• Proceedings of the KAIS Fall Conference
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• 2012.05b
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• pp.512-516
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• 2012

Recently the Korean government's green energy growth policy has been taken at the national level due to the sufficient supply of renewable energy. Some specific technique should be taken in consideration for the operation of the grid voltage and power quality management. In this case, there may have some chance of operational problems. Typical problems arise when grid-connected solar power produced by Pacific sunshine. The power flow in the reverse direction can create overvoltage on the distribution line and gives value of malfunction on the system. Line voltage and overvoltage adjustment practice can stop these symptoms occurred. Under these circumstances, this paper presents an interconnection test devices for photovoltaic(PV) systems composed of distribution system simulator, PV system simulator and control and monitoring systems using the LabVIEW S/W, and simulates the customer voltage characteristics considering the 3 parameters on the introduction capacity for PV systems, system configuration and Power factor. This paper also proposes a new calculation algorithm for voltage profile to make comparison between calculation values and test device values. The results show that the simulation results for the normal operation characteristics of PV systems which are very practical and effective.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.11
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• pp.1-9
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• 1999

As our society turns into the information age from the industrial one, the ministry of information and communication has set up functional software standards for electronic approval systems Several software houses have developed such systems in the client/server environment and subsequently for the intranet. Although electronic approval systems for the intranet have the advantages of less costly implementation and ease of use, they create heavy network traffic, and have a poor document processing functionality resulting from the lack of document processor in web environments. This paper describes a system design that web browsers utilize the resources of clients by adopting the ActiveX technique in order to improve such mallets mentions above. In other words, to use the Hangul word processor as a document processor, the ActiveX control and the Hangul DDE API have been implemented in the form of the DDE server/client, which is capable of mutual communication, and the flow of electronic approve system has been controled by connecting. As a result of running the implemented system lot three months through a real company in multi-server environment, it shows the high usage of electronic approval system as the tate roaches 75%-93% for some departments.

• Journal of Astronomy and Space Sciences
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• v.29 no.2
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• pp.221-232
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• 2012

We analyzed the manufacturing procedure, specifications, repair history, and details of celestial movements of the water-hammering type $Honsang$ (celestial globe). Results from our study on the remaining $Honsangs$ in China and Japan and on the reconstruction models in Korea were applied to our conceptual design of the water-hammering type $Honsang$. A $Honui$ (armillary sphere) and $Honsang$ using the water-hammering method were manufactured in $Joseon$ in 1435 (the 17th year of King $Sejong$). $Jang$ $Yeong-Sil$ developed the $Honsang$ system based on the water-operation method of $Shui$ $y{\ddot{u}}n$ $i$ $hsiang$ $t'ai$ in China. Water-operation means driving water wheels using a water flow. The most important factor in this type of operation is the precision of the water clock and the control of the water wheel movement. The water-hammering type $Honsang$ in $Joseon$ probably adopted the $Cheonhyeong$ (天衡; oriental escapement device) system of $Shui$ $y{\ddot{u}}n$ $i$ $hsiang$ $t'ai$ in China and the overflow mechanism of $Jagyeongnu$ (striking clepsydra) in $Joseon$, etc. In addition to the $Cheonryun$ system, more gear instruments were needed to stage the rotation of the $Honsang$ globe and the sun's movement. In this study, the water-hammering mechanism is analyzed in the structure of a water clock, a water wheel, the $Cheonhyeong$ system, and the $Giryun$ system, as an organically working operation mechanism. We expect that this study will serve as an essential basis for studies on $Heumgyeonggaknu$, the water-operating astronomical clock, and other astronomical clocks in the middle and latter parts of the $Joseon$ dynasty.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.5
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• pp.297-304
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• 2009

The aim of this study is to investigate the cooling performance of ground source multi-heat pump systems with a vertical single U-tube GLHX(U-tube system) and a vertical double tube GLHX(double tube system), which were installed in a school building located in Cheonan. All systems were operated in a part load conditions for all day, and the maximum COP of the single U-tube system and the double tube system were 6.2 and 5.2 at cooling mode, respectively. The double tube GLHX designed by the GLHEPRO, commercial program, was estimated to have the same performance as the U-tube GLHX, because the inlet temperatures of each outdoor unit heat exchanger for the former was similar to the latter. However, it is needed to prove the long tenn performance. It is suggested that the new algorithms to control the flow rate of secondary fluid for GLHX according to load variation have to be developed in order to enhance the performance of the system.

• Journal of Information Processing Systems
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• v.8 no.2
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• pp.213-240
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• 2012

Safety critical systems, real time systems, and event-based systems have a complex set of events and their own interdependency, which makes them difficult to test ma Safety critic Safety critical systems, real time systems, and event-based systems have a complex set of events and their own interdependency, which makes them difficult to test manually. In order to cut down on costs, save time, and increase reliability, the model based testing approach is the best solution. Such an approach does not require applications or codes prior to generating test cases, so it leads to the early detection of faults, which helps in reducing the development time. Several model-based testing approaches have used different UML models but very few works have been reported to show the generation of test cases that use events. Test cases that use events are an apt choice for these types of systems. However, these works have considered events that happen at a user interface level in a system while other events that happen in a system are not considered. Such works have limited applications in testing the GUI of a system. In this paper, a novel model-based testing approach is presented using business events, state events, and control events that have been captured directly from requirement specifications. The proposed approach documents events in event templates and then builds an event-flow model and a fault model for a system. Test coverage criterion and an algorithm are designed using these models to generate event sequence based test scenarios and test cases. Unlike other event based approaches, our approach is able to detect the proposed faults in a system. A prototype tool is developed to automate and evaluate the applicability of the entire process. Results have shown that the proposed approach and supportive tool is able to successfully derive test scenarios and test cases from the requirement specifications of safety critical systems, real time systems, and event based systems.

• Journal of the Korean Institute of Gas
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• v.16 no.3
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• pp.48-53
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• 2012

The purpose of this paper studies the failure cases including with system of liquefied phase injection in liquified petroleum gas vehicle. The first case, resulting with inspection the injector of LPG, it occasionally certified the injection damage phenomenon that the fuel efficiency(km/l) was decreased to 5% by carbon deposit with injector hole when the driver operates the vehicle. The second case, it certified the interference phenomenon of air flow with carbon deposit in ISA system control for idle speed of engine and throttle body suppling air into engine. As a result, the fuel efficiency was decreased 7%. The third case, the outer air during intake stroke was intermittently flowed in this gasket gap because of weaken adhesion power phenomenon for cylinder block by intake manifold gasket tearing. Consequentially, it certified the decrease for fuel efficiency to 3% by risen the amount of fuel injection as the air inflow quantity. These failure examples reduced the power performance of engine and the fuel efficiency of vehicle. It have to minimize of failure phenomenon preparing through quality management.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.277.1-277.1
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• 2013

Molecular diagnostics consists of three processes, which are a sample pretreatment, a nucleic acid amplification, and an amplicon detection. Among three components, sample pretreatment is an important process in that it can increase the limit of detection by purifying nucleic acid in biological sample from contaminants that may interfere with the downstream genetic analysis such as nucleic acid amplification and detection. To achieve point-of-care virus detection system, the sample pretreatment process needs to be simple, rapid, and automatic. However, the commercial RNA extraction kits such as Rneasy (Qiagen) or MagnaPure (Roche) kit are highly labor-intensive and time-consuming due to numerous manual steps, and so it is not adequate for the on-site sample preparation. Herein, we have developed a rotary microfluidic system to extract and purify the RNA without necessity of external mechanical syringe pumps to allow flow control using microfluidic technology. We designed three reservoirs for sample, washing buffer, and elution buffer which were connected with different dimensional microfluidic channels. By controlling RPM, we could dispense a RNA sample solution, a washing buffer, and an elution buffer successively, so that the RNA was captured in the sol-gel solid phase, purified, and eluted in the downstream. Such a novel rotary sample preparation system eliminates some complicated hardwares and human intervention providing the opportunity to construct a fully integrated genetic analysis microsystem.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.25 no.3
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• pp.197-204
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• 1992

A comparative evaluation of water quality in the existing semiclosed fish culture system was made to improve the system management. From the comparison of water quality between the flow-through mode and the recycle mode of the semiclosed system, the malfunctioning of the settling channel deteriorated water quality and reduce the nitrification rate in the recycle mode. The peak concentrations of COD, $PO_4-P$ and SS in the fish tanks appeared just after feeding, and then decreased to normal levels within two hours. However, the $NH_4-N$ concentration increased slightly after two hours of feeding in the recycle mode. The water exchange rate was directly related to the water quality in the semiclosed fish culture system.

• Journal of Korea Society of Industrial Information Systems
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• v.15 no.5
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• pp.221-233
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• 2010

For the education information system, evaluation of the performance have to incorporate the special characteristics od education. This paper is to develop some measures to assess the performance of Korean National Education Information System (NEIS). Performance measures are classified those into three detailed areas as the flow of value chain. which include end-users area, education process area and performance area. Research results show that the users's concern to the information system have an affirmative influence on the satisfaction of users, and attitude change of users have also a positive influence on the administration area of the information system such as task productivity, task innovation, satisfaction of the education users, activity of control process. Also, user's satisfaction for NEIS, that comes from the communication, have an affirmative influence on the better performance of education,

• Transactions of the Korean hydrogen and new energy society
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• v.35 no.3
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• pp.345-351
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• 2024

The unitized regenerative fuel cell (URFC) is a method that can reduce costs and increase system simplification by unitizing a fuel cell system and a water electrolysis system. The spray method is suitable as the membrane electrode assembly (MEA) manufacturing method for URFC because it is easy to control the amount of catalyst, the size of the system is small, and economical manufacturing is possible. In this study, a numerical analysis of the effect of solution concentration on the spray method was performed to use it as basic data for the spray method to be used in MEA manufacturing. As result, as the Nafion solution concentration decreases it was found that the spray speed and the mass flow rate and the discrete phase model concentration increases and the spray range widens.