• Applied Biological Chemistry
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• v.38 no.5
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• pp.468-472
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• 1995

Substantial amount of caryophyllene oxide (CPO) is present in the essential oils of traditionally-used folk medicinal plants and herbal spices. The CPO, produced via chemical and/or enzymatic reaction of caryophyllene (CP), has largely being used as a flavoring component and exhibited a variety of biological activities. Now, we report the antimutagenic activity of CPO determined by Ames's preincubation test. S-9 fraction was prepared from the liver of rats treated with Arochor 1254. Anatoxin $B_1\;(AFB_1)$ and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) were used as mutagens. Reduction of mutagenicity of $AFB_1$ or IQ for S. typhimurium TA98 and TA100 by CPO was found to be a dose-dependant manner. CPO (500 ${\mu}g/plate$) reduced mutagenicity of AEB1 for S. typhimurium TA98 and TA100 to 89% and 71%, respectively. For IQ, similar results were observed against S. typhimurium TA98 and TA100, resulting in the inhibition percentage of 77% and 51%, respectively. CP also reduced mutagenicity of AEB1 and IQ for S. typhimurium TA98 and TA100, but the reduction rate was somewhat lowered relative to that of CPO. These results indicate that CPO could be developed as a potent antimutagenic flavoring agent.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.2
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• pp.137-147
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• 2008

Statement of problem: Dental implant procedure has been recognized as a very effective treatment to rehabilitate fully or partially edentulous patients. However, mechanical failures such as screw loosening, screw fracture have been still reported frequently. Purpose: The purpose of this study was to evaluate the influence of tungsten carbide/carbon coating, which has superior hardness and frictional wear resistance, on implant-abutment screw loosening of three different joint connections after one million cyclic loading. Material and methods: The values of detorque before and after loading were measured in three different joint connections (Osstem Implant, Korea), one external butt joint, US II implant system and two internal cones, SS II and GS II system. The values of detorque before loading was analyzed by one-way ANOVA, and two-way ANOVA and Scheffe' test were performed for the value of detorque after loading. Results: 1. The values of initial detorque of tungsten carbide/carbon coated Ti alloy screw were smaller those of Ti alloy screw (P<.01), and there were no differences among implant systems in each screw (P>.05). 2. In comparison of loss rate of detorque value after cyclic loading, US II system was greater than SS II and GS II system but there was no difference between SS II and GS II system (P<.01). 3. Loss rates of detorque value after cyclic loading decreased consistently at tungsten carbide/carbon coated Ti alloy screw comparing with Ti alloy screw in all implant systems (P<.01), and there were no differences among three systems in reduction of loss rates by using tungsten carbide/carbon coated Ti alloy screw (P>.05). Conclusion: Tungsten carbide/carbon coating to increase preload with reduction of friction resistance was a effective way to decrease screw loosening by functional loading.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.1
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• pp.51-57
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• 2009

Biofouling in seawater reverse osmosis (SWRO) desalination process causes many problems such as flux decline, biodegradation of membrane, increased cleaning time, and increased energy consumption and operational cost. Therefore biofouling is considered as the most critical problem in system operation. To control biofouling in early stage, detection of the most problematic bacteria causing biofouling is required. In this study, six model bacteria were chosen; Bacillus sp., Flavobacterium sp., Mycobacterium sp., Pseudomonas aeruginosa, Pseudomonas fluorescens, and Rhodobacter sp. based on report in the literature and phylogenetic analysis of seawater intake and fouled RO membrane. The adhesion to RO membrane, the high pressure resistance, and the hydrophobicity of the six model bacteria were examined to find out their fouling potential. Rhodobacter sp. and Mycobacterium sp. were found to attach very well to RO membrane surface compared to others used in this study. The test of hydrophobicity revealed that the bacteria which have high hydrophobicity or similar contact angle with RO membrane ($63^{\circ}$ of contact angle) easily attached to RO membrane surface. P. aeruginosa which is highly hydrophilic ($23.07^{\circ}$ of contact angle) showed the least adhesion characteristic among six model bacteria. After applying a pressure of 800 psi to the sample, Rhodobacter sp. was found to show the highest reduction rate; with 59-73% of the cells removed from the membrane under pressure. P. fluorescens on the other hand analyzed as the most pressure resistant bacteria among six model bacteria. The difference between reduction rates using direct counting and plate counting indicates that the viability of each model bacteria was affected significantly from the high pressure. Most cells subjected to high pressure were unable to form colonies even thought they maintained their structural integrity.

• Journal of fish pathology
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• v.31 no.1
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• pp.41-48
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• 2018

The utility of Bacillus spp. organisms for reduction of dissolved hydrogen sulfide ($H_2S$) in white leg shrimp (Litopenaeus vannamei) culture was tested with different combinations of Bacillus spp. microorganisms: combination A (B. subtilis + B. licheniformis); combination B (B. licheniformis + B. amyloliquefaciens); combination C (B. subtilis + B. licheniformis + B. amyloliquefaciens). Of these 3 combinations, C was effective in few hours after addition whereas B needed longer time to be effective. The $H_2S-reducing$ effect of combination C was dependent on the amount of microorganisms added to $H_2S-containing$ test solution. Exposure of white leg shrimp to $H_2S$ at 8 mg/L for 7 days led to survival of 80% and 1 mg/L for 14 days it was 82.5%. The survival rate was 97.5% when combination C was simultaneously added to shrimp tanks during $H_2S$ exposure at 1 mg/L for 14 days. It was demonstrated that combination C microorganisms (B. subtilis + B. licheniformis + B. amyloliquefaciens) can reduce dissolved $H_2S$ concentrations, and this effect can be utilized to protect white leg shrimp from $H_2S$ toxicity.

• The Korean Journal of Nuclear Medicine Technology
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• v.14 no.2
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• pp.33-37
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• 2010

Purpose: In the early stage of using PET/CT, it was used to damper revision but recently shows that CT with MDCT is commonly used and works well for an anatomical diagnosis. This hospital makes the accuracy and convenience more higher in the diagnosis and evaluate of coronary heart disease through concurrently running myocardial perfusion SPECT examination, myocardial PET examination with FDG, and CT coronary artery CT angiography(coronary CTA) used PET/CT with 64-slice. This report shows protocol and image based on results from about 400 coronary heart disease examinations since having 64 channels PET/CT in July 2007. Materials and Methods: An Equipment for this examination is 64-slice CT and Discovery VCT (DVCT) that is consisted of PET with BGO ($Bi_4Ge_3O_{12}$) scintillation crystal by GE health care. First myocardial perfusion SPECT with pharmacologic stress test to reduce waiting time of a patient and get a quick diagnosis and evaluation, and right after it, myocardial FDG PET examination and coronary CTA run without a break. One-stop evaluation protocol of ischemic heart disease is as follows. 1)Myocardial perfusion SPECT with pharmacologic stress: A patient is injected with $^{99m}Tc$-MIBI 10 mCi and does not have any fatty food for myocardial PET examination and drink natural water with ursodeoxcholic acid 100 mg and we get SPECT image in an hour. 2)Myocardial FDG PET: To reduce blood fatty content and to increase uptake of FDG, we used creative oral glucose load using insulin and Acipimox to according to blood acid content. A patient is injected with $^{18}F$-FDG 5 mCi for reduction of his radiation exposure and we get a gated image an hour later and get delay image when we need. 3) Coronary CTA: The most important point is to control heart rate and to get cooperation of patient's breath. In order to reduce a heart rate of him or her below 65 beats, let him or her take beta blocker 50 mg ~ 200 mg after a consultation with a doctor about it and have breath-practices then have the examination. Right before the examination, we spray isosorbide dinitrate 3 to 5 times to lower tension of bessel wall and to extension a blood wall of a patient. It makes to get better the shape of an anatomy. At filming, a patient is injected CT contrast with high pressure and have enough practices before the examination in order to have no problem. For reduction of his radiation exposure, we have to do ECG-triggered X-ray tube modulation exposure. Results: We evaluate coronary artery stenosis through coronary CTA and study correlation (culprit vessel check) of a decline between stenosis and perfusion from the myocardial perfusion SPECT with pharmacologic stress, coronary CTA, and can check viability of infarction or hibernating myocardium by FDG PET. Conclusion: The examination makes us to set up a direction of remedy (drug treatment, PCI, CABG) because we can estimate of effect from remedy, lesion site and severity. In addition, we have an advantage that it takes just 3 hours and one-stop in that all of process of examinations run in succession and at the same time. Therefore it shows that the method is useful in one stop evaluation of ischemic heart disease.

• Quality Improvement in Health Care
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• v.10 no.2
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• pp.176-189
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• 2003

Background : Gastric cancer is the most common malignant tumor in Korea. Surgical operation is one of the major treatment modalities for gastric cancer patients. Therefore, gastrectomy is one of the most common procedures in General Surgery. There were variation in length of hospital stay and medical treatment for gastrectomy between three surgeons at Asan Medical Center. Clinical pathways have received considerable attention as a tool for reducing the medical practice variation, increasing the efficiency of care process, and improving the quality of care. The aim of this study was to evaluate the effect of a clinical pathway for gastrectomy in gastric cancer patients. Methods : The clinical pathway for gastrectomy was developed and implemented by a multidisciplinary group in Asan Medical Center. A computerized clinical pathway program was developed and revised after a pilot test. A total of 145 patients underwent gastrectomy by three surgeons at Asan Medical Center. We compared the length of hospital stay, patient satisfaction, and the unplanned readmission rate between the pre-pathway group (n=67) and the post-pathway group (n=78). We also investigated the degree of satisfaction among the physicians and nurses who were main end-users of the clinical pathway. Results : The clinical pathway was applied to all target patients. The average length of hospital stay was shortened from 12.7days to 10.6days (p<0.01). The degree of patient satisfaction with the care process changed from 90.3% to 89.2% after the implementation of the clinical pathway, but the difference was not statistically significant (p=0.761). Unplanned readmission rate was 2.9% in the pre-pathway group and 0% in the post-pathway group. More than 90% of physicians and nurses answered that the clinical pathway had been a useful tool in their medical practice. Conclusions : The findings of the study demonstrated that implementation of the clinical pathway for gastrectomy produced substantial reduction in the length of hospital stay while improving the quality of patient outcomes. The computerized clinical pathway program can be used as one of the powerful patient management tools for reducing the practice variations and increasing the efficiency of care process in Korean hospital settings.

• Journal of Korean Public Health Nursing
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• v.7 no.2
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• pp.53-66
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• 1993

By this time, a few of previous studies of factors related to separation from their jobs and job satisfaction only have dealt with the separation rate. the cause of separation and related factors that induce job satisfaction and incentive factors, the actualities of morale some suggestions for reduction of the separation rate. This study is attempted to determine factors that have effect on job satisfaction of national hospital nurses. and to proide information and materials for the development of the administration of nursing through the appreciation of factors influencing on job satisfaction between isolated ward nurses and general ward nurses working at national hospitals. 185 nurses of national hospitals responsed th this study, and were divided into two groups. Group 1: 57 nurses working at isolated wards for tuberculosis patients and Group 2 : 128 nurses at general wards. Relevant data were collected from August, 5, 1992 through August 20, 1992. The questionnaire consisted of 8 genalized items and 4 items concerning job satisfaction. The collected data were processed with SPSS, and the relationship among vaviables was analyzed by means of $X^2-test$, Pearson Correlation, Multiple Regression. The results of this study are as follows: 1. There is no significant difference between two groups in terms of generalized items. Age distributions show $44.3\%$ under the category of less than 34. and $55.7\%$ under the category more than 35, $19.3%$ was single and $74.6\%$ was married respectively. 2. $79.4\%$ of the nurses have the desire to have in-service education under the satisfactory physical environments such as welfare system, accommodating structures and facilities, instruments or management systems of the hospital, but under the category of unsatisfactory circumstances, $60.3\%$ have the intention of having in- service education. The concern in terms of in-service education shows statistically significant difference between two groups $(X^2=8.85,\;p<0. 05)$. This result accepts the hypothesis that good physical environments could intensify interests in service education. 3. The extent of satisfaction related to psychological environments is heightend according to good physical environments. In result, the hypothesis that the extent of satisfaction in terms of physical environments could raise satisfaction about psychological environment is accepted. 4. In the light of the extent of satisfaction about physical environments, $33.3\%$ of isolated ward nurses are satisfied with physical environments, but only $11.7\%$ of general ward nurses are satisfied. $(X^2=10.88,\; p<0.01)$. This result shows that the satisfaction degree about phusicalenvironments of isolated war nurses was higher than that of general ward nurses in spite of high physical and psychological risks due to exposure to infection. Consequently. the hypothesis was rejected that the satisfaction degree about physical environments would be lower in isolated ward nurses than in general ward nurses. 5. The fact that $87.7%$ of isolated ward nurses took interest in service education and $53.19\%$ of general ward nurses took interest in service education demonstrats that isolated ward nurse have more interest in service education than gerneral ward nurses. The result shows that the hypothesis is accepted that isolated ward nurses would have mor interests in service education than general ward nurses. 6. In the extent of satisfaction about physical environments such as morale human relationship promotion, there is no significant difference between two groups in terms of statistics. The hypothesis is rejected that satisfaction about psychologic environments would be high in isolated ward nurses than in general ward nurses. In conclusion. factors influencing on job satisfaction are considered to have effect on. another, and also interdisciplinary amelioration of factors accompanied with systematic inter cooperative investigation is necessary.

• Journal of the Korean Chemical Society
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• v.56 no.6
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• pp.751-758
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• 2012

In this study, we analyzed career paths and college life plans of department of chemistry education students in teacher's college examined by their roadmaps. We let students make their roadmaps and analyzed them using the PASW 18 program. There were significant differences on gender in their career paths, learning English, traveling and volunteer activity. Female students for passing the MEET(Medical Education Eligibility Test) or DEET(Dental Education Eligibility Test) were more interested in learning English and traveling than male students. In addition, female students were more interested in volunteer activity. And the lower year students, the more interested in medical paths, learning English, traveling, getting good grades, exchange student program and scholarship. On the other hand the higher year students, the more interested in group study or E-learning. Then significant differences were in learning English, traveling and getting good grades by students's career paths. Students who wish to pass the MEET or DEET were more interested in learning English and getting good grades. Those two factors were essential in passing the MEET or DEET. Students who did not specified their career paths had more traveling plans than other students for setting their directions of careers. These results show that freshman and female students don't recognize the identity of teacher's college correctly. Because of reduction in the number of teacher recruitment according to decrease of students by birth rate drop, students in teacher's college are expected to continue like this trend that students look for other paths. Therefore, it is required career counseling and guidance for students who give priority practical path choices and college life plans over original characteristics of teacher's college. And it should be reconsidered the direction of chemistry education prepared the identity of teacher's college reflected in this actuality.

• The Korean Journal of Nuclear Medicine Technology
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• v.18 no.2
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• pp.17-21
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• 2014

Purpose With the recent rise of social issue regarding radiation exposure, attention to medical radiation use has been placed under a great spotlight. During PET-CT examination, generally about 40% more of $^{18}F$-FDG is used than EANM recommendation. While maintaining the diagnostic test result, we hope to find optimal injection dose to minimize the $^{18}F$-FDG in patients by utilizing the latest PET-CT scanner which is equiped with the newest technology. Materials and Methods During this experiment, the Biograph Truepoint 40 (siemens, USA) installed in 2007 and mCT 64 (siemens, USA) installed in 2011 were used and evaluated NECR (noise-equivalent counting rate) by using a scatter phantom. For the image quality evaluation of each scanner, we injected 3.7, 4.44 and 5.18 MBq/kg of $^{18}F$-FDG in NEMA IEC Body Phantom and also evaluated SNR between two scanners by using the data acquired at 60, 70, 80, 90, 100, 110 and 120 sec per bed. For the clinical evaluation, actual data of patients who were injected $^{18}F$-FDG 3.7, 4.44, 5.18 MBq/kg were used to compare SNR and draw a final result. Results As a result, mCT 64 peak NECR value was 1.65e+005, which is 10% higher than Turepoint 40. SNR values using the IEC body phantom was 17.9%, 17.4% and 17.1% higher in $^{18}F$-FDG 3.7 MBq/kg, 4.44 MBq/kg and 5.18 MBq/kg. In clinical patients, SNR values of the image mCT 64 was 16.5, which is 25% higher than Turepoint 40 scanner. Conclusion To draw a conclusion from the test result of this experiment, the same quality of SNR could be attained even with 10% reduced injection dose, if when the duration is extended by 10 sec/bed. This optimal result was possible due to enhanced equipment. The NECR (one of the equipment's performance assessment criteria for the scanner) increased by 10% and the SNR (one of the image quality assessment criteria) also increased by 17.5%. Therefore, we can expect to reduce the injection dose without deterioration of image quality. In consequence, it will also help to decrease the patient's anxiety of the radiation exposure.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.47-56
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• 2020

In this study, three levels of W/B(Water to Binder) ratio (0.37, 0.42, 0.47) and substitution ratio of GGBFS (Ground Granulated Blast Furnace Slag) rate (0 %, 30 %, 50 %) were considered to perform RCPT (Rapid Chloride Diffusion Test) at the 1,095 aged day. Accelerated chloride diffusion coefficient and passed charge of each concrete mixture were assessed according to Tang's method and ASTM C 1202, and improving behaviors of durability performance with increasing aged days are analyzed based on the test results of previous aged days from the preceding study. As the age of concrete increases, the passed charge and diffusion coefficient have been significantly reduced, and especially the concrete specimens containing GGBFS showed a significantly more reduction than OPC(Ordinary Portland Cement) concrete specimen by latent hydraulic activity. In the case of OPC concrete's results of passed charge, at the 1,095 days, two of them were still in the "Moderate" class. So, if only OPC is used as the binder of concrete, the resistance performance for chloride attack is weak. In this study, the time-parameters (m) were derived based on the results of the accelerated chloride diffusion coefficient, and the deterministic and probabilistic analysis for service life were performed by assuming the design variable as a probability function. For probabilistic service life analysis, durability failure probabilities were calculated using Monte Carlo Simulation (MCS) to evaluate service life. The service life of probabilistic method were lower than that of deterministic method, since the target value of PDF (Probability of Durability Failure) was set very low at 10 %. If the target value of PDF suitable for the purpose of using structure can be set and proper variability can be considered for each design variable, it is believed that more economical durability design can be made.