• Journal of Electrical Engineering and Technology
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• v.9 no.4
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• pp.1248-1257
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• 2014

Overhead transmission lines are crucial components in power transmission systems. Well-designed maintenance strategy for overhead lines is required for power utilities to minimize operating costs, while improving the reliability of the power system. This paper presents a maintenance priority index (MPI) of overhead lines for a reliability centered approach. Proposed maintenance strategy is composed of a state index and importance indices, taking into account a transmission condition and importance in system reliability, respectively. The state index is used to determine the condition of overhead lines. On the other hand, the proposed importance indices indicate their criticality analysis in transmission system, by using a load effect index (LEI) and failure effect index (FEI). The proposed maintenance method using the MPI has been tested on an IEEE 9-bus system, and a numerical result demonstrates that our strategy is more cost effective than traditional maintenance strategies.

• Proceedings of the Korea Contents Association Conference
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• 2008.05a
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• pp.258-261
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• 2008

Sport industry creates value-added by production and distribution of product or service related with sports or sports. Because this industry shows promise in becoming a major industry area, the government is making an effort to bring up or develop it. The financing to firms of sport industry area(sporting goods industry, sport facility industry, sport service industry) with low interest rate and long-term repayment period on the basis of sports promotion fund is excellent scheme to promote sport industry. Nevertheless, Because many people indicate operational inefficiency of it, it is necessary to check operational efficiency through investigation for loan system of sports promotion fund. The purposes of this paper are to analyze public loan system using funds of other government organization and to the current status of loan system of sports promotion fund.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.02a
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• pp.82-94
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• 2004

This paper addresses solutions to the challenges of carrier phase integer ambiguity resolution and cycle slip detection/identification, for maintaining high accuracy of an integrated GPS/Pseudolite/INS system. Such a hybrid positioning and navigation system is an augmentation of standard GPS/INS systems in localized areas. To achieve the goal of high accuracy, the carrier phase measurements with correctly estimated integer ambiguities must be utilized to update the system integration filter's states. The occurrence of a cycle slip that is undetected is, however, can significantly degrade the filter's performance. This contribution presents an effective approach to increase the reliability and speed of integer ambiguity resolution through using pseudolite and INS measurements, with special emphasis on reducing the ambiguity search space. In addition, an algorithm which can effectively detect and correct the cycle slips is described as well. The algorithm utilizes additional position information provided by the INS, and applies a statistical technique known as the cumulative-sum (CUSUM) test that is very sensitive to abrupt changes of mean values. Results of simulation studies and field tests indicate that the algorithms are performed pretty well, so that the accuracy and performance of the integrated system can be maintained, even if cycle slips exist in the raw GPS measurements.

• Journal of Power Electronics
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• v.17 no.6
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• pp.1683-1693
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• 2017

This paper analyses the harmonic pollution to power grids caused by thyristor-controlled devices. It also formulates a mathematic derivation for the voltage spikes in thyristor-controlled branches to explain the harmonic and EMI derived from the reverse-recovery characteristics of the thyristor. With an equivalent nonlinear time-varying voltage source, a detailed simulation model is established, and the periodic dynamic switching characteristic of the thyristor can be explicitly implied. The simulation results are consistent with the probed results from on-site measurements. An improved trigger system with gate-shorted circuit structure is proposed to reduce the voltage spikes that cause EMI. The experimental results indicate that a prototype with the improved trigger system can effectively suppress the voltage spikes.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.4
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• pp.10-18
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• 2012

This paper develops a decentralized advanced traveler information system (ATIS) under the connected vehicle environment, recently regarded as one of most promising tools in Intelligent Transportation Systems (ITS). The performance of the proposed ATIS is reinforced by introducing autonomous automatic incident detection (AAID) function. The proposed ATIS is implemented and tested using an off-the-shelf microscopic simulation model (VISSIM) on a simple traffic network under idealized communication conditions. A key attribute of this experiment is the inclusion of a non-recurrent traffic state (i.e., traffic incident). Simulation results indicate that the ATIS using V2V communication is efficient in saving drivers' travel time and AAID plays an important role in improving the effectiveness of the system.

• Journal of the Korean Solar Energy Society
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• v.35 no.1
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• pp.29-34
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• 2015

The photovoltaic ribbon attached the flux reduces the solar module manufacturing process and the pollution. This paper presents an analytical method for solving the continuous flux drying system of photovoltaic ribbon. Also, some experiments of the drying of photovoltaic ribbon are carried out in order to design the drying system. Numerical results indicate the air temperature, the air velocity, the air pressure and the timewise temperature variation of ribbon during drying process. In case of the drier process length is short, 400mm, the photovoltaic ribbon is wet. Thus, another study of drying system is necessary to improve the drying ability. As a result, multi-stage drier system is proposed and shown to be good drying ability.

• PNF and Movement
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• v.1 no.1
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• pp.33-41
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• 2003

Objectives : The purpose of this study was to describe and compare the temporo-spatial gait characteristics of healthy young people with those of healthy elderly people. Methods: The data were collected by 40 volunteers. 20 subjects were between 20 and 31 years of age, and 20 subjects were between 65 and 84 years of age. Temporal and spatial parameters of gait were analysed for using the computerized GAITRite system. Results : The system integrates specific components of locomotion to provide a single, numerical representation of gait, the Functional Ambulation Performance score. Differences in gait characteristics between the two groups were examined using a correlated t-test(p<.05). Significant differences were observed between the groups for step length, step/extremity ratio and velocity. Young people demonstrated a significantly larger velocity, step length and step/extremity ratio than the elderly people. Conclusions: These results indicate that the GAITRite system can be useful in detecting footfall patterns and selected time and distance measurements of young and older persons. Additionaly, differences in walking velocity, step length and step/extremity ratio between old and young people may have influenced the gait characteristics measured.

• PNF and Movement
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• v.13 no.4
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• pp.175-180
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• 2015

Purpose: This study aimed to examine the effects of mirror-neuron-system-based action observation physical training on improvements in upper extremity functions and daily living activities in chronic stroke patients. Methods: Ten chronic stroke patients were randomly selected. As a therapeutic intervention, along with conventional occupational therapy, the patients engaged in action observation physical training through repeated imitation practices after they viewed a video. The therapeutic intervention was implemented for 20 minutes, three times each week for eight weeks. A Manual Function Test (MFT) was conducted to compare upper extremity functions before and after the therapeutic intervention, and the Modified Barthel Index (MBI) was used to compare the ability to perform daily living activities. Results: Significant improvements in upper extremity motor functions and the ability to perform daily living activities were shown after the intervention. The subjects' left upper extremity motor functions and ability to perform daily living activities showed significant improvement after the intervention. Conclusion: The study's results indicate that action observation physical training based on the mirror neuron system improves chronic stroke patients' upper extremity motor functions and their ability to perform daily living activities. Therefore, action observation training has positive effects on the functional recovery of chronic stroke patients.

• Journal of Information Processing Systems
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• v.17 no.4
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• pp.707-720
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• 2021

To improve the accuracy of the recommendation system, multi-criteria recommendation systems have been widely researched. However, it is highly complicated to extract the preferred features of users and items from the data. To this end, subjective indicators, which indicate a user's priorities for personalized recommendations, should be derived. In this study, we propose a method for generating recommendation candidates by predicting multi-criteria ratings from reviews and using them to derive user priorities. Using a deep learning model based on convolutional neural network (CNN) and bidirectional long short-term memory (BiLSTM), multi-criteria prediction ratings were derived from reviews. These ratings were then aggregated to form a linear regression model to predict the overall rating. This model not only predicts the overall rating but also uses the training weights from the layers of the model as the user's priority. Based on this, a new score matrix for recommendation is derived by calculating the similarity between the user and the item according to the criteria, and an item suitable for the user is proposed. The experiment was conducted by collecting the actual "TripAdvisor" dataset. For performance evaluation, the proposed method was compared with a general recommendation system based on singular value decomposition. The results of the experiments demonstrate the high performance of the proposed method.

• Advances in Computational Design
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• v.4 no.3
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• pp.307-326
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• 2019

A low computational cost semi-analytical method is developed, based on eigenfunction expansion, to study the vibration of rectangular plates subjected to a series of moving sprung masses, representing a bridge deck under multiple vehicle or train moving loads. The dynamic effects of the suspension system are taken into account by using flexible connections between the moving masses and the base structure. The accuracy of the proposed method in predicting the dynamic response of a rectangular plate subjected to a series of moving sprung masses is demonstrated compared to the conventional rigid moving mass models. It is shown that the proposed method can considerably improve the computational efficiency of the conventional methods by eliminating a large number of time-varying components in the coupled Ordinary Differential Equations (ODEs) matrices. The dynamic behaviour of the system is then investigated by performing a comprehensive parametric study on the Dynamic Amplification Factor (DAF) of the moving loads using different design parameters. The results indicate that ignoring the flexibility of the suspension system in both moving force and moving mass models may lead to substantially underestimated DAF predictions and therefore unsafe design solutions. This highlights the significance of taking into account the stiffness of the suspension system for accurate estimation of the plate maximum dynamic response in practical applications.