• Journal of information and communication convergence engineering
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• v.19 no.1
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• pp.1-7
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• 2021

Reinforcement learning is an area of machine learning that studies how an intelligent agent takes actions in a given environment to maximize the cumulative reward. In this paper, we propose a new MAC protocol based on the Q-learning technique of reinforcement learning to improve the performance of the IEEE 802.11 wireless LAN CSMA/CA MAC protocol. Furthermore, the operation of each access point (AP) and station is proposed. The AP adjusts the value of the contention window (CW), which is the range for determining the backoff number of the station, according to the wireless traffic load. The station improves the performance by selecting an optimal backoff number with the lowest packet collision rate and the highest transmission success rate through Q-learning within the CW value transmitted from the AP. The result of the performance evaluation through computer simulations showed that the proposed scheme has a higher throughput than that of the existing CSMA/CA scheme.

• International Journal of Safety
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• v.3 no.1
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• pp.47-52
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• 2004

Current OSH system was analyzed in this paper to explain why high fatal incidents and disasters are continuously repeated for recent years in Korea. It was found that we have Dichotomous Perceptional Misconception of prevention before accident and compensation after accident and there is a significant lack of proper feed­back reward system for OSH performance. It was assumed that no reduction of accident rate and fatality rate have not been achieved recently despite of a great effort and increased resource allocations. Some statistics for proving weak punishment were analyzed. In the current system, the will of administrative agency would have been very limited particularly in the legal aspects. The Industrial Safety and Health Act is not suitable to after-injury punishment for employer and/or corporate since it is based on a framework for enforcement of prevention. Based on these analyses, it was concluded that there was a need to consider a special law for Corporate Accountability for Fatal Accidents. Because it is necessary to consider seriously for introduction of a new legal system for after injury punishment to repair the current system where it was found lack of proper feedback system. Also, there was no proper sanction measures for corporate with the current OSH legal system, and the most urgent problem in OSH area is the high fatality rate. it is necessary to consider seriously for introduction of a new legal system for after injury punishment. Also, there is no proper sanction measures for corporate with the current OSH legal system, and the most urgent problem in OSH area is the high fatality rate.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.5
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• pp.2015-2028
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• 2016

In this paper, we propose a sum transmission rate maximization based cooperative spectrum sharing protocol with quality-of-service (QoS) support for both of the primary and secondary systems, which exploits the situation when the primary system experiences a weak channel. The secondary transmitter ST_b which provides the best performance for the primary and secondary systems is selected to forward the primary signal. Specifically, ST_b helps the primary system achieve the target rate by using a fraction of its power to forward the primary signal. As a reward, it can gain spectrum access by using the remaining power to transmit its own signal. We study the secondary user selection and optimal power allocation such that the sum transmission rate of primary and secondary systems is maximized, while the QoS of both primary and secondary systems can be guaranteed. Simulation results demonstrate the efficiency of the proposed spectrum sharing protocol and its benefit to both primary and secondary systems.

• The Journal of Economics, Marketing and Management
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• v.12 no.2
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• pp.1-10
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• 2024

Purpose: This study conducted an empirical study to estimate the loss aversion rate of individual investors in the Seoul condominium market. Research design, data and methodology: A survey was conducted with Seoul residents ranging from 30's to 60's with various backgrounds. Descriptive statistical analysis and a paired sample t-test were conducted using SPSS 27.0 statistical package. Results: The results of the t-test showed that Seoul residents are indeed more sensitive to loss than gains, as pointed out in various researches related to behavioral economics. Also, the loss aversion rate associated with KRW 50 million risk was found to be 2.14. Finally, the same question was asked with KRW 100 million risk, doubled associated risk of previous question, using the same scenario, and it's been verified that the loss aversion rate increases as the associated risk or stake increases. The loss aversion rate with double risk is 2.26 which is about 5% higher than the one with KRW 50 million risk. Conclusions: This study can help many groups of people in society who need to establish rewards and punishment policies within any organization. In particular, incorporating human cognitive biases, such as loss aversion can help the South Korean government shape more effective reward and punishment policies when building rewards and punishments using taxes.

• Journal of Communications and Networks
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• v.16 no.2
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• pp.140-145
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• 2014

In this paper, we propose an anti-interference cooperative spectrum sharing strategy for cognitive system, in which a secondary system can operate on the same spectrum of a primary system. Specifically, the primary system leases a fraction of its transmission time to the secondary system in exchange for cooperation to achieve the target rate. To gain access to the spectrum of the primary system, the secondary system needs to allocate a fraction of bandwidth to help forward the primary signal. As a reward, the secondary system can use the remaining bandwidth to transmit its own signal. The secondary system uses different bandwidth to transmit the primary and its own signal. Thus, there will be no interference felt at primary and secondary systems. We study the joint optimization of time and bandwidth allocation such that the transmission rate of the secondary system is maximized, while guaranteeing the primary system, as a higher priority, to achieve its target transmission rate. Numerical results show that the secondary system can gain significant improvement with the proposed strategy.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.40-40
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• 2003

Spontaneous firing rate and patterns of dopaminergic neurons in midbrain are key factors in determining the level of dopamine at target loci as well as in the mechanisms such as reward and motor coordination. Although glutamate, as a major afferent, is reported to enhance firing rate, the detailed actions of NMDA-, AMPA/kainate-, and metabotropic glutamate receptors (mGluR) on filing patterns are not clear. Thus we have investigated the role of glutamate receptors on the spontaneous firing activities using the network-free, acutely isolated dopamine neurons from substantia nigra pars compacta(SNc) of the 9-14 days rat. The isolated cells showed spontaneous regular firings of near 2.5 Hz, whose rate was enhanced by glutamate at submicromolar levels (0.3 $\square$M) but abolished by high concentrations more than 10 $\square$M.

• Korea Journal of Hospital Management
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• v.6 no.1
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• pp.18-40
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• 2001

This study purports to investigate the readiness of the university hospital employees in the knowledge-based management. Data were collected from 550 employees including administrative, nursing, and technical staff of 9 university hospitals located in Seoul and Kyunggi Province through the self-administered questionnaires. The response rate was 79% and 425 questionnaires were used as final data and analyzed using 2 test, t-test, and ANOVA. The main findings of the study are as follows. 1) It seems that most employees of the study hospitals have basic knowledge on the concept of knowledge-based management. This finding implies that the implementation of the knowledge-based management in Korean university hospitals will not likely to face strong resistance from their employees. 2) The results show that Korean hospital employees are still not so accustomed to using e-mail as the main communication tool. This finding suggests that it is necessary to use various communication tools which include electronic data interchange, teleconference, and cyber chatting for facilitating the knowledge-based management in Korean university hospitals. 3) It is desirable to appoint a chief knowledge officer(CKO) for operating knowledge-based management system effectively. 4) A reward system for employees who show a distinguished performance in the creation and sharing of new knowledge should be established. Knowledge mileage system, selection of the best knowledge employee and team will be a good example of the effective reward system. 5) The participation and support from the chief executive officers (CEO) of the hospitals is an important factor for successful knowledge-based management. Furthermore, to make physicians actively participate in the knowledge-based management is another important factor for obtaining valuable outputs from the system. 6) It is found that the knowledge and skills of the hospitals employees on the information technology (IT) are not sufficient for making knowledge-based management more popular. This implies that it is very important to select IT-oriented employees and educate them continuously on the knowledge-based management.

• Journal of Digital Convergence
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• v.11 no.12
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• pp.479-485
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• 2013

Virtualization is a promising approach to consolidating multiple online services onto a smaller number of computing resources. A virtualized server environment allows computing resources to be shared among multiple performance isolated platforms called virtual machines. Through server virtualization software, applications servers are encapsulated into VMs, and deployed with APIs on top generalized pools of CPU and memory resources. Networking and security have been moved to a software abstraction layer that transformed computing, network virtualization. And it paves the way for enterprise to rapidly deploy networking and security for any application by creating the virtual network. Stochastic reward net (SRN) is an extension of stochastic Petri nets which provides compact modeling facilities for system analysis. In this paper, we develop SRN model of network virtualization based on virtual switch. Measures of interest such as switching delay and throughput are considered. These measures are expressed in terms of the expected values of reward rate functions for SRNs. Numerical results are obtained according to the virtual switch capacity and number of active VMs.

• Korean Journal of Occupational Health Nursing
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• v.25 no.1
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• pp.55-64
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• 2016

Purpose: The aim of this study was to investigate the association between job stress and metabolic syndrome among male workers. Methods: A total of 396 male workers employed in an electronic company, located in 'P' city, Gyeonggi Province, who had taken medical examination at the 'D' hospital, volunteered in this study. All the data used in this study were obtained from 'D' hospital after getting consent and permission from the workers. General and occupational characteristics, medical history, and health-related behaviors of the subjects were obtained by self-administered questionnaire. Results: The highest occupational stress by sub-sector was reported in the order of insufficient job control, organizational system, lack of reward, job demand, job insecurity, physical environment, job culture, and relationship conflict. The prevalence rate of metabolic syndrome of the participants was 19.9%. The results of the multiple logistic regression analysis on metabolic syndrome of the subjects indicated that the syndrome was significantly higher among those with family history, smoking habit and ex-smoking, working duration of 3 years and over, and with higher total score of occupational stress. It was significantly more prevalent, when the degree of stress was high in the sub-sectors of occupational stress; job autonomy, job insecurity, lack of reward, and job culture. Conclusion: In conclusion, it is necessary to implement a plan to efficiently manage the job stress of these male workers, as the probability of metabolic syndrome increased with the increase of occupational stress. Furthermore, considering the highest occupational stress was found to be job autonomy among its sub-sectors, it is necessary to prepare various measures to enhance the autonomy of such employees.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.12
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• pp.1-8
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• 2005

In this paper, we study a call admission control algorithm for supporting multicast service under the BcN environment where broadcasting, communication and Internet are converging to be one. It is necessary to control service requests with a certain criteria in order to guarantee QoS because the system capacity is limited. As a possible solution, we divide one multicast service into 3 classes and set up a threshold per each class to control service request. Especially, for the purpose of system benefit, we define system pay-off rate 'GAIN' with the term 'Reward' and 'Penalty' according to admit and reject service request. And we confine the range of threshold which makes GAIN to be maximized. For the performance analysis, we model the system as M/M/m/m queueing system, investigate GAIN under various conditions and show the effectiveness of the proposed algorithm.