• 한국수소및신에너지학회논문집
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• 제23권4호
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• pp.316-322
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• 2012

A fuel cell vehicle has the hydrogen detection sensors for checking the hydrogen leakage because it use hydrogen for its fuel and can't use a odorant to protect the fuel cell stack. To verify the hydrogen safety of leakage we select the high possible leak points of fittings in hydrogen storage system and test the leaking behavior at them. The hydrogen leakage flow rate is 10, 40, 118 NL/min and the criterion for maximum hydrogen leakage is based on allowing an equivalent release of combustion energy as permitted by gasoline vehicles in FMVSS301. There are total 18EA hydrogen leakage detection sensors installed in test system. we acquire the hydrogen leakage detection time and determine the ranking. Hydrogen leakage detection time decrease when hydrogen leakage flow rate increase. The minimum hydrogen leakage detection time is about 3 seconds when the flow rate is 118NL/min. In this study, we optimize hydrogen sensor position in fuel cell vehicle and verify the hydrogen leakage safety because there is no inflow inside the vehicle.

• 지질공학
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• 제24권2호
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• pp.191-199
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• 2014

We describe a method for detecting slope instability in flume tests using pore pressure and water content data in conjunction with a statistical control chart analysis. Specifically, we conducted univariate statistical analysis on x-MR control chart data (pore pressure and water content) collected at several points along the flume slope, which we separated into three parts: upper, middle, and lower. To assess our results in the context of landslide forecasting and warning systems, we applied control limit lines at $1{\sigma}$, $2{\sigma}$, and $3{\sigma}$ levels of uncertainty. In doing so, we observed that dispersion time varies depending on the control limit line used. Moreover, the detection of instabilities is highly dependent on the position and type of sensor. Our findings indicate that different characteristics of the data on various factors predict slope failure differently and these characteristics can be identified by univariate statistical analysis. Therefore, we suggest that a univariate statistical approach is an effective method for the early detection of slope instability.

• Composites Research
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• 제24권3호
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• pp.25-30
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• 2011

복합재료의 비파괴 검사 방법에 관한 연구는 복합재료의 신뢰성 및 안전성을 개선시키는데 매우 중요하다. AE기법은 소성변형, 섬유파손, 모재균열 또는 박리에 의해 생성되는 탄성파에서 감지되는 변형 에너지를 감지하여 결함을 평가하는 기법이다. 본 논문에서는 외부 수압을 받는 필라멘트 와인딩 복합재 원통과 샌드위치 원통의 수압시험이 수행되었고, PVDF센서로부터 측정된 AE 신호특성을 분석하였다. 또한, L-C 동조회로와 Band-pass filter 회로를 가진 AE 신호분석기를 설계, 제작 하였으며, 필라멘트 와인딩 원통과 샌드위치 원통에 대한 수압실험에서 제작된 AE 신호분석기의 균열 검출 능력을 평가하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제15권3호
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• pp.171-177
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• 2011

본 논문에서는 비접촉식 충격-반향 기법을 이용한 콘크리트 구조물의 손상 탐지에 있어서 비용 효율성을 높이기 위한 다이나믹 마이크로폰의 적용 가능성에 대하여 알아보았다. 박리 손상이 인공적으로 모사된 콘크리트 슬래브 실험체에 대하여 비접촉 충격-반향 실험을 다이나믹 마이크로폰을 이용하여 수행하였으며 저비용 센서 시스템의 손상 탐지 성능을 분석하였다. 실험 결과 다이나믹 마이크로폰으로 의미있는 신호의 측정이 가능하며, 또한 콘크리트의 박리 손상도 고성능 음압 센서만큼 명확하게 검출 가능하다는 것을 알 수 있었다.

• Nuclear Engineering and Technology
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• 제41권7호
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• pp.979-988
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• 2009

Tensioned metastable fluids provide a powerful means for low-cost, efficient detection of a wide range of nuclear particles with spectroscopic capabilities. Past work in this field has relied on one-component liquids. Pure liquids may provide very good detection capability in some aspects, such as low thresholds or large radiation interaction cross sections, but it is rare to find a liquid that is a perfect candidate on both counts. It was hypothesized that liquid mixtures could offer optimal benefits and present more options for advancement. However, not much is known about radiation-induced thermal-hydraulics involving destabilization of mixtures of tensioned metastable fluids. This paper presents results of experiments that assess key thermophysical properties of liquid mixtures governing fast neutron radiation-induced cavitation in liquid mixtures. Experiments were conducted by placing liquid mixtures of various proportions in tension metastable states using Purdue's centrifugally-tensioned metastable fluid detector (CTMFD) apparatus. Liquids chosen for this study covered a good representation of both thermal and fast neutron interaction cross sections, a range of cavitation onset thresholds and a range of thermophysical properties. Experiments were devised to measure the effective liquid mixture viscosity and surface tension. Neutron-induced tension metastability thresholds were found to vary non-linearly with mixture concentration; these thresholds varied linearly with surface tension and inversely with mixture vapor pressure (on a semi-log scale), and no visible trend with mixture viscosity nor with latent heat of vaporization.

• 비파괴검사학회지
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• 제20권6호
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• pp.562-567
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• 2000

발전 및 산업설비에 사용되는 많은 압력용기는 저합금강을 사용하여 제작되고 있다. 압력용기의 내면은 부식이 미치는 영향을 최소화하기 위하여 오스테나이트계 스테인리스강으로 덧살용접을 하고 있으나, 용접층간의 계면에서 발생하고 있는 박리균열은 압력용기의 신뢰성에 중요한 변수가 되고 있다. 본 연구에서는 DSP를 사용하여 오버레이 용접부를 고속으로 검사할 수 있는 C-scan 시스템을 개발하였다. 본 시스템은 신호 처리부 (오실로스코프, 펄서/리시버, 디지타이저, DSP), 스캐너, 프로그램 및 위치 제어부로 구성되어 있다. 개발된 시스템을 사용하여 실제 오버레이 용접부에 대한 초음파검사를 실시한 결과 고속으로 신뢰성 높은 검사결과를 얻을 수 있었다.

• Smart Structures and Systems
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• 제6권5_6호
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• pp.545-559
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• 2010

This paper presents the results of a pilot study and verification of a concept of a novel methodology for damage detection and assessment of water distribution system. The unique feature of the proposed noninvasive methodology is the use of accelerometers installed on the pipe surface, instead of pressure sensors that are traditionally installed invasively. Experimental observations show that a sharp change in pressure is always accompanied by a sharp change of pipe surface acceleration at the corresponding locations along the pipe length. Therefore, water pressure-monitoring can be transformed into acceleration-monitoring of the pipe surface. The latter is a significantly more economical alternative due to the use of less expensive sensors such as MEMS (Micro-Electro-Mechanical Systems) or other acceleration sensors. In this scenario, monitoring is made for Maximum Pipe Acceleration Gradient (MPAG) rather than Maximum Water Head Gradient (MWHG). This paper presents the results of a small-scale laboratory experiment that serves as the proof of concept of the proposed technology. The ultimate goal of this study is to improve upon the existing SCADA (Supervisory Control And Data Acquisition) by integrating the proposed non-invasive monitoring techniques to ultimately develop the next generation SCADA system for water distribution systems.

• 전기학회논문지P
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• 제55권1호
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• pp.31-34
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• 2006

A infrared rays sensor or ultrasonic sensor can detect the object at the narrow area, however a pressure sensor can detect man and animal at the wide area. It is necessary to manufacture the sensor by using Pb-free ceramics in the respect of environmental protection. Piezoelectric properties of ceramics added 0.2wt% $La_2O_3\;into\;0.96Bi_{0.5}(Na_{0.84}K_{0.16})_{0.5}+0.04SrTiO_3$ were 0.4 of kp, $31{\times}$10^{-3}Vm/N\;of\;g_{33}$. The output voltage of the pressure sensor is 0.48 V at 20 in$H_2O$. The output voltage of the pressure sensor with driving circuit is 9.8 V, 37 ms width.

• 한국식품과학회지
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• 제36권4호
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• pp.677-682
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• 2004

유전자변형(GM)작물의 안전에 대한 논란은 우리나라를 포함한 많은 나라들이 GM 식품의 강제적 표시제를 도입하게 하였다. 본 연구의 목적은 어떤 수준의 열, 압력, 및 산 처리가 정성 PCR과 LEST 방법의 검출 한계 아래까지 GM 콩 혼합물의 DNA나 단백질을 파괴할 수 있는지를 조사하는 것이었다. 결과는 열처리나 고압열처리는 처리 시간에 따라서 도입유전자의 검출이 되지 않을 정도로 DNA와 단백질을 작은 절편들로 파괴함을 보여주었다. 흥미 있는 점은, 가공식품을 위한 LFST의 검출력은 약하게 가공처리된 콩에서 증가하였다. DNA 및 단백질 검출법 모두 $121^{\circ}C$, 1.5기압에서 20분 동안 처리한 후 GM 혼입물의 검출력을 거의 상실하였다. 본 연구의 결과는 시중에 유통되는 어떤 종류의 가공식품이 GM 작물 식품으로 표시되어야 할지를 결정하는데 유용할 것이다.

• 한국원자력학회:학술대회논문집
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• 한국원자력학회 2003년도 춘계학술발표대회 요약집
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• pp.251-251
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• 2003