• Journal of Korea Society of Industrial Information Systems
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• v.17 no.7
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• pp.209-214
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• 2012

RFID(Radio Frequency IDentification) is an emerging technology which brings enormous productivity benefits in applications where objects have to be identified automatically. But despite of RFID's advantage, it is not easy to realize the RFID technology in business world. The failure to read RFID tags is the most urgent problem that should be solved for RFID application. Specially, in metal and liquid material, recognition rate of RFID tag is lower than others. Though some special tags for metal and liquid have been invented, it has not prevalent in business world on account of high price. In this paper, styrofoam pad is suggested to improve recognition rate of RFID tag for metal pipe which is used in fish cultivating industry. We makes experiment using Taguchi method and analyze the effects on styrofoam thickness, attachment location of tag, and angle of antenna.

• Journal of the Korean Institute of Gas
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• v.22 no.2
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• pp.1-20
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• 2018

Despite many measures, still from time to time catastrophic events occur, even after reviewing potential scenarios with HAZID tools. Therefore, it is evident that in order to prevent such events, answering the question: "What can go wrong?" requires more enhanced HAZID tools. Recently, new system based approaches have been proposed, such as STPA (system-theoretic process analysis) and Blended Hazid, but for the time being for several reasons their availability for general use is very limited. However, by making use of available advanced software and technology, traditional HAZID tools can still be improved in degree of completeness of identifying possible hazards and in work time efficiency. The new HAZID methodology proposed here, the Data-based semi-Automatic HAZard IDentification (DAHAZID), seeks to identify possible scenarios with a semi-automated system approach. Based on the two traditional HAZID tools, Hazard Operability (HAZOP) Study and Failure Modes, Effects, and Criticality Analysis (FMECA), the new method will minimize the limitations of each method. This will occur by means of a thorough systematic preparation before the tools are applied. Rather than depending on reading drawings to obtain connectivity information of process system equipment elements, this research is generating and presenting in prepopulated work sheets linked components together with all required information and space to note HAZID results. Next, this method can be integrated with proper guidelines regarding process safer design and hazard analysis. To examine its usefulness, the method will be applied to a case study.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.8
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• pp.1064-1069
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• 2014

The railway signalling system plays an essential role in the headway and routing control for a safe and efficient train operation. The reliable and safe operation of the system is very important because the failure of the railway signalling system can lead to the collision, derailment, or unexpected stop of a train. So far, the conventional wayside signal mode (ATS: Automatic Train Stop) has been generally used as the railway signalling system. However, this system is highly linked to a risk of major accidents resulted from human mistakes such as missing a signal or careless control of train speed. Accordingly, the onboard signal mode (ATC: Automatic Train Control) as an alternative of ATS has been recently introduced and applied to transmit effectively the information on speed control of a train by using computers and communication equipment. In the process of replacing the obsolete signal system, it is necessary to switch over the system while providing passengers with normal services. Therefore, the integration of a railway signaling system compatible for both ATS and ATC and its interface is discussed in this study. In particular, the implementation scenario required for operation planning of the integrated system was designed, and the results as well as effects of its applicability test were also presented.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.3
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• pp.345-356
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• 2013

Numerical simulation on rock cutting by a TBM disc cutter was carried out using SPH (Smoothed Particle Hydrodynamics) code. AUTODYN3D, a commercial software program based on finite element method, was used in this study. The three-dimensional geometry of a disc cutter and a rock specimen were modeled by Lagrange and SPH code respectively. The numerical simulation was carried out for Hwangdeung granite for 10 different cutting conditions. The results of the numerical simulation, i.e. the relation between cutter force and failure behavior, had a good agreement with those from LCM test. The cutter forces measured in the numerical simulation had 10% deviation from the LCM test results. Moreover, the optimum cutter spacing was almost identical with the experimental results. These results indicate that SPH code can be successfully used had applicability for simulation on rock cutting by a TBM disc cutter. However, further study on Lagrange-SPH coupled modelling would be necessary to reduce the computation time.

• Journal of the Korean Society of Safety
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• v.33 no.5
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• pp.141-149
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• 2018

In a PCB factory, there is a corrosive chemical substance supply system that can causes major leakage accidents. These accidents can give rise to shut down the factory and do residents damage that cause enormous loss of properties. To mitigate these risks, it is necessary to provide a chemical disaster prevention system. Moreover, after considering the situation and environment of the production site, it is of great importance to build an optimal chemical accident prevention system by reflecting risk reduction measures from the point of process design and by assessing quantitative risk based on reliability data. However, because there was no established database of the reliability about facilities and equipment that can be used in the domestic, the business site and consulting organization had being used the reliability data such as USA CCPS(Center for Chemical Process Safety). In these days, Korean institutes are studying on reliability data utilization method of quantitative risk assessment for preventing chemical accidents and domestic utilization algorithms and storage bed of reliability data. This study presents samples of reliability database about the chemical substance supply system that constructed from the history data such as failure, maintenance for 10 years at a PCB factory. Also, this work proposes the safety design criteria for supply facilities of corrosive chemical substance by assessing quantitative risk on the basis of the reliability data.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.05a
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• pp.515-517
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• 2018

Access to public facilities such as substations, dams and railway facilities is strictly controlled, and unmanned surveillance equipment has been introduced and operated recently due to the development of IT technology and the government's cost reduction policy. However, if an unmanned surveillance system is broken, surveillance space, information leakage caused by intruders, and damage to facilities may occur. Also, it is necessary to check periodical visit by the manager in order to check the surveillance facilities, which causes additional management costs. In order to solve this problem, we designed a system to check the operation status of the unmanned monitoring facility in real time, attempt to recover automatically when a problem occurs, and notify the administrator of the problem. The designed system consists of an NVR that receives and judges information such as image, sound, and lighting condition, and a control device that detects and restores the state of the unmanned monitoring facility. The system proposed in this paper is expected to contribute to the improvement of the economic efficiency due to the minimization of surveillance space due to the failure of the unmanned monitoring facility and the reduction of the inspection cost.

• Journal of Applied Reliability
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• v.14 no.2
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• pp.129-136
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• 2014

Reliability test is focusing to detect the unexpected reliability failure and solve them for the high quality of products. The test data should be used to assess and project the current level of interesting product reliability and so it is very important to have the accurately assessing methodology with test data. There are two type of trend for test data as constant and changing one during testing and this paper shows the difference in the assessing results of these two cases. There is less information how to define the existence of reliability growth rate changing and calculate the parameters of the reliability growth models to make an accurate assessment with such condition, so i established the process and mathematical model to calculate the parameters at such condition to make reliability growth curve with high Goodness of Fit. I validated the new method with the data made from Monte Carlo Simulation and case from Demko (1993). Even the assessed result with the new methodology may be different with the case by case because of very diversity in test condition and testing product quality, but the process and method founded in this research can be applied to any case using Duane and AMSAA model for their test data assessment. I also present the evaluation method to see the effectiveness with new one which is a conventional knowledge and not popular to use, so it is possible to compare the results with the newly presented and conventional method for better business decision.

• Journal of the Microelectronics and Packaging Society
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• v.12 no.1 s.34
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• pp.65-71
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• 2005

At present, Electronic industries push ahead to eliminate the Pb(Lead) -a hazardous material-from all products. Especially, we have performed to select the optimum standard composition of lead free alloy for the application to products for about 3 years from 2000. These days, we have the chance for applying to the mass-production. This project constructed the system for applying the lead free solders on consumer electronic products, which is one of the major products of the LG Electronics. To select the lead free solders with corresponding to the product features, we have passed through the test and applied with Sn-3.0Ag-0.5Cu alloy system to our products, and for the application to the high melting temperature composition, we secured the thermal resistance of the many parts and substrate and optimized the processing conditions. We have operated the temperature cycling test and the high temperature storage test under the standards to confirm the reliability of the products. On these samples, we considered the consequence of our decision by the operating test. For the long life time of the product, we have operated the temperature cycling test at $-45^{\circ}C\;-\;+125^{\circ}C$, 1 cycle/hour, 1000 cycles. Also we have tested the tin whisker growth about lead free plating on lead finish. We have analyzed with the SEM, EDS and any other equipment for confirming the failure mode at the joint and the tin whisker growth on lead free finish.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.3
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• pp.321-331
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• 2003

Seismic fragility analysis (SFA) has been utilized to evaluate the actual seismic capacity of structure and equipment in nuclear power plants (NPP). This paper briefly introduces an improved method for evaluating seismic fragilities of components of NPP's in Korea. Engineering characteristics of small magnitude earthquake spectra recorded in the Korean peninsula during the last several years are also discussed in this paper. Some significant differences between the Newmark's spectra and the recorded spectra as a site-dependent spectra are assessed. Several comparative SFA's have been performed to evaluate the effects of the recorded earthquakes on the seismic capacities of Korean NPP structures. The results showed that SFA using the Newmark's spectra might over estimate the actual seismic capacities of Korean facilities.

• The Journal of Advanced Prosthodontics
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• v.10 no.3
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• pp.252-258
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• 2018

PURPOSE. The purpose of this study was to evaluate the repeatability and matching accuracy between two identical intraoral spectrophotometers. MATERIALS AND METHODS. The maxillary right central incisor, canine, and mandibular left central incisor of each of 30 patients were measured using 2 identical intraoral spectrophotometers with different serial numbers (EasyShade V). The color of each shade tab from 3 shade guides (VITA 3D-Master) was also determined with both devices. All measurements were performed by a single operator. Statistical analyses were performed to verify the repeatability, accuracy, and the differences between the devices with paired t-tests, one-way ANOVA, and intra-class correlation coefficients (ICCs) (${\alpha}=.05$). RESULTS. A high level of measurement repeatability (ICC>0.90) among $L^*$, $a^*$, and $b^*$ color components was observed within and between devices (P<.001). Intra-device matching agreement rates were 80.00% and 81.11%, respectively, while inter-device matching agreement rate was 51.85%. ANOVA revealed no significant different color values within each device, while paired t-test provided significant different color values between both devices. The CIEDE2000 color differences between both devices were $2.28{\pm}1.61$ ${\Delta}E_{00}$ for in-vivo readings. Regarding the clinical matching accuracy of both devices, ${\Delta}E_{00}$ values between teeth and matching shade tabs were $3.05{\pm}1.19$ and $2.86{\pm}1.02$, respectively. CONCLUSION. Although two EasyShade V devices with different serial numbers show high repeatability of CIE $L^*$, $a^*$, and $b^*$ measurements, they could provide different color values and shade for the same tooth.