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- 저자 : Sewoong Kwon (검색결과 27 건)
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권세웅(Sewoong Kwon),문현욱(Hyun Wook Moon),오재림(Jae Rim Oh),임재우(Jae-Woo Lim),배석희(Seok-Hee Bae),김영규(Young-Gyu Kim),박정수(Joungsoo Park),윤영중(Young Joong Yoon) 한국전자파학회 2009 한국전자파학회논문지 Vol.20 No.5
본 논문에서는 개선된 가시 트리 구조와 가시면 검색을 위해 효율적인 방법을 적용한 광선 추적법을 제안한다. 비슷한 특성을 갖는 트리의 노드를 재생성하지 않는 개선된 가시 트리 구조를 사용하였으며, 가시면 판별을 위해 묶음 광선(packet ray) 개념 검사점을 비균일하게 분포시키는 방법으로 경로 탐색 성능을 개선하였다. 충돌검사에서 묶음 광선를 사용함으로써 3.3배의 속도 개선을 이루었으며, 비균일 검사점 분포를 통해 1.11배의 성능향상을 이루었다. 본 광선추적법을 적용한 결과의 경우, 경로 손실에서 RMS 에러가 1.9 ㏈ 발생하여 높은 정확도를 제공할 수 있음을 보였다. In this paper, we proposed an improved ray tracing method with an amelioration of visible tree structure, a visible face determination method, and non-uniform random test point method. In a proposed visible tree structure, it reduces tree nodes by means of merging similar nodes. In a visible face determination method, it shows that a ray hit test with a packet ray method can reduce a test time. A ray tracing method involving with a packet ray hit test method can improve a tree construction time up to 3.3 times than a ray tracing method with a single ray hit test method. Furthermore, by seeding a non-uniform and random test point on a face, tree construction time is improved up to 1.11 times. Received powers from the proposed ray tracing results and measured results have good agreement with 1.9 ㏈ RMS error.
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도심 환경에서 전파 특성 모의 해석을 위한 신호 독립 부트리 방법에 대한 연구
권세웅(Sewoong Kwon),문현욱(Hyun Wook Moon),오재림(Jae Rim Oh),윤영중(Young Joong Yoon) 한국전자파학회 2010 한국전자파학회논문지 Vol.21 No.3
본 논문에서는 도심과 같이 전기적으로 큰 환경에서 광선 추적법의 광선 추적을 통한 트리 구성 및 부트리 사용에 있어서 부트리 재사용을 통한 트리 생성 효율을 높이기 위해 신호원 독립 부트리 방법을 제안하였다. 신호원 독립 부트리 방법의 적용 결과, 피코셀 및 마이크로셀에서의 노드 개수가 트리 깊이 6에서 100배 감소하는 것을 확인하였으며, 노드 재사용 효율 분석을 통해 송신 위치가 변해도 전체 노드 중 88~98 %가 재사용되는 것을 확인하였다. 그러므로 제안된 신호원 독립 부트리 적용을 통해 광선 추적법 성능 개선은 물론 다중 안테나 또는 기지국 최적화와 같은 다중 송신기 사용 시 노드 재사용으로 인한 성능 개선에 유용하다. In this paper, a SIT(Source Independent Tree) method for ray tracing is proposed to enhance the efficiency of tree construction with reuse of sub tree in urban environment, As the SIT method is applied, the decrease of the number of nodes for picocell and microcell simulations is 100 times. And 88~98 % of the total nodes are reused with change of location of signal source from an analysis of node reuse efficiency. Therefore the proposed SIT method is useful in performance enhancement of ray tracing, especially, for multiple antenna simulation like as MIMO system and cell planning.
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장거리 다기능 레이더에서 기상에 의한 고도 탐지 정확도 영향 분석 연구
권세웅(Sewoong Kwon),이종현(Jong-hyun Lee),권양원(Yangwon Kwon),이기원(Kiwon Lee),김한생(Han Seng Kim),선웅(Woong Sun) 한국전자파학회 2014 한국전자파학회논문지 Vol.25 No.1
고도 탐지 정확도는 장거리 다기능 레이더 등에서 필수적으로 분석되어야 하는 성능이지만, 기상 등 대기 현상에 의한 영향이 크기 때문에 정확한 분석이 어렵다. 따라서 고도에 따른 굴절율을 사용하여 보상을 수행하는데, 본 논문에서는 고층 기상에 의한 대기 굴절율을 고려할 수 있는 광선 추적 모의환경을 구축하고, 실환경 굴절율과 모델링된 굴절율을 각각 고려하여, 모델링된 굴절율을 실환경에 적용시 발생할 수 있는 고도 오차를 분석하였다. 모델링된 굴절율을 이용하여 고도 오차 보상값을 산출하였으며, 보상에 의한 결과를 모델링하여 고도 보상시 발생할 수 있는 고도 정확도를 정규함수로 모델링하여 통계적으로 분석하였다. This paper presents an altitude detection accuracy for long range and multifunction radar. The accuracy is difficult to estimate because it is affected by an time varying atmosphere refractivity. We analyze altitude accuracy with a raytracing simulator with atmosphere refractivity. An altitude error is simulated with measured and modeled refractivity, and the modeled refractivity is used for compensate an altitude accuracy. As a result, the error is modeled with normal distribution function, and analyzed.
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Hyun Wook Moon,Sewoong Kwon,Jong Hyun Lee,Young Joong Yoon 한국전자파학회JEES 2010 Journal of Electromagnetic Engineering and Science Vol.10 No.4
In this paper, an interference analysis method with a site-specific path loss model for a wireless personal area network (WPAN) is proposed. The site-specific path loss model is based on geometrical optics and geometric probability to consider both site-specific radio propagation characteristics and a closed-form expression to obtain the mean interference from which the uniformly distributed multiple interferers are derived. Therefore, the proposed interference analysis method can achieve more computational simplicity than the Monte-Carlo (MC) simulation, which uses the ray-tracing (RT) technique. In addition, better accuracy than the conventional interference analysis model that uses stochastic method can also be achieved. To evaluate the proposed method, a signal to the interference-noise ratio with a mean interference concept for uniformly distributed interferers is calculated and compared in two simulation scenarios. As a result, the proposed method produces not only better matched results with the MC simulation using the RT technique than the conventional interference analysis model, but also simpler and faster calculation, which is due to the site-specific path loss model and closed-form expression for interference calculation.
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Association between brain lateralization and mixing ability of chewing side
Lee, Seung-Min,Oh, Sewoong,Yu, Sung Jin,Lee, Kyung-Min,Son, Sung-Ae,Kwon, Young Hoon,Kim, Yong-Il Association for Dental Sciences of the Republic of 2017 Journal of Dental Sciences Vol.12 No.2
<P><B>Background/purpose</B></P><P>Previous studies have suggested that functional dominance in one part of the body can be correlated with functional dominance in another part. Thus, the present research aimed to determine whether brain laterality (handedness, footedness, earedness, and eyedness) was related to mixing ability and chewing side preference.</P><P><B>Materials and methods</B></P><P>Fifty-four volunteers who were not undergoing any form of dental treatment took part in this study. Self-defined brain laterality was determined through a questionnaire. The volunteers performed five tasks related to brain laterality, which was identified by the side used to perform three or more of the five tasks. Chewing side preference was determined by observing the main gum location on the occlusal area when volunteers chewed for 30 strokes. Mixing Ability Index (MAI) was measured by analyzing the degree of mixing of two differently colored waxes (height, 3 mm; diameter, 20 mm). Occlusion contact area was measured by taking the maximum intercuspation bite with polysiloxane.</P><P><B>Results</B></P><P>Thirty-nine volunteers (72%) showed significant agreement between brain dominance and chewing preference side. The association between brain dominance and MAI was not significant. The occlusal contact area of the dominant side (mean = 48.2 mm<SUP>2</SUP>) was significantly wider than that of the nondominant side (25.7 mm<SUP>2</SUP>).</P><P><B>Conclusion</B></P><P>Brain laterality can be explained by the side of functional (preference of the hands, eyes, ears, and feet, and survey) has a positive correlation with chewing preference side. MAI between the brain dominant and nondominant sides was not significant. This shows that mastication efficiency does not differ between dominant and nondominant sides. So, this study suggests that brain dominance is correlated with chewing preference, but it does not affect efficiency of mastication.</P>
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