• 대한조선학회지
• /
• 제21권3호
• /
• pp.19-26
• /
• 1984

Guilloton's wedge method is extended to evaluated velocity components on and around a ship hull. A ship is divided into a number of layers each of which is approximated by the superposition of so many wedges. These wedges start from the stations evenly placed along the length of the ship. The Michell potential is used to obtain the field generating properties of a wedge. The derivatives of this potential represent then the velocity components induced by the wedge. Superposition of velocities induced at a fixed field point by all the wedges placed at the appropriate positions to approximate the hull will result in the velocity associated with the ship at a particular speed.

• 한국해양공학회지
• /
• 제28권3호
• /
• pp.209-217
• /
• 2014

In the present study, the water impact loads on two-dimensional symmetric and asymmetric wedges were mainly studied. The impact pressure and force were measured during a vertical drop of the symmetric and asymmetric wedges. The measured pressure was compared with analytic solutions. The measured force at a local area of the wedge was compared with the integrated pressures and analytic solutions. Some findings on symmetric and asymmetrical wedge drops are presented, and the reliability of the force sensor used for the measurement of the local impact force is discussed.

• 한국의학물리학회지:의학물리
• /
• 제15권4호
• /
• pp.237-246
• /
• 2004

국제방사선량 및 측정위원회(ICRU)가 쐐기인수를 정의하고 있지만 방사선치료계획장치는 쐐기에 관한 다른 개념을 도입하여 선량을 보정하기도 한다. 개념이 다른 인수들은 아주 다르게 정의되어 있기 때문에 그 값도 용납될 수 없을 정도로 다를 수 있어서 심각한 선량오차가 발생될 수 있다. 설치된 방사선치료기(Cinac 21EX, Varian, 미국)에는 물질쐐기(위와 아래)와 위턱에 의한 쐐기 기능이 있고 방사선치료계획장치(RTPS)로 Eclipse(Varian, 미국)와 Pinnacle$^{3}$(ADAC, 미국)가 사용되고 있다. 물질쐐기와 기능상쐐기의 쐐기인수, 쐐기상대출력인수 및 쐐기출력인수를 물팬톰에서 이온함으로 측정하여 조사면크기와 쐐기위치, 쐐기각, X선 투과력, 측정조건에 따라 분석하고 비교하였다. 기능상쐐기가 물질쐐기에 비해 여러 가지 요인에 크게 영향을 받으며, 기능상쐐기의 쐐기인수 등에 영향을 미치는 주된 요인은 조사면크기와 쐐기각 이었다. X선 투과력도 쐐기인수 등에 약간의 영향을 미쳤다. 쐐기에 관련된 상이한 개념의 인수는 그 값이 6 MV는 63%, 15 MV는 59% 이상 다를 수 있기 때문에 선량오차를 줄이기 위해 방사선치료계획장치에 활용되는 인수를 파악하고 RTPS에 합당한 값을 입력해야 한다.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2003년도 춘계학술대회
• /
• pp.157-162
• /
• 2003

Singular stress fields around three-dimensional wedges are examined, and the near-tip intensity is calculated via the two-state M-integral with the aid of the domain integral representation. A numerical example demonstrates the effectiveness and accuracy of the present scheme for computing the stress intensities of singular stresses near the generic three-dimensional wedges.

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

• 한국방재학회 논문집
• /
• 제6권2호
• /
• pp.17-24
• /
• 2006

본 연구에서는 각종 토구조물의 붕괴 안정성 확보를 위하여 사용중인, 기존의 어스앵커공법의 문제점인 초기 인장시 쐐기의 Slip을 최소화하기 위하여, 간격유지구와 쐐기삽입장치(스프링)를 연구개발하였다. 간격유지장치를 이용한 어스앵커에 대한 실내시험을 통하여 PS강연선에 손상이 발생하지 않는 스프링의 상세(길이 60mm, 직경 6mm)를 도출하였으며, 본 장치는 쐐기 및 PS강연선의 상태를 육안으로 관측할 수 있으며 쐐기의 Slip을 최소화하여 인장효율을 높일 수 있는 장점이 있으며 현장적용결과도 우수한 결과를 얻었다. 또한 본 장치는 재인장 작업시 쐐기를 제거 및 교체가 가능하여 효율성을 높일 수 있었다.

• Journal of Electrical Engineering and Technology
• /
• 제12권6호
• /
• pp.2411-2418
• /
• 2017

This study focuses on the effects of using open stator slots in an interior permanent magnet traction motor with a magnetic slot wedge design in order to increase the power density at its base speed. In addition, such a configuration reduces the torque ripple under field-weakening conditions. Five different wedge models were selected, each of which was evaluated using a finite element analysis (FEA). Based on the initial model, we designed magnetic slot wedges for maximum back-EMF and minimum cogging torque. In addition, the d-q axis inductance was slightly altered due to the magnetic slot wedges. Finally, we analyzed the performance of a traction machine under field weakening control. Moreover, we have outlined the requirements for an ideal magnetic slot wedge design.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제10권4호
• /
• pp.520-528
• /
• 2018

This paper presents the results of experimental investigation on the elastic-plastic response of steel unstiffened wedges with dead-rise $10^{\circ}$ subjected to repeated impulsive pressure loadings. Repeated drop tests were performed with both wedge thickness and drop height varied. The pressure and histories were recorded during the tests and the permanent deflections were measured after every drop. Using the recorded test result, the effects of flexibility of wedges and repetition have been investigated. From the pressure history obtained from the tests the characteristics of the impulses were identified. Numerical simulations of the tests were made using the measured pressure history and the permanent deflection predictions were compared with those of the experiments.

• 대한기계학회논문집B
• /
• 제23권8호
• /
• pp.969-977
• /
• 1999

A similarity solution of a steady laminar flow of micropolar fluids past wedges has been studied. The similarity variables found by Falkner and Skan are employed to reduce the streamwise-dependence in the coupled nonlinear boundary layer equations. Numerical solutions of the equations are then obtained using the fourth-order Runge-Kutta method and the distribution of velocity, micro-rotation, shear and couple stress across the boundary layer are obtained. These results are compared with the corresponding flow problems for Newtonian fluid past wedges with various wedge angles. Numerical results show that, keeping ${\beta}$ constant, the skin friction coefficient is lower for a micropolar fluid, as compared to a Newtonian fluid. For the case of constant material parameter K, however, the velocity distribution for a micropolar fluid is higher than that of a Newtonian fluid.

• International Journal of Contents
• /
• 제5권2호
• /
• pp.26-31
• /
• 2009

This paper describes a new image watermarking scheme invariant to rotation, scaling and translation (RST) attacks. For obtaining the invariance properties we propose to present an image of watermark by wedges and rings to convert its rotation to shift and then utilize the shift invariance property of the Direct Fourier Transform (DFT). But in contrast to conversional schemes based on the Fourier-Mellin transform (FMT), we do not use a log-polar mapping (LPM). As a result, our scheme preserves high quality of original image since it is not underwent to LPM For withstanding against JPEG compression, noise addition and low-pass (LP) filtering attacks a low frequency watermark is embedded into middle frequencies of the original image. Experiments with various attacks show the robustness of the proposed scheme.