• 한국방사선학회논문지
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• 제12권4호
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• pp.459-466
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• 2018

방사선작업종사자 및 방사선작업장의 위험성은 주로 피폭선량 값으로 평가되고 있다. 하지만, 방사선작업장은 사용하는 방사선 및 작업환경이 상이하다. 특히, 방사선투과검사작업장은 작업대상물, 차폐체 사용가능 유무 등에 따라 작업환경이 다양하다. 따라서 효율적인 방사선 방호를 위해서는 여러 가지 인자들을 검토하는 것이 필요하다. 이에 전문가 및 조장 방사선작업종사자들 대상으로 설문조사를 수행하였으며, 그 결과, 방사선원, 방사선피폭선량, 작업장관리현황, 판독특이자, 정기검사현황이 주요인자로 선정되었다. 또한, 설문조사 중요도를 바탕으로 1차 가중치(안)을 설정한 후 2차적으로 전문가 자문을 통해 인자 내 세부항목별 가중치를 선정하였다. 따라서 본 연구를 통해 선정된 주요인자를 바탕으로 하여 방사선투과검사작업장 위해도 지수 모델 개발이 가능할 것으로 판단된다.

• 한국방사선학회논문지
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• 제11권7호
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• pp.555-564
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• 2017

직업상 피폭에 대한 현행 방사선 위험성 평가는 종사자의 피폭선량 평가 및 건강진단에 중점을 두고 있다. 이러한 개인 중심의 위험성 평가는 선량계 미착용 및 개개인의 기호로 인한 건강영향 문제 등 정확한 데이터 확보의 어려움으로 인한 오류의 가능성이 있다. 또한 평가의 기준이 되는 선량한도는 법적 최대 상한값으로 방사선 방호에 최적화된 값을 의미하지는 않는다. 이에 선원적, 환경적 및 인적 측면을 복합적으로 고려할 수 있고 방사선방호의 최적화를 이행할 수 있는 국가적 차원의 새로운 위험성 평가 모델이 요구되고 있다. 본 연구에서는 고용노동부의 위험성 평가에 기반하여 개인이 아닌 작업장 중심의 위험성 평가 모델을 연구하였다. 이를 위해 여러 분야의 위험성 추정 방법을 분석하여 방사선 분야에 적용하기 적합한 모델을 도출하고, 모델에 적용하기 위한 데이터 획득 방법 및 절차에 대해 기술하였다. 본 연구에서 도출한 작업장 중심의 다차원적 위험성 평가 모델은 위험성을 점수화하고 Rader Plot을 이용하여 표현함으로서 보다 정확한 방사선 위험성 평가를 가능하게 하며, 결론적으로 효율적인 종사자 관리, 선제적 종사자 보호 및 방사선 방호의 최적화 이행에 기여할 것으로 판단된다.

• Earthquakes and Structures
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• 제18권1호
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• pp.73-82
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• 2020

With the coal mining depth increasing, both stress and gas pressure rapidly enhance, causing coal and gas outburst risk to become more complex and severe. The conventional method for prediction of coal and gas outburst adopts one prediction index and corresponding critical value to forecast and cannot reflect all the factors impacting coal and gas outburst, thus it is characteristic of false and missing forecasts and poor accuracy. For the reason, based on analyses of both the prediction indicators and the factors impacting coal and gas outburst at the test site, this work carefully selected 6 prediction indicators such as the index of gas desorption from drill cuttings Δh₂, the amount of drill cuttings S, gas content W, the gas initial diffusion velocity index ΔP, the intensity of electromagnetic radiation E and its number of pulse N, constructed the Bayes discriminant analysis (BDA) index system, studied the BDA-based multi-index comprehensive model for forecast of coal and gas outburst risk, and used the established discriminant model to conduct coal and gas outburst prediction. Results showed that the BDA - based multi-index comprehensive model for prediction of coal and gas outburst has an 100% of prediction accuracy, without wrong and omitted predictions, can also accurately forecast the outburst risk even for the low indicators outburst. The prediction method set up by this study has a broad application prospect in the prediction of coal and gas outburst risk.

• Journal of Preventive Medicine and Public Health
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• 제45권1호
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• pp.14-20
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• 2012

Objectives: The aim of this study was to evaluate and quantify the risk of both individual and combined health behaviors on premature mortality in middle aged men in Korea. Methods: In total, 14 533 male subjects 40 to 59 years of age were recruited. At enrollment, subjects completed a baseline questionnaire, which included information about socio-demographic factors, past medical history, and life style. During the follow-up period from 1993 to 2008, we identified 990 all-cause premature deaths using national death certificates. A Cox proportional hazard regression model was used to estimate the hazard ratio (HR) of each health risk behavior, which included smoking, drinking, physical inactivity, and lack of sleep hours. Using the Cox model, each health behavior was assigned a risk score proportional to its regression coefficient value. Health risk scores were calculated for each patient and the HR of all-cause premature mortality was calculated according to risk score. Results: Current smoking and drinking, high body mass index, less sleep hours, and less education were significantly associated with all-cause premature mortality, while regular exercise was associated with a reduced risk. When combined by health risk score, there was a strong trend for increased mortality risk with increased score (p-trend < 0.01). When compared with the 1-9 score group, HRs of the 10-19 and 20-28 score groups were 2.58 (95% confidence intervals [CIs], 2.19 to 3.03) and 7.09 (95% CIs, 5.21 to 9.66), respectively. Conclusions: Modifiable risk factors, such as smoking, drinking, and regular exercise, have considerable impact on premature mortality and should be assessed in combination.

• 한국컴퓨터정보학회논문지
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• 제29권5호
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• pp.21-29
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• 2024

CT 촬영 시 방사선량을 줄이면 피폭 위험성을 낮출 수 있으나, 영상 해상도가 크게 저하 될 뿐아니라 잡음(noise) 발생으로 인해 진단의 효용성이 떨어진다. 따라서, CT 영상에서의 잡음제거는 영상복원 분야에 있어 매우 중요하고 필수적인 처리 과정이다. 영상 영역에서 잡음과 원래 신호를 분리하여 잡음만을 제거하는 것은 한계가 있다. 본 논문에서는 웨이블릿 변환 기반 GAN 모델 즉, WT-GAN(wavelet transform-based GAN) 모델을 이용하여 CT 영상에서 효과적으로 잡음 제거하고자 한다. 여기서 사용된 GAN 모델은 U-Net 구조의 생성자와 PatchGAN 구조의 판별자를 통해 잡음제거 영상을 생성한다. 본 논문에서 제안된 WT-GAN 모델의 성능 평가를 위해 다양한 잡음, 즉, 가우시안 잡음(Gaussian noise), 포아송 잡음 (Poisson noise) 그리고 스펙클 잡음 (speckle noise)에 의해 훼손된 CT 영상을 대상으로 실험하였다. 성능 실험 결과, WT-GAN 모델은 전통적인 필터 즉, BM3D 필터뿐만 아니라 기존의 딥러닝 모델인 DnCNN, CDAE 모형 그리고 U-Net GAN 모형보다 정성적이고, 정량적인 척도 즉, PSNR (Peak Signal-to-Noise Ratio) 그리고 SSIM (Structural Similarity Index Measure) 면에서 우수한 결과를 보였다.

• 한국농림기상학회지
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• 제6권1호
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• pp.49-60
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• 2004

Northern Gyeonggi Province(NGP), consisting of 3 counties, is the northernmost region in South Korea adjacent to the de-militarized zone with North Korea. To supplement insufficient spatial coverage of official climate data and climate atlases based on those data, high-resolution digital climate models(DCM) were prepared to support weather- related activities of residents in NGP Monthly climate data from 51 synoptic stations across both North and South Korea were collected for 1981-2000. A digital elevation model(DEM) for this region with 30m cell spacing was used with the climate data for spatially interpolating daily maximum and minimum temperatures, solar irradiance, and precipitation based on relevant topoclimatological models. For daily minimum temperature, a spatial interpolation scheme accommodating the potential influences of cold air accumulation and the temperature inversion was used. For daily maximum temperature estimation, a spatial interpolation model loaded with the overheating index was used. Daily solar irradiances over sloping surfaces were estimated from nearby synoptic station data weighted by potential relative radiation, which is the hourly sum of relative solar intensity. Precipitation was assumed to increase with the difference between virtual terrain elevation and the DEM multiplied by an observed rate. Validations were carried out by installing an observation network specifically for making comparisons with the spatially estimated temperature pattern. Freezing risk in January was estimated for major fruit tree species based on the DCMs under the recurrence intervals of 10, 30, and 100 years, respectively. Frost risks at bud-burst and blossom of tree flowers were also estimated for the same resolution as the DCMs.

• 대기
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• 제28권4호
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• pp.457-467
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• 2018

This study investigated the variability of spring (March-May) forest fire risk in Korea for the period 1991~2017 and analyzed its relationship with large-scale climate factors. The Forest Weather Index (FWI) representing the meteorological risk for forest fire occurrences calculated based on observational data and its relationship with large-scale climate factors were analyzed. We performed the empirical orthogonal function (EOF) analysis on the spring FWI. The leading EOF mode of FWI accounting for about 70% of total variability was found to be highly correlated with total number of forest fire occurrences in Korea. The high FWI, forest fire occurrence risk, in Korea, is associated with warmer atmosphere temperature in midwest Eurasia-China-Korea peninsula, cyclonic circulation anomaly in northeastern China-Korea peninsula-northwest pacific, westerly wind anomaly in central China-Korea peninsula, and low humidity in Korea. These are further related with warmer sea surface temperature and enhanced outgoing longwave radiation over Western Pacific, which represents a typical condition for a La $Ni\tilde{n}a$ episode. This suggests that large-scale climate factors over East Asia and ENSO could have a significant influence on the occurrence of spring forest fires in Korea.

• Clinical Endoscopy
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• 제57권1호
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• pp.112-121
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• 2024

Background/Aims: Since the usefulness of neoadjuvant chemo(radiation) therapy (NAT) for pancreatic cancer has been demonstrated, recurrent biliary obstruction (RBO) in patients with pancreatic cancer with a fully covered self-expandable metal stent (FCSEMS) during NAT is expected to increase. This study investigated the impact of sarcopenia on RBO in this setting. Methods: Patients were divided into normal and low skeletal muscle index (SMI) groups and retrospectively analyzed. Patient characteristics, overall survival, time to RBO (TRBO), stent-related adverse events, and postoperative complications were compared between the two groups. A Cox proportional hazard model was used to identify the risk factors for short TRBO. Results: A few significant differences were observed in patient characteristics, overall survival, stent-related adverse events, and postoperative complications between 38 patients in the normal SMI group and 17 in the low SMI group. The median TRBO was not reached in the normal SMI group and was 112 days in the low SMI group (p=0.004). In multivariate analysis, low SMI was the only risk factor for short TRBO, with a hazard ratio of 5.707 (95% confidence interval, 1.148-28.381; p=0.033). Conclusions: Sarcopenia was identified as an independent risk factor for RBO in patients with pancreatic cancer with FCSEMS during NAT.

• Asian Pacific Journal of Cancer Prevention
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• 제14권11호
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• pp.6523-6528
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• 2013

Background: Cigarette smoking is the largest single recognized cause of human cancers. In Western countries, many epidemiologists have reported risk factors for kidney cancer including smoking. However, little is known about the Japanese population. Materials and Methods: We evaluated the association of smoking with the risk of kidney cancer death in the Japan Collaborative Cohort (JACC) Study. Participants included 46,395 males and 64,190 females. The Cox proportional hazards model was used to determine age-and-sex adjusted relative risks. Results: A total of 62 males and 26 females died from kidney cancer during the follow-up of 707,136 and 1,025,703 person-years, respectively. Heavy smokers (Brinkman index >1200), fondness of fatty foods, hypertension, diabetes mellitus (DM), and obesity were suggested to increase the risk of renal cell carcinoma while walking was suggested to decrease the risk. Even after controlling for age, sex, alcohol drinking and DM, heavy smoking significantly increased the risk. Conclusions: The present study suggests that six factors including smoking may increase and/or reduce the risk of kidney cancer in the Japanese population. Because of the small number of outcomes, however, we did not evaluate these factors after adjusting for all possible confounding factors. Further studies may be needed to confirm the findings in this study.

• 한국농림기상학회지
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• 제19권1호
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• pp.10-18
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• 2017

소나무는 우리나라에서 생태적, 사회 문화적으로 가장 중요한 수종으로 보호 이용되어 온 수종이다. 그러나 산림유전자원보호구역 내 금강소나무 고사가 발생하고 있어 명확한 원인 구명 및 대책 마련이 필요하다. 따라서 본 연구에서는 금강소나무의 고사 원인 구명을 위해 시계열 항공영상을 이용하여 금강소나무 고사 발생 전수 조사를 실시하고 고사발생 지역에 대한 지형환경특성을 분석하여, 소나무 고사의 위치적 특성 및 이에 따른 기상 요인과의 연관성을 파악하였다. 그 결과, 2,600ha 연구 대상지 내에서 약 1,956본의 금강소나무 고사목이 추출되었다. 소나무의 고사는 소나무 생육지역에 비해 고도가 높고, 일사량이 많고, 지형습윤지수가 낮은 지역, 남 남서사면, 능선 부위, 풍노출도가 높은 지역에 집중되어 발생한 것으로 나타났다. 이러한 지역은 지형조건에 따라 영향을 받는 미기상 특성에 따라 고온과 건조 스트레스가 상대적으로 높은 지역으로 분류되는 지역이다. 기후변화에 따라 고온 건조 스트레스가 전반적으로 높아지고 있으며 취약지역을 중심으로 스트레스의 임계치를 넘으면서 고사현상이 발생하는 것으로 추정되었다. 이러한 지형환경 특성을 바탕으로 MaxEnt 모형을 이용하여 소나무 고사 발생 위험 지도를 제작하였으며, 이는 향후 소나무 보호 관리 대책 수립에 활용될 수 있다.