• 한국전자파학회논문지
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• 제14권3호
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• pp.276-282
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• 2003

OFDM(Orthogonal Frequency Division Multiplexing)은 고속 data 전송에 효과적인 방식이다. 그러나 많은 부반송파들로 인해 높은 PAPR(Peak-to-Average Power Ratio)이 되어 비선형 왜곡이 발생하게 된다. 기존의 PAPR 저감 기법인 SLM(Selective Mapping) 기법은 동일하게 복사된 정보에 phase sequences를 곱한 다음, 이들 중에서 가장 낮은 PAPR을 갖는 신호를 선택하여 전송하는 방식이다. 이 방식은 선택에 관한 부가 정보를 수신기에 전송해야 data를 정확히 복원할 수 있다. 본 논문에서는 SLM 기법에 부가 정보를 삽입하는 방법과 계산량을 줄이는 적응 SLM 기법을 새롭게 제안한다. 그리고, 세가지 phase sequences를 phase rotation factor로 적용하였을 때의 성능을 비교하였다. 제안된 부가정보 삽입의 적응 SLM 기법을 사용한 PAPR 저감성능은 기존의 SLM 기법과 동일하고, 계산량에서는 1/2 이상 감소되므로 더빠른 OFDM통신이 가능하게 된다. 또한 제시한 부가정 보 삽입방식을 적용하여 만족하는 BER 성능을 얻을 수 있음을 확인하였다.

• 천문학논총
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• 제4권1호
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• pp.31-52
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• 1989

태양 주위에 있는 만기형 주계열성들의 자전속도 분포와 자전축의 기울기 분포를 조사하였다. 이를 위해 104개의 낱별들과 8개의 Ursa Major Group별들, 그리고 Hyades 성단에 속한 20개의 별들에 대해 각 별들의 자전주기와 반경을 구하였다. 먼저, 별의 자전주기는 대부분 Noyes et al.(1984)의 채충활성도-자전주기 관계식을 이용하여 구했고, 반경은 태양으로부터의 거리가 25pc 이내인 별들을 택해서 Stefan법칙으로 계산하였다. 자전주기와 반경으로부터 결정된 적도자전속도는 0.4<(B-V)<0.8인 별에서는 (B-V)가 증가함에 따라 급격히 감소하고, 기존의 시선자전속도 관측자료에서 이미 밝혀진 위쪽 경계가 나타남과 동시에 아래쪽으로도 자전속도 값의 명확한 경계가 나타났다. 한편, 적도자전속도와 주어진 시선자전속도 값을 비교함으로써 태양 주위에 있는 낱별들의 자전축의 기울기를 구할 수 있었는데, 계산된 기울기는 은위에 무관한 멋대로분포를 따른다는 것을 알 수 있었다.

• Steel and Composite Structures
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• 제1권1호
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• pp.145-158
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• 2001

An experimental study was conducted to evaluate the effects of loading sequence and lateral bracing on the behavior of reduced beam section (RBS) steel moment frame connections. Four full-scale moment connections were cyclically tested-two with a standard loading history and the other two with a near-fault loading history. All specimens reached at least 0.03 radian of plastic rotation without brittle fracture of the beam flange groove welds. Two specimens tested with the nearfault loading protocol reached at least 0.05 radian of plastic rotation, and both experienced smaller buckling amplitudes at comparable drift levels. Energy dissipation capacities were insensitive to the types of loading protocol used. Adding a lateral bracing near the RBS region produced a higher plastic rotation; the strength degradation and buckling amplitude were reduced. A non-linear finite element analysis of a one-and-a-half-bay beam-column subassembly was also conducted to study the system restraint effect. The study showed that the axial restraint of the beam could significantly reduce the strength degradation and buckling amplitude at higher deformation levels.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 1999년도 추계학술대회-지능형 정보기술과 미래조직 Information Technology and Future Organization
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• pp.313-320
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• 1999

In this paper, a translation, rotation and scale invariant system for the classification of closed 2D images using the bispectrum of a contour sequence and the weighted fuzzy mean method is derived and compared with the classification process using one of the competitive neural algorithm, called a LVQ(Learning Vector Quantization). The bispectrun based on third order cumulants is applied to the contour sequences of the images to extract fifteen feature vectors for each planar image. These bispectral feature vectors, which are invariant to shape translation, rotation and scale transformation, can be used to represent two-dimensional planar images and are fed into an classifier using weighted fuzzy mean method. The experimental processes with eight different shapes of aircraft images are presented to illustrate the high performance of the proposed classifier.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 1998년도 추계학술대회 학술발표 논문집
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• pp.255-262
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• 1998

This paper presents a translation, rotation and scale invariant methodology for the recognition of closed planar shape images using the bispectrum of a contour sequence and the learning vector quantization(LVQ) neural classifier. The contour sequences obtained from the closed planar images represent the Euclidean distance between the centroid and all boundary pixels of the shape, and are related to the overall shape of the images. The higher order spectra based on third order cumulants is applied to tihs contour sample to extract fifteen bispectral feature vectors for each planar image. There feature vector, which are invariant to shape translation, rotation and scale transformation, can be used to represent two0dimensional planar images and are fed into a neural network classifier. The LVQ architecture is chosen as a neural classifier because the network is easy and fast to train, the structure is relatively simple. The experimental recognition processes with eight different hapes of aircraft images are presented to illustrate the high performance of this proposed method even the target images are significantly corrupted by noise.

• 한국멀티미디어학회논문지
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• 제12권12호
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• pp.1728-1735
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• 2009

Human action tracking plays an important place in human-computer-interaction, human action tracking is a challenging task because of the exponentially increased computational complexity in terms of the degrees of freedom of the object and the severe image ambiguities incurred by frequent self-occlusions. In this paper, we will propose a novel method to track human action, in our technique, a dynamic background estimation algorithm will be applied firstly. Based on the estimated background, we then extract the human object from the video sequence, and the skeletonization method and Hough transform method will be used to detect the main structure of human body and each part rotation angle. The calculated rotation angles will be used to control a crane in the port, thus we can just control the container crane by using signalman body. And the experimental results can show that our proposed method can get a preferable result than the conventional methods such as: MIT, JPF or MFMC.

• Structural Engineering and Mechanics
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• 제46권6호
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• pp.843-852
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• 2013

This paper presents results of the effect of different bolt tightening sequences and methods on the performance of gasketed bolted flange joint using nonlinear finite element analysis. Bolt preload scatter due to elastic interactions, flange stress variation and bolt bending due to flange rotation and gasket contact stress variation is difficult to eliminate in torque control method i.e. tightening one bolt at a time. Although stretch control method (tightening more than one bolt at time) eradicates the bolt preload scatter, flange stress variation is relatively high. Flange joint's performance is compared to establish relative merits and demerits of both the methods and different bolt tightening sequences.

• 천문학회지
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• 제51권1호
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• pp.1-4
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• 2018

We study the pseudo-synchronous orbital motion of a binary system on the main sequence. The equations of the pseudo-synchronous orbit are derived up to $O(e^4)$ where e is the eccentricy of the orbit. We integrate the equations to present their solutions. The theoretical results are applied to the evolution of the orbit and spin of the binary star Y Cygni, which has a current eccentricity of $e_0\;=\;0.142$. We tabulate our numerical results for the evolution of the orbit and spin per century. The numerical results for the semi-major axes and rotational angular velocities in the evolutional time scales of three stages (synchronization, circularization, and collapse time scale) are also tabulated. Synchronization is achieved in about $5{\times}10^3\;years$ followed by circularization lasting about $1{\times}10^5\;years$ before decaying in $2{\times}10^5\;years$.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -3
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• pp.1539-1542
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• 2002

In layout of LSI and PWB, block pack- ing problem is very important in order to reduce chip area. Sequence-pair is typical one of conventional pack- ing method and can search nearly-optimal solution by using Simulated Annealing(SA). SA takes huge computation time due to evaluating of various packing results. Therefore, Sequence-pair is not effective enough for fast layout evaluation including estimation of wire length and rotation of every blocks. This paper proposes an efficient block packing method to minimize wire length and chip area. Our method searches an optimal packing efficient- ly by using a cluster growth algorithm with changing the most valuable packing score on packing process.

• 한국지능시스템학회:학술대회논문집
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• 한국퍼지및지능시스템학회 2003년도 ISIS 2003
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• pp.32-35
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• 2003

In this paper, we describe how to represent lower case hand-written English alphabets by a sequence of two to seven fuzzy sets. Each fuzzy set represents an arc segment of the character and each arc segment is assumed to be a part of an ellipse. The part of an ellipse is defined by five quantities: its short and long radii, its orientation angle, whether it is a part of the lower half or the upper half and whether it is the full half or a part of a half. Hence, we use the Cartesian product of five fuzzy sets to represent each arc segment. We show that this representation is a translation, rotation, and scaling invariant and that it can be used to generate the hand-written English alphabets. The representation we describe is different from the one proposed earlier by the author and when compared with the previous representation, the one described in this paper simulates more closely the behavior of how one writes English characters.