• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.05a
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• pp.547-549
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• 2014

In RFID systems, the performance for the tag identification is closely related with the tag collision, which is caused by the simultaneous transmission. The PS algorithm divides the tags within the identification range of reader into smaller groups by increasing the transmission power incrementally and identifies them. This algorithm uses the fixed frame size at every scan. Therefore, it is anticipated that the performance of PS algorithm can be variously shown according to the number of tags, frame size, and power level increase. In this paper, we analize the performance of PS algorithm according to the frame length and power level increase.

• Advances in Computational Design
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• v.6 no.1
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• pp.43-53
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• 2021

Multi-stage pumps are the most popular pumps among various kinds of centrifugal pumps. Athorough review of different kinds of literature has led to the conclusion that there is a desperate need to increase the performance of the multi-stage centrifugal pump. Many investigators have put their efforts to increase the pump performance and also the work is being projected on various aspects of pump performance variables. To improve the multistage centrifugal pump performance by investigation, modification, and analysis many works of literature are available. For analysis, many researchers used the Navier-Stokes solver to create the three-dimensional unsteady turbulent flow numerical model with the standard k-ε turbulent equation. This paper mainly focuses on research related to the multi-stage centrifugal pump.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.5
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• pp.715-724
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• 2022

In many electric vehicles, large-capacity pouch-type lithium-ion battery packs are mainly used to increase the mileage on a single charge. The lithium ion battery should be operated within the temperature range of 25℃ to 40℃ because the battery performance can be rapidly deteriorated due to an increase in internal temperature. Battery thermal management system (BTMS) can give the suitable temperature conditions to battery by water cooling method. In this research, the heat transfer characteristics (the battery temperature distributions and the water flow characteristics) were analyzed by CFD method to investigate the thermal performance of the cooling plate with 4-pass water flow structure. Moreover, the effect of the presence of fins between the battery cell was identified. The fins made smooth temperature distributions between the battery cells due to the heat spreading and lower the average battery cells temperature.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.2
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• pp.49-58
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• 1994

A study on the performance of a Diesel engine with various intake gas compositions other than that of air are performed experimentally. In this study, the concentrations of each of oxygen, nitorgen, carbon dioxide, and argon are changed and their effects on the performance of the engine are investigated parametrically. The experiments are performed at constant engine speed condition, and main measured parameters are cylinder pressure, intake gas compositions, fuel consumption rate. Increase of oxygen concentration up to 24% improved the performance of the engine generally. The adverse effect was observed when the oxygen concentration was increased over 24%. Increase of carbon dioxide concentration degraded the performance of the engine, mainly due to the lower specific heat ratio of carbon dioxide. Adding argon gas to the intake gas improved the overall performance. Finally, it is found that two most influencing factors affecting the performance of the Diesel engine in this study of intake gas composition variation are ignition delay and specific heat ratio of the intake gas.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.8
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• pp.577-588
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• 2020

The study investigates by empirical methods the effect of motivation, leadership, and organizational culture on job satisfaction, and employee performance at Wahana Resources Ltd North Seram District, Central Maluku Regency, Indonesia. This examination intends to be a critical review for academics researching the field of human resources management (HRM). The study's sample consisted of 155 employees who were selected using the Proportionate Stratified Random Sampling method. At the same time, data were collected using a questionnaire and then analyzed using the Structural Equation Modeling on Amos. The results of data analysis showed that work motivation and organizational culture had a positive and significant effect on performance, but did not significantly influence employee job satisfaction. While leadership has a substantial impact on employee job satisfaction, it does not affect performance. The results of testing the coefficient of determination show that job satisfaction is influenced for 57.4% by motivation, leadership, and culture variables, while employee performance variables are influenced for 73.5% by motivation, leadership, culture, and job satisfaction variables. Other factors outside this study influence the rest. Motivation, leadership, and organizational culture of employees need to be improved to increase job satisfaction. Invariably, if employee job satisfaction increases, employee performance will also increase.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.8
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• pp.562-570
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• 2011

In this research, an experimental study is performed to investigate the effects of system operating variables on the cooling and heating characteristics of heat pump system using geothermal heat source and carbon dioxide as a refrigerant. System variables analyzed include compressor frequency, electronic expansion valve opening, refrigerant charge, secondary fluid temperature and flow rate. Results show that optimum refrigerant charge and electronic expansion valve opening position exist at the maximum point of COP curve, and both cooling and heating capacity increase but COPs decrease with the increase of compressor frequency. The change of a secondary fluid temperature leads to variation of overheat area and enthalpy difference in the evaporator and gas cooler. which again results in considerable variations of cooling and heating capacity and COP. In the case of effects of secondary water fluid flow rate, both cooling capacity and COP increase with the increase of secondary flow in evaporator or gas cooler, whereas heating capacity and COP decrease with the increase of flow rate in gas cooler.

• Korea Journal of Hospital Management
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• v.20 no.3
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• pp.13-23
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• 2015

This research is intended to inquire any discrepancy depending on the variables such as types, geography and size of hospitals of Korea in order to develop differentiated marketing strategy and to investigate how the aforementioned variables affect the management performance such as the increase in the number of foreign patients, their willingness to re-visit, the increase in profit and etc. The survey for this research was conducted for five weeks from July 10th 2014 to August 30th 2014 with 251 participants in charge of foreign patient attraction for 161 domestic hospitals. As the method of the research, a hypothesis was first established based on previous studies, followed by the incorporation of self-administered questionnaire to confirm the formulated hypothesis. Frequency analysis and ANOVA analysis were used to analyze the result of the survey. The outcome of the research and the implications are as follows. First, according to the demography of the persons-in-charge of foreign patient attraction, the proportion of female was superbly high by 76.5%. As for the age, those in their 30s were highest in proportion. Finally, for the education level, college graduates took up the largest portion by 46.5%. Second, in respect to the hypothesis assuming the difference in performance depending on the types of hospitals, national university-affiliated hospitals showed the highest level of the increase in foreign patients by the average of 3.25. Third, in respect to the hypothesis assuming the difference in performance based on geographical position, it was confirmed that hospitals in Ulsan City experienced the largest growth in the number in foreign patients. Fourth, in respect to the sizes of hospitals, those with 201 to 300 sickbeds showed the highest increase by the average of 3.45. The implication of the above research outcome indicates that while the number of foreign patients visiting Korea for medical purposes is on the rise, the number of professionals in place with necessary knowledge and capacity is insufficient and requires improvement.

• Journal of Electrochemical Science and Technology
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• v.2 no.3
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• pp.131-135
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• 2011

It is, in general, believed that during the activation process, the proton conductivity increases due to wetting effect and the electrochemical resistance reduction, resulting in an increase in the fuel cell performance with time. However, until now, very scant information is available on the understanding of activation processes. In this study, dominant variables that effect on the performance increase of membrane electrode assemblies (MEAs) during the activation process were investigated. Wetting, pore restructuring and active metal utilization were analyzed systematically. Unexpectedly, the changes for both ohmic and reaction resistance characterized by the electrochemical impedance spectroscopy (EIS) after initial wetting process were much smaller when considering the degree of cell performance increases. However, the EIS spectra represents that the pore opening of electrode turns into gas transportable structure more easily. The increase in the performance with activation cycles was also investigated in a view of active metals. Though the particle size was grown, the number of effective active sites might be exposed more. The impurity removal and catalytic activity enhancement measured by cyclic voltammetry (CV) could be a strong evident. The results and analysis revealed that, not merely wetting of membrane but also restructuring of electrodeand catalytic activity increase are important factors for the fast and efficient activation of the polymer electrolyte fuel cells.

• Journal of the Society of Naval Architects of Korea
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• v.56 no.6
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• pp.515-522
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• 2019

Since Liquefied Natural Gas (LNG) is normally carried at 1.1 bar pressure and at -163℃, special Cargo Containment System (CCS) are used. As LNG carrier is becoming larger, typical LNG insulation systems adopt a method to increase the thickness of insulation panel to reduce sloshing load and Boil-off Rate (BOR). However, this will decrease LNG cargo volume and increase insulation material costs. In this paper, silica aerogel, glass bubble were synthesized in polyurethane foam to increase volumetric efficiency by improving mechanical and thermal performance of insulation. In order to increase dispersibility of particles, ultrasonic dispersion was used. Dynamic impact test, quasi-static compression test at room temperature (20℃) and cryogenic temperature (-163℃) was evaluated. To evaluate the thermal performance, the thermal conductivity at room temperature (20℃) was measured. As a result, specimens without ultrasonic dispersion have a little effect on strength under the compressive load, although they show high mechanical performance under the impact load. In contrast, specimens with ultrasonic dispersion have significantly increased impact strength and compressive strength. Recently, as the density of Polyurethane foam (PUF) has been increasing, these results can be a method for improving the mechanical and thermal performance of insulation panel.

• Journal of Fashion Business
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• v.16 no.5
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• pp.74-87
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• 2012

The service industry will be essentially extended during the economic growth and industrial development. Especially, the role of workers meeting the customers in service industry is very important from the view point of purchase intention. So many companies in service industry endeavor to increase the work efficacies of workers through the various prizes and incentives, and improve the job performance by additional education. Recently, the incentive tours are comprehensively accepted as an efficient tool to promote the loyalty and job performance of workers. The incentive tours enable the worker to gain the cultural experiences. They will experience not only the natural heritages and antiques, but also the local life culture and arts culture. The culture marketing for worker as the internal customer increase the worker's loyalty and the ties among workers, and therefore, their job performance will be increased. The empirical results (162 workers surveyed) showed the incentive tours have improved both the individual and group's job performance at a cosmetic sales organization. So it is recommend to plan the organization specific incentive tour in order to improve the productivity of the service organization.