• Journal of Plant Biology
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• v.24 no.1
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• pp.1-12
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• 1981

Phosphorus dynamics in terms of specific absorption rate, inflow and outflow rates. turnover rate, demand and supply, and utility index of a high yield Zea mays L. cv. Bokgyo field were evaluated using an analysis of successive production structures. The analysis was adopted for measuring quantitative changes in the population by stratified clip technique on every two weeks during the growing season. The seasonal trends of specific absorption rate (2. 4 mg P/g/day in maximum) and specific absorption efficiency (0. 03) closely correlated with that of relative growth rate of the population. The overall inflow and outflow of phosphorus was 3.41 g P/$m^2$/yr showing the maximum inflow of 2.99 g P/$m^2$/month in July. While the maximum phosphorus standing crop was 1.4 g P/$m^2$ showing the maximum turnover rate of 178% in late June. The accumulation of phosphorus along plant height declined monotonically in stems and roots but increased in foliage after heading. The proportions of the total annual demand of phosphorus were 24.4% for leaves, 22.5% for stems, 49.6% for fruits and 3.5% for roots. These demands were met with internal (18.2 %) and external (81.8 %) supplies. The seasonal highest phosphorus utility index was 1,091 in early June, while the average value was 655.

• Resources Recycling
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• v.32 no.2
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• pp.52-58
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• 2023

In this study, soda lime was prepared from slaked lime to expand the scope of limestone use. To evaluate carbon dioxide absorption, an extruder-type and disc-type pelletizers were used to make the soda lime using bentonite as an additive. Regardless of the pelletizing process, the peak of CaCO₃ was confirmed in soda lime due to its reaction with carbon dioxide. Furthermore, it was confirmed that both calcite and aragonite were present together. The soda lime prepared using the disc-type pelletizer showed a larger specific surface area than that prepared using the extruder-type pelletizer did, and the specific surface area improved on adding bentonite. The carbon dioxide absorption rate increased under the sample condition with an enhanced specific surface area.

• Journal of electromagnetic engineering and science
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• v.15 no.3
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• pp.167-172
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• 2015

Research results on possible effects caused by radiofrequency fields in children are limited because most of the studies published so far have focused on adults, rather than children. Mobile phone use is now widespread, even among younger children. If a biological risk due to mobile phone exposure is found, it might be greater in children because their bodies might be more sensitive to radiofrequency energy. The issue of a possible difference in sensitivity between adults and children begins with whether any difference exists physically in terms of electromagnetic absorption. This paper presents a review of recent publications on dosimetric comparisons between children and adults with respect to radiation from mobile phones. The issue of the health effects of mobile phone use is beyond the scope of the present review. Most of the dosimetry research on possible differences in power absorption between children and adults has been based on numerical modeling and analysis. The understanding of the results so far is presented and needed studies are described.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.6
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• pp.665-680
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• 1997

The specific absorption rate (SAR) distributions in various models of the human head have been analyzed when the models are exposed to 350 MHz and 900 MHz plane waves. The numerical analysis is performed with the finite-difference time-domain (FDTD) method. A homogeneous sphere including a cylinderical neck, a homogeneous head shaped model, and a heterogeneous realistic model are used as models of human head. The incident plane wave used for these calculations is propagating from the front to the back or from the back to the front of the head model, with its E-field vector orientation being parallel to the major length of the body. The specific findings are: 1) the average SARs of the three models are similar mutually but the local SARs of them differ greatly mutually; 2) the power is deposed more deeply in the head at 350 MHz, which is roughly the resonant frequency of a human head, than at 900 MHz; 3) for a plane wave propagating from the back, "hot spot" is found in the neck region, not in the head; 4) for a plane wave propagating from the front, "hot spot" is found in the nose at 900 MHz, and in the upper part of the lip and the jaw region at 350 MHz.

• Korean Chemical Engineering Research
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• v.57 no.4
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• pp.469-474
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• 2019

Fermentation of palm oil mill effluent (POME) produces biohydrogen in a mixture at a specific set condition. This research was conducted to purify the produced mixed biohydrogen via absorption and membrane techniques. Three different solvents, methyl ethanolamine (MEA), ammonia ($NH_3$) and potassium hydroxide (KOH) solutions, were used in absorption technique. The highest $H_2$ purity was found using 1M MEA solution with 5.0 ml/s feed mixed gas flow rate at 60 minutes absorption time. Meanwhile, the purified biohydrogen using a polysulfone membrane had the highest $H_2$ purity at 2~3 bar operating pressure. Upon testing with proton exchange membrane fuel cell (PEMFC), the highest current and power produced at 100% $H_2$ were 1.66 A and 8.1 W, while the lowest were produced at 50/50 vol% $H_2/CO_2$ (0.32 A and 0.49 W). These results proved that both purification techniques have significant potential for $H_2$ purification efficiency.

• Computers and Concrete
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• v.20 no.2
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• pp.205-214
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• 2017

The Hydraulically driven test system and ${\Phi}100mm$ split Hopkinson pressure bar(SHPB) test device were employed to research the quasi-static and dynamic mechanical properties of concrete specimens which has been immersed for 60 days in sodium sulfate (group S1) and sodium chloride (group S2) solution, the evolution of their mass during corrosive period was explored at the same time, and the mechanism of performances lost was analyzed from the microscopic level by using scanning electron microscope. Results of the experimental indicated that: their law of mass both presents the trend of continuous rising during corrosive period, and it increases rapidly on the early days, the mass growth of group S1 and group S2 in first 7 days are 76.78% and 82.82% of their total increment respectively; during the corrosive period, the quasi-static compressive strength of specimens in two groups are significantly decreased, both of which present the trend of increase first and then decrease, the maximum growth rate of group S1 and group S2 are 7.52% and 12.71% respectively, but they are only 76.23% and 82.84% of specimens which under normal environment (group N) on day 60; after immersed for 60 days, there were different decrease to dynamic compressive strength and specific energy absorption, and so as their strain rate sensitivities. So the high salinity environment has a significant effect of weaken the quasi-static and dynamic mechanical performance of concrete.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.16 no.9 s.100
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• pp.903-908
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• 2005

In this paper, in order to consider SAR(Specific Absorption Rate) problem at the beginning stage of a handset development, we investigated the Shh value change by using simulation method according to various EMI(Electromagnetic Interference) paint patterns on front case of a handset and folding angles. First, we made some experiments with EMI paint pattern on front case of a handset, and obtained results showed that different patterns of EMI paint had different SAR values. Among the simulation results on SAR value according to EMI paint patterns, the hairpin pattern showed the best performance, i.e. the decrease efficiency of $8.04\%$ and completely removed pattern showed the decrease efficiency of $5.94\%$. Orignal pattern was set as the reference and the folding angle was $150^{\circ}$. Second, simulation was carried out with changing folding angle from $150^{\circ}$ to $140^{\circ}$ and $160^{\circ}$. Simulation results for the modeled handset showed that SAR value was decreased with increasing the folding angle. When the folding angle was $160^{\circ}$ and with original pattern, we got the SAR value of about 1,61 W/kg. When we applied hairpin pattern with the folding angle of $160^{\circ}$, we got the lowest SAR value of about 1.45 W/kg.

• Journal of the Korean Physical Society
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• v.73 no.10
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• pp.1584-1588
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• 2018

During hyperthermia therapy, cancer cells are heated to a temperature in the range of $40{\sim}45^{\circ}C$ for a defined time period to damage these cells while keeping healthy tissues at safe temperatures. Prior to hyperthermia therapy, the amount of heat energy transferred to the cancer cells must be predicted. Among various non-invasive methods, the thermal prediction method using the specific absorption rate (SAR) is the most widely used method. The existing methods predict the thermal distribution by using a single constant for the mass density in one organ through assignment. However, because the SAR and the bio heat equation (BHE) vary with the mass density, the mass density of each organ must be accurately considered. In this study, the mass density distribution was calculated using the relationship between the Hounsfield unit and the mass density of tissues in preceding research. The SAR distribution was found using a quasi-static approximation to Maxwell's equation and was used to calculate the potential distribution and the energy distributions for capacitive RF heating. The thermal distribution during exposure to RF waves was determined by solving the BHE with consideration given to the considering contributions of heat conduction and external heating. Compared with reference data for the mass density, our results was within 1%. When the reconstructed temperature distribution was compared to the measured temperature distribution, the difference was within 3%. In this study, the density distribution and the thermal distribution were reconstructed for the agar phantom. Based on these data, we developed an algorithm that could be applied to patients.

• Journal of Magnetics
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• v.20 no.3
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• pp.215-220
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• 2015

The PVDF fibrous composite filled with iron oxide nanoparticles were prepared by using the electrospinning technique. The electrospun composite have the thickness in the range of $60-80{\mu}m$ with the average fibrous diameters of 500-900 nm. The magnetizations of PVDF fibrous composite filled with iron oxide nanoparticles showed 4.5 emu/g, 3.1 emu/g and 1.6 emu/g at 1.5 T of external magnetic field for 20 wt.%, 10 wt.% and 5 wt.% iron oxide nanoparticles, respectively. The heat elevation of the magnetic composite were measured under various AC magnetic fields, frequency and the ambient temperatures. The temperature reached up to $46.3^{\circ}C$ from $36^{\circ}C$ at 128 Oe and 355 kHz for 20 wt.% iron oxide nanoparticles filled in PVDF fibrous composite sheet. The specific absorption rate of theses sheets increased from 0.041 W/g to 0.236 W/g with the increment of AC magnetic field from 90 Oe to 167 Oe at 190 kHz, respectively.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.9 no.6
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• pp.776-787
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• 1998

This paper analyzes the local specific absorption rates (SAR's) averaged over 1 g and 10 g in a human head model in contact with a mobile phone operating at 835 MHz. The used numerical method is a total field finite-difference time-domain (FDTD) technique. The phone was simulated with a conducting box, a plastic case, and a whip antennal composed of a monopole and a helix. The discrete human model of the spatial resolution 3 mm is based on Magnetic Resonance Imaging (MRI), computerized tomography (CT) and anatomical images. The near field and far field and far field patterns were analyzed for extended and retracted phone. The two methods to take the volumes of the weights, 1 g or 10 g in tissue are proposed and compared to offer a reproductive technique for SAR estimations.