• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 1990.04a
• /
• pp.12-17
• /
• 1990

Stepped bean with immovable ends for large amplitude of vibration including effects of longitudinal displacement, shear deformation and rotary inertia is investigated for free and forced vibration using finite element method. Modified harmonic force matrix is introduced for analysis of vibration with finite amplitude of the stepped beam under uniform hamonic loading and beam with nonuniform harmonic loading. Numerical examples of stepped beam with various support conditions are analysed for deflections and natural frequencies. Results show that the proposed method is valid and efficient.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2001.11b
• /
• pp.989-993
• /
• 2001

This paper deals with the free vibrations of horizontally curved beams supported by non-homogeneous elastic foundation. Taking into account the effects of rotatory inertia and shear deformation, differential equations governing the free vibrations of such beams are derived, in which the linear elastic foundation is considered as the non-homogeneous foundation. Differential equations are solved numerically to calculate natural frequencies. In numerical examples, the parabolic curved member is considered. The parametric studies are conducted and the lowest four frequency parameters are reported in tables and figures as the non-dimensional forms.

• Journal of KSNVE
• /
• v.4 no.4
• /
• pp.451-457
• /
• 1994

A numerical method is presented to obtain natural frequencies and mode shapes of uniform elastic beams with static deflections due to dead loads. The differential equation governing the free vibration of beam taken into account the static deflection due to deal loads is derived and solved numerically. The hinged-hinged, clamped-clamped and clamped-hinged end constraints are applied in the numerical examples. As the numerical results, the lowest three nondimensional frequency parameters are reported as functions of nondimensional system parameters; the load parameters, and the slenderness rations. And some typical mode shapes of free vibrations are also presented in figures.

• Proceedings of the Korean Society of Broadcast Engineers Conference
• /
• 2022.06a
• /
• pp.1275-1277
• /
• 2022

Structure-from-Motion(SfM), Multi-view Stereo(MVS)이 이용되는 3D Reconstruction 과정에서 생성된 3D 포인트 클라우드는 RGB 영상에 기반하여 생성되므로 실제 객체 혹은 Scene 과 달리 point 와 point 간에 존재하는 빈 공간이 발생한다. 이를 개선하기 위하여 3D 포인트 클라우드를 이용하여 3D Mesh 를 복원하는 Mesh Reconstruction 과정을 거치게 된다. 본 논문에서는 Mesh Reconstruction 과정에서 자유공간 지지도에 기반해 수정한 가중치를 이용하는 효율적인 방법을 제안한다. 실험을 통하여 제안한 알고리즘을 이용한 복원 결과가 기존보다 개선됨을 보인다.

• Monthly Duck's Village
• /
• v.62 no.8
• /
• pp.40-43
• /
• 2008

자유시장 경제를 신봉하는 사람들은 국가간 교역의 증대는 비교우위에 따른 무역의 증대를 의미하고 이것은 국가간 상호이익을 도모함으로써 세계적인 부를 증진시킨다고 주장한다. 세계화로 다른 나라의 다양한 물품을 우리나라 소비자들이 싼 값에 살 수 있고, 생산자도 세계의 넓은 시장에서 판매활동을 할 수 있으므로 세계적인 부를 증진시킨단 말은 일면 타당해 보인다. 그러나 후진국의 경제발전(특히 수입대체산업의 육성)에 악영향을 미칠 것이며, 선진국 경제에 후진국이 종속되는 결과를 낳을 것이라고 한다. 또한 세계화는 이익을 보는 계층과 손해를 보는 계층을 극명하게 나눠 놓음으로서 분쟁과 갈등을 증대시키는 면도 있다. 예를 들면 최근의 농산물시장의 개방에 따른 우리나라 농민들의 피해, 자본의 대량유입과 대량유출에 따른 외환위기의 위험성 등 개발도상국을 비롯한 중.후진국이 감수해야 할 지도 모르는 부담이 상당하다. 경제적인 종속 이외에도 사회적, 문화적인 종속을 우려하는 시각도 있다. 이러한 가운데 세계화를 주장하는 미국과 대립되는 상황이 나타나는데 이는 자국 문화를 수호하려는 정부의 노력으로 보인다.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.30 no.2
• /
• pp.111-117
• /
• 2017

In this paper, a local deformation effect in thin-walled box beams is investigated via a finite element modal analysis. The analysis is carried out for single-cell and multi-cell box beam configurations. The single-cell box beam with and without a neck, which mimics a simple wind-turbine blade, is analyzed first. The results obtained by shell elements are compared to those of one-dimensional(1D) beam elements. It is observed that the wall thickness plays a crucial role in the natural frequencies of the beam. The 1D beam analysis deviates from the shell analysis when the wall thickness is either thin or thick. The shell modes(local deformations) are dominant as it becomes thin, whereas the shear deformation effects are significant as it does thick. The analysis is extended to the single-cell box beam with a neck, in which the shell modes are confined to near the neck. Finally the multi-cell box beam with a taper, which is quite similar to real wind-turbine blade configuration, is considered to investigate the local deformation effect. The results reveal that the 1D beam analysis cannot match with the shell analysis due to the local deformation, especially for the lagwise frequencies. There are approximately 5~7% errors even if the number of segments is increased.

• Progress in Medical Physics
• /
• v.25 no.2
• /
• pp.72-78
• /
• 2014

The aim of the study is to test a hypothesis that quasi-breath-hold (QBH) biofeedback improves the residual respiratory motion management in gated 3D thoracic MR imaging, reducing respiratory motion artifacts with insignificant acquisition time alteration. To test the hypothesis five healthy human subjects underwent two gated MR imaging studies based on a T2 weighted SPACE MR pulse sequence using a respiratory navigator of a 3T Siemens MRI: one under free breathing and the other under QBH biofeedback breathing. The QBH biofeedback system utilized the external marker position on the abdomen obtained with an RPM system (Real-time Position Management, Varian) to audio-visually guide a human subject for 2s breath-hold at 90% exhalation position in each respiratory cycle. The improvement in the upper liver breath-hold motion reproducibility within the gating window using the QBH biofeedback system has been assessed for a group of volunteers. We assessed the residual respiratory motion management within the gating window and respiratory motion artifacts in 3D thoracic MRI both with/without QBH biofeedback. In addition, the RMSE (root mean square error) of abdominal displacement has been investigated. The QBH biofeedback reduced the residual upper liver motion within the gating window during MR acquisitions (~6 minutes) compared to that for free breathing, resulting in the reduction of respiratory motion artifacts in lung and liver of gated 3D thoracic MR images. The abdominal motion reduction in the gated window was consistent with the residual motion reduction of the diaphragm with QBH biofeedback. Consequently, average RMSE (root mean square error) of abdominal displacement obtained from the RPM has been also reduced from 2.0 mm of free breathing to 0.7 mm of QBH biofeedback breathing over the entire cycle (67% reduction, p-value=0.02) and from 1.7 mm of free breathing to 0.7 mm of QBH biofeedback breathing in the gated window (58% reduction, p-value=0.14). The average baseline drift obtained using a linear fit was reduced from 5.5 mm/min with free breathing to 0.6 mm/min (89% reduction, p-value=0.017) with QBH biofeedback. The study demonstrated that the QBH biofeedback improved the upper liver breath-hold motion reproducibility during the gated 3D thoracic MR imaging. This system can provide clinically applicable motion management of the internal anatomy for gated medical imaging as well as gated radiotherapy.

• Journal of Chest Surgery
• /
• v.37 no.10
• /
• pp.839-844
• /
• 2004

Background: The Y-composite graft of internal thoracic artery and radial artery is commonly used in coronary bypass surgery. The aim of this study is to look for a way to raise the free flow of the internal thoracic graft and to see flow dynamics of the Y-graft. Material and Method: In 15 patients undergoing coronary bypass surgery, free flow of the in-situ internal thoracic artery graft was measured using two different papaverine application methods; extraluminal papaverine spray in 7 patients and intraluminal papaverine injection in 8. In 18 other patients for whom the Y-graft was used, total free flow and flow changes from the two ends were measured. Result: The free flow of the in-situ internal thoracic artery graft almost doubled with internal papaverine injection than with external papaverine spray $(47.7\pm9.6$ mL/min $vs.100.8\pm26.3$ mL/min, p<0.001). Total flow of the Y-composite graft was significantly more than either flow of the internal thoracic artery end or radial artery graft end $(173.3\pm45.3$ mL/min vs. $121.1\pm34.3$ mL/min or $117.5\pm42.8$ mL/min). When both ends of the Y-composite graft were opened, free flows from the two ends were similar $(85.4\pm27.8$ mL/min vs: $87.9\pm42.4$ mL/min, p=0.772). The flow of one end of the Y-composite graft was increased significantly by clamping of the other-end than when both ends were opened. Conclusion: Intraluminal papaverine injection is very effective in raising free flow of the internal thoracic artery graft, and the free flow of the Y-composite graft of in-situ internal thoracic artery and free radial artery graft is more than that of the in-situ internal thoracic artery graft. The flow of one end flow of the Y-graft may be altered by the flow change of the other end.

• Korean journal of communication and information
• /
• v.32
• /
• pp.333-367
• /
• 2006

This paper attempted to examine to what extent advertising as expression has been constitutionally protected through an analysis on the reputational-right-related legal cases. In order to make the understanding more clearly, this paper applied Van Alstyne's graphical depiction on how commercial speech is protected compared with other constitutional rights such as political speech, private expression, defamation, and obscene expression. Through the analysis, this paper found out that first, in the legal cases, there has been no consideration on whether the status of the plaintiff is public figure or private figure, whereas in the libel cases, Korean courts has made a distinction between public figure and private figure since 2002; second, when the case is concerned with corporations, the Korean courts do not give consideration on the status of corporation, while the status of corporation is a somewhat important factor in deciding the degree of responsibility in the U.S.; third, even though it is clear that advertising in Korea is being protected as expression, it is nebulous whether it is well balanced with other personal rights that are constitutionally protected. Conclusively, applying the Alstyne's graphical depiction on Korean advertising, it advertising as expression in Korea is being provided lower protection than defamation. To put it differently, like the case in the U.S., advertising, although it is allegedly protected as expression, does not yet enjoy full-fledged constitutional protection in Korean society. Rather, there must be some actions to be taken to enhance the degree of protection of advertising.

• Phonetics and Speech Sciences
• /
• v.12 no.1
• /
• pp.19-31
• /
• 2020

The purpose of this study is to observe the realization of pause and breath groups from adult speakers and to examine how gender, generation, and tasks can affect this realization. For this purpose, we analyzed forty-eight male or female speakers. Their generation was divided into two groups: young, old. Task and gender affected both the realization of pause and breath groups. The length of the pause groups was longer in the read speech than in the spontaneous speech and female speech. On the other hand, the length of the breath group was longer in the spontaneous speech and the male speech. In the spontaneous speech, which requires planning, the speaker produced shorter length of pause group. The short sentence length of the reading material influenced the reason for which the length of the breath group was shorter in the reading speech. Gender difference resulted from difference in pause patterns between genders. In the case of the breath groups, the male speaker produced longer duration of pause than the female speaker did, which may be due to difference in lung capacity between genders. On the other hand, generation did not affect either the pause groups or the breath groups. The generation factor only influenced the number of syllables and the eojeols, which can be interpreted as the result of the difference in speech rate between generations.