• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.1297-1302
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• 2000

A literature review has been carried out to investigate why bridges have collapsed without warning. The reasons behind the collapses have been categorized into short and long term risks. It is thought that permanent monitoring systems which assess structural adequacy are more appropriate to long term risks. From the knowledge of the Korean bridge stock, its current problems and its likely future problems, it was considered that generally the most useful application for a permanent monitoring system is to monitor where chloride-induced corrosion either of the reinforcement or prestressing tendons is possible. A number of permanent monitoring systems currently in use on existing bridges which include some aspect of corrosion detection have been reviewed. The reasons as to why they are being used, what is being measured, what techniques are being used, and if they are deemed successful has been investigated. Based on these findings, and experimental programme has been constructed to investigate the accuracy, reliability and usefulness of various suitable techniques which could be included in a permanent monitoring system.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.38 no.1
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• pp.110-117
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• 2015

Spare part management is very important to products that have large number of parts and long lifecycle such as automobile and aircraft. Supply chain must support immediate procurement for repair. However, it is not easy to handle spare parts efficiently due to huge stock keeping units. Qualified forecasting is the basis for the supply chain to achieve the goal. In this paper, we propose an agent based modeling approach that can deal with various factors simultaneously without mathematical modeling. Simulation results show that the proposed method is reasonable to describe demand generation process, and consequently, to forecast demand of spare parts in long-term perspective.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.258-263
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• 2005

The purpose of this research is to present a practical method for efficiently monitoring a reliability growth process using AMSAA(Army Materiel Systems Analysis Activity) reliability growth model. The presented method is viable for identifying failure modes, incorporating design changes and monitoring reliability progress on an on-going basis during the early stages of a product development program. According to the Application Guide for EN 50126(RAM part for Rolling Stock), reliability growth monitoring is essential part of the main tasks of design phase in RAM growth monitoring. Implementation of reliability growth management program will provide very useful information on concept selection, product/process reliability, and cost effectiveness without too much time, money and engineering effort being spent on the development of failure suspect parts.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.218-219
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• 2007

Silicon feed stock shortage have acted as major restraints for growth of photovoltaic industry. Concentrating photovoltaic (CPV) system will reduce the use of silicon PV materials. This paper presents the application possibility of mono-crystalline silicon solar cell, which has increased in market share, for PV concentrator. We measured the power of solar cell using sun simulator and I-V curve tracer and compared the results. The comparison of results showed that the concentrated solar cell generated the power more approximately 7 times than without concentration in spite of non-heat sink. If CPV technology included heat sink combines already developed PV tracking system, it will have a merit economically.

• Industrial Engineering and Management Systems
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• v.7 no.1
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• pp.44-50
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• 2008

Focusing on the exponential smoothing method equivalent to (1, 1) order ARMA model equation, a new method of estimating smoothing constant using exponential smoothing method is proposed. This study goes beyond the usual method of arbitrarily selecting a smoothing constant. First, an estimation of the ARMA model parameter was made and then, the smoothing constants. The empirical example shows that the theoretical solution satisfies minimum variance of forecasting error. The new method was also applied to the stock market price of electrical machinery industry (6 major companies in Japan) and forecasting was accomplished. Comparing the results of the two methods, the new method appears to be better than the ARIMA model. The result of the new method is apparently good in 4 company data and is nearly the same in 2 company data. The example provided shows that the new method is much simpler to handle than ARIMA model. Therefore, the proposed method would be better in these general cases. The effectiveness of this method should be examined in various cases.

• Communications for Statistical Applications and Methods
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• v.22 no.4
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• pp.321-331
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• 2015

The K-means clustering algorithm is a popular and widely used method for clustering. For covariance matrices, we consider a geodesic clustering algorithm based on the K-means clustering framework in consideration of symmetric positive definite matrices as a Riemannian (non-Euclidean) manifold. This paper considers a geodesic clustering algorithm for data consisting of symmetric positive definite (SPD) matrices, utilizing the Riemannian geometric structure for SPD matrices and the idea of a K-means clustering algorithm. A K-means clustering algorithm is divided into two main steps for which we need a dissimilarity measure between two matrix data points and a way of computing centroids for observations in clusters. In order to use the Riemannian structure, we adopt the geodesic distance and the intrinsic mean for symmetric positive definite matrices. We demonstrate our proposed method through simulations as well as application to real financial data.

• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.521-524
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• 2019

온라인상의 사진 저작물들은 쉬운 복제와 수정으로 인하여 지적재산권에 많은 침해를 입히고 있다. 본 논문에서는 사진가들의 저작권을 보호하고 사용자의 편리성을 제공하는 스톡사진 어플리케이션을 설계하고 구현하였다. 본 논문에서 설계하고 개발한 어플리케이션은 사진을 업로드/다운로드 할 수 있으며, 사진의 저작권을 인정할 수 있도록 사진의 정보를 담아 사용자의 거래 간에 사진의 정보도 같이 전송한다.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1562-1569
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• 2008

In this paper, the study on development of an applicable logic on the characteristics of Rolling stocks will be proposed. In general, this logic which means decision logic or LTA(Logic Tree Analysis) is used to analyze how the failure mode have an effects on the system. The effect would be categorized as safety, operational, economical, etc. To do this, based on the typical logics which have been applied to other industries, such as plants, aero, etc. This paper emphasizes two crucial parameters that is one cost the other customer service, that have an important role in railway system operation. In conclusion, as mentioned above as the logic for which could be effectively applied for the railway system(RST) would be developed.

• The Journal of Asian Finance, Economics and Business
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• v.8 no.3
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• pp.451-458
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• 2021

The objective of this research is to analyze the effect of bad credit and liquidity on bank performance with the mediation of capital adequacy. Data were provided by banking institutions listed on the Indonesia Stock Exchange from the period of 2011-2019. The analysis technique was PLS-SEM supported by an application named WarpPLS 6.0. The results of the research show that the effect of bad credit and liquidity on bank performance is not significant. A high level of bad credit is associated with a low level of bank performance. Bank earnings decline along with low profitability. This relationship is not significant because banks can still cover some proportions of bad credit through capital availability. Capital adequacy as an intervening variable has mediated partially the effect of bad credit and liquidity on bank performance. Besides, capital adequacy has a strong effect on credit distribution. Agency theory says that the owner of the fund (the savers of saving account, current account, deposit account) is called principal while the bank as the trusted institution to manage the fund is called an agent. If customers fulfill their duty, then bad credit never happens.

• Journal of Korean Society of Forest Science
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• v.99 no.3
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• pp.285-291
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• 2010

Since 2006, the $5^{th}$ National Forest Inventory (NFI) has been implemented to provide forest resources statistics at the national level and at the county level as well. However, it needs a small-area estimator for estimating forest statistics at the county-level due to a small number of samples collected within a county. This study was conducted to evaluate the applicability of a geographical-based synthetic estimator for estimating forest growing stock volumes at the county level. The NFI-field plots surveyed were post-stratified into three forest cover types. In the synthetic estimator, field plots within a geographical-based super-county for each county were used to estimate stratum weights and stratum mean volumes. It was resulted that estimated stratum weights using the synthetic estimation were significantly differ from forest cover maps. The standard errors of estimated mean by the synthetic estimation that ranged from ${\pm}3.5\;m^3$/ha to ${\pm}7.7\;m^3$/ha were more smaller than those (${\pm}7.8\;m^3/ha{\sim}{\pm}24.7\;m^3/ha$) by the direct estimation. This means that the synthetic estimation is possible to provide more precise estimates of mean volumes.