• Journal of Microbiology and Biotechnology
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• 제9권6호
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• pp.695-703
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• 1999

We have studied the stereospecificities of various pyridoxal 5'-phosphate (PLP) dependent enzymes for the hydrogen transfer between the C-4' of a bound coenzyme and the C-2 of a substrate in the transamination catalyzed by the enzymes. Stereospecificities reflect the structures of enzyme active-sites, in particular the geometrical relationship between the coenzyme-substrate Schiff base and the active site base participating in an $\alpha$-hydrogen abstraction. The PLP enzymes studied so far catalyze only a si-face specific (pro-S) hydrogen transfer. This stereochemical finding suggests that the PLP enzymes have the same topological active-site structures, and that the PLP enzymes have evolved divergently from a common ancestral protein. However, we found that o-amino acid aminotransferase, branched chain L-amino acid aminotransferase, and 4-amino-4-deoxychorismate lyase, which have significant sequence homology with one another, catalyze a re-face specific (pro-R) hydrogen transfer. We also showed that PLP-dependent amino acid racemases, which have no sequence homology with any aminotransferases, catalyze a non-stereospecific hydrogen transfer: the hydrogen transfer occurs on both faces of the planar intermediate. Crystallographical studies have shown that the catalytic base is situated on the re-face of the C-4' of the bound coenzyme in o-amino acid aminotransferase and branched chain L-amino acid aminotransferase, whereas the catalytic base is situated on the si-face in other aminotransferases (such as L-aspartate aminotransferase) catalyzing the si-face hydrogen transfer. Thus, we have clarified the stereospecificities of PLP enzymes in relation with the primary structures and three-dimensional structures of the enzymes. The characteristic stereospecificities of these enzymes for the hydrogen transfer suggest the convergent evolution of PLP enzymes.

• 한국경제지리학회지
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• 제15권2호
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• pp.332-342
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• 2012

본 연구는 합리적 버스 환승체계 구축을 위한 버스정류장의 환승센터로서의 유형 구분에 목적을 두고 있다. 이 분야 기존 연구는 주로 버스정류장 이용 수요의 특성과 버스정류장을 역세권으로 보았을 때 주변의 토지이용 특성을 확인하고, 이를 근거로 정류장의 유형을 구분한 후 구분된 유형들 각각의 특성을 요약하는 방식으로 진행되었다. 이러한 전통적 역세권 연구들의 공통적인 문제점은 대표적 연구 변수인 토지이용 특성과 정류장 이용 특성 등 횡단면적 snapshot의 특성만을 고려하여 환승의 본질인 통행 연계의 detail을 확보하지 못한다는 데 있다. 이에 본 연구에서는 환승통행 발생 정류장의 기능 구분을 위해 통행연계 변수로서 교통수단연계, 경유지연계, 이용시간연계 등의 변수 값이 각 정류장이 환승센터로서의 특성을 고려할 때 어느 정도와 방향인지를 확인토록 한다. 이를 위해 2009년 4월 20일 월요일 하루 동안 경기도 버스에 승하차한 통행 샘플을 분석하였다. 분석 결과 버스정류장은 연계성 관련 변수를 기준으로 비교적 뚜렷한 구분이 가능하였다. 이러한 결과는 환승센터 입지 선정이나 설계에 유용한 정보를 줄 것으로 기대된다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2021년도 춘계학술대회
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• pp.157-158
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• 2021

공급망의 빅데이터는 주로 네 가지 측면에서 발생된다. 하나는 생산 장비 품질 데이터, 계획된 조달 데이터, 제품 데이터 등과 같은 공급망에서 기업의 제품 가치 이전 과정에서 불가피하게 생성되는 관련 데이터이고, 두 번째는 공급망에 있는 다양한 회사의 ERP 데이터에서 파생된다. 세 번째는 고객의 전자 상거래 데이터이고 마지막은 외부 또는 수동으로 입력한 데이터의 데이터이다. 따라서 본 연구를 통해서 공급망 운영 과정에서 재고를 예측하고 제어하기 위해 타사 데이터 서비스 센터 분석 및 데이터 마이닝. 그것은 여러 측면에서 전체 공급망에 혁신과 관리 기술 및 사고방식의 변화를 가져오고 마침내 전체 공급망의 재고 조정 및 제로 재고 목표를 달성하게 된다.

• 한국수정란이식학회지
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• 제15권3호
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• pp.219-230
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• 2000

This study was carried out to determine the factors on achieving good viability of embryos biopsied fur sexing, to investigate pregnancy rate following embryo transfer(ET) with sexed embryos, and to confirm the accuracy for the calves bort following ET with sexed embryos by polymerase chain reaction(PCR). To investigate viability of Hanwoo embryos after biopsy for sexing, fresh and frozen/thawed embryos were biopsied according to different developmental day of blastocysts, different stage of blastocysts, and different biopsy grade and the embryos themselves were incubated for 2 hours in TCM199 after microsection to be evaluated morphologically for recovery as blastocyst. The results obtained were as follows : 1. The rate of oocytes cleaved in vitro and the rate of blastocyst of the cleaved oocytes were 52.5% and 21.6%, respectively. The rate of blastocyst on day 8 was 11.2%, denoting the highest rate during whole culture period posterior to in vitro fertilization(IVF) 2. After biopsy for sexing, the viability rate of blastocyst on day 7, 8 and 9 was 75.0%, 88.4%, and 100.0%, respectively and the viability of early, mid, and expanded blastocyst after biopsy was 75.0%, 88.9%, and 91.1%, respectively The viability rate of fresh and frozen/thawed embryos was 89.9%, 71.4%, respectively. And the viability of expanded, hatching, and hatched blastocyst of frozen/thawed embryos was : 75.0%, 75.0%, and 50.0%, respectively. The viability of embryos according to biopsy grade of 10∼20%, 21∼30%, and 31∼40% was 85.7%, 91.5%, and 71.4%, respectively. 3. Pregnancy rate after transfer with biopsied embryo between flesh and frozen/thawed embryos was 22.6% and 20.0%, respectively. 4. In comparison between sex by PCR method and sex of calves born after embryo transfer, the accuracy of sex deterimination was 92.3% (12/13).

• Journal of Radiation Protection and Research
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• 제16권2호
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• pp.55-65
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• 1991

벼, 콩, 상치, 당근, 호박의 가식부위에 대하여 몇 가지 토양에 있어서 토양-작물체간 Mn-54, Co-60, Zn-65, Cs-137의 전이계수를 포트 재배에 의한 방사성 추적자 흡수실험을 통하여 조사하였다. 핵종간 전이계수는 거의 모든 경우 Zn-65>Mn-54>Cs-137>Co-60의 순이었다 중이 벼보다 전반적으로 한 자리 정도 높은 값을 보였고 채소류의 경우에는 대체로 상치에서 가장 높고 호박에서 가장 낮은 값을 보였다. 강산성 토양에서는 약산성 토양에서보다 전이계수가 철센 높았다. 본 조사결과에 입각하여 한국인의 섭식경로 피폭선량 평가에 이용하기 위한 각 핵종의 전이계수치가 작물별로 제안되었다.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.322-322
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• 2006

Well-defined poly(N-vinylcarbazole), poly(NVC), was synthesized by macromolecular design via interchange of the xanthate (MADIX)/reversible addition-fragmentation chain transfer (RAFT) polymerization in the presence of a suitable xanthate-type chain transfer agent (CTA). Good control of the polymerization was confirmed by the linear first-order kinetic plot, the molecular weight controlled by the monomer/CTA molar ratio, linear increase in the molecular weight with the conversion, and the ability to extend the chains by the second addition of the monomer. Star polymers having various architectures were also synthesized using this technique.

• 대한화학회지
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• 제16권1호
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• pp.46-49
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• 1972

Divinylbenzene의 중합에 있어서 gel point에서의 점도가 일정하다는 가정을 사용하여 점도 방정식, 점도와 분자량과의 관계식 및 사슬이동 방정식 등의 상호 관계를 연구하였다. 중합도 대신에 Gel time을 측정하여 사슬이동상수 $C_{tr}$을 계산해 낼 수 있는 새로운 식을 제안 하였다.

• Macromolecular Research
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• 제13권3호
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• pp.236-242
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• 2005

Three dithioester-derived carboxyl acid functionalized RAFT(reversible addition-fragmentation chain transfer) agents, viz. acetic acid dithiobenzoate, butanoic acid dithiobenzoate and 4-toluic acid dithiobenzoate, were used in the RAFT bulk polymerization of styrene, in order to study the effects of the R-group structure on the living nature of the polymerization. By conducting the polymerization with various concentrations of the RAFT agents and at different temperatures, it was found that the R-group structure of the RAFT agents plays an important role in the RAFT polymerization; the bulky structure and radical stabilizing property of the R-group enhances the living nature of the polymerization and allows the polymerization characteristics to be well controlled.

• Bulletin of the Korean Chemical Society
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• 제31권10호
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• pp.2943-2948
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• 2010

Silica monolith powders were prepared by a new procedure where ground powders of proper size distribution were obtained without sieving. An initiator was attached to this ground monolith and polystyrene was bound by reversible addition-fragmentation chain transfer polymerization to give a new stationary phase. The separation efficiency of this phase was found better than that of the polystyrene bound phase based on conventional silica particles and that of the C18 bound silica monolith powders.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2002년도 춘계학술대회논문집
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• pp.89-99
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• 2002

Since 1996, the document exchange method by EDI has been introduced in port and logistics industries in Korea to enhance the declaration activities to the Pusan Port Authority and Customs. In spite of these efforts, users such as shipping companies, shipping agents, and freight forwarders have complained the inconvenience of using EDI systems. The major reasons can be summarized as follows: repetitional EDI transfer, too much transfer time, inconvenient EDI software, and problems on message receiving confirmation. Furthermore, EDI has been used only for transmitting messages. To solve these problems, this study has adopted the integration system by applying the concept of SCM to logistics system by XML/EDl. In the view of SCM, the existing EDI has some problems because its role is only to transmit the messages. This paper is to suggest how current EDI systems in Port and logistics sector has to be chanced by Introducing SCM. The integration system gives us such advantages as accuracy of cargo data, integration of processes among firms, and keeping the trace of cargo.