• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.4
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• pp.1154-1163
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• 1996

This paper presents a three dimensional modeling and dynamic anlaysis of a hydraulic excavator. An excavator is composed of a ground, an under-frame, two idlers, two spockets, an upper-frame, a boom, an arm, a bucket two yokes, two connecting rods, two boom cylinders, an arm cylinder, and a bucket cylinder. Each cylinder is modeled with two separate bodies which are linked to each other by a translational joint. The three dimensioanl model of the excavator consists of 22 bodies and each body is assumed as rigid. This paper suggested the maximum lifting capability, a critical load and reaction forces at joints form the DADS simulation. It was presumed that the reaction forces due to a critical load are three times bigger than those due to the maximum lifting capacity.

• Journal of Navigation and Port Research
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• v.38 no.5
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• pp.493-501
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• 2014

An automated lifting vehicle(ALV) used in an automated container terminal is a type of unmanned vehicle that can self-lift a container as well as self-transport it to a destination. To operate a fleet of ALVs efficiently, one needs to be able to determine a minimum-time route to a given destination whenever an ALV is to start its transport job. To find a route free from any collision or deadlock, the occupation time of the ALV on each segment of the route should be carefully scheduled to avoid any such hazard. However, it is not easy because not only the travel times of ALVs are uncertain due to traffic condition but also the operation times of cranes en route are not predicted precisely. In this paper, we propose a routing method based on an ant colony optimization algorithm that takes into account these uncertainties. The result of simulation experiment shows that the proposed method can effectively find good routes under uncertainty.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.16 no.1
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• pp.92-97
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• 2007

This study was carried out to minimize the lifting force and to design the slim sized frame of a height adjustment mechanism. This unit is designed for the display devices in order to enhance the ergonomics for effective height adjustment as well as to achieve much slimmer frame for the pedestal. A tolerance analysis of 6 sigma was applied to achieve smooth lift at design stage not to change the tolerance specification of gap several times in a roller type of lifting mechanism at mass production stage. The specification of minimum gap and the target of production yield ratio were agreed with a quality team before tooling. A DFSS simulation on drawings had been done with reasonable tolerance and achievable standard deviation(${\sigma}$) several times until the target specification of gap and yield ratio was met. Once tolerance and deviation(${\sigma}$) were fixed tooling start was done successfully. A CAE method was applied to achieve a slim design. Design parameters were frozen when those parameters matched the reference strength data of standard model. Through those tolerance analysis and CAE simulation the number of tool modification was reduced and production yield ratio was raised up without arguing quality specification at production stage in the end.

• Proceedings of the KSME Conference
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• 2000.04a
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• pp.714-719
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• 2000

In this paper, an application program is made to simulate the behavior of a ship block under various crane works and to generate data of lu9 reactions and wire tensions. The program is based on a CAD program, Pro/ENGINEER. A ship is composed of more than 100 ship blocks. In order to lift, move, turn, or put a ship block at a convenient location fur assembling, workers in a shipyard use cranes, wires, and lugs temporarily attached to the block. In the procedure of lifting and turning a ship block with a crane, it is important to find suitable lug points and wires to do the handling efficiently and prevent accidents. Evaluation of forces in lugs and wires is necessary, but the problem is rather complex due to nonlinearity and nonuniqueness. In the present development, the nonlinear system of equations for quasi-static equilibriums is derived and a Newton type solution method is adopted to solve the system. The importance of initial estimates to the solution is illustrated and two approaches are utilized and compared. With the program developed, users can assign lug points on the CAD model by mouse and choose various linking devices at each crane point. Users can try to simulate the motion for any prescribed conditions, compare the motion of the block and the reactions and choose appropriate lug points and the type of wires and lugs.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1687-1689
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• 1998

In this work, the behaviours of conducting wire type particles within the coaxial electrode gap energized with high ac voltage have been systematically investigated using charge simulation method. For this, spheroidal charge is adopted as a image charge for the CSM analysis in order to calculate the acquired charge of the particles which are erected on the surface of the outer electrode. For this purpose, the effects of the lengths and diameters of Cu, Al particles in gas insulated system have been studied by a numerical computation and particle lifting voltage, lifting field, breakdown voltage, acquired charge and travelling distance have been considered. From this, we understand that the particle behaviours have different characteristics according to the particle lengths and diameters. And a possible countermeasure, based on the proposed simulation, has been provided with a view to estimating the flashover voltage of $SF_6$ gas under the 1 atm.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.628-633
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• 2008

Tall building construction has been increasing due to the need to maximize land usage. It causes the increase of vertical transportation for workers and materials, which significantly affects the productivity and lifting planning, therefore, has to be made carefully based on the characteristics of the field. However, the existing method to calculate the number of lift is too simple to consider complex and various characteristics in tall building construction. Accordingly, we developed the model for selecting the best system of vertical transportation by using Queueing theory. To find out the situation of the queue of resources such as material and workers, a simulation program will be applied.

• Journal of Korea Multimedia Society
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• v.15 no.1
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• pp.81-86
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• 2012

This paper presents a VLSI design for lifting-based discrete wavelet transform (DWT) 9/7 filter using multiplierless multiple constant multiplication (MCM) architecture. This proposed design is based on the lifting scheme using pattern search for folded architecture. Shift-add operation is adopted to optimize the multiplication process. The conventional serial operations of the lifting data flow can be optimized into parallel ones by employing paralleling and pipelining techniques. This optimized design has simple hardware architecture and requires less computation without performance degradation. Furthermore, hardware utilization reaches 100%, and the number of registers required is significantly reduced. To compare our work with previous methods, we implemented the architecture using Verilog HDL. We also executed simulation based on the logic synthesis using $0.18{\mu}m$ CMOS standard cells. The proposed architecture shows hardware reduction of up to 60.1% and 44.1% respectively at 200 MHz clock compared to previous works. This implementation results indicate that the proposed design performs efficiently in hardware cost, area, and power consumption.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.1
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• pp.27-33
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• 2017

An agriculture machines are subjected to different loads conditions. Due to this loads variations there will be certain deformations and stress which affect the performance of the electric vehicle in adverse manner. The purpose of this paper is to analyze the total deformation and stress of the electric farm vehicle middle frame based on the finite element method. The proposed electric farm vehicle has lifting and dumping capability. Therefore, in this research four operational condition such as normal condition, dumping condition, lifting condition, and lifting-dumping condition was analyzed. In this research, the design for whole frame structure is elaborated. According to the mechanical characteristics of the frame, materials are selected and manufacturability requirements are limited. Based on ANSYS 15 software, the finite element model of electric farm vehicle is established to carry out static analysis on full-loaded conditions. The simulation results shows that the proposed design meet the strength requirements and displacement requirements. The maximum deformation 0.53611 mm and maximum stress 30.163 MPa occurred at lifting-dumping condition.

• International Journal of Aeronautical and Space Sciences
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• v.1 no.1
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• pp.29-35
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• 2000

A numerical method to simulate Wing-In-Ground(WIG) effects for the wings moving near ground is developed. The aerodynamic analysis scheme for the wings is based on a compressible non-planar lifting surface panel method and the WIG effect is included by images. The thickness-induced effect is implemented into the lifting surface panel method by using the teardrop theory. The numerical simulation is done for the rectangular wings by varying the ground proximity. The present method is validated by comparing the calculated aerodynamic coefficients with other numerical results and measured data, showing good agreements.

• Special Issue of the Society of Naval Architects of Korea
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• 2009.09a
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• pp.107-114
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• 2009

In the recent large block are used to build the ship to improve productivity. For this reason, two or more floating cranes that are connected in parallel is the trend. Typically, when working with floating crane load safety factor is considered. Even in the parallel operation, load safety factor is calculated similar to working alone. For this reason, operations do not guarantee the reliability or excessive safety factor applied. Therefore, the subdivided cases for calculating the safety factor are defined when parallel connected floating cranes are operated. Based on those cases, the operation standard is made about procedure using parallel connected floating cranes. And to verify this, dynamics simulation was performed for verification using the dynamics simulation program.