• Journal of the Korean Ceramic Society
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• v.54 no.2
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• pp.150-157
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• 2017

Three types of piezoelectric single crystals [PMN-PT (Generation I $[Pb(Mg_{1/3}Nb_{2/3})O_3-PbTiO_3]$), PMN-PZT (Generation II $[Pb(Mg_{1/3}Nb_{2/3})O_3-Pb(Zr,Ti)O_3]$), PMN-PZT-Mn (Generation III)] were grown by the solid-state single crystal growth (SSCG) method, and their dielectric and piezoelectric properties were measured and compared. Compared to (001) PMN-PT and PMN-PZT single crystals, the (001) PMN-PZT-Mn single crystals exhibited a higher transition temperature between the rhombohedral and tetragonal phases ($T_{RT}=144^{\circ}C$), as well as a higher coercive electric field ($E_C=6.3kV/cm$) and internal bias field ($E_I=1.6kV/cm$). The (011) PMN-PZT-Mn single crystals showed the highest coercive electric field ($E_C=7.0kV/cm$), and the highest stability of $E_C$ and $E_I$ during 60 cycles of polarization measurement. These results demonstrate that both Mn doping (for higher electromechanical quality factor ($Q_m$)) and a (011) crystallographic orientation (for higher coercive electric field and stability) are necessary for high power transducer applications of these piezoelectric single crystals. Specifically, the (011) PMN-PZT-Mn single crystal (Gen. III) had the highest potential for application in the fields of SONAR transducers, high intensity focused ultrasound (HIFU), ultrasonic motors, and others.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.11
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• pp.495-501
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• 2006

Diagnostics of unborn baby is mainly aimed at prediction and detection of occurrence of intrauterine hypoxia. Consequences resulting from fetal hypoxia appear in its heart activity. In this study, we have developed a new non-invasive system for fetal hypoxia diagnosis which provides systolic time interval(STI) parameters on the basis of analysis of electrical and mechanical heart activity together. For this we have worked on 1) the proper lead system for the acquisition of abdominal ECG, 2) the independent component analysis based signal processing and fetal ECG separation, 3) the development of a hardware which consists of an abdominal ECG amplifying module and an ultrasound module and 4) the detection of characteristic points of FECG and Doppler signal and the extraction of diagnostic parameters. The developed system was evaluated by the clinical experiments in which 33 subjects were participated. The acquired STI by the system were distributed within the ranges from the well-established invasive results of other researchers. From this, we can conclude that the developed non-invasive fetal hypoxia diagnosis system is useful.

• Journal of Korean Medicine Rehabilitation
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• v.32 no.1
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• pp.145-155
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• 2022

The purpose of this study is to evaluate the effectiveness of traditional Korean medicine treatment of cervical vertigo. Three patients were diagnosed as cervical vertigo with correlating symptoms of imbalance and dizziness with neck pain. The diagnosis of cervical vertigo is also dependent on excluding other vestibular disorders on the basis of history, examination, and vestibular function tests. They were treated by acupuncture, transcutaneous electrical nerve stimulation therapy and low-intensity pulsed ultrasound at acupoints and sympathetic ganglion chain of their cervical and upper thoracic region. The evaluation of clinical outcome was done by numeric rating scale (NRS), dizziness handicap inventory (DHI) and neck disability index (NDI), EuroQol-five dimensions questionnaire (EQ-5D) index. After the treatment, the value of their NRS, NDI, DHI was significantly decreased and their EQ-5D index was significantly increased. The traditional Korean medicine treatment at cervical and upper thoracic region could be an effective way to treat cervical vertigo.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.1
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• pp.117-126
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• 2006

The purpose of this study is to develop a badge-type passive sampler for the measurement of short-term nitrogen dioxide and to evaluate its performance. The principle of the method is a colorimetric reaction of nitrogen dioxide with sulfanilic acid, N-1-naphthylethylendiamine, and phosphoric acid. First, it has been shown that the filter paper should be rinsed with ultrapure water and ultrasound, and then dried in a vacuumed desiccator. The concentration and volume of absorption reagent (triethanolamine) were $20\%$ and 100 ${\mu}L$, respectively. The extraction time was determined as 60 min. Second, duplicate measurements (n= 116) were carried out for evaluating the precision of the passive sampler. The relative error and the correlation coefficient between duplicates are $3.4\pm 3.0\%$ and 0.994, respectively. In addition, the $95\%$ confidence interval of intraclass correlation coefficient and the estimated value are 0.992$\sim$0.996 and 0.994, respectively. Third, a paired t-test was carried out for evaluating the accuracy of the passive sampler (n=40). In the result of the test, the $95\%$ confidence interval of the difference was -1.710 ppb <$\gamma$< 0.788 ppb. Finally, the average concentration of blanks, measurement detection limit, limit of detection, and limit of quantification are $2.4\pm 0.4$ ppb, 104 ppb, 3.8 ppb, and 7.0 ppb, respectively.

• Journal of Sensor Science and Technology
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• v.26 no.1
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• pp.66-72
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• 2017

The three dimensional ultrasonic anemometer was constructed to reduce the disadvantages of the two-dimensional anemometer and to be free from the use environment. Three pairs of transmitting and receiving ultrasonic sensors were designed to face each other at an angle of $45^{\circ}$ to the upper and lower surfaces at intervals of $120^{\circ}$. 200 kHz ultrasonic sensor Oscillation, transmission and reception, level detection, power supply circuit were designed and U, V, W wind speed vector components were obtained by measuring the time of first received ultrasonic pulse by transmitting pulse ultrasound. It is implemented as firmware in ARM Coretex-M3 processor so that horizontal and vertical wind direction and wind speed can be converted into digital signal by vector calculation. In this study, The three-dimensional ultrasonic anemometer can complement the disadvantages of the two-dimensional anemometer (mechanical and ultrasonic), and it is expected to gradually replace the two-dimensional anemometer due to its high utilization rate by collecting additional information such as vertical wind.

• Asian-Australasian Journal of Animal Sciences
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• v.33 no.8
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• pp.1284-1291
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• 2020

Objective: To evaluate the effects of the carmine cochineal-resistant spineless cactus genotypes cv. Orelha de Elefante Mexicana (Opuntia) and Miúda (Nopalea) on the intake and digestibility of nutrients, ingestive behavior, performance, and ultrasound measurements of growing lambs. Methods: Thirty-six male (non-castrated) Santa Inês lambs were used, with an average age of 6 months and an initial average weight of 22.0±2.9 kg. They were distributed in a completely randomized design with 3 treatments (Tifton hay, Nopalea and Opuntia) and 12 replications, using initial weight as a covariate. The experimental period was 86 days, with the first 30 days used for the adaptation of the animals to the facilities, diets and management, and the remaining 56 days used for evaluation and data collection. Results: The intake and apparent digestibility of dry matter (DM), organic matter (OM), crude protein (CP), neutral detergent fiber (NDF), total carbohydrates (TC), non-fibrous carbohydrates (NFC), and total digestible nutrients (TDN) showed a significant difference (p<0.05) as a function of the diets, with the Nopalea treatment (p<0.05) increasing DM intake (g/kg and % body weight [BW]), CP, TDN, and TC digestibility, whereas the Tifton hay diet led to a high (p<0.001) neutral detergent fiber corrected for ash and protein (NDFap) g/d intake, NDFap (BW %) and digestibility of said nutrient. There was no effect of treatments (p>0.05) on feeding time, however, rumination time and total chewing time were higher (p<0.05) for animals fed Tifton hay. The performance of the animals was similar (p>0.05). For the ultrasound measurements, Nopalea promoted an increase in the final loin eye area, compared to Tifton hay. Conclusion: The use of spineless cactus variety Miúda leads to the greater intake and digestibility of nutrients. The evaluated carmine cochineal-resistant spineless cactus genotypes are alternatives for semi-arid regions as they do not negatively affect the performance of growing lambs.

• Journal of the Korean Society of Radiology
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• v.13 no.6
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• pp.857-864
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• 2019

Many countries, including Canada, operate a sonographer license system separately from a radiological technologist license. However, in Korea, radiological technologists perform ultrasound imaging under the guidance of doctors. Therefore, in order to have the opportunity to provide a systematic education by analyzing the job competency of the radiological technologist's ultrasound imaging, based on the Canadian National Competency Profile (NCP) lists, this study measured the job content validity of the job competences and detailed competencies required for performing ultrasonography in Korea. From the results of comparing and analyzing the importance of the core competencies included in the Korean radiological technologist's job competencies and the degree of job performance, the average overall importance was 4.087, the average of overall performance was 3.640, showing that the importance was higher than the performance and that there was a statistically significant difference. In conclusion, 'A Communication', 'B Professional responsibilities', 'D Operation of equipment' and 'G Workplace health and safety' showed high job content validity. However, it is said that as 'C Patient assessment and care', 'E Critical thinking and problem solving', and 'H Image' showed low job content validity, it is necessary to seek ways to strengthen and complement these competencies.

• Korean Chemical Engineering Research
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• v.40 no.6
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• pp.669-675
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• 2002

The alkenylation of o-xylene with 1,3-butadiene to make OTP(ortho-tolyl Pentene) was carried out over liquid phase NaK alloy, Na metal and the metallic sodium dispersed on the specific support such as NaX and $Al_2O_3$. Liquid phase NaK alloy showed the improved conversion and selectivity when they were pretreated by ultrasound to increase the dispersion. For the case of metallic sodium, the induction period for the formation of homogeneous metal sodium solution with high dispersion was needed before the reaction. In the case of metallic sodium dispersed on support, more than 80 % conversion could be obtained without induction period regardless of supports used. But 85 % of the metallic sodium was resolved into the reaction mixture after reaction for 7 hours. The amount of byproducts, oligomers, produced from OTP and 1,3-butadiene increased with the amount of 1,3-butadiene introduced and the selectivity to OTP was in inversely proportional to the conversion.

• Bulletin of the Korean Chemical Society
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• v.27 no.5
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• pp.637-641
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• 2006

Although chiral separation has been one of the main topics of chromatographic practice for over twenty-five years, it still presents many difficulties. In this work, the ultrasonic dependence of chiral resolution was investigated at various temperatures to improve resolution and reduce analysis time. The chiral resolution was performed on recently commercialized two HPLC chiral stationary phases (CSP 1 and CSP 2) with the analogues of racemic N-acylnaphthylethylamines (1a-d) and racemic amino acid derivatives (2a-c, 3a-c) as analytes. The CSP 1 was prepared from a (R)-N-(3,5-dinitrobenzoyl)phenylglycinol and the CSP 2 was prepared from a (S)-N-3,5-(dinitrobenzoyl) leucine. From the comparison of the chromatographic results under sonic condition with those under non-sonic condition, we found that the ultrasound decreased the elution time in chiral chromatography at all temperatures and improved the enantioselectivity at high temperature (45, 50, 60 ${^{\circ}C}$).

• Korean Journal of Veterinary Research
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• v.37 no.4
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• pp.917-924
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• 1997

Estrus cycle of cow, season and follicldar stimulating treatment, having an effect on the number of follicle, are investigated for the oocyte recovery rate in ovum pick-up(OPU). The number of follicle aspirated and oocyte collected on the different days of estrus cycle(D 4~5, D 9~10 and D 14~15) were not significantly different among the groups. The higher number of viable oocytes were produced on Jan-May(79.0%) than Jun-Aug(33.3%) by OPU in cow. The number of follicle and aspirated oocyte in cows treated FSH or PMSG combined with bovine somatotropin(bST) were 1.2~1.5 times higher than in cows treated alone follicular stimulating hormone(FSH) or pregnant mare serum gonadotropin(PMSG). In conclusion, OPU can be repeatedly practiced 2 or 3 times in an estrus cycle. In addition, the high environmental temperature is not good for ovarian function of cow and the bST co-treatment with FSH or PMSG is increasing the number of aspiratable follicle.