• Journal of the Society of Cosmetic Scientists of Korea
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• v.42 no.1
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• pp.29-35
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• 2016

RS White (resorcinol bis-ethylhexanoate) is used in cosmetics as a skin whitening agent. In this study, we studied the possibility of nano-emulsion formation containing whitening agent, RS White, with different types of emulsifying agents. With Tween 80, 60, HCO 60 and 40 as a hydrophilic surfactants and Span 80 as ahydrophilic surfactant, nano-emulsions were formed at appropriate concentrations, but they were not formed in the system using the Myrj 52, Montanov L, and Tegocare 450 with Span 80. The diameter of nano-emulsion sphere was smaller than 100 nm. The emulsion showed a translucent appearance and maintained stability in stability evaluation with time. In vitro skin permeation experiments showed that amounts of skin permeated nano-emulsion for 24 h were $70.84{\mu}g/cm^2$ and those of O/W emulsion were $28.97{\mu}g/cm^2$. In conclusion, a stable nano-emulsion containing the resorcinol bis-ethylhexanoate is effective for potential efficacy system as an efficient delivery system of the functional materials into skin.

• Nuclear Engineering and Technology
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• v.24 no.1
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• pp.40-51
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• 1992

One of the important irradiation performance characteristics of the silicide dispersion fuel element in research reactors is the diameteral increase resulting from fuel swelling. This paper, will attempt to develop a physical model for the fuel swelling, DFSWELL, by analyzing the basic irradiation behaviours and some experimental evidences. From the experimental evidences, it was shown that the volume changes in irradiated U$_3$Si-Al were strongly dependent on temperature and fission rate. The quantitative-amount of swelling for silicide fuel is estimated by considering temperature, fission rate, solid fission product build-up and gas bubble behavior. The swelling for the silicide fuel is comprised of three major components : i ) a volume change due to the formation of an interfacial layer between the fuel particle and matrix. ii ) a volume change due to the accumulation of gas bubble nucleation iii ) a volume change due to the accumulation of solid fission products The DFSWELL model which takes into account the above three major physical components predicts well the absolute magnitude of silicide fuel swelling in accordance with the power histories in comparison with the experimental data.

• Korean Chemical Engineering Research
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• v.43 no.4
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• pp.482-486
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• 2005

The biodegradable poly(${\varepsilon}$-caprolactone)(PCL)/poly(ethylene imine)(PEI) microcapsules containing $Al_2O_3$ and fragrant oil were prepared with different PEI contents. The effects of stirring rate and concentration of the surfactant on the diameter and morphologies of microcapsules were investigated by using scanning electron microscope (SEM). Thermal behaviors were studied by using a differential scanning calorimetry(DSC), and the release behaviors of fragrant oil from microcapsule were characterized by UV/vis. spectrophotometer. As a result, the average particle size of the microcapsules decreased with increasing the stirring rate or concentration of the surfactant. The surface morphologies of the microcapsules were changed from smooth surfaces to skin-like rough surfaces as increasing the PEI content. These results were mainly due to the increased hydrophilic groups at the microcapsule surfaces, resulting in increasing the release rate of fragrant oil in the microcapsules studied.

• Journal of ILASS-Korea
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• v.3 no.3
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• pp.33-41
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• 1998

In recently, a study on the lean combustion is investigated intensively, because it is expected that this method may decrease the harmful exhaust gas and improve fuel economy in gasoline engine. The problems of lean combustion system in gasoline engine are ignition difficulty, misfire and instability of combustion. The investigation on the optimization of fuel metering and the control of mixing gas flow may be critical to improve the performance of lean combustion. In the fuel injection gasoline engine, the formation of mixture influences strongly on the engine performance such that the importance of fuel metering system becomes apparent. First of all, a study on the fuel breakup characteristics of gasoline fuel injector was carried out in this paper. Fuel injectors are pintle and 4hole-2spray type. The purpose of this study is to clarify the atomization mechanism of spray injected into atomosphere field through electronic controlled-fuel injectors, and to analyze spray characteristics such as drop size distribution and mean drop diameter produced at fuel injector. In this paper, the spray development is observed by taking photograps using 80mm still-camera system, and drop sizes are measured by PMAS. From these experiment, spray pattern injected from gasoline fuel injectors was investigated clearly. Also, it was found that SMD and drop size distribution of injected fuel spray from gasoline fuel injectors.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.571-580
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• 2018

In this study, hybrid adsorbents (SS) were prepared by mixing spent coffee grounds (SCG) and sericite, a kind of clay minerals, to adsorb Pb(II) from an aqueous solution. In FT-IR analyses, the main functional groups of SS adsorbents were O-H, C=O and C-N groups. The specific surface area, cation exchange capacity and the pore diameter of SS were larger than those of using SCG and sericite. Formation conditions of the SS adsorbent were the optimum pyrolysis temperature of $300^{\circ}C$, SCG : sericite ratio of 8 : 2, and particle size of 0.3 mm. Langmuir adsorption isotherm was more suitable than Freundlich one, and the maximum adsorption capacity was reached 44.42 mg/g. As a result of the adsorption thermodynamic analysis, the adsorption of Pb(II) onto SS was the physical adsorption and exothermic process in nature. The regeneration of SS adsorbent using distilled water showed 88~92% recovery and the active site of SS adsorbent decreased with increasing the reuse cycle time. As a result, SS adsorbent showed that it can be used to remove Pb(II) easily, inexpensively and efficiently without any pre-treatment from aqueous solutions.

• Korean Chemical Engineering Research
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• v.45 no.5
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• pp.442-447
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• 2007

In order to improve the surface hardness of transparent plastic films, organic-inorganic hybrid coating solutions were synthesized by the sol-gel method. The coating solutions were prepared by adding GPTMS (glycidoxypropyl trimethoxysilane) to a colloidal silica (12 nm) suspension. PC(polycarbonate) substrates were dipped into the coating solutions and dried at room temperature for 10 min before being cured at $80^{\circ}C$ for 30 min. The effect of the solution pH and GPTMS content was investigated on the properties of coating films. The pencil hardness and adhesion to substrates of the coating films, prepared at acidic condition (pH 4), showed better properties than those at neutral or basic conditions. Also, the pencil hardness and adhesion to substrates of the coating films increased with increasing GPTMS content.

• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.80-80
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• 1998

RU02 박막은 전이금속으로서 rutile 구조이며, 넓은 온도 영역에서 금속성의 를 나타내고, 700도 이상의 높은 온도에서 열적 안정성을 갖는 물질이다 이러한 특성 때문 에 RU02 박막은 실리콘 디바이스에서 배선 게이트 전극 확산 장벽 등에 응용가능성이 높 은 물질로 각광을 받고 있다- 특히 다결정 RU02 박막은 DRAM (dynamic random access m memory) 내의 강유전성 축전기의 전극으로서 유망한 물질이다. 지금까지 이러한 응용분야에 사용된 전극물질은 pt 금속이었다 그러나 이러한 금속전극은 SI 산소 그리고 강유전체의 구성물질 등과의 상호확산, pt 표면의 hillock의 존재로 생기는 전기적 단락, 기판과의 나쁜 점작성, 어려운 에칭 프로세스 등의 단점을 가지고 있다 더욱 더 심각한 문제는 P Pt'ferroelectric/Pt 구조에서 나타나는 aging과 fatigue인데, 이는 108 사이쿨 이후에 스위칭 가 능한 잔류 pOlarization 으$\mid$ 감소를 유발하게 된다- 최근 Berstein은 Pt 대신에 RU02를 사용함으로써 강유전체 축전기에서의 fatigue 현상을 크게 감소시켰다고 보고 한 바 있다 Burst川도 RU02 가 실리콘 표면과 유전체 물질 사이에 전기전도 어떠한 상호 확산도 일어나지 않음을 보였다. 그러나 이러한 연구 결과에도 증착조건과 RU02 박악의 특성에 관한 상호 관계가 충분히 더욱 더 중은 강유전성 박막올 만들기 위해서는 이러한 박막 전극에 않고 있다 연구되지 대한 상세한 연구가 반드시 필요하다고 본다. RU02 박막은 실리콘 기판 위에 고주파 마그네트론 스퍼터링 방법으로 증착하였다. 사용 한 타켓은 2 인치의 직경을 가지는 CERAC 사에서 제작한 Ruol다 초기 진공은 1O~6 Torr 이하였고, 고주파 전력은 20 - 80W 까지 변화시켰다 반응성 스퍼터링율 하기 위해 아르곤과 산소롤 주입하였고, 산소/(산소+아르곤)의 비를 변화시켰다 기판의 온도와 증착압력은 각각 상온에 서 500도까지 , 5mTorr에 서 100mTorr 까지 변 화시 켰 다 RU02 박막의 결정성을 조사하기 위해 XRD 표면 형상과 단면을 조사하기 위해 SEM을 사용하였다‘ 박악의 비저항을 조사하기 위해 4-단자법 van der Pauw 방법을 사용하였다. RU02 박막은 증착압력이 높을수록 비저항은 높아지고, 두께는 감소하였다. 특히 1 100mTorr에서는 작업가스와 스퍼터된 입자사이의 심각한 산란 때문에 아예 증착이 이루어 지지 않았다‘ RF 전력이 증가할수록 비저항이 낮아졌다. 이는 두께에 의존하는 결과이며 전형적인 금속박막에서 나타나는 현상과 유사함을 알 수 있었다- 기판온도와 작업가스의 산소 분압이 높을수록 비저항이 감소하였다‘ 이러한 사실은 성장한 박악의 결정구조와 밀접한 관련이 있음을 보여준다.

• Applied Chemistry for Engineering
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• v.18 no.4
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• pp.386-390
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• 2007

In this study, polyurethane prepolymers were synthesized from polycaprolactonediol (PCDs. M.W. 530, 830, 1000, 1250, and 2000) and polycaprolactonetriol (PCTs. M.W. 300 and 900), and hexamethylenediisocyanate (HMDI). Polyurethane beads was prepared from the different prepolymers by a two-step suspension polymerization. The particle size of polyurethane beads was investigated by particle size analyzer. The beads were $10{\sim}30{\mu}m$ in size. The structure of beads was confirmed by FT-IR spectrometer. Their thermal properties were analyzed by TGA. Glass transition temperatures ($T_g$) of the beads were in the range of $-23{\sim}-53^{\circ}C$ and decreased with the increase of the PCD molecular weight. In order to prevention the cohesion of beads, the beads were coated with tetraethoxysilane (TEOS).

• Journal of Sericultural and Entomological Science
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• v.13 no.1
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• pp.35-47
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• 1971

Current overseas research reveals that among the pathogens causing flacherie of silkworm, damage by infectious flacherie virus is the most serious, but little research in this fold has been reported in Korea. This experiment was undertaken to observe the occurrence of infectious flacherie virus by means of biological environmental conditions associated with occurrence of virus discase and interaction of the virus of flacherie and Bacillus spp. isolated from flacherie silkworm, and to determine ways to check infection by the virus during the rearing of silkworms. The results obtained are as follows: 1. The pathogen, infectious flacherie virus observed in Korea, is proved to be round in shape and 26-30m$\mu$ in diameter under observation with electron microscope, 2. The infectious flacherie virus-disease occurred apparently in conditions of nutritional disturbance such as shortage of diet or rearing in high temperature and humidity during the 3-4th instar. 3. The percentage of disease-occurrence was increased remarkably, and the latent period was shortened in the case of simple inoculation of virus suspension as compared with the suspension added with bacteria. 4. The application of calcium hydroxide in the silkworm-rearing bed is able to check infection of virus disease.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.232-232
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• 2011

DAF는 기존 침전 공정에 비해 뛰어난 정수 품질과 빠른 처리 시간으로 차세대 정수 공정으로 각광 받고 있다. DAF는 기포 생성 방법에 따라 용존 공기 부상법, 분산 공기 부상법, 진공 부상법, 전해 부상법, 미생물학적 부상법 등이 있다. 이 중 가장 많이 쓰이는 방식은 용존 공기 부상법으로, 과포화 상태의 기체와 액체의 혼합액을 압력을 급격히 감소시켜 기포를 발생 시키는 방법이다. 이 방법은 기포의 발생은 많지만 장비의 크기가 거대하고 시설제조 비용이 많이 드는 단점이 있다. 수중에서 발생되는 플라즈마는 그 구조와 메카니즘에 따라 생성되는 버블의 양을 제어할 수 있음을 확인하였다. 모세관 형태의 전극을 이용한 수중 방전은 전원 공급 장치만 있다면 적은 공간으로도 효과적으로 기포를 생성 할 수 있기 때문에, 수중 방전을 이용하여 기포 발생 후 DAF에 적용 가능한지 알아보고자 한다. DAF공정에서 필요한 요인으로는 기포의 크기, 개수, 성분 물질 등이 있는데, 그 중 가장 핵심은 기포의 크기 이다. 그래서 간단한 전원 장치와 리액터 제작 후 방전에 최적화 된 전극으로 기포를 발생시켜 기포의 크기를 측정하였다. 기포의 크기는 전극의 직경과 방전공간의 비율에 따라 제어가 가능함을 확인하였고 평균 기포의 크기는 약 50 ${\mu}m$로서, DAF에 적용 할 수 있는 크기이다. 일반적으로 기포의 사이즈가 작을수록 입자 제거율이 높은데, 실제 DAF공정에서 사용되는 기포의 사이즈는 80 ${\mu}m$정도 이다. 따라서 개발된 기포 발생장치를 DAF 공정에 응용한다면 높은 효율을 가질 것으로 판단된다.