• 한국항해항만학회지
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• 제27권6호
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• pp.677-682
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• 2003

The long-period gravity wave, the wave period from some ten seconds to some minutes, induces not only the big sway of a ship moored and berthed in the harbor due to the horizontal long-distance motion of a water but also strong exfoliated flow and vortices near the harbor entrance. They muse serious problems on the safety navigation of vessels entering and leaving the harbor, but this gravity wave has not been searched sufficiently yet. Then it is quite important to reveal the characteristics of this long-period gravity wave ana to solve various problems induced by this wave. The long-period gravity wave measurement system with arrayed buoys installed the kinematic GPS was already proposed, which provides the precise propagating direction of the long-period gravity wave. In this paper, the observation results of the wave measurement system are shown by the MUSIC method And the propagating wave direction was estimated precisely enough in comparison with other results used other method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1988년도 전기.전자공학 학술대회 논문집
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• pp.709-712
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• 1988

Ultrasonic Doppler Diagnostic System utilizes the Doppler effect for measurement of blood velocity. The sign of the Doppler frequency shift represents blood flow direction. CW(Continuous-Wave) Doppler System uses quadrature detection and phase rotation method to produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction in the time-domain, had been fabricated. But time-domain analyzing such as audio evaluation and zero- crossing detection for instantaneous and mean frequnecy measurement do not provide both an accurate and quantitative result. Therefore, it is necessary to adopt frequency-domain technique to improve system performance. In this paper, we describe a unit which is composed of CW Doppler System and real-time spectrum analyzer (installed TMS 32010 DSP Chip). This unit shows time-dependent spectrum variation and mean velocity of Blood signal.

• 대한의용생체공학회:의공학회지
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• 제8권1호
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• pp.75-80
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• 1987

With the conventional CW Doppler velocity meter, bl-directional velocities cannot be separated. The new CW Doppler system uses quadrature detection and phase rotation to produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction, is fabricated. Specially, this system shows that phase rotation method for flow direction separation provides easy and satisfactory feature. From in vivo blood flow measurement, we can easily differentiate typical artery flow from vein flow, and measure both velocity characteristics qualitatively.

• 한국산학기술학회논문지
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• 제18권10호
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• pp.499-504
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• 2017

이동형 전파측정시스템은 차량 탑재형으로, 단독임무수행이 가능하도록 설계되었다. 이동측정의 업무 특성상 기동성 확보가 필요하며, 이를 위해서는 안테나의 배치와 매립 방법에 대해 고려할 필요가 있다. 본 논문에서는 이동형 전파측정시스템의 방향탐지 정확도 측정방법개선을 위한 설계를 소개한다. 서보모터(Servo Motor)와 슬립링(Slip-Ring)을 활용하여 방향탐지안테나 마스트를 자체적으로 360도 회전하는 방법에 대해 분석하였고, 기동성과 내구성을 고려했을 때 슬립링을 활용하여 마스트를 회전시키는 방법으로 설계하였다. 이러한 설계를 통해 방향탐지 정확도 측정방법에서 턴테이블(Turn-Table)이 필요 없게 되어 지역적 의존성을 제거하였다. 즉, 전파무반사환경을 충족하는 챔버나, EUT를 공중에 매달리게 만든 후 시험을 수행할 필요가 없어지게 된다. 또한 턴테이블상의 피실험체의 영점조정 및 피실험체의 마운트 절차가 단축되어 생산성의 향상을 꾀할 수 있다. 내구성 강화를 위해 RF케이블 조립체를 마스트 내부로 포선하는 방법을 사용하였고, 설계내용에 따라 RF케이블의 길이가 짧아지는 효과로 인해 케이블 손실의 개선효과를 볼 수 있다. 또한 같은 현상으로 인해 시스템 전체의 무게가 줄어들어 기동성의 향상도 꾀할 수 있다.

• 대한의용생체공학회:학술대회논문집
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• 대한의용생체공학회 1997년도 춘계학술대회
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• pp.131-135
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• 1997

We implementated an ultrasonic wave cane for the blind. The cane detect walking obstacle and provide a walking direction. The cane used time of flight method of ultrasonic-wave for a measurement of obstacle distance and fluxgate geomagnetic sensor for guidance of walking direction. This system can detect an obstacle of upward, forward, downward and that warn to the blind with vibration, pitch sound. And the blind can know walking direction to voice output. As a result, the blind could efficiently avoid a exposed obstacle, obstacles beyond knee, an exposed street obstacle, a branch of tree person's height and it is usable search for surrounding land mark.

• 한국군사과학기술학회지
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• 제23권4호
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• pp.346-354
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• 2020

Nowadays, it is required to apply low observable technology to weapon systems in operation or under development. Radar Cross Section(RCS) is a measure of the scattered power in an given direction when a target is illuminated by an incident wave and used as a parameter to estimate the low observable performance of weapon system. RCS of a target can be calculated by various numerical methods. However, measurement is also needed to estimate RCS of a complex target because it is difficult to estimate theoretically. To acquire reliable measurement results, an analysis of measurement uncertainty is essential. In this paper, error components and uncertainties of near-field RCS measurement system which was constructed in ASTEC(Aerospace System Test & Evaluation Center) were analyzed based on the IEEE recommended practice for radar cross-section test procedures(IEEE Std. 1502-2007) which describes the uncertainty of RCS measurement and unique error components of this near-field measurement system were also identified.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2003년도 제21회 추계학술대회 논문집
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• pp.91-94
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• 2003

An experimental study has been carried out in a supersonic blow-down wind tunnel for examining the influence of streamwise vortices on normal shock-wave/boundary layer interaction. It has been reported by the earlier investigator the streamwise vortices generated by the blowing jets can significantly suppress the shock-induced separation and reduce the wave drag. The blowing jets generate the streamwise vortices with 45$^{\circ}$ angle in the spanwise direction. The shock waves are visualized by a Schlieren optical system. Appropriate measurement systems are provided for the characterization of shock wave/boundary layer interaction. The chamber pressure ratio and blowing pressure ratio are varied from 1.5 to 2.4 and 1.0 to 2.0 respectively.

• 한국해안해양공학회:학술대회논문집
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• 한국해안해양공학회 2003년도 한국해안해양공학발표논문집
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• pp.35-43
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• 2003

Methods for measuring wave height and direction varies throughout the world, depending on wave climate and local traditions. In Japan, bottom mounted systems have long been the standard fur coastal areas with water depth less than 50m, and extensive studies in the 1980s and 1990s refined the systems to a level where the full wave directional spectrum could be measured. (omitted)

• Journal of electromagnetic engineering and science
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• 제5권2호
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• pp.97-103
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• 2005

This paper describes the measured results of sonobuoy transmitting antenna system for anti-submarine warfare (ASW). Since radiation pattern and power density depend on impedance matching between transmitting RF part and antenna with termination resistance, design of matching circuit is very important for sonobuoy system performance. Matching circuit is designed by Smith chart using control of L and C. In standing wave ratio(SWR) measurement using Network Analyzer, SWR of antenna with matching circuit observed 1.5 below at the assigned VHF band. It shows very excellent performance comparison with conversional product that is used for the same object. The measured vertical and horizontal radiation patterns are also shown the satisfaction of military specifications. A drop out of sonobuoy system on the sea is happened when angle of elevation direction is over 10 degrees, and it is conformed that it takes less than I second return to original signal level. The required electric power density is $83\;mW/m^2$ in the military specification, and measured electric power density is observed over average $110\;mW/m^2$ at all frequency bands.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1987년도 전기.전자공학 학술대회 논문집(II)
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• pp.1239-1242
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• 1987

With the convention CW Doppler velocity meter, bi-directional velocities cannot be separated. The new CW Doppler system usee quadrature detection and phase rotation to Produce simultaneous independent audio and velocity signals for forward and reverse blood flow direction, is fabricated. Specially, this system shows that phase rotation method for flow direction separation provides easy and satisfactory feature. From in vivo blood flow measurement, can easily differentiate typical artery flow from vein flow. and measure both velocity characteristics qualitatively.