• 한국정보과학회논문지:소프트웨어및응용
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• 제29권1_2호
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• pp.91-97
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• 2002

본 논문에서는 자율수중운동체(AUVs, Autonomous Underwater Vehicles)의 실시간 충돌회피를 위한 휴리스틱 탐색기법을 논한다. 퍼지관계곱(fuzzy relational products)은 항행 환경에서 발생하는 장애물과 다음으로 이동 가능한 후보노드들과의 관계를 분석, 종합하는 수학적 도구로 사용된다. 본 논문은 영역전문가 보유한 장애물회피 관련 경험적 정보(heuristic information)를 반영하여 보다 효율적인 평가함수(evaluation function)를 고안하며 지능항행시스템의 상세경로설정(local path-planning)에 퍼지관계곱을 적용하여 보다 개선된 휴리스틱 탐색기법을 제안한다. 제안된 탐색기법의 성능검증을 위해 수행시간(cpu time), 경로의 최적화(optimization) 정도, 그리고 사용 메모리 관점에서 시뮬레이션을 통해 $A^{*}$ 탐색기법과 비교한다.

• Korean Chemical Engineering Research
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• 제60권1호
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• pp.70-79
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• 2022

Biodiesel production has attracted attention as a sustainable source of fuel and is a competitive alternate to diesel engines. The glycerol that is produced as a by-product is generally discarded as waste and can be converted to green chemicals such as acetins to increase bio-diesel profitability. Acetins find application in fuel, food, pharmaceutical and leather industries. Batch experiments and analysis have been previously conducted for synthesis of acetins using glycerol esterification reaction aided by sulfated metal oxide catalysts (SO₄^2-/CeO₂-ZrO₂). The aim of this study was to optimize process parameters: effects of mole ratio of reactants (glycerol and acetic acid), catalyst concentration and reaction temperature to maximize glycerol conversion/acetin selectivity. The optimum conditions for this reaction were determined using response surface methodology (RSM) designed as per a five-level-three-factor central composite design (CCD). Statistica software 10 was used to analyze the experimental data obtained. The optimized conditions obtained were molar ratio - 1:12, catalyst concentration - 6 wt.% and temperature -90 ℃. A packed bed reactor was fabricated and column studies were performed using the optimized conditions. The breakthrough curve was analyzed.

• Journal of Microbiology and Biotechnology
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• 제32권7호
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• pp.892-901
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• 2022

The rising demand for carotenoids can be met by microbial biosynthesis as a promising alternative to chemical synthesis and plant extraction. Several species of lactic acid bacteria (LAB) specifically produce C₃₀ carotenoids and offer the added probiotic benefit of improved gut health and protection against chronic conditions. In this study, the recently characterized Lactiplantibacillus plantarum subsp. plantarum KCCP11226^T produced the rare C₃₀ carotenoid, 4,4'-diaponeurosporene, and its yield was optimized for industrial production. The one-factor-at-a-time (OFAT) method was used to screen carbon and nitrogen sources, while the abiotic stresses of temperature, pH, and salinity, were evaluated for their effects on 4,4'-diaponeurosporene production. Lactose and beef extract were ideal for optimal carotenoid production at 25℃ incubation in pH 7.0 medium with no salt. The main factors influencing 4,4'-diaponeurosporene yields, namely lactose level, beef extract concentration and initial pH, were enhanced using the Box-Behnken design under response surface methodology (RSM). Compared to commercial MRS medium, there was a 3.3-fold increase in carotenoid production in the optimized conditions of 15% lactose, 8.3% beef extract and initial pH of 6.9, producing a 4,4'-diaponeurosporene concentration of 0.033 A₄₇₀/ml. To substantiate upscaling for industrial application, the optimal aeration rate in a 5 L fermentor was 0.3 vvm. This resulted in a further 3.8-fold increase in 4,4'-diaponeurosporene production, with a concentration of 0.042 A₄₇₀/ml, compared to the flask-scale cultivation in commercial MRS medium. The present work confirms the optimization and scale-up feasibility of enhanced 4,4'-diaponeurosporene production by L. plantarum subsp. plantarum KCCP11226^T.

• Medical Lasers
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• 제10권4호
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• pp.207-213
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• 2021

Background and Objectives This study was undertaken to assess the stability and efficacy of laser therapy (808 nm), Liquiband (a commercial topical skin adhesive product), and a combination treatment, for application in oral ulcers. Materials and Methods The oral ulcer rat animal model was used to determine the efficacy of photobiomodulation, Liquiband, or combination therapy. Ulcers were induced by injecting 60% acetic acid in the oral mucosa. Three days after ulcer confirmation, the chemically induced ulcers were treated with either laser (808 nm), Liquiband, or a combination of both, every two days for 8 days (4 sessions). Combination therapy was performed by first treating with laser followed by application of the Liquiband. Reduction in ulcer area size was subsequently determined, and animals were sacrificed at 5 and 10 days after the last administration, for histological observation of the extracted oral ulcer tissue samples. Results In this study, treatment with either laser (808 nm) or commercial Liquiband product as well as the combined treatment significantly enhanced oral ulcer healing in the rat animal model. The effect of laser treatment is mainly attributed to collagen synthesis, whereas application of the Liquiband promotes vascularization and formation of granulation tissue. Our results indicate that further optimization of the combined therapy could synergistically and significantly enhance oral ulcer healing. Conclusion Laser or Liquiband treatment of oral ulcer in the rat animal model exert different outcomes, but both methods confirm significant effects relative to the untreated group. The combined treatment group with laser and Liquiband showed marked oral ulcer healing, but further optimization is required to get highly significant results and establish the potential synergistic effect of the combination therapy, as compared to the individual enhancing effects of healing oral ulcers.

• 융합정보논문지
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• 제12권2호
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• pp.142-148
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• 2022

본 논문은 풍력발전기용 요 감속기를 경량화하여 유한요소해석과 위험속도해석을 통해 안정성검증을 하였다. 제품의 경량화는 엔진의 효율을 높일 수 있으며, 부품의 소재를 절약하여 경제적 이득을 취할 수 있다. IEC 61400-1에서 제시한 풍력발전기 부품의 안전율 1.3이상을 목표로 풍력발전기용 요 감속기를 경량화하였다. 위상 최적화를 수행한 캐리어를 유한요소해석을 수행하여 안전율을 나타냈고, 하우징과 최적화한 캐리어를 MASTA11을 활용하여 작성한 풍력발전용 요 감속기 기어트레인 모델과 부분구조합성법으로 연결하여 고유 모드와 고유진 동수를 파악하여 질량불평형과 치통과 주파수에 대하여 위험속도해석을 수행하였고, 캠벨 선도(Campbell Diagram)를 작성하여 안정성 검증을 하였다.

• Journal of Applied Biological Chemistry
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• 제66권
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• pp.29-38
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• 2023

Recent studies have highlighted the link between diseases and inflammation across our lifespan. Our sedentary lifestyle, high-calorie diet, chronic stress, chronic infections, and exposure to pollutants and xenobiotics, collectively intensify the course and recurrence of infections and inflammation in our bodies, promoting the prevalence of chronic diseases and aging. Given such phenomena and considering additional factors such as the frequency of prescription, and easy access to over-the-counter drugs, the need for anti-inflammatory therapeutics is ever-increasing. However, the readily available anti-inflammatory treatment option comes with a greater risk of side effects or high cost (biologics). Therefore in this growing competition of discovering and developing new potent anti-inflammatory drugs, we focused on utilizing the established knowledge of traditional medicine to find lead compounds. Since lead optimization is an indispensable step toward drug development, we applied this concept for the production of potent anti-inflammatory compounds achieved by structural modification of flavonoids. The derivative obtained through acetylation of myricetin, 3,3',4',5,5',7-hexaacetate myricetin, showed a greater inhibitory effect in the production of pro-inflammatory mediators such as nitric oxide, Prostaglandin E₂, and pro-inflammatory cytokines like interleukin-6, interleukin1β, in lipopolysaccharide-stimulated RAW264.7 mouse macrophage cells compared to myricetin. The increased potency of inhibition was in conjunction with an increased inhibitory effect on inducible nitric oxide synthase and cyclooxygenase-2 proteins. Through such measures, this study supports lead optimization for well-established lead compounds from traditional medicine using a simpler and greener chemistry approach for the purpose of designing and developing potent anti-inflammatory therapeutics with possibly fewer side effects and increased bioavailability.

• 자원리싸이클링
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• 제33권1호
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• pp.22-30
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• 2024

2차원 물질 MXene의 전구체로 사용되는 Ti₃AlC₂ MAX 상 합성을 위해, 출발물질로써 타이타늄 (Ti) 스크랩을 활용하는 것은 경제적인 접근이 될 수 있다. 본 연구는 Ti 스크랩을 활용하여 Ti₃AlC₂ MAX상의 상분율 향상을 위한 합성 조건의 최적화를 수행하였다. Ti 스크랩으로부터 수소화-탈수소화(hydrogenation-dehydrogenation, HDH) 공정에 의해 제조된 Ti 분말의 산소 함량은 고상탈산(Deoxidation in solid state, DOSS) 공정을 통하여 효과적으로 감소되었다. 최적 합성 조건은 25 ~ 32 ㎛의 DOSS-Ti, Al, graphite 분말을 3:1.1:2의 몰 비율로 혼합하여 합성되었다. 이 때의 Ti₃AlC₂, TiC 및 Al₃Ti의 상분율은 각각 97.25%, 0.93%, 1.82%로 나타났으며, 25 ~ 45 ㎛의 Ti₃AlC₂ MAX 분말의 산소 함량은 4,210 ppm으로 확인되었다.

• 공업화학
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• 제29권6호
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• pp.682-689
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• 2018

본 연구에서는 중심합성계획모델을 사용하여 닥나무 추출물을 함유한 cosmeceuticals 유화액의 안정성 조건을 설정하였다. 중심합성계획모델을 이용한 유화 최적화 조건으로 계량인자는 유화제와 유화안정제의 농도로, 반응치는 ESI와 PDI로 설정하였으며 ESI의 목표값은 60% 이상, PDI의 목표값은 최소값으로 하였다. 유화 최적화 결과 유화제와 유화안정제의 농도는 각각 3.73, 3.07 wt%이었으며, 이때 예상 반응치 ESI는 60%, PDI는 0.585로 산출되었다. 유화제와 유화안정제의 농도가 증가할수록 제조한 유화액의 안정성은 증가하는 경향을 보였으며, 두 가지의 계량인자 중 ESI에 가장 큰 영향을 미치는 인자는 유화제였으며, PDI에 대한 두 인자의 영향은 유사하게 나타났다. 중심합성계획모델의 실험조건으로 제조한 cosmeceuticals 유화액의 ESI는 적어도 약 45% 이상의 안정성을 보였으나 제조 후 4주 뒤에는 모두 분리되었다. 유화제의 농도가 3.72 wt% 이상일 때 ESI의 값은 60% 이상으로 나타났으며, 유화안정제의 농도가 증가할수록 층 분리 속도는 감소하였다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제7권5호
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• pp.237-251
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• 2002

The recent progress on metabolic systems engineering was reviewed based on our recent research results in terms of (1) metabolic signal flow diagram approach, (2) metabolic flux analysis (MFA) in particular with intracellular isotopomer distribution using NMR and/or GC-MS, (3) synthesis and optimization of metabolic flux distribution (MFD), (4) modification of MFD by gene manipulation and by controlling culture environment, (5) metabolic control analysis (MCA), (6) design of metabolic regulation structure, and (7) identification of unknown pathways with isotope tracing by NMR. The main characteristics of metabolic engineering is to treat metabolism as a network or entirety instead of individual reactions. The applications were made for poly-3-hydroxybutyrate (PHB) production using Ralstonia eutropha and recombinant Escherichia coli, lactate production by recombinant Saccharomyces cerevisiae, pyruvate production by vitamin auxotrophic yeast Toluropsis glabrata, lysine production using Corynebacterium glutamicum, and energetic analysis of photosynthesic microorganisms such as Cyanobateria. The characteristics of each approach were reviewed with their applications. The approach based on isotope labeling experiments gives reliable and quantitative results for metabolic flux analysis. It should be recognized that the next stage should be toward the investigation of metabolic flux analysis with gene and protein expressions to uncover the metabolic regulation in relation to genetic modification and/ or the change in the culture condition.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.428-432
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• 2003

Quantitative Feedback Theory (QFT) is one of most effective methods of robust controller design and can be considered as a suitable method for systems with parametric uncertainties. Particularly it allows us to obtain controllers less conservative than other methods like $H_{\infty}$ and ${\mu}$-synthesis. In QFT method, we transform all the uncertainties and desired specifications to some boundaries in Nichols chart and then we have to find the nominal loop transfer function such that satisfies the boundaries and has the minimum high frequency gain. The major drawback of the QFT method is that there is no effective and useful method for finding this nominal loop transfer function. The usual approach to this problem involves loop-shaping in the Nichols chart by manipulating the poles and zeros of the nominal loop transfer function. This process now aided by recently developed computer aided design tools proceeds by trial and error and its success often depends heavily on the experience of the loop-shaper. Thus for the novice and First time QFT user, there is a genuine need for an automatic loop-shaping tool to generate a first-cut solution. In this paper, we approach the automatic QFT loop-shaping problem by using an algorithm involving Linear Programming (LP) techniques and Genetic Algorithm (GA).