• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.9
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• pp.1175-1182
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• 2013

The lock-in mode infrared thermography (IRT) technique has been developed to improve the detection capability of defects in materials with high thermal conductivity, and it has been shown to provide better detection capability than conventional active IRT. Therefore, to investigate the application of this technique to nuclear piping components, lock-in mode IRT tests were conducted on pipe specimens containing simulated wall-thinning defects. Phase images of the wall-thinning defects were obtained from the tests, and they were compared with thermal images obtained from conventional active IRT tests. It showed that the ability to size the detected wall-thinning defects in piping components was improved by using lock-in mode IRT. The improvement was especially apparent when detecting short and narrow defects and defects with slanted edges. However, the detection capability for shallow wall-thinning defects did not improve much when using lock-in mode IRT.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.20 no.1
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• pp.77-83
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• 2002

Recently, the industrial development caused the expansion of city and the field of construction is being larged in size. So, information of construction buried in underground is necessary. In this paper, we were investigated the detachability on various specimen in self-designed test field using the GPR system with three antenna elements and it was constantly radiated 730 MHz frequency. To examine the detachability on various condition, the test were displayed B-scan CRT. And the pattern was exactly positioned when it was compared to the real buried-depth. Therefore, we can confirm similarity between the wave-propagation velocity and previous results.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.17 no.2
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• pp.161-166
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• 1999

The GPS ability for detecting the deformation is experimently tested by analyzing how precisely GPS can detect the true movement value of the GPS test bed with three axis. As the result, we found that GPS can detect the deformation with the precision of 2 mm in horizontal componts and 8 mm in vertical component for the short baseline of 16 km. The applicable possibilities of GPS for measuring the structure deformation are discussed on the base of this result.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.4
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• pp.322-328
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• 2000

In this paper, we were investigated the detectability on various specimen in self-designed test field using the GPR system with three antenna elements. The GPR system was constantly radiated 730MHz frequency. To examine the detectability on various condition, the test were experimented using different materials, size and buried depth. As an adjusted wave-propagation velocity, the location of hyperbolic curve pattern were displayed B-scan CRT. And the pattern was exactly positioned when it was compared to the real buried-depth. Therefore, we can confirm similarity between the wave-propagation velocity and previous results.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.900-901
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• 2008

본 논문은 NPC 인버터(Neutral-point-clamped Inverter) 시스템을 구성하는 스위칭 소자에 개방성 고장이 발생하였을 경우 인버터 시스템의 고장 검출을 위한 새로운 고장 검출 방법을 제안하였다. 이 방법은 CPWM(continuous-PWM) 고유의 특성을 이용하기 때문에 간단한 알고리즘으로서 구현이 용이할 뿐만 아니라 기존의 방법보다 빠른 고장 검출 능력을 가진다. 빠른 고장 검출 능력은 고장 검출 시간의 지연에서 올 수 있는 직류-링크 커패시터의 전압 불평형 문제 및 이로 인한 다른 스위치로의 전압 스트레스 증가에 의한 소자 파괴와 같은 악영향을 개선시킬 수 있다. 제안된 방법의 타당성을 입증하기 위하여 실험을 수행하였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4A
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• pp.316-323
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• 2002

In this paper, we propose a counter-countermeasure (CCM) in a crossed array tracker for efficient target tracking under countermeasures (CM) operated by a target. The proposed CCM adepts two detection bands and uses the signal distribution characteristics to discriminate between the target and the CMs. To avoid wrong detection of a target position due to missing signal pulses, it predicts current target position based on previous target position. To evaluate the performance of the proposed CCM in a crossed array tracker, we perform numerical simulations for target signal extraction and target tracking under various conditions. The simulation results show that the proposed CCM removes the CM effect well and tracks the target efficiently.

• Journal of Radiation Protection and Research
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• v.35 no.1
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• pp.43-48
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• 2010

Beam quality is determined according to Xray tube's target material. In a range of between 22 kVp and 28 kVp, molybdenum target generates the characteristics energy between the average 17.9 kVp and 19.5 kVp, which produces the high contrast image of the breast. In this study, we used the Mo/Mo combination breast device and ALVIM TRM phantom and measured the detection ability of the minute lesion in the breast imaging throughout analyzing ROC curves. Assuming that an average subject thickness of the breast is 40 mm, the detection ability was not dependent on the kVp changes in a while dependent on both the mAs and thickness change. We can assure that it is not needed to increase the kVp for the imaging of breast which thickness is within the mean range of 40 mm.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.3
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• pp.19-26
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• 1999

The detectability of pipes buried in dry sand is investigated by using the GPR with self-designed bow-tie antenna. The antennas are covered with shielding structures to reduce the direct-coupling between the transmitting and receiving antennas. The ringing, due to finite length of the antenna, is decreased by performing resistive termination at the ends of the antennas. It is shown that without additional signal processing, the presence of various buried targets can be found by discriminating hyperbolic pattern in B-scan data.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.11
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• pp.69-77
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• 2004

An efficient board-level interconnect test algorithm is proposed considering both the ground bounce effect and the delay fault detection. The proposed algorithm is capable of IEEE 1149.1 interconnect test, negative ground bounce effect prevention, and also detects delay faults as well. The number of final test pattern set is not much different with the previous method, even our method enables to detect the delay faults in addition to the abilities the previous method guarantees.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1B
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• pp.112-119
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• 2000

A two-color infrared (IR) seeker employs two detection-bands for efficient target tracking under countermeasures and background noises. This paper describes a study on the detection-band selections for the two-color seeker. To select the detection-bands, we analysis infrared radiation characteristics of a target, a flare, and background noises and then other characteristics closely related with the received power, such as the atmospheric transmission, acquisition range, background noise effect, and signal-to-noises. The analysis shows that the pertinent bands of two-color IR seeker are 3 um~5 um for target detection and 1.5 um~l.7 um for counter-countermeasures. The results of our study will play a significant role in the further study of two-color seekers.