• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1526-1531
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• 2008

The objective of this study is to evaluate the loading capacity of lattice girder according to loading position. 3-point flexible strength tests were performed on three types of lattice girder, such as LG-$50{\times}20{\times}30$, LG-$70{\times}20{\times}30$, and LG-$95{\times}22{\times}32$, mainly used in Korea. Two types of loading position for each flexible strength test were used to analyze the behavior of load-deformation. In 3-point flexible strength test, the difference of the average of maximum flexible strength according to loading position had the range from 10% to 33%.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.4
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• pp.371-382
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• 2008

The objective of this study is to develop the laboratory testing method for evaluating the loading capacity of lattice girder used for support in tunnel structure. 3-point flexible strength test and 4-point flexible strength test were performed on three types of lattice girder, such as $LG-50{\times}20{\times}30$, $LG-70{\times}20{\times}30$, and $LG-95{\times}22{\times}32$, mainly used in Korea. Two types of loading position for each flexible strength test were used to analyze the behavior of load-deformation. The loading distribution in the lattice girder was analyzed by means of strains measured by strain gauges attached on chords and diagonal bars. In 3-point flexible strength test, the difference of the average of maximum flexible strength according to loading position had the range from 10% to 33%. In 4-point flexible strength test, the average of maximum flexible strength according to loading position was almost no difference. The difference between the average of maximum flexible strengths obtained from 3-point and 4-point flexible strength tests was from 13.56 to 31.55%. The load applied on the lattice girder was concentrated to the main chord in 3-point flexible strength test. The load applied on the lattice girder in 4-point flexible strength test was distributed to three chords and diagonal bars.

• Journal of Korean Society of Water and Wastewater
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• v.26 no.1
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• pp.13-20
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• 2012

In this paper, we present the result of an investigation pertaining to the pipe stiffness of buried flexible pipes. Pipe stiffness (PS) formula for the parallel plate loading condition is derived based on the elasticity theory. Vertical and horizontal displacements are also derived. Vertical deflection is always larger than the horizontal deflection because some of energy due to overburden load is stored in the pipe but the difference is negligibly small. In the study, mechanical properties of the flexible pipes produced in the domestic manufacturer are tested and the results are reported in this paper. In addition, pipe stiffness is determined by the parallel plate loading tests and the finite element analysis. The difference between test and analysis is less than 14% although there are significant variations in the mechanical properties of the pipe material. Therefore, it was found that the finite element analysis can be used to predict the pipe stiffness instead of conducting parallel plate loading test.

• Journal of the Society of Disaster Information
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• v.13 no.4
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• pp.491-498
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• 2017

The primary objective of this research is to develop a rutting performance prediction model of flexible pavement. Extensive laboratory testings were conducted to achieve the objective. A new test method employing repetitive axial loading with confinement was also adopted to estimate the rutting performance of asphalt concrete in the research. The rutting prediction model employes a layer-strain theory. The required rutting coefficients for the prediction model were determined through the laboratory rutting characterizations of the asphalt concrete layer materials. Within the limits of this study, a laboratory rutting prediction model of flexible pavement using repetitive axial loading test was presented. It is noted that the developed rutting prediction model simulates propery the behaviors of flexible pavement layer materials.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.50
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• pp.127-137
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• 1999

This study is concerned with the loading problems in flexible manufacturing system(FMS). The loading problem in FMS is a complex one, when the number of machine and job is increased. It may be time-consuming and even impossible to achieve an optimal solution about this problem mathematically. Thus, a heuristic method is recommended in order to gain near-optimal solutions in a practically acceptable time. A new loading algorithm is developed with a multi-criterion objective of considering the workload unbalance, and maximizing the machine utilization, throughput for critical resources such as the number of tool slots and the number of working hours in a scheduling period and so on. The results of SAS analysis indicated that true average throughput of proposed heuristic loading statistically exceeds that of Shanker and Srinivasulus loading algorithm at the significance level of 0.1.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.2 s.257
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• pp.151-158
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• 2007

The mechanism of power transmission from motor torque to stem thrust and the operation characteristic of each stroke position are analyzed using the diagnostic signal, and effects of differential pressure on the performance of motor operated flexible wedge gate valve are investigated. Test facility consists of 76 mm motor operated valve(flexible wedge type), pump and pipe system. Static and dynamic test are performed separately, and two differential pressure conditions are applied in the dynamic test. To evaluate the performance of valve, test signals for the torque, thrust, current, voltage and stroke length are acquired by using UDS which is diagnosis device for motor operated valve, and each diagnostic signal is analyzed and compared. The characteristic of valve performance factors such as stem factor, rate of loading, valve factor, are evaluated, and these factors are found to be severely influenced by the fluid differential pressure.

• Structural Engineering and Mechanics
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• v.6 no.7
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• pp.817-826
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• 1998

A finite element model based on the incremental endochronic theory for flexible pavement materials was developed in this study. Three grid systems with eight-node cubic isoparametric elements, and different loading steps were used to perform the calculations for a specimen of circular cylinder. The uniaxial stress experimental results on an asphalt mixture at $60^{\circ}C$ in SHRP conducted by University of California at Berkeley were used to check the ability of the derived numerical model. Then, the numerical results showed isotropic response and deviatoric response on the specimen in a three dimensional manner, which provided a better understanding for a deformed flexible material under the specified loading conditions.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.1
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• pp.119-135
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• 1995

We consider problems of tool loading and scheduling in a flexible manufacturing system (FMS) in which tool transportation constitutes the major portion of material flows. In this type of FMSs, parts are initially assigned to machines and released to the machines according to input sequencing rules. Operations for the parts released to the machines are performed by tools initially loaded onto the machines or provided by an automatic tool transport robot when needed. For an efficient operation of such systems, therefore, we may have to consider loading and scheduling problems for tools in addition to those for parts. In this paper, we consider three problems, part loading, tool loading, and tool scheduling problems with the overall objective of minimizing the makespan. The part loading problem is solved by a method similar to that for the bin packing problem and then a heuristic based on the frequency of tool usage is applied for tool loading. Also suggested are part input sequencing and tool scheduling rules. To show the effectiveness of the overall algorithm suggested here, we compare it with an existing algorithm through a series of computational tests on randomly generated test problems.

• Journal of Korean Institute of Industrial Engineers
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• v.19 no.4
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• pp.41-48
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• 1993

Prime advantage of flexible manufacturing systems(FMS) is a flexibility. Flexibility is expected to prolong the service life of a manufacturing facility and enable it to respond quickly and economically to dynamic market change. The FMS loading decision is concerned with the allocation of operations and tools to machines subject to technological and capacity constraints of the system. Modern FMS loading problem has the multiple objectives such as processing cost, time and work load balance. We propose multi-objectives which could be used to formulate the loading/routeing problem and sequencing decision which should be adopted for each part type in order to maximize the machine flexibility by Hamming distance matrix based on Incidance matrix. Finally, a numerical example is provided to illustrate the proposed model.

• Journal of Korean Institute of Industrial Engineers
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• v.15 no.1
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• pp.65-75
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• 1989

This study complements the previous studies on workload distribution problems in Flexible Manufacturing Systems. Specifically, we consider the problem in two perspectives, the long-range policy and the short and medium-term planning and control. The long-term loading policy focusses on identifying the optimal loading of the system characterized by either balanced loading or unique unbalanced loading for which a steepest ascent method is developed. These results are then applied to study the optimal medium and short-term planning and control problems, for which a truncated dynamic programming method is developed in order to obtain the optimal allocation of the given operation mix of part types to work stations.