• Journal of Korea Multimedia Society
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• v.15 no.11
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• pp.1284-1291
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• 2012

Ship object detection is a technique to detect the existence and the location of ship when ship objects are shown on input image sequence, and there are wide variations in accuracy due to environmental changes and noise of input image. In order to solve this problem, in this paper, we propose multiple ship object detection based on background registration technique and morphology operation. The proposed method consists of the following five steps: background elimination step, noise elimination step, object standard position setting step, object restructure step, and multiple object detection steps. The experimental results show accurate and real-time ship detection for 15 different test sequences with a detection rate of 98.7%, and robustness against variable environment. The proposed method may be helpful as the base technique of sea surface monitoring or automatic ship sailing.

• The Korean Journal of Applied Statistics
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• v.31 no.3
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• pp.353-366
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• 2018

This study uses mixed-effects models to predict thigh soft tissue artefact (STA), relative movement of soft tissue such as skin to femur occurring during hip joint motions. The random effects in the model were defined as STA and the fixed effects in the model were considered as skeletal motion. Five male subjects without musculoskeletal disease were selected to perform various hip joint rotational motions. Linear mixed-effects models were applied to markers' position vectors acquired from non-invasive method, photogrammetry. Predicted random effects showed similar patterns of STA among subjects. Large magnitudes of STA appeared on the points near the hip joint regardless of sides; however, small values appeared on the distal anterior.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.42 no.2
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• pp.413-423
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• 2017

In this paper, we propose a ultrasonic and RF-based indoor localization system. In previous work, various systems were proposed for indoor localization, but they have limitation in applicability due to time-synchronization, complexity, or accuracy. To overcome such problems, an indoor localization system with ultrasonic and RF is proposed. A transmitting system is composed of a pair of ultrasonic and RF transmitters and the receiving system is composed of multiple ultrasonic receivers and one RF receiver. The theoretical performance limitation is also analyzed. To verify localization performance, we have implemented a receiving systems and a transmitting system using Arduino modules. Experiments were performed in $2m{\times}2m{\times}2m$ space and the localization errors had a mean of 6.1cm and a standard deviation of 1.6cm.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.3
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• pp.177-184
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• 1987

The quantitative mechanics on the sideways walking of the crabs may provide a basic solution for entanglements of the walking legs in gillnets. The gaiting behaviour of the crabs on the flat board and the nettings 10, 16 and 23 mm in mesh size were experimented concerning about stepping positions and times in the laboratory using video set on July, 1984, It was found that the irregular movements of walking crabs in stepping positions and patterns were appeared on the nettings due to the absence of mechanical contact in spite of neural control of compensating, while on the flat surface evolved systematic leg movements. The mean stride length and walking velocity, which were increased with the carapace width on the flat board, as well as the step period and forward by backward stroke time were greater than those values on the netting, not associated with the carapace or the mesh size. Also, the step period and the Phase difference on the nettings revealed larger fluctuation than on the flat board. The joint angles of the walking legs, on the nettings in meropodite-carporodite and thorax-meropodite, which joint was varied especially up to below horizon because of the falling legs through the netting twine, were virtually wider than those on the flat substrate.

• The Journal of Engineering Geology
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• v.21 no.1
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• pp.1-13
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• 2011

Joint roughness is one of the most important parameters in analysis of rock slope stability. Especially in probabilistic analysis, the random properties of joint roughness influence the probability of slope failure. Therefore, a large dataset on joint roughness is required for the probabilistic analysis but the traditional direct measurement of roughness in the field has some limitations. Terrestrial LiDAR has advantagess over traditional direct measurement in terms of cost and time. JRC (Joint Roughness Coefficient) was calculated from statistical parameters which are known from quantitative methods of converting the roughness of the material surface into JRC. The mean, standard deviation and distribution function of JRC were obtained, and we found that LiDAR is useful in obtaining large dataset for random variables.

• Journal of Korean Society of Transportation
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• v.25 no.4
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• pp.7-19
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• 2007

The purpose of posted speeds is to provide a speed that ensures the safety of vehicle flow according to given road situations. Because of this, posted speeds must be carefully examined, and posted speeds at freeway exits and entrances in particular should consider car characteristics. Posted speeds at freeway exits and entrances must take changing speeds due to curve radiuses into consideration and in this study, an 85th percentile speed becomes the most important element to consider. When it is considered that most traffic accidents occur because of variations in speed between cars, posted speeds should be set after considering car traveling characteristics. Within these dimensions, instead of putting significance on an upper direction regulation or lower direction regulation, speed distributions which fit to the characteristics of each road should be fully considered. Accordingly, this study evaluated appropriate posted speeds that will reduce the dangers of traffic accidents through posted speed regulations of roads now in operation by offering a posted speed setting method theory, using entries at Yangji, Yongin, and Cheongwon interchanges as subjects.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.18 no.1
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• pp.19-23
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• 2000

The estimation of crustal movements along the Cam Lo fault (Quang Tri province, Vietnam) from repeated GPS data (1995-1998) is addressed in this paper. The study area is relatively small and locates at about latitude of N 16 40' 10" and longitude of E 106 58' 40" in the middle of Vietnam. The network consists of 6 points, is located in 3 tectonics units, baselines are from 3 km to 11 km. GPS observations were perforemed to the stations of our network during two campaigns in March 1995 and May 1998. Considering the relation of coordinate variation and its standard deviation based on the result, some remarks can be made: during interval from March, 1995 to May, 1998, there are movements in the investigated area, and the. vertical movements are stronger than horizontal ones. The above results will be favor in a geophysical interpretation of Cam Lo fault for geologists. This seems to be an encouraging result in studying activity of faults in Vietnam.n Vietnam.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.4
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• pp.367-376
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• 2006

This study determines the optimum polynomial of exterior orientation parameters(EOPs) as a function of line number of linear array scanner. To estimate priori EOPs, meta data of IKONOS scene and ground control points are used. We select a first order polynomial and a constant for position elements modeling and rotation elements modeling. Positioning accuracy of the determined EOPs is compared with that of RPCs bias-corrected by the least squares adjustment. There is almost no difference between accuracies of the two methods. To obtain digital elevation model(DEM), matching line is established by the EOPs. The DEM is compared with DEM generated by ERDAS IMAGINE software, which utilizes the bias-corrected RPCs. Height differences of DEMs by the two methods are ranged within a allowable standard deviation. The produced DEM, therefore, shows accuracy similar to the verified method.

• Korean Journal of Optics and Photonics
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• v.9 no.2
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• pp.51-58
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• 1998

We investigated surface-relief profiles of the TPHK(telecentric paraxial holographic kinofrm) used as a Fourier-transform lens employing exact geometrical raytracing. For the TPHK of F/8 and focal length of 15 mm, we consider the cases where the thickness of the substrate is 0 and 50 ${\mu}{\textrm}{m}$, dividing the surface-relif profiles into fifty steps from plano-convex to convexplano shapes and varying the angle of incidence($0^{\circ},{2.5}^{\circ},5^{\circ}$). In order to identify appropriate surface-relief profiles, we employ, as criteria of performance, rms spot size, rms deviation from $f{\sin}{\theta}$, peak position and FWHM(full width at half maximum), number of rays abandoned from raytracing etc., which are determined from the result of exact raytracing. It is found that the profile with 80% of its relief thickness facing the image plane gives the best performance regardless of the presence of substrate.

• Journal of Korean Society for Geospatial Information Science
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• v.18 no.2
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• pp.13-20
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• 2010

Currently, NGII(National Geographic Information Institute) provides VRS(Virtual Reference System) service using 44 CORS(Continuously Operating Reference Stations). Since the VRS provides high-precision coordinate in a short time, the users and applications are expected to be rapidly increasing. The accuracy analysis on the VRS service, however, was not sufficiently performed yet. Therefore, in this study, the VRS data is acquired from various circumstances and its accuracy is analyzed. According to analysis, it was concluded that the VRS could be applied to public control point survey. Furthermore, it was found that the PQ(Position Quality) which represents variance of estimated coordinates rather than GDOP(Geometric Dilution of Precision) is more relevant as a factor to determine the accuracy of coordinates. Based on the analysis of data from four manufacturers (TRIMBLE, MAGELLAN, LECIA, TOPCON), it was confirmed that the standard deviations better than 3cm. Therefore, VRS Survey apply to public control point survey.