• The korean journal of orthodontics
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• v.25 no.4
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• pp.453-463
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• 1995

Most commonly used axis for central incisors in lateral cephalometric radiographs is the line connecting root apex and incisor edge. However, crown axis and root axis do not always coincide in cases of malocclusion patients. The angle created by these axis are called the collum angle, which should be considered in orthodontic diagnosis and treatment. In this study, 31 Class I malocclusion, 30 Class II division 1 malocclusion, 31 Class II division 2 malocclusion, and 31 Class m malocclusion patients were selected and their collum angles were measured. Correlation between these angles and malocclusions was investigated, and the correlation analysis with other parameters in cephalometrics was done. The results were as follows ; 1. The mean collum angles according to the types of malocclusions are ; $3.11^{\circ}{\pm}3.54^{\circ}$ for Class I, $1.23^{\circ}{\pm}2.41^{\circ}$ for Class II division 1, $3.77^{\circ}{\pm}4.39^{\circ}$ for Class II division 2, and $3.90^{\circ}{\pm}4.08^{\circ}$ for Class III malocclusion. 2. Statistically significant differences in collum angles were noted between Class II division 1 group and Class II division 2 and Class III group. 3. Significant correlations were found between collum angles and other parameters used in cephalometrics, namely IMPA for Class I, Wits for Class II division 1, Overbite for Class II division 2 and for ClassIII.

• Journal of the Korean institute of surface engineering
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• v.53 no.3
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• pp.116-123
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• 2020

Ion beam irradiation induces self-organization of nanostructure on the surface of polymer film. We show that the incident angle of Ar ions on polyethylene naphthalate(PEN) film changes self-organized nanostructure. PEN film was irradiated by argon ion beams with the ion incident angle of 0°, 30°, 45°, 60°, and 80°. Nanostructure was altered from dimple to ripple structure as the angle increases. The ripple structure changed to pillar structure after 60°due to that the shallow incident angle increased the ion energy transfer per depth up to 50 eV/Å, which value could induce excessive surface heating and oligomer formation reacting as a physical mask for anisotropic etching. And quantitative analysis of the nanostructures was adapted by using ABC model and fractal dimension theory.

• The Journal of the Korean dental association
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• v.19 no.1 s.140
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• pp.67-71
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• 1981

This study was undertaken to find out the characteristic craniofacial morphology of Class II Division 2 malocclusions in children by means of roentgenocephalometry. The subjects consisted of twelve boys and thirteen girls with Class Ii, Division 2, thirty seven boys and fifty three girls with Class II, Division 1, and forty six boys and eighty one girls with normal occlusion, ranged from 10 years old to 18 years old. The following results were obtained; 1. The anteroposterior relationship of the maxilla to the cranium in the Class II, Division 2 malocclusion similar to the normal occlusion, but the mandible was the posterior position in th the cranial anatomy. 2. There were no significant differences in the anteroposterior relationship of the maxilla and the mandible between Class II, Division 1 and Class II, Division 2 malocclusions. 3. In Class II, Division 1 the axes of maxillary incisors showed labial inclination, but lingual inclination in Class II, Division 2 malocclusions. 4. Overbite was prominent one in Class II, Division 2, on the other hand overjet was distinguished in Class II, Division 1.

• International Journal of Fluid Machinery and Systems
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• v.3 no.4
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• pp.360-368
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• 2010

This paper describes the flow field and the blade pressure distribution of a horizontal axis wind turbine in various yawed flow conditions. These measurements were carried out with 2.4m-diameter rotor with pressure sensors and a 2-dimensional laser Doppler velocimeter for each azimuth angle in a wind tunnel. The results show that aerodynamic forces of the blade based on the pressure measurements change according to the local angle of attack during rotation. Therefore the wake of the yawed rotor becomes asymmetric for the rotor axis. Furthermore, the relations between aerodynamic forces and azimuth angles change according to tip speed ratio. By the experimental analysis, the flow field and the aerodynamic forces for each azimuth angle in yawed flow condition were clarified.

• Carbon letters
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• v.4 no.1
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• pp.10-13
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• 2003

The structural studies of amorphous isotropic carbon prepared from pyrolysis of phenol formaldehyde resin have been carried out using X-ray diffraction. X-ray diffraction from as prepared sample at $1000^{\circ}C$ and a sample treated at $1900^{\circ}C$ revealed that both are amorphous even though there are small differences in short range order. It is found that both are graphite like carbon (GLC) with predominantly $sp^2$ hybridization. Small angle X-ray scattering results show that as prepared sample mainly consists of thin two dimensional platelets of graphitic carbon whereas they grow in thickness to become three dimensional materials of nano dimensions.

• Bulletin of the Korean Chemical Society
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• v.30 no.5
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• pp.1067-1070
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• 2009

We studied change in water contact angle on $TiO_2$ surfaces upon high-energy electron-beam treatment. Depending on conditions of e-beam exposures, surface OH-content could be increased or decreased. In contrast, water contact angle continuously decreased with increasing e-beam exposure and energy, i.e. change in the water contact angle cannot be rationalized in terms of the overall change in the surfacestructure of carbon-contaminated $TiO_2$. In the C 1s spectra, we found that the C-O and C=O contents gradually increased with increasing e-beam energy, suggesting that the change in the surface structure of carbon layers can be important for understanding of the wettability change. Our results imply that the degree of oxidation of carbon impurity layers on oxide surfaces should be considered, in order to fully understand the change in the oxide surface wettability.

• Journal of the Ergonomics Society of Korea
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• v.5 no.2
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• pp.37-44
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• 1986

This study investigates display station physical adjustments preferred by a sample of visual display terminal operators. Participants in the study were selected to assure representation of extremely short and extremely tall persons, as well as persons of midrange physical stature. Individual operators were led through a step-by-step sequence to determine their preferred initial settings of seat height, keyboard height and slope angle, and CRT height and tilt angle. Each operator then performed a brief text input tase, after which final preferred adjustments were measured. Intermeasure correlation strongly suggest that "flat" (low slope angle) keyboards are in appropriate for short operators who select low seat heights. In addition, the keyboard angle adjustments preferred by most operators substantially exceed a current German ergonomic display station requirement.

• The Journal of the Acoustical Society of Korea
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• v.20 no.3E
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• pp.25-30
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• 2001

In angle of arrival estimation, the direction of a signal is usually assumed to be a point. If the direction of a signal is distributed due to some reasons in real surroundings, however, angle of arrival estimation techniques based on the point source assumption may result in poor performance. In this paper, we consider angle of arrival estimation when the signal sources are distributed. A parametric source model is proposed, and the estimation techniques based on the well-known maximum likelihood technique is considered under the model. In addition, Various statistical properties of the estimation errors were obtained.

• Bulletin of the Korean Chemical Society
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• v.25 no.11
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• pp.1676-1680
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• 2004

We demonstrate that wide-angle X-ray scattering pattern from photoactive yellow protein (PYP) in solution using a high flux third generation synchrotron X-ray source reflects not only the overall structure, but also fine structures of the protein. X-ray scattering data from PYP in solution have been collected in q ranges from 0.02 ${\AA}^{-1}$ to 2.8 ${\AA}^{-1}$. These data are sensitive to the protein structure and consistent with the calculation based on known crystallographic atomic coordinates. Theoretical scattering patterns were also calculated for the intermediates during the photocycle of PYP to estimate the feasibility of time-resolved wide-angle X-ray scattering experiments on such proteins. These results demonstrate the possibility of using the wide-angle solution X-ray scattering as a quantitative monitor of photo-induced structural changes in PYP.

• Journal of Korean Tunnelling and Underground Space Association
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• v.16 no.6
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• pp.573-584
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• 2014

In this study, the variations of cutter acting forces depending on cutting conditions were examined to obtain basic data for roadheader cutting head design. The linear cutting tests were performed in the condition of different attack angles, penetration depths, cutter spacings by using a slim conical pick for the light cutting condition. Cutter acting forces were measured by 3-directional load cell under different test conditions, and the analysis for cutting performance were carried out after calculating average values of the measured results. It is confirmed that the optimal cutting condition for the mortar specimen is the 50 degree attack angle, the cutter spacing of 12 mm, the cutting depth of 9 mm which are obtained from the analysis results. In addition, 50 degree attack angle is more effective than 45 degree attack angle to design optimal specifications of cutting head.