• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.529-535
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• 2017

In this paper the laminate design parameters are researched to maximize the performance index of a composite pressure vessel. The pressure-resistant performance and the light-weight concept with contained internal space are implied in the performance index. To maximize the performance index, the three design variables that the thickness of each of helical and hoop layers and the length of hoop layer are considered under the assumption of fixed internal space. To optimize the variables, the response surface method is introduced for construction of the surrogate model and the ANOVA(analysis of variance) is performed to evaluate the effects of the variables. The optimization problem is formulated to maximize performance index under the burst pressure constraint. To verify the effectiveness of the research, numerical analyses are performed for the optimum model.

• Applied Chemistry for Engineering
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• v.30 no.3
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• pp.337-344
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• 2019

In this study, an antioxidant was extracted from Lonicera japonica and Sophora japonica L, which was optimized by using the central composite design (CDD) model of response surface methodology (RSM). The response value of CDC model establishes the extraction yield and the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity. The extraction time, volume ratio of ethanol/ultrapure water, and extraction temperature were selected as quantitative factors. According to the result of CDC, optimal extraction conditions of Lonicera japonica were as follows; the extraction time of 2.08 h, volume ratio of ethanol/ultrapure water of 41.53 vol.%, and extraction temperature of $55.08^{\circ}C$. At these conditions the expected results indicated that the yield and DPPH radical scavenging activity were estimated as 37.88 wt% and 40.37%, respectively. On the other hand, optimal extraction conditions of Sophora japonica L. could be found as the extraction time of 2.13 h, volume ratio of ethanol/ultrapure water of 62.89 vol.%, and temperature of $50.42^{\circ}C$. Under the conditions, the (possible) maximum values of yield and DPPH radical scavenging activity were found as 35.43 wt% and 55.7%, respectively.

• Journal of the Korean Applied Science and Technology
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• v.37 no.6
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• pp.1738-1751
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• 2020

The skin is divided into three parts: the epidermis, the dermis, and the subcutaneous fat, and the stratum corneum, which is located at the top of the epidermis, acts as a barrier that prevents drug delivery. Nanoemulsions are known to be effective in transdermal delivery of drugs through intercellular lipids because of their unique small particle size. In this study, phase inversion temperature (PIT) nanoemulsion containing α-bisabolol was optimized using response surface methodology (RSM) for effective skin absorption of α-bisabolol. As a preliminary experiment, the 25-2 fractional factorial design method and the 23 full factorial design method were performed. Box-Behnken design was performed based on the results of the factorial design method. The content of surfactant (6.3~12.6%), co-surfactant (5.2~7.8%) and α-bisabolol (0.5~5.0%) were used as factors, and the dependent variable was the particle size of the nanoemulsion. PIT nanoemulsion optimization was performed according to the RSM results, and as a result, the optimal nanoemulsion formulation conditions were predicted to be 10.4% surfactant content, 6.3% co-surfactant content, and 5.0% α-bisabolol content. As a result of the skin absorption test, the final skin absorption rate of the PIT nanoemulsion was 35.11±1.01%, and the final skin absorption rate of the general emulsion as a control was 28.25±1.69%, confirming that the skin absorption rate of the PIT nanoemulsion was better.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.10
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• pp.7061-7070
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• 2015

Multi-Response Surface Optimization aims at finding the optimal setting of input variables considering multiple responses simultaneously. The Weighted Mean Squared Error (WMSE) minimization approach, which imposes a different weight on the two components of mean squared error, squared bias and variance, first obtains WMSE for each response and then minimizes all the WMSEs at once. Most of the methods proposed for the WMSE minimization approach to date are classified into the prior preference articulation approach, which requires that a decision maker (DM) provides his/her preference information a priori. However, it is quite difficult for the DM to provide such information in advance, because he/she cannot experience the relationships or conflicts among the responses. To overcome this limitation, this paper proposes a posterior preference articulation method to the WMSE minimization approach. The proposed method first generates all (or most) of the nondominated solutions without the DM's preference information. Then, the DM selects the best one from the set of nondominated solutions a posteriori. Its advantage is that it provides an opportunity for the DM to understand the tradeoffs in the entire set of nondominated solutions and effectively obtains the most preferred solution suitable for his/her preference structure.

• Korean Journal of Food Science and Technology
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• v.35 no.5
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• pp.884-892
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• 2003

This study was conducted to optimize the water homogenization process of mandarin orange peel for colored rice. Four variables were used to determine the optimum conditions for homogenization speed, time, temperature, and water volume with a five level central composite design and response surface methodology. The process was optimized using the combination of EI and b values of rice coated with water extract of the mandarin orange peel. The effect of water volume was the most significant compared to the other variables on the quality of water homogenate. The regression polynomial model was a suitable (p>0.05) model by lack-of-fit analysis showing high significance. To optimize the process, based on surface response and contour plots, individual contour plots for the response variables were superimposed. The optimum conditions for manufacturing water extract from mandarin orange was with 8,500 rpm homogenization speed, 2.8 min time, $53^{\circ}C$ temperature, and 42 mL water volume with the maximum of restricted variables of EI above 400 and h value above 24.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.340-349
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• 2016

Electro oxidation system was designed in this study for the reduction of COD (Chemical Oxygen Demand) from high-strength wastewater, produced during refinery turnaround period. First, BDD (Boron Doped Diamond) electrode was synthesized and electro oxidation system of actual industrial wastewater was developed by adopting the synthesized BDD electrode. The experiments were carried out under various operating conditions under certain range of current density, pH, electrolyte concentration and reaction time. Secondly, reaction kinetics were identified based on the experimental results, and the kinetics were embedded into a genetic mathematical model of the electro oxidation system. Lastly, design and operating parameters of the process were optimized to maximize the efficiency of the pretreatment system. The coefficient of determination ($R^2$) of the model was found to be 0.982, and it proved high accuracy of the model compared with experimental results.

• Proceedings of the Materials Research Society of Korea Conference
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• 2009.05a
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• pp.59.2-59.2
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• 2009

화학보호복은 독성이 있는 화학물질 및 미세분진등에 대해 공기를 차단하며 완전 밀폐형으로 공기호흡기 및 에어라인 같은 호흡보호장치와 함께 착용하여 신체부위를 보호한다. 그 예로 생물/화학보호복은 유독하고 해로운 생물/화학물질로 부터 인체를 보호해준다. 이들 보호복은 다양한 환경이 노출되어 장시간 작업을 위해서 오랜시간 보호성능을 유지해야한다. 특히, 이런 원단의 구성은 플라스틱과 고무류의 다층구조로 구성되어있다. 플라스틱류(폴리에틸렌, PTFE 등)는 표면장력이 너무 낮아 접착하는데 어려운 점이 많이 대두된다. 일반적인 표면처리방법은 크게 물리화학적 방법으로 4가지로 분류한다. 화학적산화, 불꽃처리, 플라즈마처리, UV 방사법 등이 있다. 이들 중에서 가장 간단한 산화처리는 플라즈마처리다. 이처리는 상온/상압하에서 대기 중 또는 가스내에 방전에 의해 플라즈마를 형성하고 이 플라즈마가 대상물의 표면분자와 격렬히 반응하게 하여 표면의 분자구조를 변화시킴에 따라 소수성의 표면에 Carboxyl, hydroxyl과 carbonyl과 같은 친수성으로 변하여 결합능력을 증가 시켜 표면장력을 높여주는 가장 효과적인 방법이다. 플라즈마 표면처리를 하고 나면 육안으로 표면의 변화를 감지할 수 없지만 접착, 잉크, 코팅을 잘 받아들이는 결과를 가져온다. 플라즈마 표면처리의 효과는 주로 부도체의 필름이나 합성수지 계열의 인쇄성과 접착성을 향상시키고자 많이 활용되고 있는 실정이다. 특히, 화학보호복과 같은 플라스틱류인 다양한 고분자 합성수지(Polyethylene, polypropylene, nylon, vinyl, PVC, PET 등)에 적용가능하다. 본 연구에서는 플라즈마처리조건에 영향을 주는 변수들을 고려하여 실험계획법(DOE, RSM)을 이용하여 최적화된 플라즈마 공정을 향상시키고자한다.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1442-1444
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• 2003

폴리머 애자용 shed 재료의 전기방전에 대한 열화내성과 표면이 오염된 조건하에서도 우수한 발수성 유지는 제품의 장기성능에 있어서 가장 중요한 인자들이다. 내트래킹성 확보를 위한 보강재로는 ATH가 주로 사용되고 있으며 ATH의 첨가량이 많을 수록 내트래킹성은 대체로 향상되는 것으로 되어 있다. 그러나 애자 제조시 무결점 성형성의 만족이 대단히 중요하기 때문에 ATH를 고충진하는 경우 사용하는 process oil들의 종류 및 첨가량을 고려한 ATH 첨가량의 최적화는 필요하다. 본 논문에서는 ATH를 170 part로 다량으로 첨가하면서 화학적 구조와 점도가 다른 몇 가지 실리콘 fliud들을 사용하여 무결점 성형에 적합한 가소도를 갖는 컴파운드를 제조하여 기본물성과 초고압 옥외절연물의 shed 재료로서 장기성능에 영향을 주는 방전열화내성과 표면발수성의 회복특성을 평가하였다. 컴파운드의 성형작업성과 관련이 큰 가소도는 fluid 점도에 따라 상당한 차이를 보이므로 실리콘 fluid 종류의 선택과 첨가량의 최적화에는 성형작업성, 발수성 회복특성, 열화내성 등의 고려가 필요하다. 무결점 애자성형을 위한 진공 사출에서 고무 컴파운드의 가소도가 중요한데 동일한 ATH첨가조건에서 일정한 가소도를 갖게 하는데 필요한 양은 fluid들의 종류에 따라서 상당한 차이가 있었다. 코로나 처리후 발수성 회복특성은 fluid들의 분자크기와 반응기의 종류에 따라 상당히 영향을 받았으며 분자가 클수록 초기회복속도는 다소 느렸지만 평상시에 늘 유지되는 상시발수성은 다소 높게 유지되었다. 아크와 트래킹 방전에 의한 무게 감소는 ATH가 과량으로 첨가되어 상당히 적었으며 fluid의 분자가 크면서 페닐기를 가진 fluid들이 첨가된 고무가 우수한 특성을 보였다.

• Food Engineering Progress
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• v.14 no.3
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• pp.217-221
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• 2010

Various conditions of acetic acid fermentation by Acetobacter aceti B20 strain were investigated and evaluated to optimize the fermentative production of acetic acid. The effects of the initial ethanol concentration on growth and acid productivity in a flask and fermentor were also studied. The growth of A. aceti B20 strain was inhibited as the concentration of ethanol increased. However, the highest total acidity and fermentation yield were 5.34% and 56.1%, respectively when the initial concentration of ethanol was 7% in the batch fermentation. Although the concentration of initial glucose influenced the growth rate of B20 strain, it did not influence the total acidity in the flask culture. When the agitation speed increased, the growth, total acidity and fermentation yield were all improved. In fed-batch fermentation, total acidities and fermentation yields were 7.14-8.76% and 39.1-53.0%, respectively, and their values mostly depended on the feeding methods.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.3
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• pp.451-459
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• 2002

High strength flour (12.5% protein) and low strength flour (10.5% protein)were used to determine optimum formulation far steamed bread added with green tea powder (GTP). The response surface study consisted of the following independent variables : GTP (1.5∼4.5%), mixing time (8∼14 min), fermentation time (30∼50min). Bread Quality attributes measured for total bread score of each combination were loaf volume, spread ratio, surface glossiness, smoothness, grain and texture (firmness, cohesiveness, elasticity and adhesiveness). The required amount of GTP, mixing time and fermentation time for steamed bread made from two kinds of flour were different. GTP could be more added to lower strength flour than higher strength flour without losing bread quality. GTP highly affected the loaf volume, spread ratio, surface smoothness, firmness and total bread score of steamed bread (p<0.001). The results suggested that the functional steamed bread added with GTP having excellent quality can be made from low strength flour using green tea powder 3.2%, mixing time 11 min 8 sec and fermentation time 39 min 55 sec.