• Journal of the Earthquake Engineering Society of Korea
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• 제17권3호
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• pp.117-125
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• 2013

Seismic isolation has been considered and utilized in various industries as a way to prevent huge damage on to structures by large earthquakes in various industries. The laminated Laminated rubber bearings is are most frequently used in seismic isolation systems. The structural Structural safety could not be assured unless the performance of the rubber bearing is not guaranteed for the life time of the structure under the consideration that the bearing is a critical structural member to sustain vertical loads in the seismically isolated structure. However, there are few studies on the deterioration problems of rubber bearings during their service life. The long term performance of the rubber bearings was not considered in past designs of seismically isolated structures. This study evaluates the long term performance and creep characteristics of laminated natural rubber bearings that are used in seismically isolated buildings. For the this study, a set of accelerated thermal aging tests and creep tests are were performed on real specimens. The experimental results show that the natural rubber bearings would have a stable change rate of change for durability under severe environmental conditions for a long time.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 한국해양정보통신학회 2003년도 춘계종합학술대회
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• pp.629-632
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• 2003

This paper presents a way to maximize transmission efficiency and reception ability through transmission diversity technology, which can be adapted to wireless multimedia OFDM system. The presented method is a comparative analysis between a case where parameter $\alpha$for time average is 0.3, 1 with consideration of channel presumption with two types of rms delayed proliferation, which is 50nsec, 150nsec, for the performance analysis of STTC(Space-Time Trellis Code) using time-space ciphering method appropriate for MIMO channel, and performance in the case where presumed channel value from long training column section is applied to according frame in a single frame. The result showed that BER brought SNR improvement of 1.0dB in 10-3 when $\alpha$ was 0.3 than using only the long training column, and showed increase of general performance improvement for the sake of time average rather than the case without.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 I
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• pp.473-476
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• 2003

In this paper, presents a way to maximize transmission efficiency and reception ability through transmission diversity technology, which can be adapted to wireless multimedia OFDM system. The presented method is a comparative analysis between a case where parameter a for time average is 0.3, 1 with consideration of channel presumption with two types of rms delayed proliferation, which is 50nsec, 150nsec, for the performance analysis of STTC(Space-Time Trellis Code) using time-space code method appropriate for MIMO channel, and performance in the case where presumed channel value from long training column section is applied to according frame in a single frame. The result showed that BER brought SNR improvement of 1.0dB in 10$^{-3}$ when a was 0.3 than using only the long training column, and showed increase of general performance improvement for the sake of time average rather than the case without.

• Proceedings of the KIEE Conference
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1228-1229
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• 2011

A novel approach has been promoted for FNN ship controllers. An Electro-hydraulic governor has been widely adopted to the ship speed control of propulsion marine diesel engines for a long time, it was very difficult for Electro-hydraulic governor to regulate the speed of high power engine with long stroke at low speed and low load, because of the jiggling phenomena by rough fluctuation of rotating torque and the hunting phenomena by long dead time occurred in fuel combustion process in the engine cylinder. This paper provides an efficient way for improving control performance by FNN controller. An RBF neural network and GA optimization are employed in a fuzzy neural controller to deal with the nonlinearity, time varying and uncertain factors, the rule base and membership functions can be auto-adjusted by GA optimization. The parameters of neural network can be decreased by using union-rule configuration in the hidden layer of the network. The performance of controller is evaluated by the system simulation using simulink tools.

• Proceedings of the IEEK Conference
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• 대한전자공학회 2003년도 하계종합학술대회 논문집 V
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• pp.2799-2802
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• 2003

The automatic diameter control system of the Crystal Grower has a good performance with only PD control. But it contained the integrator the plant which has a long time delay. In this paper. we show the secondary approximate model and applies time delay controller which is good performance for in the long time delay plant. It will be able to improve the response characteristic against a standard input and a load disturbance.

• Journal of the Korean Society of School Health
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• 제31권3호
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• pp.135-145
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• 2018

Purpose: The study aimed to investigate the factors associated with long hours of smartphone usage and to identify the characteristics of the high-risk group among female middle school students in South Korea. Methods: The study analyzed the data of 13,648 female middle school students using their own smartphone extracted from the 13th Youth Health Behavior Online Survey (2017). The factors related to using smartphones for a long time was analyzed by binomial logistic regression. The characteristics of the high-risk group was defined by a decision tree analysis. Results: The average hours spent on smartphone usage was 269.54 minutes per day. The significant factors associated with the long hours of smartphone usage were grade, living with parents, perceived household economic status, perceived academic achievement, stress, sadness and hopelessness, the main purpose of smartphone usage, drinking, body mass index, breakfast, and satisfaction with sleep quality. The subjects showing low academic performance and having breakfast four times a week or less were more likely to use their smartphone for a long time. Conclusion: Based on the results of the research, we need to establish intervention strategies focusing on the factors influencing long-time usage of smartphone. Particularly, the subjects who show poor academic performance and skip breakfast frequently should be considered as the high-risk group for spending long hours on smartphone usage.

• The Korean Journal of Health Service Management
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• 제5권3호
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• pp.77-88
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• 2011

As same time of starting on the Korean Long-term Care Insurance System, the government developed a program to train new qualification of long-term care workers. The number of enrolled long-term care workers are 950,000 persons in 2010. Mostly they are working in home based care work places such as home visit care centers and home visit bathing centers covered insurance. The purpose of this study is to understand the difference of task performance requirement according to long-term care workers' responsibilities which divided into home visiting care and home visiting bathing. The comparison analysis was conducted to task performance requirement in basic management, safety management, administration management, practical services. Key result was found that task performance requirement of long-term care workers whose responsibilities are home visiting care were more higher than the home visiting bathing. Finally, To improve quality of home visiting care and home visiting bathing, it is necessary to provide the fields based continuing education and reflect new reimburse system.

• Earthquakes and Structures
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• 제14권6호
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• pp.493-503
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• 2018

With the further increase of span length, the cable-stayed bridge tends to be more slender, and becomes more susceptible to the seismic action. By taking a super long-span cable-stayed bridge with main span of 1400m as example, structural response of the bridge under the E1 horizontal and vertical seismic excitations is investigated numerically by the multimode seismic response spectrum and time-history analysis respectively, the seismic behavior and also the effect of structural nonlinearity on the seismic response of super long-span cable-stayed bridge are revealed. Furthermore, the effect of structural parameters including the girder depth and width, the tower structural style, the tower height-to-span ratio, the side-tomain span ratio, the auxiliary piers in side spans and the anchorage system of stay cables etc on the seismic performance of super long-span cable-stayed bridge is investigated numerically by the multimode seismic response spectrum analysis, and the favorable earthquake-resistant structural system of super long-span cable-stayed bridge is proposed.

• Journal of information and communication convergence engineering
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• 제2권2호
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• pp.61-66
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• 2004

This paper presents a way to maximize transmission efficiency and reception ability through transmission diversity technology, which can be adapted to wireless multimedia Wireless LAN system. The presented method is a comparative analysis between a case where parameter a for time average is 0.3.1 with consideration of channel presumption with two types of rms delayed spread, which is 50nsec. 150nsec, for the performance analysis of STTC (Space-Time Trellis Code) adopting time-space ciphering method appropriate for MIMO channel, and performance in the case where presumed channel value from long training column section is applied to according frame in a single frame. The result showed that BER brought SNR improvement of l.0dB in $10^{-3}$ when a was 0.3 than adopting only the long training column, and showed increase of general performance improvement for the sake of time average rather than the case without.

• Journal of the Korean Solar Energy Society
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• 제40권2호
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• pp.11-23
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• 2020

The application of the high-performance insulation materials for buildings seems to be an essential measure for reducing energy use in buildings. Phenolic foam is a readily available insulation material with thermal conductivity of about 0.018 to 0.020 W/(mK). It has the advantage of higher thermal resistance and better fire resistance compared to other conventional building insulation materials. Insulation material used for building envelope is regarded as one of the decisive factors for building's energy load. Furthermore, the degradation of its thermal performance over time increasingly affects the building's energy use demand. Generally, the life span of conventionally built buildings is expected to be more than 50 years, so the long-term performance of insulation materials is critical. This paper aims to evaluate the long-term performance of phenolic form boards through an accelerated aging test. The tests were conducted according to BS EN 13166 and KS M ISO 11561. Based on the results of the accelerated aging test, the thermal performance variation of the material was analyzed, and then its aged value after 25 years was computed. Also, the characteristics of the phenolic foam board's long-term performance were also examined based on the standard testing methods adopted.