• Journal of Power Electronics
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• v.13 no.2
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• pp.197-205
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• 2013

In energy injection resonant AC-AC converters, due to the low frequency effect of the AC input envelope and the low energy injection losses requirement, the constant and steady control of the high frequency AC output envelope is still a problem that has not been solved very well. With the aid of system modeling, this paper analyzes the mechanism of the envelope pit on the resonant AC current. The computing methods for the critical damping point, the falling time and the bottom value of the envelope pit are presented as well. Furthermore, this paper concludes the stability precondition of the system AC output. Accordingly, an optimal control method for the AC output envelope is put forward based on the envelope prediction model. This control method can predict system responses dynamically under different series of control decisions. In addition, this control method can select best series of control decisions to make the AC output envelope stable and constant. Simulation and experimental results for a contactless power transfer system verify the control method.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.3
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• pp.273-279
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• 2004

There are several ways to solve parking problem in the downtown One of them is to manage parking efficiently, that is, to raise use-efficiency of parking place and to help drivers to select easily. When we manage the parking place m the block efficiently, It can prevent disproportion that some parking space is over capacity and the other parking one is under. It causes not only the disproportion of economic efficiency but also the congestion of local road. The precondition to manage parking efficiently is to analyse the parking characteristics. In this study we found out the characteristics of parking vehicles by analyzing the turnover per parking mesh and occupancy rate And we build up total D/B by collecting every information about parking space. We developed the Parking Management System by using GIS with D/B and digital map. The efficient Parking Management System is for convenience of drivers and efficient usage of parking space. And this system is also the basic study to be developed as the total Parking Management System by upgrading every information.

• Industrial Engineering and Management Systems
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• v.12 no.4
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• pp.336-350
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• 2013

This paper proposes a mathematical modeling-based approach for assessing disaster effects and selecting suitable mitigation alternatives to provide humanitarian relief (HR) supplies, shelter, rescue services, and long-term services after a disaster event. Mitigation steps, such as arrangement of shelter and providing HR items (food, water, medicine, etc.) are the immediate requirements after a disaster. Since governments and non-governmental organizations (NGOs) providing humanitarian aid need to know the requirements of relief supplies and resources for collecting relief supplies, organizing and initiating mitigation steps, a quick assessment of the requirements is the precondition for effective disaster management. Based on satellite images from weather forecasting channels, an area/dimension of the disaster-affected zones and the extent of the overall damage may often be obtained. The proposed approach then estimates the requirements for HR supplies, supporting resources, and rescue services using the census and other government data. It then determines reliable transportation routes, optimum collection and distribution centers, alternatives for resource support, rescue services, and long-term help needed for the disaster-affected zones. A numerical example illustrates the applicability of the model in disaster mitigation planning.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.12
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• pp.255-265
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• 2020

This study examines whether the adoption of International Financial Reporting Standards (IFRS) has increased financial statement comparability among firms and reduced undervaluation of Korean firms in the capital market by enhancing financial statement comparability. The so-called Korea Discount, which indicates an inefficient allocation of capital, has been attributed to lack of transparency and comparability of accounting information. Therefore, an efficient distribution of capital in the market was intended when IFRS was first adopted in Korea, but such progress is based on a premise of enhancement in Korean firms' accounting information comparability. This study conducts empirical analysis by using a comparability measure by De Franco et al. (2011). More specifically, it analyzes differences among comparability of domestic firms following IFRS adoption, with firms in the EU, which adopted IFRS in 2005, and with firms in the U.S., China and Japan that do not follow IFRS. The analysis of changes in domestic firms' comparability finds that their comparability improved following IFRS adoption. Meanwhile, the examination of cross-national differences in comparability demonstrates that, although there has been no significant change in comparability with firms in the U.S. and the EU across Korean industry since IFRS adoption, comparability with China has decreased while that with Japan improved.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2313-2318
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• 2003

By means of flexible forming processes in sheet metal manufacturing it is possible to produce parts of complex geometry within short manufacturing time. These procedures are suitable especially for prototyping or adjustment of deformation. Here formative procedures like laser forming are increasingly important, because they make the large-scale-like production of the prototypes with the required materials possible. High accuracy and reproducibility of the products is the precondition of the production. Due to the lack of a forming tool, complex geometries can hardly be manufactured within tolerances. To overcome this problem an automatic closed loop control system for the adjustment of deformations has been developed. An important element of the closed loop control system is the definition of a suitable irradiation strategy for laser forming. For the determination of the irradiation strategy a lot of influences must be taken into consideration from the field of material, geometry and laser. In this paper the improved closed loop control system and the development of an irradiation strategy for 4 mm deep buckles in an ALMgSi1 sheet will be represented. This system can be used e.g. in the automated adjustment of hail damage in car bodies or deformation by heat treatment.

• Journal of The Korean Digital Architecture Interior Association
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• v.8 no.2
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• pp.21-28
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• 2008

The main purpose of this paper is to find the phase-in of BIM adoption by focusing on the level of integration. BlM should be aimed at integration and collaboration of all parties furnishing design and construction services to increase the productivity. Therefore, the degree and depth of integration for project collaboration is very important to BlM design process. One of the key advantages of full integration is that is to facilitates the development of detailed information much earlier in the entire design process to improve collaboration among stakeholders. Such integrated use is the ultimate method, but even so, it's not the precondition of BlM. One of the key advantages of relatively low integration as a transition phase is to adopt the BlM earlier than full integration. Such transitional and non-integrated BIM can also reduce the possibility of trial and error in BlM adoption. Therefore, this paper focused on non-integrated use of BlM as a substitute of full IPD by analyzing obstacles in BIM adoption.

• Journal of the Ergonomics Society of Korea
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• v.21 no.3
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• pp.13-24
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• 2002

Reduction and prevention of human error is one of the major interests for the enhancement of system safety and availability in Nuclear Power Plants (NPPs). As human beings have become the weak point in the system safety, a systematic evaluation on human performance during emergency situation should be performed in advance to identify the potential vulnerability of human tasks. Though the data gathering and analysis from real field is an important precondition, there were no available data in nuclear field of korea. This paper presents the result of human performance analysis on emergency tasks in NNPs. Firstly, a task analysis was performed to identify the characteristics of operator tasks during emergency condition and to classify them into a set of generic emergency tasks. Secondly, simulation data were collected and analyzed for the emergency tasks using the full scope simulator of Younggwang NPPs. The analyzed human performance information cover the event diagnosis time, the execution time of each procedural step, observation parameters, typer of irrelevant response, pattern of communication among staffs, and so on. These performance data would be used for human reliability analysis and the research of human error as technical bases.

• The Korean Journal of Health Service Management
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• v.5 no.4
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• pp.53-63
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• 2011

This study focused on 'The Health' which should considered as a precondition for the local residents by reinvestigating the indicators of happiness after Young-Do ward formulate a community social welfare plan. There is purpose of this study as below. I searched an general attribute and the indicators of happiness, then looked how does results from questions about health and factors of the indicators of happiness can affects the health with some kinds of elements. Five hundred people from the inhabitants of Young-Do ward who is living in Young-Do district were separated by using the random sampling method as the subject of the study. The investigation took effect from October to November of 2010 and an investigator visited the inhabitants of a ward with structured questionnaire. An investigator had one-on-one talk with inhabitants of Young-Do ward while the investigation and I also collected the data through self-administered questionnaire as well. I found the physical elements influence in the health much more than the outside factors from the study. Higher satisfaction of their career, relationship between friends and co-workers, work environment and married life reflects the fact that higher self-contentment means high quality health level.

• KSBB Journal
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• v.24 no.1
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• pp.9-16
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• 2009

Chemotaxis is the movement of an organism toward chemical attractant and away from chemical repellents. Several bacteria are known to cometabolically degrade some pollutants and attracted to the pollutants. The chemotactic responses to these compounds influence the efficiency of bioremediation because the first precondition of pollutant degradation is definitely confrontation between microorganisms and pollutants. In this review, we summarize present knowledge of about the chemotactic mechanism to environmental pollutants of Pseudomonas species.

• Proceedings of the KIEE Conference
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• 1999.07c
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• pp.1049-1053
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• 1999

It is important to measuring and monitoring about state vectors of power system for precise operation control. All state vectors cannot be measured because it is economically disadvantageous, so that some state vectors are determined using state estimator. Determination of observability is a important precondition of power system state estimation because state estimation can be performed when given power system is observable. Recently as time-synchronization technique progress, using the PMU(Phasor Measurement Unit), state vector can be measured directly so that voltage phasor and current phasor measurements can be used for power system estimation. In this paper, observability algorithm is proposed to determinate the observability with real/reactive injection power measurements and real/reactive lineflow power measurements of existing measurement system and with phasor measurements of PMU. The jacobian matrix is newly composed for state estimation with measurements of added PMU, and state estimation is performed with least square estimatior. Comparison between state estimation result of existing measurement system and that of measurement system added PMU is presented.