• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.1C
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• pp.131-137
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• 2009

Binary offset carrier (BOC) signal synchronization is one of the most important steps to recover the transmitted information in global navigation satellite systems (GNSS) including Galileo and global positioning system (GPS). Generally, BOC signal synchronization is based on the correlation between the received and locally generated BOC signals. Thus, the multiple side-peaks in BOC autocorrelation are one of the main error sources in synchronizing BOC signals. Recently, a novel correlation function with reduced side-peaks was proposed for BOC signal synchronization by Julien [8]; however, Julien's correlation function not only still has the side-peaks, but also is only applicable to sine phased BOC(n, n), where n is the ratio of the pseudo random noise (PRN) code rate to 1.023 MHz. In this paper, we propose a new correlation function for BOC signal synchronization, which does not have any side-peaks and is applicable to general types of BOC signals, sine/cosine phased BOC(kn, n), where k is the ratio of a PRN chip duration to the period of a square wave sub-carrier used in BOC modulation. In addition, an efficient correlator structure is presented for generating the proposed correlation function.

• Journal of Korea Water Resources Association
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• v.38 no.11
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• pp.937-946
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• 2005

The objective of the study is to develop a reservoir optimal operation model and to suggest the appropriate amount of additional water supply and optimal operation rule. The model uses multiple objective function and a global search method, SCE-UA method. The objective function is set up to maintain the storage at target level, to satisfy the water demand, and to maximize the hydropower product. To evaluate the model's applicability, the model was applied for allocating the optimal water depending on storage level changes of Seomjin dam. The results comparing optimal operation and historical data showed that hydropower product increased from $-2.29\%$ to $14.51\%$, $-5.94\%$ to $3.98\%$, and $-0.43\%$ to $6.35\%$ with varying target levels in wet, dry, and normal period, respectively. Also, The model was applied for assessing water supply capacity of Seomjin dam to satisfy increasing water demand. The dam was operated by the model on consideration of downstream flow as 0.17, 0.50, 0.70, 1.0, 1.5, and $3.0\;m^3/sec$. The results showed that in case of operating the dam with downstream flow less than $0.70\;m^3/sec$ and with target water level lower than 194.0 m, hydropower product was more than the historical operation data and existing amount of water supply was less influenced.

• Journal of KIISE:Software and Applications
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• v.27 no.12
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• pp.1193-1201
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• 2000

본 논문에서는 탐색 영역과 특징의 가중치를 동적으로 조절하여 블록 단위의 움직임 벡터를 추출하는 활동적 블록 정합 알고리듬을 제안한다. 본 논문에서 제안하는 알고리듬은 탐색 영역의 중심 위치를 결정하기 위해 시간에 따른 블록의 동작 변화는 작다고 가정한다. 그리고 탐색 영역의 크기는 공간적으로 인접한 블록들의 신뢰도에 따라 조절된다. 또한 본 논문에서 제안하는 알고리듬은 다중 특징을 사용하는 블록 정합 알고리듬으로 블록 정합 시 특징의 기여 정도를 나타내는 가중치를 블록 안에서 각 특징이 가지는 구분력에 따라 자동으로 설정하는 정합 유사 함수를 사용한다. 실험 결과는 본 논문에서 제안한 블록 정합 알고리듬이 기존의 알고리듬 보다 정확하게 움직임 벡터를 추출함을 보여준다.

• Journal of KIISE:Information Networking
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• v.28 no.1
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• pp.1-10
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• 2001

파장경로주가 통신망은 근원지에서 목적지까지 정보가 빛의 형태로 전달되는 전광 통신망이다. 정보는 빛의 길을 통해 전달되어 지는데 이는 광 채널들을 교환 연결방식을 이용하여 연결함으로써 만들어진다. 링크간의 연결이 복수개의 광섬유로 이루어진 파장 경로주기 통신망에서는 광섬유간의 교환능력을 통해 더욱 효율적으로 채널들을 이용할 수 있다. 이논문에서는 주어진 연결 요구들을 충족시키는 오프라인 채널 지정문제를 통하여 링이나 트리 구조를 갖는 통신망에서 광섬유간의 교환 능력이 미치는 영향을 조사해 보았다. 주어진 연결 요구들은 하나의 변수인 부하로 나타내 진다. 링의 형태를 갖는 통신망에서 부하를 교환기의 크기에 대한 함수로 나타냄으로써 교환기의 크기가 미치는 영향을 수량화했고 트리의 형태를 가는 통신망에서는 일반적으로 부하가 L일 때 하나의 링크에 L개의 채널을 사용하여 채널 지정을 얻기에는 광섬유간의 교환이 충분하지 않다는 반증을 보였다.

• Journal of Ocean Engineering and Technology
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• v.11 no.3
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• pp.180-190
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• 1997

잠수함이 저심도 조건에서 특수임무 수행시, 표면파도 및 조류등 외란의 영향하에서 요구심도 및 위치 유지를 위한 강인한 자동항법장치 설계는, 첨단 군용 잠수함 개발에 필수적이다. 본 연구는 잠수함 조종 운동역학계에 기초하여, 정확한 심도 및 피치 운동 제어를 위해 선형 행렬 부등식을 이용한 혼합 $H_2/H_{\infty}$ 설계법을 사용, 다중 목적 함수로 표현된 잠수함의 조종성능들을 개선하였다. 또한, 제어기 설계법의 타당성을 수치 시뮬레이션을 통하여 검증하였다. 결과적으로 본 제어법은 각종 외란 및 계의 불확실성하에서 잠수정의 만족스러운 과도 상태 응답과 일정 심도 유지 및 피치 각도 변동 최소화에 적합한 강인한 방법임이 검증되었다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.1020-1025
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• 2002

This paper exploits how vortex noise is generated around a cylinder. This is done by utilizing an acoustic holography. In this experiment. compressed air was Infected to tile cylinder through a hose. Therefore, major noise sources were at a hose end as well as around the cylinder： vortex shedding noise. The holography results show a resultant noise picture there it is not easy to clearly sort out the shedding noise and what is generated at the end of the tube. We attempted to separate those noise by the method we developed : contribution analysis scheme. The method, in fact, was found to be efficient and practical to separate the noise field into independent noise sources. The highlights of the results are. we believe, that lift and drag noise picture are now available. This procedure does not limit its application. therefore we may use this to visualize any noise field that we want to understand.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3638-3644
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• 2009

A CMOS multi-channel low-voltage current mode filter circuit is designed. The designed current-mode filter is based on linear cascode current-mode integrator that is newly proposed in this paper. When it is compared with that of the typical current-mirror type current-mode integrator, the proposed linear cascode current-mode integrator achieves high current gain and unity gain frequency. The designed filter is composed with 5th Chebyshev function and converted to active version by signal flow graph method. We verified that the designed filter can be applied to three-channel basedband, bluetooth, DECT and WCDMA with 0.51MHz~7.03MHz frequency tuning range by Hspice simulation using 1.8V-$0.18{\mu}m$ CMOS technology.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.4A
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• pp.330-335
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• 2002

In the direct sequence code division multiple access system, the problem of multiple access interference due to multiple access is generated. A interference cancelling receiver is used to solve this problem. The conventional interference cancelling receiver is structure of successive interference canceller using antenna array. In this structure, the difference of between method I and method II depends on updating weight vector. In this paper, the adaptive blind CMA array interference cancelling receiver using cost function of constant modulus algorithms is proposed to update weight vector at conventional structure. The simulation compared the proposed interference cancelling receiver with two conventional interference cancelling receivers by signal to interference ratio and bit error rate curve under additive white Gaussian noise environment. The simulation results show that the proposed receiver has about the gain of SIR of 1.5[dB] more than method I which is conventional receiver at SIR curve, and about the gain of SIR of 0.5(dB) more than method II. In BER curve, the proposed IC receiver about the gain of SNR of 2[dB] more than method I and about the gain of SNR of 0.5[dB] more than method If, Thus, the proposed interference cancelling receiver has the higher performance than conventional interference cancelling receivers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10C
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• pp.942-948
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• 2003

In this paper, we analyze the performance of multiple trellis coded modulation applied to continuous phase frequency shift keying (MTCM/CPFSK) for the noncoherent receiver without channel state information (CSI) on the interleaved Rician fading channel. In this system, the squared cross-correlation between the received signal and a candidate signal is used as the branch metric of the Viterbi decoder. To obtain the bit error performance of this system, we analyze the approximated pairwise error probability (PEP) and the exact PEP. We also derive the equivalent normalized squared distance (ENSD) and compare it with the ENSD of the noncoherent receiver with perfect CSI. Simulation results are also provided to verify the theoretical performance analysis.

• Journal of Korea Water Resources Association
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• v.35 no.1
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• pp.51-64
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• 2002

In this study, the formulation of the developed mixed-integer programming model for a multi-reservoir system including hydro-electric power generation (park et al., 2001) has been improved for multiple reservoir system operation using risk evaluation criteria. Sequential linear programming(SLP) was applied for the linearization of the hydro-electric energy term in the model. In order to allocate monthly reservoir release reasonably the value of weight for hydro-electric energy was assigned by level of power generation hour. The improved model was applied to the five reservoirs system in the Han river. And could be confirmed the availibility of new formulation appling risk evaluation criteria.