• Journal of Korean Society of Environmental Engineers
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• v.35 no.4
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• pp.276-282
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• 2013

The reclaimed water has been highlighted as a representative alternative to solve the lacking water resources. This study examined the reduction of residual free chlorine by temperature (5, 15, $25^{\circ}C$) and initial injection concentration (1, 2, 4, 6 mg/L) in the reclaimed water and carried out propose on the calculating method of the optimal chlorine dosage. As the reclaimed water showed a very fast reaction with chlorine at the intial time comparing to that of drinking water, the existing general first-order decay model ($C_t=C_o(e^{-k_bt})$) was not suitable for use. Accordingly, the reduction of residual free chlorine could be estimated in a more accurate way as a result of applying the exponential first-order decay model ($C_t=a+b(e^{-k_bt})$). ($r^2$=0.872~0.988). As a result of calculating the bulk decay constant, it showed the highest result at 653 $day^{-1}$ under the condition of 1 mg/L, $25^{\circ}C$ for the initial injection whereas it showed the lowest result at 3.42 $day^{-1}$ under the condition of 6 mg/L, $5^{\circ}C$ for the initial injection. The bulk decay constant tends to increase as temperature increases, whereas the bulk decay constant tends to decrease as the initial injection concentration increases. More accurate calculation for optimal chlorine dosage could be done by using the experimental results for 30~5,040 min, after the entire response time is classified into 0~30 min and 30~5,040 min to calculate the optimal chlorine dosage. In addition, as a result of calculating the optimal chlorine dosage by temperature, the relationships of initial chlorine demand (y) by temperature (x) could be obtained such as y=1.409+0.450x to maintain 0.2 mg/L of residual free chlorine at the time after 4 hours from the chlorine injection.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.5
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• pp.429-435
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• 2009

Purpose: The purpose of this study was to assess the prognostic value of preoperative FDG-PET in colorectal cancer (CRC) patients with hepatic metastasis (HM). Materials and Methods: 24 CRC patients (M:F=14:10; age, $63{\pm}10$ yrs) with HM who had undergone preoperative FDG PET were included. Cure-intent surgery was performed in all the patients and HMs were controlled using resection (n=13), radio-frequency ablation (RFA) (n=7), and resection plus RFA (n=4). Potential prognostic markers tested were maxSUV of primary tumor, maxSUV of HM, maxSUV ratio of HM over primary tumor (M/P ratio), histologic grade, CEA level, venous/lymphatic/nerve invasion, T stage, N stage, no. of HM, no. of lymph node metastasis, and treatment modality of HM. Results: 14 CRC patients developed a recurrence with a median follow-up duration of 244 days, whereas 10 patients did not develop recurrence with a median follow-up duration of 504 days. M/P ratios but other potential prognostic markers were significantly higher in the recurrent patients ($0.72{\pm}0.14$) than recurrence-free patients ($0.54{\pm}0.23$) (p=0.038). M/P ratio only was found to predict recurrence by Cox multivariate analysis (hazard ratio 37.7, 95% confidence interval 2.01-706.1, p=0.016). The 11 patients with lower M/P ratio of <0.61 had significantly better disease-free survival rate than the 13 patients with higher M/P ratio (${\geq}0.61$) (p=0.026). Conclusion: maxSUV ratio of HM over primary tumor (M/P ratio) may be useful for prognosis prediction of CRC patients with HM. Higher FDG uptake of HM than that of primary tumor may indicate a more advanced status in stage IV CRC.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.19 no.1
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• pp.66-75
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• 2014

This study aims to understand environmental factors that determine spatial distribution of macrozoobenthic community in the southern area (ca 100-500 m depth) of East Sea, Korea, known as a candidate site for carbon storage under the seabed. From sixteen locations sampled in the summer of 2012, a total of 158 species were identified, showing density of $843indiv/m^2$ and biomass of $26.2g\;WW/m^2$, with increasing faunal density towards biologically higher diverse locations. Principal component analysis showed that a total of 33 environmental parameters were reduced to three principal components (PC), indicating sediment, bottom water, and depth, respectively. As sand content was increasing, number of species increased but biomass decreased. Six dominant species including two bivalve species favored high concentrations of ${\Omega}$ aragonite and ${\Omega}$ calcite, indicating that the corresponding species can be severely damaged by ocean acidification or $CO_2$ effluent. Cluaster analysis based on more than 1% density dominant species classified the entire study area into four faunal assemblage (location groups), which were delineated by characteristic species, including (A) Ampelisca miharaensis, (B) Edwardsioides japonica, (C) Maldane cristata, (D) Spiophanes kroeyeri, and clearly separated in terms of geography, bottom water and sediment environment. Overall, a discriminant function model was developed to predict four faunal assemblages from five simply-measured environmental variables (depth, sand content in sediment, temperature, salinity and pH in bottom water) with 100% accuracy, implying that benthic faunal assemablages are closed linked to certain combinations of abiotic factors.

• Korean Journal of Soil Science and Fertilizer
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• v.43 no.6
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• pp.954-961
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• 2010

Ground-based remote sensing can be used as one of the non-destructive, fast, and real-time diagnostic tools for quantifying yield, biomass, and nitrogen (N) stress during growing season. This study was conducted to assess biomass and nitrogen (N) status of paddy rice (Oryza sativa L.) plants under N stress using passive and active ground-based remote sensors. Nitrogen application rates were 0, 70, 100, and 130 kg N $ha^{-1}$. At each growth stage, reflectance indices measured with active sensor showed higher correlation with DW, N uptake and N concentration than those with the passive sensor. NIR/Red and NIR/Amber indices measured with Crop Circle active sensors generally had a better correlation with dry weight (DW), N uptake and N content than vegetation indices from Crop Circle passive sensor and NDVIs from active sensors. Especially NIR/Red and NIR/amber ratios at the panicle initiation stage were most closely correlated with DW, N content, and N uptake. Rice grain yield, DW, N content and N uptake at harvest were highly positively correlated with canopy reflectance indices measured with active sensors at all sampling dates. N application rate explains about 91~92% of the variability in the SI calculated from NIR/Red or NIR/Amber indices measured with Crop Circle active sensors on 12 July. Therefore, the in-season sufficiency index (SI) by NIR/Red or NIR/Amber index from Crop Circle active sensors can be used for determination of N application rate.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.4
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• pp.363-371
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• 2023

To construct a ship, blocks of various sizes must be moved and erected . In this process, lugs are used such that they match the block fastening method and various functions suitable for the characteristics of each shipyard facility. The sizes and shapes of the lugs vary depending on the weight and shape of the block structures. The structure is reinforced by welding the doubling pads to compensate for insufficient rigidity around the holes where the shackle is fastened. As for the method of designing lugs according to lifting loading conditions, a simple calculation based on the beam theory and structural analysis using numerical modeling are performed. In the case of the analytical method, a standardized evaluation method must be established because results may differ depending on the type of element and modeling method. The application of this ambiguous methodology may cause serious safety problems during the process of moving and turning-over blocks. In this study , the effects of various parameters are compared and analyzed through numerical structural analysis to determine the modeling conditions and evaluation method that can evaluate the actual structural response of the lug. The modeling technique that represents the plate part and weld bead around the lug hole provides the most realistic behavior results. The modeling results with the same conditions as those of the actual lug where only the weld bead is connected to the main body of the lug, showed a lower ulimated strength compared with the results obtained by applying the MPC load. The two-dimensional shell element is applied to reduce the modeling and analysis time, and a safety working load was verified to be predicted by reducing the thickness of the doubling pad by 85%. The results of the effects of various parameters reviewed in the study are expected to be used as good reference data for the lug design and safe working load prediction.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.1
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• pp.9-16
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• 2013

An experiment was conducted to evaluate the biochemical adverse effect of increased carbon dioxide in seawater on marine polychaete, Perinereis aibuhitensis. We measured the available energy reserves, Ea (total carbohydrate, protein, and lipid content) and the energy consumption, Ec (electron transport activity) of Perinereis aibuhitensis exposed for 7-d to a range of $CO_2$ concentration such as 0.39 (control =390 ppmv), 3.03 (=3,030 ppmv), 10.3 (=10,300 ppmv), and 30.1 (=30,100 ppmv) $CO_2$ mM, respectively. The cellular energy allocation (CEA) methodology was used to assess the adverse effects of toxic stress on the energy budget of the test organisms. The results of a decrease in CEA effect of increased carbon dioxide in seawater from all individual in Ea and Ec. Increase of carbon dioxide reduced pH in seawater, significantly. The chemical changes in sea- water caused by increasing $pCO_2$ might cause stresses to test organisms and changes in the cellular energy allocations. Results of this study can be used to understand the possible influence of $CO_2$ concentration increased by the leakage from sub-sea bed storage sites as well as fossil fuel combustion on marine organisms.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.4
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• pp.191-198
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• 2008

To design a reliable $CO_2$ marine geological storage system, it is necessary to perform numerical process simulation using thermodynamic equation of state. $CO_2$ capture process from the major point sources such as power plants, transport process from the capture sites to storage sites and storage process to inject $CO_2$ into the deep marine geological structure can be simulate with numerical modeling. The purpose of this paper is to compare and analyse the relevant equations of state including ideal, BWRS, PR, PRBM and SRK equation of state. We also studied the effect of thermodynamic equation of state in designing the compression and transport process. As a results of comparison of numerical calculations, all relevant equation of state excluding ideal equation of state showed similar compression behavior in pure $CO_2$. On the other hand, calculation results of BWRS, PR and PRBM showed totally different behavior in compression and transport process of captured $CO_2$ mixture from the oxy-fuel combustion coal-fired plants. It is recommended to use PR or PRBM in designing of compression and transport process of $CO_2$ mixture containing NO, Ar and $O_2$.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.5 no.1
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• pp.21-30
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• 1985

The tension leg platform (TLP) is a kind of compliant structures, and is also a type of moored stable platform with a buoyancy exceeding the weight because of having tensioned vertical anchor cables. In this paper, among the various kinds of tension leg structures, Deep Oil Technology (DOT) TLP was analyzed because it has large-displacement portions of the immersed surface such as vertical corner pontoons and small-diameter elongated members such as cross-bracing. It also has results of hydraulic model tests, comparable with theorectical analysis. Because of the vertical axes of symmetry in the three vertical buoyant legs and because there are no larger horizontal buoyant members between these three vertical members, it was decided to develop a numerical algorithm which would predict the dynamic response of the DOT TLP using the previously developed numerical algorithm Floating Vessel Response Simulation (FVRS) for vertically axisymmetric bodies of revolution. In addition, a linearized hydroelastic Morison equation subroutine would be developed to account for the hydrodynamic pressure forces on the small member cross bracing. Interaction between the large buoyant members or small member cross bracings is considered to be negligible and is not included in the analysis. The dynamic response of the DOT TLP in the surge mode is compared with the results of the TLP algorithm for various combinations of diffraction and Morison forces and moments. The results which include the Morison equation are better than the results for diffraction only. This is because the vertically axisymmetric buoyant members are only marginally large enough to consider diffractions effects. The prototype TLP results are expected to be more inertially dominated.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.2
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• pp.120-128
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• 2009

Purpose: Early detection of recurrence is an important factor for long term survival of patients with colorectal cancer. Measurement of serum levels of CEA, CA 19-9, CT and PET/CT has been commonly used in the postoperative surveillance of colorectal cancer. The purpose of this study was to compare the diagnostic ability of PET/CT, tumor marker and CT for recurrence in colorectal cancer patients after treatment. Materials and Methods: F-18 FDG PET/CT imaging was performed in 189 colorectal cancer patients who underwent curative surgical resection and/or chemotherapy. Measurement of serum levels of CEA, CA 19-9 and CT imaging were performed within 2 months of PET/CT examination. Final diagnosis of recurrence was made by biopsy, radiologic studies or clinical follow-up for 6 months after each study. Results: Overall sensitivity, specificity of PET/CT was 94.7%, 91.1%, while those of serum CEA were 44.7% and 97.3%, respectively. Sensitivity and specificity were 94.2%, 90.4% for PET/CT and better than those of combined CEA and CA 19-9 measurement(52.1%, 88.5%) in 174 patients measured available both CEA and CA 19-9 data. In 115 patients with both tumor markers and CT images available, PET/CT showed similar sensitivity but higher specificity(92.9%, 91.3%) compared to combination of tumor markers and CT images(92.9%, 74.1%). Conclusion: PET/CT was superior for detection of recurred colorectal cancer patients compared with both CEA, CA 19-9, and even with combination of both tumor markers and CT. Therefore PET/CT could be used as a routine surveillance examination to detect recurrence or metastasis of colorectal cancer.

• Journal of the Korean Society for Marine Environment & Energy
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• v.18 no.2
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• pp.94-101
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• 2015

To mitigate the greenhouse gas emission, many carbon capture and storage projects are underway all over the world. In Korea, many studies focus on the storage of $CO_2$ in the offshore sediment. Assurance of safety is one of the most important issues in the geological storage of $CO_2$. Especially, the assessment of possibility of leakage and amount of leaked $CO_2$ is very crucial to analyze the safety of marine geological storage of $CO_2$. In this study, the leakage of injected $CO_2$ through fault was numerically studied. TOUGH2-MP ECO2N was used to simulate the subsurface behavior of injected $CO_2$. The storage site was 150 m thick saline aquifer located 825 m under the continental shelf. It was assumed that $CO_2$ leak was happened through the fault located 1,000 m away from the injection well. The injected $CO_2$ could migrate through the aquifer by both pressure difference driven by injection and buoyancy force. The enough pressure differences made it possible the $CO_2$ to migrate to the bottom of the fault. The $CO_2$ could be leaked to seabed through the fault due to the buoyancy force. Prior to leakage of the injected $CO_2$, the formation water leaked to seabed. When $CO_2$ reached the seabed, leakage of formation water stopped but the same amount of sea water starts to flow into the underground as the amount of leaked $CO_2$. To analyze the effect of injection rate on the leakage behavior, the injection rate of $CO_2$ was varied as 0.5, 0.75, and $1MtCO_2/year$. The starting times of leakage at 1, 0.75 and $0.5MtCO_2/year$ injection rates are 11.3, 15.6 and 23.2 years after the injection, respectively. The leakage of $CO_2$ to the seabed continued for a period time after the end of $CO_2$ injection. The ratios of total leaked $CO_2$ to total injected $CO_2$ at 1, 0.75 and $0.5MtCO_2/year$ injection rates are 19.5%, 11.5% and 2.8%, respectively.