• Journal of Institute of Control, Robotics and Systems
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• v.20 no.2
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• pp.138-142
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• 2014

This research presents an A* based algorithm which can be applied to Unmanned Ground Vehicle self-navigation in order to make the driving path smoother. Based on the grid map, A* algorithm generated the path by using straight lines. However, in this situation, the knee points, which are the connection points when vehicle changed orientation, are created. These points make Unmanned Ground Vehicle continuous navigation unsuitable. Therefore, in this paper, B-spline curve function is applied to transform the path transfer into curve type. And because the location of the control point has influenced the B-spline curve, the optimal control selection algorithm is proposed. Also, the optimal path tracking speed can be calculated through the curvature radius of the B-spline curve. Finally, based on this algorithm, a path created program is applied to the path results of the A* algorithm and this B-spline curve algorithm. After that, the final path results are compared through the simulation.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.10a
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• pp.397-404
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• 1999

It is essential to measure load transfer mechanism of pile to check the appropriateness of assumptions made for design purpose and to continuously monitor the behavior of pile foundation. Through many attempts to monitor the behavior of super-structure in civil engineering area using several optical fiber sensors have been made, application of optical fiber sensor technology on pile foundation has not been tried up to now. Load transfer of model piles during compression loading was measured by optical fiber sensors and compared with the measurement by strain gauges. Fiber Bragg Grating(FBG) sensor system was used since it has many advantages, such as easy multiplexing, high sensitivity, and simple fabrication. Besides the model pile tests, uniaxial tension test of steel bar and compression tests of mortar specimen were carried out to evaluate the performance of FBG sensors in embedded environments. The shift of refilming wavelength due to the strain in FBG sensor is converted to the strain at sensor location and the dependence between them is 1.28 pm/${\mu}$ strain. FBG sensors embedded in model pile showed a better survivability than strain gauges. Measured results of load transfer by both FBG sensors and strain gauges were similar, but FBG sensors showed a smoother trend than those by strain gauge. Based on the results of model pile test, it was concluded that the use of FBG sensor for strain measurement in pile has a great potential for the analysis of pile load transfer.

• Journal of The Korean Astronomical Society
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• v.44 no.2
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• pp.59-65
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• 2011

A small number of active galactic nuclei are known to exhibit prominent double peak emission profiles that are well-fitted by a relativistic accretion disk model. We develop a Monte Carlo code to compute the linear polarization of a double peaked broad emission line arising from Thomson scattering. A Keplerian accretion disk is adopted for the double peak emission line region and the geometry is assumed to be Schwarzschild. Far from the accretion disk where flat Minkowski geometry is appropriate, we place an azimuthally symmetric scattering region in the shape of a spherical shell sliced with ${\Delta}{\mu}=0.1$. Adopting a Monte Carlo method we generate line photons in the accretion disk in arbitrary directions in the local rest frame and follow the geodesic paths of the photons until they hit the scattering region. The profile of the polarized flux is mainly determined by the relative location of the scattering region with respect to the emission source. When the scattering region is in the polar direction, the degree of linear polarization also shows a double peak structure. Under favorable conditions we show that up to 0.6% linear polarization may be obtained. We conclude that spectropolarimetry can be a powerful probe to reveal much information regarding the accretion disk geometry of these active galactic nuclei.

• Journal of Environmental Impact Assessment
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• v.2 no.2
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• pp.111-116
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• 1993

The EIA system was developed during ten odd years of introduction. On the other hand, the contentional development representing systematical fidelity does not match to it. I surveyed the problems of EIA on the point of environmental items with no legal standards. EIA is being executed only once on the planning stage. If the present EIA system has two times of execution, the quality of EIA will be much better. First, on the stage of deciding location of the project, EIA should be done. And next, detailed EIA should be done on the stage of executing the project. To describe the problems of EIA, I surveyed the legislations on the point of the former stages, investigation of present status and anticipation. And I tried a theoretical approach to EIA. The knowledge of things, the subject's standpoint and his valuation are all put together in the EIA. The knowledge of relationship between air and water pollutants and their impact on human is accumulated much. On the other hand, the knowledge of the compounded item, fauna-flora(natural ecology) is partial and causes many difficulties. I pointed out the absurdities of assessment technique dealing the standards and introduced assessment technique being applied to items with no physico-chemical standards such as wild lives.

• Korean Journal of Acupuncture
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• v.24 no.2
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• pp.77-97
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• 2007

Objectives : The aim of this study is to introduce pain measurement tools that are considered suitable for clinical practice and research for Korean Medicine Doctors. Methods : We analysed some widely used and also useful pain measurement tools in terms of their methods and dimensions. Results : Diagrams, scales and questions are usually used to measure pain intensity, temporal pattern, treatment including exacerbating and/or relieving factors, pain location, pain interference, pain quality, pain affect, pain duration, pain beliefs and pain history. Specific pain measurements are also available for specific conditions such as Western Ontario and McMaster Universities Osteoarthritis Index, Oswestry Disability Index and Neck Disability Index. Conclusions : Faces Pain Rating Scale, numeric rating scale, visual analogue scale, McGill Pain Questionnaire and Brief Pain Inventory and commonly used pain measurements. Specific measurements should be considered depending on research topics.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.19 no.4
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• pp.58-66
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• 2011

The estimation of fatigue integrity is very important for aerospace structures such as engine mount strut. The reason is that the fatigue integrity is essential analysis process to establish the structural stability in aerospace field. Therefore, in this paper, the process of fatigue analysis and test was performed for engine mount strut to prove the structural fatigue integrity. First of all, the fatigue load spectrum is constructed by considering the small aircraft operating condition. Fatigue analysis is done for the cluster near the welding zone which may have F.C.L.(fracture critical location). The fatigue life of engine mount strut was estimated by the Miner's rule which is the damage summation method. Finally, Fatigue test is performed to verify the fatigue integrity. The estimation process of fatigue integrity for engine mount strut of small aircraft may help the design.

• Journal of Korean Society for Geospatial Information Science
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• v.2 no.2 s.4
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• pp.89-98
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• 1994

Digital road map - which plays an essential role in giving accurate location of the vehicle, optimum route guidance, destination searching, and topographic feature query functions - is the most fundamental element of the vehicle navigation system. Unfortunately, there is not a nation-wide digital map in Korea such as U.S. TIGER fie, that is easily applied to digital road database production. Therefore, producing new digital road map is inevitable in Korea For establishing digital road map for vehicle navigation, this paper puts forth the necessary condition to stabilize the digital road map qualify, and to keep up the compatibility and the economical use. As a result, the standards of coordinate and map accuracy arc presented, and the Items and the structures of database arc decided.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.92-96
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• 2003

Dielectric apertures in vertical cavity laser have been used for improved device performance. Numerical analysis is used to estimate the optical losses as the aperture diameter is reduced. The optical losses depend on the aperture size, thickness and location. The optical loss strongly depend on the aperture size and thickness when the aperture size is similar or smaller than the emitted wavelength. The optical loss is negligible and not depend on the aperture thickness when the aperture size is larger than 5 times emitted wavelength.

• New & Renewable Energy
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• v.3 no.3
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• pp.28-35
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• 2007

In this study, the wave power resources at the three locations [Sokcho, Hupo, and Onsan] on the east coast of Korea were estimated by using the field measurement data and were compared with the results of previous researches. It was found that seasonal variation of the wave power is very significant on the east coast of Korean peninsula. The wave power was the smallest in the summer season at all the locations. At Hupo and Onsan, the highest value of the monthly-averaged wave power was observed in September, probably because the pathways of typhoon in September were close to both locations. At the northest location, Sockcho, in contrast, the monthly highest value of the wave power appeared in January, probably owing to the influence of storm waves driven by Donghae twister. The estimated annual average wave power was 4.5 kW/m at Sokcho, which was about two times larger than those at other two locations. It is noteworthy that this result is completely different from past researches based on wave hindcasting data. In addition, the estimates of wave power by the past researches seemed to be smaller than those of the present study, especially at the northern region of the east coast.

• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.8
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• pp.1493-1502
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• 1992

The purpose of this study is to identify the effects of loading variables on fatigue crack opening behavior, using structural steel SS41. To use various stress ratios, three kinds of the methods varying stress ratio were used; .DELTA.P const., P$_{max}$ const., and P$_{min}$ const.. To measure the opening load, the direct measuring method which measures the distance between two micro indentations 20 .mu.m behind crack tip and the elastic compliance method were used. As the results of present study, the following conclusions are obtained. First, using the direct measuring method, it was possible to measure the COD at any location behind crack tip. Second, as measuring point becomes farther from crack tip, opening load becomes smaller. Third, the acceleration of da/dN near notch is due to crack opening behavior. Finally, opening ratio is a function of not only R, but .DELTA.K.K.K.