• Title/Summary/Keyword: 굴곡 효과

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Evaluation of mechanical properties and non-flammability of Nylon6 using melamine-based halogen-free flame retardant (Melamine계 난연제를 이용한 Nylon6의 난연성 및 물리적 특성 평가)

  • Kim Dong-Hak;Ryu Kwan-Suk;Son Young-Gon
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.7 no.4
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    • pp.743-748
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    • 2006
  • We investigated the flame retardancy and the mechanical properties of Nylon6 by using melamine-based halogen-free flame retardants(melamine cyanurate:MC-100 and melamine phosphate:MP-100). We chose the UL-94 method for flame retardancy and measured the tensile strength, flexural strength, flexural modulus by using UTM and impact strength by using Izod impact tester. We also tested the effect of nano-clay on flammability and mechanical properties. We obtained the V0 grade when the concentration of flame retardant was over 5 wt%. The tensile strength and flexural strength decreased and flexural modulus increased with the concentration of both flame retardant systems. The results showed that MC-100 system was better than MPP-100 system. Because of poor dispersion, we did not obtain the synergistic effect of nano-clay.

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Effects of heat treatment on the load-deflection properties of nickel-titanium wire (니켈-티타늄 와이어의 열처리에 따른 부하-변위 특성 변화)

  • Chang, Soo-Ho;Kim, Kwang-Won;Lim, Sung-Hoon
    • The korean journal of orthodontics
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    • v.36 no.5
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    • pp.349-359
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    • 2006
  • Objective: Nickel-titanium alloy wire possesses excellent spring-back properties, shape memory and super-elasticity. In order to adapt this wire to clinical use, it is necessary to bend as well as to control its super-elastic force. The purpose of this study is to evaluate the effects of heat treatment on the load-deflection properties and transitional temperature range (TTR) of nickel-titanium wires. Methods: Nickel-titanium wires of different diameters ($0.016"\;{\times}\;0.022"$, $0.018"\;{\times}\;0.025"$ and $0.0215"\;{\times}\;0.028"$) were used. The samples were divided into 4 groups as follows: group 4, posterior segment of archwire (24 mm) without heat treatment; group 2, posterior segment of archwire (24 mm) with heat treatment only; group 3, anterior segment with bending and heat treatment; group 4, anterior segment with bending and 1 sec over heat treatment. Three point bending test was used to evaluate the change in load-deflection curve and obtained DSC (different scanning calorimetry) to check changes in $A_f$ temperature. Results: In the three point bending test, nickel-titanium wires with heat treatment only had higher load-deflection curve and loading and unloading plateau than nickel-titanium wires without heat treatment. Nickel-titanium wires with heat treatment had lower Af temperature than nickel-titanium wires without heat treatment. Nickel-titanium wires with heat treatment and bending had higher load-deflection curve than nickel- titanium wires with heat treatment and nickel-titanium wires without heat treatment. Nickel-titanium with heat treatment of over 1 sec and bending had the highest load-deflection curve. Nickel-titanium wires with heat treatment and bending had lower Af temperature, Nickel-titanium wires with heat treatment of over Af sec and bending had the lowest Af temperature. Conclusion: From the results of this study, it can be stated that heat treatment for bending of Nickel-titanium wires does not deprive the superelastic property but can cause increased force magnitude due to a higher load-deflection curve.

Effect of Ankle Taping and Brief Exercise on Lower Extremity Kinematics of Healthy Adults During Vertical Drop Landing (수직착지시 발목관절의 운동형상학적(kinematic) 분석)

  • Yi, Chung-Hwi;Park, So-Yeon;Kwon, Hyuk-Cheol
    • Physical Therapy Korea
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    • v.9 no.4
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    • pp.37-44
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    • 2002
  • 이 연구의 목적은 발목에 테이핑을 한 후 40 cm의 높이에서 한 발로 수직착지를 할 때 발목관절에서의 테이핑 효과를 분석하는 것이었다. 대상자는 20대의 건강한 성인 14명(남자 4명, 여자 10명) 이었다. 대상자에게 적용한 조건은 테이핑 전, 테이핑 적용, 30분 동안 트레드밀에서 걷기, 테이핑 제거상태 이었고 맥리플렉스(MacReflex)를 이용하여 발끝이 지면에 닿은 상태에서 발목이 최대 배측굴곡(dorsiflexion) 되기까지 걸린 시간, 발목관절 각도변화, 각속도를 측정한 후 반복측정에 의한 분산분석으로 비교하였다. 그 결과 네 개의 조건간에는 통계학적으로 유의한 차이가 없었다(p>.05). 따라서 발목 테이핑은 수직착지시 발목의 배측굴곡을 제한하는 효과는 없다고 판단된다.

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The Impingement of The Posterior Elbow in The Heavy Workers (중노동자에서 발생된 주관절 후방부의 충돌 병변)

  • Moon, Young-Lae;Lee, Chul-Gap;Kim, Dong-Hui;Lee, Young-Kwan
    • Journal of the Korean Arthroscopy Society
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    • v.9 no.1
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    • pp.60-64
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    • 2005
  • Purpose: To describe the impingement of the osteophyte between the olecranon process and olecranon fossa and to understand the effect of removing the lesion on the elbow extension in heavy workers. Materials and Methods: Arthroscopy was performed to elbow of heavy industrial workers who complained painful limitation of elbow extension.6 patients(Teases) with average age of 43 year were selected. The average ROM showed flexion contracture of $17^{\circ}$ and further flexion of $87^{\circ}$. Results: In all cases, after the operation two months follow up, mean flexion contracture improved from $17^{\circ}\;to\;2^{\circ}$ with further flexion from$87^{\circ}\;to\;122^{\circ}$. After the operation 1 year follow up, the mean flexion contracture was $3^{\circ}$ and further flexion was $113^{\circ}$. Pain relief within acquired range of motion was achieved in all cases and there was no complication in this series. Conclusion: Selective removal of the impingement bony spur for treatment of flexion contracture in the patient with chronic cumulative trauma disorder patients appear to be effective method to control pain, recover joint movement and at] ow early rehabilitation.

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Influence of Detailed Structure and Curvature of Woven Fabric on the Luminescence Effect of Wearable Optical Fiber Fabric (직물의 세부 구조 및 굴곡이 웨어러블 광섬유의 발광 효과에 미치는 영향)

  • Yang, Jin-Hee;Cho, Hyun-Seung;Kwak, Hwy-Kuen;Oh, Yun-Jung;Lee, Joo-Hyeon
    • Science of Emotion and Sensibility
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    • v.21 no.4
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    • pp.55-62
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    • 2018
  • The two main requirements of wearable optical fiber fabrics are that they must presuppose a high degree of flexibility and they must maintain the luminance effect in both flat and bent conformations. Therefore, woven optical fiber fabrics that satisfy the above conditions were developed by both weaving and by using computer embroidery. First, we measured the brightness of the wearable optical fiber fabric in the flat state at a total of 10 measurement points at intervals of 1 cm. Second, the wearable optical fiber fabric was placed horizontally on the forearm, where three-dimensional bending occurs, and the luminance values were recorded at the same 10 measurement points. For the woven fabric in the flat state, the maximum, minimum, average, and standard deviation luminance values were $5.23cd/m^2$, $2.74cd/m^2$, $3.56cd/m^2$, and $1.11cd/m^2$, respectively. The corresponding luminance values from the bent forearm were $7.92cd/m^2$ (maximum), $2.37cd/m^2$ (minimum), $4.42cd/m^2$ (average), and $2.16cd/m^2$ (standard deviation). In the case of the computer-embroidered fabric, the maximum, minimum, average, and standard deviation luminance values in the flat state were $7.56cd/m^2$, $3.84cd/m^2$, $5.13cd/m^2$, and $1.04cd/m^2$, respectively, and in the bent forearm state were $9.6cd/m^2$, $3.63cd/m^2$, $6.13cd/m^2$, and $2.26cd/m^2$, respectively. Therefore, the computer-embroidered fabric exhibited a higher luminous effect than the woven fabric because the detailed structure reduced light-loss due to the backside fabric. In both types of wearable optical fiber fabric the luminance at the forearm was 124% and 119%, respectively, and the light emitting effect of the optical fiber fabric was maintained even when bent by the human body. This is consistent with the principle of Huygens, which defines the wave theory of light, and also the Huygens-Fresnel-Kirchhoff principle, which states that the intensity of light increases according to the magnitude of the angle of propagation of the light wavefront (${\theta}$).

A Semiconductor Defect Inspection Using Fuzzy Reasoning Method (퍼지 추론 기법을 이용한 반도체 불량 검사)

  • Kim, Kwang-Baek
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.14 no.7
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    • pp.1551-1556
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    • 2010
  • In this paper, we propose a new inspection method that applies fuzzy reasoning method considering the difference of brightness and intensity of illumination by bend together. In the preprocessing phase, we compensate the degree of semiconductor images with bilinear interpolation and moment-rotation. Then we use fuzzy reasoning method with the difference of brightness from error region by pattern matching and the difference of intensity of illumination from bends. Then the result is difuzzified and applied to the final inspection process. In experiment which uses 30 real world semiconductors with strait shots and side shots, the proposed method successfully discard the false positive identified by conventional brightness comparison only method without any loss of misidentification.

Mechanical Properties of Talc-Filled Polypropylene : Coupling Agent Effect (Talc로 충전된 폴리프로필렌의 기계적 물성 : 커플링제 효과)

  • 김주성;최미애;박태욱;김덕준
    • Polymer(Korea)
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    • v.24 no.6
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    • pp.770-776
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    • 2000
  • The effect of unreactive coupling agent on mechanical and thermal properties of talc-filled polypropylene (PP) composites was studied. Stearic and oleic acids were introduced as coupling agents, and tensile, flexural, and impact strength, thermal stability and melting transition temperature were measured and analyzed according to the types and concentration of coupling agents. Tensile and flexural strength were enhanced by introduction of coupling agent and the maximum effect was observed at the concentration of 3 wt% of coupling agent. Tensile and flexural strength of PP treated with oleic acid were higher than those of PP treated with stearic acid. but impact strength vice-versa. The reasons for these results were postulated by analyzing morphologies of talc-filled PP observed by SEM.

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Arthroscopic Treatment for Degenerative Elbow Contractures (주관절 퇴행성 강직의 관절경적 처치)

  • Moon, Young-Lae;You, Jae-Won;Kim, Dong-Whee
    • Journal of the Korean Arthroscopy Society
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    • v.5 no.2
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    • pp.116-119
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    • 2001
  • Purpose : To describe long-term clinical results and serial changes in the postoperative range of motion(ROM) after arthroscopic treatment for a limitation of motion(LOM) of the elbow. Materials and Methods : The subjects who visited chosun university hospital from December, 1996 to January 2000 were twenty-one patients ranging from 37 to 54 years of age, and the average age was 43.2 years. The chief complaints were painful limitation of motion of the elbow and average ROM showed that flexion contracture were 17 degrees and further flexion were 87 degrees. Results : The total ROM was $70^{\circ}$ preoperatively. 2 months after postoperatively the mean flexion contracute improved from $17^{\circ}\;to\;3^{\circ}$ with further flexion from $87^{\circ}\;to\;122^{\circ}$ degrees. One year after postoperatively the mean flexion contracture were $5^{\circ}$ and further flexion were $113^{\circ}$. All patients reported a decresement in pain level as well as improvement in motion. There was no complication in this series. Conclusion : Arthroscopic surgery appear to be satisfactory management modality for degenerative elbow contractures.

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Quasi-Analytical Method of C/SiC Material Properties Characterization (C/SiC 재료의 물성 측정을 위한 준 해석적 방법)

  • Kim, Yeong-K.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.05a
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    • pp.437-440
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    • 2010
  • This paper represents a simple and effective calculation method to predict the orthotropic engineering constants for C/SiC woven fabric composite. The method, a quasi-analytical method using the modified equivalent laminated model, idealizes the woven fabric structure as a symmetric three-ply laminate to utilize a classical laminated plate theory. The required initial parameters are in-plane modulus from experiments and crimp ratio of the woven fabric. This study shows its feasibility by demonstrating example to calculate the engineering constants to thickness direction needed for three dimensional thermo-mechanical stress calculations.

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potential of Noncircular Fiber as Reinforcing Material l. C-type carbon fiber

  • Boh, Shim-Hwan;Rhee Bo sung
    • Korean Journal of Materials Research
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    • v.4 no.7
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    • pp.817-822
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    • 1994
  • The reinforcing effect of C-shape carbon fiber was investigated as comparing to typical round-shape fiber with similar properties. The results show that C-shape fiber reinforced materials have better in almost all aspects of mechanical properties, or 218% in flexural strength, 223% flexural modulus, 157% interlamina shear strength, 227% impact strength, 184% transverse flexural strength and so on. Also in damping characteristics considerably concerned with fatigue life, friction/wear coefficient of a material, C-CF/EP had about 185% greater. In this research, we present the potential of non-circular fiber reinforcing materials by C-shape carbon fiber.

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