• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.636-647
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• 2004

The objective of this paper is to provide an improved reorder decision policy for general multi-echelon distribution systems utilizing the shared stock information. It has been known that traditional reorder policies sometimes show poor performance in distribution systems. Thus, in our previous research we introduced the order risk policy which utilizes the shared stock information more accurately for the 2-echelon distribution system and proved the optimality. However, since the real world supply chain is generally composed with more than 2 echelons, we extend the order risk policy for the general multi-echelon systems. Since the calculation of the exact order risk value for general multi-echelon systems is very complex, we provide two approximation methods for the real-time calculation. Through the computational experiment comparing the order risk policy with the existing policies under various conditions, we show the performance of the order risk policy and analyze the value of the shared stock information varying with the characteristics of the supply chain.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.742-745
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• 2004

Most of options pricing theory including Black and Scholes continuous model and Cox, Ross, and Rubinstein(CRR)'s binomial lattice model were developed based on the notion that continually revised risk-free hedges involving options and stock should earn the risk-free interest rate. This notion is valid with the assumption that the investor's attitude toward risk is neutral. In reality, this assumption may be frequently violated. Therefore, Hodder, Mello, and Sick proposed the way to value real options using the risk-adjusted interest rate. However, they did not show how to derive the mathematical expression for it. In this paper, we will clearly present how to obtain the mathematical expression for the risk-adjusted interest rate for real options and demonstrate two numerical examples to show its applicability.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2003.11a
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• pp.159-165
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• 2003

The objective of this paper is to provide an improved reorder decision policy for general multi-echelon distribution systems utilizing the shared stock information. Since it has been known that traditional reorder policies sometimes show poor performance in distribution systems, in our previous research we introduced the order risk policy which utilizes the shared stock information more accurately f3r the 2-echelon distribution system and proved the optimality. However, since the real world supply chain is generally composed with more than 2 echelons, we extend the order risk policy for the general multi-echelon systems. Since the calculation of the exact order risk value fur general multi-echelon systems is very complex, we provide two approximation methods. Through the computational experiment comparing the order risk policy with the existing policies under various conditions, we show the performance of the order risk policy and analyze the value of the shared stock information varying with the characteristics of the supply chain.

• IE interfaces
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• v.17 no.3
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• pp.359-374
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• 2004

The objective of this paper is to provide an improved reorder decision policy for general multi-echelon distribution systems utilizing the shared stock information. It has been known that traditional reorder policies sometimes show poor performance in distribution systems. Thus, in our previous research we introduced the order risk policy which utilizes the shared stock information more accurately for the 2- echelon distribution system and proved the optimality. However, since the real world supply chain is generally composed with more than 2 echelons, we extend the order risk policy for the general multi-echelon systems. Since the calculation of the exact order risk value for general multi-echelon systems is very complex, we provide two approximation methods for the real-time calculation. Through the computational experiment comparing the order risk policy with the existing policies under various conditions, we show the performance of the order risk policy and analyze the value of the shared stock information varying with the characteristics of the supply chain.

• Journal of the Korean Society of Radiology
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• v.13 no.2
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• pp.201-207
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• 2019

This study has evaluated whether the method of using the combination of different risk group, according to K-TIRADS classification and K-TIRADS classification in thyroid ultrasonography is useful in a differential diagnosis of benign and malignant nodules. The subject was patients underwent thyroid ultrasonography and retrospective analysis were performed based on the results of fine needle aspiration cytology. A chi-square test was performed for the difference analysis of the score system in K-TIRADS and different risk group according to the benign and malignant of thyroid nodule. The optimized cut off value was determined by the K-TIRADS score and different risk group to predict malignant nodule through ROC curve analysis. In the differential verification result of K-TIRADS and different risk group, according to the classification of benign and malignant nodule group each showed significant difference statistically(p=.001). In the point classification according to K-TIRADS for the prediction of benign and malignant in ROC curve analysis showed AUC 0.786, Cut-off value>2(p=.001), and in the different risk group, it was decided as AUC 0.640, Cut-off value>2(p=.001). When discovering the nodule in thyroid ultrasound, it is considered that the K-TIRADAS which helps in identifying benign and malignant thyroid nodules, it is considered to be helpful in the differential diagnosis of thyroid nodules, than the classification system according to Different risk group, and when applying the classification system according to K-TIRADS, it is considered that it can reduce unnecessary fine needle aspiration cytology and could be helpful in finding the malignant nodules early.

• Journal of Soil and Groundwater Environment
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• v.26 no.3
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• pp.37-49
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• 2021

There is domestic Soil Contamination Warning Standard (SCWS) as remediation standard concentration of contaminated soils. No risk should be observed at soil concentration less than SCWS. Therefore, SCWS was evaluated to confirm the risk assessment. Background Concentration of Soil (BGC) and target remediation concentration were also assessed. The results show that Excess Cancer Risk (ECR) of SCWS was the highest in the groundwater intake pathway (Adult: 6.27E-04, Child: 2.81E-04). Total Cancer Risk (TCR) was 7.76E-04 and 4.30E-04 for adult and child, exceeding reference value (10^-6). Hazard Quotient (Non-Carcinogenic Risk, HQ) was the highest in the indoor air inhalation pathway (Adult: 3.64E+03, Child: 8.74E+02). Hazard Index (Total Non-Carcinogenic Risk, HI) exceeded reference value 1. ECR of the BGC was the highest in the groundwater intake pathway (Adult: 1.71E-04, Child: 7.67E-05). TCR was 2.12E-04 for adults and 1.17E-04 for children, exceeding the reference value (10^-6). HQ was the highest in groundwater intake pathway (Adult: 4.10E-01, Child: 1.84E-01). HI was lower than reference value 1 (Adult: 4.78E-01, Child: 2.50E-01). The heavy metal affecting ECR was Arsenic (As). The remediation-concentration of As was 7.14 mg/kg which is higher than BGC (6.83 mg/kg). TCR of As should be less than reference value (10^-6), but it was higher for all of SCWS, BGC and target remediation concentration. Therefore, it is suggested that risk assessment factors should be re-evaluated to fit domestic environmental settings and SCWS should be induced to satisfy the risk assessment.

• The Korean Journal of Applied Statistics
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• v.29 no.4
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• pp.753-771
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• 2016

Value at Risk (VaR) is widely used as an important tool for risk management of financial institutions. In this paper we discuss estimation and back testing for VaR of the portfolio composed of KOSPI, Dow Jones, Shanghai, Nikkei indexes. The copula functions are adopted to construct the multivariate distributions of portfolio components from marginal distributions that combine extreme value theory and GARCH models. Volatility models with t distribution of the error terms using Gaussian, t, Clayton and Frank copula functions are shown to be more appropriate than the other models, in particular the model using the Frank copula is shown to be the best.

• Journal of the Korean Home Economics Association
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• v.45 no.5
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• pp.95-119
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• 2007

The purpose of this study was to investigate the shopping values(utilitarian and hedonic values) sought and the risks(economic, functional, socio-psychological, and privacy) perceived by consumers who participate in Internet auctions by determining the factors that affect their shopping values and risk perceptions. Empirical data were collected by an Internet survey of netizens who were interested in and had experience in Internet auctions. Questionnaires were distributed to the subjects through an Internet survey site and at an Internet auction cafe. A total of 300 questionnaires were analyzed. The results showed that consumers showed a slightly greater pursuit of a utilitarian value than a hedonic outcome in their Internet auction practices; however the outcomes pursued by consumers in their teens and twenties tended to be more hedonic than utilitarian. Consumers with a higher level of innovation, self-confidence in purchase, and need for information searching showed a greater pursuit of utilitarian and hedonic outcomes. The group of consumers with a higher expectation for legal protection pursued a more utilitarian outcome, whereas the group of consumers with higher influence from the reference group pursued a more hedonic outcome. The consumers showed that they perceived functional risk as boing most serious, followed by privacy risk, economic risk, and socio-psychological risk. Subjects with higher degrees of innovation, self-confidence in purchase and self-control perceived economic risk as critical. Functional risk was perceived to be highest in the group of consumers with self-control and a need for information searching, whereas socio-psychological risk was perceived to be highest in the group of consumers showing more self-control. Privacy risk was perceived to be highest in the group of consumers with a higher degree of innovation and lowest in both groups of higher and lower affection. Both economic and privacy risks were perceived to be lower in the group of lower pursuit of a hedonic outcome.

• Journal of the Korean Data and Information Science Society
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• v.25 no.6
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• pp.1171-1180
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• 2014

We considered saddlepoint approximations to VaR (value at risk) and ES (expected shortfall) which frequently encountered in finance and insurance as the measures of risk management. In this paper we supposed univariate and multivariate skew-normal distributions, instead of traditional normal class distributions, as underlying distribution of linear portfolios. Simulation results are provided and showed the suggested saddlepoint approximations are very accurate than normal approximations.

• Environmental and Resource Economics Review
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• v.12 no.1
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• pp.49-74
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• 2003

This study used a slightly modified version of contingent valuation questionnaire designed and developed by Krupnick et al.(2000) to estimate the value of mortality risk reduction for environmental policy. Because that environmental policy, especially air pollution policy with some latency main effect on mortality risk reduction of old people with some latency period, respondents were asked about their current WTP for 5/1,000 mortality risk reduction being to take place beginning at 70 over the course of ten years. The annual mean WTP is 233,370 won (standard error 32,570 won) in spike/continuous/interval data model. The implied VSL is 466 million won. The 95% confidence interval is 339 million won~594 million won.