• 한국방재안전학회논문집
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• 제9권1호
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• pp.33-38
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• 2016

도로포장 및 교량 유지보수 현장에서 노무자의 안전을 관리할 수 있도록 실시간 위치정보 시스템을 개발하였다. 이 시스템은 다중의 노무자들의 실시간 위치 탐색, 이동 이력, 행동 특성을 확인할 수 있다. 이 시스템은 저전력 블루투스 및 지그비 통신시스템으로 구성되었다. RSSI를 이용한 삼각측량으로 위치 인식을 하는 과거의 방법은 매우 큰 오차를 가진다. 때문에 본 연구는 가속도계와 RSSI를 이용한 새로운 거리측정 방법 및 보정 방안을 제시하였다. 도로포장 및 교량 유지보수 현장에서 개발한 시스템의 오차를 평가한 결과 0.2 m~0.4 m의 오차를 나타내었다. 그리고 가속도 이력을 판별하여 통해 노무자의 안전 상황에 대한 판별이 가능함을 확인하였다.

• 한국산학기술학회논문지
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• 제12권9호
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• pp.4223-4238
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• 2011

최근 환경에 대한 관심이 증대되면서 지반보강 재료의 친환경성이 강조되며, 이에 따라 각종 지반주입 재료가 개발되고 있으나 건설현장에서는 대부분 물유리계 재료가 활용되고 있다. 또한 최근 선진국에서는 물유리계 지반 주입재의 단점인 내구성 문제를 해결하기 위하여 여러 가지 공법을 개발하고 있는 실정이다. 본 연구에서는 기존 그라우트 재료의 문제점을 향상시키기 위하여 친환경적인 무기계 가소성그라우팅 재료에 대한 실내 시험을 통해 그라우팅 재료의 공학적 특성을 파악하고자 하였다. 실내시험에서는 그라우팅 재료의 사용량에 따른 점성, 가소성, 압축강도 및 환경영향평가에 대한 검토를 수행하여 최적 배합에 대한 범위를 설정하고, 설정된 배합의 현장적용을 통해 기존의 그라우팅 재료보다 경제적, 공학적으로 우수한 그라우트 재료에 대하여 평가하고자 한다.

• 대한조선학회논문집
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• 제56권1호
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• pp.94-101
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• 2019

Underwater acoustic power should be measured in a free field, but it is not easy to implement. In practice, the measurement could be performed in a reverberant field such as a water-filled steel tank and concrete tank. In this case, the structure and the acoustic field are strongly or weakly coupled according to material properties of the steel and water. So, characteristics of the water tank must be investigated in order to get the accurate underwater acoustic power. In detail, modal frequencies, mode shapes of the structure and frequency response functions of the acoustic field could represent the characteristics of the reverberant water tank. In this paper, the structure-acoustic coupling has been investigated on a reverberant water tank numerically and experimentally. The finite element analysis has been carried out to estimate the structural and acoustical modal parameters under the dry and water-filled conditions, respectively. In order to investigate the structure-acoustic coupling effect, the numerical analysis has been performed according to the structure stiffness change of the water tank. The acoustic frequency response functions were compared with the numerical analysis and acoustic exciting test. From the results, the structural modal frequencies of the water-filled condition have been decreased compared to those of the dry condition in the low frequency range. The acoustic frequency response functions under the coupled boundary conditions showed different patterns from those under the ideal boundary conditions such as the pressure release and rigid boundary condition, respectively.

• 대한한의학회지
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• 제34권1호
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• pp.179-191
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• 2013

Kleine-Levin syndrome is a rare disorder characterized by recurrent episodes of hypersomnia, hyperphagia, hypersexuality and delusion and hallucination with spontaneous recovery. A 17-year-old female suddenly showed hypersomnia, severe fatigue, and compulsive hyperphagia. She was diagnosed with suspected Kleine-Levin Syndrome. The precipitating factor was an upper respiratory tract infection that the patient had undergone 2 weeks prior. Past psychiatric history included somnambulism and ADHD; her symptoms of ADHD included attention deficit, impulsiveness, hyperactivity, and irritability. This was her third episode. Her hypersomnia was longer in duration but lower in frequency compared with usual KLS. Her low LF/HF ratio in heart rate variability measurement showed high parasympathetic nerve activity. A MMPI report showed some psychological problem. The patient was diagnosed of gastric fever by pattern identification. Her hypersomnia episode improved 6 weeks after onset. This is the first reported case of suspected Kleine-Levin Syndrome in the field of Oriental Medicine in Korea.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 하계종합학술대회 논문집(1)
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• pp.252-255
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• 2000

In this paper, a fast pseudo-noise (PN) code acquisition with novel adaptive architecture is presented in direct-sequence spread- spectrum (DS-SS) systems. Since an existing acquisition system has a fixed correlation tap size and threshold value, this system cannot adapt to various mobile communication environments and results in a low detection probability or a high false alarm rate and long acquisition time. Therefore, if a correlation tap size and a threshold value can be controlled adaptively according to received signals, problems of ail existing system will be solved. The system parameter varies adaptively by using constant false alarm rate (CFAR) algorithm well known in a field of detection and proposed signal-to-noise ratio (SNR) measurement system. By deriving formulas of the proposed system, the performance is analyzed.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.689-696
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• 2001

Exergetic and thermoeconomic analysis were performed for a 200kW Phosphoric Acid Fuel Cell(PAFC) plant which offers many advantage for cogeneration in the aspect of high electrical efficiency and low emission. This analytical study was based on the data obtained by in-field measurement of PC25 fuel cell plant to find whether this system is viable economically. For 100% load condition, the electrical efficiency and the unit cost of electricity are about 45% and 0.032 $/kWh respectively, which turn out to be much better than those for the 1000kW gas turbine cogeneration plant. Further, at lower loads, the unit costs of electricity and hot water increase slightly and consequently more economic operation is possible at any loads.

• 천문학회지
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• 제35권2호
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• pp.67-73
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• 2002

We have made a topological study of cosmic microwave background (CMB) polarization maps by simulating the AMiBA experiment results. A ACDM CMB sky is adopted to make mock interferometric observations designed for the AMiBA experiment. CMB polarization fields are reconstructed from the AMiBA mock visibility data using the maximum entropy method. We have also considered effects of Galactic foregrounds on the CMB polarization fields. The genus statistic is calculated from the simulated Q and U polarization maps, where Q and U are Stokes parameters. Our study shows that the Galactic foreground emission, even at low Galactic latitude, is expected to have small effects on the CMB polarization field. Increasing survey area and integration time is essential to detect non-Gaussian signals of cosmological origin through genus measurement.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1104-1108
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• 2007

Automobile sunroof buffeting is the tonal noise of low frequency around 20Hz. It occurs due to the acoustic feedback process between the shear layer detached from the leading edge of sunroof opening and the Helmholtz resonator-like property of a car cabin. In this paper, PIV visualization technique is applied to the unsteady flow field around sunroof opening of an SUV in the full-scale automotive wind tunnel in order to find out buffeting mechanism. A phase-marking PIV measurement method, in which image and sound pressure are recorded simultaneously, and a phase-rearrangement post-processing program were developed for capturing noise-related velocity fields without expensive synchronization systems. Through this study, some characteristics of the real-car sunroof shear layers under various deflector conditions were identified and these results can provide insights into the noise reduction mechanism of the tube-type deflector.

• 한국초전도학회:학술대회논문집
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• 한국초전도학회 2006년도 High Temperature Superconductivity Vol.XVI
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• pp.9-9
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• 2006

• Journal of the Optical Society of Korea
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• 제14권2호
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• pp.127-130
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• 2010

We have developed an efficient electron beam (e-beam) source, a microcolumn, that can be used as a source module for of microscopy and its applications. To obtain a low operating voltage, a very sharp cold field electron emitter was developed by electrochemically etching a tungsten wire. Laser diffraction was used for the fabrication of high-quality electron lenses and for their precise alignment. The measurement of the e-beam currents, and SEM images captured by the microcolumn confirmed the potential of the device as a very good e-beam source.