• Progress in Medical Physics
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• v.15 no.4
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• pp.186-191
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• 2004

The periodic Quality Assurance (QA) of each radiation treatment related equipments is important one, but quality assurance of the radiation treatment planning system (RTPS) is still not sufficient rather than other related equipments in clinics. Therefore, this study will present and test the periodic QA program to compare, evaluation the efficiency of the treatment planning systems. This QA program is divided to terms for the input, output devices and dosimetric data and categorized to the weekly, monthly, yearly and non-periodically with respect to the job time, frequency of error, priority of importance. CT images of the water equivalent solid phantom with a heterogeneity condition are input into the RTPS to proceed the test. The actual measurement data are obtained by using the ion chamber for the 6 MV, 10 MV photon beam, then compared a calculation data with a measurement data to evaluate the accuracy of the RTPS. Most of results for the accuracy of geometry and beam data are agreed within the error criteria which is recommended from the various advanced country and related societies. This result can be applied to the periodic QA program to improve the treatment outcome as a proper model in Korea and used to evaluate the accuracy of the RTPS.

• Journal of Korean Home Economics Education Association
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• v.31 no.1
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• pp.39-58
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• 2019

The purpose of this study was to investigate the home economics pre-service teachers' verbal interactions during their teaching practicum. For this purpose, the class interactions of four pre-service teachers were recorded, and the data were analyzed using advanced Flanders' verbal interaction analysis. The major findings are as follows: First, the item with the highest proportion of occurrences consisted of the pre-service teachers' 'lectures', 'nonverbal conditions' and 'asks questions'. 'forms a positive learning atmosphere' and 'praises or encourages' exhibited fewer occurrences, and there was little 'giving direction', 'criticizing students or justifying authority'. Second, the instances of class interactions appeared in the form of 'asks questions-student talk response' or 'lecture-asks questions', and in the last class were 'ask questions-student talk initiation' and 'accepts or uses ideas of students'. Third, trends of verbal interactions tend to be generally indirect, and students' remarks have appeared acceptable and compassionate. Fourth, according to expert analysis, 'class management questions' and 'diffusion questions' have increased. Pre-service teachers can guide students through their learning activities, and students can expand their thinking through the teachers' questions. As these results demonstrate, self-study analyses of pre-service teachers and active support in field are needed.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.31 no.2
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• pp.223-266
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• 2020

Massively Multiplayer Online Role-Playing Games (MMORPGs) are played by millions of people around the world. Within MMORPGs, players explore, solve mysteries, craft items, battle against dungeon or raid bosses, or compete against other players, all while using a variety of information and information behaviors. Role-players in MMORPGs develop identities and engage in interactive storytelling with other role-players as their characters. An ethnographic approach combining overt participant observation and engagement, semi-structured interviews, and artifact collection was used to explore and describe the social information behaviors of role-players through the lens of the theory of information worlds. The social types evident in the role-playing community in WildStar, a science fantasy-themed MMORPG, are closely interrelated to and differentiated by social norms and information values that dictate acceptable characters, stories, character actions, and appropriate lore sources as well as how to role-play without violating the boundary between in- and out-of-character information worlds. Role-players maintained the in-character and out-of-character boundary using a set of specific information behaviors to enable engaging and immersive role-playing experiences. Implications of the findings for the theory of information worlds as well as potential applications of role-playing and MMORPGs are also discussed.

• Journal of KIISE:Databases
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• v.28 no.3
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• pp.484-493
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• 2001

As real-time database systems are extended to the distributed computing environment, the need to apply the existing real-time concurrency control schemes to the distributed computing environment has been made. In this paper we propose an efficient concurrency control scheme for distributed real-time database system. Our proposed scheme guarantees a transaction to commit at its maximum, reduces the restart of a transaction that is on the prepared commit phase, and minimizes the time of the lock holding. This is because it raises the priority of the transaction that is on the prepared commit phase in the distributed real-time computing environment. In addition, it reduces the waiting time of a transaction that owns borrowed data and improves the performance of the system, as a result of lending the data that the transaction with the raised priority holds. We compare the proposed scheme with DO2PL_PA(Distributed Optimistic Two-Phase Locking) and MIRROR(Managing Isolation in Replicated Real-time Object Repositories) protocol in terms of the arrival rate of transactions, the size of transactions, the write probability of transactions, and the replication degree of data in a firm-deadline real-time database system based on two-phase commit protocol. It is shown through the performance evaluation that our scheme outperforms the existing schemes.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.7 no.1
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• pp.75-90
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• 1995

A mathematical model for the dynamic analysis of a riser system with the inclusion of internal flow and nonlinear effects due to large structural displacements is developed to investigate the effect of internal flow on marine riser dynamics. The riser system accounts fir the nonlinear boundary conditions and includes a steady flow inside the pipe which is modeled as an extensible or inextensible. tubular beam subject to nonlinear three dimensional hydrodynamic loads such as current or wave excitation. Galerkin's finite element approximation and time incremental operator are implemented to derive the matrix equation of equilibrium for the finite element system and the extensibility or inextensibility condition is used to reduce degree of freedom of the system and the required computational time in the case of a nonlinear model. The algorithm is implemented to develop computer programs used in several numerical applications. The investigations of the effect of infernal flow on riser vibration due to current or wave loading are performed according to the change of various parameters such as top tension, internal flow velocity, current velocity, wave period, and so on. It is found that the effect of internal flow can be controlled by the increase of top tension. However, careful consideration has to be given in the design point particularly for the long riser under the harmonic loading such as waves. And it is also found that the consideration of nonlinear effects due to large structural displacements increases the effect of internal flow on riser dynamics.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.9-14
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• 2009

In this research, a polyester manufacturing company (i.e. K Co.) in Gumi, South Korea was investigated regarding the release of high concentrations of 1,4-dioxane(about 600 mg/L) and whether treatment prior to release should occur to meet with the level of the regulation standard (e.g., 5 mg/L in 2011). The pilot-scale (reactor volume, 10 $m^3$) treatment system using Photo-Fenton Oxidation was able to remove approximately 90% of 1,4-dioxane under the conditions that concentrations of 2,800 ppm $H_2O_2$ and 1,400 ppm $FeSO_4$ were maintained along with 10 UV-C lamps (240 ${\mu}W/cm^2$) illuminated during aeration. However, the effluent concentration of 1,4-dioxane was still high at about 60 mg/L. Thus, further investigation is needed to see whether the bench scale (reactor volume, 8.9 L) of activated sludge could facilitate the decomposition of 1,4-dioxane. As a result, 1,4-dioxane in the effluent has been decreased as low as about 2~3 mg/L. Consequently, Photo-Fenton Oxidation coupled with activated sludge process can make it possible to efficiently decompose 1,4-dioxane to keep up with that of the regulation standard.

• Journal of Korean Society of Steel Construction
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• v.23 no.2
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• pp.199-210
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• 2011

The cables in cable-stayed bridges are under high stress and are very sensitive to vibration due to their small section areas compared with other members. Therefore, it is reasonable to evaluate the cable impact factor by taking into account the dynamic effect due to moving-vehicle motion. In this study, the cable impact factors were evaluated via moving-vehicle-load analysis, considering the design parameters, i.e., vehicle weight, cable model, road surface roughness, vehicle speed, longitudinal distance between vehicles. For this purpose, two steel composite cable-stayed bridges with 230- and 540-m main spans were selected. The results of the analysis were then compared with those of the influence line method that is currently being used in design practice. The road surface roughness was randomly generated based on ISO 8608, and the convergence of impact factors according to the number of generated road surfaces was evaluated to improve the reliability of the results. A9-d.o.f. tractor-trailer vehicle was used, and the vehicle motion was derived from Lagrange's equation. 3D finite element models for the selected cable-stayed bridges were constructed with truss elements having equivalent moduli for the cables, and with beam elements for the girders and the pylons. The direct integration method was used for the analysis of the bridge-vehicle interaction, and the analysis was conducted iteratively until the displacement error rate of the bridge was within the specified tolerance. It was acknowledged that the influence line method, which cannot consider the dynamic effect due to moving-vehicle motion, could underestimate the impact factors of the end-cables at the side spans, unlike moving-vehicle-load analysis.

• Journal of the Korean Society of Radiology
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• v.7 no.4
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• pp.307-311
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• 2013

This study examined the change of artifact volume by analyzing the level of image change associated with the setting of threshold through 3D imaging in scan parameter(slice thickness and helical pitch) and 3D image reconstruction to explore whether the presence of pathology was fully distinguished when CT was taken by lower dose than the existent dose to reduce exposure. Furthermore, this study attempted to investigate Scan Parameter acceptable in CT to reduce exposure dose. For materials and methods, silicon was used to produce samples. Five spherical samples were produced at 10-millimeter intervals(50, 40, 30, 20, and 10 mm) in diameter and were fixed at 120 Kvp of tube voltage and 50 mA of tube current. Varied slab thickness((1.0, 2.0, 3.0, 5.0, and 7.0mm) and Helical Pitch(1.5, 2.0, 3.0) were scanned. The image at an interval of 1.0, 2.0, 3.0, 5.0, and 7.0mm was transmitted to the workstation. Threshold(-200, -50, 50 ~ 1,000) was changed using the volume rendering technique, 3D image was reconstructed, and artifact volume was measured. In conclusion, 1.5 of Helical Pitch showed the least change of volume and 3.0 of helical pitch showed the greatest reduction of volume change. The experiment suggested that as slice thickness was increased, artifact volume was decreased more than actual measurement. Furthermore, in the 3D image reconstruction, when the range of threshold was set as -200 ~1,000, artifact volume was changed the least. Based on the results, it is expected to have an effect of reducing exposure dose.

• Journal of Korean Philosophical Society
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• v.147
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• pp.261-281
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• 2018

This paper will cover recent discussions on the risks of human being due to the development of artificial intelligence(AI). We will consider AI research as artificial narrow intelligence(ANI), artificial general intelligence(AGI), and artificial super intelligence(ASI). First, we examine the risks of ANI, or weak AI systems. To maximize efficiency, humans will use autonomous AI extensively. At this time, we can predict the risks that can arise by transferring a great deal of authority to autonomous AI and AI's judging and acting without human intervention. Even a sophisticated system, human-made artificial intelligence systems are incomplete, and virus infections or bugs can cause errors. So I think there should be a limit to what I entrust to artificial intelligence. Typically, we do not believe that lethal autonomous weapons systems should be allowed. Strong AI researchers are optimistic about the emergence of artificial general intelligence(AGI) and artificial superintelligence(ASI). Superintelligence is an AI system that surpasses human ability in all respects, so it may act against human interests or harm human beings. So the problem of controlling superintelligence, i.e. control problem is being seriously considered. In this paper, we have outlined how to control superintelligence based on the proposed control schemes. If superintelligence emerges, it is judged that there is no way for humans to completely control superintelligence at this time. But the emergence of superintelligence may be a fictitious assumption. Even in this case, research on control problems is of practical value in setting the direction of future AI research.

• Korean Journal of Social Welfare Studies
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• v.43 no.1
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• pp.203-227
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• 2012

This study analyzes the effect on depression of mutual relational aggression experienced by elderly residents at charity nursing home. It also verifies the mediated effect of adaption by the residents to the nursing home. For this end, the researchers conduct a survey for 182 elderly residents in 7 charity nursing homes in Seoul and Kyonggi Province. The statistical methods for the analysis were SPSS version 18.0 and AMOS 7.0program. Following are the findings. First, there turns out to be no statistical significant effect between mutual relational aggression and depression. Second, elderly residents' adaption to the nursing home is proved to serve as a mediated effect between mutual relational aggression and depression. In other words, the more the relational aggression, the more difficult it is for residents to be adapted to the nursing home, and the more depressed the residents are prone to be. Following are suggestions based on the findings. First, nursing home staffs need to establish a system in consideration both of relational aggression and of resident's adaption, to reduce its elderly residents' consequential depression. Second, nursing home staffs need to take measures to help adaption of new residents to prevent or reduce their depression. For example, new residents can be allowed to bring their belongings to the nursing home as much as they want and the nursing home can stand. Third, nursing homes also need to develop programs to prevent or reduce any negative relation, including bullying or casting out, among peer residents in the nursing home.