• Title/Summary/Keyword: Work speed

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A STUDY ON THE SPEED CONTROL OF A LOW SPEED-LONG STROKE MARINE DIESEL ENGINE (저속 장행정 박용디젤기관의 속도제어에 관한 연구)

  • 유영호;하주식
    • Journal of Advanced Marine Engineering and Technology
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    • v.12 no.4
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    • pp.53-61
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    • 1988
  • Speed of a diesel engine is usually controlled by the hydraulic governor which uses the centrifugal force of rotating fly balls for sensing the error speed. But for a recently developed high efficient, low speed and long stroke 2 cycle marine diesel engine, this governor doesn't work well enough because of too much changes of toraring force during one revolution of engine and too long uncontrollable time due to small numbers of cylinder. For improvement of jiggling phenomena and unstability various studies are being carried out, but they are not enough for a steep load change in a small ship's generator plant or at rough sea condition in a propulsion engine. In this paper, authors propose a new method to control a fuel before the change of angular velocity due to load change by feedforward the change of load, and find that the proposed method shows quite a good control performance in comparision to the customary PID control method by simulation using a digital computer for the various load change.

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Axial Force of a V-Belt CVT -Experimental Study- (V-벨트 CVT의 축력해석 II -실험적 연구-)

  • 김광원;김현수
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.13 no.5
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    • pp.847-854
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    • 1989
  • Axial force of a V-belt CVT is investigated experimentally. The experimental results on speed ratio-torque-axial force show good agreement with the theoretical results that were obtained in the previous work. It is also found that torque capacity of the V-belt CVT increases as the axial force and the speed ratio increase. Impending slip which occurs at the maximum torque is determined via experiments for various speed ratios. Based on the impending slip region, and the theoretical curves for the speed ratio-torque-axial force relationship, an actual operating criteria for the V-belt CVT is obtained. It is suggested to use the actual operating criteria with the theoretical equations as a basic design formula for the V-belt CVT.

Measurement of Sound Speed Following the Fluid Temperature Using Acoustic Inspection Device

  • Jeon, E.S.;Kim, W.T.;Kim, I.S.;Park, H.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.30 no.3
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    • pp.207-211
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    • 2010
  • In this paper, the fluid AID(acoustic inspection device) was developed to measure SOS(speed of sound) since fluids used in most of industrial fields have different properties and its equipment is highly expensive. From AID developed, it is intended to get potentially the capability to distinguish the kind of fluid using the measurement by the SOS at various fields. In order to measure the sound speed of specific fluids, the measurement system and ultrasonic sensors are composed. The fluid used in the experimental work are soybean oil, glycerin, diesel oil and the error of time difference due to the container wall is extracted for preliminary experiment. As results, the variations of sound speed according to the temperature change of target fluid were analyzed and the polynomial equations were proposed.

Research on Transition of Road Bed of Wuhan-Guangzhou Passenger Line and Bridge

  • Kang, Bo-Soon;Jun, Yang
    • International Journal of Railway
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    • v.2 no.4
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    • pp.180-186
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    • 2009
  • High speed railway challenge the design, construction and maintaining of traditional railway, many traditional design concepts have been changed. Transition of railway and bridge has two main problems. one is that different lines have different ability of resisting distortion in area of trial load, which was known that problem of smooth transition of stiffness, the other is that differential settlement between artificial structure and earth structure cause bending of railway. The two problems have effect on train moving. The principle of processing transition of railway and bridge is same in world, but it is difficult to find relationship between design standard of transition, vehicle performance, line standard, design speed and so on form documentation and data reports. Based on mechanics, the paper analyzed dynamic performance of transition of high speed railway, studied various rough elements which is effective to train moving, built mathematical model of interaction of train and transition of high speed railway and developed numerical simulation software. In various different work conditions, we did great quantity of numerical simulation, comprehensive analysis and performance analysis.

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Relations between Fatigue and Work-related Factors in Workers (일개 생산직 근로자들의 작업수행과 피로도와의 관계)

  • Jung, Eun-Sook;Cha, Nam-Hyun
    • Research in Community and Public Health Nursing
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    • v.22 no.4
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    • pp.420-428
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    • 2011
  • Purpose: The purpose of this study was to investigate the relations between fatigue and work-related factors in workers. Methods: A total of 204 subjects aged between 21 and 59 were selected through convenient sampling. Data were collected with a self-reported questionnaire from May 20 to 31, 2011. Collected data were analyzed with SPSS/WIN 17.0. Results: Difference in fatigue according to general characteristics was significant according to duty type. Difference in fatigue according to occupational characteristics was significant according to work intensity, work speed, demand of work concentration, work space, physical environment, largest weight by hands, vibration, visual demand of work, difficulty of work practice, work stress, and rest hours in holiday. There was a positive correlation between fatigue and occupational characteristics. Stepwise multiple regression analyses showed that educational level, work intensity, and rest hours in holiday were the strongest factors associated with fatigue ($R^2$=.363 p<.001). These factors explained fatigue by 36.3%. Conclusion: The findings of this study may be useful in understanding workers' fatigue and developing more specific fatigue relief programs.

A Study on Smart Work 2.0 Implementation Methodology (스마트워크 2.0 구축 방법론에 대한 연구)

  • Lim, Kyu-Kwan
    • Journal of Digital Convergence
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    • v.9 no.4
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    • pp.235-244
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    • 2011
  • According to spread of Smart Work introduction to public organizations & commercial enterprises, its being more focused on how to implement Smart Work effectively. So far current Smart Work, mainly Mobile Office has emphasized the speed & efficiency of management. But future Smart Work, Smart Work 2.0 must focus on the creativity & innovation of companies & people. In order to do that, the new technology like Social networking & Cloud computing should be applied. This study suggests Smart Work 2.0 implementation methodology including critical successful factors & solutions of Smart Work implementation through referencing existing implementation methodology and case study.

Effect of Welding Condition on Tensile Properties of Friction Stir Welded Joints of Al-7075-T651 Plate (용접 조건이 Al-7075-T651의 마찰교반용접부의 인장 특성에 미치는 영향)

  • Kim, C.O.;Kim, S.J.
    • Journal of Power System Engineering
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    • v.15 no.2
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    • pp.61-68
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    • 2011
  • This paper investigates the tensile properties of the friction stir welded joints of Al 7075-T651 aluminum plate according to the welding conditions. A 7075-T651 aluminum alloy plate with a thickness of 6.0 mm was used in this investigation. For the friction stir welding (FSW) process, a tool with shoulder diameter of 20 mm and probe diameter of 9 mm was used. The rotation speed and traverse speed conditions were changed in this study, the other welding conditions are constant. The welding direction was aligned with the material rolling direction, and dimension of the FSW plate were $250{\times}100{\times}6\;mm$. As far as this work is concerned, the optimal FSW conditions are determined as the rotation speed, 600 rpm and traverse speed 0.8 mm/sec or the rotation speed, 800 rpm and traverse speed 0.5 mm/sec.

Vibration Characteristics of High Speed Rotary Bell Cup (고속 회전 벨 컵의 진동 특성)

  • Sohn, Jung Woo;Park, Ji Hoon;Choi, Seung-Bok
    • Transactions of the Korean Society for Noise and Vibration Engineering
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    • v.25 no.11
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    • pp.771-778
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    • 2015
  • In this work, vibration characteristics of high speed rotary bell cup for paint atomizer are numerically investigated. New type of bell cup model is proposed and additional corresponding models with design parameter variations for length and diameter are constructed. Dynamic characteristics, such as natural frequencies and corresponding mode shapes, are studied for each model as a first step. To investigate operation stability, critical speed of rotary bell cup is numerically analyzed based on Campbell diagram and separation margin between operating speed and critical speed is identified. Unbalance vibration responses are also investigated with respect to design parameter variation, operating speed and balancing quality grade of G. Then the proper design guideline for stable operation of high speed rotary bell cup for paint atomizer is suggested.

Reconstruction Analysis of Vehicle-pedestrian Collision Accidents: Calculations and Uncertainties of Vehicle Speed (차량-보행자 충돌사고 재구성 해석: 차량 속도 계산과 불확실성)

  • Han, In-Hwan
    • Transactions of the Korean Society of Automotive Engineers
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    • v.19 no.5
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    • pp.82-91
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    • 2011
  • In this paper, a planar model for mechanics of a vehicle/pedestrian collision incorporating road gradient is derived to evaluate the pre-collision speed of vehicle. It takes into account a few physical variables and parameters of popular wrap and forward projection collisions, which include horizontal distance traveled between primary and secondary impacts with the vehicle, launch angle, center-of-gravity height at launch, distance from launch to rest, pedestrian-ground drag factor, the pre-collision vehicle speed and road gradient. The model including road gradient is derived analytically for reconstruction of pedestrian collision accidents, and evaluates the vehicle speed from the pedestrian throw distance. The model coefficients have physical interpretations and are determined through direct calculation. This work shows that the road gradient has a significant effect on the evaluation of the vehicle speed and must be considered in accident cases with inclined road. In additions, foreign/domestic empirical cases and multibody dynamic simulation results are used to construct a least-squares fitted model that has the same structure of the analytical one that provides an estimate of the vehicle speed based on the pedestrian throw distance and the band within which the vehicle speed would be expected to be in 95% of cases.

Study on the Teeth Grinding Condition of SCM415H Gears (SCM 415H 기어의 치면 연삭조건에 관한 연구)

  • Kim, Lae-sung;Kim, Jongmin;Choi, Chang;Liang, Longjun;Lyu, Sung-ki
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.14 no.2
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    • pp.19-24
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    • 2015
  • Gears are produced through a variety of methods. In general, a metal piece is formed into the general shape of a gear through rough cuts. The gear then moves on to a more precise machine that removes more material. Grinders work via abrasion, rubbing a rough surface against a work piece at such high speeds that it literally scrapes unwanted material away from the item. Since the grinder is spinning so fast, the material is removed very quickly. This allows a grinder to remove a very small amount without taking any unwanted material with it. This study investigates the effect of grinding process parameters like grinding spindle speed and table transfer speed on the gear grade and grinding efficiency.