• Title, Summary, Keyword: 인가힘

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A Study of Applied Pressure According to Knee variable During Lachman Test for Anterior Cruciate Ligament using Telos Device (Telos Device를 이용한 전방십자인대 Lachman 검사 시 무릎두께와 활성도에 따른 인가압력에 대한 고찰)

  • Lim, Jong-Cheon;Kim, Sang-Hyuk;Seo, Sang-Hyuk;Kim, Yon-Min
    • Journal of the Korean Society of Radiology
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    • v.13 no.3
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    • pp.391-398
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    • 2019
  • The purpose of study is to investigate the difference of the daN force applied during the examination using Telos Device and the degree of fluctuation of anterior cruciate ligament according to the individual differences of the muscles involved in knee stability. The examination was done by the Lachman test using Telos Device and the changes of anterior cruciate ligament were measured by varying the force of 0. 15, 30 daN on each right and left side and the force of 30 daN after the bruce protocol. Computed tomography (CT) was used to measure muscle mass. As a result of measuring the degree of fluctuation of the anterior cruciate ligament according to the change of the force applied to the Telos Device, there was a statistically significant difference in the knee fluctuation when 15 daN and 30 daN were applied on both right and left. Also, it is analyzed that the degree of fluctuation of anterior cruciate ligament varies according to the difference of individual's muscle mass. Therefore, it is considered that the force applied to the Telos Device should be changed according to the difference of individual's muscle mass.

Properties of Superconductor Thick Films by Applying Methods of Electric Fields (전계인가 방식에 따른 초전도 후막의 전기적 특성)

  • 소대화;조용준;전용우
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.691-694
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    • 2004
  • 물리적 힘에 의한 초전도 분말의 균일한 표면 확보 및 고밀도화 가 필요하다. 그러나 전기영동전착법의 특성상 물리적 힘에 의한 고밀도화에 어려움이 따르고 전착후막의 기공과 크랙현상을 발생시키는 단점으로 인하여 전기영동전착법에 의한 입자의 고밀도화를 위해서는 전착과정에서 현탁분말입자의 치밀성 및 일정한 방향성을 위한 공정기술이 요구된다. 전기영동법에 의한 초전도 후막의 특성을 향상시키기 위한 방법으로 DC전계인가 와 AC보조전계 인가방식에 공정이 있으며 이들 두 공정에 의해 제작된 후막의 특성을 비교 분석하고 두 공정기술에 따른 최적화 방안을 연구 하였다. YBCO 초전도 후막의 균일한 표면과 초전도특성 향상을 위한 공정개선방법으로는 수직방향 교류전계 인가 방식을 적용한 공정기술을 전기영동전착 공정에 적용하였다.

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Noise/Vibration Analysis of a Single-Phase SRM with Skewed Stator and Rotor (고정자와 회전자의 스큐에 따른 단상 SRM의 소음/진동 특성 분석)

  • Kim, Hyun-Chul;Yang, Hyong-Yeol;Lim, Young-Cheol;Chung, Dae-Won
    • Proceedings of the KIPE Conference
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    • pp.15-16
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    • 2010
  • 본 논문에서는 최소의 진동/소음을 가지는 SRM을 설계하기 위하여 고정자와 회전자의 Skew에 따른 단상 6/6 SRM의 소음/진동 특성을 비교, 분석하였다. SRM(Switched Reluctance Motor)에 발생하는 소음/진동의 주 원인은 모터 구동 시 Yoke 에 발생하는 방사방향 힘의 변화라고 할 수 있다. Yoke에 작용하는 힘은 돌극이 위치한 곳에 집중되므로 더욱 큰 진동을 유발하지만 회전자와 고정자에 동일한 Skew를 적용시키면 힘을 받는 Yoke의 면적은 늘어나게 되고, 따라서 방사방향의 힘을 요크 전체로 분산 시킬 수 있다. 이에 따라 스위치 온, 오프시 요크에 인가되는 방사방향의 힘의 최대치는 감소하게 되어 진동/소음이 현저히 줄어들게 된다. 본 논문에서는 최소의 진동/소음을 가지는 SRM을 설계하기 위하여 시뮬레이션을 통하여 회전자와 고정자의 스큐 각도에 따른 힘의 분포를 분석하였다. 시뮬레이션 결과를 바탕으로 하여 대표적인 특성을 가진 $0^{\circ}$, $18^{\circ}$의 SRM을 설계하여 소음/진동을 측정한 결과 제안한 방식이 소음/진동을 현저하게 감소시키는 효과를 가짐을 입증하였다.

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Design and Fabrication of a Mass-spring System for the Force-balance Servo Accelerometer (힘평형 서보 가속도계의 질량지지 장치 설계 및 제작)

  • Kim, Young-Dam;Go, Young-Jun;Nam, Hyo-Duk;Lee, Doo-Hee;Chang, Ho-Gyeong
    • The Journal of the Acoustical Society of Korea
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    • v.20 no.5
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    • pp.14-20
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    • 2001
  • The mass-spring system with four arms for the force-balance servo accelerometer was designed and fabricated. The response characteristics of a mass-spring system was calculated with the change of arms thickness and seismic mass by the finite element method (FEM). Furthermore, the response characteristics of accelerometer was measured using the change of interference pattern and response voltage value by Michelson interferometer. The response characteristics with changing length and thickness of arm was changed drastically, and changing seismic mass was minor effect for the response characteristics of mass-spring system. The measured resonant frequencies have good agreement with that of numerical analysis within 5% range.

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Effect of Pressing Force Applied to a Rotor on Revolution Characteristics in the Windmill Type Ultrasonic Motor (풍차형 초음파 전동기의 회전자에 인가된 힘이 회전특성에 미치는 영향)

  • 김영균;김진수
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.5
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    • pp.390-395
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    • 2000
  • The ultrasonic motor have recently begun to be used for certain unique practical utilizations in the fields of industrial medical consumer and automotive applications. Ultrasonic motor stimulated to ultrasonic oscillations by piezoelectrics to drive a rotor via friction contact. The metal and ceramic composite component was used as the stator element to generate ultrasonic vibrations. The ultrasonic motor used here was the windmill type ultrasonic motor operated by single-phase AC source. The windmill type ultrasonic motors has only three components; a stator element of two windmill shape slotted metal endcaps a rotor and a bearing. In this paper a prototype motor with 11.35 mm diameter was fabricated then relationship between the pressing force applied to a rotor and the rotation characteristic of windmill type ultrasonic motor are investigated when stator’s slots was changed from 4, 6, 8 and thickness changed from 0.15, 0.20 mm, respectively. Optimum pressing force applied to a rotor in the six stators was 1.2 mN.

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초음파 리니어액츄에이터 및 전동기

  • 장석명
    • 전기의세계
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    • v.39 no.9
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    • pp.27-34
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    • 1990
  • 초음파 구동장치는 기존 액츄에이터나 전동기의 우너리나 구조와는 전혀 다른 형태로, 여자전류를 흘리는 권선과 자성체로 이루어진 자기회로등의 기존 전동기에서의 필수 구성요소가 전혀 없이도 필요한 구동 토오크를 발생시키는 가장 구조가 간단한 형태이다. 즉, 압전재료에 교류전원을 인가하면 진동하는 성질을 이용하는 것으로 압전재료를 고정자로 하고 회전자 또는 이동자(리니어 액츄에이터의 경우)를 접촉시켜 놓고 고정자에 초음파 전원을 인가하면 상호간의 마찰에 의하여 힘을 받게 되어 회전자/이동자가 운동하게 되는 원리를 이용한 것이다.

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Torque Curve Shapes of Simple Uniaxial Magnetic Materials (단순 일축 비등방성 자성체의 돌림힘 곡선의 개형)

  • Hur, Jeen;Shin, Sung-Chul
    • Journal of the Korean Magnetics Society
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    • v.8 no.1
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    • pp.34-41
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    • 1998
  • We have theoretically investigated torque curve shapes of simple uniaxial magnetic materials by considering conditions for round peaks to exist. These conditions are functions of an applied field, anisotropy field, ans lowest critical field $h_0$ for a domain wall to move or nucleate. The peak having a height of 2h appears when h is lower than h$_1$, the peak having a height of 1 appears when h is higher than h$_2$, ans two peaks having heights of 1 and -1 appear when h is higher than h$_3$. It was found that torque curves of simple uniaxial magnetic materials could be classified into 8 distinct types depending on the existence of hysteresis, the number of the round peaks, and the reversal mechanisms. Simple uniaxial magnetic materials also found to be classifed into the 5 groups depending on $h_0$.

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학교사회복지 학생을 위한 맞춤 복지서비스인가?

  • Im, Seon-Suk
    • Social Workers
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    • no.2
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    • pp.36-39
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    • 2006
  • 학교사회복지 현장 실무자들에게 힘이 되는 격려의 메시지가 던져지기도 하고, 때로는 본의아니게 마음에 상처를 입게 되는 경우도 있다. 이러한 다양한 상황들을 접하면서 드는 생각은 학교사회복지의 발전이 ‘과연 누구를 위한 일인가‘라는 점이다. 또한 학생복지와 교육복지의 실현이라는 미명하에 사회복지사의 일자리 마련, 학교라는 공간에 대한 막연한 동경심, 새로운 분야에 대한 맹목적인 몰입 등과 같은 발상은 없었는지 자문과 반성을 해본다.

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Optimal design of a Linear Active Magnetic Bearing using Halbach magnet array for Magnetic levitation (자기부상용 Halbach 자석 배열을 이용한 선형 능동자기 베어링의 최적설계)

  • Lee, Hakjun;Ahn, Dahoon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.1
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    • pp.792-800
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    • 2021
  • This paper presents a new structure for a linear active magnetic bearing using a Halbach magnet array. The proposed magnetic bearing consisted of a Halbach magnet array, center magnet, and single coil. The proposed linear active magnetic bearing has a high dynamic force compared to the previous study. The high dynamic force could be obtained by varying the thickness of a horizontally magnetized magnet. The new structure of Halbach linear active magnetic bearing has a high dynamic force. Therefore, the proposed linear active magnetic bearing increased the bandwidth of the system. Magnetic modeling and optimal design of the new structure of the Halbach linear active magnetic bearing were performed. The optimal design was executed on the geometric parameters of the proposed linear active magnetic bearing using Sequential Quadratic Programming. The proposed linear active magnetic bearing had a static force of 45.06 N and a Lorentz force constant of 19.54 N/A, which is higher than previous research.

Design and Fabrication of Novel Linear Ultrasonic Motor (선형초음파 모터의 설계 및 제작)

  • 이동균;한득영;윤석진
    • Journal of the Korean Ceramic Society
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    • v.40 no.10
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    • pp.981-984
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    • 2003
  • A novel linear ultrasonic motor for precision position control was designed and fabricated. It was composed of two piezoelectric actuators with longitudinal ultrasonic fluctuations and shaking beam. When two AC electric fields (Usinwt, Ucoswt) were applied to piezoelectric actuators respectively, the middle part of shaking beam had an elliptical trajectory. According to experimental results, the generative force was proportional to pre-load force but the speed of slider was in inverse proportion. And the bar of shaking beam had a same trajectory with simulation result.