• Journal of Hydrogen and New Energy
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• v.26 no.3
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• pp.260-270
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• 2015

One-dimensional packed bed reactor model accounting for interfacial and intra-particle gradients was developed and based on it numerical analyses were performed to investigate the dynamic behavior of a commercial scale methanation reactor. Methanation reaction was almost complete near the reactor inlet and gases with equilibrated composition were discharged from the reactor. Both the intra-particle temperature gradient and differential surface temperature rise were found to be severe near the reactor inlet. To reduce the possible degradation or fracture of catalyst particles and prevent local overheating on the catalyst, addition of inert material can be an effective way.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2010.05a
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• pp.191-194
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• 2010

Construction companies are now trying a variety of cost-cutting strategies in the midst of recent slump of construction market. Notably, contract workers and local hires are accounting for increasing portion of management manpower as a part of their cost-reduction drive. However, construction site manpower researches to date have focused primarily on productivity analysis of site laborers, with little attention to the productivity of site management resources. This study aims to analyze the staffing status of office building construction site management manpower in reference to project size. Conclusions herein will provide basic inputs for subsequent attempts to build a model to enable efficient staffing of construction site management manpower.

• Journal of Mechanical Science and Technology
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• v.18 no.2
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• pp.230-239
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• 2004

A compact model approach of a network of spring elements for elastic loading is presented for the thermal deformation analysis of BGA package assembly. High-sensitivity moire interferometry is applied to evaluate and calibrated the model quantitatively. Two ball grid array (BGA) package assemblies are employed for moire experiments. For a package assembly with a small global bending, the spring model can predict the boundary conditions of the critical solder ball excellently well. For a package assembly with a large global bending, however, the relative displacements determined by spring model agree well with that by experiment after accounting for the rigid-body rotation. The shear strain results of the FEM with the input from the calibrated compact spring model agree reasonably well with the experimental data. The results imply that the combined approach of the compact spring model and the local FE analysis is an effective way to predict strains and stresses and to determine solder damage of the critical solder ball.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.1
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• pp.161-169
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• 1989

A stability problem on wave instability of natural convection flow along isothermal vertical cylindrical surfaces has been formulated, accounting for the non-parallelism of the basic flow and thermal fields. Then the problem is solved numerically under the simplifying assumption of the parallelism of the basic flow quantities. It is shown that the flow corresponding to the same characteristic boundary layer thickness becomes more stable as the value of the curvature parameter increases. The stability characteristics for Pr=0.7 appear to be more sensitive to the curvature parameter than those for Pr=7.

• Smart Structures and Systems
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• v.1 no.3
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• pp.309-324
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• 2005

This paper presents an efficient and accurate coupled beam model for piezoelectric bimorphs based on improved first-order shear deformation theory (FSDT). The model combines the equivalent single layer approach for the mechanical displacements and a layerwise modeling for the electric potential. General electric field function is proposed to reasonably approximate the through-the-thickness distribution of the applied and induced electric potentials. Layerwise defined shear correction factor (k) accounting for nonlinear shear strain distribution is introduced into both the shear stress resultant and the electric displacement integration. Analytical solutions for free vibrations and forced response under electromechanical loads are obtained for the simply supported piezoelectric bimorphs with series or parallel arrangement, and the numerical results for various length-to-thickness ratios are compared with the exact two-dimensional piezoelasticity solution. Excellent predictions with low error estimates of local and global responses as well as the modal frequencies are observed.

• Korean Journal of Bronchoesophagology
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• v.7 no.1
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• pp.54-58
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• 2001

Granular cell tumor or also called Abrikossoff's tumor, is a rare benign tumor that can occur anywhere in the body. Granular cell tumor may single or multiple (synchronous or metachronous). Approximately half of all granular cell tumors occur in the head and neck. most commonly in the tongue. But granular cell tumors of the larynx are rare, accounting for only 7 to 10% of all reported cases. Laryngeal tumors are usually small and men are more frequently affected than women. The exact histogenesis is still not known but most recent data support the neurogenic Schwann cell origin. The preferred treatment is local excision using cold knife or laser. Radiation therapy is of little benefit. We report a case of granular cell tumor of the larynx which was confirmed by histopathology.

• Journal of information and communication convergence engineering
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• v.2 no.2
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• pp.128-131
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• 2004

We suggest resource authorization system based on RBAC admitting someone to access resources. In existing grid environment, The authorization mechanism on user's resource is to give users an authority on the basis of DN(Distinguished Name) of proxy certificate and map file mapped in local system ID by one-to-one. In this case, it is difficulty in resource management such as each accounting management, memory resource, and disk resource, if the number of users, who want to use them is increased. To solve this problem, we specify the role of user's task in extension fields of his proxy certificate instead of the authorization mechanism of user's ID and propose resource authorization system being able to access his resource.

• Archives of Craniofacial Surgery
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• v.22 no.1
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• pp.56-61
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• 2021

Sebaceous carcinoma (SC) is a rare tumor, accounting for approximately 0.7% of skin cancers. SC can be classified as ocular SC (OSC) or extraocular SC (EOSC) depending on its location. Because EOSC accompanied by metastases is rare, there is a paucity of data about EOSC accompanied by metastasis. This study presents a case of an aggressive EOSC of the scalp with lymph node metastases. The patient underwent wide local excision of the primary tumor with a 1 cm safety margin and bilateral radical lymph node dissection. However, recurrence was observed 1 month after surgery. Radiation therapy and resection were performed for the recurrent tumor. However, distant metastases to both lungs eventually occurred. Here, we describe a rare recurrent case of EOSC of the scalp with distant organ metastasis with a review of the literature.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.211-211
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• 2020

The concept of virtual water has been largely applied in the study of regional, national, and global water flows with particular emphasis on water scarcity. Despite water traditionally being managed locally, certain global forces influence the local water resource scarcity/availability and hence virtual water exchanges worldwide. It is therefore of necessity that the significant forces be examined to understand the relationship between available water in a region and the variability and trends in environmental, social, and economic factors that are of utmost importance in the formulation of water resources management policies. This study therefore reviewed recent literature from 2003 - 2019 to determine the significant indicators of virtual water trade at different spatiotemporal levels. The study examined and compared the major approaches to virtual water trade flows accounting, and also identified and discussed policy implications and future research options concerning the analysis of virtual water trade. Available information has shown that virtual water trade is significantly influenced by economic (GDP, Demand-Supply of goods and services), geographical (Distance), institutional (population) and environmental (water availability, arable land, precipitation) factors. Reports further show that the selection of a given approach for virtual water trade flows accounting will depend on the scope of the study, the available datasets, and other research preferences. Accordingly, this study suggests that the adoption of multidisciplinary approaches to virtual water trade, taking into consideration the spatial and temporal variations in water resources availability and the complexity of environmental and socioeconomic factors will be pivotal for establishing the basis for the conservation of water resources worldwide.

• Journal of the Korean association of regional geographers
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• v.13 no.1
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• pp.54-67
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• 2007

This paper aims to explore the characteristics of regional embeddedness of Korean firms in Daren City, China, with special reference to management practices. To achieve this goal, I attempt to analyze the type and structure of the firm, the structure of decision-making, labor practices, and the inter-organizational networks with the government, trade associations and the business supporting agencies. The major purpose of the investment in Daren by Korean firms is to penetrate and expand the local market. In line with this, the structure of decision-making by Korean firms tends to become increasingly autonomous, especially in terms of employment and marketing. However, the decision-making related to finance and accounting tends to be still highly controlled upon the headquarter in Korea. In addition, it is shown that Korean firms make a great effort to sustain the cooperative relationships with the local society and the local government.