• Membrane Journal
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• v.29 no.4
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• pp.223-230
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• 2019

In this paper, we develop a polymeric blend membrane based on $CO_2$-philic poly(2-[3-(2H-benzotriazol-2-yl)-4-hydroxyphenyl] ethyl methacrylate)-poly(oxyethylene methacrylate) (PBEM-POEM) comb copolymer, which was synthesized by facile free radical polymerization. The PBEM-POEM (PBE) comb copolymer was blended with a commercial oligomer, low-molecular-weight poly(ethylene glycol) (PEG, $M_w=200gmol^{-1}$) with various ratios to prepare $CO_2/N_2$ separation membranes. From the result of $CO_2/N_2$ separation test of the PBE/PEG blend membranes with the various PEG contents, we could conclude that with increasing PEG content, the $CO_2/N_2$ selectivity significantly increased while the CO2 permeability decreased showing trade-off relationship. However, when comparing the performance of the PBE/PEG (9 : 1) with the PBE/PEG (7 : 3) membrane, the $CO_2$ permeance decreased by only 8.3%, while the $N_2$ permeance decreased by 69.1%. Therefore, the $CO_2/N_2$ selectivity dramatically increased from 33.8 to 100.3. This could be because the POEM chains, which account for 80% of the PBE copolymer, favorably interact with PEG and lead to a more compact chain structure, which was confirmed by FT-IR, XRD and SEM analysis. The PBE/PEG (7 : 3) blend membrane had the most optimal gas separation performance, showing a $CO_2$ permeance of 170.5 GPU and $CO_2/N_2$ selectivity of 100.3.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.848-854
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• 2011

The objective of this research was to experimentally test the effect of rice straw mats on the reduction of runoff, sediment and discharge under a laboratory scale with different rainfall intensity and slopes. We used the small runoff plots of $1m{\times}1m{\times}0.65m$ ($L{\times}W{\times}H$) in size were filled with loamy sand. Experimental treatments were bare (control), rice straw mats + PAM(SP), rice straw mats + PAM + sawdust(SPS) and rice straw mats + PAM + rice husks(SPR); slope of 10% or 20%; and rainfall intensity of 30 or 60 mm/hr. Runoff volume and coefficient from covered plots were significantly lower than those from control plots. Under the 30 mm/hr and 10% simulations, average runoff coefficient of covered plots decreased more than 92%. Under 60 mm/hr and 20% simulations, the ratios were between 39.8~58.1%. Under the condition of 30 mm/hr rainfall and 10% slope, sediment discharge from covered plots was practically zero. And at 20% plots, sediment reduction ratio was more than 95%. Under the condition of 60 mm/hr rainfall, sediment reduction ratio of 10 and 20% plots ranged between 86.3~95.3% and between 79.8~86.5%, respectively. The differences in initial runoff time, runoff and sediment discharge among different cover materials were not significant. Rainfall intensity showed higher impact on initial runoff time, runoff, and sediment discharge than slope. It was also shown that even if runoff reduction by surface cover were low, sediment discharge reduction could be very significant and contribute to improve the water quality of streams in sloping agricultural regions. It was concluded that the use of straw mat and PAM on sloping agricultural fields could reduce soil erosion and muddy runoff significantly and help improve the water quality and aquatic ecosystem in receiving waters.

• Korean Journal of Metals and Materials
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• v.46 no.6
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• pp.351-356
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• 2008

Thermally sprayed tungsten carbide-based powder coatings are being widely used for a variety of wear resistance applications. The coating deposited by high velocity processes such as high velocity oxy-fuel (HVOF) thermal spraying is known to provide improved wear resistant property. In this study, optimal coating process (OCP) is obtained by the study of coating properties such as surface hardness, porosity, surface roughness and microstructure of 9 coatings prepared by Taguchi program for 3 levels of four spray parameters. The Friction and wear behaviors of HVOF WC-CoCr coating prepared by OCP, electrolytic hard chrome (EHC) plating and Inconel718 (In718) are investigated by reciprocating sliding wear test at $25^{\circ}C$, $450^{\circ}C$. Friction coefficients (FC) of all of the 3 samples are decreased as increasing sliding surface temperature from $25^{\circ}C$ to $450^{\circ}C$. FC of WC-CoCr decreases as increasing the surface temperature from $0.33{\pm}0.02$ at $25^{\circ}C$ to $0.26{\pm}0.02$ at $450^{\circ}C$, showing the lowest FC among the 3 samples. Wear trace (WT) and wear depth (WD) of WC-CoCr are smaller than those of EHC and In718 both at $25^{\circ}C$ and $450^{\circ}C$. These show that WC-CoCr is highly recommendable for protective coating on In718 and other metal components.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.4
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• pp.553-561
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• 2020

Water-soluble rubber asphalt-based waterproofing material, which is one of the waterproofing materials for building structures, is mainly used indoors (toilet, kitchen, balcony, etc.). In general, asphalt-based materials are used for non-exposed installation, rather than as exposed type as they do not deviate from their usual basic black pigmentation, and water-soluble rubber asphalt-based coating waterproofing materials are basically limited to indoors because of their low physical properties. Accordingly, in order to improve the tensile and elongation properties, a silane coupling agent, an inorganic filler, and a processor oil w ere added to improve the physical properties, and accordingly, the basic physical properties of the outdoor coating waterproofing material quality standard were analyzed. As a result, the water-soluble rubber asphalt coating waterproofing material compared with the exposure quality standard showed a result that exceeded the basic physical property quality standard of silicone rubber in all items under test evaluation, but the tensile strength and tear strength of the first class of urethane rubber were chloroprene. It was found that the performance compared to the quality standards of rubber-based tear strength was about 34.2% to about 40.8%.

• Journal of muscle and joint health
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• v.16 no.2
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• pp.174-183
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• 2009

Purpose: The purposes of this study were to develop and examine the self-help and Tai Chi program for arthritis, and to identify the effect when combined with a supportive follow up phone-calls. Method: The design for this study was a 3*2 quasi-experimental design. Sixty-six participants were recruited in W-city, and assigned to Exp 1 group (n=21) or Exp 2 group (n=24) according to supportive follow-up phone call method, or to the control group (n=21). Fifty-two subjects (17 and 20 in Exp 1 and 2, and 15 in the control group) completed pretest and posttest. Both experimental groups participated in the self-help and Tai Chi program for arthritis once a week for 8 weeks. Exp 1 received automated follow up phone-calls made up in KT-SHUT program, and Exp 2 received follow up phone-calls made up by researchers. The control group received no education and no phone call. Measures used to examine the effect self-help and Tai Chi program for arthritis were joint flexibility, hand muscle strength, balance with closed eyes and self-efficacy. The final analysis of the post-test measures was conducted by ANCOVA with age and self efficacy as covariates. Results: Both experimental group had significantly increased right shoulder flexibility (p=.002), left shoulder flexibility (p=.000), right hand grip (p=.024), and self efficacy (p=.008) compared with the control group. But there were no significant differences between two experimental groups in any physical indicators and self efficacy. Conclusion: Automated follow up phone-call would be helpful in managing the self-help and Tai Chi program for arthritis as well as researcher's phone call. The automated follow up phone-call program which was a new method could be recommended for use to encourage home exercise practice and the program participation.

• Journal of the Korean Society of Food Culture
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• v.22 no.2
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• pp.266-273
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• 2007

This study was conducted to examine the antimicrobial activity of Perilla frutescens var. acuta leaf fractions extracted with a mixture of ethanol and water. The Ca and Mg contents of the leaf were 595.75 mg% and 467.0 mg%, respectively, and they were the highest among all of the test minerals. The extract yield increased w e content of water in e extraction solvent. Antimicrobial activity against Staphylococcus aureus, Bacillus subtilis and Pseudomonas aeruginosa was found in the 50,70 and 95% ethanol extracts. Of the various fractions extracted from the mixture of ethanol and water, the ethyl acetate fraction showed antibacterial activity against all microorganisms tested in this experiment, and the antibacterial activity of ethyl acetate fraction from the water extract was the strongest. The phenol and flavonoid content in the ethyl acetate fraction showed no correlation with the concentration of ethanol in the extract solvent; however, their contents were higher in the 30% ethanol and water extraction which the antimicrobial activity of the extract was the strongest.

• Korean Journal of Culture and Social Issue
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• v.14 no.1_spc
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• pp.391-407
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• 2008

In order to observe from a cross-cultural point of view, the temperament and character of German and Korean adolescents were compared. The 715 German subjects aged 12-18(M=14.70, SD=1.80) and 1411 Korean subjects of the same age(M=15.18, SD=1.69) were assessed through JTCI 12-18 as to whether there exist differences in temperament and character between the two groups. According to the outcomes of the t-test, the German and Korean adolescents show significant differences in all 6 main scales of temperament and character, with only one exception in the character scale, that of 'self-transcendence.' If we analyze the effect size, because even small differences in great samples becomes statistically significant differences, the significant outcomes appeared only in two scales, one of temperament(Harm Avoidance) and the other of character(Self-Directedness): Korean subjects showed a higher tendency of Harm Avoidance related to inhibitions and anxiety and a lower tendency of Self-Directedness, meaning self-acceptance, purposefulness etc. Sex-differences according to the effect size showed only on the scale of Reward Dependence, which was the same in both samples. The outcomes are discussed according to the concepts of individualism and collectivism which are used to divide the Western and Asian cultures. It is also suggested to view these outcomes in the education-political and social bases of each country.

• Journal of the Korea institute for structural maintenance and inspection
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• v.27 no.5
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• pp.97-104
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• 2023

The aim of this study was to produce polymer cement composites (PCCs) composed of polymer dispersion and cement as crack repair materials for RC structures, and to investigate their fundamental properties. The test mixtures for the study were based on EVA and SAE polymer dispersions, and the water-cement ratio was determined while varying the polymer-cement ratio(P/C) in four different levels (20%, 60%, 80%, and 100%) to achieve the desired viscosity of PCCs considering their fillability as crack repair materials. Additionally, silica fume was incorporated into P/C 80% and 100% specimens to enhance their stiffness. The basic properties of PCCs as crack repair materials, such as viscosity, flowability, fillability, tensile strength, elongation, and modulus of elasticity, were examined. The results showed that P/C depending on the type of polymer significantly affected the viscosity and flowability, and appropriate w/c ratios were needed to achieve the desired viscosity for the mixture design with consideration of fillability as crack repair materials for RC structures. All designed mixtures in this study exhibited excellent fillability. The tensile strength and elongation of PCCs satisfied the KS regulation for cement- polymer modified waterproofing coatings. The incorporation of silica fume improved the tensile strength and modulus of elasticity of PCCs. Depending on the type of polymer, mixtures using SAE showed better fundamental properties as crack repair materials for RC structures compared to those using EVA. In conclusion, SAE-based P/C 80% or 100% with the addition of up to 30% silica fume can be recommended as suitable mixtures for crack repair of RC structures.

• Journal of Cardiovascular Imaging
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• v.30 no.4
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• pp.263-275
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• 2022

BACKGROUND: Cardiac allograft vasculopathy (CAV) is a complication beyond the first-year post-heart transplantation (HTx). We aimed to test the utility of cardiac magnetic resonance (CMR) to detect functional/structural changes in HTx recipients with CAV. METHODS: Seventy-seven prospectively recruited HTx recipients beyond the first-year post-HTx and 18 healthy controls underwent CMR, including cine imaging of ventricular function and T1- and T2-mapping to assess myocardial tissue changes. Data analysis included quantification of global cardiac function and regional T2, T1 and extracellular volume based on the 16-segment model. International Society for Heart and Lung Transplantation criteria was used to adjudicate CAV grade (0-3) based on coronary angiography. RESULTS: The majority of HTx recipients (73%) presented with CAV (1: n = 42, 2/3: n = 14, 0: n = 21). Global and segmental T2 (49.5 ± 3.4 ms vs 50.6 ± 3.4 ms, p < 0.001;16/16 segments) were significantly elevated in CAV-0 compared to controls. When comparing CAV-2/3 to CAV-1, global and segmental T2 were significantly increased (53.6 ± 3.2 ms vs. 50.6 ± 2.9 ms, p < 0.001; 16/16 segments) and left ventricular ejection fraction was significantly decreased (54 ± 9% vs. 59 ± 9%, p < 0.05). No global, structural, or functional differences were seen between CAV-0 and CAV-1. CONCLUSIONS: Transplanted hearts display functional and structural alteration compared to native hearts, even in those without evidence of macrovasculopathy (CAV-0). In addition, CMR tissue parameters were sensitive to changes in CAV-1 vs. 2/3 (mild vs. moderate/severe). Further studies are warranted to evaluate the diagnostic value of CMR for the detection and classification of CAV.

• Hip & pelvis
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• v.34 no.1
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• pp.25-34
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• 2022

Purpose: Mortality rates following hip fracture surgery have been well-studied. This study was conducted to examine mortality rates in asymptomatic patients presenting for treatment of acute hip fractures with concurrent positive COVID-19(+) tests compared to those with negative COVID-19(-) tests. Materials and Methods: A total of 149 consecutive patients undergoing hip fracture surgery during the COVID-19 pandemic at two academic medical centers were reviewed retrospectively. Patients were divided into two groups for comparative analysis: one group included asymptomatic patients with COVID-19+ tests versus COVID-19- tests. The primary outcome was mortality at 30-days and 90-days. Results: COVID-19+ patients had a higher mortality rate than COVID-19- patients at 30-days (26.7% vs 6.0%, P=0.005) and 90-days (41.7% vs 17.2%, P=0.046) and trended towards an increased length of hospital stay (10.1±6.2 vs 6.8±3.8 days, P=0.06). COVID-19+ patients had more pre-existing respiratory disease (46.7% vs 11.2%, P=0.0002). Results of a Cox regression analysis showed an increased risk of mortality at 30-days and 90-days from COVID-19+ status alone without an increased risk of death in patients with pre-existing chronic respiratory disease. Conclusion: Factors including time to surgery, age, preexisting comorbidities, and postoperative ambulatory status have been proven to affect mortality and complications in hip fracture patients; however, a positive COVID-19 test result adds another variable to this process. Implementation of protocols that will promote prompt orthogeriatric assessments, expedite patient transfer, limit operating room traffic, and optimize anesthesia time can preserve the standard of care in this unique patient population.