• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1998.06a
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• pp.33-36
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• 1998

This paper is a study on a linear ultrasonic motor with a first longitudinal$(L_1)$ and fourth bending $(B_4)$ double-mode rectangular plate. The stator vibrator is composed of an elastic material plate and of a piezo-ceramic element having a motion by electrical excitation. Each strain vector differs by $90^{\circ}$ generate travelling wave with the elliptical displacement motion of a point on the surface. To magnify displacement of longitudinal direction in elliptical displacement motion, the motor has a mechanism of the.displacement enlargement. In this paper, the vibration shape of the stator is simulated using the finite element method. A detailed model considered of the piezoelectric effect and of the exact geometry of the stator is used to calculate the displacement. The position of displacement mechanism is decided by the maximum displacement.

• International Journal of Highway Engineering
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• v.20 no.4
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• pp.15-20
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• 2018

PURPOSES : The purpose of this study is to analyze the magnitude of shoving of asphalt pavement by junction type between airport concrete and asphalt pavements, and to suggest a junction type to reduce shoving. METHODS : The actual pavement junction of a domestic airport, which is called airport "A" was modified by placing the bottom of the buried slab on the top surface of the subbase. A finite element model was developed that simulated three junction types: a standard section of junction proposed by the FAA (Federal Aviation Administration), an actual section of junction from airport "A" and a modified section of junction from airport "A". The vertical displacement of the asphalt surface caused by the horizontal displacement of the concrete pavement was investigated in the three types of junction. RESULTS : A vertical displacement of approximately 13 mm occurred for the FAA standard section under horizontal pushing of 100 mm, and a vertical displacement of approximately 55 mm occurred for the actual section of airport "A" under the same level of pushing. On the other hand, for the modified section from airport "A" a vertical displacement of approximately 17 mm occurred under the same level of pushing, which is slightly larger than the vertical displacement of the FAA standard section. CONCLUSIONS : It was confirmed that shoving of the asphalt pavement at the junction could be reduced by placing the bottom of the buried slab on the top surface of the subbase. It was also determined that the junction type suggested in this study was more advantageous than the FAA standard section because it resists faulting by the buried slab that is connected to the concrete pavement. Faulting of the junctions caused by aircraft loading will be compared by performing finite element analysis in the following study.

• Journal of the Korean Applied Science and Technology
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• v.26 no.2
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• pp.224-231
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• 2009

Techniques measuring Maxwell displacement current (MDC) and LB films surface measuring technique have been applied to the study of monolayers of polyamic acid containing azobenzene. MDCs was generated from monolayers on the water surface by monolayer compression and expansion. It was generated when the area per molecule was about $103{\AA}^2\;and\;78{\AA}^2$ just before the initial rise of the surface pressure during the 1st and 2nd mixed monolayer compressions cycle, respectively. It was the maximum of MDCs appeared at the molecular area just before the initial rise of surface pressure in compression cycles, and we have found that the increase of aggregations causes the noticeable increase of the surface roughness.

• Journal of the Optical Society of Korea
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• v.12 no.1
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• pp.13-18
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• 2008

We numerically investigate by the finite-difference time-domain method the effects of surface termination on directional emission exiting a photonic crystal waveguide. The directed power and far-field beam profile for the original proposal [E. Moreno et al., Phys. Rev. B 69, 121402 (2004)] and its enhancement [S. K. Morrison et al., Appl. Phys. Lett. 86, 081110 (2005)] are computed for different values of some important parameters. We find another surface termination condition with a positive surface displacement in the structure of the original proposal which has a negative surface displacement. Our surface termination is more effective than the original structure, and nearly as effective as the termination for the enhancement, for directional emission. Besides, our termination is simpler than that for the enhancement. We confirm the effectiveness of directional emission from our termination in its far-field beam profile, radiation intensity distribution, and additionally the wave-vector space representation by the Fourier analysis.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.05a
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• pp.38-42
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• 2001

To observe the Langmuir films, displacement current measuring system(Nippon Laser & Electronics), $\pi-A$ isotherms measuring device, and Brewster Angle Microscope(BAM) were used. As results, for 8A5H, big tilt angle changes of many molecules were detected before liquid expanded phase when the monolayer was compressed and expanded by barrier. Also many small and bright points were detected by BAM when the displacement current radically changed. In $\pi$-A isotherms, surface pressure of 8A5H was radically decreased between 35 and 40[mN/m] and monolayer was assumed to be collapsed in solid condensed phase, since large bright domain was observed without change of displacement current and this bright boundary was not classified part of domain in BAM image. If we observe behaviors of molecules on the water surface in these three measurement at the same time, we can get more precise informations on L films and it could be good data for fabricating LB films.

• Tunnel and Underground Space
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• v.18 no.5
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• pp.355-365
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• 2008

Displacement caused by tunneling is difficult to predict since it is affected by many factors such as ground condition, excavation method and supplementary method of reinforcement. In this study, horizontal inclinometer was employed to monitor ground settlements above a tunnel face before and after the excavation. Monitoring results were analyzed to predict the preceding displacement and settlement of the surface structures. The result of the analysis can be used to establish a proper counter measure which keeps the serviceability of the surface structures. Based on the analysis of the monitoring result, ground properties of the site were deduced and the influence of the tunnel excavation on the settlement of the foundation above the tunnel is analyzed.

• Earthquakes and Structures
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• v.22 no.4
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• pp.373-386
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• 2022

The development of performance-based design methodologies requires a reasonable definition of a displacement-response spectrum. Although ground motions are known to be significantly affected by the resonant-like amplification behavior caused by multiple wave reflections within the surface soil, such a soil-resonance effect is seldom explicitly considered in current-displacement spectral models. In this study, an analytical approach is developed for the construction of displacement-response spectra by considering the soil-resonance effect. For this purpose, a simple and rational equation is proposed for the response spectral ratio at the site fundamental period (SRTg) to represent the soil-resonance effect based on wave multiple reflection theory. In addition, a bilinear model is adopted to construct the soil displacement-response spectra. The proposed model is verified by comparing its results with those obtained from actual observations and SHAKE analyses. The results show that the proposed model can lead to very good estimations of SRTg for harmonic incident seismic waves and lead to reasonable estimations of SRTg and soil displacement-response spectra for earthquakes with a relatively large magnitude, which are generally considered for seismic design, particularly in high-seismicity regions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.4
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• pp.371-380
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• 2000

The turbulent heat transfer from a round oblique impinging jet on a concave surface were experimentally investigated. The transient measurement method using liquid crystal was used in this study. In this measurement, a preheated wall was suddenly exposed to an impinging jet while recording the response of liquid crystals to measure surface temperature. The Reynolds numbers were 11000, 23000 and 50000, nozzle-to-surface distance ratio was from 2 to 10 and the surface angles were a =$0^{\circ}\;15^{\circ},\;30^{\circ}and\;40^{\circ}$. Correlations of the stagnation point Nusselt numbers with Reynolds number, jet-to-surface distance ratio and dimensionless surface angle, which account for the surface inclined angle, are presented. The maximum Nusselt numbers, in this experiment, occurred in the direction of upstream. The displacement of the maximum Nusselt number from the stagnation point increases with increasing surface angle or decreasing nozzle-to-surface distance. In this experiment, the maximum displacement is about 0.7 times of the jet nozzle diameter when surface curvature, D/d is 10.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.50-50
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• 2000

In this paper, a new measuring system is :proposed which can measure the fine 6-DOF displacement of rigid bodies. Its measurement principle is based on detection of laser beam reflected from a specially fabricated mirror that looks like a triangular pyramid having an equilateral cross-sectional shape. The mirror has three lateral reflective surfaces inclined 45$^{\circ}$ to its bottom surface. We call this mirror 3-facet mirror. The 3-facet mirror is mounted on the object whose 6-DOF displacement is to be measured. The measurement is operated by a laser-based optical system composed of a 3-facet mirror, a laser source, three position-sensitive detectors(PSD). In the sensor system, three PSDs are located at three corner points of a triangular formation, which is an equilateral triangular formation tying parallel to the reference plane. The sensitive areas of three PSDs are oriented toward the center point of the triangular formation. The object whose 6-DOF displacement is to be measured is situated at the center with the 3-facet mirror on its top surface. A laser beam is emitted from the laser source located at the upright position and vertically incident on the top of the 3-fatcet mirror. Since each reflective facet faces toward each PSD, the laser beam is reflected at the 3-facet mirror and splits into three sub-beams, each of which is reflected from the three facets and finally arrives at three PSDs, respectively. Since each PSD is a 2-dimensional sensor, we can acquire the information on the 6-DOF displacement of the 3-facet mirror. From this principle, we can get 6-DOF displacement of any object simply by mounting the 3-facet mirror on the object. In this paper, we model the relationship between the 6-DOF displacement of the object and the outputs of three PSDs. And, a series of simulations are performed to demonstrate the effectiveness of the proposed method. The simulation results show that the proposed sensing system can be an effective means of obtaining 3-dimensional position and orientation of arbitrary objects.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.27 no.5
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• pp.417-422
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• 2001

Objective: In many TMD cases, deformed and reduced condyle heads were frequently observed. This study was prepared to compare the dimensions between normal and symptomatic condyles, using MR images. Materials: One hundred and twenty one patients with clinical signs and MRI-confirmed diagnosis of disc displacement were selected for this study. Thirty eight TMJs from nineteen asymptomatic volunteers who had no clinical symptoms and no disc displacement on sagittal and coronal view of MRI, were served as normal. Methods: Symptomatic condyles were classified according to the severity of the anterior disc displacement. The amount of anterior disc displacement was evaluated at sagittal section, and they were classified into 4 groups as normal(N), little(G0), mild(G1), moderate(G2) and severe displacement(G3). The dimentions of condyle were measured at the 200% magnified view, by digitizing program. All dimensions were compared among each groups on the central section of sagittal and coronal views, and the statistical analysis was performed. Results: The mean value of anteroposterior length of normal condyle was $0.79{\pm}0.13cm$ at sagittal section and mediolateral length was $2.12{\pm}0.22cm$ on coronal section. The mean value of anteroposterior length of symptomatic condyle was $0.67{\pm}0.16cm$ at sagittal section and mediolateral length was $1.97{\pm}0.28cm$ on coronal section. Conclusions: The size of symptomatic condyle was smaller than normal TMJ. The size of condyle was decreased as the amount of the disc displacement was increased. The dimensional change was found on the anterior articular surface of condyle at the mild or moderate disc displacement. And at the case of severe disc displacement, dimensional change was found on the superior articular surface.