• Proceedings of the Korean Information Science Society Conference
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• 2002.04a
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• pp.589-591
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• 2002

본 논문에서는 메쉬 구조의 다중처리시스템을 위한 새로운 할당방법을 제안한다. 이 할당방법은 다른 가용 서브메쉬와 중첩되지 않는 독립 가용 서브메쉬를 유형에 따라 분류하여 유형별 가용 서브메쉬 리스트를 생성한다. 그리고 태스크의 유형에 따라 해당 유형별 가용 서브메쉬 리스트에서 최적할당이 가능한 서브메쉬를 찾음으로써 서브메쉬를 탐색하는데 소요되는 시간을 줄인다. 이 때 서브메쉬를 찾지 못하면 확장지수를 이용하여 더 큰 가용 서브메쉬를 형성한 후 할당함으로써 태스크의 대기 시간을 줄이고, 이 결과로 외적단편화를 줄이는 효과도 얻는다. 또한 할당 해제시 독립 가용 서브메쉬는 다른 가용 서브메쉬의 크기 에 변화를 주지 않기 때문에 그 유형에 따라 유형별 가용 서브메쉬 리스트에 삽입한다. 그럼으로써 할당 해제 후 유형별 가용 서브메쉬 리스트를 재생성하기 위해 전체 메쉬 구조를 탐색 할 필요가 없어진다.

• Journal of Korea Multimedia Society
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• v.6 no.5
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• pp.769-777
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• 2003

We present a striping technique that MPEG-1 video streams ell a disk array can be efficiently played back at different resolution levels. For the MPEG-1 compression algorithm, the proposed multi-level encoding technique first partitions the parent video stream in the temporal dimension. Each frame in the sub-stream is then Partitioned in the chroma dimension yielding a low resolution and a residual component. The multimedia server stores blocks of different components on consecutive disks in a round robin manner. As a result, the lower the resolution level being maintained, the smaller is the number of disks accessed by each client. To effectively utilize a disk array and to maximize the number of clients that can be serviced simultaneously, the proposed technique interleaves the storage of the component of sub-streams among the disks in the array We empirically validate and evaluate this striping technique through simulation in order to show the improvement of its performance on the server.

• Korean Journal of Remote Sensing
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• v.20 no.2
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• pp.125-137
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• 2004

In case of using image sequence taken from a moving camera along a road in an urban area, general video mosaicing technique based on a single baseline cannot create 2-D image mosaics. To solve the drawback, this paper proposed a new image mosaicing technique through 3-D multi-baselines that can create image mosaics in 3-D space. The core of the proposed method is that each image frame has a dependent baseline, an equation of first order, calculated by using ground control point (GCP) of optical flows. The proposed algorithm consists of 4 steps: calculation of optical flows using hierarchical strategy, calculation of camera exterior orientation, determination of multi-baselines, and seamless image mosaics. This paper realized and showed the proposed algorithm that can create efficient image mosaics in 3-D space from real image sequence.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.62.2-62.2
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• 2010

박막 실리콘 태양 전지는 저가격화 및 대량생산, 대면적화에 유리하다는 장점을 가지고 있다. 단점으로 지적되는 낮은 효율을 극복하기 위해 광흡수층의 밴드갭이 서로 다른 두 개 이상의 박막을 적층하여, 넓은 파장 대역의 빛을 효과적으로 흡수함으로써 광변환 효율을 올리기 위한 많은 연구가 이루어지고 있다. 서로 다른 밴드갭의 광흡수층을 가진 p-i-n 구조를 다중 적층하여 고효율의 태양 전지를 제작하기 위해서는 n-도핑층과, p-도핑층 간에 전자와 정공이 빠르게 재결합할 수 있는 터널 접합(Tunnel Recombination Junction)의 형성이 필수적이며, 이때 광손실이 최소화되도록 해야한다. 만약 터널 접합이 적절하게 형성되지 않으면 결합되지 않은 전자와 정공이 도핑층 사이에 쌓이게 되고, 도핑층 사이의 저항 증가로 태양 전지의 광변환 효율은 크게 하락한다. 이번 연구에서는 터널 접합이 잘 이루어지게 하기 위한 n-도핑층 및 p-도핑층 박막의 특성과, 터널 접합의 특성에 따른 적층형 태양 전지의 광효율 변화를 확인하였다. 광흡수층 및 도핑층은 TCO($SnO_2:F$, Asahi) 유리 기판 위에 PECVD를 사용하여 p-i-n 구조로 RF Power 조건에서 증착되었고, ${\mu}c$-Si 광흡수층의 경우에는 VHF Power 조건에서 증착되었다. 광흡수층이 a-Si/${\mu}c$-Si의 구조를 가지는 이중 접합 태양 전지에서 ${\mu}c$-Si n-도핑층/${\mu}c$-Si p-도핑층 사이의 터널 접합 실험 결과 n-도핑층 및 p-도핑층의 결정화도와 도핑 농도를 조절하여 터널 접합의 저항을 최소화했고, 터널 접합 특성이 이중 접합 셀의 광효율 특성과 유사한 경향을 보임을 확인하였다. 광흡수층이 a-Si/a-SiGe/${\mu}c$-Si의 구조를 가지는 삼중 접합 태양 전지 실험의 경우 a-Si과 a-SiGe 광흡수층 사이에 ${\mu}c$-Si n-도핑층/${\mu}c$-Si p-도핑층/a-SiC p-도핑층의 구조를 적용하여 터널 접합을 형성하였으며, ${\mu}c$-Si p-도핑층의 두께 및 박막 특성을 개선하여 광손실이 최소화된 터널 접합을 구현하였고, 삼중 접합 태양 전지에 적용되었다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1A
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• pp.37-52
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• 2004

In this paper, Multistage Adaptive Partial PIC eliminating effectively the multiple access and multipath interference for DS-CDMA based W-CDMA uplink system is designed and its performance is evaluated with computer simulation. By adaptively controlling the slope of the soft limiter with received signals, the efficiency of the soft limiter can be maximized and the better performance is obtained by solving error floor problem using further precise generation of interference signal. As a result, The proposed Multistage Adaptive Partial PIC with simple optimizing method for time-variant channel showed optimum performance at fewer stages. Besides fewer stages, the interference cancellation at the output of the rake receiver considerably reduced system complexity. The Multistage Adaptive Partial PIC with precise generation and efficient cancellation of interference signal can solve error eoor problem, resulted from initial false detection and improve system performance of high data rate system.

• Journal of Navigation and Port Research
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• v.34 no.10
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• pp.727-733
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• 2010

An estimation algorithm of collision risk among multiple ships has been developed in order to reduce human error and prevent collision accidents. The algorithm is designed to calculate the collision risk among ships based on Fuzzy theory by using AIS data as traffic information. In this paper, to validate the algorithm, the AIS data of actual collision accident, which occurred between a product carrier and a cargo carrier in Busan harbor in 2009 are collected. The replay simulation is carried out on the actual AIS data and the collision risk is calculated in real time. In this paper, the features of the estimation algorithm of collision risk and the results of replay simulation based on AIS data of actual collision accident are discussed.

• Journal of Convergence for Information Technology
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• v.7 no.2
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• pp.59-65
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• 2017

In order to realize the operation of the creative modular toy, it is required to record the motion and to read and repeat the motion. At this time, a control potentiometer is used to read the absolute angle of rotation of the toy motion output shaft. However, the unstable part of the sensing area of the potentiometer is present in a certain region, which may lead to instability of the motor control. In this paper, we propose an algorithm to find the absolute angle of one rotation by reading two stable potentiometers on one axis and reading each stable region. We also describe the correction algorithm that is needed to perform multiple rotations. The proposed method is applied to Topobo modular toys to record the operation and perform iterative operation. In addition, multi-turn operation is recorded and operated to suggest the usefulness of the proposed method. In the future, we will expand the functions of recording and playback through various actions.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.151-160
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• 2004

In the present study, Loop scheme is applied to generate smooth surfaces. To be consistent with the limit points of target surface, the initial sampling points are properly rearranged. The pointwise errors of curvature and position in the sequence of subdivision process are evaluated in the Loop subdivision scheme. A first-order shear deformable Loop subdivision triangular element which can handle transverse shear deformation of moderately thick shell are developed. The developed element is more general than the previous one based on classical shell theory, since the new one includes the effect of transverse shear deformation and has standard six degrees of freedom per node. The quartic box spline function is used as interpolation basis function. Numerical examples for the benchmark static shell problems are analyzed to assess the performance of the developed subdivision shell element and locking trouble.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.23 no.8
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• pp.2042-2051
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• 1998

VBR compressed, pre-recorded video is known to exhibit significant, multiple time-scale bit rate variability. To reduce the variability and burstiness of the aggregated transmission rate as low as possible, in this paper, we present an adaptive bandwidth smoothing algorithm, that can be effectively applicalble for VoD services over a shared-medium channel. For these environments where many clients are connected to a single server, by introducing the conventional MVBA(minimum variability bandwidth allocation) algorithm and controlling adaptively the conventional MVBA(minimum variability bandwidth asllocation) algorithm and controlling adaptively the aggregated transmission rate whenever a new clients request is arrived at the server side, the proposed algorithm effectively reduces the burstiness and variability of the aggregated transmission rate. Through computer experiments, it is shown that the proposed method perporms better than the convertional non-aggregated bandwidth smoothing schemes in terms of the peak rate, standard deviation, number of rate changes for the aggregated traffic.

• The KIPS Transactions:PartB
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• v.14B no.4
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• pp.273-280
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• 2007

This paper presents a new 3D sound toolkit called $EVE-Sound^{TM}$ that consists of pre-processing tool for environment simplification preserving sound effect and 3D sound API for real-time rendering. It is designed so that it can allow users to interact with complex 3D virtual environments by audio-visual modalities. $EVE-Sound^{TM}$ toolkit would serve two different types of users: high-level programmers who need an easy-to-use sound API for developing realistic 3D audio-visually rendered applications, and the researchers in 3D sound field who need to experiment with or develop new algorithms while not wanting to re-write all the required code from scratch. An interactive virtual environment application is created with the sound engine constructed using $EVE-Sound^{TM}$ toolkit, and it shows the real-time audio-visual rendering performance and the applicability of proposed $EVE-Sound^{TM}$ for building interactive applications with complex 3D environments.