• Journal of Environmental Health Sciences
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• v.28 no.3
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• pp.1-8
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• 2002

The experiments for the characterization of inactivation were performed in a series of batch processes with the total coliform as a general indicator organism based on chlorine, chlorine dioxide and ozone as disinfectants. The water sam-ples were taken from the outlet of settling basin in a conventional surface water treatment system that is provided with the raw water drawn from the mid-stream of the Han River. The inactivation of total coliform was experimentally ana-lyzed for the dose of disinfectant contact time, pH, Temperature and DOC. The nearly 2.4,3.0,3.9 log inactivation of total coliform killed by injecting 1 mか1 at 5 minutes for chlorine, chlorine dioxide and ozone. For the inactivation of 99.9%(3 log), Disinfectants required were 1.70, 1.00 and 0.60 mか1 for chlorine, chlorine dioxide and ozone, respec-tively. The higher the pH is, the poorer the disinfections effects are in the range of pH 6-9 by using chlorine and ozone. But the irfluence of pH value on killing effects of chlorine dioxide is weak. The parameters estimated by the models of Chick-Watson, Hom, and Selleck from our experimental data obtained for chlorine are: log(N/ $N_{0}$ )=-0.16 CT with n= 1, log(N/ $N_{0}$ )=-0.71 $C^{0.87}$T with n$\neq$1, for Chicks-Watson model, log (N/ $N_{0}$ )= -1.87 $C^{0.47}$ $T^{0.36}$ for Hom model. For chlorine dioxide are: log(N/ $N_{0}$ )= -1.53 CT with n = 1, log(N/ $N_{0}$ )= -2.29 $C^{0.94}$T with n$\neq$1,, for Chicks-Watson model, log(N/ $N_{0}$ )= -3.64 $C^{0.43}$ $T^{0.24}$ for Hom model and for ozone are: log(N/ $N_{0}$ )= -2.59 CT with n = 1, log(N/ $N_{0}$ )= -2.28 $C^{0.36}$T with n$\neq$1, for Chicks-Watson model, log(N/ $N_{0}$ )= -4.53 $C^{0.26}$ $T^{0.19}$ for Hom model.19/ for Hom model.

• Radiation Oncology Journal
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• v.37 no.3
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• pp.166-175
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• 2019

Purpose: This study aimed to investigate neutrophil-to-lymphocyte ratio (NLR) and platelet-to-lymphocyte ratio (PLR) as prognostic factors in patients with locally advanced non-small cell lung cancer (NSCLC) who received concurrent chemoradiotherapy (CCRT). Materials and Methods: We retrospectively analyzed 66 patients with locally advanced NSCLC treated with definitive CCRT. Among these patients, 95% received paclitaxel/carboplatin or docetaxel/cisplatin. The median radiation dose was 66 Gy in 33 fractions. The NLR and PLR before/after CCRT were evaluated. The maximally selected log-rank test was used to obtain the cutoff values related to the overall survival (OS). Results: Patients with high post-CCRT NLR (>3.12) showed worse OS, locoregional progression-free survival (LRPFS), and distant metastasis-free survival (DMFS) than those with low NLR (2-year OS: 25.8% vs. 68.2%, p < 0.001; 2-year LRPFS: 12.9% vs. 33.8%, p = 0.010; 2-year DMFS: 22.6% vs. 38.2%, p = 0.030). Patients with high post-CCRT PLR (>141) showed worse OS and LRPFS than those with low PLR (2-year OS: 37.5% vs. 71.1%, p = 0.004; 2-year LRPFS: 16.5% vs. 40.3%, p = 0.040). Patients with high NLR change (>1.61) showed worse OS and LRPFS than those with low NLR change (2-year OS: 26.0% vs. 59.0%, p < 0.001; 2-year LRPFS: 6.8% vs. 31.8%, p = 0.004). The planning target volume (hazard ration [HR] = 2.05, p = 0.028) and NLR change (HR = 3.17, p = 0.025) were the significant factors for OS in the multivariate analysis. Conclusion: NLR change after CCRT was associated with poor prognosis of survival in patients with locally advanced NSCLC. An elevated NLR after CCRT might be an indicator of an increased treatment failure risk.

• Journal of the Korean Geotechnical Society
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• v.29 no.5
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• pp.29-38
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• 2013

The G-class cement is commonly used in practice for geothermal well cementing in order to protect a steel casing that is designed to transport hot water/steam from deep subsurface to ground surface during operating a geothermal power plant. In order to maintain optimal performance of geothermal wells, physical properties of the cementing material should be satisfactory. In this paper, relevant factors (i.e., groutability, uniaxial compression strength, thermal conductivity and free fluid content) of the G-class cement were experimentally examined with consideration of various water-cement (w/c) ratios. Important findings through the experiments herein are as follows. (1) Groutability of the G-class cement increases by adding a small dose of retarder. (2) There would be a structural defect caused when the w/c ratio is kept higher in order to secure groutability. (3) Thermal conductivity of the G-class cement is small enough to prevent heat loss from hot steam or water to the outer ground formation during generating electricity. (4) The G-class cement does not form free water channel in cementing a geothermal well. (5) The Phenolphthalein indicator is applicable to the distinction of the G-class cement from the drilling mud.

• Korean Journal of Ecology and Environment
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• v.52 no.1
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• pp.13-20
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• 2019

Heavy metals resulted from the increase of human industrial activity are introduced into the environment through rainfall and wastewater, and have harmful effects on inhabitants. In this study, we investigated biological responses such as survival rate, growth rate, emergence rate and sex ratio, and morphological effects of mentum deformity in Chironomus plumosus, an indicator organism to evaluate pollutions on aquatic ecosystem. The survival rate of C. plumosus showed time- and dose-dependent decrease after chromium and copper exposures. Growth rate decreased at $4^{th}$ day after chromium exposure and significantly reduced at exposure to relatively high concentration (copper $1000mg\;L^{-1}$) for all exposure times. In addition, we observed that the emergence rate by exposure to copper $1000mg\;L^{-1}$ was significantly lower than that of the control group. The imbalance of sex ratios showed at relatively low concentrations (chromium 10 and $50mg\;L^{-1}$) with the high proportion of female and at the relative high concentration (copper $1000mg\;L^{-1}$) with the high proportion of male. Furthermore, the morphological mentum deformities of C. plumosus observed in the exposed group according to chromium and copper exposure. These results suggest that the heavy metal exposure in environment may influence biosynthetic and morphological stresses of benthic invertebrate C. plumosus, and aquatic midge C. plumosus are potential indicators for toxicity assessment of heavy metals such as chromium and copper.

• Korean Journal of Radiology
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• v.21 no.10
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• pp.1165-1177
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• 2020

Objective: To assess the feasibility of applying a deep learning-based denoising technique to coronary CT angiography (CCTA) along with iterative reconstruction for additional noise reduction. Materials and Methods: We retrospectively enrolled 82 consecutive patients (male:female = 60:22; mean age, 67.0 ± 10.8 years) who had undergone both CCTA and invasive coronary artery angiography from March 2017 to June 2018. All included patients underwent CCTA with iterative reconstruction (ADMIRE level 3, Siemens Healthineers). We developed a deep learning based denoising technique (ClariCT.AI, ClariPI), which was based on a modified U-net type convolutional neural net model designed to predict the possible occurrence of low-dose noise in the originals. Denoised images were obtained by subtracting the predicted noise from the originals. Image noise, CT attenuation, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) were objectively calculated. The edge rise distance (ERD) was measured as an indicator of image sharpness. Two blinded readers subjectively graded the image quality using a 5-point scale. Diagnostic performance of the CCTA was evaluated based on the presence or absence of significant stenosis (≥ 50% lumen reduction). Results: Objective image qualities (original vs. denoised: image noise, 67.22 ± 25.74 vs. 52.64 ± 27.40; SNR [left main], 21.91 ± 6.38 vs. 30.35 ± 10.46; CNR [left main], 23.24 ± 6.52 vs. 31.93 ± 10.72; all p < 0.001) and subjective image quality (2.45 ± 0.62 vs. 3.65 ± 0.60, p < 0.001) improved significantly in the denoised images. The average ERDs of the denoised images were significantly smaller than those of originals (0.98 ± 0.08 vs. 0.09 ± 0.08, p < 0.001). With regard to diagnostic accuracy, no significant differences were observed among paired comparisons. Conclusion: Application of the deep learning technique along with iterative reconstruction can enhance the noise reduction performance with a significant improvement in objective and subjective image qualities of CCTA images.

• Radiation Oncology Journal
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• v.17 no.2
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• pp.136-140
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• 1999

Purpose : Prostate specific antigen (PSA) is a useful tumor marker, which is widely used as a diagnostic index and predictor of both treatment and follow-up result in prostate cancer. A prospective analysis was carried out to obtain the period of PSA normalization and the half life of PSA and to analyze the factors influencing the period of PSA normalization. The PSA level was checked before and serially after radical radiotherapy. Materials and Method : Twen쇼 patients with clinically localized prostate cancer who underwent radical external beam radiotherapy were enrolled in this study. Accrual period was from April 1993 to May 1998. Median follow-up period was 20 months. Radiotherapy was given to whole pelvis followed by a boost to prostate. Dose range for the whole pelvis was from 45 Gy to 50 Gy and boost dose to prostate, from 14 Gy to 20 Gy. The post-irradiation PSA normal value was under 3.0 ng/ml. The physical examination and serum PSA level evaluation were performed at 3 month interval in the first one year, and then at every 4 to 6 months. Results : PSA value was normalized in nineteen patients (95%) within 12 months. The mean period of PSA normalization was 5.3 (${\pm}$2.7) months. The half life of PSA Of the nonfailing patients was 2.1 (${\pm}$0.9) month. The nadir PSA level Of the nonfailing Patients waS 0.8 (${\pm}$0.5) ng/ml. The period of PSA normalization had the positive correlation with pretreatment PSA level (R$^{2}$=0.468). The nadir PSA level had no definite positive correlation with the pretreatment PSA level (R$^{2}$=0.075). The half life of serum PSA level also had no definite correlation with pretreatment PSA level (R$^{2}$=0.029). Conclusion :The PSA level was mostly normalized within 8 months (85%). If it has not normalized within 12 months, we should consider the residual disease in prostate or distant metastasis. In 2 patients, the PSA level increased 6 months or 20 months before clinical disease was detected. So the serum PSA level can be used as early diagnostic indicator of treatment failure.

• The Korean Journal of Nuclear Medicine
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• v.29 no.3
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• pp.343-349
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• 1995

Background : For biological dosimetry of radiation exposure, both observing hematologic change and calculating Ydr by chromosomal analysis as biological indicators are widely used. However, due to the lack of studies on biological dosimetry of radiation dose absorbed in the body such as in the cases of radioactive iodine therapy, the maximal and safe dose is not well known, nor is the extent to which the body can safely endure radiation exposure. Purpose : To investegate the practical applicability of hematologic changes and Ydr as an indicator for estimating radiation exposure, to patients with thyroid diseases after doses of radioactive iodine. Material and Methods : 5 patients with hyperthyroidism and 35 patients who have had thyroid cancer operation were under treatment with radioactive iodine, changes in number of lymphocytes were tracked and Ydr was calculated for more than 2 months by chromosomal analysis in peripheral lymphocytes. Results ; 1) The number of lymphocytes began to decrease 2 weeks after doses of radioactive iodine, and reached the nadir after 6 and 8 weeks, then gradually recovered. 2) The nadir count of lymphocytes was reversely correlated with the administered dosage of radioactive iodine. 3) Ydr was generally stable between 2 and 8 weeks. 4) The maximal value of Ydr was correlated with the administered dosage of radioactive iodine. 5) Ydr value at the 2nd week increased with augmented dosage of radioactive iodine. 6) Ydr value at the 2nd week was correlated with fall of lymphocyte count. Conclusion : Patients must be closely observed, because temporary bone marrow suppression and slight chromosomal aberration can be produced by even generally used dosages of radioactive iodine for diagnosis and therapy. Maximal percent fall of lymphocyte count, Ydr at the 2 week interval and maximal Ydr can be used as the biological predictor of administered dosage of radioactive iodine.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.48-56
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• 2014

Purpose $^{99m}Tc$-DTPA renal scintigraphy serves as a key indicator to measure a kidney donor's Glomerular Filtration Rate (GFR) and determine the possibility of kidney transplant. The Gates method utilized to measure GFR considers 3 variables of renal depth, injection dose, and net kidney counts. In this research, we seek to compare changes in kidney donors' GFR according to renal depth measurement methods of the 3 variables. Materials and Methods We investigated 32 kidney donors who had visited the hospital from October, 2013 to March, 2014 and received abdominal CT and $^{99m}Tc$-DTPA GFR examination. With the cross-section image of the CT and the lateral image from a gamma camera, we measured the renal depth and compared with renal depth calculation equations-Tonnesen, Taylor, and Itoh methods. Renal depth-specific GFR was calculated by using Xeleris Ver. 2.1220 of GE. Then the results were compared with MDRD (Modification of Diet Renal Disease) GFRs based on serum creatinine level. Results The renal depths measured based on the CT and gamma camera images showed high correlation. Tonessen equation gave the lowest GFR value while the value calculated by using the renal depth of CT image was the highest with a 16.62% gap. MDRD GFR showed no statistically significant difference among values calculated through Taylor, Itoh, CT and gamma camera renal depth application (P>0.05), but exhibited a statistically significant change in the value based on Tonnesen equation (P<0.05). Conclusion This research has found that, in GFR evaluation in kidney donors by utilizing $^{99m}Tc$-DTPA, Tonnesen equation-based Gates method underestimated the value than the MDRD GFR. Therefore, if a MDRD GFR value shows a huge difference from the actual examination value, using an image-based renal depth measurement, instead of Tonnesen equation applied to Gates method, is expected to give an accurate GFR value to kidney donors.

• Korean Journal of Environmental Biology
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• v.32 no.3
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• pp.243-249
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• 2014

In this study, we evaluated the toxic effects of heavy metals (Cd, Cu, Zn) on the population growth rate (r) of the marine diatom, Skeletonema costatum. S. costatum. The population growth rate (r) of the species was determined after 96 hrs. of exposure to Cd (0, 0.63, 1.25, 2.50, 5.00, 10.00 ppm), Cu (0, 0.25, 0.50, 0.75, 1.00, 1.25, 1.50 ppm) and Zn (0, 0.31, 0.63, 1.25, 2.00, 2.50, 5.00 ppm). It was observed that 'r' in the control (absence of Cd, Cu and Zn) were greater than 0.05, however suddenly decreased with increased heavy metal concentrations. Cd, Cu and Zn reduced 'r' in a dose-dependent manner and a significant reduction were occurred at concentration of greater than 1.25, 1.25 and 2.50 ppm, respectively. Based on the toxicity, the heavy metal were ranked as Cu>Zn>Cd, with EC50 values of 1.11, 2.13 and 6.84 ppm, respectively. The lowest-observed-effective-concentration (LOEC) of 'r' in exposed to Cd, Cu and Zn were 1.25, 1.00, 2.00 ppm, respectively. Precisely, a concentration of greater than 1.25 ppm of Cd, 1.00 ppm of Cu and 2.00 ppm of Zn in marine ecosystems induced toxic effect on the 'r' of S. costatum. Based on our results, we suggested that the 'r' of S. costatum might be a useful bio indicator for the toxicity assessment of heavy metals in marine ecosystems.

• Journal of Life Science
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• v.27 no.2
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• pp.202-210
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• 2017

As an effort to find a potential biopreservative, we isolated bacterial strains producing bacteriocin from fermented foods. A strain was finally selected and characteristics of the bacteriocin were investigated. The selected strain was identified as Bacillus subtilis E9-1 based on the 16S rRNA gene analysis. The culture supernatant of B. subtilis E9-1 showed antimicrobial activity against Gram-positive bacteria. Subtilisin A, ${\alpha}$-chymotrypsin, trypsin and proteinase K inactivated the antimicrobial activity, which means its proteinaceous nature, a bacteriocin. The bacteriocin activity was fully retained at the pH range from 2.0 to 8.0 and stable at up to $100^{\circ}C$ for 60 min. Solvents such as ethanol, isopropanol and methanol had no effect on the antimicrobial activity at the concentration of 100% but acetone and acetonitrile reduced the activity at up to 100% concentration. Cell growth of four indicator strains was dramatically decreased in dose-dependent manner. Listeria monocytogenes was the most sensitive, but Enterococcus faecium was the most resistant. Bacillus cereus and Staphylococcus aureus showed the medium sensitivity. The bacteriocin showed its antimicrobial activity against B. cereus and L. monocytogenes via bactericidal action. The number of viable cells of L. monocytogenes started to reduce after addition of bacteriocin to the minced beef. The bacteriocin was purified through acetone concentration, gel filtration chromatography and RP-HPLC. The whole purification step led to a 6.82 fold increase in the specific activity and 6% yield of bacteriocin activity. The molecular weight of the purified bacteriocin was determined to be 3.3 kDa by MALDI-TOF/TOF mass spectrometry.