• Journal of Korean Society of Water and Wastewater
• /
• v.20 no.1
• /
• pp.35-43
• /
• 2006

Concerns related to protecting, identifying, and isolating of subsystems of a water distribution network have led to the realization of the increased importance of valves in the system. The most important purpose of valves in water distribution systems is to isolate a subsystem due to breakage, maintenance activities, or contamination. A subsystem called segment is isolated by the closure of adjacent valves. Minimizing the pipe failure impact, an efficient algorithm is required to identify adjacent valves quickly. In this paper, an algorithm to identify adjacent valves to be closed to isolate a subsystem from the remainder of a network when a pipe failure is presented. The algorithm is operated on a matrix called the valve location matrix containing the information of valve locations. An application to an existing water distribution system demonstrates the developed algorithm efficiently locates the adjacent valves for the isolation of a broken pipe.

• Proceedings of the IEEK Conference
• /
• 2003.07a
• /
• pp.525-528
• /
• 2003

This paper describes the effective and rigorous analytic method of multipath effect which results from insufficient isolation characteristics between adjacent channels in communication payload system. It is very important to analyze the multipath effect for verifying the performance of transponder subsystem that especially is consist of multi channels. Finally the multipath effect are analyzed by calculating the GR and GDR for two adjacent channels of Ku-band transponder subsystem on the Communication & Broadcasting Satellite(CBS).

• Aerospace Engineering and Technology
• /
• v.12 no.2
• /
• pp.14-23
• /
• 2013

Fault management design of the satellite describes preparations for failures which can occur during operational phase. Fault management design contains detection and isolation function of anomaly, and also it contains function to maintain the satellite in safe condition until the ground station finds out a cause of failure and takes a countermeasure. Unlike normal operation, safing operation is automatically performed by Power Control and Distribution Unit and Integrated Bus Management Unit which loads Flight Software without intervention of ground station. Since fault management operation is automatical, fault management logic and functionality of relevant hardware should be thoroughly checked during ground test phase, and error which is similar to actual should be carefully applied without damage. Verification test for fault management design is conducted for various subsystems of satellite. In this paper, we show the design process of fault management design verification test for Electrical Power Subsystem and Attitude and Orbit Control Subsystem of Low Earth Orbit satellite flight model and the test results.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.15 no.2
• /
• pp.111-120
• /
• 2012

Built-In-Test is a design feature in more and more advanced weapon system. During development test and evaluation(DT&E) it is critical that the BIT system be evaluated. The BIT system is an integral part of the weapon system and subsystem. Built-In-Test assists in conducting on system and subsystem failure detection and isolation to the Line Replaceable Unit(LRU). This capability reduces the need for highly skilled personnel and special test equipment at organizational level, and reduces maintenance down-time of system by shortening Total Corrective Maintenance Time. During DT&E of weapon system the objective of BIT system evaluation is to determine BIT capabilities achieved and to identify deficiencies in the BIT system. As a result corrective actions are implemented while the system is still in development. Through the use of the reiterative BIT evaluation the BIT system design was corrected, improved, or updated, as the BIT system matured.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.27 no.4
• /
• pp.41-65
• /
• 2002

We study a multi-component production/inventory system in which individual components are made to meet various demand types. We assume that the demands arrive according to a Poisson process, but there is a fixed probability that a demand requests a particular kit of different components. Each component is produced by a flow line with several stations in which the processing times of each station follow a two-stage Coxian distribution. The production of each component is operated by an independent base-stock policy with blocking. We assume that the time needed to assemble final products follows a general distribution and the capacity of an assembling facility is sufficiently large. The objective of this study is to obtain key performance measures such as the distribution of the number of each orders for each final product and the mean time of fulfilling a customer order. The basic principle of the proposed approximation method is to decompose the original system into a set of subsystems, each subsystem being associated with a flow line. Each subsystem is analyzed in isolation using a Marie's method. An iterative procedure is then used to determine the unknown parameters of each subsystem. Numerical results show that the accuracy of the approximation method is acceptable.

• Proceedings of the Korea Society for Simulation Conference
• /
• 1999.04a
• /
• pp.47-52
• /
• 1999

In this paper we propose new approximate method for the performance analysis of closed-loop production system with unreliable machines and random processing times. The approximate method decomposes the production system consisting of K machines into a set of K subsystems, each subsystem consisting of two machines separated by a finite buffer. Then, each subsystem is analyzed by analyzing method n isolation. The population constraint of the closed-loop production system is taken into account by prescribing that the sum of average buffer level in the subsystems is equal to the number of customers in the closed-loop production system,. We establish a set of equations that characterizes unknown parameters of the servers in the subsystems. An iterative procedure is then used to determine the unknown parameters. Experimental results show that these methods provide a good estimation of the throughput.

• Journal of Korean Institute of Industrial Engineers
• /
• v.25 no.2
• /
• pp.240-253
• /
• 1999

In this paper we propose new approximate methods for the performance analysis of closed-loop production systems with unreliable machines and random processing times. Each approximate method decomposes the production system consisting of K machines into a set of K subsystems, each subsystem consisting of two machines separated by a finite buffer. Then, each subsystem is analyzed by three different analyzing methods in isolation. The population constraint of the closed-loop production system is taken into account by prescribing that the sum of average buffer levels in the subsystems is equal to the number of customers in the closed-loop production system. We establish a set of equations that characterize unknown parameters of the servers in the subsystems. An iterative procedure is then used to determine the unknown parameters. Experimental results show that these methods provide a good estimation of the throughput.

• 제어로봇시스템학회:학술대회논문집
• /
• 2001.10a
• /
• pp.116.1-116
• /
• 2001

In the near future, drive-by-wire systems will replace mechanical systems of vehicles. Since there would be no mechanical redundancy in the x-by-wire subsystem, it needs to improve the reliability of the system using fault diagnosis of sensors and actuators. This paper proposes a Kalman filter based fault diagnosis method for the vehicle with the drive-by-wire system, which includes steer-by-wire, brake-by-wire and throttle-by-wire systems. We will show that the proposed method is successful in fault detection and isolation for single sensor/actuator faults of the vehicle system.

• Journal of Family Resource Management and Policy Review
• /
• v.5 no.1
• /
• pp.141-150
• /
• 2001

This study applicates one of the five elaborated functional analyses of Piotr Stztompka to the housewives’study. The four general assumptions of plurality, wholeness, integration and boundary of the simple system issue the eight specific solutions; reciprocity, exploitation, consensus, conflict, dependence, autonomy, isolation and structural context of the relationships among the various elements of the system. From the eight specific assumptions of the housewives’studies, we have found that many managerial subsystem studies see the housewives’relationships to other elements in their reciprocity, concensus, dependence and isolation characteristics. If the assumptions of autonomy and structual context are used to this kind of study, we can understand the housewives’problem and potential but as an active subject of their humanlives, not as a simply passive primary manager of the family, and we can find a new concept of the development to change the housewives’quality of life.

• Structural Engineering and Mechanics
• /
• v.43 no.4
• /
• pp.475-502
• /
• 2012

In this paper, the seismic analysis modeling technologies for sodium-cooled fast reactor (SFR) are presented with detailed descriptions for each structure, system and component (SSC) model. The complicated reactor system of pool type SFR, which is composed of the reactor vessel, internal structures, intermediate heat exchangers, primary pumps, core assemblies, and core support structures, is mathematically described with simple stick models which can represent fundamental frequencies of SSC. To do this, detailed finite element analyses were carried out to identify fundamental beam frequencies with consideration of fluid added mass effects caused by primary sodium coolant contained in the reactor vessel. The calculation of fluid added masses is performed by detailed finite element analyses using FAMD computer program and the results are discussed in terms of the ways to be considered in a seismic modeling. Based on the results of seismic time history analyses for both seismic isolation and non-isolation design, the functional requirements for relative deflections are discussed, and the design floor response spectra are proposed that can be used for subsystem seismic design.