• Radiation Oncology Journal
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• v.32 no.3
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• pp.156-162
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• 2014

Purpose: This study was designed to evaluate the efficacy and safety of topically applied recombinant human epidermal growth factor (rhEGF) for the prevention of radiation-induced dermatitis in cancer patients. Materials and Methods: From December 2010 to April 2012, a total of 1,172 cancer patients who received radiotherapy (RT) of more than 50 Gy were prospectively enrolled and treated with EGF-based cream. An acute skin reaction classified according to the Radiation Therapy Oncology Group 6-point rating scale was the primary end point and we also assessed the occurrence of edema, dry skin, or pruritus. Results: The percentage of radiation dermatitis with maximum grade 0 and grade 1 was 19% and 58% at the time of 50 Gy, and it became 29% and 47% after completion of planned RT. This increment was observed only in breast cancer patients (from 18%/62% to 32%/49%). Adverse events related to the EGF-based cream developed in 49 patients (4%) with mild erythema the most common. Skin toxicity grade >2 was observed in 5% of the patients. Edema, dry skin, and pruritus grade ${\geq}3$ developed in 9%, 9%, and 1% of the patients, respectively. Conclusion: Prophylactic use of an EGF-based cream is effective in preventing radiation dermatitis with tolerable toxicity. Further studies comparing EGF cream with other topical agents may be necessary.

• Journal of the Korean Geosynthetics Society
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• v.16 no.4
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• pp.33-41
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• 2017

In this study, the increment effect of safety factor according to increasing of horizontal permeability coefficient is analyzed when geocell is installed on the slope for protection. To evaluate the horizontal permeability and reinforcement effect, the laboratory tests such horizontal permeability test were conducted. According to the laboratory test results, as the porosity rate of geocell increases, the coefficient of horizontal permeability is also increased. And also, regardless of the different types of filled materials, the coefficient of horizontal permeability is improved in a geocell reinforced ground compare with the non-reinforced ground. Laboratory test results and the rainfall intensity were applied to the numerical modeling of slope for seepage analysis and stability analysis of slope by using Soilworks, numerical analysis program. As a result of the slope stability analysis, it is confirmed that the installed geocell on the slope facilitates the drainage of water on the surface of slope. Hence, the ground water elevation is suppressed. Therefore, the safety factor of the slope is increased by the increasing of the internal friction angle, apparent cohesion, and coefficient of horizontal permeability by reinforcing the slope with geocell.

• Journal of the Korean GEO-environmental Society
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• v.20 no.7
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• pp.5-10
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• 2019

In recent Gyeongju and Pohang earthquakes, motions that exceed the design ground motion were recorded. This has led to adjustments to the design earthquake intensity in selected design guidelines. An increment in the design intensity requires reevaluation of all associated facilities, requiring extensive time and cost. Firstly, the seismic factor of safety of built concrete retaining walls are calculated. Secondly, the seismic margin of concrete retaining walls is evaluated. The design sections of concrete walls built at power plants and available site investigation reports are utilized. Widely used pseudo-static analysis method is used to evaluate the seismic performance. It is shown that all concrete walls are safe against the adjusted design ground motion. To determine the seismic margin of concrete walls, the critical accelerations, which is defined as the acceleration that causes the seismic factor of safety to exceed the allowable value, are calculated. The critical acceleration is calculated as 0.36g~0.8g. The limit accelerations are significantly higher than the design intensity and are demonstrated to have sufficient seismic margin. Therefore, it is concluded that the concrete retaining walls do not need to be reevaluated even if the design demand is increased up to 0.3g.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.7
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• pp.693-700
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• 2015

To estimate the fatigue crack propagation behavior of compact tension shear (CTS) specimen under mixed-mode loads, crack path prediction theories and Tanaka's equation were applied. The stress intensity factor at a newly created crack tip was calculated using a finite element method via ANSYS, and the crack path and crack increment were then obtained from the crack path prediction theories, Tanaka's equation, and the Paris' equation, which were preprogrammed in Microsoft Excel. A new method called the finite element crack tip updating method (FECTUM) was developed. In this method, the finite element method and Microsoft Excel are used to calculate the stress intensity factors and the crack path, respectively, at the crack tip per each crack increment. The developed FECTUM was applied to simulate the fatigue crack propagation of a single-edge notched bending (SENB) specimen under eccentric three-point bending loads. The results showed that the number of cycles to failure of the specimen obtained experimentally and numerically were in good agreement within an error range of less than 3%.

• Journal of Korean Society for Atmospheric Environment
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• v.33 no.5
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• pp.445-457
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• 2017

In this study, we developed an approach to better account for uncertainties in estimated contributions from fine particulate matter ($PM_{2.5}$) modeling. Our approach computes a Concentration Correction Factor (CCF) which is a ratio of observed concentrations to baseline model concentrations. We multiply modeled direct contribution estimates with CCF to obtain revised contributions. Overall, the modeling system showed reasonably good performance, correlation coefficient R of 0.82 and normalized mean bias of 2%, although the model underestimated some PM species concentrations. We also noticed that model biases vary seasonally. We compared contribution estimates of major source sectors before and after applying CCFs. We observed that different source sectors showed variable magnitudes of sensitivities to the CCF application. For example, the total primary $PM_{2.5}$ contribution was increased $2.4{\mu}g/m^3$ or 63% after the CCF application. Out of a $2.4{\mu}g/m^3$ increment, line sources and area source made up $1.3{\mu}g/m^3$ and $0.9{\mu}g/m^3$ which is 92% of the total contribution changes. We postulated two major reasons for variations in estimated contributions after the CCF application: (1) monthly variability of unadjusted contributions due to emission source characteristics and (2) physico-chemical differences in environmental conditions that emitted precursors undergo. Since emissions-to-$PM_{2.5}$ concentration conversion rate is an important piece of information to prioritize control strategy, we examined the effects of CCF application on the estimated conversion rates. We found that the application of CCFs can alter the rank of conversion efficiencies of source sectors. Finally, we discussed caveats of our current approach such as no consideration of ion neutralization which warrants further studies.

• Journal of Korea Water Resources Association
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• v.51 no.1
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• pp.61-70
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• 2018

This study examined how to determine the optimal sediment level in dam reservoir for efficient plan and operation of dam. Currently, Korea is applying a horizontally accumulated method for sediment level estimation for the safety design of dam and so the method estimated relatively higher level than others. However, the sediment level of dam reservoir should be accurately estimated because it is an important factor in assessing life cycle of a dam. The sediment level in dam reservoir can be determined by SED-2D model linked with RMA-2, horizontally accumulated method, area increment method, and empirical area reduction method. The estimated sediment level from each method was compared with the observed sediment level measured in 2007 in Imha dam reservoir, Korea and then the optimal method was determined. Also, the future sediment level was predicted by each method for the future trend analysis of sediment level. As the results, the most accurate sediment level was estimated by the empirical area reduction method and the future trend of sediment level variation followed the past trend. Therefore, we have found that the empirical area reduction method is a proper one for more accurate estimation of sediment level and it can be validated by the results from a numerical model of SED-2D linked with RMA-2 model.

• Environmental Analysis Health and Toxicology
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• v.22 no.2 s.57
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• pp.157-163
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• 2007

Tetrabromobisphenol A (TBBPA) is the most widely used BFR (brominated flame retardants) as a reactive flame retardant in printed circuit boards, and as additive applications in several types of polymers. The purpose of this study is to assess the adverse effects of TBBPA on the benthic amphipod (Hyalella azteca). Results on the acute toxicity of TBBPA using Hyalella azteca showed that NOEC and LOEC are 100mg/kg and 200mg/kg, respectively. In addition, when chronic toxicity of TBBPA was investigated at the concentration ranges between 0.01 to 100mg/kg, it was found that NOECs are $10mg/kg(fecundity){\sim}100mg/kg(viability)$, respectively. Significant fecundity inhibition was appeared at 100mg/kg of TBBPA, however, this concentration did not show severe adverse effect on weight increment. The values of PNEC were determined as 0.1mg/kg (fecundity) and 1mg/kg (lethal effect), respectively, using a safety factor suggested by EU and OECD.

• 한국지구물리탐사학회:학술대회논문집
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• 2002.09a
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• pp.126-138
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• 2002

Designing the bridge with wider span is the present-day trends. Therefore, constructing the foundation on the suitable ground is one of the important factor for the safety of bridge. But, getting a subsurface information under the river is not easy problem. This paper shows results of electrical resistivity survey at the river. Electrical resistivity survey have revealed geoelectrical structure successfully. The result is well matched with boring and can provide useful information on the geological structure such as fault fracture zone for suitable location of foundation. It is expected that application of electrical resistivity survey at the river will be helpful in preventing modification of design due to unexpected ground condition during the construction, or water contamination and increment of costs accompanied with ground reinforcement.

• Journal of the Korean Geotechnical Society
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• v.26 no.10
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• pp.15-25
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• 2010

In this study, a method for estimating the in-situ stress state of NC clays using piezocone penetration test (PCPT) results is proposed. The proposed method is based on a correlation between the PCPT results and strength increment ratio. According to proposed method, no additional testing procedure for collecting undisturbed soil sample is required, which can reduce overall testing cost. To verify this method various analytical solutions were adopted and used. Measured result and predicted result are compared with each other. The verification sites consist of a variety of soil conditions. From the comparison, it is seen that predicted value of effective strcss using the proposed method match well those from measured results.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.2
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• pp.141-154
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• 2015

In general, conventional criticality analysis for spent fuel transport/storage systems have been performed based on the assumption of fresh fuel concerning the potential uncertainties from number density calculations of actinide nuclides and fission products in spent fuel. However, these evaluation methods cause financial losses due to an excessive criticality margin. In order to overcome this disadvantage, many studies have recently been conducted to design and commercialize a transportation and storage cask applied to the Burnup Credit (BUC). This study conducted an assessment to ensure criticality safety for reactor operating parameters, axial burn-up profiles and misload accident conditions, which are the factors that are likely to affect criticality safety when the BUC is applied to the dual-purpose cask under development at the KOrea RADioactive waste agency (KORAD). As a result, it was found that criticality resulting from specific power, changed substantially and relied on conditions of low enrichment and high burn-up. Considering the end effect in the case of high burn-up produced a positive-definite result. In particular, the increment of maximum effective multiplication factors due to misloading was 0.18467, confirming that misload is a factor that must be taken into account when applying the BUC. The results of this study may therefore be utilized as references in developing technologies to apply the BUC to domestic models and operational procedures or preventing any misload accidents during the process of spent fuel loading.