• 대한임상전기생리학회지
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• 제8권1호
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• pp.43-50
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• 2010

Purpose : The objective of this study is to effect of an aquatic rotation control and obstacle avoidance when conducted underwater on hemiplegia patient's balance ability and vestibular function. Methods : Twelve hemiplegia patients participated and were randomly assigned to a control group(I) with standard physical therapy and an aquatic group(II) with an aquatic rotation control, obstacle avoidance and standard physical therapy as well. The aquatic group trained using a Halliwick rotation control and obstacle avoidance through 3 times per week over 6 weeks. For all subjects, vestibular function, their balance, the change of electrooculogram (EOG), the change of accelerometer axis and torsiometer according to visual sense, vestibular sense with galvanic vestibular stimulation (GVS) or not during leg close stance were measured. Results : The EOG in the vertical and horizontal (p<0.05) were both significantly lowered. The change was significantly lower in the trajectory range of motion of trunk and spine with torsiometer when leg close stand (p<0.01) and leg close stand with GVS (p<0.01). The centre of gravity accelerated, there were reduced significantly difference X and Y axis of accelerometer during the closing of the leg without vision (p<0.05). There were reduced significantly difference X and Z axis of accelerometer during the closing of the leg with GVS (p<0.05). There were reduced significantly difference X and Z axis of accelerometer during the closing of the leg and close eyes with GVS (p<0.05). Conclusion : The balance ability, vestibular system and postural control is improved.

• 대한기계학회논문집A
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• 제34권4호
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• pp.431-437
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• 2010

본 연구의 목적은 편마비 환자와 같이 정상 보행이 아닌 경우의 보행 실험에서 힘측정판을 이용한 지면반발력의 측정이 매우 어려웠던 경험에서 출발하여 힘측정판을 사용하지 않고 운동학적 데이터만으로 보행 중 발생하는 지면반발력을 계산하는 것이다. 3차원 동작분석 시스템과 동기화된 힘측정판을 이용하여 보행실험을 실시하여 3차원 동작분석 시스템으로부터 보행의 운동학적 데이터를 추출하였고 이로부터 보행주기를 검출하였다. 인체를 13개의 체절로 모델링하고 각 체절의 거동이 추출한 운동학적 데이터를 따르도록 하였다. 각 체절의 질량과 질량 중심은 인체측정학의 자료를 이용하였다. 보행실험에서 측정한 지면반발력과 운동학적 데이터만을 이용한 계산 결과의 비교에서 크기가 가장 큰 수직방향은 잘 일치하였고 전후방향이나 횡방향도 유사한 경향을 보였다. 본 계산 결과는 보행에 관한 역동역학 해석의 기본 자료로 활용할 수 있다.

• Journal of Korean Neurosurgical Society
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• 제59권5호
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• pp.471-477
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• 2016

Objectives : The correction of clinical and radiologic abnormalities in patients with symptomatic ossification of the posterior longitudinal ligament (OPLL) is the current mainstay of treatment. This study aimed to identify radiographic predictors of severity of myelopathy in patients with symptomatic OPLL. Methods : Fifty patients with symptomatic cervical OPLL were enrolled. Based on Japanese Orthopedic Association (JOA) scores, patients were divided into either the mild myelopathy (n=31) or severe myelopathy (n=19) group. All subjects underwent preoperative plain cervical roentgenogram, computed tomography (CT), and MR imaging (MRI). Radiological parameters (C2-7 sagittal vertical axis, SVA; C2-7 Cobb angle; C2-7 range of motion, ROM; OPLL occupying ratio; and compression angle) were compared. Compression angle of OPLL was defined as the angle between the cranial and caudal surfaces of OPLL at the maximum level of cord compression Results : The occupying ratio of the spinal canal, C2-7 Cobb angle, C2-7 SVA, types of OPLL, and C2-7 ROM of the cervical spine were not statistically different between the two groups. However, the OPLL compression angle was significantly greater (p=0.003) in the severe myelopathy group than in the mild myelopathy group and was inversely correlated with JOA score (r=-0.533, p<0.01). Furthermore, multivariate regression analysis demonstrated that the compression angle (B=-0.069, p<0.001) was significantly associated with JOA scores (R=0.647, p<0.005). Conclusion : Higher compression angles of OPLL have deleterious effects on the spinal cord and decrease preoperative JOA scores.

• 대기
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• 제18권4호
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• pp.339-354
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• 2008

A numerical simulation of a heavy snowfall event that occurred 13 January 2008 along the Yeongdong coastal area, was performed using WRF (Weather Research and Forecasting) in order to reveal mesoscale structures and to construct a conceptual model showing the meteorological background that caused the large difference in snowfall amounts between the Yeongdong mountain area and the Yeongdong coastal area. The simulation results matched well with various observations such as corresponding 12h-accumulated observed precipitation, surface wind obscrvation, radar echoes, and satellite infrared images. The simulation and the observations showed that the scale of the event was of meso - $\beta$ and meso - $\gamma$ scale. The simulation represented well the mesoscale process causing the large difference in snowfall amounts in the two areas. First, wind flow was kept, to a certain extent, from crossing the mountains due to the blocking effect of the low Froude number (~1). The northeast flow over the adjaccnt sea tumcd northwest as it approachcd the mountains, where it was trapped, allowing so-called cold air damming. Second, a strong convergence area formed where the cold northwest flow along the Yeongdong coastal area and the relatively warm and moist northeast flow advecting toward the coast met, supporting the fonllation of a coastal front. Thus, the vertical motion was strongest over the front located near the coast, leading to the heavy snowfall there rather than in the remote mountain area.

• 환경영향평가
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• 제11권2호
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• pp.79-91
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• 2002

Four dimensional data assimilation (FDDA) technique was considered for 3 dimensional wind field in coastal area and a set of 3 numerical experiments including control experiments has been tested for the case of the synoptic weather pattern of the weak northerly geostrophic wind with the cloud amount of less than 5/10 in autumn. A three dimensional land and sea breeze model with the sea surface temperature (SST) of 290K was performed without nudging the observed wind field and surface temperature of AWS (Automatic Weather System) for the control experiment. The results of the control experiment showed that the horizontal temperature gradient across the coastline was weakly simulated so that the strength of the sea breeze in the model was much weaker than that of observed one. The experiment with only observed horizontal wind field showed that both the pattern of local change of wind direction and the times of starting and ending of the land-sea breeze were fairly well simulated. However, the horizontal wind speed and vertical motion in the convergence zone were weakly simulated. The experiment with nudgings of both the surface temperature and wind speed showed that both the pattern of local change of wind direction and the times of starting and ending of the land-sea breeze were fairly well simulated even though the ending time of the sea breeze was delayed due to oversimulated temperature gradient along the shoreline.

• 한국운동역학회지
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• 제19권3호
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• pp.519-528
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• 2009

상해 예방을 위해 이용하는 테이핑의 효과는 이미 선행연구들에서 이해할만하게 이야기 되어져 왔지만, 기능적 발목 불안정성을 가진 대상자에게 동적 임무를 가지고 지면반력과 안정성을 분석한 연구는 거의 없다. 본 연구는 발목 불안정성을 가진 선수들을 대상으로 점프 후 착지 시 지면반력 변인과 안정성에 미치는 영향을 알아보는데 있다. 이 실험을 위하여 기능적 발목 불안정성을 가진 14명의 선수가 참가하였고 동작분석과 지면반력 값을 산출하기 위해 적외선 카메라 8대(Vicon MX-F20, Oxford Metric Ltd, Oxford, UK)로 구성된 동작분석시스템(Vicon Motion Systems)과 지면반력기를 사용하였다. 본 연구 결과 발목 불안정성이 있는 선수에게 테이핑의 적용은 착지 시 배측굴곡 각속도, 내번 각속도, 최대 수직지면반력을 감소시켰으며, 안정성과 관련된 변인인 A-P cop, M-L cop에서 안정성을 향상시켰다. 임상에서 발목 불안정성이 있는 선수들에게 상해 예방을 위한 하나의 방법으로 테이핑의 사용을 권장해도 될 것으로 사료된다.

• 대한기계학회논문집A
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• 제36권4호
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• pp.429-435
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• 2012

압연공정 중에 작업롤은 스트립과의 지속적인 마찰에 의해 마모가 발생하여, 질량 불평형이 발생하게 된다. 이러한 작업롤의 질량 불평형을 고려한 압연기의 수학적 모델을 제안하였고, 이 모델은 실험에 의해 검증되었다. 작업롤은 편심을 가진 강체 로터로 가정되어, 질량 불평형의 채터 진동에 대한 영향을 분석하였다. 스핀들의 준평형 해석을 통해 계산된 조인트 힘은 압연기의 작업롤에 외력으로 작용시켰다. 압연기의 운동방정식을 직접적분법으로 풀어 과도 응답을 얻고 주파수 분석을 수행하였다. 편심은 수직 방향의 진동보다 수평 방향의 진동에 더 큰 영향을 끼쳤는데, 작업롤 반경의 1%의 편심거리도 수평 방향 채터 주파수의 진폭을 크게 상승시킬 수 있다는 것을 확인하였다.

• 대한기계학회논문집B
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• 제37권6호
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• pp.545-550
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• 2013

본 논문은 정전기력을 이용한 마찰력 변조를 이용하여 손끝을 통한 촉각정보의 입출력을 동시 구현하는 소자를 제안하였다. 기존의 촉각소자들이 촉각정보의 입력 및 출력을 개별적으로 구현한 것에 비해 본 연구는 손끝의 수직/수평 방향 동작 인식과 질감 구현을 동시에 구현하였다는 점에서 차별성을 가진다. 실험분석을 통해 검증한 손끝 동작 인식기능은 수직방향의 클릭의 경우 0.146nF/$40{\mu}m$, 수평방향의 경우 0.09nF/$750{\mu}m$의 정전용량 변화를 통해 인식 가능하였으며, 질감 구현의 경우 정전기적 인력을 통해 마찰력을 32~152mN의 범위에서 제어할 수 있음을 확인하였다. 교류전압을 이용한 수평적 진동은 60V, 3Hz에서 최대 128.1mN의 마찰력 변조를 구현하였으며, 이는 기존 연구 대비 32% 향상을 보여준다. 본 연구는 손끝에서 정보의 입출력을 동시 구현하여 정보기기의 촉각인터페이스에 적용 가능하다.

• 한국자동차공학회논문집
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• 제14권2호
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• pp.100-106
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• 2006

The behavior of spray impinging on the inclined constant temperature flat plate was experimentally investigated. To clarify the wall effect of a high pressure DISI injector, a relative angle of the inclined wall to a spray axis was varied. Spray penetration along the wall was observed optically and it was compared with that of a Fan spray type and Swirl type spray. To evaluate various spray motion quantitatively, a spray path penetration which describe the development of a spray tip along the wall was newly introduced. To observe the structure of an impinging spray, it was visualized by a controlled stroboscope light and its visualized image was captured on an CCD camera. Using the digital image of impinging spray $H_x$ and $R_x$ was extracted to clarify the structure of impinging spray. The main parameter of the relative position of the wall was the inclined angle which was defined as the angle was varied from $0^{\circ}$ (vertical impingement) to $60^{\circ}$ at the same condition.

• Journal of Biosystems Engineering
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• 제30권6호통권113호
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• pp.366-372
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• 2005

The objective of this study was to evaluate the bump crossing and loading stability of a proto-type mini-forwarder under development. The evaluation was performed by computer simulation using a multi-body dynamic analysis program, Recur- Dyn 5.21. The proto-type was modeled and its properties such as mass, mass center, and mass moment of inertia were determined using 3D CAD modeler, Solid Edge 8.0. The $\%$ errors of masses, mass center, mass moment of inertia, and vertical motion of the model were within less than $10\%$ and the model's behavior agreed relatively well with those of the proto-type when traversing over a rectangular bump. Using the validated model, bump crossing of the proto-type was simulated and the loading limit was determined. It was found that effects of the shapes of bump on the bump crossing performance was insignificant within the practical heights of bumps. Stability of bump crossing increased with loading. However, loading of longer logs than 2.7 m made the crossing unstable because the ends of logs contacted ground when traversing over the bump. The maximum loading capacity of the proto-type was estimated to be 7.8 kN of 2.7 m long logs.