• The korean journal of orthodontics
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• v.16 no.2
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• pp.43-51
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• 1986

The highly accurate laser holographic interferemotry method was used to determine in what way low-magnitude forces during maxillary expansion are transmitted to the entire maxillary complex and its surrounding structures. The experiments were carried out on a dryed human skull which had a perfectly preserved, normally aligned maxillary dental arch and intact alveolar process. The skull was fixed within a constructed metal frame which ensured maximal stability of the object. The optical equipment and the object were mounted on antivibration table. Interferograms were taken on the lateral and frontal sides of the maxillary complex, using the 10mW He-Ne laser and the double-exposure method. Analysis of the fringe pattern on the recorded object surface was performed by graphically determining the deformation curves related to the bony surface in selected horizontal and vertical planes. On the basis of this study, the following conclusions can be drawn: 1. The density of the interference fringes was gradually increased with the degree of expansion force. 2. Mechanical reactions on the maxillary complex, circummaxillary sutures, and surrounding bones were clearly visible, even with the lowest loading degree. 3. The amount of bone displacement was greater in application of the force after $90^{\circ}$ turn than in initial application of the same force. 4. The direction of interference fringes on the bony surface was similar at all loading degrees.

• Korean Journal of Optics and Photonics
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• v.3 no.1
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• pp.67-72
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• 1992

Since the inception of the idea to develop an X-ray laser in 1960's, a rapid progress to demonstrate soft X-ray lasers in the wavelength region below 300$\AA$ has been made during the last ten years. Among many prospective proposals, the recombination scheme and the collisional exitation scheme have been most successful in achieving a significant gain. An appreciable single-pass amplification was achieved at 182 $\AA$ from CVI ions using the recombination scheme and at 206 and 290$\AA$ from the Se XXV ions using the collisional excitation scheme. The current research on X-ray lasers emphasizes the enhancement of amplification upto saturation and the extension of operating wavelength to shorter wavelengths, especially to the water window region between 23 and 44 $\AA$. X-ray lasers are expected to open many application fields, such as X-ray laser microscopy, X-ray holography, X-ray lithography, and more, in the near future.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.11a
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• pp.112-113
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• 2006

In this paper. we investigated a characteristic of holographic grating data erasure with non-polarized beam at amorphous chalcogenide As-Ge-Se-S thin film. A sample of holographic grating data was formed with DPSS laser for setup. Then, the erasure process was performed with He-Ne laser vertically at sample. As-Ge-Se-S(single layer). Ag/As-Ge-Se-S(double layer) and As-Ge-Se-S/Ag/As-Ge-Se-S(multi-layer) are manufactured to compare their characteristic of erasure.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.134-134
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• 2010

We have investigated the holographic grating formation on Ag-doped amorphous chalcogenide AsGeSeS thin films with Ag thickness. Holographic gratings have been formed using Diode Pumped Solid State laser (DPSS, 532.0nm) under [P:P] polarized the intensity polarization holography. The diffraction efficiency was obtained by +1st order intensity.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3211-3223
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• 1996

In this paper, the propagation of elastic wave generated by loading impact to plates made of isotropic of anisotropic material was studied. And the influence of boundary conditions (free or clamped edge) upon the reflection of elastic wave was anlyzed. Also, double exposure holographic interferometer using ruby pulse laser was formed in order to investigate transient waves. Before the elasitc wave was reflected from the edges, the elastic wave of isotropic plate such as aluminum plate showed circular interferometric fringe pattern, whereas that of anisotropic plate such as epoxy composite laminates showed elliptical one. And the transverse displacement curves obtained from experiment and theory for both plates agreed well. Also, the waves reflected from the boundary edges showed much differences according to the boundary condition of edges.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.2
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• pp.65-71
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• 1992

In most absorption machines, absorption enhancement has been achieved by adding small amount of surfactant additive, which introduced the surface tension difference between absorbent and surfactant droplets in the vapor absorption. The aim of this study is to understand a basic mechanism of Marangoni convection and its effectiveness in the vapor absorption enhancement. In this study, nonflowing aqueous solution of LiBr 60 mass% was exposed to saturated water vapor under the condition that two dropwises surfactant were fixed on the absorbent surface. Our experiments achieved to visualize the enhanced heat and mass transfer phenomena by the effect of Marangoni convection through the laser holographic interferometry. Also, Marangoni convection behavior was obtained by using tracer method.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.107-107
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• 2010

In this study, we have investigated the holographic grating formation on Ag-doped amorphous chalcogenide AsGeSeS thin films with Ag thickness. Ag/AsGeSeS thin films with the incident laser beam wavelength for the improvement of the polarization diffraction grating efficiency. Holographic gratings have been formed using Diode Pumped Solid State laser (DPSS, 532.0nm) under [P:P] polarized the intensity polarization holography. The diffraction efficiency was obtained by +1st order intensity. The result is shown that the diffraction efficiency of Ag/AsGeSeS double layer thin film for the Ag thickness, the maximum grating diffraction efficiency using 60nm Ag layer is 0.96%.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1430-1431
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• 2006

We investigated the formation of 2-dimension hologram grating by means of selective etching characteristic and photo-expansion effect according to photo irradiation on amorphous As-Ge-Se-S thin film. By method of phase holography, we made the 2-dimensional hologram grating by each (S:P) and ($+45^{\circ}:-45^{\circ}$) polarized beam with DPSS laser(532nm) and He-Ne laser(632nm). A recording property was observed at each polarized beam through 2-dimensional hologram surface relief grating. Chalcogenide thin film was etched selectively by NaOH solution after the formation of 1-dimensional diffraction grating. And then etched sample was rotated 90 degree to fabricate 2 dimensional hologram grating. We found that it was observed the formation of 2-dimensional hologram grating by AFM(Atomic Force Microscopy).

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.9
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• pp.791-795
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• 2000

Amorphous chalcogenide glasses have a wide variety of light-induced effects. In this study, we have investigated the diffraction efficiency of chalcogenide. As$_{40}$ Ge$_{10}$ Se$_{15}$ S$_{35}$ thin films by the various applied electric fields. The holographic grating in these thin films has been formed using a linearly polarized He-Ne laser light (633nm). The diffraction efficiency was investigated the two method of applied electric field in the perpendicular and parallel to the direction of inducing beam. We obtained that properties of diffraction efficiency in the two methods of applied electric field. The result is shown that the diffraction efficiency of parallel electric field is 285% increase, η=1.1$\times$10$^{-3}$ and the diffraction efficiency of perpendicular electric field is 80% decrease, η=9.83$\times$10$^{-5}$ . Also, we have investigated the anisotropy property on chalcogenide thin films by the electric field effects.

• The korean journal of orthodontics
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• v.18 no.2
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• pp.367-385
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• 1988

In case of skeletal Class III malocclusion with underdeveloped maxilla, the extraoral orthopedic force for the stimulation of maxillary growth or anterior reposition of the maxilla has been used clinically for the improvement of facial skeletal relationship. The purpose of this investigation was to examine the initial reaction of maxillofacial complex to the maxillary protraction by using extraoral orthopedic force. The dried human skull was used and this investigation was done by means of double exposure holographic interferometry. The protraction forces placed on the canine or the first molar were parallel, $10^{\circ}$ downward, $20^{\circ}$ downward to the occlusal plane. Fringe pattern of each protraction condition was compared and analized. The results were as follows: 1. Each maxillofacial bone displaced saparately. 2. More displacement was shown at the area of the teeth and the alveolar bone. 3. A counterclockwise rotation of the maxilla wa decreased by downward protraction and especially 20 degree downward protraction from the canine showed least rotation. 4. On the zygomatic arch, outward bend was observed and this effect was decreased by downward protraction. 5. On the zygomatic bone, the counter clockwise rotation was increased by the downward protraction. 6. When maxillary expansion was applied at the same time, outward and upward displacement with counterclockwise rotation was observed on the maxilla. 7. The lateral pterygoid plate of sphenoid bone was affected by maxillary protraction.