• Proceedings of the Korea Society for Simulation Conference
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• 1998.03a
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• pp.74-77
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• 1998

This paper presents a real design and implementation of an intelligent client-server equipment controller in computer-integrated manufacturing systems. An automated manufacturing process is commonly controlled by a number of PLC (Programmable Logic Controllers), which are attached to various equipments. A manufacturing cell consists of a set of equipments or workstation, which are also controlled by equipment or cell controller. We propose an intelligent equipment controller which has two function: one is to request (collect) an important information from each equipment and the other is to send the collected equipment information to the upper level controller (shop floor controller). Two-phase approaches are considered for the development of equipment client-server controller. The first events are generated virtually using computer simulation. Using the virtually generated activities, operating software of equipment server is developed. The second phase is to embed the virtually developed software (controller) into a real manufacturing system. The proposed methodology might be a novel design and implementation of a virtual simulator, which could be used for developing an intelligent equipment server.

• Computers and Concrete
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• v.4 no.4
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• pp.285-298
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• 2007

Corrosion of Reinforcement (rebar) is nondestructively estimated by the half-cell potential measurement. As is the case with other nondestructive testings (NDT), understanding of the underlying principles should be clarified in order to obtain meaningful results. Therefore, the measurement of potentials in concrete is analytically investigated. The effect of internal defects on the potentials measured is clarified numerically by the boundary element method (BEM). Thus, a simplified inversion by BEM is applied to convert the potentials on concrete surface to those on rebars, taking into account the concrete resistivity. Because the potentials measured on concrete surface are so sensitive to moisture content, concrete resistivity and surface condition, an inverse procedure to convert the potentials on concrete surface into those on rebars is developed on the basis of BEM. It is found that ASTM criterion is practically applicable to estimate corrosion from the potential values converted. In experiments, an applicability of the procedure is examined by accelerated corrosion tests of reinforced concrete (RC) slabs. For practical use, the procedure is developed where results of IBEM are visualized by VRML (Virtual Reality modeling Language) in three-dimensional space.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.101-104
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• 2000

Nowadays, the issue of congestion control in high-speed communication networks becomes critical in view of the bandwidth-delay products for efficient data flow. In particular, the fact that the congestion is often accompanied by the data flow from the high-speed link to low-speed link is important with respect to the stability of closed-loop congestion control. The Virtual-Connection Network (VCN) in Gigabit Ethernet networks is a packet-switching based network capable of implementing cell- based connection, link-by-link flow-controlled connection, and single- or multi-destination virtual connections. VCN described herein differ from the virtual channel in ATM literature in that VCN have link-by-link flow control and can be of multi-destination. VCNs support both connection-oriented and connectionless data link layer traffic. Therefore, the worst collision scenario in Ethernet CSMA/CD with virtual collision brings about end-to-end delay. Gigabit Ethernet networks based on CSMA/CD results in non-deterministic behavior because its media access rules are based on random probability. Hence, it is difficult to obtain any sound mathematical formulation for congestion control without employing random processes or fluid-flow models. In this paper, an analytical method for the design of a congestion control scheme is proposed based on Smith＇s principle to overcome instability accompanied with the increase of end-to-end delays as well as to avoid cell losses. To this end, mathematical analysis is provided such that the proposed control scheme guarantees the performance improvement with respect to bandwidth and latency for selected network links with different propagation delays. In addition, guaranteed bandwidth is to be implemented by allowing individual stations to burst several frames at a time without intervening round-trip idle time.

• Journal of Microbiology and Biotechnology
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• v.32 no.10
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• pp.1262-1274
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• 2022

Cholangiocarcinoma (CCA) is a complex and refractor type of cancer with global prevalence. Several barriers remain in CCA diagnosis, treatment, and prognosis. Therefore, exploring more biomarkers and therapeutic drugs for CCA management is necessary. CCA gene expression data was downloaded from the TCGA and GEO databases. KEGG enrichment, GO analysis, and protein-protein interaction network were used for hub gene identification. miRNA were predicted using Targetscan and validated according to several GEO databases. The relative RNA and miRNA expression levels and prognostic information were obtained from the GEPIA. The candidate drug was screened using pharmacophore-based virtual screening and validated by molecular modeling and through several in vitro studies. 301 differentially expressed genes (DEGs) were screened out. Complement and coagulation cascades-related genes (including AHSG, F2, TTR, and KNG1), and cell cycle-related genes (including CDK1, CCNB1, and KIAA0101) were considered as the hub genes in CCA progression. AHSG, F2, TTR, and KNG1 were found to be significantly decreased and the eight predicted miRNA targeting AHSG, F2, and TTR were increased in CCA patients. CDK1, CCNB1, and KIAA0101 were found to be significantly abundant in CCA patients. In addition, Molport-003-703-800, which is a compound that is derived from pharmacophores-based virtual screening, could directly bind to CDK1 and exhibited anti-tumor activity in cholangiocarcinoma cells. AHSG, F2, TTR, and KNG1 could be novel biomarkers for CCA. Molport-003-703-800 targets CDK1 and work as potential cell cycle inhibitors, thereby having potential for consideration for new chemotherapeutics for CCA.

• The Transactions of the Korea Information Processing Society
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• v.2 no.5
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• pp.667-676
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• 1995

In ATM traffic multiplexing, the cell clumping and the cell dispersion are occured due to the cell delay variance(CDV) which changes the traffic characteristics. These cell variances increase the burstiness of t.he cell streams and make the network congested. The function of the traffic shaping is necessary to transmit the input streams into the networks or into the traffic policing schemes with some intevals. Most of the existing studies regard the input traffics as the traffic with the identical characteristics. In this study, the traffic shaping is processed by considering the traffic characteristICS with t.he loss-sensitive traffic and the delay-sensitive traffic. The traffic shaping model and the traffic shaping algorithm which considers the" characteristics of input streams have been presented. The traffic effect On t.he CDV size is also studied. The proposed scheme is compared to Virtual Scheduling Algorithm(VSA) and the efficiency of the proposed scheme is evaluated. According to the simulation results, t.he mean delay is decreased about 12% in delay-sensitive traffic and the traffic burstiness is decreased about 11 % in loss-sensitive traffic.

• Journal of the Korea Society of Computer and Information
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• v.17 no.6
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• pp.173-182
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• 2012

A recent advance in smart phones is increasing utilization of location information. Existing positioning system was using GPS location for positioning. However, the GPS cannot be used indoors, if GPS location has an incorrectly problem. In order to solve indoor positioning problems of indoor location-based positioning techniques have been investigated. There are a variety of techniques based on indoor positioning techniques like as RFID, UWB, WLAN, etc. But WLAN location positioning techniques take advantage the bond in real life. WLAN indoor positioning techniques have a two kind of method that is centroid and fingerprint method. Among them, the fingerprint technique is commonly used because of the high accuracy. In order to use fingerprinting techniques make a WLAN signal map building that is need to lot of resource. In this paper, we try to solve this problem in an Indoor environment for WLAN-based fingerprint of a virtual building technique, which is proposed. Proposed technique is classified Cell environment in existed Indoor environment, all of fingerprint points are shown virtual grid map in each Cell. Its method can make fingerprint grid map very quickly using estimate virtual signal value. Also built signal value can take different value depending of the real estimate value. To solve this problem using a calibration technique for the Splite-tree is proposed. Through calibration technique that improves the accuracy for short period of time. It also is improved overall accuracy using predicted value of around position in cell.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.243-245
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• 1998

미래의 셀룰라 이동통신망은 멀티미디어 데이터 서빗를 제공하기 위해서 높은 대역폭이 필요하기 때문에 셀의 크기가 수십 미터 내오인 피코 실(pico cell)로 구성되는 피코 셀 망이 될 것이다. 이와 같은 피코 셀룰라 망에서는 이동통신자의 우치 변화에 따른 handoff 처리 회수가 상대적으로 증가하므로, handoff 처리로 인한 망부하가 늘어났고, handoff처리 지연으로 인하여 사용자는 중단없는 연결서비스 (seamless connection service)를 받지 못할 수도 있다. 본 논문은 VT-CSMA방식을 응용한 기법을 새로운 handoff방식으로 제안한다. 이 기법은 handoff에서 사용하고 delay time virtual clock 과 real clock 의 2개의 clock을 갖도록 함으로써, 빠른 속도로 이동하는 호는 느린 속도로 이동하는 호보다 상대적으로 짧은 시간 내에 handoff가 처리 되도록 한다. 모의 실험 결과는 VT-CSMA기법을 응용한 새로운 방식이 기존 CDMA 방식에서 drop되는 호를 많이 줄이는 효과가 있음을 보인다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.11
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• pp.2585-2593
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• 1997

Recently a new wireless communication architecture, a Virtual Cellular Network(VCN) was proposed in order to improve the preformance of a wireless network. Unlike a conventional cellular network, the VCN does not use a conventional frequency reuse concep. In the VCN, however, each mobile can use the entire system bandwidth. There is no pre-determined border of cells nor fixed based station for a mobile to communicate with. The performance of the VCN is improved by allowing any mobile to communicate with any port which residues in the virtual cell of the mobile. In this paepr, the Multi Packet Encoding (MPE) is proposed for the VCN uplink in order to improve the unfair throughput and delay caused by the position of the mobiles, and its performance is investigated via computer simulations. The Minimum Group(MG) is proposed for downlink protocol.

• IMMUNE NETWORK
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• v.23 no.1
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• pp.11.1-11.11
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• 2023

Memory T cells that mediate fast and effective protection against reinfections are usually generated upon recognition on foreign Ags. However, a "memory-like" T-cell population, termed virtual memory T (T_VM) cells that acquire a memory phenotype in the absence of foreign Ag, has been reported. Although, like innate cells, T_VM cells reportedly play a role in first-line defense to bacterial or viral infections, their protective or pathological roles in immune-related diseases are largely unknown. In this review, we discuss the current understanding of T_VM cells, focusing on their distinct characteristics, immunological properties, and roles in various immune-related diseases, such as infections and cancers.

• Korea-Australia Rheology Journal
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• v.21 no.3
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• pp.161-173
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• 2009

This study analyzes especially drag and lift models recently developed for fluid-solid, fluid-fluid or liquid-liquid two-phase flows to understand their applicability on the computational fluid dynamics, CFD modeling of pulsatile blood flow. Virtual mass effect and the effect of red blood cells, RBCs aggregation on CFD modeling of blood flow are also shortly reviewed to recognize future tendencies in this field. Recent studies on two-phase flows are found as very useful to develop more powerful drag-lift models that reflect the effects of blood cell's shape, deformation, concentration, and aggregation.