• Journal of information and communication convergence engineering
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• v.18 no.4
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• pp.245-253
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• 2020

The human body and nervous system transmit information through electric charges. After the electric charge transmits information to the brain, we can feel pain, numbness, comfort, and other feelings. Electric therapy is currently used widely in clinical practice because the field of examination is more representative of electrocardiogram, and in the field of treatment is more representative of electrotherapy. In this study, we design a system for neurophysiological therapy and conduct parameter calculation and model selection for the components of the system. The system is based on a discontinuous conduction mode (DCM) boost circuit, and controlled and regulated by a single-chip microcomputer. The system does not only have a low cost but also fully considers the safety of use, convenience of the human-computer interface, adjustment sensitivity, and waveform diversity in the design. In future, it will have strong implications in the field of electrotherapy.

• Asian Journal of Innovation and Policy
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• v.12 no.2
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• pp.200-215
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• 2023

The purpose of this paper is to analyze the Korean government's investment priorities for the establishment of a supercomputer joint utilization system using AHP. The AHP model was designed as a two-layered structure consisting of two areas of specialized infrastructure, a one-stop joint utilization system service, and four evaluation items for detailed tasks. For the weight of each evaluation item, a cost efficiency index considering the annual budget was developed for the first time and applied to the weight calculation process. AHP analysis conducted a survey targeting supercomputer experts and derived priorities with 22 data that had completed reliability verification. As a result of the analysis, the government's investment priority was high in the order of dividing infrastructure for each Specialized Center and building resources in stages. In the future, the analysis results will be used to select economic promotion plans and prepare strategies for the establishment of the government's supercomputer joint utilization system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.1
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• pp.57-65
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• 2007

Along with the development of power electronics and magnetic materials, permanent magnet (PM) brushless direct current (BLDC) motors are now widely used in many fields of modern industry BLDC motors have many advantages such as high efficiency, large peak torque, easy control of speed, and reliable working characteristics. However, Compared with the other electric motors without a PM, BLDC motors with a PM have inherent cogging torque. It is often a principle source of vibration, noise and difficulty of control in BLDC motors. Cogging torque which is produced by the interaction of the rotor magnetic flux and angular variation in the stator magnetic reluctance can be reduced by sinusoidal air-gap flux density waveform due to reduction of variation of magnetic reluctance. Therefore, this paper will present a design method of magnetizing system for reduction of cogging torque and low manufacturing cost of BLDC motor with isotropic bonded neodynium-iron-boron (Nd-Fe-B) magnets in ring type by sinusoidal air-gap flux density distribution. An analytical technique of magnetization makes use of two-dimensional finite element method (2-D FEM) and Preisach model that expresses the hysteresis phenomenon of magnetic materials in order for accurate calculation. In addition, For optimum design of magnetizing fixture, Factorial design which is one of the design of experiments (DOE) is used.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.2526-2531
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• 2005

A practical pinch torque estimator based on the Kalman filter is proposed for low-cost anti-pinch window control systems. To obtain the accurate angular velocity from Hall-effect sensor measurements, the angular velocity calculation algorithm is executed with additional procedures for removing the measurement noises. Apart from the previous works using the angular velocity estimates and torque estimates for detecting the pinched condition, the torque rate is augmented to the system model and the proposed pinch estimator is derived by applying the steady-state Kalman filter recursion to the model. The motivation of this approach comes from the idea that the bias errors in torque estimates due to the motor parameter uncertainties can be almost eliminated by introducing the torque rate state. For detecting the pinched condition, a systematic way to determine the threshold level of the torque rate estimates is also suggested via the deterministic estimation error analysis. Simulation results are given to certify the pinch detection performance of the proposed algorithm and its robustness against the motor parameter uncertainties.

• Journal of KIBIM
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• v.7 no.2
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• pp.8-15
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• 2017

Building Information modeling is playing an important role in transforming the construction industry. It helped the industry with better visualization, minimum design errors, and excellent planning of the construction activities. Time and cost saving can be effectively achieved by using BIM for any construction project. It improves information exchange between all the project stakeholders. However, the development of earthwork 3D BIM is still underway and has not been fully implemented yet. This paper presents the study of a complete process for Earthwork BIM design using Autodesk Civil 3D. A real site road construction project is used as a case study to explain the process of earthwork modeling, starting from laser scanning to 3D model. Quantity take off calculation is very important part of any road construction project so during this study earthwork volume from two 3D earthwork model is calculated. The results obtained through this study will be the basis for future work which has been concluded in this paper.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.430-433
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• 2001

When the vector control, which does not need a speed signal from a mechanical speed sensor, it is possible to reduce the cost of the control equipment and to improve the control performance in many industrial application. This paper describes a rotor speed identification method of induction motor based on the theory of flux model reference adaptive system. The estimator execute the rotor speed identification so that the vector control of the induction motor may be achieved. The improved auxiliary variable of the two model are introduced In perform accurate rotor speed estimation. The control system is composed of the PI controller for speed control and current controller using space voltage vector PWM technique. High speed calculation and processing for vector control is carried out by TMS320C31 digital signal processor. Validity of the proposed control method is verified through simulation and experimental result.

• Journal of KIBIM
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• v.11 no.3
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• pp.55-66
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• 2021

Recently, Building Information Modeling(BIM) has become a hot topic in the construction industry such as quantity calculation, interference check, process management, and construction cost management. It is also trying to convert the existing 2D design to 3D design and introduce the BIM in various fields, thus, many new deliverable are being presented but there are many issues due to the lack of standard guides on the preparation and delivery criteria for such new deliverable and how to utilize performance data. Therefore, In order to develop the electronic delivery process, we analyzed the process related to the delivery of BIM digital models presented in domestic and international BIM guidelines and the delivery of products from the Korea National Railway. The analysis focused on the list of achievements, delivery process, quality review standards, and the utilization code system of the Korea National Railway through BIM guidelines and the National Railroad Service's business procedures. Based on these analysis results, it presents a plan to construct an functional module of electronic delivery.

• Journal of Power Electronics
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• v.19 no.1
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• pp.244-253
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• 2019

Finite control set model-predictive control (FCS-MPC) has received increasing attentions due to its outstanding dynamic performance. It is being widely used in power converters and multilevel inverters. However, FCS-MPC requires a lot of calculations, especially for multilevel-cascaded H-bridge (CHB) static synchronous compensators (STATCOMs), since it has to take account of all the feasible voltage vectors of inverters. Hence, an improved five-segment space vector pulse width modulation (SVPWM) method based on the non-orthogonal static reference frames is proposed. The proposed SVPWM method has a lower number of switching states and requires fewer computations than the conventional method. As a result, it makes FCS-MPC more efficient for multilevel cascaded H-bridge STATCOMs. The partial cost function is adopted to sequentially solve for the reference current and capacitor voltage. The proposed FCS-MPC method can reduce the calculation burden of the FCS-MPC strategy, and reduce both the switching frequency and power losses. Simulation and experimental results validate the excellent performance of the proposed method when compared with the conventional approach.

• Structural Engineering and Mechanics
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• v.78 no.5
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• pp.519-528
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• 2021

One of the most efficient designs of solar trackers for photovoltaic panels is the single-axis tracker, which holds the panels along a torque tube that is driven by a motor at the central section. These trackers have evolved to become extremely slender structures due to mechanical optimization against static load and the need of cost reduction in a very competitive market. Owing to the corresponding decrease in mechanical resistance, some of these trackers have suffered aeroelastic instability even at moderate wind speeds, leading to catastrophic failures. In the present work, an analytical and experimental approach has been developed to study that phenomenon. The analytical study has led to identify the dimensionless parameters that govern the motion of the panel-tracker structure. Also, systematic wind tunnel experiments have been carried out on a 3D aeroelastic scale model. The tests have been successful in reproducing the aeroelastic phenomena arising in real-scale cases and have allowed the identification and a close characterization of the phenomenon. The main results have been the determination of the critical velocity for torsional galloping as a function of tilt angle and a calculation methodology for the optimal sizing of solar tracker shafts.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.3
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• pp.257-262
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• 2009

The unified power flow controller(UPFC) is one of the most effective devices in the FACTS family. This paper concerns about a filtering technique for reducing the computer calculation to determine the optimal location of UPFC in a power system. The sensitivities of the power generation cost for UPFC control parameters are evaluated. This technique requires that only one optimal power flow is run to get UPFC sensitivities for all possible transmission lines. To find out a optimal locating of a single UPFC in power system, an ideal transformer model which consists of a complex turns ratio and a variable shunt admittance was used. In this model, the UPFC control variables do not depend on UPFC input and output currents and voltages. The sensitivity method was tested on a 5-bus system derived from the IEEE 14-bus system and IEEE 14-bus system to establish its effectiveness.