• The Journal of the Acoustical Society of Korea
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• v.24 no.6
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• pp.334-342
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• 2005

In this Paper. a time-domain geoacoustic inversion was performed using the bulb signals measured during MがU. 04 experiment conducted in the East Sea of Korea in 2004. An obiective function was defined as a direct cross-correlation between the measured and the simulated signals in time domain. The ray theory was used to model the wave propagation in time domain and optimizations were Performed using VFSA (very fast simulated annealing) algorithm. Comparison of inversion results with those from transmission loss matching (an accompanying paper in this issue of the Journal of the Acoustical Society of Korea) shows that Parameters are consistently inverted. Direct time series comparisons between the measured signals and the simulated signals are Presented based on inversion results.

• Proceedings of the Korea Contents Association Conference
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• 2017.05a
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• pp.45-46
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• 2017

본 논문에서는 간섭신호가 존재하는 무선 에너지 중계 네트워크 환경에서 중계 노드의 에너지 수확률을 결정하는 TSR 기반 에너지 하베스팅 기법의 성능을 향상시키기 위하여 간섭을 고려한 전송채널 분석 모델과 에너지 하베스팅 최적화 기법을 제안한다. 특히, 간섭 신호를 고려한 최적의 수신기 모드 스위칭 메커니즘 설계를 위한 최적의 에너지 수확률(energy harvesting ratio) 결정 기법을 제안하여 RF 에너지 하베시팅 시스템의 처리율을 최대화 할 수 있도록 하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.578-581
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• 2011

H.264/AVC에서는 율-왜곡 최적화 기법을 사용하여 부호화 성능을 이전 보다 대폭 향상시켰다. 율-왜곡 최적화 기법은 선택할 수 있는 모든 코딩 모드들의 비용을 계산한 후, 최소의 비용을 가진 모드를 선택하여 부호화를 한다. 따라서 코딩 모드들이 많아질수록 복잡도 역시 증가하며, 기존 표준보다 다양한 코딩모드를 지원하는 H.264에서는 복잡도가 더 많이 증가한다. 본 논문에서는 SAHTD(Sum of Absolute Hadamard Transform Difference)를 이용하여 화면 내 모드 결정부에서 빠른 화면내 모드 결정을 하면서도 압축 손실이 적게 발생하는 방법을 제시하였다. 휘도 신호 $16{\times}16$블록, 휘도 신호 $4{\times}4$블록, 색차 신호 $8{\times}8$블록 모두 SAHTD를 기준으로 최적의 모드가 결정된다. 휘도 신호 $16{\times}16$블록에서 SAHTD값에 따라 $4{\times}4$블록 부호화 과정을 조기 종결이 가능하게 하는 것과, 휘도 신호 $4{\times}4$에서는 SAHTD 값이 가장 낮은 3개의 모드와 MPM(Most Probable Mode)을 후보 모드로 선택하여 율-왜곡 최적화를 수행하는 방식이 사용되었다. MPM이 SAHTD값이 가장 낮을 경우 MPM이 휘도신호 $4{\times}4$블록의 최적의 모드로 선택되고 종료된다. JM 참조 소프트웨어를 통한 실험결과 제안된 기법은 기존 JM의 방식에 비해 화면 내 프레임의 부호화 시간의 84.7% 감소와 0.049dB의 PSNR 감소율, 0.595%의 비트 증가율을 보여주었다.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.9 no.5
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• pp.458-464
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• 2016

This paper proposes the compensation method which decreases the radiation pattern distortion caused by the mutual coupling in an array antenna. If the element distance of an array antenna decreases, the radiation pattern could be distorted by the strong mutual coupling, which changes the magnitude and phase of input signals and causes an unwanted radiation pattern. To remove the pattern distortion, compensated input signals are inserted in an array antenna. The magnitude and phase of input signals are determined by Particle Swarm Optimization (PSO) algorithm. A $4{\times}1$ dipole array antenna with omnidirectional elements is used to confirm the validity of the algorithm, where each element is placed in 0.2 wavelength to evoke the strong coupling. After input signals are optimized by PSO, it is found that the compensated radiation results in the same as the ideal case.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.10
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• pp.70-78
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• 2009

This paper addresses the analysis and the design optimization of differential interconnects for high-speed Low-Voltage Differential Signaling (LVDS) applications. Thanks to the differential transmission and the low voltage swing, LVDS offers high data rates and improved noise immunity with significantly reduced power consumption in data communications, high-resolution display, and flat panel display. We present an improved model and new equations to reduce impedance mismatch and signal degradation in cascaded interconnects using optimization of interconnect design parameters such as trace width, trace height and trace space in differential printed circuit board (FPCB) transmission lines. We have carried out frequency-domain full-wave electromagnetic simulations, and time-domain transient simulations to evaluate the high-frequency characteristics of the differential FPCB interconnects. We believe that the proposed approach is very helpful to optimize high-speed differential FPCB interconnects for LVDS applications.

• Journal of Korean Society of Transportation
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• v.22 no.7 s.78
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• pp.131-137
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• 2004

Conventional traffic signal optimization models assume that green intervals for pedestrian crossings are given as exogenous inputs such as minimum green intervals for straight-ahead movements. As the result, in reality, the green intervals of traffic movements may not distribute adequately by the volume/saturation-flow of them. In this paper, we proposed signal optimization models formulated in BMILP to integrate pedestrian crossings into traffic movements under under-saturated traffic flow. The model simultaneously optimizes traffic and pedestrian movements to minimize weighted queues of primary queues during red interval and secondary queues during queue clearance time. A set of linear objective function and constraints set up to ensure the conditions with respect to pedestrian and traffic maneuvers. Numerical examples are given by pedestrian green intervals and the number of pedestrian crossings located at an arm. Optimization results illustrated that pedestrian green intervals using proposed models are greater than those using TRANSYT-7F, but opposite in the ratios of pedestrian green intervals to the cycle lengths. The simulation results show that proposed models are superior to TRANSYT-7F in reducing delay, where the longer the pedestrian green interval the greater the effect.

• Proceedings of the Korean Society of Computer Information Conference
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• 2021.07a
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• pp.201-202
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• 2021

본 논문에서는 다중 엑세스 포인트 환경에서 전송전력, 수신필터, 엑세스 포인트 선정 최적화 알고리즘을 제안한다. 최종목적은 신호대간섭비를 유지하면서, 전송전력의 총합을 최소화하는 것이다. 증명을 통해서 제안하는 알고리즘은 최소전력에 수렴함을 보인다. 제안하는 알고리즘이 기존에 제안되었던 두 개의 알고리즘인 1)전송전력과 최소제곱평균오차(MMSE) 수신필터 최적화 알고리즘, 2) 전송전력 최적화 알고리즘보다 전송전력 소모량에서 성능이 우수함을 실험을 통해서 확인하였다.

• Journal of the Korea Society of Computer and Information
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• v.12 no.6
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• pp.235-242
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• 2007

Network Mobility Basic Support protocol reduces location-update signaling by making network movements transparent to the mobile nodes (MNs) behind the mobile router (MR), but causes some problems such as sub-optimal routing and multiple encapsulations. This paper proposes an Route Optimization Employing HMIP Extension for Mobile Networks (ROHMIP) scheme for nested nubile networks support which introduces HMIP concept with relation information between MNNs behind a MR and the MR in order to localize handoff, to optimize routing and especially reduce handoff signal overhead. With ROHMIP, a mobile network node (MNN) behind a MR performs route optimization with a correspondent node (CN) as the MR sends a binding update message (BU) to mobility anchor point (MAP) via root-MR on behalf of all active MNNs when the mobile network moves. This paper describes the new mechanisms and provides simulation results which indicate that our proposal reduces transmission delay, handoff latency and signaling overhead.

• The Journal of the Acoustical Society of Korea
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• v.29 no.7
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• pp.411-421
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• 2010

A time-reversal mirror (TRM) is useful in diverse areas, such as reverberation ing, target echo enhancement and underwater communication. In underwater communication, the bit error rate has been improved significantly due to the increased signal-to-noise ratio by spatio-temporal focusing. This paper deals with two issues. First, the optimal number of array elements for a given environment was investigated based on the exploitation of spatial diversity. Second, an algorithm was developed to determine the optimal location of the given number of array elements. The formulation is based on a genetic algorithm maximizing the contrast between the foci and area of interest as an objective function. In addition, the developed algorithm was applied to the matched field processing with ocean experimental data for verification. The sea-going data and simulation showed almost 3 dB improvement in the output power at the foci when the array elements were optimally distributed.

• Journal of Korean Society of Transportation
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• v.17 no.2
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• pp.127-135
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• 1999

Most existing progression bandwidth models maximize the single or multi weighted sum of bandwidths in the both directions to improve traffic mobility on an arterial, but they cannot be applied to general networks. Even though a few models formulating a looped network problem cannot be applied to networks have not loops. Also they have some defects in optimizing phase sequences. Therefore, the objective of this study is to develope a mathematical formulation of the synchronization problem for a general traffic network. The goal is achieved successfully by introducing the signal phasing for each movement and expanding the mixed integer linear programming of MAXBAND. The experiments indicate that the proposed model can formulate the general traffic network problem mere efficiently than any other model. In conclusion, this model may optimize signal time to smooth progression in the general networks.