• Journal of Pharmaceutical Investigation
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• 제21권2호
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• pp.97-101
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• 1991

Six different O/W cream bases containing 4% ascorbic acid dipalmitate and two different O/W cream bases containing 1% ascorbic acid were prepared. Percutanceous absorption of ascorbic acid as well as safety were determined using rabbits. The stability of the creams was also tested at room temperature. Ascorbic acid concentrations in urines varied depending on the characteristics of cream bases used. The absorption of ascorbic acid was increased and sustained with the cream bases containing branched chain esters of fatty acid instead of natural oils used currently. The excretion level of ascorbic acid in urine was high with the cream base including nonionic surfactants and a small quantity of natural oils. The creams containing nonionic surfactants showed excellent stability, while those containing anionic surfactants were not stable in terms of pH, odor and coloring test at room temperature during six months. But, the two creams containing ascorbic acid were unstable. All the cream bases tested showed good safety.

• 센서학회지
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• 제24권5호
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• pp.287-290
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• 2015

Liquid crystal polymer (LCP) is a thermoplastic polymer with superior mechanical and thermal properties. In addition, its characteristics include very low water absorption rate and possibility to apply bonding process under low temperature. In this study, LCP is utilized as a packaging material for a microelectronic system (MEMS) based safety device with suggestion of a low temperature packaging process. Highly sensitive and stable capacitive type humidity sensor is fabricated to investigate hermeticity of the packaged MEMS device.

• 한국염색가공학회지
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• 제16권5호
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• pp.35-41
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• 2004

Poly(ethylene terephthalate), polyimide(Kapton), and polypropylene surfaces were modified with argon low temperature plasma by RF glow discharge at 240m Torr, 40W to investigate the surface morphological changes due to the plasma treatment using atomic force microscopy(AFM). Analysis of the AFM images and Ra(average roughness) revealed that the plasma treatment resulted in significant ablation on the surfaces. The morphological changes and surface roughness, however, were different depending on material characteristics such as heat stability, presence of amorphous region, swelling phenomenon, and molecular structure of repeating unit. It was assumed that polypropylene due to its tertiary hydrogen was ablated easily compared to poly(ethylene terephthalate), and that polyimide was more resistant to the ablation than PET due to rigid skeleton of imide and stable phenyl ring structure.

• 한국전기전자재료학회논문지
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• 제25권11호
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• pp.926-929
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• 2012

The $Sr_{0.7}Bi-{2.3}Nb_2O_9$(SBNO) thin films were deposited on Si substrate by RF magnetron sputtering method at $300^{\circ}C$ of substrate temperature. And the SBNO thin films were annealed at $650{\sim}800^{\circ}C$ using RTA (rapid thermal annealing). The grain of SBNO thin films were increased with the increase of annealing temperature. The dielectric constant (100) of SBNO thin film was obtained by RTA above $750^{\circ}C$. The voltage dependence of dielectric loss showed a value within 0.03 in voltage ranges of -5~+5 V. Also, the dielectric constant characteristics showed a stable value with the increase of frequency.

• Nuclear Engineering and Technology
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• 제51권5호
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• pp.1272-1278
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• 2019

A lumped kinetic modeling platform is developed to investigate the coupled nuclear/thermo-fluid features of the closed natural circulation loop in a low power lead cooled fast reactor. This coolant material serves a reliable choice with noticeable thermo-physical safety characteristics in terms of natural convection. Boussienesq approximation is resorted to appropriately reduce the governing partial differential equations (PDEs) for the fluid flow into a set of ordinary differential equations (ODEs). As a main contributing step, the coolant circulation speed is accordingly correlated to the loop operational power and temperature levels. Further temporal analysis and control synthesis activities may thus be carried out within a more consistent state space framework. Nyquist stability criterion is thereafter employed to carry out a sensitivity analysis for the system stability at various power and heat sink temperature levels and results confirm a widely stable natural circulation loop.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2002년도 proceedings of the second asia international conference on tribology
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• pp.113-114
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• 2002

Radial, tilting 12-pad proceeding bearings are applied as the radial bearings of vertical rotors of water turbines. The mean loads are stable at the peripheral speeds of proceeding reaching 50 m/s. The operation of tilting 12-pads proceeding bearing has been introduced at the assumption of adiabatic oil film. The oil film pressure, temperature and viscosity distributions have been obtained by iterative solution of the Reynolds', energy and viscosity equations. The resulting oil film force, minimum oil film thickness, power loss, oil flow, maximum oil film pressure, maximum temperature have been computed for different load angle of bearing.

• 에너지공학
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• 제8권2호
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• pp.298-308
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• 1999

과냉각수조로 분사되는 증기의 직접접촉 응축특성을 알아보기 위하여 다섯 개의 수평 노즐에 대해 증기 질량유량과 수조 온도를 여러 가지로 변화시키면서 실험적 연구를 수행하였다. 증기응축현상을 육안관찰과 고속 비디오 카메라를 사용한 방법으로 분석한 결과, 안정된 증기제트인 경우 증기 질량속과 수조온도가 변화함에 따라 타원형 및 원추형 증기제트 형상이 나타나는 것을 관찰하였다. 증기제트 팽창비, 증기제트 길이 및 응축연전달계수를 구하였고, 증기 질량속, 수조온도 및 노즐 내경이 미치는 영향을 분석하였다. 증기제트 길이와 응축열전달계수를 증기 질량속 및 응축추진 포텐셜의 함수로 나타낸 상관식을 구하였다. 증기제트 내부와 주위 수조온도 분포를 구했으며 증기 질량속, 수조온도 및 노즐 내경이 미치는 영향을 분석하였다. 처깅, 천이처깅, 응축진동, 안정응축, 방울응축진동 및 간헐진동응축 등 여섯 가지 영역으로 구분된 응축 영역도를 작성하였다. 그 외, 수조 벽면에서의 동압을 측정하였고, 증기 질량속과 수조온도에 따라 변화하는 증기 응축모드와 동압과는 밀접한 연관성이 있음을 확인하였다.

• 한국표면공학회지
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• 제34권5호
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• pp.481-485
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• 2001

We investigated the structural and electrical properties of the Ba ($Zr_{x}$ $T_{il-x}$ )$O_3$ (BZT thin films with a mole fraction of x=0.2 and thickness 150 nm for the application in MLCC (Multilayer Ceramic Capacitor). BZT films were prepared on $Pt/SiO_2$/Si substrate at various substrate temperatures by the RF-magnetron sputtering system. When the substrate temperature was above $500^{\circ}C$, we could obtain multi-crystalline BZT films oriented at (110), (111), and (200) directions. The crystallization of the film and high dielectric constant were observed with the increase of substrate temperature. Capacitance of the film deposited at high temperature is more sensitive to the applied voltage than that of the film deposited at low temperature. This paper reports surface morphology, dielectric constant, dissipation factor, and C-V characteristics for BZT films deposited at three different temperatures. The BZT film deposited at 40$0^{\circ}C$ shows stable electrical properties but a little small dielectric constant for MLCC application.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제51권11호
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• pp.526-530
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• 2002

The $(Sr_{0.9}Ca_{0.1})TiO_3(SCT)$ thin films were deposited on Pt-coated electrode (Pt/TiN/$SiO_2$/Si) using RF sputtering method. The composition of SCT thin film deposited on Si substrate at room temperature is close to stoichiometry(1.081 in A/B ratio). The maximum dielectric constant of SCT thin film was obtained by ammealing at $600^{\cric}C$. The temperature dependence of dielectric loss showed a value within 0.02 in temperature ranges of -80 ${\sim}$ +90$^{\circ}C$. The capacitance characteristics showed a stable value within ${\pm}$4%. The drastic decrease of dielectric constant and increase of dielectric loss in SCT thin films was observed at the frequency above 200kHz.

• 한국초전도ㆍ저온공학회논문지
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• 제17권4호
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• pp.25-29
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• 2015

In 1987, M. K. Wu and Paul Chu discovered $Y_{1.2}Ba_{0.8}CuO_4$ (YBCO) with critical temperature ($T_c$) of 93 K. It has significantly lowered the cost of cooling of a material up to the point where superconductivity set in. Utilizing the cost reduction of attaining superconductivity and the vast amount of research to understand characteristics of high temperature oxide superconducting materials, there has been effort to use a high temperature superconductor as a coated conductor. It is important to characterize the materials precisely for stable performance before commercializing. We used polarized Raman scattering spectroscopy to study structural and stoichiometric information regarding $YBa_2Cu_3O_{7-x}$, $GdYBa_2Cu_3O_{7-x}$, and $GdBa_2Cu_3O_{7-x}$ produced by three leading groups of producing commercial grade high temperature superconductor coated conductors American Superconductor Corporation, Superpower, and SuNAM.