• Journal of Advanced Marine Engineering and Technology
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• 제30권4호
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• pp.505-513
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• 2006

A linear power amplifier is particularly emphasized on the system using a linear modulations, such as 16QAM and QPSK with pulse shaping. because intermodulation distortion which causes adjacent channel interference and co-channel interference is mostly generated in a nonlinear power amplifier. In this paper, parameters of a linearization loop, such as an amplitude imbalance a phase imbalance and a delay mismatch, are briefly analyzed to get a specific cancellation performance and linearization bandwidth. Experimental results are presented for IMT-2000 frequency band. The center frequency of the feedforward amplifier is 2140 MHz with 60 MHz bandwidth. When the average output power of feedforward amplifier is 20 Watt. the intermodulation cancellation performance is more than 21 dB. In this case, the output power of feedforward amplifier reduced 3.5 dB because of extra delay line loss and coupling loss. The feedforward amplifier efficiency is more than 7.2 % for multicarrier signals, 59 dBc for ACPR.

• 한국해양공학회지
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• 제21권3호
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• pp.40-45
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• 2007

This study was performed to investigate the effect of various propeller tunnel shapes on the propulsion performance of a fishing boat. The propeller tunnel reduces the problem resulting from the open propeller accidentally catching the waste net and cable on the sea, as well as increasing the cruising speed. For 3 different tunnel geometries, the model test is conducted in the circular water channel, and the potential based panel method was applied to analyze the hydrodynamic characteristics of propeller. Also, both results are compared with each other to represent the difference between results of the model scale test and the potential theory. It is expected that these results could be referenced in the design of the propeller tunnel in consideration of the hydrodynamic interaction between the propeller and the tunnel.

• 한국정보처리학회논문지
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• 제7권6호
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• pp.1923-1931
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• 2000

In this paper, e analyze the performance of the PSS-type Viterbi decoder which can reduce calculations and power consumption using the Monte Carlo simulations. Gaussian and burst noise channels are considered in this simulation, and we achieve that convolutional interleaver can reduce complexity and power consumption in burst noise channel. In order to implement the high-speed PSS-type Viterbi decoder, the architectures of decoder are presented, and we implemented the PSS-type Viterbi decoder for r=1/2, k=3 using the VHDL tool, and prove the decoding process.

• ETRI Journal
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• 제27권2호
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• pp.223-226
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• 2005

This paper presents the application of a turbo coding technique combined with a bandwidth efficient method known as trellis-coded modulation. A transformation applied to the incoming I-channel and Q-channel symbols allows the use of an off-the-shelf binary/quadrature phase shift keying (B/QPSK) turbo decoder without any modifications. A conventional turbo decoder then operates on transformed symbols to estimate the coded bits. The uncoded bits are decoded based on the estimated coded bits and locations of the received symbols.

• 한국통신학회논문지
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• 제42권2호
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• pp.383-385
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• 2017

For the purpose of providing high data rate real-time services, radio transmission technologies for ship ad-hoc network based on the Recommendation ITU-R 1842-1 are designed. In order to increase the link throughput of real-time services, in this paper, we investigate the performance of the SANET with the spatial transmit diversity techniques are employed. Based on the analysis of the packet error rate and throughput, we select the efficient multiple antenna schemes for SANET to improve the link reliability.

• 한국해양공학회지
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• 제11권4호
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• pp.221-226
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• 1997

This study was carried out for the hull form development of G/T 340ton class high speed fishery patrol ship by Chosun University at the Circulating Water Channel cooperatively with Korea Maritime Service. Same size of 15knots class fishery patrol ship was selected as a parent form (Model number : CU-015), and modified fore and after body to be suitable for the operation at 20 knots. To minimize the breaking wave in the vicinity of fore body at high speed zone, high bulb nose and slender fore body hull form was chosen as an initial condition. Meanwhile, to ensure the engine room space keeping high resistance-propulsion performance, U-type stern hull form was developed.

• 한국통신학회논문지
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• 제35권12A호
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• pp.1145-1151
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• 2010

Hochwald et al. introduced unitary space-time codes for quasi-static Rayleigh fading channels which allows for noncoherent decoding when the channel response is not known at the receiver. However, when reliable information on the channel response is available, coherent decoding is preferable for improved performance. Here, we study the relationship between the performance criteria on the diversity and coding advantages provided by unitary space-time codes with noncoherent and coherent decoding. We show that when a unitary space-time code achieves full spatial diversity with noncoherent decoding, full spatial diversity is also guaranteed with coherent decoding.

• Journal of information and communication convergence engineering
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• 제20권4호
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• pp.235-241
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• 2022

A dispersion map was proposed to improve the compensation effect of a distorted WDM (wavelength division multiplexed) channel in a dispersion-managed link coupled with optical phase conjugation. The dispersion map is an origin-symmetric structure around the optical phase conjugator in the middle of the transmission path. In addition, the dispersion map has a form in which a constant dispersion accumulation pattern is repeated regularly. Through simulation, we confirmed that the application of the origin-symmetric dispersion map with a repetitively shaped configuration was more effective in compensating for the distorted WDM channel than in the dispersion-managed link with a conventional dispersion map. In addition, we confirmed that the compensation effect could be increased when the cumulative dispersion distribution of the origin-symmetric distribution map had a positive value in the first half section and a negative value in the second half section. Further, we observed that as the number of repeated dispersion accumulation patterns increased, the residual dispersion per span should also be increased.

• The Journal of the Acoustical Society of Korea
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• 제25권2E호
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• pp.43-48
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• 2006

Abstract-Using the recursive generalized eigendecomposition method, we develop a recursive form solution to the data least squares (DLS) problem, in which the error is assumed to lie in the data matrix only. Simulations demonstrate that DLS outperforms ordinary least square for certain types of deconvolution problems.

• 한국항만경제학회지
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• 제27권4호
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• pp.313-346
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• 2011

바다를 지배한 민족이 세계를 지배한다고 로마의 키케로(Cicero)가 말했다. 세계사에서 중요 역할을 한 국가는 대부분 바다의 중요성을 강조하였다. 페니키아, 그리스, 카르타고, 로마, 포르투칼, 스페인, 영국, 미국 등 세계는 바다를 지배해온 민족의 역사라 할 수 있다. 바다는 자원의 보고, 소통과 물류, 유통의 통로로 국가의 원활한 정치, 경제, 사회, 문화의 터전이며 바다는 동시에 꿈과 상상의 장이며, 가능성과 비전의 토대이다. 본 연구에서는 우리나라 해양강국의 실현이라는 비전의 실현을 위해 세계의 주요 국가와 역사를 개관하였다. 우리 주요 해양정책의 주요 이슈에 대한 실태와 전망을 살펴보았으며, 이를 토대로 우리 해양강국의 비전을 제시하였다. 2020년 세계 5대 해양강국, 세계 10위의 해양과학기술 보유 등을 비전으로 제시하고 세부추진 전략을 제안하였다. 이를 위해 해양수산부의 복원이 절실하며 그 이유와 필요성을 5가지 논리로 제시하였다. 또한 해양수산부의 복원의 향후 방향도 정책, 기능적 관점과 제도적 관점에서 제시하였다. 해양강국 대한민국은 해양수산부가 향후 정부조직 개편에서 반드시 복원되야 실현될 수 있다고 본다.