• 제목/요약/키워드: turning

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기립자세 증진 운동이 파킨슨병 환자의 제자리 돌기 동작에 미치는 영향 (The Effects of Standing Posture Improvement Exercise to the Turning Round Movement in Patients with Parkinson Disease)

  • 김주현;황병용;윤희종
    • The Journal of Korean Physical Therapy
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    • 제19권5호
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    • pp.21-28
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    • 2007
  • Purpose: The aims of this study was to evaluate the effects of shoulder lateral rotation and trunk extension exercises on standing posture improvement exercises using turning round in the patients with Parkinson's disease. Methods: For twenty-one patients with Parkinson's disease, shoulder lateral rotation and trunk extension exercises were performed for a total of three sets, ten times a set, three days a week for twelve weeks. To measure turning round, ink foot-print method was used. The number of steps and time were measured every week for before and after study (twelve weeks). Results: The results are as follows: Changes in steps and time on each week during twelve weeks showed significant differences, compared with before test(p<0.05). Conclusion: Standing posture improvement exercises can help perform turning round in the patients with Parkinson's disease.

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비보호좌회전에서의 간격수락 행태모형 개발 (Development of Gap Acceptance Models for Permitted Left Turn Intersections)

  • 이청원;이동민;황순천
    • 한국도로학회논문집
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    • 제18권5호
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    • pp.95-103
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    • 2016
  • PURPOSES : Permitted left turn is a turning maneuver in which a vehicle turns left using a gap between oncoming vehicles, called gap acceptance, and it enables for more efficient traffic operation at intersections. In Korea, the permitted left turn has not been a common maneuver at signalized or un-signalized intersections. However, many experts and the Police Agency tried to apply this effective turning maneuver at intersections in Korea since 2010. Though the investigation of gap acceptance is significantly important in understanding a driver's behavior at intersections, there have not been many studies about this topic, specifically a study to develop probability models of gap acceptance behavior. METHODS : In this study, the probability model of gap acceptance behavior for a permitted left turn was developed based on observational field studies. To develop the model, seven variables were analyzed including gap, waiting time, traffic volume, conflict-flow vehicle type, left-turning vehicle type, the number of lane, and time. RESULTS : In the final model, gap and left-turning vehicle type were found to be significant influencing factors. CONCLUSIONS : Through this model development, it was concluded that as the gap size increased, the probability of gap acceptance was higher. Moreover, when a left-turning vehicle was a passenger car, the probability of gap acceptance was higher than compared to large size buses or freight cars.

용접부의 선삭특성에 관한 실험적 연구 (An Experimental Study on the Turning Property of Welded Material)

  • 장복득
    • 한국정밀공학회지
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    • 제3권3호
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    • pp.13-21
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    • 1986
  • Turning property of metal is affected by the cutting condition, tool geome- try and cutting material. But the turning property of welded material is not welknown. Welded structures usually contain nonhomogeneity, defects and resi- dual stresses due to differential contraction between welded metal and base metal. In this paper, authors conducted the experimental test on the turning property, by changing turning condition and welding electrodes of the welded specimens. The results obtained in these experimental tests are as follows; (1) Within the limit of this experimental test, the cutting force of the weld zone is bigger than that of base metal, and this phenomena is caused by the different mechanical property of the weld zone. The range of the variation of cutting force in the weld zone is caused by the nonhomogeneity of the weld zone, respectively. (2) The surface roughness follows the general characteristic of the effect of cutting condition on the surface roughness and the surface roughness of the weld zone shows coarse surface comparing with that of the base metal. (3) The specimen welded by the electrode E4301, shows worse cutting property than that of E4361 and E4313.

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Co-Cr-Mo 합금의 선삭 가공 특성에 관한 연구 (A Study on the Machining Characteristics of Co-Cr-Mo Alloy in Turning Process)

  • 홍광표;조명우;최인준
    • Design & Manufacturing
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    • 제11권1호
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    • pp.50-54
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    • 2017
  • In this study, researches were conducted as follows. First, as the basic experiment, the cutting speed, feedrate, and the depth of cut were set as the process parameters, and by setting the surface roughness as the factor of measurement for each of the combinations, and the analysis about cutting tendency of the material was conducted by proceeding the turning process of Co-Cr-Mo alloy. Second, by setting the feature of the surface roughness according to the 'turning processing condition' that was confirmed in the previous experiment, and by applying the Taguchi Method, the conditions that influence the features of the surface roughness according to the 'turning processing condition' of Co-Cr-Mo was analyzed, and also by measuring the surface roughness according to each of the 'cutting conditions', the optimal processing condition was generated. As the result of analysis, it was possible to understand that the factor that mostly affects the surface roughness was the cutting speed, followed by the dept of cutting and transfer speed, and as for the optimal processing condition, it was possible to find that the cutting speed was 5,000rpm, and the depth of cut was 0.1mm, and the feedrate was 0.003mm/rev, and the value of the surface roughness at this point is $0.197{\mu}m$.

CBN 공구를 이용한 선삭에서의 절삭력과 공구마모 특성 (Cutting Forces and Tool Wear Characteristics in Hard Turning using CBN Tools)

  • 김태영;스기타;신형곤;김종택
    • 한국기계가공학회지
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    • 제6권1호
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    • pp.27-33
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    • 2007
  • Hard turning on modern lathes becomes a realistic replacement for many grinding applications. Because CBN tools are expensive, excessive tool wear can eliminate economic advantages of hard turning. This paper describes a study of investigating the cutting force and the characteristics of tool wear in hard turning of hardened steels, AISI 52100. Cutting forces generated using CBN tools have been evaluated. The radial thrust cutting force was the largest among three cutting force components. It increased dramatically as a result of progressive tool wear. On the other hand, the result shows significantly different wear characteristics between high CBN and low CBN. Backpropagation neural network was used for the estimation of tool wear. The networks were achieved the reliability of 96.3% even when the spindle speed and feed rate are changed.

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절삭 깊이의 무작위 제어를 적용한 다이아몬드 선삭공정에서 소재회전 반경에 따른 미세패턴의 크기변화 분석 연구 (A study on size variation of micro-pattern according to turning radius of workpiece in diamond turning with controlled random cutting depth)

  • 정지영;한준세;최두선;제태진
    • Design & Manufacturing
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    • 제14권1호
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    • pp.63-68
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    • 2020
  • Ultra-high brightness and thin displays need to optical micro-patterns which can uniformly diffuse the lights and low loss. The micro random patterns have characteristics to rise the optical efficiency such as light extraction, uniform diffusion. For this reason, various fabrication processes are studied for random patterns. In this study, the micro random patterns were machined by diamond turning which used a controlled cutting tool path with random cutting depth. The machined patterns had random shape and directionality along the circumferential direction. The average width and length of machined random pattern according to rotation radius were 40.13㎛~55.51㎛ and 37.25㎛~59.49㎛, and these results were compared with the designed result. Also, the machining error according to rotation radius in diamond turning using randomly controlled cutting depth was discussed.

스퍼 유성감속기 기반 선박용 터닝기어의 설계 변경 (Design Modification of Marine Turning Gear Based on Spur Planetary Gear)

  • 김건우;이재욱;장진석;오주영;홍종해;이강재
    • 한국기계가공학회지
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    • 제18권12호
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    • pp.7-14
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    • 2019
  • A marine turning gear controls the position of the piston-crank mechanism by rotating the flywheel of the marine engine at a low speed, which is the main auxiliary machine that enables the disassembly and maintenance of the engine. In this study, the safety factor for surface durability and tooth bending strength was improved by the design modification of the marine turning gear based on the spur planetary gear. Angular velocity, torque, and efficiency of the turning gear were measured using a reliability evaluation tester, and a multibody dynamics model for analysis corresponding to the test results was developed. Finally, it was confirmed that the design improvements improved the tooth surface damage of the sun gear in the 3rd reduction stage.

직교배열에 의한 선삭과 회귀분석방법에 의한 Al-6061의 진원도 평가 (A Roundness Evaluation of Al-6061 Turning by Orthogonal Table and Multiple Linear Regression)

  • 장성민;백시영
    • 한국산학기술학회논문지
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    • 제13권1호
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    • pp.45-50
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    • 2012
  • 본 논문은 CNC 선반에서 Al-6061의 보링 선삭 후 진원도 오차 분석에 관한 것이다. 실험은 실험계획법을 기초로 하여 신호대 잡음비, 분산분석을 사용하여 진원도 오차에 관한 파라미터의 영향을 연구하였다. 그리고 다중선형회귀분석은 진원도 오차의 예측 가능한 수학적 모델을 유도하기 위해 적용되었다. 선삭 파라미터인 고정압, 벽두께, 절삭깊이 그리고 이송속도는 논문의 목적달성을 위해 적용되었고 그 결과를 고찰하였다.

초경합금재의 하드터닝에서 공구재종에 따른 절삭성 (Hard Turning Machinability of V30 Cemented Carbide with PCD, cBN and PcBN Cutting Tool)

  • 허성중
    • 한국정밀공학회지
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    • 제25권12호
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    • pp.47-54
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    • 2008
  • Hard turning process can be defined as a single-point machining process carried out on "hard" materials. The process is intended to replace or limit traditional grinding operations that are expensive, environmentally unfriendly, and inflexible. The purpose of this study is to achieve a systematic understanding of machining characteristics and the effects of machining parameters on cutting force, tool wear shape and chip formation by the outer cutting of a kind of wear resistant tungsten carbide V30. Hard turning experiments were carried out on this alloy using the PCD (Poly Crystalline Diamond), cBN (cubic Boron Nitride) and PcBN (Polycrystalline cubic Boron Nitride) cutting tools. The PcBN and the usual cBN tools were used to be compare with the PCD tool and the dry turning was carried out. The PcBN is attractive as the tool material which replaces the PCD. The tool wear width and cutting force were measured, and the worn tool and chip were observed. The difference of the tool wear mechanism among the three tool materials was investigated.

EVOLUTION OF INTERNAL WAVES NEAR A TURNING POINT IN THE SOUTH CHINA SEA USING SAR IMAGERY AND NUMERICAL MODELS

  • Kim, Duk-Jin;Lyzenga, David R.;Choi, Woo-Young;Kim, Youn-Soo
    • 대한원격탐사학회:학술대회논문집
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    • 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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    • pp.61-64
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    • 2007
  • Subsurface Internal Waves (IWs) can be detected in satellite images as periodic alternating brighter/darker stripes. It is known that there are two types of IWs - depression type and elevation type - depending on the water depth in stratified oceans. In this study, we have quantitatively verified the process of converting polarity from depression waves to elevation waves using ERS-2 SAR images acquired over the northern South China Sea. We simulated the evolution of IWs near a turning point with a numerical model for internal wave propagation. The simulation results near the turning point clearly showed us not only a conversion process of IWs from depression to elevation waves, but also a similar wave pattern with the observed SAR image. We also simulated SAR intensity variation near the turning point. The upper layer currents were computed at regular intervals using the numerical model, as the IWs were passing through the turning point. Then, an integrated hydrodynamic-electromagnetic model was used for simulating SAR intensity profiles from the upper layer currents at each position. The simulated SAR intensity profiles at each position were compared with the observed SAR intensities.

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