• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.189-194
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• 2002

Many researches in the past have shown that a majority initial cracking in concrete are caused during early age period. Therefore, the close examination of early age concrete behavior under various stress conditions is necessary to fully understand the cracking mechanism of concrete. In this study early age cement paste specimen is axially strained up to 20% of its original length by laterally reinforcing it. This type of test is called "Tube Squash Test" and has been previously used to apply up to 50% axial strain on concrete. Microscopic analyses (XRD, FESEM, EDS and DSE/TG) are performed on 20% axially strained early age cement paste specimen. The analysis results show that the microscopic structures and material characteristics of 20% axially strained cement paste remained same as the unstrained cement paste.

• Journal of the Korea Concrete Institute
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• v.14 no.3
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• pp.331-340
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• 2002

In this paper, finite element analysis is applied for simulation of cracks due to restraining autogenous and drying shrinkage at early-age concrete. A micro-level heat hydration model and a shrinkage prediction model along with a moisture diffusion model are adopted for the finite element analysis. Then, an axial restraint test is carried out for concrete specimens containing different amounts of chloride ions to evaluate stress development and cracking due to the restraining shrinkages at early ages. Test results show that the increase of contents of chloride ions increases restrained stress, but does not increase strength. By this increase of shrinkage strain at early-age, time to occur the crack is accelerated. Finally, stress development and cracking of concrete specimens containing different amount of chloride ions we simulated using the finite element analysis. Results of the analysis using the Proposed model are verified by comparison with test results.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.79-80
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• 2010

Age-dependent laboratory tests for a curved composite box girder were carried out to investigate age-dependent effects of concrete on toraional behavior of a curved girder. Time-dependent incremental finite element method predicted the toraional behavior as well as flexural including axial behaviors of the test specimen.

• Communications of Mathematical Education
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• v.28 no.2
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• pp.281-302
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• 2014

The purpose of this paper is to offer a history of golden ratio, the criterion raised by Markowsky, and misconceptions about golden ratio. Markowsky(1992) insists that the golden ratio does not appear in the great pyramid of Khufu. On the contrary, we claim that there exists the golden ration on it. Elementary and middle school text books, and domestic history books deal with the great pyramid of Khuff and the Parthenon by examples of the golden ratio. Text books make many incorrect statements about golden ratio; so in teaching and learning the golden ratio, we recommend the design-composition of dynamic symmetry, for example, industrial design, aerodynamic, architecture design, and screen design. Finally we discuss the axial age how to affect the school mathematics with respect to the subject of Thales and the golden ratio.

• Communications of Mathematical Education
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• v.29 no.2
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• pp.157-196
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• 2015

The purpose of this article is to discuss some of the most commonly repeated misconceptions on the history of mathematics described in the secondary school mathematics textbooks, and recommend that we should include mathematical transculture in the secondary school mathematics. School mathematical history described in the texts reflects the axial age, and deals with mathematical transculture from the ancient Greek into Europe excluding the ancient Egypt, Old Babylonia, and Islamic mathematics. We discuss about them through out the secondary school textbooks and give some alternatives for the historical problems.

• Clinical Pain
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• v.18 no.2
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• pp.82-87
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• 2019

Objective: To evaluate which Korean pain descriptors are frequently used in the patients with neuromusculoskeletal diseases and compare the frequency of Korean pain descriptor according to age, gender, pain pattern and intensity, and clinical diagnosis. Method: Two hundreds sixty nine patients with neuromusculoskeletal diseases were enrolled in this study. The patients were asked to fill out a pain questionnaire using Korean. The Korean pain descriptors were collected and classified according to neurophysiological mechanism. The frequency of Korean pain descriptor was analyzed by age, gender, pain pattern and intensity, and clinical diagnosis. They were divided into axial spine and peripheral joint pain group depending on the location of causal disease and shoulder pain descriptors were divided into intra-articular and bursa group. Results: Among 24 Korean pain descriptors, 'arida' was the most common pain descriptor, followed by 'ssusida' and 'jjireunda'. When the pain descriptors were classified according to neurophysiological mechanism, superficial somatic pain was the most common, followed by deep somatic pain. There was a significant difference in the frequency of the pain descriptor between axial spine and peripheral joint pain group (p=0.007). The pain descriptor 'danggida' was used significantly more in the patients with axial spine pain than peripheral joint pain (p=0.024). However, there was no significant difference in other factors. Conclusion: The patients with neuromusculoskeletal diseases expressed their pain using various Korean pain descriptors with stabbing nature and superficial somatic pain. Our results may be helpful to assess and develop a new Korean pain quality measure in the patients with neuromusculoskeletal diseases.

• Korean Journal of Digital Imaging in Medicine
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• v.17 no.1
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• pp.13-18
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• 2015

Purpose : Skip the repetitive HRCT axial scan in order to reduce the exposure of patients during chest HRCT scan, Helical Scan Data into a reconstructed image, and exposure of the patient change and visually evaluate the usefulness of the HRCT images. Materials and method : Patients were enrolled in the survey are 50 people who underwent chest CT scans of patients who presented to the hospital from January 2015 to March 2015. 50 people surveyed 22 people men and 28 people women people showed an average distribution of 30 to 80 years age was 48 years. 50 patients to Somatom Sensation 64 ch (Siemens) model with 120 kVp tube voltage to a reference mAs tube current to mAs (Care dose, Siemens) as a whole, including the lungs and the chest CT scan was performed. Scan upon each patient CARE dose 4D (Automatic exposure control, Siemens Medical Solution Erlangen, Germany) was to maintain the proper radiation dose scan every cross-section through a device that automatically adjusts the tube current of. CT scan is the rotation time of the Tube slice collimation, slice width 0.6 mm, pitch factor was made under the terms of 1.4. CT scan obtained after the raw data (raw data) to the upper surface of the axial images and coronal images for each slice thickness 1 mm, 5 mm intervals in the high spatial frequency calculation method (hight spatial resolution algorithm, B60 sharp) was the use of the lung window center -500 HU, windows were reconstructed into images in the interval -1000 HU to see. Result : 1. Measure the total value of DLP 50 patients who proceed to chest CT group A (Helical Scan after scan performed with HRCT) and group B (Helical Scan after the HR image reconstruction to the original data) compared with the group divided, analysis As a result of the age, but show little difference for each age group it had a decreased average dose of about 9%. 2. A Radiation read the results of the two Radiologist and a doctor upper lobe and middle lobe of the lung takes effect the visual evaluation is not a big difference between the two images both, depending on the age of the patient, especially if the blood vessels of the lower lobe (A: 3.4, B: 4.6) and bronchi(A: 3.8, B4.7) image shake caused by breathing in anxiety (blurring lead) to the original data (raw data) showed that the reconstructed image is been more useful in diagnostic terms. Conclusion : Scan was confirmed a continuous, rapid motion video to get Helical scan is much lower lobe lung reduction in visual blurring, Helical scan data to not repeat the examination by obtaining HRCT images reorganization reduced the exposure of the patient.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.427-432
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• 2003

An analytical method to predict the flexural behavior of composite girder is presented in which the early-age properties of concrete are specified including maturing of elastic modulus, creep and shrinkage. The time dependent constitutive relation accounting for the early-age concrete properties is derived in an incremental format by expanding the total form of stress-strain relation by the first order Taylor series with respect to the reference time. The sectional analysis calculates the axial and curvature strains based on the force and moment equilibriums. The deflection curve of the box girder approximated by the quadratic polynomial function is calculated by applying to the proper boundary conditions in the consecutive segments. Numerical applications are made for the 3-span double composite steel box girders which is a composite bridge girder filled with concrete at the bottom of the steel box in the negative moment region. The one dimensional finite element analysis results are compared with those of the three dimensional finite element analysis and the analytical method based on the sectional analysis. Close agreement is observed among the three methods.

• The korean journal of orthodontics
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• v.12 no.1
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• pp.27-30
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• 1982

The growth changes in position of upper and lower jaws, incisal inclination in relation to inferior cranial base have been described. Twenty five males was studied quantitavely by means of serial cephalometric reontgenogram from seven to thirteen years of age. The findings seem to warrant the following conclusions: 1. Growth change in anteroposterior relationship of upper and lower jaws to the anterior cranial base showed very little change before eleven years of age but axial inclination of incisal teeth tended to become labiaization in relation to the anterior cranial base. 2. kiter eleven years of age, there wasn't nearly labialization of incisal teeth but jaw prognathism occurred a little in relation to the anterior cranial base.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.147-148
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• 2010

Time-dependent deformation process of concrete was incrementally formulated to take account of the persistent change of creep-inducing stress as well as shrinkage and development of elastic modulus. Three types of experiments were performed including a set of experiments to derive three basic time-dependent equations regarding to shrinkage, creep and development of elastic modulus of concrete, cylindrical concrete specimen with axial reinforcements subjected to a sustained axial load, and RC beam subjected to uniformly distributed load as well as self-weight.