• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.1
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• pp.42-51
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• 2007

An AC electrical railroad system has rapidly changing dynamic single-phase load, and at a feeding substation, three-phase electric power is transformed to the paired directional single-phase electric power. There is a great difference in electrical phenomenon between the load of AC electrical railroad system and that of general power system. Electric characteristics of AC electrical railroad's trainload are changed continuously according to the traction, operating characteristic, operating schedule, track slope, etc. Because of the long feeding distance of the dynamic trainload, power quality problems such as voltage drop, voltage imbalance and harmonic distortion my also occur to AC electrical railroad system. These problems affect not only power system stability, but also power quality deterioration in AC electrical railroad system. The dynamic simulation model of AC electrical railroad system presented by PSCAD/EMTDC is modeled in this paper, andthen, it is analyzed voltage drop for AC electrical railroad system both with single-phase distributed STATCOM(Static Synchronous Compensator) installed at SP(Sectioning Post) and without.

• Korean Journal of Cleft Lip And Palate
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• v.4 no.1
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• pp.1-11
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• 2001

Disposable blade is widely used for palatal and oral mucosal incision in oral and maxillofadal surgery nowadays, But its design and durability need for improvement, Especially, there are so many hard tissues intraoral area, such as bone and tooth, therefor the sharpness of the surgical blade was easily destroyed, The purpose of this study was to make basic data for developing new design of surgical blade using in oral and maxillofacial area including for the patients who have cleft lip and palate deformities, Some questionnaires about the usefulness of currently used surgical blades were sent to 150 dentists, the 54 of them made a reply, Secondly, The used-once blade and fresh new blade were examined under the scanning electron microscope with the 4000-times magnification, Lastly, the tissue reaction following the surgical incision with a fresh-new and a used blade on rat buccal cheek mucosa and hard palate was evaluated with light microscope with hematoxilin-eosin staining, The time interval from the surgical trauma to taking a sample were 1 day, 3 days, 7 days, and 14 days, At each time schedule, 2 Sprague-Dawley rats were sacrificed, Many dentists were agreed to need for changing the design of the surgical blades and also demand to improve the durability of the blades, They were also eager to adopt the new design of blade if it was available, The blade used in surgical extraction procedure was heavily damaged in its sharpe edge of number 15 blade, The histological differences were not prominent, but the delayed healing was detected in buccal mucosal defects especially in the surgical group with used blade, There are slight different changes in hard palatal defects between a used and a new blade group, In this study, we could find that there are imperative demanding on improvement of surgical blade design and durability for oral and maxillofadal area, The blade currently using in surgical extraction was easily damaged, The animal model of this study was not perfect for the purpose of this study.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.8
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• pp.157-163
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• 2016

BIM is currently applied in some domestic construction firms, but it is not being actively utilized due to changes in working environments and qualms about new studies. In order to utilize a BIM model in the design phase, process information is needed during construction, but the input system and utilization method of the process information's state are not complete. Therefore, we propose a BIM template for construction progress management that can show basic BIM information as the construction progresses in an easy and convenient way. This method will facilitate the adoption of BIM and enhance the productivity of construction companies. To this end, we designed a progress explorer for step-by-step progress and work schedules, and we generated three-dimensional views and a progress list by applying unit information (primary units, part units, and detail units) of the work breakdown structure (WBS) to the parameters. To use the BIM template, work progress information is input to the BIM modeling objects through Dynamo. We also used Dynamo for quick and easy calculation of the quantity of materials needed for construction work. To test the BIM template, we applied it to an actual project and evaluated its visibility and a progress list. The results showed that the proposed BIM template facilitates progress management of a project and can thus facilitate the adoption of BIM and improve the productivity of construction companies.

• Science of Emotion and Sensibility
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• v.21 no.1
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• pp.165-176
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• 2018

A demand for user's participation in the designing process, which is called the participation design, is increasing with social change. Practically, however, there is lack of researches on the improvement of the problem in actual design development and participation design effect. In order to understand the field-based participation design effect in view of user's change of awareness on participation design, this study carried out a survey on the change of awareness through a design workshop in which all stakeholders have participated on the subject of agricultural direct sales facilities as a part of participation design programs. Many references were reviewed first to understand the participation design principles and their current research trend. Next, the questionnaire was developed using an effectiveness verification model for an effective analysis. A design workshop as one of the participation design programs was organized and applied for the field response. In order to analyze the effect, the survey on participants' change of awareness was carried out before and after the program. The survey questionnaires were about motivation, knowledge, recognition, function, and participation and asked the design study graduates. The participation design effect was supplemented by additional open questions. As a consequence, the participants in the participation design program showed the noticeable effect in knowledge and function about the agricultural direct sales facilities. It was found that they were also highly satisfied with the participation design result and they recognized an importance of collaboration. This study also showed that a sufficient time schedule considering agricultural village life should be given for a smooth operation of the program and also a working environment is necessary for designing work.

• Nuclear Engineering and Technology
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• v.27 no.1
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• pp.8-17
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• 1995

A great effort has been made to improve the nuclear plant control system by use of digital technologies, and a long term schedule for the control system upgrade has been prepared with an aim to implementation in the next generation nuclear plane. In case of digital control system, it is important to decide the sampling period for analysis and design of the system, because the performance and the stability of a digital control system depend on the value of the sampling period of the digital control system. There is, however, currently no systematic method used universally for determining the sampling period of the digital control system. Generally, a traditional way to select the sampling frequency is to use 20 to 30 times the bandwidth of the analog control system which has the same system configuration and parameters as the digital one. In this paper, a new method to select the sampling period is suggested which takes into account of the performance as well as the stability of the digital control system. By use of the frying's model of steam generator, the optimal sampling period of an assumptive digital control system for steam generator level control is estimated and is actually verified in the digital control simulation system for KORI-2 nuclear power plant steam generator level control. Consequently, we conclude the optimal sampling period of the digital control system for KORI-2 nuclear power plant steam generator level control is 1 second for all power ranges.

• Korean Chemical Engineering Research
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• v.44 no.2
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• pp.149-159
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• 2006

This research is a development of useful S/W program for real industry about optimal product scheduling in real plant for manufacturing polymer products. For this, we used a fine model with total amount of losses in weight(ton) as an objective for optimal scheduling and a genetic algorithm for optimization in this factory they manufacture three different products. Major products are A and B but the product which can be process in the period of products change over. They also sells them as a chap product in market. The major products have several types of packing process-bulk, pack for domestic market, pack for export. The demands of product with each packing type are increased, and frequently they failed keep the deadline for sail. Based on realistic production situation, we composed a fine modeling for optimal scheduling. And we also develop a S/W program for optimal scheduling which can be used by non-specialist in scheduling problem. We used a modified genetic algorithm and it gave us a better solution in process. We can have a result of reducing the total amount of losses in weight by half compared with the losses when existing production schedule.

• Journal of Digital Convergence
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• v.9 no.2
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• pp.111-129
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• 2011

Nowadays, the IS project is getting more and more complicated and large-scaled. Many researchers and practitioners are interested in the IS development methodologies, automated tools and techniques to decrease project failure and to increase IS project performance. This research is to seize the management level of PMO affecting on the IS project, as a new method to increase the IS project development performance. As a result of surveying the present PMO operation state with banks which are the leading industry to accept the PMO in Korea, technology support management and infrastructure management are the core functions to affect the IS performance including schedule management, quality management, and user and stakeholders' satisfaction. Also, the PMO management level is the important point of IS project success. Among the 5 levels PMI suggested, PMO can implement the project effectively at least at the third level. Korean companies introducing the PMO have to do research the PMO core functions and the management levels according to the project scale, and review the distinctive features of their organization to increase the maturity of IS project. This research has been proved through the Full Structural Equation Model. The results show that the five core functions of PMO have relationship with the IS project performance.

• Journal of Korea Water Resources Association
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• v.40 no.11
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• pp.861-867
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• 2007

This Research analyzes the consumers' willingness to pay(WTP) for residential water on severe drought condition. The 7 large cities and 32 chronicle drought regions have been selected for this research survey. Results show that the consumers of large cities, which are relatively rich, think water quality is more important than quantity, but the consumers of 32 chronicle drought regions expressed just opposite. Dichotomous choice and open-ended questionnaire are mixed for the survey and Tobit model is applied in the analysis. As we expected, the higher the education level, the number of household member, and the income, the higher the WTP. When there is 25% reduction of supply, the WTP is about $2 per month. Contrary to the expectation, WTP is just slightly increased for 50% of water supply reduction. This is because of the resistance of tax as well as the limited actual experiences of water shortage so, they underestimated it. In any cases, actual WTP for actual water shortage is much higher than this result. More effective water supply and distribution schedule must be ready as a national and local level to prepare severe drought in the near future. Consumers are willing to pay higher price than the current level for water security. Water distributional system should be reconsidered and alternative source of water also be prepared.

• Journal of Intelligence and Information Systems
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• v.8 no.2
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• pp.205-227
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• 2002

Our study is focused on a multiple-agent system to provide efficient collaborative work by automating the conference calling process with the help of intelligent agents. Automating the meeting scheduling requires a careful consideration of the individual official schedule as well as the privacy and personal preferences. Therefore, the automation of conference calling needs the distributed processing task where a separate calendar management process is associated for increasing the reliability and inherent parallelism. This paper describes in detail the design and implementation issues of a multiple-agent system for conference calling that allows the convener and participants to minimize their efforts in creating a meeting. Our system is based on the client-sewer model. In the sewer side, a scheduling agent, a negotiating agent, a personal information managing agent, a group information managing agent, a session managing agent, and a coordinating agent are operating. In the client side, an interface agent, a media agent, and a collaborating agent are operating. Agents use a standardized knowledge manipulation language to communicate amongst themselves. Communicating through a standardized knowledge manipulation language allows the system to overcome heterogeneity which is one of the most important problems in communication among agents for distributed collaborative computing. The agents of our system propose the dates on which as many participants as possible are available to attend the conference using the forward chaining algorithm and the back propagation network algorithm.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.11
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• pp.846-850
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• 2009

Recently, wireless sensor networks have found their way into a wide variety of applications and systems with vastly varying requirements and characteristics such as environmental monitoring, smart spaces, medical applications, and precision agriculture. The sensor nodes are battery powered. Therefore, the energy is the most precious resource of a wireless sensor network since periodically replacing the battery of the nodes in large scale deployments is infeasible. Energy efficient mechanisms for gathering sensor readings are indispensable to prolong the lifetime of a sensor network as long as possible. There are two energy-efficient approaches to prolong the network lifetime in sensor networks. One is the compression scheme to reduce the size of sensor readings. When the communication conflict is occurred between two sensor nodes, the sender must try to retransmit its reading. The other is the MAC protocol to prevent the communication conflict. In this paper, we propose a novel approaches to reduce the size of the sensor readings in the MAC layer. The proposed scheme compresses sensor readings by allocating the time slots of the TDMA schedule to them dynamically. We also present a mathematical model to predict latency from collecting the sensor readings as the compression ratio is changed. In the simulation result, our proposed scheme reduces the communication cost by about 52% over the existing scheme.