• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.1127-1143
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• 2016

The pounding phenomenon in adjacent structures happens in severing earthquakes that can cause great damages. Connecting neighboring structures with active and semi-active control devices is an effective method to avoid mutual colliding between neighboring buildings. One of the most important issues in control systems is applying online control force. There will be a time delay if the prose of producing control force does not perform on time. This paper proposed a time-delay compensation method in coupled structures control, with semi-active Magnetorheological (MR) damper. This method based on Newmark's integration is adopted to mitigate the time-delay effect. In this study, Lyapunov's direct approach is employed to compute demanded voltage for MR dampers. Using Lyapunov's direct algorithm guarantees the system stability to design a controller based on feedback. Because of the strong nonlinearity of MR dampers, the equation of motion of coupled structures becomes an involved equation, and it is impossible to solve it with the common time step methods. In present paper modified Newmark-Beta integration based on the instantaneous optimal control algorithm, used to solve the involved equation. In this method, the response of a coupled system estimated base on optimal control force. Two MDOF structures with different degrees of freedom are finally considered as a numeric example. The numerical results show, the Newmark compensation is an efficient method to decrease the negative effect of time delay in coupled systems; furthermore, instantaneous optimal control algorithm can estimate the response of structures suitable.

• Transactions on Control, Automation and Systems Engineering
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• v.2 no.4
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• pp.274-284
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• 2000

In this paper, the design methodology of digital fuzzy controller(DFC) for the systems with time-delay is presented and the qualitative effects of the quantizers in digital implementation of a fuzzy controllers are investigated. We propose the fuzzy feed-back controller whose output is delayed with unit sampling period and period and predicted. the analysis and the design problem considering time-delay become very easy because the proposed controller is syncronized with the sampling time. The stabilization problem of the digital fuzzy system with time-delay is solved by linear matrix inequality(LMI) theory. Furthermore, we analyze the stability of the quantized fuzzy system. Our results prove that when quantization os taken into account, one only has convergence to some small neighborhood about origin. We develop a fuzzy control system for backing up a computer-simulated truck-trailer with the consideration of time-delay and quantization effect. By using the proposed method, we analyze the quantization effect to the system and design a DFC which guarantees the stability of the control system in the presence of time-delay.

• The Journal of Korean Medicine
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• v.16 no.2 s.30
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• pp.299-311
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• 1995

The studies were investigated in the coma time and the survival time induced by KCN, the duration of breathing after decapitation, the survival time following ligation of both common carotid arteries and the survival time after it is treated for normobaric bypoxia with a nitrogen gas, a carbon dioxide gas or a vaccum in mice. The results were as follows: 1. In histotoxic anoxia, Moschus(0.4mg／kg, p.o) demonstrated a protective effect on coma induced by a sublethal dose of KCN(1.8mg／kg, i.v.) in mice. 2. Mice subjected to a lethal dose of KCN(3.0mg／kg, i.v.) did not die by administration of Moschus. 3. Moschus was significantly extended the duration of breathing after decapitation in mice. 4. Moschus showed a significant extension of survival time in mice following ligation of both common carotid arteries. 5. In the normobaric hypoxia with a nitrogen gas, Moschus showed a significant extension of survival time in mice. 6. In the normobaric hypoxia with a carbon dioxide gas, Moschus showed a significant shortness of survival time in mice. 7. In the normobaric hypoxia with a vaccum, Moschus showed a significant extension of survival time in mice. From the above results, it is suggested that Moschus demonstrated protective effects on the brain damages induced by cerebral anoxia.

• Culinary science and hospitality research
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• v.13 no.2
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• pp.69-80
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• 2007

The purpose of this study is that problems caused by labor environment of cuisiniers in hotels need to be considered and studies regarding a part-time cuisinier in a special-grade hotel need to be conducted. This study analyzes the influence of labor conditions and organizational commitment of a part-time hotel cuisinier on duty satisfaction. It consists of two parts: a research based on the review of the literature and empirical study methods. The method of human resource management in hotels such as treatment of a part-time cuisinier in a special-grade hotel and the way of management as a result of an empirical study are proposed. First, as a result of conducting research on duty satisfaction to part-time cuisinier, most of them are highly satisfied with their duty regardless of their age and academic backgrounds. Second, men hold a majority; woman staffs tent to have a had time working overtime considering the situation that hotels run for 24 hours. That is the main reason why less woman staffs work in hotels than man staffs do. Part-time staffs would like to work consistently after they get upgraded to a regular worker. Forth, it is considered to break down into detailed sectors and speciality is highly demanded.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.5
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• pp.409-415
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• 2012

This paper presents a new software-based on-line dead-time compensation technique for a single-phase grid-connected photovoltaic (PV) inverter system. To prevent a short circuit in the inverter arms, a switching delay time must be inserted in the pulse width modulation (PWM) signals. This causes the dead-time effect, which degrades the system performance around zero-crossing point of the output current. To reduce the dead-time effect around the zero-crossing point of grid current, a harmonic mitigation of grid current is used as an additional part of the synchronous frame current control scheme. This additional task mitigates the harmonic components caused by the dead-time from the grid current. Simulation and experimental results are shown to verify the effectiveness of the proposed dead-time compensation method in the single-phase grid-connected inverter system.

• Journal of Family Resource Management and Policy Review
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• v.19 no.2
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• pp.127-148
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• 2015

This study compared types of time and money attitudes by respondents' characteristics, and compared leisure consumption behavior and leisure satisfaction among different groups, which are classified by attitudes toward time and money. It also verified a structural model for the relationship of leisure satisfaction and the attitudes toward time and money, and investigated the moderating effects of leisure consumption behavior. Data were obtained from a questionnaire completed by 512 adult consumers. Using factor analyses and cluster analyses, this study classified the types of time and money attitudes. The time attitude was categorized according to four clusters: time-insensibility, future- oriented, present-oriented, and past-oriented. The money attitude was divided into four clusters: future safety, stinginess/anxiety, diversion, and power/prestige. The major findings of this study were as follows: First, the propensity of leisure consumption behavior to seek fashion and conspicuousness was higher for time-insensibility group than for the others. However, the propensity of rational consumption behavior for leisure was higher for the future-oriented group. The level of leisure satisfaction was the highest for the time-insensibility group. Second, the propensity of leisure consumption behavior to seek fashion and conspicuousness was higher for those who considered money as tools for diversion and power/prestige. The propensity of rational consumption behavior for leisure was higher for the future safety and stinginess/anxiety groups. The level of leisure satisfaction was significantly higher for the diversion group. Third, from the results of structural analyses, the time-insensibility attitude showed a positive effect on the leisure consumption behavior to seek fashion and conspicuousness. The future-oriented attitude had a positive effect on the propensity of rational consumption behavior for leisure. The money attitudes of diversion and power/prestige had positive impacts on the leisure consumption behavior to seek fashion and conspicuousness, although they had negative effects on the propensity of rational consumption behavior for leisure. The leisure consumption behavior to seek fashion and conspicuousness had a positive effect on leisure satisfaction, although the rational consumption behavior for leisure had a negative effect.

• Journal of Distribution Science
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• v.14 no.3
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• pp.55-62
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• 2016

Purpose - Average using time of smart-phone for Korean people is 3 hours 39 minutes and most people who are using a computer at home and their workplace can be affected over force to neck and shoulder due to unstable body posture. musculoskeletal disorders which caused by unstable body posture can affect strongly to decrease work efficiency. So this research is designed to measure the effect of using computer & smart-phone on decreased work efficiency due to musculoskeletal disorders and mediating effect between decreased work efficiency and musculoskeletal disorders. Research Design, Data, and Methodology - The author has developed a questionnaire with 6 hypothesis on the basis of previous research result with 5 constructs. The questionnaires were also made by interview and E-mail. 300 copies of questionnaires were distributed and 282 questionnaire were used for the analysis as valid data responses. SPSS ver.21.0 were used and made Cronbach's α and reliability test, correlation, Baron & Kenny 3 step mediated regression analysis. Result - Cronbach's α shows 0.770~0.954 and C.R. is 0.963~0.997 which is higher than 0.7. and AVE was 0.867~0.933. So the data are all acceptable condition. Using for a long time of a computer & smart-phone has a positive effect on musculoskeletal disorders. This means, it can cause musculoskeletal disorders if people use a computer & smart-phone for a long time due to unstable body posture. And musculoskeletal disorders can effect strongly decrease work efficiency. This study also found out that a long time of using computer can cause musculoskeletal disorders rather than using smart-phone a long time. To check mediate effect of musculoskeletal disorders between using a computer & smart-phone and Decreased Work Efficiency, author used 3-step mediated regression analysis of Baron & Kenny (1986). Using a computer for a long time mediate partially and using a smart-phone for a long time mediate completely. This means that using a smart-phone a long time is not the actual reason to decrease work efficiency. But using level of smart-phone is increasing rapidly day by day. So we need to make additional research about this matter seriously. Conclusion - Nowadays, people can not live on without a computer & smart-phone even a moment. But, using a computer for a long time will affect to cause musculoskeletal disorders and it will effect strongly to decrease work efficiency. Before, we thought over that musculoskeletal disorders were diseases of elder people. But, we found out from this study that musculoskeletal disorders can be happen to any people, even children, or workers in heavy industry or engaged in brain work. So we need to be careful when we use a computer for a long time. People also need to be careful to keep correct body posture when using both a computer and smart-phone since a smart-phone became more popular and using time level became longer. Due to increased income and living standard of people, physical growth of young people is so rapid. But the physical environment of society is not suitable for them since it can not follow up the speed of growth. Suitable work table is very important to prevent musculoskeletal disorder which can affect decrease work efficiency. For a person, a society or country, increased productivity is very important since it can directly connected to the job satisfaction. Education and reeducation for the people is also important, but to teach them how to keep good condition of health will be more important since it can increase the quality of work efficiency and quality of life. Computer and Smart-phone is one the best invention of modern society, but it can cause mental and physical disease which can affect decrease work efficiency and productivity. So it is necessary to observe attentively for the situation continually.

• Korean Journal of Weed Science
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• v.1 no.1
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• pp.69-77
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• 1981

Six herbicides were evaluated to investigate the phytotoxicity of rice plant and the weeding efficacy influenced by the time of application in mechically transplanted paddy field. The amount of each chemical applied was 3 kg, a. i, /ha. Chlormethoxynil : Rotala indica KOEHNE and Lindernia pyxuiaria PHILCOX were effectively controlled when applied on the 12th day after transplanting (12 DAT) and this herbicide was excellent for the control of Echinochloa crusgalli P. BEAUV, Monochoria vaginalis PRESL and Sagittaria pygmaea MIQ, when applied early (7 days after puddling) but its weeding effect for these weeds decreased greatly as the application time became later. It had a controlling effect for Potamogeton distinctus A. BENN, Cyperus serotinus ROTTB and Scirpus hotarui ROXB at the initial period at the earlier application time. Butachlor was effective in controlling E. crusgalli, R. indica and L. pyxidaria at 12 days after transplanting (DAT) but was not effective in controlling P. distinctus and S. pygmaea even at the early application time. M. vaginalis, C. serotinus and S. hotarui were effectively controlled by the butachlor treatment at 7 days after final puddling (2 DBT-SDAT) but this weeding effect decreased at the late application time. A combination of butachlor and naproanilide excellently controlled E. crusgalli, R. indica, L. pyxidaria and S. pygmaea regardless of the application time. For the control of M. vaginalis, C. serotinus and P. distinctus, the weeding effect of this mixtures was much greater than that of the single treatment of butachlor. Perfluidone was excellent for the control of E. crusgalli, R. indica, L. pyxidaria, M. vaginalis and S. pygmaea at either application time tested. P. distinctus, C. serorinus and S. hotarui could be controlled by this chemicals until the time of first observation (23 DAT) but the effect for these weeds somewhat decreased as time passed. The effect of pyrazolate on E. crusgalli, M. vaginalis, S. hotarui and P. distinctus was very excellent regardless of the application time but R. indica and L. pyxidaria could not be completely eliminated by this chemical. This chemical was effective in controlling C. serotinus when applied at 7-9 days after final puddling and showed a controlling effect for S. hotaruionly at the initial period. Piperophos + dimethametryn was very excellent for the control of all the annual weeds and P. distinctus. It showed a controlling effect on S. pygmaea, C. serotinus and S. hotarui only at the initial period. There was no difference in the effects on phytotoxicity and yield between chlormethoxynil and pyrazolate at either times of application tested. The later the application time was, the less the phytotoxicity of butachlor and piperophos+dimethametryne was. The phytotoxicity of butachlor + naproanilide and perfluidone decrease in the plots treated at the later application time. When the last two chemicals were treated at 2 days before transplanting (DBT) the yield decreased as compared with the hand weeded plot.

• The Journal of the Korea Contents Association
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• v.14 no.7
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• pp.395-406
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• 2014

This research observes how an adolescent's usage of social network services is related with media use time, and also tries to verify how a parent's participation in acting to limit usage time serves as a mediating effect. For this analysis, data from The Korean Information Society Development Institute [Korea Media Panel Research] was used, being a survey conducted on 1,572 students from primary to secondary and high schools nationwide. The subjects' gender in the final analysis was 818 male students and 754 female students. In addition, primary school students consisted of 672 individuals, 416 were from secondary and 484 from high schools. To verify the appropriateness of the model proposed in this research, analyzed through the structural equation, using social network services(SNS) was not shown to have an effect on media usage time. However, there was an indirect effect from the use of alternative activities. In addition, the parent's limitation of usage showed no effect on media use time. This research attempts to identify the reasons why parents' limiting the usage time, along with alternative activities, do not have any significant effect in reducing media usage time in this era of smart media evolution. Further, this research hopes to suggest meaningful and political implications for the nation and society to understand and resolve media addiction.

• 한국노년학
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• v.34 no.2
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• pp.315-331
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• 2014

The goal of this study was to examine the association between employment and depressive symptoms among older adults in Korea, including analysis of potential gender differences. Using a sample of Korean adults aged 60 years or older from the 2008(Time 2) and 2010(Time 3) national longitudinal survey data from the Korean Longitudinal Study of Ageing, we regressed measures of depressive symptoms at Time 3 on employment at Time 2 (and employment both at Time 2 and Time 3), controlling for Time 2 depressive symptoms, subjective physical health, and sociodemographic variables as well. First, there was no evidence that older adults with a job at Time 2 had significantly lower levels of depressive symptoms at Time 3 compared to their counterparts. However, multi-group analyses showed that the effect of employment at Time 2 on depression at Time 3 differed by gender. For older men, employment predicted better mental health over time. However, this was not the case for older women. As such work role provided benefits only for older men. Second, older adults with a job at both Time 2 and Time 3 reported significantly lower levels of depressive symptoms at Time 3 than older adults who did not have a job either at Time 2 or Time 3. However, only older men who were employed at both Time 2 and Time 3 reported significantly less depression than their counterparts. These findings suggest that the mental health effects of employment are contingent on gender.