• Bulletin of the Korean Mathematical Society
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• v.50 no.6
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• pp.2071-2077
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• 2013

In this paper we consider the existence of smooth conics on a general hypersurface of degree d in $\mathbb{P}^n$.

• Bulletin of the Korean Mathematical Society
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• v.54 no.5
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• pp.1859-1871
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• 2017

We compute the Jordan constant for the group of birational automorphisms of a projective plane ${\mathbb{P}}^2_{\mathbb{k}}$, where ${\mathbb{k}}$ is either an algebraically closed field of characteristic 0, or the field of real numbers, or the field of rational numbers.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07a
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• pp.436-436
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• 2005

We have investigated electro-optical properties of an in-plane switching cholesteric liquid crystal display (LCD). Planar and focal-conic texture changes re induced by application of an in-plane electric field.

• Honam Mathematical Journal
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• v.29 no.3
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• pp.475-480
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• 2007

In this paper we find the point at which the rational B$\'{e}$zier curve has the given tangent direction. We also analyze the geometric properties of the point of quadratic rational B$\'{e}$zier curve.

• Journal of the Korean School Mathematics Society
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• v.17 no.1
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• pp.45-71
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• 2014

In learning the conic session, there is a gap between the curricula of the high school and the university level for the pre-service math teachers. So through the art of problem posing, 38 number of pre-service teachers worked in a pair to find fidelities in the environment of hand-held graphing calculator. We concluded that the cognitive fidelity showed three different properties using "what if not" strategy which the mathematical fidelity between the representations supported. Also, the exploration using a calculator in the pedagogical fidelity strongly helped them to apply and to expand their learning.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.1 s.94
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• pp.253-264
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• 1999

Most autonomous mobile robots view only things in front of them, and as a result, they may collide with objects moving from the side or behind. To overcome this problem. an Active Omni-directional Range Sensor System has been built that can obtain an omni-directional range data through the use of a laser conic plane and a conic mirror. Also, mobile robot has to know its current location and heading angle by itself as accurately as possible to successfully navigate in real environments. To achieve this capability, we propose a self-localization algorithm of a mobile robot using an active omni-directional range sensor in an unknown environment. The proposed algorithm estimates the current position and head angle of a mobile robot by a registration of the range data obtained at two positions, current and previous. To show the effectiveness of the proposed algorithm, a series of simulations was conducted and the results show that the proposed algorithm is very efficient, and can be utilized for self-localization of a mobile robot in an unknown environment.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.5
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• pp.532-537
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• 2015

In this paper, we propose target range estimation method using ghost target in the submarine linear array sonar. Usually, when submarine detect target, they use passive sonar detection to avoid self-disclosure by active sonar transmission. But, originally, passive linear array sonar have limitation for target range estimation and additional processing is required to get target range information. For the case of near-field target, typical range estimation method is using multiple information by multipath effect in underwater environment. Acoustic signal generated from target are propagated along with numerous multipath in underwater environment. Since multipath target signals received in the linear array sonar have different conic angles each other, ghost target is appeared at the bearing different with real target bearing and sonar operator can find these information on the operation console. Under several assumption, this geometric properties can be analysed mathematically and we get the target range by derivation of this geometric equations using measured conic angles of real target and ghost target.

• Journal of the Korean Society of Clothing and Textiles
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• v.21 no.5
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• pp.807-820
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• 1997

This exploratory research was intended to develop and test a slacks pattern based upon conic model. Data came from measurements of photograph of three subjects. Silhouette of slacks was close fit on waist and hip and loose under hip level. This three-dimensional form was modeled with truncated cones. This conic model was truncated by plane of the waist level, the abdomen level, the hip level, the crotch level and the ankle level parallel to the floor. Two models that have differences in back part of the model were tested. Drafted patterns from two models were taken for each subject. Drafted experimental pattern was operated for slacks pattern. The first step was to make sideseam. Parts over crotch level were moved to both sides. And then to make waistdarts. Experimental pattern had two darts each in front and back. Each experimental slacks was evaluated by sensory test to appearance and comfort by five judges. The results can be summarized as follows. 1) Appearance and comfort of experimental pattern were judged to be satisfactory. Especially these patterns were fitted we18 in waist darts front and back. So we evaluated that was proper pattern for slacks. 2) Model 2 was better in appearance than model 1. But Model 1 was more comfortable in non significant difference. This was supposed to be resulted from fit more closely of model 2. 3) considering preceding results, this geometric model based upon truncated cone was applicable for slacks pattern.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.24 no.2
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• pp.217-223
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• 2015

In this paper, the performance of a system was analyzed according to the design parameters of a LED secondary lens that can be applied at a very close range, e.g., for direct lighting or display systems. We designed the secondary lens of the very-close-range LED using an aspheric equation and analyzed its performance-particularly the angle of the beam spread, central luminous intensity, and light uniformity-with respect to the thickness of lens, radius, conic constant, and asphericity (4th). Our analysis shows that four parameters affect the performance. The simulation results indicate an optimal thickness of 1 mm and show that a larger radius yields higher performance. The optimal range for the conic constant was determined as -1.21 to -1.25, the optimal range for the asphericity was determined as 0.0047xx to 0.0049xx (4th).

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.34 no.2
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• pp.171-183
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• 2016

Small-scale maps currently used are made by scanning and editing printed maps and its shortcoming is accumulated errors at the time of editing and low accuracy. TM projection method is used but its accuracy varies. In addition, small-scale maps are made without consideration of usability and compatibility with other scale maps. Therefore, it is necessary to suggest projection and coordinates system improvement methods in consideration of usability and compatibility between data. The results of this study reveal that in order to make the optimum small-scale map, projection that fits the purpose of map usage in each scale, coordinate system and neat line composition should be selected in consideration of interrelation and compatibility with other maps. Conic projection should be used to accurately illustrate the entire country, but considering usability and compatibility with other maps, traversing cylindrical projection should be used instead of conic projection. For coordinates system of the small-scale map, Universal Transverse Mercator (UTM-K) based on the World Geodetic System should be used instead of conventional longitude and latitude coordinate system or Transverse Mercator.