• Journal of the Computational Structural Engineering Institute of Korea
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• 제30권5호
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• pp.405-413
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• 2017

In this paper, we study the biaxial buckling analysis of nonlocal MEE(magneto-electro-elastic) nano plates based on the first-order shear deformation theory. The in-plane electric and magnetic fields can be ignored for MEE(magneto-electro-elastic) nano plates. According to magneto-electric boundary condition and Maxwell equation, the variation of magnetic and electric potentials along the thickness direction of the MME plate is determined. In order to reformulate the elastic theory of MEE(magneto-electro-elastic) nano-plate, the nonlocal differential constitutive relations of Eringen is used. Using the variational principle, the governing equations of the nonlocal theory are discussed. The relations between nonlocal and local theories are investigated by computational results. Also, the effects of nonlocal parameters, in-plane load directions, and aspect ratio on structural responses are studied. Computational results show the effects of the electric and magnetic potentials. These computational results can be useful in the design and analysis of advanced structures constructed from MEE(magneto-electro-elastic) materials and may be the benchmark test for the future study.

• Journal of the Korean Magnetics Society
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• 제4권3호
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• pp.239-243
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• 1994

$NiFe/TbCo/Si_3N_4$ thin films were fabricated, which can be employed as dualOongitudinal and transverse) biased magnetoresistive elements utilizing surface magnetic exchange at the interface of NiFe/TbCo films. When Tb area percent was 36 % and substrate bias was not applied, magnetic exchange fields of 100~180 Oe were obtained. The thicknesses of NiFe, TbCo and $Si_3N_4$(Protective layer) were $470\;{\AA},\;2400\;{\AA}\;and\;600\;{\AA}$, respectively. Magnetoresistance ratio of 1.45 % was obtained using NiFe films fabricated with 1000 W power and 2.5 mTorr of Ar pressure. The MR ratio of microstructured elements was reduced to 1.31 % and the MR response curves were shown not to saturate due to demagnetizing fields of the elements. When elements were fabricated with $36^{\circ}$ of misalignment with respect to the exchange field direction using films having 150 Oe exchange field, MR response curve was shifted by 85 Oe, and the operating point of the device shifted to the linear region of the response. Also, the Barkhausen noise was eiminated due to longitudinal bias field originating from the exchange field.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제17권4호
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• pp.269-279
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• 2005

Numerical simulations were done using depth integrated ADCIRC model in order to evaluate dynamic response on the inner Saemankeum reservoir due to flood flow and gate operation for the both situations of dike construction and inner development. According to 2-dimensional dynamic flood routing, temporal variation of hydrographs shows sensitive at upstream riverine region while it becomes stable from the center part of the reservoir due to sudden expansion of physical changes. Dynamic response of hydraulic changes such as water surface elevation and velocity on the inner region arises suddenly by gate operation and more rapidly after the inner development than dike construction. Temporal surface fluctuation arises during inflowging of outer sea water and propagates upstream up to 10km to 16km in accordance with inner development status.

• The Journal of the Korea Contents Association
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• 제21권7호
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• pp.404-412
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• 2021

This study was conducted by using the Q research method, one of the qualitative analysis methods, in order to approach consumers' perceptions of processed meat food in an essential and in-depth approach. To this end, Q-sort, which goes through the task of distributing responses by setting P samples by creating a question-and-answer table of positive and negative, was analyzed by using the PC QUANL program and analyzing the Q factor. As a result of the analysis, it was divided into three single types. Type 1 (N= 10) : Preferred types of processed meat food, Type 2 (N= 7) : Types of Pursuing Functionality of Processed Meat Food, Type 3 (N= 4) : The name of the factor was set as the non-preferred type of processed meat food. Each type has different characteristics, and the subjective perception of each factor detected through this analysis can be used as various basic research data in the future, and for the purpose of the study, the perceptions of consumers who use processed meat foods were classified and classified by type. It is to suggest future improvement directions by checking the characteristics of the variables.

• Journal of the Earthquake Engineering Society of Korea
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• 제8권5호통권39호
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• pp.1-14
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• 2004

The seismic behavior of a 1/3-scale model of a two-story unreinforced masonry (URM) structure typically used in constructing low-rise residential buildings in Korea is studied through a shaking table test. The purposes of this study are to investigate seismic behavior and damage patterns of the URM structure that was not engineered against seismic loading and to provide its experimental test results. The test structure was symmetric about the transverse axis but asymmetric to some degrees about longitudinal axis and had a relatively strong diaphragm of concrete slab. The test structure was subjected to a series of differentlevels of earthquake shakings that were applied along the longitudinal direction. The measured dynamic response of the test structure was analyzed in terms of various global parameters (i.e., floor accelerations, base shear, floor displacements and storydrift, and torsional displacements) and correlated with the input table motion. Moreover, different levels of seismic performance were suggested for performance-based design approach. The results of the shaking table test revealed that the shear failure was dominant on a weak side of the 1stfloor while the upper part of the test model remained as a rigid body. Also, it was found that substantial strength and deformation capacity existed after cracking.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제10권4호
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• pp.838-845
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• 2009

The inelastic response characteristics of the standard school buildings depending on selection of hysteresis models are reviewed. Three earthquake records of El-centre, Santa-Monica, Taft and three artificial earthquake records in accordance with Korea standard are used and the inelastic response characteristics such as story shear force, story drift ratio, story displacement, hinge distribution state are reviewed with various hysteresis models. As results, story shear force is increased by maximum 60% according to hysteresis model. And Story drift ratio is increased by maximum 42% according to hysteresis model. And The result with clough model shows the maximum hinge distribution state.

• Journal of Digital Convergence
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• 제14권7호
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• pp.461-473
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• 2016

The purpose of this study is to analyze cognition of applicants about the national sports coaching certificate examination. In order to collect data an online survey was conducted against those who attended the practical and oral examination for the sports coaching certificate. SPSS Version 18.0 was used to analyze frequency of the collected 2,895 samples, the factors of measuring methods in the study, difference of applicants' cognition on the certificate system, and difference of applicants' cognition on the practical and oral examination. Results from this study indicates that the applicants' cognition on the sports coaching certificate system differs according to ages, educational levels, and sports related majors at college, and that the applicants' cognition on the practical and oral examination for the sports coaching certificate is also different according to gender, age, educational level, and sports related majors at college. This study suggests development directions for the future sports coaching system by comprehending of the study results.

• Journal of Aerospace System Engineering
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• 제12권2호
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• pp.30-36
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• 2018

In this study, a small-scaled test system for a tip jet rotor was developed to contribute to the research on unmanned compound rotorcraft. The performance and dynamic characteristics of the tip jet rotor were investigated using the test system. The diameter of the tip jet rotor was set to 2m in consideration of the size of the test site and the pneumatic supply capacity of the. The rotating speed of the rotor was controlled by the pressure of the compressed air. The thrust and forces during the rotor rotation were measured using a load measuring device. A hydraulic actuator was installed for the dynamic test and full-bridge strain gages were attached to the root of each blade to measure the flap, lag, and torsion-wise responses generated when the rotor is excited by the actuator. The performance and dynamic characteristic tests were conducted at various rotor speeds and blade pitches. In order to check the validity of the test results, the results were also compared with the CAMRAD II analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• 제22권5호
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• pp.89-97
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• 2021

The purpose of this study was to examine the awareness of early childhood teachers for early childhood creativity programs using physical computing in an effort to provide future direction for program development. The findings were as follows: First, 43.8 percent of teachers answered they were neutral about the need for these programs, while 40.5 percent replied these programs were necessary. Second, 73.8 percent thought the utilization of physical computing tools would be useful. Third, the largest group thought that the programs should be provided for five-year-olds. Regarding the frequency of programs, once or twice a week were considered most appropriate. Concerning the length of each activity, 20 to 30 minutes was identified as ideal, and study subjects preferred small group activities. In regard to the most effective theme for these programs, tools for daily life were considered best. As for educational content to be included in program planning, scientific inquiry and experiment were viewed as best, followed by the design/ production/utilization of creative works, game and play, and producing and playing musical instruments. Evaluation by a creativity test was chosen as the most desirable evaluation method.

• Spatial Information Research
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• 제11권3호
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• pp.261-274
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• 2003

The effective probability-based tile pre-fetching algorithm and the collaborative cache replacement algorithm are able to reduce the response time for user's requests by transferring tiles which will be used in advance and determining tiles which should be removed from the restrictive cache space of a client based on the future access probabilities in Web GISs(Geographical Information Systems). The Web GISs have multi-level abstracted data for the quick response time when zoom-in and zoom-out queries are requested. But, the previous pre-fetching algorithm is applied on only two-dimensional pre-fetching space, and doesn't consider expanded pre-fetching space for multi-level abstracted data in Web GISs. In this thesis, a probability-based pre-fetching algorithm for multi-level abstracted in Web GISs was proposed. This algorithm expanded the previous two-dimensional pre-fetching space into three-dimensional one for pre-fetching tiles of the upper levels or lower levels. Moreover, we evaluated the effect of the proposed pre-fetching algorithm by using a simulation method. Through the experimental results, the response time for user requests was improved 1.8%∼21.6% on the average. Consequently, in Web GISs with multi-level abstracted data, the proposed pre-fetching algorithm and the collaborative cache replacement algorithm can reduce the response time for user requests substantially.