• 한국산학기술학회논문지
• /
• 제14권3호
• /
• pp.1258-1265
• /
• 2013

본 논문의 목적은 랩탑 컴퓨터의 터치패드 및 두 개의 클릭 버튼 위치에 따른 손목과 어깨 부위 근육의 EMG 진폭 및 중앙 주파수 변화를 알아보는 것이다. 기존 연구결과를 바탕으로 손목과 어깨의 외전현상이 근골격계질환으로 이어지는 메커니즘을 살펴보고, 이를 토대로 연구가설이 설정되었다. 실험에서 터치패드 및 클릭버튼의 위치는 기존의 중앙 아래(bottom center, BC)와 중앙 아래에 위치하지만 $45^{\circ}$ 반시계방향으로 회전된 방식(bottom center with rotation, BCR), 그리고 회전없이 중앙 오른쪽에 위치한 경우(bottom right, BR)가 비교되었다. 10명의 피실험자는 오른 손으로 5분 동안 터치패드 및 두 개의 버튼을 이용하는 task를 각각의 시행하는 동안 EMG 진폭과 중앙 주파수가 측정되었다. 손목 부위의 근육은 척측수근굴근, 어깨부위의 근육은 위쪽 승모근이 선정되었다. 실험결과 손목부위에서는 BC의 경우가 진폭은 크게 나타나고 중앙 주파수는 작게 나타났으며, 어깨부위에서는 BC와 BCR이 BR보다 진폭은 크고 중앙 주파수는 작게 나타났다. 또한, 손목부위에서는 진폭과 중앙 주파수 모두에서 BCR과 BR의 차이가 유의하게 나타나지 않았고, 어깨부위에서는 BC와 BCR에서의 차이가 나타나지 않았다. 이러한 결과는 BC에서는 손목과 어깨의 외전이 동시에 나타나고, BCR은 어깨의 외전만, 그리고 BR은 손목과 어깨에서 외전이 모두 나타나지 않기 때문이다.

• 대한후두음성언어의학회지
• /
• 제11권2호
• /
• pp.178-184
• /
• 2000

Laryngeal evoked EMG is the objective and quantitative method to measure the innervation of laryngeal muscle. If there is a mobility disorder of vocal cords, the cause and location of neural lesion co be understood by the laryngeal evoked EMG and if there is a vocal cord paralysis, the degree of recovery and the policy of treatment can be determined by it. Recently, the studies of reinnervation after recurrent laryngeal nerve injury have been actively carried out. Laryngeal evoked EMC is useful to these studies. The aim of study is to know whether noninvasive methods for stimulating the recurrent laryngeal nerve and for recording of compound action potential(CAP) using surface electrode are as useful as the invasive method using needle electrode. We obtained EMG of laryngeal muscle by various stimulating and recording methods : 1) Direct nerve stimulation by placing nerve cuff electrode made out of silastic tube and platinum wire and recording by insertion of hook wire electrode into posterior cricoarytenoid(PCA) and thyroarytenoid(TA) muscles, respectively. 2) Recording of compound action potential by surface electrode after stimulation of recurrent laryngeal nerve by the insertion of 27 gauge of needle electrode. 3) Recording of compound action potential by surface electrode after stimulating the recurrent laryngeal nerve by transcutaneous blunt rod electrode at tracheoesophageal groove. The amplitude, duration and latency of the CAP evoked by recurrent laryngeal nerve stimulation were compared among the three groups. The amplitude of CAP was smallest in the group recorded from posterior cricoarytenoid and hyroarytenoid muscle, and that recorded by surface electrode after stimulation by needle electrode was largest. The difference in amplitude between the group by hook wire recording and the two groups by surface electrode recording was significant statistically. There is no significant difference in duration and latency among three groups. Since the waveform of CAP from all three methods has similar duration, latency, we concluded that noninvasive method is a useful as invasive methods.

• Journal of the korean society of oceanography
• /
• 제37권1호
• /
• pp.1-9
• /
• 2002

Cable voltage was measured simultaneously at Hamada, Japan and Pusan, Korea, using an inservice telephone cable from March to December 1990. The spectral and harmonic analyses of these data sets show that tidal signals are dominant, and that tidal constituents $M_2$ and $O_1$, which are not affected by solar geomagnetic variations, have almost the same amplitude and are of opposite phase to each other. comparing the voltage difference in 1990 with that measured using the now abandoned cable in 1998, there are dominant tidal signals at the same periods in both data sets. They have approximately the same amplitude and phase for $M_2andO_1$. The relationship between the observed voltage and the volume transport through the Korea Strait can be considered robust and stable over time. The conversion factor from voltage to transport is estimated to be $11.9{\times}10^6m^3S^{-1}volt^{-1}$ by comparing the amplitude of model-derived $M_2$ tidal transport with that of the voltage difference in 1998. This value changes to $8.6{\times}10^6m^3S^{-1}volt^{-1}$ when taking into consideration the horizontal electric current effect. This effect depends on the downstream length scale of the flow. To obtain a more reliable and stable conversion factor from voltage to transport, the voltage should be compared with observed sub-tidal transports, which may have long downstream length scales.

• 비파괴검사학회지
• /
• 제20권6호
• /
• pp.490-500
• /
• 2000

사용하는 탄성파의 파장과 두께가 비슷하거나 보다 얇은 박판 구조에서 음향방출(acoustic emission, AE) 신호의 위치표정 정확도의 향상을 위해 새로운 신호처리 방법인 웨이블릿 변환 디노이징(wavelet transform de-noising) 기법을 도입하였다. 탐지된 AE 신호에 대하여 웨이블릿 변환과 역변환을 수행하여 상대적으로 저주파수이고 큰 진폭을 갖는 굽힘파 성분(flexural component)은 활용하고, 고주파수이고 작은 진폭의 팽창파 성분(extensional component)은 필터링하여 제거한 다음 신호를 재구성하는 디노이징 처리를 거침으로써 박판에서의 위치표정 시 발생하는 도달시간차 측정오차를 최소화할 수 있음을 확인하였다. 따라서 웨이블릿 디노이징 처리를 도입함으로써 위치표정의 정확도가 게인(gain)이나 문턱값의 설정, 판의 두께, 센서간거리, 발생원과 센서의 상대적인 위치에 무관하고 전통적인 문턱값 통과 방법에 비하여 월등하게 향상되었다. 또한 상대적으로 매우 큰 진폭을 가지는 굽힘파 성분을 활용하므로 실제적인 박판 구조물에서의 위치표정에 효과적으로 활용될 수 있을 것이다.

• 산업기술연구
• /
• 제20권A호
• /
• pp.139-148
• /
• 2000

A numerical model is represented to calculate the wave fields such as the reflected waves, the transmitted waves, and depth averaged velocities over submerged breakwaters for the normally incident wave trains of nonlinear monochromatic wave. The numerical model is correctly formulated by using both the finite amplitude shallow water equations with the effects of bottom friction and the explicit dissipative Lax-Wendroff finite difference scheme, also satisfactorily verified by comparison with the other results. The behaviors of reflected and transmitted waves with respect to geometric parameters of submerged breakwater such as the slope, crest depth, and crest width are numerically analyzed in this study. In particular, the reflection and transmission coefficients are quantitatively calculated as the function of geometric parameter of submerged breakwater. It is found that the crest depth among parameters related to practical design may be the most important parameter in designing the submerged breakwater. Therefore, the effective and economic performances of submerged breakwater should be depended on the determination of optimal crest depth.

• 한국정밀공학회지
• /
• 제28권9호
• /
• pp.1070-1077
• /
• 2011

This study intends to assess the defect in the weld zone of titanium grade 2 plate in terms of acoustical anisotropy based on the angle beam method. Depending on the rolling direction, the ratio of wave velocity was found to be 1.08 and the difference in the angle of refraction was more than seven degrees, confirming the presence of acoustical anisotropy. Thus for measuring the length of defect in the weld zone of the titanium plate (thickness of 10mm), the distance amplitude characteristics curves of titanium, TDACC-R and TDACC-T were constructed for the measurements in consideration of the acoustical anisotropy on CRT of the ultrasonic testing equipment. As a result, when the distance amplitude characteristics curve corresponds to the rolling direction, the length of defect was close to the actual measurement within 1mm and when different, the difference was found to be over 4mm. It was affirmed that the acoustical anisotropy should be taken into consideration when measuring the length of defects in the weld zone of the titanium plate with the presence of acoustical anisotropy.

• 한국전산유체공학회지
• /
• 제6권4호
• /
• pp.26-34
• /
• 2001

The flow past a circular cylinder forced to vibrate transversely is numerically simulated by solving the two-dimensional Navier-Stokes equations modified by the vibration velocity of a circular cylinder at a Reynolds number of 164. The higher-order finite difference scheme is employed for the spatial discretization along with the second order Adams-Bashforth and the first order backward-Euler time integration. The calculated cylinder vibration frequency is between 0.60 and 1.30 times of the natural vortex-shedding frequency. The calculated oscillation amplitude extends to 25% of the cylinder diameter and in the case of the lock-in region it is 60%. It is made clear that the cylinder oscillation has influence on the wake pattern, the time histories of the drag and lift forces, power spectral density and phase diagrams, etc. It is found that these results include both the periodic (lock-in) and the quasi-periodic (non-lock-in) state. The vortex shedding frequency equals the driving frequency in the lock-in region but is independent in the non-lock-in region. The mean drag and the maximum lift coefficient increase with the increase of the forcing amplitude in the lock-in state. The lock-in boundaries are also established from the present direct numerical simulation.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2001년도 춘계 학술대회논문집
• /
• pp.181-188
• /
• 2001

The flow past a circular cylinder forced to vibrate transversely is numerically simulated by solving the two-dimensional Wavier-Stokes equations modified by the vibration velocity of a circular cylinder at a Reynolds number of 164. The higher-order finite difference scheme is employed for the spatial discretization along with the second order Adams-Bashforth and the first order backward-Euler time integration. The calculated cylinder vibration frequency is between 0.60 and 1.30 times of the natural vortex-shedding frequency. The calculated oscillation amplitude extends to $25\%$ of the cylinder diameter and in the case of the lock-in region it is $60\%$. It is made clear that the cylinder oscillation has influence on the wake pattern, the time histories of the drag and lift forces, power spectral density and phase diagrams, etc. It is found that these results include both the periodic (lock-in) and the quasi-periodic (non-lock-in) state. The vortex shedding frequency equals the driving frequency in the lock-in region but is independent in the non-lock-in region. The mean drag and the maximum lift coefficient increase with the increase of the forcing amplitude in the lock-in state. The lock-in boundaries are also established from the present direct numerical simulation.

• 한국전자파학회논문지
• /
• 제7권3호
• /
• pp.201-210
• /
• 1996

본 논문에서는 페이딩환경에서 16QAM Radio 시스템의 심볼 타이밍 복원에 대한 성능을 분석하였다. 심볼 타이밍 복원 방식으로서 파형 성형 필터 즉 raised cosine filter(RCF)와 비선형 필터를 사용하여 비영점교차방식인 MAM(Maximum Amplitude Method)과 WDM (Wave Difference Method)을 비교 분석하였다. 시뮬레이션에 의한 결과로부터 비선형 필터를 사용한 심볼 동기 방식(MAM and WDM)이 RCF를 사용한 것보다 지터 성능이 더 우수함을 알 수 있었다. 또한 레일리 페이딩채널을 추정하고 보상하기 위해 PSAM(Pilot Symbol Assisted Modulation)방식과 공간 다이버시티방석을 적용하였으며, $E_b/N_o$가 20dB일 때 $10^{-4}$의 BER(Bit Error Rate)성능을 얻을 수 있었다.

• 한국전기전자재료학회논문지
• /
• 제23권3호
• /
• pp.228-233
• /
• 2010

We studied the optical characteristics correlated with low dielectric constants of low-k SiOCH thin films through ellipsometry. The low-k SiOCH thin films were prepared by CCP-PECVD method using BTMSM(Bis-trimethylsilylmethane) precursors deposited on p-Si wafer. The Si-O-CHx, Si-O-Si, Si-CHx, CHx and Si-H bonding groups were specified by FTIR spectroscopic spectra, and the groups coupled with the nano-porous structural organic/inorganic hybrid-type of SiOCH thin films which has extremely low dielectric constant close to 2.0. The structural groups includes highly dense pore as well as ions in SiOCH thin films affecting to complex refraction characteristics of single layer on the p-Si wafer. The structural complexity originate the complex refractive constants of the films, and resulted the elliptical polarization of the incident linearly polarized light source of Xe-light source in the range from 190 nm to 2100 nm. Phase difference and amplitude ratio between s wave and p wave propagating through SiOCH thin film was studied. After annealing, the amplitude of p wave was reduced more than s wave, and phase difference between p and s wave was also reduced.