• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.6D
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• pp.663-673
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• 2009

Driver's perceived curve radius is different from actual curve radius at curve sections. This is called visual distortion. It has effect on operation speed according to driver's perception and finally bad effect on safety at curve sections. At present, however, there is no research on quantitatively analysis of visual distortion and no criteria for curve section design considering the visual distortion. Therefore, this study focus on finding degree of visual distortion and suggesting design criteria by visual distortion analysis. The process of this study is as below; First, a calculaiton model of perceived curve radius was developed by survey using computer simulation. In this model, a dependent variable is perceived curve radius and an independent variable is geometric factors. Second, degree of visual distortion was calculated from ratio of perceived curve radius to actual curve radius. Finally, design criteria were suggested through influencing factor analysis of visual distortion at curve sections.

• Review of KIISC
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• v.3 no.1
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• pp.86-90
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• 1993

Finite field GF$(2^n)5에서 정의된 elliptic curve가 있을때 그 curve위의 어떤 point p를 k배하는 연산은 암호론에서 매우 자주 쓰여진다. 이때 optimal normal bases를 이용하여 GF$(2^n)의 element를 표현하고, 또 elliptic curve를 선택할 때 animalous curve가 되도록 한다면, 기존이 방법 보다 매우 빠르게 k P를 구할 수 있다.

• Journal of the Korean School Mathematics Society
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• v.3 no.2
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• pp.165-176
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• 2000

This note introduces elliptic curve cryptosystems and related algorithms and gives an elliptic curve cryptosystems practice program made with Javascript. We can find the practice program at author′s homepage "http://my.dreamwiz.com/math88". It is useful for students to study about elliptic curve cryptosystems.

• Korean Journal of Computational Design and Engineering
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• v.3 no.2
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• pp.113-120
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• 1998

Calculation of intersection points by two curves is fundamental to computer aided geometric design. Bezier clipping is one of the well-known curve intersection algorithms. However, this algorithm is only applicable to Bezier curve representation. Therefore, the NURBS curves that can represent free from curves and conics must be decomposed into constituent Bezier curves to find the intersections using Bezier clipping. And the respective pairs of decomposed Bezier curves are considered to find the intersection points so that the computational overhead increases very sharply. In this study, extended Bezier clipping which uses the linear precision of B-spline curve and Grevill's abscissa can find the intersection points of two NURBS curves without initial decomposition. Especially the extended algorithm is more efficient than Bezier clipping when the number of intersection points is small and the curves are composed of many Bezier curve segments.

• Proceedings of the KIEE Conference
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• 1998.07c
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• pp.964-966
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• 1998

The TC curve of recloser which used in KEPCO's distribution line is a little different in a pattern with the TC curve of sub-station OCR. So it sometimes fails in protection coordination. And the recloser sometimes does mis-open/close owing to the inrush current of CB reclosing when a fault occurred on the source-side of the recloser. The mis-open/close is another trouble maker. This Paper Present a new delay TC curve of recloser which has the same pattern with the TC curve of OCR, and a new instantaneous TC curve of recloser which doesn't mal-function to the inrush current. In addition, this paper present another two TC curves for the serial positioning of 2 reclosers. So we accomplished the simple protection coordination of OCR-recloser-fuse.

• Computers and Concrete
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• v.4 no.6
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• pp.425-436
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• 2007

This study is mainly focused on applying Fuller's ideal gradation curve to theoretically design blended ratio of all solid materials of a reactive powder mortar (RPM), also known as reactive powder concrete (RPC), with the aid of error function, and then to study the effect of fly ash/slag on the performance of RPM. The solid particle is assumed to be spherical particles. Then, the void volume of paste ($V_{\nu}$) and the paste content with specific quality can be obtained. As conclusion, under Fuller's ideal grading curve, the amount of fly ash/slag mixture is higher than that with silica fume along due to it better filled the void within solid particle and obtains higher packing density.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.12
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• pp.1984-1994
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• 1989

Techniques for approximating digitalcurves by polygonal lines are a valuable tool for image analysis and data compression. S. Shilien proposed a method for segmenting a digital curve into digital straight line segments digital straight line segments which are not satisfied with the structural properties, and have more than one break point by Shilien's method. Here, the structural representation of digital straight lines and digital staight line segments is described. And a method for segmenting a digital curve into digital straight line segments which are not satisfied with the structural properties, and have more than one break point by Shilien's method. Here, the structural representation of digital straight lines and digital staight line segments is described. And a method for segmenting a digital curve into digital straight line segments which may be not satisfied with the structural properties is proposed. The number of break points extracted by this method is less than that by S. Shilien's method from the digital curve which includes the digital straight line segments not satisfied with the structural properties.

• Journal of Astronomy and Space Sciences
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• v.17 no.2
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• pp.181-188
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• 2000

DO Cas is a short period (P=0.68day) eclipsing binary star and is classified as a near-contact binary by Shaw(1990). There is no published radial velocity curve for this short period binary after Mannino(1958). Hill(1991) suspected that Mannino's radial velocity curve had some serious mistake. So, we scanned the original plates used by Mannino with PDS and the spectra were employed to IRAF packages to estimate the radial velocities. The radial velocity curve and the BVR light curves made by us in 1998 were analyzed simultaneously with Wilson-Devinney code. We found that DO Cas is a contact or near-contact binary which the primary component fills its Roche lobe and we also estimated the absolute dimensions of each components of this system.

• Korean Journal of Digital Imaging in Medicine
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• v.17 no.1
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• pp.9-12
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• 2015

임상용 모니터의 출력값 중 가장 큰 영향을 주는 것이 휘도이다. 최근 컬러 모니터의 임상용 사용으로 인해 출력값의 보정은 매우 중요하게 관리되고 있다. 색보정 변위의 특성화가 휘도와 동일한 인자로 영향을 주는지 분석하기 위해 사용된 특성화 보정 모델은 GOG모델과 S-curve모델 이다. 두 개의 모델을 통해 모니터의 휘도는 장치의 출력과 직접적인 관계가 있다는 것을 증명하고 동일한 출력에 입력값을 가질 수 있도록 구성하고자 한다. 동일한 출력을 디스플레이 할 경우 동일한 출력값을 얻어야 한다. 그러나 모니터에 따라 서로 다른 출력값을 산출한다. 컬러모니터의 경우는 출력의 안정성에 휘도뿐만 아니라, 색감(R,G,B) 변화가 큰 역할을 수행한다. 본 연구에서는 분석인자 중 대조도에 영향을 주는 인자를 역추적하여 특성화 보정 S-curve모델을 LCD에 적용하였다. 이는 GOG모델을 적용한 CRT와 동일한 결과를 얻었다. 따라서 인자는 CIEXYZ의 결과값과 동일한 인자를 구할 수 있다.

• Bulletin of the Korean Mathematical Society
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• v.50 no.5
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• pp.1599-1622
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• 2013

We show many examples of curves on the unit 2-sphere $S^2(1)$ in $\mathbb{R}^3$ and the unit 3-sphere $S^3(1)$ in $\mathbb{R}^4$. We study whether its curves are Bertrand curves or spherical Bertrand curves and provide some examples illustrating the resultant curves.