• Steel and Composite Structures
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• v.25 no.4
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• pp.427-442
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• 2017

This paper presents unprecedented damped oscillation behaviours of a precast steel-concrete composite slab panel for track support. The steel-concrete composite slab track is an innovative slab track, a form of ballastless track which is becoming increasingly attractive to asset owners as they seek to reduce lifecycle costs and deal with increasing rail traffic speeds. The slender nature of the slab panel due to its reduced depth of construction makes it susceptible to vibration problems. The aim of the study is driven by the need to address the limited research available to date on the dynamic behaviour of steel-concrete composite slab panels for track support. Free vibration analysis of the track slab has been carried out using ABAQUS. Both undamped and damped eigenfrequencies and eigenmodes have been extracted using the Lancsoz method. The fundamental natural frequencies of the slab panel have been identified together with corresponding mode shapes. To investigate the sensitivity of the natural frequencies and mode shapes, parametric studies have been established, considering concrete strength and mass and steel's modulus of elasticity. This study is the world first to observe crossover phenomena that result in the inversion of the natural orders without interaction. It also reveals that replacement of the steel with aluminium or carbon fibre sheeting can only marginally reduce the natural frequencies of the slab panel.

• Proceedings of the Korea Society for Simulation Conference
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• 2002.11a
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• pp.101-105
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• 2002

In a traditional hierarchical inventory system, direct orders are the only information for inventory management that is exchanged between the firms involved. But due to the rapid development of modern information technology, it becomes possible for the firms to share more information in real time, e.g. demand and inventory status data. And so the term Supply Chain has emerged because it is seen as an important source of competitive advantage. Now it is possible to challenge traditional approaches to inventory management. In the past, one of the de-facto assumptions for inventory management was that the demand pattern follows a specific distribution function. However, it is undesirable to apply this assumption in real situations because the demand information in the supply chain tends to be distorted due to the bullwhip effect in a supply chain. To overcome this weakness, we propose a new solution method using NN (Neural Network). Our method proceeds in three steps. First, we find the patterns of optimal reorder points by analyzing past data. Second. train the NN using these pattern data and finally decide the reorder point. Using simulation experiment, we show that the proposed solution method gives better result than that of traditional research.

• Nuclear Engineering and Technology
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• v.47 no.2
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• pp.219-225
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• 2015

In this paper, a three-dimensional model for the dynamic analysis of a flywheel based on the finite element method is presented. The static structure analysis for the model provides stress and strain distribution cloud charts. The modal analysis provides the basis of dynamic analysis due to its ability to obtain the natural frequencies and the vibration-made vectors of the first 10 orders. The results show the main faults are attrition and cracks, while also indicating the locations and patterns of faults. The harmonic response simulation was performed to gain the vibration response of the flywheel under operation. In this paper, we present a Hilbert-Huang transform (HHT) algorithm for flywheel vibration analysis. The simulation indicated that the proposed flywheel vibration signal analysis method performs well, which means that the method can lay the foundation for the detection and diagnosis in a reactor main coolant pump.

• Nuclear Engineering and Technology
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• v.47 no.2
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• pp.165-175
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• 2015

The application of neutron noise analysis (NNA) to the ex-core neutron detector signal for monitoring the vibration characteristics of a reactor core support barrel (CSB) was investigated. Ex-core flux data were generated by using a nonanalog Monte Carlo neutron transport method in a simulated CSB model where the implicit capture and Russian roulette technique were utilized. First and third order beam and shell modes of CSB vibration were modeled based on parallel processing simulation. A NNA module was developed to analyze the ex-core flux data based on its time variation, normalized power spectral density, normalized cross-power spectral density, coherence, and phase differences. The data were then analyzed with a fuzzy logic module to determine the vibration characteristics. The ex-core neutron signal fluctuation was directly proportional to the CSB's vibration observed at 8Hz and15Hzin the beam mode vibration, and at 8Hz in the shell mode vibration. The coherence result between flux pairs was unity at the vibration peak frequencies. A distinct pattern of phase differences was observed for each of the vibration models. The developed fuzzy logic module demonstrated successful recognition of the vibration frequencies, modes, orders, directions, and phase differences within 0.4 ms for the beam and shell mode vibrations.

• Journal of the Optical Society of Korea
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• v.20 no.1
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• pp.42-54
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• 2016

A hybrid color and grayscale images encryption scheme based on the quaternion Hartley transform (QHT), the two-dimensional (2D) logistic map, the double random phase encoding (DRPE) in gyrator transform (GT) domain and the three-step phase-shifting interferometry (PSI) is presented. First, we propose a new color image processing tool termed as the quaternion Hartley transform, and we develop an efficient method to calculate the QHT of a quaternion matrix. In the presented encryption scheme, the original color and grayscale images are represented by quaternion algebra and processed holistically in a vector manner using QHT. To enhance the security level, a 2D logistic map-based scrambling technique is designed to permute the complex amplitude, which is formed by the components of the QHT-transformed original images. Subsequently, the scrambled data is encoded by the GT-based DRPE system. For the convenience of storage and transmission, the resulting encrypted signal is recorded as the real-valued interferograms using three-step PSI. The parameters of the scrambling method, the GT orders and the two random phase masks form the keys for decryption of the secret images. Simulation results demonstrate that the proposed scheme has high security level and certain robustness against data loss, noise disturbance and some attacks such as chosen plaintext attack.

• Journal of architectural history
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• v.22 no.5
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• pp.7-22
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• 2013

Gimlyong-sa temple has played an important role of Buddhist culture in Gyeongsangdo Provinces(嶺南地域) in the late Joseon Dynasty as the 31st head temple(本山) in the Japanese occupation. There are lots of architectural documentary records remained nevertheless, most of cultural heritages are destroyed by fire in 1997. There were 85 articles in five kinds of books which contained historical achievements of Gimlyong-sa temple and hermitages(Daeseongam(大成庵), Hwajangam(華藏庵), Yangjinam(養眞庵), Geum seondae(金仙臺), Dosoram(兜率庵), Myeongjeogam(明寂庵)). It is possible to understand the five situational peculiarities in the 17~19th century. At the first, they were compiled in 1914 to around 1930 by Kwon Sangro(權相老) to clarify the historical facts. Second, confirmed the formation process of the foundation narrative. Third, the meaning of Seolseondang(設禪堂), Manseru(萬歲樓) and Hyangnojeon(香爐殿) were recorded, it is possible to look at the concept of people at that time. Fourth, the great masters portraits were enshrined in hermitages, not in Gimlyong-sa temple. It means that a hermitage is not for only self-discipline or living but assembly of religious orders(門派). Fifth, Chimgye(枕溪), the great Buddhist clergy and carpenter of Gimlyong-sa, was nationwide active worker in 19th century because he was also in a charge of investment manager for construction.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.15 no.2
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• pp.134-142
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• 2008

Purpose: This study was done to identify satisfaction with the method of evaluating practical skills in fundamental nursing through cellular phone animation self-monitoring and feedback. Method: The participants were 163 first-year student nurses. Data were collected from October 1 to 5 2007 using a structured questionnaire. Results: The average score for satisfaction was 3.65(${\pm}.69$) and the highest score was for the item, "I was pleased to have the opportunity of relearning by looking back at my behaviors through self monitoring" with 4.05(${\pm}.89$). The average score for dissatisfaction was 3.23(${\pm}.90$) and the highest score was "I memorized only orders according to the checklist" with 3.65(${\pm}.97$). The practical tests method showed a significant difference according to motivation for application to college of nursing (F=3.11, p=.047). There was a significant positive correlation between practical education satisfaction and test method (r=.363, p=.000). Conclusion: These findings show that there is a need to develop strategies to improve practical test methods for student nurses.

• Journal of Advanced Marine Engineering and Technology
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• v.9 no.2
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• pp.159-169
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• 1985

The calculation of torsional vibration for marine diesel engine propulsion shafting is normally carried out by equalizing exciting energy to damping energy, or using the dynamic magnifier. But, with these methods, the vibration amplitudes are calculated only for resonance points and vibration amplitudes of other running speeds of engine are determined by the estimation. Recently, many energy-saving ships have been built and on these ships, two-stroke, supercharged, super-long stroke diesel engines which have a small number of cylinders are usually installed. In these cases, the first order critical-torsional vibrations of these engine shaftings appear ordinarily near the MCR speed and the stress amplitudes of their vibration skirts exceed the limit stress defined by the rules of classification society. To predict the above condition in the design stage, the synthesized vibration amplitudes of all orders which are summed up according to their phase angles must be calculated from the drawings of propulsion shaft systems. In this study, a theoretical method to fulfill the above calculation is derived and a computer program is developed according to the derived method. And a shafting system of two-stroke, super-long stroke diesel engine which was installed in a bulk carrier is analyzed with this method. The measured values of this engine shafting are compared with those of calculated results and they show a fairly good agreement.

• Management Science and Financial Engineering
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• v.17 no.2
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• pp.63-84
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• 2011

The ordinary multiple criteria decision making (MCDM) approach requires two types of input, alternative values and criterion weights, and employs two schemes of alternative prioritization, dominance and potential optimality. This paper allows for incomplete information on both types of input and gives rise to the dominance relationships and potential optimality of alternatives. Unlike the earlier studies, we emphasize that incomplete information frequently takes the form of strict inequalities, such as strict orders and strict bounds, rather than weak inequalities. Then the issues of rising importance include: (1) The standard mathematical programming approach to prioritize alternatives cannot be used directly, because the feasible region for the permissible decision parameters becomes an open set. (2) We show that the earlier methods replacing the strict inequalities with weak ones, by employing a small positive number or zeroes, which closes the feasible set, may cause a serious problem and yield unacceptable prioritization results. Therefore, we address these important issues and develop a useful and simple method, without selecting any small value for the strict preference information. Given strict information on both types of decision parameters, we first construct a nonlinear program, transform it into a linear programming equivalent, and finally solve it via a two-stage method. An application is also demonstrated herein.

• Journal of The Korean Association of Information Education
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• v.11 no.4
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• pp.397-406
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• 2007

There are lots of studies going on about internet addiction in a point of view of psychology and sociology. The purpose of this paper is to examine the relation between the internet addiction and the services and functions of internet softwares in a point of view of developing softwares. For this, the first goal is to see the type of the software that used most by elementary school students addicted to internet, and the second is to examine the risk factors of addiction and their priority orders in the services and functions offered by that kind of software. The results of this paper can give instructive informations to every children who use internet and their parents and teachers and software developers.