• The Journal of the Acoustical Society of Korea
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• v.33 no.3
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• pp.174-183
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• 2014

When a active sonar signal is transmitted and returned back from a target, it has been distorted by various properties of acoustic channel such as multipath arrivals. And signals have been appeared to be different form by target position and attitude. Therefore, we simulated the target echo signal using 3 dimensional target model include reflects target features. In this paper, we develop components form of a simulated target model is made up equally spaced highlight points, and each part of the target consists of shape function. We can simulate a target echo signal and Target strength (TS) according to wave incident angle. To verify, we made small scale target in kit form and we had got underwater target signal for comparing simulation result in water tank.

• Journal of Broadcast Engineering
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• v.14 no.4
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• pp.518-536
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• 2009

To verify the performance of a Distributed Translator Network(DTxR) system in the real world conditions, 5 legacy DTV broadcasting repeater sites were implemented with 5 DTxR systems and field-tested by the DTV field test truck. The 4 DTV broadcasting repeater sites are selected in congested areas where their service areas are overlapped and the 5th site is deviated from the other sites to examine the effect of long-delayed multipath signals. First of all, we checked the receiving signal of the main station that used as a transmitting signal in 5 DTxR systems on the pre-selected 60 test points and tested every case of a DTxR system's on & off except 1 repeater site due to the already built-in DTV repeater system. The test items are received signal electric field strength, noise margin, ease of reception and subjective evaluation of the picture quality for received signals. We used 3rd, 5th, and 6th generation DTV receivers to examine the differences of the receivability by each generation of DTV receivers. Reviewing the test results, we conclude that the DTxR system can be adopted in the current DTV Repeater sites and it could improve the quality and receivability of the main signals by extending the service areas and enhancing the signal levels in the shadow areas without using the extra broadcasting channels.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.80-80
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• 2016

GPS로 대표되는 위성항법시스템(GNSS : Global Navigation Satellite System)은 지구 주위를 돌면서 연속적으로 항법신호를 보내고 있다. 그 중 지구표면으로부터 반사되는 항법신호를 수신하고 해석함으로써 지구표면에 관한 정보를 취득할 수가 있다. GPS로 대표되는 항법신호는 L밴드를 사용하기 때문에 토양수분의 변화 등에 대한 반사강도의 감도가 비교적 높다고 알려져 있으며, 토양수분 측정 등에 사용할 수 있다. 뿐만 아니라 경량화, 소형화하기 쉬운 점, 능동적 마이크로웨이브 리모트센싱시스템(Active Microwave Remote Sensing System)과 달리 스스로 신호를 발사하지 않기 때문에 관측의 스텔스성(Stealth)dl 뛰어난 점 등의 장점을 가지고 있다. 또한 향후 10년 이내에 준천정위성(QZSS), Galileo, COMPAS, IRNSS 등 많은 위성항법시스템이 본격 운용되어 GPS와 함께 120기 정도의 항법위성이 항법신호를 송신할 예정이므로 이용 가능성은 크게 늘어날 것으로 기대된다.한편, 항법위성을 이용한 바이스테이틱 리모트센싱은 반사파의 강도가 상당히 미약하기 때문에 정량적 계측모델의 구축은 미미한 상태이다. 즉, 지상 타워에서의 관측, 항공기에서의 관측, 소형 위성에서의 관측 등이 수행되고 있으나, 타워관측과 같이 지상의 거의 동일한 장소를 계속적으로 관측하는 경우를 제외한 기존의 연구에서는 토지의 피복상황이나 토양수분 등의 상관관계를 제시하는 수준으로써 정량적인 계측방법은 아직 확립되어 있지 않다. 이러한 관점에서 본 연구에서는 GPS위성으로부터의 항법신호를 이용하여 지구표면에 관한 정보를 얻는 바이스테이틱 리모트센싱(Bi-static Remote Sensing) 기술을 바탕으로 육지면과 해면의 판별에 신호특성이 어떻게 유효한가를 실험적으로 밝혔다. 이러한 기술은 토양수분 측정 등 수자 원인자를 추출하는데 유용할 뿐만 아니라 수면의 고도 측정, 해상풍 산출 등에도 응용 가능하다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2009.06a
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• pp.368-371
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• 2009

The GALILEO Project is to be the one and only European Global Navigation Satellite System(GNSS). The GIVE-B satellite, a second experimental GALILEO satellite was launched and started the transmission of ranging signals. GIOVE-B satellite is intended as a trueprototype of future GALILEO satellite. So I introduce the standard deviation of code multi path, signal power, antennas performance and L1-E5 group delay etc. Therefore I comprehend the current progress and tend of GALILEO Project and try to propose the national countremeasures.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.7 no.6
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• pp.1146-1152
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• 2003

Satellite television receiving antenna is required for watching TV on the vehicles, ship and car. Recently TV is not only facility as getting information but one of utility in our life. In Korea, already on the service multi-channel satellite TV using excellent visibility and sound, and there are many users using now by fixing antenna. On this thesis, developed ship's satellite TV receiving antenna, the azimuth controlling is adopted azimuth information using gyro sensor and differential of receiving signal strength algorithm, and elevation controlling used gimbals. The result of this research is successfully implemented Korean satellite tracking antenna as performance until ${\pm}$30 degree roll and pitch of ship motion.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.281-281
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• 2004

본 논문에서는 레이들(ladle)에 실린 용강의 균일한 혼합을 위해 사용되는 저취 시스템의 버블 강도를 예측하기 위해 진동센서를 이용한 안착대를 설계하고 제작하였다 또한 무선 인터넷을 이용해 안착대로부터 진동 데이터를 수신하여 실시간으로 원격지에 위치한 서버에 저장하는 시스템을 구현하였다. 이와 함께 저취 시스템에 사용되는 유량제어밸브를 컨트롤하기 위해 기존에 사용되는 프로토콜 변환기를 변경한 데이터 처리장치를 설계하고 제작하였다. 데이터처리장치는 4개의 직렬 신호를 동시에 처리 가능하며 비구조화된 데이터를 보관하다록 하기 위해 플래쉬 메모리를 장착하였으며, CPU의 데이터 처리를 위해 SRAM을 장착하도록 구성하였다.(중략)

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.1
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• pp.51-56
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• 1990

The authors carried out an experiment to investigate the echo fluctuations from ocean bottom due to ship's motion. The bottom echoes was continuously measured, by using a 50 kHz Echo sounder on board of the ship being at anchor under the sea condition of 15 knots in wind velocity and approximately 2 meters in wave height, to extract the information about the pulse stretching and the ship's motion from the first return and the second return. A data acquisition system was used to record digitally the envelope of the echoes, and the analysis was applied to the echo data collected from the continental shelf in the South China Sea. The results obtained can be summarized as follows: 1. The equivalent pulse width of the second return echoes from ocean bottom was 2.4 times longer than that of the first return echoes. 2. The echo peak values of the first return fluctuated markedly than that of the second return and was shown to be extremely sensitive to small change in ship's motion. 3. Energy target strength and peak target strength of the sandy-mud bottom were -13.4 dB and -14.6 dB, respectively.

• Journal of Broadcast Engineering
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• v.15 no.6
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• pp.731-741
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• 2010

In this paper, we propose the methodology of prediction of field strength for a digital television (DTV) receiver by virtue of Recommendation ITU-R P.1546. The curves shown in this recommendation represent the point-to area field strength for 1.0 kW effective radiated power in the 30 MHz ~ 3000 MHz. Based upon the procedures described in this Recommendation, computation results are presented here from the derived formulation of field strength for DTV receiver. To show the validity of this method, some results are compared with the analysis by Okumura-Hata model and it was shown that the error of field strength is in the range of 6.9 ~ 11.5 %. The presented method provides not only the predicted values of field strength for DTV receiving area to check the quality of transmitted signal, but also an appropriate site selection for obtaining good propagation environment. In addition, it can be directly used for analyzing the protection ratio or separated distance for frequency sharing in the same band.

• Korean Journal of Veterinary Research
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• v.41 no.3
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• pp.421-427
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• 2001

This study was performed to evaluate the embolized kidney and contralateral normal kidney using computed tomography (CT) and enhanced computed tomography. Experimental hydronephrosis was induced by ligation of unilateral ureter in Beagle dogs. Renal artery embolization was performed using selective catheterization in the hydronephrotic kidney of seven dogs and EKG, $SpO_2$, body temperature, pulse, and repiratory rate were within normal ranges during procedures. Iohexol-ethanol solution was used as embolic material. There were no dogs expired after TAE-Ra and no side effects associated with regurgitation of iohexol-ehtanol solution. Revascularization of renal artery was not found in angiography in dogs treated by TAE-RA at immediately after TAE-RA and 14 days after TAE-RA. CT showed dilation of urinary collection system and ventral displacement of spleen at 14 days after TAE-RA in one dog not treated by TAE-RA and experimental group treated by TAE-Ra. CT two month after TAE-RA showed the shrunken embolized kidney in experimental group. Transverse CT with contrast enhancement demonstrated the increase of signal intensity at thinned renal cortex in control group not treated by TAE-Ra at 30 days and 60 days, however, there was no increase of signal intensity at shrunken embolized kidney at 60 days after TAE-RA. CT was useful modality for evaluation of the morphology and the size of embolized kidney and contralateral normal kidney. Enhanced CT was availabel for the detection of revascularization of renal artery after TAE-RA in dogs with hydronephrosis. It is conclued that CT is useful modality for the monitoring of the revascularization of the renal artery after TAE-RA.

• Proceedings of the Korea Inteligent Information System Society Conference
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• 2006.06a
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• pp.107-115
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• 2006

본 논문은 유비쿼터스 환경하에서 수신된 RF 신호의 수신 강도를 이용하여 위치를 추정하고 이를 기반으로 각종 서비스를 제공하는 시스템이다. 이는 크게 무선 송신 단말기, 정보처리 기지국 위치인식 서버 및 시스템 호스트의 네 부분으로 구성되었으며, 30층 규모의 건물에 5000여 개의 단말기가 운영 중에 있다. 실내에서의 이동 객체 위치를 추정하기 위하여 자체 개발, 제작된 송/수신기의 RF 감쇠 특성을 살펴보고, 이를 이용하여 책상, 파티션 등 사무 기기로 이루어진 사무실에서의 위치추정 방법을 소개한다. 실내 환경의 변화와 주변 시설물 등의 영향으로 RF 신호는 감쇠, 흡수, 반사, 회절 등 많은 영향을 받으며, 특히 복층의 경우 층간 효과도 존재한다. 이러 한 실내 상황에서 위치추정 결과를 제시하며, BAS등 회부 시스템과의 연계를 통한 지능적인 서비스를 제공한다. 제고하는 서비스에는 사용자 위치에 근거한 자동 조명/공조 연동 및 주차장 Gate 연동 서비스 등 기본적인 공공 서비스부터 개인별 시강/wellness 이용 현황 등을 자동 체크하여 이에 근거한 요금 부과 및 Schedule 관리 등을 할 수 있게 하는 개인 서비스가 있다. 또한 본 시스템을 실제로 설치, 운영하고 있는 적용 사이트에 관한 사례를 통해 앞으로의 개선 방향 및 서비스 효율성 등에 관해 논의한다.