• Title/Summary/Keyword: Loading/Unloading time

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A study on the Desing Technuque of a Process Interration CNC Lathe for High Productivity (공정집약형 CNC 선반의 설계기술에 관한 연구)

  • 박종권;최대봉;황주호
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 1996.04a
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    • pp.651-657
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    • 1996
  • Industrial products are getting more and more complex. The number of parts or components and the variety of manufacturing processes are increasing. This leads to rapid product oriented machine tools. The process integrated CNC lathe is one of the these machine tools which can produce numerous parts and various machining processes and reduce the lead time and non-machining time. Therefore this study deals with the design technique of a process-intergated CNC lathe which can reduce the tact time and production cost by the speed-up of the tooling system and the high-speed machining oriented construction of 2 spindles and 2 turrets.

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On optimal cyclic scheduling for a flexible manufacturing cell

  • Kise, Hiroshi;Nakamura, Shinji;Karuno, Yoshiyuki
    • 제어로봇시스템학회:학술대회논문집
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    • 1990.10b
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    • pp.1250-1255
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    • 1990
  • This paper discusses an optimal cyclic scheduling problem for a FMC (Flexible Manufacturing Cell) modeled by a two-machine flowshop with two machining centers with APC's (Automated Pallet Changers), an AGV (Automated Guided Vehicle) and loading and unloading stations. Cyclic production in which similar patterns of production is repeated can significantly reduce the production lead-time and WIP (Work-In-Process) in such flexible, automated system. Thus we want to find an optimal cyclic schedule that minimizes the cycle time in each cycle. However, the existence of APC's as buffer storage for WIP makes the problem intractable (i.e., NP-complete). We propose an practical approximation algorithm that minimizes, instead of each cycle time, its upper bound. Performances of this algorithm are validated by the way of computer simulations.

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A Design and Characteristics Analysis of High Efficiency Gantry Crane (고효율 갠트리 크레인 설계 및 성능분석)

  • 김경한;이영진;이진우;이권순
    • Journal of Korean Port Research
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    • v.14 no.4
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    • pp.395-406
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    • 2000
  • In this paper, an improved high efficiency gantry crane for container transportation is designed. The basic concept of the designed crane can be used with modification of the classical gantry crane instead of changing lots of them. This crane can reduce the cycle time more than the classical gantry carne. The high efficiency gantry crane can improve the productivity of the container transportation job because of reducing cycle time. The loading and unloading capability are compared with classical crane. The result show that show that the proposed crane has better performances than classical type.

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A Study on the Prediction of Yard Tractors Required by Vessels Arriving at Container Terminal (컨테이너터미널 입항 선박별 야드 트랙터 소요량 예측에 관한 연구)

  • Cho, Hyun-Jun;Shin, Jae-Young
    • Journal of Korea Port Economic Association
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    • v.37 no.4
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    • pp.33-40
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    • 2021
  • Currently, the shipping and port industries are implementing strategies to improve port processing capabilities through the expansion and efficient operation of port logistics resources to survive fierce competition with rapidly changing trends. The calculation of the port's processing capacity is determined by the loading and unloading equipment installed at the dock, and the port's processing capacity can be improved through various methods, such as additional deployment of logistics resources or efficient operation of resources in use. However, it is difficult to expect an improvement effect in a short period of time because the additional deployment of logistics resources is clearly limited in time is clear. Therefore, it is a feasible way to find an efficient operation method for resources being used to improve processing capacity. Domestic ports are also actively promoting informatization and digitalization with the development of the 4th industrial revolution technology. However, the calculation of the number of Y/T (Yard Tractor) assignments in the current unloading process depends on expert experience, and related previous studies also focus on the allocations of Y/T or Calculation of the total number of Y/T required. Therefore, this study analyzed the factors affecting the number of Y/T allocations using the loading and unloading information of incoming ships, and based on this, cluster analysis, regression analysis, and deep neural network(DNN) model were used.

Experimental Study on the Cooling and Heating Characteristics of System A/C Applying the Digital Scroll Compressor (디지털 스크롤 압축기를 적용한 시스템 에어컨의 냉난방특성에 대한 실험적 연구)

  • Jeon, Yong-Ho;Kim, Dae-Hoon;Kwon, Young-Chul;Jang, Geun-Sun;Lee, Yoon-Soo;Moon, Je-Nyung;Yoon, Baek;Hong, Ju-Tae
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.15 no.6
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    • pp.454-460
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    • 2003
  • In order to investigate the cooling and heating characteristics of a variable-capacity system A/C applying a digital scroll compressor, the cooling and heating capacities and COP are measured by the psychrometric calorimeter. The capacity of the system is controlled by the digital scroll compressor, which is operated by controling PWM valve and the loading vs. unloading time. In the case of unloading compared that of loading, the consumption power of the compressor is about 11% and the capacity variation of the system A/C is within about 1%. When the system A/C is operated under the cooling and heating standard conditions, COP is nearly uniform but cooling capacity and heating capacity increase at minimum, rated and maximum modes. The system A/C applying the digital scroll compressor is effective for the range with high load or the width of large load variation. When the auxiliary heater is on, at the cold region, the system A/C produces the excellent heating capacity.

Fracture Behavior Analysis in CFRP Specimens by Acoustic Emission and Ultrasonic Test (음향방출 및 초음파시험을 이용한 CFRP 시험편의 파괴 거동 해석)

  • Ahn, Seok-Hwan;Nam, Ki-Woo
    • Journal of the Korean Society for Nondestructive Testing
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    • v.21 no.3
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    • pp.251-260
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    • 2001
  • Damage Profess of CFRP laminates under monotonic tensile test was characterized by the correlation between Acoustic Emission(AE) and Ultrasonic Test(UT). The amplitude distribution of AE signal from a specimens is an aid to the determination of the extent of the different fracture mechanism such as matrix crack, debonding, fiber pullout and fiber fracture as load is increased. In addtion, the characteristics of ultrasonic amplitude attenuation are useful lot analysis of the different type of fracture mechanism. Different orientation of carbon fiber reinforced plastic specimens were used to investigate the AE amplitude range and ultrasonic amplitude attenuation. Finally, loading-unloading tests were carried out to check Felicity effect. During the tests, ultrasonic amplitude attenuation was investigated at the same time and compared with AE parameters. The result showed that two parameters of both AE and UT could be effectively used for analysis of fracture mechanism in CFRP laminates.

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Analysis on Thermomechanical Response to Tensile Deformation of GaN Nanowires (GaN 나노와이어의 인장 변형에 의한 열기계적 거동 해석)

  • Jung, Kwangsub;Zhou, Min;Cho, Maenghyo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.25 no.4
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    • pp.301-305
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    • 2012
  • In this work the mechanical behaviors of GaN nanowires are analyzed during tension, compression, and unloading deformations. The thermal conductivity of the nanowires at each deformed state is evaluated using an equilibrium Green-Kubo approach. Under tensile loading, the [0001]-oriented nanowires with hexagonal cross-sections undergo a phase transformation from wurtzite to a tetragonal structure. The phase transformation is not observed under compressive loading. The thermal conductivity decreases on going from compressive strains to tensile strains. The strain dependence of the thermal conductivity results from the relaxation time of phonon. A reverse transformation from the tetragonal structure to the wurtzite structure is observed during unloading. The thermal conductivities in the intermediate states are lower than the conductivity in the wurtzite structure at same strain. Such differences in the thermal conductivity between different atomic structures are mainly due to changes in the group velocity of phonon.

Numerical Analysis on External Strengthening Effects in Aged Structures (사용중인 구조물의 보강효과에 대한 해석적 연구)

  • 신승교;임윤묵;김문겸;박동철
    • Proceedings of the Korea Concrete Institute Conference
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    • 2002.05a
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    • pp.455-460
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    • 2002
  • In this study, a numerical analysis that can effectively predict the effect of strengthening of cracked flexural members is developed using axial deformation link elements. Concrete and interface between concrete and repair material are considered as quasi-brittle material. Reinforcing bars and reinforcing steel plates are assumed to perform as elasto-plastic materials. Unloading behavior of axial deformation link element is implemented. In the developed numerical model, a flexural member is intentionally cracked by pre-loading, then, the cracked member is repaired using extra elements, and reloaded. The results from analysis of repaired flexural members agrees well with available experiment results. Also, it was shown that the effect of strengthening and the change of failure mode with respect to the time for strengthening and thickness of repair materials. Based on the results, it was determined that the developed numerical model has a good agreement for determining failure modes and effect of strengthening in cracked flexural members. By utilizing the developed numerical analysis, the time and dimension of external strengthening in an existing cracked flexural member with predition of failure mechanism can be determined.

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FMS Control and Monitoring using Petri Net (Petri-Net 을 이용한 FMS 제어 및 모니터링)

  • Kim, Go-Joong;Jung, Moo-Young;Jo, Hyeon-Bo
    • Journal of Korean Institute of Industrial Engineers
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    • v.21 no.1
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    • pp.137-151
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    • 1995
  • A difficult problem in operating Flexible Manufacturing Systems (FMS) is to control the system in real-time by coordinating heterogeneous machines and integrating distributed information. The objective of the paper is to present the models and methodologies useful to resolve the difficult problem. The detailed objectives can be described in three folds. First, a hierarchical Colored and Timed Petri-Net (CTPN) is designed to control an FMS in real-time. The concerned FMS consists of a loading station, several machining cells, a material handling system, and an unloading station. Timed-transitions are used to represent the timed-events such as AGV movements between stations and cells, part machining activities in the cells. Signal places are also used to represent communication status between the host and the cell controllers. To resolve the event conflicts and scheduling problems, dispatching rules are introduced and applied. Second, an implementation methodology used to monitor and diagnose the errors occurring on the machines during system operation is proposed. Third, a Petri-Net simulator is developed to experiment with the designed control logic.

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Container Crane Control: Modified Time-Optimal Traveling Followed by Nonlinear Residual Sway Control (컨테이너 기중기의 제어 : 수정된 시간최적주행과 비선형 잔류흔들림 제어)

  • Hong, Keum-Shik
    • Journal of Institute of Control, Robotics and Systems
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    • v.5 no.5
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    • pp.630-639
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    • 1999
  • To achieve fast loading and unloading of containers from a container ship, quick suppression of the remaining sway motion of the container at the end of each trolley stroke is crucial. Due to the pendulum motion of the container and disturbances like sind, residual sway always exists at the end of trolley movement. In this paper, the sway-control problem of a container crane is investigated. A two-stage control is proposed. The first stage is a time optimal controlfor the purpose of fast trolley traveling. The second stage is a nonlinear control for the quick suppression of residual sway, which starts right after the first stage while lowering the container. The nonlinear control is investigated in the perspective of controlling an underatuated mechanical system, which combines partial feedback linearization to account for the known nonlinearities as much as possible, and variable structure control to account for the unmodeled dynamics and disturbances. Simulation and experimental results are provided.

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