• Nuclear Engineering and Technology
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• v.51 no.3
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• pp.692-701
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• 2019

Recently, instrumentation and control (I&C) systems in nuclear power plants have undergone digitalization. Owing to the unique characteristics of digital I&C systems, the reliability analysis of digital systems has become an important element of probabilistic safety assessment (PSA). In a reliability analysis of digital systems, fault-tolerant techniques and their effectiveness must be considered. A fault injection experiment was performed on a safety-critical digital I&C system developed for nuclear power plants to evaluate the effectiveness of fault-tolerant techniques implemented in the target system. A software-implemented fault injection in which faults were injected into the memory area was used based on the assumption that all faults in the target system will be reflected in the faults in the memory. To reduce the number of required fault injection experiments, the memory assigned to the target software was analyzed. In addition, to observe the effect of the fault detection coverage of fault-tolerant techniques, a PSA model was developed. The analysis of the experimental result also can be used to identify weak points of fault-tolerant techniques for capability improvement of fault-tolerant techniques

• International Journal of Korean Welding Society
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• v.4 no.1
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• pp.38-45
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• 2004

A practical method for evaluating the possibility of the occurrence of cracking in actual thick-plate T-joint weldments is presented in this study. Systematic experitrients based on the method of the design of experiment are conducted in order to investigate the crack tendency in relation to typical welding parameters such as diffusible hydrogen, restraint intensity, preheating temperature and so on. The elastic analysis using the fmite element techniques is employed to quantify the restraint intensities of the specimens. The defined restraint intensities are treated in numerical way for the sake of considering the most uncertain factor among some major factors that govern the cracking phenomena due to welding. The critical plane for judgment of the crack occurrence or crack density is presented as a function of typical welding parameters including determined restraint intensities. The results of numerical estimation by the proposed method for the experimental specimens show the usefulness as a practical tool in welding induced crack problem having extensive uncertainties.

• Proceedings of the Korea Information Processing Society Conference
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• 2021.11a
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• pp.805-807
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• 2021

In-hospital cardiac arrest is a significant problem for medical systems. Although the traditional early warning systems have been widely applied, they still contain many drawbacks, such as the high false warning rate and low sensitivity. This paper proposed a strategy that involves a deep learning approach based on a novel interpretable deep tabular data learning architecture, named TabNet, for the Rapid Response System. This study has been processed and validated on a dataset collected from two hospitals of Chonnam National University, Korea, in over 10 years. The learning metrics used for the experiment are the area under the receiver operating characteristic curve score (AUROC) and the area under the precision-recall curve score (AUPRC). The experiment on a large real-time dataset shows that our method improves compared to other machine learning-based approaches.

• Journal of Korean Home Economics Education Association
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• v.16 no.1
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• pp.63-77
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• 2004

The purpose of this study was to construct an issue-centered discussion instructional model for Home Economics and to determine its effect on middle school students' critical thinking. The research questions were posed as below. 1) The object and content of home economics in the 7th national middle school curricula are analyzed to sort out possible issues. 2) An issue-centered discussion instructional model is constructed to be applicable to middle school home economics class. and a lesson plan is prepared. 3) The effect of the issue-centered discussion instructional model developed in this study on student critical thinking faculty is examined. The findings of this study were as follows : First. seven criteria were selected to determine what types of issues were applicable to home economics lesson. Based on the selected criteria. 41 themes of issues were extracted from the 7th middle school textbooks. and their content validity was verified. Second, an issue-centered discussion instructional model was designed to deal with four themes in eight sessions in the procedure of problem raising, confirming, term defining. tentative alternative selecting, data gathering. discussing/critical approaching. and selecting/concluding. Third, two different third-year classes of K middle school in the city of Busan that consisted of 75 students were respectively selected as an experimental group and a control group, and the experiment was conducted in eight sessions for five weeks to see whether the teaching plan brought any changes to the critical mind of the students. The experimental group exposed to the issue-centered discussion lesson made a significant progress in critical thinking faculty(P＜.05). In particular. that instruction gave a favorable impact on demonstration evaluating(P＜.05). one of the critical thinking subfactors. When the students were asked to assess the issue-centered discussion lesson. most of them viewed it favorably. In the future, more research efforts should be dedicated to enhancing the practical applicability of issue-centered discussion instruction in home economics education. developing good evaluation tools about critical thinking faculty and finding out how discussion instruction could be conducted more efficiently.

• Journal of The Korean Society of Grassland and Forage Science
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• v.5 no.1
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• pp.33-36
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• 1985

This experiment was carried out to investigate the effect of crown density of trees on the growth and yield of cool-season grasses in forest. The species used in this study was orchard-grass (Dactylis glomerata L.) and 4 levels of tree crown density(O=full sunlight, 25, 50 and 75%) were treated. The experiment was performed at the experimental filed of the Livestock Experiment Station in Suweon, during 1979 to 1950. The results obtained are summarized as follows: 1. Maximum leaf area was obtained at 25% crown density of trees, followed by 0, 50 and 75%, regardless of cutting times. 2. Plant height tended to increase as the crown density of trees increased. However, there was no difference between 0% and 25% crown density of trees. 3. There was a negative correlation between plant height and leaf area of orchardgrass grown under pine trees. 4. The more dry matter yield of orchardgrass was obtained at 25% crown density of trees (p<0.05), follwed by 0, 50 and 75%, respectively. However, there was no significant difference between 0% and 50% crown density of trees. Therefore it is suggested that the critical level of crown density of trees is 50% to culture of cool-season grasses in forest.

• Environmental and Resource Economics Review
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• v.17 no.4
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• pp.875-901
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• 2008

This article estimates the economic values of changes in water quality of the Paldang Watershed by using the Choice Experiment (CE). The conditional logit model estimation results show that a small improvement in water quality from the 'status quo' level to the level of 'very good' increases average household's monthly utility by 3,157 Won, whereas a water quality degradation down to the 'normal' level gives rise to an increase in the monthly average utility by 9,649 Won. The corresponding social gain and loss of water quality changes to the Metropolitan Area were thus estimated about 285 billion Won and 872 billion Won, respectively. This article seems meaningful in that it resorts to the new water ecosystem classification criteria and indices that are respondent-friendly. They help a CE study like this to overcome one of its critical weakness that the number and contents of attributes of a CE study can quickly add to the information overload problem, especially where the environmental good under investigation is hard for ordinary respondents to understand.

• KIEAE Journal
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• v.16 no.3
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• pp.121-128
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• 2016

Purpose: The vacuum glazing should constantly retain the gap in vacuum state to maintain high thermal performance. To do so, pillars are used to prevent the glazing from clinging to each other by the atmospheric pressure and therefore surface of the vacuum glazing is consistently affected by residual stress. The vacuum glazing could be applied to curtain wall systems at spandrel area to fulfill a rigorous domestic standard on U-value of the external wall. However, this can lead to high glazing temperature increase by heat concentration at a back panel and finally thermal stress breakage. This study experimentally determined weakness of the vacuum glazing systems on the thermal stress breakage and investigated effect of the residual stress. Method: The experiment first built two scale-down mock-up facilities that replicate the spandrel area in curtain wall, and then installed single low-e glass and vacuum glazing respectively. The two mock-up facilities were exposed to outside to induce the thermal stress breakage. Result: The experiment showed that the temperature occurred the thermal stress breakage was $114.4^{\circ}C$ for the single low-e glass and $118.9^{\circ}C$ for the vacuum glazing respectively. The result also showed the vacuum glazing reached the critical point earlier than the single low-e glass, which means that the vacuum glazing has high potential to occur the thermal shock breakage. In addition, the small temperature difference between two glazing indicates that the residual stress scarcely affects breakage of the vacuum glazing.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.6
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• pp.373-387
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• 2017

Objectives: The purpose of this study was to introduce our three experiments on bone morphogenetic protein (BMP) and its carriers performed using the critical sized segmental defect (CSD) model in rat fibula and to investigate development of animal models and carriers for more effective bone regeneration. Materials and Methods: For the experiments, 14, 16, and 24 rats with CSDs on both fibulae were used in Experiments 1, 2, and 3, respectively. BMP-2 with absorbable collagen sponge (ACS) (Experiments 1 and 2), autoclaved autogenous bone (AAB) and fibrin glue (FG) (Experiment 3), and xenogenic bone (Experiment 2) were used in the experimental groups. Radiographic and histomorphological evaluations were performed during the follow-up period of each experiment. Results: Significant new bone formation was commonly observed in all experimental groups using BMP-2 compared to control and xenograft (porcine bone) groups. Although there was some difference based on BMP carrier, regenerated bone volume was typically reduced by remodeling after initially forming excessive bone. Conclusion: BMP-2 demonstrates excellent ability for bone regeneration because of its osteoinductivity, but efficacy can be significantly different depending on its delivery system. ACS and FG showed relatively good bone regeneration capacity, satisfying the essential conditions of localization and release-control when used as BMP carriers. AAB could not provide release-control as a BMP carrier, but its space-maintenance role was remarkable. Carriers and scaffolds that can provide sufficient support to the BMP/carrier complex are necessary for large bone defects, and AAB is thought to be able to act as an effective scaffold. The CSD model of rat fibula is simple and useful for initial estimate of bone regeneration by agents including BMPs.

• Korean Journal of Cognitive Science
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• v.21 no.4
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• pp.535-557
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• 2010

Researchers have shown the negative compatibility effect (NCE) consistently using arrows. However, they provided inconsistent interpretations about the reason why the NCE happens. The purpose of the present study is to test the factors suggested to be critical for the NCE including automatic inhibition, updated information and top-down control. Presented with arrays of masked prime and targets composed of colored double-headed arrows, participants demonstrated invulnerable NCE on the basis of direction of arrows in the judgment of direction with corresponding hands (Experiment 1), with reverse-mapping hands (Experiment 2) and even in the color-judgment task (Experiment 3). These results imply that the main sources of NCE might be perceptual dominance and inherent properties of stimuli and responses; this contrasts with previously proposed explanations.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.410-413
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• 2005

The results of an experimental and analytical study of composite pressure hull on buckling pressure are presented for LRN 300. Composite tensile test was done to know the composite material properties applied FE analysis for URN composite. We predicted the buckling and post buckling analysis of composite laminated cylindrical panels under external compression by using ABAQUS /Standard[Ver 6.4]. To obtain nonlinear static equilibrium solutions for unstable problems, where the load-displacement response can exhibit the type of nonlinear buckling behavior, during periods of the response, the load and/or the displacement may decrease as the solution evolves, used the modified Riks method. The modified Riks method is an algorithm that allows effective solution of such cases [7]. Experiments were conducted to verify the validation of present analysis for cross-ply laminated shells. The shells considered in the study have two different lamination patterns, $[{\pm}45/0/90]_{18s\;and}\;[/0/90]_{18s}$. Cylindrical panel of experiment and analysis have the radius of 200mm, length of 210mm and 60 degree of cutting angle. The critical load from experiment is $69\%$ of that of numerical analysis, because the fracture of matrix was generated before buckling. So URN 300 is not proper to use at the condition under high external pressue.