• Nuclear Engineering and Technology
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• 제55권4호
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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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• 제21권11호
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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.

• 한국식품위생안전성학회지
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• 제35권5호
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• pp.452-458
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• 2020

본 연구는 식물성 식품에 대한 잔류농약의 국내와 코덱스의 residue definition 비교를 통해 국내에서 식이노출 과소평가의 가능성이 있는 농약성분을 파악하고 더 나아가 식이노출 과소평가가 위해성 평가에 미치는 영향에 대해 우선적으로 검토가 필요한 농약성분을 알아내고자 하였다. 연구결과, 국내와 코덱스의 residue definition 정보로부터 식이노출 과소평가의 가능성이 있는 44종의 농약성분이 파악되었다. 이들 성분 중 농약성분의 ADI값, 국내 MRL 정보 및 대사물질의 독성학적 정보에 근거하여 다음의 24종 농약성분이 식이노출 과소평가가 위해성 평가에 미치는 영향에 대해 우선적으로 검토가 필요한 것으로 나타났다: 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. 더 나아가 chlorfenapyr, chlorothalonil, dithiocarbamates, fenamidone은 대사물질의 독성이 더 커서 특히 우선적으로 검토가 요구되는 것으로 판단된다. 본 연구는 식품 중 잔류농약에 대한 국내 위해성 평가방법의 개선을 위해 활용될 수 있을 것으로 기대된다.

• Nuclear Engineering and Technology
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• 제50권7호
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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.

• 보험의학회지
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• 제26권
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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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• 제15권7호
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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.

• 문화기술의 융합
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• 제8권2호
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• pp.139-148
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• 2022

우리는 제 16차 청소년건강행태조사 자료를 이용하여 청소년의 일반적 특성, 외모스트레스, 불안이 청소년의 신체 이미지 왜곡에 어떠한 영향을 미치는지 확인하고자 시도하였다. 우리는 대상자의 38.2%에서 신체이미지 왜곡을 확인하였고 19.9%에서 신체 이미지에 대한 과소평가(underestimate), 18.3%에서 과대평가(overestimate)하는 결과를 확인하였다. 과소평가(underestimate)와 과대평가(overestimate) 집단 모두에서 외모스트레스, 불안이 영향을 주는 것으로 확인되었다. 우리는 성별, 경제적 수준, 학업수준등의 인구학적 특성이 과소평가와 과대평가 집단에서 각각 다른 양상으로 영향을 미치는 것을 확인하였다. 따라서, 우리는 청소년의 체중에 대한 주관적인 인식을 과대평가와 과소평가의 경우로 세분화하여 포괄적인 평가를 하는 것이 추후 정신건강과 체중 조절 행동을 결정하는 중요한 요소가 될 것으로 제언한다.

• 한국지구과학회지
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• 제31권5호
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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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• 제4권1호
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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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• 제32권3호
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• pp.71-99
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• 2010

Adrian and Brunnermeier(2009)가 제안한 CoVaR는 위기의 파급효과를 측정하는 데 유용한 도구이다. 특히 어떤 금융기관이 금융시스템에 대해 어느 정도의 잠재적 리스크를 갖고 있는지를 측정할 수 있다. 본 연구는 CoVaR를 추정하는데 있어서 Adrian and Brunnermeier(2009)가 사용한 분위수 회귀방식이 아니라 이변량 정규분포 및 $S_U$-정규분포 등 모수적 분포함수를 이용하여 CoVaR를 추정하는 방법을 제안한다. 이들 모형을 이용하여 국내 은행산업을 대상으로 CoVaR를 추정하고, 이를 통해 CoVaR의 현실적 유용성을 점검함과 동시에 각 모형들의 추정 성과를 비교한다. 추정 결과, 은행들이 시스템리스크에 양(+)의 기여를 하고 있는 것으로 나타났다. 모형별로는 $S_U$-정규분포모형에 비해 분위수 회귀와 정규분포모형이 CoVaR를 (절댓값에서) 크게 과소평가하며, 위기수준을 높일수록 그 정도가 심해지는 것으로 나타났다.