• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.587-599
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• 2018

In building-integrated photovoltaic (BIPV) systems, power generation functions are integrated into building functions by installing solar modules in combination with building materials. While this integration appears to be attractive, a design method is needed to achieve maximum power generation. Previously, the influence of the design elements on power generation was analyzed by computer simulations and demonstration tools. On the other hand, problems remain due to the inaccuracy of power generation analysis and relationship analysis, and limited demonstration. To solve this problem, this paper proposed the use of an extended demonstration mock-up. The mock-up was designed and constructed by implementing the design elements of the module types, installation angles, and direction. The actual operation data for one year were analyzed to evaluate the effects of the design elements on power generation. These results can be used to determine the feasibility of future BIPV systems and the optimal selection of system design elements.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.12
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• pp.762-767
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• 2017

This paper presents an analysis for improving the power transfer capability in transmission lines caused by the movable load charging of electric vehicles (EVs). EVs are expected to be used more widely and replace gas fuel vehicles in the near future due to the shortage of fossil fuels and for environmental preservation. Movable load charging of EVs could lead to the convergence of transferred power flow and overloading conditions in transmission lines in a specific area of a power system, which is conventionally based on estimated fixed load capability. To analyze these conditions, the New England Test System was divided into four regions based on the load characteristics, and different charging scenarios were considered. In these scenarios, the regional power load was highly increased to 31% based on the standard charging capacity of an EV. As a solution to the overloading problem of transmission lines, a TCSC was installed serially on the overloaded line to directly control the transferred power under limited line capability (100% load capability). The simulation showed that the application of a few TCSCs could efficiently and economically control the line capability problem caused by movable load charging of EVs.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.4
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• pp.39-48
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• 2020

Since the fire accident of ESS (energy storage system) occurred at Gochang KEPCO Power Testing Center in August 2017, 29 fire cases with significant property losses have occurred in Korea. Although the cause of fire accidents have not been identified precisely, it should be considered battery and PCS (power conditioning system) as well as unbalance issues in the distribution system. In particular, circulating currents in a neutral line of a grid-connected transformer, which can affect a magnetized current, may have a negative effect on the ESS with unintentional core saturation and surge voltages at the secondary side of the transformer. Therefore, this paper proposes the modeling of the distribution system, which was composed of a substation, grid-connected transformer, and customer loads using PSCAD/EMTDC S/W, to analyze the phenomena of circulating current and surge voltages of the transformer with unbalanced currents in the distribution system. This paper presents a countermeasure for a circulating current with the installation of NGR (neutral grounding resistor) in grid-connected transformer. From the simulation results, it is clear that exceeding the circulating current and surge voltage at the secondary side of the transformer can be one of the causes of fire accidents.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.4
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• pp.333-340
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• 2011

KJJVC(Korea-Japan Joint VLBI Correlator) was installed at the KJCC(Korea-Japan Correlation Center) and has been operated by KASI(Korea Astronomy and Space Science Institute) from 2009. KJNC is able to correlate the VLBI observed data through KVN(Korean VLBI Network), VERA(VLBI Exploration of Radio Astrometry), and JVN(Japanese VLBI Network) and its joint network array. And it is used exclusively as computer in order to process the observed data for the scientific purpose KJJVC used the VSI(VLBI Standard Interface) as the VLBI international standard at the data input-output specification between each component. Especially, for correlating the observed data, the data is transmitted with 1024Mbps speed between Mark5B high-speed playback and RVDB(Raw VLBI Data Buffer). The EMI(Electromagnetic lnterference), which is occurred by data transmission with high-speed, cause the data loss and the loss occurrence is frequently often for long transmission cable. Finally it will be caused the data recognition error by decreasing the voltage level of digital data signal. In this paper, in order to minimize the data loss by measuring the EMI noise level in transmission of the VSI specification, the 3 methods such as 1) RC filtering method, 2) lmpedance matching using Microstrip line, and 3) Signal buffering method using Differential line driver, were proposed. To verify the effectiveness of each proposed method, the performance evaluation was conducted by implementing and simulations for each method. Each proposed method was effectively confirmed as the high-speed data transmission of the VSI specification.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.269-281
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• 2018

Unlike its archetype predecessor such as the Highway Capacity Manual of the United States, the Korean Highway Capacity Manual of 2013 provides the analytical models for estimating the saturation flow rates for the lane-occupying work-zones in the proximity of the signalized intersections. Direct application of the revised saturation flow rates into the classic control delay models, however, appears to produce unreasonable delay amount as traffic demand approaches lane-group capacities and surpasses them, which is common phenomena in the work-zones. Complex interaction among vehicles, lane-dropping work-zone geometry and signal operations were never accounted in the traditional control delay models, and considerable differences between the delay model outcomes and field observations are repeatedly experienced. This paper proposes the modified approaches to the delay models in the manual, exerted on all three elements of control delay, and particularly focuses on the temporal and spatial boundary expansion in comparing the simulated results to the estimated ones. Extensive microscopic simulation work and calibration effort supports the modified approaches well enough to use them in the work-zone planning and evaluation.

• Journal of the Korean Society for Marine Environment & Energy
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• v.5 no.3
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• pp.28-34
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• 2002

As the technology of Speech Recognition(SR) and Text-To-Speech(TTS) develops rapidly, voice control and guidance system is thought to be very helpful for safe navigation. But Voice Control and Guidance System(VCGS) is not yet so popularly included in Navigation Supporting System(NSS). The main reason of this is that VCGS is so complicated and user-unfriendly that navigation officers hesitate to use VCGS. Frequent errors in operating VCGS due to low rate of SR are another reason. To make VCGS more practicable for safe navigation, we design the user-friendly VCGS. Firstly, by using interviews we survey functions and procedures that navigation officers want to be included in VCGS. Secondly, to raise the rate of SR, we tun the environmental noise in bridge and to reduce the errors due to low rate of SR in operating VCGS, we design the functions of self-correction. Also we apply a user-independent SR engine so that procedures of teaming of speakers is basically not necessary. Using simulator experiments the functions and procedures of the user-friendly YCGS for safe navigation are evaluated and the results of evaluation are fed back to the design. As a result, we can design the VCGS more helpful for safe navigation. In this paper, we describe the features of the user-friendly VCGS for safe navigation and discuss the results of simulator experiments.

• Fire Science and Engineering
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• v.28 no.6
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• pp.52-57
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• 2014

The present study suggests the fundamental method for the prediction time of the fire origin by analyzing the combustion phenomenon of inflammable material in the building structure. The heat release rate (HRR) with time variant is evaluated for the interphone as a inflammable material, which is opted from the fire incidents in the stairwell. the fire dynamics simulator (FDS ver. 6.1) is applied in order to analyze the difference of the smoke inflow time to the downstair from the fire event area with various fire pattern. The results show that the maximum inflow time difference for the case of the interphone made from ABS materials is about 4.93 times with the input conditions of heat flux values and the environment in the FDS for the fixed stairwell which composed of total volume $291.3m^3$, floorage $23.3m^2$ and the height of each floor 2.5 m. This research can be practical information for the application method of simulation scheme with experimental data to the fire Identification.

• Journal of the Society of Naval Architects of Korea
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• v.33 no.4
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• pp.1-14
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• 1996

Especially in the case of a full form ship, the stability on course can be considered to become severest among 4 items of criteria in Interim Standards for Ship Maneuverability adopted by IMO in 1993. The purpose of this study is to find some ideas for the improvement of stability on course through changes in rudder area with reference to span distance. In this paper, we established the formula on the relation between the experimental constants relevant to rudder normal force and hydrodynamic derivatives of hull-propeller-rudder system. We carried out various kinds of captive model test relevant to rudder normal force etc., and evaluated hydrodynamic derivatives of hull-propeller-rudder system, and analyzed the stability on course with the parameter of changes in rudder area. Furthermore, we also discussed effects of changes in rudder area on maneuvering performance including stability on course, based on computer simulation. As a result, it is clarified that there is a possibility that stability on course may become bad through an increase of rudder area. The reason for the bad stability on course is that the void space between the upper edge of rudder and the lower part of stern overhang decreases. This space change exerts a great influence on straightening coefficient of incoming flow to rudder in maneuvering motion, which has close relation to stability on course.

• KEPCO Journal on Electric Power and Energy
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• v.6 no.2
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• pp.145-150
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• 2020

Water wall tube is one of the major factors consisting of a fluidized bed boiler and it plays very important role for the generation of electricity within the boiler. But these water wall tubes within the fluidized bed boiler are subject to the ware and corrosion caused by the high temperature gas and the flowing medium. If water leak is occurred, the secondary damage by the water leak will occur. As a result of that, the power generation efficiency decreases noticeably. Therefore, the maintenance of the water wall tube is very important. In this study, we designed a exciter sensor based on simulation and composed a remote field eddy current system for the defect evaluation of the outer water wall tube. Starting from the shape design of exciter, we conducted simulations for various design factors such as the water wall tube size, material, frequency, lift-off and so on. Based on the results, we designed the optimum exciter sensor for the water wall tube test within the fluidized bed boiler.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.19 no.5
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• pp.162-177
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• 2020

The perception of traffic environment based on various sensors in autonomous driving system has a direct relationship with driving safety. Recently, as the perception model based on deep neural network is used due to the development of machine learning/in-depth neural network technology, a the perception model training and high quality of a training dataset are required. However, there are several realistic difficulties to collect data on all situations that may occur in self-driving. The performance of the perception model may be deteriorated due to the difference between the overseas and domestic traffic environments, and data on bad weather where the sensors can not operate normally can not guarantee the qualitative part. Therefore, it is necessary to build a virtual road environment in the simulator rather than the actual road to collect the traning data. In this paper, a training dataset collection process is suggested by diversifying the weather, illumination, sensor position, type and counts of vehicles in the simulator environment that simulates the domestic road situation according to the domestic situation. In order to achieve better performance, the authors changed the domain of image to be closer to due diligence and diversified. And the performance evaluation was conducted on the test data collected in the actual road environment, and the performance was similar to that of the model learned only by the actual environmental data.