• Computational Structural Engineering
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• v.11 no.4
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• pp.187-196
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• 1998

불연속 갤러킨 정식화에 기초를 둔 시간적분법에 대하여 시간을 변수로 한 유한요소적 접근법을 시도하였다. 단일 형상함수와 두 형상함수 정식화에 대해 각각 선형, 이차 형상함수를 적용하여 모두 네 종류의 시간적분법을 유도하였으며, 각 방법에 대하여 시간시텝의 증가에 따른 변위와 속도의 관계를 나타내는 증폭행렬을 계산하였다. 유도된 방법들의 성능을 평가하기 위하여 부하가 갑자기 변화는 진동 문제를 해석하고 변위의 오차를 비교하였다. 네 가지의 방법에 대하여 국부 오차 추정치를 개발하였으며, 오차 추정치의 정확도를 수치예를 이용하여 평가하였다. 단일 형상함수 정식화에서 이차 형상함수를 이용한 오차 추정치가 실제 국부오차를 잘 나타내었으며 유도된 오차 추정치는 시간간격제어 기법에서 시간간격의 크기를 결정하는 척도로 이용 가능하다.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.2
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• pp.27-34
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• 2013

We propose a simple power allocation scheme for an amplify-and-forward multiple relay system with multiple-input multiple-output antennas. Unlike the existing relay precoding matrix with full elements, proposed precoder is a diagonal matrix whose diagonal element is the relay gain for each stream. Furthermore, a weight vector is applied to streams, such that the mutual information of the system approaches that of the exhaustive search scheme, regardless of the number of antennas. Numerical results show that proposed scheme outperforms the conventional schemes with respect to mutual information.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5A
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• pp.408-413
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• 2009

In this paper, minimum mean-square-error (MMSE)-based transceiver processing of a bidirectional amplify-and-forward (AF) relay having multiple antennas is proposed. Besides, the optimal beamforming vectors of users are designed in the sense of the sum rate maximization. Simulation results show that the proposed relay processing can effectively reduce both co-channel interferences and self-interferences and that the proposed beamforming method is proper to the bidirectional communication employing the AF relay.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.5 no.1
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• pp.60-69
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• 1980

The computerized analysis of complicated circuits requires large memory capacity and considerable length of time. In order to enhance the efficiency of memory capacity and the executing time, Sparse Matrix is applied to the solution of simultaneous equations required for the analysis of amplification circuit. The optimization Subroutine, FMFP is utilized for the decision of optimum element parameters of an equalizer amplifier.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1782-1783
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• 2011

실내공간상에서 3차원 실시간 위치를 결정하는 다양한 측지기법들이 존재하지만 $100{\mu}m$ 이하 계측기 수준의 정밀도를 측정하는 방법은 여전히 Laser Theodolite 신호를 사용할 수밖에 없다. Rotary-Laser Automatic Theodolite(R-LAT)는 Fan Laser Beam을 주사하면서 회전시킨 후 주어진 공간의 수직과 수평을 계측하는 Laser Transmitter의 한 종류이다. 본 논문에서는 R-LAT에서 발생되는 Fan Laser Beam 신호를 취득할 수 있는 센서와 증폭회로의 개발을 통하여 3차원 공간좌표에 대한 회전변환행렬로 이루어진 알고리즘을 제안하고 실험을 통하여 기존 Laser Tracker에서 구해지는 공간좌표와 상호 비교하였다.

• Computational Structural Engineering
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• v.7 no.1
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• pp.25-30
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• 1994

본 고에서는 강한 바람이나 지진에 의한 고층 구조물의 진동을 감소시키기 위하여, 능동제어장치가 효과적으로 사용될 수 있음을 보이었다. 그러나 능동제어장치를 실제 구조물에 널리 적용하기에는 아직 많은 문제점들이 남아있다. 첫째, 효과에 비해 고가의 진동제어장치가 필요하며 유지관리에도 많은 비용이 필요하다. 또한 진동제어장치가 원활히 작동하기 위해서는 계속된 에너지의 공급이 있어야 하는데, 지진과 같은 과도한 구조물의 진동시 이를 보장할 수는 없다. 그러므로 극한상황에서는 진동을 오히려 증폭시킬 수도 있다. 둘째, Control Force의 산정시 사용되는 목적함수의 가중행렬을 결정하는 정형화된 방법이 아직 존재하지 않으며 효율적인 산정을 위해서는 많은 시행착오가 필요하다. 그밖에도 복잡한 실제 구조물의 단순한 모형화에 따라서 여러 문제점들이 발생하기 쉬우며, 실제 제어시에는 시간지연효과나 측정되지 못한 거동에 의한 문제 등이 있다. 구조물의 진동 저감방안에 대한 지금까지의 연구결과로는, 일반적인 경우에 있어서는 Base Isolator와 같이 재료의 감쇠특성을 이용하는 방법이 추천되고 있으나, 현재 내진설계된 고층건물과 같은 대형 구조물의 진동제어 등의 몇몇 경우에 있어서 능동제어의 필요성이 인정되고 있다. 좀더 안정적이고 효율적인 제어기법의 개발에 의해 많은 실제 구조물에 적용 범위를 넓힐 수 있을 것으로 기대된다.

• Korean Journal of Optics and Photonics
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• v.14 no.5
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• pp.483-490
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• 2003

We have analyzed theoretically optical pulse propagation in a coherent atomic medium for amplification without inversion (AWI), which is achieved by adding incoherent optical pumping to a typical EIT system. In order to explain experimental results [Kim et al., J. Phys. B, 36, 2671(2003)] to control the group velocity of the optical pulse by changing pumping power, we established a 5-level atomic system and applied density matrix equations. This AWI model system is different from previous AWI systems from the viewpoint of using two levels for incoherent optical pumping isolated optically from the EIT (electromagentically induced transparency) system so that more atoms can participate in pulse speed control. We have found that population transfer by collisions between ground states plays a decisive role for efficient AWI, and more atoms are effective for slowing the pulse. Our numerical results are in good agreement qualitatively with experimental results.

• Journal of Korea Multimedia Society
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• v.13 no.5
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• pp.641-650
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• 2010

Color image sensors (CIS) output color images through image sensors and image signal processing. Image sensors that convert light to electrical signal are divided into CMOS image sensor and CCD image sensor according to transferring method of signal charge. In general, a CIS has RGB output signals from tri-stimulus XYZ of the scene through image signal processing. This paper presents an adaptive colorimetric analysis method to obtain chromaticity and luminance using CIS under various environments. An image sensor for the use of colorimeter is characterized based on the CIE standard colorimetric observer. We use the method of least squares to derive a colorimetric characterization matrix between camera RGB output signals and CIE XYZ tristimulus values. We first survey the camera characterization in the standard environment then derive a SGL(shutter-gain-level) function which is relationship between luminance and auto exposure (AE) characteristic of CIS, and read the status of an AWB(auto white balance) function. Then we can apply CIS to measure luminance and chromaticity from camera outputs and AE resister values without any preprocessing. Camera RGB outputs, register values, and camera photoelectric characteristic are used to analyze the colorimetric results for real scenes such as chromaticity and luminance. Experimental results show that the proposed method is valid in the measuring performance. The proposed method can apply to various fields like surveillant systems of the display or security systems.

• Journal of Life Science
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• v.22 no.11
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• pp.1470-1476
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• 2012

A genetic variation of Lepista nuda and two genus Lepista species (L. irina and L. sordida) were analyzed by random amplified polymorphic DNA (RAPD) and internal transcribed spacer (ITS) sequence analysis. In the resulting RAPD analysis, 22 out of 40 random primers amplified polymorphic RAPD fragment patterns, the amplified bands were 355, and DNA fragment sizes were 200-400bp. Intraspecific genetic dissimilarity of the 10 L. nuda strains were calculated to range from 0% to 21.60%, L. sordida from 16.93% to 24.82%, L. irina were 20.62% to 25.54%, and intraspecific genetic dissimilarity of L. sordida and L. irina was 23.49%. The 673 base pairs were sequenced during the analysis of the ITS I and II region; six L. nuda strains intraspecific genetic dissimilarities ranged from 1.58% to 11.47%, L. nuda and L. sordida from 3.83% to 12.88%, L. nuda and L. irina from 7.11% to 15.61%, and intra-specific genetic variation between L. sordida and L. irina was 4.79%. The findings showed that RAPD and ITS sequencing could be used for developing molecular genetic markers and screening of unidentified genus Lepista species.

• Korean Journal of Plant Taxonomy
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• v.38 no.1
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• pp.17-29
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• 2008

Phylogenetic relationships were examined for 17 taxa of Lycoris by RAPD analysis. The length of the amplified DNA fragments ranged from 300 bp to 1,700 bp. 57 scorable RAPD markers were observed from PCR reactions with five random oligoprimers. The analysis by UPGMA sepatated the examined taxa of Lycoris into were clusters. First group was comprised of ten taxa of L. chinensis var. sinuolata, L. sanguinea var. koreana, L. uydoensis, L. flavescens, L. radiata var. pumila, L. radiata, L. squamigera, L. chejuensis, L. aurea and L. guangxiensis, second group of L. haywardii, L. sprengeri, L. rosea, L. straminea and L. houdyshii, third group of outgroup of Narcissus tazetta var. chinensis and Crinum asiaticum var. japonicum. From the viewpoint of cytological characters such as polyploidy and karyotype, the RAPD analysis was very useful to show the relationship among the intraspecific taxa of Lycoris.