• 대한전자공학회논문지SD
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• 제46권10호
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• pp.79-85
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• 2009

본 논문은 $0.18{\mu}m$ CMOS 공정을 이용하여 3.2 Gb/s serial link receiver를 설계하였다. High-speed links의 performance를 제한하는 가장 큰 요소는 transmission channel bandwidth, timing uncertainty가 있다. 이러한 문제점을 해결하기 위한 방법으로 multi-level signaling(4-PAM)을 이용하였다. 추가적으로 전송속도를 높이고 BER를 낮추기 위한 방법으로 current-mode amplifier, CML sampling latch를 사용하였다. 4-PAM receiver의 최대 데이터 전송속도는 3.2 Gb/s이다. BER은 $1.0{\times}10^{-12}$ 이하이며 chip size는 $0.5\;{\times}\;0.6\;mm^2$이고 1.8 V supply voltage에서 49mA current를 소모한다.

• 전자공학회논문지CI
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• 제45권6호
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• pp.194-203
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• 2008

CCTV와 같은 기존의 영상 감시 시스템들은 상황을 통제하는 오퍼레이터에 많이 의존했었다. 하지만, 최근 제품화 되고 있는 시스템들은 오퍼레이터에 의존하지 않고 시스템 안에서 자동으로 문제를 해결할 수 있도록 지능화 되고 있다. 하지만, 시스템에서 자동으로 상황을 처리하기에 많은 문제가 존재한다. Occlusion, 타겟의 Scale, Affine 변화가 대표적인 문제인데, 본 논문에서는 타겟의 크기변 화로 인해 발생하는 정보 손상 문제를 다룬다. 이 문제는 타겟의 크기가 다양하게 변화함으로써 정확한 정보를 얻지 못하고, 배경 정보를 흡수함으로써 추적 알고리즘의 성능을 크게 저하시키는 원인이 된다. 따라서 본 논문에서는 물체의 크기가 변화함으로써 타겟 정보를 손상시키는 문제를 최소화하기 위한 방법을 제안한다. 이 문제를 해결하기 위해 Multi-Stage Sampling을 이용한 Particle Filter를 기반으로 물체 추적 알고리즘에 적합하도록 개량된 MSER을 이용하였다. 이를 통해 타겟 물체의 크기가 다양하게 변화해도 정확한 크기를 추정함으로써 이 문제를 해결할 수 있다.

• 한국군사과학기술학회지
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• 제22권3호
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• pp.311-319
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• 2019

This paper proposes an acceleration of the multi-level fast multipole algorithm(MLFMA) by using a double interpolation method. The MLFMA has been primarily used to conduct scattering analysis of electrically large targets, e.g. stealth aircraft. In the MLFMA, radiation functions of each basis functions are first precomputed, and then aggregated. After transfer calculations for the aggregations, each interaction is disaggregated, and then received in the testing function. The key idea of the proposed method is to decrease the sampling rates of the radiation and receiving functions. The computational complexity of the unit sphere integration in terms of the testing functions is thus highly alleviated. The remaining insufficient sampling rate is then complemented by using additional interpolation. We demonstrate the performance of the proposed method through radar cross-section(RCS) calculations for realistic aircraft.

• 한국인터넷방송통신학회논문지
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• 제17권6호
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• pp.69-78
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• 2017

5G 스마트폰의 샤논과 신호처리의 푸리에가 표본화정리(최고 주파수의 2배분1 즉, $\frac{1}{2f_n}=T$)에서 만난다. 본 논문에서는 초기 샤논 정리가 Point-to-Point에서 샤논 용량을 구했지만 5G는 Multi point MIMO로 기술이 발전했음을 Relay 채널에서 보인다. 푸리에 변환은 고정매개변수로 신호처리를 했는데, 멀티미디어 시대에 2N-1 다변수인 푸리에-Jacket 변환을 제안해서 성능을 분석했다. 이 연구에서 저자는 시간 계산 측면에서 프리 코딩 / 디코딩 복잡성을 줄이기위한 Jacket 기반의 빠른 방법을 제안함으로써 신호 처리의 복잡성 문제를 해결한다. 재킷 변환은 신호 처리 및 코딩 이론에서 응용 프로그램을 찾는 것으로 나타냈다. 재킷 변환은 속성 $AA^{\dot{+}}=nl_n$이 있는 필드 F에 대해 $n{\times}n$ 행렬 $A=(a_{jk})$로 정의되며, 여기서 $A^{\dot{+}}$는 A의 원소 역행렬의 전치 행렬, 즉 $A^{\dot{+}}=(a^{-1}_{kj})$이며, 이는 변환을 일반화하고 중심 가중 변환, 특히 재킷 변환 특성을 이용하여, 저자는 전송 기반의 중계 기반 DF 협동 무선 네트워크에서 분산 다중 입력 다중 출력 채널의 프리 코딩 및 디코딩에 적용하여 새로운 고유치 분해 (EVD : eigenvalue decomposition) 방법을 제안한다. 단일 심볼 디코딩 가능한 시공간 블록 코드를 사용한다. 본 논문은은 제안 된 Jacket 기반 EVD 방법이 기존의 EVD 방법에 비해 계산 시간이 현저히 단축되었다. 계산 시간 단축과 관련된 성능은 수학적 분석 및 수치결과를 통해 정량적으로 평가했다.

• 한국방재학회 논문집
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• 제9권5호
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• pp.93-102
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• 2009

본 연구는 미호천 유역을 대상으로 유량곡선의 세부적인 특성을 고려한 다목적함수를 적용하여 Probability Distribution Model(PDM) 모형의 유량모의성능을 검토하였다. PDM은 유역을 한 개의 단위구역으로 개념화한 집중형 강우유출모형으로 영국의 지역화 연구 및 홍수량 산정방법에 대표적으로 이용되고 있다. PDM 모형의 5개 매개변수를 Monte Carlo 방법에 기반을 둔 분석도구(MCAT, Monte Carlo Analysis Toolkit)를 활용하여 사후검정분포, 검정근거 및 민감도 분석 등을 수행하였으며, 모형의 매개변수 중 cmax와 k(q)만이 뚜렷한 검정 근거가 있고 나머지 변수들은 동등성의 영향을 확인하였다. 또한, 유량곡선의 고유량 및 저유량의 특성을 맞춘 목적함수의 Trade-off를 고려한 매개변수의 파레토 최적해를 산정한 결과, 모든 목적에 최대한 부합하는 유량 산정의 가능성을 제시하였다. 검정(calibration)기간에서 NS*E=0.035, FSB=0.161, FDBH= 0.809로 안정적이며 만족할만한 모의성능을 나타내었고, 검증(validation)기간에 대해서도 안정적인 모의성능을 나타내었다.

• International Journal of Computer Science & Network Security
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• 제23권7호
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• pp.1-8
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• 2023

An Orthogonal Frequency Division Multiplexing (OFDM) based wireless communication system has drawn wide attention for its high transmission rate and high spectrum efficiency in not only radio but also Underwater Acoustic (UWA) applications. Because of the narrow sub-carrier spacing of OFDM, orthogonality between sub-carriers is easily affected by Doppler effect caused by the movement of transmitter or receiver. Previously, Doppler compensation signal processing algorithm for Desired propagation path was proposed. However, other Doppler shifts caused by delayed Undesired signal arriving from different directions cannot be perfectly compensated. Then Receiver Bit Error Rate (BER) is degraded by Inter-Carrier-Interference (ICI) caused in the case of Multi-path Doppler channel. To mitigate the ICI effect, a modified Delay and Doppler Profiler (mDDP), which estimates not only attenuation, relative delay and Doppler shift but also sampling clock shift of each multi-path component, is proposed. Based on the outputs of mDDP, an ICI canceling multi-tap equalizer is also proposed. Computer simulated performances of one-tap equalizer with the conventional Time domain linear interpolated Channel Transfer Function (CTF) estimator, multi-tap equalizer based on mDDP are compared. According to the simulation results, BER improvement has been observed. Especially, in the condition of 16QAM modulation, transmitting vessel speed of 6m/s, two-path multipath channel with direct path and ocean surface reflection path; more than one order of magnitude BER reduction has been observed at CNR=30dB.

• 한국의류학회지
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• 제29권3_4호
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• pp.391-402
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• 2005

Tile purposes of this study were to find out any significant relations among body image, needs for body modification, self concept, and some selected clothing behaviors of two age group females using social comparison theory as the research background. The sampling method was a convenient sampling, and the subjects were 56 females aged from 20 to 24 years and 54 females aged from 40 to 49 years. The quasi-experiment and survey were conducted from May 1 to June 30, 2002. The results of tile study were as follows. First, the perceptual body image is more important than measured body size and ideal body size in body image. Apart from measurement instrument, people who perceived slim had higher self concept, exhibition and conformity of clothing. Second, there were significant differences between the two age groups(twenties and forties) in needs for plastic modification, self concepts and clothing behaviors. The younger age group exhibited higher need for modification than the older age group and the younger group also showed higher self concept, higher interests in clothing and fashion, more exhibition tendency and conformity to clothing.

• Asian-Australasian Journal of Animal Sciences
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• 제22권1호
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• pp.124-130
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• 2009

Estimating genetic interaction effects in animal genomics would be one of the most challenging studies because the phenotypic variation for economically important traits might be largely explained by interaction effects among multiple nucleotide sequence variants under various environmental exposures. Genetic improvement of economic animals would be expected by understanding multi-locus genetic interaction effects associated with economic traits. Most analyses in animal breeding and genetics, however, have excluded the possibility of genetic interaction effects in their analytical models. This review discusses a historical estimation of the genetic interaction and difficulties in analyzing the interaction effects. Furthermore, two recently developed methods for assessing genetic interactions are introduced to animal genomics. One is the restricted partition method, as a nonparametric grouping-based approach, that iteratively utilizes grouping of genotypes with the smallest difference into a new group, and the other is the Bayesian method that draws inferences about the genetic interaction effects based on their marginal posterior distributions and attains the marginalization of the joint posterior distribution through Gibbs sampling as a Markov chain Monte Carlo. Further developing appropriate and efficient methods for assessing genetic interactions would be urgent to achieve accurate understanding of genetic architecture for complex traits of economic animals.

• JSTS:Journal of Semiconductor Technology and Science
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• 제15권1호
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• pp.22-28
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• 2015

This paper proposes column-parallel three step Single Slope Analog-to-Digital Converter (SS-ADC) for high frame rate VGA CMOS Image Sensors (CISs). The proposed three step SS-ADC improves the sampling rate while maintaining the architecture of the conventional SS-ADC for high frame rate CIS. The sampling rate of the three-step ADC is increased by a factor of 39 compared with the conventional SS-ADC. The proposed three-step SS-ADC has a 12-bit resolution and 200 kS/s at 25 MHz clock frequency. The VGA CIS using three step SS-ADC has the maximum frame rate of 200 frames/s. The total power consumption is 76 mW with 3.3 V supply voltage without ramp generator buffer. A prototype chip was fabricated in a $0.13{\mu}m$ CMOS process.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권4호
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• pp.703-719
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• 2011

In multi-user wireless communication systems, adaptive modulation and scheduling are promising techniques for increasing the system throughput. However, a mass of wireless recourse will be occupied and spectrum efficiency will be decreased to feedback channel quality indication (CQI) of all users in every subcarrier or chunk for adaptive orthogonal frequency division multiplexing (OFDM) systems. Thus numerous limited feedback schemes are proposed to reduce the system overhead. The recently proposed compressive sensing (CS) theory provides a new framework to jointly measure and compress signals that allows less sampling and storage resources than traditional approaches based on Nyquist sampling. In this paper, we proposed two novel CQI feedback schemes based on general CS and subspace CS, respectively, both of which could be used in a wireless OFDM system. The feedback rate with subspace CS is greatly decreased by exploiting the subspace information of the underlying signal. Simulation results show the effectiveness of the proposed methods, with the same feedback rate, the throughputs with subspace CS outperform the discrete cosine transform (DCT) based method which is usually employed, and the throughputs with general CS outperform DCT when the feedback rate is larger than 0.13 bits/subcarrier.