• Korean Journal of Construction Engineering and Management
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• v.20 no.1
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• pp.124-132
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• 2019

Notwithstanding the crucial contribution of international construction industry in the national economy, previous studies on international construction contracts had mainly focused either on trend investigation or market share analysis at a point of time. Fundamentally, the international construction industry is fragmented due to its project-based nature, is heterogeneous that has to involve different firms from diverse fields, and tends to be dynamic according to macroeconomic conditions. Therefore, the combination of static and dynamic analyses is necessary to understand its underlying structure. This study analyzes the market structure of international construction contracts using the data of 9,173 projects awarded by Korean construction firms from 2000 to 2017. Industry-level performance data is analyzed both in static (market concentration) and dynamic (market mobility and instability) methods, and detailed methodology is also provided. Consequently, the static analysis result shows that the competition among Korean construction firms has been more intensified, and the dynamic analysis result indicates that market positions of Korean construction firms are unstable and vulnerable in most of the regions and the sectors. The combination of static and dynamic indices is found to be helpful to understand the underlying aspects of market structure and can be utilized as an effective strategic reference in the highly competitive market.

• Geophysics and Geophysical Exploration
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• v.11 no.1
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• pp.34-40
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• 2008

Underwater seismic refraction with advanced interpretation approaches makes important contributions to shallow marine exploration and geotechnical investigations in Australia's coastal areas. A series of case studies are presented to demonstrate the recent applications of continuous and static USR methods to river crossing and port infrastructure projects at various sites around Australia. In Sydney, static underwater seismic refraction (USR) with bottom-placed receivers and borehole seismic imaging assisted the development of improved geotechnical models that reduced construction risk for a tunnel crossing of the Lane Cove River. In Melbourne, combining conventional boomer reflection and continuous USR with near-bottom sources and receivers improved the definition of a buried, variably weathered basalt flow and assisted dredging assessment for navigation channel upgrades at Geelong Ports. Sand quality assessment with continuous USR and widely spaced borehole information assisted commercial decisions on available sand resources for the reclamation phase of development at the Port of Brisbane. Buried reefs and indurated layers occur in Australian coastal sediments with the characteristics of laterally limited, high velocity, cap layers within lower velocity materials. If these features are not recognised then significant error in depth determination to deeper refractors can occur. Application of advanced refraction inversion using wavefront eikonal tomography to continuous USR data obtained along the route of a proposed offshore pipeline near Fremantle allowed these layers and the underlying bedrock refractor to be accurately imaged. Static USR and the same interpretation approach was used to image the drowned granitic regolith beneath sediments and indurated layers in the northern area of Western Australia at a proposed new berthing site where deep piling was required. This allowed preferred piling sites to be identified, reducing overall pile lengths. USR can be expected to find increased application to shallow marine exploration and geotechnical investigations in Australia's coastal areas as economic growth continues and improved interpretation methods are developed.

• Progress in Medical Physics
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• v.24 no.1
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• pp.76-83
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• 2013

Previous studies about effect of respiratory motion on diagnostic imaging and radiation therapy have been performed by monitoring external motions but these can not reflect internal organ motion well. The aim of this study was to develope the artificial pulmonary nodule able to perform non-invasive implantation to dogs in the thorax and to evaluate applicability of the model to respiratory motion studies on PET image acquisition and radiation delivery by phantom studies. Artificial pulmonary nodule was developed on the basis of 8 Fr disposable gastric feeding tube. Four anesthetized dogs underwent implantation of the models via trachea and implanted locations of the models were confirmed by fluoroscopic images. Artificial pulmonary nodule models for PET injected $^{18}F$-FDG and mounted on the respiratory motion phantom. PET images of those acquired under static, 10-rpm- and 15-rpm-longitudinal round motion status. Artificial pulmonary nodule models for radiation delivery inserted glass dosemeter and mounted on the respiratory motion phantom. Radiation delivery was performed at 1 Gy under static, 10-rpm- and 15-rpm-longitudinal round motion status. Fluoroscpic images showed that all models implanted in the proximal caudal bronchiole and location of models changed as respiratory cycle. Artificial pulmonary nodule model showed motion artifact as respiratory motion on PET images. SNR of respiratory gated images was 7.21. which was decreased when compared with that of reference images 10.15. However, counts of respiratory images on profiles showed similar pattern with those of reference images when compared with those of static images, and it is assured that reconstruction of images using by respiratory gating improved image quality. Delivery dose to glass dosemeter inserted in the models were same under static and 10-rpm-longitudinal motion status with 0.91 Gy, but dose delivered under 15-rpm-longitudinal motion status was decreased with 0.90 Gy. Mild decrease of delivered radiation dose confirmed by electrometer. The model implanted in the proximal caudal bronchiole with high feasibility and reflected pulmonary internal motion on fluoroscopic images. Motion artifact could show on PET images and respiratory motion resulted in mild blurring during radiation delivery. So, the artificial pulmonary nodule model will be useful tools for study about evaluation of motion on diagnostic imaging and radiation therapy using laboratory animals.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2010.10a
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• pp.110-112
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• 2010

Because the building of new meteorological observation towers requires high cost, a collection of precise meteorological data over city area is not easy. To collect atmosphere environment data or meteorological data precisely, a new approach is required. This paper introduces a new meteorological data collecting system using the public traffic systems such as regular route bus. On real time, the regular route bus can provide a meteorological data in periodic time interval and provide them on static route. Without constructing new facilities, only simple sensing and transmission equipments to attach on the bus are needed.

• Korean journal of communication and information
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• v.67
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• pp.119-151
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• 2014

The absence of the commensurable general mass media system theory has been problematic in empirical communication studies. This study first suggests the static mass media system theory based on modified Habermas's two level society, and then develops the dynamic mass media system theory based on the boundary-agencement theory that synthesizes Luhmann's boundary theory and Delueze & Guattari's agencement theory. In the static mass media system theory, the mass media system interpenetrates other social subsystems and the life world as a part of the cultural system coordinated by generalized language media. In the dynamic mass media system theory, the mass media system is a boundary of all social subsystems. The mass media system also articulates its self-referential observations to other-referential observations from other subsystems, mediated interpenetrations between the social subsystems and the life world. Especially, performances in the mass media system deterritorizes social systems to the life world, and reterritorizes the life world to social systems. The general mass media system theory can provide commensurability for various empirical mass media system studies, and prevent biases when researchers choose research topics.

• The Journal of the Korea Contents Association
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• v.21 no.10
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• pp.368-377
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• 2021

This study analyzed the determinants of capital structure based on the financial statements of agricultural corporations disclosed on the DART(data analysis, retrieval and transfer system) of the Financial Supervisory Service since 2011, when the Korea international financial reporting standards (K-IFRS) was introduced. There have been many empirical studies on the capital structure so far, but there are no studies targeting agricultural corporations. The sample period of agricultural corporations was from 2015 to 2019, with the debt ratio as the dependent variable, and among the variables suggested as meaningful in existing empirical studies, ROA(profitability), SIZE(corporate size), LIQ(liquidity), TA(tangible asset ratio), FA(fixed long-term suitability ratio), and GROWTH(growth potential) were selected as independent variables and panel data analysis was performed. As a result of the analysis, it was found that the debt ratio decreased as the ROA and SIZE of agricultural corporations increased. This can be interpreted as supporting the pecking order theory rather than the static trade-off theory in the relationship between the ROA and SIZE of Korean agricultural corporations with the capital structure. In addition, it was found that the debt ratio increased as the FA increased. These results suggest that Korean agricultural corporations need to establish a financing policy in consideration of ROA, SIZE, and FA.

• Journal of Korean Academy of Nursing
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• v.43 no.3
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• pp.341-351
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• 2013

Purpose: This study was done to analyze the effects of Tai Chi on fall-related risk factors through meta-analysis of randomized clinical trials published in English and Korean between 2000 and 2010. Methods: Using health related database and hand search of references and Google, 28 randomized studies were collected from doctoral dissertation and published peer reviewed articles. The Comprehensive Meta-analysis version 2.0 was used for the analysis. Results: The effect sizes for Tai Chi for 3 months were significant with ES=0.54 for static balance, ES=0.24 for dynamic balance, ES=0.69 for balance measured by scale, and ES=0.40 for flexibility, ES=0.48 for muscle strength, ES=0.71 for ADL, and ES=0.37 for fear of falling. Also, the effect sizes of Tai Chi for 6 months were significant for most fall-related variables. The 6 month data for flexibility was not analyzed since only one study was published. Conclusion: The analysis of studies of randomized clinical trials indicate that Tai Chi is effective in improving balance, flexibility, muscle strength, activities of daily living, and fear of falling when applied for 3 or 6 months. The findings provide the objective evidence to apply Tai Chi as a fall preventive intervention.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.557-560
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• 1999

In civil engineering and construction field, recently the great enhancement of new material and building technique have been made by many studies and reports. These studies have attracted many countries, since 1980's those study on reinforcement with steel fiber have been done by America, Japan and the other countries. Designs and proposals on building method have been applied, several universities and laboratory centers in our country have been studied, but the study on field application is short. Also a part of study on the shear behavior of reinforced concrete beams with steel fiber has accomplished. but up to this time, reliable establishment is undone. Therefore, this study is performed the static loading test to analysis shear failure behavior in reinforced concrete beams with steel fiber. we have observed the limit load of shear force, primary bending crack load, primary diagonal crack load, evaluating relative of load and steel, crack increase and failure shape according to increase of load. Through the exam and the observation of output, we estimate the shear failure behavior of SFRC beams according to fiber mixing amount.

• 한국전산유체공학회:학술대회논문집
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• 2004.03a
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• pp.224-229
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• 2004

The objective of this work is not only to perform feasibility studies on the CFD (computational fluid dynamics) analysis for the capillary system design but also to provide an enhanced understanding of the autonomous capillary flow. The capillary flow is evaluated by means of the commercial CFD software of FLUENT, which includes the VOF (volume-of-fluid) model for multiphase flow analysis. The effect of wall adhesion at fluid interfaces in contact with rigid boundaries is considered in terms of static contact angle. Feasibility studies are first performed, including mesh-resolution influence on pressure profile, which has a sudden increase at the liquid/gas interface. Then we perform both 2D and 3D simulations and examine the transient nature of the capillary flow. Analytical solutions are also derived for simple cases and compared with numerical results. Through this work, essential information on the capillary system design is brought out. Our efforts and initial success in numerical description of the microfluidic capillary flows enhance the fundamental understanding of the autonomous capillary flow and will eventually pave the road for full-scale, computer-aided design of microfluidic networks.

• Proceedings of the KWS Conference
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• 2006.10a
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• pp.63-65
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• 2006

The paper deals with the effect of hydrogen or helium in argon as a shielding gas on GTA welding of austenitic stainless steel. The studies were carried out in GTA(Gas Tungsten Arc) welding with a non-consumable electrode in case with different volume additions of hydrogen or helium to the argon shielding gas, i.e $5%H_2,\;10%H_2$, 30%He and 67%He. The penetration, welding voltage, microstructure and mechanical property were examined. The deepest penetration was obtained from the sample which was welded under shielding gas of $10%H_2$. The studies showed that hydrogen or helium addition to argon changes the static characteristic of the welding arc. The hydrogen or helium addition to argon increases arc power and the quantity of the material melted. The weld metal penetration depth and its width increased with increasing hydrogen or helium content. Additionally, welding voltage increased with increasing hydrogen or helium content.