• Journal of Korean Society of Water and Wastewater
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• v.35 no.1
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• pp.63-69
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• 2021

Microalgae are primary producers of aquatic ecosystems, securing biodiversity and health of the ecosystem and contributing to reducing the impact of climate change through carbon dioxide fixation. Also, they are useful biomass that can be used as biological resources for producing valuable industrial products. However, harvesting process, which is the separation of microalgal biomass from mixed liquor, is an important bottleneck in use of valorization of microalgae as a bioresource accounting for 20 to 30% of the total production cost. This study investigates the applicability of sewage sludge-derived extracellular polymeric substance (EPS) as bioflucculant for harvesting microalgae. We compared the flocculation characteristics of microalgae using EPSs extracted from sewage sludge by three methods. The flocculation efficiency of microalgae is closely related to the carbohydrate and protein concentrations of EPS. Heat-extracted EPS contains the highest carbohydrate and protein concentrations and can be a best-suited bioflocculant for microalgae recovery with 87.2% flocculation efficiency. Injection of bioflocculant improved the flocculation efficiency of all three different algal strains, Chlorella Vulgaris, Chlamydomonas Asymmetrica, Scenedesmus sp., however the improvement was more significant when it was used for flocculation of Chlamydomonas Asymmetrica with flagella.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.29 no.1
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• pp.15-25
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• 2023

Since the COVID-19 crisis, the use of disposable packaging materials and delivery services, which raise environmental and social issues with waste disposal, has significantly increased. Antimicrobial active packaging has emerged as a viable solution for extending the shelf-life of foods by minimizing microbial growth and decomposition. In this review article, we provide a comprehensive overview of current research trends in antimicrobial active film and coating published over the last five years. First, we introduced various polymer materials such as film and coating that are used in active packaging. Next, various types of antimicrobial (antibacterial, antifungal, and antiviral) packaging including essential oil, extracts, biological material, metal, and nanoparticles were introduced and their activities and mechanisms were discussed. Finally, the current challenges and prospects were discussed. Overall, this review provides insights into the recent advancements in antimicrobial active packaging research and highlights the potential of the technology to enhance food safety and quality.

• 한국생물공학회:학술대회논문집
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• 2003.10a
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• pp.761-762
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• 2003

Recently, several studies have reported on the successful repair of osteochondral defects by transplantation of cultured chondrocytes, but the method requires a sufficient number of cells obtained from the donor site in the articular cartilage. This can potentially be overcome by the use of undifferentiated or partially developed cartilage precursor cells drived from early embryos and fetal tissue. Neonatal cartilage unlike adult cartilage has the capacity for rapid regeneration. the purpose of this study is to determine effective regeneration method using early cartilage precursors for tissue-engineered cartilage. Cells isolated from neonatal (immediately postpartum, 2 hours of age) SD rats were seeded onto biodegradable polymer matrices and transplanted in nude mice's subcutaneous sites for 4 and 8 weeks. Tissue-engineered cartilage showed gross and histologic evidences similar to native articular cartilage.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.277-282
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• 1989

Xanthan gum is a biopolymer produced by Xanthomonas campestris. In xanthan gum fermentation, the fermentation broth changes to highly viscous non-Newtonian fluid as xanthan gum concentration increases. Maximum xanthan gum concentration is limited by high viscosity of the broth since mass transfers of nutrient and oxygen are inhibited. Int this study the mass transfer effects were investigated in batch and fed-batch fermentations at various agitation speeds and by separate oxygen transfer experiments. Xanthan gum production rate was observed to be largely dependent on oxygen transfer coefficient; while cell growth rate was not affected highly by this factor.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.591-594
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• 2003

In the present study, we developed a filling material composed of poly(lactic-co-glycolic) acid (PLGA) microspheres with applications in the treatment of facial wrinkle and urinary incontinence and studied the feasibility of injecting the filling materials in animal models for plastic surgical and urological applications. Former filling materials including Teflon, Silicon, and collagen have shown a few shortcomings such as inflammation reaction, particles migration or volume decrease. We injected PLGA microspheres into the subcutaneous dorsum of mice. Injected volume was constantly maintained after implanting. We hardly found either inflammation reaction or migration. This material overcomes the problems of the current filling materials and could be utilized as a new filling material for plastic surgical and urological applications.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.644-647
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• 2000

The properties of hydrogen bonding between poly(2-ethyl-2-oxazoline)[PEOx] and poly(acrylic acid)[PAA] were investigated. PEOx and PAA formed stable complex and precipitated due to hydrogen bonding between hydrogen of PAA and oxygen of PEOx in acidic condition(below pH 4.3). Optimum reaction ratio of PEOx and PAA was determined as mass ratio of 1:1.5 for applications in aqueous two phase system. The mixtures of the polymers formed aqueous two phase system with dextran solution after the breakage of hydrogen bondings. This properties can be used for the recovery of valuable products.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.59-61
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• 2002

The injury of meniscus, integral components of the knee joint, is a common sports-related problem and the most frequent injurγ to the knee joint.$^1$ This study was aimed to tissue-engineer meniscus in rabbit models. Cells isolated from rabbit meniscus were seeded onto meniscus-shaped, biodegradable polymer matrices and implanted to rabbit knee joints The tissue-engineered meniscus explanted at 6 and 10 weeks showed gross and histologic evidences similar to those of native meniscus. This study may lead to the development of tissue-engineered meniscus appropriate for clinical applications.

• 한국생물공학회:학술대회논문집
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• 2002.04a
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• pp.379-380
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• 2002

Biodegradable polymers have been regarded as a good alternative to solve the plastic waste problems caused by nondegradable synthetic polymers such as polyethylene and polystyrene. In the soil environment, plastics are mainly being used as a mulching film for agricultural purposes. In this research, the miscibility, tensile properties and biodegradation effect of poly-${\varepsilon}$-caprolactone(PCL) with polyvinyl chloride(PVC) have been studied. After 8 weeks of biodegradation, PCL/PVC(9/91) blend surface showed newly formed many holes. Consequently, the antiplasticization phenomenon and biodegradation were observed in the PCL/PVC blends. It was confirmed that a test for general biodegradation condition can be applied to plastic biodegradation in soil.

• Bulletin of Food Technology
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• v.14 no.4
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• pp.52-59
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• 2001

미국 내에서 첨단 농업과 관련한 학문 연구 및 기술개발 활동이 가장 활발하며, 농산물의 수확 후 관리기술 등의 분야에서 세계적으로 명성이 높은 University of California, Davis에서 지난 2000년 10월 9일부터 200 1년 10월 7일까지 1년간 해외연수를 수행하였다. 연수 지도교수였던 식품공학과(Food Sci. & Technol.) 및 생물.농공학과(Bio. & Agric. Engin.) 소속의 Dr. John M. Krochta는 천연소재의 환경친화성 생고분자 (biopolymer ) 필름/ 피막의 제조 기술과 특성 평가에 관한 연구분야에서 이미 수많은 탁월한 연구성과를 축적한 저명 과학자로서, 실제 연수를 수행한 식품공학과 내의 Packaging & Biopolymer Film Lab.에서는 최근 10년 동안 주로 유가공 부산물인 유청 단백질(whey proteins )을 원료로 한 생고분자 필름/ 피막을 개발하여 각종 신선 농산물 및 가공식품에 대한 적용 가능성 연구를 수행하면서 다수의 연구논문과 저서, 특허를 배출하고 있었다. 필자는 연수기간동안 whey protein films의 산소 차단특성을 활용하여 기존 합성 고분자 재질의 산소 차단재를 대체할 수 있는 새로운 생고분자 포장재로서 whey protein coating의 제조 및 성능 평가에 관한 연구를 수행한바, 이에 간략히 그 내용과 결과를 소개하고자 한다.

• Journal of Life Science
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• v.29 no.3
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• pp.362-368
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• 2019

For the practical application and development of biopolymer flocculant Biopol32 produced by Pseudomonas sp. GP32, its flocculation effect on wastewater from food processing, slaughter houses, and the dyeing industry was investigated. In the food processing wastewater, Biopol32 led to a chemical oxygen demand (COD) reduction rate of 70% and a suspended solid (SS) removal rate of 49% at pH 6.0. In the slaughter house wastewater at pH 4.0, a COD reduction rate of 61% and SS removal rate of 91% were observed, and in the dyeing wastewater, the rates were 72% and 92%, respectively, at pH 5.0. The size of floc formed during the flocculation process was 10 mm at a final concentration of 20 ppm, and the dehydration efficiency was 62%. In both the bioflocculant Biopol32 group and a PAA synthetic flocculant group, optimal flocculant concentration that yielded the best overall dehydration efficiency was 20 ppm, and, at this concentration, the shortest filtration time to reach the natural critical moisture content of 78.1% was attained.