• Journal of Korean Society for Quality Management
• /
• v.24 no.2
• /
• pp.172-178
• /
• 1996

In this study, we developed a software for statistical process control. This software presents $\bar{x}$, R, CUSUM, EWMA control chart and process capability index. In this system, statistical process control methods are integrated into the automated method on a real time base. It is available in process control of specified type and can be performed on personal computer with network system.

• Proceedings of the KSR Conference
• /
• 2008.11b
• /
• pp.1126-1131
• /
• 2008

In this paper we introduce an applicable RCM(Reliability centered maintenance) method for Track circuit equipment of AREX's Signalling System. AREX computerize all the process of FRACAS(Failure Reporting, Analysis and Corrective Action System)) by the Facility Management System of Integrated Information System. These datum were analysed and reproduced as the RAMS index value which can be used by maintenance staff for optimizing the maintenance method of the System.

• Journal of Yeungnam Medical Science
• /
• v.23 no.2
• /
• pp.205-212
• /
• 2006

Background: Malignant pulmonary nodules account for about 30 to 40 percent of solitary pulmonary nodules (SPN). Therefore, tissue characterization of SPNs is very important. Recently, PET/CT has been widely used for tissue characterization, and has become of importance. The purpose of this study was to compare and to assess multiple factors in PET/CT comparing benign and malignant nodules. Materials and Method: Nineteen patients with SPN underwent PET/CT and biopsy. The difference of standardized uptake value 1 (SUV1), standardized uptake value 2 (SUV2) and retention index in PET/CT between malignancy and benignancy were compared by Levene's test. Result: There were twelve malignant and seven benign nodules. SUV1 and SUV2 were significantly different between malignant nodule and benign nodule (p=0.006 and 0.022), but retention index was not significantly different between malignant nodule and benign nodule (p=0.526). By receiver-operating-characteristic (ROC) analysis, the sensitivity was 66.7% and the specificity was 71.4% at a cut off value of 5.40 in SUV1. The sensitivity was 75% and the specificity was 71.4% at cut off value of 7.45 in SUV2. Conclusion: There was a statistically significant difference in SUV1 and SUV2 between benign and malignant nodules. However, the cut off value of SUV1 and SUV2 by receiver-operating-characteristic (ROC) analysis was 5.40 and 7.45 which is different from previous studies. Therefore, studies on a larger sample of patients are required for confirmation.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.20 no.4
• /
• pp.348-356
• /
• 2018

Most of fires were human-caused fires in Korea, but meteorological factors are also big contributors to fire behavior and its spread. Thus, meteorological factors as well as topographical and forest factors were considered in the fire danger rating systems. This study aims to develop an advanced national integrated daily weather index(DWI) using weather data in the spring and fall to support forest fire prevention strategy in South Korea. DWI represents the meteorological characteristics, such as humidity (relative and effective), temperature and wind speed, and we integrated nine logistic regression models of the past into one national model. One national integrated model of the spring and fall is respectively $[1+{\exp}\{-(2.706+(0.088^*T_{mean})-(0.055^*Rh)-(0.023^*Eh)-(0.014^*W_{mean}))\}^{-1}]^{-1}$, $[1+{\exp}\{-(1.099+(0.117^*T_{mean})-(0.069^*Rh)-(0.182^*W_{mean}))\}^{-1}]^{-1}$ and all weather variables significantly (p<0.01) affected the probability of forest fire occurrence in the overall regions. The accuracy of the model in the spring and fall is respectively 71.7% and 86.9%. One integrated national model showed 10% higher accuracy than nine logistic regression models when it is applied weather data with 66 random sampling in forest fire event days. These findings would be necessary for the policy makers in the Republic of Korea for the prevention of forest fires.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2009.05a
• /
• pp.236-239
• /
• 2009

우리나라는 계절적으로 편중된 강우특성 때문에 가용 수자원이 충분하지 않고 최근엔 빈번하게 발생하는 이상기후현상과 국지성기후로 인해 가뭄의 빈도 및 강도가 증대되고 있어 기후변화에 적응할 수 있는 농촌용수 물관리 대책과 가뭄대응능력 개선의 필요성이 요구되고 있다. 이러한 가뭄의 관리를 위해서는 시간적인 가뭄의 발생과 공간적인 가뭄의 분포를 파악하여 적절한 가뭄평가 수단을 통한 가뭄대책 수립기준을 설정하고 이에 대한 대책방안을 마련하여 각 지역별 특성에 맞는 가뭄대책을 수립해야 한다. 따라서 본 연구에서는 농업가뭄을 극복하고 농촌수자원의 안정적 확보와 효율적인 이용을 위해서 농업가뭄 상황을 분석하고 평가할 수 있으며 농업가뭄대책의 수립과 시행을 뒷받침할 수 있는 Web 및 GIS 기반농업가뭄관리시스템을 제안하고자 한다. 기존의 개발된 토양수분지수(Soil Moisture Index, SMI)와 저수지가뭄지수(Reservoir Drought Index, RDI)를 통합한 통합농업가뭄지수(Integrated Agricultural Drought Index, IADI)을 이용하여 다양한 시나리오를 통해 가뭄의 여러 가지 패턴에 따른 지역별 농업가뭄의 위험과 예측 피해를 설명하고, 가뭄관리에 필요한 정보를 단계적으로 제공함으로써 실제 물 관리 및 가뭄대책 업무에 반영하고 적절한 대응책을 수립하는데 기초자료가 될 것으로 판단된다.

• The Korean Journal of Applied Statistics
• /
• v.24 no.1
• /
• pp.83-92
• /
• 2011

This paper examines empirically Durham's (2008) asset pricing models to the KOSPI200 index. This model Incorporates the VKOSPI index as a proxy for 1 month integrated volatility. This approach uses option prices to back out implied volatility states with an explicitly speci ed risk-neutral measure and risk premia estimated from the data. The application uses daily observations of the KOSPI200 and VKOSPI indices from January 2, 2003 to September 24, 2010. The empirical results show that non-affine model perform better than affine model.

• Korean Journal of Optics and Photonics
• /
• v.28 no.6
• /
• pp.346-350
• /
• 2017

A tunable filter incorporating an apodized grating with a high-refractive-index polymer layer is demonstrated. In the apodized tunable filter, the reflectivity is decreased compared to that of a uniform grating, because of the gradually decreased grating depth. To increase the reflectivity of the apodized grating, a polymer of high refractive index is adopted for the apodized grating, and then high reflectivity is obtained while maintaining a narrow bandwidth. The apodized tunable filter exhibits a 3-dB bandwidth of 0.51 nm and a 20-dB bandwidth of 1.05 nm, with 98.5% reflection.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2003.10a
• /
• pp.251-254
• /
• 2003

In order for multidimensional infer structures to be integrated into an existing database management system, proper concurrency control methods that guarantee all isolation levels supported by the database management system. Several concurrency control methods have been proposed. They ran be classified into predicate locking based methods and granular locking based methods. Most of them are difficult to implement and ran not be applied to non-tree structured index structures. In this paper, we propose a new concurrency control method that guarantee all isolation levels. It is easy to implement and can be applied to any type of index structures. We implement the proposed method and existing methods, and perform various experiments to show the superiority of the proposed algorithm.

• Environmental Engineering Research
• /
• v.24 no.4
• /
• pp.582-590
• /
• 2019

Currently, the waterfront facility was constructed in New Songdo City, South Korea. It has the various water leisure areas and especially an artificial urban canal with filtered seawater by re-circulating flow system. However, due to excessive amount of nutrients from seawater combined with complicated geometry, it is highly vulnerable to deterioration of water quality. In this study, flow characteristics and pollutant transport were analyzed with comprehensive numerical models, MIKE 3 FM and ECO-lab. Based on these numerical results, notable sampling points were selected for field measurements and comparison between modeling and measured results were conducted. In addition, the integrated water quality evaluation index, Water Quality Index was applied to analyze various water quality issues. We also set up scenarios to control the two kinds of water quality factors, dissolved oxygen (DO), and total phosphorus (TP). As a result, the effect of 20% reduction of TP was less than 10% and it was almost ineffective for a year but it was reduced by up to 40% in case of scenario which DO is increased by 20%. Therefore, it was recommended to control the DO concentration, usually by applying re-aeration facility, rather than TP in artificial urban canal with seawater.

• KNOM Review
• /
• v.24 no.2
• /
• pp.35-47
• /
• 2021

Various stress exists in a modern society, which requires constant competition and improvement. A person under stress often shows his pressure in his facial expression and language. Therefore, it is possible to measure the pressure using facial expression and language analysis. The paper proposes a stress measurement system using facial expression and language sensitivity analysis. The method analyzes the person's facial expression and language sensibility to derive the stress index based on the main emotional value and derives the integrated stress index based on the consistency of facial expression and language. The quantification and generalization of stress measurement enables many researchers to evaluate the stress index objectively in general.