• Journal of the Korea Computer Industry Society
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• v.2 no.9
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• pp.1163-1174
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• 2001

A general goal of the ATM(Asynchronous Transfer Mode) network is to support connections across various networks. ABR service using EPRCA(Enhanced Proportional Rate Control Algorithm) switch controls traffics in ATM network. EPRCA switch, traffic control method uses variation of the ACR(Allowed Cell Rate) to enhance the utilization of the link bandwidth. However, in ABR(Available Bit Rate) service, different treatments are offered according to different RTTs(Round Trip Times) of connections. To improve the above unfairness, this paper presents ABR DELAY mechanism, in which three reference parameters for cell delay are defined, and reflect on the messages of RM(Resource Management) cells. To evaluate our mechanism, we compare the fairness among TCP connections between ABR DELAY mechanism and ABR RRM mechanism. And also we execute simulations on a simple ATM network model where six TCP connections and a background traffic with different RTTs share the bandwidth of a bottleneck link. The simulation results, based on TCP goodput and efficiency, clearly show that ABR DELAY mechanism improves the fairness among TCP connections.

• Journal of Microbiology and Biotechnology
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• v.9 no.6
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• pp.757-763
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• 1999

The metal specificity of D-xylose isomerase from Streptomyces rubiginosus was examined by site-directed mutagenesis. The activation constants for metal ion ($Mg^{2+},{\;}Mn^{2+},{\;}or{\;}Co^{2+}$) of wild-type and mutant enzymes were determined by titrating the metal ion-free enzyme with $Mg^{2+},{\;}Mn^{2+},{\;}and{\;}Co^{2+}$, respectively. Substitutions of amino acids either on coordinated or around the M2 site (His-22O, Asn-185, Glu-186, and Glu-221) dramatically affected the activation constants as well as activity. A decrease of metal binding affinity was most significant in the presence of $Mg^{2+}$. When compared with the wild-type enzymes, the binding affinity of H220S and Nl85K for Mg^{2+} was decreased by 10-15-fold, while the affinity for $Mn^{2+}{\;}or{\;}Co^{2+}$ only decreased by 3-5-fold. All the mutations close to the M2 site changed their metal preference from $Mg^{2+}{\;}to{\;}Mn^{2+}{\;}or{\;}Co^{2+}$. These altered metal preferences may be caused by a relatively weak binding affinity of $Mg^{2+}$ to the enzyme. Thermal inactivation studies of mutants at the M2 site also support the importance of the M2 site geometry for metal specificity as well as the thermostability of the enzyme. Mutations of other important groups hardly affected the metal preference, although pronounced effects on the kinetic parameters were sometimes observed. This study proposes that the metal specificity of D-xylose isomerase can be altered by the perturbation of the M2 site geometry, and that the different metal preference of Group I and GroupII D-xylose isomerases may be caused by nonconserved amino acid residues around the M2 site.

• Journal of Advanced Navigation Technology
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• v.16 no.1
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• pp.96-102
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• 2012

The goal of mobile internet system is to provide a high-data-rate, low-latency and optimized packet radio access technology supporting flexible bandwidth deployments. Therefore, network architecture is designed with the goal to support packet-switched traffic with seamless mobility, quality of service and minimal latency. An important requirement for the mobile internet system is improved cell-edge BER performance and data throughput. This is to provide some level of service consistency in terms of geographical coverage as well as in terms of available data throughput within the communication coverage area. In a cellular system, however, the signal to interference plus noise power ratio gap between cell-center and cell-edge users can be of the order of 20 [dB]. The disparity can be even higher in a communication coverage limited cellular system. This leads to vastly lower data throughputs for the cell-edge users relative to cell-center users creating a large QoS gap. This paper proposes a analytical approach that tries to reduce inter-cell interference, and shows the SIR and BER performance according to the OFDM system parameters in mobile Internet environment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.557-560
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• 2013

MANTET(Mobile Ad-Hoc Networks), which is configured and operated by each terminals with no support of communication infra-structures, is recently expanded its application fields from terrestrial communications to underwater environments with technical advances of Wi/Fi and minimized portable terminals. Underwater sensor network, undersea environment explorations and probes, information transmission for underwater area, etc., is typical application fields of underwater MANET. Especially, Performance measurement and analysis on this application fields is one of important research area and base of design, implementation and operation for underwater MANET. However, the research results are focued on various transmission parameters on network level, and its objects of analysis are also performance of network level. In this paper, transmission performances for application levels are measured and analyzed for user levels on underwater MANET. In this study, voice traffic is assumed as object application traffic, computer simulation which is based on NS-2 having additional implemented functions for underwater communications is used. on some defined scale of MANET, transmission performances according to varying traffic environments are measured and analyzed, operation conditions on underwater MANET is suggested with the analysis.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.19 no.2
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• pp.128-135
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• 2007

In response to anthropogenic global warming due to a buildup greenhouse gas, the effect of the air temperature on water temperature has been noticed. Therefore, effects have been made to build an air/water temperature relationship at three study regions using the data collected by the Ministry of the Maritime Affairs and Fisheries (MOMAF). The air/water relationship varies with time-scale and weekly time-scale was chosen for the study. The data were fitted to the S-shaped non-linear relationship, and the parameters for the S-curve were derived using a single-criteria multi-parameter optimization scheme. Separate regression curves were fitted to consider seasonal hysteresis at the Masan site. The study results support the S-shaped non-linear relationship is the best fit for the air/water relationship at the Korean coastal zone. This study will contribute to determine the future policy regarding water quality and ecosystem for the decision-driving organization.

• Korean Journal of Pharmacognosy
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• v.17 no.3
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• pp.248-254
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• 1986

Effects of vinblastine(VLB) and vincristine(VCR) on cell-mediated immunity(CMI) were studied with the microcytotoxicity test(MCT) after normal or pre-sensitized Balb/c mice had been treated in vivo with a combination of two different doses of VLB or VCR(single dose of 20% and 60% $LD_{50}$, i.p.) at different times (from day -6 to day +4) plus allo-transplantation antigen(allo-TA, cells from C3H mice at day 0). The results were that $LD_{50}$ of VLB for female Balb/c mouse was 7.3mg/kg body weight (i.p.) and $LD_{50}$ of VCR was 4.3mg/kg body weight and that VLB and VCR acted as immunosuppressive agents on the primary CMI when administered after allo-TA(antigen-drug-phase), but showed no effect when administered prior to allo-TA(drug-antigen-phase). Change of doses of VLB and VCR(20% $LD_{50}$, 60% $LD_{50}$) caused quantitative or qualitative variations in the immunomodulating effects of these two drugs. Neither VLB nor VCR had any immunomodulating effect on the secondary CMI. Lastly, the results support that the four parameters (type of drug, sensitization status, time of drug treatment in relation to antigen injection, and drug dosis) are significant for the effects of the VLB and VCR on the CMI, and that VLB and VCR may inhibit the proliferation of antigen-stimulated T effector lymphocytes but not memory-cytotoxic T lymphocytes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.7
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• pp.667-672
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• 2016

This study presents results of an experimental investigation of the laser-arc, hybrid, butt welding process of SS400 structural steel. Welding parameters including laser power, welding current and speed were varied in order to obtain one-pass, full-penetration welds without defects. The conditions that resulted in optimal beads were identified. After welding, hardness measurements and microstructure observations were carried out in order to study weld properties. The mechanical properties of both the base material and welded specimen were compared based on the results of tensile strength measurements. The yield and tensile strengths were found to be similar.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.16 no.2 s.107
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• pp.163-168
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• 2006

The PWR Nuclear Fuel assembly consists of more than 250 fuel rods that are supported by leaf springs in the cells of more than 10 Spacer Grids (SG) along the rod length. Since it is not easy to conduct mechanical tests on a full-scale model basis, the small-scaled rod bundle $(5\times5)$ which is called partial fuel assembly is generally used for various performance tests during the development stage. As one of the small-scaled tests, a flow test should be carried out in order to verify the performance of the spacer grid to obtain the Flow-Induced Vibration (FIV) characteristics of the scaled fuel assembly over the specified flow range. A vibration test should be also performed to obtain the modal parameters of the assembly prior to the flow test. In this study, we want to develop the estimation procedure of the damping ratio for the scaled test assembly. For the damping factor of the partial fuel assembly and the grid cage at the first vibration mode, as one of the vibration tests, a so-called pluck testing has been performed in air as a preliminary test prior to in-flow damping measurement test. Logarithmic decrement method is used for calculation of the damping ratio. Estimated damping ratio of the partial fuel assembly is about $0.7\%$ with reasonable error of $2\%$ for the previous results. Nonlinear behavior of the partial fuel assembly might be stem mainly from the rod-grid support configuration.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.4
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• pp.429-435
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• 2009

This paper propose color assessment method using HSI model to evaluate quantitative quality of mosaic images by aerial digital frame camera. Firstly, we convert RGB color into HSI model and we extract six pixel information of S and I corresponding to H from adjacency image by using HSI model. Secondly, a method to measure similarity and contrast is proposed and performed for assesment of observation regarding adjacency images. Through these procedure, we could generate four parameters. We could observe that both of the evaluation results by proposed method and the evaluation results by visual were almost similar. This facts support that our method based on several formula can be an objective method to evaluate a quality of mosaic images itself.

• Journal of the Korean Society of Physical Medicine
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• v.2 no.2
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• pp.243-250
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• 2007

Purpose : Shoulder subluxation is a very common problem in patients with hemiplegia with stroke. Prevention of the low tone subluxed shoulder has been an issue for physical therapists working with neurological patients for many years. Methods : This study reviewed the literature to definite the management and a cause of shoulder subluxation with hemiplegia patients after stroke. Various modalities have been suggested for realigning the glenohumeral joint, but their use is controversial. The purpose of this paper is to review critically the evidence base in order to inform the clinical decision-making process for physiotherapists working in neurology. Results : Literature has identified supports, strapping and functional electrical stimulation(FES) in the management of low tone shoulders. Following review of this evidence it is suggested that there is a lack of reliable and valid research evidence on which to base conclusions. The modalities with the best supporting evidence for realigning the low tone subluxed glenohumeral joint are the triangular sling, Harris hemi sling and the Rolyan humeral cuff used in a standing position and the lap board and arm trough while the patient is sitting. However, due to soft tissue adaptation with associated lack of movement, over-correction and the need for careful patient positioning these supports need to be evaluated for each patient and should be used only in appropriate situations. Conclusion : Similarly, there is a lack of evidence on the effects of long-term use to this equipment. Electrical stimulation is also thought to have potential in the treatment to subluxed low tone shoulders but additional research is required to clarify the parameters for use and the long-term effects of these forms of management.