• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.150-159
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• 2014

A simplified method for the calculation of buckling and vibrational characteristics of initially stressed rectangular plate and antisymmetric angle-ply laminated plates is presented in this paper using the natural frequencies under unloading state. The equation of motion of rectangular plate with two opposite edges simply supported is investigated on the basis of Rayleigh-Ritz method and Mindlin plate theory with effect of the curvature term. The relationships of the non-dimensional natural frequencies with initial stresses the coeffcients of critical buckling and the boundaries of the dynamic principal instability region can be characterized by the non-dimensional natureal frequencies under unloading state. Numerical examples are presented to verify the simplified equations and to illustrate potential applications of the analysis.

• Journal of Korean Society for Geospatial Information Science
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• v.23 no.1
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• pp.47-54
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• 2015

In this study, we developed strategies for pre-processing GNSS data for the purpose of separating geodetic factors from crustal deformation due to the earthquakes. Before interpreting GNSS data analysis results, we removed false signals from GNSS coordinate time series. Because permanent GNSS stations are located on a large tectonic plate, GNSS position estimates should be affected by the tectonic velocity of the plate. Also, stations with surrounding trees have seasonal signals in their three-dimensional coordinate estimates. Thus, we have estimated the location of an Euler pole and angular velocities to deduce the plate tectonic velocity and verified with geological models. Also, annual amplitudes and initial phases were estimated to get rid of those false annual signals showing up in the time series. By considering the two effects, truly geodetic analysis was possible and the result was used as preliminary data for analyzing post-seismic deformation of the Korean peninsula due to the Tohoku-oki earthquake.

• Journal of Digital Convergence
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• v.19 no.8
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• pp.385-396
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• 2021

The purpose of the study was to explore the process of experience of spinal stenosis, herniation of intervertebral disk patients with low back pain under non-surgical treatment. 10 participants attended in-depth individual interview. Data analyzed using the Grounded theory methodology of Corbin and Strauss(2015). A core category emerged as 'Compromise with my body in the swamp of pain'. Central phenomenon was 'Constrained life by severe pain'. The process of the low back pain experience included three phases: 'cognition', 'coping', and 'adaptation'. This finding will be helpful for understanding the low back pain experience and be as fundamental data as for developing and applying nursing intervention program according to the low back pain experience process.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.7
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• pp.681-686
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• 2015

The onset characteristics of friction-induced noise for a steel plate and 4 metallic pins (Cu, Ni, Al, Mg) were studied through the pin-on-disk machine and the reciprocating testing machine. The results showed that the negative slope of the friction curve was related to the onset time of friction noise. Particularly, Cu was found to be the best metallic material for preventing squeak noise in terms of the onset time and the negative friction slope.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.283-286
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• 2009

척추경 나사못을 이용한 요추 유합술은 가장 보편적으로 사용되어지는 수술적 치료 방법이다. 과거 여러 연구들에서 이러한 척추 유합술의 임상적 우수성은 이미 입증 되었으며, 척추경 나사못은 시술 부위의 운동을 완전히 제한함으로써 높은 유합율을 얻을 수 있으나, 상대적으로 인접 분절의 조기 퇴행성 변화의 요인 중 하나로 보고되고 있다. 따라서 본 연구에서는 유한요소해석 방법을 이용하여 척추경 나사못 시술에 따른 척추체의 운동범위 및 인접 분절 추간판의 스트레스 증가량을 계산하였고, 척추경 나사못 모델과 유합 후 나사못 제거에 따른 모델 또 시술하기 전 정상모델과 비교하여 생체 역학적 측면에서 분석하여 척추경 나사못을 이용한 요추 유합술 후, 척추경 나사못의 제거의 임상적 효과와 그 이론적 근거를 제시하고자 한다.

• Proceedings of the Korean Society of Computer Information Conference
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• 2019.07a
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• pp.141-142
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• 2019

본 논문에서는 현대사회에서 스마트 폰 보급의 활성화와 좋지 않은 자세로 오래 앉아 있는 학생들이 자가적으로 척추 측만증을 진단하여 스스로 인지하게 하는 것이 목표이다. 척추측만증은 통증이 나타나지 않아 질병으로인해 병원에서 진료받지 않으면 자가적으로 판단하기 어려울 뿐만 아니라 방치하면 추간판 탈출증 등 여러 척추 질환에 노출 되기 쉽다. 질환을 예방 하기 위해 자이로 센서와 균형센서를 이용하여 집이나 재활트레이닝 센터 및 학교 등에서 자가적으로 판단을 할 수 있다. 센서를 통한 자가적인 진단 정보는 휴대폰의 어플리케이션으로 전달되어 척추 측만증의 정도를 알 수 있고 그에 따른 운동방법이나 자세 교정 방법등을 알려주고 운동 프로그램을 설계하는 시스템을 개발하는데 목적이 있는 연구이다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.12
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• pp.75-81
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• 2006

In this paper, the 6-dof electric motion platform system designed for the helicopter simulator satisfying the class of the CASA(Civil Aviation Safety Authority) level 2 is presented. From the kinematic, dynamic and structural analyses for motion base and electrical actuator systems, we show the feasibility of the developed motion platform system by producing the acceptable results of the test and evaluation according to the requirements specified in the CASA level 2. Furthermore through this development we suggest newly the adaptability of the electrical actuator system up to 10 ton class motion platform system, whose usage will be broaden rapidly, substituting with the advantage over the conventional hydraulic system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.4
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• pp.37-44
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• 1991

A powerful analytical procedure and strain energy analysis to investigate the free vibration of antisymmetric cross-ply laminated plates, having one pair of opposite edges simply supported, are develped on the basis of the Yang, Norris abd Stavsky (YSN) theory. The equation of motion of the plate are solved by the use of collation method. A range of results are presented for plates to show the effects of modulus ratio and number of layers on natural frequency. In addition, an analysis of the strain energy distributions is used as an aid for the better understanding of the vibration characteristics of the plates.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.1
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• pp.65-73
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• 1987

An efficient plate bending finite element has been developed using higher-order inplane displacement profiles of the plate. The 6-noded, 21-d.o.f. triangular element including shear deformation effect has been derived from the plate-like continuum by the Galerkin's weighted residual method. Square plate examples were tested with selected element meshes and several aspect ratios for their static behavior under uniformly distributed load. The result of the example tests indicated consistently good performance of the present higher-order plate bending element in comparison with the thin and thick plate solution and other existing finite element solutions.

• Journal of Korean Ophthalmic Optics Society
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• v.6 no.2
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• pp.77-80
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• 2001

The purpose of this work is that by using speckle phenomena of low-level He-Ne laser, it analyzes the movement condition of surface elements on a substance vibrating. The lights from laser reflect against a copper plate and will be shown as speckles on a vibration board. If we vibrate these speckles by sound waves of a speaker installed on the back, the speckles change with various shapes. When a vibration board has a maximum vibration, the frequency becomes a dynamical resonance frequency and we can mark the changes of speckles at that time on a vibration board.