• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1010-1011
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• 2006

A new soft switched active snubber circuit is proposed to achieve zero voltage and zero current switching for all the switching devices in PWM DC-DC converters. The unique location of the snubber capacitor and inductor ensures low current/voltage stresses and commutation losses. With a saturable reactor, the conduction loss of the auxiliary switch could be further minimized. A boost converter adopting this technique is presented as an example, to illuminate its operation principles and derive the design procedures. Simulation and hardware implementation have been made to validate its performance. Some other basic PWM DC-DC topologies using the proposed snubber have also been given.

• Proceedings of the Korean Information Science Society Conference
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• 2000.10c
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• pp.141-143
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• 2000

Web을 이용한 인터넷기술의 발달은 보다 많은 일반 사람들에게 컴퓨터를 이용한 상상을 초월한 인터넷상의 정보를 공유하고 활용할 수 있는 기회를 제공함으로써 인간의 삶을 보다 더 윤택하게 해 주었다. 그러나, 모든 사람들이 손쉽게 컴퓨터를 구입하거나 용이하게 사용할 수 없음에 따라 정보의 소외계층을 형성하고 국가간 개인간 정보의 빈익빈 부익부 현상을 초래하였다. 최근 들어 컴퓨터보다 사용자들에게 친근하고 이동성이 뛰어난 무선 통신 기기를 통한 인터넷접근이 관심을 받고 있다. 그러나 이러한 무선 인터넷 환경은 기존의 유선환경에 비해 많은 제약이 따르게 된다. 본 논문에서는 그러한 제약 중 비 지속적인 연결로 인한 파라미터 손실에 관한 해결방법의 모델링과 그 방법을 적용한 무선 인터넷 사이트를 구현해 보았다.

• Proceedings of the IEEK Conference
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• 2000.07a
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• pp.117-120
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• 2000

As the use of real-time multimedia applications increases, a considerable amount of “greedy” UDP traffic would easily dominate network bandwidth and packet loss. As a result, bandwidth available to TCP connections is oppressed and their performance extremely deteriorates. In or-der that both TCP and UDP sessions fairly co-exist in the Internet, it is vital that we consider the fairness among both protocols. In this work, we implement a “TCP-friendly” rate control mechanism suitable to video applications and con-sider its applicability to a real system through observation of the video quality at the receiver and the connection state. It is shown that we can achieve high-quality and stable video transfer fairly sharing the network bandwidth with TCP by applying our rate control at a control interval of 32 times as long as RTT.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.81-82
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• 2006

Most work on cooperative diversity has assumed that the cooperating group (source and partners) and the associated average channel conditions between terminals (source, partners, and destination) are predetermined. In practical situations, however, it is important to develop the efficient algorithms for assigning the terminals with good inter-user channels for cooperating groups. In this paper, we propose the partner assignment algorithm for cooperative diversity in mobile communication systems. The proposed partner assignment algorithm is investigated by using the path loss model for mobile communication systems. Numerical results show that the proposed partner assignment algorithm provides the comparable probability of cooperative transmission to the partner assignment algorithm using exhaustive search. The probability of cooperative transmission increases with the number of users, which gives potential benefits of practical implementation to user cooperation in mobile communication systems.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.45-46
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• 2006

An ultrawide bandpass filter with sharp rejection and wider stopband is designed and implemented using multilayer ceramic configuration. The proposed filter is composed of a broadside coupled structure and a ring type filter with an embedded stripline stub. The measured results show that the fractional bandwidth and upper stopband of the proposed filter are 106 % and better than -30 dB, respectively. The insertion loss is less than 1 dB, and group delay is less than 0.3 ns in the passband. In addition, ring and broadside coupled gap structures are characterized and compared to the proposed structure.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.169-170
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• 2006

A band pass filter for the V-band application with unique circuit and structure was designed and implemented using 2-metals, 3-BCB layers. In the mean while the effective electrical conductivity of metal layer was extracted and its value was $4{\times}10^7S/m$. The insertion loss of band pass filter at 60 GHz was 3.0 dB and group delay was below 0.1 ns.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1847-1850
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• 2002

In this paper, MPLS Router module supporting Differentiated Service(Diffserv) for quality of Service (QoS) and High-speed switching is proposed and implemented. And we compare and analyze the proposed architecture with the conventional one in terms of CLR (Cell Loss Rate) and average delay. Switch is an extended system of Queue of each VOQ and PHB in the manner of Input Queuing for QoS. Algorithm, Priority-iSLIP is used for its scheduling algorithm. The proposed architecture is modeled in C++ and verified.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2002.11a
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• pp.672-676
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• 2002

Normally the 3rd grade class teachers at commercial rush schools suffer from coaching to selecting new employment of their students because of the lack of those data and systems. Also, the 3rd grade student are struggling for finding optimum information because there is hardly spare time and system for them So, in this article, the guideline for the new students employment-coaching system is described focused on simplification the coaching process by offering useful information and reducing time loss.

• 한국정보디스플레이학회:학술대회논문집
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• 2007.08a
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• pp.413-416
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• 2007

Motion-estimation/motion-compensation (ME/MC) provides superior motion picture quality but its huge computation load results in high cost. Impulsive driving is a cost-effective solution but it suffers from large flicker and brightness loss. Motion compensated impulsive driving technology has been developed to achieve high motion picture quality in a cost-effective implementation by combining ME/MC and impulsive driving. The key idea is to apply ME/MC or impulsive driving selectively according to the motion vector distribution of the incoming image sequence. In this paper, the description of the algorithm and the experimental results are provided.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.78-79
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• 2019

A construction project with a total construction cost of over 10 billion KRW should be evaluated whether construction works are appropriately executed. The evaluation is carried out on quality management, process management, construction management, safety management, environmental management. The implementation period is within 60 days after completion of construction of the construction, from the time when the construction rate of the construction work has progressed by more than 90% to the construction cost. However, the participating construction engineers should prepare the evaluation within the period according to the evaluation criteria, but there are difficulties in preparation for the evaluation due to the reasons such as the change of engineers in charge and loss of data. Therefore, this study proposes the procedure of construction evaluation and adjusts timing of construction evaluation.