• Journal of Drive and Control
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• v.15 no.4
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• pp.39-47
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• 2018

Recently, as environmental regulations for earth-moving equipment have been tightening, advanced systems such as electronic control, have been introduced for energy savings. An IMV (Independent Metering Valve) consisting of four 2-way valves, is an electro-hydraulic control systems that provides more flexible controllability, and potential for energy savings in excavators, when compared to the conventional 4-way spool valve system. To fully maximize use of an IMV, the bi-directional flow control valve that can regulate a large amount of flow in both directions, should be adopted. The hydraulic circuit of an IMV applied to an excavator from an overseas construction equipment company, reveals the flow control valve with the compound of proportional solenoid valve for first stage, and 2-way spool valve for the second stage. Moreover, the two spools are interconnected by a feedback spring, presumed to compensate for flow force acting on the second stage spool. This paper addresses the static analysis of flow control valve in an IMV to investigate the improvement of robustness, against flow force by the feedback spring. From the steady-state analysis of flow control valve model, it can be concluded that the feedback spring facilitates maintaining linearity of spool displacement for control input, and relatively constant flow for load disturbance.

• Tribology and Lubricants
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• v.37 no.1
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• pp.1-6
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• 2021

This paper presents the experimental results of hydrophobic surfaces developed using a stereolithography-based additive-manufacturing technique. The additive manufacturing technique can be used to manufacture objects with complex geometries from computer-aided design data. Several additive manufacturing methods, such as selective laser sintering, fused deposition modeling, stereolithography apparatus (SLA), and inkjet-based system, have been developed. The SLA is a form of three-dimensional printing technology used to create prototypes, patterns, and production parts in successive layers through photochemical processes. Light causes chemical monomers and oligomers to cross-link together to form objects composed of polymers. Moreover, this method is economical for fabricating surfaces with high output resolution and quality. Here, we fabricate various surfaces using different shapes using an SLA. The surfaces with micro-patterns are fabricated for 10 cases, including the biomimetic surface. The fabricated surfaces with various micro-patterns are evaluated for hydrophobicity performance based on the static contact angle. The contact angle is measured three times for each case, and the averaged value is used. The results indicate that the arrangements in a staggered structure have a larger contact angle than those in a line when the same micro-pattern is applied. Moreover, the mimetic surfaces exhibit more hydrophobic characteristics than those of artificial micro-patterns.

• Proceedings of the ESK Conference
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• 1992.10a
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• pp.54-62
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• 1992

This work has been directed at studying and developing a prototype Computer Aided Design(CAD) tool to be used for planning tendon paths in hand reconstructive surgery. The application of CAD to rehabilitative surgery of the hand is a new field of endeavor. There are currently no existing systems designed to assist the orthopedic surgeon in planning these complex peocedures. Additionally, orthopedic surgeons are not trained in mechanics, kinematics, math modeling, or the use of computers. It was also our intent to study the mechanisms and the efficacy of the application of CAD techniques to this important aspect of hand surgery. The following advances are reported here: Interactive 3D tendon path definition tools., Software to calculate tendon excursion from an arbitrary tendon path crossing any number of joints., A model to interactively compute and display the foirces in muscle and tendon., A workstation environment to help surgeons evaluate the consequences of a simulated tendon transfer operation when a tendon is lengthened, rerouted, or reattached in a mew location., It also has been one of the primary concerns in this work that an interactive graphical surgical workstation must present a natural, user-friendly environment to the orthopedic durgeon user. The surgical workstation must ultimately aid the surgeon in helping his patient or in doing his work more efficiently or more reliably.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.4D
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• pp.413-421
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• 2010

Scheduling management is one of the most important factors for the efficient performance of construction projects. Various computer-aided solutions for schedule management have been developed, but they are not commonly used in practice. This study conducted surveys on scheduling management methods and the related solutions to identify their status and problems in practice. Based on the results of the surveys, this study also developed a scheduling assistant program to improve the usability of scheduling management solutions. Through the developed program, the usability of scheduling management solutions will be improved in practice, thus enabling efficient scheduling management.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.6
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• pp.3012-3028
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• 2017

In this paper, we propose a joint power control strategy for both the uplink and downlink transmission by considering the energy requirements of the user equipments' uplink data transmissions in data and energy integrated communication networks (DEINs). In DEINs, the base station (BS) adopts the power splitting (PS) aided simultaneous wireless information and power transfer (SWIPT) technique in the downlink (DL) transmissions, while the user equipments (UEs) carry out their own uplink (UL) transmissions by exploiting the energy harvested during the BS's DL transmissions. In our DEIN model, there are M UEs served by the BS in order to fulfil both of their DL and UL transmissions. The orthogonal frequency division multiple access (OFDMA) technique is adopted for supporting the simultaneous transmissions of multiple UEs. Furthermore, a transmission frame is divided into N time slots in the medium access control (MAC) layer. The mathematical model is established for maximizing the sum-throughput of the UEs' DL transmissions and for ensuring their fairness during a single transmission frame T, respectively. In order to achieve these goals, in each transmission frame T, we optimally allocate the BS's power for each subcarrier and the PS factor for each UE during a specific time slot. The original optimisation problems are transformed into convex forms, which can be perfectly solved by convex optimisation theories. Our numerical results compare the optimal results by conceiving the objective of maximising the sum-throughput and those by conceiving the objective of maximising the fair-throughput. Furthermore, our numerical results also reveal the inherent tradeoff between the DL and the UL transmissions.

• Journal of Ocean Engineering and Technology
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• v.22 no.5
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• pp.52-60
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• 2008

This study investigates the applicability of CADMAS-SURF (Super Roller Flume for Computer Aided Design of a MArtime Structure) code basal on the Navier-Stokes solver to predict bore phenomena. The time variation of ware levels and velocities due to the bore propagation were computed for the different bore strength conditions. In order to verify the numerical results by CADMAS-SURF, laboratory experiments were also performed, using the DPIV and LDV measuring system. The numerical results were compared to the experimental data and the analytical predictions by the NSC method basal on fully nonlinear shallow-water theory by the method of characteristics. It appears that the CADMAS-SURF slightly overestimated the water-surface level measured by the laboratory experiments and its discrepancy becomes prominent as the bore strength increases. The predicted propagation speed for a bore was also slaver than that by the experiment and NSC method. However, the temporal variations in velocities were in relatively good agreement with the experimental data for all cases, except for overshooting and undershooting in the front face of a bore, which may be derived from the numerical instability. Further, CADMAS-SURF successfully simulated the decrease in the water level and velocity caused by the effects of negative waves reflected from the upstream end wall.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.8
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• pp.689-696
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• 2001

Large-scale Multi-disciplinary Systems(LMS) such as transportation, aerospace, defense etc. are complex systems in which there are many subsystems, interfaces, functions and demanding performance requirements. Because many contractors participate in the development, it is necessary to apply methods of sharing common objectives and communicating design status effectively among all of the stakeholders. The processes and methods of systems engineering which includes system requirement analysis; functional analysis; architecting; system analysis; interface control; and system specification development provide a success-oriented disciplined approach to the project. This paper shows not only the methodology and the results of model-based systems engineering to Automated Guided Transit(AGT) system as one of LMS systems, but also propose the extension of the model-based tool to help manage a project by linking WBS (Work Breakdown Structure), work organization, and PBS (Product Breakdown Structure). In performing the model-based functional analysis, the focus was on the operation concept of an example rail system at the top-level and the propulsion/braking function, a key function of the modern automated rail system. The model-based behavior analysis approach that applies a discrete-event simulation method facilitates the system functional definition and the test and verification activities. The first application of computer-aided tool, RDD-100, in the railway industry demonstrates the capability to model product design knowledge and decisions concerning key issues such as the rationale for architecting the top-level system. The model-based product design knowledge will be essential in integrating the follow-on life-cycle phase activities. production through operation and support, over the life of the AGT system. Additionally, when a new generation train system is required, the reuse of the model-based database can increase the system design productivity and effectiveness significantly.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1075-1084
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• 2014

It is necessary to construct an equipment catalog in plant design. A different level of detail may be needed for the three-dimensional (3D) computer aided design (CAD) data for equipment, depending on the purpose. Equipment suppliers provide CAD data with high complexity, whereas plant designers need CAD data with low complexity. Therefore, it is necessary to simplify the 3D CAD assembly data. To resolve this issue, a system for automatically simplifying the 3D CAD assembly data of equipment was developed. This paper presents the architecture of the system, the detailed functions of the system, and a neutral data format used for uploading simplified 3D CAD assembly data to a plant 3D CAD system. In addition, experiment results using the prototype system are explained.

• Journal of Electrical Engineering and Technology
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• v.11 no.3
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• pp.609-617
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• 2016

Belt-driven Starter Generator (BSG) differs from other mild hybrid systems as the crankshaft of vehicle are not run off. Motor permits a low-cost method of adding mild hybrid capabilities such as start-stop, power assist, and mild levels of regenerative braking. Wound rotor synchronous motor (WRSM) could be adopted in BSG system for HEV e-Assisted application instead of the interior permanent magnet synchronous motor (IPMSM). In practice, adequate torque is indispensable for starter assist system, and energy conversion should be taken into account for the HEV or EV as well. Particularly, flux weakening control is possible to realize by adjusting both direct axis components of current and field current in WRSM. Accordingly, this paper present an off-line current acquisition algorithm that can reasonably combine the stator and field current to acquire the maximum torque, meanwhile the energy conversion is taken into consideration by losses. Besides, on account of inductance influence by non-uniform air gap around rotor, nonlinear inductances and armature flux linkage against current variation are proposed to guarantee the results closer to reality. A computer-aided method for proposed algorithm are present and results are given in form of the Look-up table (LUT). The experiment shows the validity of algorithm.

• The Journal of Advanced Prosthodontics
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• v.9 no.4
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• pp.239-243
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• 2017

PURPOSE. The purpose of this study is to compare single and three-unit metal frameworks that are produced by micro-stereolithography. MATERIALS AND METHODS. Silicone impressions of a selected molar and a premolar were used to make master abutments that were scanned into a stereolithography file. The file was processed with computer aided design software to create single and three-unit designs from which resin frameworks were created using micro-stereolithography. These resin frameworks were subjected to investment, burnout, and casting to fabricate single and three-unit metal ones that were measured under a digital microscope by using the silicone replica technique. The measurements were verified by means of the Mann-Whitney U test (${\alpha}=.05$). RESULTS. The marginal gap was $101.9{\pm}53.4{\mu}m$ for SM group and $104.3{\pm}62.9{\mu}m$ for TUM group. The measurement of non-pontics in a single metal framework was $93.6{\pm}43.9{\mu}m$, and that of non-pontics in a three-unit metal framework was $64.9{\pm}46.5{\mu}m$. The dimension of pontics in a single metal framework was $110.2{\pm}61.4{\mu}m$, and that of pontics in a three-unit metal framework was $143.7{\pm}51.8{\mu}m$. CONCLUSION. The marginal gap was smaller for the single metal framework than for the three-unit one, which requires further improvement before it can be used for clinical purposes.