• 한국수소및신에너지학회논문집
• /
• 제24권1호
• /
• pp.50-60
• /
• 2013

High temperature proton exchange membrane fuel cells (PEMFCs) using phosphoric acid (PA) doped polybenzimidazole (PBI) membranes have been concentrated as one of solutions to the limits with traditional low temperature PEMFCs. However, the amount of reported experimental data is not enough to catch the operational characteristics correlated with cell performance and durability. In this study, design of experiments (DOE) based operational optimization method for high temperature PEMFCs has been proposed. Response surface method (RSM) is very useful to effectively analyze target system's characteristics and to optimize operating conditions for a short time. Thus RSM using central composite design (CCD) as one of methodologies for design of experiments (DOE) was adopted. For this work, the statistic models which predict the performance and degradation rate with respect to the operating conditions have been developed. The developed performance and degradation models exhibit a good agreement with experimental data. Compared to the existing arbitrary operation, the expected cell lifetime and average cell performance during whole operation could be improved by optimizing operating conditions. Furthermore, the proposed optimization method could find different new optimal solutions for operating conditions if the target lifetime of the fuel cell system is changed. It is expected that the proposed method is very useful to find optimal operating conditions and enhance performance and durability for many other types of fuel cell systems.

• 한국식품영양학회지
• /
• 제27권6호
• /
• pp.1175-1181
• /
• 2014

This study was conducted to develop for the elderly food that is safe, well-shaped, and easy to chew and swallow, using gelification. Gelatin, which has low adhesiveness, thereby lowering the possibility of being swallowed wrongly into the respiratory track, was used as a viscosity agent for the gelification. Water and gelatin amounts were adjusted to facilitate breaking the food with the tongue. Various foods for the elderly with chewing and swallowing difficulties were used for sensory assessment. Sensory panel consisted of 10 dietitians (10 women) in nursing care facilities. The sensory optimal composite recipes were determined by central composite design (CCD). The sensory measurements were significantly different in appearance (p<0.05), saltiness (p<0.05), sweetness (p<0.01), and overall quality (p<0.05). The optimum formulation of the Korean barbecue beef calculated by numerical and graphical method was 3.71 g of sugar and 19.53 g of soy sauce. Moisture content, hardness and adhesiveness of the Korean barbecue beef were 78.85%, 2.40, -1.87, respectively. The result shows that food for the elderly, which is easy to chew and swallow, using gelification will have sufficient competitiveness in terms of safety, taste, and preference. The development of food for the elderly that take into account the difficulties in chewing and swallowing among the elderly, reflects their preference, and has sufficient nutrients, is important to enable the elderly to enjoy their meals. Also, as the Korean society is getting older, it remains one of the biggest social challenges.

• 한국식품영양학회지
• /
• 제29권4호
• /
• pp.480-485
• /
• 2016

This study was conducted to develop food for the elderly, which is easier to chew and swallow, using gelification. Various foods for the elderly with chewing and swallowing difficulties were used for sensory assessment. The sensory panel consisted of 10 dieticians (10 women) working in nursing care facilities. The sensory optimal composite recipes were determined by the central composite design (CCD). The optimum formulation of hot pepper paste stir fried pork calculated by the numerical and graphical method was 1.48 g of sugar and 18.97 g of hot pepper paste. The optimum formulation of seasoned spinach was 8.0 g of sesame oil and 5.41 g of soy sauce. Moisture content, hardness, and adhesiveness of hot pepper paste stir fried pork was 76.49%, 2.50, and -1.20, respectively. Moisture content, hardness, and adhesiveness of seasoned spinach was 83.48%, 2.27, and -1.17, respectively. This study provides the basic materials for the development of easily chewable and swallowable foods for the elderly, which can reduce the risk of food going down the wrong pipe, and the preference can be improved by eating solid food instead of porridge or liquid food. The development of food for the elderly, which takes the difficulties in chewing and swallowing among the elderly into consideration and reflects their preference and has sufficient amount of nutrients, is important to enable the elderly to enjoy their meals and it is one of the biggest challenges in Korea, as Korean society is aging rapidly.

• Ocean and Polar Research
• /
• 제39권4호
• /
• pp.269-277
• /
• 2017

Medium compositions for the hyperthermophilic archaeon, Thermococcus onnurineus NA1 was statistically optimized to enhance formate-driven hydrogen ($H_2$) production by using response surface methodology. From the Plackett-Burman design-based experiment, it was confirmed that among the minor components of medium such as KCl, $MgSO_4$, $NH_4Cl$, Cystein-HCl, trace elements, Fe-EDTA and $CaCl_2$, the trace elements were screened as the only positively effective components with respect to $H_2$ production. Subsequently, the optimal concentrations of the trace elements and the major components of a medium such as NaCl, yeast extract and sodium formate were determined from the five-level central composite design (CCD)-based experiment. The resulting quadratic model predicted the maximum $H_2$ production of 46.6 mmol/L in serum bottle and it was validated experimentally using the optimal medium initially supplemented with 26.70 g/L of NaCl, 9.81 g/L of sodium formate, 3.50 g/L of yeast extract and 4.59 mL/L of trace elements. From the duplicate batch cultivations in the fermentor using the optimized medium, the a maximum $H_2$ production rate up to 71.8 mmol/L/h could be obtained, which was a 65% enhanced value compared with that obtained using the control medium, showing the high efficiency of the optimized medium.

• Journal of Microbiology and Biotechnology
• /
• 제30권8호
• /
• pp.1252-1260
• /
• 2020

(R)-2-(4-hydroxyphenoxy)propionic acid (HPOPA) is a key intermediate for the preparation of aryloxyphenoxypropionic acid herbicides (R-isomer). In order to improve the HPOPA production from the substrate (R)-2-phenoxypropionic acid (POPA) with Beauveria bassiana CCN-A7, static cultivation and H₂O₂ addition were attempted and found to be conducive to the task at hand. This is the first report on HPOPA production under static cultivation and reactive oxygen species (ROS) induction. On this premise, the cultivation conditions and fermentation medium compositions were optimized. As a result, the optimal carbon source, organic nitrogen source, and inorganic nitrogen source were determined to be glucose, peptone, and ammonium sulfate, respectively. The optimal inoculum size and fermentation temperature were 13.3% and 28℃, respectively. The significant factors including glucose, peptone, and H₂O₂, identified based on Plackett-Burman design, were further optimized through Central Composite Design (CCD). The optimal concentrations were as follows: glucose 38.81 g/l, peptone 7.28 g/l, and H₂O₂ 1.08 g/l/100 ml. Under the optimized conditions, HPOPA titer was improved from 9.60 g/l to 19.53 g/l, representing an increase of 2.03-fold. The results obtained in this work will provide novel strategies for improving the biosynthesis of hydroxy aromatics.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2002년도 생물공학의 동향 (X)
• /
• pp.381-384
• /
• 2002

Response surface methodology (RSM) was successfully applied to optimize for the production of Ganoderma lucidum in batch fermentations using the whey (40,000 mg latose/L) as substrate. This study was performed according to the central composite design (CCD) with respect to pH and temperature, where the designed intervals were 3.3$22.9^{\circ}C$$37.1^{\circ}C$, respectively. A second-order factorial design of the experiments was used to build empirical models providing a quantitative interpretation of the relationships between the two variables. The optimum conditions to maximize the production of G. lucidum were pH 4.2 and $28.3^{\circ}C$. At optimum conditions, the mycelial dry weight (MDW) and residual soluble COD (SCOD) were simultaneously used to evaluate the biokinetic coefficients assocoated with substrate inhibition model by nonlinear least squares method with 95% confidence interval. The. maximum microbial growth rates (${\mu}m$), half saturation coefficient ($K_s$), and the inhibition substrate concentration ($K_{is}$) were determined to be 0.095 l/hr, 128,000 mg SCOD/L and 49,000 mg SCOD/L, respectively. And the microbial yield coefficient (Y), biomass decay rate coefficient ($K_d$), and the maintenance energy coefficient ($m_s$) were determined to be 0.37 mg MDW/mg SCOD, 0.001 1/hr, and 0.0015 1/hr, respectively.

• 한국미생물·생명공학회지
• /
• 제41권1호
• /
• pp.52-59
• /
• 2013

The nutritional requirements for the maximum production of lipopeptides by Bacillus subtilis N7 (B. subtilis N7) were investigated and optimized using response surface methodology (RSM) under shake flask fermentation. A one-factor-at-a-time experimental setup was used to screen carbon and nitrogen sources. A Plackett-Burman design (PBD) was employed to screen the most critical variables for lipopeptides production amongst ten nutritional elements. The central composite experimental design (CCD) was finally adopted to elucidate the composition of the fermentation medium. Statistical analyses (analysis of variance, ANOVA) of the results showed that KCl, $MnSO_4$ and $FeSO_4{\cdot}6H_2O$ were important components and that their interactions were strong. Lipopeptide production was predicted to reach 709.87 mg/L after a 60 h incubation using an optimum fermentation medium composed of glucose 7.5 g/L, peanut oil 1.25 g/L, $MgSO_4$ 0.37 g/L, $KH_2PO_4$ 0.75 g/L, monosodium glutamate 6.75 g/L, yeast extract and $NH_4Cl$ (5:3 w/w) 10 g/L, KCl 0.16 g/L, $FeSO_4{\cdot}6H_2O$ 0.24 mg/L, $MnSO_4$ 0.76 mg/L, and an initial pH of 7.0. Lipopeptide production ($706.57{\pm}3.70$ mg/L) in the optimized medium confirmed the validity of the predicted model.

• 한국축산식품학회지
• /
• 제38권3호
• /
• pp.580-592
• /
• 2018

The formulation of an oil/water (o/w) emulsion made up of a mixture of perilla oil and canola oil (30/70 w/w) was optimized using a response surface methodology to find a replacement for animal fat in an emulsion-type meat product. A 12 run Plackett-Burman design (PBD) was applied to screen the effect of potential ingredients in the (o/w) emulsion, including polyglycerol polyricinoleate (PGPR), fish gelatin, soy protein isolate (SPI), sodium caseinate, carrageenan (CR), inulin (IN) and sodium tripolyphosphate. The PBD showed that SPI, CR and IN showed promise but required further optimization, and other ingredients did not affect the technological properties of the (o/w) emulsion. The PBD also showed that PGPR played a critical role in inhibiting an emulsion break. The level of PGPR was then fixed at 3.2% (w/w total emulsion) for an optimization study. A central composite design (CCD) was applied to optimize the addition levels of SPI, CR or IN in an (o/w) emulsion and to observe their effects on emulsion stability, cooking loss and the textural properties of a cooked meat emulsion. Significant interactions between SPI and CR increased the cooking loss in the meat emulsion. In contrast, IN showed interactions with SPI leading to a reduction in cooking loss. Thus, CR was also removed from the formulation. After optimization, the level of SPI (4.48% w/w) and IN (14% w/w) was validated, leading to a perilla-canola oil (o/w) emulsion with the ability to replace animal fat in an emulsion-type meat products.

• 한국지반환경공학회 논문집
• /
• 제12권4호
• /
• pp.25-31
• /
• 2011

본 연구의 목표는 전자빔공정을 통한 1,4-dioxane 처리의 최적화를 이루기 위해 실험계획법을 적용하는 것이다. 주요 인자를 1,4-dioxane removal efficiencies(%), TOC removal efficiencies(%)로 반응표면분석법(RSM) 중 중심합성실험법을 이용하여 수학적으로 표시하였다. 1,4-dioxane의 농도를 "$x_1$", Irradiation intensity를 "$x_2$"로 지정하였다. 1,4-dioxane 농도와 removal efficiencies(%)의 코드화된 회귀방정식은 $y=71.00-10.85x_1+20.67x_2+{1.53x_1}^2-{7.92x_2}^2-1.23x_1x_2$, 1,4-dioxane 농도와 TOC Removal efficiencies(%)의 코드화된 회귀방정식은 $y=44.48-13.25x_1+9.54x_2+{5.43x_1}^2-{1.35x_2}^2+4.45x_1x_2$로 나타났다. 모델 예측식의 $R^2$(Adj.)가 90%이상으로 실험적인 관찰결과 잘 맞는 것으로 나타났다. 마지막으로 조류 Pseudokirchneriella Subcapitata를 이용하여 전자빔에 의한 1,4-dioxane에 대한 독성평가를 실시한 결과 전자빔 조사선량의 증가에 따라 생물학적 방해영향이 저감되었다.

• 응용통계연구
• /
• 제25권1호
• /
• pp.215-223
• /
• 2012

반응표면 방법론은 어떤 공정을 개선하거나 최적화하는데 이용되는 아주 유용한 통계적방법이다. 이러한 최적조건을 추정하기 위하여 최적조건이 있으리라 예상되는 실험구역을 탐색하여 실험을 실시한다. 그런데 이 실험구역은 실험의 환경의 제약 그리고 연구자의 선택 등으로 그 모습이 다양하게 달라질 수 있다. 반응표면 설계는 실험구역의 모양에 따라 보통 둥그런 모양의 "구형설계"와 육면체 모양의 "입방형설계"로 구분한다. 구형설계는 회전성을 만족하거나 회전성에 상당히 근접하는 "유사회전성"을 갖는 특징이 있다. 반응표면 설계에서 가장 많이 사용되는 중심합성설계는 실험구역이 구형인 5수준 실험설계이다. 이 때, 축점의 ${\alpha}$값을 ${\alpha}=\sqrt{k}$ 대신 ${\alpha}=1$로 조정하면 5-수준이 아닌 3-수준 입방형 중심합성설계를 얻을 수 있다. 그러나 입방형 중심합성설계는 실험구역이 구형이 아니므로 회전성을 만족하지 못하는 문제가 있다. 이러한 이유로, 변수들의 수준 수를 3으로 제한하면서 실험구역은 구형인 실험설계가 필요할 때가 많다. 이에 대한 대표적 실험설계가 바로 박스-벤켄 실험설계이다. 이 실험설계는 구형의 실험구역으로 회전성을 만족하나 실험구역의 크기가 변수의 개수가 증가해도 제자리 수준으로 좁은 특징이 있다. 현실적으로 실험구역의 가상 자리 부분에 대한 예측에 관심이 있을 경우 변수의 개수가 많아지면 이에 비례하여 실험구역이 커지는 실험설계가 바람직하다. 본 논문은 3-수준 입방형설계에 비하여 실험구역이 유달리 좁은 박스-벤켄 실험설계를 보완하여 구형설계를 만족하면서도 다른 한편으로는 변수 수에 따라 실험반경이 커지는 3-수준 구형 반응표면 설계를 소개하고자 한다. 이 방법을 기존의 실험설계들과 비교한 결과 변수수가 비교적 작을 경우 실험횟수 등을 고려하여 응용가치가 있음을 확인하였다.