• Progress in Superconductivity
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• 제4권1호
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• pp.74-79
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• 2002

High-speed probe made to test single flux quantum(SFQ) circuits was comprised of semi-rigid coaxial cables and microstrip lines. The impedance was set at 50 $\Omega$to carry high-speed signals without much loss. To do performance test of high-speed probe, we have attempted to fabricate a test chip which has a coplanar waveguide(CPW) structure. Electromagnetic simulation was done to optimize the dimension of CPW so that the CPW structure has an impedance of 50$\Omega$, matching in impedance with the probe. We also used the simulation to investigate the effect of the width of signal line and the gap between signal line and ground plane to the characteristics of CPW structure. We fabricated the CPW structure with a gold film deposited on Si wafer whose resistivity was above $1.5\times$10$_4$$\Omega$.cm. The magnitudes of S／sub 21／ of CPW at 6 ㎓ in simulations and in the actual measurements done with a network analyzer were: -0.1 ㏈ and -0.33 ㏈ (type A),-0.2 ㏈ and -0.48 ㏈ (type B), respectively. Using the test chip, we have successfully tested the performance of high-speed probe made for SFQ circuits. The probe showed the good performance overthe bandwidth of 10 ㎓.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.444-449
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• 2004

The design modification of bottom guide structures of the instrumented capsule, which is used for the irradiation test in the HANARO reactor, was required because of the trouble of the bottom guide arm's pin during irradiation. The previous structure with 3-pin arms was changed into the cone shape of one body. The specimens of the bottom end cap ring with three different sizes (${\Phi}68/70/72mm$) were designed and manufactured. The out-pile tests for the capsule with previous and new three bottom guide structures were performed in the one-channel flow test facilities. In order to evaluate the compatibility with HANARO and the structural integrity of the capsule, a loading/unloading, a pressure drop, a thermal performance, a vibration, and an endurance test were conducted. From out-pile test results, the capsule with the cone shape bottom guide structures was found to be more stable than the previous structure and the optimized size of the bottom guide structure selected was 70mm in diameter. It is expected that the new bottom guide structures will be applicable to all material and special capsules which will be designed and manufactured for the irradiation tests in the future.

• 한국공작기계학회논문집
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• 제14권4호
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• pp.49-54
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• 2005

Measuring defects on the inside and on the surface of a steel structure is very important technology in order to predict the life span of the structure. In particular, a place with a high probability that it may contain defects is a welded part and it is very important to check defects in the part, absence/presence of non-uniform substances, its shape, and the location. Many non-destructive tests can be applied, but the ultrasonic flow detection test is widely used with some advantages. The ultrasonic flow detection test, however, cannot be applied when there is a problem by a contact medium between PZT and a specimen, in case of a small and complicated shape or a moving object or when the specimen is hot. In this study, to solve the problems of the contact ultrasonic flow detection test, the non-contact ultrasonic flow detection test for sending/receiving ultrasonic waves using lasers was described. I intended to develop a non-destructive detection system applying the laser application ultrasonic test to a steel structure by detecting the defects inside of and on the surface of the specimen.

• 한국지진공학회논문집
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• 제23권4호
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• pp.231-238
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• 2019

A conventional lumped-mass stick model is based on the tributary area method to determine the masses lumped at each node and used in earthquake engineering due to its simplicity in the modeling of structures. However the natural frequencies of the conventional model are normally not identical to those of the actual structure. To solve this problem, recently an updated lumped-mass stick model is developed to provide the natural frequencies identical to actual structure. The present study is to investigate the seismic response accuracy of the updated lumped-mass stick model, comparing with the response results of the shaking table test. For the test, a small size four-story steel frame structure is prepared and tested on shaking table applying five earthquake ground motions. From the comparison with shaking table test results, the updated model shows an average error of 3.65% in the peak displacement response and 9.68% in the peak acceleration response. On the other hand, the conventional model shows an average error of 5.15% and 27.41% for each response.

• 전기학회논문지
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• 제60권5호
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• pp.1043-1048
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• 2011

Test vector reordering is a very effective way to reduce power consumption during test application. But, it is time-consuming and complicated processes, and it does not consider internal circuit structure, which may limit the effectiveness. In this paper, we order test vectors using fanout count of primary inputs that consider the internal circuit structure, which may reduce the switching activity. Then, we reorder test test vectors again by using Hamming distance between test vectors. We proposed FOVO algorithm to perform these two ideas. FOVO is an effective way to reduce power consumption during test application. The algorithm is applied to benchmark circuits and we get an average of 3.5% or more reduction of the power consumption.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.204-209
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• 2004

Recently, the various performances of vehicle are rapidly improved. Therefore tire noise is recognized as important noise source because vehicle noise is considerably reduced. This study is performed for the control of the cavity resonance noise that is structure-borne noise, due to fluid(air)-structure interaction. For this investigation, FRF analysis has been carried out using FEM and we found an important factor affecting cavity resonance. The effect of this factor is confirmed by objective noise test. We confirmed that the result of FRF analysis and objective noise test is that the structure control of tire sidewall can reduce cavity resonance noise due to fluid-structure interaction

• 한국지반신소재학회논문집
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• 제10권3호
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• pp.53-62
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• 2011

본 연구에서는 방수제 구조물 및 하부지반에 대하여 1/100 축소모형의 비율을 갖는 토조를 제작, 설계지진 가속도 0.154g의 진동하중 적용시 진동대 모형실험을 통하여 구조물의 거동특성과 내진 안정성을 평가하였다. 실제 시공순서를 재현하여 완성 후 진동대 모형토조 하부에 설정된 지진하중을 발생시켜 지진에 의한 하부지반과 방수제 구조물의 상호작용을 분석하였다. 즉, 구조물의 수평 및 수직 변위, 구조물 하부지반에 작용하는 간극수압 변화, 하부지반 및 방수제 구조물의 최대가속도 변화량 측정 등 계측결과를 비교 분석하여 내진 안정성을 판단하였다.

• 한국항공우주학회지
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• 제43권9호
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• pp.773-780
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• 2015

본 논문에서는 아음속 환경에서 원통형 비행체의 구조 건전성을 확인하였다. 극한 기동 조건에서 원통형 비행체의 정적 구조 안전성을 확인하기 위하여 구조 해석과 전기체 정적 구조 시험을 수행하였다. 수치 해석을 위하여 상용 유한 요소 프로그램 MSC. Patran/Nastran을 이용하였으며, 전기체 정적 구조 시험에는 중량 보상 장치, 하중 부가 장치, 데이터 획득 장치를 적용하였다. 이와 함께, 동특성 시험으로서 햄머 충격시험을 수행하여 원통형 비행체의 동적 특성을 확인하였다.

• Current Photovoltaic Research
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• 제8권4호
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• pp.114-119
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• 2020

In this study, Mitigation of Potential-induced degradation (PID) for PERC solar cells using SiO2 Structure of ARC layer. The conventional PID test was conducted with a cell-level test based on the IEC-62804 test standard, but a copper PID test device was manufactured to increase the PID detection rate. The accelerated aging test was conducted by maintaining 96 hours with a potential difference of 1000 V at a temperature of 60℃. As a result, the PERC solar cell of SiO2-Free ARC structure decreased 22.11% compared to the initial efficiency, and the PERC solar cell of the Upper-SiO2 ARC structure decreased 30.78% of the initial efficiency and the PID reliability was not good. However, the PERC solar cell with the lower-SiO2 ARC structure reduced only 2.44%, effectively mitigating the degradation of PID. Na+ ions in the cover glass generate PID on the surface of the PERC solar cell. In order to prevent PID, the structure of SiNx and SiO2 thin films of the ARC layer is important. SiO2 thin film must be deposited on bottom of ARC layer and the surface of the PERC solar cell N-type emitter to prevent surface recombination and stacking fault defects of the PERC solar cell and mitigated PID degradation.

• 화약ㆍ발파
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• 제22권1호
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• pp.33-43
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• 2004

본 연구에서는 철근콘크리트(reinforced connote) 구조물에 대해 발파해체 축소모형실험을 수행하고 이를 전산실험결과와 비교하였다. 적용된 발파해체 공법은 파괴거동을 비교적 쉽게 확인할 수 있는 점진붕괴공법이며, 차원해석(Hobbs(1969))을 실시하여 축소모형실험에 적용될 강도특성을 계산하였다. 이에 따라 석고, 모래, 물의 혼합하여 콘크리트를 대용할 재료로 사용하였으며, 연성을 지니며 축소강도가 철근과 유사한 땜용 납선을 철근 대용 재료로 사용하였다. 이 때 모래와 석고의 중량 비를 다양하게 변화시키면서 이에 따른 강도의 변화를 측정하고 최적의 강도 값을 갖는 배합 비를 결정하여 사용하였다. 모형의 제작은 실내에서 미리 양생된 부재들을 현장으로 옮겨 연결부만을 타설하여 일체화시키는 방법으로 구조물을 축조하였다. 축소모형실험을 전산실험결과와 비교하기 위하여 요소의 파괴거동을 육안으로 확인할 수 있는 개별요소법에 의해 수행되는 상용코드인 PFC2D(Particle Flow Code 2-Dimension)를 사용하여 전산해석을 수행하였다. 먼저 3차원 무근 콘크리트 라멘 구조의 모형을 설계하고 그 축소모형을 발파해체하여 거동을 촬영하였다. 이를 전산실험결과와 비교하여 2차원 해석의 한계는 존재하나 대체로 유사한 형태의 거동을 보임을 알 수 있었다. 그리고, 무근 콘크리트 라멘 구조 해석의 경험과 철근콘크리트 보의 실내 굴곡실험결과를 근거로 하여 철근콘크리트 구조모형의 발파해체 사전해석을 실시하였다. 그 결과, 2차원 해석이라는 한계에도 불구하고 900ms 까지는 거의 유사한 거동을 보이며 붕괴됨을 확인하였다.