• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.11
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• pp.755-762
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• 2014

In recent year, along with the rapid development of LED technology, many applications using LEDs with Visible Light Communication(VLC) have been researched. Since it is easy to provide LOS communication environment along with cheap deployment cost, the indoor positioning system based on VLC has been actively studied. In this paper, we propose an accurate indoor positioning algorithm using a stereo image sensor and white-light LEDs with the visible light communication. Indoor white-light LEDs are located at the ceiling of a room and broadcast their position information by VLC technology. Mobile receiver with stereo image sensor receives LED position information by VLC and estimates its position and angle information. Simulation results are given to show the efficiency of proposed indoor positioning algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.11
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• pp.2541-2546
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• 2013

In this paper, we proposed on the azimuth correction method for a line-of-sight data-link tracking antenna system. Tracking antenna system is essential to maintain line-of-sight between moving object and data-link equipment. In order to calculate the azimuth and elevation between the moving object and antenna system, we used GPS data. also to match the each coordinate systems, we used geomagnetic sensor or beacon. However, the geomagnetic disturbance-prone terrain in places difficult to correct calibration. The first step, finds the location of the strongest RF signal, we should remember the difference between the reference point and the detected position of the antenna. The second step, we could communicate each other. And the azimuth angle is calculated by GPS values. Despite the geomagnetic interference, we can correct the azimuth angle quickly and easily.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.4
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• pp.529-535
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• 2020

It is important to secure the driver's external field view in armored vehicles surrounded by iron armor for preparation for the enemy's firepower. For this purpose, a 360 degree rotatable surveillance camera is mounted on the vehicle. In this case, the key idea is to recognize the head of the driver wearing a helmet so that the external camera rotated in exactly the same direction. In this paper, we introduce a method that uses a MEMS-based AHRS sensor and a illuminance sensor to compensate for the disadvantages of the existing optical method and implements it with low cost. The key idea is to set the direction of the camera by using the difference between the Euler angles detected by two sensors mounted on the camera and the helmet, and to adjust the direction with illuminance sensor from time to time to remove the drift error of sensors. The implemented prototype will show the camera's direction matches exactly in driver's one.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.4
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• pp.219-228
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• 2013

The surveillance imaging equipments are functioning to observe the shape of the target in real time or to measure its location precisely. The roles of such equipments are becoming more important in today's weapon systems.The aforementioned imaging equipments can be classified based on the modes of operations such as fixed, installed on cars, or composite of those. Also, according to different concepts of sensor operation, a separate type uses independent housing for each sensor whereas in a composite type a set of multiple sensors are housed into a unit altogether. The sensors in general have magnetism, thereby introducing the possible negative effects, particularly in the composite types, in locating the reference position, which is carried out by the digital compass. The use of shielding material/housing could be an option but results in increased weight and reduced portability, restricting its use in composite type equipments. As such, the objective of this paper is to study on how to reduce such magnetic effects on the position location. To do so, in the absence of magnetic shielding, a variety of sensor positions were first modeled. By combing the result with the fact that the functions of PAN & Tilt are used in the equipments, a new position location algorithm is proposed. The use of the new algorithm can automate the position location process as compared to the manual process of the existing approach. In the algorithm developed, twelve locations are measured in connection with both the azimuth and elevation angles in comparison to the six locations alone around the azimuth angle. As a result, it turns out that the measurement range has been widened but the measurement time reduced. Also, note that the effect of errors the operators may make during measurement could be reduced.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.10
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• pp.4733-4739
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• 2012

While traditional two-axis tracking systems with double sensors had been using two sensors to control azimuth and elevation angle of the sun so that a solar cell module would make a normal line with the sun, this paper proposed a new two-axis system that can achieve the same performance with only one sensor in it. It is Two-axis tracking system that control azimuth and elevation to control to be reduced for solar cell module as proposed tracking system uses 1 sensors and the sun always forms normal. Two-axis tracking system of one sensor method that propose in paper that could reduce electric power consumption and sees than fixed type preventing action and the most efficient driving and needless drive could confirm that generation efficiency of about 23 [%] increases. To heighten efficiency of solar cell doing to receive more sunlights chasing the sun, done tracking device have proceeded a lot of studies in large size way. Therefore, is expected that will do big part in the sun tracking supply through utility study about persistent generation efficiency constructing monitoring system of the sun tracking of this paper.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.155-160
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• 2004

배열센서를 사용한 표적의 위치 추정은 레이다 및 소나에서 잘 알려진 문제이다. 최근에 Lee 등은 1 차원 수평 선배열 센서만을 사용하여 다중경로를 통해 들어오는 신호로부터 표적의 3 차원 위치를 추정하였다. 그러나 이 알고리즘에서 수중에서의 음속은 수심에 관계없이 일정하다고 가정하였기 때문에 음속이 수심에 따라 다양하게 변화하는 실제 수중환경에서는 그 추정성능이 현저히 저하된다. 따라서 본 논문에서는 표적의 거리, 깊이, 방위각으로 구성되는 3 차원 위치 추정을 위해 비균일 음속환경에서의 음파전달모델(ray propagation model)을 이용한 ML 기법(maximum likelihood estimation)을 적용하였으며 일정한 음속을 가정한 Lee 기법의 추정치를 초기값으로 한 탐색을 통해 ML 기법의 연산량을 감소시켰다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.2
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• pp.865-871
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• 2011

Presently, the location and direction information are certainly needed for the autonomous vehicle of the ship. Among them, the direction information is a essential elements to automatic steering system. And the gyro-compass, the magnetic-compass and the GPS compass are the sensor indicating the direction. The gyro-compasses are mainly used in the large-sized ship of the GMDSS(Global Maritime Distress & Safety System). The precision and the reliability of the gyro-compasses are excellent but big volume and high price are disadvantage. The magnetic-compass has relatively fine precision and inexpensive price. However, the disadvantage is in the influence by the magnetism object including the steel structure of a ship, and etc. In the case of the GPS compass, the true north is indicated according to the change of the location information but in case of the minimum number of satellites or stopping of a ship or exercise in the error range, the exact direction cannot be obtained. In this paper, the performance of the GPS compass was improved by using the least-square curve fitting method for the mutual trade off of the angle sensor. The algorithm which improves the precision of an azimuth by applying the weighted value according to the size of covariance error was proposed with GPS-compass and magnetic compass. The characteristic and the performance of the proposed algorithm were analyzed and verified through experimentation. The applicability of the proposed algorithm was shown through the experimental result.

• Defense and Technology
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• no.11 s.297
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• pp.56-61
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• 2003

Longbow Apache의 밀리미터파 사통 레이더는 최첨단의 광학 체계조차 장님으로 만드는 연기와 날씨도 침투한다. 애초에 특수 작전용 Black Hawk와 Chinook에 탑재된 통합 RF Countermeasures는 대공 레이더를 식별하고 위치확인 후 교란한다. IDM(Improved Data Modem), 내장된 GPS 관성 항법장치 그리고 초지평선 HF 무전기가 헬기편대에 포함되서 미래전투체계(FCS)와 UAV(Unmanned Aerial Vehicle)의 정보를 실시간으로 이용할 수 있게 한다. 게다가 AWACS와 JSTARS같은 공군의 공중 레이더, 혹은 해군의 네트워크 중심의 전장 공간 같은 데 있는 해상 센서를 통해 전체적으로 파악된 영상까지도 가능하게 될 것이다.

• 한국공간정보시스템학회:학술대회논문집
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• 2005.11a
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• pp.23-28
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• 2005

고해상도 위성영상으로부터 건물, 도로 등의 인공지물의 정보를 추출하기 위한 연구들이 현재 활발히 진행되고 있다. 대부분의 기존 연구들의 경우, 위성영상에서 3차원 건물정보를 추출하기 위해서는 영상과 별도의 기준점을 필요로 하며, 영상에서의 측정값을 3차원 정보로 변환하기 위해서는 센서모델링의 과정을 거쳐야 했다. 이 연구에서는 단안식 (Monoscopic)영상으로부터 이러한 복잡한 과정을 거치지 않고 직접 건물의 3차원 정보를 추출하는 기술개발에 대하여 소개한다. 제안하는 방식은 단안식 영상에서 영상의 방위각 및 촬영지역에서의 태양과 카메라의 방위각 및 고도각을 이용하여 건물의 높이가 주어졌을 때 이에 따르는 건물 수직선과 건물 그림자를 영상에 투영시키는 과정을 반복함으로써 투영된 건물 그림자가 실제 영상에서 관측되는 건물의 그림자와 일치될 대의 건물의 높이 값을 구하고 건물 지붕 외각선을 구해진 건물의 높이 값에 따르는 건물 수식선 만큼 수평 이동하여 건물의 위치를 구하게 된다. 실제 대전지역을 촬영한 IKONS 영상을 이용하여 실험한 결과 이와 같은 방법으로 취득 된 건물 높이값이 약 1m 내외의 정확도를 가지는 것을 나타났다.

• The Journal of the Acoustical Society of Korea
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• v.25 no.4
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• pp.184-190
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• 2006

Recently, Lee et al. have proposed an algorithm utilizing the signals from different paths by using bottom mounted simple linear array to estimate 3-D location of oceanic target. But this algorithm assumes that sound velocity is constant along depth of sea. Consequently, serious performance loss is appeared in real oceanic environment that sound speed is changed variously. In this paper, we present a 3-D near field localization algorithm for inhomogeneous sound speed. The proposed algorithm adopt localization function that utilize ray propagation model for multipath environment with linear sound speed profile(SSP), after that, the proposed algorithm searches for the instantaneous azimuth angle, range and depth from the localization cost function. Several simulations using linear SSP and non linear SSP similar to that of real oceans are used to demonstrate the performance of the proposed algorithm. The estimation error in range and depth is decreased by 100m and 50m respectively.