• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.6
• /
• pp.1112-1121
• /
• 2011

A microgrid is an aggregation of multiple distributed generators (DGs) such as renewable energy sources, conventional generators, and energy storage systems that provide both electric power and thermal energy. Generally, a microgrid operates in parallel with the main grid. However, there are cases in which a microgrid operates in islanded mode, or in a disconnected state. Islanded microgrid can change its operational mode to grid-connected operation by reconnection to the grid, which is referred to as synchronization. Generally, a single machine simply synchronizes with the grid using a synchronizer. However, the synchronization of microgrid that operate with multiple DGs and loads cannot be controlled by a traditional synchronizer, but needs to control multiple generators and energy storage systems in a coordinated way. This is not a simple job, considering that a microgrid consists of various power electronics-based DGs as well as alternator-based generators that produce power together. This paper introduces the results of research examining an active synchronizing control system that consists of the network-based coordinated control of multiple DGs. Consequently, it provides the microgrid with a deterministic and reliable reconnection to the grid. The proposed method is verified by using the test cases with the experimental setup of a microgrid pilot plant.

• Computers and Concrete
• /
• v.3 no.1
• /
• pp.65-77
• /
• 2006

This study reports the details of the finite element analysis of eleven shear critical partially prestressed concrete T-beams having steel fibers over partial or full depth. Prestressed concrete T-beams having a shear span to depth ratio of 2.65 and 1.59 and failing in the shear have been analyzed using 'ANSYS'. The 'ANSYS' model accounts for the nonlinear phenomenon, such as, bond-slip of longitudinal reinforcements, post-cracking tensile stiffness of the concrete, stress transfer across the cracked blocks of the concrete and load sustenance through the bridging of steel fibers at crack interface. The concrete is modeled using 'SOLID65'-eight-node brick element, which is capable of simulating the cracking and crushing behavior of brittle materials. The reinforcements such as deformed bars, prestressing wires and steel fibers have been modeled discretely using 'LINK8' - 3D spar element. The slip between the reinforcement (rebar, fibers) and the concrete has been modeled using a 'COMBIN39'-non-linear spring element connecting the nodes of the 'LINK8' element representing the reinforcement and nodes of the 'SOLID65' elements representing the concrete. The 'ANSYS' model correctly predicted the diagonal tension failure and shear compression failure of prestressed concrete beams observed in the experiment. The capability of the model to capture the critical crack regions, loads and deflections for various types of shear failures in prestressed concrete beam has been illustrated.

• Journal of Information Technology Applications and Management
• /
• v.23 no.2
• /
• pp.177-194
• /
• 2016

This study analyzed President Park's speeches and the government's industry policy in the field of information security using cognitive map. The relationship analysis between policy tool variables and policy goal variables was employed to derive revitalization strategy of information security. This paper found that entrepreneurship revitalization has very strong causality with expansion of domestic market and global market. But, on the other hand, HR development has very weak causality with job creation and future growth driver because the labor market in the information security industry is poor and its transfer rate to other industry is very high. This study showed that this cognitive map could be characterized by a scarcity of feedback loops and a strong emphasis on the positive loops in the structure of virtuous circle. In this paper, we also constructed a comprehensive cognitive map on the policy vision of information security, showing that there are a risk of cyber threat, an opportunity of new fusion security market, information security reinforcing circle, global economic circle, and domestic market circle.

• STI Policy Review
• /
• v.4 no.2
• /
• pp.74-95
• /
• 2013

Rapid changes in the economic, social and academic environments often provide opportunities to develop new and advanced technologies. In China, recent literature on the role of universities suggests that university-industry linkages (UILs) play a substantial role in the development of high-tech industries. Since 1979 when the country became more open and underwent economic reform, Chinese central authorities, local governments, and universities have continued to set up various science and technology (S&T) policies to stimulate UILs, contributing to China's technological progress and economic growth. This study examines the role of S&T policies on UILs such as transfer of technology, joint research, and spin-off creation with a particular focus on Nanjing University (NJU) in Jiangsu Province. Nanjing has over 53 universities, ranking it behind Beijing and Shanghai in terms of S&T and higher education opportunities. By adopting "institutional methodology," this study contends that UILs not only benefit universities and industry but also society in terms of job training, consulting activities, joint research, R&D results commercialization, patent licensing, new business creation, and other aspects. Finally, we suggest that the Chinese experience, though with some problems, might enhance our understanding of how to stimulate UILs through the arrangement of various S&T policies.

• Journal of the Ergonomics Society of Korea
• /
• v.29 no.1
• /
• pp.121-128
• /
• 2010

The purpose of this study is to confirm the impact of noise on subject accomplishment as well as physical/mental load, and evaluates the effects of noise-masking and earplug. 15 college students participate in the test, and the comparison is performed by executing four projects according to conditional categories of noise environments; control condition, noise condition, earplug condition, and noise-masking condition. Noise in the field site of the H manufacturer was used as the noise source, the general job aptitude test which consist of linguistic ability, math ability, perception ability, reasoning ability was used as the task of this project. To estimate physical/mental load evaluation, we used the heart rate R-R interval, Criteria flicker fusion frequency(CFF) and measured NASA-TLX workload for subjective evaluation. As the research outcome, it is shown that there is a meaningful difference for the project task score, dropping rate of CFF, the heart rate, and NASA-TLX subjective evaluation score according to conditions of noise environment. Therefore, the impact of noise on capability of subject accomplishment as well as physical/mental load was confirmed along with the effects of using earplug and noise-masking.

• Journal of the Ergonomics Society of Korea
• /
• v.30 no.6
• /
• pp.749-755
• /
• 2011

Objective: The purpose of this study is to assess the reducing effect of workload on developed electro-motion scissors. Methods: To achieve this, we measured the pressure distribution, Joint angle of fingers and JSI(Job Strain Index) for electro-motion scissors and hand-operated scissor in objective assessment and surveyed the uncomfortable degree in subjective assessment. Results: As a result, The peak of pressure in the electro-motion scissors was generally lower than the hand-operated scissors. JSI and overall joint angle of fingers for the electro-motion scissors were remarkably lower than the hand-operated scissors. Also, the subjective uncomfortable degree showed that the uncomfortable point of electro-motion scissors were generally lower than the hand operated scissors. Conclusion: The impact of reducing the work load as well as distributing the pressure around the hand by using electro-motion scissors during grapes pinching was confirmed.

• KIEAE Journal
• /
• v.6 no.3
• /
• pp.49-56
• /
• 2006

The roof among the outer surfaces of buildings is an optimum place to install PV since it is the best favorable part in the building to be exposed to day light. Especially, in case of module of BIPV for Roof, it should have essentially the functions of both electricity generation and roof-finish as a construction material. The followings are the results of the study which has analyzed the architectural conditions and applications thereof at the job site. -The aesthetic function of BIPV module is very important because the roof, mostly located at the top of the buildings, is easily recognized and affects outer interior design of the building a lot. -The heat proof of BIPV for Roof could affect the energy consumption through the roof having a wide area. -For architectural condition to the weather, the roof has to ensure the stability of the weather, humidity proof, and airtightness to the wind respectively. -For architectural condition of the structure, endurance by physical power such as stability of both combining and fixing and transfer of load should be ensured. -For residents protection, it has also architectural functions to secure for the space and shield ozone, UV and noxious substances. -Through its practical applications, It is already confirmed that there are various types of BIPV modules overseas and its application has been proved successfully.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• v.1
• /
• pp.371-376
• /
• 2006

Recently the container volume in the global trade is steadily increasing. In an effort to cope with this trend, major ports of the world are stepping up the introduction of high-tech equipments, trying to establish a highly efficient information system, and improving the internal work processes of their container terminals. For speedy and effective cargo handling, they are making every effort in the diverse fields. The purpose of this study aims at developing an intelligent multi-agent system for the gate work of a container terminal, which is the place of authority transfer in a container terminal. The agent system suggested in this study has made a comparison between COPINO information by TOS (Terminal Operating System) and information on containers and trucks recognized at the gate passage, checking up their efficiency, and performing the function of controlling outside truck's input-output. Also, based on the records of outside truck's gate passage, some gates can be operated flexibly, consequently enhancing the efficiency of the gate function. The results of job performance will immediately be notified to the customers and terminal managers, thus helping them make decisions speedily.

• Journal of Navigation and Port Research
• /
• v.46 no.5
• /
• pp.400-408
• /
• 2022

Maritime transportation is one of the most complicated and hazardous business fileds. Maritime accidents still occur despite several precautions since maritime is exposed to natural factors more than any other industries. In this harsh environment as a part of their job, marine pilots often embark/disembark to/ from vessels and confront life-endangering personal accidents. In the maritime field, several risk assessments are applied. However, all of them could not evaluate occupational accident risk for maritime pilot specifically. This paper performs specific risk analysis using the bow-tie method based on past accident records. This paper aims to qualify root causes and quantify root causes by importance level according to occurrence probability. As a result of analysis, occupational accident occurrence probability is found to be 14%, indicating that accident occurrence rate is significantly high. Hence, the probability of root causes triggering accidents and accident occurrence probability can be ascertained so that preventive measurements can be implemented. Besides theoretical achievement, this paper provides safety awareness to marine pilots, Marine Pilot Organizations, and ship crew who play a key role during marine pilots' transfer.

• Health Policy and Management
• /
• v.9 no.3
• /
• pp.129-148
• /
• 1999

This study was performed to investigate contents of affairs and job satisfaction of sanitary officials at sanitary department and health center. and to assess attitude about transfer of sanitary affairs control to health center and to devise Improving program of sanitary affairs. Four-hundred and fifty-five sanitary officials were sent a postal questionnaire and eighty-four percent completed and returned the questionnaire (382 persons). The major results are as follows: The major sanitary affairs performed by sanitary officials were permission and filing of restaurant business (15.1%), supervision and regulation of that (14.4%). Sanitary officials answered that supervision and regulation of insanitary and/or subquality foods, planning of food sanitary administration, and permission and filing of restaurant business were their important affairs. They replied that the most serious problem of sanitary affairs was 'lack of contribution to the public health' (40.9%), 'putting first in supervision' (26.4%), and 'lack of personnels' ( 19.1 %), and the most important thing to improve sanitary affairs was the substantial inherent affairs. And they indicated that the agency to be desired for sanitary affairs control was the sanitary department (51.6%), the health center (25.4%), For the degree of satisfaction in affairs, 29.1% of sanitary officials felt proud, 59.6% felt overwork, 59.3% hoped transferring to other worksite and the major reason of transferring was lack of promotion opportunity in officials of sanitary department. disciplinary punishment and social corrupt view in officials at health center. The 41.1 % of sanitary officials at sanitary department didn't know that sanitary affairs had been stated as affairs of the health center in Community Health Act. After transferring affairs control to the health center, 14.4% of them felt more proud of affairs but 20.0% less proud. 23.2% more satisfactory but 22.4% more dissatisfactory. and 64.8% answered that sanitary affairs did not change. The results indicate that sanitary affairs should be changed to supervise and control insanitary and/or subquality foods, so that they play an important role at health promotion, and make sanitary officials feel proud at their own work.