• Journal of Hydrogen and New Energy
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• v.19 no.2
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• pp.132-138
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• 2008

금속산화물의 열화학싸이클에 의한 수소생산 소재중 안정성이 우수하고 물분해 수소생산능이 비교적 우수한 $NiFe_2O_4$를 합성하여 열화학수소생산공정 적용시 최적화의 조건에 대하여 검토하였다. 합성한 $NiFe_2O_4$는 격자상수가 $8.34\;{\AA}$이었고, 뫼스바우어에 의해 구조는 Ni이 페라이트 구조인 $AB_2O$의 B위치에 주로 위치하는, A 및 B의 상대적 흡수강도가 57.9:42.1인 역스피넬구조를 보이고 있다. 이러한 구조의 $NiFe_2O_4$의 열적환원은 $610^{\circ}C$부터 시작하여 $1200^{\circ}C$에 이르는 동안 약 1.1 wt%의 무게감소가 관찰된다. 물에 의한 산화과정에서 수소가 발생하게 되는데, $1200^{\circ}C$이하의 환원온도에서 가능한 수소생산량은 약 $0.45\;cm^3/g{\codt}cycle$ 이었다. 산화 환원의 반복과정에서 $NiFe_2O_4$의 XRD에 의한 구조변화는 관찰되지 않아 매우 안정한 구조를 갖는다는 것을 보여주었다. 수소생산을 위한 무게당 싸이클당 수소생산양은 산화 환원과정의 온도범위가 가장 중요하였고 물의 접촉시간은 중요한 요소가 되지 않았다. 열적 환원과정에서 많은 양의 수소생산성능을 보이기 위해서는 $1200^{\circ}C$이상의 고온을 필요로 하는 것을 보여주었다.

• Korean journal of food and cookery science
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• v.27 no.6
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• pp.793-801
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• 2011

We examined the quality characteristics of obtaining the optimal curing conditions for black garlic extract (BGE) added mackerel by using response surface methodology (RSM). The condition of RSM was included in 13 experimental points using two dependent variables: concentration of BGE (2.6~12.5 brix, X1) and curing time of BGE (17.58~102.42 min, X2). An assessment was conducted with four replicates on three independent variables: volatile basic amine (VBN, Y1), thiobarbituric acid (TBA, Y2), and shear force (Y3). The minimum content of VBN was 1.625 mg% at 3.17 brix, for 80.5 min. This was obtained when the BGE concentration was lower and the curing time was longer. The content of the TBA was 3.13~12.24 MA mg/kg at experiment range and the stationary point was at saddle point. Therefore, by using ridge analysis, the minimum point of TBA was 2.414 MA mg/kg at 3.5 brix for 84.4 min. The truth coefficient of the BGE concentration and curing time were 2.9 brix and 75.1 min, respectively, with a shear force ($120.764cm/kg^2$) shown at maximum point. The optimum Hunter color range was estimated from the lowest TBA value. The optimum range of the L color was 39.16~40.26, a and b color were 4.40~4.88 and 12.35~13.20, respectively.

• Journal of the Korean Chemical Society
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• v.51 no.2
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• pp.147-153
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• 2007

A simple, selective and highly sensitive flow injection catalytic method was presented for determination of ruthenium based on its catalytic effect on the oxidation of pyronin B by periodate in pH=1.0. The reaction rate is controlled specrophotometricaly by monitoring the dye absorbance at 555 nm. The optimized conditions make it possible to determine ruthenium in the ranges of 0.1-10.0 ng/mL (r2=0.9982) and 10.0-50.0 ng/mL (r2=0.9934) with a detection limit of 0.04 ng/mL and a sample rate of 30±5 samples/h. Relative standard deviation for the results of five replicate measurements does not exceed 1.44%. The proposed method has been successfully applied for quantitation of ultra trace amounts of ruthenium in some environmental and biological samples.

• Applied Chemistry for Engineering
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• v.28 no.4
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• pp.437-441
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• 2017

This study was carried out to investigate the volumetric expansion ratio and hardness of expanded graphite after coating with various resins which were used as an additive of fireproof sealant. The coating thickness of the resin, which represents the coating rate, was dependent of the drying speed of the resin and the viscosity of the resin. Therefore the coating thickness was shown as follows: polyvinyl acetate > acrylic resin > urethane resin > water soluble latex. Furthermore, the volumetric expansion ratio was as follows: urethane resin > water soluble latex > acrylic resin > polyinyl acetate and the hardness was as follows: polyvinyl acetate resin > acrylic resin > water soluble latex > urethane resin. This showed that the volume of expansion was reduced by expansion, which was not covered by coating, but significantly increased by increasing hardness and allowed it to be used as a refractory addition. According to the response surface methodology, the optimized addition amount and stirring speed of acrylic resin were 37.6 wt% and 441.4 rpm, respectively.

• Korean journal of food and cookery science
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• v.26 no.5
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• pp.575-585
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• 2010

This study was performed to determine the optimal composition of a muffin administered dried burdock powder and oligosaccharide. The experiment was designed base on CCD (Central Composite Design), and evaluation was carried out by means of RSM (Response Surface Methodology), which included 10 experimental points with 3 replicates for the two independent variables burdock powder and oligosaccharide. The experimental muffin was made according to a traditional recipe, except that the flour was partially replaced with dried burdock powder (5%, 15%, 25%) and the sugar was partially replaced with oligosaccharide (25%, 50%, 75%). The compositional and functional properties of the prepared products were measured, and these values were applied to the mathematical models. Using the F-test, volume, height, pH, yellowness, chewiness, resilience, springiness, cohesiveness, taste, and overall quality were expressed as a linear model, whereas lightness, redness, adhesiveness, color, flavor, and overall quality were expressed as a quadratic model. The polynomial models developed by RSM for sensory evaluation, color, flavor, texture, taste, and overall quality were highly effective in describing the relationships between the factors (p<0.01). The estimated response surfaces confirmed that the amount of burdock powder had significant effects on color, taste, texture, flavor, and overall quality (p<0.01), whereas and the amount of oligosaccharide had significant effects on color and texture (p<0.01). Increased amount of burdock powder led to reductions of the sensory scores for color, taste, texture, flavor, and overall quality at all oligosaccharide levels. The optimal mixing percentage of burdock powder and oligosaccharide muffin were determined to be 5.00% and 46.25%, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.9
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• pp.3125-3134
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• 2010

Three-way catalyst durability in the Korea requires 5 years/80,000km in 1988 but require 10 years/120,000km after 2002. Domestic three-way catalyst satisfies exhaust gas conversion efficiency or pressure drop etc. but don't satisfy thermal durability. Three-way catalyst maintains high temperature in interior domain but maintain low temperature on outside surface. This study evaluated thermal durability of three-way catalyst by thermal flow and structure analysis and the procedure is as followings. Thermal flow parameters ranges were determined by vehicle test and basic thermal flow analysis. Response surface for rear catalyst temperature was constructed using the design of experiment (DOE) for thermal flow parameters. Thermal flow parameters for rear catalyst temperature in vehicles examination were predicted by desirability function. Temperature distribution of three-way catalyst was estimated by thermal flow analysis for predicted thermal flow parameters.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.1
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• pp.31-38
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• 2004

Mechanical design process is generally accomplished by design, analysis, and test. Designers use programs fitting purpose, and obtain repeatedly a response of a simulation program, a sub-program for optimization. In this paper, shape optimization using approximate optimization technique is carried out with sequential design domain(SDD). In addition, algorithm executing Pro/Engineer and ANSYS automatically are adopted in the approximate optimization program by SDD. It is difficult for design problem to be approximated accurately for the whole range of design space. However, more or less accurate approximation is constructed if SDD is applied to that case. SDD starts with a certain range which is off-seted from midpoint of an initial design domain and then SDD of the next step is determined by a move limited. Convergence criterion is defined such that optimal point must be located within SDD during the two steps. Also, the PLBA(Pshenichny-Lim-Belegundu-Arora) algorithm is used to solve approximate optimization problems. This algorithm uses the second-order information and the active set strategy, in order to seek the direction of design variables.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.24-24
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• 2010

대형구조물의 구조안정성 진단, 로봇과 같은 지능기계의 제어, 환경오염을 감지하기 위한 센서의 중요성은 날로 증대되고 있다. 이러한 센서의 감도와 성능을 높이기 위해서 소형화, 다기능화, 집적화가 요구되고 있는데, 고성능 센서소자들의 집적화를 위해서 기존에 적용된 벌크형태의 재료들을 박막화하여 다층적층 및 소형화할 필요가 있다. 집적화 센서의 구현에 있어서 전극박막은 센서의 특성을 좌우하는 중요한 역할을 한다. 일반적으로 금속박막이 전극으로 사용되고 있으나 열적 불안정성 및 박리현상의 문제점을 지니고 있다. 따라서 이를 해결하기 위해 전도성산화막을 전극으로 적용하고자하는 연구가 요구되고 있다. 전도성산화막을 전극으로 적용하면 센서소자의 성능이 개선되는 경향이 있다. $Sr_2FeMoO_6$(SFMO) 산화물은 자기장을 인가했을 때 저항이 감소하는 CMR(colossal magnetoresistance) 물질이며 상온비저항이 낮은 것으로 알려져 있다. 이중 페롭스카이트 (double perovskite) 구조를 갖는 $Sr_2FeMoO_6$ 박막은 센서소자의 전극으로 적용 가능할 것으로 생각되어 박막을 제조하고자 하였으며 미세구조와 전기전도 특성을 조사하였다. 박막제조를 위해서는 RF 스퍼터법을 사용하였다. 스퍼터를 위한 타겟은 고상반응법으로 분말타겟을 제조하였다. Ar/$O_2$ 가스 유랑변화, 압력변화, 기판 온도변화가 박막의 상형성 등 박막특성에 미치는 영향을 조사하였다. 기판으로는 $SiO_2$(100nm)/Si 기판을 사용하였다. 증착직후에는 비정질막이 얻어졌으며 SFMO 상을 만들기 위해서는 후열처리가 필요하였는데, 환원성 가스 분위기 [$H_2$(5%)/Ar] 에서 열처리 조건을 최적화하여 이중 페롭스카이트 구조의 단일상 박막을 제조할 수 있었다. SFMO 단일상 박막은 증착시에나 후열처리 시 산소의 억제가 중요함을 알 수 있었다.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.4
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• pp.325-329
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• 2016

In this study, we investigated the feasibility of using printed Indium Tin Oxide (ITO) film as a remote sensor for Hazardous and Noxious Substances (HNS). To improve the quality of the ITO films, binder mixing ratio, Sn concentration in ITO, thermal treatment temperature, and printing process conditions were optimized. We fabricated an electrical resistance-type liquid sensor, and to confirm the sensor operation, the change in resistance in air and seawater was monitored. The change in resistance of the ITO sensor was explained in terms of reduction reaction on the surface. Further, the sensor was controlled by Arduino, and the remote data acquisition was demonstrated.

• The Korean Journal of Food And Nutrition
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• v.29 no.4
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• pp.583-594
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• 2016

The purpose of this study was to determine the optimal mixing ratio of olive oil, parmesan cheese, and nuts for preparation of pesto with spinach. Based on a surface response methodology (RSM), the independent variables were olive oil (100~300 g), parmesan cheese (25~75 g) and nuts (12~36 g). The dependent variables were physico-chemical properties as pH, color values (L, a, and b values), viscosity and sensory evaluation. pH decreased with increasing parmesan cheese levels. The L value decreased and the a and b values increased with increasing olive oil levels. Viscosity was negatively correlated with olive oil levels but positively correlated with the amounts of parmesan cheese and nuts. The addition of oil exerted a positive effect on gloss, and oily taste. In the sensory evaluation, the values of appearance, color, flavor, taste and overall acceptance were in the range of 4.4~7.2, 3.7~7.4, 4.4~7.1, 3.9~7.3 and 3.5~7.6, respectively. The sensory evaluation results showed significant values in appearance (p<0.01), flavor (p<0.01), taste (p<0.01) and overall acceptance (p<0.05). The optimal amounts of spinach pesto with olive oil, parmesan cheese, and nuts were determined by numerical optimization of a canonical model and graphical optimization. The optimal amounts were 175.29 g of olive oil, 49.51 g parmesan cheese, and 27.37 g of nuts per 100 g of spinach.