• Investigative Magnetic Resonance Imaging
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• v.22 no.3
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• pp.141-149
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• 2018

Purpose: The purpose of this study is to develop a simple method to measure magnetic susceptibility of arbitrarily shaped materials through MR imaging and numerical modeling. Materials and Methods: Our 3D printed phantom consists of a lower compartment filled with a gel (gel part) and an upper compartment for placing a susceptibility object (object part). The $B_0$ maps of the gel with and without the object were reconstructed from phase images obtained in a 3T MRI scanner. Then, their difference was compared with a numerically modeled $B_0$ map based on the geometry of the object, obtained by a separate MRI scan of the object possibly immersed in an MR-visible liquid. The susceptibility of the object was determined by a least-squares fit. Results: A total of 18 solid and liquid samples were tested, with measured susceptibility values in the range of -12.6 to 28.28 ppm. To confirm accuracy of the method, independently obtained reference values were compared with measured susceptibility when possible. The comparison revealed that our method can determine susceptibility within approximately 5%, likely limited by the object shape modeling error. Conclusion: The proposed gel-phantom-based susceptibility measurement may be used to effectively measure magnetic susceptibility of MR-compatible samples with an arbitrary shape, and can enable development of various MR engineering parts as well as test biological tissue specimens.

• Water for future
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• v.13 no.4
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• pp.41-50
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• 1980

The prupose of this study are the theoretical examination of Gamma distribution function and its application to hydraulic engineering, that is studying the simulation of monthly streamflow by the Gamma distribtution function model(Gamma Model) based on Monte Carlo technique. In the analysis, monthly streamflow data in the Nak Dong River, the Han River, and the Keum River were used and the data were changed to modular coefficient in order to make the analysis convenient. At first, the fitness of monthly streamflow to 2-Parameter Gamma distribution was tested by Chi-square and Kolmogrov-Smironov test, by which it was found the monthly streamflow were fit well to this Gamma distribution function. Then, the Gamma Model based on the Gamma distribution and Monte Carlo Method was used in the simulation of monthly streamflow, and simulateddata showed that all their stastical characteristics were preserved well in the simulation. Consequently, it can be concluded that the Gamma Model is suitable for the simulation of monthly streamflow series directly by using the Mote Carlo technique.

• Journal of Information Processing Systems
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• v.10 no.3
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• pp.395-411
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• 2014

Temporal medical data is often collected during patient treatments that require personal analysis. Each observation recorded in the temporal medical data is associated with measurements and time treatments. A major problem in the analysis of temporal medical data are the missing values that are caused, for example, by patients dropping out of a study before completion. Therefore, the imputation of missing data is an important step during pre-processing and can provide useful information before the data is mined. For each patient and each variable, this imputation replaces the missing data with a value drawn from an estimated distribution of that variable. In this paper, we propose a new method, called Newton's finite divided difference polynomial interpolation with condition order degree, for dealing with missing values in temporal medical data related to obesity. We compared the new imputation method with three existing subspace estimation techniques, including the k-nearest neighbor, local least squares, and natural cubic spline approaches. The performance of each approach was then evaluated by using the normalized root mean square error and the statistically significant test results. The experimental results have demonstrated that the proposed method provides the best fit with the smallest error and is more accurate than the other methods.

• The Journal of the Korea Contents Association
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• v.6 no.12
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• pp.59-70
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• 2006

Since communication systems software is very large and complex, it requires component based architecture for software reusability, hardware transparency, high performance, and easy software reconstruction in different applications. In order to meet these requirements, we analyze performance and inter-process communication techniques of existing CORBA IIOP, and designed a shared memory-based CORBA inter-ORB protocol that would best fit for communication systems software. The designed protocol supports the same interface and can minimize the message transfer overhead in the same host environment. The test results of our protocol compared with other protocols show that the performance is increased by about 15%-200%. We are thus assumed that our protocol can be used in developing CORBA-based component software architecture for communication systems.

• Journal of Distribution Science
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• v.12 no.9
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• pp.95-99
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• 2014

Purpose - This study aims to develop and empirically test a multi-dimensional service convenience scale with the dimensions and measurement items of service convenience perceived by Korean consumers in retail contexts. Research design, data, and methodology - The study adopts the framework suggested by Berry et al. (2002) and conceptualizes service convenience as a second-order reflective construct comprising 31 items. Three department store chains (Hyundai, Lotte, and Shinsegae) and three discount store chains (E-mart, Homeplus, and Lotte Mart) were involved 510 valid responses were used for the empirical testing. Results - The measurement model is acceptable for internal consistency, convergent validity, and discriminant validity. Further, the structural model results show that service convenience is positively related to satisfaction. Results of the rival model comparison indicate that the proposed second-order factor model provides a better fit to the data than both the five-factor and the one-factor model. Conclusions - The multi-dimensional, second-order conceptualization of service convenience is robustly supported. This study provides psychometrically valid scales to measure service convenience in retail contexts as conceptualized by Berry et al. (2002).

• Journal of Distribution Science
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• v.17 no.9
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• pp.35-45
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• 2019

Purpose - This study analyzes the relationship between inter-function coordination variables, competitor, customer and innovation orientation that has been developed by Narver & Slater (1990), also known as Market Orientation Strategy on SME Sutera's marketing performance, through direct and indirect effect relationships. Research design, data, and methodology - This study uses a sample of 168 respondents who are silk SME entrepreneurs in eleven Silk Craftsman sub-districts in Wajo Regency - South Sulawesi Province, Indonesia. Data collection using a questionnaire with a period between January - June 2019. Data analysis use PLS. The stages of testing the results of analysis go through several stages: the first stage, analysis of variable descriptions, the goodness of fit model (AVE, CR, Cronbach Alpha, R²) and hypothesis test. Results and Findings - From the fifteen hypothesis by direct and indirect effect state six hypothesis are rejected and eleven hypothesis are accepted. Overall, the concepts of Resource Based View theory (RBV) and Structure-Conduct- Performance theory (SCP) also provide a strategic picture for businessmen related to product innovation and service innovation and the urgency of regeneration in order to maintain the continuity of superior products in the future.

• Journal of Korean Society of Rural Planning
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• v.15 no.4
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• pp.59-74
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• 2009

This study reviews and modifies general IS success models to find success factors of WIS(Web-based Information Systems) and to confirm the relationship between WIS success and user's satisfaction of web use. A WISSM(Web-based Information Success Model extended to include EQ(E-Quality) is developed to anticipate user's intention to use Web-based Agricultural Information System and fit into the survey data from 252 WIS users of RDA(Rural Development Administration). PLS is applied to estimate a structural model based on EQ-WISSM to test hypotheses including 1) users reach a high level of intention to use Web-based Information Systems when they feel a high level of interactivity among an 'E-Quality', 'Decision Making Support Satisfaction' and 'Task Support Satisfaction', and E-Quality boosts intention to use Web-based Information Systems. The results show high path coefficients and $R^2$ values and find followings; First, the EQ-WISSM explains the user's intention to use WAIS quite well. Second, E-Quality can be used well in web-based IS environment to predict IS Success. Finally, this research finds the importance of 'Task Support Satisfaction' as a mediator between 'Decision Making Support Satisfaction', 'E-Quality' and 'Intention to Use'.

• Transactions of Materials Processing
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• v.26 no.6
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• pp.341-347
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• 2017

Flexibly-reconfigurable roll forming (FRRF) is a novel sheet metal forming technology conducive to produce multi-curvature surfaces by controlling strain distribution along longitudinal direction. Reconfigurable rollers could be arranged to implement a kind of punch die set. By utilizing these reconfigurable rollers, desired curved surface can be formed. In FRRF process, three-dimensional surface is formed from two-dimensional curve. Thus, it is difficult to predict the forming result. In this study, a regression analysis was suggested to construct a predictive model for a longitudinal curvature of FRRF process. To facilitate investigation, input parameters affecting the longitudinal curvature of FRRF were determined as maximum compression value, curvature radius in the transverse direction, and initial blank width. Three-factor three-level full factorial experimental design was utilized and 27 experiments using FRRF apparatus were performed to obtain sample data of the regression model. Regression analysis was carried out using experimental results as sample data. The model used for regression analysis was a quadratic nonlinear regression model. Determination factor and root mean square root error were calculated to confirm the conformity of this model. Through goodness of fit test, this regression predictive model was verified.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.6
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• pp.626-631
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• 2012

In this study, fatigue life of the motor block bracket units for KTX-Sancheon trains was assessed. Design evaluation for railway structures was performed based on the UIC 566 regulation, and test and evaluation of fatigue life in welded parts was performed in accordance with standard ERRI B 12/RP17 and ERRI B 12/RP60. The actual vehicle dynamic stress testing was executed in KTX-Sancheon service line with the service operating speed. The dynamic stress was measured with commercial data acquisition system (MGC plus). The cumulative damage was evaluated by applying standard BS 7608 - Class F and cycle counting was used rain-flow counting method. As a result, the motor block bracket units for KTX-Sancheon trains was designed to fit the regulation and the safety of fatigue life for 30 years, assuming that KTX-Sancheon trains travels 600,000km annually, were confirmed under current operating conditions.

• Journal of Korean Society of Water and Wastewater
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• v.25 no.2
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• pp.141-152
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• 2011

In this study, we extracted effective factors of pipe burst from the status data of water asset, operating data of pressure, volume and etc. and 7 years' pipe burst and repair records. The extracted factors were sorted by each attribution and then a statistical analysis was performed to generate a pipe burst probability function using the logistic regression model. As the result, material, diameter, length, laying year, pressure and road width affected to pipe burst significantly. Especially, in case of small diameter, laying year was most effective factor and in case of steel pipe, external loading was main cause of burst, and in case of cast iron, PE, PC, HP pipes, the deterioration of joint was main cause. The other side, as a result of Hosmer-Lemeshow goodness of fit test the models are turned out significant statistically. Also the classification criteria were determined to minimize the total cost from classification errors, when the predicted probability was more than 18% this pipe could have a chance of burst.