• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.12
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• pp.602-607
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• 2000

This paper presents the new simulation algorithms using network methods to analysis the steady-state train voltage distribution characteristics in ac auto-transformer fed railroads. In general, the supply system of railroads is composed of non-symmetrical and unbalance transmission line. Therefore, the general method using simplified old algorithms have the self-contradictory errors because the supply line of train railroads is completely unbalanced. In this paper, the simulation results of new developed algorithms is compared with those of EMTP to confirm the effectiveness.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.56 no.1
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• pp.28-36
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• 2007

Sensor networks are usually composed of tens or thousands of tiny devices with limited resources. Because of their limited resources, many researchers have studied on the energy management in the WSNs(Wireless Sensor Networks), especially taking into account communications efficiency. For effective data transmission and sensor fault detection in sensor network environment, a new remote monitoring system based on PCA(Principle Component Analysis) and AANN(Auto Associative Neural Network) is proposed. PCA and AANN have emerged as a useful tool for data compression and identification of abnormal data. Proposed system can be effectively applied to sensor network working in LEA2C(Low Energy Adaptive Connectionist Clustering) routing algorithms. To verify its applicability, some simulation studies on the data obtained from real WSNs are executed.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04d
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• pp.283-285
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• 2003

슈퍼컴퓨터 사용자들은 FTP(File Transfer Protocol)을 이용해서 대용량의 파일을 전송한다. 전송되는 데이터들은 승용차나 비행기 설계, 의약품 개발. 기상 예보 그리고 복잡한 수학적 계산 등과 같이 다양한 분야에 걸친 연구관련 데이터로서 고성능 슈퍼컴퓨터에 의한 연산 처리가 요구된다 기존의 FTP 는 네트워크 상태에 따라 전송 지연이나 데이터 손실 등의 문제로 사용자의 불편을 초래하였다. 이에 전송 성능을 효율적으로 높이고 데이터 손실을 최소화를 제공하는 연구가 필요하다. 근래의 TCP (Transmission Control Protocol) 성능 향상 연구에 관한 연구들의 관심은 크게 두 가지이다. 하나는 윈도우 사이즈 조절(auto-tuning)이고, 다른 하나는 Multi-stream 이다. 본 연구에서는 파일 전송 성능 향상을 위한 방법으로 윈도우 사이즈 조절 방법을 사용하였고, 네트워크 상태에 따라 QoS(quality of Service)를 제공한다. 이런 성능 향상 결과로 신뢰성 있는 네트워크를 제공하여 사용자들은 신속하게 데이터를 전송하며 연산처리 결과가 더욱 정확하다고 신뢰할 수 있다. 본 고에서는 대용량 파일을 전송 할 때 성능을 향상시키는 관련 연구를 알아보고 대용량 파일 전송 중 네트워크 상태에 따라 005를 능동적으로 작용하여 테스트하고 성능을 분석하였다.

• Proceedings of the KIEE Conference
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• summer
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• pp.289-291
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• 2004

ln this paper, A dc-offset elimination novel algorithm based on an An model is proposed. The algorithm can eliminate dc-offset rapidly than other algorithms. The signal of fault current can be presented as a linear equation combined sinusoidal with exponential signals. Then, the linear equation can be presented an auto-regressive(AR) model and do-offset can be calculated by the equation of AR model. So it is possible to be removed the dc-offset from the original current signal. Performance evaluation of the algorithm was tested on condition that A-phase ground fault on 154kV 25km overhead transmission line.

• Korean Journal of Metals and Materials
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• v.49 no.6
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• pp.448-453
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• 2011

Pre-aging heat treatment after solution heat treatment (SHT) of Al-0.4 wt%Mg-1.2 wt%Si-0.1 wt%Mn alloy sheets for auto-bodies was carried out to investigate the effect of pre-aging and its conditions on the bake-hardening response. Mechanical properties were evaluated by a tensile and Vickers hardness test. Microstructural observation was also performed using a transmission electron microscope (TEM). It was revealed that pre-aging treatments play a great role in the bake-hardening response. In addition, it was found that the sphere-shaped nanosized clusters that can directly transit to the needle-shaped ${\beta}$" phase during the paint-bake process, not being dissolved into the matrix, are formed at 343 K. The result, reveals that the dominant factor of the bake-hardening response is the pre-aging temperature rather than the pre-aging time.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.467-468
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• 2011

본 논문에서는 촉각전달장치를 기반으로 수식에 대한 그래프와 도형과 같은 시각교육정보들을 촉각 정보로 자동 변환하여 제공하는 프로그램을 구현하였다. 구현한 프로그램으로는 입력된 그래픽 정보를 촉각정보전달 장치의 해상도에 적합하게 다운샘플링(downsampling)을 수행한 후, 이진화(binarization)를 통해 촉각신호를 생성한다. 그리고 이를 촉각정보전달 장치에 전달하여 출력함으로써, 시각장애인들에게 그래픽 정보를 촉각정보로 변환하여 제공할 수 있다. 결과적으로 본 프로그램을 통해 수학 및 과학과 같은 이공계열의 교육정보를 편리하고 빠르게 촉각정보로 변환하여 시각장애인들에게 제공할 수 있었다.

• International journal of advanced smart convergence
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• v.13 no.1
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• pp.201-205
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• 2024

Currently, the most important issue on the earth is global warming, which causes climate change and leads to disasters. For this reason, each country is focusing on renewable energy, carbon neutrality, environmentally friendly energy and transportation. Bicycles used as short-distance vehicles do not emit gases harmful to the human body that pollute the Earth's atmosphere. Also, the use of bicycles has the effect of improving the health of people, and each country is designing a short distance transportation network using bicycles. In this study, we propose a model of a bicycle power-train that can use a belt as a power transmission medium. The basic principles and methods for applying the proposed new type of power-train to bicycles are presented.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.5
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• pp.30-37
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• 2015

The study for enhancing the data transmission rate of the next generation wireless communication system using MIMO system operating in the frequency selective fading environment is currently actively conducted. Mixed signal from each transmitted antennas are received at antennas. The training signal with orthogonal property is needed to separate the mixed signal and enable to estimate channel and time synchronization. In this paper we introduce several training sequences used in MIMO communication system and proposed the modified WeCAN sequence with good auto-correlation property in interested area. We compared auto-correlation property of each sequence via simulation and compared the performance of sequences in doppler shift and multipath fading channel.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.3
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• pp.274-283
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• 2006

The Permanent Magnet Synchronous Motor(PMSM) drive systems with ball-screw, gear and timing-belt are widely used in industrial applications such as NC machine, machine tools, robots and factory automation. These systems have torsional vibration in torque transmission from servo motor to mechanical load due to the mechanical couplings. This vibration makes it difficult to achieve quick responses of speed and may result in damage to the mechanical plant. This paper presents adaptive notch filter with auto searching function of vibration frequency to reject the mechanical vibration of linear feeder system with PMSM. The proposed adaptive notch filter can suppress the torque command signal of PMSM in the resonant bandwidth for reject the mechanical torsional vibration. However, the resonant frequency can vary with conditions of mechanical load system and coupling devices, adaptive notch filter can auto search the vibration frequency and suppress the vibration signal bandwidth. Computer simulation and experimental results shows the verification of the proposed adaptive notch filter in linear feeder system with PMSM.

• Korean Journal of Digital Imaging in Medicine
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• v.3 no.1
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• pp.126-132
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• 1997

Purpose : To apply to Program of Auto processor quality control after comparison of Film density variations with amendments to Auto density by using Check density program and Adjust density program of calibration mode into the Laser imager. Methods : Observe Check and Adjust density variations on the Control chart with standard step and value during seven months from December, 1995 to June, 1956 extending twice a week. (1) Measure density value on the steps after printing out 17-step sensitometric pattern of the Check density program. (2) In the same way, measure density values after amending density by using Adjust density program If they are exceeding allowable error limit. Results : In case of Check density program, the exceeding limit rates of Density difference(DD) and Middle density(MD) are: FL-IM3543 DD=75%. MD=72.5%, FL-IMD DD=0%. MD=30.8%(14.5%) After amending density by using Adjust density program, the exceeding limit rates of all both Laser imager were zero percent. The standard deviations are show lower FL-IM D than FL-IM3543 on the Check density control chart, but higher on the Adjust density control chart. Conclusion : (1) Check density variations by printingout sensitometric pattern extending once a week at least for quality control of the Laser imager. (2) In case of a dusty place, check the Laser beam transmission after cleaning Laser optical unit extending once a month. (3) Be sure to measure and check density values by using adjust density program if they are exceeding allowable error limit. (4) Maintain much better film density by performing the adjust density program even if check density values are existed within normal limit.