• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.9
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• pp.687-699
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• 2013

IP-based IP-USN overcomes that disadvantages of verify the existence and geographic limits of the sensor by applying a standard technique called 6LoWPAN. However, in terms of the management and cost, The USN node should work for a long period of time without periodic batter replacement. but this solution is insufficient.In this paper, we configure the node using TI's CC2530 that low-power Soc solution and Contiki OS for optimal low-power operation IP-USN and implement the gateway to support connecting IP networks and Sensor networks. In addition, a system implemented to measure and analyze the energy consumption of an independent power supply to look for ways.

• Proceedings of the Korea Information Processing Society Conference
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• 2012.04a
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• pp.986-988
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• 2012

최적의 식물 생장을 위해서는 적절한 수분의 유지가 필수적이며 넓은 지역, 다양한 종류, 고가의 식물의 경우일수록 적절한 수분의 관리를 위한 시스템의 도움이 필요하다. 이를 위해 저가의 센서노드 시스템이 적절한 해결책이 될 수 있으나 일반적인 배터리 기반의 센서노드 시스템을 적용시 배터리 용량 확인 및 교체 등의 유지보수 문제가 대두된다. 본 논문에서는 이러한 유지보수의 문제를 해결하고 식물재배에 도움을 줄 수 있는 자기유지 지원 방식의 정전용량 센싱기반의 수분 모니터링 센서노드를 설계하였다. UHF 기반의 무선 전력 전송의 자기유지 지원 시스템 및 PCB 패턴기반의 정전용량센싱 수분센서와 초저전력 센서노드 시스템으로 구성된다. 센서노드는 한번 송신시 약 0.24 mJ을 소모하며 에너지획득모듈은 에너지 획득 주기마다 약 4 mJ의 에너지를 공급하도록 설계하여 센서동작을 위한 충분한 에너지 마진을 주도록 설계하였다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.11
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• pp.1169-1174
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• 2015

Risk-Risk-based inspection (RBI) has been developed in order to identify risky equipments that can cause major accidents or damages in large-scale plants. This assessment evaluates the equipment's risk, categorizes their priorities based on risk level, and then determines the urgency of their maintenance or allocates maintenance resources. An earlier version of the risk-based assessment software is already installed within the equipment management system; however, the assessment is based on examination by an inspector, and the results can be influenced by his subjective judgment, rather than assessment being based on failure probability. Moreover, the system is housed within a server, which limits the inspector's work space and time, and such a system can be used only on site. In this paper, the development of independent risk-based assessment software is introduced; this software calculates the failure probability by an analytical method, and analyzes the field inspection results, as well as inspection effectiveness. It can also operate on site, since it can be installed on an independent platform, and has the ability to generate an I/O function for the field inspection results regarding the period for an optimum maintenance cycle. This program will provide useful information not only to the field users who are participating in maintenance, but also to the engineers who need to decide whether to extend the lifecycle of the power machinery or replace only specific components.

• Journal of the Korean Society for Nondestructive Testing
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• v.35 no.1
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• pp.61-67
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• 2015

Recently, the initiation of outside diameter stress corrosion cracking (ODSCC) at the tube support plate region of domestic steam generators (SG) with Alloy600 HTMA tubes has been increasing. As a result, SGs with Alloy600 HTMA tubes must be replaced early or are scheduled to be replaced prior to their designed lifetime. ODSCC is one of the biggest threats to the integrity of SG tubes. Therefore, the accurate evaluation of tube integrity to determine ODSCC is needed. Eddy current testing (ECT) is conducted periodically, and its results could be input as parameters for evaluating the integrity of SG tubes. The reliability of an ECT inspection system depends on the performance of the inspection technique and abilty of the analyst. The detection probability and ECT sizing error of degradation are considered to be the performance indices of a nondestructive evaluation (NDE) system. This paper introduces an optimized evaluation method for ECT, as well as the sizing error, including the analyst performance. This study was based on the results of a round robin program in which 10 inspection analysts from 5 different companies participated. The analysis of ECT sizing results was performed using a linear regression model relating the true defect size data to the measured ECT size data.

• Journal of Korean Library and Information Science Society
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• v.48 no.4
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• pp.1-20
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• 2017

The most important identity of public library is local public goods that guarantee access and use of knowledge and information of local residents. To justify this, the library must create an optimal lighting environment. Particularly, since the perception rate of information through vision is over 80%, it is necessary to secure proper illuminance. This study measured the illuminance level of public libraries in Daegu. Based on the results, this study suggested a desirable illuminance level for each space and proposed plans to secure and maintain proper illuminance(prospective revision of the KS A 3011, setting the illuminance range for each space of the local government, replacing the existing lighting fixtures with LED, enhance supervision of lighting management, establishment of basic principles for proper lighting and detailed plans for each space of the library, investigation and reflection on users' complaints and satisfaction, etc.)

• Journal of the Korea Institute of Building Construction
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• v.16 no.2
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• pp.117-123
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• 2016

Glass wool is a material that has been used as a heat insulator in various fields including construction industry. Since it is a nonflammable material, it does not generate toxic gases on fire, and thus public agencies recommend using glass wool as a heat insulator instead of other organic materials. However, repeated drying and wetting cycles can deteriorate thermal property of glass wool due to the shrinkage and reduction in pore size. For this reason, it needs to be replaced periodically, and waste materials are generated. This research aims to utilize waste glass wool as additives for increasing mechanical properties of concrete. According to the experimental results, it was found that glass wool has weak pozzolanic activity, and beneficial effect on both compressive and flexural strength. The optimum amount found in this experimental work was 0.5% volumetric addition to the concrete.

• Journal of the Korean Society of Safety
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• v.38 no.2
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• pp.104-111
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• 2023

Rolling stock maintenance, which focuses on preventive maintenance, is typically implemented considering the potential harm that may be inflicted to passengers in the event of failure. The cost of preventive maintenance throughout the life cycle of a rolling stock is 60%-75% of the initial purchase cost. Therefore, ensuring stability and reducing maintenance costs are essential in terms of economy. In particular, private railroad operators must reduce government support budget by effectively utilizing railroad resources and reducing maintenance costs. Accordingly, this study analyzes the reliability characteristics of components using field data. Moreover, it resolves the problem of determining an economical replacement interval considering the timing of scrapping railroad vehicles. The procedure for determining the optimal replacement interval involves five steps. According to the decision model, the optimal replacement interval for the onboard signal device components of the "A" line train is calculated using field data, such as failure data, preventive maintenance cost, and failure maintenance cost. The field data analysis indicates that the mileage meter is 9 years, which is less than the designed durability of 15 years. Furthermore, a life cycle in which the phase signal has few failures is found to be the same as the actual durability of 15 years.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.48 no.3
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• pp.82-90
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• 2011

Multi-core system is becoming more general with development of microprocessors. Due to this change in performance improvement paradigm, switching conventional single thread applications with multi thread applications. Performance monitoring tools are used to optimize application performance because of complexity in development of multi thread applications. Conventional performance monitoring tools are focused on performance itself rather than user friendliness or real-time support. Real-time performance monitor identify the problem while multi-threaded applications should be performed as well as check real-time operating status of the application. So it can be used as an effective tool compared to non-real-time performance monitor that only with simple performance indicators to find the cause of the problem. In this paper, we propose RMPM(Real-time Multi-core Performance Monitor) which is real-time performance monitoring tool for multi-core system. Observation period is optimized by comparing relation between overhead due to performance evaluation period and accuracy. Our performance monitor shows not only amount of CPU usage of whole system, memory usage, network usage but also aspect of overhead distribution per thread of an application.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.278-280
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• 2012

We are propose the position of the node context-awareness information and the validity of the head node in the path according to the clustering how to elect one of the energy efficiency ECOPS (Energy Conserving Optimal path Schedule) algorithm. Existing LEACH algorithm to elect the head node when the node's energy probability distribution function based on the management of the head node is optional cycle. However, in this case, the distance of the relay node status information including context-awareness parameters does not reflect. These factors are not suitable for the relay node or nodes are included in the probability distribution, if the head node selects occurs. In particular, to solve the problems from the LEACH-based hierarchical clustering algorithms, this study defines location with the status context information and the residual energy factor in choosing topology of the structure adjacent nodes. ECOPS algorithm that contextual information is contributed for head node selection in topology protocols. The proposed ECOPS algorithm has the head node replacement situations from the candidate head node in the optimal path and efficient energy conservation that is the path of the member nodes. The new head node election show as the entire node lifetime and network management technique improving the network lifetime and efficient management the simulation results.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.225-232
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• 2013

In this paper, we introduce a method that can be used to select the position of head node for context-awareness information. The validity of the head node optimal location is saving the energy in the path according to the clustering. It is important how to elect one of the relay node for energy efficiency routing. Existing LEACH algorithm to elect the head node when the node's energy probability distribution function based on the management of the head node is optional cycle. However, in this case, the distance of the relay node status information including context-awareness parameters does not reflect. These factors are not suitable for the relay node or nodes are included in the probability distribution during the head node selects occurs. In particular, to solve the problems from the LEACH-based hierarchical clustering algorithms, this study defines location with the status context information and the residual energy factor in choosing topology of the structure adjacent nodes. The proposed ECOPS (Energy Conserving Optimal path Schedule) algorithm that contextual information is contributed for head node selection in topology protocols. This proposed algorithm has the head node replacement situations from the candidate head node in the optimal path and efficient energy conservation that is the path of the member nodes. The new head node election technique show improving the entire node lifetime and network in management the network from simulation results.