• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 추계학술대회 논문집 학회본부 A
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• pp.3-5
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• 2000

It has been the paradigm of game theory that more than two utilities compete and determine the price and amount of dispatch. In order for this theory to be available on real power system, it is necessary to consider the transmission costs as well as the generation costs. In addition Independent System Operator(ISO) should be able to mitigate the congestion, recover the transmission costs and provide information for long-term capacity investment by devising reasonable pricing schemes for the transmission services. Generators also have to take the transmission costs into account when building the bidding strategies. This paper proposes an approach to analyzing the profit maximizing game considering the transmission cost in a competitive electricity market.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 추계학술대회 논문집
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• pp.3-6
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• 2002

This paper presents the cutting simulation system for prediction and regulation of cutting force in CNC machining. The cutting simulation system includes geometric model, cutting force model, and off-line fred rate scheduling model. ME Z-map(Moving Edge node Z-map) is constructed for cutting configuration calculation. The cutting force models using cutting-condition-independent coefficients are developed for flat-end milling and ball-end milling. The off-line feed rate scheduling model is derived from the developed cutting force model. The scheduled feed rates are automatically added to a given set of NC code, which regulates the maximum resultant cutting force to the reference force preset by an operator. The cutting simulation system can be used as an effective tool for improvement of productivity in CNC machining.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.308-315
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• 1997

In this study, the effect of modal filter error on the vibration control characteristics of flexible structures is analyzed for IMSC(Independent Modal Space Control), and optimal sensor placement in the structural vibration control with consideration of performance of modal filter has been studied. An Lyapunov asymptotic stability condition has been derived, which depends on the magnitude of the modal filter errors. The extent of the response deviation of the closed-loop system is also derived and evaluated using operator techniques. A sensor placement technique has also been suggested to maximize the performance of the modal filter. It has been found by a series of simulation that the suggested sensor placement technique is very effective on the determination of the number and placement of sensors of modal filter in the structural vibration control.

• 전기학회논문지
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• 제63권6호
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• pp.752-757
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• 2014

This paper attempts to evaluate the impact of power plant penetration on constraints of a transmission network and proposes a methodology based on risk level, which can evaluate the condition of the network and facilities intuitionally. Furthermore, based on this methodology, RLII(Risk Level Improvement Index) is proposed in order to establish comprehensive TNEP(Transmission Network Expansion Planning) from a viewpoint of ISO(Independent System Operator). In order to verify the proposed methods in this paper, real power systems in Incheon and Shiheung areas, south Korea are applied to the case study.

• ETRI Journal
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• 제43권1호
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• pp.152-162
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• 2021

In the last few years, detection has become a powerful methodology for network protection and security. This paper presents a new detection scheme for data recorded over a computer network. This approach is applicable to the broad scientific field of information security, including intrusion detection and prevention. The proposed method employs bidimensional (time-frequency) data representations of the forms of the short-time Fourier transform, as well as the Wigner distribution. Moreover, the method applies matrix factorization using singular value decomposition and principal component analysis of the two-dimensional data representation matrices to detect intrusions. The current scheme was evaluated using numerous tests on network activities, which were recorded and presented in the KDD-NSL and UNSW-NB15 datasets. The efficiency and robustness of the technique have been experimentally proved.

• 전기학회논문지
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• 제63권9호
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• pp.1171-1179
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• 2014

ISO(Independent System Operator) or TSO(Transmission System Operator) use power system analysis program to simulate contingency analysis and remedial actions to operate power system stably. Generally, power system analysis program provides automated analysis functions(or modules) to deal with wide area power system. However, because of missed contingency cases, automated contingency analysis has no practical use or has limitation. And in case of remedial action, it doesn't support automated function or takes a lot of times to study, because of simulation in manual for each cases. This paper suggests that new relation with buses and transmission line properties of power system DB used for power system analysis program to simulate automated contingency including all contingency cases needed in the field without missed cases. And it proposes automated remedial action scheme based on practical approach analysis to alleviate overloading or voltage problems. Finally it deals with automated contingency/remedial action analysis(automated scheduled outage) program which is developed by KEPCO and its performance and proposed schemes are proven by case study for real Korean power system data.

• Journal of Korea Trade
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• 제27권1호
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• pp.101-118
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• 2023

Purpose - Korea became a trillion-dollar trading country in 2011. With the exponential increase in Korea's trade volume over the past decades, trade-related administrative burdens per capita for Korea Customs became enormous, for which the government established the Single Window, a trade-facilitating system, in 2004 to enhance the efficiency of customs-clearing procedures for traders. This paper focuses on finding whether the Korean Single Window system affects the country's trade facilitation positively through an empirical methodology. Design/methodology - To find empirical evidence that Single Window affects trade facilitation for the customs-clearing procedure, this study assumes that a time-efficient environment enables the handling of the increase in trade volume, under which four independent variables related to import customs-clearing procedures and two dependent variables to import were adopted for empirical analysis. The import customs procedures are classified into four steps from port entry to declaration acceptance. To understand the relationship between variables, scattered plots and correlation coefficients were calculated. Eight hypotheses were set and underwent simple linear regression. The data for analysis were collected by Korea Customs, and were about the lead time of import, the volume of imports in million USD, and the number of import declarations reported to customs offices on a monthly basis from 2005 to 2013. Findings - Six of the eight hypotheses showed the statistically significant result that lead time in the import customs-clearing procedure positively affects the number of import declaration reports and import volume. Specifically, Hypothesis 1, Hypothesis 2, and Hypothesis 3 strongly support the assumption lead time in import customs declaration has an inverse relationship with the number of import declarations, which means that the shorter the import lead time, the more import declaration increases. Research Limitations/Implications - With limited data accessibility to the government's custom-sclearing procedures, only the import lead time for customs clearance were adopted as independent variables. This paper, however, successfully found that the Single Window system contributed to trade facilitation. Originality/value - This study found that the time-saving Single Window system of Korea Customs enables itself to manage an exponentially-increasing trade volume by creating a trade-facilitating environment for customs personnel and traders, which may be a unique implication found through quantitative methodology.

• 대한디지털의료영상학회논문지
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• 제15권2호
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• pp.1-6
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• 2013

This study is to provide clinical data when reverse-water's-view was carried out about pediatric who did not communicate by applying self-development jaw lift tool. This study were conducted in a subject of 23 children who examined revers-water's-view from 2013 July 6 to 2013 August 5 at our hospital. Two group time which were carried out revers-water's with tool and without tool were measured. also, Image of two group were evaluated. Evaluation data obtained by measuring the average difference were analyzed by independent-t-test. After apply self-development-jaw-lift-tool, time was reduced by 35.2%(36.6sec). the results indicated significant differences(p< .05). Image evaluation was increase 43.5%(1.03point), It was statistically highly significant difference (p< .01). If apply self-development-jaw-lift-tool in pediatric revers-water's-view, operator can provide fast, convenience, high quality image to pediatric.

• International Journal of Control, Automation, and Systems
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• 제6권5호
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• pp.639-650
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• 2008

Electricity price forecasting has become an integral part of power system operation and control. In this paper, a wavelet transform (WT) based neural network (NN) model to forecast price profile in a deregulated electricity market has been presented. The historical price data has been decomposed into wavelet domain constitutive sub series using WT and then combined with the other time domain variables to form the set of input variables for the proposed forecasting model. The behavior of the wavelet domain constitutive series has been studied based on statistical analysis. It has been observed that forecasting accuracy can be improved by the use of WT in a forecasting model. Multi-scale analysis from one to seven levels of decomposition has been performed and the empirical evidence suggests that accuracy improvement is highest at third level of decomposition. Forecasting performance of the proposed model has been compared with (i) a heuristic technique, (ii) a simulation model used by Ontario's Independent Electricity System Operator (IESO), (iii) a Multiple Linear Regression (MLR) model, (iv) NN model, (v) Auto Regressive Integrated Moving Average (ARIMA) model, (vi) Dynamic Regression (DR) model, and (vii) Transfer Function (TF) model. Forecasting results show that the performance of the proposed WT based NN model is satisfactory and it can be used by the participants to respond properly as it predicts price before closing of window for submission of initial bids.

• 대한전자공학회논문지TC
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• 제40권11호
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• pp.27-33
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• 2003

데이터 감시(AUDIT) 기능이란 분산 실장 되어 있는 데이터들을 대상으로 데이터 이상을 진단하고 불일치 데이터를 검출하여 이를 일치시키는 일련의 작업을 말하는 것으로 데이터 불일치로 인해 유발되는 시스템 문제를 최소화시키는데 목적을 둔다. 본 논문에서는 ATM 교환기의 연결 데이터의 대부분을 차지하고 있는 PVC(Permanent Virtual Circuit) 데이터에 대한 감사 기능 지원 방안을 제안하였다. 즉 고속/저속 가입자 링크에 대해 일정 시간마다 감사 기능의 주기적 수행과 운용자 명령어에 의한 즉각적인 감사 기능을 제안하여 PVC 정보의 불일치로 인한 데이터의 손실 및 시스템 장애를 최소화 할 수 있게 하였다. 또한 감사 기능으로 인해 연결 제어 프로세서와 DC(Device Controller) 사이에 송수신하는 많은 IPC(Inter Processor Communication) 메시지가 연결 제어 프로세서의 부하에 어떠한 영향을 미치는지 분석하였는데, 시스템 부하와 거의 무관하게 연결 제어 프로세서의 부하가 일정함을 확인하였다.