• 전기의세계
• /
• v.42 no.12
• /
• pp.65-73
• /
• 1993

지금까지 산업용 유도전동기의 속도 제어에 필요한 전류 제어기법과 센서리스 벡터 제어, 벡터 제어계의 실험 적용되고 있는 몇종류의 현대 제어이론에 대한 기본개념과 동향을 살펴보고자 한다.

• Journal of the Institute of Electronics Engineers of Korea TC
• /
• v.48 no.8
• /
• pp.1-6
• /
• 2011

In this paper, another analytical approach for dual-hop amplify-and-forward(AF) relay systems is proposed over Rayleigh fading channels. Previous approaches derived the moment generating function(MGF) by using the cumulative distribution function(CDF) or probability density function(PDF) of the received signal-to-noise ratio(SNR) for source-relay-destination(S-R-D) link. Then, the average symbol error rate is expressed based on derived MGFs. In this paper, another new approach is proposed. It means that the MGF is directly derived by utilizing PDFs of both source-relay(S-R) and relay-destination(R-D) links. Additionary, the newly derived MGF is compared and analyzed with previous ones. Furthermore, simulation results are presented to validate the accuracy of proposed analytical expression. Based on this, it is confirmed that the proposed analytical approach can be a another solution for dual-hop AF relay systems.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.29 no.3
• /
• pp.253-260
• /
• 2016

In this paper, the optimal seismic design method for inducing the beam-hinge collapse mechanism of steel moment frames is presented. This uses the non-dominated sorting genetic algorithm II(NSGA-II) as an optimal algorithm. The constraint condition for preventing the occurrence of plastic hinges at columns is used to induce the beam-hinge collapse mechanism. This method uses two objective functions to minimize the structural weight and maximize the dissipated energy. The proposed method is verified by the application to nine story steel moment frame example. The minimum column-to-beam strength ratio to induce the beam-hinge collapse mechanism are investigated based on the simulation results. To identify the influence of panel zone on the minimum column-to-beam strength ratio, three analytic modeling methods(nonlinear centerline model without rigid end offsets, nonlinear centerline model with rigid end offsets, nonlinear model with panel zones) are used.

• Journal of Biomedical Engineering Research
• /
• v.24 no.4
• /
• pp.339-346
• /
• 2003

MRI provides anatomical structure information with superb spatial resolution that can be utilized in clinical surgeries. Advanced image processing techniques in conjunction with the MRI-guided surgery is expected to be of great importance in brain surgeries in the near future. In this paper, we introduce an image-guided surgery technique using the stereo matching method. To perform image-guided biopsy operations, we made MRI markers, camera markers and a detection probe marker. To evaluate the accuracy of the image-guided system. we made a silicone phantom. Using the phantom and markers, we have performed MRI-guided experiments with a 1.5 Tesla MRI system. It has been verified from phantom experiments that our system has a positioning error less than 1.5%. Compared with other image guided surgery system, our system shows better positioning accuracy.

• Journal of the Korea Society of Computer and Information
• /
• v.12 no.6
• /
• pp.167-175
• /
• 2007

Fuzzy logic is used to represent qualitative knowledge and provides interpretability to a controlling system model in bioinformatics. This paper focuses on a bioinformatics data classification which is an important bioinformatics application. This paper reviews the two traditional controlling system models The sequence-based threshold controller have problems of optimal range decision for threshold readjustment and long processing time for optimal threshold induction. And the binary-based threshold controller does not guarantee for early system stability in the GPCR data classification for optimal threshold induction. To solve these problems, we proposes a fuzzy-based threshold controller for ART1 clustering in GPCR classification. We implement the proposed method and measure processing time by changing an induction recognition success rate and a classification threshold value. And, we compares the proposed method with the sequence-based threshold controller and the binary-based threshold controller The fuzzy-based threshold controller continuously readjusts threshold values with membership function of the previous recognition success rate. The fuzzy-based threshold controller keeps system stability and improves classification system efficiency in GPCR classification.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.39 no.6
• /
• pp.505-516
• /
• 2011

The concept of the IGC(Integrated Guidance and Control) has been introduced to overcome the performance limit of the SGC(Separated Guidance and Control) loop. A new type of IGC with impact angle constraint has been proposed in this paper. Angle of attack, pitch angle rate, pitch angle and line of sight angle are considered as state variables. A controllability analysis and equilibrium point analysis have been carried out to investigate the control characteristic of the prposed IGC. The LQR(Linear Quadratic Regulator) has been adopted for the control law and detailed explanations about the adoption has been provided. The performance comparison between the IGC and the SGC has been carried out. The result of numerical simulations shows that the IGC guarantees better guidance performance than the SGC when the agile maneuver is needed for a specific guidance geometry.

• The Transactions of the Korea Information Processing Society
• /
• v.6 no.1
• /
• pp.216-224
• /
• 1999

In the paper we propose two recovery methods by adopting a rollback and/or roll-forward technique (S) to recover TMR failures in a TMR (structured ) system that is the simplest spatial redundancy. This technique is apparently effective to recovering TMR failures primarily caused by transient faults. The proposed policies carry out few reconfigurations at the cost of (minimal) time-overhead needed for those time-redundant schemes. The optimal checkpoint-interval vectors are derived for both methods through the likelihoods of all (possible) states of the system as well as the total execution-time. Consequently the effectiveness of our proposed policies is validated through certain numerical examples and simulations.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.11 no.6
• /
• pp.563-569
• /
• 2006

In this paper, the system to control the PWM inverter-induction motor drive system including ac current sensors, voltage sensors, and an encoder through the network is developed. Although the network-based control for an induction motor drive system is becoming increasingly important at factory automations, there will inevitably be time delay from the sensors to the motor control system, which may cause the instability. The algorithm to minimize the efforts for network induced time delay of sensor data is proposed, using both the synchronous signal and the method for estimating sensor data. The experiments with DSP are carried out in order to verify proposed algorithms.

• Journal of Korea Society of Industrial Information Systems
• /
• v.23 no.1
• /
• pp.43-52
• /
• 2018

This paper presents the performance of a Phase Shift Full Bridge (PSFB) converter with inductive load and a new current control scheme to improve dynamic response of output current with various inductive loads. Enhanced dynamic model is used which includes leakage inductance and inductive load. Effect of changing of inductive load was analyzed in detail. Proposed current control scheme is designed based on phase margin specifications. As a result, the proposed current control scheme helps to improve the dynamic response in comparison with the existing current control scheme. The performance of the designed controller is verified by a 500 A PSFB converter. The results will be utilized for high current applications with high inductive load such as superconducting devices.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.25 no.2
• /
• pp.95-102
• /
• 2005

There are many tube and pipeline in nuclear power plant under high temperature and high pressure. Erosion and corrosion defects were expected on these tube and pipe-line by environmental and mechanical factors. These erosion and corrosion defects ran be evaluated by ultrasonic technique. In these study, Scanning Laser Source(SLS) technique was applied to detect defect and construct image. This technique also makes detection possible on rough and curved surfaces such as tube and pipe-line by scanning. Conventional ultrasonic scanning technique requires immersion of specimen or water jet for transferring ultrasonic wave between transducer and specimen. However, this SLS technique does not need contacting and couplant to generate surface wave and to get flaw images. Therefore, this SLS technique has several advantages, for complicated production inspection, non-contact, remote from specimen, and high resolution. In this study, SLS images were obtained with various conditions of generation laser ultrasound and receiving in order to enhance detectability of flaws on the tube. Stress corrosion cracks were produced on tube and images of stress corrosion cracks were constructed by using SLS technique.