• International Journal of Automotive Technology
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• v.8 no.4
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• pp.493-504
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• 2007

This paper proposes a stereo vision-based forward obstacle detection and distance measurement method. In general, stereo vision-based obstacle detection methods in automotive applications can be classified into two categories: IPM (Inverse Perspective Mapping)-based and disparity histogram-based. The existing disparity histogram-based method was developed for stop-and-go applications. The proposed method extends the scope of the disparity histogram-based method to highway applications by 1) replacing the fixed rectangular ROI (Region Of Interest) with the traveling lane-based ROI, and 2) replacing the peak detection with a constant threshold with peak detection using the threshold-line and peakness evaluation. In order to increase the true positive rate while decreasing the false positive rate, multiple candidate peaks were generated and then verified by the edge feature correlation method. By testing the proposed method with images captured on the highway, it was shown that the proposed method was able to overcome problems in previous implementations while being applied successfully to highway collision warning/avoidance conditions, In addition, comparisons with laser radar showed that vision sensors with a wider FOV (Field Of View) provided faster responses to cutting-in vehicles. Finally, we integrated the proposed method into a longitudinal collision avoidance system. Experimental results showed that activated braking by risk assessment using the state of the ego-vehicle and measuring the distance to upcoming obstacles could successfully prevent collisions.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1100-1109
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• 2006

In this study, two different technologies which can measure temperature simultaneously at many points are introduced. One is to use a thermal sensor cable that is comprised of addressable thermal sensors connected in parallel within a single cable. The other is to use an optic fiber with Distributed Temperature Sensing (DTS) system. The difference between two technologies can be summarized as follows. A thermal sensor cable has a concept of 'point sensing' that can measure temperature at accurate position of a thermal sensor. So the accuracy and resolution of temperature measurement are up to the ability of the thermal sensor. Whereas optic fiber sensor has a concept of 'distributed sensing' because temperature is measured by ratio of Stokes and anti-Stokes component intensities of Raman backscatter that is generated when laser pulse travels along an optic fiber. It's resolution is determined by measuring distance, measuring time and spatial resolution. The purpose of this study is that application targets of two temperature measurement techniques are checked in technical and economical phases by examining the strength and weakness of them. Considering the functions and characteristics of two techniques, the thermal sensor cable will be suitable to apply to the assessment of groundwater flow, geothermal distribution and grouting efficiency within 300m distance. It is expected that the optic fiber sensor can be widely utilized at various fields (for example: pipe line inspection, tunnel fire detection, power line monitoring etc.) which need an information of temperature distribution over relatively long distance.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2008.05a
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• pp.101-104
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• 2008

현대에 컴퓨터를 기반으로 무선으로 데이터를 측정하고 제어하는 device들이 보편화 되어있으며, 낮은 가격으로 높은 성능을 낼 수 있는 device들이 각광 받고 있다. 그리고 산업 환경에서 유선 이용이 불가능한 곳이나 직접 사람이 들어갈 수 없는 위험한 장소와 거리 측정할 때 Zigbee 통신 Solution을 이용한다면 공간의 제약 없이 컴퓨터로 데이터를 분석 처리할 수 있다. Zigbee 통신은 기존의 RF나 bluetooth등에 비해 전력 소모에서 효율적이고 battery 사용을 장시간 사용할 수 있는 장점을 가지고 있다. 또한 시스템 구현 비용이 아주 저렴하기 때문에 네트워크에 많은 노드들을 설치 할 수 있다. 이에 본 논문에서 구현한 거리 측정 무선 송/수신 시스템은 여러 개의 LMC(Laser Measuring Control)와 이에 상응하는 여러 개의 Slave Zigbee에서 하나의 Master Zigbee 까지 무선으로 데이터를 송신한다. Master Zigbee는 LMC에서 측정한 데이터들을 수신 받아 컴퓨터로의 처리를 하고자 하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.845-850
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• 2012

Currently power of the diesel engine is increasing continuously, where the wearing problems become more severe. The wearing happens irregularly inside the cylinder, which causes a high burden to the marine engine. In this paper, a novel scheme to measure the wearing and to represent the engine states has been proposed. To monitoring the states of the marine engine efficiently, a laser displacement sensor has been utilized to measure the wearing happening inside the marine engine. To eliminate the noise signals in the distance measurement, the wavelet transform has been adopted, which is robust against the noises caused by vibrations. An engine simulator is designed to develop the system for measuring the engine wears, where the superiority of the wavelet transform against the conventional filtering schemes has been demonstrated.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.6_2
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• pp.643-651
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• 2012

Object recognition belongs to high-level processing that is one of the difficult and challenging tasks in computer vision. Digital photogrammetry based on the computer vision paradigm has begun to emerge in the middle of 1980s. However, the ultimate goal of digital photogrammetry - intelligent and autonomous processing of surface reconstruction - is not achieved yet. Object recognition requires a robust shape description about objects. However, most of the shape descriptors aim to apply 2D space for image data. Therefore, such descriptors have to be extended to deal with 3D data such as LiDAR(Light Detection and Ranging) data obtained from ALS(Airborne Laser Scanner) system. This paper introduces extension of chain code to 3D object space with hierarchical approach for segmenting point cloud data. The experiment demonstrates effectiveness and robustness of the proposed method for shape description and point cloud data segmentation. Geometric characteristics of various roof types are well described that will be eventually base for the object modeling. Segmentation accuracy of the simulated data was evaluated by measuring coordinates of the corners on the segmented patch boundaries. The overall RMSE(Root Mean Square Error) is equivalent to the average distance between points, i.e., GSD(Ground Sampling Distance).

• Journal of the Korean Association of Geographic Information Studies
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• v.11 no.3
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• pp.68-79
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• 2008

Ground vehicle borne system which is named RoSSAV(Road Safety Survey and Analysis Vehicle) developed in KICT(Korea Institute of Construction Technology) can collect road geometric data. This system therefore is able to evaluate the road safety and analyze road deficient sections using data collected along the roads. The purpose of this study is to extract road geometric data for 3D road modeling in dangerous road section and The system should be able to quickly provide more accurate data. Various sensors(circular laser scanner, GPS, INS, CCD camera and DMI) are installed in moving object and collect road environment data. Finally, We extract 3d road geometry(center, boundary), road facility and slope using integrated multi-sensor data.

• Korean Journal of Optics and Photonics
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• v.30 no.3
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• pp.114-119
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• 2019

This paper discusses the development of a Raman lidar system for remote detection and measurement of hydrogen gas by using a photon counter. The Raman signal of the hydrogen gas is very weak and has a very low signal-to-noise ratio. The photon counter has the advantage of improving the signal-to-noise ratio, because it has a discriminator to eliminate the background noise from the Raman signal of the hydrogen gas. Therefore, a small and portable Raman lidar system was developed using a low-power pulsed laser and a photon-counter system to measure the hydrogen gas concentration remotely. To verify the capability of measuring hydrogen gas using the developed photon-counting Raman lidar system, experiments were carried out using a gas chamber in which it is possible to adjust the hydrogen gas concentration. As a result, our photon-counting Raman lidar system is seen to measure a minimum concentration of 0.65 vol.% hydrogen gas at a distance of 10 m.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.172-175
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• 2016

Time of Flight(ToF) LiDAR(Light Detection And Ranging) technology has been used for distance measurement and object detection by measuring ToF time information. This technology has been evolved into higher precision measurement field such like autonomous driving car and terrain analysis since the retrieval of exact ToF time information is of prime importance. In this paper, as a accuracy indicator of the ToF time information, timing jitter was measured and analyzed through Single-Shot LiDAR system(SSLs) mainly consisting of 1.5um wavelength MOPA LASER, InGaAs Avalanche Photodiode(APD) at 31M free space environment. Additionally, we applied spline interpolation and multiple-shot averaging method on measured data through SSLs to improve ToF timing information.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.4
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• pp.301-308
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• 2016

In this study, a novel method referred as non-marker vision-based displacement measuring system(NVDMS) was introduced in order to measure the displacement of structure. There are two distinct differences between proposed NVDMS and existing vision-based displacement measuring system(VDMS). First, the NVDMS extracts the pixel coordinates of the structure using a feature point not a marker. Second, in the NVDMS, the scaling factor in order to convert the coordinates of a feature points from pixel value to physical value can be calculated by using the external conditions between the camera and the structure, which are distance, angle, and focal length, while the scaling factor for VDMS can be calculated by using the geometry of marker. The free vibration test using the three-stories scale model was conducted in order to analyze the reliability of the displacement data obtained from the NVDMS by comparing the reference data obtained from laser displacement sensor(LDS), and the measurement of dynamic characteristics was proceed using the displacement data. The NVDMS can accurately measure the dynamic displacement of the structure without the marker, and the high reliability of the dynamic characteristics obtained from the NVDMS are secured.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.673-679
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• 2000

LNG Carriers are currently known as sole commercial means of shipping natural gas on the sea. They are designed to proven dangerous explosion for shipping a lot of gas over long distance. In this study. In this study, a scaled model chamber was made to investigate ventilation characteristics of the hood room in LNG carrier. Experimental study was performed in model using visualization equipments with laser apparatus and image intensifier CCD camera gated by an AOM controller Twelve different kinds of measuring area were selected as experimental condition. Instant simultaneous velocity vectors at whole field were measured by using 2-D PIV system which software adopts two-frame grey-level cross correlation algorithm. To look into stagnation area of hood room for LNG carrier, a three-dimensional numerical simulation with standard ${\kappa}-{\varepsilon}$ model was carried out by using PHOENICS for three kinds of Reynolds number, $6.5{\times}10^3$, $9.7{\times}10^3\;and\;1.29{\times}10^4$, based on the cavity inlet velocity and cavity height. The flow pattern showed the large scale counter-clockwise forced-vortex rotated at center area, small eddies at each corner and stagnation area located at left-back upper side of model.