• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.5
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• pp.535-541
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• 2015

In this study, an approximate multi-objective optimization of a wall-mounted monitor bracket arm was performed. The rotation angle of the bracket arm was determined considering the inplane degree of freedom. We then formulated an optimization problem on maximum stress and deflection. Analyses of mean and design parameters were conducted for sensitivity regarding performance with orthogonal array and response surface method (RSM). RSM models of objective and constraint functions were generated using central composite (CCD) and D-optimal design. The accuracy of approximate models was evaluated through $R^2$ value. The obtained optimal solutions by non-dominant sorting genetic algorithm (NSGA-II) were validated through the finite element analysis and we compared the obtained optimal solution by CCD and D-optimal design.

• Applied Chemistry for Engineering
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• v.29 no.5
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• pp.565-570
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• 2018

In this study, the antioxidant was extracted from Broussonetia kazinokii using ultrasound-assisted extraction (UAE) and optimized by using a response surface methodology. The response value of the central composite design model establishes the extraction yield and the DPPH radical scavenging activity. The extraction time and temperature and volume ratio of ethanol/ultrapure water were selected as quantitative factors. When considering both the main and interaction effects, the factor having the greatest influence on the extraction yield and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity was the volume ratio of ethanol/ultrapure water. The results of optimal extraction conditions were the extraction time (19.92 min), volume ratio of ethanol/ultrapure water (54.23%), and ultrasonic irradiation power (557.65 W). We could also obtained expected results of the yield = 38.93 wt% and DPPH radical scavenging activity = 55.33% under these conditions.

• Korean Journal of Food Science and Technology
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• v.35 no.3
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• pp.399-404
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• 2003

Aliphatic polyester, especially poly(butylene adipate)(PBA), is quite biodegradable and one of the most promising polymer materials to be commercialized. Bis(4-hydroxybutyl) adipate (BHBA) formation stage is the first principal process in the production of PBA from adipic acid (AA) and 1,4-butane diol (BD). In this study, we investigated for the effective production of Bis(4-hydroxybutyl) adipate (BHBA), effects of molar ratio of adipic acid (AA) to 1,4-butane diol (BD), catalyst (tetrabutyl titanate, TBT) concentration, and temperature on the reaction rate of esterification between AA and BD were investigated. Initial reaction rate of the esterification decreased with increasing molar ratio of AA to BD and reaction temperature, whereas reaction constant increased with increase in catalyst-concentration. Activation energy values for catalyzed and uncatalyzed esterifications were 198.5 and 94.8 kJ/mol, respectively.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2013.05a
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• pp.130-131
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• 2013

최근 연구에서는 상용 통계분석 프로그램인 Minitab을 사용하여 실험 요소 설계 및 최적 공정조건을 구하는데 많이 이용하고 있다. 본 연구에서는 도금 제품의 Peeling 최적화를 위해 도금 전처리 공정인 에칭 및 화학 니켈 공정 시간을 인자로 설정하였다. 또한 2인자 2수준(2 factor 2 Level)의 직교 배열표를 구성하고 도금 제품의 밀착성을 만족하는 범위 내에서 설계변수에 의한 반응표면법(Response surface analysis)을 사용하여 최적 조건을 설정하였다. 실험 결과, 에칭 및 화학니켈 공정 시간의 주효과도에서 에칭 공정시간이 낮을수록, 화학니켈 공정시간이 높을수록 Peeling 값이 향상된다는 결과를 얻었다. 그리고 최적 조건을 도출하기 위한 방법으로 반응표면 설계법 중의 중심합성법을 사용하여 에칭(10min 15sec)및, 화학니켈(10min 15sec)의 최적 공정 시간을 도출하였다.

• Applied Chemistry for Engineering
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• v.29 no.3
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• pp.325-329
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• 2018

In this study, polyphenols were extracted from Angelica, which are known to have a high antioxidant content and the extraction process was optimized using the response surface methodology. The extraction yield and the total polyphenols were set as response values for the methodology. Quantitative factors in the extraction process were the extraction time, volume ratio of alcohol/ultrapure water, and extraction temperature. When considering both the main and interaction effects, the greatest influence factor on the extraction yield and total polyphenols was the extraction time. The optimum extraction time and temperature and alcohol/ultrapure water volume ratio for angelica were 2.8 h, $56.6^{\circ}C$ and 64.0 vol% respectively. The extraction yield and total polyphenols when using the conditions were calculated to be 24.6% and 8.76 mg GAE/g. respectively. Determination coefficients of regression equations for the extraction yield and total polyphenols were 81.4 and 75.4%, respectively. Also the overall satisfaction level was found to be 0.80 and the significance was confirmed within 5%.

• Korean Journal of Food Science and Technology
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• v.50 no.5
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• pp.474-479
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• 2018

In this study, ultrasound-assisted extraction conditions of total anthocyanins and total phenolic compounds from Campbell early grape (Vitis labruscana) were optimized via response surface methodology using a Box-Behnken design. Three independent variables, including solid-liquid ratio (1/30-1/50 g/mL), extraction time (2-10 min), and amplitude (20-100%), significantly affected total anthocyanin content. However, no significant effect of these variables was observed in the total phenolic compound content. The optimized extraction conditions were solid-liquid ratio of 1/48.13 g/mL, extraction time of 2 min, and amplitude of 20%. Under these conditions, the predicted values of total anthocyanins and total phenolic compounds were 94.96 and 1,661.16 mg/100 g dry weight (DW), respectively. The experimental values of total anthocyanins and total phenolic compounds were 88.25 and 1,554.37 mg/100 g DW, respectively, which is well matched with the predicted values within 7.5% difference.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.1
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• pp.116-120
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• 2009

Response surface methodology (RSM) was applied to optimize alcohol fermentation of concentrated grape juice. Sugar concentration ($X_1$), agitation rate ($X_2$) and fermentation time ($X_3$) were chosen as the independent variables of the central composite design (CCD). Dependent variables were alcohol content ($Y_1$) and total acidity ($Y_2$). To optimize two dependent variables, desirability function was defined as $Y_1$=10.0% and $Y_2$=minimum. The optimum conditions for alcohol fermentation were $19.98^{\circ}Bx$ (sugar concentration), 104.1 rpm (agitation rate) and 89.67 hr (fermentation time). The predicted responses were 10.0% in alcohol content and 0.86% in total acidity. The coefficients of determination ($R^2$) were 0.948 and 0.958, which indicate that the model fit was highly significant (p<0.001). The experimental values were 10.1% for alcohol content and 0.88% for total acidity. These values were similar to the predicted values from RSM.

• KSBB Journal
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• v.18 no.1
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• pp.8-13
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• 2003

Recombinant trehalose synthase from Thermus caldophilus GK24 showed an ability to produce trehalose from maltose. The activity of the partially purified enzyme was not influenced by most metal ions at 1 mM but was inhibited by 10 mM $Co^{2+}$, $Mn^{2+}$, and $Fe^{2+}$. Enzyme activity varied during prolonged reaction due to changes in the environmental conditions. Thus, the reaction was carried out for an extended time with optimized conditions of $45^{\circ}C$ and pH 7.0. An yield of 32.9% was reached at $60^{\circ}C$ after reaction for 22 h, and, maximum trehalose conversion (69.2%) was attained at $25^{\circ}C$. The yields obtained using enzyme dosages of 10, 25, and 50 U/g were 62.3, 62.3 and 59.0 %, respectively, though the initial conversion rate was higher when the higher dose was used. Similar profiles of trehalose production yields were observed with reaction working volumes of 10 ml to 2,000 ml.

• Korean Journal of Food Science and Technology
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• v.29 no.2
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• pp.249-254
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• 1997

Stevioside was transglucosylated to improve its sweetness. Eighteen conditions were tested using the tables of orthogonal arrays of $L_{18}\;(2^{1}{\times}3^{7})$. Statistical analysis showed that the transglucosylation rate was significantly affected by temperature, the ratio of co-substrate (maltodextrin) to stevioside, pH, DE of maltodextrin and concentration of stevioside, in their order. Optimum conditions selected for temperature, ratio of co-substrate to stevioside, pH and DE of maltodextrin were $80^{\circ}C$, 1.0, 6.0 and 15, respectively. Glycosyl-stevioside with 68% yield of transglucosylation was produced at the optimum condition and found to have better quality in sweetness than stevioside and rebaudioside A.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.67-72
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• 2000

PET는 합성섬유, 필름, 음료수병, 성형 플라스틱 등의 다양한 용도를 가지고 있으며 특히 섬유 원료부분에서는 전세계의 약 40%이상을 차지하고 있는 상업적 입장에서 아주 중요한 소재이다.［1］그러나, PET 제조공정은 긴 반응시간과 높은 반응온도, 대용량의 다단계 공정시설을 필요로 하는 대표적인 에너지 다소비 공정으로서 현대의 치열한 고분자 제품의 시장경쟁 상황에서 에너지 투입량 감축을 위한 공정의 해석 및 개발과 그로 인한 생산원가의 절감이 필수적이다. 본 연구에서는 실제 공장에서 사용되는 단일 연속식 직접 에스테르화 반응기(CSTR Direct Esterification Reactor)를 모델링하고 Van Krevelen［2］의 Group contribution method로 계산된 올리고머의 열용량값을 이용하여 에너지 소모량을 계산하였다. 모델링 결과는 모두 실제 공장의 자료와 비교되었으며 가장 제어하기 쉬운 변수에 따른 반응물의 물성과 에너지 소모량을 분석하였다. 또한 압력이 일정한 조건 하에서 입력변화에 따른 반응기의 동적 모델링을 동시에 수행하였으며 투입에너지량과 반응기의 운전지표와의 관계를 분석하였다. 이러한 연구는 실제 공정분석과 최적화에 있어서 소모 에너지량을 고려한 보다 정확한 지표를 제시하고 에너지 사용의 효율성을 높이는 데 기여할 수 있다.