• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.237-240
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• 2000

Organic acids which were produced from biomass wastes streams by cell-recycle fermentation using Propionibacterium acidipropionici ATCC 4965 were extracted by Membrane Contactor using TOA/MIBK system. Maximum productivity was 3.32g organic acid/L/hr at the dilution rate of 0.2/hr in the results of continuous fermentation. The diluted organic acids in the fermenter were selectively separated by Membrane Contactor extraction using 30%(w/w) trioctylamine(TOA) dissolved in methylisobutylketone(MIBK). The flow rate of aqueous phase is 200ml/min and that of extraction phase is 100ml/min. The degree of Acetic acid and Propionic acid extraction from fermentation broth was reached 56.25%, 72.41% respectively.

• Journal of Korea Multimedia Society
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• v.9 no.2
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• pp.208-214
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• 2006

Participants of a NVE(networked virtual environment) may have different hardwares and network environments, and to guarantee the fairness, messages of participants should be synchronized. A solution for the synchronization problem is to wait for a certain amount of time until the server processes the message. It is not easy to determine a suitable waiting period because of the trade-off between the fairness and the responsiveness. In this paper we propose a method to decide a waiting period by considering only the participants with small network delays and perform experiments for the performance evaluation. Experiments show that the proposed method leads to significant improvement of responsiveness, while retaining fairness.

• Microbiology and Biotechnology Letters
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• v.48 no.3
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• pp.344-357
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• 2020

Strain improvement and bioprocess development were undertaken to enhance hyaluronic acid(HA) production by Streptococcus zooepidemicus cells. Using a high-yielding mutant strain, statistical medium optimization was carried out in shake flask cultures, resulting in 52% increase in HA production (5.38 g/l) at the optimal medium composition relative to the parallel control cultures. For sufficient supply of dissolved oxygen (DO), which turned out to be crucial for enhanced production of HA, agitation system and speed were intensively investigated in 5 L bioreactor cultures. Increase in oxygen mass transfer coefficient (k_La) through increment of agitation speed (rpm) and 35% expansion of diameter of the newly-designed impellers showed significantly positive effects on HA production. By installing an expanded Rushton-turbine impeller for efficient break-down of sparged air, and an extended marine impeller above the Rushton-turbine impeller for efficient mixing of the air-born viscous fermentation broth, maximum amount of HA (9.79 g/l) was obtained at 450 rpm, 1.8 times higher level than that of the corresponding flask culture. Subsequently, the possibility of bioprocess scale-up to a 50 L bioreactor was investigated. Despite almost identical maximum HA production (9.11 vs 9.25 g/l), the average HA volumetric productivity (r_p) of the 50 L culture turned out only 74% compared to the corresponding 5 L culture during the exponential phase, possibly caused by shear damages imposed on the producing cells at the high stirring in the 50 L culture. The scale-up process could be successfully achieved if a scale-up criterion of constant oxygen mass transfer coefficient (k_La) is applied to the 50 L pilot-scale bioreactor system.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2018.04a
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• pp.64-64
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• 2018

생물전환(Bioconversion)은 천연소재의 기능성을 증대시키기 위한 방안으로 많은 연구가 진행되고 있으며 다양한 산업에서도 활용되고 있어 유용미생물을 기반 차세대 기술로 각광받고 있다. 이러한 기술의 도입은 식품은 물론 의약품 및 화장품 산업에서도 활발히 사용되고 있으며, 특히 최근 기능성 제품에 대한 소비가 급증함에 따라 그 중요성이 높아지고 있다. 산초(Zanthoxylum schinfolium)는 limonene, citronellal, phellandrene 등의 다양한 유효물질을 함유하고 있으며 유효성분들로부터 유래되는 항산화 활성과 항암활성, 항균활성 등의 효능을 지니는 것으로 보고된바 있다. 본 연구의 생물전환 공정에 사용된 유산균들은 전통 발효식품으로 알려진 다양한 젓갈류로부터 분리하였으며, 16S rDNA 염기서열 분석을 통해 유전학적 특성을 확인하였다. 또한 확보된 유산균들을 사용하여 산초(전북 진안군) 분말의 발효공정을 수행하였으며, 산초의 최적 추출조건을 선정하고 추출물을 제조하여 생물전환 공정 전 후 활성의 변화추이를 관찰하였다. 추출물의 활성평가는 항산화 효능 및 유효성분 함량을 평가하기 위하여 DPPH radical scavenging activity와 total polyphenol 함량을 평가하고 세포주를 활용해 MTT assay, Nitric oxide(NO) 생성억제 효능을 확인하여 세포독성 및 항염증 활성을 확인하였다. 실험결과, 생물전환 공정에 사용할 유용 미생물을 확보하기 위한 실험을 통해 다양한 젓갈류에서 다양한 미생물을 확보할 수 있었으며 약 16종의 유산균을 분리하였다. 분리된 미생물을 사용하여 산초 분말의 생물전환 공정을 실시한 결과, 5종의 유용미생물 처리에서 무처리 대비 DPPH radical 소거능 및 polyphenol 함량이 유의적으로 증가됨을 확인할 수 있었다. 그 중 가장 높은 활성을 나타내는 균주를 16S rDNA 염기서열 분석을 통해 확인한 결과 Weissella confusa D1로 확인되었다. 선별 균주를 활용한 생물전환 공정 후 항산화 활성은 대조군 대비 약 120%의 활성을 나타냈으며, polyphenol의 함량은 약 126%로 증가하는 것을 확인할 수 있었다. 더 나아가 생물전환 공정 후 산초추출물의 세포독성은 처리전과 비교하여 월등히 감소하는 경향을 확인할 수 있었으며, 항염효능 또한 증가하는 경향을 나타내는 것이 확인되었다.

• Clean Technology
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• v.17 no.2
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• pp.117-123
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• 2011

In this study, evaluation tests for cleaning performance of various cleaning agents and selection of optimal ultrasonic cleaning parameters were executed to develop an efficient cleaning process in remanufacturing of laser copy machine. Cleaning performance tests were executed with 8 cleaning agents (A~H) to remove the contaminants of oil-ink, toner particles, and shoe polish. Physical properties and foamability tests were also applied. For 3 types of contaminants, cleaning agent G showed superior cleaning performance compared to agent A which has being used at a remanufacturing of laser copy machine in Korea. With cleaning agents selected in pre-tests, ultrasonic cleaning tests were executed to remove real contaminants on the parts of used digital laser copy machine parts. Cleaning agent G at 28 kHz ultrasonic frequency showed faster cleaning performance compared to agent A and other frequencies. The productivity and economic efficiency in remanufacturing of laser copy machine are expected to increase by adapting agent G and 28 kHz frequency at ultrasonic cleaning process.

• Korean Journal of Construction Engineering and Management
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• v.12 no.1
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• pp.3-12
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• 2011

Technology based civilization has made a sustained advancement, resulting in economic growth and material prosperity. The outcome was the beginning of environmental destruction. Especially, in regard to construction, it has been recognized as a key culprit for pollution. As such, the construction industry has recently shown interest in the environment, as it has been applying environment friendly method of construction and reducing wastes. As the number of old common housing increases in our country, reconstruction and remodeling are implemented as a means of improvement. However, it can be said that remodeling is the inevitable option because of cost and environmental problems associated with reconstruction. As part of its feature, remodeling work is preceded by removal work. And, removal work inevitably creates construction wastes. Treatment of wastes that takes into consideration environmental aspects is important and for this, removal work that is based on environment friendly remodeling to ensure selective separation must be implemented. Yet, a removal work based on environment friendly remodeling has a lower level of output compared to existing methods. Because remodeling work by its nature has a post construction work which proceeds after it, securing work efficiency is important as the removal work is a critical path activity. Thus, the present study improves the work process of a removal work that is based on environment friendly remodeling so that it becomes a work process that includes work efficiency. For this, as a case study, old common housing has been selected, and a TACT process has been developed which is based on data acquired from environment friendly removal work. And, this study develops an optimal TACT process which is based on environment friendly remodeling by conducting a simulation for a 15 floor apartment.

• 한국생물공학회:학술대회논문집
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• 2003.04a
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• pp.356-360
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• 2003

Hundreds of microbial species were isolated and collected from dye-processing wastewater. Among them three species (named as RA1, RA2, and YA1) showed excellent ability of dye degradation. Especially, YA1 species could remove 53% of dye in 24 hours. To find optimal growth conditions for the isolated species, further research is going on.

• Proceedings of the KAIS Fall Conference
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• 2009.05a
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• pp.550-553
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• 2009

본 연구에서는 천연염색 실크직물의 배색 시스템을 활용하여 배색 감성에 기반한 패션의류 제품을 개발하고자 하는 목적으로 천연염색 업계에서 즉시 활용 가능한 국내외 시판용 천연염재를 대상으로 균일화된 기계화 염색 공정을 통해 의류용 실크직물에 다양한 천연염색 색채를 발현한 후 대표 단색군을 선별하여 동일톤과 유사톤의 원리를 이용한 3배색 데이터 베이스를 구축하였다. 나아가 현대적이면서 한국적인 텍스타일 모티브를 개발하여 3배색 데이터를 적용한 배색 디자인을 제시하고, 이들 모티브와 배색 디자인이 적용된 패션 의류 아이템들을 제작하여 천연염색을 활용한 실크직물의 배색 감성을 적용한 현대적 하이-프리미엄 패션의류제품을 제안하였다.

• Journal of Korean Institute of Industrial Engineers
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• v.26 no.3
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• pp.200-205
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• 2000

An economic process monitoring procedure is presented using a surrogate variable for the case where performance variable is dichotomous. Every item is inspected with a surrogate variable and determined whether it should be accepted or rejected. When an item is rejected, the previous number of consecutively accepted items is compared with a predetermined number r to decide whether there is a shift in fraction nonconforming or not. The conditional distribution of the surrogate variable given the performance variable is assumed to be normal. A cost model is constructed which includes costs of inspection, misclassification, illegal signal, undetected out-of-control state, and correction. Methods of finding the optimum number r and screening limit are provided. Numerical studies on the effects of cost coefficients are also performed.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.150-151
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• 2019

리튬 이온 배터리가 전기 자동차 및 다양한 어플리케이션에 적용됨에 따라 폐배터리의 수요 또한 증가하고 있다. 내부 화학적 상태가 상이한 배터리의 전기적 특성실험을 통해 파라미터를 선정할 수 있으며 전기적 특성 실험 전 후의 시간차에 따른 파라미터 변화를 반영하는 것이 필수적이다. 제조 공정과정의 파라미터의 측정값과 특성실험 후의 파라미터 재측정값을 비교함으로써 이를 3-D Kmeans Clustering 알고리즘에 반영하여 더욱 정밀한 셀 선별을 실시하였다.