• Steel and Composite Structures
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• 제28권3호
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• pp.331-347
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• 2018

In this paper history of stresses, strains, radial and circumferential displacements of a functionally graded thick-walled hollow cylinder due to creep phenomenon is investigated. The cylinder is subjected to an arbitrary non-axisymmetric two dimensional thermo-mechanical loading and uniform magnetic field along axial direction. Using equilibrium, strain-displacements and stress-strain relations, the governing differential equations of the problem containing creep strains are derived in terms of radial and circumferential displacements. Since the displacements are varying with time due to creep phenomenon, an analytical solution is not available for these equations. Thus, a semi-analytical procedure based on separation of variables and Fourier series together with a numerical procedure is employed. The numerical results indicate that the non-axisymmetric loading and the material grading index have significant effect on stress redistributions. Moreover, by proper selection of material for any combination of non-axisymmetric loading, one can arrive suitable response for the cylinder to achieve optimal design. With some simplifications, the results are validated with the existing literature.

• 한국수학교육학회지시리즈D:수학교육연구
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• 제5권1호
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• pp.45-58
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• 2001

This study sheds light on the importance of developing creativity in mathematics class by examining the theoretical base of creativity and its relationship to mathematics. The study also reviewed the realities of developing creativity in mathematics courses, and it observed and analyzed the processes in which students and teachers solve the mathematics problems. By doing so, the study examined creative abilities of both students and teachers and suggests what teachers can do to tap the potential of the student. The subjects of the study are two groups of students and one group of mathematics teachers. These groups were required to solve a particular problems. The grading was made based on the mathematical creativity factors. There were marked differences in the ways of the solutions between of the student groups and the teacher group. It was clear that the teachers\\` thinking was limited to routine approaches in solving the given problems. In particular, there was a serious gap in the area of originality. As can be seen from the problem analysis by groups, there was a meaningful difference between the creativity factors of students and those of teachers. This study presented research findings obtained from students who were guided to freely express their creativity under encouragement and concern of their teachers. Thus, teachers should make an effort to break from their routine thinking processes and fixed ideas. In addition, teaching methods and contents should emphasize on development of creativity. Such efforts will surely lead to an outcome that is beneficial to students.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.834-841
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• 1996

Egg production in Korea is becoming automated with a large scale farm. Although many operations in egg production have been and cracks are regraded as a critical problem. A computer vision system was built to generate images of a single , stationary egg. This system includes a CCD camera, a frame grabber board, a personal computer (IBM PC AT 486) and an incandescent back lighting system. Image processing algorithms were developed to inspect egg shell and to sort eggs. Those values of both gray level and area of dark spots in the egg image were used as criteria to detect holes in egg and those values of both area and roundness of dark spots in the egg and those values of both area and roundness of dark spots in the egg image were used to detect cracks in egg. Fro a sample of 300 eggs. this system was able to correctly analyze an egg for the presence of a defect 97.5% of the time. The weights of eggs were found to be linear to both the projected area and the perimeter of eggs v ewed from above. Those two values were used as criteria to sort eggs. Accuracy in grading was found to be 96.7% as compared with results from weight by electronic scale.

• 한방안이비인후피부과학회지
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• 제21권1호
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• pp.113-120
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• 2008

Objective : The purpose of this study was to explore the correlation between efficacy and various factors of the acne patients. Method : We reviewed 30 acne patients who visited Allergy/Derma-cosmetic Clinic at Kyung Hee Neo Medical Center from June, 2006 to December, 2007 and were treated with herbal medicine and acupuncture for 4 weeks. We investigated premenstrual aggravation of acne, facial burning sensation, constipation, Heart Rate Variability(HRV) results and regional distribution of acne. And we evaluated inflammatory acnes according to the Korean Acne Grading System(KAGS). Results & Conclusions : 1. The average age of total patients was 23.0 years old. The most frequent age group was 21-25 years old. Patients evaluated as KAGS Grade 2 were most common. 2. In total patients, inflammatory acne were reduced significantly after 4 weeks of treatment. 3. The result of analysis on premenstrual aggravation of acne, facial burning sensation and constipation, there weren't any difference of treatment results on statistical meaning. 4. The results show that there were significant correlations between the Low Frequency at HRV and the rate of acne reduction. (Pearson correlation = -0.565) 5. If the distribution of acne did not involve the T-zone of the face, chest, or back of the body, inflammatory acne were significantly decreased after 4 weeks of treatment.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1025-1028
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• 2009

Earth and rock fill dam is our typical dam because of their inherent flexibility and adaptability to various fundation conditions. In order to secure structural safety, rockfill materials are used angular particles obtained by blasting parent rock or rounded particles collected from river beds. Concrete-faces rockfill dams(CFRD) and Concrete-faces gravelfill dams(CFGD) have become popular in the last 20 years as s result of their good performance and low cost compared with the rockfill dam. These Dams are also constructed by the materials. A key factor in the design of the dams is the deformations induced during construction and upon reservoir filling. These can be predicted using the stress-strain and strength properties can be adequately define. However the stress-strain properties of rockfill are difficult to determine because the properties are affected by such factors as particle grading, size and shape of particles, stress conditions, and particle crushing. In our study, testing of the behavior of the rockfill materials are essential prerequisites to the realistic analysis and design of the CFGD. This paper deals with laboratory testing of particle crushing among the study.

• 센서학회지
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• 제17권5호
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• pp.387-395
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• 2008

An optic module system is developed adopting multiple colorimetry units for the measurement of multi-pad urinalysis dipsticks. Multiple photometry system instead of moving mechanisms has the advantages of system reliability and simplicity as well as economic aspects due to the recent development of economic color light emitting diodes and stable photo sensors. An integration amplifier with programmable integration time, a current source circuit with selectable and stable current settings were connected through analog multiplexers to thirty light emitting diodes for illumination and ten photo transistors for reading each strip pad. All the circuits are controlled by a microprocessor through a simple set of serial communication commands. The detect ability is eighteen times better than the minimum color difference of the test grading which is 0.013 in urobilinogen in the color space defined in this paper.

• Journal of Biosystems Engineering
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• 제35권6호
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• pp.450-457
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• 2010

Although cherry tomato is one of major vegetables consumed in fresh vegetable market, the quality grading method is mostly dependant on size measurement using drum shape sorting machines. Using Visible/Near-infrared spectroscopy, apparatus to be able to acquire transmittance spectrum data was made and used to estimate firmness, sugar content, and acidity of cherry tomatoes grown at hydroponic and soil culture. Partial least square (PLS) models were performed to predict firmness, sugar content, and acidity for the acquired transmittance spectra. To enhance accuracy of the PLS models, several preprocessing methods were carried out, such as normalization, multiplicative scatter correction (MSC), standard normal variate (SNV), and derivatives, etc. The coefficient of determination ($R^2_p$) and standard error of prediction (SEP) for the prediction of firmness, sugar, and acidity of cherry tomatoes from green to red ripening stages were 0.859 and 1.899 kgf, with a preprocessing of normalization, 0.790 and $0.434^{\circ}Brix$ with a preprocessing of the 1st derivative of Savitzky Golay, and 0.518 and 0.229% with a preprocessing normalization, respectively.

• Journal of Korean Neurosurgical Society
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• 제29권3호
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• pp.360-364
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• 2000

Objective : To investigate the prognostic factors associated with outcome in patients with ossification of posterior longitudinal ligament. Method : During the past 4 years, we have operated on 35 patients with cervical OPLL. Anterior cervical decompression(total or subtotal corpectomy, discectomy, and removal of the OPLL) and interbody fusion with iliac bone were performed in all patients. Results : Eight cases(22.9%) were continuous type, 11(31.4%) segmental, 13(37.1%) Mixed, and 3(8.6%) localized type. Thirty-two patients(91.4%) showed an excellent or good results. Conclusion : These results indicate that surgical treatment should be considerated in case of clinical grading higher than II and the surgical outcome is worse when duration of preoperative symptom is longer and when percentage of spinal narrowing is higher. Anterior cervical decompression and interbody fusion seems to be a better method in patients with lesions limited to one or two level. Age at surgery did not significantly affect the outcom.

• 한국의상디자인학회지
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• 제21권1호
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• pp.115-129
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• 2019

This study aimed to develop methods for technical design education that can be intimately connected to the industrial field. For this, technical design jobs performed in the fields of the domestic and foreign fashion industries and their required competences were examined, and educational methods based on constructivism were proposed. Korean fashion technical designers' works were identified, and then the fashion technical designer's responsibilities and qualifications were collected and analyzed from global employment sites. On the basis of the collection and analysis, hands-on staff members and education experts were interviewed about required competences for the actual business and possible suitable methods for education. The results of research showed that in the case of the US, job systems and relevant duties for technical designers were clearly defined by clothing brands, whereas in Korea, businesses were systematized around vendors, not brands, and as a result the businesses of technical package composition and specification proposals were not performed properly. This study organized the contents of technical design education into fit development and specification, the composition of technical design packages, the evaluation and approval of samples, fit schedule management and fitting, block pattern setting and pattern correction, sewing specifications appropriate for styles and materials, grading, technical terms, and production management. As for the technical design education models, the cognitive apprenticeship model, resource-based learning, the problem-based and anchored model, and the problem-based and resource-based models were proposed.

• Structural Engineering and Mechanics
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• 제85권2호
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• pp.233-246
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• 2023

Bending and buckling analysis of multi-directional porous functionally graded sandwich plate has been performed for two cases namely: FG skin with homogeneous core and FG core with homogeneous skin. The principle of virtual displacements was employed and the solution was obtained using Navier's technique. This theory imposes traction-free boundary conditions on the surfaces and does not require shear correction factors. The validation of the present study has been performed with those available in the literature. The composition of metal-ceramic-based FGM changes in longitudinal and transverse directions according to the power law. Different porosity laws, such as uniform distribution, unevenly and logarithmically uneven distributions were used to mimic the imperfections in the functionally graded material that were introduced during the fabrication process. Several sandwich plates schemes were studied based on the plate's symmetry and the thickness of each layer. The effects of grading parameters and porosity laws on the bending and buckling of sandwich plates were examined.