• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.10
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• pp.1207-1218
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• 2013

It is difficult to predict derailment with the existing derailment coefficient like Nadal's formula which is based on the contact forces between one wheel and rail. A new derailment coefficient model developed on a wheelset is able to make a better estimate about the climb derailment, slip derailment, roll over derailment, and mixed derailment types of these. Moreover, not only the mechanical factors considered in the existing derailment coefficients but also other various factors affecting derailment such as wheel unloading and loading, diameter of wheel, and locations of axle-box bearings can be covered with this new derailment coefficient model. That is, the derailment patterns which couldn't be solved with the existing formulas such as Nadal's and Weinstock's models can be analyzed with this wheelset derailment coefficient model because of considering various factors causing derailment. Finally, the validity of the new derailment coefficient model is verified using dynamic model simulations.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.480-488
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• 2000

Cabbage is the most important vegetables in korea. The cabbage production was based on arduous human labor. A comprehensive research for substituting the human work by machines has been performed at present. In general, cabbage is cultivated on hillside in korea. The harvested cabbage in a field and carrying it to a vehicle for transportation are very laborious work. Hand labor in cabbage transportation to the market damages the quality of cabbage and is also a cause to increase the cost of cabbage production. This study was to design and evaluate a prototype cabbage loader for deserving efficient and safe transportation of cabbage. The developed cabbage loader was a semi-tracked vehicle operated by a hydraulic system, allowing the safe transporting and the loading of cabbage in a steep field. The maximum loading capacity of the loader was 1.0 ton. By using safety devices attached to the loader, the static slopes were 34.0% and 37.4% for the left and the rear roll-over, respectively. The maximum field speed was about 6km/hr with two cabbage pallets of 750kg at a 25% inclined field. The field capacity was about 35 pallets/hr in case of picking up, carrying and unloading two cabbage pallets. The field efficiency of the loader was analyzed to be more than 8 times in comparison of the conventional human labor. The developed loader would be applied for loading and carrying the other vegetables due to the similarity of operations. The study suggested a standard approach to the design of field machines operated in a steep field.

• Proceedings of the Korea Society for Simulation Conference
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• 2001.10a
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• pp.263-268
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• 2001

In this paper, we present a new heuristic algorithm fur buffer allocation in FMS (Flexible Manufacturing System). It is conducted by using a genetic algorithm and simulation. First, we model the system by using a simulation software, \"Arena\". Then, we apply a genetic algorithm to achieve an optimal solution. VBA blocks, which are kinds of add-in functions in Arena, are used to connect Arena with the genetic algorithm. The system being modeled has seven workstations, one loading/unloading station, and three AGVs (Automated Guided Vehicle). Also it contains three products, which each have their own machining order and processing times. We experimented with two kinds of buffer allocation problems with a proposed heuristic algorithm, and we will suggest a simple heuristic approach based on processing times and workloads to validate our proposed algorithm. The first experiment is to find a buffer profile to achieve the maximum throughput using a finite number of buffers. The second experiment is to find the minimum number of buffers to achieve the desired throughput. End of this paper, we compare the result of a proposed algorithm with the result of a simple buffer allocation heuristic based on processing times and workloads. We show that the proposed algorithm increase the throughput by 7.2%.t by 7.2%.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.23 no.11 s.170
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• pp.1982-1992
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• 1999

This paper presents a novel concept of cargo handling system adapted for a sea port subjected to severe time-varying tide. The proposed system can perform loading or unloading by using a sort of hydraulic elevator associated with real-time position control. In order to achieve a proof-of-concept, a small-sized laboratory model of the cargo handling system is designed and built. The model consists of three principal components container palette transfer (CPT) car, platform with lifting columns, and cargo ship. The platform activated by electro-rheological (ER) valve-cylinders is actively controlled to track the position of the cargo ship subjected to be varied due to the time-varying tide and wave motion. Following the derivation of the dynamic model for the platform and cargo ship motions, an appropriate control scheme is formulated and implemented. The location of the CPT car is sensed by a set of photoelectric switches and controlled via sequence controller. On the other hand, a sliding mode controller (SMC) is adopted as the position controller for the platform. Both simulated and measured control results are presented to demonstrate the effectiveness of the proposed cargo system.

• Smart Structures and Systems
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• v.24 no.3
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• pp.403-414
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• 2019

Offshore drilling has become a key process for obtaining oil. Offshore platforms have many applications, including oil exploration and production, navigation, ship loading and unloading, and bridge and causeway support. However, vibration problems caused by severe environmental loads, such as ice, wave, wind, and seismic loads, threaten the functionality of platform facilities and the comfort of workers. These concerns may result in piping failures, unsatisfactory equipment reliability, and safety concerns. Therefore, the vibration control of offshore platforms is essential for assuring structural safety, equipment functionality, and human comfort. In this study, an optimal multiple tuned mass damper (MTMD) system was proposed to mitigate the excessive vibration of a three-dimensional offshore platform under ice and earthquake loadings. The MTMD system was designed to control the first few dominant coupled modes. The optimal placement and system parameters of the MTMD are determined based on controlled modal properties. Numerical simulation results show that the proposed MTMD system can effectively reduce the displacement and acceleration responses of the offshore platform, thus improving safety and serviceability. Moreover, this study proposes an optimal design procedure for the MTMD system to determine the optimal location, moving direction, and system parameters of each unit of the tuned mass damper.

• Nuclear Engineering and Technology
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• v.56 no.5
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• pp.1913-1924
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• 2024

This paper presents the design and operation of an autonomous robot for pyroprocess automation, which requires unique approaches beyond those used in industrial applications to achieve the desired performance. Maintaining an extremely dry atmosphere is crucial to handle various materials, including chloride, and an autonomous system ensures this dry environment. The drying room dehumidifier was carefully selected and designed to generate dry air, and different types of dry air conditioning performance were evaluated, including assessing worker accessibility inside the mock-up to determine the system's feasibility. Containers used for process materials were modified to fit the gripper system of the gantry robot for automation. The loading and unloading of process materials in each equipment were automatically performed to connect the process equipment with the robotic system. The gantry robot primarily operated through macro motion to approach waypoints containing process materials, eliminating the need for precise approach motion. The robot's tapered jaw design allowed it to grasp the target object even with imperfect positioning. Robot motions were programmed using a robot simulator for initial positioning and motion planning, and real accuracy was tested in a mock-up facility using the OPC platform.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2008.10a
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• pp.378-381
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• 2008

The buckling behavior of cylindrical shape-memory alloy and aluminum tube is investigated at room temperature using a split Hopkinson pressure bar and an Instron hydraulic machine with a specially designed recording system. The shape-memory alloy at superelastic property regime buckles gradually in quasi-static loading, and fully recovers upon unloading. However, the buckling of aluminum tube is sudden and catastrophic, and shows permanent deformation. This gradual buckling of shape-memory alloy is associated with the forward and reverse transformation of stress-induced martensite and seems to have a profound effect on the unstable deformation of tube structures made from shape-memory alloy.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1926-1927
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• 2011

In this paper, an alignment method between a transporter and a stowage is presented for the automation of loading and unloading operations in the mobile harbor system. The principle of linetracer is utilized for the automatic alignment of transporter and stowage, and the effectiveness of the alignment method is proved by a simulated experiment using mobile robot.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.02a
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• pp.42-50
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• 2004

The pool $(3m{\times}6m{\times}10m{\times}$ in Irradiated Materials Examination Facility is generally used to transport irradiated materials between a moving cask and hot-cell. During the operation in the pool such as loading/unloading the cask, holding specimen and bucket elevation, water maybe contaminated by radioactive or contaminated impurities from irradiated materials. Then, it must be purified and filtered continuously to keep lower radioactivity than that of regulation prescribed by RCA Korea Activity in a part of radioactive contamination control. This paper described radioactive contamination distribution of water as transported materials, which is related to effective operation of purification and filtration system.

• Journal of the Korean Society for Railway
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• v.12 no.1
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• pp.175-182
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• 2009

Needs on ensuring compatibility and conformity of equipments that are used in logistics functions - such as packaging, transporting, loading/unloading and storing - are raised. This article presents a classification scheme for analyzing the interfacing characteristics of logistics equipments focusing on standardized pallets of unit load system. International and domestic classification systems are reviewed and analyzed; as a result several problems are issued. Methods to resolve the problems, to specify the attributes of logistics equipments and to represent the semantics among them using semantic web technology are proposed. This study could make it possible to examine the conformities of interfacing equipments automatically.