• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 B
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• pp.1309-1312
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• 2002

The electric power network paralleled with wind turbine generator may have the negative impacts on the protection, operation, and management caused by the operation of wind turbine generator. Therefore, it is necessary to investigate the operating characteristic of wind turbine generator. This paper describes model of a squirrel-cage type wind turbine induction generator and the soft cut-in connection method for reducing the transient state on power network, and simulates various cases of wind turbine operations. The radial distribution network of IEEE 13-bus are modeled and tested by PSCAD/EMTDC.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 D
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• pp.2611-2613
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• 2000

This paper deals with a novel approach to unknown inputs observer(UIO) design for linear time-invariant dynamical systems using a fast Walsh transform and Walsh function's differential operation. Generally, UIO has a derivation of system outputs which is not available from the measurement directly. And it is an obstacle to estimate the unknown inputs properly when unexpected measurement noises are presented. Therefore, this paper propose an algebraic approach to eliminate such problems by using a Walsh function's differential operation.

• 인터넷정보학회논문지
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• 제20권6호
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• pp.21-28
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• 2019

Process mining is state-of-the-art technology in the workflow field. Recently, process mining becomes more important because of the fact that it shows the status of the actual behavior of the workflow model. However, as the process mining get focused and developed, the material of the process mining - workflow event log - also grows fast. Thus, the process mining algorithms cannot operate with some data because it is too large. To solve this problem, there should be a lightweight process mining algorithm, or the event log must be divided and processed partly. In this paper, we suggest a set of operations that control and edit XES based event logs for process mining. They are designed based on relational algebra, which is used in database management systems. We designed three operations for tailoring XES event logs. Select operation is an operation that gets specific attributes and excludes others. Thus, the output file has the same structure and contents of the original file, but each element has only the attributes user selected. Union operation makes two input XES files into one XES file. Two input files must be from the same process. As a result, the contents of the two files are integrated into one file. The final operation is a slice. It divides anXES file into several files by the number of traces. We will show the design methods and details below.

• 한국멀티미디어학회논문지
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• 제24권11호
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• pp.1552-1559
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• 2021

Convolution neural networks (CNNs) show notable performance in image processing and are used as representative core models. CNNs extract and learn features from large amounts of train dataset. In general, it has a structure in which a convolution layer and a fully connected layer are stacked. The core of CNN is the convolution layer. The size of the kernel used for feature extraction and the number that affect the depth of the feature map determine the amount of weight parameters of the CNN that can be learned. These parameters are the main causes of increasing the computational complexity and memory usage of the entire neural network. The most computationally expensive components in CNNs are fully connected and spatial convolution computations. In this paper, we propose a Fourier Convolution Neural Network that performs the operation of the convolution layer in the Fourier domain. We work on modifying and improving the amount of computation by applying the fast fourier transform method. Using the MNIST dataset, the performance was similar to that of the general CNN in terms of accuracy. In terms of operation speed, 7.2% faster operation speed was achieved. An average of 19% faster speed was achieved in experiments using 1024x1024 images and various sizes of kernels.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.863-868
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• 2004

Reheating furnace is an essential facility of a rod mill plant where a billet is heated to the required rolling temperature so that it can be milled to produce wire. Sometimes, it is also necessary to control a transient billet temperature pattern according to the material characteristics to prevent a wire from breaking. Though it is very important objective to obtain a correct information of a billet temperature during furnace operation. Consequently, a billet temperature profile must be estimated. In this paper, a billet heat transfer model based on FEM (Finite Element Method) with spatially distributed emission factors is proposed and a measurement is also carried out for two different furnace operation conditions. Finally, the difference between the model outputs and the measurements is minimized by using the new optimization algorithm named uDEAS(Univariate Dynamic Encoding Algorithm for Searches) with multi-step tuning strategy. Hence, the information of billet temperatures can be obtained by using proposed model on various furnace operation conditions.

• 한국컴퓨터정보학회논문지
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• 제9권2호
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• pp.125-130
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• 2004

정보통신과 네트워크의 발전으로 인하여 정보에 대한 보안의 중요성이 날이 갈수록 심화되고 있다. 이러한 시점에서 암호시스템들이 발전하고 있으나 비례적으로 크랙 및 해킹의 기술도 발전되고 있다. 그러므로 본 논문에서는 바이트 가변연산을 이용하여 블록암호시스템을 설계하였다. 설계된 바이트 기반 블록암호시스템은 고정된 DC 및 LC를 발생시키지 않으므로 이러한 공격방법으로부터 안전하다는 장점을 가진다. 또한 기존 대칭형 암호시스템이 가지고 있던 처리속도와 비대칭 암호시스템이 가지고 있던 인증기능을 모두 포함함으로서 네트워크 기반에서의 정보통신발달에 많은 도움을 주리라 사료된다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.1212-1218
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• 2004

Train operation simulation program models the railway facilities such as railway network configuration, railway parameters and signalling equipments, as well as the train performances such as traction performance, schedules, timetable. As the program can emulate exactly the train movements on the railway network by using computer simulation techniques, it can be applied to the optimization of the train operation plan and the reform of railway facilities. This paper provides a simulation case study which shows that we can simulate exactly the unusual situations of train traffic operation when train movements are disturbed by accidents, and also provide the effective countermeasure to minimize the train delays.

• 전력전자학회논문지
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• 제20권4호
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• pp.313-320
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• 2015

This study deals with a bidirectional interleaved soft switching DC-DC converter for a wide range of input voltages. The proposed converter operates in complementary switching with the purpose of inductor size reduction and zero-voltage switching (ZVS) operation. The current ripple related to complementary switching is minimized by three-phase interleaved operation. The main characteristics of the proposed topology are its soft-switching method of operation and its simple structure. The soft-switching operation and the system efficiency of the proposed converter are verified by experimental results.

• 한국자동차공학회논문집
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• 제11권5호
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• pp.193-200
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• 2003

A computer simulation program to evaluate the performance of railway systems and train operation plans and the effects of new technologies is provided. The program has the functions of tracing the movements of trains on railway network following the indication of railway signalling system and obeying all kinds of operation rules. An object-oriented technique is applied to model railway system effectively, and it is expected that the program code can be reused easily for other railway simulation programs. Dedicated graphic user interface displaying the simulation outputs by animation during simulation process makes the program convenient to use. Simulation results on the train operations on Kyung-bu line show the proposed program is promising.

• Journal of Information Technology Applications and Management
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• 제25권3호
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• pp.29-41
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• 2018

The purpose of constructing university information system is for improvement in diversification and throughput of information, streamlines business processes, rapid exchange of information, sharing of information, decision-making information, and securing educational facilities. Similar to business information technology system, university information system does not have a review system for sharing and overlapping investment of information. Due to the lack of project management for outsourcing and vulnerability of system suitability, system audit is absolutely needed for the university information system. This paper especially focuses on an operational phase in the audit of university information system. Additionally, we proposed operating model and checklists of the university information system based on Management Guidelines of ITIL V3 Operational and Information System. We derived the checklists of operation audit by each domain of service strategy, service design, service transition, service operation, and continual service improvement. As the result, this study appear to have more than average satisfaction the suitability results were.