• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.624-627
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• 2010

최근 자동차 업계서는 차량의 온실가스 배출량을 줄이고 연비를 개선시킬 수 있는 방법 중의 하나로 경량화 소재를 사용하여 차체의 중량을 줄이는 연구가 활발히 진행 중에 있다. 특히 알루미늄 합금의 경우 기존 강재에 비해 비중이 낮아 가볍고 부식에 대한 저항성이 높아 많이 사용되어지고 있는 추세이다. 본 연구에서는 먼저, 저입열 용접공정을 적용하여 용접 변수와 토치의 각도에 따른 인장강도 특성을 비교하여 적정 용접 범위를 산정하였으며, 인장강도와 비드형상의 관계를 다중 회귀 분석을 이용하여 비드 예측 회귀 모델을 제시하였다. 또한 호감도 함수를 적용한 반응표면분석법을 이용하여 자동차 생산 현장에서 겹치기 용접 이음부의 강건한 용접 품질을 가질 수 있는 최적용접 공정 조건을 도출할 수 있는 효과적인 방법을 제안하고자 한다.

• Applied Chemistry for Engineering
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• v.32 no.1
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• pp.61-67
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• 2021

In this study, the adsorption decolorization process of sea buckthorn oil was carried out to verify the possibility of the sea buckthorn oil as a natural UV absorber. The optimization was carried out by using the central composite design model-response surface methodology (CCD-RSM). The response values of CCD-RSM were selected as the decolorization effect through the process, acid value after decolorization, and UV absorbance of the decolored oil at 290nm. The amount of adsorbent, temperature and time were selected as the process variables for the experiments. According to the results of CCD-RSM, the results of optimization were all consistent. The optimal conditions, which satisfy CCD-RSM statically and mathematically, were 4.32 wt.%, 134.90 ℃, and 19.8 min for the amount of adsorbent, temperature and time, respectively. The estimated response values expected under these optimal conditions values were 94.78%, 2.08 mg/g KOH, and 2.91 for the decolorization effect, acid value and UV absorbance at 290 nm, respectively. Also the average error from actual experiment for verifying the conclusions was smaller than 2%. Therefore, it was confirmed that the application of CCD-RSM to the adsorption decolorization process of sea buckthorn oil showed a very high level of acceptable results and that the sea buckthorn oil has high possibility to be used as a natural UV absorber.

• 한국신재생에너지학회:학술대회논문집
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• 2005.06a
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• pp.264-267
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• 2005

수소의 소규모 분산 생산 기술은 본격적 인 수소 인프라가 도입되기 전에 연료전지 자동차의 수소 충 전용이나 분산 발전형 연료전지의 수소 공급을 위해 필요하다. 생산 용량은 수소 기준으로 $10\~100 Nm^3/hr$ 정도로 현재로선 천연가스의 수증기 개질법이 가장 경제적인 공정으로 알려져 있다. 소규모 생산에 따른 열효율 저하를 줄이 기 위해 단위 공정들이 통합된 컴팩트 개질 시스템의 개발이 필요하다. 핵심 기술인 컴팩트 리포머의 국산화 기술 확보를 위하여 $20 Nm^3/hr$용량의 동심관형 리포머를 설계, 제작하였다. 내부구조는 제작의 단순화를 고려하여 중첩된 동심관이 배열되었고 압력 손실과 열웅력 발생을 억제하도록 유로를 배치하였다. 수증기개질 반응에 필요한 반응열은 리포머 본체에 부착된 버너를 이용하여 공급하였다. 성능 측정을 위한 부속 기기로 상온 흡착식 탈황기, 폐열 회수형 수증기 발생기, 반응물 예열을 위한 열교환기, 생성 가스 응축기를 설계 제작하여 전체 리포밍 시스템을 구성하였다. 반응 온도 $680\~720^{\circ}C$, 탄소 대 수중기 비(S/C ratio) $2.7\~3.2$ 조건에서 수증기 개질 반응을 수행하였다. 해당 반응 조건에서 메탄 전환율 $89\%$ 이상, 저위 발열량 기준 개질 열효율 $70\%$ 이상을 달성하였고 개질 생성가스 내 수소의 최대 유량은 $23.4Nm^3/h$였다. 개발된 리포밍 시스템은 고순도 수소 생산이 필요한 경우, 수소 수율 향상을 위한 고온 수성 가스 전화 반응기를 통합 가능하도록 열교환기 구성을 조정할 수 있으며 용융 탄산염 연료전지와 같이 고온형 연료전지의 경우 $550^{\circ}C$ 이상으로 개질 생성 가스를 공급하도록 구성할 수도 있다. 향후 리포머 본체의 개질 효율 향상 및 장치 소형화, 부속 기기의 최적화를 통한 전체 리포밍 시스템 개선, 스케일 업 설계를 위한 엔지니어링 설계 패키지 구성을 계획하고 있다.

• KSBB Journal
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• v.22 no.4
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• pp.222-227
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• 2007

Biodiesel (fatty acid methyl esters) have used to as substitutes for petro-diesel by mixed-form with petro-diesel. In several processes of biodiesel production, alkali-catalyst transesterification produced to biodiesel of high contents with short reaction time. In this study, we investigate the optimal condition of alkali-catalyst transesterification of rapeseed oil produced at Jeju island in Korea using response surface methodology. The optimal condition of biodiesel production is reaction temperature 59.7$^{\circ}C$, catalyst amount 1.18%, oil to methanol molar ratio 1:8.75, and reaction time 5.18 min. At that reaction condition, the fatty acid methyl ester contents of product are above 97%. Our results may provide useful information with regard to the development of more economic and efficient biodiesel production system.

• Clean Technology
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• v.14 no.3
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• pp.211-217
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• 2008

We investigated the reduction of pollutants such as TOC (total organic carbon) and decolorization of Reactive Black 5 (RB5) by photocatalytic oxidation. The optimal values of major parameters for the reaction were obtained including the concentration of RB5, the amount of $TiO_2$ dosage and pH of solution. The values were 100 mg/L, 2 g/L and 4.9, respectively. As the concentration of oxygen increased, removal rate of pollutants increased. After $TiO_2$ was regenerated and used again by micro filtration (MF) ceramic membrane, the removal efficiency of color and removal rate of pollutants did not decrease significantly.

• Journal of the Korean Chemical Society
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• v.43 no.4
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• pp.438-446
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• 1999

The optimum analytical method of aldehydes, ozone by-products, was established by reverse phase liquid chromatography. Six aldehydes including formaldehyde, acetaldehyde, acrolein, propionaldehyde, butylaldehyde and benzaldehyde, and one ketone including acetone were selected as aldehyde test samples through preliminary experiments. Such analytical conditions as the pH of citrate buffer solution, reaction temperature, reaction time, and concentration of DNPH, the component and composition of desorption solvent were optimized. As the result, pH 3.0 of citrate buffer solution, 40$^{\circ}C$ of reaction temperature, 15 minutes of reaction time, and 0.012% of DNPH concentration were chosen as optimum conditions. Aldehydes-DNPH derivatives in water were concentrated on $C_18$ Sep-Pak cartridge and followed by elution of their derivatives fraction with THF/ACN(70/30) mixture, and showed recoveries of the range from 87 to 107%. Separation condition on Nova-Pak $C_18$ column with low pressure gradient elution from ACN/MeOH/water(30/10/60) of an initial condition to 80% ACN of a final condition was found to give a good resolution within 20 minutes of run time. 86% to 103% of recovery for aldehydes using this method was similar to that for aldehyde using EPA Method 554 which is ranged from 84% to 103%.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.3
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• pp.449-454
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• 2010

Extraction characteristics of pumpkin (Cucurbita moschata Duch.) and the functional properties of the corresponding extracts were monitored by the response surface methodology (RSM). The maximum electron donating ability was found as 24.57% at the conditions of 33.13 watt microwave power, 53.67% ethanol concentration and 3.76 min extraction time. The maximum tyrosinase inhibition was 96.59% at 56.21 watt, 68.02% and 7.97 min. The SOD-like activity was 45.57% at 36.00 watt, 71.51% and 5.28 min. The total polyphenol content was 85.02% at 127.39 watt, 76.18% and 2.68 min. Based on superimposition of four dimensional RSM with respect to electron donating ability, tyrosinase inhibition, SOD-like activity and total polyphenol contents obtained under the various extraction conditions, the optimum ranges of extraction conditions were found to be microwave power of 72~144 watt, ethanol concentration of 0~38% and extraction time of 6~9 min.

• Korean Chemical Engineering Research
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• v.48 no.5
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• pp.589-597
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• 2010

Strengthening the regulation standard of biological nutrient in wastewater treatment plant(WWTP), the necessity of repair of WWTP which is operated in conventional activated sludge process to advanced nutrient removal treatment is increased. However, in full-scale wastewater treatment system, it is not easy to fine the optimized operational condition of the advanced nutrient removal treatment through experiment due to the complex response of various influent conditions and operational conditions. Therefore, in this study, an upgrading design of conventional activated sludge process to advanced nutrient removal process using the modeling and simulation method based on activated sludge model(ASMs) is executed. And a design optimization of advanced treatment process using the response surface method(RSM) is carried out for statistical and systematic approach. In addition, for the operational optimization of full-scale WWTP, a correct analysis about kinetic variables of wastewater treatment is necessary. In this study, through partial least square(PLS) analysis which is one of the multivariable statistical analysis methods, a correlation between the kinetic variables of wastewater treatment system is comprehended, and the most effective variables to the advanced treatment operation result is deducted. Through this study, the methodology for upgrading design and operational optimization of advanced treatment process is provided, and an efficient repair of WWTP to advanced treatment can be expected reducing the design time and costs.

• Applied Chemistry for Engineering
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• v.31 no.1
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• pp.19-24
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• 2020

In this study, the O/W emulsions prepared from coconut oil and the non-ionic mixed surfactant as Tween-Span system were evaluated and optimized in order to upgrade the stability of manufactured emulsions. For the optimization, a central composite design model-response surface methodology, so called as CCD-RSM was implemented. Quantitative factors were the hydrophile-lipophilie balance (HLB), amount of non-ionic mixed surfactant and emulsification speed while experimental results included the mean droplet size (MDS), emulsion stability index (ESI), and thermal instability index (TII). Optimized values of the HLB, amount of non-ionic mixed surfactant and emulsification speed obtained from CCD-RSM were 9.1, 8.7 wt.%, and 6,200.8 rpm, respectively. Expected experimental results for MDS, ESI, and TII under the optimized experimental condition were 151.0 nm, 99.86, and 3.17%, respectively. The average error from actual experiments which established for validation of the conclusions was lower than 3.5%. Therefore, a highly favorable level could be obtained when the optimized CCD-RSM was applied to manufacturing the O/W emulsion in this study.

• The Korean Journal of Food And Nutrition
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• v.29 no.2
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• pp.228-236
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• 2016

The purpose of this study was to determine the optimum conditions of solvent extraction type and solvent concentration (60, 70, 80%, v/v), extraction time (30, 80, 130 mins) and extraction temperature (10, 15, $20^{\circ}C$) in order to increase the antioxidant activity of the chia seed. The total polyphenol content and DPPH radical scavenging activity was measured by using response surface methodology (RSM) to establish the optimal conditions. Using ethanol and methanol extractions at extraction concentrations of 60%, and time and temperature of 130 mins and $20^{\circ}C$, the maximum total polyphenol content was 871.00 mg% ($R^2=0.9507$) and 557.70 mg% ($R^2=0.9784$) for ethanol and methanol extraction respectively. Using the same extraction conditions, the maximum level of DPPH radical scavenging activity was 72.14% ($R^2=0.9675$) and 52.79% ($R^2=0.9524$) for ethanol and methanol extraction respectively. The results indicate that ethanol extracts showed a higher antioxidant activity than methanol extracts. The ethanol extraction conditions of response surface analysis (RSA) were affected more by ethanol concentration than by extraction time or temperature. In contrast, the methanol extraction conditions of response surface analysis (RSA) were affected more by extraction time. Based on the RSM, the optimum ethanol extraction conditions were the following: extraction concentration, 63%: time, 100 mins: and temperature, $18^{\circ}C$. The optimum methanol extraction conditions were the following: extraction concentration, 65%; time, 120 mins; and temperature, $16^{\circ}C$.