• Journal of KSNVE
• /
• v.6 no.1
• /
• pp.65-70
• /
• 1996

The sensor response of a piezoelectric transducer embedded in a fluid loaded structure is modeled using a hybrid numerical approach. The structure is excited by an obliquely incident acoustic wave. Finite element modeling in the structure and fluid surrounding the transducer region, is used and a plane wave representation is exploited to match the displacement field at the mathematical boundary. On this boundary, continuity of field derivatives is enforced by using a penalty factor and to further achieve transparency at the mathematical boundary, drilling degrees of freedom (d.o.f.) are introduced to ensure continuity of all derivatives. Numerical results are presented for the sensor response and it is found that the sensor at that location is not only non-intrusive but also sensitive to the characteristic of the structure.

• Journal of the Institute of Electronics Engineers of Korea CI
• /
• v.48 no.5
• /
• pp.33-41
• /
• 2011

In this paper, we propose a lossless compression scheme for cloud point data of the target construction by using doubleness and decreasing useless information of cloud point data. We use Hough transform to find the horizontal angle between construction and terrestrial LIDAR. This angle is used for the rotation of the cloud point data. The cloud point data can be parallel to x-axis, then y-axis doubleness is increased. Therefore, the cloud point data can be more compressed. In addition, we apply two methods to decrease the number of cloud point data for useless information of them. One is decimation of the cloud point data, the other is to extract the range of y-coordinates of target construction, and then extract the cloud point data existing in the range only. The experimental result shows the performance of proposed scheme. To compress the data, we use only the position information without additional information. Therefore, this scheme can increase processing speed of the compression algorithm.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.22 no.4
• /
• pp.83-90
• /
• 2018

Considering the increased threats from worldwide terrors and the increased demands on the blast resistant design of commercial buildings, this study is aimed at understanding the basic concept of blast resistant design and evaluating the blast performance with an actual design example. Although there are many differences between earthquake and blast loads, the design concept against both loads is similar in terms of allowing the plastic behavior of a structure and sharing the ductile detailing. Through the blast performance evaluation of a target building provided in this study, it is noted that a well-designed building for the conventional loads can have a certain level of blast resistance. However, this cannot be generalized since the blast load on a structure varies depending on the type of weapon, TNT equivalence, standoff distance, etc. Architectural planning with positioning the sacrificial structure or maintaining a sufficient standoff distance from the expected detonation is the simple and effective way of improving the blast resistance of a building.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.23 no.4
• /
• pp.45-52
• /
• 2019

In this study, the seismic strengthening technique considering the rocking behavior of the wall was developed. The rocking system rotates left and right around the vertical axis of the wall. The development system is a method of dissipating energy by installing a damper which was attached at a large displacement portion. The damper was made of a steel material, and the shape and height of the strut were selected as variables. Experimental results showed that in case of shorter strut make strength capacity increasement and in case of longer strut make deformation capacity increasement. As a result of comparing the abilities according to I and S type strut shapes, it was evaluated that S type has better seismic performance.

• Journal of KSNVE
• /
• v.10 no.2
• /
• pp.312-318
• /
• 2000

A modeling method for the vibration analysis of rotating cantilever plastes with stiffeners is presented. The equations of motion for the plates aer derived and trnasformed into a dimensionless form. A mass density Dirac's delta function is used to idealize the stiffener mathematically. The effects of stiffeners on the model characteristics of the plate are investigated, and mode shape variations due to some parameter variation are exhibited. It is found that veering phenomena occur between some loci and associated mode shapes change significantly during the veering phenomena.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.11a
• /
• pp.586-590
• /
• 2006

This paper presents a new vibration control device by which the mass and damping of a structure is increased equivalently. The vibration control system, named toggle-rotational inertia-viscous damper, can be utilized effectively in applications of small structural drift. Numerical analysis shows that because the relative drift of a structure can be effectively amplified by the toggle system, the device has a great performance in the vibration control without the increase of the damper capacity and size. It is also observed that vibration control effects is caused by the increase of equivalent mass and damping due to the rotational inertia and damping of the device.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2010.05a
• /
• pp.145-146
• /
• 2010

A moment redistribution method was developed for earthquake design of reinforced concrete moment-resisting frames. For a frame designed with strong column-weak beam, the moment redistribution mechanism was investigated. Based on the result, the relationship between redistributed moment and plastic rotation in plastic hinges was established. By using the relationship, we developed a method for the evaluation of plastic rotations during the moment redistribution, addressing the effects of various design parameters including member stiffness, load condition, and plastic mechanism of structure.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.2
• /
• pp.127-134
• /
• 2008

The aerodynamically excited vibration and natural frequency of rotating disks are analytically studied in this paper. The theoretical analysis uses a fluid-structure model where the aerodynamic effects are represented in terms of elastic, lift and drag forces. The explicit expressions on natural frequencies of the air coupled disk are obtained as functions of the aerodynamic coefficients. for the three cases where the disk rotates in three different cases (in vacuum, in open air without enclosure, and close to rigid wall). The theoretical results give that the natural frequencies of rotating disks in air are smaller than those in vacuum, because the effect of the added fluid mass decreases the frequencies. This paper also proposes an analytical method to predict the flutter speed of a rotating disk.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.32 no.2
• /
• pp.135-142
• /
• 2008

Experimental studies on the aerodynamic coupling effect on natural frequencies, critical speed and flutter instability of rotating disks are investigated in this paper. The theoretical analysis uses a fluid-structure model where the aerodynamic effects are represented in terms of elastic, lift and damping and stiffness components. The experiments performed using a vacuum chamber and ASMO/DVD disks rotating in vacuum, open and enclosure in several gaps with stationary wall give three main results. One is that the aerodynamic effect by the surrounding air reduces the natural frequencies and critical speeds of the vibration modes. The second is that natural frequency of disks rotating in open air is larger than that in enclosure. Finally, it is shown that the disk vibration is reduced as the gap between the disk and the rigid wall decreases.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.05a
• /
• pp.819-822
• /
• 2001

ISO TC 108/SC 2 산하에 이미 제정된 24 개의 관련 규격이 있으며, 그 중에 현재 4 개의 규격이 개정 심의 중에 있다. 본 논문에서는 FDIS(Final Draft International Standard) 개정 단계에 있는 육상용 증기 터빈 발전기 세트의 회전축 진동 및 비회전부 진동에 관련한 두 규격(ISO 7919-2:1996, ISO 10816-2:1996) 과 2000년 12월 15일자로 개정 완료된 선박 거주구역 및 작업구역의 진동에 관한 규격(ISO 6954:2000)을 개정 전 규격과 비교 설명 하고자 한다. (중략)