• Journal of the Institute of Convergence Signal Processing
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• v.14 no.1
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• pp.1-5
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• 2013

The two major problems related to the blood flow in replaced prosthetic heart valve are thrombus formation and hemolysis. Reliability of prosthetic valve is very important because its failure means the death of patient. There are many factors affecting the valvular failures and their representatives are mechanical failure and thrombosis, so early noninvasive detection is essentially required. The purpose of this study is to detect the various thromboses formation by using acoustic signal acquisition and its spectral analysis on the frequency domain. We made the thrombosis models using Polydimethylsiloxane (PDMS) and they are thrombosis model on the disc, around the sewing ring and fibrous tissue growth across the orifice of valve. Using microphone and amplifier, we measured the acoustic signal from the prosthetic valve, which is attached to the pulsatile mock circulation system. A/D converter sampled the acoustic signal and the spectral analysis is the main algorithm for obtaining spectrum. Then the spectrum of normal and 5 different kinds of abnormal valve were obtained. Each spectrum waveform shows a primary and secondary peak. The secondary peak changes according to the thrombus model. To quantitatively distinguish the frequency peak of the normal valve from that of the thrombosed valves, analysis using a neural network was employed. Acoustic measurement has been used as a noninvasive diagnostic tool and is thought to be a good method for detecting possible mechanical failure or thrombus.

• The KIPS Transactions:PartA
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• v.11A no.1
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• pp.49-56
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• 2004

The performance of the multiprocessor systems is limited by the several factors. The system performance is affected by the processor speed, memory delay, and interconnection network bandwidth/latency. By the evolution of semiconductor technology, off the shelf microprocessor speed breaks beyond GHz, and the processors can be scalable up to multiprocessor system by connecting through the interconnection networks. In this situation, the system performances are bound by the latencies and the bandwidth of the interconnection networks. SCI, Myrinet, and Gigabit Ethernet are widely adopted as a high-speed interconnection network links for the high performance cluster systems. Performance improvement of the interconnection network can be achieved by the bandwidth extension and the latency minimization. Speed up of the operation clock speed is a simple way to accomplish the bandwidth and latency betterment, while its physical distance makes the difficulties to attain the high frequency clock. Hence the system performance and scalability suffered from the interconnection network limitation. Duplicating the link of the interconnection network is one of the solutions to resolve the bottleneck of the scalable systems. Dual-ring SCI link structure is an example of the interconnection network improvement. In this paper, I propose a network topology and a transaction path algorism, which optimize the latency and the efficiency under the duplicated links. By the simulation results, the proposed structure shows 1.05 to 1.11 times better latency, and exhibits 1.42 to 2.1 times faster execution compared to the dual ring systems.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.320-322
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• 1998

TCP/IP 네트워크상의 네트워크 관리에서는 SNMP가 업계의 표준으로 자리 잡고 있다. 또한 각 업계에서는 독자적으로 어플리케이션을 개발해 가지고 있다. 네트워크와 시스템은 관리 시스템의 구축에 있어 가장 중요한 점은 표준화된 관리 정보의 제공에 있다. 이를 위해 관리 시스템간에 교환되는 모든 관리 정보를 위한 개념적인 저장 장소를 에이젼트라 한다. 이에는 관리정보와 구조에 대한 정의로 MIB가 사용된다. 이에 SNMP와 MIB는 네트워크를 관리하기 위해 고안된 프로토콜이며 상호간에 같은 시스템 내에 존재하여야만 한다.이로인해서 SNMP나 시스템을 지원하지 않는 중요 장비에 대한 관리가 어렵다. 이는 관리를 위한 정보가 독립된 패킷으로 구성되어 네트워크 내부로 투입되며 일반 사용자 트래픽과 관리 트래픽이 네트워크 자원을 공유하기 때문이다. 일반 사용자 트래픽과 관리 트래픽 사이의 발생 빈도 균형적으로 유지 할 수 있다면 보다 나은 네트워크 관리가 될 것이다. 이에 본 논문에서는 네트워크간의 상호접속을 균형적인 링 접속 방식을 이용하며 개선하고자 한다. 이로 인하여 시스템의 안정적인 접속과 신뢰성 및 가용성을 증가시킬 수 있다.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.667-669
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• 2002

IEEE 802.1x는 LAN(Local Area network) 환경에서의 인증을 위해서 IEEE에서 제안한 인증 표준 프로토콜이다 IEEE 802.1x는 token ring, FDDI(Fiber Distributed-Data Interrace), 802.3 등 다양한 802 표준에서 동작할 수 있도록 고안되었다 802.1x는 supplicant와 Authenticator, Authentication Server로 구성된다. 이러한 802.1x의 LAN 환경에서 QoS(Quality of Service)를 보장하기 위해서는 자원 예약 메커니즘이 필요하다. 이러한 자원 예약 메커니즘으로는 RSVP(Resource Resonation Protocol)가 있는데 이것은 유선 네트워크를 위해 설계되었기 때문에 새롭게 수정이 불가피하다. 본 논문에서는 RSVP를 수정 보완하여 WLAN(Wireless LAN)에 맞는 시그널링 프로토콜을 제안한다. 제안한 시그널링 프로토콜을 이용하여 WLAN 에서의 QoS 문제를 해결한다.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 2006.07a
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• pp.632-632
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• 2006

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3591-3596
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• 2013

The enantioselective aza-Morita Baylis Hillman reaction of nitroalkene and N-tosylimine catalyzed by thiourea-tertiary amine has been investigated using density functional theory. Enantioselectivity is dominated by the cooperative effect of non-covalent and weak covalent interactions imposed by different units of catalyst. As Lewis base, the tertiary amine unit activates nitroalkene via weak covalent bond. The weak covalent interaction orients the reaction in a major path with smaller variations of this bond. The aromatic ring unit activates N-tosylimine via ${\pi}-{\pi}$ stacking. The non-covalent interaction selects the major path with smaller changes of the efficient packing areas. Thiourea unit donates more compact H-bonded network for species of the major path. The calculated ee value in xylene solution phase (97.6%) is much higher than that in N,N-Dimethylformamide (27.2%). Our conclusion is also supported by NBO analysis.

• Bulletin of the Korean Chemical Society
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• v.35 no.8
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• pp.2419-2422
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• 2014

The syntheses and crystal structures of a three-dimensional (3D) coordination network $[Zn_4(2-mBIM)_5-(C_2H_6NCOO)(HCOO)({\mu}-OH)]{\cdot}DMF$ ($1{\cdot}$DMF; 2-mBIM = 2-methylbenzimidazolate) and a two-dimensional (2D) layer $[Zn_2(2-mBIM)_3(HCOO)(H_2O)]{\cdot}DMF$ ($2{\cdot}DMF$) are reported. Different structures were produced depending on the ratio of reactants. Structurally, 1 illustrates the formation of a unique framework based on a 2-mBIM bridge with the side group on an imidazole ring, while 2 possesses a honeycomb layer built up purely from imidazolates. For gas sorption, $CO_2$ is adsorbed on the activated phase of 1 but $N_2$ is not taken up.

• Korean Journal of Optics and Photonics
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• v.5 no.4
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• pp.493-498
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• 1994

A fiber-optic matched filter with Cr/ Au film-deposited fiber-optic delay lines is fabricated for a possible application as photonic packet address detectors for an all-optical slotted ring network. Correlation waveforms for a set of 6-bit address codes with 2.5 Gb/s are produced by simulation. It is shown that the measured correlation outputs agree well with the calculated ones.d ones.

• Proceedings of the KIEE Conference
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• 1997.07a
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• pp.159-161
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• 1997

This paper presents a method of reducing cogging torque and improving average torque by changing the dead zone angle of trapezoidal magnetization distribution of rotor magnet in ring type. Because brushless d.c. motor has 3D shape of overhang, 3D analysis should be used for computation of its magnet field. In this paper, Three Dimensional Equivalent Magnetic Circuit Network method (3DEMCN) which can calculate an accurate 3D magnetic field has been introduced. The method has an advantage that nonlinear magnetic phenomena can be considered and the cogging torque analyses requesting the rotation of the rotor can be performed by the variation of magnetization distribution without remesh.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10b
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• pp.667-669
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• 1998

그래프 드로잉 시스템이란 주어진 그래프에 대하여 그 그래프가 가진 어떤 특성을 가시화하여 그래픽하게 표현해 주는 소프트웨어 시스템을 말한다. 본 논문에서는 Java를 사용하여 WWW(World Wide Web) 상에서의 상호연결망 그래프의 대칭적 드로잉을 수행하는 그래프 드로잉 시스템을 소개한다. 이 시스템을 Ring, HyperCube, Butterfly와 같은 대표적인 상호연결망 그래프에 대한 기존의 드로잉과 대칭성을 잘 나타내 주는 드로잉을 동시에 보여주며, 또한 HyperCube, HyperTree, Pyramid와 같이 그 모양을 입체적으로 나타낼 수 있는 그래프에 대해서는 원근법을 사용한 3차원 드로잉을 하고 X,Y,Z 축에 따라 이를 회전시켜 그래프에 대한 이해도를 높였다.