• Elastomers and Composites
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• 제54권3호
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• pp.225-231
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• 2019

Bio-based polyester polyol was synthesized via esterification between azelaic acid and isosorbide. After esterification, bio-based polyurethanes were synthesized using polyester polyol, 1,3-propanediol as the chain extender, and 4,4'-diphenylmethane diisocyanate, in mixing ratios of 1:1:1.5, 1:1:1.8, 1:1:2, and 1:1:2.3. The bio TPU (Thermoplastic Polyurethane) samples were characterized by using FT-IR (Fourier Transform Infrared Spectroscopy), TGA (Thermal Gravimetric Analysis), DSC (Differential Scanning Calorimetry), and GPC (Gel Permeation Chromatography). The mechanical properties (tensile stress and hardness) were obtained by using UTM, a Shore A tester, and a Taber abrasion tester. The viscoelastic properties were tested by an Rubber Processing Analyzer in dynamic strain sweep and dynamic frequency test modes. The chemical resistance was tested with methanol by using the swelling test method. Based on these results, the bio TPU synthesized with the ratio of 1:1:2.3, referred to as TPU 4, showed the highest thermal decomposition temperature, the largest molecular weight, and most compact matrix structure due to the highest ratio of the hard segment in the molecular structure. It also presented the highest tensile strength, the largest elongation, and the best viscoelastic properties among the different bio TPUs synthesized herein.

• 한국기계가공학회지
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• 제21권9호
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• pp.1-11
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• 2022

Recently, there has been continuous technological development in the semiconductor industry, and semiconductor manufacturing technologies are being advanced and highly integrated. For this reason, ceramic material having excellent heat resistance, wear resistance, and conductivity are used as components in semiconductor manufacturing. Among them, the probe card's space transformer is used as ceramic material to prevent electronic signal noise during the electrical die sorting of semiconductor function testing. However, implementing a bulk-type space transformer with a thickness of 5.6 mm or more is challenging, and thus it is produced in a structure with a stacked ceramic film. The stacked space transformer has low productivity because it is difficult to ensure hole clogging and a precise shape. In this research, an ultrasonic horn is designed to manufacture a bulk-type ceramic space transformer through ultrasonic drilling. Vibration characteristics were analyzed according to the ultrasonic horn, and the natural frequency was measured.

• 대한의용생체공학회:의공학회지
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• 제26권2호
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• pp.111-116
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• 2005

This study was designed to apply the stimulation system developed in our laboratory to investigate how the stimulation conditions affect the muscle contractile characteristics in the isometric condition as well as during the FES standing/walking. Four paraplegic and ten healthy subjects participated in this study, and their knee extensors were voluntary contracted or electrically stimulated to measure the muscle force and the fatigue index for different waveforms of the pulse train. We also investigated different combinations of the electrode positions during standing/walking. It was confirmed that continuous and high-frequency stimulation causes faster fatigue than intermittent and low-frequency stimulation. Fatigue resistance was higher around the optimal muscle length than at a stretched position in healthy subjects, whereas the opposite was observed in paralyzed subjects. The paired t-test results with the level of significance at 0.01 indicated that the sinusoidal waveform generated the largest torque among the four typical waveforms. Although statistically not very significant, the sinusoidal waveform also generated, in general, the highest fatigue resistance at an intensity level below the supramaximal stimulation. One of the paraplegic subject who participated in the standing/walking program can now stand up for 1 minute and 50 seconds with the knee extensors, and walk for about 5 minutes at the speed of 12m/sec.

• 전기학회논문지
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• 제62권9호
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• pp.1308-1312
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• 2013

In this paper, carried out for optimal ground system for ensuring safety for electricity used to power equipment in the 20 kHz frequency. Now the grounding system of the mesh electrode, electrode rods are installed for power plant safety and protection against electric shock. However, the electrical equipment grounding system in the 20 kHz were considering the increasing grounding impedance due to the high frequency and the magnetic shielding. But until now, there has been little research on the grounding system. To solve this problem, In this paper was proposed optimal grounding system due to the experiment using a mesh electrode, rod electrode, aluminum plate electrodes. Measurement results, grounding resistance was depending on the material of the electrode grounding resistance. In addition, the leakage current (induced) appeared to be affected depending on the type of electrode.

• Journal of Microbiology and Biotechnology
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• 제25권7호
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• pp.1154-1162
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• 2015

The emergence of carbapenem resistance among Pseudomonas aeruginosa is an increasing problem in many parts of the world. In particular, metallo-$\beta$-lactamases (MBLs) and AmpC $\beta$lactamases are responsible for high-level resistance to carbapenem and cephalosporin. We studied the diversity and frequency of $\beta$-lactamases and characterized chromosomal AmpC $\beta$lactamase from carbapenem-resistant P. aeruginosa isolates. Sixty-one carbapenem-resistant P. aeruginosa isolates were collected from patients in a tertiary hospital in Daejeon, Korea, from January 2011 to June 2014. Minimum inhibitory concentrations (MICs) of four antimicrobial agents were determined using the agar-dilution method. Polymerase chain reaction and sequencing were used to identify the various $\beta$-lactamase genes, class 1 integrons, and chromosomally encoded and plasmid-mediated ampC genes. In addition, the epidemiological relationship was investigated by multilocus sequence typing. Among 61 carbapenem-resistant P. aeruginosa isolates, 25 isolates (41.0%) were MBL producers. Additionally, 30 isolates producing PDC (Pseudomonas-derived cephalosporinase)-2 were highly resistant to ceftazidime (MIC₅₀ = $256{\mu}g/ml$) and cefepime (MIC₅₀ = $256{\mu}g/ml$). Of all the PDC variants, 25 isolates harboring MBL genes showed high levels of cephalosporin and carbapenem resistance, whereas 36 isolates that did not harbor MBL genes revealed relatively low-level resistance (ceftazidime, p < 0.001; cefepime, p < 0.001; imipenem, p = 0.003; meropenem, p < 0.001). The coexistence of MBLs and AmpC $\beta$-lactamases suggests that these may be important contributing factors for cephalosporin and carbapenem resistance. Therefore, efficient detection and intervention to control drug resistance are necessary to prevent the emergence of P. aeruginosa possessing this combination of $\beta$-lactamases.

• 한국연초학회지
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• 제20권1호
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• pp.66-70
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• 1998

TMV resistant lines (TRLs) originated from the Blo plant of Nicotiana tabacum cv. NC82 transformed with TMV coat protein cDNA which initially showed delayed disease symptom were selected for increased resistance in each subsequent generation. The result of field experiment of the transgenic tobacco lines in the fifth generation for TMV resistance and their response to other tobacco diseases (black shank, bacterial wilt, and powdery mildew) is described in this report. When fifteen TRLs of the fifth generation were tested for TMV resistance by mechanically inoculating the individual plants, over 95 percent of the plants of 6 lines showed complete resistance even 8 weeks after the inoculation. Average frequency of the resistant plants in TRLs of the fifth generation 8 weeks after the inoculation was 87%. Stable insertion and expression of TMV coat protein cDNA in the fifth generation of the transgenic tobacco plant were confirmed by PCR and immunoblot hybridization, respectively. All TRLs were resistant to the black shank but were susceptible to the bacterial wilt disease and the powdery mildew to the same degree as non-transgenic NC82 was. Therefore, it was indicated that the phenotypes related at least to disease resistance were not changed in the transgenic tobacco. Key words : TMV CP cDNA, TMV resistant tobacco plant, transformation.

• 대한통합의학회지
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• 제9권3호
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• pp.145-153
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• 2021

Purpose : The purpose of this study was to compare and analyze whether there are changes in muscle elasticity when resistance using an elastic band is present or absent during a bridge exercise on an unstable surface with a gymball. Methods : Eighteen healthy adult college students attending E University in Gyeonggi-do, who voluntarily agreed to participate were included in this study. The subjects were instructed to perform the bridge exercise using a gymball both without resistance and with resistance using an elastic band. Myoton was used during the exercise to measure the elasticity of the rectus abdominis and biceps femoris muscles. Results : There was a significant difference in the stiffness of the rectus abdominis muscle on both sides before and after using the elastic band (p<.05). however, no significant difference was observed in the biceps femoris on either side (p>.05). Based on the evaluation of the frequency before and after using the elastic band, no significant difference was observed between the rectus abdominis and biceps femoris muscles on both sides (p>.05). The logarithmic decrement was significantly different in the right rectus abdominis muscle (p<.05), and there was no significant difference in the left rectus abdominis and both biceps femoris (p>.05). Conclusion : Resistance exercise using an elastic band is more effective in improving elasticity of the rectus abdominis muscle than without a elastic band during bridge exercise with a gymball.

• Tuberculosis and Respiratory Diseases
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• 제45권6호
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• pp.1123-1142
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• 1998

Background : The frequency of MOTT has risen as the prevalence of tuberculosis has been declining. Our country has been also. The most of MOTT was resistant to the major anti-tuberculous drugs. Method : To compare clinical characteristics and frequencies of MDR tuberculosis with MOTT, the author studied 65 patients showing AFB culture positive with sputum. The data were collected from 176 patients who had been admitted at the National Masan Tuberculosis Hospital from May to June, 1997 to April, 1998. Result : The frequency of MDR tuberculosis was 43.1% and that of MOTT was 9.2%. Among 65 isolated mycobacteria, 3 cases were M. intracellulare. 2 cases were M. fortuitum, and 1 case was unidentified MOTT. The most frequent age group in 65 culture positive patients was 4th decade and the mean age was 44. The mean age was 61 in MOTT and 42 in M. tuberculosis and had significant difference(p<0.01). The numbers with past history of treatment were 2.3 in MDR tuberculosis and 1.7 in non-MDR tuberculosis and had significant difference(p<0.05). At the time of admission, the most frequent regimen for the treatment of MDR tuberculosis was 24 months regimen(85.7%) with the 2nd line anti-tuberculosis drugs. For non-MDR tuberculosis, 9 or 12 months regimen (72.9%) with the 1st line anti-tuberculosis drugs and had significant difference (p<0.01). At the time of admission, the symptom of weight loss was shown in 84.7% of M. tuberculosis and 50.0% in MOTT and there was significant difference(p<0.05) between them. All of the MOTT were identified to be resistant against INH and PAS. Drug resistance rates to INH, OFX(p<0.01) and PAS(p<0.05) in MOTT were higher than in MDR. All of three M. intracellulare strains were resistant to INH, RFP, PAS and OFX. All of two M. fortuitum strains were resistant to most anti-tuberculosis drugs. And the other MOTT was resistant to INH, EMB and PAS. Conclusion : MOTT was more common in elderly patients than M. tuberculosis. MOTT cases should be considered to be the probability of multiple drug resistance and treatment failure during the 1st treatment because they showed more resistance to anti-tuberculosis drugs than M. tuberculosis cases. Therefore, there should be more careful investigations for clinical characteristics, natural history of disease, and efficient management for MOTT.

• 대한수의학회지
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• 제29권3호
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• pp.303-313
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• 1989

To investigate the epidemiological trait of intestinal diseases of animals caused by thermophilic Campyllobacter spp., isolation of etiological agent was carried out and the profiles of plasmids and the transfer of resistance plasmid in the isolated Campylobacter spp. were examined. The results were as follows. 1. A total of 110 isolates of C jejuni and C coli were subjected to the test for the presence of plasmid DNA. Of the isolates examined, 60% of the isolates were noted to harbor plasmid DNA. Plasmid occurrencer ate from pigs, chickens and cattle were 76.2%, 61.7% and 37.7%, respectively. The plasmids of a large molecular weight, ranging from 36 Md to 86Md, were identified with the strains of tetracycline resistant. 2. Transfer frequency of tetracycline resistant plasmids was higher in the case of the filter mating method than in the broth mating method by the factor of 10~1,000. 3. Tetracycline resistant plasmids of C jejuni were transferrable to C jejuni and C coli by conjugation. In a low frequency, the transfer of tetracycline plasmid was also possible to Vibrio parahemolyticus. However, it was impossible to transfer to Streptococcus fecalis, E coli and Vibrio cholerae. 4. Tetracycline resistant plasmids of C jejuni were impossible to transfer to Campylobacter spp. and related bacteria by transformation.

• 한국멀티미디어학회논문지
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• 제20권10호
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• pp.1678-1688
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• 2017

Infiltration is one of detrimental problems occurring in nursing or medical settings. Early detection of infiltration is essential to minimize the risk of injury from infiltration. To perform a preliminary study on the point of care and automated infiltration detection system, bioelectrical impedance was investigated using bioelectrical impedance analyzer. We would like to report experimental results that allow impedance parameters to effectively distinguish infiltration. Electrodes were attached to both sides of the transparent dressing on the fusion site where IV solution was being infused. Then, impedance parameters before and after infiltration were measured as a function of time and frequency. The experimental results are as follows. After infiltration was intentionally induced by puncturing the vein wall with a needle, the resistance gradually decreased with time. That is, when an alternating current having a frequency of 20 kHz was applied to the electrodes, the resistance gradually decreased with time, reflecting the accumulation of IV solution in the extracellular fluid since the current could not pass through the cell membrane. Impedance parameters and equivalent circuit model for human cell were used to examine the mechanism of current flow before and after infiltration, which could be used for early detection of infiltration.