• The Transactions of The Korean Institute of Electrical Engineers
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• v.57 no.1
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• pp.52-57
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• 2008

In the transformer that is used for the contactless power transmission system, the primary and secondary sides are separated structurally unlike general transformers. When the contactless transformer is built, it forms relatively bigger air gap than the general transformer. Thus it is difficult to transfer energy from the primary side input to the secondary side output with high power efficiently because of low coupling coefficient. This paper proposes a contactless transformer using the rectangular type core that maintains high coupling coefficient even when it has relatively large air gap. The performance characteristics of the proposed transformer are compared with the transformer using general EE core to the air gap variation. The proposed contactless system using rectangular type core and dc-dc full bridge converter, and the system using EE core type and dc-dc full bridge converter are respectively implemented and their performance characteristics are verified by the simulation and experiment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.8
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• pp.3366-3383
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• 2020

The Poisson point process (PPP) is widely used in wireless network modeling and performance analysis because it can provide tractable results for heterogeneous cellular networks (HetNets) analysis. However, it cannot accurately reflect the spatial distribution characteristics of the actual base stations (BSs). Considering the fact that the distribution of macro base stations (MBSs) is exclusive, the deployment of MBSs is modeled by the Matérn hard-core point process (MHCPP), and the deployment of pico base stations (PBSs) is modeled by PPP. This paper studies the performance of multiantenna HetNets and improves the energy efficiency (EE) of HetNets by optimizing the transmit power of PBSs. We use a simple approximate method to study the signal-to-interference ratio (SIR) distribution in two-tier MHCPP-PPP HetNets and derive the coverage probability, average data rate and EE of HetNets. Then, an optimization algorithm is proposed to improve the EE of HetNets. Finally, three transmission technologies are simulated and analyzed. The results show that multiantenna transmission has better system performance than single antenna transmission and that selecting the appropriate transmit power for a PBS can effectively improve the EE of the system. In addition, two-tier MHCPP-PPP HetNets have higher EE than two-tier PPP-PPP HetNets.

• Hwankyungkyoyuk
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• v.15 no.2
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• pp.30-48
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• 2002

This study is on theoretical foundation for orthodoxy korean style Environmental Education based on oriental ecological thought. The main theme is that various kinds of all the ideas related with ecological thought based on oriental thoughts for EE should be focused into Moderation, the core-concept of oriental confuscian thoughts. The Moderation has not meant just a personal enlightenment, as it has known to general people, it can be developed into social status core-consciousness for regulating the natural resource. So we should focus on this conceptual developing mechanism personal enlightenment into social status for our orthodoxy konean style EE. It can be infered from Taoism, Confuscionism Buddism, especially, Anxiety Consciousness (WOOHWAN) for grand-scale anxiety to public society and universal cosmos. And also I drawed Harbermas-philosophy to provide good means for fortifying this research. His communication theory and restoration of real life for public people communication can be connected to oriental thoughts in the aspect of reciprocative response among the community people. So our orthodoxy korean style EE can be erected on the community-based regionality and their public communication through reciprocative response process. We should try to make this surrounding conditions nature-familiar oriental philosophy has provided from ancient times in the aspect all the traditional thought has been eco-deterministic.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.1216-1222
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• 2009

Ecological Engineering (EE) refers to all sustainable engineering that can reduce damage to ecosystems and that adopts ecology as a base and safety as an orientation in order to implement conservation of biodiversity and sustainable development. In short, EE attempts to safeguard the ecological environment while any essential construction projects proceed. EE encompasses many fields, including construction skills, ecosystem preservation, landscape, and even related cultures and so on. Such variety results in greater complexity of construction, and, consequently, indirectly increases the difficulty of construction quality control. The objective of our research is to explore a promising model for EE via an extensive literature survey. This model includes three principal stages: plan-design, construction, and maintenance, along with individual accompanying phases concerned with quality control and vital management. In this article, a river restoration example is adopted to describe in detail the critical points of quality control in the three stages (plan-design, construction, and maintenance) of the construction life cycle. This study proposes an integrated structure for quality management of EE to guarantee its quality and to enhance its core applications in order to achieve long-lasting preservation of the environment.

• Journal of Power Electronics
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• v.4 no.1
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• pp.12-17
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• 2004

In this paper, a practical implementation to reduce leakage flux of a high-frequency inverter based non-contact type power transformer composed of EE-shape ferrite cores is presented for key technology of the next generation medical use X-ray CT scanner system. Design consideration for the unique structure of the non-contact power transformer with 900mm in diameter is also introduced. The complete non-contact transformer is actually arranged by several blocks of the magnetic circuit assembled by using 10 small EE shape cores with 120mm in length. It is experimentally and analytically discussed from a reduced leakage flux viewpoint related to its inductively coupling coefficient. A practical method to lower the leakage flux is described based on effective Copper-Sheet- Treatment placed on EE shape ferrite cores of magnetic circuit.

• IEMEK Journal of Embedded Systems and Applications
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• v.13 no.5
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• pp.225-234
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• 2018

Control flow errors are caused by the vulnerability of memory and result in system failure. Signature-based control flow monitoring is a representative method for alleviating the problem. The method commonly consists of two routines; one routine is signature update and the other is signature verification. However, in the existing signature-based control flow monitoring, monitoring target application is tightly combined with the monitoring code, and the operation of monitoring in a single thread is the basic model. This makes the signature-based monitoring method difficult to expect performance improvement that can be taken in multi-thread and multi-core environments. In this paper, we propose a new signature-based control flow monitoring model that separates signature update and signature verification in thread level. The signature update is combined with application thread and signature verification runs on a separate monitor thread. In the proposed model, the application thread and the monitor thread are separated from each other, so that we can expect a performance improvement that can be taken in a multi-core and multi-thread environment.

• The Transactions of the Korean Institute of Power Electronics
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• v.8 no.5
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• pp.407-417
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• 2003

Detachable transformers used in contactless battery chargers have poor power transfer characteristics because they have low coupling coefficients due to their gaps. The ㄷㅓ type core gives a high coupling coefficient in a contactless battery charger compared with standard cores such as EE, EC and UU. In this paper, characteristics of the ㄷㅓ type core is studied. Detailed analyses and comparisons are given based on the sinusoidal operation and square-wave operation. Reductions in output current, voltage and power are stated analytically and numerically. The analyses are verified by experiments conducted on a ZVS converter including a detachable transformer. The analyses and comparison method can be applied to other gaped transformer such as a PCB transformer.

• Hwankyungkyoyuk
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• v.20 no.4
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• pp.12-26
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• 2007

The purpose of this research is to develop a water environmental education (EE) program using streams, based on the core ideas of ENVISION and materializing elements that were extracted in this research. This research realized the elements and presented a model of the water EE program using a local stream. First, this research developed a basic model of a water EE program using streams by extracting 10 materializing elements and realizing the elements in 4 stage-procedural model. The 10 materializing elements were 1. experiencing the process of inquiry, 2. inquiring local environments, 3. self-directing learning and mutual interaction with colleagues, 4. collecting real data and interpreting, 5. utilizing the ICT(information and communication technology), 6. inquiring with the view point of the 'Environmental Studies for EE', 7. inquiring with the watershed concept, 8. inquiring with the integrating and the holistic view point, 9. pursuing the macroscopic understanding about environment, and 10. connecting the real world phenomena with the environmental concepts and theories. This research materialized these 10 elements in 4 stage model, following the previous ENVISION research, which are 1. preparing stage and visual assessment, 2. writing the report of the inquiry plan, 3. collecting the real data in the environment and performing the investigation, and 4. presenting the inquiry results. Second, with using this basic model, this research developed and presented a model of the specific water EE program using a case stream called 'Baig Cheon' stream, which is a local stream. This research is considered to have a considerable meaning in developing a EE program with ENVISION ideas for the watershed concept and inquiry with environmental science using local streams. The developed model can help the professional development of teachers and teacher education of water EE.

• Journal of KIISE:Software and Applications
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• v.30 no.5_6
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• pp.529-539
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• 2003

Due to the emersion of J2EE (Java 2, Enterprise Edition), many enterprises inside and outside of the country have been developing the enterprise applications appropriate to the J2EE model. With the help of the component model of Enterprise JavaBeans (EJB) which is the J2EE core technology, we can develop the distributed object applications quite simple. EJB application can be implemented by using the component-oriented object transaction middleware and the most applications utilize the distributed transaction. Due to these characteristics, EJB technology became popular and then the study for EJB based application has been done quite actively. However, the research of techniques for the performance monitoring during run-time of the EJB applications has not been done enough. In this paper, we propose the techniques for monitoring the performance of EJB Application on the run time. First, we explore the workflow for the EJB application service and classily the internal operation into several elements. The proposed techniques provide monitoring the performance elements between the classified elements. We can also monitor by extracting the performance information like state transition and process time of the bean which is related to the lifetime occurred during one workflow, and the resource utilization rate.

• Proceedings of the KIEE Conference
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• 2004.07e
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• pp.49-51
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• 2004

This paper researched the power loss characteristics according to winding method of high frequency transformer. Power loss was analyzed by PExprt using FEM software. The ferrite core model for analysis be used the EE type. Transformer model objected type applied to flyback converter. Therefore, analysis result was obtained the many parameter of DC, AC resistance, leakage inductance, copper loss, core loss, and temperature etc.