• Management & Information Systems Review
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• v.24
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• pp.97-124
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• 2008

This study aimed to explore how the involvement of environment influenced eight subjects group. Thus, experiment was performed to clarify the role that the attitude of university student consumer plays in the communication process depending on the level of engagement of consumer in the environment and method to raise donation for preservation of environment. Analyzing as per the type of appeal, the mark in altruistic appeal type was higher in all variables than egoistic appeal type. Finally, checking the average mark of each variable as per the condition of donation, the value in unconditional donation was higher than in all variables than conditional donation. It was found 3 groups composed of 2 groups with high level of environmental engagement and 1 group with low level of environmental engagement were suitable to double mediation model among the 8 experimental groups. The group where double mediation model best corresponds than any other group was high level related to environment and the group that contacts altruistic appeal and the message in the form of conditional donation. It was also found that the group that has low level of environmental engagement and contacts egoistic appeal type and conditional donation shows the group that corresponds to double mediation model in the second place among the 8 groups. Finally, it was found that the group that has high level of environmental engagement and is stimulated by altruistic appeal and unconditional donation corresponds to double mediation model. Depending on the condition of message stimulation, unconditional donation is found to better correspond to double mediation model than conditional donation. However, opposite phenomena is observed when the level of environmental engagement is high and appeal type is egoistic. Namely, it was found that conditional donation better corresponds to double mediation model than unconditional donation.

• IE interfaces
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• v.18 no.4
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• pp.444-453
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• 2005

The purpose of the Gage R&R study is to determine whether a measurement system is adequate for monitoring a process. If the measurement system variation is small relative to the process variation, then the measurement system is deemed "adequate". The sources of variation associated with the measurement system are compared using an analysis of variance (ANOVA) model, in general. A typical ANOVA model used in a standard Gage R&R study is the two-factor random effect model. Then, the ANOVA partitions the total variation into three categories: repeatability, reproducibility, part variation. However, if the process variation possesses the between group variation, within group variation, and within part variation, these variations can cause the measurement system evaluation to provide misleading results. That is, in the standard Gage R&R study these variations affect the estimate of repeatability, reproducibility, or both. This paper presents a four-factor nested factorial ANOVA model which explicitly considers these variations for the Gage R&R study. The variance component estimators are derived by setting the EMS equations equal to the corresponding mean square from the ANOVA table and solving. And the proposed model is compared with the standard Gage R&R model.

• Journal of The Korean Association For Science Education
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• v.14 no.3
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• pp.293-303
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• 1994

The purpose of this study was to find the effect of molecular movement model based instruction on high school students' conceptions of diffusion and osmosis. The study was composed of two groups, the traditional instruction group in which the so-called traditional instruction was performed, and the other group in which interventions by researchers were made. The subjects of the traditional instruction group consisted of a total of 242 high school students from Seoul, Gwangju and Mokpo. The subjects of the model based instruction group consisted of 177 first-year high school students in Mokpo. The study was focused on the use of the term of 'molecular movement' in their explanation of diffusion and osmosis in the correct contexts. In general, students who got the molecular movement model based instruction showed more frequent use of the terms of 'molecular movement' in the correct contexts than the control group students did. It was found that misconceptions including teleological explanations changed into scientific explanations by the intervention. It seemed that the molecular movement model led students to make scientific explanations on natural phenomena. A further research is recommended to assess the improvement of teleological explanation and scientific attitude by the molecular movement model.

• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.501-511
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• 2002

This paper presents a study of the effect of rolling temperature, roll gap (pass height), initial specimen size and steel grades of specimens on the roll force in round-oval-round pass sequence by applying approximate method and verifications through single stand pilot rod rolling tests. The results show that the predicted roll forces are in good agreement with the experimentally measured ones. The approximate model is independent of the change of roll gap, specimen size and temperature. Thus, the generality of the prediction methodology employed in the approximate model is proven. This study also demonstrates that Shida's constitutive equation employed in the approximate model needs to be corrected somehow to be applicable for the medium and high carbon steels in a lower temperature interval (700∼900$\^{C}$).

• Korean Management Science Review
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• v.26 no.2
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• pp.19-35
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• 2009

This paper investigated performance of the Markowitz's portfolio selection model with applications to Korean stock market. We chose Samsung-Group-Funds and KOSPI index for performance comparison with the Markowitz's portfolio selection model. For the most recent one and a half year period between March 2007 and September 2008, KOSPI index almost remained the same with only 0.1% change, Samsung-Group-Funds showed 20.54% return, and Markowitz's model, which is composed of the same 17 Samsung group stocks, achieved 52% return. We performed sensitivity analysis on the duration of financial data and the frequency of portfolio change in order to maximize the return of portfolio. In conclusion, according to our empirical research results with Samsung-Group-Funds, investment by Markowitz's model, which periodically changes portfolio by using nonlinear programming with only financial data, outperformed investment by the fund managers who possess rich experiences on stock trading and actively change portfolio by the minute-by-minute market news and business information.

• Journal of Korean Elementary Science Education
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• v.23 no.2
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• pp.116-122
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• 2004

The purpose of this study is to investigate effects of computer animations using particulate model in elementary science classes related to air pressure. To do those, four classes of 5th grade in an elementary school located in a city were selected. As an experiment group, two classes were applied the teaching materials of computer animations developed for this study based on particulate model. The other classes as a control group were not applied these materials in science classes. The total scores of experiment group in which computer animation using particulate model was applied in science classes are higher than those of the control group in the conception test. Only in one conception related to high and low atmospheric air pressure, the scores of the two groups are not significantly different at 0.05 significance level.

• Journal of international Conference on Electrical Machines and Systems
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• v.3 no.1
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• pp.78-82
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• 2014

Power Transformers with more than one secondary winding are not uncommon in industrial applications. But new classes of applications where very large number of independent secondaries are used are becoming popular in controlled converters for medium and high voltage applications. Cascade H-bridge medium voltage drives and Pulse Step Modulation (PSM) based high voltage power supplies are such applications. Regulated high voltage power supplies (Fig. 1) with 35-100 kV, 5-10 MW output range with very fast dynamics (${\mu}S$ order) uses such transformers. Such power supplies are widely used in fusion research. Here series connection of isolated voltage sources with conventional switching semiconductor devices is achieved by large number of separate transformers or by single unit of multi-secondary transformer. Naturally, a transformer having numbers of secondary windings (~40) on single core is the preferred solution due to space and cost considerations. For design and simulation analysis of such a power supply, the model of a multi-secondary transformer poses special problem to any circuit analysis software as many simulation softwares provide transformer models with limited number (3-6) of secondary windings. Multi-Secondary transformer models with 3 different schemes are available. A comparison of test results from a practical Multi-secondary transformer with a simulation model using magnetic component is found to describe the behavior closer to observed test results. Earlier models assumed magnetising inductance in a linear loss less core model although in actual it is saturable core made-up of CRGO steel laminations. This article discusses a more detailed representation of flux coupled magnetic model with saturable core properties to simulate actual transformers very close to its observed parameters in test and actual usage.

• Restorative Dentistry and Endodontics
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• v.25 no.2
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• pp.235-242
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• 2000

The purpose of this in vitro study was to evaluate the sealing ability of three sealers(Sealapex, Pulp canal sealer, AH26) used with continuous wave method using an anaerobic bacterial leakage model. 53 extracted human teeth with straight and single canals were prepared with crown-down pressureless technique using .04, .06 taper Profile(Maillefer, Swiss). Master apical file was maintained as #35 K-file. All canals of the experimental teeth were obturated with continuous wave method using System B(Analytic technology, U.S.A.) The teeth were randomly divided into three experimental groups of 15 and two control groups of 4. Experimental group 1 was obturated with Sealapex and group 2 with Pulp canal sealer, and group 3 with AH26. A dual chamber anaerobic bacterial leakage model was assembled. Brain heart infusion with yeast extract, hemin, menadion, and the chromogenic indicator bromocresol purple was used as the culture broth for Fusobacterium nucleatum(VPI 10197), The specimens were incubated in anaerobic chamber at $37^{\circ}C$ and were observed every 2 to 3 clays, The coronal leakage was evaluated through the color change of culture broth in lower chamber for 60 days. The results were as follows: 1. The incidence of bacterial leakage in group 1 (Sealapex group was 80%, 53% in group 2 (Pulp canal sealer), 27% in group 3 (AH26). 2. There were statistically significant differences in leakage scores between group 1 and group 2, and between group 1 and group 3, respectively. (P<0.05) 3. There was no significantly difference in leakage score between group 2 and group 3. (P>0 05)

• Journal of the Korean Society of Radiology
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• v.15 no.5
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• pp.643-647
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• 2021

The purpose of this study was to access the possibility and ideal model for corrosive-induced tissue hyperplasia in the rat esophagus. Twenty rat were divided into two group: a healthy group, corrosive group. corrosive burn in esophagus were produced using 30% NaOH on the distal esophagus. After surgical procedure, behavioral and weight changes were monitored on a weekly. At 3 weeks after surgical procedure, fluoroscopic esophagogram was performed and then all rats sacrificed for histological analysis by administering inhalable pure carbon dioxide. Technical surgery for corrosive stricture were 100%. A total of 2 rats died in corrosive group from a corrosive burn related to dysphagia within 14 days. The esophageal stenosis ratio was significantly higher in the corrosive group than in the healthy group (40.1 ± 9.2 % and 1.4 ± 7.2%, respectively; p = 0.001). The tissue hyperplasia ratio was also significantly higher in the Corrosive group (62.5 ± 9% and 22.08 ± 6%, respectively; p = 0.001). Infusion of 30% NaOH may suggest alternative option to evaluation tool for preclinical study in a rat corrosive model.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.03a
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• pp.1077-1087
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• 2010

Generally most of pile foundations are constructed with group pile rather than single pile. The study on efficiency and bearing capacity which are major elements for rational design of this group pile has been actively progressed, whereas there are truly only a few studies of negative skin friction working on group pile due to the consolidation of ground. The purpose of this study is to determine, among the elements of negative skin friction applied to pile, the occurrence modality of negative skin friction at center, side, and corner of $3{\times}3$ group pile using model test and, based on those observations, to propose the effective design direction of group pile.