• Electrical & Electronic Materials
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• v.7 no.6
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• pp.534-542
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• 1994

Microstructures and dielectric properties of (Sr$_{1-x}$ .Ca$_{x}$)TiO$_{3}$+0.006Nb$_{2}$O$_{5}$ (0.05.leq.x.leq.0.2) ceramic were investigated. The specimens fired in a reducing atmosphere(N$_{2}$) were painted on the surface with CuO paste, and then annealed at 1100.deg. C for 2 hr. SEM and EDAX revealed that CuO penetrated rapidly into the bulk along the grain boundaries during the annealing. Grain size increased with increasing Ca content up to 15[mol%], but decreased with further addition. In the specimens with 10-15[mol%l of Ca, excellent dielectric properties were obtained as follows; dielectric constant <25000, dielectric loss(tan .delta[%]) <0.3[%] and capacitance change rate with temperature <.+-.[%], respectively. All the specimens in this study exhibited dielectric relaxation with frequency as a function of the temperature. The dispersive frequency was over 10$^{6}$ [Hz].z].

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.10
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• pp.5257-5261
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• 2012

Background: High incidence of breast cancer and its fatal effect has reached an alarming stage across the globe, including the third world countries. Many factors have been reported to be associated with the development of breast cancer but detailed structural and functional information is missing. CA 15-3 is one of the known potential tumor marker of breast cancer; however little is known about structure and functional site of this protein. Present study aims to investigate the functional role of CA 15-3 in breast cancer, especially in development and metastasis. Material and Methods: Hundred female breast cancer patients confirmed by histopathological reports were included in the study. Their physiological characters were recorded in a performa. Enzyme linked immunosorbent assay (ELISA) technique was used to estimate serum CA 15-3 level. Immunohistochemistry was done for estrogen (ER), progesterone (PR) and Her2/neu receptors expression. Results: The study revealed the details of physiological characteristics of female breast cancer. Mean age was $37.72{\pm}5.99$ and $55.05{\pm}7.28$ years and serum CA 15-3 (MUC1) level was $60.47{\pm}8.59$ and $63.17{\pm}4.58$ U/ml in pre and post-menopause respectively, and both groups of women had sedentary life style. Their receptor status especially of progesterone, estrogen and HER-2/neu were positive in 50% of premenopausal women and 65% of postmenopausal women. Conclusion: There are multiple physiological factors promoting breast cancer. High serum CA 15-3 level and hormonal imbalance of ER, PR and Her2/neu appears to be the main cause of breast cancer. It may be possible that the functional sites of these proteins may be altered which may increase the chances of metastasis in breast cancer.

• ETRI Journal
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• v.34 no.1
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• pp.24-34
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• 2012

In this paper, the directional carrier sense multiple access/collision avoidance (CSMA/CA) protocol in the immediate acknowledgement mode for IEEE 802.15.3c is analyzed under saturation environments. For the analysis, a sensing region and an exclusive region with a directional antenna are computed probabilistically and a Markov chain model in which the features of IEEE 802.15.3c and the effects of using directional antennas are incorporated is analyzed. An algorithm to find the maximal number of concurrently transmittable frames is proposed. The system throughput and the average transmission delay are obtained in closed forms. The numerical results show the impact of directional antennas on the CSMA/CA media access control (MAC) protocol. For instance, the throughput with a small beamwidth of antenna is more than ten times larger than that for an omnidirectional antenna. The overall analysis is verified by a simulation. The obtained results will be helpful in developing an MAC protocol for enhancing the performance of mmWave wireless personal area networks.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.243-244
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• 2013

Over the past 15 years, several groups have incorporated radio-frequency quadrupole (RFQ) based instruments before the accelerator in accelerator mass spectrometry (AMS) systems for ion-gas interactions at low kinetic energy (＜40 eV). Most AMS systems arebased on a tandem accelerator, which requires negative ions at injection. Typically, AMS sensitivity abundance ratios for radioactive-to-stable isotope are limited to Xr/Xs ＞10^-15, and the range of isotopes that can be analyzed is limited because of theneed to produce rather large negative ion beams and the presence of atomic isobaric interferences after stripping. The potential of using low-kinetic energy ion-gas interactions for isobar suppression before the accelerator has been demonstrated for several negative ion isobar systems with a prototype RFQ system incorporated into the AMS system at IsoTrace Laboratory, Canada (Ontario, Toronto). Requisite for any such RFQ system applied to very rare isotope analysis is large transmission of the analyte ion. This requires proper phase-space matching between the RFQ acceptance and the ion beam phase space (e.g. 35 keV, ${\varphi}3mm$, +-35 mrad), and the ability to control the average ion energy during interactions with the gas. A segmented RFQ instrument is currently being designed at Korea Institute for Science and Technology (한국과학기술연구원, KIST). It will consist of: a) an initial static voltage electrode deceleration region, to lower the ion energy from 35 keV down to ＜40 eV at injection into the first RFQ segment; b) the segmented quadrupole ion-gas interaction region; c) a static voltage electrode re-acceleration region for ion injection into a tandem accelerator. Design considerations and modeling will be discussed. This system should greatly lower the detection limits of the 6 MV AMS system currently being commissioned at KIST. As an example, current detection sensitivity of 41Ca/Ca is limited to the order of 10^-15 while the 41Ca/Ca abundance in modern samples is typically 41Ca/Ca~10^-14 - 10^-15. The major atomic isobaric interference in AMS is 41K. Proof-of-principal work at IsoTrace Lab. has demonstrated that a properly designed system can achieve a relative suppression of KF3-/41CaF3- ＞4 orders of magnitude while maintaining very high transmission of the 41CaF3- ion. This would lower the 41Ca detection limits of the KIST AMS system to at least 41Ca/Ca~10^-19. As Ca is found in bones and shells, this would potentially allow direct dating of valuable anthropological archives and archives relevant to our understanding of the most pronounced climate change events over the past million years that cannot be directly dated with the presently accessible isotopes.

• Journal of Korean Society of Water and Wastewater
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• v.33 no.2
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• pp.95-101
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• 2019

High voltage impulse(HVI) has been gained attention as an alternate technique controlling $CaCO_3$ scale formation. Investigation of key operational parameters for HVI is important, however, those had not been reported yet. In this study, the effect of temperature and applied voltage of HVI on $Ca^{2+}$ concentration was studied. As the applied voltage from 0 to 15kV and the temperature increased from 20 to $60^{\circ}C$, the $Ca^{2+}$ concentration decreased, indicating that the aqueous $Ca^{2+}$ precipitated to $CaCO_3$. The $Ca^{2+}$ concentration decreased up to 81% under the condition of 15kV and $60^{\circ}C$. Rate constant for the precipitation reaction, k was determined under different temper1ature and voltage. The reaction rate constant under the 15kV and $60^{\circ}C$ condition was evaluated to $66{\times}10^{-3}L/(mmol{\cdot}hr)$, which was 5 times greater than the k of the reaction without HVI at same temperature. The increases in k by HVI at higher temperature region(40 to $60^{\circ}C$) was much greater than at lower temperature region(20 to $40^{\circ}C$), which implies temperature is more important parameter than voltage for reducing $Ca^{2+}$ concentration at high temperature region. These results show that the HVI induction accelerates the precipitation to $CaCO_3$, particularly much faster at higher temperature.

• Korean Journal of Materials Research
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• v.33 no.9
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• pp.367-371
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• 2023

In this study we examine variations in the structure of perovskite compounds of LaBa₂Cu₂O₉, LaBa2₂CaCu₃O₁₂ and LaBa₂Ca₂Cu₅O₁₅ synthesized using the solid state reaction method. The samples' compositions were assessed using X-ray fluorescence (XRF) analysis. The La: Ba: Ca: Cu ratios for samples LaBa₂Cu₂O₉, LaBa2₂CaCu₃O₁₂ and LaBa₂Ca₂Cu₅O₁₅ were found by XRF analysis to be around 1:2:0:2, 1:2:1:3, and 1:2:2:5, respectively. The samples' well-known structures were then analyzed using X-ray diffraction. The three samples largely consist of phases 1202, 1213, and 1225, with a trace quantity of an unknown secondary phase, based on the intensities and locations of the diffraction peaks. According to the measured parameters a, b, and c, every sample has a tetragonal symmetry structure. Each sample's mass density was observed to alter as the lead oxide content rose. Scanning electron microscope (SEM) images of the three phases revealed that different Ca-O and Cu-O layers can cause different grain sizes, characterized by elongated thin grains, without a preferred orientation.

• Journal of Nutrition and Health
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• v.36 no.9
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• pp.942-949
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• 2003

This study was longitudinally conducted to evaluate the intakes of protein, Ca, Mg and P of exclusively breast-fed infants compared with the Recommended Dietary Allowances (RDA) for Korean infants. Twenty Korean lactating women and their infants during the first 3 months of lactation in Incheon area were participated. Protein, Ca and Mg, and P contents in the milk were determined using semimicro Kjeldahl (N ${\times}$ 6.38) , atomic absorption spectrophotometer and colorimeter, respectively, and also the milk consumption of the infants was measured by the test-weighing method. Protein contents of the milk were 1.96, 1.63, 1.51, 1.25 and 1.16 g/100 ml, and protein intakes of the breast-fed infants were 9.00, 9.85, 9.17, 8.97 and 7.76 g/day at 7, 15, 30, 60 and 90 days postpartum. The average protein intake per body weight of the breast-fed infants was 1.84 g/kg/day. The average intakes of Ca, Mg, P were 172.1 mg/day, 15.2 mg/day and 91.4 mg/day, respectively, and the average Ca/P ratio was 1.91. There was positive correlation between protein and Ca, protein and p, and Ca and P contents while negative correlation between Mg and P, The body weight of breast-fed infants increased normally from 3.6 $\pm$ 0.41 g at birth to three month during lactation. It is suggested that the breast-fed infants in Incheon area consume almost adequately protein, Ca and P from the milk compared with RDA for Korean infants.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1995.11a
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• pp.29-33
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• 1995

The ($Ba_{0.85}Ca_{0.15}$)$TiO_3$-Zndielectrics was made by ZnO mol ratio from 0.1 to 0.4. The characteristics of structural was analyzed by SEM and XRD and the insulating properties was examined by dielectric constant and resistivity. The grain size were 1.3[$\mu\textrm{m}$] and those shape ware a rectangular. The relativity density were over 90[%] in all specimen. It was found that the best insulating characteristics were obtained for 0.3 mol ratio.

• Applied Chemistry for Engineering
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• v.30 no.1
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• pp.43-48
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• 2019

This study investigated the feasibility of $CaSnO_3$ particles as an oxygen carrier in chemical looping combustion (CLC). $CaSnO_3$ particles had a perovskite crystal structure and showed the structural stability after repeated reduction-oxidation reactions. The oxygen transfer capacity was 15.4 wt% almost the same as the calculated theoretical value from the crystal structure transformation during reduction. After $10^{th}$ cycles of reduction and oxidation, the oxygen transfer capacity and rate were still maintained constantly at an operating temperature. In conclusion, $CaSnO_3$ particles could be a good alternative material as an oxygen carrier in CLC.

• Journal of Applied Tourism Food and Beverage Management and Research
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• v.9
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• pp.15-32
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• 1998

This experiment was carried out to evaluated biological availability of calcium inthe sea mustard, sea tangle and sea lettuce in the rats. Standard diets were made to supply 0.3% of Ca from CaCO3. Consequently, levels each test ingredients to be added were sets by their Cacontents. The ingredients such as sea mustard, sea tangle and sea lettuce wereadded to basal diet at levels of 15.23%, 12.66% and 23.42% respectively. Ingredients of the basal diet were soybean protein, corn oil, alpha-cellulose, methionine, choline cholride and vitamin and mineral premix. Dextrose was added at level up to 100%. Amount of soybean protein was adjustable to make all the diets isontrogenous. Rats were fed ad libitum the diets for 13 days. The results were summarized as follow: 1. Serum calcium levels of the sea mustard group(15.23%) were higher than those of the other group, but rats fed sea lettuce diets appeared to have the lowest value. 2. Ca concentration in tibia were lower in rats fed with sea lettuce, rather than in those with standard diet. 3. Ca concentration in femur of the rats fed seaweeds did not show any significant difference among groups. 4. In the liver weight in groups fed on the all experimental groups were decreased more than that in the case of the standard diet groups.