• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.847-856
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• 2019

The various environmental issues arose with the development of today's economy. naturally, people were increased interest in environment and the importance of research on drinking water and contamination are emerging especially. A number of country areas, uranium and ²²²Rn in ground water have been detected to people using as drinking water. So this study evaluated the way for more accurate measurements than when measuring ²²²Rn concentrations in the ground water containing. the experiment was performed using the low-level liquid scintillation counter with an alpha, beta analysis easy PSA function of pulse. the scintillator as the preparation of the ground water samples are mixed, the measure value detection is lowered over prepare period and expiration date. Energy spectrum was also moved to a lower side channel. As a long time to buy the scintillator and over time after opening, it was confirmed that detection is lowered. if the purpose is to use a different scintillator can see the energy through the channel change.

• Proceedings of the Korea Water Resources Association Conference
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• 2017.05a
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• pp.118-118
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• 2017

4대강 사업으로 인하여 장래 치수 및 물부족현상과 가뭄에 대비한 용수 확보를 위해 하도준설과 보의 설치, 중소규모댐 건설, 농업용저수지 증설 등이 진행되었다. 그중 낙동강에는 8개 대형보가 건설되었다. 하지만 보 건설로 인하여 주변 지역 지하수위가 상승하여 주변 농경지나 저지대가 침수될 가능성이 있어 4대강 사업의 문제점의 하나로 지적되어 왔다. 이에 본 연구에서는 낙동강 유역에 건설된 보로 인하여 상승한 하천수위가 보 주변지역에 미치는 영향을 알아보기 위하여 8개보 주변의 연구대상지역을 선정하고 지하수 모델(Visual-MODFLOW)을 이용하여 보 관리수위 및 함양량 변화에 따른 지하수 유동과 지하수 변화를 분석하였다. 각 연구대상지역별 지하수위 변동특성 분석 순서는 보 건설 후(현재상태)에 대하여 정류상태 보정을 실시한 후 보 관리수위 시나리오를 정하고 그에 따른 분기별 함양량을 적용하여 부정류 모의를 실시하였다. 그 결과 각 연구대상지역의 지하수위는 낙동강 하천수위와 비슷하게 형성되는 것으로 평가되었으며, 낙단보의 경우 분기별 지하수위 변화가 0.1m ~ 0.2m로 함양량 변화에 따른 지하수위 변동이 가장 작게 평가되었다. 상주보의 경우 분기별 지하수위 변화가 1.5m ~ 2.1m로 함양량 변화에 따른 지하수위 변동이 가장 큰 것으로 평가되었다. 이러한 지하수위 변화는 하천주변 농가의 재배 작물 수확량 및 품질에 직접적인 영향을 줄 수 있어 농번기인 2분기(4월 ~ 6월)와 4분기(10월 ~ 12월)의 경우 보 관리수위를 주변 재배작물에 따라 운영한다면 보 건설로 인한 주변 지하수위 상승으로 인한 영향을 최소화 할 수 있을 것으로 판단된다. 향후 한강, 금강, 영산강에 건설된 보 주변에 대한 지하수위 변화특성 연구가 필요할 것으로 판단되며 본 연구 결과를 바탕으로 보 관리수위 결정의 기초자료로 활용할 수 있을 것이라 판단 된다.

• The Journal of Engineering Geology
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• v.16 no.4 s.50
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• pp.411-427
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• 2006

This study aimed to recognize characteristics of groundwater flow in fractured bedrocks based on zonal pump-ing tests, slug tests, water quality logs and borehole TV camera logs conducted on two boreholes (NJ-11 and SJ-8) in the city of Naju. Especially, the zonal pumping tests using sin91e Packer were executed to reveal groundwater flow characteristics in the fractured bedrocks with depth. On borehole NJ-11, the zonal pumping tests resulted in a flow dimension of 1.6 with a packer depth of 56.9 meters. It also resulted in lower flow dimensions as moving to shallower packer depths, reaching a flow dimension of 1 at a 24 meter packer depth. This fact indicates that uniform permissive fractures take place in deeper zones at the borehole. On borehole SJ-8, a flow dimension of 1.7 was determined at the deepest packer level (50 m). Next, a dimension of 1.8 was obtained at 32 meters of packer depth, and lastly a dimension of 1.4 at 19 meters of packer depth. The variation of flow dimension with different packer depths is interpreted by the variability of permissive fractures with depth. Zonal pumping tests led to the utilization of the Moench (1984) dual-porosity model because hydraulic characteristics in the test holes were most suitable to the fractured bedrocks. Water quality logs displayed a tendency to increase geothermal temperature, to increase pH and to decrease dissolved oxygen. In addition, there was an increasing tendency towards electrical conductance and a decreasing tendency towards dissolved oxygen at most fracture zones.

• Journal of Soil and Groundwater Environment
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• v.14 no.6
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• pp.53-64
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• 2009

Wetlands can remove organic contaminants, metals and radionuclides from wastewater through various biogeochemical mechanisms. In this study, a mathematical model was developed for simulating the fate and transport of chemical species in marsh wetland sediments. The proposed model is a one-dimensional vertical saturated model which is incorporated advection, hydrodynamic dispersion, biodegradation, oxidative/reductive chemical reactions and the effects from external environments such as the growth of plants and the fluctuation of water level due to periodic tides. The tidal effects causes periodic changes of porewater flow in the sediments and the evapotranspiration and oxygen supply by plant roots affect the porewater flow and redox condition on in the rhizosphere along with seasonal variation. A series of numerical experiments under hypothetical conditions were performed for simulating the temporal and spatial distribution of chemical species of interests using the proposed model. The fate and transport of a trace metal pollutant, chromium, in marsh sediments were also simulated. Results of numerical simulations show that plant roots and tides significantly affect the chemical profiles of different electron acceptors, their reduced species and trace metals in marsh sediments.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.5
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• pp.109-116
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• 2010

Infiltration and the rising level of groundwater caused by rainfall are a major cause of the landslide and sliding. In order to secure the safety factor of slope, the slope stabilization and reinforcement works are used to enhance consistency. Nailing, Slope Drainage method and the surface vegetation measures can be simultaneously applied in the Mass Nail method, which is also environmental friendly reinforcement method. To demonstrate the reinforcement effect of a strengthened slope by Mass Nail, the changes in water contents by rainfall were considered while performing Scale Model Test. As a result, safety factor of reinforced slope was about 1.4~2.3 times increased on the unstrength slope. In the case of increasing water content 10% to 22%, The maximum stress was reduced to 12%~24% at the average rate of 18% on the unstrength slope and the reinforced slope by the Mass Nail Method was reduced to 4%~23% at the average rate of 14%.

• The Journal of Engineering Geology
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• v.7 no.3
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• pp.191-205
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• 1997

Measurements on subsurface movement of the Songsanri tomb site including the Muryong royal tomb was conducted using a tiltmeter system for the period of 15 months form July 7, 1996 to September 30, 1997. Two coordinate tilt monitoring data shows the biggest movement rate of 2.3mm/m/yr toward south in the frontal wall(N-S tilt) of the Muryong royal tomb. Southward tilting of bricks above the southern fire place in the western wall of the Muryong royal tomb is a proof of southward tilting of the royal tomb since its excavation in 1971. The eastern wall of the Muryong royal tomb is also tilting toward inside the tomb with the rate of 1.523mm/m/yr. Furthermore, tilting rate of wall increases twice in rainy season. It is interpreted tbat infiltration of water into the tomb and nearby ground in rainy season results in dangerous status for the safety of tomb structure. On the whole, normal component tilting of the walls of the 5th tomb is large than its shear component. It shows a small displacement toward one direction without no abrupt change in its direction and amount of tilting. The tilting rate of walls of the 6th tomb is about 8.8mm/m/yr in the dry season which is much bigger than those of other tombs in rainy season. Deformation events of walls of the tombs are closely related to amount of precipitation and variation of temperature. In comparison with different weather conditions, tilting is much bigger during the period of rainy weather than sunny weather. It is interpreted that rainwater flew into the turm through faults and nearby ground. High water content in nearby ground resulted strength of ground. The tilting event of walls shows a hysterisis phenomenon in analysis of temperature effect on tilting event. The walls tilt rapidly with steep rising of temperature, but the tilted walls do not come back to original position with temperature falling. Therefore, a factor of steep increase of the temperature must be removed. It means the tomb have to be kept with constant temperature. The observation of groundwater level using three boreholes located in construction site and original ground represented that groundwater level in construction site is higher than that of original ground during the rainy season from the end of June to August. It means that the drainage system of the Muryong royal tomb is worse than original ground, and it is interpreted that the poor drainage system is related to safety of tomb structure. As above mentioned, it is interpreted that artificial changes of the tomb environment since the excavation, infiltration of rainwater and groundwater into the tomb site and poor drainage system had resulted in dangerous situation for the tomb structure. According to the result of the long period observation for the tomb site, it is interpreted that protection of the tomb site from high water content should be carried out at first, and the rise of temperature by means of the dehumidifier inside the tomb must be removed.

• Journal of Radiation Protection and Research
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• v.44 no.3
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• pp.118-126
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• 2019

Background: Government conducts environmental radioactivity surveillance for verification purpose around nuclear facilities based on the Nuclear Safety Law and issues a surveillance report every year. This study aims to evaluate the short and the long-term fluctuation of radionuclides detected above MDC and their origins using concentration ratios between these radionuclides. Materials and Methods: Sample media for verification surveillance are air, rainwater, groundwater, soil, and milk for terrestrial samples, and seawater, marine sediment, fish, and seaweed for marine samples. Gamma-emitting radionuclides including $^{137}Cs$, $^{90}Sr$, Pu, $^3H$, and $^{14}C$ are evaluated in these samples. Results and Discussion: According to the result of the environmental radioactivity verification surveillance in the vicinity of nuclear power facilities in 2017, the anthropogenic radionuclides were not detected in most of the environmental samples except for the detection of a trace level of $^{137}Cs$, $^{90}Sr$, Pu, and $^{131}I$ in some samples. Radioactivity concentration ratios between the anthropogenic radionuclides ($^{137}Cs/^{90}Sr$, $^{137}Cs/^{239+240}Pu$, $^{90}Sr/^{239+240}Pu$) were similar to those reported in the environmental samples, which were affected by the global fallout of the past nuclear weapon test, and Pu atomic ratios ($^{240}Pu/^{239}Pu$) in the terrestrial sample and marine sample showed significant differences due to the different input pathway and the Pu source. Radioactive iodine ($^{131}I$) was detected at the range of < $5.6-190mBq{\cdot}kg-fresh^{-1}$ in the gulfweed and sea trumpet collected from the area of Kori and Wolsong intake and discharge. A high level of $^3H$ was observed in the air (Sangbong: $0.688{\pm}0.841Bq{\cdot}m^{-3}$) and the precipitation (Meteorology Post: $199{\pm}126Bq{\cdot}L^{-1}$) samples of the Wolsong nuclear power plant (NPP). $^3H$ concentration in the precipitation and pine needle samples showed typical variation pattern with the distance and the wind direction from the stack due to the gaseous release of $^3H$ in Wolsong NPP. Conclusion: Except for the detection of a trace level of $^{137}Cs$, $^{90}Sr$, Pu, and $^{131}I$ in some samples, anthropogenic radionuclides were below MDC in most of the environmental samples. Overall, no unusual radionuclides and abnormal concentration were detected in the 2017's surveillance result for verification. This research will be available in the assessment of environment around nuclear facilities in the event of radioactive material release.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.9
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• pp.995-1005
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• 2005

The study with laboratory sandbox model has been carried out to address potential use of reclaimed water, as a countermeasure artificially recharging the coastal aquifer, to effectively prevent from seawater intrusion due to overexploitation. It also investigated plausibility for either preserving or recovering the freshwater interface facing with seawater intrusion. To do this, we assessed hydraulic properties in artificial aquifer seawater/freshwater interface) depending upon the variation of extraction, storage and injection of reclaimed water. The variation of interface between freshwater and seawater were visualized by Surfer 8(Golden Software, USA) according to given experimental conditions. The interface between seawater and freshwater has been sensitively influenced by the change of extraction rate, where seawater zone migrated much faster into freshwater zone even though extraction rate became decreased. However, decreasing recharge rate could slow down moving of saline water zone toward freshwater zone. When the recharge was solely introduced into the sand box model, saline water intrusion was retarded than those of recharge and extraction working together. And also, the level of salinity of saline water was diluted by artificial recharge. It finally revealed that the artificial recharge would hydraulically avoid seawater intrusion while the freshwater sources could be conservatively utilized.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.4
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• pp.293-301
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• 2010

Optical fiber cable, as a sensor, was installed on the wall of KAERI(Korea Atomic Energy Research Institute) Underground Research Tunnel(KURT) in order to monitor the physical stability of the tunnel, which was constructed for technical development and demonstration of radioactive waste disposal. This monitoring system has two simultaneous measurements of temperature and strain over time using Brillouin backscatter. According to the results of the monitoring from Jan. 2008 to Nov. 2009, there is no significant displacement or movement at the tunnel wall However, the cumulative volume of total strain increased slightly as time passes with the comparison of the reference observation, which was measured in Jan. 2008. The change in cumulative volume of total strain indicates that the strain level had been affected by saturation and de-saturation phenomena due to groundwater fluctuation at several points at KURT. This system is based on the distributed sensing technique concept, not point sensing. By using this system, a displacement can be detected with the range from $20{\mu}{\varepsilon}$ to $28,000{\mu}{\varepsilon}$ every 1m interval in minimum. A temperature variation can be monitored at every 0.5m interval with the resolution of 0.01 in minimum. Based on the study, this monitoring system is potentially applicable to long term monitoring systems for radioactive waste disposal project as well as other structures and underground openings.

• The Journal of Engineering Geology
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• v.22 no.3
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• pp.331-341
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• 2012

Granitoid rocks are generally high-quality rock from a geotechnical perspective, because they rarely contain systematic joints or fragmented fault zones. Although the rock type at the Sanhak site is granite, a collapsed slope has a deep soil layer and shows no residual structures such as discontinuities or faults; surface avalanches from this slope can be observed in several places. To study the stability of this slope, we investigated rainfall duration, variation in pore-water pressure, and the factor of safety considering three cases (current cross-section, initial planning cross-section, revised planning cross-section). With increasing duration of rainfall, the groundwater level rises, up to 20 m in height from ground surface. In the initial planning cross-section, safety was secure for rainfall of 2 days duration, but inadequate for rainfall of 4 days duration. In the revised planning cross-section, however, safety factors were secure for rainfall of 4 days duration. Therefore, to ensure permanent stability at the Sanhak site, a slope degree of 1:1.8 should be maintained during cutting.