• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.10 no.5
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• pp.105-111
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• 2010

In this paper the elasticity of fault-detection algorithm based on fuzzy logic is proposed through lots of experiments, justifying its validity. The four mathematical morpholgical operators was defined to detect the cracks. The cracks was detected via center of area method with ${\lambda}$-fuzzy measure of fuzzy sets. However generally favorable, the result owes to how adequate the lighting device is designed in case of the so far fine crack of pieces. In an attempt to improve the response of the system, It is designed to minimize the use of memory via LookUp table in software.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.65-77
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• 2004

In this paper, we propose an adaptive mechanism based on immune algorithm and neural network identifier technique. It is also applied fur an autonomous guided vehicle (AGV) system. When the immune algorithm is applied to the PID controller, there exists the case that the plant is damaged due to the abrupt change of PID parameters since the parameters are almost adjusted randomly. To solve this problem, we use the neural network identifier (NNI) technique fur modeling the plant and humoral immune algorithm (HIA) which performs the parameter tuning of the considered model, respectively. After the PID parameters are determined in this off-line manner, these gains are then applied to the plant for the on-line control using an immune adaptive algorithm. Moreover, even though the neural network model may not be accurate enough initially, the weighting parameters are adjusted to be accurate through the on-line fine tuning. Finally, the simulation and experimental result fur the control of steering and speed of AGV system illustrate the validity of the proposed control scheme. These results for the proposed method also show that it has better performance than other conventional controller design methods.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.448-454
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• 2010

Currently a KTX train of 20-car formation is 388m long and carries 931 passengers including one captain and three crews which is quite a few to cover the lengthy service area and many customers. On the other hand, if a passenger wants to talk to an attendant, he has to wait for an attendant passing by his/her seat or walk to an intercom which is placed at every other car. Any of these choices is inconvenient. So, in this paper, we presented a system design for developing an audio/visual communication system for a passenger and an attendant. The system was analyzed and designed according to the Object-Oriented methodology with UML (Unified Modeling Language). Based on a problem statement, a Use-case Diagram, Sequence Diagrams, Class Diagram, State Charts, collaboration Diagram were generated. The design will be used in system implementation to a HEMU-400X test train and to be tested.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.6
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• pp.783-790
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• 2012

Electric Vehicles(EVs) and Plug-in Hybrid Electric Vehicles(PHEVs) which have the grid connection capability, represent an important power system issue of charging demands. Analyzing impacts EVs charging demands of the power system such as increased peak demands, developed by means of modeling a stochastic distribution of charging and a demand dispatch calculation. Optimization processes proposed to determine optimal demand distribution portions so that charging costs and demand can possibly be managed. In order to solve the problems due to increasing charging demand at the peak time, alternative electricity rate such as Time-of-Use(TOU) rate has been in effect since last year. The TOU rate would in practice change the tendencies of charging time at the peak time. Nevertheless, since it focus only minimizing costs of charging from owners of the EVs, loads would be concentrated at times which have a lowest charging rate and would form a new peak load. The purpose of this paper is that to suggest a scenario of load leveling for a power system operator side. In case study results, the vehicles as regular load with time constraints, battery charging patterns and changed daily demand in the charging areas are investigated and optimization results are analyzed regarding cost and operation aspects by determining optimal demand distribution portions.

• Atmosphere
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• v.24 no.4
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• pp.471-479
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• 2014

A road surface temperature prediction model (UM-Road) using input data of the Unified Model (UM) output and road physical properties is developed and verified with the use of the observed data at road weather information system. The UM outputs of air temperature, relative humidity, wind speed, downward shortwave radiation, net longwave radiation, precipitation and the road properties such as slope angles, albedo, thermal conductivity, heat capacity at maximum 7 depth are used. The net radiation is computed by a surface radiation energy balance, the ground heat flux at surface is estimated by a surface energy balance based on the Monin-Obukhov similarity, the ground heat transfer process is applied to predict the road surface temperature. If the observed road surface temperature exists, the simulated road surface temperature is corrected by mean bias during the last 24 hours. The developed UM-Road is verified using the observed data at road side for the period from 21 to 31 March 2013. It is found that the UM-Road simulates the diurnal trend and peak values of road surface temperature very well and the 50% (90%) of temperature difference lies within ${\pm}1.5^{\circ}C$ (${\pm}2.5^{\circ}C$) except for precipitation case.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.625-630
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• 2000

Numerical and experimental investigations are peformed for the rarefied gas flows in pumping channels of a helical-type drag pump. Modern turbomolecular pumps include a drag stage in the discharge side, operating roughly in $10^{-2}{\sim}10Torr$. The flow occurring in the pumping channel develops from the molecular transition to slip flow traveling downstream. Two different numerical methods are used in this analysis: the first one is a continuum approach in solving the Navier-Stokes equations with slip boundary conditions, and the second one is a stochastic particle approach through the use of the direct simulation Monte Carlo(DSMC) method. The flow in a pumping channel is three-dimensional(3D), and the main difficulty in modeling a 3D case comes from the rotating frame of reference. Thus, trajectories of particles are no longer straight lines. In the Present DSMC method, trajectories of particles are calculated by integrating a system of differential equations including the Coriolis and centrifugal forces. Our study is the first instance to analyze the rarefied gas flows in rotating frame in the presence of noninertial effects.

• Journal of Power Electronics
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• v.18 no.3
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• pp.757-765
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• 2018

This paper deals with the instability and resonant phenomena in distribution systems with multiple grid-connected inverters with an LCL output filter. The penetration of roof-top and other types of small photovoltaic (PV) grid-connected systems is rapidly increasing in distribution grids due to the attractive incentives set forth by different governments. When the number of such grid-connected inverters increases, their interaction with the distribution grid may cause undesirable effects such as instability and resonance. In this paper, a grid system with several grid-connected inverters is studied. Since proportional-resonant (PR) controllers are becoming more popular, it is assumed that most inverters use this type of controller. An LCL filter is also considered at the inverters output to make the case as realistic as possible. A complete modeling of this system is presented. Consequently, it is shown that such a system is prone to instability due to the interactions of the inverter controllers. A modification of PR controllers is presented where the output capacitor is virtually decreased. As a result, the instability is avoided. Simulation results are presented and show a good agreement with the theoretical studies. Experimental results obtained on a laboratory setup show the validity of the analysis.

• International Journal of Highway Engineering
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• v.15 no.2
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• pp.149-157
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• 2013

PURPOSES : This study is to analysis for benefit and construction cost in underpass for small vehicles. METHODS : The study was performed using the traffic software VISSIM 5.20 for analysis on a variety of traffic conditions and analysed of benefits of changes through analysis of travel speed and travel time after modeling of existing underpass and small vehicle underpass. RESULTS : Results of this study, the benefits will be reduced by the introduction underpass for small vehicles were analyzed because heavy vehicles use the intersection above the underpass. However, it was required economic analysis considering both the benefits reduction and the construction costs reduction because it has the effect of reducing the construction cost. Showed that the difference in benefit changes depending on the v/c and heavy vehicles ratio and construction cost was difference by types of underpass. As a result of performing economic analysis with total benefits and construction cost, it was analyzed to be economical in underpass over a certain size. CONCLUSIONS : The result of this study are expected to be able to contribute to reviewing for feasibility due to the small vehicles underpass introduction and economic analysis. The study is case study to the underpass in Daegu. Therefore, the future requires the calculation of benefits reflect a wider range of traffic conditions and the economic analysis to construction cost calculation for various types of grad separation facilities.

• Journal of KIBIM
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• v.5 no.1
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• pp.8-15
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• 2015

With the emergence of environment-friendly paradigms, many countries around the world have enacted various laws to take care of environmental pollution-related problems. The goal of these environmental laws and regulations was to properly respond to rapid environmental pollution. Because of the simultaneous enactment of these laws on diverse pollution sources, however, a variety of problems, including an unclear correlation among these laws, have occurred. As a result, workers have found it hard to collect and use the related laws and regulations. Therefore, this study proposes a metadata-based information retrieval method for the efficient search of environment-friendly laws and regulations. The laws and regulations were structured using metadata from users, business stage, topic and department. These were obtained through semantic analysis on environment-friendly laws and regulations, and then an intelligent retrieval approach was utilized. To verify the retrieval plan, a test case was conducted, and improvement in retrieval accuracy against the conventional system was confirmed. It appears that the proposed plan will improve productivity in the construction industry by improving accuracy in retrieving environment-friendly laws and regulations.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.472-481
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• 2006

In the conventional SRM with multi-rotor teeth, the air gap must be very small in order to drive the SRM in the saturation region that is necessary for high output torque. However, this leads to the problem of overheating; particularly in the case of a small-size SRM This paper discusses the design of a new type of SRM, namely the rolled rotor SRM. This new type does not require more than a single region of a very small airgap. This solves the overheating problem in the small size SRM. Moreover, the use of the rolled rotor, instead of the conventional toothed rotor, grades the airgap region in a fashion that gives a smooth variation in the reluctance and smooth shapes of both current and torque. The latter functional behavior is required in many applications such as servo applications. The paper first addresses general design steps of the rolled rotor SRM then proceeds to the simulation results of the new SRM in order to evaluate the advantages gained from the new design. In addition, this paper compares the torque ripples obtained from the new design to its equivalent conventional one.