• The Journal of Korean Academy of Prosthodontics
• /
• v.33 no.3
• /
• pp.492-516
• /
• 1995

This study evaluated the responses of mandibular bones of mongrel dogs to loaded hydro xylapatite(HA) and titanium plasma spray(TPS) coated endosseous dental implants, using unloaded ones as the control group. after HA and TPS coated implants were implanted, their bone reactions with vital bones have been observed with light and scanning electron microscope(SEM) at the three periods of the 4th, 12th and 20th week. These reactions have been also compared in a histomorphometric method. The elemental distribution state of implants and the interface neighboring bone tissues have been measured with the energy dispersive analysis of X-rays(EDAX). The following results were obtained ; 1. The light microscopic analysis showed osseointegration in both the control group and the occlusal force loaded group ; Its degree was shown to be higher in the long-maintained and occlusal force groups. 2. The SEM analysis showed that both groups had osseointegration, In the case of TPS-coated implants, the coated layer was divided on the bone interface. In the case of HA-coated implants, there appeared a division between the metal and coated interface. 3. In the histomorphometric analysis, the measured ratio contaction bone of TPS-coated implants was $70{\pm}19$% in the case of no occlusal force ; it was $84{\pm}13$% in the case of occlusal force. The measured ratio contacting bone of HA-coated implants was $75{\pm}18$% in the case of no occlusal force ; it was $94{\pm}9$% in the case of occlusal force. However, there was no significant difference statistically(p>0.05). 4. Both groups showed that the ratio of calcium and phosphorous increased more in the bone tissues than on the bone to implant interface.

• The korean journal of orthodontics
• /
• v.25 no.5 s.52
• /
• pp.587-592
• /
• 1995

The purpose of this study was to observe the pattern of bone remodellings in the periodontal ligament of dog, in which experimental tooth movement was performed A control and 5 experimental dogs, one and half year in age, were studied. Light force (50-75g) was applied by placing open-coil spring between left mandibular premolars ; heavy force (250-300g), between right mandibular premolars. Experimental dogs were sacrificed at 12 hours, 1, 3 ,7 and 14 days after force application, respectively. And soft X-ray films were obtained and read on the sectioned periodontal tissue around mandibular premolars. The results were as follows. 1. New bone formation began to be observed in tension side at 7-day and increased at 14-day , No difference was observed between light force group and heavy force group. 2. Bone resorption was observed as a shape of destruction of lamina dura at 3-day and increased gradually at 7-day, 14-day.

• Electrical & Electronic Materials
• /
• v.10 no.5
• /
• pp.461-466
• /
• 1997

In this paper, we developed the new non-rubbing liquid crystal (LC) alignment techniques in the cell with slanted non-polarized ultraviolet (UV) light irradiation on polyimide (PI) film. It is shown that the uniform alignment for nematic (N) LC is obtained by using slanted non-polarized UV light irradiation on PI surface. We successfully obtained that the pretilt angle of NLC is generated about 3.3 degree in the cell with slanted non-polarized UV light irradiation with 70 degree on PI surface, for the first time. It is considered that the pretilt angle generation in NLC is attributed to interaction between the LC molecular and the PI, which is broken the polymer by slanted non-polarized UV irradiation. Therefore, we concluded that the uniform LC alignment is attributed to anisotropic dispersion force due to photo depolymerization with slanted non-polarized UV light irradiation on PI surface.

• The korean journal of orthodontics
• /
• v.41 no.5
• /
• pp.337-345
• /
• 2011

Objective: The purpose of this study was to evaluate the effect of force and moment produced by Nickel-titanium wires of different sizes at activation and deactivation according to differing vertical bracket displacement. Methods: Superelastic NiTi wires of 3 different sizes (0.014", 0.016", and 0.016" ${\times}$ 0.022") were tied with elastomeric or 0.009-inch stainless steel ligations in a twin-bracket, 0.018-inch slot. A testing machine recorded the effects of simulated activation of 5 distances from 1 to 5 mm and deactivation of 5 distances from 4 to 0 mm, in increments of 1 mm. Results: Frictional force increased the wire stiffness during loading. Ligation of 0.014-inch NiTi wire with O-ring resulted in a significant increase in the stiffness. On application of orthodontic force for 5 mm of vertical displacement of teeth, the effective displacement in the case of the 0.014", 0.016", and 0.016" ${\times}$ 0.022" NiTi wires was 2 mm, 3 mm, and 4 mm, respectively. Conclusions: Our results showed that movement of teeth with large vertical displacement was ineffective because of excessive friction. This finding might contribute to the understanding of the force system required for effective teeth movement and thereby facilitate the application of the appropriate light wire for leveling and alignment.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.10 no.3
• /
• pp.1182-1194
• /
• 2016

The single image dehazing algorithm in existence can satisfy the demand only for improving either the effectiveness or efficiency. In order to solve the problem, a novel variational framework for single image dehazing based on restoration is proposed. Firstly, the initial atmospheric scattering model is transformed to meet the kimmel's Retinex variational model. Then, the green light component of image is considered as an input of the variational framework, which is generated by the sensitivity of green wavelength. Finally, the atmospheric transmission map is achieved by multi-resolution pyramid reduction to improve the visual effect of the results. Experimental results demonstrate that the proposed method can remove haze effectively with less memory consumption.

• Journal of the Optical Society of Korea
• /
• v.10 no.2
• /
• pp.63-66
• /
• 2006

In microband-induced fiber gratings, polarization properties and birefringence are investigated as a function of an applied line force. With the transmission curves associated with the maximum and minimum resonant wavelengths, the polarization-dependent behaviors are analyzed. By increasing the transverse line force, the resonance wavelength for an incident light polarized to the same direction of the force is blue-shifted as much as 0.69 nm/(N/cm) while that for the other polarization is insensitive. Using the resonant wavelength separation corresponding to the force variation, the transverse effective index change or modal birefringence variation is obtained. The ratio of modal birefringence versus applied line force is ${\Delta}B/{\Delta}f_x={\sim}8.38{\times}10^{-7}$.

• Proceedings of the Optical Society of Korea Conference
• /
• 2000.02a
• /
• pp.130-131
• /
• 2000

One of the more promising proposals for guiding and focusing neutral atoms involves dark hollow laser beams. When the frequency of the laser is detuned to the blue of resonance, the dipole force the atoms feel in the light confines them to the dark core where the atoms can be transported with minimal interaction with the light. The ability of the all-light atom guides to transport large number of ultracold atoms for long distances without physical walls leads to the possibility of a versatile tool for atom lithography, atom interferometry, atomic spectroscopy as well as for transporting and manipulating Bose-Einstein condensates. Furthermore since the atoms transported in all-light atom guides do not come into contact with matter, they can in principle be used to transport antimatter as well. The ability to vary the core size of the hollow beam makes the all-light atom guide potentially useful for focusing neutral atoms. The atoms could be focused as tight as the core size of the hollow beam at its waist. This new focusing scheme, called the atom funnel, would not show spherical and chromatic aberrations that conventional harmonic focusing suffers from. (omitted)

• Bulletin of the Korean Chemical Society
• /
• v.13 no.3
• /
• pp.325-331
• /
• 1992

By using the general theoretical framework proposed recently for treating the fluorescence quenching kinetics, we investigate the effect of light pulse intensity on the decay of fluorescence which follows excitation of fluorophors by the light pulse of very short but finite duration. It is seen that conventional theory breaks down when the exciting light pulse has a pulse width comparable to the fluorescent lifetime and its intensity is very high. We also find that even when the light intensity is not too high, conventional theory may fail in either of the following cases: (i) when the quencher concentration is high, (ii) when there is an attractive potential of mean force between the fluorophor and quencher, or (iii) when the energy transfer from the fluorophor to the quencher may also occur at a distance, e.g., via dipole-dipole interaction. The validity of the predictions of the present theory may thus be tested by fluorescence quenching experiments performed under such situations.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.9
• /
• pp.2225-2233
• /
• 1994

In order to improve the cutting ability of face mill, a model for optimal cutter shape was developed to minimize resultant cutting force by combing cutting force model and optimal technique. Wear test and surface roughness test for optimized and conventional cutter were performed. The new optimized cutter shows longer tool life of 2.29 times than conventional cutter in light cutting condition and 2.52 times in heavy cutting condition. The surface roughness of workpiece by optimized cutter is improved in heavy cutting condition, but deteriorated in light cutting condition in comparison with conventional cutter. The surface profiles of workpiece were analyzed by Fourier transformation. The distribution of cut lay left on workpiece by optimized cutter is more regular than that by the conventional cutter.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.05a
• /
• pp.93-94
• /
• 2016

The resistance of crowd pressure is an important performance to be influential on safety of facility users among performances required for light weight walls of public facilities. This study has empirically evaluated the estimation of size of crowd pressure to be applied to a wall of structure. For the load analysis test, the force plate with stiffness of 28 kN/cm was designed and manufactured. For inspectors, 15 males in the age of 20s were selected. The action of putting load was set as instantaneous push of plate and continuous push. As the load was increased linearly from the weight of inspector, the size of load was indicated as the load ratio. In case of instantaneous force, about 1.18 times the weight of pushing personnel was acted as a load. In case of continuous push, about 0.80 times the weight of pushing personnel was acted as a load.