• Journal of Korea Society of Industrial Information Systems
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• v.28 no.5
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• pp.77-87
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• 2023

Wind turbines playing a critical role in renewable energy generation, accurately assessing their operational status is crucial for maximizing energy production and minimizing downtime. This study conducts a comparative analysis of different neural network models for wind turbine condition diagnosis, evaluating their effectiveness using a dataset containing sensor measurements and historical turbine data. The study utilized supervisory control and data acquisition data, collected from 2 MW doubly-fed induction generator-based wind turbine system (Model HQ2000), for the analysis. Various neural network models such as artificial neural network, long short-term memory, and recurrent neural network were built, considering factors like activation function and hidden layers. Symmetric mean absolute percentage error were used to evaluate the performance of the models. Based on the evaluation, conclusions were drawn regarding the relative effectiveness of the neural network models for wind turbine condition diagnosis. The research results guide model selection for wind turbine condition diagnosis, contributing to improved reliability and efficiency through advanced neural network-based techniques and identifying future research directions for further advancements.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.23 no.3
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• pp.445-457
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• 2013

This paper is about the study to build a quantitative methodology to assess cyber threats and vulnerabilities on control systems. The SCADA system in power industry is one of the most representative and biggest control systems. The SCADA system was originally a local system but it has been extended to wide area as both ICT and power system technologies evolve. Smart Grid is a concept to integrate energy and IT systems, and therefore the existing cyber threats might be infectious to the power system in the integration process. Power system is operated on a real time basis and this could make the power system more vulnerable to the cyber threats. It is a unique characteristic of power systems different from ICT systems. For example, availability is the most critical factor while confidentiality is the one from the CIA triad of IT security. In this context, it is needed to reflect the different characteristics to assess cyber security risks in power systems. Generally, the risk(R) is defined as the multiplication of threat(T), vulnerability(V), and asset(A). This formula is also used for the quantification of the risk, and a conceptual methodology is proposed for the objective in this study.

• Journal of the Korean Dietetic Association
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• v.8 no.2
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• pp.163-174
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• 2002

The purpose of this study is to gather basic data on dietitian's general characteristics, working conditions, job achievement and job satisfaction. Thereby, a formulation can be worked out to improve dietitian's job achievement and satisfaction. The study was conducted during one week period, spanning July 23 to July 30, 1998. The method of the study was to distribute 560 questionnaires to the primary school dieticians working in the city of Tae Jun, located in Choong-Cheong Province. Out of 560 questionnaires that was distributed, 327 were returned. Moreover, 318 out of 327 questionnaires that was returned was valid enough to be processed by the SAS Program. About sixty percent of the respondents(61.1%) indicated that they were between 26 to 30 years old. Moreover, approximately half of the respondents(48.8%) were unmarried. In terms of the level of education, the bachelor's degree was reported as the most common education level(56.3%), while 3.8% of the participants reported achieving graduate degrees. The number of years in working in the profession ranged from 2 to 5 years. Furthermore, approximately 74% of the respondents indicated that, on average, they earned over ￦800,000 per month. In terms of the type of the school setting, 52.8% of the respondents worked in the urban setting, whereas, 60.0% worked in the rural school setting. Of these schools, about thirty eight percent(38.7%) of the schools were relatively small sized schools(400 students or less ). In terms of dietitian's sense of job satisfaction, the areas that showed relatively high level of satisfaction was in the menu control work(3.90) and purchase control work(3.90). However, appallingly low job satisfaction was indicated in the areas of personnel management (2.96%), and nutritional education and counsel(2.73%). Furthermore, job satisfaction varied greatly depending on age, wage, type of the food service, and type of school. The highest satisfaction was indicated in the areas of supervisory position(3.42), work itself(3.31%), co-workers(3.11). Other facets that led to job satisfaction were periodic wage increase(2.19%) and promotion opportunities(2.79%). In conclusion dietitian's job achievement showed significant correlation with job satisfaction. The study suggests that, in order to improve the overall job satisfaction of the dieticians, it is necessary to improve the working conditions of dieticians in primary schools. Secondly, there is a necessity for improving the status of the dieticians by raising the salary and treating the dieticians with the same level of respect in comparison with teachers or executive officials. Finally, another way of raising the job satisfaction of the dieticians is to provide opportunity for continuing education. So that, they can further their career in their chosen field.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1154-1163
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• 2008

DAS and SCADA system are main systems, which operate and manage the power system by using computer and communication technology. But DAS and SCADA have been operated independently in Korea, so there was some time delay in the fault handling and live-line work. To improve that problems, studies on the interface between DAS and SCADA have been needed. From November 2005 to December 2007, the pilot project has been performed in KEPCO's branch offices, as a result, direct method will be applied widely all over the country until 2010 because the operation information of substation users want can be transmitted fast and it is possible to control 43RC directly although the expense for direct method is about 1.3 times larger than that for web method. To improve problems revealed during the pilot project, substation object to object communication method is proposed and interface database automatic generation and interface system diagnosis and logging functions are developed. Interface data point and communication data type are defined, substation single line diagram automatic generation or manual editing function, SCADA monitoring and controlling function, log data managing function are developed in SCADA HMI program. It is expecting to reduce the average time for each outage about 33% and to improve the reliability, efficiency of operation, execution of DAS from automatic load transfer under a fault, and to contribute to export project.

• Korean Chemical Engineering Research
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• v.45 no.1
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• pp.73-80
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• 2007

This article aims to optimize the nitrogen removal of a sequencing batch reactor (SBR) through the use of the activated sludge model and iterative dynamic programming (IDP). Using a minimum batch time and a maximum nitrogen removal for minimum energy consumption, a performance index is developed on the basis of minimum area criteria for SBR optimization. Choosing area as the performance index makes the optimization problem simpler and a proper weighting in the performance index makes it possible to solve minimum time and energy problem of SBR simultaneously. The optimized results show that the optimal set-point of dissolved oxygen affects both the total batch time and total energy cost. For two different influent loadings, IDP-based SBR optimizations suggest each supervisory control of batch scheduling and set-point trajectory of dissolved oxygen (DO) concentration, and can save 20% of the total energy cost, while meeting the treatment requirements of COD and nitrogen. Moreover, it shows that the re-optimization of IDP within a batch can solve the modelling error problem due to the influent loading changes, or the process faults.

• Journal of the Korean Society of Safety
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• v.37 no.4
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• pp.20-27
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• 2022

This article aims to develop an algorithm that detects fire pump defects by analyzing the current signals of an induction motor, which are triggered by changes in the flow rate and pressure of multistage volute pumps that are used for fire services. The operational status of the pumps was categorized into three: first, normal operation; second, a defect that is caused by a change in the current value; and third, a defect occasioned by a change in current, pressure, and flow rate. When a fire pump was in normal operation, the motor's operating current was measured between 5.06 A and 6.9 A, the flow rate was estimated at 0-0.27 m³/min, and the pressure ranged from 0 to 0.47 MPa. In the event that a defect was caused by an abnormal current value in the motor, it was attributed to the pump's adherence. Furthermore, if there was no source of water, the defect was considered to have been induced by phase-loss operation, no-load operation, or run-stop operation, with the current value of each scenario being measured at > 52.8 A, < 4.13 A, > 45.15 A, and < 3.8 A, respectively, placing its overall range between 0 and 50 A. The sources of defects were detected based on an analysis of the flow rate, pressure, and current, which represent the following causes: air inflow into the casing, inadequate suction of water, and reverse-phase operation, respectively. Each cause entailed the following values: when air seeped into the casing, the pressure was measured at 0.24 MPa irrespective of changes in the flow rate; when there was inadequate suction of water, the pressure was recorded between 0 and 0.05 MPa despite changes in the flow rate; and when the power line's reverse-phase loss was the cause of the defect, the pressure was measured at 0.33 MPa for a flow rate of 0 L/min, and a higher flow rate decreased the pressure to nearly 0 MPa. The results of this study will enable engineers to develop a pump defect detection algorithm that is based on an analysis of current, and this algorithm will facilitate the execution of a program that will control a fire pump defect detection system.

• Journal of Legislation Research
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• no.44
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• pp.343-386
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• 2013

"Financial ADR" system in South Korea can be represented by so-called "Financial Dispute Resolution System", in which Financial Supervisory Service (FSS) and Financial Dispute Resolution Committee are the principal actors in operation of the system, and this is discussed as an "Administrative Financial ADR System". The system has over 10-year history since it was introduced in around 1999. Nonetheless, it was not until when financial consumer protection began to be highlighted after the 2008 financial crisis that Financial ADR system actually started to draw attention in Korea. This was because interest has been rising in "Alternative Dispute Resolution (ADR)" as an institutional measure to protect financial consumers damaged via financial transactions. However, the current discussion on the domestic Financial ADR system shows an aspect that it is confined to who is to be a principal actor for the operation of Financial ADR institution with main regards to reorganization of supervisory system. This article aims to embody these facts in an institutional model by recognizing them as a problem and analyzing the features of the Financial ADR system, thereby clarifying problems of the system and presenting the direction of improvement. The Korean Financial ADR system can be judged as "administrative model integrated model consensual model quasi-judicial model non-prepositive Internal Dispute Resolution (IDR) model". However, at the same time, it is confronted with a task to overcome the two problems; the system is not equipped with institutional basis for securing its validity in spite of the adopted quasi-judicial effect model; and a burden of operating an integrated ADR system is considerable. From this perspective, the article suggests improvement plans for security of validity in the current system and for expansion of industry-control ADR system, in particular, a system of prepositive IDR model. Amongst them, it suggests further plans for securing the validity of the system as follows; promotion to expand the number of internal persons and to differentiate mediation procedures and effect; a plan to keep a financial institution from filing a lawsuit before an agreement recommendation or a mediation proposal is advised; and a plan to grant suspension of extinctive prescription as well as that of procedures of the lawsuit.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.284-291
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• 2017

There is no doubt that advances in UAV technology have improved military performance. However, these advances require humans to adapt to new and complex operational systems. UAV has been rapidly expanding to a variety of fields such as reconnaissance, transportation, communication and aerial photographing recently. Also, with the development of UAV automation technology, one operator is able to supervisory-control multiple-UAVs. However, as the number of assigned UAV increases, the amount of information increases and this results in the workload of the operator increasing and deterioration in controlling performance. Accordingly, there is a need for a model to determine the level of overload an operator may encounter with regard to multiple-UAV but nationally this kind of research is currently lacking. Therefore, this paper provides an experimental platform for evaluating workload index effectiveness integrating multiple-UAV operational environments, GCS, and eye-tracking system followed by a limited survey of domestic and international studies of multi-UAV overload studies.

• Journal of the Korean Institute of Intelligent Systems
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• v.25 no.2
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• pp.174-179
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• 2015

Failure Mode and Effects Analysis (FMEA) has been used by Dynamic Positioning (DP) system for risk and reliability analysis. However, there are limitations associated with its implementation in offshore project. 1) since the failure data measured from the SCADA system is missing or unreliable, assessments of Severity, Occurrence, Detection are based on expert's knowledge; 2) it is not easy for experts to precisely evaluate the three risk factors. The risk factors are often expressed in a linguistic way. 3) the relative importance among three risk factors are rarely even considered. To solve these problems and improve the effectiveness of the traditional FMEA, we suggest a Fuzzy-FMEA method for risk and failure mode analysis in Dynamic Positioning System of offshore. The information gathered from DP FMEA report and DP FMEA Proving Trials is expressed using fuzzy linguistic terms. The proposed method is applied to an offshore Dynamic Positioning system, and the results are compared with traditional FMEA.

• The Journal of the Convergence on Culture Technology
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• v.5 no.3
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• pp.125-130
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• 2019

This research is about alternative measure of main components for sprinkler system like automatic wet pipe sprinkler system, dry pipe sprinkler system, pre-action sprinkler system, vacuum sprinkler system, deluge sprinkler system, and so on. By replacing the alarm check valve, dry valve, pre-operated valve, and deluge open valve with a solenoid valve, it be can be simplifed the various processes of the manufacturing process into one process, it creates an environment in which one standardized product can be produced simultaneously on a single machine. Therefore, it could improve the price competitiveness of products, reduce the maintenance cost, and help the adaptability of new sprinkler systems in the future. There is a benefit when it comes to apply to sprinkler system. Only replace the valve which is used to control primary and secondary valve such as wet, dry, pre operated, vacuum, deluge system valve. Other components such as retarding chambers, automatic air compressors, accelerators or adjusters, supervisory panels, vacuum pumps, and manual starters can be used as they are, so they can be easily applied to existing sprinkler system. It is needed to legal and institutional study for solenoid valve applied sprinkler system to commercialize.