• Journal of the Computational Structural Engineering Institute of Korea
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• v.18 no.2
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• pp.201-211
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• 2005

Due to the complex mechanism and various parameters that affect shear behavior of reinforced concrete (RC) members, models on shear tend to be complex and difficult to utilize for design of structural members, and empirical relationships formulated with limited test data often work lot members having a specific range of influencing parameters on shear. As an alternative approach tot solving this problem, artificial neural networks have been suggested by some researchers. In this paper, artificial neural networks were used to predict shear strengths of RC beams without shear reinforcement. Especially, a large database that consists of shear test results of 398 RC members without shear reinforcement was used for artificial neural network analysis. Three well known approaches for shear strength of RC members, ACI 318-02 shear provision, Zsutiy's equation, and Okamura's relationship, are also evaluated with test results in the shear database and compared with neural network approach. While ACI 318-02 provided inaccurate predictions for RC members without shear reinforcement, the empirical equations by Zsutty and Okamura provided more improved prediction of Shear strength than ACI 318-02. The artificial neural networks, however provided the best prediction of shear strengths of RC beams without shear reinforcement that was closest to test results.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.3
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• pp.130-134
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• 2017

In this study, numerical simulation was performed to focus on optimized process condition for obtaining a long-term growth and high quality SiC crystal. It could be optimized by considering the change of fluid and a carbon flow in the Si melt added with 40 % Cr. The Crystal Growth Simulator ($CGSim^{TM}$, STR Group Ltd.) was used as a numerical simulation. It was confirmed that many parameters such as temperature, rotation speed of seed crystal and crucible, and seed position during the crystal growth step had a strong influence on the speed and direction of solution flow for uniform temperature gradient and stable crystal growth. The optimized process condition for the solution growth of SiC crystal was successfully exhibited by adjusting various process parameters in the numerical simulation, which would be helpful for real crystal growth.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.187-196
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• 2005

Since the allowable bearing capacities of piles in weathered/fractured rock are mainly governed by settlement, the load-displacement behavior of pile should be known accurately. To predict pile head settlement at the design stage, the exact understanding of the load-transfer mechanisms is essential. Therefore, in this research, the load-transfer mechanism of drilled shaft socketed into weathered rock was investigated. For the investigation, five cast-in-place concrete piles with diameters of 1,000 mm were socketed into weathered gneiss. The static axial load tests and the load-transfer measurements were performed to examine the axial resistant behavior of the piles. A comprehensive field/laboratory testing program on weathered rock at the Held test sites was also performed to describe the in situ rock mass conditions quantitatively. And then, the effect of rock mass condition on the load transfer mechanism was investigated. The f-w (side shear resistance-displacement) curve of the pile in moderately weathered rock reached to yielding point at a for millimeter displacements, and after yielding point, the rate of resistance increment dramatically decreased. However, the f-w curve in the highly/completely weathered rock did not show the obvious yielding point, and the resistance gradually increased showing the hyperbolic pattern until relatively high displacement (>15 mm). The q-w (end bearing resistance-displacement) curves showed linear response at least until the base displacement of approximately 10 mm, regardless of rock mass conditions.

• Journal of the Korean Society for Library and Information Science
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• v.53 no.2
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• pp.201-221
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• 2019

The Korea Institute of Civil Engineering and Building Technology provides the documents and information on the construction technology through the Construction Technology Digital Library System to enhance the technological competitiveness of the construction engineers. The purpose of this study is to measure the monetary value of information service quality in order to improve the documents and information service quality provided by this system. For this purpose, a questionnaire model was designed to apply the DBDC- CVM. We surveyed the members of 300 this systems for the amount of information that they are willing to pay to maximize the quality of information service. The correlation between the dependent variable and the explanatory variables was analyzed with the basic statistics of the survey results. The independent variables affecting the dependent variable are statistically significant. The logit model is used to estimate the monetary value of individual respondents who are willing to pay for information service quality. In previous research, we measured the use value of information service. On the other hand, this study shows that the measurement of value based on information service quality is different from previous research.

• Journal of Convergence for Information Technology
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• v.11 no.7
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• pp.111-117
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• 2021

This research work is to suggest the experimental results capable of solving an initial unsuitability of combustion and environment in a constant volume combustion chamber by using LFG(Land Fill Gas) which consists of 40% CO₂ and 60% CH₄. The experimental condition is set as 0.9~1.6 of air-fuel ratio, 3bar of combustion pressure, 25℃ of room temperature, methane for using gas, and 2.5~4.5 of Pre-chamber hole sizes. As a result, it can be seen that diffusion of initial flame is significantly increased by M3.0 model comparing with other one. The reason for the characteristics is that orifice effect is extremely improved by 0.9, 1.0, and 1.2 of air-fuel ratio comparing with other one. Consequently, this experiment is shown that M3.0 model is partially capable of improving combustion performance than a conventional ignition plug in case of applying to LFG with Pre-chamber design.

• Journal of Advanced Navigation Technology
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• v.21 no.6
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• pp.537-543
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• 2017

Underwater glider is the long-term operating underwater robot that was developed with a purpose of continuous oceanographic observations and explorations. Torpedo-type underwater glider is not efficient from an aspect of maneuverability, because it uses a single buoyancy engine and motion controller for obtaining propulsive forces and moments. This paper introduces a ray-type underwater glider(RUG) with dual buoyancy engine, which improves the control performance of buoyancy and motion compared with torpedo-type underwater glider. Carrying out Computational Fluid Dynamics (CFD) analysis as static pitch drift test, the performance of fluid resistance for gliding motion was identified. Based on the calculated hydrodynamic coefficients, the dynamic simulation compared and analyzed the motion performance of torpedo-type and ray-type while controlling same volume of buoyancy engine. Small-sized model of RUG was developed to perform fundamental performance tests.

• Korean Chemical Engineering Research
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• v.54 no.3
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• pp.380-386
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• 2016

In this study, we described a paper-based neuraminidase assay sensor (PNAS) which can be applied to detect the infection by influenza viruses. The PNAS was designed and manufactured to quantitatively identify the levels of neuraminidase in the sample, which is based on colorimetric analysis using the X-Neu5Ac substrate. The limit of detection of the PNAS was determined as 0.004 U/mL of neuraminidase. According to the amount of neuraminidase in human serum, the PNAS could monitor the enzyme activity with a good linearity ($R^2$ > 0.99). In addition, the initial performance of the PNAS has been maintained up to 70 days in the $4^{\circ}C$. Finally, we demonstrated whether the Michaelis-Menten kinetics is applied to the PNAS, which can show the reliability of the enzyme reactions. The kinetic studies indicated that the PNAS provides the good condition for enzyme reactions ($K_m=8.327{\times}10^{-3}M$), but they were performed on paper chip nonetheless. The paper-based neuraminidase assay sensor may be useful in a wide range of rapid and safe detection of influenza virus.

• Korean Security Journal
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• no.55
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• pp.117-141
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• 2018

Police crime statistics report that residential housing such as apartment, low rise, detached houses is the second most vulnerable to crime, which is closely followed by the number of street crimes. Also residential houses are often exposed to quality-of-life crime, e.g burglary. It threatens the basic human rights of house residents in terms of safety and comfort within the urban living environment. This study examines related precedent studies regarding the vulnerability of residential housing including studios, multi-family housing from the viewpoint of crime prevention through environment design(CPTED), extracted the elements and items suitable for the safety of residential facilities and the certification evaluation indicators and check items to be the basis for the checklist are derived. Based on these evaluation indicators and inspection items, we conducted on-site surveys of residential facilities in three areas of Seoul, Yongin and Asan, and the final draft of the checklist was revised based on the results of the field survey. There are 43 items on the 7 fields of evaluation in the final version of checklist, 11 items in the management and operation, 20 items in the surveillance, 7 items in the access control, 1 item in the territoriality, 2 items in the activity support, and 2 items in the security and safety facilities. In addition, various points of interest were added to allow the administrator of the residential facility to earn points for special measures taken for safety. This checklist can be appropriately modified and utilized in consideration of the characteristics of each facility. Korean national police agency has CPOs to check the residential facilities in their jurisdiction using checklists and to certify excellent facilities with high level of safety.

• Journal of Intelligence and Information Systems
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• v.24 no.3
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• pp.177-198
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• 2018

Recently, as economic property it has become necessary to acquire and utilize the framework for water resource measurement and performance management as the property of water resources changes to hold "public property". To date, the evaluation of water technology has been carried out by feasibility study analysis or technology assessment based on net present value (NPV) or benefit-to-cost (B/C) effect, however it is not yet systemized in terms of valuation models to objectively assess an economic value of technology-based business to receive diffusion and feedback of research outcomes. Therefore, K-water (known as a government-supported public company in Korea) company feels the necessity to establish a technology valuation framework suitable for technical characteristics of water resources fields in charge and verify an exemplified case applied to the technology. The K-water evaluation technology applied to this study, as a public interest goods, can be used as a tool to measure the value and achievement contributed to society and to manage them. Therefore, by calculating the value in which the subject technology contributed to the entire society as a public resource, we make use of it as a basis information for the advertising medium of performance on the influence effect of the benefits or the necessity of cost input, and then secure the legitimacy for large-scale R&D cost input in terms of the characteristics of public technology. Hence, K-water company, one of the public corporation in Korea which deals with public goods of 'water resources', will be able to establish a commercialization strategy for business operation and prepare for a basis for the performance calculation of input R&D cost. In this study, K-water has developed a web-based technology valuation model for public interest type water resources based on the technology evaluation system that is suitable for the characteristics of a technology in water resources fields. In particular, by utilizing the evaluation methodology of the Institute of Advanced Industrial Science and Technology (AIST) in Japan to match the expense items to the expense accounts based on the related benefit items, we proposed the so-called 'K-water's proprietary model' which involves the 'cost-benefit' approach and the FCF (Free Cash Flow), and ultimately led to build a pipeline on the K-water research performance management system and then verify the practical case of a technology related to "desalination". We analyze the embedded design logic and evaluation process of web-based valuation system that reflects characteristics of water resources technology, reference information and database(D/B)-associated logic for each model to calculate public interest-based and profit-based technology values in technology integrated management system. We review the hybrid evaluation module that reflects the quantitative index of the qualitative evaluation indices reflecting the unique characteristics of water resources and the visualized user-interface (UI) of the actual web-based evaluation, which both are appended for calculating the business value based on financial data to the existing web-based technology valuation systems in other fields. K-water's technology valuation model is evaluated by distinguishing between public-interest type and profitable-type water technology. First, evaluation modules in profit-type technology valuation model are designed based on 'profitability of technology'. For example, the technology inventory K-water holds has a number of profit-oriented technologies such as water treatment membranes. On the other hand, the public interest-type technology valuation is designed to evaluate the public-interest oriented technology such as the dam, which reflects the characteristics of public benefits and costs. In order to examine the appropriateness of the cost-benefit based public utility valuation model (i.e. K-water specific technology valuation model) presented in this study, we applied to practical cases from calculation of benefit-to-cost analysis on water resource technology with 20 years of lifetime. In future we will additionally conduct verifying the K-water public utility-based valuation model by each business model which reflects various business environmental characteristics.

• Journal of Nutrition and Health
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• v.52 no.1
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• pp.104-117
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• 2019

Purpose: This study examined dietary and health characteristics of the young-old and the old-old by food security status. Methods: The study used data from the $6^{th}$ (2013 ~ 2015) Korea National Health and Nutrition Examination Survey. The study subjects consisted of 3,948 subjects, of whom 2,445 were the young-old (aged 65 to 74 years) and 1,503 were the old-old (aged 75 years and over). Food security status was evaluated using an 18-item questionnaire. Energy intake, nutrient densities, and prevalence of insufficient nutrient intake were assessed. Food intake was evaluated in terms of the number of food group servings. Dietary behaviors and health status were also assessed. Results: The prevalence of food insecurity among the young-old and the old-old was 10.0% and 11.6%, respectively. Among the young-old, the food insecure group had a significantly higher level of prevalence of insufficient intake for all the nutrients (protein, vitamin A, thiamin, riboflavin, niacin, vitamin C, calcium, phosphorous, and iron) assessed in this study compared with the food secure group. In case of the old-old, significant differences were found only for four nutrients (protein, riboflavin, niacin, and phosphorus) in the prevalence of insufficient nutrient intake between the food secure and the food insecure groups. Kinds of food groups with significantly different numbers of servings by food security status were dissimilar between the two age groups. In both the age groups, the food insecure group consumed a significantly lower number of servings in meat fish eggs legumes and fruits than the food secure group; grains and vegetables intake in the young-old and oils sweets intake in the old-old differed in the number of servings by food security status. Among the young-old, the prevalence of chewing difficulties in the food insecure group was significantly higher than that of the food secure group, while among the old-old, no significant differences were found by food security status. Conclusion: Dietary and health characteristics of the young-old and the old-old differed by food security status. Such differences were more apparent in the young-old than the old-old. Therefore, it is suggested that food and nutrition assistant programs should be designed with consideration of the differences.