• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2008년도 추계학술대회 논문집
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• pp.631-632
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• 2008

• 한국지반신소재학회논문집
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• 제20권1호
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• pp.21-34
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• 2021

단일지반에서의 경험토압을 다층지반에 적용할 때 각 지층이 토압에 기여하는 효과를 고려할 수 없는 문제 등을 해결하고자 국내외에서 지반굴착시 측정된 토압을 조사하고 분석하였다. 다층지반의 토압은 단일지반의 경험토압과 상이하고, 대표 토질이 아닌 지층의 토압 기여 효과를 고려할 수 없음을 확인하였다. 본 연구에서는 기존의 단일지반에 대한 경험토압 산정방법을 다층지반까지 확장하여 단일지반과 다층지반 모두 적용 가능한 방법을 제안하고 검증하였다. 제안방법은 굴착심도 0.1Z/H 이하에서 실측값에 더 근접한 토압을 예측하는 등 기존 단일지반의 토압보다 예측 신뢰도가 우수한 것으로 평가되었다. 제안방법 중 주동상태에서의 파괴면적비를 고려하는 방법이 지반공학적 타당성을 갖추고도 실측토압과 가장 유사한 결과를 도출하였다. 또한, 제안방법의 적용성을 확인하고자 실제 설계사례에 대해 제안방법과 기존 방법의 설계 결과를 비교 분석하여 제시하였다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2008년도 추계학술대회논문집
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• pp.489-496
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• 2008

This paper investigates active noise control of ducts using Filtered-x Least Mean Square (FXLMS) algorithms to reduce noise transmission. Single channel FXLMS (MFXLSM) and multiple channel FXLMS (MFXLMS) algorithms are used to implement the active control systems. The transmission loss is significantly increased by SFXLMS but the sound pressure level (SPL) at the upstream of the error sensor is increased while that of downstream is very low. This increase of the upstream SPL causes the duct wall to vibrate and so to radiate noise. To prevent the wall vibration generated by the sound field upstream, global sound field control is required. To reduce SPL globally along the duct, active noise control using MFXLMS is implemented. We can then obtained globally reduced SPL. It is found experimentally that the vibration level, and so the radiated noise level. can be reduced by the active noise control using MFXLMS.

• 한국소음진동공학회논문집
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• 제19권1호
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• pp.24-34
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• 2009

This paper investigates active noise control of ducts using filtered-x least mean square(FXLMS) algorithms to reduce noise transmission. Single channel FXLMS(SFXLSM) and multiple channel FXLMS(MFXLMS) algorithms are used to implement the active control systems. The transmission loss is significantly increased by SFXLMS but the sound pressure level(SPL) at the upstream of the error sensor is increased while that of downstream is very low. This increase of the upstream SPL causes the duct wall to vibrate and so to radiate noise. To prevent the wall vibration generated by the sound field upstream, global sound field control is required. To reduce SPL globally along the duct, active noise control using MFXLMS is implemented. We can then be obtained globally reduced SPL. It is found experimentally that the vibration level, and so the radiated noise level, can be reduced by the active noise control using MFXLMS.

• Wind and Structures
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• 제17권4호
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• pp.399-417
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• 2013

The structural vibration suppression with active constrained layer damping (ACLD) was widely studied recently. However, the literature seldom concerned with the vibration control on flow-induced vibration using active constrained layer. In this paper the wind induced vibration of cantilevered beam is analyzed and suppressed by using random theory together with a velocity feedback control strategy. The piezoelectric material and frequency dependent viscoelastic layer are used to achieve effective active damping in the vibration control. The transverse displacement and velocity in time and frequency domains, as well as the power spectral density and the mean-square value of the transverse displacement and velocity, are formulated under wind pressure at variable control gain. It is observed from the numerical results that the wind induced vibration can be significantly suppressed by using a small outside active voltage on the constrained layer.

• 한국전문물리치료학회지
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• 제18권3호
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• pp.67-75
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• 2011

The purpose of this study was to assess the agreement of manual muscle testing (MMT) and test-retest reliability of a hand held dynamometer for the posterior gluteus medius muscle, with and without lumbar stabilization, using a pressure biofeedback unit for patients with low back pain. The pressure biofeedback unit was used to minimize the substitute motion of the lumbopelvic region during hip abduction in patients lying on their side. Fifteen patients with low back pain participated in this study. A tester determined the MMT grades of the posterior gluteus medius with and without the pressure biofeedback unit. Active hip abduction range of motion with an inclinometer and the strength of their posterior gluteus medius using a hand held dynamometer were measured with and without the pressure biofeedback unit in the MMT position. The agreement of the grade of muscle strength in the MMT, and intra-rater reliability of both the active hip abduction range of motion and the strength of posterior gluteus medius were analyzed using the weighted kappa and intraclass correlation coefficient (ICC), respectively. The agreement of MMT with the pressure biofeedback unit (weighted kappa=.92) was higher than the MMT (weighted kappa=.34)(p<.05). The inclinometer with pressure biofeedback unit measurement of the active hip abduction range of motion had an excellent intra-rater reliability (ICC=.90). Also, the hand held dynamometer with pressure biofeedback unit measure of strength of the posterior gluteus medius had a good intra-rater reliability (ICC=.85). Therefore, the test for muscle strength with pressure biofeedback unit will be a reliable method for the determination of the MMT grades or amount of posterior gluteus medius muscle strength and the measurement of the range of motion for hip abduction in patients with low back pain.

• 한국지반환경공학회 논문집
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• 제13권12호
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• pp.67-74
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• 2012

기존건물의 지하층과 인접하여 굴착 시 양단벽체 토사의 마찰로 발생하는 아칭효과는 굴착벽체에 작용하는 토압을 경감시키게 된다. 본 논문에서는 굴착깊이에 대한 배면폭의 비와 벽마찰각의 변화에 따른 아칭효과의 변화를 다양한 조건에서 수치해석을 통하여 살펴보았다. 수치해석 모델은 원심모형시험결과를 바탕으로 검증하여 적용하였으며, 아칭에 의한 토압경감 효과는 굴착깊이에 대한 배면폭의 비가 작고 벽마찰각이 커짐에 따라 증가함을 알 수 있었다. 이와 같은 아칭 현상은 기존의 아칭이론 중 Handy(1985)가 제안한 이론식을 통하여 가장 정확히 묘사 가능함을 알 수 있었다.

• 한국미생물·생명공학회지
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• 제28권1호
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• pp.26-32
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• 2000

Electrostatic forces contribute to the high degree of enzyme transition state complementarity in enzyme catalyzed reaction and such forces are modified by the solvent through its dielectric constant and polar properties. The contributions of electrostatic interaction to the formation of ES complex and the stabilization of transition state of the trypsin catalyzed reaction were probed by kinetic studied with high pressure and solvent dielectric constant. A good correlation has been observed between the increase of catalytic efficiency of trypsin and the decrease of solvent dielectric constant. Activation volume linearly decreased as the dielectric constant of solvent decreased, which means the increase in the reaction rae. Moreover, the decrease of activation volume by lowering the solvent dielectric constant implies a solvent penetration of the active with and a reduction of electrostatic energy for the formation of dipole of the active site oxyanion hole. When the 야electric constant of the solvents was lowered to 4.7 unit, the loss of activation energy and that of free energy of activation were 2.262 KJ/mol and 3.169 KJ/mol, respectively. The results of this study indicate that the high pressure kinetics combined with solvent effects can provide unique information on enzyme reaction mechanisms, and the controlling the solvent dielectric constant can stabilize the transition state of the trypsin-catalyzed reaction.

• 제어로봇시스템학회논문지
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• 제11권5호
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• pp.451-456
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• 2005

This paper describes three kinds of experiments and analysis of their results related to human tactile sensitivity using an integrated tactile display system. The device can provide vibration, normal pressure and lateral slip/stretch which are important physical quantities to sense texture. We have tried to find out the efficient method of stimulating, limitation of surface discrimination by kinesthetic farce feedback and the effectiveness of the combination of kinesthetic force and tactile feedback. Seven kinds of different stimulating methods were carried out and they are single or combination of the kinesthetic force, normal static pressure, vibration, active/passive shear and moving wave. Both prototype specimen and stimulus using tactile display were provided to all examinees and they were allowed to answer the most similar sample. The experimental results show that static pressure is proper stimulus for the display of micro shape of the surface and vibrating stimulus is more effective for the display of fine surface. And the sensitivities of active touch and passive touch are compared. Since kinesthetic force feedback is appropriate to display shape and stiffness of an object, but roughness display has a limitation of resolution, the concurrent providing methods of kinesthetic and tactile feedback are applied to simulate physical properties during touching an object.

• 공업화학
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• 제19권2호
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• pp.236-241
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• 2008

자외선 조사에 따른 광촉매 $TiO_2$의 표면에서 발생하는 활성산소종의 기상확산을 이용하여 실리콘기판 위에 산화박막을 성장시켰다. 자외선의 세기, 기판의 온도와 반응기 내의 산소 압력을 공정변수로 한 결과, 일정두께의 실리콘 산화박막의 성장이 자외선의 세기가 증가할수록 빨랐으며, 자외선램프의 세기를 60 W BLB 램프에서 1 kW 고압수은 랩프로 변경할 경우 성장속도가 8배 정도 빨라졌다. 반응기 내의 압력이 증가할수록 실리콘 산화박막의 성장속도는 느렸다. 대부분 산화박막의 성장은 $20{\AA}$에서 포화되었으며, 자외선의 세기가 증가할수록 포화상태까지 도달시간이 빨라졌다. 성장된 산화박막을 열처리를 통하여 전형적인 열산화막의 물성에 도달할 수 있었다. 광활성 산소종의 기상확산은 실리콘 산화박막의 저온 형성에 대한 광촉매 활용이라는 새로운 산화공정 방법으로 사용이 가능함을 확인할 수 있었다.