• Journal of the Korea Institute of Building Construction
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• v.7 no.1 s.23
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• pp.71-77
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• 2007

This paper is to investigate the effect of the curing temperature on strength development of concrete incorporating cement kiln dust(CKD) and blast furnace slag (BS) quantitatively. Estimation of the compressive strength of the concrete was conducted using the equivalent age equation and the rate constant model proposed by Carino. Correction of Carino model was studied to secure the accuracy of strength development estimation by introducing correction factors regarding rate constant and age. An increasing curing temperature results in an increase in strength at early age, but with the elapse of age, strength development at high curing temperature decreases compared with that at low curing temperature. Especially, the use of BS has a remarkable strength development at early age and even at later age, high strength is maintained due to accelerated pozzolanic activity resulting from high temperature. Whereas, at low curing temperature, the use of BS leads to a decrease in compressive strength. Accordingly, much attention should be paid to prevent strength loss at low temperature. Based on the strength development estimation using equivalent age equation, good agreements between measured strength and calculated strength are obtained.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1993.10a
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• pp.650-655
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• 1993

Carbon/epoxy composite(CFRP) coupons previously damaged by low velocity impact were tested under static tensile loading and microscope progress of damage was characterized by ultrasonic C-scan, Scanning Acoustic Microscopy (SAM) and Acoustic Emission(AE) techniques which were based on the application of elastic waves. The degress of impact damage has been correlated with the AE activity during monotonic or loading/unloading tensile testing as well as the result of ultrasonic test. The coupons were subjected to impact velocities ranged from 0.71 to 2.17 m/sec, which introduced the amount of damage rated as 0%, 10%, 30%, and 50% with reference to the total absorbed energy at fracture. Special attention was paid to determine optimal AE parameters to characterize the microscopic fracture process and to predict the residual strength of composite laminates. AE RMS voltage during the early stage of tensile loading was found an effective parameter to quantify the degree of impact damage. It was also found that the Felicity ratio is closely related to the stacking sequence and the residual strength of the CFRP laminates.

• Journal of the Korean Society of School Health
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• v.14 no.2
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• pp.187-206
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• 2001

The study was carried out to estimate the prevalence and possible causes of refractive errors in primary school children. At one primary school in urban Daegu, one in the medium-sized city of Yongcheon and 2 in rural areas, children wearing glasses and children with visual acuity of less than 0.7 were given our questions. 354 out of 378 children responded to our questions. The research was done from March 2000 to February 2001. The data were analyzed by percentage, x2 test, t-test, ANOVA and Scheff method. Children with eyesight problems were more prevalent in urban areas than rural areas. The lack of luminosity during reading (p=0.015), length of reading time (p=0.08) and posture which watching TV (p=0.023) appeared leading causes of progressing myopias. The visual impairment caused by refractive errors may affect the mental and physical activity of primary school children and lead to social isolation, loneliness and depression. However, little attention may be paid by professionals engaged in providing health care to the children. Once we have recognized the impact of visual impairment, we may be in a better position to prevent progressing refractive errors.

• Journal of Information Technology Services
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• v.5 no.2
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• pp.93-105
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• 2006

More emphasis has recently been put on the strategic application of IT, the linkage and integration between information system, and business process for value increase of a company's business. Thus, it is high time to redefine the concept of IT governance in order to effectively manage various IT services and assets. However, less attention has been paid to the practical study of domestic firms, compared to in the academic and industrial level. In this study, the current situation of IT governance setup and various factors for future development will be examined by a case study to explore activities, types, and determinants of decision making process that companies are currently conducting regarding IT governance. For the purpose of comparative analysis, two large enterprises were chosen with similar size of sales and high investment rate for IT within the same industry, and in-depth analysis was conducted based on the interviews of the concerned parties and in-house materials, from the perspective of structure, process, and relational mechanism. By the case study on IT governance of company 'A' and 'B', decision making mechanism and factors will be analyzed, which will indicate detailed characteristics of each decision-making field and its components for general application. By doing so, it is expected to be used as reference in building IT governance that fits the environment of a firm in the future.

• Knowledge Management Research
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• v.17 no.3
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• pp.117-136
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• 2016

External knowledge search is critical to expand the firm's knowledge base, increasing the innovation performance. However, prior literature has paid less scholarly attention on the boundary condition of the search activity. In particular, the few literatures on the contingency factors are either conceptual or focus on the firm characteristics such as resources and capability. In this regard, this study argues the negative moderating effect of knowledge protection and environmental uncertainty of a firm on the positive relationship between external knowledge search and innovation performance, because these contingency factors hamper the reciprocity and the mutual trust between the firm and its external partner that provides knowledge needed in the innovation process. The empirical analysis is based on the sample drawn from Korean Innovation Survey, provided by STEPI in Korea. The sample consists of 1,637 respondent firms that experienced product innovation during the survey period. We could find statistically supporting results for the negative moderating effect on the positive relationship between external knowledge search and innovation performance. This study extends the academic debate on the boundary conditions of external knowledge search and provides managerial implications for successful product innovation.

• Journal of Korean Society of Rural Planning
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• v.21 no.3
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• pp.59-66
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• 2015

The objective of this study was to investigate the perception of walking environment and use of neighborhood facilities of rural female elderly, who are the most susceptible to ambulatory problems. The study showed that parks, senior centers and hospitals were among the most frequently used neighborhood facilities by rural female elderly, while bus stations and senior centers were recognized as the closest facilities. Frequency of use was higher for paid sports facilities rather than parks. Hospitals and health centers were facilities that were desired to be in close proximity. Social support, self-efficacy, and attitude were the factors that affected walking environment. Street trees, accessibility to parks, and street lights were factors that showed a positive relationship with total time of walking activity while perceived crime rate and slopes were perceived as environmental challenges for groups that walked under 150 minutes per week. One factor that negatively affected walking was the lack of sidewalks on streets. Providing parks and walking trails within neighborhood, pleasant walking environments, and safe sidewalks would contribute to improved perception of neighborhood and walking of older rural women.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.26 no.1
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• pp.35-50
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• 2015

In order to re-activation of shared cataloging, spirit of community and cooperation are most needed. But proper compensation about contribution would motivate. Through representing basic data for making compensation policy about university library's share cataloging system, this study analyzes activities about contribution and utilization of participated libraries. To put it concretely, this study considers overall status of contribution and utilization through descriptive statistics and analyzes relationship between both sides. Furthermore through clustering participating library, this study brightened the libraries that ought to be compensated and who would be need to be specially rewarded. And draw the libraries that need to be paid and need to be led for active participation of shared cataloging.

• Sleep Medicine and Psychophysiology
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• v.9 no.1
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• pp.5-8
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• 2002

Stroke is a leading cause of death in most developed countries and some developing countries including South Korea. It is well known that stroke has is related in some way with several sleep disorders. At first, the onset time of stroke varies according to circadian rhythm. Early morning is the most prevalent time and late evening the least. The changes of blood pressure, catecholamine level, plasminogen activity and aggregation of platelet during sleep have been suggested as possible mechanisms. Sleep apnea (SA), a representative disorder in the field of sleep medicine, is found in more than 70% of acute stroke patients compared to 2-5% of the general population. Various sleep related breathing disorders occur after stroke and snoring is a distinct risk factor for stroke. So the relationship between stroke and SA is obvious, but the cause and effect are still not clearly known. Also, stroke may cause many sleep related problems such as insomnia, hypersomnia, parasomnia and changes in sleep architecture. Patients, family members and even medical personnel often ignore stroke-related sleep problems, being concerned only about the stroke itself. The clinical impacts of sleep problems in stroke patients may be significant not only in terms of quality of life but also as a risk factor or prognostic factor for stroke. More attention should be paid to the sleep problems of stroke patients.

• Architectural research
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• v.14 no.4
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• pp.133-141
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• 2012

The research started from the consideration that, although many aspects of the Milanese Early Renaissance are well known today, thanks to a vast literature, only few studies, so far, have paid attention to the ordinary world of architectural work - and its obscure protagonists - of this area and this period. Moving from the belief that this topic is crucial for a complete understanding of the 15th century architectural world, characterized by a progressive overlapping of roles and responsibilities in the worksites, this study aims to provide a contribution to expand the understanding of this matter, by focusing on a particular aspect of it: the role of the public administration in the architectural activity. In particular, the paper analyzes the characteristics of the "Office of the engineers of the Municipality of Milan", one of the major public architectural institution of the Duchy of Milan in the 15th century. Through an extensive archival survey, conducted in the major archives of Milan and Lombardy, the research achieves two main findings: a) the reconstruction of the complete Office staff throughout the 15th century and, b) an outline of the role and identity of the Office and its officers, through the elaboration of data collected. In particular, professional roles, technical duties, cultural background and tasks of the officers, together with Office management, appointment procedures and salary conditions are highlighted. This research, not meant as an ultimate study on the topic discussed, is intended to provide some material and reference points for further researches that will aim to expand the understanding of this matter.

• Architectural research
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• v.16 no.4
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• pp.193-202
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• 2014

This research started from the premise that Jacques Perret, "Savoyard gentleman" of the 17th century - whose only legacy consists of Des fortifications et artifices, a book of fortified town designs - is still an elusive figure in the history of architecture and deserves to be further investigated. In particular, attention needs to be paid to the lack of any attempt by scholars to define his actual professional status and cultural background: was he an architect, an engineer, a professional or an amateur? The intention of this paper is therefore to shed some light on this question by examining selected contents of his book describing five projects of fortified towns. Plates and descriptions are carefully analyzed related to the engineering (defensive structures) and architectural (city layouts, buildings) content. The figure that emerges is that of an articulate personality who does not fit either in the architectural or in the military engineering professional world. In the field of engineering, he simultaneously demonstrated the competence of a professional and the na$\ddot{i}$vety of an immature technician, while in the field of architecture he showed an advanced creativity alongside several technical and theoretical misunderstandings. From the analysis in this study, the assumption is formulated that Jacques Perret was a connoisseur, i.e. an erudite without any direct involvement in real professional activity. This work is intended to provide a hypothesis for further researches that, hopefully, will deepen our understanding of several other aspects of Perret's complex identity and work.