• Journal of Communications and Networks
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• v.13 no.6
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• pp.639-654
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• 2011

In this paper, we present a channel access mechanism, referred to as the enhanced mesh coordinated channel access (eMCCA) mechanism, for IEEE 802.11s-based wireless mesh networks. The current draft of IEEE 802.11s includes an optional medium access control (MAC), denoted as MCCA, which is designed to provide collision-free and guaranteed channel access during reserved periods. However, the MCCA mechanism fails to achieve the desired goal in the presence of contending non-MCCA nodes; this is because non-MCCA nodes are not aware of MCCA reservations and have equal access opportunities during reserved periods. We first present a probabilistic analysis that reveals the extent to which the performance of MCCA may be affected by contending non-MCCA nodes. We then propose eMCCA, which allows MCCA-enabled nodes to enjoy collision-free and guaranteed channel access during reserved periods by means of prioritized and preemptive access mechanisms. Finally, we evaluate the performance of eMCCA through extensive simulations under different network scenarios. The simulation results indicate that eMCCA outperforms other mechanisms in terms of success rate, network throughput, end-to-end delay, packet-loss rate, and mesh coordinated channel access opportunity-utilization.

• International Journal of High-Rise Buildings
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• v.1 no.2
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• pp.99-105
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• 2012

The higher the building height and the larger the temperature difference between the outdoor and indoor space, the more remarkable is the draft driven by the stack effect in high-rise buildings. Moreover, the stack effect can bring about the deterioration of habitability and the degradation of the performance of the indoor control system in high-rise buildings. In this study, as a measure to attenuate the stack effect, the E/V shaft cooling method was proposed and its performance was compared with the conventional stack effect control method for strengthening the air-tightness of the building using a numerical simulation method. The total decreasing ratios on the stack effect in a building were compared, and the probabilities of the secondary problems were analyzed. The results show that the E/V shaft cooling is very effective to decrease the stack effect in a high-rise building in terms of the reduction performance and application. Moreover, this method does not cause secondary problems, such as stack pressure transition to other walls, unlike the conventional stack effect mitigation method.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.375-380
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• 2008

This study have processed the developing of vane damper with accurate control by using gear which is a flow-control equipment of marine boiler's FD fan on this research. For the developing of vane damper, we have corrected some problem from welding & assembly process by changing the design, and for the case of an emergency case, we have applied the easy disassembly & assembly on that vane damper. Compared to Rink type vane damper in current, we have focused on high efficiency with low price of that new developing damper. For selection of actuator, we have tried to find the propriety with our developing focus. Also, we have developed a jig of assembly processing for high productivity with quality, it caused the best assembly performance with heat-treated & processed parts.

• Journal of Navigation and Port Research
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• v.32 no.1
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• pp.1-7
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• 2008

Since the shipbuilding industry is at its peak to assimilate the large volume of orders in recent years, the Floating Dock has been an alternative to the dry dock which takes a certain period of time to build. Hence the use of Floating Dock is steadily increasing. Since the Skid Launching System(SLS) is used in Floating Dock, the balancing of the ship while launching is important and achieved by adjusting the Ballast tank of the Floating Dock. In this paper a Floating Dock Control Simulator for SLS is developed through the on-line interface of VRC(Valve Remote Control), Tank Level & Draft Measuring System and Valve Control algorithm on Simulation Tank Plan.

• Asia-Pacific Journal of Business
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• v.10 no.3
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• pp.125-142
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• 2019

The study wanted to verify the effect of emotional sub-compression, a negative variable of emotional labor, on job performance, on security personnel working at private security companies, and further to verify how the impact on emotional sub-compression can affect job performance through the first draft of regulation. Empirical analysis through the study model showed that emotional edema was not a significant effect, but a negative effect on job performance, and that it did not affect the control focus itself. This revealed that emotional harmony has been shown to have a negative impact on performance due to the present state and conflicting situations in one's emotions, which means that emotional harmony does not affect negative or positive effects depending on a person's attributes. It also showed that the temperamental control focus on job performance had a positive impact on employees with an improvement focus and had a negative impact on employees with a preventive focus, and that a temperamental control focus between emotional dissonance and job performance had an effect. This indicated that job performance was affected by a temperamental control focus and that employees with an improvement focus had a positive effect and had a positive effect on performance. The implications of the study in this study are that it can have target differentiation in the areas where the study was conducted on guard workers, a social issue related to the study of emotional labor, and it can be meaningful that the study of emotional labor had a control focus and measured both positive and negative tendencies. It is also believed that there will be contributions to the verification of differences in performance resulting from employee propensity and by linking it with a variable called emotional instability. However, the data collected have the limitations of the subject and region, and the emphasis on cross-sectional analysis and the representative of the various emotions to verify the negative effects of emotional labor, and the problem of securing reliability related to the adjustment focus verification are the limitations of the research.

• Journal of Nutrition and Health
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• v.31 no.8
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• pp.1355-1364
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• 1998

This study was planned to investigate the effect of 40 plant ethanolic extracts on antioxidant activities in vitro. The total phenolics, $\beta$-carotene, $\alpha$-tocopherol and selenium contents were also determined . Antioxidant activities fo the ethanolic extracts(0.02%, w/w) in the soybean oil were measured both by determining the peroxide value (POV) during 35 days of storage at 4$0^{\circ}C$ in a forced draft air-incubator and by determining changes in conductivity at 11$0^{\circ}C$(Rancimat method.). Soybean oil without any additives was used as a control and that treated with 0.02% BHT was used as a positive control. Based on the POV determination, green tea extract was found to be the most effective in stabilizing soybean oil, then followed by long tea, which both of them showed higher antioxidant activities compared to the BHT treatment. The antioxidant activities of them showed higher antioxidant activities compared to the BHT treatment. the antioxidant activities of coffee, cinnamomi cortex, acanthopanacis cortex, black tea, orange peel , instant coffee, peony and crni fructus extracts were stronger compared to the control .By the Rancimat method, green tea leaf and oolong tea leaf, foxglove, acanthopanacis cortex and peony extracts. Compared to other extracts, green tea leaf, black tea leaf, foxglove, acanthopanacis cortex and peony extracts had stronger antioxidative effects in both the POV and Rancimat methods used in this study. ethanolic extracts which showed the stronger antioxidative effect also has the higher contents of total phenolics, $\beta$-carotene, and/or $\alpha$-tocopherol. The antioxidative effect of ethanolic extracts was found to be due to the combined effect of various antioxidants.

• Journal of Korean Academy of Nursing
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• v.47 no.4
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• pp.526-539
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• 2017

Purpose: This study was undertaken to develop and test a mastery learning program of nursing skills for undergraduate nursing students. Methods: In this methodological study, first, the preliminary draft of a mastery learning program to provide training for nursing skills was developed based on Bloom's framework for mastery learning. Second, to test the developed program, a single-blinded, nonequivalent control group nonsynchronized study was conducted on 50 senior nursing students in a University selected by convenient sampling. Thirteen students were assigned to a control group; 13, 12, and 13 of them were assigned to intravenous therapy, transfusion, and patient transfer groups, respectively. The achievement levels and performance scores of the selected nursing skills were measured before and after the completion of the program in all the groups. Lastly, the final program was confirmed based on the results of the program testing. Results: Intravenous therapy, transfusion, and patient transfer were selected as essential nursing skills for the program based on the priorities rated by clinical instructors and staff nurses. The achievement levels of selected nursing skills were determined by Angoff scores. After participating in the program, the proportion of passers and performance scores of the nursing skills in the experimental groups were significantly higher than those in the control group. The final program was confirmed which included a diagnostic test, enrichment activities for the passers and three repetitions of corrective activities and formative assessments for non-passers. Conclusion: The results suggest that a mastery learning program for undergraduate students can lead to better improvement and performance of essential nursing skills.

• Journal of Navigation and Port Research
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• v.33 no.6
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• pp.375-380
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• 2009

The authors had consisted the construction of shipyard must be investigated under the consideration of long term ship's demand and so the Floating Dock might be an alternative to the dry dock. This paper shows a development of Floating Dock Controller for Skid Launching System(SLS). While loading out a block to the Floating Dock and launching ship from the Floating Dock, the balancing of the ship and the dock is very important and achieved by adjusting the Ballast tank of the Floating Dock In this paper a Floating Dock Controller for SLS was developed through the on-line interface of VRC(Valve Remote Control), Tank Level & Draft Measuring System and Valve Control algorithm on Tank Plan. The control system developed was applied to a shipbuilding and verified good and stable.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.190-201
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• 2021

The variable message sign (VMS) is equipment to improve the efficiency of traffic flow and safety of travel by providing real-time information to road users on traffic, road, weather situation, and traffic control due to construction. The information messages of the letter-based VMS taking up most of the VMS on the general national highways consist of section, travel time in sections, and road control situation. This study devised an improvement plan centered on road users, not road managers-centered existing message-based VMS through an analysis of road users' preference targeting the letter-based VMS operated in the general national highways in the Seoul Metropolitan Area. By presenting the measure for system improvement through which information on unexpected situations that road users prefer the most can be quickly and efficiently provided, this study aims to improve the efficiency of road user-centered VMS traffic information.

• Journal of Navigation and Port Research
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• v.47 no.2
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• pp.75-84
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• 2023

Ships need to ensure safety during their navigation, which makes route determination highly important. It must be accompanied by a route following controller that can accurately follow the route. This study proposes a method for automatically generating the ship route based on deep reinforcement learning algorithm and following it using a route following controller. To generate a ship route, under keel clearance was applied to secure the ship's safety and navigation chart information was used to apply ship navigation related regulations. For the experiment, a target ship with a draft of 8.23 m was designated. The target route in this study was to depart from Busan port and arrive at the pilot boarding place of the Ulsan port. As a route following controller, a velocity type fuzzy P ID controller that could compensate for the limitation of a linear controller was applied. As a result of using the deep Q network, a route with a total distance of 62.22 km and 81 waypoints was generated. To simplify the route, the Douglas-Peucker algorithm was introduced to reduce the total distance to 55.67 m and the number of way points to 3. After that, an experiment was conducted to follow the path generated by the target ship. Experiment results revealed that the velocity type fuzzy P ID controller had less overshoot and fast settling time. In addition, it had the advantage of reducing the energy loss of the ship because the change in rudder angle was smooth. This study can be used as a basic study of route automatic generation. It suggests a method of combining ship route generation with the route following control.