• Digital Contents
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• no.12 s.139
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• pp.90-92
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• 2004

국내 최초의 줌인, 줌 아웃과 자유로운 카메라 회전이 가능한 FULL 3D MMORPG ‘라그하임’의 제작사인 나코인터랙티브가 드디어 차기작을 선보였다. ‘라스트카오스’가 바로 그 주인공. 오픈베타 서비스 시절‘포스트 리니지’로 각광받았던 라그하임이 정작 상용화에서 쓴잔을 마셨던 만큼 같은 실수는 되풀이하지 않겠다는 게 나코의 각오다. 5차 클로즈베타 서비스를 마친 라스트카오스를 살펴봤다.

• Proceedings of the KIPE Conference
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• 2019.11a
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• pp.1-3
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• 2019

본 논문에서는 전차원 관측기를 이용한 유도기의 센서리스 운전에서 제정수 오차가 제어 성능에 미치는 영향을 수식적으로 분석하였다. 주파수 응답 함수를 이용해 실제 자속과 추정 자속의 관계를 운전 속도와 슬립 주파수의 함수로 나타내었다. 적응(adaptive) 법칙을 이용하여 추정 속도를 수식에서 제거하였다. 또한 각오차가 존재하는 상황에서 전류 운전점 변화를 고려하여 슬립 주파수를 토크 지령으로 변환하였다. 결과적으로 모든 운전 속도와 토크 지령에 대해서 임의의 제정수 오차가 시스템의 안정도, 속도 오차 및 토크 오차에 미치는 영향을 계산할 수 있는 수식을 구하였다. 기존의 분석 방법들이 많은 시뮬레이션과 실험을 통해 제정수의 영향을 평가했던 것과 달리, 구해진 수식에 근거하여 계산을 통해 빠르게 주어진 센서리스 운전 방법을 평가할 수 있는 방법을 제공하였다. 제안된 분석 방법은 시뮬레이션과 실험을 통해 검증되었다.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.3
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• pp.155-162
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• 2004

This paper presents the fabrication procedure and the experiments for the 3-axis fine positioning stage proposed in［1］. First, the dynamic characteristics of the actuator and the stage are tested with the preload changed in order to validate the stage design specifications. Secondly, the performance of the stage is also evaluated on the accuracy associated with linear positioning, angular error, and straightness error. Experimental results show that the developed stage is accurate enough to be used for nanometer positioning. Through the analysis and experiment, the developed fine positioning stage are found to have a long stroke due to the magnetically preloaded PZT actuators, the minimum motion crosstalk due to the use of a ball contact mechanism and the compact design.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.30 no.4
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• pp.363-368
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• 2012

The result of the line simplification algorithm varies with the choice of algorithms, the change in tolerance and the selection of target objects. Three of the algorithms used in this study are Sleeve-fitting, Visvalingam-Whyatt, and Bend-simplify. They were applied to the three kinds of objects which were buildings, rivers, and roads with the five degrees of the tolerance. Through this experiments the vector displacement, the areal displacement, and the angular displacement were measured and the qualitative analysis was performed with the trend line of the errors. The experimental results show that errors were differ from tolerance values, and characteristics of line simplification algorithms based on changes of tolerance were understood.

• Journal of Astronomy and Space Sciences
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• v.9 no.1
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• pp.69-88
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• 1992

The effects of the ionosphere on the radio wave propagation are scattering of radio waves, attenuation, angle error, ranging error, and time delay. If ionospheric conditions are suitable, the charged particles can remove energy from radio waves and thus attenuate the signal. Also, a radio wave traveling a path along which the electron density is not constant undergoes changes in direction, positon and time of propagation. The present study is based on Korean ionospheric data obtained at the AnYang Radio Research Institute from Jan. 1985 through Oct. 1989. The data are used to simulate the Korean ionosphere following the Chapman law. The effects of the model ionosphere on the radio wave propagation, such as the angle, position error, time delay, and the attenuation, are studied for the various cases of the wave frequency and the altitude.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.417-418
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• 2007

• Digital Contents
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• no.2 s.129
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• pp.28-37
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• 2004

희망찬 새해가 다시 붉게 타올랐다. 다사다난했던 2003년을 힘들게 보내야했던 정보통신업계로선 새해를 맞는 감회가 유달리 새롭다. 매년 새해가 되면 장밋빛 희망과 새로운 각오를 품게 되지만, 2004년 새해에 거는 기대는 여느 때와는 다르다. 무엇보다 지난해 정부가 발표한 차세대 성장동력 과제들을 본격적으로 육성하는 원년이기 때문이다. 2007년 이내에 세계 5대 디지털콘텐츠 강국으로 부강하겠다는 정부의 야심찬 포부를 이루기 위해 첫 단추를 메는 올해 정보통신부를 비롯해 과학기술부 · 문화관광부 등 디지털콘텐츠 육성사업의 주무부처가 계획하고 있는 사업 내용을 살펴봤다.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.34-42
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• 2008

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.4
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• pp.213-217
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• 2004

A current transformer(CT) used for the estabilishment of high current national standard, has generally very small ratio error and phase angle error. Both the errors of CT depend critically on the external burden used. When both the ratio and phase angle errors at two different burdens including zero burden are known, those at any other burdens are calculated theoretically. The theoretical values are well consistent with the experimental results within the $82{\times}10$-6, implying the measurement system of CT in KRISS is well maintained.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.4
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• pp.159-166
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• 2005

This study deals with the correction of gear tooth profile error by finish roll forming. First, we experimentally confirmed that the tooth profile error is a synthesis of the concave error and the pressure angle error. Since various types of tooth profile errors appear in the experiments, we introduced evaluation parameters for rolling gears to objectively evaluate profile quality. Using these evaluation parameters, we clarified the relationship among the tooth profile error, the addendum modification factor (A. M. factor), and the tool loading force. We verified the character of concave error, pressure angle error, tool loading force and number of cycles of finish roll forming by using a forced displacement method. This study makes clear that tool loading force and number of cycles of finish roll forming are very important factors that affect involute tooth profile error. The results of the experiment and analysis show that the proposed method reduces concave and pressure angle errors.