• Journal of computational fluids engineering
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• 제18권1호
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• pp.28-35
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• 2013

Behavior of the side force generated at high angles of attack by two ogive-cylinder bodies of revolution with nose fineness ratio of 2.3 (B1) and 3.5 (B2) and the effect of a strip placed close the nose tip of each body (B1S and B2S) are analyzed through the wind tunnel test at ReD=200,000 and a=42~60 deg. The side force generated by B1 is increased by placing a strip. The side force generated by B2 is in the starboard direction and its magnitude is higher than that of the B1S. The effect of the strips with various dimensions placed on B2 is investigated. It is found that the 4-layer strip placed on the starboard reversed the direction of the side force into port direction. It is confirmed by numerical simulations that the strip promotes the flow separation and increases the average pressure on the side where it is placed and consequently produces the side force in the corresponding direction.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• 제10권5호
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• pp.757-765
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• 1999

In this paper, L-Type aperture coupled circular polarization patch antenna for mobile communication(IMT-2000, 1.9375 GHz), which is capable of being mounted in mobile unit, was designed and fabricated. This antenna is expanded to the $2\times2$ circular polarization array antenna for satellite mobile communications which are using the L-band frequency. The results are as followings : Returnloss 18.56 dB, beamwidth $60^{\circ}$, gain 7 dBd, axial ratio 0.9 dB in the case of single element and returnloss 28.43 dB, beamwidth $38^{\circ}$, gain 9.8dBd, axial ratio 1.5 dB in the case of $2\times2$ array, respectively.

• Journal of Distribution Science
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• 제21권12호
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• pp.91-102
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• 2023

Purpose: This study analyzed the structural relationship between interaction quality and relationship satisfaction, towards providing managerial implications for effective relationship management in the B2B market. Research design, data and methodology: The following survey was conducted only if respondents had used the airline's B2C more than twice. A total of 398 copies were collected and empirical analysis was conducted using AMOS 18.0 and PASW 18.0. Results: The flexibility, quickness, and fairness that make up the interaction quality in airline B2C have been shown to have a significant impact on trust, relationship performance and relationship satisfaction. Conclusions: Usefulness, quickness, and fairness, which are sub-variables of airline B2C mutual quality, have a positive effect on trust. In addition, trust was found to have a positive effect on relationship performance and relationship satisfaction. We draw implications for the importance of interaction quality in order to strengthen and sustain relationships with users in the airline B2C distribution market. In addition, in order to build meaningful relationship performance and relationship satisfaction, interaction quality and trust level should be examined first, and interaction quality improvement should be the top goal.

• Journal of the Institute of Electronics and Information Engineers
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• 제53권7호
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• pp.27-38
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• 2016

This work proposes a 12b 30MS/s 0.18um CMOS SAR ADC based on low-power composite switching with an active die area of $0.16mm^2$. The proposed composite switching employs the conventional $V_{CM}$-based switching and monotonic switching sequences while minimizing the switching power consumption of a DAC and the dynamic offset to constrain a linearity of the SAR ADC. Two equally-divided capacitors topology and the reference scaling are employed to implement the $V_{CM}$-based switching effectively and match an input signal range with a reference voltage range in the proposed C-R hybrid DAC. The techniques also simplify the overall circuits and reduce the total number of unit capacitors up to 64 in the fully differential version of the prototype 12b ADC. Meanwhile, the SAR logic block of the proposed SAR ADC employs a simple latch-type register rather than a D flip-flop-based register not only to improve the speed and stability of the SAR operation but also to reduce the area and power consumption by driving reference switches in the DAC directly without any decoder. The measured DNL and INL of the prototype ADC in a 0.18um CMOS are within 0.85LSB and 2.53LSB, respectively. The ADC shows a maximum SNDR of a 59.33dB and a maximum SFDR of 69.83dB at 30MS/s. The ADC consumes 2.25mW at a 1.8V supply voltage.

• Asian-Australasian Journal of Animal Sciences
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• 제33권12호
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• pp.2021-2030
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• 2020

Objective: Quantitative polymerase chain reaction (qPCR) has been extensively used in the field of mesenchymal stem cell (MSC) research to elucidate their characteristics and clinical potential by normalization of target genes against reference genes (RGs), which are believed to be stably expressed irrespective of various experimental conditions. However, the expression of RGs is also variable depending on the experimental conditions, which may lead to false or contradictory conclusions upon normalization. Due to the current lack of information for a clear list of stable RGs in bovine MSCs, we conducted this study to identify suitable RGs in bovine MSCs. Methods: The cycle threshold values of ten traditionally used RGs (18S ribosomal RNA [18S], beta-2-microglobulin [B2M], H2A histone family, member Z [H2A], peptidylprolyl isomerase A [PPIA], ribosomal protein 4 [RPL4], succinate dehydrogenase complex, subunit A [SDHA], beta actin [ACTB], glyceraldehyde-3-phosphate dehydrogenase [GAPDH], TATA box binding protein [TBP], and hypoxanthine phosphoribosyltrasnfrase1 [HPRT1]) in bovine bone marrow-derived MSCs (bBMMSCs) were validated for their stabilities using three types of RG evaluation algorithms (geNorm, Normfinder, and Bestkeeper). The effect of validated RGs was then verified by normalization of lineage-specific genes (fatty acid binding protein 4 [FABP4] and osteonectin [ON]) expressions during differentiations of bBMMSCs or POU class 5 homeobox 1 (OCT4) expression between bBMMSCs and dermal skins. Results: Based on the results obtained for the three most stable RGs from geNorm (TBP, RPL4, and H2A), Normfinder (TBP, RPL4, and SDHA), and Bestkeeper (TBP, RPL4, and SDHA), it was comprehensively determined that TBP and RPL4 were the most stable RGs in bBMMSCs. However, traditional RGs were suggested to be the least stable (18S) or moderately stable (GAPDH and ACTB) in bBMMSCs. Normalization of FABP4 or ON against TBP, RPL4, and 18S presented significant differences during differentiation of bBMMSCs. However, although significantly low expression of OCT4 was detected in dermal skins compared to that in bBMMSCs when TBP and RPL4 were used in normalization, normalization against 18S exhibited no significance. Conclusion: This study proposes that TBP and RPL4 were suitable as stable RGs for qPCR study in bovine MSCs.

• Progress in Superconductivity and Cryogenics
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• 제18권4호
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• pp.9-14
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• 2016

The effect of the size and shape of magnesium(Mg) powder on the formation of $MgB_2$ and the critical current density($J_{c,}$) of $MgB_2$ bulk was studied. As a precursor for the formation of $MgB_2$, Mg and $MgB_4$ powder, which was synthesized through the reaction of boron (B) with Mg powders, was used. $MgB_4$ was mixed with Mg powders of various sizes, pressed into pellets and heat-treated at $650^{\circ}C-750^{\circ}C$ in flowing argon gas. The XRD analysis of the heat-treated $MgB_2$ samples showed that the volume fraction of $MgB_2$ was the highest as 92.74 % when spherical Mg powder with an average size of $25.7{\mu}m$ was used, whereas the volume fraction was the lowest as 79.64 % when plate-like Mg powder with a size of $34.1{\mu}m$ was used. The superconducting transition temperature ($T_c$) of $MgB_2$ was not sensitive to the characteristics of the Mg powders used. All of the prepared $MgB_2$ samples showed a high $T_c$ of 38.3 K and a small superconducting transition width of 0.2 K-0.5 K. $J_c$ (5 K and 1 T) of $MgB_2$ was the highest as $3.93{\times}10^4A/cm^2$ when spherical Mg powder with a size of $25.7{\mu}m$ was used, whereas $J_c$ was the lowest as $2.18{\times}10^4A/cm^2$when plate-like Mg powder with a size of $34.1{\mu}m$ was used. The relationship between the $J_c$ of $MgB_2$ and the characteristics of the Mg powders used was explained in terms of the volume fraction of $MgB_2$ and the apparent density of the $MgB_2$ pellets.

• Journal of the Institute of Electronics Engineers of Korea SD
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• 제44권11호
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• pp.89-94
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• 2007

For successful implementation of multi-standard transmitter, reconfigurable architecture and component design are essential. This paper presents a reconfigurable CMOS power amplifier designed CMOS 0.25 um process. Designed power amplifier can be operated at 0.9, 1.2, 1.75, and 1.85 GHz. Also, it can be used at 2.4 GHz by using bonding wire inductor. The interstage matching network is composed of two inductors and four switches, and operation frequency can be varied by controlling switches. Proposed power amplifier can be used as a power amplifier in low power applications such as ZigBee or Bluetooth application and used as a driver amplifier in high power application such as CDMA application. Designed power amplifier has 18.2 dB gain and 10.3 dBm output power at 0.9 GHz. Also, it represented 10.3 (18.1) dB gain and 5.2 (10) dBm output power at 1.75 (2.4) GHz.

• Journal of Soil and Groundwater Environment
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• 제18권2호
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• pp.10-18
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• 2013

The pilot scale biopile system was designed and operated for evaluation of bioremediation efficiency for petroleum contaminated soil. The pilot scale biopile consisted of biopile dome, aeration system and monitoring system and two biopiles were operated with nutrients and inoculum for more 100 days. The test pile A and B were analyzed with regard to pH, total carbon contents, water contents, nutrients (N, P) and TPH. The initial TPH concentrations for pile A and pile B were about 10,000 mg/kg and 2,300 mg/kg, respectively. After 100 days, the TPH contents decreased about 70% in the pile A and 30% in the pile B. Also, n-$C_{17}$/pristane and n-$C_{18}$/phytane ratios in all pile were significantly changed. The microbial densities in the pile A was increased by approximately $10^7$ CFU/g-soil~$10^8$ CFU/g-soil, but there was almost no changed in the pile B. The average biodegradation rates were calculated about 66.8 mg/kg-day in the pile A and 10.9 mg/kg-day in the pile B. Over the course of operation period, pile temperature was considered the major limiting factor for the efficiency of all biopiles.

• Korean Journal of Materials Research
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• 제8권11호
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• pp.1038-1042
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• 1998

Mechanical grinding and subsequent annealing were applied to the $Nd_5Pr_7Fe_{82}B_6$ and $Nd_{12}Fe_{82}B_6$ ingots, and the crystal structure and magnetic properties were investigated. After 330 hours milling, the particles with $2~3\mu\textrm{m}$average size were identified to be composed of very fine crystallites judging from the x-ray diffraction patterns. The intrinsic coercivity of 18.36 ~ 18.79 kOe and the maximum energy product of 8.32-8.38 MGOe were obtained by the annealing of the milled powders at $600^{\circ}C$ for 2 hours. Annealing at a higher temperature resulted in the improved magnetic properties. However it was revealed that the control of the micro-crystallites formed during the grinding process was more important to get an optimized magnetic properties than the annealing condition.

• Mycobiology
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• 제51권3호
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• pp.115-121
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• 2023

The fungal strain KNUF-22-18B, belonging to Cucurbitariaceae, was discovered from a stink bug (Hygia lativentris) during the investigation of insect microbiota in Chungnam Province, South Korea. The colonies of the strain KNUF-22-18B were wooly floccose, white to brown in the center on oatmeal agar (OA), and the colonies were buff, margin even, and colorless, reverse white to yellowish toward the center on malt extract agar (MEA). The strain KNUF-22-18B produced pycnidia after 60 days of culturing on potato dextrose agar, but pycnidia were not observed on OA. On the contrary, N. keratinophila CBS 121759^T abundantly formed superficial pycnidia on OA and MEA after a few days. The strain KNUF-22-18B produced chlamydospores subglobose to globose, mainly in the chain, with a small diameter of 4.4-8.8 ㎛. At the same time, N. keratinophila CBS 121759^T displayed a globose terminal with a diameter of 8-10 ㎛. A multilocus phylogeny using the internal transcribed spacer regions, 28S rDNA large subunit, b-tubulin, and RNA polymerase II large subunit genes further validated the uniqueness of the strain. The detailed description and illustration of the proposed species as Neocucurbitaria chlamydospora sp. nov. from Korea was strongly supported by molecular phylogeny.