PFG NMR Study of Intra-cellular Drug Uptake in Xenopus laevis Oocyte

홍관수,염규선,조지현,김은희,이철현,이상도,정재준 한국자기공명학회 2005 Journal of the Korean Magnetic Resonance Society Vol.9 No.1

Intra-cellular drug uptake in Xenopus laevis oocyte has been elucidated using localized MR spectroscopy (MRS) and PFG NMR techniques at a 600 MHz (Bruker, 14.1 T) NMR spectrometer. The localized MRS has been done with a home-made probe, and shows the intra-cellular uptake of nicotinamide. The self-diffusion of the molecule in Xenopus oocyte was obtained by PFG NMR technique. The measured data are well fitted with a linear combination of two exponential functions, which shows that there are two types of drug molecules, intra- and extra-cellular molecules. Diffusion coefficients of intra- and extra-cellular drug molecules are 3.7 × 10-11 m2/s and 6.4 × 10-10 m2/s, respectively. In the weighting factors there is shown that about 5% of drug molecule is inside the cells. These techniques can be used for drug screening in molecule-, cell-, and tissue-based preclinical test. 영어논문

다수요인을 가진 설비배치문제를 위한 유전알고리즘

洪寬洙 啓明大學校 産業經營硏究所 1997 經營經濟 Vol.30 No.2

SUMMARY The facility layout problem has the goal of locating departments in a floor to achieve the greatest efficiency in producing a product or service. This problem is usually formulated as the quadratic assignment problem(QAP). Traditionally, two basic approaches have been used to solve plant layout problems. One is a quantitative approach which tries to minimize material handling costs between departments. The other is a qualitative approach which considers subjective closeness ratings. Each approach has its oun set of advantages and disadvantages. Recently, work has been done to integrate the two approaches. However, the problem of finding optimal layout is hard and traditional approaches are not computationally feasible. In this paper, a genetic algorithm is presented for obtaining efficient layouts. To test the effectiveness of the heuristic. a set of examples previously used by various authors is solved and the results are compared to those from other known heuristics. The comparison indicates that the proposed method performs well for the classical test problems. The facility layout problem has the goal of locating departments in a floor to achieve the greatest efficiency in producing a product or service. This problem is usually formulated as the quadratic assignment problem (QAP). Traditionally two basic approaches have been used to solve plant layout problems. One is a quantitative approach which tries to minimize material handling costs between departments. The other is a qualitative approach which considers subjective closeness ratings. Each approach has its own set of advantages and disadvantages. Recently work has been done to integrate the two approaches. However, the problem of finding optimal layout is hard and traditional approaches are not computationally feasible. In this paper, a genetic algorithm is presented for obtaining efficient layouts. To test the effectiveness of the heuristic, a set of examples previously used by various authors is solved and the results are compared to those from other known heuristics. The comparison indicates that the proposed method performs well for the classical test problems.

기업간 의존도가 기업간 네트웍 성과에 미치는 영향

홍관수 啓明大學校 産業經營硏究所 2004 經營經濟 Vol.37 No.1

The purpose of this study is to examine the effects of collaboration and dependence between manufactures and their major suppliers on supplier network performance. This study hypothesizes relationships among collaboration, dependence and supplier performance. Findings indicate that all hypotheses in the model are significant. The result of this study indicates that the higher the degree of collaboration, the greater the benefit of buyer-suppler relationships. This research also supports the association between the degree of collaboration and performance is moderated by the degree of dependence. Therefore, the positive benefit decreases as the degree of supplier's dependence increases. Reasons for and implications of these observed relationships are discussed.

競爭力提高를 위한 生産情報시스템에 관한 硏究

洪寬洙 啓明大學校 産業經營硏究所 1992 經營經濟 Vol.25 No.1

과업불확실성과 컴퓨터 활용능력이 사용자 만족도에 미치는 영향

홍관수,이지우 啓明大學校 産業經營硏究所 2002 經營經濟 Vol.35 No.1

End users exhibit different computing abilities and behavior. Assessing individual's capabilities with respect to end user technologies is central to both research on end user computing(EUC) and management of EUC. The capability is composed of an individual's ability to creatively apply end user technologies. The study uses results from a survey of 233 users to test a structural model examining the hypothesized relationships among the following constructs: task uncertainty, finesse of user technologies, and decision satisfaction. The finding indicated that finesse of user technologies is the dominant factors affecting the success of EUC. Reasons for and implications of these observed relationships are discussed.

Blood Half-Life Study of Magnetic Fluorescent Silica Nanoparticles by Using MR T2 Relaxation Measurement: Long Circulating SPIO

홍관수,이규홍,정재준,고의관,김미현,신형선,김영남,이수형 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

Iron-oxide-based nanoparticles have been used as MRI contrast agents because of their T₂ and T*₂shortening effect properties. Recently, we developed a material consisting of magnetic and fluorescent silica-coated nano-particles (MFSNs) that incorporated rhodamine isothiocyanate (RITC). A commercial and conventional T2 contrast agent is coated with a hydrophilic polymer, like dextran or carboxymethyl dextran, to reduce bio-toxicity and to increase biocompatibility. In contrast, our MFSN is surface-modied with silica and polyethyleneglycol (PEG) to make it biocompatible and water-soluble. The MFSN has multi-modal magnetic and fluorescent properties. Therefore it can be used in confocal imaging, as well as magnetic resonance imaging (MRI). Various applications of this useful material in the biological and medical elds are strongly expected. For such applications, various physical and biological properties, like size, T2 relaxivity (r2) and blood half-life (T1=2), have to be studied in advance. In the present study, a transmission electron microscope (TEM) was used to measure the characteristics of MFSN. The average size of the MFSN particles is about 70 nm and the MFSN is categorized as a superparamagnetic iron oxide (SPIO). The r2 is ∽130 mM-1s-1 measured by using nuclear magnetic resonance (NMR) spin-spin relaxation, was much longer than for conventional SPIO agents as a result of PEGylation. This study is the first report of a ''long circulating SPIO" with a big hydrophilic size and a long blood half-life. In conclusion, MFSN, with its property of long circulation, may be a good agent for macrophage imaging at a specific inflammation site, for tumor imaging and for cellular labeling. Iron-oxide-based nanoparticles have been used as MRI contrast agents because of their T₂ and T*₂shortening effect properties. Recently, we developed a material consisting of magnetic and fluorescent silica-coated nano-particles (MFSNs) that incorporated rhodamine isothiocyanate (RITC). A commercial and conventional T2 contrast agent is coated with a hydrophilic polymer, like dextran or carboxymethyl dextran, to reduce bio-toxicity and to increase biocompatibility. In contrast, our MFSN is surface-modied with silica and polyethyleneglycol (PEG) to make it biocompatible and water-soluble. The MFSN has multi-modal magnetic and fluorescent properties. Therefore it can be used in confocal imaging, as well as magnetic resonance imaging (MRI). Various applications of this useful material in the biological and medical elds are strongly expected. For such applications, various physical and biological properties, like size, T2 relaxivity (r2) and blood half-life (T1=2), have to be studied in advance. In the present study, a transmission electron microscope (TEM) was used to measure the characteristics of MFSN. The average size of the MFSN particles is about 70 nm and the MFSN is categorized as a superparamagnetic iron oxide (SPIO). The r2 is ∽130 mM-1s-1 measured by using nuclear magnetic resonance (NMR) spin-spin relaxation, was much longer than for conventional SPIO agents as a result of PEGylation. This study is the first report of a ''long circulating SPIO" with a big hydrophilic size and a long blood half-life. In conclusion, MFSN, with its property of long circulation, may be a good agent for macrophage imaging at a specific inflammation site, for tumor imaging and for cellular labeling.

소동물 영상용 MRI 및 분자/세포영상 응용

홍관수 한국고분자학회 2009 고분자 과학과 기술 Vol.20 No.3

Bottleneck Behavior of 1H NMR Spin-lattice Relaxation in Ammonium Sulfate

홍관수,유인숙 한국자기공명학회 2002 Journal of the Korean Magnetic Resonance Society Vol.6 No.2

1H nuclear magnetic resonance (NMR) relaxations have been investigated in ammonium sulfate ((NH4)2SO4) powder at temperatures ranging from 102 K to 440 K. There is a bottleneck in the spin-lattice relaxation between the nuclear spin system and the hindered rotation of ammonium ions, which is certified by measuring the relaxation according to the initial condition of the spin system. For temperatures below 318 K the 1H spin-lattice relaxations have double-exponential behaviors with the exponent, n, having a value 2 > n > 1 initially and n = 1 after a long time. Above 318 K not only is the relaxation exponential initially with exponent n = 1, but it is a single-exponential over the entire time, resulting in one T1 value. The two types of NH4+ ions have different activation energies for hindered rotation, EaI = 0.27  0.02 eV and EaII = 0.12  0.01 eV, in the ferroelectric phase 영어논문

설비배치안 작성을 위한 유전 알고리즘에 관한 연구

홍관수,권성우 한국산업정보학회 1997 한국산업정보학회논문지 Vol.2 No.2

환경변화속도, 정보공유, 그리고 협력이 공급사슬의 성과에 미치는 영향

홍관수,정기웅 한국중소기업학회 2004 中小企業硏究 Vol.26 No.2

기업의 성과를 제고하기 위한 공급사슬관리의 중요성은 많은 연구자들에 의해 강조되었다. 그러나 환경변화속도가 구매자와 공급자간의 관계에 영향을 미치고 있음에도 불구하고 이에 대한 실증 연구와 기업간 통합의 핵심요소인 정보공유와 협력을 분리하여 각각이 성과에 미치는 영향에 대한 실증 연구는 많지 않은 실정이다. 따라서 본 연구의 목적은 공급사슬의 성과에 영향을 미치는 환경변화속도, 정보공유, 그리고 협력간의 관계에 대한 선행 연구들을 고찰하여 연구모형을 개발하고 가설들을 설정한 후 실증분석을 통해 이를 검정하는 것이다. 분석 결과 환경변화속도가 빠를수록 기업간 정보공유와 협력의 수준이 높은 것으로 나타났다. 특히 환경변화속도는 협력에 부정적인 영향을 준다는 기존 연구와는 달리 본 연구에서는 긍정적인 영향을 미치고 있어, 공급자와의 밀접한 협력은 환경변화의 불확실성을 감소시켜 주는 주요 수단이 될 수 있을 것으로 판단된다. 그리고 정보공유는 서로를 동반자로 인식하게 하여 협력에 긍정적인 도움을 주고, 정보공유와 협력은 성과에 긍정적인 영향을 미치는 것으로 나타났다. As the importance of supply chain management becomes increasingly recognized as a vital factor to company performance, researchers and practitioners alike are focusing their attention on this subject. The study's main object is to examine the impact of environmental clockseed, information sharing, and collaboration on supply chain performance. Reviewing the literature, we suggested a research model and developed five hypotheses to be tested. A sample of 102 manufacturing firms in several industries was used to empirically test these hypotheses. Major findings are: 1) environmental clockspeed has a positive impact on information sharing and collaboration, 2) information sharing has a positive impact on collaboration, 3) greater the information sharing and greater the collaboration between the buyer and its supplier, greater the performance. Inconsistent with prior research, the influence of environmental clockspeed on collaboration was positive. The result of the hypotheses test are detailed and implications for supply chain management discussed.