• Journal of Engineering Education Research
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• v.2 no.1
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• pp.10-16
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• 1999

In this paper, we developed the internet-based educational software package (DVLab) for design and virtual experiment of the digital logic circuits. The DVLab consists of the LogicSim module for design and simulation of digital combinational/sequantial logic circuits, micro-controller application circuits and the BreadBoard module for virtual experiment and the Theory module for lecture and the Report/ReportChecker module and some other utility modules. All developed modules can be run as application programs as well as applets in the Internet. The LogicSim and the BreadBoard support real time clock function, output verification function on the designed circuits, trace function of logic values, copy-protection function of designed circuits and provide various devices including logic gates, TTLs, LED, buzzer, and micro-controller. The educational model of digital logic circuit design and experiment using the DVLab is also presented in this paper.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.2
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• pp.134-138
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• 2008

We present a power gating turn-on mechanism that digitally suppresses ground-bounce noise in ultra-deep submicron technology. Initially, a portion of the sleep transistors are switched on in a pseudo-random manner and then they are all turned on fully when VVDD is above a certain reference voltage. Experimental results from a realistic test circuit designed in 65nm bulk CMOS technology show the potential of our approach.

• Proceedings of the KIPE Conference
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• 1996.06a
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• pp.63-66
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• 1996

An micro model for the power insulated Gate Bipolar Transistor(IGBT) is developed. The model consistently described the IGBT steady-state current-voltage characteristics and switching transient current and voltage waveform for all loading conditions. The model is based on the equivalent circuit of a MOSFET with supplies the base current to a low-gain, high-level injection, bipolar transistor with its base virtual contact at the collector and of the base. Model results are compared with measured turn-on and turn-off waveform for different drive, load, and feedback circuits.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1514-1517
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• 2005

In recent years, as the demands of VBNS(Very high speed Backbone Network Service) and VDSL(Very high-data rate Digital Subscriber Line) increase, the development of kernel parts of optical communication such as PLC(Planar Light Circuit), Coupler, WDM elements increase. The alignment and the attachment technology are very important to fabricate the optical elements for communication. In this paper, the mechanism of rotational stage are studied. with the three different method and the results of them are applied to the design of the system. The performance test of resolution and travel is performed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.3
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• pp.225-231
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• 1992

In this paper, queuing networks with open chains are considerd to analyze the performance of packet switching networks. Networks are classified into backbone and local access networks. Networks for performance analysis are distributed to twelve regions and DNS is the backbone. Analysis was conducted using the real values from the input to existing networks and mathematical estimation values. As the result of analysis, the mean of end-to-and delay for each chain was presented. Except special regions, we found that there was a little difference between real values and mathematical estimation values. However, there could be a performance problem in total networks due to the increase of communication volumes in each region. So we proposed some solutions to this problem.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2099-2104
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• 2015

The paper presents a monitoring system for the cooling of distribution transformers. The suggested system is controlled by a microcontroller scheme. The system is designed to control the oil temperature. It gives a solution to improve the cooling system by adding a number of fans especially for indoor transformers that are placed in badly-ventilated rooms. Also, the paper includes an alarm system with the possibility of tripping the transformer if it is necessary. The monitoring system consists of acquisition temperature sensor, and on-site unit. The hardware and software of the on-site unit are demonstrated with sufficient illustrations. Small prototype is constructed in the laboratory. Some laboratory experiments are carried out for examining the designed circuit by using Proteus Virtual System Modeling as well as for testing the prototype monitoring system. Concerning this research point, a study is carried out to evaluate the economic feasibility. The results are recorded and associated with many recommendations that may be valuable to electrical distribution (utility) companies.

• Proceedings of the Korea Multimedia Society Conference
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• 2001.11a
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• pp.746-751
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• 2001

본 논문에서는 디지털 논리회로에 대하여 인터넷을 기반으로 가상교육 및 실험실습이 가능한 멀티미디컨텐츠를 개발하였다. 가상강의를 위한 컨텐츠들은 WMT 기술 및 애니메이션이 포함된 파워포인트 자료로 구성된 화상강의 모들과 개념이해를 위한 플래쉬 및 회로실험을 위한 자바 프로그램들로 구성되었다. 또한 웹 상에서의 가상 실험실을 구현하기 위해 임의의 디지털 논리회로 설계 및 검증을 위한 LogicSim 프로그램과 실험기관과 IC 칩 등을 이용한 임의회로의 가상실험 프로그램인 BreadBoard 등을 개발하였고 웹 상에서의 리포트 작성, 제출 및 검사가 가능한 Report 프로그램, 이론 학습 및 가상실험 보조 유틸리티 프로그램들을 개발하였다.

• Journal of the Korean Operations Research and Management Science Society
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• v.18 no.1
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• pp.45-54
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• 1993

Monitoring processor in a circuit switched network is considered. Monitoring processor monitors communication links offers a grade of service in each link to controller. Such an information is useful for an effective maintenance of system. Two links with asymmetric system parameters and multi-symmetric links are respectively considered. Each links is to be an independent M /M/ 1/ 1/ type. Markov modeling technique is used to represent a model of monitoring processor with FCFS steering protocol. Performance measures considered are ratio of monitored jobs in each link, availability of minitoring processor and throughput of virtual processor in each link. The value of the performance meausres are compared with existing and simulation results.

• Proceedings of the IEEK Conference
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• 1998.06a
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• pp.74-77
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• 1998

We consider connection-oriented wireless cellular networks. These networks employ dedicated radio channels for the transmission of signaling information. A forward signaling channel is a common signaling channel assigned to carry the multiplexed stream of paging and channel allocation(virtual circuit allocation) packets from a base station to mobile stations. The delay levels experienced by paging and channel allocation packets have serious effect on the utilization level of the limited radio channel capacity. While a slotted mode operation is used to reduce the power consumption level at mobile stations, it may induce an increase in packet delay levels. In this paper, we thus consider a multiplexing scheme for paging and channel allocation packets under which slots are dynamically allocated for the paging packet transmission. For this dynamic scheme, we develop an analytical method for deriving the delay characteristics exhibited by paging and channel allocation packets, and investigate the effect of network parameters on the delay level by using this method.

• Convergence Security Journal
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• v.7 no.1
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• pp.99-106
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• 2007

We propose a distributed anchor Crossover Switches (CX) searching algorithm to play an important role in ensuring fast and seamless handoff control in wireless ATM networks. Within networks that are grouped together, connection management is done for each group by anchor switches, and Permanent Virtual Circuit (PVC) with a narrow bandwidth is assigned between anchors for exchange of information. The proposed algorithm enables quick searching of a targeted CX, makes management of the overall network easier, and reduces system overhead or propagation delay time, thus providing fast and seamless handoff.