• Korean Journal of Construction Engineering and Management
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• v.9 no.3
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• pp.164-174
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• 2008

It is crucial In decision making to select a project delivery system (PDS) adjusted accordingly to the project characteristics. Furthermore, selecting a tendering system is the kernel in the process of selecting PDS. In October 2007, the Ministry of Finance and the Economy of Korea launched two new project delivery systems, "Best Value Contract (Design-Bid-Build)" and "Bridging Contracts (Design-Build)" by revising enforcement ordinances of "Act on Contracts to Which the State is a Party" to provoke the tendering systems. In order to support the proposed purpose, this research developed a selection model for suitable tendering system, which helps a public owner select a tendering system appropriate to the project characteristics. First, the framework of the model was set throughout analyzing previous researches and interviewing relevant experts. Additionally, by analyzing the survey result from 265 experts engaged in architectural and civil engineering business, the relative weights of the selection factors and the effectiveness values of the alternatives were suggested as the quantitative evaluation references. Finally, the practical guideline was suggested to apply this model to three public projects scheduled to be delivered. The result of applying the model to three case projects showed that further researches were needed to make the selection process logical and to suggest the standard weights and effectiveness values according to project type.

• The Journal of Sustainable Design and Educational Environment Research
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• v.18 no.3
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• pp.50-59
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• 2019

The results of a survey on 6,192 elementary schools across the country in April 2019 are as follows : First, there was a correlation between the number of students and the number of classes. Second, 2,788 schools (45.0%) were small schools, 1,931 schools (31.2%) were suitably sized schools, and 1,473 schools (23.8%) were large schools among the 6,192 elementary schools surveyed. Third, there was a significant difference in the proportion of small schools, suitably sized schools, and large schools by province. Among the 8 metropolitan cities, Seoul had the lowest percentage of small schools at 9.8%, followed by Incheon at 18.0%. Among the 9 provinces, Gyeonggi Province had the lowest rate at 26.8%, while Jeollanam-do had the highest rate at 87.2%. This means that adopting the same standard for abolition of small schools throughout different provinces can cause serious problems. Therefore, it is necessary to reflect the educational conditions of each province.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.13 no.2
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• pp.13-29
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• 2003

Web-mail system is worthy of note as a next generation e-mail system for its mobility and easiness. But many web-mail system does not have any kind of security mechanism. Even if web-mail system provides security services, its degree of strength is too low. Using these web-mail systems, the e-mail is tabbed, modified or forged by attacker easily. To solve these problems, we design and implement secure web-mail system based on the international e-mail security standard S/MIME in this thesis. This secure web-mail system is composed of server system and client system The server system performs basic mail functions - sending/receiving the mails, storing the mails, and management of user information, etc. And the client system performs cryptographic functions - encryption/decryption of the mails, digital signing and validation, etc. Because client system performs cryptographic functions this secure web-mail system gives its reliability and safety, and provides end-to-end security between mail users. Also, this secure web-mail system increase system efficiency by minimize server load.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.54-63
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• 2022

This paper is a study on the friction damper, which is one of the seismic reinforcement devices for structures. This study developed a damper by replacing the internal friction material with ultra high molecular weight polyethylene (UHMWPE), a type of composite material. In addition, this study applied a multi-friction method in which the internal structure where frictional force is generated is laminated in several layers. To verify the performance of the developed multi-friction damper, this study performed a characteristic analysis test for the basic physical properties, wear characteristics, and disc springs of the material. As a result of the wear test, the mass reduction rate of UHMWPE was 0.003%, which showed the best performance among the friction materials based on composite materials. Regarding the disc spring, this study secured the design basic data from the finite element analysis and experimental test results. Moreover, to confirm the quality stability of the developed multi-friction damper, this study performed an seismic load test on the damping device and the friction force change according to the torque value. The quality performance test result showed a linear frictional force change according to the torque value adjustment. As a result of the seismic load test, the allowable error of the friction damper was less than 15%, which is the standard required by the design standards, so it satisfies the requirements for seismic reinforcement devices.

• The Journal of the Acoustical Society of Korea
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• v.40 no.6
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• pp.615-625
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• 2021

Prior to proposing appropriate standard for subway station platform, this study conducted field measurements to examine characteristics of room acoustics on platform of two subway stations. As a result of analyzing the longitudinal length of the platform, Sound Pressure Level (SPL) decreased (maximum difference : 14 dB), Reverberation Time (RT) tended to increase (maximum difference of 0.8 s ~ 1.5 s), and C50 and D50 were decreased (maximum difference: 5.9 dB ~ 9.1 dB and 31.8 % ~ 37.6 %, respectively) as measurement positions moved away from the sound source. The Interaural Cross-correlation Coefficient (IACC) did not show clear tendency, but it was lower than 0.3 in entire points. It is judged that the subway platform has non-uniform sound field characteristics due to various combinations of direct and reflective sound even though it is finished with a strong reflective material.This indicates that the room acoustic characteristics of the near and far sound field are clearly expressed depending on the source-receiver distances in the subway platform having a long flat shape with a low height compared to the length.Therefore, detailed architectural and electric acoustic design based on the characteristics of each location of speaker and sound receiver in the platform is required for an acoustic design with clear sound information at all positions of the platform.

• Journal of Nutrition and Health
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• v.56 no.4
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• pp.404-418
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• 2023

Purpose: This study aimed to analyze the trends in kimchi, vegetable, and fruit consumption among the Korean population and identify the factors associated with this consumption. The goal was to provide fundamental data for developing appropriate guidelines to increase kimchi consumption by understanding its characteristics. Methods: The analysis utilized data from the Korea National Health and Nutrition Examination Survey (KNHANES) conducted between 1998 and 2020. A total of 81,680 adults, aged 30 years or older, were included in the trend analysis. For the analysis of factors associated with kimchi, vegetable, and fruit intake, a subgroup of 22,122 adults aged 30 years or older from the KNHANES (2016-2020) was divided into two groups: 30-64 years old and 65 years old or older. Since the KNHANES data employed a complex sampling design, the statistical analysis was conducted using the appropriate complex sampling design method. Results: The overall consumption of kimchi exhibited a declining trend among both men and women. Specifically, there was a significant decline in the intake of baechu kimchi among both genders. The decline in kimchi consumption above the standard was associated with a decrease in meal frequency and an increase in the frequency of eating alone. However, the patterns for unsalted vegetables and fruits differed compared to kimchi. Conclusion: In this study, there was a decline in kimchi consumption among both men and women, and the potential factors associated with this trend included Westernized dietary habits, the presence of a spouse who influenced dietary habits, and an increased frequency of solitary dining due to the rise in single-person households. Therefore, it is necessary to develop dietary guidelines that consider these factors.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.2090-2100
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• 2011

Railway rail fastening system is the critical device which gives big influences to not only the vehicle driving stability and the orbit's structural stability against the impulsive load, but also the noise vibration and the ride comfort. As a part of the low-carbon green growth, the importance of the railroad industry is getting highlights on its excellent energy-efficiency and eco-friendliness. However, so far the Korea's domestic rail fastening system technology is not so good and the technical reliance to abroad is very heavy. In this study, we conducted comparative analysis on the rail fastening system with new and used one of the same type. And those systems are imported by Seoul Metro and are being used by it. With this basis, we developed the components and the materials and then, established the durability assessment methods appropriate to the Korean domestic circumstances. And through the reliability qualification test on the 7 parts of the rail fastening system, we've improved the reliability and guaranteed the 15 years of service lifetime. ($B_{10}Life15$) Establishment and standardization of Reliability Standard on the parts of the rail fastening system such as anti-vibration pads, guide-plate, screw spike made it possible to perform the internationally fair assessment. And it is thought that we can satisfy the manufactures' and consumers' needs of cost-cutting and qualification security by shortening of assessment period on rail fastening system.

• KIEAE Journal
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• v.11 no.5
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• pp.107-117
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• 2011

This paper aims to analyze architectural planning factors that could contribute to reductions in electricity consumption in the household of apartments, to apply energy saving methods at the design phase. These six architectural planning factors were orientation, building type (flat, tower block), standard floor access type (corridor access type, stair case type, EV hall access type), household location (floor), household opening type (one side opening, right angle opening, two sides opening or three sides opening), and bay on the facade (one bay, two bays, three bays, four bays), and these were derived from literature review. Household electricity consumption data were gathered from 2168 households with a total area of 135~150$m^2$ of 6 apartment complexes over 1000 households in Seoul. The annual characteristics of electricity consumption according to architectural planning factors were analyzed. And, variances between groups with respect to the mean of summer, winter, and annual electricity consumption according to each architectural planning factors were analyzed using ANOVA and t-test. The results showed that an annual electric energy saving of over 1000kWh was facilitated by these planning factors. In addition, high energy efficiency architectural planning factors based on the analysis were as follows: southwest orientation, flat type, corridor access type and staircase type, household loation below the 20th floor, two sides opening and three sides opening, and 2 bays and 3 bays.

• Journal of the Institute of Convergence Signal Processing
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• v.14 no.2
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• pp.77-81
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• 2013

The international standard AIS, which stands for the safety of ship navigation and vessel traffic management, provides 27 messages to exchange the navigational information of ship. Among 27 messages, message ID 6 and 8 are defined as the binary data format to exchange application specific information and are classified into IFM for international use and RFM for national or regional use. Since international standards are based on English, there have been some needs to exchange data in Hangul text for vessel traffic management to correct the static and dynamic ships' information. In this paper, I analyze international standards to provide a Hangul text messaging service based on RFM and propose a RFM message and a simple protocol to correct information of a ship.

• Journal of the Korean GEO-environmental Society
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• v.21 no.12
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• pp.11-16
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• 2020

It is necessary to assess the proper performance of the existing rockfall prevention net in order to minimize the damage to human lives and property in the event of rockfall. However, there is no standard for performance evaluation of rockfall prevention net in Korea, and only the design of rockfall prevention net exists by calculating energy that can be absorbed energy. Therefore, laboratory pullout test was conducted for the performance evaluation of the rockfall prevention net, cuts and load-displacement characteristics of the PVC coating net used in the laboratory pullout test are determined to identify the performance of the rockfall prevention net.