• Communications for Statistical Applications and Methods
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• v.17 no.6
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• pp.811-827
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• 2010

This paper deals with a density estimation method in binary choice models that can be regarded as a statistical inverse problem. We use an orthogonal basis to estimate density function and consider the choice of an appropriate truncation parameter to reflect the model complexity and the prediction accuracy. We propose a data-dependent rule to choose the truncation parameter in the context of binary choice models. A numerical simulation is provided to illustrate the performance of the proposed method.

• Journal of the Korean Society for Precision Engineering
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• v.11 no.6
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• pp.179-184
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• 1994

In this study a nondimensional parameter, feed/land length(F/L) was introduced, and using this parameter, cutting performance and chip breaking characteristics of the groove and the land angle type chip formers were assessed. Specific cutting energy consumed and shape of broken chip with its breaking cycle time were appraised to find out the ranges of F/L value where efficient cutting and effective chip breaking could be achieved. C type chip was found out to be the most preferable in terms of cutting efficiency.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.11a
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• pp.231-232
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• 2022

Pavement cutting work frequently occurs in new building construction, reconstruction, and complex construction, and this work causes a lot of noise and dust. Eco-friendly pavement cutters are being developed to reduce noise and dust in this work, however the on-site cutting performance of the equipment under development has not been quantified. In this study, the eco-friendly pavement cutter was applied to four residential areas in Seoul and Gyeonggi-do, and its cutting performance was quantified. As a result of the analysis, the eco-friendly pavement cutter showed cutting performance of 20.1~46.9sec/m, and the average was 33.5sec/m. In the future, we plan to conduct additional cutting experiments with various mixing ratios, materials, and depths to confirm the performance of eco-friendly road cutters in more detail.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2008.11a
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• pp.111-113
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• 2008

반도체 산업에 있어 package 절단에 사용되는 diamond micro blade의 성능은 그 반도체의 자체적 성능에서뿐만 아니라 생산 비용 등에 있어서도 매우 중요한 비중을 차지하고 있다. 이러한 블레이드의 성능향상을 위해 윤활첨가제(흑연, $MoS_2$)의 첨가효과에 대해 마모성능시험을 통해 알아보고 비교 분석을 행하였다. 그 결과 윤활첨가제의 첨가를 통해 절삭 중 블레이드 표면에서 발생할 수 있는 응착 마멸현상이 줄어들었음을 확인할 수 있었고, 윤활첨가제의 적절한 첨가량에 대해 재조명 해 볼 수 있었다.

• The Korean Journal of Applied Statistics
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• v.28 no.3
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• pp.467-475
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• 2015

Accurate demand forecasting is a crucial component in revenue management(RM). The booking data of departed flights is used to forecast the demand for future departing flights; however, some booking requests that were denied were omitted in the departed flights data. Denied booking requests can be interpreted as censored in statistics. Thus, unconstraining demand is an important issue to forecast the true demands of future flights. Several unconstraining methods have been introduced and a method based on expectation maximization is considered superior. In this study, we propose a new unconstraining method based on a regression model that can entertain such censored data. Through a simulation study, the performance of the proposed method was evaluated with two representative unconstraining methods widely used in RM.

• The Korean Journal of Applied Statistics
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• v.25 no.2
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• pp.261-267
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• 2012

In constructing a credit scorecard, each characteristic variable is divided into a few attributes; subsequently, weights are assigned to those attributes in a process called coarse classification. While partitioning a characteristic variable into attributes, one should determine appropriate cutpoints for the partition. In this paper, we propose a cutpoint selection method via penalization. In addition, we compare the performances of the proposed method with classification spline machine (Koo et al., 2009) on both simulated and real credit data.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.6
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• pp.102-112
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• 2012

Recently, the near surface mounted (NSM) FRP strengthening technique has been actively applied to deteriorated concrete structures for rehabilitation purposes. However, the use of this conventional NSM technique could be restricted due to the insufficient height or strength of the concrete cover. In this study, the stirrup-Cutting Near Surface Mounted(CNSM) technique was considered as an alternative, whereby NSM strips are placed at a deeper level, namely at the level of the main steel reinforcement. A flexural test of a concrete beam strengthened with CNSM technique was performed and the results were then compared to those for a concrete beam strengthened by the conventional NSM technique. The embedment length of the CFRP strips was varied in order to increase the effect of the anchoring depth of the NSM and CNSM CFRP strips in the beam specimens. From the results of the test, the beam with the CNSM CFRP strip showed typical structural behavior similar to that of the beam with the NSM CFRP strip. Moreover, there was no apparent structural degradation resulting from the stirrup partial-cutting. Consequently, the CNSM strengthening technique can be suitably utilized for extensively damaged concrete structures where it is difficult to apply the conventional NSM technique.

• The Korean Journal of Applied Statistics
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• v.34 no.5
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• pp.735-744
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• 2021

Maintaining the lifetime of a product is one of the objectives of quality control. In real processes, most samples are constructed with censored data because, in many situations, we cannot measure the lifetime of all samples due to time or cost problems. In this paper, we propose two cumulative sum (CUSUM) control charting procedures to monitor the mean of type I right-censored lognormal lifetime data. One of them is based on the likelihood ratio, and the other is based on the binomial distribution. Through simulations, we evaluate the performance of the two proposed procedures by comparing the average run length (ARL). The overall performance of the likelihood ratio CUSUM chart is better, especially this chart performs better when the censoring rate is low and the shape parameter value is small. Conversely, the binomial CUSUM chart is shown to perform better when the censoring rate is high, the shape parameter value is large, and the change in the mean is small.

• Photonics industry news
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• s.2
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• pp.52-55
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• 2001

본지에서는 연구개발정보센타(KORDIC)의 자료협조를 받아 광산업과 관련된 해외기술 동향들을 소개한다.

• Explosives and Blasting
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• v.36 no.1
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• pp.1-11
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• 2018

In this study, several underwater steel cutting tests and AUTODYN numerical analyses were conducted to evaluate the penetration performance of a shaped charge device. Parameter analyses for the contribution rate were conducted by using the robust design method. The parameters adopted in this study were chamber type, stand-off, and wire setting, each of which had three levels in the analysis. Analysis results showed that the contribution rate was most affected by the stand-off, followed by the chamber type and wire setting. Experiments of underwater steel cutting were conducted at water depth of 25m. As expected, the experiments and numerical simulation showed similar results for underwater steel cutting performance, and thus the feasibility of the shaped charge device for underwater steel cutting at deep water depth was verified.