• Journal of Biomedical Engineering Research
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• v.39 no.6
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• pp.243-249
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• 2018

The indoor radon concentration was measured in the lecture room of the university and the radon concentration was converted to the amount related to the radon exposure using the dose conversion convention and compared with the reference levels for the radon concentration control. The effect of indoor radon inhalation was evaluated by estimating the life effective dose and the risk of exposure. To measure the radon concentration, measurements were made with a radon meter and a dedicated analysis Capture Ver. 5.5 program in a university lecture room from January to February 2018. The radon concentration measurement was carried out for 5 consecutive hours for 24 hours after keeping the airtight condition for 12 hours before the measurement. Radon exposure risk was calculated using the radon dose and dose conversion factor. Indoor radon concentration, radon exposure risk, and annual effective dose were found within the 95% confidence interval as the minimum and maximum boundary ranges. The radon concentration in the lecture room was $43.1-79.1Bq/m^3$, and the maximum boundary range within the 95% confidence interval was $77.7Bq/m^3$. The annual effective dose was estimated to be 0.20-0.36 mSv/y (mean 0.28 mSv/y). The life-time effective dose was estimated to be 0.66-1.18 mSv (mean $0.93{\pm}0.08mSv$). Life effective doses were estimated to be 0.88-0.99 mSv and radon exposure risk was estimated to be 12.4 out of 10.9 per 100,000. Radon concentration was measured, dose effective dose was evaluated using dose conversion convention, and degree of health hazard by indoor radon exposure was evaluated by predicting radon exposure risk using nominal hazard coefficient. It was concluded that indoor living environment could be applied to other specific exposure situations.

• Journal of Sensor Science and Technology
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• v.21 no.1
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• pp.39-45
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• 2012

Recently the convergence of healthcare technology is used for daily life healthcare monitoring. Cardiac arrhythmia is presented by the state of the heart irregularity. Abnormal heart's electrical signal pathway or heart's tissue disorder could be the cause of cardiac arrhythmia. Fatal arrhythmia could put patient's life at risk. Therefore arrhythmia detection is very important. Previous studies on the detection of arrhythmia in various ECG analysis and classification methods had been carried out. In this paper, an ECG signal processing techniques to detect abnormal ECG based on DTW minimum accumulation distance through the template matching for normalized data and variable threshold method for ECG R-peak detection. Signal processing techniques able to determine the occurrence of normal ECG and abnormal ECG. Abnormal ECG detection algorithm using DTW minimum accumulation distance method is performed using MITBIH database for performance evaluation. Experiment result shows the average percentage accuracy of using the propose method for Rpeak detection is 99.63 % and abnormal detection is 99.60 %.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.800-807
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• 2009

The limited public funds available for infrastructure projects have led governments to consider private entities' participation in long-term contracts for finance, construction, and operation of these projects to share risks and rewards between the public and the private. Because these projects have complicated risk evolutions, diverse contractual forms for each project member to hedge risks involved in a project are necessary. In light of this, Build-Operate-Transfer(BOT) model is considered as effective to accomplish Public Private Partnerships(PPPs) with a characteristic of an ownership-reversion. In BOT projects, the government has used such an incentive system as minimum revenue guarantee(MRG) agreement to attract the private's participation. Although this agreement turns out critical in success of BOT project, there still exist problematic issues in a financial feasibility analysis since the traditional capital budgeting theory, Net Present Value(NPV) analysis, has failed to evaluate the contingent characteristic of MRG agreement. The purpose of this research is to develop real option model based on option pricing theory so as to provide a theoretical framework in valuing MRG agreement in BOT projects. To understand the applicability of the model, the model is applied to the example of the BOT toll road project and the results are compared with that by NPV analysis. Finally, we found that the impact of the MRG agreement is significant on the project value. Hence, the real option model can help the government establish better BOT policies and the developer make appropriate bidding strategies.

• Aerospace Engineering and Technology
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• v.2 no.2
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• pp.179-185
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• 2003

In this study, considerations for establishing RVSM airspace and requirements for RVSM operating aircraft are verified. The purpose of RVSM is to reduce vertical separation minimum for aircraft which operate between FL290~FL410 inclusive in regional airspace, and to increase airspace capacity by providing additional flight levels. To introduce RVSM, it is necessary to estimate quantatively airborne collision risk due to the reduction in vertical separation minimum. Aircraft operating through RVSM airspace is required to verify that height keeping performance is above specific standards.

• Communications for Statistical Applications and Methods
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• v.17 no.5
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• pp.725-731
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• 2010

Economic Reliability test plans(ERTP) are proposed considering that the life time of the submitted items follow the Pareto distribution of the second kind. For various specified acceptance number, sample size and producer's risk, a minimum test termination time is obtained. A comparison of proposed plan has been made with the existing plan developed by Aslam et al. (2010). The results are explained by tables and example.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.4
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• pp.137-152
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• 2014

In this paper, I suggest several techniques to estimate covariance matrix and compare the performance of the global minimum variance portfolio (GMVP) in terms of out of sample mean standard deviation and return. As a result, the return differences among the GMVPs are insignificant. The mean standard deviation of the GMVP using historical covariance is sensitive to the estimation window and the number of assets in the portfolio. Among the model covariance, the GMVP using constant systematic risk ratio model or using short sale restriction shows the best performance. The performance difference between the GMVPs using historical covariance and model covariance becomes insignificant as the historical covariance is estimated with longer estimation window. Lastly, the implied volatilities from ELW prices do not lead to superior performance to the historical variance.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.238-241
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• 2009

In order to design a good quantizer for the underlying distribution using a training sequence (TS), the traditional approach is seeking for the empirical minimum based on the empirical risk minimization principle. As the size of TS increases, we may obtain a good quantizer for the true distribution. However, if we have a relatively small TS, searching the empirical minimum for the TS causes the overfitting problem, which even worsens the performance of the trained codebook. In this paper, the performance of codebooks trained by small TSs is studied, and it is shown that a piecewise uniform codebook can be better than an empirically minimized codebook is.

• Journal of Industrial Convergence
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• v.15 no.1
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• pp.1-7
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• 2017

The purpose of this study is to analyze the facility standards of the elderly welfare facilities applying the seven principles of the universal design. The facility standards of the elderly welfare facilities were limited to the provisions of the "Enforcement Regulation of the Elderly Welfare Act". There are few legal regulations applying the universal design in the construction of the elderly welfare facilities. The facility standards are set only with the minimum requirements such as securing the safety of the user, securing the space area, functional convenience, and risk prevention. However, the contents of the regulations are limited to the minimum standards for functional convenience and safety required for living. In conclusion, in the elderly welfare facilities, the notion of universal design, which considers not only the elderly, but also service providers, employees, and general visitors, should be considered.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.4
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• pp.225-231
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• 2010

Extremely low values of the daily minimum temperature occurred in January 2010, ranging from -18 to $-29^{\circ}C$ at various locations growing peach trees in the Gangwon province. Due to the extreme cold temperature during the winter dormancy period of peach trees, the growth of the peach trees was damaged and the damaged areas increased as the extent of 17 to 144 ha. In order to provide information on mitigation measure of the cold temperature on the peach trees in the Gangwon province, we assessed the distribution of the damaged areas of growing the peach trees in 2010 and compared it with freezing risk estimated from the dormancy depth of the peach trees and the daily minimum temperature. The dormancy depth of 'Changhowon Hwando (Prunus persica (L.) Batsch)' ranged from -62 to -90 and the freezing risk was greater than 51%. The relationship between the freezing risk and the actual damaged area ratio showed reasonable agreement ($r^2$ of 0.5 with p < 0.01). The results imply that the estimates of the freezing risk based on the dormancy depth can be used as a mitigation measure to identify susceptible peach growing areas to freezing damage injury.

• Journal of Navigation and Port Research
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• v.38 no.4
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• pp.327-333
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• 2014

The Convention on the international regulations for preventing collisions at sea, 1972(COLREGs) defines the collision avoidance principles and various navigation rules for the prevention of collision at sea. In particular, the initial responses to avoid risk of collision are mainly decided by navigation officer's experience and subjective judgement. However, collision accidents could be effectively prevented if the minimum criteria of quantitative initial response are suggested to the junior officers and the cadets who have insufficient sea experience and navigation competency. This study reviewed the COLREGs terms related to the initial response and the existing papers concerned with risk assessment model. A questionnaire survey is also carried out for safe passing distance, degrees of alternating course and initial response distance to avoid collision in accordance with various encounter situations. Base on these results, we propose the proper minimum safe passing distance between the vessels, the initial response distance and required turning angles for alternation in each encounter situations. The suggested criteria of initial response will contribute to the prevention of collision at sea as well as the improvement of gradual navigation technology.