• Journal of Korean Society of Transportation
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• v.32 no.5
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• pp.531-543
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• 2014

Research on activity-based travel demand forecasting and activity-travel simulator has received an international attention for the last two decades. Ways to develop the activity-based simulator may be manifold. It is obvious that importing an existing simulator that has been proven internationally likely reduces the development cost and the risk of failure. By definition of the activity-based approach, however, the details of an activity-based simulator inevitably relies on particular social, economic and cultural characteristics of the society where the simulator is developed. When importing such a simulator from overseas, the researcher should be aware of the importance of tuning the system for the society to which the imported system is applied. There are many potential works on this, including for example the tuning of data structure that is likely different form of the original system. The authors are yet aware of certain research on those. The current paper aims to report the result of transforming the input data for applying the existing activity-travel simulator to Seoul. The paper first introduces FEATHERS that was developed in Belgium having Albatross which is the core of system. FEATHERS Seoul that is under development and modified version of the original FEATHERS is briefly described and the related problems are discussed. The paper then explored to resolve and to alleviate such problems.

• Journal of the Korean Society of Radiology
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• v.6 no.1
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• pp.19-26
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• 2012

It is very important for early diagnosis and therapy with ischamic cerebral infarction patients. This study was to know the ischemic penumbra lesion which compared CT-perfusion and diffusion weighted MRI(DWMRI) with acute cerebral infarction patients. 12 acute cerebral infarction patients had performed perfusion CT and performed DWMRI. Perfusion images including cerebral blood volume(CBV), cerebral blood flow(CBF), time to peak(TTP) and mean transit time(MTT) maps obtained the values with defect lesion and contralateral normal cerebral hemisphere and DWMRI was measured by signal intensity and compared of lesion size between each perfusion map. All perfusion CT maps showed the perfusion defect lesions in all patients. There were remarkable TTP and MTT delay in perfusion defect lesions. The lesions on CBF map was the most closely correlated with the lesions on DWMRI. The size of perfusion defect lesions on TTP and MTT map was larger than that of lesions on DWMRI, suggesting that MTT map can evaluate the ischemic penumbra. Perfusion CT maps make it possible to evaluate not only ischemic core and ischemic penumbra, but also hemodynamic status in the perfusion defect area. These results demonstrate that perfusion CT can be useful to the diagnosis and treatment in the patients with acute cerebral ischemic infarction.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.140-140
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• 2018

The 3D interconnect technologies have been appeared, as the density of Integrated Circuit (IC) devices increases. Through Silicon Via (TSV) process is an important technology in the 3D interconnect technologies. And the process is used to form a vertically electrical connection through silicon dies. This TSV process has some advantages that short length of interconnection, high interconnection density, low electrical resistance, and low power consumption. Because of these advantages, TSVs could improve the device performance higher. The fabrication process of TSV has several steps such as TSV etching, insulator deposition, seed layer deposition, metallization, planarization, and assembly. Among them, TSV metallization (i.e. TSV filling) was core process in the fabrication process of TSV because TSV metallization determines the performance and reliability of the TSV interconnect. TSVs were commonly filled with metals by using the simple electrochemical deposition method. However, since the aspect ratio of TSVs was become a higher, it was easy to occur voids and copper filling of TSVs became more difficult. Using some additives like an accelerator, suppressor and leveler for the void-free filling of TSVs, deposition rate of bottom could be fast whereas deposition of side walls could be inhibited. The suppressor was adsorbed surface of via easily because of its higher molecular weight than the accelerator. However, for high aspect ratio TSV fillers, the growth of the top of via can be accelerated because the suppressor is replaced by an accelerator. The substitution of the accelerator and the suppressor caused the side wall growth and defect generation. The suppressor was used as Single additive electrodeposition of TSV to overcome the constraints. At the electrochemical deposition of high aspect ratio of TSVs, the suppressor as single additive could effectively suppress the growth of the top surface and the void-free bottom-up filling became possible. Generally, copper was used to fill TSVs since its low resistivity could reduce the RC delay of the interconnection. However, because of the large Coefficients of Thermal Expansion (CTE) mismatch between silicon and copper, stress was induced to the silicon around the TSVs at the annealing process. The Keep Out Zone (KOZ), the stressed area in the silicon, could affect carrier mobility and could cause degradation of the device performance. Cobalt can be used as an alternative material because the CTE of cobalt was lower than that of copper. Therefore, using cobalt could reduce KOZ and improve device performance. In this study, high-aspect ratio TSVs were filled with cobalt using the electrochemical deposition. And the filling performance was enhanced by using the suppressor as single additive. Electrochemical analysis explains the effect of suppressor in the cobalt filling bath and the effect of filling behavior at condition such as current type was investigated.

• The Journal of Engineering Geology
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• v.17 no.3
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• pp.435-443
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• 2007

This study shows the prediction of the engineering properties of weathered zone bearing corestones through the engineering geological surveys and the scale model test in the laboratory. The window survey and the observation on the borehole core were peformed on three natural slopes in corestones area in order to analyse the distribution pattern and the geometrical properties of corestones. Natural corestones were crushed and abrased for the scale model test into less than 5 mm in maximum-2mm in average by the scale reduction ratio based on the size of natural corestones and the specimen size. Scale model tests were carried out on soil and plaster model specimens with different corestone content ratio - 0%, 10%, 20%. The direct shear test on soils shows that shear strength is increased by the increase of corestone content ratio. The increase of cohesion is, however, more important factor to the shear strength of soil for 20% corestone content ratio due to interlocking of crushed corestone particles. The plaster model test shows a tendance of increase of UCS and modulus of elasticity with increase of corestone content. The variation ratio of specimen property by change of corestone content ratio in plaster model test was applied to in situ properties in order to estimate the properties of weathered zone bearing corestones. So it could be predicted that the increase of corestone content to 10% and to 20% produce about 18% and 30% UCS's increase respectively.

• 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.

• Macromolecular Research
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• v.10 no.3
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• pp.158-167
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• 2002

In order to endow with new bioactive functionality from small intestine submucosa (SIS) powder as natural source to poly (L-lactide) (PLA) and poly (lactide-co-glycolide) (PLGA) synthetic biodegradable polymer, porous SIS/PLA and SIS/PLGA as natural/synthetic composite scaffolds were prepared by means of the solvent casting/salt leaching methods for the possibility of the application of tissue engineered bone and cartilage. A uniform distribution of good interconnected pores from the surface to core region was observed the pore size of 40~500 ${\mu}{\textrm}{m}$ independent with SIS amount using the solvent casting/salt leaching method. Porosities, specific pore areas as well as pore size distribution also were almost same. After the fabrication of SIS/PLA hybrid scaffolds, the wetting properties was greatly enhanced resulting in more uniform cell seeding and distribution. Five groups as PGA non-woven mesh without glutaraldehyde (GA) treatment, PLA scaffold without or with GA treatment, and SIS/PLA (Code No.3 ; 1 : 12 of salt content, (0.4 : 1 of SIS content, and 144 ${\mu}{\textrm}{m}$ of median pore size) without or with GA treatment were implanted into the back of nude mouse to observe the effect of SIS on the induction of cells proliferation by hematoxylin and eosin, and von Kossa staining for 8 weeks. It was observed that the effect of SIS/PLA scaffolds with GA treatment on bone induction are stronger than PLA scaffolds, that is to say, in the order of PLA/SIS scaffolds with GA treatment > PLA/SIS scaffolds without GA treatment > PGA nonwoven > PLA scaffolds only with GA treatment = PLA scaffolds only without GA treatment for the osteoinduction activity. The possible explanations are (1) many kinds of secreted, circulating, and extracellular matrix-bound growth factors from SIS to significantly affect critical processes of tissue development and differentiation, (2) the exposure of SIS to GA resulted in significantly calcification, and (3) peri-implant fibrosis due to covalent bonding between collagen molecule by crosslinking reaction. In conclusion, it seems that SIS plays an important role for bone induction in SIS/PLA scaffolds for the application of tissue engineering area.

• Plant Journal
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• v.10 no.1
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• pp.47-53
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• 2014

The national capacity of electricity of Korea was 81,737 MW and the peak demand was renewed by the record of 71,230 MW in 2012 which has been increasing since the first lighting ceremony had taken place in the Royal Palace(Kyung-Bok Goong) in 1887. Aa the counteract on the rapid increasing of the demand, Korean government is constructing and operating the high capacity nuclear and thermal power plants, however, the operating reserve on weekdays is small while those of weekends are more than 40% of capacity, so they are providing the pumped-storage power plants with the surplus electricity during weekends and operating the power plants which cost higher production price and located in the capital area with WSS (Weekly Start and Stop) mode including the Seoul Thermal Power Plant. Since the Seoul Thermal Power Plant is spending huge amount of expenses for more than 30 times of the WSS annually due to the high production cost even though it is in Seoul, the core of the demand, I chose the power plant unit #5 which was on the grid in 1969 for the case to confirm reducing 23% of the warm start-up time by applying the "Start-up time management program", and that reducing 35% of the water temperature increasing time by accelerate the increasing rate of the inlet temperature of the water circulating pump.

• Nuclear Engineering and Technology
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• v.27 no.3
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• pp.301-316
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• 1995

experimental and computational studies ore carried out to investigate the natural convection of the single phase flow in a tank with a heated horizontal plate facing downward. This is a simplified model for investigations of the influence of a core melt at the bottom of a reactor vessel on the thermal hydraulic behavior in a oater filled cavity surrounding the vessel. In this case the vessel is simulated by a hexahedron insulated box with a heated plate Horizontally mounted at the bottom of the box. The box with the heated plate is installed in a water filled hexahedron tank. Coolers are immersed in the U-type water volume between the box and the tank. Although the multicomponent flows exist more probably below the heated plate in reality, present study concentrates on the single phase flow in a first step prior to investigating the complicated multicomponent thermal hydraulic phenomena. In the present study, in order to get a better understanding for the natural convection characteristics below the heated plate, the velocity and temperature are measured by LDA(Laser Doppler Anemometry) and thermocouples, respectively. And How fields are visualized by taking pictures of the How region with suspended particles. The results show the occurrence of a very effective circulation of the fluid in the whole How area as the heater and coolers are put into operation. In the remote region below the heated plate the new is nearly stagnant, and a remarkable temperature stratification can be observed with very thin thermal boundary. Analytical predictions using the FLUTAN code show a reasonable matching of the measured velocity fields.

• Information Systems Review
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• v.6 no.2
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• pp.285-305
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• 2004

This study is based on providing core infrastructure to make or extend an ERP strategy to make the proper model to cope effectively with various customer requirements and market changes through ERP improvement. The purpose of this study is to support making a competitive advantage by raising productivity and reducing costs as a result of making and applying the "mobile real time connection to ERP"model which is accessible anywhere and anytime using PDA and wireless LAN on the basis of mobile business concept. The model is implemented as the "mobile Material Management System" on the area of material management of ERP in the enterprise which already implemented ERP system. This model is also applied into other divisions of the enterprise. This case study shows that the proper application of ERP reduces costs by reducing business process lead time, increase productivity and customer satisfaction through mobility and instant connectivity and easiness of the system. It is recommended to apply this model into the ERP system which is used in most enterprise, to make a competitive advantage. To sum up, the model in this study can be applied into the enterprise which wants to reduce costs, increase productivity and customer satisfaction through ERP improvement.

• Journal of Gifted/Talented Education
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• v.26 no.1
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• pp.77-99
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• 2016

The purpose of this study was to examine the effect of GI-STEAM program on leadership, creative personality, and learning flow of elementary Gifted Students. GI-STEAM program was the convergence model of Group Investigation that belongs to Co-learning and STEAM framework of learning criterion. The participants were 16 gifted students in a Korean elementary school located in Gyeong-gi province. The experimental design was one group pretest-posttest design. After a pretest on leadership, creative personality, and learning flow was conducted, classes were carried out as GI-STEAM program for the gifted student and a post-test was conducted. The study results of the class that was conducted twelve times for two weeks are as follows. First, Individual area of leadership is meaningfully developed in statistics after GI-STEAM program. The sub-domains of leadership, such as the communication, organization management, society commitment and teamwork showed a statistically significant improvement. Second, the domain of creative personality didn't show meaningful difference after GI-STEAM program. However, the aesthetic in the sub-domains of the creative personality showed a statistically significant improvement. Third, learning flow was meaningfully developed in statistics after GI-STEAM program. The sub-domains of the leadership, such as the balance between challenge and ability, integration with behavior and consciousness, concrete feedback and Autotelic experience showed a statistically significant improvement. In conclusion, GI-STEAM is an effective program for improving ability of communication, aesthetic sensibility, which are core competency of 'creative-convergence' gifted students. For this reason, it is highly considered that various programs applying GI-STEAM should be developed.