• Journal of Electrical Engineering and Technology
• /
• 제7권4호
• /
• pp.493-500
• /
• 2012

In this paper the performance of meta-heuristics algorithms such as GA (Genetic Algorithm), DE (Differential Evolution), PSO (Particle Swarm Optimization) and SA (Simulated Annealing) for the problem of TTC enhancement using FACTS devices are compared. In addition to that in the assessment procedure of TTC two novel techniques are proposed. First the optimization algorithm which is used for TTC enhancement is simultaneously used for assessment of TTC. Second the power flow is done using Broyden - Shamanski method with Sherman - Morrison formula (BSS). The proposed approach is tested on WSCC 9 bus, IEEE 118 bus test systems and the results are compared with the conventional Repeated Power Flow (RPF) using Newton Raphson (NR) method which indicates that the proposed method provides better TTC enhancement and computational efficacy than the conventional procedure.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.2043-2052
• /
• 2008

The increasing heat generation rates in CPU of notebook computers motivate a research on cooling technologies with low thermal resistance. This paper develops a closed-loop two-phase cooling system using a micropump to circulate a dielectric liquid(PF5060). The cooling system consists of an evaporator containing a boiling enhancement microstructure connected to a condenser with mini fans providing external forced convection. The cooling system is characterized by a parametric study which determines the effects of volume fill ratio of coolant, existence of a boiling enhancement microstructure and pump flow rates on thermal performance of the closed loop. Experimental data shows the optimal parametric values which can dissipate 33.9W with a film heater maintained at $95^{\circ}C$.

• ETRI Journal
• /
• 제33권6호
• /
• pp.841-848
• /
• 2011

A signal-to-noise ratio (SNR) enhancement algorithm using multiple chirp symbols with clock drift is proposed for accurate ranging. Improvement of the ranging performance can be achieved by using the multiple chirp symbols according to Cramer-Rao lower bound; however, distortion caused by clock drift is inevitable practically. The distortion induced by the clock drift is approximated as a linear phase term, caused by carrier frequency offset, sampling time offset, and symbol time offset. SNR of the averaged chirp symbol obtained from the proposed algorithm based on the phase derotation and the symbol averaging is enhanced. Hence, the ranging performance is improved. The mathematical analysis of the SNR enhancement agrees with the simulations.

• 디지털산업정보학회논문지
• /
• 제15권1호
• /
• pp.99-107
• /
• 2019

Retinex-based image enhancement is a technique that utilizes the property that the human visual characteristics are sensitive to the difference from the surrounding pixel value rather than the pixel value itself. These Retinex-based algorithms show different characteristics of the improved image depending on the applied color space or gamma correction. In this paper, we set eight different experimental conditions according to the application of color space and gamma correction, and analyze the objective and subjective performance of each Retinex based image enhancement algorithm and apply it to the implementation of Retinex based algorithm. In the case of gamma correction, quantitative low entropy images and low contrast images are obtained. The application of Retinex technique in HSI color space rather than RGB color space is found to be high in overall subjective image quality as well as maintaining color.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2009년도 정보 및 제어 심포지움 논문집
• /
• pp.115-117
• /
• 2009

This paper presents localization performance enhancement on GPS interfering spot for mobile robot. Localization system applied Extended Kalman filter algorithm that utilized Diffrential GPS and odometry, inertial sensors. In this paper, different noise covariance is applied to Extended Kalman Filter according to the GPS quality. Experiment results show that proposed localization system improve considerably localization performance of mobile robots.

• 한국전자통신학회논문지
• /
• 제14권5호
• /
• pp.901-906
• /
• 2019

무인항공기는 오락산업을 비롯하여 민간 및 국방 분야 등의 다양한 분야에서 널리 적용되고 있다. 무인항공기를 통신시스템에 적용하는 기술 또한 주요한 응용분야 중 하나이다. 중계기는 통신성능향상 및 통신거리 확장의 장점으로 인해 통신시스템에서 많은 관심을 받아왔다. 본 논문에서는 중계기로의 무인항공기에 대한 연구동향을 물리계층에 초점을 맞추어 알아본다. 먼저 현재 무인항공기를 중계기로 적용하여 연구된 사항을 소개하고 무인항공기를 이용한 중계네트워크의 기본적인 성능을 듀얼홉 통신시스템에서 복조 후 전송 프로토콜을 적용하여 분석한다. 성능은 심벌오류율로 나타내며 무인항공기 채널은 비대칭 환경을 가정하여 적용한다. 마지막으로 성능분석을 기반으로 하여 물리계층에서 성능향상을 위해 필요한 사항에 대해 논의한다.

• Advances in concrete construction
• /
• 제5권3호
• /
• pp.201-219
• /
• 2017

With the rapid growth in construction sector, it becomes all the more important to assess the amount of Construction and Demolition (C&D) waste being generated and analyze the practices needed to handle and use this waste before final disposal. This serves waste management and disposal issues, paving way to waste utilization in construction industry from the sustainability point of view. C&D waste constitutes a major bulk of total solid waste produced in the world. In this work, an attempt is made to study the performance of concrete using water soaked Recycled Coarse Aggregates (RCA) in replacement levels of 0%, 25%, 50%, 75% and 100% to Natural Coarse Aggregates (NCA). Experiments were designed and conducted to study the performance of RCA based concrete. Further suitable performance enhancement techniques to RCA based concrete were attempted, to achieve compressive strength at least equal to or more than that for no RCA based concrete (control concrete). Performance enhancement study is reported here for 50% and 100% RCA based concretes. All four techniques attempted have given favorable results encouraging use of RCA based concretes with full replacement levels, to adopt RCA based concrete in structural applications, without any kind of concern to the stake holder. Further attempts have also been made to use Recycled Fine Aggregates (RFA) with appropriate modifications to serve as fine aggregates in mortar and concrete. Using RFA blended with river sand fractions as well as RFA with Iron Ore Tailings (IOT) fractions, have given good results to serve as fine aggregates to the extent of 100% replacement levels in mortars and concretes.

• IEIE Transactions on Smart Processing and Computing
• /
• 제3권6호
• /
• pp.358-365
• /
• 2014

This paper proposes a method that reduces the flickering effect caused by A-GLG (Adaptive Gray-Level Grouping) during video contrast enhancement. Of the GLG series, A-GLG shows the best contrast enhancement performance. The GLG series is based on histogram grouping. Histogram grouping is calculated differently between the continuous frames with a similar histogram and causes a subtle change in the transformation function. This is the reason for flickering effect when the video contrast is enhanced by A-GLG. To reduce the flickering effect caused by A-GLG, the proposed method calculates a modified transformation function. The modified transformation function is calculated using a previous and current transformation function applied with a weight separately. The proposed method was compared with A-GLG for flickering effect reduction and video contrast enhancement. Through the experimental results, the proposed method showed not only a reduced flickering effect, but also video contrast enhancement.

• JSTS:Journal of Semiconductor Technology and Science
• /
• 제4권4호
• /
• pp.263-268
• /
• 2004

In this paper, we motivate the post-mask performance enhancement technique combined with the Multi-Threshold Voltage CMOS (MTCMOS) leakage current suppression technology, and integrate the new design issues related to the MTCMOS technology into the ASIC design methodology. The issues include short-circuit current and sneak leakage current prevention. Towards validating the proposed techniques, a Personal Digital Assistant (PDA) processor has been implemented using the methodology, and a 0.18um process. The fabricated PDA processor operates at 333MHz which has been improved about 23% at no additional cost of redesign and masks, and consumes about 2uW of standby mode leakage power which could have been three orders of magnitude larger if the MTCMOS technology was not applied.

• 품질경영학회지
• /
• 제24권3호
• /
• pp.1-18
• /
• 1996

The purpose of this study is to empirically examine the role of supplier relationships as a means of enhancement of quality. The model for this study consists of four groups of concepts - 1) goal of quality, as 2) measures of supplier relationships, supplier assistance and buyer supplier communication, 3) the level of automation and technology, as 4) measures of performance, reliability quality and performance quality. By statistical analysis, the results are as follows. First, the goal of quality positively influences the level of automation, technology, supplier assistance and supplier communication. Second, the level of technology has a positive effect on supplier assistance and supplier communication on the level of automation. Third, the level of automation and technology positively influence the reliability quality. Fourth, supplier assistance and buyer-supplier communication has a positive effect on the reliability and performance quality. These results reveal three paths of supplier relationships in systems for the enhancement of quality.