• Journal of Communications and Networks
• /
• v.18 no.2
• /
• pp.150-161
• /
• 2016

Coordinated multi-point transmission (CoMP) techniques are being touted as enabling technologies for interference mitigation in next generation heterogeneous wireless networks (HetNets). In this paper, we present a comparative performance study of uplink (UL) CoMP algorithms for the 3GPP LTE HetNets. Focusing on a distributed and functionally-split architecture, we consider six distinct UL-CoMP algorithms: 1. Joint reception in the frequency-domain (JRFD) 2. Two-stage equalization (TSEQ) 3. Log-likelihood ratio exchange (LLR-E) 4. Symmetric TSEQ (S-TSEQ) 5. Transport block selection diversity (TBSD) 6. Coordinated scheduling with adaptive interference mitigation (CS-AIM) where JRFD, TSEQ, S-TSEQ, TBSD and CS-AIM are our main contributions in this paper, and quantify their relative performances via the post-processing signal-to-interference-plus-noise ratio distributions.We also compare the CoMP-specific front-haul rate requirements for all the schemes considered in this paper. Our results indicate that, with a linear minimum mean-square error receiver, the JRFD and TSEQ have identical performances, whereas S-TSEQ relaxes the front-haul latency requirements while approaching the performance of TSEQ. Furthermore, in a HetNet environment, we find that CS-AIM provides an attractive alternative to TBSD and LLR-E with a significantly reduced CoMP-specific front-haul rate requirement.

• Restorative Dentistry and Endodontics
• /
• v.44 no.3
• /
• pp.23.1-23.9
• /
• 2019

Objectives: The aim of this study was to investigate the microshear bond strength (${\mu}SBS$) of different universal adhesive systems applied to hybrid computer-aided design/computer-aided manufacturing (CAD-CAM) restorative materials repaired with a composite resin. Materials and Methods: Four types of CAD-CAM hybrid block materials-Lava Ultimate (LA), Vita Enamic (VE), CeraSmart (CS), and Shofu Block HC (SH)-were used in this study, in combination with the following four adhesive protocols: 1) control: porcelain primer + total etch adhesive (CO), 2) Single Bond Universal (SB), 3) All Bond Universal (AB), and 4) Clearfil Universal Bond (CU). The ${\mu}SBS$ of the composite resin (Clearfil Majesty Esthetic) was measured and the data were analyzed using two-way analysis of variance and the Tukey test, with the level of significance set at p < 0.05. Results: The CAD-CAM block type and block-adhesive combination had significant effects on the bond strength values (p < 0.05). Significant differences were found between the following pairs of groups: VE/CO and VE/AB, CS/CO and CS/AB, VE/CU and CS/CU, and VE/AB and CS/AB (p < 0.05). Conclusions: The ${\mu}SBS$ values were affected by hybrid block type. All tested universal adhesive treatments can be used as an alternative to the control treatment for repair, except the AB system on VE blocks (the VE/AB group). The ${\mu}SBS$ values showed variation across different adhesive treatments on different hybrid CAD-CAM block types.

• Resources Recycling
• /
• v.31 no.5
• /
• pp.20-25
• /
• 2022

In this study, the applicability of microalgae was evaluated for eco-friendly decontamination of cesium-137 (Cs-137) and strontium-90 (Sr-90), which are radioactive nuclides contained in radioactive waste. The monolithic radioactive solution used in the experiment was manufactured at a concentration of 1.5 Bq/mL Cs-137 and 1.0 Bq/mL Sr-90 by diluting a standard radioactive solution and distilled water. This experiment used two types of microalgae, Chlorella Vulgaris was used for Sr-90 decontamination and Hematococcus pluvialis for Cs-137 decontamination. The experimental method is to put the microalgae cultured for 2 weeks into a bottle with a semi-permeable membrane, and then put the bottle in which the microalgae was put into the manufactured radioactive solution, so that the microalgae and the radioactive solution react through the semi-permeable membrane for 48 hours. For the radioactivity concentration analysis of each sample, a gamma-ray nuclide analyzer was used for Cs-137, a γ-ray isotope, and a Liquid Scintillation Count(LSC) was used f or Sr-90, a β-ray isotope. As a result of the experiment, it was confirmed that about 88.0 % of Cs-137 and about 89.7 % of Sr-90 could be decontaminated, and about 98.6 % of Sr-90 was finally able to be decontaminated by the two-stage decontamination method.

• Journal of Radiation Protection and Research
• /
• v.20 no.4
• /
• pp.255-263
• /
• 1995

Root uptakes of $^{54}Mn,\;^{60}Co,\;^{85}Sr\;and\;^{137}Cs$ by rice were studied through a greenhouse experiment in which the upper 20 cm of the culture box was filled with an acidic loamy-sandy soil and a mixed solution of the radionuclides was applied to the surface water on the soil 2 days before, and 5 different times after, transplanting. Percent uptakes of the radionuclides to rice tops varied $3.4{\sim}13.7%,\;0.03{\sim}0.1%,\;0.6{\sim}1.5%,\;0.02{\sim}0.15%$, respectively, with application time. Among radionuclides, soil-to-plant transfer factors decreased, on the whole, in the order of $^{54}Mn>^{85}Sr>^{60}Co{\geq}^{137}Cs$, and among plant parts, in the order of straw > chaff > hulled seed. Transfer factors $(m^2/kg-dry)$ in hulled seed were, depending on application time, $1.2{\times}10^3{\sim}5.0{{\times}10^3\;for\;^{54}Mn,\;1.6{\times}10^5{\sim}2.6{\times}10^4\;for\;^{60}Co,\;1.1{\times}10^4{\sim}7.6{\times}10^4\;for\;^{85}Sr\;and\;5.2{\times}10^5{\sim}7.0{\times}10^4\;for\;^{137}Cs$. The highest factors of all the radionuclides in straw came from the application at 67 days after transplanting while those of $^{54}Mn,\;^{60}Co\;and\;^{85}Sr$ in hulled seed appeared at later applications. The data from this studv can be referred to in assessing the radiological impact of an accidental contamination during the rice growth.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.61 no.1
• /
• pp.85-93
• /
• 2019

The objective of this study is to assess the environmental effect of the reclaimed land drainage method using oyster shell through the Life cycle $CO_2$ assessment, and to evaluate the applicability in South Korea. In this Study, the life cycle $CO_2$ emissions of oyster shell (OS) and crushed stone (CS, as avoided product) were assessed and compared. The Life Cycle Assessment method was used for quantitative evaluation of direct or indirect environmental effects of OS recycling. $CO_2$ was selected as the evaluation target material, and the scope of assessment includes the acquisition of materials, processing, transportation, construction phases. Compared to using CS, 77.0% of $CO_2$ emissions in acquisition and processing, 47.0% in transportation and 6.5% in construction phase were reduced, respectively by using of OS. The maximum transportation distance of OS was estimated according to transportation distance of CS. OS has environmental advantages than CS within about 26 - 101 km from the source. OS was found to be applicable to reclaimed lands up to 810 ha, 3,910 ha from Tongyeong and Yeosu, respectively. In addition, the amount of OS that could be used as drainage material for reclaimed land was much higher than annual OS production of South Korea. Therefore, it is considered that OS is sufficient to be used as drainage material for reclaimed land in South Korea.

• Journal of Sensor Science and Technology
• /
• v.7 no.5
• /
• pp.319-326
• /
• 1998

Anodic half-reaction in the $Na^+$ ionic sensors using $Na_2CO_3$ and $MCO_3$ ($M=Cs_2,K_2,Li_2,Ca$) as a sensitive membrane is derived in continuous flow system to explain $CO_2$ sensing characteristics. For various gas-sensitive membranes, a well known overall reaction, $MCO_3\;=\;MO\;+\;CO_2$, cannot be applied for the EMF behaviors of these kinds of sensors. So, the anodic reaction is found to involve $Na_2CO_3$ and $M^{++}$-containing oxide phases by employing the ion exchange reaction at the interface of solid electrolyte and the sensitive membrane to maintain ionic balance in the whole cell. Based on the electrode reaction derived in flow system, differences of cell potentials between continuous and discontinuous flow systems were also discussed. These EMF differences were considerably caused by the partial pressures of oxygen and $CO_2$ as well as irreversible chemical reactions between electrode materials and $CO_2$ atmosphere.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.11
• /
• pp.1566-1570
• /
• 2013

In this paper, we analyzed the electric characteristics of the OLEDs device of which anode ITO has been treated with the oxygen plasma. We fabricated the basic three-layer structure (ITO / AF / $Alq_3$ / $Cs_2CO_3$ / Al) device, analyzed how the oxygen plasma treatments of the ITO surface affects to the electrical characteristics of OLEDs. We also produced a four-layer structure device (ITO / AF / TPD / $Alq_3$ / $Cs_2CO_3$ / Al) with the oxygen plasma treatment. From the comparative analysis to the devices, we confirmed following results. The three-layer structure OLEDs device with oxygen plasma treatment has better characteristics than the device without the treatments; maximum luminance, luminous efficiency, and external quantum efficiency are improved approximately 151 [%], 126 [%], and 175[%], respectively. Also, the electric characteristics of the four-layer structure device with oxygen plasma treatment are improved comparing to the characteristics of the three-layer structure device with oxygen plasma treatment; maximum luminance, luminous efficiency, and external quantum efficiency are improved approximately 144 [%], 115 [%], and 124[%], respectively.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.5 no.3
• /
• pp.179-188
• /
• 2007

In this work $^{14}C\;and\;^3H$ distribution characteristics of spent resins from nuclear power plants(NPPs), pressurized water reactors(PWRs), was investigated. It was found that the recovery percent of $^{14}C$ by the wet oxidation-acid stripping was $81%{\sim}100%$ for the added activity range of $^{14}C,\;0.72\;Bq{\sim}460\;Bq$, and it was not affected by the kinds of stripping acids, 3N-HCl, $3\;N-HNO_3\;and\;3\;N-H_2SO_4$. And the recovery percent of $^3H$ by distillation using the same apparatus was $81%{\sim}101%$ for the added activity range of $^3H,\;0.60\;Bq{\sim}435\;Bq$. Among the tested stripping acids, 3\;N-HCl, $3\;N-HNO_3\;and\;3\;N-H_2SO_4$, only the trapped $^3H$ solution by distillation in $3\;N-H_2SO_4$ was compatible with the 3H scintillator, Ultimagold XR. Neither of the $^{14}C\;and\;^3H$ trapping solutions from the spent ion exchange resin samples by the wet oxidation-3 $N-H_2SO_4$ stripping contained gamma nuclides. However, some gamma nuclides, $^{60}Co,\;^{134}Cs,\;^{137}Cs\;and\;^{54}Mn$, were found in the trapped $^3H$ solutions of the spent resins by the wet oxidation-3 N-HCl stripping. It was the same for the $^3H$ trapping solutions of the spent resins by Sample Oxidizer(PACKARD MODEL 307). Meanwhile only two nuclides, $^{134}Cs,\;and\;^{134}Cs$, were found in the $^{14}C$ trapping solutions of the spent resins by Sample Oxidizer(PACKARD MODEL 307). It was found that most of the $^{14}C$ in the spent resins existed as inorganic carbon form, more than about 70% of the total $^{14}C$ content. Among the analyzed 30 spent ion exchange resin samples, the average concentration of $^{14}C$ and $^3C$ for the high radioactive samples, 8 samples, was $19000\;Bq/g{\pm}41000\;Bq/g,\;670\;Bq/g{\pm}460\;Bq/g$ and that for the low radioactive samples, 22 samples, was $4.2\;Bq/g{\pm}4.3\;Bq/g,\;6.0\;Bq/g{\pm}5.3\;Bq/g$, respectively. And the average $^{14}C/^3H$ ratio for the high radioactive samples, was higher, 28, than that of low radioactive samples, 0.70. Some linear relationship trend was found between the activity concentrations of $^{14}C\;and\;^3H$.

• Nuclear Engineering and Technology
• /
• v.27 no.5
• /
• pp.767-774
• /
• 1995

Behavior of radionuclides such $^{60}$ Co, $^{54}$ Mn and $^{137}$ Cs in the incineration Process was Studied by trial burns of simulated wastes with radio-isotope tracers. Behavior of nonvolatiles, $^{60}$ Co and $^{54}$ Mn, was similar to that of particulate matters in the process. Decontamination factors(DFs) for $^{60}$ Co and $^{54}$ Mn were 4.7$\times$10$^{5}$ and 6.2$\times$10$^{5}$ , respectively. Behavior of semivolatile radio-isotope, $^{137}$ Cs, was temperature dependent. DFs for $^{l37}$Cs at In different incineration temperature of 85$0^{\circ}C$ and $700^{\circ}C$ were 2.8$\times$10$^3$ and 2.6$\times$10$^4$, respectively. Trial bums of dry active waste(DAW) transported from nuclear power station(NPS) Kori 3,4 were also performed. DF for gross $\beta$/${\gamma}$ radioactivity in DAW was 1.1$\times$10$^{5}$ . This was a little higher than the estimated value, which was calculated from the tracer test results and nuclides distribution in the DAW. Average emission concentration was 0.019 Bq/N $m^3$, which could meet the maximal permissible concentration(MPC) in stack emission.n.

• Journal of Radiation Protection and Research
• /
• v.22 no.3
• /
• pp.171-181
• /
• 1997

A mixed solution of $^{54}Mn$, $^{60}Co$, $^{85}Sr$ and $^{137}Cs$ was applied to the soil of culture boxes in a greenhouse 2 days before transplanting red pepper and at 3 different times during its growth for investigating transfer factors ($m^2/kg-dry$) for its green and red fruits. Transfer factors varied with radionuclide, application time and harvest time by factors of about $20{\sim}100$. They decreased mostly in the order of $^{85}Sr>^{54}Min>^{60}Co>^{137}Cs$ while $^{54}Mn$ and $^{60}Co$ was higher than $^{85}Sr$ when time lapse between application and harvest was short. Transfer factors of $^{85}Sr$ and $^{137}Cs$ at the last application were lower than those at the previous one by factors of $3{\sim}20$ depending on harvest time. Variations in $^{54}Mn$ and $^{60}Co$ transfer factors with application time after transplanting were comparatively low. Transfer factors of $^{54}Mn$, $^{60}Co$ and $^{85}Sr$ mixed with topsoil before transplanting were up to $3{\sim}9$ times higher than those for the application onto soil surface 2 days after transplanting while there was no difference in $^{137}Cs$. The present results can be referred to in estimating root-uptake concentrations of the radionuclides in red pepper fruit and taking proper measures for its harvest and consumption at the event of an accidental release during the growing season of red pepper.