• Journal of Digital Contents Society
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• v.6 no.4
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• pp.243-248
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• 2005

In this paper, We proposed joint-modulation CDMA system for efficient streaming transmission. and, We analyzed joint-modulation CDMA system using nakagami fading model and impulsive interference model for transmission channel environment. Also, it can being compensate the performance degradation by using MRC diversity scheme and BCH coding scheme.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• fall
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• pp.45-48
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• 2021

본 논문은 RGB 컬러 3 채널에 대해 공유되는 홀로그램 픽셀 피치를 사용하여 3 차원 장면의 라이트 필드 데이터에서 비호겔 기반 컴퓨터 생성 홀로그램(CGH)을 합성하는 방법을 제안한다. 비호겔 기반 CGH 기술은 라이트 필드의 광선 각도를 평면 파면의 공간 주파수로 해석하여 주어진 라이트 필드 데이터에서 임의의 반송파로 연속 파면을 생성한다. 그러나 광선 각도와 공간 주파수 관계는 파장에 따라 달라지므로 라이트 필드 데이터에서 공간 주파수 샘플링 그리드가 달라져서 홀로그램 재구성에서 색 수차가 발생한다. 제안하는 방법은 가장 작은 청색 회절각이 라이트 필드의 시야를 커버하도록 모든 색상 채널에 공통적인 홀로그램 픽셀 피치를 설정한다. 그런 다음 라이트 필드를 파란색 파장의 공간 주파수 범위와 빨간색 파장의 샘플링 간격으로 보간하여 모든 색상 채널에 공통적인 공간 주파수 샘플링 그리드를 설정한다. 공통 홀로그램 픽셀 피치 및 라이트 필드 공간 주파수 샘플링 그리드는 홀로그램 재구성에서 색상 수차 또는 라이트 필드에 포함된 정보 손실 없이 컬러 홀로그램 합성을 보장한다. 제안된 방법은 다양한 테스트와 리얼 3D 장면의 컬러 라이트 필드 데이터를 사용하여 검증되었다.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.9
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• pp.46-51
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• 2009

This paper propose the new approach of the quantity effect by high efficiency inductor characteristic to the harmonic suppression of the lowpass filter. We applied the reliable de-embedding process in order to extract the precise elements values. Moreover, for the effective its application and comparison, the variable stepped impedance low pass filters with a same specification are designed. The proposed procedure is expected to handle the overall filter performance and to construct a synthesized equivalent circuit from its determined specification.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.6
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• pp.512-519
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• 2013

In this paper, we propose a novel unambiguous correlation function for composite binary offset carrier (CBOC) signal tracking. First, we observe that a sub-carrier of CBOC signal is seen as a sum of four partial sub-carriers, and generate four partial-correlations composing the CBOC autocorrelation. Then, we obtain an unambiguous correlation function with a sharp main-peak by re-combining the partial correlations. From numerical results, we confirm that the proposed unambiguous correlation function offers a better tracking performance than the conventional correlation functions in terms of the tracking error standard deviation and multipath error envelope.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.3
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• pp.257-264
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• 1995

Various factors are investigated on the bed load transport driven by waves and current, and proper forms of bed load transport formulas mainly used in river hydraulics are chosen for the estimation of combined flow bed load transport after considering the additional factors. The BYO Model is employed for the computation of maximum bed shear stress and mean bed shear stress of the combined flow. The friction factor of uni-directional flow is estimated by using modified Keulegan equation, and equivalent roughness height is determined by obtaining correct answer for the bed shear stress of uni-directional flow. Empirical constant in each bed load formula is determined by applying it to Bijker's laboratory data of bed load transport by waves and current and the formulas obtained are discussed on their final forms with the values of empirical constants.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.1-9
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• 2000

This paper presents the error performance of 16 star-QAM with diversity reception in microcell systems in the presence of additive white Gaussian noise(AWGN) and cochannel interference. The differential detection of 16 star-QAM is split into phase detection and amplitude detection. This technique can reduce the degradation of error performance which is due to fading and the complexity of receiver. Diversity reception is proposed to improve the degradation of error performance due to fading. Equal gain and maximal ratio combinings were adopted for the phase detection and the amplitude detection, respectively. The performance of 16 star-QAM was evaluated for various of Rician factor K, maximum Doppler frequency f_DT, signal to cochannel interference ratio and diversity branch L.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.2
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• pp.87-95
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• 2000

Spectral wave models are applied to the area of Kyung-gi bay with two different combinations. One combination assumes a constant tidal elevation over the whole region when applying the wave model to the area. In this case no tidal currents exist in any place. The other combination employs tide model as well as wave model so that tidal condition is defined at every computation time when wave modelling is carried out. Significant wave heights and wave directions are shown for these two cases. With these two different constraints of tidal variation, the results are checked and compared with each other. Both results are found significantly different from each other.

• Journal of the Korean Geophysical Society
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• v.3 no.1
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• pp.37-48
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• 2000

In order to investigate in-line ground motions caused by earthquakes, we examine the multicomponent complex trace analysis method (MCTAM) for the synthetic data and apply it to real earthquake data. An experimental result for synthetic data gives correct information on the arrival times, duration of individual phases, and approaching angles for body waves. Rayleigh waves are also easily identified with the MCTAM. A deep earthquake with magnitude of 7.3 was chosen to test various polarization attributes of ground motions. For P waves, instantaneous phase difference between the vertical and the in-line horizontal components ${\phi}(t)$, instantaneous reciprocal ellipticity ${\rho}(t)$, and approaching angle ${\tau}(t)$ are computed to be ${\pm}180^{\circ},\;0{\sim}0.25,\;and\;-30^{\circ}{\sim}-45^{\circ}$, respectively. For S waves, ${\phi}(t)$ tends to vary while ${\rho}(t)$ have values of $0{\sim}0.3\;and\;{\tau}(t)$ remains near vertical, respectively. A relatively low frequency signal registered just prior to the S wave event is interpreted as a P-wave phase based on its polarization characteristics. Velocities of P and S waves are computed to be 8.633 km/s and 4.762 km/s, and their raypath parameters 0.074 s/km and 0.197 s/km. Dynamic Poisson's ratio is obtained as 0.281 from the velocities of P and S waves.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.5
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• pp.480-488
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• 2006

Up to recently the harmonic generation has deteriorated the quality of electricity and affected the performance on the electrical installation including OA, FA, IT devices and so on. Some studies of harmonic affects in diagnosis and the cause of accident has not done by the experimental data of harmonic source but merely by presumption according to qualitative analysis. So, in order to research the harmonic affect on the electrical installation according to quantitative analysis and gather reliable data over and over again, it is necessary to develop an AC power source which is capable of generating some harmonics. In this paper, we described about realization of AC power source which can produce and compose harmonics for the analysis of accident due to harmonics.

• Proceedings of the KIEE Conference
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• 2001.11c
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• pp.431-434
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• 2001

단층 퍼셉트론이 처음 개발되었을 때, 간단한 패턴을 인식하는 학습 기능을 가지고 있기 장점 때문에 학자들의 관심을 끌었다. 단층 퍼셉트론은 한 개의 소자를 이용해서 이진 논리를 가중치(weight)의 변경만으로 모두 표현할 수 있는 장점 때문에 영상처리, 패턴인식, 장면인식 등에 이용되어 왔다. 최근에, 역전파학습(Back-Propagation Learning)알고리즘이 이진 공간내의 매핑 문제에 적용되고 있다. 그러나, 역전파 학습알고리즘은 연속공간 내에서 긴 학습시간과 비효율적인 수행의 문제를 가지고 있다. 일반적으로 역전파 학습 알고리즘은 간단한 이진 공간에서 매핑하기 위해서 많은 반복과정을 요구한다. 역전파 학습 알고리즘에서는 은닉층의 뉴런의 수는 주어진 문제를 해결하기 위해서 우선순위(prior)를 알지 못하기 때문에 입력층과 출력층내의 뉴런의 수에 의존한다. 따라서, 3층 신경회로망의 적용에 있어 가장 중요한 문제중의 하나는 은닉층내의 필요한 뉴런수를 결정하는 것이고, 회로망 합성과 가중치 결정에 대한 적절한 방법을 찾지 못해 실제로 그 사용 영역이 한정되어 있었다. 본 논문에서는 패턴 분류를 위한 새로운 학습방법을 제시한다. 훈련입력의 기하학적인 분석에 기반을 둔 이진 신경회로망내의 은닉층내의 뉴런의 수를 자동적으로 결정할 수 있는 NETLA(Newly Expand and Truncate Learning Algorithm)라 불리우는 기하학적 학습알고리즘을 제시하고, 시뮬레이션을 통하여, 제안한 알고리즘의 우수성을 증명한다.