• 디지털산업정보학회논문지
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• 제16권3호
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• pp.1-11
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• 2020

In this paper, we describe about the user terminal tagging-based embarkation/disembarkation management system and embarkation/disembarkation management method using this system. The system authenticates the validity of the user and on whether to board on the ship by tagging the user's terminal which the boarding reservation was made by using the management terminal provided in the ship. The system identifies on whether the user disembark in the ship by tagging the user's terminal. In the event of ship accident, it is easy to figure out the user and manage the non-contact boarding and disembarking. Therefore, we design the embarkation/disembarkation management system based on user's terminal tagging on the terminal provided in the ship and embarkation/disembarkation management method using this system. User terminal tagging can solve the problem of manpower required for the management of embarkation and disembarkation, the problem of requiring time to confirm the match between the reservation and the passenger, and the problem of increase of the possibility on the spread of infectious diseases due to face-to-face contact.

• Advances in materials Research
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• 제8권3호
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• pp.155-177
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• 2019

In this paper, a new displacement based high-order shear deformation theory is introduced for the static response of functionally graded sandwich plate with new definition of porosity distribution taking into account composition and the scheme of the sandwich plate. Unlike any other theory, the number of unknown functions involved is only four, as against five in case of other shear deformation theories. The theory presented is variationally consistent, has strong similarity with classical plate theory in many aspects, does not require shear correction factor, and gives rise to transverse shear stress variation such that the transverse shear stresses vary parabolically across the thickness satisfying shear stress free surface conditions. Material properties of FGM layers are assumed to vary continuously across the plate thickness according to either power-law or sigmoid function in terms of the volume fractions of the constituents. The face layers are considered to be FG across each face thickness while the core is made of a ceramic homogeneous layer. Governing equations are derived from the principle of virtual displacements. The closed-form solution of a simply supported rectangular plate subjected to sinusoidal loading has been obtained by using the Navier method. Numerical results are presented to show the effect of the material distribution, the sandwich plate geometry and the porosity on the deflections and stresses of FG sandwich plates. The validity of the present theory is investigated by comparing some of the present results with other published results.

• 대한기계학회논문집A
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• 제20권8호
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• pp.2508-2515
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• 1996

Determination of an optimal feed rate is valuable in the sense of the precision and efficient machining. In this regard, a new surface roughness model for the face milling operation that considered the radial and axal runouts of the inserts in the cutter body was developed. The validity of the model was proved through the cutting experiments, and the model is able to predict the real machined surface roughness exactly with the information of the insert runouts and the cutting conditions. From the estimated surface roughness value, the maximum feed rate that obtains a maximum naterial removal rate under the given surface roughness constraint can be selected by using a bisection method. Therefore, this mehod for optimizing the feed rate can be well applied to the using a bisection method. Therefore, this method for optimizing the feed rate can be well applied to the using selsction of the cutting condition during the NC data generation in CAM.

• 대한조선학회논문집
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• 제46권2호
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• pp.155-164
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• 2009

In this paper, a spectral finite element method for a rectangular sandwich plate with viscoelastic core having the Levy-type boundary conditions has been plated. The sandwich plate consists of two isotropic and elastic face plates with a surfaced-bonded viscoelastic core. For the analysis, the in-plane and transverse energy in the face plates and only shear energy in the core are considered, respectively. To account for the frequency dependent complex shear modulus of the viscoelastic core, the Golla-Hughes-McTavish model is adopted. To evaluate the validity and accuracy of the proposed method, the frequency response function and dynamic responses of the sandwich plate with all edges simply supported subject to an impact load are calculated and compared with those calculated by a finite element method. Though these calculations, it is confirmed that the proposed method is very reliable and efficient one for vibration analysis of a rectangular sandwich plate with viscoelastic core having the Levy-type boundary conditions.

• Steel and Composite Structures
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• 제32권5호
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• pp.611-632
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• 2019

In this work, a four-variable refined plate model is applied to study the thermomechanical bending of two kinds of functionally graded material (FGM) sandwich plates. The sandwich core of one kind is isotropic with the FGM face sheets whereas in the second kind, the sandwich core is FGM with the isotropic and homogeneous face sheets. By considering only four unknown variables, the governing equations are written based on the principle of virtual work and then Navier method is employed to solve these equations. Deflections and stresses of two kinds of FGM sandwich structures are analyzed and discussed. The validity and efficiency of the proposed model is checked by comparing it with various available solutions in the literature. The effects of volume fraction distribution, geometric ratio and thermal load on thermomechanical bending properties of FGM sandwich plate are investigated in detail.

• Advances in nano research
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• 제17권1호
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• pp.19-32
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• 2024

Functionally graded-carbon nanotube (FG-CNT) is expected to be a new generation of materials with a wide range of potential applications in technological fields such as aerospace, defense, energy, and structural industries. In this paper, an exact finite strip method for functionally graded-carbon nanotube sandwich plates is developed using first-order shear deformation theory to get the exact natural frequencies of the plates. The face sheets of the plates are made of FG-CNT with continuous and smooth grading based on the power law index. The equations of motion have been generated based on the Hamilton principle. By extracting the exact stiffness matrix for any strip of the sandwich plate as a non-algebraic function of natural frequencies, it is possible to calculate the exact free vibration frequencies. The accuracy and efficiency of the current method is established by comparing its findings to the results of the literature works. Examples are presented to prove the efficiency of the generated method to deal with various problems, such as the influence of the length-to-height ratio, the power law index, and a core-to-face sheet thickness of the single and multi-span sandwich plates with various boundary conditions on the natural frequencies. The exact results obtained from this analysis can check the validity and accuracy of other numerical methods.

• 한국초등과학교육학회지:초등과학교육
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• 제27권1호
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• pp.42-48
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• 2008

The purpose of this study was to develop an instrument for assessing teachers' awareness of science teaching through analogy (ASTA) and to establish its validity and reliability. Based on the literatures on science teaching with analogies, we constructed 23 survey items. Face validity of the items was established using three science education experts. Through exploratory factor analysis with responses of 35 pre- and 26 inservice elementary school teachers, the instruments were constructed on four subcategories: awareness of analogies in science, use of analogy in teaching and learning, self-efficacy in science knowledge, and knowledge of analogy. The data collected from pre- and in-service elementary teachers demonstrated that overall the teachers' awareness of analogy in science was neutral, which indicated they did not have clear standpoints of science teaching through analogy. Further examination demonstrated that there was no significant difference between pre- and in-service teachers and between two genders. Moreover, there was no significant difference among teachers who preferred either didactic or discovery teaching approaches. We conclude that ASTA test would contribute assessment of teachers' awareness of analogy in science teaching while further examination of the instrument will warrant for its broader use.

• 대한간호학회지
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• 제45권3호
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• pp.323-328
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• 2015

Purpose: The process of designing a questionnaire is complicated. Many questionnaires on nursing phenomena have been developed and used by nursing researchers. The purpose of this paper was to discuss questionnaire design and factors that should be considered when using existing scales. Methods: Methodological issues were discussed, such as factors in the design of questions, steps in developing questionnaires, wording and formatting methods for items, and administrations methods. How to use existing scales, how to facilitate cultural adaptation, and how to prevent socially desirable responding were discussed. Moreover, the triangulation method in questionnaire development was introduced. Results: Steps were recommended for designing questions such as appropriately operationalizing key concepts for the target population, clearly formatting response options, generating items and confirming final items through face or content validity, sufficiently piloting the questionnaire using item analysis, demonstrating reliability and validity, finalizing the scale, and training the administrator. Psychometric properties and cultural equivalence should be evaluated prior to administration when using an existing questionnaire and performing cultural adaptation. Conclusion: In the context of well-defined nursing phenomena, logical and systematic methods will contribute to the development of simple and precise questionnaires.

• 성인간호학회지
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• 제23권2호
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• pp.111-122
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• 2011

Purpose: The aim on this study was to establish the validity, reliability and efficiency of a Pain Self-Report Scale for elderly with dementia and compare these results with an observational pain rating scale. Methods: Study subjects were 136 elderly with dementia who were residents in a nursing home, geriatric hospital, or day care center. The subject's pain was measured by five self-report scales and observational scale. DS-DAT (discomfort scale-dementia of the Alzheimer's type) was used for pain behavior observational measure. Cognitive state was assessed using the MMSE (Mini-Mental State Examination). Results: Observational rating correlated moderately with self-report (r=.225~.585, p<.05) and tended to underestimate pain intensity. Test-retest reliability was high for all five self-report scales, and the correlation between these scales was very strong (r=.735~.856, p<.05). Comprehension rate of VDS (verbal descriptor scale) was 88.3%, and NRS (numeric rating scale) 69.9%, FPS (face pain scale) 66.9%, HVAS (horizontal visual analog scale) and VVAS (vertical visual analog scale) 65.4%. Conclusion: Nurses should not apply observational scales routinely in demented patients as many of these are capable of reporting their own pain. Self-report, the highest standard of pain measurement can be reliably performed in a large proportion of demented elderly.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제23권1호
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• pp.23-45
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• 2020

Many researches proposed different models and concepts for the PCK. It is important to understand its composition. Most studies investigated the development of PCK and its influence on students' learning from the teachers' perspectives. We developed an instrument for assessing middle school students' perceptions of mathematics teachers' PCK (SPOMTPCK) to investigate the nature of PCK. Theoretical claims and empirical research in PCK were used to design questions and sub-scales for the SPOMTPCK. The face validity of the instrument was established by the expert mathematics teachers and students. A questionnaire consisting of 38 items on a five-point Likert-type scale was used for data collection from 799 middle school students. The exploratory factor analyses resulted in the development of a three-factor scale of 17 items that was proved valid and reliable, that is, pedagogical representation, understanding students and curriculum, and encouraging students' engagement. The Cronbach α coefficients of the scale was 0.935, and the Cronbach α coefficient of three factors were ranged from 0.721 to 0.912. The confirmatory factor analysis showed that the questionnaire has good construct validity and the fit indexes are good. MANOVA analysis of variance revealed that the differences in mathematics teachers' PCK identified by students of different school types and grades were statistically significant. It is a validate measurement to evaluate the perceived mathematics teachers' PCK for middle school students.