• Journal of the Korean Geotechnical Society
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• v.23 no.9
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• pp.5-16
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• 2007

The simple linear elastic-perfectly plastic model with soil parameters $s_u,\;E_u$ and n of undrained condition is usually applied to predict the displacement of a constructed diaphragm wall(DW) on soft soils during excavation. However, the application of this soil model for finite element analysis could not interpret the continued increment of the lateral displacement of the DW for the large and deep excavation area both during the elapsed time without activity of excavation and after finishing excavation. To study the characteristic behaviors of soil behind the DW during the periods without excavation, a series of tests on soft Bangkok clay samples are simulated in the same manner as stress condition of soil elements happening behind diaphragm wall by triaxial tests. Three kinds of triaxial tests are carried out in this research: $K_0$ consolidated undrained compression($CK_0U_C$) and $K_0$ consolidated drained/undrained unloading compression with periodic decrement of horizontal pressure($CK_0DUC$ and $CK_0UUC$). The study shows that the shear strength of series $CK_0DUC$ tests is equal to the residual strength of $CK_0UC$ tests. The Young's modulus determined at each decrement step of the horizontal pressure of soil specimen on $CK_0DUC$ tests decreases with increase in the deviator stress. In addition, the slope of Critical State Line of both $CK_0UC$ and $CK_0DUC$ tests is equal. Moreover, the axial and radial strain rates of each decrement of horizontal pressure step of $CK_0DUC$ tests are established with the function of time, a slope of critical state line and a ratio of deviator and mean effective stress. This study shows that the results of the unloading compression triaxial tests can be used to predict the diaphragm wall deflection during excavation.

• Proceedings of the IEEK Conference
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• 2000.06a
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• pp.73-76
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• 2000

In tendency of digitalization, we studied about the purpose of digital modem for MRI spectrometer and advantage of digital modem compared with analog one. We introduce requirements lot designing transmitter of high speed digital modem for MRl spectrometer We also introduce its top-level and mid-level architecture. The transmitter is composed of CPC-P interface block, DUC & DAC block, RF block, master clock generation block, MCU block. Especially, DUC and its control parts are studied in detail. DUC and DAC can operate up to 52MHz and 100Msps, respectively. However we uses 35MHz as master clock and this paper shows its validity through simulations.

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.125.1-125.1
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• 2007

• Proceedings of the Korean Magnestics Society Conference
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• 2007.05a
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• pp.82.2-82.2
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• 2007

• Bulletin of the Korean Mathematical Society
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• v.56 no.2
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• pp.391-397
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• 2019

In this paper, we give a simple proof of the improved Johnson bound for A(n, d), the maximum number of codewords in a binary code of length n and minimum distance d, given by Mounits, Etzion and Litsyn.

• Journal of the Korean Mathematical Society
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• v.58 no.5
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• pp.1279-1298
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• 2021

The aim of this paper is to prove the existence of the global attractor of the Cauchy problem for a semilinear degenerate hyperbolic equation involving strongly degenerate elliptic differential operators. The attractor is characterized as the unstable manifold of the set of stationary points, due to the existence of a Lyapunov functional.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.9
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• pp.467-475
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• 2020

The study aims to investigate factors affecting enterprise's satisfaction and loyalty toward the Social Security's online public services, looking at the case of Thanh Hoa province, Vietnam. This study employs samples with 216 enterprises that use online public system of Thanh Hoa province's Social Security. The research model is closely linked to the SERVQUAL model developed by Parasuraman, Zeithaml and Berry (1988). We propose 23 scales that constitute the quality of service, three scales that constitute Customer Satisfaction and three components that constitute Customer Loyalty. This study use the tool of Exploratory Factor Analysis (EFA), Cronbach's Alpha test, Confirm Factor Analysis (CFA) and Structural Equation Modeling (SEM) in order to address the question of satisfaction and loyalty. The result shows that the factor with the most impact is Reliability, next is Capacity of staffs, Tangibles, Attitude of staffs, and the least impacting factor is Empathy; moreover, the results also show that Satisfaction has a strong impact on Customer Loyalty. The findings of this study suggest that Thanh Hoa province's Social Security should: (i) strengthen the reliability of online service system; (ii) build capacity for staffs; (iii) develop the responsiveness of electronic transactions systems; and (iv) improve the empathy of staffs.

• Computers and Concrete
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• v.31 no.2
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• pp.111-121
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• 2023

The influence of material composition such as aggregate types, addition of supplementary cementitious materials as well as exposed temperature levels have significant impacts on concrete residual mechanical strength properties when exposed to elevated temperature. This study is based on data obtained from literature for fly ash blended concrete produced with natural and recycled concrete aggregates to efficiently develop prediction models for estimating its residual compressive strength after exposure to high temperatures. To achieve this, an extensive database that contains different mix proportions of fly ash blended concrete was gathered from published articles. The specific design variables considered were percentage replacement level of Recycled Concrete Aggregate (RCA) in the mix, fly ash content (FA), Water to Binder Ratio (W/B), and exposed Temperature level. Thereafter, a simplified mathematical equation for the prediction of concrete's residual compressive strength using Gene Expression Programming (GEP) was developed. The relative importance of each variable on the model outputs was also determined through global sensitivity analysis. The GEP model performance was validated using different statistical fitness formulas including R², MSE, RMSE, RAE, and MAE in which high R² values above 0.9 are obtained in both the training and validation phase. The low measured errors (e.g., mean square error and mean absolute error are in the range of 0.0160 - 0.0327 and 0.0912 - 0.1281 MPa, respectively) in the developed model also indicate high efficiency and accuracy of the model in predicting the residual compressive strength of fly ash blended concrete exposed to elevated temperatures.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.10
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• pp.919-927
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• 2020

The study examines the influence of factors on customer satisfaction in hotel services in Thanh Hoa province of Vietnam. In terms of the tangible facilities of hotels, customers appreciate the availability and the full range of equipment and additional services, as the 3-to-5-star hotels in Thanh Hoa province are almost new, built in the last five years - 7 of 13 hotels were built in 2015. In the process of measuring the effect of factors on satisfaction in hotel services there, the researchers conducted exploratory factor analysis, reliability test, correlation and regression to confirm the relationships of factors. Based on a survey of 380 respondents, the test results showed that the proposed factors have positive impacts on consumer satisfaction; they are: perceived quality (including intangible and tangible elements), brand image, perceived value, and customer relationship management. In particular, intangible elements have the strongest influence on customer satisfaction, followed by tangible elements, brand image, perceived value, and finally, customer relationship management. In addition, the study found that foreigners and higher education customers tend to be more satisfied by the hotels than other groups, which helps to suggest important and appropriate solutions for hotel managers in Thanh Hoa province.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.7
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• pp.123-133
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• 2022

This paper explores the key factors influencing the business performance of enterprises, specifically women-owned small and medium enterprises (SMEs) in Vietnam. The extant literature on factors affecting the business performance of women-owned SMEs in Vietnam is still quite scarce. The researchers used a self-administered questionnaire to achieve a sample of 265 female SME owners in Vietnam to find these factors. The obtained data was analyzed by using SPSS 20.0. Cronbach's α test and factor analysis have been carried out to test the reliability of data and validate the hypothesis. The results showed that these enterprises' performances had a significant positive relationship with the business management competencies of the directors of the business, quality of human resources, financial access, socio-cultural factors, and government policy. Also, the study showed no relationship between the enterprise's business network and business performance. The results suggest that female business owners should improve their business management capacity, focusing on training activities to improve the quality of human resources of enterprises. The Government needs policies to support small and medium enterprises in accessing financial and other resources and propagate to reduce gender stereotypes.