• Journal of Industrial Technology
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• v.24 no.A
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• pp.109-117
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• 2004

This paper presents a current control strategy to reduce torque ripple of Brushless DC Motor in commutation period with PWM pattern. The torque ripple is mainly caused by the inequality in the rate of change between rising current and decaying one during commutation. And also it is influenced by the shape of real back EMF. Therefore, in the proposed control strategy, considering real back EMF a compensation voltage is generated to equalize the rate of change in these commutating currents. And then, by providing the compensation voltage in commutation period with PWM pattern, the torque ripple can be reduced. The simulation and experimental results verify that the proposed method can reduce the torque and the current ripples significantly.

• The KIPS Transactions:PartB
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• v.8B no.5
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• pp.493-500
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• 2001

Video scene segmentation is fundamental role for content based video analysis. In this paper, we propose a new region based video scene segmentation method using continuity test for each object region which is segmented by the watershed algorithm for all frames in video data. For this purpose, we first classify video data segments into classes that are the dynamic and static sections according to the object movement rate by comparing the spatial and shape similarity of each region. And then, try to segment each sections by grouping each sections by comparing the neighbor section sections by comparing the neighbor section similarity. Because, this method uses the region which represented on object as a similarity measure, it can segment video scenes efficiently without undesirable fault alarms by illumination and partial changes.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.729-733
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• 2010

현재 진행 중인 4대강 살리기 사업은 정부가 가장 역점을 두는 사업이다. 또한 최근 발생하는 대형 홍수 및 가뭄은 21세기 물 관리에 대한 중요성을 인식시키기에 충분하다. 금강 살리기 사업은 안정적인 수자원 확보를 위하여 금남보, 금강보, 부여보 건설 및 하도준설을 통하여 0.5억$m^3$의 물을 확보하여 하천유지용수 및 생활용수 등으로 사용할 계획이며, 이중 금강보는 다기능 보로써 용수확보 및 홍수기 홍수조절 기능을 가지며, 공주지역의 랜드마크로 조성될 것이다. 본 연구에서는 금강보 기준 상 하류 2.5km 구간에 대하여 축척 1/60 정상모형으로 계획하였으며, 수리모형실험을 통하여 빈도별 홍수량에 대한 주요지점별 홍수위 검토, 보상류 수위 유속 및 유황검토를 통해 하도정비 및 다기능 보 설치에 따른 수리적 특성 및 흐름을 검토하였다. 계획홍수량 및 수문의 운영조건에 따른 유량에 대한 흐름분석에서 보가 위치한 지점과 상 하류 구간에서 모두 원활한 흐름이 이루어지는 것으로 나타났다.

• Journal of the Korea Computer Industry Society
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• v.9 no.4
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• pp.149-156
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• 2008

There is the temporal correlation of a animation sequence between the motion vector of current block and the motion vector of previous block. In this paper, we propose the scene change detection algorithm for block matching using the temporal correlation of the animation sequence and the center-biased property of motion vectors. The proposed algorithm determines the location of a better starting point for the search of an exact motion vector using the point of the smallest SAD(sum of absolute difference) value by the predicted motion vector from the same block of the previous frame and the predictor candidate point on each search region. Simulation results show that the proposed algorithm has better detection performance, such as recall rate, then the existing method. The algorithm has the advantage of speed, simplicity and accuracy. In addition, it requires less amount of storage.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.3
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• pp.191-198
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• 1998

This paper presents a new current control method to reduce the torque ripple due to phase commutation, when the unipolar PWM method is applied for the phase current control of brushless DC motor. Phase commutation bring about an instantaneous change in the average voltage of conducting phase so that current undulates, and this undulating current generates torque ripple. In this paper, we analyze average voltage variations of conducting phase in commutation period with PWM pattern and design current controller to compensate average variations. In addition, we prove the validity of proposed method by experimental results.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2003.11a
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• pp.395-400
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• 2003

For the long term storage safety study of the metallic spent fuel, U-Nb, U-Ti, U-Ni, U-Zr, and U-Hf simulated metallic uranium alloys, known as corrosion resistant alloys, were fabricated and oxidized in oxygen gas at $200^{\circ}C~300^{\circ}C$. Simulated metallic uranium alloys were more corrosion resistant than pure uranium metal, and corrosion resistance increases Nb, Ni, Ti in that order. The oxidation rates of uranium alloys determined and activation energy was calculated for each alloy. The matrix microstructure of the test specimens were analyzed using OM, SEM, and EPMA. It was concluded that Nb was the best acceptable alloying elements for reducing corrosion of uranium meta] considered to suitable as candidate.

• International Journal of Highway Engineering
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• v.13 no.3
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• pp.195-202
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• 2011

The purpose of this study is to estimate the capacity of two-lane freeway work zone blocking one lane using traffic flow models of each vehicle-type. Firstly, three traffic flow models of three different vehicle-types were developed using the data collected from each at the beginning and the ending point of the work zone. For each model, the maximum flow rate of three vehicle-types were calculated respectively. Maximum flow rate at the work zone was recalculated using passenger car equivalent value and percentage of vehicle-type. Secondly, traffic flow model using passenger car equivalent volume data was developed using the data collected from each at the beginning and the ending point of the work zone. Maximum flow rate for the work zone was calculated along. Two values of maximum flow rates through the work zone were compared and evaluated as the capacity of the work zone. This study found that the maximum flow rate of the work zone at the beginning point was less than that at the ending point because of impedance such as lane changing behaviors before entering the work zone. The capacity of two-lane freeway work zone blocking one lane was estimated 1,800pcphpl.

• Journal of Internet of Things and Convergence
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• v.8 no.4
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• pp.25-40
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• 2022

This study aimed to understand the increasing number of elder abuses in South Korea, where entry into the super-aged society is imminent, by implementing text mining analysis. Korean Academic journals were obtained from 2004, the establishment year of the senior care agency, to 2021. We performed natural language processing of the titles, keywords, and abstracts and divided them into three segments of periods to identify latent meanings in the data. The results illustrated that the first section included 81 papers, the second 64, and the third 104 respectively, averaging 13.8 annually, which increased its numbers from 2014 until the decrease below the annual average in 2020. Word frequency demonstrated that the common keywords of the entire segments were 'elder abuse,' 'elders,' 'influences,' 'factors,' 'recognition,' 'family,' 'society,' 'prevention plans,' 'experiences,' 'abused elders,' 'abuse prevention,' 'depression,' etc., in consecutive order. TF-IDF indicated that 'influences,' 'recognition,' 'society,' 'prevention plans,' 'abuse prevention,' 'experiences,' 'depression,' etc., were the common keywords of all divisions. Network text analysis displayed that the commonly represented keywords were 'elder abuse,' 'elders,' 'influences,' 'factors,' 'characteristics,' 'recognition,' 'family,' 'prevention plans,' 'society,' 'abuse prevention,' and 'experiences' in the entire sections. concor analysis presented that the first segment consisted of 5 groups, the second 7, and the third 6. We suggest future directions for elder abuse research based on the results.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.967-970
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• 2000

본 논문에서는 기동하는 표적을 추적하기 위한 표적의 운동 모델링 방법에 대해서 다룬다. 실제 표적의 운동은 진행방향으로의 가속과 이와는 독립적인 방향 전환으로 이루어진다는 점에 착안하여 표적의 진행방향에 따라 동작 잡음의 분산 행렬이 변화하는 표적 중심 모델을 제안하고, 이를 IMMPDAF(Interacting Multiple Model Probabilistic Data Association Filter)에 적용하였다. 모의실험을 통해 기존의 모델을 사용한 IMMPDAF와 비교하였으며, 그 결과 기동 구간의 오차가 30% 정도 줄어들며 추적 실패율도 낮아짐을 볼 수 있었다.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.185-186
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• 2012

본 논문에서는 고승압 소프트스위칭 양방향 컨버터의 스위칭 모드절환 시점을 제안하여 전류의 불연속 구간이 발생되지 않는 방법을 소개하여 일반적인 부스트 컨버터와 같이 일반적인 제어 알고리즘을 적용 가능함을 검증하였고 시뮬레이션 및 실험을 통해 타당성을 검증하였다.