• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.184-190
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• 2011

The membrane properties (membrane resistance and ion exchange capacity) of the five types of commercial anion exchange membrane, i.e. IOMAC, AHT, APS, AHA, AFN, were evaluated for the application in the alkaline electrolysis. The membrane resistance decreased in the order; in 1M KOH: AHT>IOMAC>AHA>AFN>APS; in 1M NaOH: AHT>IOMAC>AHA>APS>AFN. The ion exchange capacity decreased in the order: AFN>APS>AHT>AHA>IOMAC. The membrane life was determined from the change of membrane resistance in 1M KOH and NaOH with an increase of soaking time in 20 wt% KOH and 30 wt% NaOH solution. AHA membrane had a good membrane life in 20 wt% NaOH with its unchanged membrane resistance. And, AFN and AHA membrane had a good membrane life in 30 wt% NaOH with its unchanged membrane resistance.

• 한국세라믹학회지
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• 제34권4호
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• pp.343-350
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• 1997

To fabricate the ceramic/metal(SiC/ Al alloy) composite, SiC preform was prepared by Pressureless Powder Packing Forming Method and 6061 Al alloy was infiltrated into the preform. Uniform compact having an average pore size of 10 ${\mu}{\textrm}{m}$ and narrow pore size distribution was prepared. Phenolic resin solution(40 wt%) was penetrated into the SiC compact, and then the compact was preheated at the temperature of 120$0^{\circ}C$. The pore size distribution and the microstructure of the preform were not changed by preheating. An uniform microstructure without any crack in the preform was obtained in SiC-Al alloy composite. The infiltration of 6061. Al alloy into the preform began at the temperature of 130$0^{\circ}C$ and the amount of infiltration increased in proportion to the infiltration temperature and the soaking time. The increasement rate of the infiltration amount decreased after 3 h. As a result of the infiltration at 140$0^{\circ}C$ for 4 h, Al alloy was well distributed in the interparticle channels and the relative density of the composite was above 98%. The strength and the fracture toughness of the composite were 303 MPa and 21.65 MPam1/2, respectively.

• 한국세라믹학회지
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• 제33권10호
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• pp.1177-1185
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• 1996

Y-TZP/Ce-TZP ceramics having relative sintered densities of>95% average grain sizes of 0.36$\mu\textrm{m}$ microhar-dness of 1150 kg/mm2 fracture strength of 390-830 MPa and toughness of 6.4-10.2 MPa$.$mm1/2 were prepared by conventional sintering of 3 mol% Y2O3-ZrO2 and 12 mol% CeO2-ZrO2 powders at 1400 and 1500$^{\circ}C$ The average grain sizes of Y-TZP/Ce-TZP ceramics were mainly governed by those of Ce-TZP. White increasing Ce-TZP content toughness increased while microhardness and fracture strength decreased. With comparing microhardness and toughness fracture strength was more sensitive on not only grain size but also other factors such as microstructural and compositional variations. The densification of Y-TZP/Ce-TZP cermaics was not greatly affected by composition and soaking time at temperature over 1400$^{\circ}C$ With increasing CE-TZP content the stability of t-ZrO2 decreased under thermal aging in air whereas increased in hydrothermal atmosphere and aqueous solution.

• 한국전기전자재료학회논문지
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• 제26권5호
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• pp.360-366
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• 2013

For conventional electrical actuators, the materials are mainly made up of metals, which mean they are prone to corrosion and electrical sparking. Replacing these systems with polymer metal composite based materials can be solved both problems. Considering their excellent electromechanical property, low device fabrication cost, light weight, and good electrical conductivity, the actuator based on ionic polymer metal composite (IPMC) was fabricated using Nafion film, NaOH 0.1 molar solution, and Au electrode. IPMCs exhibit good electrostatic property which means they can in principle be used in making actuators based on electromechanical motions. The resistance measurements of Nafion film after soaking in NaOH and deionized water were demonstrated and compared each other. The result of sample soaked in NaOH showed better electrical conductivity than in deionized water. The fabricated IPMC actuator exhibits a large deformation of bending displacement of approximately 9 mm with applied low AC voltage 6.89 V at 2.84 Hz. The result of computer simulation was also very similar and shown as a bending displacement of 8.6085 mm.

• 식물조직배양학회지
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• 제25권5호
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• pp.305-308
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• 1998

키위의 엽육조직과 엽병조직을 치상하여 캘러스 및 부정아형성에 미치는 생장조절제의 효과를 조사한 결과 기관분 화성 캘러스형성은 2,4-D와 kinetin을 조합한 배지에서보다 NAA와 BA를 조합한 배지에서 양호하였고, 부정아 형성은 NAA와 BA를 조합한 배지에서만 형성되었으며 엽병조직보다 엽육조직을 배양하였을 때 반응이 양호하였다. 유도된 캘러스와 부정아로부터 신초의 형성은 MS기본배지에 0.1mg/L NAA와 2.0mg/L zeatin을 첨가한 배지에 계대배양하였을 때가 가장 효과적이었다. 신초의 발근은 1.0 mg/L IBA용액에 1시간 신초를 침지한 후 0.5 mg/L IAA와 0.1mg/L BA를 첨가한 배지에 배양하면 IBA용액에 침지처리 하지 않은 것보다 더 효과적이었으며 정상식물체로 발달하였다.

• Journal of the Korean Wood Science and Technology
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• 제48권4호
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• pp.458-471
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• 2020

Effect of pre-treatment and compression ratio on specific gravity (SG) and dimensional stability improvement of three lesser-used wood species from natural forest area of North Kalimantan Province, Indonesia had been investigated. Hot soaking at 80℃ for 3 hours within 2 and 5% of boron solution was applied as pre-treatment, while compression ratio applied was 20 and 40% from the initial thickness. Densification was conducted using hot pressing machine at 30 kg/㎠ of pressure and 160℃ of temperature for 15 minutes. Specific gravity was measured gravimetrically, while dimensional stability was evaluated through thickness swelling and water absorption as the indicator. Results show that SG of densified wood was influenced by wood species and compression ratio, but not by pre-treatment applied; while dimensional stability was influenced by wood species, compression ratio, and pre-treatment. Specific gravity and water absorption of densified wood was improved significantly. Specific gravity increased 28.86-63.03%, while water absorption decreased 12.80-15.89%. Thickness swelling of 20% densified wood was lower than that of 40% densified wood.

• 동아시아식생활학회지
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• 제15권5
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• pp.613-618
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• 2005

This study was performed to analyze the microbiological properties of Oiji soaking solution and Oiji preserved with $7\%$ brine and the others preserved with Pulsatilla koreana additives of various concentration$(0,\;3,\;6,\;9\%)$ during fermentation(24 days) at room temperature$(20\pm2^{\circ}C)$. The results of this experiment are as follows: The total number of microbes showed radical increase up to 6th day of growth period and decreased afterwards. Growth of microbes was impeded in the beginning of fermentation in the case of adding $6\%$ Pulsatilla koreana. The number of lactic acid bacteria tended to increase progressively until 15th day and then decreased, and that in the group of $6\%$ Pulsatilla koreana was relatively lower than those of other groups. Antimicrobial activity against Staphylococcus aereus and Micrococcus luteus was shown weakly from 9th day of fermentation regardless of the concentration of Pulsatilla koreana additives, but inactivated after 21st day of fermentation.

• 한국식품과학회지
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• 제29권3호
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• pp.576-580
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• 1997

배추를 절이는 과정에서 배추 lipoxygenase의 활성변화는 linoleic acid를 기질로 하여 용존산소 소비량의 변화로 효소활성을 측정하였다. 소금물에 배추를 침지한 경우 소금의 농도가 증가할수록, 절임시간이 길어질수록 효소의 실활 정도가 큰 것으로 나타났다. 13%의 소금물에서 5시간 절인 후 약 60%의 효소활성이 감소하였다. 한편 calcium chloride의 영향을 살펴보기 위하여 절임시 0.7% calcium chloride를 첨가한 결과 calcium chloride를 첨가한 것이 calcium chloride를 첨가하지 않은 것 보다 효소의 실활정도가 $10{\sim}15%$ 적은 것으로 나타났다. 효소 저해제로 마늘 추출물을 사용한 결과 생배추에 첨가한 경우는 약 40%, 13%의 소금물에 절인 후의 배추의 경우는 약 20%의 잔존활성을 보여 주었다.

• Journal of Pharmaceutical Investigation
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• 제34권4호
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• pp.275-281
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• 2004

We have studied the effect of polarity, current density, current duration, crosslinking density, swelling ratio, and permeation enhancers on the transdermal flux of ketoprofen from acrylamide hydrogel. Hydrogel was prepared by free radical crosslinking polymerization of acrylamide. Drug loading was made just before transport experiment by soaking the hydrogel in solution containing drug. In vitro flux study using hairless mouse skin was performed at $36.5^{\circ}C$ using side-by-side diffusion cell, and the drug was analysed using HPLC/UV system. The result showed that, compared to passive flux, the total amount of drug transported increased about 18 folds by the application of $0.4\;mA/cm^2$ cathodal current. Anodal delivery with same current density also increased the total amount of drug transported about 13 folds. It seemed that the increase in flux was due to the electrorepulsion and the increase in passive permeability of the skin by the current application. Flux increased as current density, the duration of current application and loading amount (swelling duration) increased. As the cross linking density of the hydrogel increased, flux clearly decreased. The effect of hydrophilic enhancers (urea, N-methyl pyrrolidone, Tween 20) and some hydrophobic enhancers (propylene glycol monolaurate and isopropyl myristate) was minimal. However, about 3 folds increase in flux was observed when 5% oleic acid was used. Overall, these results provide some useful information on the design of an optimized iontophoretic delivery system of ketoprofen.

• Applied Biological Chemistry
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• 제35권5호
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• pp.399-403
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• 1992

무의 염절임 과정에서 일어나는 염의 침투와 관련하여 무의 응력완화 변화를 측정하고 점탄성의 변화를 제시하였다. 침지 염용액의 농도와 침지온도가 증가할수록 염의 확산은 더 잘 일어났으나 염용액의 온도에 따른 염의 침투 정도는 낮은 염용액의 농도에 의해서 더 많은 영향을 미쳤다. 염장하지 않은 무의 높은 조직의 강도와 점탄성은 염용액의 온도를 증가시킴에 따라 초기 응력에 대한 조직의 강도약화를 보여 주었으며 응력완화의 정도도 빨라졌고 평형상태에서 잔여응력 양도 감소하였다. 또한 염용액의 농도가 증가할수록 무 조직의 응력완화정도와 잔존응력양의 변화가 거의 일치함을 보였다. 염용액의 온도와 농도를 증가시킴에 따라 염절인 무조직의 점탄성 성분들도 낮아졌는데, 온도에 따른 무의 점탄성의 낮아지는 정도는 염침투나 초기응력과 마찬가지로 낮은 염용액의 농도에서 더 많은 영향을 받았다.