• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.14 no.4
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• pp.23-30
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• 2000

Cogeneration systems are seen as a significant innovation for dispersed energy generation since they are both environmentally friendly and has comparatively high degrees of efficiency. It is especially suited for the decentralized provision of electricity and heat. However, it causes operational problems such as voltage regulation, voltage variation, protection and safety. Especially, it is expected that the interconnection/disconnection operation of cogeneration system has an effect on distribution voltage regulation and variation. Recently, with the increased use of customer-owned computers and other sensitive electronic equipment, electric power quality has become an important concerns. Therefore, the voltage quality problems with cogeneration system should be investigated because the voltage quality is an important part of electrical power quality. In this paper, the momentary voltage dips associated with the interconnection/disconnection operation of cogeneration system are analyzed, including restraint solutions at the customer level. In addition, the unit capacity of cogeneration systems per feeder are evaluated from the view point of momentary voltage variations. The results of this paper are useful analysis data for interconnection standards/guidelines of cogeneration systems and dispersed generation (DG)

• Journal of the Korea Institute of Military Science and Technology
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• v.23 no.3
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• pp.302-309
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• 2020

Early-detection and monitoring of toxic chemical gas cloud with chemical detector is essential for reducing the number of casualties. Conventional method for chemical detection and reconnaissance has the limitation in approaching to chemically contaminated site and prompt understanding for the situation. Stand-off detector can detect and identify the chemical gas at a long distance but it cannot know exact distance and position. Chemical detection UAV is an emerging platform for its high mobility and operation safety. In this study, we have conducted chemical gas cloud detection with the stand-off chemical detector and the chemical detection UAV. DMMP vapor was generated in the area where the cloud can be detected through the field of view(FOV) of stand-off chemical detector. Monitoring the vapor cloud with standoff detector, the chemical detection UAV moved back and forth at the area DMMP vapor being generated to detect the chemical contamination. The hybrid detection system with standoff cloud detection and point detection by chemical sensors with UAV seems to be very efficient as a new concept of chemical detection.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.38 no.5
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• pp.415-423
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• 2020

GNSS (Global Navigation Satellite System) is mostly used for high-precise surveys due to its accuracy and efficiency. But this technique does not always fulfill the demanding accuracy in harsh operational environments such as urban canyon and forest. One of the remedies for overcoming this barrier is to compose a heterogeneous surveying network by adopting terrestrial measurements (i.e., distances and angles). Hence, this study dealt with the adjustment of heterogeneous surveying networks consisted of GNSS baseline vectors, distances, horizontal and vertical angles with a view to enhancing their accuracy and so as to derive an appropriate scheme of the measurement combination. Reviewing some technical issues of the network adjustments, the simulation, and experimental studies have been carried out, showing that the inclusion of the terrestrial measurements in the GNSS standalone overall increased the accuracy of the adjusted coordinates. Especially, if the distances, the horizontal angles, or both of them were simultaneously adjusted with GNSS baselines, the accuracy of the GNSS horizontal component was improved. Comparing the inclusion of the horizontal angles with those of the distances, the former has been more influential on accuracy than the latter even though the same number of measurements were employed in the network. On the other hand, results of the GNSS network adjustment together with the vertical angles demonstrated the enhancement of the vertical accuracy. As conclusion, this paper proposes a simultaneous adjustment of GNSS baselines and the terrestrial measurements for an effective scheme that overcomes the limitation of GNSS control surveys.

• Korean Institute of Interior Design Journal
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• v.24 no.5
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• pp.144-152
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• 2015

In modern city, art museum is regarded as significant institutions because it includes educational roles beyond the means of facilities for historical exhibitions. Based on these flow, various research of museum's space with view from the operational point to the spatial analysis point has been approached. Moreover, it is required to address human behavior in art museum space on the ground that lots of audience move simultaneously. In the field of interior architecture, it is also necessary to analyze how design elements affect the human behavior directly and use the method of controling a circulation. In this research, based on the role and importance of the basic components of the interior space, re-interprets the exhibition space based on the relevant theory, to comprehensively examine the influence the shape of the space is on the substantially walking behavior. Therefore, first is to determine whether the spatial type corresponding to the position of the connectors in the exhibition space. Second is to conduct the investigation observation for gathering the actual viewing exhibition circulation. Finally, it analyzed whether the observed actual circulation and planned circulation matched. As the result, the position of the connectors is that causes the difference of the spatial configuration, which affects the viewing circulation was found. The significance of the research is to present the form to plans of the interior space as a method of reducing congestion perception of viewing circulation.

• Journal of Korea Technology Innovation Society
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• v.12 no.1
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• pp.36-69
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• 2009

This work aims to firstly know what does the inside and outside participants perceive the system itself and its execution in the evaluation of the research institutes in science and technology sector which has been introduced in 1999, and to secondly discuss how can diverse perceptions among participants be integrated in the institutional and operational aspects. This has been conducted mainly by in-depth interviews with 99 staffs from 10 research institutes under the Korea Research Council for Public Technology as well as with 10 members of evaluation committee for research institutes. According to the in-depth interviews, the both inside and outside participants perceive that the evaluation of research institutes can be necessary and useful for the management of the institute itself and R&D programs in view of the strategic reasons as well as practical one. Despite of the affirmative perceptions to the evaluation of research institute, based on the common or individual experiences, they have also suggested that there will be lots of improvements in the individual components of evaluation system and its current status of execution.

• Journal of the Korean Society of Safety
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• v.26 no.4
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• pp.41-46
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• 2011

The purpose of this paper is to analyze the causes of accidents related to the 3 phase 170 kV gas insulated switchgear of a power system collected from accident sites to secure data for the prevention of similar accidents and provide important points of view regarding diagnosis for the prevention of accidents involving gas insulated switchgears. The analysis results of the causes of accidents involving gas insulated switchgears showed deformation of the manipulation lever installed at the S-phase, disconnection of the insulation rod connection, melting of the upper conductor, a damaged tulip, damage to the lower spacer and the spacer at the breaker, etc. It is believed from this result that the potential for accidents has expanded due to accumulated energy as a result of repeated deterioration. The carbonization depth of a GIS was formed near the screw (T2, T3) used to secure the lower pole of the S-phase tulip. It is not known what has caused the screws to be extruded and melted. However, it is thought that an unbalanced electromagnetic force, micro-discharge, surface discharge, etc., have occurred at that point. In addition, even though 16 years have passed since its installation, there was no installation defect, act of arson, accidental fire, etc. General periodical inspection and diagnosis failed to find the factors causing the accidents. As a system contained in a closed metal container, it has a high risk factor. Therefore, it is necessary to design, install and operate a GIS in accordance with the standard operational procedure (SOP). In addition, it is necessary to apply conversion technology for periodical SF6 gas analysis and precision safety diagnosis. It is expected that tracking and managing these changes in characteristics by recording the results on the history card will provide a significant accident prevention effect.

• Journal of Navigation and Port Research
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• v.41 no.5
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• pp.353-358
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• 2017

This study aims to propose an assessment tool of port service quality (PSQ) in the context of container transport logistics (CTLs), by taking the perspectives from port users. The CTLs defined in this study are the relevant activities of serving the physical flows of a container box from a point of origin via a container port to a point of destination. To address the ports' role in collaboration between its channel members in CTLs, the PSQ measures for all port user groups (i.e. common PSQ measures) are selected based on the relevant CTLs activities involved by port, and its users within terminal/port area as well as throughout the CTLs chain. An importance-performance analysis (IPA) is applied as a diagnostic tool to analyse the status quo of Busan Port in CTLs contexts, by comparing the importance and performance (IP ) scores against each individual CTLs criterion. The findings from the IPA reveal that port managers and policy makers at the Busan Port should concentrate on six PSQ measures (i.e. SR1, SR4, ITS1, VAS1, VAS4, ICI3) to enhance PSQ in CTLs. However, four measures (i.e. ITS2, ITS3, ITS4, VAS2) are identified as a possible overkill, indicating an area of inefficiency where a remedial action of the cost-cutting decision is necessary. On the other hand, the Busan port shows an outstanding performance on four measures such as SR2, SR3, ICI1 and ICI2. The measures are not only important but also high performance. The study findings provide managerial guidance to port managers in Busan Port, in view of searching for managerial and operational strategies for sustainable port growth.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.191-197
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• 2006

Recently, the earth scale disaster is occurring frequently. Under the effects of global warming, the weather has become unseasonable worldwide. Hence, the earth is experiencing unstable condition with many disasters such as storms and flood damages as well as earthquake. Therefore, it is necessary to consider what we can do to prevent disasters. A disaster like earthquake will inevitably occur in view of the probabilities. The active period of earthquakes and the inactive periods repeat alternatively. Consequently, recent warnings indicate that there is a potential risk of massive earthquakes. Consideration of the effects of tsunami to the moored ship is very important. Operational problems such as moored ship motions sometimes become remarkable with large amplitude and long periods in harbor. Moored ship motions may cause the breakage of mooring systems such as mooring lines, fenders or quay. Large and long period moored ship motions are caused by resonant effects. In this paper, the moored ship motions within a harbor by the large-scale tsunami and the effects on the motions and mooring loads with resonant effects are investigated by numerical simulations.

• The Mathematical Education
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• v.40 no.2
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• pp.195-215
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• 2001

The purpose of this paper is to present a specific set of home teaching methods in hopes to prevent slow learner of the elementary mathematics. This paper deals with the number and operations, one of five topics in the elementary mathematics A survey of two hundred elementary school teachers was made to see the teacher's opinions of the role of home studying and to concretize the contents of the research topics. There were asked which is the most essential contents for the concrete loaming and which is the most difficult monad that might cause slow leaner. And those were found to be; counting, and arithmetic operations(addition and subtraction) of one or two-digit numbers and multiplication and their concepts representations and operations(addition and subtraction) of fractions. The home teaching methods are based on the situated learning about problem solving in real life situations and on the active teaming which induces children's participation in the process of teaching and learning. Those activities in teaching each contents are designed to deal with real objects and situations. Most teaching methods are presented in the order of school curriculum. To teach the concepts of numbers and the place value, useful activities using manipulative materials (Base ten blocks, Unifix, etc.) or real objects are also proposed. Natural number's operations such as addition, subtraction and multiplication are subdivided into small steps depending upon current curriculum, then for understanding of operational meaning and generalization, games and activities related to the calculation of changes are suggested. For fractions, this paper suggest 10 learning steps, say equivalent partition, fractional pattern, fractional size, relationship between the mixed fractions and the improper fraction, identifying fractions on the number line, 1 as a unit, discrete view point of fractions, comparison of fractional sizes, addition and subtraction, quantitative concepts. This research basically centers on the informal activities of kids under the real-life situation because such experiences are believed to be useful to prevent slow learner. All activities and learnings in this paper assume children's active participation and we believe that such active and informal learning would be more effective for learning transfer and generalization.

• Fire Science and Engineering
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• v.31 no.5
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• pp.107-116
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• 2017

Fires in tunnels are an international concern and fatal accidental fires in tunnels seem to occur on annual. They have the potential to become much worse int the future as more and longer tunnels are constructed and as traffic densities increase. This is a serious problem. The main purpose of this study is to develop operational procedures for fire brigades in road tunnel fires. This study discussed the past to see what can be learned from the incidents that have already done in tunnels. 73 cases of road tunnel fires domestic and outside of Korea were investigated and classified into 4 incident categories. Among them, 4 tunnel fires are highlighted, focusing on the activities of fire brigades and operation. Regarding the establishment of the strategies for fire fighting, 6 kinds of fire scenario curves have been deducted with regard to the relation between intervention time and heat release rate. It made the choice from the defensive or aggressive fire fighting activities depending on two criteria i.e. response limit and maximum response time. Road Tunnel Classification models can be useful when a fire brigade evaluates fire risk levels in the tunnels under its jurisdiction from the firefighting point of view and sets up preventive measures.