• Tribology and Lubricants
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• 제17권5호
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• pp.365-372
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• 2001

This paper has been presented the hydrodynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from existed investigations in the side of pressure distribution of air film because of the high speed of journal and the wedge effects by the eccentricity. These optimal chooses of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high speed spindle. In this paper, The pressure behavior in theory of air film according to the eccentricity of journal and the source positions analyzed. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high speed milling.

• KSTLE International Journal
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• 제4권2호
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• pp.66-72
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• 2003

This paper presents the hydrodynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from existing investigations in the side of pressure distribution of air film because of the high speed of journal and the wedge effects by the eccentricity. These optimal choices of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high-speed spindle. In this paper, The pressure behavior in theory of air film in high speed region of journal according to the eccentricity of journal and the source positions analyzed. The theoretical analysis has been identified by experiments. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high-speed milling.

• Tribology and Lubricants
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• 제17권6호
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• pp.476-481
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• 2001

This paper has been presented the hydrodynamic effect by the journal speed, eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from existed investigations in the side of pressure distribution of air film because of the high speed of journal and the wedge effects by the eccentricity. These optimal chooses of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high speed spindle. In this paper, The pressure behavior in theory of air film according to the eccentricity of journal and the source positions analyzed. The theoretical analysis have been identified by experiments. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high speed milling.

• 대한정형도수물리치료학회지
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• 제12권1호
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• pp.44-50
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• 2006

The purpose of this study is to assess the radiographic effects of normal person with contact laterally wedged insoles with strapping of varying elevations. Eight person who were randomized into group according to their birth dates and wedge elevation, participants wore contact laterally wedged insoles with strapping with elevation of 9, 15, 21mm. Standing radiographs were used to analyze the femorotibial angle for each subject, The result of repeated measures ANOVA's reveled that laterally wedged insoles with strapping of varying elevations produced significantly the femorotibial angle. The degree of change in femorotibial angle with the insole with strapping was effected by the tilt of the lateral wedge(P<0.05). We suggest that these results may be beneficial for manufacturing foot orthotic devices, such as wedged insoles, to control medial and later compartment forces in the knee varus-valgus deformity.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2001년도 제33회 춘계학술대회 개최
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• pp.231-235
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• 2001

This paper has been presented the dynamic effect by the journal speed. eccentricity and source positions in order to overcome the defects of air bearing such as low stiffness and damping coefficient. Choosing the two row source position of air bearing is different from previous investigations in the side of pressure distribution of air film by the wedge effects. These optimal chooses of the two row source positions enable us to improve the performance of the film reaction force and loading force as making the high speed spindle. The results of investigated characteristics may be applied to precision devices like ultra-precision grinding machine and ultra high speed milling.

• Journal of applied mathematics & informatics
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• 제25권1_2호
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• pp.67-83
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• 2007

The characteristics of steady two-dimensional laminar boundary layer flow of a viscous and incompressible fluid past a moving wedge with suction or injection are theoretically investigated. The transformed boundary layer equations are solved numerically using an implicit finite-difference scheme known as the Keller-box method. The effects of Falkner-Skan power-law parameter (m), suction/injection parameter ($f_0$) and the ratio of free stream velocity to boundary velocity parameter (${\lambda}$) are discussed in detail. The numerical results for velocity distribution and skin friction coefficient are given for several values of these parameters. Comparisons with the existing results obtained by other researchers under certain conditions are made. The critical values of $f_0$, m and ${\lambda}$ are obtained numerically and their significance on the skin friction and velocity profiles is discussed. The numerical evidence would seem to indicate the onset of reverse flow as it has been found by Riley and Weidman in 1989 for the Falkner-Skan equation for flow past an impermeable stretching boundary.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.651-658
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• 2004

In this study, we introduced the spiral pipe nailing system (refer as SPN system) with self drilling method, can apply to ground which is hard to keep shape of bore hole, and performed limit equilibrium analysis with simplilied trial wedge method while length ratio and bond ratio were altered to evaluate slope stability considered of tensile strength and bending stiffness. A newly soil nailing system named as the SPN system is respected to reduce displacement of nail and increase global slope stability. And effects of various factors related to the design of the SPN system, such as the type of drilling method and the bit, are examined throughout a series of the displacement-controlled field pull-out tests. 6 displacement-controlled field pull-out tests are performed in the present study and the volume of grouting arc also evaluated based on the measurements. In addition, short-term characteristics of pull-out deformations of the newly proposed SPN system are analyzed and compared with those of the general soil nailing system by carrying out the displacement-controlled field pull-out tests.

• Computers and Concrete
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• 제19권2호
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• pp.211-216
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• 2017

Crack on concrete surface allows more rapid penetration of chlorides. Crack width and depth are dominant parameters for chloride behavior, however their effects on chloride penetration are difficult to quantify. In the present work, the previous anisotropic (1-D) model on chloride diffusion in concrete with single crack is improved considering crack shape and roughness. In the previous model, parallel-piped shape was adopted for crack shape in steady-state condition. The previous model with single crack is improved considering wedge shape of crack profile and roughness. For verifying the proposed model, concrete samples for nuclear power plant are prepared and various crack widths are induced 0.0 to 1.2 mm. The chloride diffusion coefficients in steady-state condition are evaluated and compared with simulation results. The proposed model which can handle crack shape and roughness factor is evaluated to decrease chloride diffusion and can provide more reasonable results due to reduced area of crack profile. The roughness effect on diffusion is evaluated to be 10-20% of reduction in chloride diffusion.

• 자원환경지질
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• 제55권6호
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• pp.727-736
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• 2022

얼음쐐기는 영구동토 지역의 토양층에서 관찰되는 얼음체로, 형성 당시의 강수 및 토양이 유입되어 형성되며, 높은 농도의 용질 및 고체함량을 가진다. 이러한 얼음쐐기는 그 형성 및 분포적 특성으로 인해 최근 고기후 및 고환경 복원을 위한 연구에 활용될 수 있는 가능성이 제시되고, 이에 대한 연구가 제한적으로 시작되고 있다. 하지만 얼음쐐기에 포함된 용질 및 고체 혹은 광물입자들을 고기후 및 고환경 복원 프록시로 사용하기 위해서는 이들의 물리화학적 특성 보존이 필수적이다. 만약 얼음쐐기 시료의 해동과정에 의한 물리화학적 특성 변화가 야기된다면, 이를 활용한 고기후 및 고환경 해석에 오류를 야기할 수 있다. 본 연구에서는 동시베리아 쑤야(Cyuie) 지역에서 채취된 얼음쐐기를 이용하여 해동조건이 얼음쐐기 내 용질 및 고체상에 미치는 영향을 조사하였다. 쑤야(Cyuie) 지역의 얼음쐐기 시료에 대해 해동온도와 산소유무를 고려하여 네 가지 해동조건(4℃-유산소, 4℃-무산소, 23℃-유산소 혹은 23℃-무산소)에서 회수된 용액 및 고체시료의 특성을 분석하였다. 온도와 산소의 영향이 가장 제한적일 것으로 예상되는 4℃-무산소 조건에서 측정된 결과를 기준으로 비교한 결과, 얼음쐐기 내 고체입자들에 대한 해동조건의 영향은 미미하였다. 반면, 용액의 화학적 특성(pH, 전기전도도, 알칼리도와 주양이온 및 미량원소의 농도)은 기준조건에 비해 4℃-유산소 조건에서 일관성 있게 유의미한 차이를 보였다. 본 연구결과, 얼음쐐기 시료의 해동조건에 따라 시료의 화학적 특성에 변화를 야기할 수 있으며, 이는 시료처리 방법 및 절차가 얼음쐐기를 이용한 고기후 및 고환경 복원 결과에 중요한 영향을 미칠 수 있음을 시사한다.

• 한국전문물리치료학회지
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• 제18권2호
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• pp.60-66
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• 2011

Foot posture is important in the development of the musculoskeletal structure in the lower limbs because it can change the mechanical alignment. Although foot orthotics are widely used for the correction of malalignments in the lower extremities, the biomechanical effects of wedges have not yet been cleared. The aim of this study was to investigate whether medial wedges affect the electromyographic (EMG) activity of the knee and hip joints in healthy adults that are performing one leg standing. Seventeen healthy volunteers performed the one leg standing under two foot conditions: A level surface, and a $15^{\circ}$ medial wedge. The subjects' EMG data for the gluteus maximus (Gmax), gluteus medius (Gmed), tensor fasciae latae (TFL), biceps femoris (BF), vastus lateralis (VL), and vastus medialis oblique (VMO) were recorded, along with the surface EMG, and all were analyzed. The EMG activity of the Gmed and TFL had significantly decreased under the medial wedge condition during one leg standing. Further study is needed in order to investigate whether medial wedges influence the EMG activity and kinematic data of the knee and hip joints as well as the ankle joints in adults with flexible flatfoot, while they are performing one leg standing.