• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2468-2473
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• 2009

In this paper, a quadrafilar antenna is designed to have a lower profile as an essential part of the size reduction technique and lower backradiation(namely, higher forward radiation) for the S-band telemetry/telecommand(TM/TC) function of a communication satellite. Particularly, to meet the challenging requirements on the higher isolation between the TM/TC antennas and simultaneously a smaller size, the lowest backradiation and lowest cross-polarization, the optimal physical dimensions of the quadrafilar antenna are found by using the Genetic Algorithm(GA). To prove the validity of the proposed antenna design, its 3D electromagnetic analysis and measured results are compared to show good agreement. Using this antenna as the elements, an array antenna is made to have directivity.

• Proceedings of the KOSOMBE Conference
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• v.1997 no.05
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• pp.366-369
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• 1997

In this study, we measured upper right, lower right, upper left region to find the optimal region which represent liver function. We found that the upper right region is optimal because of high accuracy and low standard deviation. For normal subjects all the calculated HEFs were greater than 100% and all those of abnormal ones were less than 80%. Thus HEF can be assumed to discriminate abnormal livers from normal ones. It was found that the patients with surgical operation would survive if both the pre-and the post-operative HEFs are greater than 50%. Therefore HEF method can be a good estimator for surgeon to determine the surgical operation and to evaluate remaining hepatic function after surgery as well as it is reliable and simple.

• Nuclear Engineering and Technology
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• v.34 no.6
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• pp.533-544
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• 2002

The neutron induced nuclear data for Mo-95, Tc-99, Ru-101 and Rh-103 was calculated and evaluated in the fast energy region. The energy dependent optical model potential parameters were extracted based on the recent experimental data and applied up to 20 MeV. The s-wave strength function was calculated from the parameters. Spherical optical model, statistical model in equilibrium energy, multistep direct and multistep compound model in pre-equilibrium energy and direct capture model were used in the calculation. The theoretically calculated cross sections were compared with the experimental data and the evaluated files The model- calculated total and capture cross sections were in good agreement with the reference experimental data. The direct capture contribution improved the capture cross sections in pre- equilibrium region. The evaluated cross section results were compiled to ENDF-6 format and will improve the ENDF/B-Vl.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1992.05a
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• pp.133-136
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• 1992

Electrical resistivity and piezoelectric properties were investigated in Lead Zirconate-Titante(PZT) with Nb$_2$O$\sub$5/dopant, fabricated from conventional mixed-oxide powders and molten salt synthesis. The resistivity and electromechanical coupling factor(K$\sub$p/) were increased with increasing Nb content. The reason for increasing of the electrical resistivity below the Curie Temperature(TC). It is believed that the Curie Temperature(Tc). It is believed that the p-type electrical conduction in PZT is due to lead vacancies. The electromechanical coupling factor(K$\sub$p/) and piezoelectric constant d$\sub$33/ were improved. This behavior can be explained as a compensation effect and Nb$\^$5+/ can serve as a donar and contribute electrons to the conduction process. As a result, the optimized Nb$_2$O$\sub$5/ dopants on the PZT specimens were 0.75 wt%.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.7 no.1
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• pp.50-55
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• 2021

Low-dose radiotherapy has been known to have anti-inflammatory activity and been used for treatment of pneumonia together with anti-serum and sulfanilamide. However, it rapidly discontinued after the development of various antibiotics showing outstanding effect. Recently, it was re-considered to treat COVID-19 which has very limited treatment such as remdesivir and dexamethasone. So, several studies of COVID-19 therapy using low-dose radiation were reported very recently. They showed that low-dose radiation of 0.5~1.5 Gy were useful for decreasing the oxygen consumption and hospitalization period of COVID-19 patients without adverse reaction. Radiopharmaceuticals such as [⁹⁹mTc]Tc-macroaggregated albumin (MAA) also might be used for low-dose radiotherapy. Administration of vitamin D having anti-inflammatory effect would also be helpful for therapy with synergistic effect.

• Applied Chemistry for Engineering
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• v.25 no.5
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• pp.463-467
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• 2014

In this paper, the thermal behaviors of expanded graphite(EG)/erythritol composites with different contents of EG were studied. The surface and structure properties of the composites were determined by using scanning electron microscope (SEM), transmission electron microscope (TEM), and X-ray diffraction (XRD), respectively. The thermal properties were investigated by differential scanning calorimetry (DSC) and thermal conductivity (TC). As experimental results, the thermal conductivity of the composites increased with increasing the EG content. However, the latent heat was somewhat decreased in the presence of EG. We could concluded that EG was highly promising materials for improving the heat transfer enhancement and energy storage capacity of phase change materials (PCMs).

• The Korean Journal of Nuclear Medicine
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• v.20 no.2
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• pp.19-38
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• 1986

54 patients who had symptoms after biliary operation were studied by $^{99m}Tc-DISIDA$ hepatobiliary scintigraphy for evaluation of clinical utility, with regional emphasis of recurrent pyogenic cholangitis (RPC) and intrahepatic stones. As expected, the most common disease was recurrent pyogenic cholangitis regardless of surgical anastomosis, 58% and next frequent disease was clonorhis sinensis infestation, 26%, stenosis of ampula vater 8%, and chronic hepatitis 4% (20% of patients had hepatitis but they showed clinically and scintigraphically dominallt combined disease feature). 87% of recurrent pyogenic cholangitis was associated with stones in intra or/and extrahepatic ducts and only 11.4% of RPC was found to be associated with Cs-infestation. The scintigraphic diagnosis of RPC was 81.6% and 78.6% of stones was detected by indirect visualization of scintigraphy findings and 71.7% of Cs-infestation was detected by scintigraphy. The characteristic bile flow pattern were described.

• The Korean Journal of Nuclear Medicine
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• v.37 no.2
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• pp.83-93
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• 2003

Background: Lung-to-heart uptake ratio (LHR) in $^{201}Tl-chloride$ myocardial perfusion scan is believed to be a reliable marker for left ventricular (LV) dysfunction, but the clinical value of LHR is controversial for $^{99m}Tc-MIBI$ imaging. Furthermore, most of results suggesting lung uptake of $^{99m}Tc-MIBI$ as a potential marker for LV dysfunction used immediate post-stress images, instead of routine images acquired 1 hour after tracer injection. The goal of our study was to investigate whether LHR evaluated with routine gated $^{99m}Tc-MIBI$ imaging can reflect the degree of perfusion defect or left ventricular performance. Subjects and Methods: 241 patients underwent exercise $^{99m}Tc-MIBI$ myocardial SPECT were classified into normal myocardial perfusion (NP, n=135) and abnormal myocardial perfusion (AP, n=106) group according to the presence of perfusion defect. LHR was calculated from anterior projection image taken at 1-hour after injection. Two legions of interest (ROIs) were placed on left lung above LV and on myocardium showing the highest radioactivity. Subjects were classified by left ventricular ejection fraction (LVEF), as Gr-I: >50%, Gr-II: 36-50%, Gr-III: <36% and by summed stress score (SSS), as Gr-A: <4, Gr-B: 4-8, Gr-C: 9-13, Gr-D: >13, LHR was compared among these groups. Results: In NP group(n=135), LHR, were higher in men than women ($men:\;0.311{\pm}0.03,\;women:\;0.296{\pm}0.03,\;p<0.05$). Significant difference, in LHR were found between NP and AP groups both for men and women ($men:\;0.311{\pm}0.03\;vs\;.\;0.331{\pm}0.06,\;women:\;0.296{\pm}0.03\;vs.\;0.321{\pm}0.07.\;p<0.05$). There were weak negative correlation between LHR and LVEF (r=-0.342, p<0.05) and weak positive correlation between LHR and SSS (r=0.478, p<0.05) in men, but not in women (LVEF: r=-0.279, p=0.100, SSS: r=0.276, p=0.103). Increased LHR was defined when for more than mean + 2SD value ($men{\geq}0.38,\;women{\geq}0.37$) of the LHR of the subject with normal perfusion. Increased LHR were observed more frequently in subjects with lower LVEF (Gr-I: 11.1%, Gr-II: 27.0%, Gr-III: 35.4%, p<0.05) and higher SSS(Gr-A: 14.0%, Gr-B: 5.7%, Gr-C: 18.2%, Gr-D: 40.7%, p<0.05). Conclusions: LHRs obtained from routine $^{99m}Tc-MIBI$ gated SPECT images were weakly correlated with LVEF and perfusion defect. Although significant overlaps were observed between normal and abnormal perfusion group, LHRs could be used as an indirect marker of severe perfusion defect or reduced left ventricular function.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.1
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• pp.20-33
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• 2002

Usage of ATM AAL2 packets becomes dominant to increase transmission efficiency of voice traffic in the backbone network. In case of voice service that uses AAL2 mechanism, if resources of network are enough, connection of new call is accepted. However, due to packets generated by the new call, transmission delay of packets from old calls can increase sharply. To control this behavior, in this paper we present an AAL2 buffer management scheme that allocates a virtual buffer to each call and after calculating its propagation delay variation(PDV), decides to drop packets coming from each call according to the PDV value. We show that this packet dropping algorithm can effectively prevent abrupt QoS degradation of old calls. To do this, we analyze AAL2 packet composition process to find a critical factor in the process that influences the end-to-end delay behavior and model the process by K-policy M/D/1 queueing system and MIN(K, Tc)-policy M/D/1 queueing system. From the mathematical model, we derive the probability generating function of AAL2 packets in the buffer and mean waiting time of packets in the AAL2 buffer. Analytical results show that the AAL2 packet dropping algorithm can provide stable AAL2 packetization delay and ATM cell generation time even if the number of voice sources increases dramatically. Finally we compare the analytical result to simulation data obtained by using the COMNET Ⅲ package.

• Journal of the Health Care and Life Science
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• v.9 no.1
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• pp.161-167
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• 2021

The present study was conducted to assess the association between serum ferritin and 25-hydroxyvitamin D [25(OH)D] and metabolic syndrome (MetS) in Korean women. The data of a total of 9,256 adults (4,196 premenopausal women and 4,340 postmenopausal women) aged ≥ 20 years from the Fifth Korean National Health and Nutrition Examination Survey (KNHANES V) (2010-2012) were analyzed. The key study results were as follows: First, in women without MetS, after adjusting for related variables (age, smoking, alcohol consumption, regular exercise, SBP, DBP, WM, TC, TGs, HDL-C, FPG, Hb, Hct, and Fe), vitamin D status was positively associated with serum ferritin levels (premenopausal, p < 0.001; postmenopausal, p = 0.027). Second, in women with MetS, after adjusting for related variables, vitamin D status was not associated with serum ferritin levels (premenopausal, p = 0.739; postmenopausal, p = 0.278). In conclusions, vitamin D status was positively associated with serum ferritin levels in women without MetS but not in women with MetS.