• Tunnel and Underground Space
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• v.31 no.1
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• pp.10-24
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• 2021

Rock mass classification for construction of underground facilities is essential to secure their stabilities. Therefore, the reliable values for rock mass classification from the precise information on rock discontinuities are most important factors, because rock mass discontinuities can affect exclusively on the physical and mechanical properties of rock mass. The conventional classification operation for rock mass has been usually performed by hand mapping. However, there have been many issues for its precision and reliability; for instance, in large-scale survey area for regional geological survey, or rock mass classification operation by non-professional engineers. For these reasons, automated rock mass classification using LiDAR becomes popular for obtaining the quick and precise information. But there are several suggested algorithms for analyzing the rock mass discontinuities from point cloud data by LiDAR scanning, and it is known that the different algorithm gives usually different solution. Also, it is not simple to obtain the exact same value to hand mapping. In this paper, several discontinuity extract algorithms have been explained, and their processes for extracting rock mass discontinuities have been simulated for real rock bench. The application process for several algorithms is anticipated to be a good reference for future researches on extracting rock mass discontinuities from digital point cloud data by laser scanner, such as LiDAR.

• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.310-312
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• 2006

Maglev using EMS becomes unstable by unexpected big air-gap disturbance. The main causes of the unexpected air-gap disturbance are step-wise rail joint and large distance between rail splices. For the stable operation of the Maglev, the conventional system uses the threshold method, which selects one gap sensor among two gap sensors installed on the magnet to read the gap between magnet and guide rail. But the threshold method with a wide bandwidth makes the discontinuous air-gap signal at the rail joints because of the offset in air gap sensors and/or the step-wise rail joins. Further more, in the case of the one with a narrow bend-width, it makes Maglev system unstable because of frequent alternation. In this paper, a new method using fuzzy rule to reduce air-gap disturbances proposed to improve the stability of Maglev system. It treats the air-gap signal from dual gap sensors effectively to make continuous signal without air gap disturbance. Simulation and experiment results proved that the proposed scheme was effective to reduce air-gap disturbance from dual gap sensors in rail joints.

• Journal of IKEEE
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• v.22 no.3
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• pp.619-623
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• 2018

Due to the development of society, the demand for electric power has increased and the quality control of electric power has become an important issue. In order to efficiently perform such power management, we propose a DSP based power measurement system for multi-wire power measurement. Since the conventional power measurement system can measure only the power of one line, a power quality measurement device is required for each line in order to measure the power quality of the individual line. Respectively. The system proposed in this paper proposes a system capable of real-time measurement of power quality at up to 12 points using digital signal processing algorithm, and the prototype based on this system was evaluated through the official test report of Korea Electrotechnology Research Institute. As a result of the performance test, it was evaluated that the error range is excellent at ${\pm}0.3%$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.4
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• pp.14-22
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• 2001

In this paper, we design the Adaptive Neuro-Fuzzy Precompensator(ANFP) for the suppression of low-frequency oscillation and the improvement of system stability. Here, ANFP is designed to compensate the conventional Power System Stabilizer(PSS). This design technique has the structural merit that is easily implemented by adding ANFP to an existing PSS. Firstly, the Fuzzy Precompensator with Loaming ability is constructed and is directly learned from the input and output data of the generating unit. Because the ANFP has the property of learning, fuzzy rules and membership functions of the compensator can be automatically tuned by teaming algorithm Loaming is based on the minimization of the ems evaluated by comparing the output of the ANFP and a desired controller. Case studies show the 7posed schema can be provided the good damping of the power system over the wide range of operating conditions and improved dynamic performance of the system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.2
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• pp.576-582
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• 2017

The switching system in a maglev train is an indispensable element for distributing train routes, and it should be designed to ensure safe operation. Unlike conventional wheels on rails, the switching track in EMS-type maglev is supported by a group of 3 to 4 steel girders. When the vehicle changes its route, the segmented track allows the girders to change from a straight position to a curved one with a small radius of curvature. Hence, the structural characteristics of the segmented switching system may affect the levitation stability of the maglev vehicle. This study experimentally evaluates the dynamic interaction between maglev vehicles and a segmented switching system. The results may be helpful for improving the switching system. The measured levitation and lateral air gaps were evaluated at a vehicle speed of 25 km/h, and the ride quality of the Maglev vehicle was determined to be "comfortable" according to the UIC 513 standard.