• Proceedings of the KAIS Fall Conference
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• 2004.06a
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• pp.206-208
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• 2004

본 논문에서는 LabIEW를 이용하여 필터(RF 수동회로)의 주파수 특성을 테스트하고 테스트한 필터의 특성정보를 관리하는 필터 품질 자동화 시스템을 개발하였다. 개발된 시스템은 LabVIEW에 의해 GPIB 통신으로 계측장비 네트워크 어날라이저를 제어하며 제작된 필터의 S파라미터를 측정하여 명세 기준에 적합하게 제작되었는지를 판별하며 그 결과를 Mysq데이터베이스에 저장하고 관리하게 된다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.9
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• pp.2313-2318
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• 2009

In this paper, when the power equipment, which is based on RFID, is managed, it is reviewed the performance of RFID frequency recognition and its scheme is required to manage status information efficiently. The proposed paper is studied for optimization of recognition performance, when tags are attached the power equipment & major components, to diagnosis failure status of power equipment in monitoring service. The results of paper is valuable applying environment of power equipment.

• The Journal of the Acoustical Society of Korea
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• v.40 no.1
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• pp.73-83
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• 2021

Wind power energy harvesting has a big potential as a future clean energy resource, but accompanies infrasonic noises. The infrasound is difficult to shield and can induce various negative physiological effects. In this study, the Wind Turbine Syndrome (WTS) caused by the infrasonic noises are introduced, and the technical aspects for the measurement and management of the infrasonic noises from wind power plants are discussed.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.1 s.53
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• pp.205-213
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• 2009

This study was planned to develop monitoring system of cable force to resolve cable force of cable-stayed bridge efficiently in a long-term plan. In the proposed monitoring system, firstly data are sampled from real-time acceleration record, secondly these sampled data are frequency analyzed by using the FFT(Fast Fourier Transform) algorism and lastly the analyzed results are averaged and generalized. For evaluating the applicability of this monitoring system, field loading test has performed in real cable-stayed bridge. In comparison with cable force by field manual calculation and cable force of monitoring system by semi-automatic calculation, the difference of calculated cable forces has within 1% error range and it is acceptable range. Additionally within negligible 5% error range of difference has occur between field manual calculation and monitoring system by automatic calculation. so monitoring system in this study has been verified to be reliable.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.8
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• pp.31-40
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• 2009

This paper presents a design of a high performance DC-DC boost converter as a power module for SOC designs. It applied to this chip that reduced inductor and capacitor for integrating on a chip, and it operates with a switching frequency of 100MHz. It has reliability and stability in high switching frequency. The controller of DC-DC boost converter is designed by voltage-mode control method and compensated properly. The designed DC-DC converter is fabricated with the 0.18${\mu}m$ standard CMOS technology with a thick-gate oxide option. The overall die size is 8.14$mm^2$, and controller size is 1.15$mm^2$. The converter has the maximum efficiency over 76% for the output voltage of 4V and load current larger 300mA. The load regulation is 0.012% (0.5mV) for the load current change of 100mA.

• Journal of the Korea institute for structural maintenance and inspection
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• v.7 no.2
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• pp.177-184
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• 2003

A series of experimental work has been conducted to evaluate the capability of Ground Penetrating Radar (GPR) system in detecting delamination inside concrete. Three antenna at 900 MHz, 1000 MHz, and 1500 MHz frequency are used in the experiments for laboratory size specimens, and 400 MHz antenna has been used for a large size specimen. The laboratory size specimens have the dimensions of 1,000 mm (length) ${\times}$ 600 mm (width) ${\times}$ 140 mm (thickness) with a delamination of 200 mm (length) ${\times}$ 600 mm (width) ${\times}$ 140 mm (thickness). The cover depth of the delamination is varied as follows: 20 mm, 30 mm, 60 mm, and 70 mm. In all cases, the delamination has been successfully identified. The property of three frequencies was seized about detecting delamination. Also, it was shown that the image results in GPR were improved by signal processing.

• Explosives and Blasting
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• v.38 no.1
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• pp.14-22
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• 2020

Bit damage is one of the primary causes of decreasing drilling efficacy. Nevertheless the management of bit ware and failure are often left for field engineers' experience. Thus it is imperative to establish a proper system to predict and manage the bit damage during the rock drilling process. In this study, the drilling sound signal has been recorded and analyzed using wavelet transform analysis to identify the exact moment of bit failure. Through the analysis wavelet time-frequency spectrums have been constructed and an abnormal point has been identified with 0.9 of wavelet transform value at the 652.8s on a frequency band around 500Hz. Furthermore it is also observed that the penetration rate of the damaged bit has been decreased to 23mm/s which is 9mm/sec lower than the average of undamaged bit. The study verifies that wavelet transform analysis can be used to build a system to diagnose the bit damage while drilling.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.12A
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• pp.1034-1043
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• 2011

As an introduction of an open spectrum allocation approach with technology and service neutrality is expected as a way to solve problems of frequency shortage due to the expansion of demand for wireless multimedia communications, recently, the new management model of interferences and its standard setting are required. In this paper, as a model for this new interference management considering several candidates, Block Edge Mask(BEM) approach is chosen as the most appropriate model. And to investigate the effects of interference resulting from the standard setting of BEM, assuming the use of LTE systems in the Digital Dividend, BEM out-of-band baseline in the boundaries between digital terrestrial television (DTV) service and LTE mobile communications services which are heterogeneous systems for analysis is derived and the effect of setting guard band is analyzed.

• Journal of KIISE
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• v.42 no.5
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• pp.566-572
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• 2015

We proposed a novel energy optimization technique for smartphone GPUs, more aggressively lowering the GPU frequency while obtaining higher energy efficiency with a negligible negative impact on the GPU performance. In order to achieve the Quality of Service (QoS) specified by the smartphone application, the proposed optimization technique employed the minimal acceptable GPU frequency based on average Frames per Second (FPS) for each GPU frequency level. Our experimental results on a smartphone development board showed that the proposed technique can reduce the GPU energy consumption by up to 23% over the default DVFS algorithm with only a 0.45 frame drop.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.165-174
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• 2010

In this paper, a two-phase structural health monitoring system using acceleration response signatures are presented to firstly alarm the change in structural condition and to secondly detect the changed location for full-scale concrete girder bridges. Firstly, Mihocheon Bridge which is a two-span continuous concrete girder bridge is selected as the target structure. The dynamic response features of Mihocheon Bridge are extracted by forced vibration test using bowling ball. Secondly, the damage alarming occurrence and the damage localization techniques are selected to design two-phase structural health monitoring system for Mihocheon Bridge. As the damage alarming techniques, auto-regressive model using time-domain signatures, correlation coefficient of frequency response function and frequency response ratio assurance criterion are selected. As the damage localization technique, modal strain energy-based damage index method is selected. Finally, the feasibility of two-phase structural health monitoring systems is evaluated from static loading tests using a dump truck.