• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.6
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• pp.61-66
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• 2008

In railroad operation, turnout is the device designed to provide very critical functions of moving the train to the neighboring rail. It's the only movable section among the rail and track equipment, which has a complicated structure and as rapid movement between the wheel and rail during operation is unavoidable, the safety and the vibration caused by the impact load of the passing train becomes always the major concern. Response to rail vibration tends to vary depending on physical properties of the rail, rail base and the ground, making it difficult to estimate the quantitative outcome through the measurement. Thus, experimental or empirical approach, rather than an analytic method, has been more commonly employed to deal with the ground vibration. To predict the vibration of the turnout, an experimental value and the measured values are applied in parallel to the factors with a high degree of uncertainty. This study hence was intended to compare and analyze the vibration values measured at the crossing part of manganese turnout by type of train and turnout and distance, as well as predict the intensity of vibration generated at the crossing part of manganese turnout when tilting train accelerates.

• Journal of Korean Society of Rural Planning
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• v.18 no.2
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• pp.57-68
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• 2012

This study is to suggest the improving methods for rural community centers by analysis of 30 community centers in Samnangjin-eup, Miryang city, Gyeongnam. To fulfill this purpose, the facilities, usable condition and management system were examined. The user needs and level of satisfaction were also investigated through the interviews with 858 citizens. The average size of the centers is $96m^2$, and 73% of them are one-story buildings. Women use the community center more frequently than men in ratio of 6:4. 43.4% of interviewees visit the center 1 or 2 times a month, but on the other hand 27.4% of them use the center almost every day. Recess is surely the main purpose, and health care and community meeting are next two reasons. 67.8% and 72.4% of them are not satisfied with the inside and outside of the community center respectively. The interview results demonstrate that the most important issue is the lack of facilities. To improve the community centers in Samnangjin-eup, first of all, various kinds of indoor and outdoor facilities must be equipped. Secondly, considering the center is the core of rural community life, the qualitative improvement in accommodation is also needed as well as facility diversification. The efficiency of space utilization is another issue. A small piece of land or abandoned space must be utilized. Moreover, it is very critical that the users are mostly seniors and elders, so improvements of facilities will be executed in terms of safety and convenience. Finally, administrative and financial support should be made for the people, so as to maintain the the rural community center on their own.

• Nuclear Engineering and Technology
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• v.35 no.5
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• pp.426-441
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• 2003

A reactor inlet header break experiment, B9401, performed in the RD-14M multi channel test facility was analyzed using RELAP5/MOD3.2 and RELAP5/CANDU[1]. The RELAP5 has been developed for the use in the analysis of the transient behavior of the pressurized water reactor. A recent study showed that the RELAP5 could be feasible even for the simulation of the thermal hydraulic behavior of CANDU reactors. However, some deficiencies in the prediction of fuel sheath temperature and transient behavior in athe headers were identified in the RELAP5 assessments. The RELAP5/CANDU has been developing to resolve the deficiencies in the RELAP5 and to improve the predictability of the thermal-hydraulic behaviors of the CANDU reactors. In the RELAP5/CANDU, critical heat flux model, horizontal flow regime map, heat transfer model in horizontal channel, etc. were modified or added to the RELAP5/MOD3.2. This study aims to identify the applicability of both codes, in particular, in the multi-channel simulation of the CANDU reactors. The RELAP5/MOD3.2 and the RELAP5/CANDU analyses demonstrate the code's capability to predict reasonably the major phenomena occurred during the transient. The thermal-hydraulic behaviors of both codes are almost identical, however, the RELAP5/CANDU predicts better the heater sheath temperature than the RELAP5/MOD3.2. Pressure differences between headers govern the flow characteristics through the heated sections, particularly after the ECI. In determining header pressure, there are many uncertainties arisen from the complicated effects including steady state pressure distribution. Therefore, it would be concluded that further works are required to reduce these uncertainties, and consequently predict appropriately thermal-hydraulic behaviors in the reactor coolant system during LOCA analyses.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.3
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• pp.509-516
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• 2018

TCP is a well-known communication protocol which is widely used for reliable message transmissions. The urgent mechanism of TCP plays a key role to transmit messages with a high priority. If a high priority message occurs at the transmitting node, the urgent mechanism informs the receiving node about the presence of a high priority message prior to its transmission so that the receiving node can be prepared for handling this message in advance. This implies that the existing urgent mechanism of TCP does not guarantee an immediate or faster delivery of the high priority message itself. Therefore, the ability of priority-based transmission is required on TCP not only to ensure reliable transmissions of normal messages but also to offer a differentiated service according to the priority of message. This paper presents a priority-based transmission algorithm over TCP using a priority queue in a multi-threaded environment. The effectiveness of the proposed algorithm is explored using an experimental setup in which various messages with different priority levels are transmitted.

• Informatization Policy
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• v.18 no.1
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• pp.24-44
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• 2011

The evolution of cloud computing over the past few years is potentially one of the major advances in information technology. However, if cloud computing is to achieve its potential, there needs to be a clear identification and understanding of the various issues involved, both from the perspectives of the providers and the consumers of the technology. While a lot of research is currently taking place in the technology itself, there is an equally urgent need for understanding the business-related issues surrounding cloud computing service. As more and more information on individuals and companies are placed in the cloud service, concerns are beginning to grow about just how safe and reliable an environment it is. For successful implementation of cloud services, it is necessary to establish the certification systems to ensure the safety and reliability of cloud services. This paper provides a safe and reliable framework for cloud service certification systems. In order to develop it, the critical issues related to service quality and certification of cloud services have been identified and the systematic framework for certification systems of cloud services and service provider domains have been developed. An evaluation method for the developed certification systems is also proposed.

• The Transactions of the Korea Information Processing Society
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• v.2 no.1
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• pp.95-105
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• 1995

An appendix to the MAP 3.0 specification notes that there are primary advantages to use of fiber optics : noise immunity, ability to run in difficult electrical environments, safety and high data rates. All of these may be quite useful in various manufacturing environments. In this paper, we study on construction schmes for a fiber-based 802.4 MAP system including the use of both bus and star topologies. We suggest passive star network and FDDI network for manufacturing environment. And then, we propose the FDDI protocol including the use a dual ring topology running at 100 Mbps to physical and datalink layer of MAT specification and analysis it's protocol and topology for abilities in manufacturing environments, We evaluate about applications service, time-critical processing and topology of two models in manufacturing environment.

• KIISE Transactions on Computing Practices
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• v.22 no.3
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• pp.145-150
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• 2016

Finding the exact location of faults in a program requires enormous time and effort. Several fault localization methods based on control flows of a program have been studied for decades. Unfortunately, these methods are not applicable to programs based on data-flow languages. A recently proposed mutation-based fault localization method is applicable to data-flow languages, as well as control-flow languages. However, there are no studies on the effectiveness of the mutation-based fault localization method for data-flow based programs. In this paper, we provided an experimental case study to evaluate the effectiveness of mutation-based fault localization on programs implemented in Function Block Diagram (FBD), a widely used data-flow based language in safety-critical systems implementation. We analyzed several real faults in the implementation of FBD programs of a nuclear reactor protection system, and evaluated the mutation-based fault localization effectiveness for each fault.

• International Journal of Highway Engineering
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• v.18 no.5
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• pp.105-115
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• 2016

PURPOSES : This study was initiated to analyze the characteristics of bus traffic accidents, by bus types, using the decision tree in order to establish customized safety alternatives by bus types, including the intra-city bus, rural area bus, and inter-city bus. METHODS : In this study, the major elements involved in bus traffic accidents were identified using decision trees and CHAID algorithm. The decision tree was used to identify the characteristics of major elements influencing bus traffic accidents. In addition, the CHAID algorithm was applied to branch the decision trees. RESULTS : The number of casualties and severe injuries are high in bus accidents involving pedestrians, bicycles, motorcycles, etc. In the case of light injury caused by bus accidents, different results are found. In the case of intra-city bus accidents, the probability of light injury is of 77.2% when boarding a non-owned car and breaching of duty to drive safely are involved. In the case of rural area bus accidents, the elements showing the highest probability of light injury are boarding an owned car, vehicle-to-vehicle accidents, and breaching of duty to drive safely. In the case of intra-city bus accidents, boarding owned car, streets, and vehicle-to-vehicle accidents work as the critical elements. CONCLUSIONS : In this study, the bus accident data were categorized by bus types, and then the influential elements were identified using decision trees. As a result, the characteristics of bus accidents were found to be different depending on bus types. The findings in this study are expected to be utilized in establishing effective alternatives to reduce bus accidents.

• Korean Institute of Interior Design Journal
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• v.24 no.4
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• pp.23-32
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• 2015

This research tried identifying the current status of Gyongrodangs to find solutions to the problems of the oldest old through revitalization of the existing senior centers. With 31 national and public Gyungrodangs in Seocho-gu, Seoul as research subjects, the research contents include a survey of the facilities including main exit doors, living rooms and lounges, kitchens, and rest rooms in the Gyungrodangs by the checklist, and as the research tool a laser finder, measuring tapes, and cameras were used. The checklist was used as the research method to investigate main exit doors, living rooms and lounges, kitchens, and rest rooms. Based on the research results, the following conclusions are presented. The safety-related items of the public Gyungrodang facilities were reaching a critical level. They need to equip emergency exit routes, install exit lights and alarm bells, and teach how to use them. After that, the issue of rest room would be raised; the oldest old had difficulty in using the rest room with no consideration of universal design(UD), so installation of grab bars is needed around toilets, washstands, and urinals. Besides them, although absence of the western style furniture without consideration of users' ages caused inconvenience of using, there are no solutions due to the limited space. Unnecessary equipment such as treadmills which only occupy spaces without users should be thrown away and replaced with the furniture people would use like tables with supplement of furnitures to lie down and rest. Overall, the current Gyongrodang Facilities lack systems and need standardized management, in which the checklist this researcher developed and used in evaluating the present conditions could be recommended. It is expected that the evaluation system of senior centers would be arranged through this checklist, so that systematic service supply could be possible in the better facility environment.

• Membrane Journal
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• v.26 no.4
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• pp.310-317
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• 2016

Lithium ion secondary battery (LISB) is an energy conversion system operated via charging-discharging cycle based on Lithium ion migration. LISB has a lot of advantages such as high energy density, low self-discharge rate, and a relatively high lifetime. Recently, increasing demands of electric vehicles have been encouraging the development of LISB with high capacity. Unfortunately, it causes some critical safety issues. It includes dendrite formation on negative electrode, resulting in electric shortage problems and battery explosion. Also, the elevated temperatures occurred during the LISB operation induces thermal shrinkage of polyolefin (e.g., polyethylene and polypropylene) separators. Consequently, the low thermal stability leads to decay of LISB performances and the reduction of lifetime. In this study, sulfonated poly (arylene ether sulfone) (SPAES) random copolymers were used as key materials to prepare polyolefin pore-filling separator. The resulting separators were evaluated in the term of metal ion chelation capability associated with dendrite formation, $Li^+$ ion conductivity and thermal durability.