• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.38
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• pp.9-15
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• 1996

The purpose of this research is to develop a method for part-machine grouping subject to production and management constraints. In the proposed integer programming model, minimization of operating and material-handling costs are considered as an objective function. The model allows one to recognize the existing parts and machines into disaggregated cells. New constraints are introduced in the model to resolve unbalancing capacity and bottleneck problems. It is found that this approach could have a better flexibility on cell size design for mote alternatives than conventional methods. Experimental grouping and comparison studies with ROC algorithm are given for evaluation purposes.

• Journal of Microbiology and Biotechnology
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• v.14 no.1
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• pp.1-14
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• 2004

More than twenty years have passed since the approval of the first recombinant DNA product for therapeutic use (recombinant human insulin, 1982). However, the biotechnology industry is still facing a shortage of manufacturing capacity due to the increasing demand of therapeutic proteins. This demand has prompted the search for a growing number of biological production systems but, nevertheless, the Gram-negative bacterium Escherichia coli remains one of the most attractive production hosts. This review highlights the most important features and developments of plasmid vector design, emphasizing the different reported strategies for improving the expression and secretion of heterologous proteins using the cellular machinery of E. coli.

• Proceedings of the KSAR Conference
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• 2001.10a
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• pp.3-4
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• 2001

Normal cells proliferate generally a limited number doublings in culture and only rarely have they been shown to overcome cellular senescence and crisis stages, and immortalize spontaneously. I have established a number of non-chemically and non-chemically immortalized embryo fibroblastic (EF) cell lines in continuous cell culture. These include the spontaneously immortalized cell line, DF-1 and several immortal EF cell lines derived from various embryonic tissues. I have previously demonstrated that all of the immortal EF cells established have rapid cell proliferation capacity compared to primary EF cells, presumably due to the deregulation of cell cycle regulators such as p53, E2F-1 and the numerous cyclins. DF-1 cells, in particular, were shown to proliferate more rapidly under normal culture conditions compared to other immortal EF cells, implicating other mechanisms may be important for regulating their growth. The possible mechanism(s) underlying the accelerated growth of DF-1 cells will be addressed in this study. (omitted)

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.7
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• pp.1448-1458
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• 1997

In this paper the reverse link of the GLOBALSTAR-the representative CDMA LEO satellite system and LEO mobile satellite channel are developed by the SPW software simulation tool. And the performance of the system is evaluated. GLOBALSTAR is designed to give cellular-type service to hand-held user terminals through a constellation of 48 LEO satellites in circular orbites with 1414 Km altitude. Since LEO mobile satellite system communicates with mobile unit, it is suffered from severe multipath fading and shadowing. The fast mobility of LEO satellites makes the channel condition time vering. So, the LEO mobile satellite channel is different from land mobile channels. In this unique LEO satellite channel, it is shown that the performance of the GLOBALSTAR reverse link is varied according to the elevational angle, but this variation is overcome by satellite path diversity.

• Archives of Pharmacal Research
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• v.13 no.4
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• pp.355-358
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• 1990

In order to investigate the cellular mechanisms of hypoglycemic of brazilin, hepatocyte monolayer culture was introduced and, glycogen synthesis rate and insulin binding were measured as parameters. Glycogen synthesis and insulin sensitivity were remarkably augmented by the treatment of brazilin. Brazilin slightely increased insulin binding. Scatchard analysis revealed that this increase in insulin binding was not due to increase in the binding capacity but in binding affinity. These results suggest that the augmentation of hepatic glycogenesis and insulin sensitivity by brazilin may play an important role in the improvement of hyperglycemia.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.151-153
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• 2002

Mobile handhold devices such as PDA(Personal Digital Assistant) and Cellular Phone are more and more popular for personal web surfing. But today, most mobile handheld devices have relatively poor web browsing capability because of the small bandwidth of wireless connection, the small speed of CPU, the small capacity of RAM and Flash ROM, the small display size of LCD and the short lifecycle of battery. Users have to endure bigger communication latency than Desk PC's one because of these factors. In this paper, we propose an effective pre-refresh mechanism for handheld device's embedded web browser so as to make user's web surfing faster. The experiment was done using the simulator designed by ourselves and the experiment result demonstrates the proposed mechanism has a good performance to make web surfing faster.

• ETRI Journal
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• v.28 no.2
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• pp.227-230
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• 2006

There has been a growing need for increased capacity in cellular systems. This has resulted in the adoption of the code division multiple access (CDMA) system as a multiple channel access method. Thus, it is important to obtain the phase offsets of binary codes in the CDMA system because distinct phase offsets of the same code are used to distinguish signals received at the mobile station from different base stations. This letter proposes an efficient algorithm to compute the phase offset of a binary code in the CDMA system through the use of the basic facts of number theory and a new notion of the subcodes of a given code. We also formulate the algorithm in a compact form.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.6A
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• pp.903-912
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• 2001

본 논문에서는 계층적 구조를 가진 CDMA 셀룰러 시스템에서 여러 가지 자원 공유 방식들 중 주파수 공유 방식과 주파수 분할 방식의 용량을 순방향 링크에 대해 분석 비교하였다. 용량 분석은 마이크로셀 반경 및 마이크로셀 클러스터의 위치 및 매크로셀에 대한 마이크로셀의 전력 비를 고려하여 몬테카를로 시뮬레이션을 통해 수행하였다. 시뮬레이션 결과로부터 각각의 자원 공유 방식들에 대해 이러한 영향들을 분석하였고, 일반적인 설계 접근방식을 제시하였다. 또한 자원공유방식들의 성능을 용량평면도를 통해 비교하였다. 결과를 요약하면, 계층적 구조를 가진 CDMA 셀룰러 시스템에서 스펙트럼 공유 방식을 적용할 경우 순방향 링크의 용량을 최대로 하기 위해서는 마이크로셀 클러스터가 매크로셀의 중심으로부터 멀리 배치하고, 마이크로셀의 반경을 작게 하는 것이 바람직함을 알 수 있었다.

• ETRI Journal
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• v.34 no.3
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• pp.297-307
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• 2012

A femtocell is a small cellular base station, typically designed for use in a home or small business. The random deployment of a femtocell has a critical effect on the performance of a macrocell network due to co-channel interference. Utilizing the advantage of a multiple-input multiple-output system, each femto base station (FBS) is able to form a cluster and generates a precoding matrix, which is a modified version of conventional single-cell block diagonalization, in a cooperative manner. Since interference from clustered-FBSs located at the nearby macro user equipment (MUE) is the dominant interference contributor to the coexisting networks, each cluster generates a precoding matrix considering the effects of interference on nearby MUEs. Through simulation, we verify that the proposed algorithm shows better performance respective to both MUE and femto user equipment, in terms of capacity.

• Molecules and Cells
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• v.37 no.4
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• pp.337-344
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• 2014

Adipose-derived stem cells represent a type of mesenchymal stem cells with the attendant capacity to self-renew and differentiate into multiple cell lineages. We have performed a microarray-based gene expression profiling of osteogenic differentiation and found that the transcription factor Sox11 is down-regulated during the process. Functional assays demonstrate that down-regulation of Sox11 is required for an efficient differentiation. Furthermore, results from forced expression of constitutively-active and dominant-negative derivatives of Sox11 indicate that Sox11 functions as a transcriptional activator in inhibiting osteogenesis. Sox11 thus represents a novel regulator of osteogenesis whose expression and activity can be potentially manipulated for controlled differentiation.