• Journal of the Korean GEO-environmental Society
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• v.16 no.10
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• pp.5-14
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• 2015

Suction affects the unsaturated soil as the negative pore pressure, and leads to increases of the yield stress and the plastic shear stiffness of the soil skeleton due to the growth in interparticle stress. Hence, in this study, in order to account for these effects of suction under the dynamic loading condition such as the earthquake, the element simulation of the cyclic triaxial test using induced stress-strain relation based on cyclic elasto-plastic constitutive model extended for unsaturated soil considering the $1^{st}$ and the $2^{nd}$ yield functions was conducted. Through the stress path, stress-strain relation and relation between volumetric strain and axial strain, it was seen in all the cases that the simulation results demonstrated a good agreement with the experimental results. It is expected that the results of this study possibly contribute to the accuracy improvement on the prediction of unsaturated soil behavior under the dynamic loading condition.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.377-382
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• 2001

Mechanical behavior and electrical resistance change of CPDP (carbon particle dispersed plastic) composite consisting of epoxy resin and conductive carbon particle were investigated under monotonic loading and repeated loading-unloading. The electrical resistance almost linearly increased with increasing strain during loading and the residual electrical resistance was observed even after removing load. The value of the residual electrical resistance was dependent on the maximum strain under the applied stress. This result suggests that the estimation of maximum strain (i.e., damage) is possible by the measuring electrical resistance of composite. The behavior of electrical resistance change during and after loading was discussed on the basis of the results of microscopic deformation and fracture observation. Moreover, the relationship between the volume fraction of carbon particle and the electrical resistivity of CPDP was investigated in relation to the percolation theory. Simulation model of percolation structure was established by Monte Carlo method and the simulation result was compared to the experimental results. The electrical resistance change under applied loading was analyzed quantitatively using the percolation equation and a simple model for the critical volume fraction of carbon particle as a function of the mechanical stress. It was revealed that the prediction was in good agreement with the experimental result except in the region near the failure of material.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.74-80
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• 2021

When a berth is built close to a fairway, a moored vessel will be affected by the ship waves generated by navigating vessels. In this study, a portable measurement system was developed to measure the roll motion of an actual vessel, and the results were compared with simulation results. The simulation results showed that the roll motion satisfies the loading safety criteria. However, the actual results of the vessel, did not satisfy the criteria in some cases. In this study, 18 cases that did not satisfy the loading safety criteria were analyzed. Among these cases, three cases were affected by a different time zone of the remaining 15 cases, 11 cases (73.3%) were observed to be consistent with arrival times of passenger ships of more than 10,000GT sailing between in Mokpo and Jeju. The results of this study can be used to reflect marine traffic characteristics in the assessment of loading safety, which can increase the reliability of results of the loading safety assessment of ships.

• Steel and Composite Structures
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• v.46 no.1
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• pp.53-73
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• 2023

Man-made structure materials like concrete usually contain inclusions. These inclusions affect the mechanical properties of concrete. In this investigation, the influence of inclusion length and inclination angle on three-dimensional failure mechanism of concrete under uniaxial compression were performed using experimental test and numerical simulation. Approach of acoustic emission were jointly used to analyze the damage and fracture process. Besides, by combining the stress-strain behavior, quantitative determination of the thresholds of crack stress were done. concrete specimens with dimensions of 120 mm × 150 mm × 100 mm were provided. One and two holes filled by gypsum are incorporated in concrete samples. To build the inclusion, firstly cylinder steel tube was pre-inserting into the concrete and removing them after the initial hardening of the specimen. Secondly, the gypsum was poured into the holes. Tensile strengths of concrete and gypsum were 2.45 MPa and 1.5 MPa, respectively. The angle bertween inclusions and axial loadind ary from 0 to 90 with increases of 30. The length of inclusion vary from 25 mm to 100 mm with increases of 25 mm. Diameter of the hole was 20 mm. Entirely 20 various models were examined under uniaxial test. Simultaneous with experimental tests, numerical simulation (Particle flow code in two dimension) were carried out on the numerical models containing the inclusions. The numerical model were calibrated firstly by experimental outputs and then failure behavior of models containing inclusions have been investigated. The angle bertween inclusions and axial loadind vary from 0 to 90 with increases of 15. The length of inclusion vary from 25 mm to 100 mm with increases of 25 mm. Entirely 32 various models were examined under uniaxial test. Loading rate was 0.05 mm/sec. The results indicated that when inclusion has occupied 100% of sample thickness, two tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. When inclusion has occupied 75% of sample thickness, four tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. When inclusions have occupied 50% and 25% of sample thickness, four tensile cracks originated from boundaries of sample and spread parallel to the loading direction until being integrated together. Also the inclusion was failed by one tensile crack. The compressive strength of samples decease with the decreases of the inclusions length, and inclusion angle had some effects on that. Failure of concrete is mostly due to the tensile crack. The behavior of crack, was affected by the inclusion length and inclusion number.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.405-408
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• 1998

Generally, the principle function of simulator control loading system is to provide the pilot or student with the "feel" of the actual aircraft flight control systems during flight, taxing, and in malfunction. Flight control "feel" is the resistance felt by the pilot when moving a control stick or pedal, coupled with the amount of control surface deflection, and hence aircraft response, resulting from the input. Therefore, the control loading servo must be capable of performing to some general list of requirements derived from real aircraft control forces. In this paper, we deal with a $\mu-controller$ design for a control loading system of the flight simulator. For this, we derive a frequency response of the hydraulic system from the identification data and then design a controller using a $\mu-synthesis$ method. Under the same condition of simulation, $\mu-controller$ provides the superior performance than PID controller.than PID controller.

• Journal of electromagnetic engineering and science
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• v.10 no.2
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• pp.50-55
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• 2010

Orthogonal Frequency Division Multiplexing(OFDM) dual-hop systems can take full advantages of the techniques of both multi-hop communication and OFDM. To achievethis end, we propose a joint subcarrier matching, power allocation and bit loading algorithm operating under a total power constraint and the same Bit Error Rate(BER) threshold over all subcarriers. Simulation results demonstrated system throughput improvement compared to single-hop systems and dual-hop systems with different bit loading algorithms for each relay position, power constraint, and required BER.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.1
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• pp.95-101
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• 2006

Minimum weight design of laminated composite panel under combined loading was studied using linear and nonlinear deformation theories and by closed-form analysis and finite difference energy methods. Various buckling load factors are obatined for laminated composite panels with rectangular type longitudinal stiffeners and various longitudinal length to radius ratios, which are made from Carbon/Epoxy USNl25 prepreg and are simply-supported on four edges under combined loading, and then for them, minimum weight design analyses are carried out by the nonlinear search optimizer, ADS. This minimum weight design analyses are constructed with various process such as the simple design process, test simulation process and sensitivity analysis. Subseguently, the buckling mode shapes are obtained by buckling and minimum weight analyses.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.5
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• pp.106-115
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• 2002

The objective of this study was to evaluate the GLEAMS-PADDY model by applying it to estimate nutrients loading from paddy-field areas. Field data from Soro region of Chungbuk province during May to September 1999 were used for model application. Field data collected include the amounts of rainfall, irrigation water, drainage water, ET, and Percolation in hydrology Part. T-N and T-P concentrations in the rain water, irrigation water, ponded water, drainage water and percolated water were measured. The comparisons of observed and simulated water balance components and nutrient concentrations showed reasonably good agreements and the GLEAMS-PADDY model may be used to simulate nutrients loading from paddy fields. Futher research was suggested to include the erosion submodel in the GLEAMS-PADDY model to better simulate the nutrient behavior. In addition, the pesticide submodel also recommended to be included in order to simulate the various pesticide applied in paddy fields.

• Proceedings of the KSRS Conference
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• v.1
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• pp.263-266
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• 2006

Now, on the developing COMS(Communication, Ocean and Meteorological Satellite) has solar panel on the South panel only. Therefore, the wheel off-loading has to be performed periodically to reduce a induced momentum energy by a asymmetric solar panel. One of two East/West station keeping maneuver to correct simultaneously longitude and eccentricity, orbit corrections may be performed during one of the two wheel off-loading manoeuvres per day to get enough observation time for meteorological and ocean sensor. In this paper, we applied a linearized orbit maneuver equation to acquire maneuver time and delta-V. Nonlinear simulation for the station keeping is performed and compared with general station keeping strategy for fuel reduction.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.37
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• pp.201-210
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• 1996

Although FMS implementation in Korea is not yet mature, the worldwide empirical data shows the diffusion of FMS is inevitable in near future. As the reletionships between the high capital cost and the relative benefits and advantages are complex to analyse, it is rather beneficial to prepare the effective operation strategies which exploit the FMS flexibility, such as machine loading with alternative routing and dispatching rules. This paper shows the formulation applying a goal programming model for the loading problem with objectives of minimizing the production cost and maximizing the machine utilization, including constraints such as machine tool capacity and demands, etc. A realistic random FMS model is developed for illustration. Since loading and dispatching are a composite of two interdependent tasks, simulation is made to investigate the interactions between the two.