• 한국해양공학회지
• /
• 제24권1호
• /
• pp.34-38
• /
• 2010

An analytical solution procedure for the dynamic response of beams with variable properties is developed by using an asymptotic solution and the Green's function. This asymptotic closed form solution is derived for the transverse vibration of beams under the assumption of slowly varying properties, such as mass, cross-section, tension etc., along the beam length. However, this solution is still found to be very accurate even in the case of large variation, such as step change in cross-section, mass, and tension. Therefore, this derived asymptotic closed form solution and the Green's function can be easily applied to find dynamic responses for various kind of beam vibration problems.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2006년도 춘계 학술발표회 논문집
• /
• pp.1334-1339
• /
• 2006

Dynamic response of buried pipelines both in the axial and the transverse directions on concrete pipe and steel pipe, FRP pipe were investigated through a forced vibration analysis. The dynamic behavior of the buried pipelines for the forced vibration is found to exhibit two different forms, a transient response and a steady state response, depending on the time before and after the transfer of a seismic wave on the end of the buried pipeline. The former is identified by a slight change in its behavior before the sinusoidal-shaped seismic wave travels along the whole length of the pipeline whereas the latter by the complete form of a sinusoidal wave when the wave travels throughout the pipeline. The transient response becomes insignificant as the wave speed increases. From the results of the dynamic responses at the many points of the pipeline, we have found that the responses appeared to be dependent critically on the boundary end conditions. Such effects are found to be most prominent especially for the maximum values of the displacement and the strain and its position.

• 한국공작기계학회:학술대회논문집
• /
• 한국공작기계학회 2004년도 추계학술대회 논문집
• /
• pp.416-421
• /
• 2004

Off-line feedrate scheduling is presented as the advanced technology to regulate cutting forces at the desired level through change of feedrates. In rough cutting, the feedrate scheduling aims at reducing the machining time, which is the most important factor for better productivity. Thus, the largest force which can avoid breakage of tool shank and tooth is a reference force for feedrate scheduling in rough cutting. In this paper, a calculation method of the reference cutting force for feedrate scheduling is developed. This model calculates rupture plane of tooth using the FEM analysis of a tool and computes the reference force using the transverse rupture strength of a tool. Experiments validate that the presented feedrate scheduling model reduced machining time drastically and regulate cutting forces at the reference cutting force.

• 대한기계학회논문집A
• /
• 제25권5호
• /
• pp.866-873
• /
• 2001

The governing partial differential equations of a helical spring with a circular section were derived from Frenet formulas and Timoshenko beam theory. These were solved to give the dispersion relationship between wave number and frequency along with wave form. Wave motions of helical springs are categorized by 4 regimes. In the first regime, the lower frequency area, the torsional and extensional waves of the spring are predominant and two waves are composite wave motions involving lateral motion of the coils and rotation of the coils about a horizontal axis. All waves are propagating in the second regime. The wave of the extensional motion of the spring and one wave of transverse motion of a wire change from travelling waves to near field waves in the third regime. Both waves excited by both axial and transverse motion are predominant in the fourth regime.

• Journal of the Optical Society of Korea
• /
• 제10권2호
• /
• pp.63-66
• /
• 2006

In microband-induced fiber gratings, polarization properties and birefringence are investigated as a function of an applied line force. With the transmission curves associated with the maximum and minimum resonant wavelengths, the polarization-dependent behaviors are analyzed. By increasing the transverse line force, the resonance wavelength for an incident light polarized to the same direction of the force is blue-shifted as much as 0.69 nm/(N/cm) while that for the other polarization is insensitive. Using the resonant wavelength separation corresponding to the force variation, the transverse effective index change or modal birefringence variation is obtained. The ratio of modal birefringence versus applied line force is ${\Delta}B/{\Delta}f_x={\sim}8.38{\times}10^{-7}$.

• 한국안전학회지
• /
• 제24권6호
• /
• pp.93-102
• /
• 2009

Because steel girder bridge has big slenderness ratio, buckling is very important in design. Local buckling of plate girders having two longitudinal stiffeners in different positions under various load conditions is investigated. Various parametric study according to the change of web height, transverse stiffeners and load conditions are examined. These parametric studies are performed by numerical simulation utilizing finite element method. The objective of this study is to present the rational reinforcement location of two longitudinal stiffeners. The results of analysis are compared to that recommended by korean specifications for road bridges(2003).

• 한국안전학회지
• /
• 제24권4호
• /
• pp.82-89
• /
• 2009

Unlike concrete bridge, steel bridge resists external force by forming thin plate. Thus, because steel girder bridge has big slenderness ratio, buckling is a major design factor. Plate girder consists of flange and web plate. Because of economic views, web plate that resists shear forces is made by more thinner plate. Thus, web plate has much risk for buckling. The objective of this study is to analyze the buckling behaviors of plate girder and to present the proper reinforcement location of longitudinal stiffeners. Various parametric study according to the change of web height, transverse stiffeners and load condition are examined.

• 대한정형도수물리치료학회지
• /
• 제28권2호
• /
• pp.7-14
• /
• 2022

Purposed: This study was conducted to find out by ultrasonic waves the thickness change of the deep abdominal muscles, such as transverse abdominal, internal oblique and external oblique when performing general bridge exercise on the stable surface (GBE), single-legged bridge exercise on the stable surface (BES), bridge exercise with a sling (SBE) and single-legged bridge exercise with a sling (SBS). Methods: The subject, 33 healthy adults(18 men and 15 women) in their 20s of V university in J city were subjected to take four postures of GBE, BES, SBE, and SBS. When performing each posture, the thickness of transverse abdominal, internal oblique and external oblique were measured by ultrasonic waves and analyzed by repeated measures of ANOVA. This significance level was set to be p<.05. Results: Muscle thickness was increased in the order of BES, SBE, and GBE in the external oblique, resulting in statistically significant differences(p<.001). The internal oblique was significantly thicker in SBE and SBS rather than in GBE, and was thicker in SBE and SBS rather than in BES (p<.01). The thickness of the transverse abdominal was significantly increased in SBS than in GBE (p<.01). Conclusion: As the result, it may be more effective for the trunk stabilization exercises to activate the internal oblique and transverse abdominal by applying both-legged or single-legged bridge exercise in slings.

• PNF and Movement
• /
• 제20권2호
• /
• pp.285-293
• /
• 2022

Purpose: The purpose of this study was to confirm that the activation of the contralateral muscles changes according to posture after applying the proprioceptive neuromuscular facilitation leg pattern. Methods: Ten healthy adults (four males and six females) with no history of current musculoskeletal/neurological injuries were recruited for this study. Abdominal muscle (transverse abdominis) and hip joint muscle (gluteus maximus and gluteus medius) activation was assessed using surface electromyography (Ultium EMG, Noraxon Inc., USA). We evaluated muscle activation during the application of the PNF leg pattern. The data were analyzed using the SPSS version 21.0 program. Results: The results were found to be statistically significantly different in the 90/90 supine posture and sitting posture for the gluteus maximus (p < 0.05). The results were found to be not statistically significantly different for the transverse abdominis according to posture (p > 0.05). The results were found to be not statistically significantly different for the gluteus medius according to posture (p > 0.05). Conclusion: Application of the PNF leg pattern resulted in a significant change in the muscle activation of the contralateral segment according to posture, and the 90/90 supine posture induced high muscle activation of the gluteus maximus. In addition, the activation of the transverse abdominis was high in all three postures.

• 한국진공학회지
• /
• 제20권1호
• /
• pp.1-6
• /
• 2011

포항광가속기의 섹터 진공용기에 부착된 빔위치측정기의 수직방향 위치 읽음 값이 갑자기 변하는 오류가 관찰되었다. 이 오류의 원인을 알기 위해서 섹터 진공용기의 양 끝단에 있는 빔위치측정기의 전극을 통한 고주파전달 산란계수를 측정하였다. 급한 변화를 보이는 섹터 진공용기에서는 측정한 산란계수의 첨단 값이 빔위치측정기의 작동 주파수 내에 존재함을 확인하였고, 전산시늉을 통해 빔위치측정기의 작동 주파수내 첨단 주파수가 가로 전장 모드의 공진모드와 일치함을 확인하였다.