• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1359-1364
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• 2004

An experiment was performed to study the evaporation heat transfer and the pressure drop characteristics of liquid nitrogen in a horizontal stainless steel tube with wire coil inserts. The inner diameter of test tube is 4.3mm and the length is 1.5m. Four wire coils having different pitch and thickness were inserted into the plain test tube. The wire coil length is 1.5m and the diameter is 3.65mm with thickness of 0.5mm and 0.9mm. Experiments were conducted at saturation temperature of $-191^{\circ}C$ mass flux from 200 to 370 $kg/m^{2}s$ and heat flux of 62 $kW/m^{2}$. Direct heating method was used to apply heat to the test section. Boiling heat transfer coefficients of both the plain and the enhanced tubes were calculated. Pressure drops between inlet and outlet side of test section were also measured, and they are used to estimate EPR(Enhancement Performance Ratio).

• 한국전산구조공학회논문집
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• 제28권6호
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• pp.707-714
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• 2015

본 논문에서는 프리텐션된 고강도 콘크리트 부재에서의 전달길이를 측정하기 위해 FBG 센서가 기입된 스마트 강연선을 활용하여 실험을 수행하였다. 전달길이 측정을 위해 길이 3m, 단면 $150{\times}150mm$의 고강도 콘크리트 시험체를 총 5개 제작하였으며, 프리텐션 도입 시 콘크리트 압축강도는 58MPa로 측정되었다. 실험 결과 콘크리트 표면에 부착하는 기존의 전기 저항식 게이지보다 FBG 센서로부터 보다 정밀하고 신뢰성있는 강연선의 전달길이를 계측할 수 있는 것으로 나타났다. 계측결과로부터 산정된 강연선 전달길이를 기존의 여러 모델들과 비교하였으며, 이를 통해 고강도 콘크리트 부재에서의 전달길이 산정에 대한 기존 모델들의 적용성을 분석하였다. 본 연구 내용은 향후 강연선의 부착 특성 분석 등의 관련 분야 연구 등에 유용할 것으로 기대된다.

• 대한전자공학회논문지
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• 제19권3호
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• pp.19-27
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• 1982

LSI, 프린트 기판등의 배치 문제에 있어서의 목적 함수로써 총배선장의 최소화, 통과선선의 최소화가 지금까지 채용되어 왔었다. 이 목적 함수는 layout의 궁극적인 목표(100% 결선률)를 대국적으로는 반영하고 있다고 말할 수 있지만 국기적으로 혼잡한 배선 상태를 나타내고 있지 않기 때문에 목적 함수로써 불충분한 경우가 많이 보여 지고 있다. 본 논문에서는 국소적인 배선 혼잡도를 나타내기 위해 쎄그먼트(segment) 혼잡도라고 하는 새로운 개념을 도입하여 이 쎄그먼트 혼잡도를 최소로 하는 것을 목적 함수로 하는 것을 제안하였다. 그리고 이 목적 함수를 최적화 하기 위해 능률 좋은 휴리스틱 알고리즘을 제안하고 프로그램 실험에 의해 그 유용성을 확인하였다. 쎄그먼트 혼잡도의 최대치는 총배선장이 짧게 되면 적게 되고 총배선장이 길게 되면 크게 되는 것이 실험의 결과로 얻어져 총배선장을 ?게 하고 동시에 쌔그먼트 혼잡도의 최대치를 적게 하는 제어 파라미터 (혼잡도 Parameter)의 값의 범위를 실험적으로 구하였다.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2001년도 춘계학술대회 논문집
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• pp.250-253
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• 2001

Mechanical properties of gold bonding wire for VLSI packaging have been studied. The diameters of gold wires are about 20-30 micrometer and fracture loads are 8-20 gram force. The elastic modulus, yield strength, fracture strength and elongation properties have been evaluated by micro-tensile test method. This work discusses for an appropriate selection of micro-force testing system and grip design in mim testing. The best method to determine gauge length of wire and to measure tensile properties has been proposed. The mechanical properties such as strength and elastic modulus of current gold bonding wire are higher than pure those of gold wire.

• 한국초전도ㆍ저온공학회논문지
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• 제8권3호
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• pp.1-4
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• 2006

The characteristics of Bi2212 round wire was systematically studied depending on different heat treatment conditions. Initial wire was drawn after routine PIT (Powder In Tube) process. The wire was divided into 3 pieces with 10 cm in length and 2.5 mm in diameter. 3 wires were pre-heat treated separately by different heat treatment schedules, heated in air and nitrogen atmosphere and centrifugally melted. Pre-heated wires were annealed at $845^{\circ}C$ for 40 hours in oxygen atmosphere. SEM results indicate that all pre-heated wires showed highly oriented microstructure. However the wire by centrifugally melted process showed higher density and better electric properties as compared with 2 other wires pre-heated in air and nitrogen atmosphere. The critical current of a centrifugally melted wire was about 18 A in 77 K.

• 수산해양기술연구
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• 제33권1호
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• pp.27-37
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• 1997

The aim of the present study is to investigate experimentally the mechanism of an exploding wire in water and also to observe the bubble motion induced by an exploding wire. The experiment of an exploding wire is carried out in a water tank. As a metallic wire, a tungsten wire of 0.2mm in diameter and 10mm in length is employed. The electric energy of 50-300J is fed to the wire from a capacitor of 100$\mu$F charged up to 1-2.5kV. The explosion is recorded by a CCD camera with the resolution of 1$\mu$sec. The explosion process of metallic wire is divided into three phases. Phase 1 : As the voltage is applied to the wire, the temperature increases due to Joule heating and the wire emits light. Phase 2 : Then the wire melts and the cylindrical plasma is formed between the electrodes. Up to this stage, strong light emission is observed. Phase 3 : The light emission goes out and a vapor bubble begins to grow spherically. The radius of a bubble oscillates in time, but the amplitude of oscillation diminishes in several cycles.

• 정보처리학회논문지A
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• 제13A권1호
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• pp.57-70
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• 2006

본 논문에서는 주어진 상세배치의 배선밀집도를 예측하고, 배선밀집도가 높은 지역을 효과적으로 해결하는 새로운 알고리즘을 소개한다. 제안된 기법의 특징은 다음과 같다. 첫째, 특정지역을 관통하는 넷이 많아 그 지역의 배선밀집도가 높을 경우 관통하는 넷에 연결된 셀들을 효과적으로 찾아내어 그들의 위치를 조정함으로써 배선밀집도를 완화시킨다. 둘째, 리플이동 (ripple movement) 기법을 이용하여 셀들을 이동함으로써 배선길이를 희생시키지 않으면서 배선밀집도를 완화시킨다. 셋째, 셀의 이동에 따른 배선밀집도의 변화 및 배선길이의 변화를 효과적으로 추적할 수 있도록 증분 자료구조 (incremental data structure)를 사용하였기 때문에 실시간으로 변화되는 상황에 적합한 셀 선택이 이루어지며, 실행시간도 매우 빠른 장점이 있다. 마지막으로, 본 논문에서는 MST 넷 모델을 사용하여 배선밀집도를 예측하지만 제안한 기법은 특정 넷 모델에 상관없이 적용할 수 있다. 특히 실제 라우터로부터 배선정보를 얻을 수 있다면, 배선밀집도는 더욱 효과적으로 해결될 수 있다. 제안된 기법을 이용한 실험결과는 배선길이를 희생하지 않으면서 배선밀집도를 매우 효과적으로 개선할 수 있음을 보여준다.

• Journal of information and communication convergence engineering
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• 제6권4호
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• pp.383-390
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• 2008

Clock skew modeling is important in the performance evaluation and prediction of clock distribution network and it is one of the major constraints for high-speed operation of synchronous integrated circuits. In clock routing synthesis, it is necessary to reduce the clock skew under the specified skew bound, while minimizing the cost such as total wire length and delay. In this paper, a new efficient bounded clock skew routing method is described, which generalizes the well-known bounded skew tree method by allowing loops, i.e., link-edges can be inserted to a clock tree when they are beneficial to reduce the clock skew and/or the wire length. Furthermore, routing topology construction and wire sizing is used to reduce clock delay.

• 전기전자학회논문지
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• 제8권1호
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• pp.63-72
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• 2004

The supply voltage has been drop rapidly and the total length of the wire increased exponentially in the nanometer SoC design environment. The ideal supply voltage was dropped sharply by the resistance and parasitic devices which stayed on the kilometers-long wire length. Even worse, it could severely affect the functional behavior of the block of the design. To analyze the effects of the long wire of the SoC while maintaining the accuracy, the modeling of the current and the RC conversion of the parasitic techniques are researched and applied. By these modeling and conversion, the multi-million gates HDTV Chipset can be analyzed within a day. The benchmark analysis of the HDTV SoC showed the superiority to the conventional methods in performance and accuracy.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2000년도 추계학술대회 논문집
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• pp.488-491
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• 2000

Bi-2223/Ag superconducting wires have been mainly prepared by a powder-in-tube method. The drawing and the rolling are main processes to increase the core density and wire length. In the fabrication of long wire, especially, the drawing should be precisely controlled to assure the filament homogeneity. In this paper, the influences of drawing die angle, bearing length and reduction ratio on the sausaging and the critical current density of the wire are investigated. Single cored and multi-filamentary wires are fabricated by PIT method with different conditions. The core densities and sausaging in the wires are investigated and are discussed regarding their relationship to the I$_{c}$. It was made clear that the geometry of drawing die is sensitively dependent on the sausaging. The improvement of I$_{c}$ was achieved by reducing the die angle and high core density.ity.