• Nuclear Engineering and Technology
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• v.55 no.4
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• pp.1420-1427
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• 2023

Seismic risk has received increased attention since the 2011 Fukushima accident in Japan. The seismic risk of a nuclear power plant is evaluated via seismic probabilistic safety assessment (PSA), for which several methods are available. Recently, the discrete approach has become widely used. This approximates the seismic risk by discretizing the ground motion level interval into a small number of subintervals with the expectation of providing a conservative result. The present study examines the effect of the number of subintervals upon the results of seismic risk quantification. It is demonstrated that a small number of subintervals may lead to either an underestimation or overestimation of the seismic risk depending on the ground motion level. The present paper also provides a method for finding the boundaries between overestimation and underestimation regions, and illustrates the effect of the number of subintervals upon the seismic risk evaluation with an example. By providing a method for determining the effect of a small number of subintervals upon the results of seismic risk quantification, the present study will assist seismic PSA analysts to determine the appropriate number of subintervals and to better understand seismic risk quantification.

• Korean Journal of Radiology
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• v.21 no.11
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• pp.1220-1229
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• 2020

Objective: Stereotactic vacuum-assisted breast biopsy (VABB) is considered a reliable alternative to surgical biopsy for suspicious calcifications. In most cases, the management of flat epithelial atypia (FEA) and atypical ductal hyperplasia (ADH) after VABB with residual calcifications requires surgical excision. This study aimed to evaluate the impact of pathology of non-calcified specimens on the underestimation of malignancy. Materials and Methods: We retrospectively reviewed 1147 consecutive cases of stereotactic VABB of suspicious calcifications without mass from January 2010 to December 2016 and identified 46 (4.0%) FEA and 52 (4.5%) ADH cases that were surgically excised for the retrieval of residual calcifications. Mammographic features and pathology of the calcified and non-calcified specimens were reviewed. Results: Seventeen specimens (17.3%) were upgraded to malignancy. Mammographic features associated with the underestimation of malignancy were calcification extent (> 34.5 mm: odds ratio = 6.059, p = 0.026). According to the pathology of calcified versus non-calcified specimens, four risk groups were identified: Group A (ADH vs. high-risk lesions), Group B (ADH vs. non-high-risk lesions), Group C (FEA vs. high-risk lesions), and Group D (FEA vs. non-high-risk lesions). The lowest underestimation rate was observed in Group D (Group A vs. Group B vs. Group C vs. Group D: 35.0% vs. 20.0% vs. 15.0% vs. 3.6%, p = 0.041, respectively). Conclusion: Considering that the calcification extent and pathology of non-calcified specimens may be beneficial in determining the likelihood of malignancy underestimation, excision after FEA or ADH diagnosis by VABB is required, except for the diagnoses of FEA coexisting without atypia lesions in non-calcified specimens.

• Journal of Food Hygiene and Safety
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• v.35 no.5
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• pp.452-458
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• 2020

In this study we aimed to find out pesticide types with probability for underestimation of dietary exposure to pesticide residues in Korea by comparing the residue definitions between Korea and Codex standards. In addition, we sought to establish priorities regarding the necessity of review concerning pesticide types and their impacts based on the risk assessment and dietary exposure underestimation. As a result, we found that according to the residue definition information, 44 pesticides have probability for underestimation in terms of dietary exposure assessments. Among them, 24 pesticides have priority for review of dietary exposure underestimation and its impacts on risk assessment, based on the ADI values of pesticides, Korean MRL information and toxicological information of metabolite. The 24 pesticides were as follows: acibensolar-S-methyl, chlorfenapyr, chlorothalonil, cyantraniliprole, cyclaniliprole, cyflumetofen, dithiocarbamates, fenamidone, fenpyroximate, fluazifop-P-butyl, fluopicolide, flupyradifuron, fluxapyroxad, glyphosate, hexythiazox, isoprothiolane, isopyrazam, myclobutanil, penthiopyrad, propiconazole, spinetoram, spiromesifen, spirotetramat, trifloxystrobin. Furthermore, chlorfenapyr, chlorothalonil, dithiocarbamates and fenamidone may have considered a top priority for review due to greater toxicity of metabolite. This study could be of great use for improvement on risk assessment approaches in South Korea regarding pesticide residues in food commodities.

• Nuclear Engineering and Technology
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• v.50 no.7
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• pp.1099-1105
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• 2018

How to choose defaults in risk-informed regulations depends on the conservatism implicated in regulatory defaults. Without a universal agreement on the approaches dealing with the conservatism of defaults, however, the desirability of conservatism in regulatory risk analyses has long been controversial. The opponent views it as needlessly costly and irrational, and the proponent as a form of protection against possible omissions or underestimation of risks. Moreover, the inherent ambiguity of risk makes it difficult to set suitable defaults in terms of risk. This paper, the extension of the previous work [1], focuses on the effects of different levels of conservatism implicated in regulatory defaults on the estimates of risk. According to the postulated behaviors of regulated parties and the diversity of interests of regulators, in particular, various measures for evaluating the effect of conservatism in defaults are developed and their properties are explored. In addition, a simple decision model for setting regulatory defaults is formulated, based on the understanding of the effect of conservatism implicated in them. It can help decision makers evaluate the levels of safety likely to result from their regulatory policies.

• The Journal of the Korean life insurance medical association
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• v.26
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• pp.31-39
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• 2007

Background and main issue: In the Korean insurance market, an outstanding issue is the decrease of margin of risk ratio. This affects the solvency and profitability of insurance companies. Insurance medicine, which has been developed in Western countries, is so-called medical risk selection or medical underwriting. Medical risk selection is based on clinical follow-up study and mortality analysis methodology. Unfortunately, there have been few clinical follow-up studies, and no intercompany disease analysis system is available in the Korean insurance market. In practice, we use underwriting guidelines, which were developed by some global reinsurance companies. However, these guidelines were developed under clinical follow-up studies performed abroad. So, we cannot rule out underestimation of excess mortality factors such as mortality ratio, excess death rate, and life expectancy. It is necessary to perform medical assessment in claims administration. Comparing the insured's statement by medical records with products' benefit according to this procedure, we can make sound claim decisions and participate in the role of sound underwriting. We can call this scientific procedure as the verification of medical claims review. Another area of medical claims review is medical counsel for claims staff. Result: There is another insurance medicine in addition to medical risk selection. Independent medical assessment by medical records of insured is medical claims review. Medical claims review is composed of verification and counsel.

• Asian Pacific Journal of Cancer Prevention
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• v.15 no.7
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• pp.3179-3183
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• 2014

Background: The purpose of study was to evaluate radiologic or clinical features of breast cancer undergoing ultrasound (US)-guided 14G core needle biopsy (CNB) and analyze the differences between underestimated and accurately diagnosed groups. Materials and Methods: Of 1,898 cases of US-guided 14G CNB in our institute, 233 cases were proven to be cancer by surgical pathology. The pathologic results from CNB were invasive ductal carcinoma (IDC) (n=157), ductal carcinoma in situ (DCIS) (n=40), high-risk lesions in 22 cases, and benign in 14 cases. Among high-risk lesions, 7 cases of atypical ductal hyperplasia (ADH) were reported as cancer and 11 cases of DCIS were proven IDC in surgical pathology. Some 29 DCIS cases and 157 cases of IDC were correctly diagnosed with CNB. The clinical and imaging features between underestimated and accurately diagnosed breast cancers were compared. Results: Of 233 cancer cases, underestimation occurred in 18 lesions (7.7%). Among underestimated cancers, CNB proven ADH (n=2) and DCIS (n=11) were diagnosed as IDC and CNB proven ADH (n=5) were diagnosed at DCIS finally. Among the 186 accurately diagnosed group, the CNB results were IDC (n=157) and DCIS (n=29). Comparison of underestimated and accurately diagnosed groups for BI-RADS category, margin of mass on mammography and US and orientation of lesion on US revealed statistically significant differences. Conclusions: Underestimation of US-guided 14G CNB occurred in 7.7% of breast cancers. Between underestimated and correctly diagnosed groups, BI-RADS category, margin of the mass on mammography and margin and orientation of the lesions on US were different.

• The Journal of the Convergence on Culture Technology
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• v.8 no.2
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• pp.139-148
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• 2022

We attempted to determine how adolescents' general characteristics, appearance stress, and anxiety affect adolescents' body image distortion using data from the 16th Korea Youth Risk Behavior Survey. We confirmed Body image distortion in 38.2% of the subjects, and the results of underestimated body image in 19.9% and overestimation in 18.3%. Appearance stress and anxiety were found to have an effect in both underestimate and overestimate groups. We confirmed that demographic characteristics such as gender, economic level, and academic level influence different aspects in the underestimation and overestimation groups. Therefore, we suggested that comprehensive evaluation by subdividing the subjective perception of adolescents' weight into cases of overestimation and underestimation will be an important factor in determining mental health and weight control behavior in the future.

• Journal of the Korean earth science society
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• v.31 no.5
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• pp.437-447
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• 2010

Spatial estimation of environmental variables has been regarded as an important preliminary procedure for decision-making. A minimum variance criterion, which has often been adopted in traditional kriging algorithms, does not always guarantee the optimal estimates for subsequent decision-making processes. In this paper, a geostatistical framework is illustrated that consists of uncertainty modeling via stochastic simulation and risk modeling based on loss functions for the selection of optimal estimates. Loss functions that quantify the impact of choosing any estimate different from the unknown true value are linked to geostatistical simulation. A hybrid loss function is especially presented to account for the different impact of over- and underestimation of different land-use types. The loss function-specific estimates that minimize the expected loss are chosen as optimal estimates. The applicability of the geostatistical framework is demonstrated and discussed through a case study of copper mapping.

• Journal of Construction Engineering and Project Management
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• v.4 no.1
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• pp.29-36
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• 2014

Tunnelling has become a preferred method of construction for road and highway projects in countries with a lot of hilly slope geological conditions such as found in Malaysia. However the construction works of a tunnelling project are usually complicated and costly, which consequently impose great risks to the parties involved. This paper identifies the key significant risks and sub-risks for tunnelling construction projects in Malaysia through a case study. Interview has been used as the solitary means to determine the significant risks from contractor's eleven key project personnel who were directly involved in the tunnelling construction such as consultant, construction manager and tunnel engineers. The importance of the risks identified is then prioritised and ranked via the Analytic Hierarchy Process (AHP)'s pairwise comparison approach to determine their criticality towards a successful delivery of project. As a result, three key risks have been identified as significant for the tunnelling case study project, namely health and safety, cost overrun in construction and time overrun in construction. Two sub-risks each of the latter categories, which are cost underestimation and unforeseen events (cost overrun in construction) as well as plant and machinery failure and delay in material delivery (time overrun in construction), have occupied the top five overall risk ranking.

• KDI Journal of Economic Policy
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• v.32 no.3
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• pp.71-99
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• 2010

The concept of CoVaR introduced by Adrian and Brunnermeier (2009) is a useful tool to measure the risk spillover effect. It can capture the risk contribution of each institution to overall systemic risk. While Adrian and Brunnermeier rely on the quantile regression method in the estimation of CoVaR, we propose a new estimation method using parametric distribution functions such as bivariate normal and $S_U$-normal distribution functions. Based on our estimates of CoVaR for Korean banking industry, we investigate the practical usefulness of CoVaR for a systemic risk measure, and compare the estimation performance of each model. Empirical results show that bank makes a positive contribution to system risk. We also find that quantile regression and normal distribution models tend to considerably underestimate the CoVaR (in absolute value) compared to $S_U$-normal distribution model, and this underestimation becomes serious when the crisis in a financial system is assumed.