• Journal of Oral Medicine and Pain
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• v.20 no.2
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• pp.399-406
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• 1995

The author studied to determine the tooth-age according to the degree of attrition. This study was performed on 247 subjects over forties. Upper and lower posterior teeth were clinically examined and transferred to a store model on which degree of attrition was measured with a magnifier respectively. The obtained results were as follows : The attrition by aging was increased in both male and female. The degree of attrition in male was higher than that in female for same age group. The coefficients of correlation and relation equations by the degree of attrition were obtained.

• Journal of Technologic Dentistry
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• v.20 no.1
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• pp.5-11
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• 1998

The purpose of this study is to evaluate the castability and surface roughness of the casts using Non-percious alloys. For samples of 25 wax patterns, it is made from eight layers of sheet wax, arranged in the escalating layers. After fabricated wax patterns, using 5 kinds of Ni-Cr alloys is casted, and the casts are sandblasted. To castability, magnifier is used and values of surface roughness of the casts is measured with profilometer(tracing length 1.75mm, cutoff value 0.25mm) The results are as follows : 1. The castanbility of alloys, in case of C alloys, showed with $8.0{\pm}0.0000$, and in case of CS alloys and N alloys showed equal with $7.8{\pm}0.4472$, respectively. T alloys and V alloys showed equal with $7.2{\pm}0.4472$, respectively. 2. The values of surface roughness of the casts are decreased more T alloys than in case of order alloys, and in order, increased in case of CS alloys, C alloys, V alloys, N alloys, respectively.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.81-85
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• 2017

The purpose of this study is to investigate the user satisfaction of kiosk contents installed at bus stops in Seoul. A total of 400 kiosks, which are touch-based traffic information systems, are installed and operated, providing contents such as bus routes, marginal area, seoul tourism, life information, angel donation, transportation cards, magnifier and boarding requests. The study results showed that the user satisfaction scores of bus routes and transportation cards were high, but it was necessary to improve other contents. The results of this study will be used as basic data to propose user experience(UX) of public service design. We will also use it as content guidelines for public information kiosks to be developed in the future.

• Restorative Dentistry and Endodontics
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• v.12 no.1
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• pp.165-169
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• 1986

A total of 114 extracted human mandibular 2nd molars were used to study the configuration of the floor of the chamber. The specimens were ground and the pulp chamber was examined with a magnifier and explored with sharp explorer. The study showed the shape of the pulp chamber, number of root canals, and the type of canal orifice. The results were as follows, 1. In so far as observing the shape of the pulp chamber of the teeth, 47.4% of the teeth were square, 42.9% were triangle and 9.7% were ovoid shape. 2. 35% of the samples had 2 root canal orifices, 62% had 3 root canal orifices, 3% had 4 root canal orifices. 3. 3% of the specimens showed 'H' shape, 5% showed 'Square' shape, 51% showed 'T' shape, 1% showed 'reverse-T' shape, 35% showed 'I' shape and 5% showed the specific 'C' shape.

• Restorative Dentistry and Endodontics
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• v.7 no.1
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• pp.53-57
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• 1981

A total of 130 extracted human maxillary second molars were used to study the configuration of the floor of the pulp chamber. The specimens were ground and the pulp chamber was examined with a magnifier and explored with sharp explorer. The study showed the shape of the pulp chamber, number of root canals, and the type of canal orifice. The results were as follows; 1. In so far as observing the shape of the pulp chamber of the teeth, 16.9% of the teeth were quadrilateral, 70.0% were triangle and 13.1% were ovoid shape. 2. 13.1% of the specimens have 4 root canal orifices. 73.9% have 3 root canal orifices, 11.5% have 2 root canal orifices and 1.5% have single orifice. 3. 13.1% of the specimens have 2 mesio-buccal canal orifices and among the teeth those have 3 canals, 20.8% show 'Y' shape, 29.1% show straight line and 23.8% show obtuse triangle shape.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.563-565
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• 2019

4차 산업혁명 시대에 우리나라의 인구비율은 점점 고령화되어 가고 있고 전자기기 사용률도 같이 증가함에 따라 사회적 약자들을 위한 접근성 도구들도 많이 개발되고 있다. 하지만 이들을 위한 접근성 도구들의 존재 유무를 대부분의 사용자는 모르기 때문에 사용하지 못하고 있다. 본 논문에서는 사회적 약자에 속하는 노인이나 신체적 장애 등을 가진 사람들이 컴퓨터를 사용할 때 가장 필요한 접근성 도구들을 추려 이들을 하나의 UI로 통합하고, 사용자의 시선을 추적하는 Tobii사의 시선추적장치를 이와 융합한다. 즉, 신체적 제약이 따르더라도 컴퓨터 사용을 도와줄 수 있는 도구들의 접근성을 개선하여 시선추적 돋보기를 포함한 통합 UI 시스템을 설계 및 구현한다.

• 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.

• Journal of the Korea Concrete Institute
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• v.11 no.4
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• pp.55-62
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• 1999

When stress is beyond elastic limit or cracks occur in a reinforced concrete member subjected to axial force and biaxial bending, curvature about each principal axis of uncracked section is influenced by axial force and bending moments about both major and minor principal axes. It is mainly due to the translation and rotation of principal axes of the cross section after cracking. Recently, by considering these effects, a numerical method predicting the behavior of concrete columns subjected to axial force and biaxial bending was proposed. In this study, in order to verify the proposed numerical method and investigate the effects of cracking on the behavior of reinforced concrete columns, a series of tests were carried out for 16 tied reinforced concrete columns with 100×100 mm square and 200×100 mm rectangular sections under various loading conditions. The angle between the direction of eccentricity and the major principal axis of uncracked section were 0, 30, 40° for the square section and 0, 30, 45, 60, 90° for the rectangular section, respectively. A comparison between numerical predictions and test results shows good agreements in ultimate loads, axial force-lateral deflection relations, and lateral deflection trajectories. It is also found, in this limited investigation, that the ACI's moment magnifier method is conservative in both uniaxial and biaxial loading conditions.

• Journal of dental hygiene science
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• v.7 no.4
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• pp.207-211
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• 2007

Many studies reported that the presence of cervical enamel projection (CEP) in cemento-enamel junction(CEJ) is greatly related to periodontal disease. The aim of this study was to investigate the prevalence of enamel projections in buccal, mesial, distal and lingual(palatal) surface of maxillary and mandibular first and second molars on extracted teeth. Among 660 teeth extracted due to the periodontal disease and dental caries in Seoul National University Dental Hospital was examined, 530 teeth which has distinct CEJ were examined with 8 times x electronic magnifier by one examiner. The prevalence of CEP for maxillary teeth (45.49%) was higher than that of mandible (39.62%). The first molar (45.22%) had more CEP than second (39.89%). Furthermore, buccal surface had highest incidence of CEP than other surfaces. The results of this study imply that the clinicians should take good care of the prevalence of CEP when scaling or root planning, plaque control instruction and periodontal surgery.

• Journal of Biosystems Engineering
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• v.40 no.3
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• pp.296-304
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• 2015

Purpose: The balance between miscanthus production and its cost effectiveness depends greatly on its moisture content during post processing. The objective of this research was to measure the moisture content using a non-destructive and non-contact methodology for in situ applications. Methods: The moisture content of comminuted miscanthus was controlled using a closed chamber, a humidifier, a precision weigher, and a real-time monitoring software developed in this research. A CMOS sensor equipped with $50{\times}$ magnifier lens was used to capture magnified images of the conditioned materials with moisture content level from 5 to 30%. The hypothesis is that when light is incident on the comminuted particles in an inclined manner, higher moisture content results in light being reflected with a higher intensity. Results: A linear regression analysis for an initiative hypothesis based on general histogram analysis yielded insufficient correlations with low significance level (<0.31) for the determination coefficient. A significant relationship (94% confidence level) was determined at level 108 in a reverse accumulative histogram proposed based on a revised hypothesis. A linear regression model with the value at level 108 in the reverse accumulative histogram for a magnified image as the independent variable and the moisture content of comminuted miscanthus as the dependent variable was proposed as the estimation model. The calibrated linear regression model with a slope of 92.054 and an offset of 32.752 yielded 0.94 for the determination coefficient (RMSE = 0.2%). The validation test showed a significant relationship at the 74% confidence level with RMSE 6.4% (n = 36). Conclusions: To compensate the inconsistent significance between calibration and validation, an estimation model robust against various systematic interferences is necessary. The economic efficiency of miscanthus, which is a promising energy resource, can be improved by the real-time measurement of its crucial material properties.