• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.455-460
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• 2006

Currently, the IETF group is working on service differentiation in the Internet. However, in wireless environments such as Ad-hoc networks, where channel conditions are variable and bandwidth is scarce, the Internet differentiated services are suboptimal without lower layers' support. The IEEE 802.11 standard for Wireless LANs is the most widely used WLAN standard today. 1t has a mode of operation that can be used to provide service differentiation, but it has been shown to perform badly. In this paper, we present a new service differentiation scheme for support QoS in the wireless IEEE 802.11, which is based on a multiple queuing system to provide priority of user's flow. We simulate and analyze the performance of our algorithm and compare its performance with the original IEEE 802.11b protocol. Simulation results show that our approach increases overall throughput in the MAC layer.

• Journal of Korean Neurosurgical Society
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• v.47 no.5
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• pp.338-344
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• 2010

Objective : This study assessed the safety and efficacy of one level unilateral laminotomy bilateral decompression (ULBD) with the placement of a device for intervertebral assisted motion (DIAM) compared with one level ULBD only in elderly patients with degenerative lumbar spinal stenosis (DLSS). Methods : A non randomized prospective analysis was performed on 16 patients who underwent one level ULBD with DIAM (Group A) and 20 patients with one level ULBD only (Group B) between February 2007 and March 2008. Radiographic imaging, visual analog scale (VAS) and MacNab outcome scale were obtained before and after surgery at a mean interval of 21 months (range 17-27 months). Results : The disc height, interpedicular distance, slip distance and segmental lordotic angle were similar between two groups. In the group A, there was no significant difference between the pre- and post-operative imaging in terms of the sagittal balance and disc height. Both groups showed significant improvement in the clinical outcomes. In addition, there was significantly less low-back pain in the group A than in the group B at the last follow up, while the clinical improvement of the leg pain and MacNab outcome scale showed no significant difference in the two groups. There were no major complications or DIAM associated complications. Conclusion : ULBD with DIAM is a safe and efficacious treatment for selective elderly patients with DLSS, particularly for relieving low back pain comparing to ULBD. ULBD with DIAM did not alter the disc height or sagittal alignment at the mean 21 months follow-up interval.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.9
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• pp.561-569
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• 2014

In wireless ad hoc networks, neighbor discovery is essential in the network initialization and the design of routing, topology control, and medium access control algorithms. Therefore, efficient neighbor discovery algorithms should be devised for self-organization in wireless ad hoc networks. In this paper, we propose a probabilistic neighbor discovery (PND) algorithm, which aims at reducing the neighbor discovery time by adjusting the transmission probability of advertisement messages through the multiplicative-increase/multiplicative-decrease (MIMD) policy. To further improve PND, we consider the collision detection (CD) capability in which a device can distinguish between successful reception and collision of advertisement messages. Simulation results show that the transmission probabilities of PND and PND with CD converge on the optimal value quickly although the number of devices is unknown. As a result, PND and PND with CD can reduce the neighbor discovery time by 15.6% to 57.0% compared with the ALOHA-like neighbor discovery algorithm.

• International Journal of Internet, Broadcasting and Communication
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• v.13 no.3
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• pp.178-192
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• 2021

File system forensics typically focus on the contents or timestamps of a file, and it is common to work around file/directory centers. But to recover a deleted file on the disk or use a carving technique to find and connect partial missing content, the evidence must be analyzed using cluster-centered analysis. Forensics tools such as EnCase, TSK, and X-ways, provide a basic ability to get information about disk clusters, but these are not the core functions of the tools. Alternatively, Sysinternals' DiskView tool provides a more intuitive visualization function, which makes it easier to obtain information around disk clusters. In addition, most current tools are for Windows. There are very few forensic analysis tools for MacOS, and furthermore, cluster analysis tools are very rare. In this paper, we developed a tool named FACT (Forensic Analyzer based Cluster Information Tool) for analyzing the state of clusters in a HFS+ file system, for digital forensics. The FACT consists of three features, a Cluster based analysis, B-tree based analysis, and Directory based analysis. The Cluster based analysis is the main feature, and was basically developed for cluster analysis. The FACT tool's cluster visualization feature plays a central role. The FACT tool was programmed in two programming languages, C/C++ and Python. The core part for analyzing the HFS+ filesystem was programmed in C/C++ and the visualization part is implemented using the Python Tkinter library. The features in this study will evolve into key forensics tools for use in MacOS, and by providing additional GUI capabilities can be very important for cluster-centric forensics analysis.

• Magazine of the Korea Concrete Institute
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• v.10 no.3
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• pp.117-124
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• 1998

본 연구는 고성능 철근콘크리트 보의 연성능력에 관한 실험이다. 실험변수로는인장철근비( )와 하중재하형태(1점가력과 2점가력)가 있다. 콘크리트의 실린더 압축강도가 800-900㎏/㎠, 슬럼프 20∼25㎝ 및 슬럼프 플로우가 60∼70㎝인 고성능 철근콘크리트 보의 휨 실험 결과,고성능 콘크리트는 일반강도 콘크리트보다 취성적인 성질을 나타냈으며, 이러한 성질은 고성능 콘크리트의 연성능력을 감소시켰다. 고성능철근콘크리트의 경우 등가응력블록 변수는 MacGregor블록이나 New Zealand 규준을 사용하는 것이 바람직하다. 또한, 극한 곡률을 구할때는 cu= 0.0042값을 사용하는 것이 타당하다고 사료된다. 고성능 철근콘크리트 보의 경우, 현재 ACI 규준의 철근비에서 허용하는 2 및 4 이상의 연성지수 확보는 각각 '/ 0.30 범위에서 정적하중 상태의 경우 철근비가 - '=0.60 b이하에서 가능하고 휨 부재의 모멘트 재분배를 위한 경우는 철근비를 - '=0.33 b이하로 낮추어야 할 것으로 판단된다.

• Language and Information
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• v.17 no.2
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• pp.29-50
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• 2013

Multiple Nominative Constructions (MNCs) and Multiple Accusative Constructions (MACs) have been some of the hottest and interesting topics in Korean syntax. This paper took empirical approaches to these constructions and examined native speakers' grammaticality judgements of these constructions. Though there are lots of previous studies on these constructions, Ryu (2010, 2013a, 2013b, 2013c) recently tried to unify MNCs and MACs into Multiple Case Constructions (MCCs) and to classify them into 16 types based on the semantic relations. This paper includes experiments which were performed on these 16 different types. The experiments were designed following Johnson (2008); and the native speakers' intuition was measured with two scales, numerical estimates and line drawing, though the latter was adopted in the actual analyses. Through the experiment, the following facts were observed: (i) the grammaticality of the MCCs varies depending on their semantic relations, (ii) MNCs were more grammatical than MACs if both constructions occurred in similar environments, and (iii) the sentences in some MAC types had much lower grammaticality than those in the others, as Ryu (2013b, 2013c) mentioned.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.6
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• pp.278-286
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• 2005

Recently, high-speed centrifugal turbo-compressors have been under intensive research and development. Since, compared to conventional compressors, high-speed centrifugal compressors hive numerous qualities such as simple structure, light weight small size, and high efficiency, etc. In cope with such industrial demands, a high-speed brushless DC motor for a 50-kW, 70-krpm turbo-compressor was developed based on a 2-D analytical method, of which design was verified using the FE analysis. A prototype machine was also fabricated and tested to confirm the analytical design. Preliminarily obtained experimental data using the prototype mac]line shows the validity of the analytical approach.

• Journal of Periodontal and Implant Science
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• v.29 no.2
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• pp.333-350
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• 1999

The modulation of leukocyte cell surface adhesion molecules may influence the development of cellular events that determine the course of the inflammatory process. Direct interaction between activated T cells and monocytes resulted in a large production of $IL-1{\beta}$ by monocytes. In this reactions, adhesion molecules play an important part, yet the role of them in Tmonocytes interaction remain unclear. This study was undertaken in an effort to elucidate, 1) the influence of 1.25(OH)$_2D_3-induced$ differentiation on the monocyte responsiveness to direct contact with T lymphocytes, and 2) the role of adhesion molecules on the T-monocyte direct interaction. Initially, I observed that direct contact of monocyte cell line THP-1 with stimulated fixed T cell line HuT78 markedly induces IL-1${\beta}$ production by THP-1. $IL-1{\beta}$ production was higher when THP-1 had been previously exposed to 1.25(OH)$_2D_3$ as compared to control, with ${\alpha}$- 1.25(OH)$_2D_3$ dose-dependent and exposure time-dependent manner. It was shown that 1.25(OH)$_2D_3$ also increased the expression of ${\beta}_2$ integrin adhesion receptor Mac-1(CD11b/CD18) dose- and timedependently, but did not increase the expression of human leukocyte antigen- D(HLA-D) and intercellular adhesion molecule-1(ICAM-1). The $IL-1{\beta}$ producing activity of THP-1 cells correlated well with the ability to induce the Mac-1 expression on THP-1 surface. Monoclonal antibody raised against relevant cell surface glycoproteins on THP-1 were tested for their ability to block the response of THP-1 to T cells. Antibody to Mac-1 only partially blocked $IL-1{\beta}$ production by THP-1, whereas antibodies to ICAM-1 and HLA-D did not. These data indicate that regulation of Mac-1 expression on THP-1 cells can alter the responsiveness of these cells to contact by activated T cells, however other unknown structures on the THP-1 cells may be involved in this process also.

• Current Research on Agriculture and Life Sciences
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• v.10
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• pp.125-135
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• 1992

Nine strains of xyl mutants that could not utilize xylose as a carbon source were isolated from E. coli JM109 by the treatment of NTG in order to investigate the regulation of xylose operon and to use recipient cells for the cloning of xylR gene. For the characterization of all isolated mutants, colony colors of all mutants on MacConkey-xylose and MacConkey-xylulose agar plate were observed for the utilization of xylose and xylulose, and the growth level and the activity of xylose isomerase and xylulokinase were determined in need. The isolated xylR/T mutants formed the white colony on MacConkey-xy-lose and MacConkey-xylulose agar plate. They did not detect the activity of xylose isomerase, and the activity of xylose isomerase was not restored in transformants of xylR/T mutant with pEX13 which contained xylA gene. xylR and xylT mutants were classified from xylR/T mutants depending upon the growth level in minimal medium. xylT mutants; DH13, DH121 and DH125 could grow a little in that medium, but xylR mutants; DH10, DH53, and DH60 could not grow that medium.

• Proceedings of the Korean Society of Developmental Biology Conference
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• 2003.10a
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• pp.119-119
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• 2003

분만후 젖소의 자궁내 미생물상을 조사하고 미생물로부터 분리한 Lipopolysaccharide를 적용하여 소의 번식효율 증진에 기여하고자 분만후 젖소의 도축장 유래 자궁을 채취하여 혐기적 상태에서 균분리 동정을 실시하였다. 균분리 동정을 위하여, 시료를 1cm$\times$1cm로 채취하여 혐기상태에서 거품이 생길 때까지 vortexing한 후 균액 300$\mu l$를 뽑아 혐기배지에 도말하였고 도말한 plate는 $37{\circ}C$ 혐기chamber에서 24시간 배양하였다. 혐기배지에서 자란 균의 colony를 따서 Mac, BHI+B, BHI 배지에 배양한 후 Gram stain을 실시하였다. BHI 배지에서 자란 균의 colony를 따서 BUA+B 배지에 계대배양하였고 BUA+B 배지에서 자란 균중에 가장 마지막으로 자란 균을 따서 An-IF에 넣고 탁도를 63%T로 맞춘 후 An micro plate에 100$\mu l$씩 분주하였다. 분주한 plate를 $37{\circ}C$ 혐기 chamber에서 20~24시간 동안 배양한 후 Biolog를 실시하였다. 시료의 UV측정을 위하여 Sonic Processor로 세포를 분쇄하였고 분쇄한 세포를 $4{\circ}C$에서 10,000rpm으로 10분간 원심분리한 후 상층액을 분리하여 0.45$\mu m$ 필터로 여과한 다음 여과액을 취하여 UV로 standard(E.coli O26 B6 LPS)와 sample(10배 및 20배 희석액)을 측정하였다. (중략)