• Proceedings of the Korea Inteligent Information System Society Conference
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• 2001.01a
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• pp.78-82
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• 2001

Most of current Internet auction systems are simple server programs that partly automated the function of the conventional auction house. These system do not provide sufficient independence, distribution and parallelism between the functions of the conventional auction house. In there are automated by server program, but still users need to execute a repetitive task to monitor the dynamic progress of a certain auction, decide proper bid price, and submit the bid. Another problem is that they support only single as English auction and Dutch auction, but they do not support the double auctions are superior to the single auction with respect to speed., efficiency, and the fair distribution of profit. In this paper, we present design and implement of an agent-based continuous double auction system, called CoDABot, in order to mitigate the limitations of current auctions system. CoDABot supports continuous double auction, provides various bidding agent for users to select, and has been implemented into a multi-agent system that realize more independent, distributed, and parallel subsystems.

• Korean Journal of Artificial Intelligence
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• v.9 no.2
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• pp.23-28
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• 2021

In this paper, we studied a system that can efficiently build security management for single-person households using Arduino, ESP32-CAM and PIR sensors, and proposed an Android app with an internet connection. The ESP32-CAM is an Arduino compatible board that supports both Wi-Fi, Bluetooth, and cameras using an ESP32-based processor. The PCB on-board antenna may be used independently, and the sensitivity may be expanded by separately connecting the external antenna. This system has implemented an Arduino-based Unauthorized intrusion system that can significantly help prevent crimes in single-person households using the combination of PIR sensors, Arduino devices, and smartphones. unauthorized intrusion system, showing the connection between Arduino Uno and ESP32-CAM and with smartphone applications. Recently, if daily quarantine is underway around us and it is necessary to verify the identity of visitors, it is expected that it will help maintain a safety net if this system is applied for the purpose of facial recognition and restricting some access. This technology is widely used to verify that the characters in the two images entered into the system are the same or to determine who the characters in the images are most similar to among those previously stored in the internal database. There is an advantage that it may be implemented in a low-power, low-cost environment through image recognition, comparison, feature point extraction, and comparison.

• The KSFM Journal of Fluid Machinery
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• v.17 no.1
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• pp.47-53
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• 2014

This paper aims to present the design and performance evaluation of a counter-rotating tidal turbine using CFD and to compare its performance with single rotor. The device scale is 10kW and the rotating part consists of two rotors which rotate in opposite direction. Compared with conventional single rotor, the counter-rotating system shows higher power efficiency at high stream velocity but lower efficiency at low stream velocity. The added counter-rotated rotor together helps improve the energy absorption capacity but has influence on the upstream rotor that reduces its performance. In terms of power capture, the designed counter-rotating tidal turbine is more advantageous in high speed tidal condition.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.459-462
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• 2008

This paper describes the design of single body type repeater antenna for isolation enhancement between donor and receptor antennas. The antenna system consists of cavity, triangular patch antenna and cavity reflector. The antenna satisfies return-loss and isolation specifications in the desired band while the broadside gain is a little bit short from the spec.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.44 no.4 s.316
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• pp.21-26
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• 2007

Output voltage waves of a DC/AC inverter system are likely to be distorted if variable loads e.g. motors or rectifiers exist in the output terminal. This paper designs a disturbance observer-based PI-controller for a single-phase inverter system that is robust against load changes. In this Paper, we regard the output voltage changes due to various loads as disturbances of the control system. Then we design a disturbance observer for estimation of the disturbances caused by the load current and any other error sources (such as parameter uncertainties and model mismatches etc.). In order to test the performance of the proposed control law, simulation studies are carried out for a single-phase inverter system using SimPowerSystem of Matlab Simuink. Compared to a simple PI-control, the disturbance observer-based controller shows enhanced performance in transient responses for step load changes.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.809-812
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• 1999

The pendulum is a SIMO(Single-input multi-output) system that both angle of pendulum and position of cart controlled simultaneously by one actuator. In this paper, propose a hybrid neuro-controller to apply to pendulum system. We design the conventional optimal controller and the neural network as a identifier, which can identify the uncertainty of plant not modeled, respectively. Then we combine them into a novel controller, with a structure that the error between plant and identifier is added in conventional optimal control input Finally, the paper shows the validity of the proposed controller through computer simulations and experiments.

• Journal of the Korea Society for Simulation
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• v.8 no.3
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• pp.1-16
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• 1999

This paper deals with a discrete simulation optimization method for designing a complex probabilistic discrete event system. The proposed algorithm in this paper searches the effective and reliable alternatives satisfying the target values of the system to be designed through a single run in a relatively short time period. It tries to estimate an autoregressive model, and construct mean and confidence interval for evaluating correctly the objective function obtained by small amount of output data. The experimental results using the proposed method are also shown.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.2
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• pp.207-216
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• 2000

This paper introduces an effective system design method to develop a customer oriented product using a design optimization process and to select a set of critical design paramenters,. The process results in the development of a successful product satisfying customer needs and reducing development risk. The proposed scheme adopted a five step QFD(Quality Function Deployment) in order to extract design parameters from customer needs and evaluated their priority using risk factors for extracted design parameters. In this process we determine critical design parameters and allocate them to subsystem designers. Subsequently design engineers develop and test the product based on these parameters. These design parameters capture the characteristics of customer needs in terms of performance cost and schedule in the process of QFD, The subsequent risk management task ensures the minimum risk approach in the presence of design parameter uncertainty. An application of this approach was demonstrated in the development of weld quality monitoring system. Dominant design parameters affect linearity characteristics of weld defect feature vectors. Therefore it simplifies the algorithm for adopting pattern classification of feature vectors and improves the accuracy of recognition rate of weld defect and the real time response of the defect detection in the performance. Additionally the development cost decreases by using DSP board for low speed because of reducing CPU's load adopting algorithm in classifying weld defects. It also reduces the cost by using the single sensor to measure weld defects. Furthermore the synergy effect derived from the critical design parameters improves the detection rate of weld defects by 15% when compared with the implementation using the non-critical design parameters. It also result in 30% saving in development cost./ The overall results are close to 95% customer level showing the effectiveness of the proposed development approach.

• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.4
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• pp.181-186
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• 2013

The construction costs for nonstructural systems such as mechanical/electrical equipment, ceiling system, and piping system occupy a significant proportion of the total cost. These nonstructural systems can also cause considerable economic losses and loss of life during and after an earthquake. Therefore, reduction of seismic risk of nonstructural components has been emerging as a key aspect of research in recent year. The primary objective of this study was to evaluate the seismic performance of a single-story and multi-story piping system installed in low-rise building and to identify the seismic vulnerability of the current piping systems. The seismic performance evaluation of the piping systems was conducted with 5 different earthquakes to account for the ground motion uncertainty and the preliminary results demonstrated that the maximum displacements of each floor in the multi-story piping system increased linearly with increasing floor level in the building system. This study revealed that the current design piping systems are significantly sensitive to the effect of floor height, which stress the necessity to improve the seismic performance of the current piping systems by, for example, strengthening with seismic sway bracing using transverse/longitudinal bracing cables or hangers.

• Journal of IKEEE
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• v.12 no.4
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• pp.239-245
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• 2008

In this paper, a dc-dc power converter scheme with the FPGA based technology is proposed to apply for solar power system which has many features such as the good waveform, high efficiency, low switching losses, and low acoustic noises. The circuit configuration is designed by the conventional control type converter circuit using the isolated dc power supply. This new scheme can be more widely used for industrial power conversion system and many other purposes. Also, I proposed an efficient photovoltaic power interface circuit incorporated with a FPGA based DC-DC converter and a sine-pwm control method full-bridge inverter. The FPGA based DC-DC converter operates at high switching frequency to make the output current a sine wave, whereas the full-bridge inverter operates at low switching frequency which is determined by the ac frequency. As a result, we can get a 1.72% low THD in present state using linear control method. Moreover, we can use stepping control method, we can obtain the switching losses by Sp measured as 0.53W. This paper presents the design of a single-phase photovoltaic inverter model and the simulation of its performance.