• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.11a
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• pp.360-361
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• 2005

Rapid progress in IC fabrication technology has strong demand in polishing of silicon wafer to meet the tight specification of nanotopography and surface roughness. One of the important issues in Si CMP is the stabilization of polishing pad. If a polishing pad is not stabilized before main Si wafer polishing process, good polishing result can not be expected. Therefore, new pad must be subjected into break-in process using dummy wafers for a certain period of time to enhance its performance. After the break-in process, the main Si wafer polishing process must be performed. In this study, the characteristics of break-in process were investigated in Si wafer polishing. Viscoelastic behavior, temperature variation of pad and friction were measured to evaluate the break-in phenomenon. Also, it is found that the characteristic of the break-in seems to be related to viscoelastic behavior of pad.

• Communications for Statistical Applications and Methods
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• v.19 no.1
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• pp.177-182
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• 2012

A structural break in the level as well as in the innovation variance has often been exhibited in economic time series. In this paper we propose robust unit root tests based on a sign-type test statistic when a time series has a shift in its level and the corresponding volatility. The proposed tests are robust to a wide class of partially stationary processes with heavy-tailed errors, and have an exact binomial null distribution. Our tests are not affected by the size or location of the break. We set the structural break under the null and the alternative hypotheses to relieve a possible vagueness in interpreting test results in empirical work. The null hypothesis implies a unit root process with level shifts and the alternative connotes a stationary process with level shifts. The Monte Carlo simulation shows that our tests have stable size than the OLSE based tests.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2000.06a
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• pp.159-165
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• 2000

In this paper the residual stresses on lubricated sliding surfaces were measured during break-in procedure and up to scuffing by the X-ray diffraction method. The cylinder-on-disk type tribometer was used with the line-contact geometry. Scuffing tests were done using a constant load. In the break-in procedure the loads were increased from very low values in several steps. It was found that the sliding surfaces with break-in represented relatively higher values of residual compressive stresses than those without break-in. The residual stresses below the surfaces showed the small amount of stress increases. The results of scuffing tests with and without break-in showed the same trends as break-in tests did. However, in case of tests with break-in procedure the stresses below the surfaces showed very large increases in the residual compressive stresses. From the tests of break-in and scuffing, it was found that the increases in scuffing lives were related with the increases of residual stresses on the lubricated sliding surfaces with break-in.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.983-984
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• 2008

This paper proposes a variable break that can offset prediction error as well as a pre-selection methods, based on the variable break, for enhanced unit selection. In Japanese, a sentence consists of several APs (Accentual phrases) and MPs (Major phrases), and the breaks between these phrases must predicted to realize text-to-speech systems. An MP also consists of several APs and plays a decisive role in making synthetic speech natural and understandable because short pauses appear at its boundary. The variable break is defined as a break that is able to change easily from an AP to an MP boundary, or from an MP to an AP boundary. Using CART (Classification and Regression Trees), the variable break is modeled stochastically, and then we pre-select candidate units in the unit-selection process. As the experimental results show, it was possible to complement a break prediction error and improve the naturalness of synthetic speech.

• ETRI Journal
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• v.29 no.4
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• pp.527-529
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• 2007

In this paper, a decision-tree-based Markov model for phrase break prediction is proposed. The model takes advantage of the non-homogeneous-features-based classification ability of decision tree and temporal break sequence modeling based on the Markov process. For this experiment, a text corpus tagged with parts-of-speech and three break strength levels is prepared and evaluated. The complex feature set, textual conditions, and prior knowledge are utilized; and chunking rules are applied to the search results. The proposed model shows an error reduction rate of about 11.6% compared to the conventional classification model.

• Journal of Applied Reliability
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• v.13 no.3
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• pp.165-174
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• 2013

Thruster break for aerogenerator performs a role that is stopping the rotor in case of emergency such as strong wind, system abnormality or maintenance check. In this study, failure analysis and test evaluation on the thruster break for aerogenerator are proposed, and the entire process to improve reliability of the product through design improvement is presented. The typical failure case is fatigue and wear, and failure cause on these are identified and improvement plan is presented. Lastly, reliability improvement is established to analyse test results before after the life test.

• Journal of Korea Water Resources Association
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• v.39 no.5 s.166
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• pp.383-394
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• 2006

This study is for the inundation damage analysis caused by levee break, and for the applicability of GIS tool to make inundation map in the Jungrang stream basin which is one of the representative urbanized area in Korea. The FLDWAV was applied to the actual flood in 1998 to calibrate the parameters, and was used under the flood conditions of 100, 200 years and PMF for the analysis of inundation caused by the levee breach. As the conditions of the levee break, the duration of break(10, 30, 60 min), the width of break(10, 20, 30m) and the location of the break are considered. We found out that the range and the volume of the inundation are strongly influenced by the location of the levee break, the break width in order. And, we compared the two processes of making the inundation map using WMS and ArcView model. The Process 1 which use only WMS has the benefit by its simplicity but there could be considerable errors in making the inundation map, while Process 2 where the ArcView model is introduced to WMS has the capability of making detailed topography map but needs more process time. This study could contribute to levee breach flood analysis and making flood map to establish the EAP(Emergency Action Plan) in the urban basin.

• The Journal of the Acoustical Society of Korea
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• v.26 no.8
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• pp.403-408
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• 2007

In a large corpus-based speech synthesizer, a break, which is a parameter influencing the naturalness and intelligibility, is used as an important feature during a unit selection process. Japanese is a language having intonations, which ate indicated by the relative differences in pitch heights and the APs(Accentual Phrases) are placed according to the changes of the accents while a break occurs on a boundary of the APs. Although a break can be predicted by using J-ToBI(Japanese-Tones and Break Indices), which is a rule-based or statistical approach, it is very difficult to predict a break exactly due to the flexibility. Therefore, in this paper, a method is to conduct a unit search by dividing breaks into two types, such as a fixed break and a flexible break, in order to use the advantages of a large-scale corpus, which includes various types of prosodies. As a result of an experiment, the proposed unit selection method contributed itself to enhance the naturalness of synthesized speeches.

• Journal of Korea Water Resources Association
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• v.42 no.7
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• pp.571-578
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• 2009

Levee-break Analysis model is developed to predict the variation of breach width according to time and to estimate inundation area and depth in protected lowland. This Model calculate flood depth using 4 point implicit finite difference method in river channel and analyze breach flow based on physical theory introducing soil transport equation and erosion process. Breach analysis model and channel flood model are combined into Levee-Break Model and this model is applied to actual levee break case. Then, this model can simulate reasonably many levee-break parameters such as river stage, breach width, breach formation and so on. If the applicability of this model is proved through applications to more various actual levee-break cases, the suggested model is expected to do more accurate flood analyses on levee break site.

• Nuclear Engineering and Technology
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• v.36 no.5
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• pp.388-402
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• 2004

A phenomena identification and ranking table(PIRT) was developed for a main steam line break (MSLB) event for the Advanced Power Reactor-1400 (APR-1400). The selectee event was a double-ended steam line break at full power, with the reactor coolant pump running. The developmental panel selected the fuel performance as the primary safety criterion during the ranking process. The plant design data, the results of the APR-1400 safety analysis, and the results of an additional best-estimate analysis by the MARS computer code were used in the development of the PIRT. The period of the transient was composed of three phases: pre-trip, rapid cool-down, and safety injection. Based on the relative importance to the primary evaluation criterion, the ranking of each system, component, and phenomenon/process was performed for each time phase. Finally, the knowledge-level for each important process for certain components was ranked in terms of existing knowledge. The PIRT can be used as a guide for planning cost-effective experimental programs and for code development efforts, especially for the quantification of those processes and/or phenomena that are highly important, but not well understood.