The study reveals that the presence of MoS₂ nanoparticles curbs the friction between the fluid and the solid boundary. Moreover, the variable thermal conductivity controls the rate of heat transfer and variable mass diffusivity regulates the rate of mass transfer. The numerical and statistical results computed are mutually justified via tables. The results obtained from this investigation provide valuable insights into the design and optimization of systems involving nanofluid-based heat and mass transfer processes, such as solar collectors, chemical reactors, and heat exchangers. Furthermore, the findings contribute to a deeper understanding of stretching sheet systems, such as in manufacturing processes involving continuous casting or polymer film production. The incorporation of MoS₂-C₂H₆O₂ nanofluids can potentially optimize temperature distribution and fluid dynamics.