• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1996.04a
• /
• pp.15-18
• /
• 1996

Shewhart control chart is a basic technique to monitor the state of a process. We observe observations of a group of size four or five in a rational way and plot some statistics (e.g., means and ranges) on the chart. When setting up the control chart, the control limits are calculated based on preliminary 20-40 samples, which were supposedly obtained from stable operating conditions. But it may be hard to believe, especially at the beginning of constructing the chart for the first time, whether the process is stable and hence all samples were generated under the homogeneous operating conditions. In this report we suggest a mechanism to obtain robust control limits under self-criticism. When outliers are present in the sample, we obtain tighter control limits and hence increase the sensitivity of the chart. Examples will be given via simulation study.

• Proceedings of the KIEE Conference
• /
• 2008.05a
• /
• pp.147-148
• /
• 2008

In this paper, we calculated the axial magnetic field at mid-gap plane between upper and lower electrode in vacuum interrupter by means of commercial finite element method Maxwell 3D and compared on the basis of "effective area" criterion. The models used in this paper are coil type(axial magnetic field) vacuum interrupter electrodes which have different numbers of coil segment. We used Dr. Schulmann's experimental equation which indicates minimum critical value of axial magnetic field to diffuse arc.

• Proceedings of the Korean Operations and Management Science Society Conference
• /
• 1995.04a
• /
• pp.252-269
• /
• 1995

Organizational decision support systems(ODSS) are a new type of decision support systems(DSS) focusing on the organization-wide issues rather than individual, group, or departmental issues. Because of its organization-wideness, which means an ODSS cuts across organizational functions or hierarchical layers, seamless integration with organization's diverse IS applications running on heterogeneous platforms becomes a critical issue. In this paper, we analyzed the Korea Telecom(KT)'s Operations & Maintenance(O&M) division focusing on its investment strategies. We developed a conceptual framework which links O&M investment to its performance. We also developed a prototype of KTOM-ODSS with an EIS-like user-friendly interface.

• The KIPS Transactions:PartD
• /
• v.8D no.1
• /
• pp.62-70
• /
• 2001

Correct descriptions for software component functions become a strong requirement in developing critical software especially on the area of real-time applications. In this paper, we introduce both formalization of software design using patterns and verification methods in order for the components to increase their understandability. In particular, the paper investigates into a means of formal description techniques based on VDM++ for the software components, and provides adequacy proof steps for a given functional descriptions.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2007.08b
• /
• pp.1688-1691
• /
• 2007

This paper shows that the boundary image sticking can be prohibited completely by using the vacuum sealing process, which means that the residual impurities such as nitrogen or oxygen can be a critical factor inducing the boundary image sticking. The production of boundary image sticking was checked in the test panel fabricated by the $N_2$ or $O_2$ flow during the vacuum sealing process. As a result, the boundary image sticking did not appear in the case of $N_2flow$, whereas the boundary image sticking was observed in the case of $O_2$ flow even though the test panel was fabricated by the vacuum sealing process.

• Journal of the Korean Institute of Educational Facilities
• /
• v.19 no.5
• /
• pp.37-43
• /
• 2012

Results of experiments conducted in university-based design studio suggests that Building information Modeling invites the adoption of a dramatically different design process, traditional design process and BIM-aided design process. Experiment method is used the actual experiment by students. In contrast to traditional design process rooted in successive refinement of abstractions and dependence on tacit knowledge, the studio BIM-aided design process depends on a complete and comprehensive date base and alterative solutions by complete analysis for helping choice of finial result. BIM viewed as provocateur of design education provides great potential for the critical analysis of how architectural design is taught. The results reflect new ways of teaching and addressing BIM methods and process in the design studio project.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.04a
• /
• pp.49-53
• /
• 1997

In this paper, YbBa$_{2}$Cu$_{3}$O$_{x}$ superconductor was sintered by means of conventional solid reaction and the textured YbBa$_{2}$Cu$_{3}$O$_{x}$ was prepared by the Melted-Condensed Process in which SmBa$_{2}$Cu$_{3}$O$_{x}$ crystal was used as seed crystal to introduce the YbBa$_{2}$Cu$_{3}$O$_{x}$ crystal growth. The texture of YbBa$_{2}$Cu$_{3}$O$_{x}$ was examined by X-ray diffraction, and the fracture of YbBa$_{2}$Cu$_{3}$O$_{x}$ sample was observed by SEM, which proved the sample was well oriented. After oxygen absorption of the textured YbBa$_{2}$Cu$_{3}$O$_{x}$ sample, it's critical temperature was measureed to be 86K.eed to be 86K.

• Proceedings of the KSR Conference
• /
• 2004.06a
• /
• pp.865-871
• /
• 2004

The safety evaluations of railway wheel sets make use of the static fracture toughness obtained in ingot materials. The static fracture toughness of wheelset materials has been extensively studied by experiments, but the dynamic fracture toughness with respect to wheel set materials has not been studied enough yet. It is necessary to evaluate the characteristics of the fracture mechanics depending on each location for a full-scale wheel set for high-speed trains, because the load state for each location of the wheel set while running is different the contact load between the wheel and rail, cyclic stress in the wheel plate, etc. This paper deals with the fracture toughness depend on load rates. The fracture toughness depending on load rate data shows that once the downward curve from quasi-static values was reached, subsequent values showed a slow increase with respect to the impact velocity. This means that dynamic fracture toughness should be considered in the design code of the wheelset material.

• Journal of the Korean Statistical Society
• /
• v.13 no.1
• /
• pp.48-56
• /
• 1984

This paper considers one-sample and two-sample test for the logistic function by means of Kolmororov-Smirnov type statistics. The standard tables used for the Kolmogorov-Smirnov test are valid only when the function is completely specified; but they are not valid if the parameters of function are estimated from the sample. This note presents modified tables for the Kolmogorov-Sminov type staistic. These tables can be used to test the hypothesis that a sample comes from a logistic function when shape parameter $(\alpha)$ and location parameter $(\beta)$ must be estimated from the sample by the method of maximum likelihood. Monte Carlo method is employed to calculate the criticla values of the test. The tables of the critical values are provided.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2004.10a
• /
• pp.429-436
• /
• 2004

For the in-situ health monitoring of critical members in civil infra-structures, ultrasonic guided Lamb waves-based non-destructive evaluation (NDE) is very suitable. However, a chief drawback of the Lamb wave techniques is that multiple modes exist at all frequencies and the modes are generally dispersive, which means that the received signals may be very complicated. To overcome these complications, selective transmitting and receiving of a single A/sub 0/ mode within a frequency range can be adopted. Furthermore, a wavelet technique can be utilized to decompose the Lamb wave response into wavelet coefficients as a tool for signal processing. The changes in the Lamb waves interacting with damages in the steel plates are successfully characterized by this wavelet technique, through the amplitude change of the wavelet coefficients. In this paper, the feasibility of detecting a line crack on the surface of a steel plate and loosened bolts in a joint steel specimen using the Lamb waves and the wavelet technique is investigated.