• Journal of Korean Society for Quality Management
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• v.26 no.2
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• pp.27-38
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• 1998

Consider a life testing experiment in which multiple two-component shared parallel systems are put on test, and the test is terminated at a specified number of system failures. The bivariate data obtained from such a system-level life testing can be classified into three classes: 1) the case of failed two components with known failure times, 2) the case of censored two components, and 3) the case of one censored component and the other failed component of which the failure time might be known or unknown. Under this censoring scheme and the assumption of Freund's bivariate exponential life distribution, the maximum likelihood estimators are obtained. Results of comparative studies based on Monte Carlo simulation are presented.

• The Journal of the Korea institute of electronic communication sciences
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• v.6 no.1
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• pp.142-147
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• 2011

In this paper, we make a RT component as a configuration element of cooperation robot of 7 degree of freedom manipulator using RTM which was adapted international standardization among the robot middleware technology. We implemented the one system by connecting the RT component of elements of a robot organize to each other based on middleware network and tested an operation of implemented system using the 7 degree of freedom manipulator which was real made.

• Journal of the Korean Data and Information Science Society
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• v.20 no.5
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• pp.941-948
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• 2009

We consider a life testing experiment in which several two component shared parallel system are put on test, and the test is terminated at a specified number of system failures. The bivariate data obtained from such a system level life testing can be classified into three classes: (1) the case of failed two components with known failure times, (2) the case of one censored component and the other failed component of which the failure time might be known or unknown, (3) the case of censored two components. In this thesis, the maximum likelihood estimators of parameters for Block and Basu bivariate exponential distribution under above censoring scheme are obtained. And the results of comparative studies are presented.

• Journal of Korean Institute of Industrial Engineers
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• v.21 no.4
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• pp.555-570
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• 1995

We consider a preventive replacement policy for a cold-standby system with N components, in which only one component is in operation at a time. If the component in operation fails, a standby component is immediately switched into operation. If all components fail, the system fails. The system is inspected at random poins in time to determine whether it is to be replaced or not. If the number of failed components at the time of inspection exceeds a threshold value r, the system is replaced. Otherwise the decision is put off until the next inspection point arrives. Under the cost structure which includes a replacement cost, a system down-time cost and a holding cost of the components, we develop an efficient procedure to find the optimal control values N and r, which minimize the expected cost per unit time.

• Journal of Applied Reliability
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• v.15 no.4
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• pp.233-240
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• 2015

We analyse reliability of multi-state UH-60 helicopter hydraulic pump system with a multi-functional standby component using Markov analysis method. The system consists of seven components: 2 main pumps, 1 standby pump, 2 primary servos, and 2 tail rotor servos. The standby pump can take over when one more than components fail. Therefore the standby pump is multi-functional standby component. The system has four states: good, deteriorated, dangerous, and failed. The components have 2 states: working and failed. We assume the system is unrepairable when the components fail. We estimate failure distributions and rates using collected failure time data in field. And we classify multi-state of the system according to emergency procedure of UH-60A student handout. We obtain the reliabilities of multi-state system using Visual Basic program because the differential equations is extremely complicated and tedious to solve.

• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.694-698
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• 2008

In hydrology, it is a difficult task to deal with multivariate time series such as modeling streamflows of an entire complex river system. Normal distribution based model such as MARMA (Multivariate Autorgressive Moving average) has been a major approach for modeling the multivariate time series. There are some limitations for the normal based models. One of them might be the unfavorable data-transformation forcing that the data follow the normal distribution. Furthermore, the high dimension multivariate model requires the very large parameter matrix. As an alternative, one might be decomposing the multivariate data into independent components and modeling it individually. In 1985, Lins used Principal Component Analysis (PCA). The five scores, the decomposed data from the original data, were taken and were formulated individually. The one of the five scores were modeled with AR-2 while the others are modeled with AR-1 model. From the time series analysis using the scores of the five components, he noted "principal component time series might provide a relatively simple and meaningful alternative to conventional large MARMA models". This study is inspired from the researcher's quote to develop a multivariate simulation model. The multivariate simulation model is suggested here using Principal Component Analysis (PCA) and Independent Component Analysis (ICA). Three modeling step is applied for simulation. (1) PCA is used to decompose the correlated multivariate data into the uncorrelated data while ICA decomposes the data into independent components. Here, the autocorrelation structure of the decomposed data is still dominant, which is inherited from the data of the original domain. (2) Each component is resampled by block bootstrapping or K-nearest neighbor. (3) The resampled components bring back to original domain. From using the suggested approach one might expect that a) the simulated data are different with the historical data, b) no data transformation is required (in case of ICA), c) a complex system can be decomposed into independent component and modeled individually. The model with PCA and ICA are compared with the various statistics such as the basic statistics (mean, standard deviation, skewness, autocorrelation), and reservoir-related statistics, kernel density estimate.

• Journal of the Korean Society for Aviation and Aeronautics
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• v.20 no.3
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• pp.35-43
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• 2012

Medium size rotorcraft consist of approximately 5,000 key components. The components must satisfy the target weight and performance requirement through optimization. Therefore a rotorcraft component has approximately 100 times higher unit cost for mass production than the equivalent of an automobile's, along with huge development cost. Configuration management consists of four main parts : configuration identification, configuration control, configuration audit, and data management. In development programme, configuration management is one of the methods to save development cost, and setting a well-structured configuration management system according to the Military Standard is an important factor in success of the programme. The paper proposes a configuration management system suitable for development of various multi-use components development and presents that the configuration management was performed successfully during dual-use component development programme using the established system.

• The KIPS Transactions:PartD
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• v.11D no.4
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• pp.929-936
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• 2004

A major limitation of available component-based platforms Is that they do not provide suitable means for describing and reasoning on the concurrent behaviour of interacting component-based system. Indeed while these platforms provide convenient ways to describe the typed signatures of components, e.g. like CORBA's IDL, they offer a quite low-level support to describe the concurrent behaviour of component. The ability to describe and verify the concurrent behaviour of interacting components is key aspect In the development of large component-based software system. This study propose a component interface specification using process algebra and configuration's role which allows one to prove correctness of software architecture generated at design level as well as to define compatibility relations by our evolution rule and $\pi$-graph. Also, we shown on an appropriateness of a specification techniques and definitions proposed in this paper by case-study.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.11
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• pp.1089-1095
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• 2010

We propose an image segmentation method for auto-teaching system of PCB (Printed Circuit Board) assembly inspection machines. The inspection machine acquires images of all components in PCB, and then compares each image with its standard image to find the assembly errors such as misalignment, inverse polarity, and tombstone. The component window that is the area of component to be acquired by camera, is one of the teaching data for operating the inspection machines. To reduce the teaching time of the machine, we newly develop the image processing method to extract the component window automatically from the image of PCB. The proposed method segments the component window by excluding the soldering parts as well as board background. We binarize the input image by use of HSI color model because it is difficult to discriminate the RGB colors between components and backgrounds. The linear combination of the binarized images then enhances the component window from the background. By use of the horizontal and vertical projection of histogram, we finally obtain the component widow. The experimental results are presented to verify the usefulness of the proposed method.

• Korean Journal of Computational Design and Engineering
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• v.2 no.1
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• pp.53-59
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• 1997

Current CAD systems used in the AEC community have some critical problems. One of them is that they hardly support design collaboration. Thus designers and engineers are hard to transfer design knowledge from one discipline to another. What we need is a common building database which creates and manages building plans/models and relevant design knowledge consistently and effectively. This paper presents a powerful CAD editor, called UNIFORM, which is being developed. Currently UNIFORM includes three main modules: a plan generator, a 3-D model generator, and component databases. A plan generator, called UNIFORM PLANNER, creates a plan which contains semantically-rich information of building. Each component in the plan can be presented in various ways and connected to component databases that contain knowledge of building components such as windows, doors, walls, etc. Based on the plan UNIFORM MODELER, another module of the program, generates a three dimensional building model which could be a multiple-story building. One of the main ideas behind the system is that it generates and maintains a common building form that can be easily delivered to other members of the project team. Thus it is expected to increase system integration, team interactions, and productivity.