• 대한치과보철학회지
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• 제36권2호
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• pp.245-257
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• 1998

This study was performed to measure the changes of the mandibular movement and the masticatory muscular activities - anterior temporal and masseter muscle of both side - reflected by intentional increase of anterior guidance angie. For this study, 5 volunteers (3 males and 2 females with average age of 24.0) were selected. Each volunteer had Angle's classification I and did not have any missing tooth except third molar and any extensive restorations. Metallic guide plate was made at volunteer's working model fabricated by improved dental stone and cemented to the palatal surface of maxillary central incisor using resin cement(Panavia $21^{(R)}$) and then adjusted not to give any occlusal interferences at intercuspal position. The activity of masticatory muscles and the changes of mandibular movement were recorded by EMG and Sirognathograph in Biopak analysing system(Bioresearch Inc., Milwaukee, Wisconsin, USA). Measurement was done at before experiment, immediatley after placement, 1 week after placement, immediately after removal, and 1 week after removal. The results were as follows: 1. Moderate phonetic disturbance and mild headache were occured to 3 volunteers for 2 days after setting and 1 volunteer had positive reaction to percussion and slight midline diastema. But all of these clinical signs were diappeared 1 week after removal and the other volunteer did not have any special clinical sign. 2. In the EMG of the mandibular rest position, the mean value of anterior tempotal muscle was increased immediately after placement(p<0.01) and then decreased 1 week after placement(p<0.05) and increased 1 week after removal(p<0.05) but not recovered as before experiment. The mean value of masseter muscle was decreased during the experiment period. 3. In the EMG during mandibular protrusive movement, all muscular activity was decreased during the experiment period. Reduced activity was not recovered 1 week after removal(p<0.03). 4. During the habitual opening, anteroposterior movement of mandible was decreased immediately after placement(p<0.05) and then increased 1 week after placement but not statistically significant(p>0.1). Vertical movement was not shown significant difference during the experiment period(p>0.1). Lateral movement was decreased immediately after placement(p<0.05) and then increased 1 week after placement but not recovered as before experiment. The opening and closing velocity of mandible was shown minor changes but not statistically significant. 5. During the habitual opening, anteroposterior movement of mandible was decreased 1 week after placement(p<0.05) and then increased immediately after removal and recovered 1 week after removal as before experiment. Vertical movement was not shown significant changes. Lateral displacement of mandible was increased continuously and recovered 1 week after removal. Opening velocity was temporarily increased immediately after removal but recovered and closing velocity was not shown significant changes. 6. During the right side chewing, anteroposterior movement of mandible was increased immediately after removal but recovered and vertical movement was not shown statistically significant results. Lateral displacement and velocity of mandible were not shown significant results. 7. During the left side chewing, the changes of mandibular movement pattern were not shown statistically significant results.

• 전자공학회논문지
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• 제50권1호
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• pp.261-268
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• 2013

본 논문은 지능형 보행보조로봇이 횡단경사면주행에 있어 직진성 향상 알고리즘을 제안한다. 보행보조로봇은 횡단경사면주행시 로봇의 무게와 경사도에 의해 발생되어지는 회전모멘트의 영향을 받아 경로 이탈을 하게 된다. 이를 보정하기 위해 사용자가 입력하는 목표 회전각속도와 로봇의 회전각속도와의 비교를 통해 각 구동축에 가중치를 인가하는 알고리즘을 적용하였다. 제안한 보정 제어기를 실\제 보행보조로봇에 적용한 결과 횡단경사면 이동시 Yaw 축 이탈거리는 무보정 실험의 경우 발산하지만 Yaw 보정 알고리즘을 적용하였을 경우에는 이탈거리가 최대 20cm 이내로 안정적인 주행을 하는 것을 확인할 수 있었으며, 이탈거리 변화율 또한 300cm 이후 안정화되어 더 이상의 변화가 발생하지 않는 것을 확인할 수 있었다.

• Physical Therapy Rehabilitation Science
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• 제7권4호
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• pp.172-178
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• 2018

Objective: The purpose of this study was to show the temporary effects of performing jumping lunges on a sand surface on static balance and dynamic balance. Design: Randomized controlled trial. Methods: Twenty healthy subjects volunteered in the study and was randomly assigned into either the sand group (n=10) or the control group (n=10). The subjects in the sand group performed jumping lunges on a sand surface and the subjects in the control group performed jumping lunges on a firm surface. The intervention was performed for 3 sets of 8 repetitions by both groups. To measure static balance, the force plate was employed to measure the center of pressure (CoP) area, and the CoP velocity during one-legged standing. Anterior, postero-medial, postero-lateral movements was assessed using the Star Excursion Balance Test (SEBT) to measure dynamic balance. Results: After the intervention, the sand group showed statistically significant improvements on all variables (CoP area, CoP velocity) in static balance (p<0.05). There were statistically significant changes in CoP area and CoP velocities between the two groups (p<0.05). In the sand group, there were significant improvements in the postero-medial and postero-lateral directions (p<0.05) except for anterior direction on dynamic balance. In the control group, there was a significant improvement in the postero-lateral and anterior directions (p<0.05). In comparison of the two groups, there was no statistically significant improvement in all variables. Conclusions: This study demonstrated that performing jumping lunges on a sand surface was effective in improving static and dynamic balance temporarily.

• 대한전자공학회논문지SD
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• 제37권4호
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• pp.25-30
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• 2000

금속 유도 측면 결정화에 의한 다결정 실리콘 박막 트랜지스터의 제작에서 이온 질량 주입이 MILC 속도 및 거동에 미치는 영향을 분석하였다. 비정질 실리콘에 도펀트를 주입하거나 이온충돌을 가하면 MILC의 속도가 50% 이상 감소하고 MILC선단이 불균일 해졌다. IMD에 따른 비정질 실리콘 박막의 성질 변화를 분석하기 위하여 자외선 반사도 및 표면 거칠기를 관찰하였고, 이온 충돌에 의한 표면 거칠기의 증가가 MILC 속도 감소와 균일도에 영향을 주는 것으로 나타났다.

• Nuclear Engineering and Technology
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• 제53권4호
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• pp.1119-1126
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• 2021

Spacer grid with mixing vane had been widely used in nuclear reactor core. One of the main feather of spacer grid with mixing vane was that strong swirl flow was formed after the spacer grid. The swirl flow not only changed the bubble generation in the near wall field, but also affected the bubble behaviors in the center region of the subchannel. The interaction between bubble and the swirl flow was one of the basic phenomena for the two phase flow modeling in fuel assembly. To obatin better understanding on the bubble behaviors in swirl flow, full three dimension numerical simulations were conducted in the present paper. The swirl flow was assumed in the cylindral calculation domain. The bubble interface was captured by Volume Of Fluid (VOF) method. The properties of saturated water and steam at different pressure were applied in the simulation. The bubble trajectory, motion, shape and force were obtained based on the bubble parameters captured by VOF. The simulation cases in the present study included single bubble with different size, at different angular velocity conditions and at different pressure conditions. The results indicated that bubble migrated to the center in swirl flow with spiral motion type. The lateral migration was mainly related to shear stress magnitude and bubble size. The bubble moved toward the center with high velocity when the swirl magnitude was high. The largest bubble had the highest lateral migration velocity in the present study range. The effect of pressure was small when bubble size was the same. The prelimenery simulation result would be beneficial for better understanding complex two phase flow phenomena in fuel assembly with spacer grid.

• 지구물리와물리탐사
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• 제12권1호
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• pp.85-98
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• 2009

굴절법 토모그래피를 구현하는 대부분의 컴퓨터 프로그램은 타우-피 역산 알고리즘을 이용하여 초기 모델을 생성한다. 타우-피 역산 알고리즘은 지층의 수직 분해능에 초점을 맞추기 때문에 전단 영역의 존재를 지시하는 탄성파 속도의 감소와 같은 수평적인 변화를 탐지하는데 실패하는 경우가 자주 발생한다. 본 연구에서는 타우-피 역산 알고리즘이 50미터 혹은 10개 측점 너비의 주요 전단 영역을 탐지하거나 정의하는데 실패하는 사례를 보여준다. 그럼에도 불구하고 대다수의 굴절법 토모그래피 프로그램들이 각 지층의 수직 속도 구배로 탄성파 속도를 매개화한다. 이와는 달리, 일반상반성방법(Generalized Reciprocal Method; GRM) 역산 알고리즘은 개별 지층의 수평 분해능을 강조한다. 본 연구에서는 GRM 역산 알고리즘을 이용하여 50미터 폭의 전단 영역을 성공적으로 탐지하고 정의하는 사례를 보여준다. 전단 영역의 존재는 2차원 선두파 진폭분석과 이후의 3차원 굴절법 탐사의 일환으로 수행된 몇 개의 근거리 직교 탄성파 탐사에 의해 확인된다. 또한. 송신원 기록 진폭분석 결과는 풍화대에서 수직 속도 구배보다는 속도역전이 발생하는 것을 보여준다. 결론적으로 말하면, 모든 탄성파 굴절법 탐사가 실용적으로 정확한 심도추정 결과를 제공하는 것을 목적으로 하면서도 개별 지층의 수평 분해능을 강조하는 기법들이 지질환경공학적인 응용에 더 유용한 결과를 생성한다는 것이다. 향상된 수평 분해능의 장점은 구조적 특징이 탄성파 속도의 변화 크기로부터 인식될 수 있는 2차원 트래버스(tracverse)로 얻어질 수 있다. 또한, 3차원 탐사로부터 얻어진 공간 패턴은 탄성파 속도에서는 고유한 변화나 징후를 보이지 않는 단층과 같은 구조적 특징의 인식을 가능하게 한다.

• 한국지반공학회논문집
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• 제20권6호
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• pp.51-59
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• 2004

공학적 물성치로서의 저변형율에서의 전단탄성계수의 결정은 다양한 토목분야에서 매우 중요하다. 본 논문에서는 저변형율에서의 전단탄성계수를 결정하기 위하여 개발된 HWAW(Harmonic Wavelet Analysis of Wave)방법을 이용한 지반조사기법의 실제 현장에서의 타당성을 검증하기 위하여 두 곳의 현장에 HWAW방법을 적용하였다. HWAW방법을 검증하기 위하여 동일한 현장에서 수행된 SASW시험과 PS-Suspension Logging 실험의 결과와 비교하였다. 이를 통하여 HWAW방법이 배경잡음과 지반의 횡방향 불균일성에 의한 오류를 기존 방법에 비하여 최소화 할 수 있으며, 국부적이며 정밀한 대상지반의 실제 전단파 속도 주상도를 매우 효과적으로 결정할 수 있음을 확인할 수 있었다.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권4호
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• pp.691-698
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• 2015

The hydrodynamic interaction forces and moments induced by the vicinity of bank on a passing vessel are known as wall effects. In this paper, the characteristics of interaction acting on a passing vessel in the proximity of a semi-circle bank wall are described and illustrated, and the effects of ship velocity, water depth and the lateral distance between vessel and semi-circle bank wall are discussed. For spacing between ship and semi-circle bank wall (SP) less than about 0.2 L and depth to ship's draft ratio (h/d) less than around 2.0, the ship-bank interaction effects increase steeply as h/d decreases. However, for spacing between ship and semi-circle bank wall (SP) more than about 0.3 L, the ship-bank interaction effects increase slowly as h/d decreases, regardless of the water depth. Also, for spacing between ship and semi-circle bank wall (SP) less than about 0.2 L, the hydrodynamic interaction effects acting on large vessel increase largely as ship velocity increases. In the meantime, for spacing between ship and semi-circle bank wall ($S_P$) more than 0.3 L, the interaction effects increase slowly as ship velocity increases.

• Water Engineering Research
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• 제3권3호
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• pp.163-176
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• 2002

In this study, laboratory experiments have been performed to investigate characteristics of the velocity fields and turbulence for non-buoyant plane jet in the vicinity of the jet nozzle using PIV system. The experimental results show that, in the transition region, the lateral velocity profile is in good agreement with Gaussian distribution. However, the coefficient of Gaussian distribution, $\K_{u,}$, decreases with longitudinal distance in the transition region. The existing theoretical equation for the centerline velocity tends to overestimate the measured data in the transition region. A new equation for the centerline velocity derived by incorporating varying $k_{u}$ gives better agreement with the measured data than the previous equation. The results of the turbulence characteristics show peak values are concentrated on the shear layers. The Reynolds shear stress profile shows the positive peak in the upper layer and negative peak in the lower layer. The turbulent kinetic energy also provides double peaks at the shear layers. The peak of the Reynolds shear stress and the turbulent kinetic energy increases until x/B=8, and then it decreases afterwards.s.

• Wind and Structures
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• 제38권6호
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• pp.445-459
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• 2024

To model the aeroelasticity in vortex-induced vibrations (VIV) of slender tubular towers, this paper presents an approach where the aerodynamic damping distribution along the height of the structure is calculated not only as a function of the normalized lateral oscillation but also considering the local incoming wind velocity ratio to the critical velocity (velocity ratio). The three-dimensionality of aerodynamic damping depending on the tower's displacement and the velocity ratio has been observed in recent studies. A contour map model of aerodynamic damping is generated based on the forced vibration tests. A sectional calculation procedure based on the spectral method is developed by defining the aerodynamic damping locally at each increment of height. The proposed contour map model of aerodynamic damping and the sectional calculation procedure are validated with full-scale measurement data sets of a rotorless wind turbine tower, where good agreement between the prediction and measured values is obtained. The prediction of cross-wind response of the wind turbine tower is performed over a range of wind speeds which allows the estimation of resulting fatigue damage. The proposed model gives more realistic prediction in comparison to the approach included in current standards.