• Structural Engineering and Mechanics
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• v.55 no.3
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• pp.555-581
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• 2015

Triangular pyramid and Quadrangular pyramid elements for partial double-layer spherical reticulated shells of pyramidal system are investigated in the present study. Macro programs for six typical partial double-layer spherical reticulated shells of pyramidal system are compiled by using the ANSYS Parametric Design Language (APDL). Internal force analysis of six spherical reticulated shells is carried out. Distribution regularity of the stress and displacement are studied. A shape optimization program is proposed by adopting the sequence two-stage algorithm (RDQA) in FORTRAN environment based on the characteristics of partial double-layer spherical reticulated shells of pyramidal system and the ideas of discrete variable optimization design. Shape optimization is achieved by considering the objective function of the minimum total steel consumption, global and locality constraints. The shape optimization of six spherical reticulated shells is calculated with the span of 30m~120m and rise to span ratio of 1/7~1/3. The variations of the total steel consumption along with the span and rise to span ratio are discussed with contrast to the results of shape optimization. The optimal combination of main design parameters for six spherical reticulated shells is investigated, i.e., the number of the optimal grids. The results show that: (1) The Kiewitt and Geodesic partial double-layer spherical reticulated shells of triangular pyramidal system should be preferentially adopted in large and medium-span structures. The range of rise to span ratio is from 1/6 to 1/5. (2) The Ribbed and Schwedler partial double-layer spherical reticulated shells of quadrangular pyramidal system should be preferentially adopted in small-span structures. The rise to span ratio should be 1/4. (3) Grids of the six spherical reticulated shells can be optimized after shape optimization and the total steel consumption is optimized to be the least.

• Polymer(Korea)
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• v.27 no.2
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• pp.120-128
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• 2003

The effects of catalyst, accelerator and blend composition on the cure behavior of unsaturated polyester resin (UPE), vinyl ester resin (VE) and their blends were studied using differential scanning calorimetry(DSC). The DSC thermograms strongly depend on each variable. The result shows that the small exothermic peak at 115$^{\circ}C$ is due mainly to the UPE component in the UPE/VE blends and the large one at 134~138 $^{\circ}C$ is due mainly to the VE component. The results also indicate that the change of the DSC thermogram measured after each blend was exposed to high temperature 18$0^{\circ}C$ and the fast curing conditions of a few tens seconds provide useful information on understanding the thermal processing of a blend at high speed. The measurements of resin flow time represent that there are three distinct stages of cure in the UPE/VE blends: induction, transition and macro-gelation stages, as similarly reported for UPE by others earlier. The thermal stability and flexural properties of the cured UPE are significantly improved by blending it with the VE, depending on the composition.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.753-756
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• 2008

HPFRCC (High-Performance Fiber Reinforced Cementitious Composites), which is relatively more ductile and has the characteristic of high toughness with high fiber volume fractions, can be used in structures subjected to extreme loads and exposed to durability problems. In the case of using PVA(polyvinyl alcohol) fibers, it is noted by former studies that around 2% fiber volume fractions contributes to the most effective performance at HPFRCC. In this study, therefore, compressive and flexural tests were implemented to evaluate the compressive and flexural capacities of HPFRCC while the total fiber volume fractions was fixed at 2% and two different PVA fibers were used with variable fiber volume fractions to control the micro-crack and macro-crack with short and long fibers, respectively. Moreover, specimens reinforced with steel and PVA fiber simultaneously were also tested to estimate their behavior and finally find out the optimized mixture. In the result of these experiments, the specimen consists of 1.6% short fibers (REC 15) and 0.4% long fiber (RF4000) outperformed other specimens. When a little steel fibers added to the mixture with 2% PVA fibers, the flexural capacity was increased, however, when high steel fiber volume fractions applied, the flexural capacity was decreased.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.30 no.2
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• pp.213-225
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• 2020

Objectives: In order to prepare measures to enhance construction workers' satisfaction with their working environment, the effects of working conditions and the mediating effects of safety and health information on workers' satisfaction with their working environment in the construction industry have been studied. The results of this study can be used as basic data for further studies in this field. Method: Data on 1,361 male construction workers from the 5th Korea Working Condition Survey (KWCS) were used for this study. The effects of working conditions were analyzed using SPSS 25.0 and the mediating effects of health and safety information were analyzed with SPSS PROCESS macro using the bootstrap method. Results: The safety and health management system and the self-determination of break time had a statistically significant positive effect on satisfaction with the working environment. Chemical and ergonomic risk factors had a statistically significant negative effect on satisfaction with the working environment. The provision of safety and health information, the mediating variable, had a statistically significant positive effect on satisfaction with the working environment. Therefore, it had a mediating effect between working conditions and satisfaction with the working environment. Conclusion: In order to enhance construction workers' satisfaction with their working environment, the above results suggest that the safety and health management system should be well established; self-determination of break times should be guaranteed; and chemical and ergonomic risk factors should be controlled. In addition, workers should be provided with necessary health and safety information related to their work. This study will be useful if these findings are used as basic data in further studies in related fields.

• Journal of the Korean Geographical Society
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• v.48 no.5
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• pp.786-801
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• 2013

This study aims to elucidate features of the geography assessment of France in which geography has a high status in school curriculum. The main data for analysing are the geography examinations(1999-2013) of the Baccalaur$\acute{e}$at. In terms of objectives of the assessment, the exams put emphasis on promoting cultural knowledges of students and developing their competences in graphic languages. In terms of formal aspect, the exams take a simple layouts to raise a readability, use variable test tools, especially an essay and a 'croquis'. They also emphasize students self-directedly constructing and representing geography knowledges and their inquiry abilities with geography materials. In terms of contents aspect, the exams mainly cover subjects of political-economic geography, particularly a spatial organization, a development inequality and the world powers in global contexts or macro spatial scales. One of a distinguishing characteristics of Baccalaur$\acute{e}$at's History-Geography examinations is that it designs to keep balance between two parties; history and geography.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10C
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• pp.1036-1043
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• 2005

In this paper, we propose a sequential motion vector recovery algorithm for H.264 video coding standard. Motion vectors of H.264 video coding standard cover relatively smaller areas than other standard, since motion estimation of H.264 takes place in the fashion of variable block size. Therefore, the correlation of motion vectors between neighboring blocks increases as the block size of motion estimation is lowered. Under the framework of sequential recovery, we introduce a motion vector recovery using $\alpha$-trimed mean filter. Experimental results show that proposed algorithm is useful in real time video delivery .with nearly comparable or better visual quality than previous approaches such as macro block boundary matching and Lagrage interpolation.

• The Journal of the Korea Contents Association
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• v.21 no.9
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• pp.404-418
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• 2021

This study aimed to verify the mediating effects of personality and job-seeking efficacy in the process of college students' career maturity affecting their career decision certainty level. To this end, an online survey was conducted with 254 college students attending domestic and foreign universities, which confirmed the mediating effect of job-seeking efficacy in the relationship between career maturity and career decision certainty level. In addition, the effect of career maturity on the level of career decision certainty, mediated by job-seeking efficacy, was shown to be controlled by personality, namely extraversion, confirming the moderate mediating effect of this variable. Based on these findings, the implications and limitations of this study are discussed.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.31 no.1
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• pp.38-49
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• 2021

Objectives: This study was conducted to analyze the impact of safety/health managers' experience of trauma case on their post traumatic stress disorder and the mediation effects of job stress and the moderated mediation effects of social support. Method: Using a structured questionnaire, data were collected from 241 workplace safety/health managers with experience in trauma case. The collected data were analyzed using SPSS(IBM. Ver.26.0) and verified through SPSS PROCESS Macro (Ver. 3.4). Results: The trauma case experience and the job stress, which is a mediation variable, had a statistically significant positive effect on post-traumatic stress disorder, and the job stress had a positive mediation effect in the relationship between the trauma case experience and post-traumatic stress disorder. Social support had a statistically significant negative moderation effect in the relationship between the trauma case experience and job stress; social support had a moderated mediation effect on the indirect effect of a job stress on the post-traumatic effect through a trauma case experience. Conclusion: The above findings suggest that work-related job stress management is important in order to reduce safety/health managers' post-traumatic stress disorder caused by the experience of trauma case, and that social support is essential to reduce the job stress, which can later be used as a basis for further studies.

• Journal of Korea Trade
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• v.24 no.7
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• pp.54-72
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• 2020

Purpose - This study explores the contextual factors that affect the relationship between CEO overseas experience and firm internationalization. This study incorporates a wide range of contextual factors, including mega, macro, and micro variables. In particular, this study goes a step further from prior studies by incorporating a higher-order variable i.e., the global financial crisis that can constrain the managerial discretion of a CEO. Design/methodology - To structure the balanced data set before and after the 2008 global financial crisis, we used the data for the years from 2002 to 2014 from a sample of Korean manufacturing firms. Ultimately, 1101 firm-year unbalanced panel observations from 101 firms were used for the analysis. Findings - Our main findings can be summarized as follows. CEO overseas experience is positively related to firm internationalization. However, this relationship varies depending on the CEOs level of managerial discretion. As for the constraining moderation, the global financial crisis weakened the positive relationship between CEO overseas experience and firm internationalization. As for the enabling moderation, the CEOs tenure strengthened the relationship. Originality/value - This study adopted the knowledge, skills, and abilities (KSA) framework to explain the relationship between CEO overseas experience and firm internationalization. Moreover, we argue that the CEO-internationalization relationship depends on the specific context of the managerial discretion, focusing on the 2008 global financial crisis. Empirically, this study adopted the 2SLS procedure to correct endogeneity. Instead of taking the actual value of prior internationalization as a control, we estimated prior internationalization using the instrument variables at an industry level. This procedure made our estimation more robust.

• The Journal of the Korea Contents Association
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• v.22 no.2
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• pp.379-389
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• 2022

This study analyzed 10,352 married women to find the correlation between marital equality felt by married women and additional childbirth intentions. Frequency analysis and chi-square test analysis were performed to analyze the general characteristics of the investigator, and studies were conducted through binary logistic regression analysis and interaction analysis to analyze the relevance between each variable and additional childbirth. As a result, the 4-point group based on the 0-point group that lowest marital equality had 2.01 times higher willingness to additional birth. And, the 3-point group and the 2-point group were 1.46 times and 1.41 times higher than 0-point group with marital equality and additional childbirth intentions. In addition, intention of additional childbirth was increased when the higher the number of children, if they own a house, and if wives are non-regular or unemployed. This study analyzed the relationship between married women's intention to give birth additionally, focusing on marital equality. It is suggested that specific and reasonable policies at the macro level are required to improve the fertility rate.