• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.7C
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• pp.743-754
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• 2006

In the proposed method, two regular laser working at two different wavelengths perform moving object detection alternatively in time. The laser intensity and the beaming period of each laser is equally maintain as to the single laser radar, hence, externally, dual beam lasers radar works exactly same as the single beam laser radar except that the proposed dual lasers radar needs additional post-processing of received signals in the receiver. To verify the robustness of the proposed method, a set of computer simulation has been performed. The communication channel is assumed to be additive white Gaussian noise, and the perfect synchronization is assumed. All other simulation parameters such as signal power and signalling period are equally maintain in both systems while the signal processing time such as spreading and filtering are expected to be trivial in call cases.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.2
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• pp.57-65
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• 2008

The improvement of the performance in laser radar simulation requires fast retrievals of the spatial locations and attributes of objects in response to the laser signals of the simulators. Since the data used in simulation are complex 3D objects such as terrain, buildings and vehicles, and are of large sizes, commonly used 3D modeling tools are not suitable for this use. We proposed a method to store such 3D objects in a database, perform required queries and integrate with visualization tools. We showed the processes for the data modeling based on 3D topological concepts and then building a spatial DBMS. Also, we illustrated the process for accessing and visualizing the stored data using VRML and performed test computations using some laser signal data. With further enhancement on data modeling and LOD problems in visualization, the proposed method will be practically applied in different situations including laser simulation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.11A
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• pp.1056-1063
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• 2005

In this paper, we develop a dual beam automotive laser radar system which improve the defect of conventional unipolar one beam laser scheme. We introduce an SNR improving method using bipolar signal synthesizing scheme from two unipolar signals at the receiving unit via differential structure by allocating bipolar m-sequence into the two laser wavelengths, which have similar property like 2-D OOC, and investigate its performance. Simulation results show that the proposed dual beam scheme can have 3dB SNR improvement as compared with conventional unipolar signaling laser radar system. Also, we show the simple interference rejection scheme using differential structures. The proposed scheme have a merit to obtain additional 3dB SNR gain applied into the excellent results based on unipolar optical signal studied lately.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.10a
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• pp.305-306
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• 2008

• Journal of the Korea Institute of Military Science and Technology
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• v.14 no.3
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• pp.474-481
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• 2011

The Electronic Warfare Computer for the Aircraft Survivability Equipment will improve the ability for countermeasures by analysis about threat information. This paper suggests method that threat data integration of multiple sensors(Radar Warning Receiver, Laser Warning Receiver, Missile Warning Receiver). The algorithm of threat data integration is based on detected threat sequence and azimuth information. The threat sequence information is analyzed in advance and the azimuth data is received from sensors. The suggested method is evaluated through simulation under the environment like real helicopter.

• Current Optics and Photonics
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• v.1 no.6
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• pp.598-603
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• 2017

Traditional three-dimensional (3-D) laser imaging systems are based on real aperture imaging technology, whose resolution decreases as the range increases. In this paper, we develop a novel 3-D imaging technique based on the synthetic aperture technology in which the imaging resolution is significantly improved and does not degrade with the increase of the range. We consider an imaging laser radar (ladar) system using the floodlight transmitting mode and multi-beam receiving mode. High 3-D imaging resolutions are achieved by matched filtering the linear frequency modulated (LFM) signals respectively in range, synthetic aperture along-track, and the real aperture across-track. In this paper, a novel 3-D imaging signal model is given first. Because of the motion during the transmission of a sweep, the Doppler shift induced by the continuous motion is taken into account. And then, a proper algorithm for the 3-D imaging geometry is given. Finally, simulation results validate the effectiveness of the proposed technique.

• Journal of Korean Society for Geospatial Information Science
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• v.17 no.3
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• pp.97-107
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• 2009

Experiments using real guided weapons for the development of the LADAR(Laser radar) are not practical. Therefore, we need computing environment that can simulate the 3D detections by LADAR. Such simulations require dealing with large sized data representing buildings and terrain over large area. And they also need the information of 3D target objects, for example, material and echo rate of building walls. However, currently used 3D models are mostly focused on visualization maintained as file-based formats and do not contain such semantic information. In this study, as a solution to these problems, a method to use a spatial DBMS and a 3D model suitable for LADAR simulation is suggested. The 3D models found in previous studies are developed to serve different purposes, thus, it is not easy to choose one among them which is optimized for LADAR simulation. In this study, 4 representative 3D models are first defined, each of which are tested for different performance scenarios. As a result, one model, "Body-Face", is selected as being the most suitable model for the simulation. Using this model, a test simulation is carried out.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.9 no.3
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• pp.232-237
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• 2009

Active safety vehicle devices are getting more attention recently. To prevent traffic accidents, the environment in front and even around the vehicle must be checked and monitored. In the present applications, mainly camera and radar based systems are used as sensing devices. Laser scanner, one of the sensing devices, has the advantage of obtaining accurate measurement of the distance and the geometric information about the objects in the field of view of the laser scanner. However, there is a problem that detecting object occluded by a foreground one is difficult. In this paper, criterions are proposed to manage this problem. Simulation is conducted by vehicle mounted the laser scanner and multiple-hypothesis algorithm tracks the candidate objects. We compare the running times as multi-hypothesis algorithm parameter varies.

• Korean Journal of Optics and Photonics
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• v.27 no.4
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• pp.133-142
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• 2016

This paper presents the design and simulation of a three-dimensional pixel-by-pixel scanning light detection and ranging (LIDAR) system with a microelectromechanical system (MEMS) scanning mirror and direct sequence optical code division multiple access (DS-OCDMA) techniques. It measures a frame with $848{\times}480$ pixels at a refresh rate of 60 fps. The emitted laser pulse waves of each pixel are coded with DS-OCDMA techniques. The coded laser pulse waves include the pixel's position in the frame, and a checksum. The LIDAR emits the coded laser pulse waves periodically, without idle listening time to receive returning light at the receiver. The MEMS scanning mirror is used to deflect and steer the coded laser pulse waves to a specific target point. When all the pixels in a frame have been processed, the travel time is used by the pixel-by-pixel scanning LIDAR to generate point cloud data as the measured result.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2008.06a
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• pp.497-500
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• 2008

3차원 오브젝트의 위치 및 정보 획득을 위한 레이저레이더 시뮬레이션의 성능을 향상시키기 위해서는 시뮬레이션의 결과로 획득되는 공간의 범위와 해당 사물의 정보를 정확하고 빠르게 획득해야 한다. 본 연구에서는 이러한 레이더 시뮬레이션의 성능을 향상시키기 위해서 3차원 공간 데이터를 공간DB에 저장하고, 질의를 수행하여 해당 3차원 오브젝트의 정보를 효과적으로 추출해내는 방법론을 제시하였다. 이를 위해 본 연구에서는 시뮬레이션에서 사용되는 3차원 지형지물(지형, 건물 사물 등) 모델의 정보를 데이터모델링을 통해 토폴로지 형태를 갖도록 하였으며, 이를 공간DB에 저장하고, 레이저 신호와의 연산 쿼리를 시행하는 과정을 예시하였다. 이러한 과정을 구현하기 위하여 OGC 기반의 공간 데이터 타입, 함수, 인덱스들을 제공하는 PostgreSQL과 PostGIS를 사용하였다. 지형, 건물, 탱크 등 이렇게 세 가지의 범주의 사물로 나누어 각각을 공간DB로 구현, 쿼리를 실시하였다. 지형정보는 TIN을 사용하였고, 건물의 좌표 값들은 도화원도에서 추출하였으며, 탱크와 같은 사물은 VRML 모델의 좌표 값을 사용하였다.