• Applied Chemistry for Engineering
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• v.32 no.3
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• pp.268-276
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• 2021

As wireless communication devices become more common, interests in how to control the electromagnetic waves generated from the devices are increasing. One of the most commonly used electromagnetic wave control materials is magnetic one, but due to the features that make the product heavy and thick when applied to the product, it is difficult to use them in curved electronic devices. Therefore, a polymer flexible meta electronic device has been presented to sort out the problem, which is thin and can have various curvatures. However, it requires an additional evaluation of curvature reliability. In this study, we developed a method to predict electromagnetic wave control characteristics through the resistance/length of the conductive ink line patterns of polymer flexible meta electronic devices, which is inversely proportional to the electromagnetic wave control characteristics. As the radius of curvature decreased, the resistance/length increased, and there was little variations with the duration times of curvature. We also found that both permanent and recoverable changes along with the removal of curvature were occurred when the curvature was applied, and that the cause of these changes was newly created vertical cracks in the conductive ink line pattern due to the tensile stress applied by applying curvature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.3
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• pp.390-398
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• 2020

To solve the problem of frequent component failure in guided weapons, a process of component failure in developed countries was investigated and analyzed. The suitability of component control, including risk assessment, analysis of operational impact, and the establishment of response measures, was also demonstrated. In addition, the economic effects of component control were presented by estimating the costs incurred if component control is performed in advance, after-sales, and non-management. DMSMS problems refer to losses or impending losses of an item, raw material, or software manufacturer or supplier. A problem with the discontinuation of parts occurs when the manufacturer or supplier ceases to produce and support the necessary parts, materials, or software, or when the supply of raw materials is no longer possible. Hence, it is important to recognize that failure to all parts of the system can occur.

• Journal of Gastric Cancer
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• v.8 no.4
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• pp.237-243
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• 2008

Purpose: Postoperative Infectious complications are recognized as major complications that are associated with surgery. Although many studies have focused on the risk factors of postoperative complications, little is known about the risk factors of infectious complications after gastric cancer surgery, and especially after elective gastrectomy. There is now more and more interest in the risk factors of infectious complications in relation to controlling infection and as indicators of qualitatively assessing infectious complications. The aim of this study was to evaluate the risk factors related with infectious complications after performing elective gastrectomy for treating gastric cancer. Materials and Methods: We retrospectively reviewed a total of 788 patients who had undergone elective gastrectomy for gastric cancer between Jan. 2000 and Dec. 2007. The characteristics of the patients were divided according to the patients' factors and the operations' factors. Results: The patients' mean age was 58.9 (range: 24~91) years; 545 were male and 243 were female. The mean duration of the hospital stay was 20.3 days (range: 5~135 days), the mean operation time was 181.3 minutes (range: 65~440 minutes). The total complication rate was 17.1% (n=135) and the complication rate was 38.5% (n=52) among the 135 patients with infectious complications. The infectious complications were surgical site infection (59.7%), Pneumonia (19.3%), intra-abdominal abscess (11.5%), pseudomembranous colitis (5.7%), bacteremia (1.9%) and hepatic abscess (1.9%). On the univariate analysis, the significant risk factors were male gender, blood transfusion, smoking at the time of diagnosis, alcohol drinking, diabetes mellitus and previous cardiovascular disease (P<0.05 for all). On multivariate analysis that used a logistic regression model, the significant independent risk factors were smoking at the time of diagnosis (OR: 2.877. 95% CI: 1.449~5.713), blood transfusion (OR: 3.440, 95% CI: 1.241~9.534), diabetes mellitus (OR: 3.150, 95% CI: 1.518~6.538), and previous cardiovascular disease (OR: 2.784, 95% CI: 1.4731~5.2539). Conclusion: Pre- or post-operative blood transfusion and the patient's medical history such as previous cardiovascular disease, diabetes mellitus, smoking etc. are the risk factors for infectious complications after undergoing elective gastrectomy for gastric cancer. The patients that have these risk factors need to be treated with great care to prevent infectious disease after elective gastrectomy.

• Food Science and Preservation
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• v.30 no.6
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• pp.1082-1094
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• 2023

The purpose of this study was to examine the characteristics of Leuconostoc spp. isolated from radish kimchi and to investigate the potential for the use of functional ingredients by evaluating enzymatic characteristics, safety, and immune-enhancing effects among the isolates, including Lactobacillus rhamnosus ATCC53103 (LGG) as a control strain. All test strains exhibited β-glucosidase enzyme activity that releases β-1,4 sugar chain bonds. In addition, as a result of antibiotic resistance assay among the isolates, MIC values on 8 antibiotics were below compared to the EFSA standard, and hemolytic experiments confirmed that all showed gamma hemolysis without hemolytic ability. As a result of the antibacterial activity experiment, the Leu. mesenteroides K2-4 strain showed a higher activity than LGG against Bacillus cereus and Staphylococcus aureus. Additionally, the activity of the NF-kB/AP-1 transcription factor increased when the isolates were treated in macrophage RAW cells. These results were related to increasing the high mRNA expression levels on TNF-α and IL-6 by Leu. mesenteroides K2-4 strain to be treated at low concentration. Consequently, we suggest that it will be useful as a candidate for functional food ingredients.

• Economic and Environmental Geology
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• v.51 no.5
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• pp.401-407
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• 2018

For the treatment of heavy metals in the mine drainage from the closed mine area, various methods such as passive, active and semi-active treatments are considered. Among contaminated elements in the mine drainage, Mn is one of the difficult elements for the treatment because it needs high pH over 9.0 for its concentration to be reduced. In this study, the efficiency of various slag complex reactors (slag (S), slag+limestone (SL) and slag+Mn coated gravel (SG)) on Mn removal in the presence of Fe, which is a competitive element with Mn, was evaluated to investigate effective methods for the treatment of Mn in mine drainage. As a result of experiments on Mn removal without Fe during 358 days, using influent with $30{\sim}50Mn{\cdot}mg/L$ and pH 6.7 on the average, S reactor showed continuously high Mn removal efficiency with the average of 99.9% with pH 8.9~11.4. Using the same reactors, Mn removal experiments with Fe during 237 days were conducted with the influent with $40{\sim}60Mn{\cdot}mg/L$. The pH range of effluent reached to 6.1~10.0, which is slightly lower than that of effluent without Fe. S reactor showed the highest range of pH with 7.1~9.9, followed by S+L and S+G reactor. However, the efficiency of Mn removal showed S+L>S>S+G with the range of 94~100%, 68~100% and 68~100%, respectively in spite of relatively low pH range. S+L reactor showed the most resistance on Fe input, which means other mechanisms such as $MnCO_3$ formation by the carbonate prouced from the limestone or autocatalysis reaction of Mn contributed to Mn removal rather than pH related mechanisms. The evidence of reactions between carbonates and Mn, rhodochrosite ($MnCO_3$), was found from the X-ray diffraction analysis of precipitates sample from S+L reactor. From this study, the most effective reactors on Mn removal in the presence of Fe was S+L reactor. The results are expected to be applied for the Mn containing mine water treatment in the presence of Fe within the relatively low range of pH.

• Korean Journal of Ecology and Environment
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• v.43 no.1
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• pp.35-43
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• 2010

Nutrient limitation and light limitation was examined for the Youngsan Lake by collecting chlorophyll $\alpha$ and other properties including light intensity, nutrient concentrations, pheopigment ratio monthly from March, 2003 to April, 2004 (except for November-January). Chlorophyll $\alpha$ was fractionated into net-(>$20\;{\mu}m$) and nano-size(<$20\;{\mu}$). Light and nutrient limitation index was calculated based on the equations incorporating the mechanisms of limitation of light and nutrients from the literature. Phytoplankton population (chlorophyll $\alpha$) was low during the wet season especially in August and increased in short-period during other seasons. Photoperiod was short during the wet season but long during the dry season. Nutrients such as phosphate and ammonium were rapidly increased in spring, 2004. Light limitation index was minimum (0.01) in August during the wet season and nutrient limitation index was relatively high (>0.4) except for May and September. Light limitation may affect phytoplankton growth rather than nutrient limitation considering that nutrient levels are high in the Youngsan Lake. Results of correlation analyses showed a negative correlation between light and nutrient limitation indices and net-pheopigment index, and a positive correlation between the indices and nano-pheopigment index. These results suggest that phytoplankton response to change of light and nutrient may be size-dependant.

• Polymer(Korea)
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• v.29 no.2
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• pp.135-139
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• 2005

In this study, poly(ethylene imine) (PEI) modified by methoxypoly(ethylene glycol) (mPEG) and folate as a gene carrier was synthesized to decrease cytotoxicity and to improve in vivo targeting. mPEG was modified by glutaric anhydride (GA) to endow carboxylic end group, followed by the activation reaction with EDC (N-ethyl-N'-(3-dimethyl-aminopropyl) carbodiimide) and NHS (N-hydroxysuccinimide). The activated carboxylic end group of mPEG was reacted with the amines of PEI to give mPEG graft PEI. The mPEG-folate-graft-PEI was synthesized by the reaction of mPEG-PEI with folate pre-activated by EDC/NHS. The obtained copolymers were characterized by $^1H-NMR$ and FT-IR. Gel retardation assay and fluorescence measurement indicated that DNA formed the complexes with the synthesized copolymers above N/P charge ratio 2. The size of complexes was ranging from 100 nm to 300 m. In conclusion, we confirmed that the synthesized copolymer have the possibility as a DNA carrier.

• Clean Technology
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• v.17 no.3
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• pp.215-224
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• 2011

It is an important issue to develop quality assessing system for biofuel for the purpose of accelerating the mass production of biofuel. It is particularly challenging to conduct testing method in the mass production of bioethanol while meeting quality specifications such as ASTM (American Society for Testing & Materials) D4806-10. In order to address this challenge, this paper proposes on-line spectroscopic quality assesment system based on Near Infrared spectrum and Partial Least Squares method in Chemometrics. As a result of testing a number of preprocessing methods and Partial Least Squares, it was found out that Savitzky-Golay method showed the best performance in terms of spectrum correction, noise reduction, and model maintenance. The proposed system allows us to assess multiple quality components continuously using spectroscopic facilities with the cheap cost. Since the value of R2 is more than 0.99, it is possible to replace the laboratory analysis.

• Weed & Turfgrass Science
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• v.4 no.4
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• pp.390-396
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• 2015

Water shortage is becoming a serious problem of turfgrass management on sand green. Many superintendents in golf course in Korea have interested in use of irrigation of recycled water for turfgrass water management. This study was conducted to investigate the effect of greywater as an irrigation source on the growth and quality of creeping bentgrass green. Turfgrass was irrigated with tap water (TW) and greywater (GW), under with or without compound fertilizer application (nonfertilizer + TW, N-TW; non-fertilizer + GW, N-GW; fertilizer + TW, F-TW; fertilizer + GW, F-GW). The chemical properties of the green sand soil were not changed by irrigation. Turf color index, chlorophyll index, root length, clipping yield and nutrient uptake of GW treatment were similar to TW treatment. The growth and quality of turfgrass were more likely related with the fertilizer application than irrigation source or quality. These results indicated that GW could be used as alternative irrigation source on the sand greens of golf courses.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.420-424
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• 2019

In SNG (synthetic natural gas) process by proposed RIST(Research Institute of Industrial Science & Technology)-IAE(Institute for Advanced Engineering) (including three adiabatic reactors and one isothermal reactor), the methanation reaction and water gas shift (WGS) reaction take place simultaneously, and the supply of steam with syngas might control the temperature in catalyst bed and deactivate the catalyst. In this study for development of SNG process, the characteristics of the methanation reaction with a Ni-based catalyst by prepared RIST and using a low $H_2/CO$ mole ratio (including $CO_2$ 22%) are evaluated. The operating conditions ($H_2O/CO$ ratio of the $1^{st}$ adiabatic reactor, operating temperature range of $4^{th}$ isothermal reactor, etc.) were reflected the results from previous studies and in the same condition a pilot scale SNG process is carried out. As a results, the pilot scale SNG process is stable and the CO conversion and $CH_4$ selectivity are 100% and 96.9%, respectively, while the maximum $CH_4$ productivity is $660ml/g_{cat}{\cdot}h$.