• Journal of Radiation Protection and Research
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• v.10 no.2
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• pp.96-108
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• 1985

A study for the assessment of natural environmental radiation exposure at a flat and open field of about $10,000m^2$ in area in CNU Daeduk campus has been carried out by means of gamma-ray scintillation spectrometry and thermoluminescence dosimetry for one year period of time from October 1984. The detectors used were 3'${\phi}{\times}$3' NaI(T1) and two different types of LiF TLD, namely, chip sealed in plastic sheet which tightly pressed on two open holes of a metal plate and Teflon disk. Three 24-hour cycles of in-situ spectrometry, and two 3-month and one 1-month cycles of field TL dosimetry were performed. All the spectra measured were converted into exposure rate by means of G(E) opertaion, and therefrom exposure rate due to terrestrial component of environmental radiation was figured out. Exposure rate determined by the spectrometry was, on average, $(10.54{\pm}2.96){\mu}R/hr$, and the rates of $(12.0{\pm}3.4){\mu}R/hr$ and $(11.0{\pm}3.6){\mu}R/hr$ were obtained from chip and disk TLD, respectively. Fluctuations in diurnal variation of the exposure rate measured by the spectrometry were noticeable sometime even in a single cycle of 24 hours. It is concluded that appropriately combined use of TLD with iu-sitn gamma-ray spectrometry system can give more accurate and precise measure of environmental radiation exposure, and further study for more adequate and sensitive TLD for environmental dosimetry, including improvement and elevation of accuracy in data assessment through inter-laboratory or international intercomparison is necessary.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.7
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• pp.658-663
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• 2012

An accurate outdoor localization method using line/arc features is suggested for mobile robots with LRFs (Laser Range Finders) and odometry. Localization is a key process for outdoor mobile robots which are used for autonomous navigation, exploration and so on. In this paper, an accurate pose correction algorithm is proposed for mobile robots using LRFs, which use three feature types: line, circle, and arc. Using this method we can reduce the number of singular cases that robots couldn't find their pose. Finally we have got simulation results to validate the proposed algorithm.

• Journal of the Korea Computer Industry Society
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• v.8 no.3
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• pp.155-166
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• 2007

In this paper, captured face-image was pre-processing, segmentation, and extracting features from thinning by differential operator and minute-delineation. A straight line in slope-intercept form was transformed at the $r-\theta$ domain using Hough Transform, instead of Housdorff distance are extract feature as length, rotation, displacement of lines from thinning line components by differentiation. This research proposed a new approach compare with Hough Transformation and Housdorff Distance for face recognition so that Hough transform is simple and fast processing of face recognition than processing by Housdorff Distance. Rcognition accuracy rate is that Housdorff method is higher than Hough transformation's method.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.12 s.177
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• pp.61-69
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• 2005

This paper presents an efficient method of extracting line segments from the occupancy grids in a grid map. The grid map is composed of 2-D grids that have both the occupancy and orientation probabilities using sonar sensors. We evaluate the orientation information of every grid when the occupancy probability of the grid is updated from sonar range data. To find the shape of an object in the map from orientation information, the orientations are clustered into several groups according to their values. The line segments are, then, extracted from the clusters based on Hough transform. Finally, a feature-based map is built with these line segments. The proposed method is illustrated with the results produced by sets of experiments in an indoor environment.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.9
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• pp.80-89
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• 1997

Die sinking electrical discharge machining(EDM) was conducted for ceramic composite of 33 weight percent TiC based on AI$_{2}$O$_{3}$ ceramic matrix according to the change of current and duty factor(DF). Material removal rate(MRR) was increased as the current and the duty factor increased, but better surface mor-pholoty was obtained in the region of lower current and duty factor. From the scanning electron microscopy(SEM) photographs and the energy dispersive X-ray spectroscopy(EDX) of the EDMed surface, EDM trace formed by one discharge spark was analyzed. Although the bending strength after EDM was highly decreased, reliability obtained by weibull analysis was increased twice. The bending strength was recovered or more by barrel polishing after EDM. From the FEM analysis of temperature for one spark, the possible melting region of AI$_{2}$O$_{3}$and TiC was obtained.

• Water for future
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• v.20 no.4
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• pp.279-284
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• 1987

An improved mathematical model is presented which will predict the initial minimum dilution and terminal rise height of wastewater discharged from ocean outfalls into density stratified water flowing at an arbitary direction and speed. Solutions are derived for discharge into linearly stratified water, based on three-dimensional experimental work on line plumes in unstratified currents. The effects of current speed, direction, stratification and type of nozzle are discussed, and the model predictions are compared to laboratory experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1496-1499
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• 2004

The paper persents an efficient method of extracting line segment in a grid map. The grid map is composed of 2-D grids that have both the occupancy and orientation probabilities based on the simplified Bayesian updating model. The probabilities and orientations of cells in the grid map are continuously updated while the robot explorers to their values. The line segments are, then, extracted from the clusters using Hough transform methods. The eng points of a line segment are evaluated from the cells in each cluster, which is simple and efficient comparing to existing methods. The proposed methods are illustrated by sets of experiments in an indoor environment.

• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.291-294
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• 2004

본 논문에서는 Smith에 의해 제안된 이중 지연 라인을 갖는 양방향 디지털 도파관 모델을 SDL(sing1e delay line)모델로 변환하여 가야금의 단위 음이 만들어지는 과정을 나타내었다. 각 단계의 시스템은 선형적이며 단일 지연 라인과 LPF로 구성된다. 가야금의 임펄스 응답을 기본 입력신호로 하였으며. 실제 가야금의 조율 시스템인 안족은 선분 적합성을 이용한 근사화 과정을 거쳐 구현하였으며 이를 이용한 모의실험을 하였다. 실제 가야금을 조율하듯 안족에 의한 조율과 실제 음과 유사한 단위 음 생성을 할 수 있었다.

• Journal for History of Mathematics
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• v.17 no.2
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• pp.61-72
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• 2004

In this article we study on didactic transposition and enlargement of the Ceva theorem(if three cevians AX, BY, CZ, one through each vertex of a triangle ABC, are concurrent, then $\frac{BX}{XC}\frac{CY}{YA}\frac{AZ}{ZB}$ = 1). We suggest inverse of the Ceva theorem, some different forms of the Ceva theorem(oriented segment form, trigonometric form, vector form), enlarged the Ceva theorem of polygon and tetrahedron, and in detail propose these proofs.

• Proceedings of the Korean Information Science Society Conference
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• 2006.10c
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• pp.22-27
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• 2006

4단계 스카이라인 영역 결정 기법[2]은 영역 결정 시간이 객체의 개수에 비례해서 현저히 증가하기 때문에 다수의 객체를 포함하는 도메인들에 적용하기 어렵다. 이러한 문제점은 스카이라인 영역이 지배 객체 집합의 부분 집합으로 이루어지는 특성을 고려하지 않았기 때문에 발생한다. 이 논문에서는 스카이라인 영역 결정에 불필요한 객체들을 제거할 수 있는 거리 기반 가지치기 기법과 영역 결정 선분의 범위 축소 기법을 제안한다. 제안한 기법들을 R*-트리와 INN(Incremental Nearest Neighbor) 알고리즘에 적용함으로써 점진적으로 스카이라인 영역을 결정할 수 있으며 영역 결정 시간을 현저하게 감소시킬 수 있다. 제안한 기법의 성능 향상을 증명하기 위해 4단계 영역 결정 기법과의 비교 실험을 수행한다.