• Proceedings of the KIEE Conference
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• 1994.11a
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• pp.33-35
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• 1994

This Paper Presents a practical approach to evaluate the reliability indices of electric distribution systems. The use of reliability evaluation is placed with the framework of distribution system planning. In this paper, the reliability model is based on an analytical method, connecting component failure to load point outage each section. five case studies are reported in the paper. These are to study the effect of varying failure rates and repair times on distribution feeders. The results of a study on sample system are presented in this paper.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.53 no.4
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• pp.309-316
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• 2017

In this paper, numerical modeling is conducted to analyze the tension of an anchor line by varying the size and drag coefficient of a buoy when the trapnet is influenced by the wave and the current simultaneously. A mass-spring model was used to analyze the behavior of trapnet underwater under the influence of waves and current. In the simulation of numerical model, wave height of 3, 4, 5 and 6 m, a period of 4.4 s, and the flow speed of 0.7 m/s were used for the wave and current condition. The drag coefficients of buoy were 0.8, 0.4 and 0.2, respectively. The size of buoy was 100, 50 and 25% based on the cylindrical buoy ($0.0311m^3$) used for swimming crab trap. The drag coefficient of the trapnet, the main model for numerical analysis, was obtained by a circular water channel experiment using a 6-component load cell. As a result of the simulation, the tension of the anchor line decreased proportional to buoy's drag coefficient and size; the higher the wave height, the greater the decrease rate of the tension. When the buoy drag coefficient and size decreased to one fourth, the tension of the anchor line decreased to a half and the tension of the anchor line was lower than the holding power of the anchor even at 6 m of wave height. Therefore, reducing the buoy drag coefficient and size appropriately reduces the trapnet load from the wave, which also reduces the possibility of trapnet loss.

• Journal of the Korea Society for Simulation
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• v.25 no.4
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• pp.53-63
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• 2016

This study aims to verify the feasibility of design by developing pressure flow-controlled swash plate type pump with the use of SimulationX, a computer analysis program. Developing analysis model based on design drawing data has a cost-saving effect because it is possible to figure out the effectiveness of design through the work and it never falls into repeated inaccuracies in the production process. Analysis model is developed in the following order. First, the structure of each part such as valve and rotating unit which have dynamic factor is analyzed and the modeling of single component is carried out, reflecting drawing data. Second, the modeling of pump assembly is carried out with the combination of each analysis model and a work is conducted to determine whether the modeling can perform pressure flow control function according to load condition smoothly based on design intent. At the end of the modeling process, the feasibility of design is verified by showing the parts which are moving as expected mechanism.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.18 no.6
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• pp.642-651
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• 2009

The history of excavator design is not long enough which still causes most of the design considerations to be focused on static analysis or simple functional improvement based on static analysis. However, the real forces experiencing on each component of excavator are highly transient and impulsive. Therefore, the prediction and the evaluation of the movement of the excavator by dynamic load in the early design stage through the dynamic transient analysis of the excavator and ensuring of design technique plays an importance role to reduce development-cost, shorten product-deliver, decrease vehicle-weight and optimize the system design. In this paper, Commercial software DADS and ANSYS help to develop the track model of the crawler type excavator, and to evaluate the performance and the dynamic characteristics of excavator with various simulations. For that reason, the track of crawler type excavator is modelled with DADS Track Vehicle Superelement, and the reaction forces on the track rollers were predicted through the driving simulation. Also, the upper frame and cabin vibration characteristics, at the low RPM idle state, were evaluated with engine rigid body modelling. And flexibility body effects were considered to determine the more accurate joint reaction forces and accelerations under the upper frame swing motion.

• Journal of KIISE:Software and Applications
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• v.30 no.5_6
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• pp.529-539
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• 2003

Due to the emersion of J2EE (Java 2, Enterprise Edition), many enterprises inside and outside of the country have been developing the enterprise applications appropriate to the J2EE model. With the help of the component model of Enterprise JavaBeans (EJB) which is the J2EE core technology, we can develop the distributed object applications quite simple. EJB application can be implemented by using the component-oriented object transaction middleware and the most applications utilize the distributed transaction. Due to these characteristics, EJB technology became popular and then the study for EJB based application has been done quite actively. However, the research of techniques for the performance monitoring during run-time of the EJB applications has not been done enough. In this paper, we propose the techniques for monitoring the performance of EJB Application on the run time. First, we explore the workflow for the EJB application service and classily the internal operation into several elements. The proposed techniques provide monitoring the performance elements between the classified elements. We can also monitor by extracting the performance information like state transition and process time of the bean which is related to the lifetime occurred during one workflow, and the resource utilization rate.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.10
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• pp.5176-5183
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• 2013

In general, Korean Lightweight Concrete used Heat insulating material for building and filler for civil construction, backfill material for tunnel, office floor fillers, lightweight blocks and so on. These expand the range of use ALC(autoclaved lightweight concrete) on the soft-ground at regular intervals during road construction by installing piles used as substrates for the process is under study. In this study, behavior characteristics on the soft-ground of pavement analysis was used to test the geo-Centrifuge. Prototype pavement reduced to 1/30 slab form of the composition as kaolinite model tests were conducted in the soft ground. Pile Arrangement (having 36 component pile with an array of $3{\times}12$) was used to group of piles. Tests of gravity 30 level the centrifugal force acting Light-weight pavement models. Based on the Prototype pavement of the behavior characteristics of pavement behavior characteristics were estimated. FMA analysis of the 10 times as big 39.4kg (actual load 35 ton) of the lateral load is applied to the case 7.8mm (actual behavior 23.4mm) behavior was fine.

• Computers and Concrete
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• v.30 no.5
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• pp.311-321
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• 2022

The interfacial bond strength of partially encased composite (PEC) structure tends to 0, therefore, the cast-in-place concrete theoretically cannot embody better composite effect than the fabricated structure. A total of 12 specimens were designed and experimented to investigate the energy dissipation and damage of fabricated PEC beam through unidirectional cyclic loading test. Because the concrete on both sides of the web was relatively independent, some specimens showed obvious asymmetric concrete damage, which led to specimens bearing torsion effect at the later stage of loading. Based on the concept of the ideal elastoplastic model of uniaxial tensile steel and the principle of equivalent energy dissipation, the energy dissipation ductility coefficient is proposed, which can simultaneously reflect the deformability and bearing capacity. In view of the whole deformation of the beam, the calculation formula of energy dissipation is put forward, and the energy dissipation and its proportion of shear-bending region and pure bending region are calculated respectively. The energy dissipation efficiency of the pure bending region is significantly higher than that of the shear-bending region. The setting of the screw arbors is conducive to improving the energy dissipation capacity of the specimens. Under the condition of setting the screw arbors and meeting the reasonable shear span ratio, reducing the concrete pouring thickness can lighten the deadweight of the component and improve the comprehensive benefit, and will not have an adverse impact on the energy dissipation capacity of the beam. A damage model is proposed to quantify the damage changes of PEC beams under cyclic load, which can accurately reflect the load damage and deformation damage.

• Korean Journal of Agricultural Science
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• v.50 no.4
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• pp.773-784
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• 2023

In this study, we developed a dynamic model and steering controller model for an autonomous tractor and evaluated their performance. The traction force was measured using a 6-component load cell, and the rotational speed of the wheels was monitored using proximity sensors installed on the axles. Torque sensors were employed to measure the axle torque. The PI (proportional integral) controller's coefficients were determined using the trial-error method. The coefficient of the P varied in the range of 0.1 - 0.5 and the I coefficient was determined in 3 increments of 0.01, 0.05, and 0.1. To validate the simulation model, we conducted RMS (root mean square) comparisons between the measured data of axle torque and the simulation results. The performance of the steering controller model was evaluated by analyzing the damping ratio calculated with the first and second overshoots. The average front and rear axle torque ranged from 3.29 - 3.44 and 6.98 - 7.41 kNm, respectively. The average rotational speed of the wheel ranged from 29.21 - 30.55 rpm at the front, and from 21.46 - 21.63 rpm at the rear. The steering controller model exhibited the most stable control performance when the coefficients of P and I were set at 0.5 and 0.01, respectively. The RMS analysis of the axle torque results indicated that the left and right wheel errors were approximately 1.52% and 2.61% (at front) and 7.45% and 7.28% (at rear), respectively.

• Journal of Power Electronics
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• v.18 no.3
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• pp.802-816
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• 2018

A digital direct phase-shift control (DDPSC) method based on the phase-shifted full-bridge LLC (PSFB-LLC) converter is presented. This work combines DDPSC with the conventional linear control to obtain a hybrid control strategy that has the advantages of linear control and DDPSC control. The strategy is easy to realize and has good dynamic responses. The PSFB-LLC circuit structure is simple and works in the fixed frequency mode, which is beneficial to magnetic component design; it can realize the ZVS of the switch and the ZCS of the rectifier diode in a wide load range. In this work, the PSFB-LLC converter resonator is analyzed in detail, and the concrete realization scheme of the hybrid control strategy is provided by analyzing the state-plane trajectory and the time-domain model. Finally, a 3 kW prototype is developed, and the feasibility and effectiveness of the DDPSC controller and the hybrid strategy are verified by experimental results.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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• v.4B no.3
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• pp.146-152
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• 2004

Cost effective simulation schemes for Wind Power Generation Systems (WPGS) considering wind turbine types, generators and load capacities have been strongly investigated by researchers. As an alternative, a true weather condition based simulation method using a real-time digital simulator (RTDS) is experimented in this paper for the online real-time simulation of the WPGS. A stand-alone WPGS is, especially, simulated using the Simulation method for WPGS using Real Weather conditions (SWRW) in this work. The characteristic equation of a wind turbine is implemented in the RTDS and a RTDS model component that can be used to represent any type of wind turbine in the simulations is also established. The actual data related to weather conditions are interfaced directly to the RTDS for the purpose of online real-time simulation of the stand-alone WPGS. The outcomes of the simulation demonstrate the effectiveness of the proposed simulation scheme. The results also signify that the cost effective verification of efficiency and stability for the WPGS is possible by the proposed real-time simulation method.