• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3373-3383
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• 2009

The aim of the current study is to look at the mediating effects of structural features (i.e. decentralization, formalization, and specialization) on the relationship between product variety and the performance of product family. This study investigates the impact of decentralization and formalization for platform and derivative projects separately and in the context of the performance of the product family as a whole, as opposed to individual projects. In addition to relationships between people and groups, the current study considers physical element of an organization such as geographical location in which business tasks are conducted. The current study focuses on spatial differentiation which refers to the number of different sites or locations operated by an organization. Based on a cross-industry sample of 103 Korean manufacturers, this study examines the role of organizational structure features in which firms successfully increase product variety. The study examines that formalization in platform projects and decentralization in derivative projects enhance high variety firms' product family performance. The study finds significant mediating effect of spatial proximity on the relationship between product variety and product family performance.

• Journal of the Korean institute of surface engineering
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• v.46 no.2
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• pp.68-74
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• 2013

For the coating of diamond films on WC-Co tools, a buffer interlayer is needed because Co catalyzes diamond into graphite. W and Ti were chosen as candidate interlayer materials to prevent the diffusion of Co during diamond deposition. W or Ti interlayer of $1{\mu}m$ thickness was deposited on WC-Co substrate under Ar in a DC magnetron sputter. After seeding treatment of the interlayer-deposited specimens in an ultrasonic bath containing nanometer diamond powders, $2{\mu}m$ thick nanocrystalline diamond (NCD) films were deposited at $600^{\circ}C$ over the metal layers in a 2.45 GHz microwave plasma CVD system. The cross-sectional morphology of films was observed by FESEM. X-ray diffraction and visual Raman spectroscopy were used to confirm the NCD crystal structure. Micro hardness was measured by nano-indenter. The coefficient of friction (COF) was measured by tribology test using ball on disk method. After tribology test, wear tracks were examined by optical microscope and alpha step profiler. Rockwell C indentation test was performed to characterize the adhesion between films and substrate. Ti and W were found good interlayer materials to act as Co diffusion barriers and diamond nucleation layers. The COFs on NCD films with W or Ti interlayer were measured as less than 0.1 whereas that on bare WC-Co was 0.6~1.0. However, W interlayer exhibited better results than Ti in terms of the adhesion to WC-Co substrate and to NCD film. This result is believed to be due to smaller difference in the coefficients of thermal expansion of the related films in the case of W interlayer than Ti one. By varying the thickness of W interlayer as 1, 2, and $4{\mu}m$ with a fixed $2{\mu}m$ thick NCD film, no difference in COF and wear behavior but a significant change in adhesion was observed. It was shown that the thicker the interlayer, the stronger the adhesion. It is suggested that thicker W interlayer is more effective in relieving the residual stress of NCD film during cooling after deposition and results in stronger adhesion.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.21-30
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• 2013

As increasing number of large-size earthquake, the social interest of seismic retrofitting of RC structure is growing. Especially, the RC columns that are not reflected seismic design can not resist lateral loads by the earthquake. The brittle fracture of Non-seismic designed columns lead to full collapse of the building. Thus, the emergency columns reinforcement method is needed. That have a fast construction time, do not cause damage to the column. In the past, cross-sectional expansion method, a steel plate reinforcing method is applied mainly, but in recent years, carbon fiber sheet taking advantage of FRP (Fiber Reinforced Polymer) is widely used. In this study, retrofitting effect of seismic performance of FRP seismic reinforcement, which is possible to emergency construction, was examined. Reinforced concrete specimens were constructed to experimental study. The seismic performence of specimes retrifitted with FRP seismic reinforcement were evaluated. As a result, the seismic performance of specimen reinforced with FRP seismic reinforcement has been improved.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.8
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• pp.555-563
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• 2020

Foward-swept wings are known to possess superior aerodynamic performance compared to the conventional straight wings. However major concerns regarding forward-swept wings include divergence at lower airspeeds which require careful consideration at the design stage. As an endeavor to overcome such drawbacks, aeroelastic tailoring is attempted. In order to find an optimal ply sequence, recursive aeroelastic analyses is conducted and one-dimensional beam analysis coupled with simple aerodynamics is used for the improved computational efficiency and modelling convenience. The analysis used in this paper, DYMORE and analytic formula, both use one-dimensional beam model for the structure. Cross-sectional analysis for multi-cell NACA0015 airfoil section is conducted using VABS and oblique function is used for the sweep angle. Throughout the present aeroelastic tailoring, the maximum divergence speed of 290.2m/s is achieved which is increased by approximately 43% than that for the conventional ply configuration.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.6
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• pp.1-9
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• 2017

Spiral reinforcement in a circular column plays an effective role in the ductile behavior of a column through position fixing and buckling restraining of the longitudinal reinforcement, and confining core-concrete. Each country has suggested the minimum volumetric ratio of spiral reinforcement in order to secure the ductility of concrete columns. The minimum volumetric ratio of spiral reinforcement suggested by ACI 318-14 and the national concrete structure design standard was developed based on the theory of Richard et al. (1928); furthermore it has been used until now. However, their theory cannot consider the effects of high strength concrete and high strength reinforcement, and arrangement condition of the spiral reinforcement. In this study, a modified minimum volumetric ratio equation is suggested, which is required to improve the ductility of reinforced concrete circular columns and to recover their stress. The modified minimum volumetric ratio equation suggested here considers the effect of the compressive strength of concrete, the yield strength of spiral reinforcement, the cross sectional area of columns, the pitch of spiral reinforcements and the diameter of spiral reinforcement. In this paper, the validity of the minimum volumetric ratios from ACI 318-14 and this study was investigated and compared based on the results of uniaxial compression experiment for specimens in which the material strength and the spiral reinforcements ratio were used as variables. In the end of the study, the modification method for the suggested equation was examined.

• Journal of the korean academy of Pediatric Dentistry
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• v.40 no.1
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• pp.1-10
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• 2013

Dental erosion is a complex disease of multifactorial etiology with high risk of loss of tooth structure, which still has not been appropriate interest. The aim of this study was to assess the prevalence and risk indicators of dental erosion in Korean school children. A cross-sectional survey was performed on 664 children aged 8~9 years. Data concerning gender, types of caregiver, dietary habits, oral hygiene habits and parental knowledge were obtained from a questionnaire, which was answered by the parents of the children. Association between erosion and the factors were statistically analyzed with chi-squared test and independent t-test at a significance level of 0.05. Dental erosion was present in 242 children. In carbonated drinks, dental erosion was significantly associated with preference, frequency of consumption and the ingestion method (p < 0.05). In fruit juices, dental erosion was significantly associated with preference and frequency of consumption (p < 0.05), but no significant associations were found with the ingestion method (p > 0.05). There were no significant associations between dental erosion and gender, type of caregiver, oral hygiene habits and parental knowledge (p > 0.05). In conclusion, it was considered that motivation to be followed by practice is important as well as education for prevention of dental erosion.

• Journal of The Korean Association For Science Education
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• v.24 no.5
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• pp.987-995
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• 2004

The purpose of this study was to analyze characteristics of problem solving process with proportional or compensational reasoning of the elementary school students. For this study, 85th grade students were selected and tested with Science Reasoning Task, information processing ability test and proportional and compensational reasoning tasks. This study revealed that students in mid concrete stage could solve the proportionality task and easy compensation task. But, most of the students could not solve difficult compensation task. And as the students got higher score in information processing test, it took them less time to solve the problem. The types of strategy used in solving proportional and compensational problem were categorized as the factor of change, building-up and the cross-product. Most of the students failed in problem solving used incorrect schema knowledge, procedure knowledge and strategy knowledge. Many students tended to use proportionality strategy to solve the difficult compensation task. Result of this study suggested that various task included different structure and the same schema knowledge can be effective for the advancement of students' proportional and compensational reasoning ability.

• Culinary science and hospitality research
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• v.17 no.2
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• pp.51-73
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• 2011

Companies are required to invest in numerous intial marketing costs for establishing brand power, thus, many companies in the foodservice industry are increasing their budgets on communication to strengthen their own brand equity components such as brand recognition, brand royalty, perceived quality and associated image using mass media that has not been used before. For this study, 617 samples were analyzed by such analytic methods as a frequency analysis, cross-tabulation, a factor analysis and a reliability analysis for validity, and a confirmatory factory analysis, a model adequacy evaluation, and a path analysis using AMOS 17.0. The hypothesis verification by the AMOS analysis has revealed that all hypotheses positively influenced contract foodservice brands, and the brand recognition of a university contract foodservice company has an impact on sincerity and refinement. Therefore, positive brand image formation encourages strong brand establishment between a university contract foodservice business and customers, and this study strongly suggests continuous further studies about constructing a positive brand image.

• KDI Journal of Economic Policy
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• v.28 no.1
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• pp.145-191
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• 2006

This paper studies implications of financial conglomeration for both financial risk of individual conglomerates and systemic risk potential in post-crisis Korea. Our analyses suggest that we cannot conclude that financial conglomerates are taking on higher risks relative to non-conglomerate independent institutions. We also find that larger financial institutions show a significantly higher profitability and lower variability in profitability operating on a superior efficient frontier. However, it turns out that the consolidation has raised systemic risk potential as direct and indirect interdependencies among large banking institutions have substantially increased. Furthermore, financial conglomerates have become more vulnerable to contagion risks from non-bank sectors and capital markets. In the face of the shifting risk structure, financial supervisory and regulatory systems must be upgraded toward a more risk-based, consolidated supervision. Prompt corrective action provision for financial conglomerates must be based upon fully consolidated group risks, and effective supervisory devices need to be introduced to avoid inadvertent extension of public safety net to cross-sectoral activities of financial conglomerates. It is also critical to strengthen internal control and risk management capacities at financial conglomerates, and to establish strong market discipline by improving information transparency and monitoring incentives in the financial market.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.10
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• pp.1089-1097
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• 2002

In this paper, the novel shipboard Active Phased Array Antenna(APAA) system for maritime mobile satellite communications is introduced. The antenna uses novel technologies like wide range hybrid tracking, single antenna elements with both of Rx and Tx, asymmetrical array structure, interference isolation between Rx and Tx, and error correction method from frequency scan effect. The antenna has single aperture for both of Rx and Tx with 32 $\times$ 4 two-dimensional array. The antenna has two beams. Its frequencies are 7.25 ~ 7.75 GHz for Rx and 7.9 ~ 8.4 GHz for Tx. The antenna gains are 35.4 dBi for Rx and 35.7 dBi for Tx, those are 54 % of efficiency. The electrically steering ranges are $\pm$35$^{\circ}$ of elevation direction and $\pm$4$^{\circ}$ of azimuth direction. The mechanical control ranges at hybrid tracking capability are continuous 360$^{\circ}$ of azimuth direction and $\pm$10$^{\circ}$ of elevation direction. The antenna has 2.2$^{\circ}$ of 3 dB beamwidth, -14 dB of sidelobe level, and 21 dB of cross-pol suppression. The antenna performance was measured by near field measurement set. Its system performance was tested on the ship motion simulator and with the satellite transponder simulator. The test result showed that its tracking error was within -3 dB from its peak gain under motion condition. The antenna system was tested by real modulated Direct Broadcasting Satellite(DBS) signals to check its communication processing function.