• Proceedings of the Korea Contents Association Conference
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• 한국콘텐츠학회 2008년도 춘계 종합학술대회 논문집
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• pp.771-775
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• 2008

Concerns related to protecting, identifying, and isolating of subsystems of a water distribution network have led to the realization of the increased importance of valves in the system. The most important purpose of valves in water distribution systems is to isolate subsystems due to breakage, maintenance activities, or contamination. A subsystem called segment is isolated by the closure of adjacent valves and an efficient algorithm should identify the adjacent valves to minimize the pipe failure impact. In this paper, an algorithm to identify adjacent valves to be closed to isolate a subsystem from the remainder of a network in case of a pipe failure is presented. An application to the water distribution system in Ottawa, Canada demonstrates the developed algorithm efficiently locates the adjacent valves for the isolation of a broken pipe.

• Journal of the Korean Institute of Gas
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• 제12권2호
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• pp.110-117
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• 2008

The risks of the chemical facilities were estimated by the KS-RBI(Ver. 3.0) program supporting the quantitative cause analysis, and reduction method for the risks of the facilities was investigated. As a result, we could find that the risks of the facilities decrease with reducing the likelihood of failure (LOF) affected by demage mechanism, inspection number and effectiveness of inspection, and with reducing the consequence of failure (COF) affected by the ratings of the detection, isolation, and mitigation systems. Furthermore, high risks of the facilities would be decreased by reduction of the LOF and the COF simultaneously. Accordingly, the applied plant would be able to achieve the decrease of inspection and labor costs because of the decrease of consequences and inspection intervals through the reduction of risks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제10권10호
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• pp.4902-4932
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• 2016

The popularity of network virtualization has recently regained considerable momentum because of the emergence of OpenFlow technology. It is essentially decouples a data plane from a control plane and promotes hardware programmability. Subsequently, OpenFlow facilitates the implementation of network virtualization. This study aims to provide an overview of different approaches to create a virtual network using OpenFlow technology. The paper also presents the OpenFlow components to compare conventional network architecture with OpenFlow network architecture, particularly in terms of the virtualization. A thematic OpenFlow network virtualization taxonomy is devised to categorize network virtualization approaches. Several testbeds that support OpenFlow network virtualization are discussed with case studies to show the capabilities of OpenFlow virtualization. Moreover, the advantages of popular OpenFlow controllers that are designed to enhance network virtualization is compared and analyzed. Finally, we present key research challenges that mainly focus on security, scalability, reliability, isolation, and monitoring in the OpenFlow virtual environment. Numerous potential directions to tackle the problems related to OpenFlow network virtualization are likewise discussed.

• Smart Structures and Systems
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• 제24권1호
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• pp.127-139
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• 2019

Residual drifts after an earthquake can incur huge repair costs and might need to replace the infrastructure because of its non-reparability. Proper functioning of bridges is also essential in the aftermath of an earthquake. In order to mitigate pounding and unseating damage of bridges subjected to earthquakes, a self-adaptive Ni-Ti shape memory alloy (SMA)-cable-based frictional sliding bearing (SMAFSB) is proposed considering self-adaptive centering, high energy dissipation, better fatigue, and corrosion resistance from SMA-cable component. The developed novel bearing is associated with the properties of modularity, replaceability, and earthquake isolation capacity, which could reduce the repair time and increase the resilience of highway bridges. To evaluate the super-elasticity of the SMA-cable, pseudo-static tests and numerical simulation on the SMA-cable specimens with a diameter of 7 mm are conducted and one dimensional (1D) constitutive hysteretic model of the SMAFSB is developed considering the effects of gap, self-centering, and high energy dissipation. Two types of the SMAFSB (i.e., movable and fixed SMAFSBs) are applied to a two-span continuous reinforced concrete (RC) bridge. The seismic vulnerabilities of the RC bridge, utilizing movable SMAFSB with the constant gap size of 60 mm and the fixed SMAFSBs with different gap sizes (e.g., 0, 30, and 60 mm), are assessed at component and system levels, respectively. It can be observed that the fixed SMAFSB with a gap of 30 mm gained the most retrofitting effect among the three cases.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권4호
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• pp.1502-1520
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• 2021

This paper attempts to investigate Korean youth Not in Education, Employment and Training (NEET) and how daily activities and community participation may influence their positive emotions and job search desire. First, we conducted a focus group interview with 16 NEETs who participated in the Kakao NEET Company project. The project allowed participants to experience employment by founding a virtual company in which each participant selected a daily activity to perform as part of the company's operations. Second, the interview responses were categorized and assigned emotional values using the card sorting technique and multi-dimensional analysis (MDS). A total of 11 emotional values were derived through this process. Finally, a social network analysis was conducted in order to measure the density of relations among the emotional values. Results suggest that immersion, confidence, belongingness were the three highest values evaluated by participants. Furthermore, network diagrams imply that the stronger participants perceived social support and belongingness with others, the stronger their responsibility grew, further leading them to establish steady goals. In particular, the high eigenvector score for "desire for job" suggests that emotional values are sequentially connected to the immersion-social support-responsibility-goal-job desire. This sequence suggests that digital services that are developed with the aim to enhance social values such as the Kakao NEET Project may engender motivation and confidence in youth NEETs. The overall results suggest that a systematic approach to policymaking should be considered in order to provide fundamental solutions and expand opportunities for social participation and emotional comfort, as social isolation due to low self-esteem has been reported as one of the reasons for NEETs' failure in the labor market.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제24권9호
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• pp.1165-1171
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• 2020

In this study, we designed a single antenna taking into account the performance, such as return loss and radiation pattern, of 28 GHz and 38 GHz array antennas for 5G mobile devices. In millimeter wave band communication, high path loss occurs between transmission and reception, unlike in conventional microwave bands. In the design of array antennas for 5G millimeter wave terminals, antenna performance such as antenna gain, bandwidth, isolation between antenna elements, side-lobe level(SLL), etc. should be further considered. The performance of the designed array antennas was analyzed by spacing the antenna elements at half a wavelength. Our results proved the validity of the design and its suitability for applications in mm-Wave by showing that the 28 GHz and 39 GHz array antennas had antenna gains of 13.5 dBi and 11.3 dBi and return losses below -18.4 dB and -20 dB, correspondingly.

• International Journal of Computer Science & Network Security
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• 제21권11호
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• pp.81-88
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• 2021

The presented scientific research substantiates the principles of the mechanism of the investment resources involvement in order to introduce innovations at enterprises in the context of digitalization using a resource-functional approach. The importance of attracting investment resources, which contributes to the modernization of production systems, the creation of a stable economic field of development of economic entities, is justified. The expediency of application of the resource-functional approach on research of the mechanism of attraction of investment resources for introduction of innovations at the enterprises in the conditions of digitalization is proved. The investment process is presented in the form of a chain of interdependent processes which include: attraction of investment resources, investments, increase of investment value, profit. It is proved that the mechanism of attracting investment resources for the introduction of innovations in enterprises in the context of digitalization cannot be considered in isolation from the process, due to the fact that the mechanism is aimed at performing specific functions. The functions of the mechanism include management, complex, coordination, monitoring, performance and control functions. Functions of the mechanism of attraction of investment resources for introduction of innovations at the enterprises in the conditions of digitalization are caused by the purposes of attraction of investment resources for innovative development; the presence of an objective nature; relative independence and homogeneity; implementation of functions in the process of investing in innovative activities of the enterprise.

• Journal of The Korea Institute of Healthcare Architecture
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• 제28권2호
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• pp.31-38
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• 2022

Purpose: This study presents the results of the analysis on space utilization of kidney dialysis units in regional public hospitals, which plays a key role in local public medical services. The result aims to achieve safety from infection, allow comfort for the dialysis environment, and stability for medical support. The purpose of this study is to present fundamental data for architectural plans for the kidney dialysis unit, as well as to alleviate potential infectious diseases such as COVID-19. Methods: For research purposes, the investigation and analysis of space utilization were based on architectural floor plans, research papers and literature, related legal systems, and public statistics. Of the main 35 regional public hospitals, in regards to data accessibility, 15 facilities were selected to conduct the survey and analysis for the objective. Results: The space composition by area research results of kidney dialysis units in public hospitals are as follows: Firstly, most targets do not have required rooms in the access and support area, except for the hemodialysis beds in the treatment section. Secondly, the access area requires necessary room and space design that took into consideration of convenience and accessibility for patients. Thirdly, in regards to infection prevention and control, proper circulation and room plan is essential for storage and disposal of contaminated products and linen after use. For the treatment area, the arrangement plan needs to establish a visual connection between the isolation room, the nursing station, and the bed area. Additionally, consideration of circulation in the preparation, treatment, observation, examination, and all other rooms in the facility is required. Lastly, for the support area, the room is designed to consider adequate working and meeting spaces for the medical staff, consultation space for patients or guardians, separate storage and disposal of clean and contaminated items, and the storage of various equipment for dialysis. Implications: In preparation for the increase in chronic kidney failure patients and the spread of infectious diseases, such as COVID-19, the researched data demonstrates the basic guidelines for space composition of kidney dialysis units and the significant role of regional public hospitals.

• KIPS Transactions on Computer and Communication Systems
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• 제11권1호
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• pp.9-22
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• 2022

Virtual Reality(VR) technology is an interface technology that is actively used in various audio-visual-based applications by showing users a virtual world composed of computer graphics. Since VR-based applications are graphic processing-based applications, expensive computing devices equipped with Graphics Processing Unit(GPU) are essential for graphic processing. This incurs a cost burden on VR application users for maintaining and managing computing devices, and as one of the solutions to this, a method of operating services in cloud environments is being used. This paper proposes a performance management technique to address the problem of performance interference between containers owing to GPU resource competition in container-based high-performance cloud environments in which multiple containers share a single GPU. The proposed technique reduces performance deviation due to performance interference, helping provide uniform performance-based remote VR services for users. In addition, this paper verifies the efficiency of the proposed technique through experiments.

• Korea Journal of Hospital Management
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• 제27권3호
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• pp.26-38
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• 2022

Purposes: We analyzed the profitability determinants of regional public hospitals during the entire period between 2010 and 2020 and the period before and after COVID-19. We intended to provide fundamental data for developing publicness evaluation index and task of establishing and expanding regional public hospitals. Methodology: The financial and non-financial information of the regional public hospitals were used as the main analysis data; The financial data was established by the Center for Public Healthcare Policy of National Medical Center, and the non-financial data by the Health Insurance Review and Assessment Service. T-test and regression analysis were used. Findings: The results can be summarized in two. First, the main determinants of profitability of the regional public hospitals were appeared to be the total asset turnover rate and the labor cost rate. Second, during the COVID-19 pandemic in the regional public hospitals, the number of sickbeds, the number of isolation rooms, the total asset turnover rate and the labor cost rate appeared to be the factor worsening the profitability. Practical Implication: The results of this study suggests that the management of the regional public hospitals is not aiming for the profit making, but it performs the functions as the community healthcare safety net such as controlling infectious diseases.