• IE interfaces
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• v.16 no.4
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• pp.421-431
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• 2003

Due to the increasing complexity of the information systems environment, modern information systems are facing more difficult and various security risks than ever, there by calling for a higher level of security safeguard. In this paper, an information technology security risk management model, which modified by adopting the concept of business processes, is applied to client/server distributed systems. The results demonstrate a high level of risk-detecting performance of the model, by detecting various kinds of security risks. In addition, a practical and efficient security control safeguard to cope with the identified security risks are suggested. Namely, using the proposed model, the risks on the assets in both of the I/O stage(on client side) and the request/processing stage(on server side), which can cause serious problems on business processes, are identified and the levels of the risks are analyzed. The analysis results show that maintenance of management and access control to application systems are critical in the I/O stage, while managerial security activities including training are critical in the request/processing stage.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.23 no.57
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• pp.123-129
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• 2000

The Bootstrap method proposed by Efron is non-parametric method which doesn't depend on the estimation of prior distribution refer to population. A typical statistical process control chart which is generally used is developed under the assumption that observations follow mutually independent and identically distributed within a sample and between samples. However, autocorrelation greatly affect the developed control chart under the assumption that observations are mutually independent. Many researchers showed that the result which was analyzed by using a typical control chart for the observations which has the correlation violated to the independence assumption can not be true. Therefore, we compared the standard method with bootstrap method and then evaluated them for x control chart and EWMA control chart by using bootstrap method which was proposed by Efron in the AR(1) model when the observations have correlation.

• Journal of Korean Institute of Industrial Engineers
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• v.43 no.1
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• pp.12-18
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• 2017

This study presents a plant concept design for a smart factory which is mainly targeted to machine airplane parts. The plant layout is based on the TOC-DBR approach together with autonomous distributed factory control considered, while discrete event simulation is also performed in order to validate its layout. The resulting layout and its procedure turn out to be quite a useful guideline in realizing those smart factories especially for machining-oriented manufacturing industries.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.3
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• pp.169-175
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• 2010

Recently, to improve operating efficiency with the higher in-line rate in automated production lines, a lot of cases of grouping machines and material handling system together to form a cluster has shown frequently. This article addresses the job allocation and operation method of automated material handling for cluster-type production systems. First of all, the control problems of the automated material handling systems are classified into the control problem of inter-cluster material handling system and that of intra-cluster material handling system. Then, a distributed agent-based control scheme is proposed for the former, and an operational control procedure for the latter. Simulation experiment shows that the proposed method is efficient in reducing cycle times and improving utilization of material handling vehicles.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.1
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• pp.137-151
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• 1995

A difficult problem in operating Flexible Manufacturing Systems (FMS) is to control the system in real-time by coordinating heterogeneous machines and integrating distributed information. The objective of the paper is to present the models and methodologies useful to resolve the difficult problem. The detailed objectives can be described in three folds. First, a hierarchical Colored and Timed Petri-Net (CTPN) is designed to control an FMS in real-time. The concerned FMS consists of a loading station, several machining cells, a material handling system, and an unloading station. Timed-transitions are used to represent the timed-events such as AGV movements between stations and cells, part machining activities in the cells. Signal places are also used to represent communication status between the host and the cell controllers. To resolve the event conflicts and scheduling problems, dispatching rules are introduced and applied. Second, an implementation methodology used to monitor and diagnose the errors occurring on the machines during system operation is proposed. Third, a Petri-Net simulator is developed to experiment with the designed control logic.

• Journal of Institute of Control, Robotics and Systems
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• v.6 no.11
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• pp.943-954
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• 2000

Fieldbus is the lowest level industrial network in the communication hierarchy of factory automation and distributed process control systems. Data generated from field devices are largely divided into three categories : time-critical, periodic and time-available data. Because these data share one fieldbus medium, it needs a method that allocates these data to the bandwidth-limited fieldbus medium. This paper introduces an implementation method of bandwidth allocation scheme on PROFIBUS. In order to implement bandwidth allocation scheme on PROFIBUS, the following functions need to be supplemented on the FDL(Fieldbus Datalink Layer) protocol: (i) separation of medium bandwidth into periodic and non-periodic intervals, (ii) synchronization of node timers over a local link. In order to examine the validity of bandwidth allocation scheme on PROFIBUS, this paper develops an experimental model of a network system. The results obtained from the experimental model show that the bandwidth allocation scheme satisfies the performance requirement of time-critical, periodic and time-available data.

• 제어로봇시스템학회:학술대회논문집
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• 1993.10a
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• pp.595-600
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• 1993

The heat of reaction has been estimated from heat balance relationships around the reactor. The heat balance equations were formulated with the assumptions that the reactor temperature is uniformly distributed and the jacket temperatures are axially distributed. We have obtained the temperature distribution of jacket contents by FDM. And then, we have rearranged the heat balance equations so that the heat of reaction can be estimated from the finite number of temperature measurements, i.e., temperatures of the reactor contents, at the jacket inlet and outlet, respectively. The proposed method for reaction heat estimation on were applied to industrial batch reactors ; one is ABS polymerization reactor and the other is SAN polymerization reactor. We have also examined the variation of overall heat transfer coefficients for the reactors during reaction.

• Journal of the Korean Institute of Intelligent Systems
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• v.15 no.5
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• pp.632-638
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• 2005

This paper describes a new data-handing, based on a Spatial Human Interface as human indicator, to the Spatial-Knowledge-Tags (SKT) in the spatial memory the Spatial Human Interface (SHI) is a new system that enables us to facilitate human activity in a working environment. The SHI stores human activity data as knowledge and activity history of human into the Spatial Memory in a working environment as three-dimensional space where one acts, and loads them with the Spatial-Knowledge-Tags(SKT) by supporting the enhancement of human activity. To realize this, the purpose of SHI is to construct new relationship among human and distributed networks computers and sensors that is based on intuitive and simultaneous interactions. In this paper, the specified functions of SKT and the realization method of SKT are explained. The utility of SKT is demonstrated in designing a robot motion control.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1600-1609
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• 2016

As the penetration of different types of renewable energy sources (RES) and energy storage systems (ESS) increases, the importance of stability in AC microgrid is being emphasized. Especially, RES and ESS which are operated using power electronics have difference in output characteristics according to control structures. When faults like single-line-to-ground fault or islanding operation occur, this means that a fault should be interpreted in different way. Therefore, it is necessary to analyze fault characteristics in AC microgrid in case of grid-connected mode and standalone mode. In this paper, the fault analysis for AC microgrid is carried out using PSCAD/EMTDC and an overvoltage problem and the countermeasures were proposed.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2039-2044
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• 2003

The advanced infrastructure for accelerating the development of personal robots is presented. Based on this structure, effective ways for integrating the various commercial components and interfacing among them are studied. The infrastructure includes the technology such as modularization based on independent processing and standardization open to other developers. The infrastructure supports not only that each hardware component of a personal robot can be easily attached to and detached from the whole system mechanically but also that each software of the components can be functionally distributed. As a result, we developed the fully modularized personal robots mechanically, and a virtual machine for the control of these robots. In this paper the proposed infrastructure and its implementations are described.