• Journal of IKEEE
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• v.22 no.2
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• pp.289-301
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• 2018

IIoT, the IoT technology applied to the industrial field, is being used as a monitoring technology for increasing in production rate and safety of workers. However, monitoring through the construction of IIoT network using Ethernet and RS485 in production lines where dozens to hundreds of machine tools are manufacturing components, have difficulties of infrastructure cost and network flexibility and fluidity. Therefore, in this paper, using IEEE 802.15.4 standard WSN device to construct a Ad-Hoc WSN in the production line. In addition, the transmission period and order of the sensor nodes are set by applying the EtherCAT communication method in which the payload frames are shared by all the sensor nodes. From this, we have overcome the problem of reliability decline and real-time issue due to the packet collision of wireless network and confirmed that it is a wireless network routing method that can be used in the actual industrial field.

• Journal of the Microelectronics and Packaging Society
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• v.11 no.1
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• pp.1-6
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• 2004

The requirements for harsh environment electronic controllers in automotive applications have been steadily becoming more and more stringent. Electronic substrate technologists have been responding to this challenge effectively in an effort to meet the performance, reliability and cost requirements. An effect of the plasma cleaning at the ECM(Engine Control Module) alumina substrate and the intermetallic compound layer between Sn-37wt%Pb solder and pad joints after reflow soldering has been studied. Organic residual carbon layer was removed by the substrate plasma cleaning. So the interfacial adhesive strength was enhanced. As a result of AFM measurement, conductor pad roughness were increased from 304 nm to 330 nm. $Cu_6/Sn_5$ formed during initial reflow process at the interface between TiWN/Cu pad and solder grew by the succeeding reflow process, so the grains became coarse. A cellular-shaped $Ag_3Sn$ was observed at the interface between Ag-Pd conductor pad and solder. The diameters of the $Ag_3Sn$ grains ranged from about 0.1∼0.6 $\mu\textrm{m}$. And a needle-shaped was also observed at the inside of the solder.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.11 s.353
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• pp.8-13
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• 2006

Recent RF SAW filters are made using a HTCC package with a CSP(chip scale Package) technology. This paper describes a development of a new $1.4{\times}1.1\;and\;2.0{\times}1.4mm$ RF SAW liters made by PCB substrate instead of HTCC package, and this technology can reduce the cost of materials down to 40%. We have investigated the multi-layered PCB substrate structures and raw materials to find out the optimal flip-bonding condition between the $LiTaO_3$ wafer and PCB substrates. Also the optimal materials and processing conditions of epoxy laminating film were found out through the experiments which can reduce the bending moment caused by the difference of the thermal expansion between the PCB substrate and laminating film. The new PCB SAW filter shows good electrical and reliability performances with respect to the present SAW filters.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.639-643
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• 1996

The manufacturing system has been changed from labored manual process system, which is managed and operated by managers and operators, to CIMS(Computer Integrated Manufacturing System) for integration of manufacturing, research, development and consumption in the age of diverse customer's needs[6]. However, because it involves the hierarchical system composed of many sub-systems interface and its installation & setup cost is very expensive, CIMS has many difficulties in constructing the durable optimal system that is able to adapt to rapid in-outer circumstance change. So, HMS(Holonic Manufacturing System), the new conceptual manufacturing system having the self-problem-solving and self-organization[11], is instructed to solve these difficulties that it has in these days. The system flexibility in the HMS is able to be ensured, with the integration of human's strong points into mechatronics manufacturing system to reduce interference among sub-systems. In this paper, the manufacturing process rationalization and integration of the assembly line in an automobile industry, has lots of problems in efficiency and productivity, has been studied in an early stage of converting the present state of process system to HMS, which is human-oriented processing system, to improve the line efficiency, system productivity and reliability by using human capability effectively. This paper is derived into the human-oriented & object-oriented holons settlement of the shop floor system composed of processing, assembly and material handling system for the future holonic manufacturing system, which is going to be computer supported control system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.4
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• pp.1651-1664
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• 2013

Precise analysis on deterioration processes of road pavements is not so simple matter due to severe uncertainty originated from a lot of explanatory variables engaged in. For those reasons, most analytical models for pavement deterioration prediction have often preferred to probabilistic approaches than deterministic models. However, the general probabilistic approaches that treat overall characteristics of population or entire sample would not be suitable for providing detail or localized information on their changing process. Considering the aspects, this paper aimed to suggest a stochastic disaggregation method to analyze the localized deterioration speeds and its variances changed by time and condition states. In addition, life expectancies and their uncertainty were estimated by probabilistic algorithm using the disaggregated stochastic process. For an empirical study, pavement inspection data (crack) accumulated from 2003 to 2010 from Korean national highway network was applied. This study can contribute to securing reliability of life cycle cost analysis, which is one of the primary analyses in road asset management, with much advanced deterioration forecasting functions. In addition, it would be meaningful trials as fundamental research for preventive maintenance strategy that demands essential understanding on changing process of the deterioration speed of pavement.

• Structural Monitoring and Maintenance
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• v.1 no.2
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• pp.183-195
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• 2014

Scour is one of the leading causes of overwater bridge failures worldwide. While monitoring systems have already been implemented or are still being developed, they suffer from limitations such as high costs, inaccuracies, and low reliability, among others. Also, most sensors only measure scour depth at one location and near the pier. Thus, the objective is to design a simple, low cost, scour hole topography monitoring system that could better characterize the entire depth, shape, and size of bridge scour holes. The design is based on burying a robust, waterproofed, piezoelectric sensor strip in the streambed. When scour erodes sediments to expose the sensor, flowing water excites it to cause the generation of time-varying voltage signals. An algorithm then takes the time-domain data and maps it to the frequency-domain for identifying the sensor's resonant frequency, which is used for calculating the exposed sensor length or scour depth. Here, three different sets of tests were conducted to validate this new technique. First, a single sensor was tested in ambient air, and its exposed length was varied. Upon verifying the sensing concept, a waterproofed prototype was buried in soil and tested in a tank filled with water. Sensor performance was characterized as soil was manually eroded away, which simulated various scour depths. The results confirmed that sensor resonant frequencies decreased with increasing scour depths. Finally, a network of 11 sensors was configured to form a distributed monitoring system in the lab. Their exposed lengths were adjusted to simulate scour hole formation and evolution. Results showed promise that the proposed sensing system could be scaled up and used for bridge scour topography monitoring.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.4
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• pp.95-104
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• 2013

As global warming and depletion of fossil fuel are considered as urgent problems, the development of electric vehicle (EV) is getting more attention by automobile industry. However, the wide adoption of EVs is not coming yet, because of many issues such as long recharging time and high cost of batteries etc. As an alternative solution to the conventional battery charging EV, the idea of battery exchanging EV is introduced. To realize the battery exchanging business model, one should solve the issues of ownership and reliability of battery. To address such issues, the concept of battery sharing should be considered together with good traceability system. In this study, we studied RFID code structure to provide better visibility and traceability for shared EV batteries. The proposed RFID code and code generation system is based on GRAI-96 of EPCglobal and included factors such as chemical, physical, and manufacturing features. The designed code can be also used as the ID of each battery.

• Journal of the Korea Society of Computer and Information
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• v.16 no.2
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• pp.279-288
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• 2011

The purpose of this research is to develop a standardization model for available stock management process among the entire Enterprise Resource Planning System modules of Automobile Parts Manufacturing Industry. The standardization model system is constructed through the phased method based on the development methodology of information establishment suggested by the Small and Medium Business Administration and Korea Technology and Information Promotion Agency for Small & Medium Enterprises. The standardization model is to develop the process modules of ordering management, storing management, delivering management, and stock management for available stock management process. The study will help the manufacturing business and related IT business which want to construct available stock management process under the ERP system to establish the system more effectively by applying the standardization model and also will provide them with construction availability and reliability. By application of this study results, the businesses will not only prevent the excessive possession of raw materials and products and reserve adequate and steady stock but also will check real-time stock, observe customer due date, decrease over-production and reduce stock cost.

• Journal of the Korea Society of Computer and Information
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• v.16 no.4
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• pp.101-110
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• 2011

A smart grid networks delivers electricity from suppliers to consumers using digital technology with two-way communications to control appliances at consumers' homes to save energy, reduce cost and increase reliability and transparency. Security is critically important for smart grid networks that are usually used for the electric power network and IT environments that are opened to attacks, such as, eavesdroping, replay attacks of abnormal messages, forgery of the messages to name a few. ZigBee has emerged as a strong contender for smart grid networks. ZigBee is used for low data rate and low power wireless network applications. To deploy smart grid networks, the collected information requires protection from an adversary over the network in many cases. The security mechanism should be provided for collecting the information over the network. However, the ZigBee protocol has some security weaknesses. In this paper, these weaknesses are discussed and a method to improve security aspect of the ZigBee protocol is presented along with a comparison of the message complexity of the proposed security protocol with that of the current ZigBee protocol.

• Journal of the Korea Society of Computer and Information
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• v.19 no.12
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• pp.209-218
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• 2014

The more mobile devices consuming web services, the more QoS-aware selection of mobile web services, we need. A QoS(Quality of Service) contract is an agreement between the web service provider and the mobile user that specifies the level of the service quality. Web services users can be assured of the level of the service quality specified by the QoS contract. We propose a broker-based framework for QoS-aware mobile web services selection in this work. Under this architecture, the mobile users can request the web services through the service broker on the wireless networks. The service broker utilizes agents to monitor the web services quality and manages the service quality by notifying the service provider and mobile user of the service contract violation. Reliability, response time, and cost were the metrics used for QoS monitoring. Futhermore mobile users can select a web service best suited for his/her needs through the service broker.