• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2008.06a
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• pp.390-390
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• 2008

In this paper, we have designed and fabricated optical waveguides based on the Mach-Zehnder Interferometer (MZI) for application to sensor. The evanecent-wave sensor based on the MZI principle has sufficiently high sensitivity to measure the change of the refractive index on surface of a waveguide. The waveguides were optimized at a wavelength of 1550 nm and fabricated according to the design rule of 0.45 delta%, which is the difference of refractive index between the core and clad. The fabrication of MZI optical waveguides was performed by a conventional Planar Lightwave Circuit (PLC) fabrication process. The fabricated MZI optical waveguide device was measured. According to the measurement result, the insertion loss of MZI optical waveguide device was below 3.5 dB and the polarization dependent loss (PDL) was within 0.1dB. In addition, we analyzed optical properties of MZI sensor according to the refractive index change of the sensor arm.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.669-676
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• 2018

Transmission system has been well studied since long time and power system techniques of distribution system are more or less derived from transmission system. However, unlike transmission systems, many practical issues are encountered in the distribution system. Considerable amount of error is observed in voltage obtained from the Feeder Remote Terminal Units (FRTUs) measured by the pole mounted PTs along the distribution feeder. Load uncertainty is also an issue in distribution system. Further, penetration of Distributed Generators (DGs) creates voltage variations in the system. Hybrid radial/ loop distribution system also make it complicated to handle distribution system. How these constraints to be handled under Distribution Automation (DAS) environment in order to obtain error free voltage is described in this paper and therefore, a new approach of voltage error correction technique has been proposed. The proposed technique utilizes reliable data from substation and the FRTUs installed in DAS. The proposed technique adopts an iterative process for voltage error correction. It has been tested and proved accurate not only for conventional radial systems but also for loop distribution systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.570-574
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• 1999

In this paper, by using the electrophoresis, preparation of YBCO superconducting wire deposited on metal Ag base wire was studied with its Properties. YBCO Powder could be prepared by solid state reactions with calcining and sintering processes. Superconducting wire prepared on metal Ag wire used as cathode of deposition base could be also fabricated in the YBCO/acetone-dispersed solution to obtain several tens of re thick films. And then it could be used as superconducting wire for measurement after calcination, sintering and oxygen absorption processes. In the process of film deposition, a catalyst I$_2$added into the suspension solution was very useful for preparing thick film of YBCO, and BaF$_2$ of additive material was also necessary for preparing crack-free wire of YBCO superconductor. As a result, YBCO superconducting wire added 2~3wt.% of BaF$_2$\ulcorner with catalyst, 12 had better deposition condition for uniform and dense YBCO wires, and critical current density, Jc was calculated at the value of 1,458A/$\textrm{cm}^2$(more than 10$^{3}$A/$\textrm{cm}^2$ ,77K, o[T]) of 30${\mu}{\textrm}{m}$ thick sample by 4 point prove method.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.52 no.1
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• pp.64-75
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• 2003

Medical image segmentation is the process by which an original image is partitioned into some homogeneous regions like bones, soft tissues, etc. This study demonstrates an automatic medical image segmentation technique based on independent component analysis. Independent component analysis is a generalization of principal component analysis which encodes the higher-order dependencies in the input in addition to the correlations. It extracts statistically independent components from input data. Use of automatic medical image segmentation technique using independent component analysis under the assumption that medical image consists of some statistically independent parts leads to a method that allows for more accurate segmentation of bones from CT data. The result of automatic segmentation using independent component analysis with square test data was evaluated using probability of error(PE) and ultimate measurement accuracy(UMA) value. It was also compared to a general segmentation method using threshold based on sensitivity(True Positive Rate), specificity(False Positive Rate) and mislabelling rate. The evaluation result was done statistical Paired-t test. Most of the results show that the automatic segmentation using independent component analysis has better result than general segmentation using threshold.

• Journal of the Korean Chemical Society
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• v.57 no.2
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• pp.272-278
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• 2013

Extract of ginger has been evaluated as a green inhibitor for the corrosion of steel in sulfide polluted NaCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Potentiodynamic polarization measurements showed that this extract acts as a mixed type inhibitor but mainly inhibits the cathodic reaction. The inhibition efficiency was found to increase with inhibitor concentration reaching to approximately 83.9% using 250 ppm of ginger. Nyquist plots show a single capacitive loop in uninhibited and inhibited solutions. From EFM the causality factors are very close to theoretical values which indicate that the measured data are of good quality. The adsorption process of the studied extract on steel surface obeys Temkin adsorption isotherm. The results obtained from the different electrochemical techniques were in good agreement which prove the validity of these tools in measurement of corrosion rate. Ginger extract has no effect on Escherichia Coli and can be applied safely on waste water treatment plants.

• Management & Information Systems Review
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• v.18
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• pp.41-67
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• 2006

Value Creation issue for customers is emerging from the college education. Most colleges are facing to cope with over-supplied education facility problems against reducing population to apply to enter universities/colleges. The best way to overcome those problems might be to implement the Customer Satisfaction Management Strategy as if they were private firms for making profit. The main purpose in this study is to provide guidelines for CS strategy with a private college. It is focused on designing research plans and searching CS index. The process of this study is as follows; - Introduced the value creation strategy for customers with private colleges. - Proposed the CS management which is very important for enhancing competitive power - Evaluate various models to measure service quality and CSI for college service. - Provided some guidelines to research design of CS according to 6 customer categories. - Proposed some methodologies to apply a service quality measurement model. - Suggested a revised model from SERVPERF to adapt with college customers satisfaction. The result from this study showed that Customer Satisfaction Management would be the most important strategy to cope with confronting difficulties for private college and the revised model from SERVPERF would be an alternative solution. Further study is essential to assure the suggested model is valuable for private colleges because empirical test has not completed yet.

• ETRI Journal
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• v.36 no.6
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• pp.1051-1061
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• 2014

Technological advances made with the development of digital technology and the Internet have led to the emergence and evolution of digital convergence - the integration of media and communications. This, in turn, has led to the creation of the representative broadcast and communication convergence business model (IPTV service). This study examines the consumption patterns and behaviors of IPTV service customers and explores the process of their continuous use of the IPTV service, thereby endeavoring to contribute to the diffusion of digital convergence services. To survey customers' continuous use of the IPTV service, this study first designs a research framework based on an examination of the existing literature on satisfaction, loyalty, and so on. In addition, research is conducted on the switching barrier of the method of consolidating customers' adherence to a given IPTV service by increasing the burden on them, thereby developing a final research model with which to attempt yet another heterogeneous approach. This enables not only an analysis of the causal relationship with antecedent variables but also a measurement of the explanatory contribution of the antecedent variables' sub-variables.

• Structural Monitoring and Maintenance
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• v.2 no.4
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• pp.399-418
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• 2015

Automated damage detection through Structural Health Monitoring (SHM) techniques has become an active area of research in the bridge engineering community but widespread implementation on in-service infrastructure still presents some challenges. In the meantime, visual inspection remains as the most common method for condition assessment even though collected information is highly subjective and certain types of damage can be overlooked by the inspector. In this article, a Frequency Response Functions-based model updating algorithm is evaluated using experimentally collected data from the University of Central Florida (UCF)-Benchmark Structure. A protocol for measurement selection and a regularization technique are presented in this work in order to provide the most well-conditioned model updating scenario for the target structure. The proposed technique is composed of two main stages. First, the initial finite element model (FEM) is calibrated through model updating so that it captures the dynamic signature of the UCF Benchmark Structure in its healthy condition. Second, based upon collected data from the damaged condition, the updating process is repeated on the baseline (healthy) FEM. The difference between the updated parameters from subsequent stages revealed both location and extent of damage in a "blind" scenario, without any previous information about type and location of damage.

• Wind and Structures
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• v.20 no.1
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• pp.75-93
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• 2015

This work is focused on a parametric numerical study of the barrier's bar inclination shelter effect in crosswind scenario. The parametric study combines mesh morphing and design of experiments in automated manner. Radial Basis Functions (RBF) method is used for mesh morphing and Ansys Workbench is used as an automation platform. Wind barrier consists of five bars where each bar angle is parameterized. Design points are defined using the design of experiments (DOE) technique to accurately represent the entire design space. Three-dimensional RANS numerical simulation was utilized with commercial software Ansys Fluent 14.5. In addition to the numerical study, experimental measurement of the aerodynamic forces acting on a vehicle is performed in order to define the critical wind disturbance scenario. The wind barrier optimization method combines morphing, an advanced CFD solver, high performance computing, and process automaters. The goal is to present a parametric aerodynamic simulation methodology for the wind barrier shelter that integrates accuracy and an extended design space in an automated manner. In addition, goal driven optimization is conducted for the most influential parameters for the wind barrier shelter.

• Women's Health Nursing
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• v.19 no.4
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• pp.242-253
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• 2013

Purpose: The purpose of this study was to develop a scale to assess immigrant women's needs for pregnancy and postpartum adaptation and to test the reliability and validity of the scale. Methods: To construct scale items, critical issues and difficulties associated with pregnancy and postpartum adaptation of immigrant women were identified and categorized through a literature review. Fifty-two scale items were constructed, and data for validity and reliability testing was collected with a questionnaire survey from 367 immigrant women. Data were analyzed with descriptive statistics, factor analysis, and reliability coefficients. Results: The final measurement scale to assess immigrant women's pregnancy and postpartum adaptation consisted of 48 items and 7 factors (adaptation to daily activity during pregnancy, cross-cultural understanding and personal respect, understanding of the process of pregnancy and delivery, baby rearing and family support, physical and emotional adaptation after childbirth, nutrition during pregnancy, and sexual life adaptation). The seven factors accounted for 64.26% of the variance, and Cronbach's ${\alpha}$ was .96. Conclusion: The scale developed by this study is a reliable and valid instrument and can be used to assess needs of pregnancy and postpartum adaptation and can be utilized in providing nursing interventions for immigrant women.