• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.183-191
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• 2018

In this study a traffic volume dependent displacement estimation model for Gwangan Bridge was developed using bridge monitoring big data. Traffic volume data for four different vehicle types and the vertical displacement data in the central position of the Gwangan Bridge were used to develop and validate the estimation model. Two statistical estimation models were developed using multiple regression analysis (MRA) and principal component analysis (PCA). Estimation performance of those two models were compared with actual values. The results show that both the MRA and the PCA based models are successfully estimating the vertical displacement of Gwangan Bridge. Based on the results, it is concluded that the developed model can effectively be used to predict the traffic volume dependent displacement behavior of Gwangan Bridge.

• Journal of the Institute of Convergence Signal Processing
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• v.21 no.2
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• pp.61-66
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• 2020

Recently, a variety of electric anesthetics devices have been developed and used in clinical practice to reduce the fatigue of the operator during local anesthesia for dental procedures and to compensate for the disadvantages of manual anesthesia device. In this electric anesthesia injection device, the accurate and constant delivery of pressure for drug infusion is a very important performance factor. In order to evaluate the accuracy of the transfer pressure, a small pressure gauge using a load cell is often used, but since the elastic body inside the load cell may not be able to accommodate a sufficient displacement, an error may occur when evaluating pressure performance. For these reasons, in this study, we proposed and evaluated a silicon-chrome steel (Si-Cr steel) spring jig that can accommodate relatively large displacements that can be used when evaluating the performance of a pressure-controlled pressure application device using a load cell type pressure gauge. As a result of the pressure transmissibility test and repeated measurement results using a commercial dental anesthesia injection device, a more stable result was obtained when using a spring jig, and it was confirmed that the frequency of abnormally high measurement was reduced.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.4
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• pp.120-130
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• 2019

In this study, based on the correlation between traffic volume data and vertical displacement data developed in previous research using the bridge maintenance big data of 2006, the vertical displacement estimation model using the traffic volume data of Gwangan Bridge for 10 years A comparison of the performance of the developed model with the current applicability is presented. The present applicability of the developed model is analyzed that the estimated displacement is similar to the actual displacement and that the displacement estimation performance of the model based on the structured regression analysis and the principal component analysis is not significantly different from each other. In conclusion, the vertical displacement estimation model using the traffic volume data developed by this study can be effectively used for the analysis of the behavior according to the traffic load of Gwangan Bridge.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.359-364
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• 1996

월성 2, 3, 4호기(중수로형 원자로) 원자로빌딩에 대한 지진절연 베어링의 효과를 예측하기 위해 해석적 연구를 수행하였다. 이를 위해 월성 원자로빌딩이 lumped-mass로 모델링되고 0.2g 설계 기준지진(DBE)을 적용하여 지진절연 베어링을 사용한 모델과 사용하지 않은 모델이 비교되었다. 지진절연 베어링을 사용하지 않은 원자로빌딩의 1차 고유진동수는 5.4Hz였고, 지진절연 베어링을 사용한 것은 0.7Hz까지 낮아 졌고 원자로빌딩 높이에 따라 거의 일정한 가속도로 나타났다. 지진절연 베어링을 사용하지 않은 원자로빌딩의 최대변위는 7mm였고 지진절연 베어링을 사용한 것의 변위는 106mm였다. 그러므로, 지진절연 베어링을 사용함으로써 지진하중은 크게 감소시키는 반면 큰 변위를 수용하기 위한 부가적설계가 수반되어야한다.

• Korean Journal of Optics and Photonics
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• v.5 no.1
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• pp.138-143
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• 1994

A speckle correlation method was applied to measure the in-plane translation of a diffuse object which has rough surface using a linear CCD sensor and personal computer. Displacement of a speckle pattern produced from the object illuminated by a laser beam was measured by the cross-correlation functions between the I-D speckle profiles before and after the object translation, which were measured by linear CCD array sensor to be sent to IBM 386 personal computer. The sensitivity of the measurement was dependent on the radius of the wavefront curvature of incident beam as well as the spatial resolution of linear CCD array. A linear CCD array had 15 Jlffi pitch and 1728 pixels. The ratio of the speckle displacement and object translation varied from 1.03 to 5.20. The object translation of $3\mu\textrm{m}$ can be measured br the linear CCD sensor of which pitch was $15\mu\textrm{m}$, when the ratio of the speckle displacement and object translation was 5.20.s 5.20.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.69-72
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• 2008

Bridge bearings are devices absorbing the displacements of the superstructure. Elastomeric bearings used generally as bridge bearings absorb the displacements of the superstructure using their rubber characteristics. Elastomeric bearings should make sure their shear fatigue performance not to impede the durability of bridge system. In this paper shear fatigue tests were performed and stiffness were measured through the shear fatigue tests. Tests results show the measured stiffness of elastomeric bearings have no specific tendency. This paper found that elastomeric bearings show bad shear performance or fail early if elastomeric bearings are manufactured with a doublefold elastomeric layer.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.5
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• pp.311-318
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• 2020

This study introduces a technique for improving the elastomeric-isolator performance using modular devices. The modular devices are shear resistance block, polymer spring, displacement acceptance guide, and anti-falling block. They are installed on the elastomeric isolator as a supplementary device. Each modularized device improves the isolator performance by performing step-by-step actions according to the seismic intensity and displacement. The PRB isolation device works in four stages, depending on the seismic magnitude, to satisfy the target performance. It is designed to accommodate design displacement in the first stage and large magnitude of earthquakes in the second and third stages. This design prevents superstructures from falling in the fourth stage due to large-magnitude earthquakes by increasing the capacity limit of the elastomeric isolator. In this study, the PRB isolation device is analyzed using finite element analysis to verify that the PRB isolation device works as intended and it can withstand loads corresponding to large-magnitude earthquakes. The performance of the PRB isolation device is validated by the analysis, which is further corroborated by actual experiments.

• Journal of the Earthquake Engineering Society of Korea
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• v.16 no.2
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• pp.1-13
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• 2012

Seismic fragility functions are derived for probabilistic evaluation of seismic control performance of energy dissipation devices installed in reinforced concrete structures. Displacement-dependent dampers are added to the nonlinear single-degree-of-freedom systems with different natural periods and hysteretic characteristics of which stiffness and strength has uncertainty. Nonlinear time history analysis is conducted for those SDOF systems and the result is processed statistically to obtain seismic fragility functions in the form of log normal distribution. Variation of seismic fragility functions for different parameters of SDOF systems and dampers are investigated and the seismic control performance is assessed probabilistically.

• Journal of the korean academy of Pediatric Dentistry
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• v.28 no.2
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• pp.281-286
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• 2001

The treatment method of impacted tooth is various from simple observation to surgical exposure and orthodontic methods, autotransplantation is concerned to severe malposed impacted tooth. Autotransplantation is the transplantation of embedded, impacted, of unerupted tooth, into extraction socket of surgically prepared in the same individual. Autotransplantation of tooth with $\frac{1}{2}{\sim}\frac{3}{4}$ root development provides a good chance of easily extracted, a little complication, pulp survival, and complete root formation. Transplantation of uncompleted root apex tooth is aim to pulpal healing, not endodontic treatment. The case which were treated with autotransplantation is reported, and induced normal physiologic eruption and good dental alignment.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.6
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• pp.548-553
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• 2008

In this paper, we propose a new swing-up control strategy for rotary inverted pendulums with restricted rotation range. The control law is derived from a Lyapunov function. The Lyapunov function is defined as the square of the sum of the absolute value of the total mechanical energy and weighted squares of the arm's angular displacement and velocity. By adjusting the weighting parameters in the Lyapunov function, we can affect the swing-up strategy such that the restriction on rotation range can be satisfied. Finally, we verify the performance of the proposed control law through simulation and experiments.