• International Journal of Automotive Technology
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• 제3권3호
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• pp.117-122
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• 2002

Joint stiffness can affect the vibration characteristics of car body structures. Therefore, it should be included in vehicle system model. In this paper, a numerical approximation of joint stiffness is presented considering joint flexibility of thin walled beam-jointed structures. Using the proposed method, it is possible to optimize joint structures considering the change of section shapes in vehicle structures. The numerical approximation of joint stiffness is derived using the response surface method in terms of beam section properties. The study shows that joint stiffnesses can be effectively determined in designing vehicle structures.

• 터널과지하공간
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• 제4권1호
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• pp.1-16
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• 1994

The study on the flow characteristics and analysis of groundwater in discontinuous rock mass is very important, since the water inflow into the underground opening during excavation induces serious stability and environmental problems. To investigate the flow through single rock joint, the effect of various aperture distribution on the groundwater flow has been analyzed. Observed through the analysis is the "channel flow", the phenomenon that the flow is dominant along the path of large aperture for given joint. The equivalent hydraulic conductivity is estimated and verified through the application of the joint network analysis for 100 joint maps generated statistically. Both the analytic aproach based on isotropic continuum premise and the joint network analysis are tested and compared analyzing the gorundwater inflow for underground openings of different sizes and varying joint density. The joint network analysis is considered better to reflect the geometric properties of joint distribution in analyzing the groundwater flow.ater flow.

• 한국자동차공학회논문집
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• 제9권3호
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• pp.155-163
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• 2001

Joint stiffnesses can affect the vibrational characteristics of car body structures and, therefore, should be included in vehicle system models. In this paper, a numerical approximation of joint stiffness is presented for considering joint flexibility of thin walled beam jointed structures. Using the proposed method, it is possible to optimize joint structures considering the change of section shapes in vehicle structures. The numerical approximation of joint stiffnesses is derived using the RSM(Response Surface Method) in terms of beam section properties. The study shows that joint stiffnesses can be effectively determined in designing vehicle structure.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.499-502
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• 2003

The purpose of this study is to understand the sliding characteristics of the infilling-joint surface using the new devised shear test apparatus with changeable slope for the original infilling materials and the infilling materials experienced cyclic freezing-thawing processes. Three types of the mother rock classified as the igneous rock, the metamorphic rock and the sedimentary rock and the infilling materials were collected for laboratory test. The cohesion according to the slope change of the rock joint shows large variation within ${\pm}$5 degrees but the internal friction angle shows appears the linear decreasing tendency. It is confirmed that the affecting factor of slope change of rock joint at the behavior of rock mass is larger than that of the infilling thickness. Test results show that the cohesion and the internal friction angle in 100 times of cyclic freezing-thawing processes are decreased about 50 percent compared with original one. A further study using various infillings materials would lead to a better understanding of the failure mechanism of rock mass by slope change of rock joint.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 추계 기술심포지움
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• pp.67-73
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• 2001

To investigate the relationships of solder joint characteristics with solder composition and A:V ratio (solder volume per pad area), Sn-37Pb and Sn-4.0Ag-0.5Cu solder balls with 330, 400, 450 and $457{\mu}{\textrm}{m}$ size were reflowed on same substrate. Sn-37Pb and Sn-4.0Ag-0.5Cu was reflowed at $220^{\circ}C$ and $240^{\circ}C$ respectively by IR-type soldering machine. As a result of reflowed solder- ball diameter(D) and height(H) measurement, D/H was decreased with solder ball size increment in range of 330~450 ${\mu}{\textrm}{m}$. But, D/H was increased in the solder joint for 457 ${\mu}{\textrm}{m}$ size, it was caused possibly by decrement of solder ball height increment compared with solder volume increment. As a result of shear and pull test, joint strength with A:V ratio was high. Joint strength of Sn-4.0Ag-0.5Cu was higher than Sn-37Pb. However, Sn-37Pb had more stable solder joint of small standard deviation. A thick and clean scallop type Ni-Cu-Sn intermetallic compound layer was formed in high A:V ratio and Sn-4.0Ag-0.5Cu solder joint interface.

• 한국정밀공학회지
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• 제25권10호
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• pp.130-136
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• 2008

The purpose of this study was to investigate chaotic characteristics of major joint motions during treadmill walking. Gait experiments were carried out for 20 healthy young women. The subjects were asked to walk on a treadmill at their own natural speeds. The chaos analysis was used to quantify nonlinear motions of eleven major joints of each woman. The joints analyzed included the neck and the right and left shoulders, elbows, hips, knees and ankles. The recorded gait patterns were digitized and then coordinated by motion analysis software. Lyapunov exponent for every joint was calculated to evaluate joint characteristics from a state space created by time series and its embedding dimension. This study shows that differences in joint motion were statistically significant.

• 한국강구조학회 논문집
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• 제22권5호
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• pp.455-463
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• 2010

본 연구는 철근콘크리트 구조와 강판 콘크리트 구조가 혼합되어 이질접합부가 있는 보형 구조물의 역학적 특성을 평가하기 위하여 수행하였다. 강판콘크리트 구조는 현재 국내와 일본, 미국 등에서 연구가 진행되고 있고, 대규모 산업설비에서 철근콘크리트 구조의 대안으로 실험연구가 수행되고 있다. 본 연구에서는 대규모 철근콘크리트 구조물에 강판 콘크리트 구조를 적용할 경우를 가정하여 보 형태의 구조물에 강판 콘크리트 구조와 철근 콘크리트 구조를 적용하여 이질접합부를 만들고, 면외하중을 파괴 시까지 가력하여 이질접합부를 가진 보형실험체의 휨 내력 및 구조특성을 평가하기 위하여 실험연구를 수행하였다.

• 생명과학회지
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• 제20권11호
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• pp.1704-1710
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• 2010

본 연구는 뇌졸중 발병 후 재활운동에 참가하는 환자들을 대상으로 재활운동 3개월이 지난 시점에서 1차 실험을 하였고, 6개월이 지난 시점에서 2차 실험을 하여 운동역학적 비교분석을 하였다. 실험에 사용된 장비는 영상분석기, 족저압분석기, 근전도분석기를 사용하였다. 대상자는 7명으로 하였으며 통계방법은 t-test분석 이용하였다. 결과는 엉덩관절의 최대신전 피크 값과 최대신전 피크 모멘트 값에서 통계적으로 유의한 차이를 나타내었다(p<0.05). 족저압의 비교에서는 환측 다리의 족저압에서 일반적인 걷기 동작시에 족저압의 중심이동거리에서 통계적으로 유의한 차이를 나타내었다(p<0.05). 근전도 분석에서는 대퇴사두근 중의 대퇴직근과 외측광근의 근력에서 통계적으로 유의한 차이를 나타내었다(p<0.05).

• 한국정보전자통신기술학회논문지
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• 제8권1호
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• pp.65-69
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• 2015

작업치료에서 관절의 가동성은 치료 절차와 기간에 영향을 미치는 중요한 요소이다. 수동적 스트레칭과 능동적 스트레칭을 병행하는 고유수용성 신경근 촉진법이 고관절의 가동성에 미치는 영향과 주요 굽힘/폄근의 근전도 활성정도 바탕으로 고유수용성 신경근 촉진 스트레칭의 생체역학적 특징을 고찰하였다. 10명의 20대 학생을 대상으로 고유수용성 신경근 촉진 스트레칭을 실시한 결과 고관절의 가동성이 전담 보조자의 도움을 받았을 때, 평균 $18.9^{\circ}$ 증가하였고 넙다리네갈래근과 뒤넙다리근의 근전도의 활성 또한 고유수용기의 생체역학적 특징을 나타내었다.

• The Journal of Korean Physical Therapy
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• 제34권5호
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• pp.242-247
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• 2022

Purpose: This study investigates the effect of 60° semi-squat exercises according to three different types of support surfaces. The effects were examined on joint position sense and balancing ability using stable and unstable surfaces in patients afflicted with post-stroke hemiplegia. Methods: Subjects were instructed to perform three sets of 60° semi-squat exercises according to the characteristics of the support surface conditions. The three ground states were bilateral stable surface (BSS), nonaffected side unstable surface (NUS), and bilateral unstable surface (BUS). The joint position sense, characteristics of body sway, and dynamic balance were analyzed according to floor conditions before and after the experiment. A balance-pad (50 cm W×41 cm L×6 cm H; Alcan Airex AG, Sins, Switzerland) was used for the unstable floor. Results: The 60° semi-squat exercises applied to hemiplegic patients showed the highest statistical significance in joint position sense in the NUS group, and Timed Up and Go test (TUG) in the BUS group (p<0.05). Conclusion: Functional training using an unstable surface can be applied as a meaningful intervention method for improving the balance and joint position sense of stroke patients.