• KIPS Transactions on Computer and Communication Systems
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• v.9 no.4
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• pp.77-82
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• 2020

Wireless sensor networks (WSNs) suffer from not only a short lifetime due to limited energy but also an energy imbalance between nodes close to the sink and others. In order to fundamentally solve the short lifetime, recent studies utilize the environmental energy such as solar power. Additionally, WSNs using mobile sinks are being studied to address the energy imbalance problem. This paper proposes an improved CTP (Collection Tree Protocol) scheme which uses these two approaches simultaneously. Basically, it is based on a CTP scheme which is a very popular data collection strategy designed for the typical battery-based WSNs with a fixed sink. Therefore, we tailored it for solar-powered WSNs with a mobile sink. Performance verification confirms that our scheme reduces the number of blackout nodes significantly compared to the typical CTP, thus increases the amount of data collected by the sink.

• Journal of Digital Contents Society
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• v.9 no.2
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• pp.193-202
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• 2008

This paper is a research of job search plan of polytech college based on SEM. We did a through research of factors on the motivation of job seeking and those of job search scheme which are independent variables. We also verified the effects of factors of stable job composition, job seeking surroundings and job selection which are dependent variables. Hence we conducted a survey among polytech college students, studying relationship between factors of dependent variable and independent one. We also analyzed whether motivation of career seeking affects job search plot by utilizing SEM based on AMOS 5.0. The consequence of the research is that stable job and job selection factor were rejected, for they do not highly affect motivation of job seeking. And the factors of job seeking environment (establishment of collaboration between businesses and colleges, hands-on guidance at workplace and the guidance for enhancement of vocational capability), which are dependent variables, were chosen because they are the affirmative factors of motivation of job seeking. After all, they are the crucial factors of job search plan.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.9
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• pp.17-23
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• 2009

Interest in application of ultraviolet light technology for primary disinfection of potable water in drinking water treatment plants has increased significantly in recent years. The efficacy of disinfection processes in water purification systems is governed by several key factors, including reactor hydraulics, disinfectant chemistry, and microbial inactivation kinetics. The objective of this work was to develop a computational fluid dynamics(CFD) model to predict velocity fields, mass transport, chlorine decay, and microbial inactivation in a continuous flow reactor. The CFD model was also used to evaluate disinfection efficiency in alternative reactor designs. In a typical operation, water enters the inlet of a UV lamp and flows through the annular space between the quartz sleeve and the outside chamber wall. The irradiated water leaves through the outlet nozzle. In this paper, it describe the how to design optimal ultraviolet disinfection device for ground water and rainwater. To search the optimal design method, it was performed computer simulation with 3D-CFD discrete ordinates model and manufactured prototype. Using proposed design method, performed simulation and proved satisfied performance.

• Magazine of the Korea Concrete Institute
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• v.7 no.3
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• pp.175-186
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• 1995

The determination of the stress intensity factors is investigated by sur-face integral method around the crack tip of the nlass~vc: concrete structure. The surface integral met hod is naturally derived from the standal-ci path integral J. Howevcr. In the J integral method, pressure in the crack-face and body forces can not be considered, while this theory has advantage of ccmsidering many kind of forces, so t.his theory will be useful in investigating more accurate strt:ss states around crack tip. Furthermore. t h~s rrlethod can elerninate unntussary process of using singular elements and fine mesh around crack tip which is used 11; modelling the singularity around crack tip. A computer program for determming $K_I$, $K_{II}$ is tfcvulopcd by applying this theory. $K_I$, $K_{II}$ values usmg X noded isoparametric elements which was proved and variation of the stress intensity factor was investigated by application of darn structures.

• Journal of Radiation Protection and Research
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• v.32 no.4
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• pp.158-167
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• 2007

It is required that the neutron dosimetry be present to monitor the reactor vessel throughout its plant life. The Ex-vessel Neutron Dosimetry Systems which consist of sensor sets, radiometric monitors, gradient chains, and support hardware have been installed for 3-Loop plants after a complete withdrawal of all six in-vessel surveillance capsules. The systems have been installed in the reactor cavity annulus in order to characterize the neutron energy spectrum over the beltline region of the reactor vessel. The installed dosimetry were withdrawn and evaluated after a irradiation during one cycle and then compared to the cycle specific neutron transport calculations. The reaction rates from the measurement and calculation were compared and the results show good agreements each other.

• Journal of Venture Innovation
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• v.1 no.2
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• pp.75-87
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• 2018

We designed this study for verifying the differences of causes and individual results of job stress between Koreans in Korea and Chinese in China of a same company. The results in the study are as follow. Significant differences between two groups were identified in job stressors: Koreans showed higher levels than Chinese for factors like inter-group conflicts, supervision/evaluation, job overload, task characteristics, socio-demographic factors, and Chinese showed higher levels than Koreans for factors like job conflicts, job ambiguity, family-related factors. We also identified that levels of stress perceived by individuals as anxiety, depression, and physical symptoms of Koreans are higher than those of Chinese. As to the influence of job stressors on stress level, Koreans show significant results for supervision/evaluation, decision making/responsibility, family-related factors, and Chinese show significant results for family-related factors, social support, socio-demographic factors. Based on the results of this study, implications, limitations, and future research topics were discussed.

• Journal of the Korea Institute of Building Construction
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• v.17 no.4
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• pp.369-375
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• 2017

This study suggests PSO(Particle Swarm Optimization) algorithm that optimizes the snowplow route allocation and the location of the snow control material storage to improve the efficiency in snow removal works. The modified PSO algorithm for improving the search capacity is proposed, and this study suggests the solution representation, the parameter setting, and the fitness function for the given optimization problems. Computational experiments in real-world case are carried out to justify the proposed method and compared with the traditional PSO algorithms. The results show that the proposed algorithms can find the better solution than the traditional PSO algorithms by searching for the wider solution space without falling into the local optima. The finding of this study is efficiently employed to solve the optimization of the snowplow route allocation by minimizing the workload of each snowplow to search the location of the snow control material storage as well.

• Journal of Internet Computing and Services
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• v.17 no.4
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• pp.69-77
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• 2016

Recently, the importance of visual analytics has been recognized in the field of business intelligence. From the view of business intelligence, visual analytics aims for acquiring valuable insights for decision making by interactively visualizing a variety of business information. In this paper, we propose a treemap-based method for visualizing work-sharing relationships among business process performers. A work-sharing relationship is established between two performers who jointly participate in a specific activity of a business process and is an important factor for understanding organizational structures and behaviors in a process-centric organization. To this end, we design and implement a treemap-based visualization tool for representing work-sharing relationships as well as basic hierarchical information in business processes. Finally, we evaluate usefulness of the proposed visualization tool through an operational example using XPDL (XML Process Definition Language) process models.

• Information Systems Review
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• v.8 no.1
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• pp.265-285
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• 2006

The purpose of this research is to identify the major evaluation criteria of IT investment projects and establish the importance weights of criteria through AHP analysis. Seven evaluation criteria which have been drawn from prior studies and industry practices are direct costs, indirect costs, financial benefits, strategic value, risk, technical necessity, and political considerations. Data have been collected from 95 IT projects in 40 public organizations and private firms in Korea. After having applied the data reliability test, 79 projects have been selected. The results of AHP analysis show the importance weights and priorities of seven evaluation criteria as follows: financial benefits 25.2%, strategic value 22.36%, direct costs 14.34%, risk 12.10%, technical necessity 11.55%, political considerations 8.3%, and indirect costs 6.48%. And the weights of seven criteria shows considerable differences among three different IT project types such as transactional, informational, and infrastructural.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.6
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• pp.463-472
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• 2017

Inertial Navigation System Alignment is the process to determine direction cosine matrix which is the transformation matrix between the INS body frame and navigation frame. INS initial position value is necessary to INS attitude calculation, so that user should wait until he get such value to start the INS alignment. To remove the waiting time, we propose an alignment algorithm that immediately starts after the INS power on by using pseudo initial position input and then is completed with attitude error compensation by entering true position later. We analyse effect of INS sensor error on attitude in process of time and verify the performance and usefulness of the close-loop alignment algorithm which corrects attitude error from the change of initial position.