• The Journal of the Acoustical Society of Korea
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• v.36 no.4
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• pp.238-246
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• 2017

High frequency ultrasound imaging typically suffers from low sensitivity due to the small aperture of high frequency transducers and shallow imaging depth due to the frequency-dependent attenuation of ultrasound. These limitations should be overcome to obtain high-frequency, high- resolution ultrasound images. One practical solution to the problems is a high-performance signal receiver capable of detecting a very small signal and amplifying the signal with minimal electronic noise addition. This paper reports a recently developed low-noise, wideband ultrasound receiver for high-frequency, high-resolution ultrasound imaging. The developed receiver has an amplification gain of up to 73 dB and a variable amplification gain range of 48 dB over an operating frequency of 80 MHz. Also, it has an amplification gain flatness of ${\pm}1dB$. Due to these high performances, the developed receiver has a signal-to-noise ratio of at least 8.4 dB and a contrast-to-noise ratio of at least 3.7 dB higher than commercial receivers.

• Journal of radiological science and technology
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• v.43 no.4
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• pp.281-288
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• 2020

This study was intented as an investigation of the employment process into UAE for Korean and overseas sonographers to understand requirements for working abroad in regards to primary education curriculum and employment expansion abroad. A total of 10 candidates are selected who were working together with a job title of a cardiac sonographer in the same department under one hospital in Abu Dhabi, UAE. The candidates had clinical experience over 2 years in other countries after graduation and for 1 year at least in UAE. Data was collected through in-depth interviews, a web search and literature reviews. We analyzed the process regarding their curriculums studying in colleges, educational courses and certificates related medical fields. The findings were created with four essential themes: first, there are specific colleges or diploma courses corresponding academic major in United states, Portugal, Turkey, India and Pakistan. Secondly, healthcare professions were systemized by certifying as a specialist relevant medical fields. Thirdly, it is mandatory to be employed in UAE that are clinical experience for 2 years at least after graduation of specific courses. Lastly, It is required to work in UAE that is a license of healthcare authority under each state by taking a national examination or transferring own certificates to a current license in UAE. In conclusion, the results indicate that employing process for healthcare professionals depends on the educational requirements or clinical experience accumulated due to the various systems to be certified in each country. We believe that this study suggests experimental information for Korean job seekers considering working abroad in the medical ultrasound fields.

• Restorative Dentistry and Endodontics
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• v.39 no.1
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• pp.17-23
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• 2014

Objectives: This study evaluated the efficacy of Endosolv-R and Xylene in softening epoxy resin based sealer after 1 to 2 min exposure. Materials and Methods: Sixty Teflon molds ($6mm{\times}1.5mm$ in inner diameter and depth) were equally divided into 3 groups of 20 each. AH 26 (Dentsply/De Trey), AH Plus (Dentsply/De Trey), Adseal (Meta-Biomed) were manipulated and placed in the molds allotted to each group and allowed to set at $37^{\circ}C$ in 100% humidity for 2 wk. Each group was further divided into 2 subgroups according to the solvents used, i.e. Xylene (Lobachemie) and Endosolv-R (Septodont). Specimens in each subgroup were exposed to respective solvents for 1 and 2 min and the corresponding Vicker's microhardness (HV) was assessed. Data was analysed by Mauchly's test and two-way analysis of variance (ANOVA) with repeated measures, and one-way ANOVA. Results: Initial hardness was significantly different among the three sealers with AH Plus having the greatest and Adseal having the least. After 2 min, Xylene softened AH Plus and Adseal sealer to 11% and 25% of their initial microhardness, respectively (p < 0.001), whereas AH 26 was least affected, maintaining 89.4% of its initial microhardness. After 2 min, Endosolv-R softened AH 26, AH Plus and Adseal to 12.7, 5.6 and 8.1% of their initial microhardness, respectively (p < 0.001). Conclusions: Endosolv-R was a significantly more effective short term softener for all the tested sealers after 2 min whereas Xylene was an effective short term softener against AH plus and Adseal but less effective against AH 26.

• Journal of Periodontal and Implant Science
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• v.51 no.2
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• pp.77-87
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• 2021

Purpose: The aim of this study was to compare the efficacy of the tunnel technique for root coverage using a new xenogeneic acellular dermal matrix vs. connective tissue grafting (CTG) for the treatment of multiple maxillary adjacent recessions (recession type 1) at 12 months postoperatively. Methods: This study enrolled 12 patients with at least 3 contiguous, bilateral, symmetrical maxillary gingival recessions (i.e., at least 6 recessions per patient). In total, 74 recessions were treated using the modified coronally advanced tunnel (MCAT) technique combined with a novel porcine-derived acellular dermal matrix (PADM) at 37 test sites or CTG at 37 control sites. The following clinical parameters were measured: recession height, clinical attachment level, width of keratinized tissue, probing depth, recession width, gingival thickness, mean root coverage (MRC), and complete root coverage (CRC). Comparisons between test and control groups were made for pain visual analog scale scores at 14 days. Results: At 12 months, the MCAT with PADM (test) yielded a statistically significant improvement in all clinical parameters studied. MRC was significantly higher on the control sides (80.6%±23.7%) than on the test sides (68.8%±23.4%). Similarly, CRC was 48.7%±6.8% on the control sides (CTG), in contrast to 24.3%±8.2% on the test sides (PADM). Statistically significant differences were observed in favor of the control sides for all clinical parameters studied. Nevertheless, the MCAT in adjunction with PADM was clearly superior at reducing mean and maximum patient-reported postoperative pain intensity and pain duration in the first week after surgery. Conclusions: The use of PADM to treat multiple recessions improved clinical parameters at 12 months, but these outcomes were nevertheless poorer than those observed for CTG. However, PADM reduced morbidity, particularly the pain experienced by patients.

• Journal of the Korea Organic Resources Recycling Association
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• v.31 no.2
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• pp.19-38
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• 2023

Nitrous oxide, one of the six greenhouse gases from Kyoto protocol, is known to be emitted in biological nitrification and denitrification reactions at wastewater treatment plant. In this study, EQPS which is a computer program that can simulate nitrous oxide gas emission amount at wastewater treatment plants is used. The MLE process which treats wastewater from combined sewer is studied. Operational variables which are MLR, water temperature at reactor and primary clarifier by-pass percentage are changed to define the condition which produces the least amount of nitrous oxide gas. 200 % of MLR, 20 ℃ of water temperature at bioreactor and 15 % of primary clarifier by-pass percentage are shown the least nitrous oxide emission factor. Also, it is found that the deep aeration tank produces less amount of nitrous oxide gas since less air is required to meet oxygen demand in this type of aeration tank.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.5A
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• pp.477-486
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• 2009

This paper deals with the strongest static arches with the solid regular polygon cross-section. Both span length and volume of arch are always held constant regardless the shape functions of cross-sectional depth of regular polygon. The normal stresses acting on such arches are calculated when both static vertical and horizontal point loads are subjected. By using the calculating results of stresses, the optimal shapes of strongest static arches are obtained, under which the maximum normal stress become to be minimum. For determining the redundant of such indeterminate arches, the least work theorem is adopted. As the numerical results, the configurations, i.e. section ratios, of the strongest static arches are reported in tables and figures. The results of this study can be utilized in the field of the minimum weight design of the arch structures.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.13 no.9
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• pp.1955-1963
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• 2009

In the application of wireless sensor networks to monitor valuable assets under concern, the appearance of a certain asset can be identified and reported simultaneously by several adjacent nodes, and this may dissipate the power of related nodes and network bandwidth as well. In the proposed method, a node that senses the appearance of some asset is allowed to send the sensing-reporting packet only after it has been being idle for a certain period without receiving any DRP(Don't Report Packet) from neighbors. It turns out that not only the cost of propagating DRPs but also that of reporting the events to the sink becomes minimal when depth of each DRP propagation is 2. In case of depth 1, at least, two routes are set up for the delivery of the sensing-reporting packet hence, reliable transfer to the sink is provided.

• Journal of the Korean Dietetic Association
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• v.16 no.1
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• pp.1-12
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• 2010

This study was conducted to characterize well-being menus and to examine the service frequency and profitability of those served in the contract-managed workplace foodservice. In-depth interviews were conducted with six persons who were in charge of menu management in the headquarters of six different foodservice management companies during March, 2007. In addition, 122 set menus consisting of 777 menu items, which were on one month menus served during January to April, 2007, were collected from three workplace operations managed by three different foodservice management companies. As a result of the in-depth interviews, four categories of well-being menu items were extracted: 'medicinal functional menu item', 'environmentally-friendly menu item', 'natural food menu item', and 'harmful components-limiting menu item'. Accordingly, a well-being menu item was defined as 'a menu item with increased nutrition value or decreased health risk by changing food material or cooking method'. When the menu items (n=777) were analyzed by applying the definition and categories, approximately 14% of the items were identified as well-being menu items and most of them were either medicinal functional (65%) or natural food menu items (33%). Approximately 59% of the 122 set menus included at least one well-being menu item, and therefore they were named the well-being set menus. These well-being set menus, however, were not significantly different from the rest set menus in terms of profitability as measured by the contribution margin. The results of this study could be useful for foodservice management companies to develop and plan well-being menus targeting workplace foodservice operations.

• Journal of Global Scholars of Marketing Science
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• v.7
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• pp.303-320
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• 2001

The purpose of the study was to investigate the hedonistic motives experienced by consumers in the apparel buying process. We carried out in-depth interviews by 32 women living in Pusan and to examine the hedonistic motives related to the apparel buying process. It was conducted and analysed by the Spradley's developmental research method.The results showed that the hedonistic motives in apparel buying process, consisted of four components at least, such as Symbolism, Conformity, Distinction, and Impulsiveness. Symbolism represented the social-psychological aspects related to the apparel buying process, such as occupation, role, and self-image etc. Conformity in the apparel buying process was usually influenced by mass-media, and companions. Consumers had strong needs of distintion for self-actualization and self-esteem in apparel buying process. The impulsiveness in apparel buying process were related to the antecedent moods, affection, tastes, price, display, and sales person or accompanied friends. We found that the hedonistic motives in the apparel buying process connected with the emotional responses and were played an important role on the consumer satisfaction in the apparel buying process. They provide informations about hedonistic motives of apparels to consumer behavior researchers and retailers related to apparel products.

• Journal of Korea Water Resources Association
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• v.33 no.2
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• pp.263-276
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• 2000

This paper is to derive the probable rainfall depths and the probable rainfall intensity formulas for Inchon Metropolitan district. The annual maximum rainfall data from 10 min. to 6 hours have been collected from the Inchon weather station. Eleven types of probability distribution are considered to estimate probable rainfall depths for 12 different storm durations at the Inchon Metropolitan district. Three tests including Chi-square, Kolmogorov-Smimov and Cramer Von Mises with the graphical analysis are adopted to select the best probability distribution. The probable rainfall intensity formulas are then determined by the least squares method using the trial and error approach. Five types of Talbot type, Sherman type, Japanese type, Unified type I, and Unified type II are considered to determine the best type for the Inchon rainfall intensity. The root mean squared errors are computed to compare the accuracy from the derived formulas. It has been suggested that the probable rainfall intensities having Unified type I for the short term duration should be the most reliable formulas by considering the root mean squared errors and the difference between computed probable rainfall depth and estimated probable rainfall depth.