• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.2
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• pp.23-28
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• 2004

In EIT, various image reconstruction algorithms have been used in order to compute the internal resistivity distribution of the unknown object with its electric potential data at the boundary. Mathematically the EIT image reconstruction algorithm is a nonlinear ill-posed inverse problem. In this paper, a SPSA approach is proposed for the solution of the EIT image reconstruction. Results of numerical experiments of EIT solved by the SPSA approach are presented and compared to that obtained by the modified Newton-Raphson(mNR) method.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2721-2723
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• 2002

Electrical impedance tomograpy(EIT) determines the resistivity distribution inside an inhomogeneous target by means of voltage and current measurements conducted at the target boundary. In this paper, a simultaneous perturbation stochastic approximation(SPSA) approach is proposed for the solution of the EIT image reconstruction. Results of numerical experiments of EIT solved by the SPSA approach are presented and compared to that obtained by the modified Newton-Raphson(mNR) method.

• Journal of the Korean Society of Safety
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• v.36 no.5
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• pp.86-91
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• 2021

Calculating the scrutable core damage frequency (CDF) of nuclear power plants is an important component of the seismic probabilistic safety assessment (SPSA). In this work, a simple approach is developed to calculate CDF from minimal cut sets (MCSs) with non-rare events. When conventional calculation methods based on rare event approximations are employed, the CDF of industry SPSA models is significantly overestimated by non-rare events in the MCSs. Recently, quantification algorithms using binary decision diagrams (BDDs) have been introduced to prevent CDF overestimation in the SPSA. However, BDD structures are generated from a small part of whole MCSs due to limited computational memory, and they cannot be reviewed due to their complicated logic structure. This study suggests a simple approach for scrutinizing the CDF calculation based on whole MCSs in the SPSA system analysis model. The proposed approach compares the new results to outputs from existing algorithms, which helps in avoiding CDF overestimation.

• Journal of Electrical Engineering and Technology
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• v.3 no.1
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• pp.14-19
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• 2008

The paper presents an intelligent time series model to predict uncertain electricity market price in the deregulated industry environment. Since the price of electricity in a deregulated market is very volatile, it is difficult to estimate an accurate market price using historically observed data. The parameter of an intelligent time series model is obtained based on the simultaneous perturbation stochastic approximation (SPSA). The SPSA is flexible to use in high dimensional systems. Since prediction models have their modeling error, an error compensator is developed as compensation. The SPSA based intelligent model is applied to predict the electricity market price in the Pennsylvania-New Jersey-Maryland (PJM) electricity market.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.4
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• pp.87-94
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• 2013

This study estimated the changes in delays and speeds of vehicles in exclusive bus lane and road when the High Occupancy Vehicles(HOV) use the median bus lane. Synchro simulation tool was used to optimize the traffic signal time on the network and VISSIM was applied to simulate various scenarios. Here, drivers behavior parameters in VISSIM was optimized using Simultaneous Perturbation Stochastic Approximation(SPSA) algorithm in order to represent real traffic condition. Based on the simulation results, the delay in Doan daero was decreased when the volume of HOV in current condition runs on the median bus lane, whereas delay in Doan dongro was increased in all scenarios. The changes in bus speed was not sharply decreased for both study sites, even though the number of HOV increased to 10%. Thus, it could be allowed that the HOV use the median bus lane in Doan dongro and Doan daero. Future research tasks include studying about changes in delay when the HOV use the curb bus lane.

• International Journal of Control, Automation, and Systems
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• v.6 no.4
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• pp.506-514
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• 2008

This paper presents an intelligent model; named as free model, approach for a closed-loop system identification using input and output data and its application to design a power system stabilizer (PSS). The free model concept is introduced as an alternative intelligent system technique to design a controller for such dynamic system, which is complex, difficult to know, or unknown, with input and output data only, and it does not require the detail knowledge of mathematical model for the system. In the free model, the data used has incremental forms using backward difference operators. The parameters of the free model can be obtained by simultaneous perturbation stochastic approximation (SPSA) method. A linear transformation is introduced to convert the free model into a linear model so that a conventional linear controller design method can be applied. In this paper, the feasibility of the proposed method is demonstrated in a one-machine infinite bus power system. The linear quadratic regulator (LQR) method is applied to the free model to design a PSS for the system, and compared with the conventional PSS. The proposed SPSA-based LQR controller is robust in different loading conditions and system failures such as the outage of a major transmission line or a three phase to ground fault which causes the change of the system structure.

• Korean Journal of Agricultural Science
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• v.46 no.4
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• pp.857-868
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• 2019

A flooded rice field is one of the significant sources of anthropogenic methane (CH₄) with the intensity of the emissions dependent on management practices. Incorporation of rice straw, which is one of the organic amendments, induces the increase of methane emissions during the flooding season. In this study, we measured of methane emission according to applications of rice straw in different soil textures during a cultivation period in 2017 and 2018. The fallow treatments were non application of rice straw (NA), spring plowing after spring spreading of rice straw (SPSA), spring plowing after previous autumn spreading of rice straw (SPAA), and autumn plowing after previous autumn spreading of rice straw (APAA). The SPSA treatment emitted the highest total methane from loam soil in both 2017 (596.7 CH₄ kg ha^-1) and 2018 (795.4 CH₄ kg ha^-1). The same trend was observed in silt clay loam soil; the SPSA treatment still emitted the highest amount of methane in both 2017 (845.9 CH₄ kg ha^-1) and 2018 (1,071.7 CH₄ kg ha^-1). The lowest emission among the rice straw incorporated plots came from the APAA treatment for both soil texture types in all the seasons. The conversion factors of the SPAA were 0.79 and 0.65 from the loam and silt clay loam soils, respectively. Relatedly, the conversion factors of the APAA were 0.71 and 0.43 from the loam and silt clay loam soils, respectively. The above observations mean therefore that incorporation of rice straw early in the fallow reduces methane emissions in the main rice growing season.

• The Journal of Korean Academy of Sensory Integration
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• v.13 no.1
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• pp.1-12
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• 2015

Objective : The purpose of the study was to investigate the characteristics and psychometric properties of assessments which were developed to measure sensory processing functions of preschool-aged children. Method : Comprehensive search for assessments measuring sensory processing functions was administered by using multiple electronic databases, including PubMed, Cochrane, CINAHL and PsycINFO. The titles and abstracts from the retrieved papers were screened. Then assessment tools that met all of the inclusion criteria were selected. Results : Thirty-eight assessments were identified. There were eight assessment tools that met the pre-defined inclusion criteria. Sensory Processing Measure-Preschool (SPM-P) was verified to be the most reliable and valid assessment tool, whereas Sensory Experiences Questionnaire (SEQ), Sense & Self-Regulation Checklist (SSRC), and Sensory Processing Scale Assessment (SPSA) showed inadequate reliability and validity. Conclusion : Based on the results from this systematic review, it would be useful for clinicians and researchers to select assessment tools of sensory processing for preschool-aged children.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.36-40
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• 2017

The launch operation for a space launch vehicle(SLV) is to be conducted by the systematic operation between SLV and the Technological Equipment(TE) such as the mechanical, fuel, and electrical ground support equipment at launch complex(LC). The basic source for the operation of the instruments in LC is the electrical power supply system, Technological Equipment Power Supply System(TEPSS), which is one of the Launch Control System. Thus TEPSS should supply the required electrical power to TE with reliability. In this paper, TEPSS which supplies operational electrical power to TE is introduced.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.9 no.4
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• pp.60-67
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• 2010

Delay reduction of vehicles at the intersection is highly dependent on the signal operation method. Most previous traffic operations have focused on minimizing delay by adjust traffic offset. However, these methods have limitation in solving traffic problem if the volume reaches or exceeds the capacity. In this paper, it was analyzed that the effectiveness of various signal operation methods such as left-turn prohibition, and using protected mixed with permitted left turn using the traffic data from Daejeon city. In case of the left-turn prohibition of a intersection, the control delay reduced from 54.2 seconds to 22.7 seconds and especially, the delay of the southbound was drastically reduced. In addition, the delay was highly reduced from 27.0 seconds to 12.1 seconds when the operation system was changed to use protected mixed with permitted left turn.