• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.6
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• pp.1043-1051
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• 2017

Asphalt overlay on deteriorated concrete pavement has a problem of early damage due to reflective cracking. There is a need for a new method capable of reducing reflection cracking and ensuring the durability of pavement. The purpose of this study was to obtain durability of asphalt overlay with stress absorbing membrane interlayer (SAMI) using epoxy asphalt binder. The tensile performance, durability, water resistance and bonding performance of Epoxy-SAMI were evaluated by various tests. As a result of tests, Epoxy-SAMI meets the quality standard of the bridge waterproofing material. The repeated direct tensile test was carried out to investigate the effect of reflective cracking reduction. When the Epoxy-SAMI was applied, it had 1.2~1.56 times higher reflective cracking resistance than PSMA asphalt concrete with the thickness of 10cm even if the section thickness decreased. 4-point bending beam test results showed the number of fatigue failures increased 7.5 times when Epoxy-SAMI was applied. The Epoxy-SAMI was found to be effective in improving the durability of the asphalt pavement overlay because it serves to prevent reflective cracking, increase lifespan, and function as a waterproof layer.

• Journal of Digital Contents Society
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• v.17 no.6
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• pp.581-592
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• 2016

WebRTC has quickly grown to be the world's advanced real-time communication in several platforms such as web and mobile. In spite of the advantage, the current technology in WebRTC does not handle a big-streaming efficiently between peers and a large amount request of users on the Signaling server. Therefore, in this paper, we put our work to handle the problem by delivering the flow of data with dynamical load balancing algorithms. We analyze the request source users and direct those streaming requests to a load balancing component. More specifically, the component determines an amount of the requested resource and available resource on the response server, then it delivers streaming data to the requesting user parallel or alternately. To show how the method works, we firstly demonstrate the load-balancing algorithm by using a network simulation tool OPNET, then, we seek to implement the method into an Ubuntu server. In addition, we compare the result of our work and the original implementation of WebRTC, it shows that the method performs efficiently and dynamically than the origin.

• KDI Journal of Economic Policy
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• v.14 no.1
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• pp.191-212
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• 1992

This paper discusses the role of money in the process of capital accumulation where financial markets are impeded by contract enforcement problems in the context of overlapping generations framework. In particular, in less developed countries (LDCs) creditors may know little about the repayment capability of potential debtors due to incomplete information so that financial instruments other than money may not acceptable to them. In this paper the impediments to the operation of the private finanical markets are explicitly modelled. We argue that creditors cannot observe actual investment decisions made by the potential borrowers, and as a result, loan contracts may not be fully enforceable. Therefore, a laissez-faire regime may fail to provide the economy with the appropriate financial instruments. Under these circumstances, we introduce a government operated discount window (DW) that acts as an open market buyer of private debt. This theoretical structure represents the practice of governments of many LDCs to provide loans (typically at subsidized interest rates) to preferred borrowers either directly or indirectly through the commercial banking system. It is shown that the DW can substantially overcome impediments to trade which are caused by the credit market failure. An appropriate supply of the DW loan enables producers to purchase the resources they cannot obtain through direct transactions in the credit market. This result obtains even if the DW is subject to the same enforcement constraint that is responsible for the market failure. Thus, the DW intervention implies higher investment and output. However, the operation of the DW may cause inflation. Furthermore, the provision of cheap loans through the DW results in a worse income distribution. Therefore, there is room for welfare enhancing schemes that utilize the higher output to develop. We demonstrate that adequate lump sum taxes-cum-transfers along with the operation of the DW can support an allocation that is Pareto superior to the laissez-faire equilibrium allocation.

• The Journal of Korean Academy of Prosthodontics
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• v.43 no.6
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• pp.751-763
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• 2005

Statement of problem. To improve a direct implant fixation to the bone, various strategies have been developed focusing on the surface of materials. The surface quality of the implant depends on the chemical, physical, mechanical and topographical properties of the surface. The different properties will interact with each other and a change in thickness of the oxide layer may also result in a change in surface energy, the surface topography and surface, chemical composition. However, there is limited the comprehensive study with regard to changed surface and biologic behavior of osteoblast by anodization. Purpose of study. The aim of this study was to analyze the characteristics of an oxide layer formed and to evaluate the cellular biologic behaviors on titanium by anodic oxidation (anodization) by cellular proliferation, differentiation, ECM formation and gene expression. And the phospholipase activity was measured on the anodized surface as preliminary study to understand how surface properties of Ti implant are transduced into downstream cellular events. Methods and Materials. The surface of a commercially pure titanium(Grade 2) was modified by anodic oxidation. The group 1 samples had a machined surface and other three experimental specimens were anodized under a constant voltage of 270 V(Group 2), 350 V(Group 3), and 450 V(Group 4). The specimen characteristics were inspected using the following five categories; the surface morphology, the surface roughness, the thickness of oxide layer, the crystallinity, and the chemical composition of the oxide layer. Cell numbers were taken as a marker for cell proliferation. While the expression of alkaline phosphatase and Runx2 (Cbfa1) was used as early differentiation marker for osteoblast. The type I collagen production was determined, which constitutes the main structural protein of the extracellular matrix. Phospholipase $A_2$ and D activity were detected. Results. (1) The anodized titanium had a porous oxide layer, and there was increase in both the size and number of pores with increasing anodizing voltage. (2) With increasing voltage, the surface roughness and thickness of the oxide film increased significantly (p<0.01), the $TiO_2$phase changed from anatase to rutile. During the anodic oxidization, Ca and P ions were more incorporated into the oxide layer. (3) The in vitro cell responses of the specimen were also dependant on the oxidation conditions. With increasing voltage, the ALP activity, type I collagen production, and Cbfa 1 gene expression increased significantly (p<0.01), while the cell proliferation decreased. (4) In preliminary study on the relation of surface property and phospholipase, PLD activity was increased but $PLA_2$ activity did not changed according to applied voltage. Conclusion. The anodized titanium shows improved surface characteristics than the machined titanium. The surface properties acquired by anodization appear to give rise more mature osteoblast characteristics and might result in increased bone growth, and contribute to the achievement of a tight fixation. The precise mechanism of surface property signaling is not known, may be related to phospholipase D.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.2
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• pp.263-273
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• 2007

Statement of problem: Alteration of tooth function is assumed to be changed by stress/strain on the adjacent alveolar bone, producing changes in morphology similar to those described for other load-bearing bones. When teeth are removed, opposing teeth will not be functioned. When edentulous area is restored by implant prostheses, opposing teeth will be received physiologic mechanical stimuli. Purpose: The aim of this study was to evaluate the bone changes around the teeth opposing implant restoration installed mandibular posterior area. Material and method: Eight patients who had mandibular posterior edentulous area were treated with implants. Radiographs of the opposing teeth were taken at implant prostheses delivery(baseline), 3 months, and 6 months later. Customized film holding device was fabricated to standardize the projection geometry for serial radiographs of opposing teeth. Direct digital image was obtained. Gray values of region of interest at each digital image were measured and compared according to time lapse. Repeated measured analysis of variance and post-hoc Scheffe's test were performed at the 95% significance level. Results: Alveolar bone changes around the natural teeth opposing the posterior implant in mandible showed statistically significant difference compared to control group(P<0.05). And gray values of alveolar bone around the teeth opposing implants were increased. There were no statistically significant differences of alveolar bone changes between crestal group and middle group and between mesial group and distal group according to time lapse(P>0.05). There were no statistically significant differences of alveolar bone changes among mesial-crestal group, mesial-middle group, distal-crestal group, distal-middle group, and control group(P>0.05). Conclusion: Alveolar bone around the natural teeth opposing the implant prosthesis showed gradual bony apposition.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.1753-1763
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• 2013

In the design phase of sea-crossing bridge projects, ship collision problem is mostly participated in decision of substructure section and it would be performed by risk assessment and impact simulations. Ship collision risk is assessed by probability model which is similar to method II of Guide Specification and Commentary for Vessel Collision Design of Highway Bridge(AASHTO, 2009). However, several factors used in the applicable code are limited to inland waterways or have many local characteristics. Accordingly, it should be needed judgement of engineer or referred to related criteria, research finding. In this study risk assessment for In-cheon bridge and review of existing substructure's impact risk and resistance capacity are performed using the 2010's ship passage data. And then consideration regarding to presumption and applied instance of factors needed for risk assessment and related research findings are performed on the basis of AASHTO Guide's Method. As a result of study, adequate variable region of factors needed for risk assessment is defined and sensitivity analysis for appropriate region is performed. Consequently, factors that should be applied carefully or needed for direct analysis of local data are confirmed. This research could be fundamental material to risk assessment related to design for sea-crossing bridge taken into account ship collision.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.5
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• pp.2081-2091
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• 2013

Recently, the demand on the practical application of life-cycle cost effectiveness for design and rehabilitation of civil infrastructure is rapidly growing unprecedently in civil engineering practice. Accordingly, in the 21st century, it is almost obvious that life-cycle cost together with value engineering will become a new paradigm for all engineering decision problems in practice. However, in spite of impressive progress in the researches on the LCC, the most researches have only focused on the Deterministic or Probabilistic LCC analysis approach and general bridge at design stage. Thus, the goal of this study is to develop a practical and realistic methodology for the Life-Cycle Cost LCC-effective optimum decision-making based on reliability analysis of bridges at design stage. The proposed updated methodology is based on the concept of Life Cycle Performance(LCP) which is expressed as the sum of present value of expected direct/indirect maintenance costs with expected optimal maintenance scenario. The updated LCC methodology proposed in this study is applied to the optimum design problem of an actual highway bridge with Cable Stayed Bridges. In conclusion, based on the application of the proposed methods to an actual example bridge, it is demonstrated that a updated methodology for performance-based LCC analysis proposed in this thesis, shown applicably in practice as a efficient, practical, process LCC analysis method at design stage.

• Korean Journal of Clinical Laboratory Science
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• v.48 no.3
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• pp.230-236
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• 2016

Economic growth has increased the living standards around the world. Water pollution, in particular, is a public relations issue because it poses a direct threat to everyone's lives. As of recently, the production of taste and odor (T&O) compounds has been a common problem in the water industry. The adsorption process using granular activated carbon (GAC) has been the most widely used process. The objectives of this study were to evaluate the microorganisms before and after the backwashing of GAC and to identify the species of the microorganisms found. Five dominants microorganisms were confirmed after the microfiltration process from backwashing of GAC, and the dominant bacterial species were found to be ${\beta}$-proteobacterium species, Porphyrobacter donghaensis, Polaromonas rhizophaerae, Hydrogenophaga species, and Pseudonocardia species. However, when UV treatment after microfiltration was performed, Hydrogenophaga species and Psedonocardia species were eliminated. Herein, I conclude that the UV treatment post microfiltration process is more efficient than microfiltration process alone. The findings of this study may provide useful information regarding the management of microfiltration process.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.5
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• pp.495-503
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• 2014

As the number of vehicles has been sharply increases, the significance of safety and effective operation issues in the parking lot is being emphasized, which takes a part of the transportation system. Recently, there have been several studies for the parking management by detecting moving object, however, recognizing numbers of fast-moving vehicles simultaneously in the picture is still a challenging problem. The parking lot in public area, or large-sized buildings has clear parking section, whereas the sensor system is configured to monitor a plurality of parking spaces. Therefore, by considering those parking lots, we suggested to develop the real-time parking availability information system by applying the real-time image processing techniques. with the help of template matching. Following the study, we wanted to provide the alternative method for parking management system through the reference template makers by recognizing movements of parked vehicles with the size and shape, regardless of direct detecting of driving movements. In addition, we evaluated the applicability and performances of the information system, presented in this study, and implemented a prototype system to simulate the parking statuses of each floor. In fat, it was possible to manage and analyze statistics about the total number of parking spaces and the number of vehicles parked through real-time video flames. We expected that the result of the study will be advanced, following the user-friendliness and cost reduction in operating parking management system and giving information by efficient analysis of parking situation.

• Journal of Preventive Medicine and Public Health
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• v.27 no.4 s.48
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• pp.747-761
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• 1994

Workers' periodic health examination is the main tools used to manage the health problems of most workers in Korea. The most common health problem found in workers' periodic health examination is liver disorder. Liver disorder is also one of the most common health problems in general population and one of the leading causes of mortality in adult population. Regulation proposed by government (No. 207, Ministry of Labor, 1992) defines the criteria for selection of workers with the liver dysfunction for further evaluative examination and the examination items used for diagnosis of the workers with liver dysfunction. This study was designed to evaluate the proficiency of each examination items presently defined in Regulation and propose the optimal examination items for detection of the liver disorders found by workers' periodic health examination. Study subjects are 186 workers with abnormal liver function tests in screening examination of workers' periodic health examination. Questionnaire survey including past history of liver disorder, drinking history, height and weight was done. Physical examination by physician, routine test items defined by Regulation (SGOT, SGPT, $\gamma$-GTP, protein, albumin, total and direct bilirubin, alkaline phosphatase, $\alpha$-feto protein, HBsAg and anti-HBs), anti-HCV antibody test and liver ultrasonography were done. Results are as follows; 1. Result of evaluative examination utilizing only the items defined in Regulation was; There were 75 workers with suspected live. disorder(40.3%), 63 with no liver dysfunction (33.9%), 13 with suspected hepatitis B(7.0%), 10 workers with hepatitis B(5.4%), 10 workers with hepatitis B carrier state(5.4%), 10 with alcoholic liver disorders(5.4%), 5 with fatty liver(2.7%). When alternative diagnostic criteria applying additional examination items (drinking history, body mass index, anti-HCV antibody and ultrasonography) diagnosability of liver disorder was increased. When all four items were included, final results were; 23 workers (17.8%) with hepatitis B (10 carriers, 13 suspects and 10 hepatitis B), 10 (5.4%) with hepatitis C(4 carriers, 5 suspects and 1 hepatitis C), 13(7.0%) with alcoholic liver disorder, 45(24.2%) with fatty liver (40 suspects, 5 fatty liver), 410%) with suspected liver disorders and 44 (23.7%) with normal liver. 2. Of examination items defined by Regulation, only SGOT, SGPT, $\gamma$-GTP and HBsAg were significantly different in abnormal rate and mean value, and all other laboratory findings did not showed significant difference between two groups. Drinking history, body mass index and anti-HCV antibody test which are the items that authors included in this study, also showed significant difference between two groups. Utilization of body mass index (BMI) for abnormal liver function group in diagnosis of fatty liver had high specificity (97.6%) but sensitivity (22.3%) was low. Therefore we suggest that SGOT, SGPT, $\gamma$-GTP, HBsAg, alcohol drinking history, BMI and anti-HCV Ab were useful for diagnosis of liver disorders among worker's periodic health examination.