• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.5
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• pp.684-689
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• 1990

We design a circular microstrip array antenna using the admittance of circular resonator. We can design the array antenna, considering equivalent radius of circular microstdrip consistant with conductances which are obtained from excitation coefficeients of the array elements. The antenna with 10 array elements are made on teflon substrate from Tshebyscheff method. It's perfermence are the gain 8.9dB, half power beam width 11.3dge, max, side lobe level -19dB, and they are almost in agreement with the theoretical results.

• Korean Journal of Radiology
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• v.19 no.6
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• pp.1140-1146
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• 2018

Objective: To compare the spinal enumeration methods that establish the first lumbar vertebra in patients with spinal variants. Materials and Methods: Of the 1446 consecutive patients who had undergone computed tomography of the spine from March 2012 to July 2016, 100 patients (62 men, 38 women; mean age, 47.9 years; age range, 19-88 years) with spinal variants were included. Two radiologists (readers 1 and 2) established the first lumbar vertebra through morphologic analysis of the thoracolumbar junction, and labeled the vertebra by counting in a cranial-to-caudal manner. Inter-observer agreement was established. Additionally, reader 1 detected the 20th vertebra under the assumption that there are 12 thoracic vertebra, and then classified it as a thoracic vertebra, lumbar vertebra, or thoracolumbar transitional vertebra (TLTV), on the basis of morphologic analysis. Results: The first lumbar vertebra, as established by morphologic analysis, was labeled by each reader as the 21st segment in 65.0% of the patients, as the 20th segment in 31.0%, and as the 19th segment in 4.0%. Inter-observer agreement between the two readers in determining the first lumbar vertebra, based on morphologic analysis, was nearly perfect (${\kappa}$ value: 1.00). The 20th vertebra was morphologically classified as a TLTV in 60.0% of the patients, as the first lumbar segment in 31.0%, as the second lumbar segment in 4.0%, and as a thoracic segment in 5.0%. Conclusion: The establishment of the first lumbar vertebra using morphologic characteristics of the thoracolumbar junction in patients with spinal variants was consistent with the morphologic traits of vertebral segmentation.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2133-2141
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• 1995

The thermo-mechanical fatigue tests were performed on the specimens extracted from 1.5Cr-0. 67Mo-0.33V alloy. The characteristics of thermo-mechanical fatigue crack propagation were examined and reviewed in view of fracture mechanics. The results obtained from the present study are summarized as follows : (1) The propagation characteristics of isothermal low-cycle fatigue crack are dominated by .DELTA.J$_{f}$ in case of PP waveform, and .DELTA.J$_{c}$ in case of CP waveform. (II)The propagation characteristics of thermo-mechanical fatigue crack are dominated by .DELTA.J$_{c}$ for in-phase case, and by .DELTA.J$_{c}$ for out-of-phase. The present results were in good agreement with the equation of propagation law for isothermal low-cycle fatigue crack in case of thermo-mechanical fatigue.tigue.e.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.9
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• pp.2353-2364
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• 1995

The ignition phenomena of a solid fuel plate of polymethyl-methacrylate(PMMA), which is vertically positioned and exposed to a thermal radiation source, is numerically studied here. A two-dimensional transient model includes such various aspects as thermal decomposition of PMMA, gas phase radiation absorption, gas phase chemical reaction and air entrainment by natural convection. Whereas the previous studies considers the problem approximately in a one-dimensional form by neglecting the natural convection, the present model takes account of the two-dimensional effect of radiation and air entrainment. The inert heating of the solid fuel is also taken into consideration. Radiative heat transfer is incorporated by th Discrete Ordinates Method(DOM) with the absorption coefficient evaluated using gas species concentration. The thermal history of the solid fuel plate shows a good agreement compared with experimental results. Despite of induced natural convective flow that induces heat loss from the fuel surface, the locally absorbed radiant energy, which is converted to the internal energy, is found to play an important role in the onset of gas phase ignition. The ignition is considered to occur when the rate of variation of gas phase reaction rate reaches its maximum value. Once the ignition takes place, the flame propagates downward.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.9
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• pp.968-977
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• 2008

In this paper, an analysis of TE-wave scattering from transversal-shifted tandem slits using fourier transform analysis and Wiener-Hopf technique are derived and the electrical performances have been compared with a commercially availabel software. In Fourier transform analysis, it is shown that a fast-convergent series solution can be obtained when the distance between the slits is very narrow, while in Wiener-Hopf technique, it is found that the highly-accurate approximation can be obtained when the gap between the slits becomes wider. In addition, this paper has dealt with a good agreement between two analytical solutions.

• Journal of Environmental Science International
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• v.19 no.9
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• pp.1169-1175
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• 2010

A case study for the design of a wind farm in complex terrain was carried out using the wind farm site analysis software OpenWind, which has an open-source platform and is free to use. The Youngdeok Wind Farm, constructed on mountainous terrain in Korea, was chosen as a model site; the design process reproduced using OpenWind. A comparison of the positions of the wind turbine derived from the OpenWind optimization process and the current positions were in good agreement. The annual energy production predicted by OpenWind compared with the prediction by the micrositing software, WindSim, were also validated to within 1%. Therefore, it was confirmed that OpenWind can be used for a practical wind farm design project. It is also anticipating that this paper will provide a prototype process for the design of a wind farm site and offer a database for the post-evaluation of a constructed wind farm in Korea.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.6
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• pp.277-285
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• 2022

This study aims to investigate the impact of the Corona pandemic on the earning quality (EQ) of Saudi national banks. It was conducted to evaluate the measurement of the earning quality based on the Penman approach. The researchers used the analytical method to conduct the study to find the effect of this Pandemic. Data was collected from the annual reports for the period 2010 to 2020 from Saudi national banks, which are twelve according to the annual report for the Saudi central bank, and eight of them were selected as a sample of the study. The banks are Alinma Bank, Al Rajhi Bank, Bank Al Bilad, The National Commercial Bank, Bank Aljazeera, Riyad Bank, Samba Financial Group (Samba), and Arab National Bank. The study findings showed that the Corona pandemic had a negative impact on the Saudi economy, and led to deflation in 2020 by 4.1% due to the oil sector. They also showed reducing oil production by the (OPEC +) agreement to achieve stability in the oil market and the non-oil sector. It was also revealed that the profits of Saudi commercial banks in 2020 decreased by 23.1% and that the Corona pandemic had Caused the earning quality to decline in all the studied banks.

• Steel and Composite Structures
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• v.9 no.1
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• pp.19-38
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• 2009

The present paper provides test data to evaluate the seismic performance of recycled aggregate concrete (RAC) filled steel square hollow section (SHS) beam-columns. Fifteen specimens, including 12 RAC filled steel tubular (RACFST) columns and 3 reference conventional concrete filled steel tubular (CFST) columns, were tested under reversed cyclic flexural loading while subjected to constant axially compressive load. The test parameters include: (1) axial load level (n), from 0.05 to 0.47; and (2) recycled coarse aggregate replacement ratio (r), from 0 to 50%. It was found that, generally, the seismic performance of RACFST columns was similar to that of the reference conventional CFST columns, and RACFST columns exhibited high levels of bearing capacity and ductility. Comparisons are made with predicted RACFST beam-column bearing capacities and flexural stiffness using current design codes. A theoretical model for conventional CFST beam-columns is employed in this paper for square RACFST beam-columns. The predicted load versus deformation hysteretic curves are found to exhibit satisfactory agreement with test results.

• Journal of Aerospace System Engineering
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• v.9 no.1
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• pp.19-27
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• 2015

The Technical Standard Order articles are the parts and appliances for which the civil aviation authority designates as it is necessary to standardize for the expedited certification process and aviation safety. TSO articles were used on the type certified aircraft as replacement parts in the early days of TSO authorization system, but those articles are widely used on the newly developed aircraft as well in these days. In this paper, we compared the differences of the TSO authorization systems between FAA and EASA, and proposed the rulemaking items to improve Korean TSO authorization system and to contribute to growth of aviation industry.

• Archives of Craniofacial Surgery
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• v.22 no.1
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• pp.17-25
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• 2021

Background: This study aims to report how the practice of plastic surgeons and their attitude was during the first measure period of coronavirus disease 2019 (COVID-19) pandemic. Methods: A survey study was held among members of the Indonesian Association of Plastic Reconstructive and Aesthetic Surgeons during week 5 after the first report of COVID-19. A 10 multiple-choice questions (MCQs) and 1 essay covered key questions on the area of surgery and operating room, clinics, internal meeting, and consultation. The only open-ended question relates to the last MCQ addresses a future "flipped" medical practice. Results: Response rate was 45.6% among 228 members, with 89.4% did no practice or limited their service to emergency and urgent cases only. Only 1.9% kept their official meeting as usual, while the majority modified it. The practice in the operating theatre and clinic were also altered to comply with the measures; with 21.2% from the total respondents only allowed patients with exposure to come for visit after taking 14 days of self-quarantine. Teleconsultation was practiced by 50% of the respondents, while 41.3% agreed and 10.6% disagreed upon the future "flipped" medical practice. Conclusion: In general plastic surgeons have made supportive actions during the pandemic. Surgery was performed with all precautions at the utmost as a reflection of high alert of viral infection. Teleconsultation has been embraced via existing social media. Agreement upon the future "flipped" medical practice is reasonable. All in all, the actions were considered as most relevant.