• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.17 no.4
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• pp.272-281
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• 2007

선박제조업을 비롯한 운송업 및 건축업 등의 다양한 분야에서 용접기술이 이용되어 옴에 따라 용접근로자들에 대한 산업보건학적 관심이 높아지고 있다. 노출정도가 다양하기는 하지만 용접흄은 6가 크롬을 비롯한 금속화합물과 유해가스, 화학물질 등을 복합적으로 포함하고 있는 스테인레스 스틸 용접흄에 대한 유전독성영향을 평가하기 위하여 흡입챔버를 이용, 실험동물인 영장류에 스테인레스 스틸 용접흄을 노출시키고 혈액 내 lymphocytes에 생성된 용접흄 노출농도 및 시간별 DNA 손상정도 및 그 회복효소를 측정함으로써, 유해성이 완전하게 확인되지 않은 용접흄에 노출되어 나타날 수 있는 암을 비롯한 심각한 건강영향을 예방하기 위한 각 지표들을 찾아 그 유용성을 비교하고자 하였다. 영장류를 노출시키기 위해 robotic arm을 장치한 영장류 흡입노출 시스템을 개발하였으며, 이 노출 시스템을 이용하여 수컷 영장류 6마리에 대해 용접흄 노출시험을 실시하였는데 실험군은 대조군 2, 저농도 ($31mg/m^3$) 노출군 2, 고농도 ($63mg/m^3$) 노출군 2마리로 구성하였고, 1일 2시간씩 일주일에 5일 동안 용접흄에 노출시켰다. 노출 농도는 지속적으로 모니터링 하였고, 노출과정 중에 영장류의 혈액을 채취하여 lymphocytes를 분리, 단세포 DNA 손상을 선별하기 위해 DNA 손상회복 효소인 E. coli formamidopyrimidine-DNA glycosylase (Fpg)와 endonuclease Ⅲ (Thymine Glycol-DNA glycosylase) 투여와 Comet asaay (single cell gel electrophoresis, 단세포겔전기영동기법)를 결합시켜 이용하는 Fpg/Endo III FLARE 분석법을 사용하였다. Fpg enzyme에 의한 olive tail moment값의 변화는 16주 노출군부터 노출부검(34주)군 까지 노출농도가 높아짐에 따른 olive tail moment 기하평균 값의 양 반응관계를 보기는 어렵지만, 고농도군의 경우 27주 노출군에서 가장 높은 olive tail moment 값을 보이고 이후 차츰 감소하였다. 한편 16주에서 22주까지의 노출기간에서는 대조군에 비해 노출군에서 DNA손상정도(olive tail moment값)는 모두 유의하게 높았으나, 6, 12, 18, 25, 31, 33, 35주간 노출하였을 때는 다른 결과를 보였다. 각 실험군의 Fpg enzyme에 의한 tail length값의 분포를 살펴볼 때, 저농도군 및 고농도군에서 27주간 노출하였을 때 가장 높은 tail length 값을 보이고 이후 차츰 감소하는 경향을 보였다. 또한 16, 22주간 노출하였을 때 대조군에 비해 노출군에서 tail length 값이 유의하게 높았으나, 20주간에서만 양 반응관계가 관찰되었고, 다른 주간에서는 양 반응 및 기간 반응관계를 나타내지는 않았다. Endo III enzyme에 의한 olive tail moment값의 변화는 기간별 노출군에서 대조군에 비해 높은 DNA손상정도(olive tail moment값)를 나타내는 결과들이 있었지만, 10, 12, 16, 22, 25, 31주간 노출하였을 때 등 상당수 노출기간에서 반응관계를 나타내지는 않았다. 각 실험군의 Endo III enzyme에 의한 tail length값의 분포를 살펴볼 때, 18, 20, 27, 33주간 노출하였을 때 대조군에 비해 노출군에서 tail length 값이 조금 높았지만, 양 반응 및 기간 반응관계를 보이지 않았고 수치의 크기가 불규칙하게 변화하였다. 즉, DNA에 있어 산화된 pyrimidine을 형성하여 손상된 부위의 염기를 제거함으로써 AP site (abasic site)를 만들고 이들이 Comet assay를 통해 break로 전환된 것을 포함한 DNA손상을 측정하기 위하여 endonuclease III (Endo III)를 첨가시킨 Endo III FLARE 분석법을 실시한 결과, 본 연구에서 나타난 결과는 용접흄 노출 영장류에서 Olive tail moment 및 tail length 공히 노출량 및 노출기간 반응관계를 볼 수 없었다. Endo III FLARE 분석법을 통한 산화적 DNA 손상지표는 영장류에 적용하기에는 적응반응현상으로 대조군과 유의한 차이도 관찰할 수 없었고 더욱이 역으로 대조군에서의 자연발생적 수치가 더 높아질 수 있어 용접흄 노출 영장류의 모니터링 지표로 사용하기에는 제한점이 있었다.

• KSBB Journal
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• v.25 no.6
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• pp.572-576
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• 2010

Biological products, such as live varicella vaccine, are composed of biological substances derived from biological organisms. It is very difficult to identify these biologics' characteristics by analysis of simple physical and chemical methods alone. So the reference material is essential in order to evaluate the quality of bilogics. The 1'st national standard for varicella live vaccine was manufactured, established in 2002 and 2003, and have been used for the manufacturer's quality control and national lot release since then. As the lack of its availability and the decrease of its stability, this study was initiated by National Institute of Food and Drug Safety Evaluation (NiFDS) in 2008 to manufacture and establish the 2nd national standard for varicella live vaccine. The candidate material was manufactured from one of domestic manufacterers and the joint research of the NiFDS and manufacturers of varicella live vaccine was conducted to estimate of the reliable virus content. In the collaborative study, 3 laboratories including NiFDS performed the virus content test more than 7 times and all assay results were statistically analyzed. The mean coefficient of variation (CV) was 1.24%, and the geometric mean titre (GMT) variation range of each laboratory was low. On the basis of the results of this study, the candidate material of 2nd national standard for varicella live vaccine was assigned a potency of 4.26 log10 pfu/0.5 mL, when reconstituted in 0.7 mL.

• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.515-530
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• 2021

This study is to estimate soil moisture (SM) using Sentinel-1A/B C-band SAR (synthetic aperture radar) images and Multiple Linear Regression Model(MLRM) in the Yongdam-Dam watershed of South Korea. Both the Sentinel-1A and -1B images (6 days interval and 10 m resolution) were collected for 5 years from 2015 to 2019. The geometric, radiometric, and noise corrections were performed using the SNAP (SentiNel Application Platform) software and converted to backscattering coefficient of VV and VH polarization. The in-situ SM data measured at 6 locations using TDR were used to validate the estimated SM results. The 5 days antecedent precipitation data were also collected to overcome the estimation difficulty for the vegetated area not reaching the ground. The MLRM modeling was performed using yearly data and seasonal data set, and correlation analysis was performed according to the number of the independent variable. The estimated SM was verified with observed SM using the coefficient of determination (R²) and the root mean square error (RMSE). As a result of SM modeling using only BSC in the grass area, R² was 0.13 and RMSE was 4.83%. When 5 days of antecedent precipitation data was used, R² was 0.37 and RMSE was 4.11%. With the use of dry days and seasonal regression equation to reflect the decrease pattern and seasonal variability of SM, the correlation increased significantly with R² of 0.69 and RMSE of 2.88%.

• Economic and Environmental Geology
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• v.56 no.4
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• pp.435-445
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• 2023

A delta is a depositional landform that is formed when sediment transported by a river is deposited in a relatively low-energy environment, such as a lake, sea, or a main channel. Among these, a delta formed at the confluence of rivers has a great importance in river management and research because it has a significant impact on the hydraulic and sedimentological characteristics of the river. Recently, the equilibrium state of the confluence area has been disrupted by large-scale dredging and construction of levees in the Nakdong River. However, due to the natural recovery of the river, the confluence area is returning to its pre-dredging natural state through ongoing sedimentation. The time-series data show that the confluence delta has been steadily growing since the dredging, but once it reaches a certain size, it repeats growth and retreat, and the overall size does not change significantly. In this study, we developed a model to explain the sedimentation-erosion processes in the confluence area based on the assumption that the confluence delta reaches a dynamic equilibrium. The model is based on two fundamental principles: sedimentation due to supply from the tributary and erosion due to the main channel. The erosion coefficient that represents the Nakdong River confluence areas, was obtained using data from the tributaries of the Nakdong River. Sensitivity analyses were conducted using the developed model to understand how the confluence delta responds to changes in the sediment and water discharges of the tributary and the main channel, respectively. We then used annual average discharge of the Nakdong River's tributaries to predict the dynamic equilibrium positions of the confluence deltas. Finally, we conducted a simulation experiment on the development of the Gamcheon-Nakdong River delta using recorded daily discharge. The results showed that even though it is a simple model, it accurately predicted the dynamic equilibrium positions of the confluence deltas in the Nakdong River, including the areas where the delta had not formed, and those where the delta had already formed and predicted the trend of the response of the Gamcheon-Nakdong River delta. However, the actual retreat in the Gamcheon-Nakdong River delta was not captured fully due to errors and limitations in the simplification process. The insights through this study provide basic information on the sediment supply of the Nakdong River through the confluence areas, which can be implemented as a basic model for river maintenance and management.