• 한국공간정보시스템학회 논문지
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• 제7권2호
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• pp.67-79
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• 2005

RFID 시스템에서 태그의 위치를 추적하기 위해서 궤적은 모델링되고 색인되어야 한다. 궤적은 태그가 판독기의 인식영역으로 들어갈 때와 나갈 때 보고되는 두 개의 시공간 위치를 연결한 선분으로 표현될 수 있다. 만약 태그가 판독기의 인식영역에 들어와 나가지 않으면 시공간 위치는 오직 태그가 인식영역에 들어올 때만 보고된다. 따라서 판독기에 머물고 있는 태그는 궤적을 표현할 수가 없으므로 질의 시 이러한 태그를 검색할 수 없다. 이러한 문제를 해결하기 위하여 이 논문에서는 태그의 궤적을 간격으로 정의하고 새로운 색인인 Interval R-tree를 제안한다. 또한 효율적인 질의처리를 위한 새로운 삽입 및 분할 알고리즘을 제안한다. 마지막으로 제안된 색인을 구현하여 다양한 데이터 집합에서 R-tree와 R*-tree와 성능을 비교하여 우수성을 입증한다.

• 정보처리학회논문지A
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• 제19A권3호
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• pp.147-154
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• 2012

창의력이나 문제해결력과 같은 고차원적인 사고 능력은 주어진 문제의 정 오답만으로는 진단이 어려우며, 진단을 위해서는 교수자가 학습자의 문제 해결 과정을 지켜보거나 해결 과정에 대한 학습자의 보고 과정이 요구된다. 더구나 교수자의 학습자에 대한 관찰이 불가능한 온라인 학습이나 버추얼 클래스와 같은 환경에서는 학습자의 문제 해결 과정을 평가하거나 학습자 스스로 자신의 부족한 부분을 진단하는 것은 더욱 어려워진다. 이러한 문제를 해결하는 최선의 방법은 학습자가 문제를 해결하는 동안을 추적하여 그 과정을 보고해 주는 것이라 할 수 있다. 본 연구에서는 MS 오피스군의 소프트웨어를 활용하여 주어진 문제를 해결하는 동안 학습자의 작업 내역을 트레이싱하여 최종적으로 학습자에게 자신의 부족한 부분을 진단해 주고 자신의 능숙도와 소프트웨어를 응용하여 주어진 문제를 해결하는 과정에 대한 평가를 해주는 모듈을 개발하였으며, 본 진단 모듈의 효용성 평가를 위하여 실제 MOS 시험을 준비하는 학습자 81명에 대한 적용 및 만족도 조사를 통하여 통계적으로도 유의미한 효과가 있음을 확인하였다.

• 대한조선학회지
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• 제10권2호
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• pp.19-28
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• 1973

This paper deals with a problem for determining the bulbous bow ship from which pertains to the study of the theoretical ship form planing method. In this paper has been determined the bulbous bow ship form which is a similar in geometric particulars with the conventional liner ship G.T.10, 000 by adopting the variable method for finding the optimum ship form by A.Y.C. Lee and the streamline tracing method by T. Inui and P.C. Pien. Each resistance performance is examined by the towing test and is compared with one another. The followings are the outcome of this study: Among the 5 type models, the bulbous bow ship form M.S. B 1120 is the most excellent for the resistance performance. The effect for the wave resistance is very sharp according to the difference of the bottom flattening of theoretical ship form. The optimum value of the bulbous bow for wave resistance can be obtained by the variable method mentioned above, and for the series of(Main hull+Bulb)opt., ${\alpha}=75/25$, the value is $f{\approx}0.11$.

• Journal of information and communication convergence engineering
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• 제8권2호
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• pp.163-167
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• 2010

In underwater acoustic communication, acoustic signals from transducers or hydrophones are used. And the underwater acoustic communication channels are very complicated, because of vertical distribution of acoustic velocity according depths, and reflections from boundaries like as surface or bottom. For the implementation of the underwater acoustic communication channel, the image method or ray tracing method have been used. In this paper, we introduce a new approach for implementation of underwater acoustic communication channel using the simulation of the Transmission Line Matrix Modeling and cross-correlations from the input and output signals.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.104-107
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• 2002

Direct Metal Manufacturing (DMM) is a new additive process that aims to take die making and metalworking in an entirely new direction. It is the blending of five common technologies : lasers, computer-aided design (CAD), computer-aided manufacturing (CAM), sensors and powder metallurgy. The resulting process creates parts by focusing an industrial laser beam onto a tool-steel work piece or platform to create a molten pool of metal. A small stream of powdered tool-steel metal is then injected into the melt pool to increase the size of the molten pool. By moving the laser beam back and forth, under CNC control, and tracing out a pattern determined by a computerized CAD design, the solid metal part is built line-by-line, one layer at a time. DMM produces improved material properties in less time and at a lower cast than is possible with traditional fabrication.

• 천문학회보
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• 제41권2호
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• pp.35.2-35.2
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• 2016

Lyman alpha photons emitted from the early generation galaxies are scattered through the intergalactic medium, and can be observed as Lyman alpha emitting sources. We examine the Lyman alpha line transfer mechanism by tracing the random scattering histories of Lyman alpha photons in the intergalactic medium of the early universe. The density and ionization fields are based on the 3D map by N-body + radiation transfer simulations of the epoch of reionization. The calculation is compared with analytical models, too. The emergent line profile and the size of the Lyman alpha blob are strongly tied to the density and ionization environment, likely to give constraints when high-z Lyman alpha blobs are observed.

• 전자공학회논문지S
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• 제34S권11호
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• pp.1-8
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• 1997

A prediction model is proposed to describe the path loss in propagation environment of indoor microcell. This model includes the lineal corridor for line--of-sight(LOS) and T-shaped corridor for non-line-of-sight(NLOS). In computation of receiving power the ray tracing technique based on image method is utilized and also reflected waves bounced on the walls and ceilings are considered. To check validity of the computed resuls cross checks between the predicted and measured are being made, which shows a close agreement for LOS case whereas somewhat disagreement for NLOS case. UTD technique is incorporated with propagation path determination algorithm in the treatment of NLOS case.

• 한국ITS학회 논문지
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• 제10권3호
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• pp.64-73
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• 2011

본 논문에서는 모서리 검출을 이용하여 추출된 모서리를 추적함으로써 차선을 검출하고 추적하는 알고리즘을 제안한다. 제안하는 알고리즘은 양 차선이 연속되지 않고 끊긴 형태로 존재하거나 교차되는 등의 다양한 차선의 형태에도 높은 추출률을 보이는 장점을 가지고 있다. 이는 이러한 형태의 차선의 비율이 높은 시내도로 와 국도에서의 차선 추출에 보다 유리하다. 이러한 점을 증명하기 위해 테스트는 주로 불연속적이고 교차되는 형태의 차선이 많은 도로에서 실시하였고 평균 87% 이상의 추출률을 보여주었다.

• 한국CDE학회논문집
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• 제8권3호
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• pp.150-156
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• 2003

Direct Metal Deposition (DMD) is a new additive process producing three-dimensional metal components or tools directly from CAD data, which aims to take mold making and metalworking in an entirely new direction. It is the blending of five common technologies: lasers, CAD, CAM, sensors and materials. In the resulting process, alternatively called laser cladding, an industrial laser is used to locally heat a spot on a tool-steel work piece or platform, forming a molten pool of metal. A small stream of powdered tool-steel metal is then injected into the metal pool to increase the size of the molten pool. By moving the laser beam back and forth, under CNC control, and tracing out a pattern determined by a computerized CAD design, the solid metal part is eventually built line-by-line, one layer at a time. DMD produces improved material properties in less time and at a lower cost than is possible with traditional fabrication technologies.

• 전자공학회논문지B
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• 제30B권6호
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• pp.76-85
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• 1993

In this paper, we propose a stroke matching method for the off-line recognition of handprinted Hangul. In this method, the preprocessing steps such as position normalization, contour tracing and thinning are carried out first. Then, after extracting features such as the firection component distribution of contour, the direction component distribution of skeleton, and the distribution of structural feature points, strokes are extracted and matched based on the midpont distribution of the direction and the length of each stroke. In order to reduce the recognition time, a preliminary classification based on the direction component distribution features of the contour is performed. In order to domonstrate the performance of the proposed method, experiments with 520 most frequently used Hangul were performed, and 90.7% of correct recognition rate and 0.46second of recognition time per one character has been obtained. This results reveal that the proposed method can absorb effectively the noise in input character and the variations of stroke slant.