• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.3
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• pp.209-215
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• 2008

Iodopropynyl butylcarbamate and climbazole as anti-dandruff agents widely used in cosmetics and pharmaceutics were micronized using supercritical fluid. Supercritical carbon dioxide was selected due to relatively low critical temperature and critical pressure. Iodopropynyl butylcarbamate and climbazole were chosen because of their solubility in supercritical carbon dioxide. The rapid expansion of supercritical solution (RESS) experiments involved investigations of the effect of pressure, temperature on particle size and morphology.

• Journal of the Korean Geotechnical Society
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• v.39 no.11
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• pp.33-40
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• 2023

This study explores the performance of pile foundations in highly expansive soil, incorporating magnesium oxide-based refractory materials. A controlled model chamber, housing a fixed pile, was utilized to induce ground expansion through fused magnesia (FM). The investigation focused on measuring the vertical displacement of FM-sand mixtures and the axial load on the pile in relation to depth and time. The study varied the amount of FM content (FM_c) at 30%, 50%, and 70%. The upward movement exhibited an augmentation with increasing FM_c, tapering off with depth as accumulation progressed toward the mixture surface. Compression and tensile forces were both evident along the pile for FM_c at 30% and 50%, while only a tensile force was observed at an FM_c of 70%. These results offer valuable insights for the analysis of pile behavior within FM-sand mixtures.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.5
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• pp.434-442
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• 2006

In a two-stage compression $CO_2$ transcritical cycle, application of a scroll expander-compressor unit has been considered in order to improve the cycle COP. For both expander and 1st stage compressor, scroll wrap profile which was originally designed for a R410A air-conditioning cycle mechanism was used with minor modifications: wrap height and involute end angle were adjusted for required displacement volume and built-in volume ratio. For pressure condition of 10 Mpa/3.5 MPa and expander inlet temperature of $35^{\circ}C$, 25% improvement in COP was obtained by using expander-compressor unit. As evaporator pressure increased, COP improvement was lowered mainly due to decreasing compressor peformance.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.11a
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• pp.32.1-32.1
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• 2009

본 연구에서는 산화 그라핀을 환원하여 얻은 그라핀 분말의 고온 XRD 패턴를 통해 그라핀의 열팽창계수를 정량하였다. 산화 그라핀은 Hummer method에 의해 제조되었다. 또한 그라핀은 산화그라핀을 1273K에서 열처리하여 얻어졌다. 1273K에서 그라핀의 열팽창계수($32.9{\pm}1.0$ X 10-6 K-1)는 원료인 흑연(30.3 X 10-6 K-1) 보다 8.6% 더 크게 나타내는것을 알 수 있었다. 그라핀은 화학적 처리에 의한 급격한 면간 팽창과 열처리에 의한 aggregation에 의해 심하게 굴곡지고 적층된 morphology를나타냈다. 이는 박리효과에 의한 것으로 XRD 패턴을 통해그라핀의 층수가 흑연보다 훨씬 적은 것을 알 수 있었다. 이에 따라 면간 규칙적인 배열을 보이는 흑연과는 달리 그라핀은 흑연구조에서 흔히 보이는 disorder 구조인turbostratic 적층 구조를 나타나고 면간인터렉션이 약화되어 열팽창계수가 크게 나타난다고 생각된다.

• Journal of the Korean Ceramic Society
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• v.35 no.2
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• pp.151-162
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• 1998

ZnO-BaO-$SiO_2-Al_2O_3$계 유리 및 결정화 유리 시편들을 제조하여 평판형 고체산화물 연료전지 봉착재로의 이용가능성을 조사하였다 구성층과 일치되는 열팽창 계수 및 화학적 안정성을 봉착재로의 적용에 있어 판단 기준으로 정하였다 실험된 다양한 조성의 유리 및 결정화 유리 시편들중 7.79ZnO-58.52BaO-$28.69SiO_2-5Al_2O_3$(ZBS3-A5) 결정화 유리의 측정된 열팽창 계수값은 $11.02\times10^{-6/^{\circ}C}$로써 YSZ 및 LSC의 평균 열팽창 계수 값과의 차이가 $0.07\timestimes10^{-6/^{\circ}C}$로 매우 작아 봉착시 열응력 발생의 최소화를 기대할수 있었다 이런 ZBS3-A5+LSC 접합 couple의 경우는 ZnCr2O4 의 dis-crete한 입자가 결정화 유리 부위에 형성되었고 역시 시간의 증가에 따라 이러한 입자의 성장은 없었다 특히 ZBS3-A5 구성 성분인 Ba, Zn, Sil 그리고 Al의 YSZ 및 LSC로의 확산은 없어 봉착후에 YSZ 및 LSC의 전기적 특성에 악영향을 미치지 않으리라 판단되었다.

• Journal of the Korean Professional Engineers Association
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• v.30 no.3
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• pp.104-114
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• 1997

Throughout the practical process engineering design and commissioning 8E startup experiences focused on chemical process safety, the review of design and installation of the thermal relief valve with its surrounding facility in a chemical plant piping system is made to help the better understanding of the piping system of characteristics of thermal relief valve which Is consisting of theoretical approach, correlation in terms of temperature and pressure increase caused by external heat supply in a piping system, consideration of thermal relief valve design, pressure relieving system of serial thermal relief valves and exception of their installation. It is earnestly recommended that following topic should be implemented during thermal relief valve design, installation and normal operation as well.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.1
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• pp.84-90
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• 2004

In order to evaluate the performance of carbon dioxide cycle, a simulation model was developed to predict the steady state performance of $CO_2$ transcritical cycle. The expansion process is treated as an isenthalpic throttling process or isentropic expansion process. The mathematical model is based entirely on the basic energy conservation law and thermodynamic and transport properties of $CO_2$. A Parametric study has been conducted in order to investigate the effect of isentropic efficiency of expansion turbine and various operating conditions on the cycle performance. An optimal heat rejection pressure existed for the given evaporating temperature and outlet temperature of gas cooler.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.1-5
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• 2009

A dilatometer was used to investigate the effect of cure conditions, mold types and the presence of filler in an epoxy system. These studies showed shrinkage in the cured epoxy when heating it through the glass transition temperature region. The magnitude of the shrinkage, related to stress build up in the epoxy during curing, was influenced by the processing conditions, filler presence and the nature of the mold used to contain the resin. Cure and cyclic cure at a lower temperature, prior to a post cure, decreased the magnitude of observed shrinkage. Cure shrinkage decreased with the number of cyclic cures. Post cured samples outside the mold led to less shrinkage compared with samples in the mold. Sample cured in a silicon mold represented less shrinkage than sample cured in an aluminum mold. Sample containing kaolin filler showed less shrinkage than unfilled sample.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1999.11a
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• pp.181-186
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• 1999

화학 축열 시스템의 성능을 모사하고 이를 해석하여 시스템 성능을 최적화하기 위해서는, 반응층의 열 및 물질 전달 특성을 정확히 아는 것이 중요하다. 본 연구에서는 $Na_2$S-$H_2O$ 반응계를 사용한 화학 열펌프에 대한 연구로, $Na_2$S-팽창흑연 복합체의 열전도도와 기체 투과도를 측정하였고, 소형 시스템을 제작하여 그 성능을 평가하였다. 열전도도는 전이 일차원 열류기법을 사용하여 측정하였고, 기체 투과도는 Darcy's law를 이용하여 측정하였다. 반응층의 열전도도와 기체 투과도는 팽창흑연 지지체의 겉보기 밀도와 반응염의 함량에 따라 각각 6~48W/mㆍK, 1.1$\times$$10^{-13}$~1.0$\times$$10^{-11}$m$^2$의 범위에 있었다. 또한 소형 시스템을 구성하여 445W/kgㆍ$Na_2$S의 냉방 출력을 얻을 수 있었다.

• Journal of the Korean Institute of Gas
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• v.19 no.5
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• pp.98-103
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• 2015

Liquefied petroleum gas can be charged up to 85% of cylinder volume by enforcement regulations of safety control and business of liquefied petroleum gas act. The charged mass by enforcement regulations is considered by liquid expansion of internal liquefied petroleum gas at $65^{\circ}C$. But the temperature of liquid would not be suspended under $65^{\circ}C$ in a cylinder or portable vessel at certain situation. In the thermodynamics view point, the cylinder can be exposed to high pressure by liquid expansion. Consequently, it can be possible to potential risk such as physical explosion. Hence, this paper will offer a method of estimated internal pressure by liquid expansion at critical state in the closed system. Also, the structural factor which is given rise to volume increasement of cylinder is offered by experiment. This paper is expected as crucial reference for a cylinder design of liquefied petroleum gas.