• Title/Summary/Keyword: Turning Angle

Search Result 289, Processing Time 0.032 seconds

Small Agricultural Skid-steer Loader Using Belt Clutch Power Transmission (벨트클러치 전동방식의 농업용 소형 스키드 스티어 로더)

  • 김상헌;신범수;정준모;김창식
    • Journal of Biosystems Engineering
    • /
    • v.21 no.2
    • /
    • pp.134-145
    • /
    • 1996
  • Since the skid-steer loader is able to work for excavating, lifting and transporting load even at the narrow space, they are widely used in the regular farm and the livestock farm. The skid-steer loader normally adopts the hydrostatic transmission because the power to move the machine backward and forward should be delivered independently on both sides of wheels. Contrast to the mechanical system such as chain and belt transmissions, however, the hydrostatic transmission is less efficient in the use of energy and more difficult in the maintenance. This study was intended to investigate the feasibility of using triangular-type belt clutch and V-belt transmission for the newly developed skid-steer loader in order to overcome the problems stated in the hydrostatic transmission. In the developed triangular-type belt clutch, the centers of driving, driven and idler sheaves are arranged in the triangular shape in a plane, and V-belts were loaded loosely on three sheaves. The power is transmitted by pressing the idler connected to a lever on the loosened V-belt. Contrast to the normal belt clutch using two sheaves, the newly developed belt clutch has the characteristics of small contact-angle of the driving sheave at no bucket load and increasing contact-angle at the time of power transmission. The results of research can be summarized as follows: 1) The developed triangular-type belt clutch adopted a spring-loaded slackside idler which could transmit more power than a fixed idler could by sacrificing the belt life. The life of V-belt used in the power transmission reached at 500 hours(6 months) when the engine power of 11.8 ㎾ was transmitted. Also, it was feasible to develop the large industrial skid-loader with the V-belt transmission by using the proper set of sheaves. 2) The developed skid-steer loader changed the rotating radius and speed with bucket loads as the conventional skid steer loader did. The rotating speed was 47 deg/s at the maximum bucket load of 2.74 kN when the minimum rotating radius was 1.5m. 3) The power required in turning at the bucket load of 2.74 kN was 4 ㎾ and the slippage of V-belt was less than 1%.

  • PDF

The Effect of Towline and Bridle on the Slewing Motion of Barge (예인삭 및 브라이들이 부선의 회두운동에 미치는 영향)

  • Yu, Chol;Lee, Sang-Min
    • Journal of Navigation and Port Research
    • /
    • v.35 no.6
    • /
    • pp.483-488
    • /
    • 2011
  • When a tug-barge navigates in the water, maneuvering ability of a tug is affected by the slewing motion of barge. Therefore it is necessary to decrease the slewing motion of a barge for safe towing work. We chose two different types of barge model and investigated their motion depending on the existence of bridle, towing speed and length of towline. The experiments are performed in the still water using the wire rope for the towline. A longer towline makes the heading angle smaller. The towing speed does not largely affect the turning of barge. Finally, it is noted that the bridle of a towing line decrease the slewing motion of barge more effectively.

A STUDY ON THE FACIAL ESTHETIC PREFERENCES AMONG KOREAN YOUTHS: ASSESSMENT OF PROFILE PREFERENCES (한국 젊은이의 안면미 선호경향에 관한 연구 : 얼굴의 측모평가를 중심으로)

  • Song, Sejin;Choi, Ik-chan
    • The korean journal of orthodontics
    • /
    • v.22 no.4 s.39
    • /
    • pp.881-920
    • /
    • 1992
  • This study was designed to assess profile preferences among Korean youths in the year 1992. Facial esthetics was evaluated by means of silhouette profiles, eliminating the influence of a number of aspects that may affect judgment when normal lateral photographs are used. The main points of preference to be clarified here are as follows. First, on facial convexity, Second, on nasion depth, Third, on mentolabial sulcus depth, Fourth, on the position of upper and lower lips, Fifth, on facial type according to Angle's classification of malocclusion, Sixth, on Song's tangents. The 54 subjects printed in questionnaire as black and white silhouettes were selected from 300 tracings from cephalometric radiographs of people whose age ranging from 11 to 20 years. Photographs of six female subjects were retouched by computer graphic software and printed in color and black/white photographs which were used for adaptation of eyes of participants in selecting profiles in silhouette. They constitute 2 questions. The 54 subjects were grouped as 22 questions, each of them composed of 6 subjects, according to the aspects to be clarified. Twenty four questions in total were asked to assess profile preferences. For the assessment, the profile line, the facial esthetic triangle, Song's tangents, and Angle's classification of malocclusion were introduced. The profile line is composed of 11 component points which are Trichion, Glabella, Nasion, Pronasale, Subnasale, Labrale superius, Stomion, Labrale inferius, Supramentale, Pogonion, and Gnathion. The facial esthetic triangle is composed of 3 tangents: A-tangent which is the tangent of dorsum of nose, B-tangent which is the line passing through Sn and Ls, and C-tangent which is drawn on the turning point of the curve which lies between mentolabial sulcus (Sm) and pogonion (Pg). Angle's classification has 3 types of malocclusion which are Class I, Class II, and Class III. Class II malocclusion is subdivided into Division 1 and Division 2. The participants of the survey were composed of 861 college students (448 male students, 413 female students) whose majors grouped as Fine Arts. Liberal Arts, and Natural Sciences, and whose mean age 21.8 years. The statistics program SPSS/PC + of SPSS Inc. was used to analyze answers of participants. Crosstabulation, Chi-square test, and Kendall test were done. The conclusions are as follows: First, Korean youths have a tendency to prefer the slightly convex face to the flat or concave face. Second, they prefer a moderately deep nasion. Third, they prefer a moderately deep mentolabial sulcus. Fourth, they prefer the position of lips which are near to Ricketts' E-line. The position of the upper lip which is slightly posterior to E-line is preferred. The upper lip which lies too far anterior or posterior to the lower lip is not perferred. Fifth, they prefer most, according to Angle's Classification of Malocclusion, Class I facial profile which has a slight inclination to Class II division 2. The order of preference is Class I, Class II division 2, Class III, and Class II division 1. Sixth, they prefer the type 2 and 3 of Song's tangents. The facial profile within which A-and B-tangent meet is preferred. The facial profile which has Cotangent that .meets with A-tangent slightly posterior to the crossing point of A-and B-tangent or that parallels with B-tangent is preferred.

  • PDF

Effect of Cross/Parallel Rib Configurations on Heat/Mass Transfer in Rotating Two-Pass Turbine Blade Internal Passage (회전하는 터빈 블레이드 내부 이차냉각유로에서 엇갈린요철과 평행요철이 열/물질전달에 미치는 영향)

  • Lee, Se-Yeong;Lee, Dong-Ho;Jo, Hyeong-Hui
    • Transactions of the Korean Society of Mechanical Engineers B
    • /
    • v.26 no.9
    • /
    • pp.1249-1259
    • /
    • 2002
  • The present study investigates the convective heat/mass transfer inside a cooling passage of rotating gas-turbine blades. The rotating duct has various configurations made of ribs with 70。 attack angle, which are attached on leading and trailing surfaces. A naphthalene sublimation technique is employed to determine detailed local heat transfer coefficients using the heat and mass transfer analogy. The present experiments employ two-surface heating conditions in the rotating duct because the surfaces, exposed to hot gas stream, are pressure and suction side surfaces in the middle passages of an actual gas-turbine blade. In the stationary conditions, the parallel rib arrangement presents higher heat/mass transfer characteristics in the first pass, however, these characteristics disappear in the second pass due to the turning effects. In the rotating conditions, the cross rib present less heat/mass transfer discrepancy between the leading and the trailing surfaces in the first pass. In the second pass, the heat/mass transfer characteristics are much more complex due to the combined effects of the angled ribs, the sharp fuming and the rotation.

The Study of Aerodynamic Characteristics of Jet-Vane Affected by the Shroud (Shroud의 영향에 따른 제트 베인의 공기역학적 특성 연구)

  • Park, Soon-Jong;Park, Jong-Ho
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.16 no.2
    • /
    • pp.34-41
    • /
    • 2012
  • Thrust vector control system is a control device which is mounted on the exit of the nozzle to generate pitch, yaw and roll directional force by deflecting flow direction of the supersonic jet from the nozzle. Thermal and aerodynamic loads are acting on the surface of jet vane when it is exposed to the jet flow. Axial thrust loss and side thrust loss are affected by shock patterns and interactions between jet-vanes which varies with jet-vane geometry and turning angle. In this research, the performance estimation using the numerical simulation analysis of the nozzle is given and the investigation of the flow visualization and aerodynamic performance with the enforced power to the vane is taken.

Steering Characteristics of an Autonomous Tractor with Variable Distances to the Waypoint

  • Kim, Sang Cheol;Hong, Yeong Gi;Kim, Kook Hwan
    • Journal of Positioning, Navigation, and Timing
    • /
    • v.2 no.2
    • /
    • pp.123-130
    • /
    • 2013
  • Autonomous agricultural machines that are operated in small-scale farmland frequently experience turning and changes in direction. Thus, unlike when they are operated in large-scale farmland, the steering control systems need to be controlled precisely so that travel errors can be minimized. This study aims to develop a control algorithm for improving the path tracking performance of a steering system by analyzing the effect of the setting of the waypoint, which serves as the reference point for steering when an autonomous agricultural machine moves along a path or a coordinate, on control errors. A simulation was performed by modeling a 26-hp tractor steering system and by applying the equations of motion of a tractor, with the use of a computer. Path tracking errors could be reduced using an algorithm which sets the waypoint for steering on a travel path depending on the radius of curvature of the path and which then controls the speed and steering angle of the vehicle, rather than by changing the steering speed or steering ratio which are dependent on mechanical performance.

Development of Non-Contact Conveyor for Clean Process by Applying Magnet Gears (비접촉형 마그넷기어를 적용한 클린 반송장치의 개발)

  • Oh, Young-Jin;Lho, Tae-Jung
    • Journal of the Korea Academia-Industrial cooperation Society
    • /
    • v.11 no.10
    • /
    • pp.3633-3640
    • /
    • 2010
  • For a development of non-contact magnet gear which is magnetized as a helical shape, a method of 3-dimensional FEM analysis is used. An elementary technique required for magnetic property analysis and parts design about magnet gear is ensured. In order to test a performance of clean conveyor and turning device which is composed with magnet gear, a clean class 10 environment booth is used for a trial test. It is verified that the magnet conveyor can be acceptable under a condition of clean class 10 by a result of trial test about transfer speed, maximum torque permission, cleanness, maximum transfer weight, existence of hunting and degree of noise.

Wear Analysis of Journal Bearings Operating in a Shaft During Motoring Start-up and Coast-down Cycles - Part II: Wear Analysis of two Journal Bearings Supporting a Misaligned Shaft (모터링 시동 및 시동정지 사이클에서 경사진 축을 갖는 저어널베어링의 마모 해석 - Part II: 경사진 축을 지지하는 두 저어널베어링의 마모해석)

  • Chun, Sang Myung
    • Tribology and Lubricants
    • /
    • v.33 no.4
    • /
    • pp.168-186
    • /
    • 2017
  • This paper presents a wear analysis procedure for calculating the wear of journal bearings during the start-up and coast-down cycles of a motoring stripped-down single cylinder engine operating with a tilted shaft. In order to decide whether the lubrication state of a journal bearing is in the mixed-elasto-hydrodynamic lubrication regime, we utilize lift-off speed and MOFT (most oil film thickness) under mixed-elasto-hydrodynamic lubrication regime at the corresponding aligned shaft. We formulate an equation for the modified film thickness in a misaligned journal bearing considering the additional wear volume described in Part I of this study. For this, we use the calculation results of the degree of misalignment and tilting angle obtained after finding the eccentricities of the two bearings supporting the crankshaft of a single cylinder engine. In this Part II, we calculate the wear of journal bearings using the fractional film defect coefficient, the asperity load sharing factor, and the modified specific wear rate for the application of mixed-elasto-hydrodynamic lubrication regime. We show that the accumulated wear volume after turning the ignition switch on and off once, increases to ${\sigma}=39{\mu}m$ and then decreases from ${\sigma}=39{\mu}m$ with increasing in surface roughness.

Validation of a Vehicle Model and an ABS Controller with a Commercial Software Program (상용 소프트웨어를 이용한 차량 모델 및 ABS 제어기의 성능 평가)

  • Song, Jeong-Hoon
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.15 no.5
    • /
    • pp.180-187
    • /
    • 2007
  • This paper presents a mathematical vehicle model that is designed to analyze the dynamic performance and to develop various safety control systems. Wheel slip controllers for ABS is also formulated to improve the vehicle response and to increase the safety on slippery road. Validation of the model and controller is performed by comparison with a commercial software package, CarSim. The result shows that performances of developed vehicle model are in good accordance with those of the CarSim on various driving conditions. Developed ABS controller is applied to the vehicle model and CarSim model, and it achieves good control performance. ABS controller improves lateral stability as well as longitudinal one when a vehicle is in turning maneuver on slippery road. A driver model is also designed to control steer angle of the vehicle model. It also shows good performance because the vehicle tracks the desired lane very well.

Developing an Biomechanical Functional Performance Index for Parkinson's Disease Patients (한국형 파킨슨 환자의 역학적 기능수행지수 개발)

  • Shin, Sunghoon;Han, Byungin;Chung, Chulmin;Lee, Yungon
    • Korean Journal of Applied Biomechanics
    • /
    • v.30 no.1
    • /
    • pp.83-91
    • /
    • 2020
  • Objective: The study aimed to develop a functional performance index that evaluates the functional performance of Parkinson's patients, i.e., to integrate biomechanical measurements of walking, balance, muscle strength and tremor, and to use multiple linear regression with stepwise methods to identify the most suitable predictors for the progression of disease. Method: A total of 60 subjects were tested for sub-variables of four factors: walking, balance, isometric strength and hand tremors. Potential independet variables were extracted through correlation analysis of the sub-variables and dependent variables, Hoehn & Yahr scale. And then, a stepwise multiple regression analysis using the potential independent variables was performed to identify predictor of Hoehn & Yahr scale. Results: First, the results of the study showed that physical composition and gait had a relatively more correlated with the progression of the disease, compared to balance and hand tremor. Second, Parkinson's functional performance is characterized by dynamic pattern of walking, such as foot clearance and turning angle (TA) of walking, and a high-explained regression model is completed. Conclusion: The study emphasized the importance of walking variables and body composition in minor pathological features compared to Parkinson's patient's balancing ability and hand tremor. Specifically, it revealed that dynamic walking patterns functionally characterize patients. The results are worth considering when assessing functional performance related to the progression of the disease at the site.