• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.385-394
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• 2021

In this paper, a new equation of electromagnetic wave transmission matrix was proposed to calculate the reflected power and transmitted power for the multi-layered planar lossy structure. The applied human leg was modeled as a four-layer planar structure of skin, fat, muscle and bone. The complex dielectric constant to consider the loss of each of these layers was calculated using the 4-pole cole-cole model parameter. When electromagnetic waves were incident on the skin surface, total reflected and transmitted power, and human body loss were calculated for a frequency band of 0.1 to 20.0 GHz. And for various muscle thicknesses, the power reflected only from the outermost bone and re-radiated from the skin was calculated. It was confirmed that at the muscle thickness of 3.0 mm and the frequency of 4.6 GHz the return loss was -6.13 dB, which was 3.42 dB lower than the average value.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.22 no.5
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• pp.87-92
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• 2022

In this paper, a study was conducted on the design of an array element that can be applied to the AESA radar for seeker. An antenna for application to AESA radar should choose an optimal radiation element to be applied to an array antenna in order to secure electronical beam steering characteristics, and consider beam steering characteristics when designing. In particular, in order to satisfy the wide-angle beam steering characteristics, the wide-angle impedance matching technique should be used to minimize the scan blindness region that may occur during wide-angle steering. As such, securing the stability of system operation is becoming an important design consideration for AESA radar. In this paper, WAIM is applied to the end of the radiation element to improve the characteristics of the radiation element applied to the AESA radar antenna device, and the change in the performance of the active reflection coefficient, which is a stable operation index of the system, is reviewed. The final performance result verified the validity of the proposed method by mathematically synthesizing the simulation data.

• Clinical Pain
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• v.20 no.2
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• pp.135-140
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• 2021

MiraDry^®, a microwave thermolysis device, is comparably new non-surgical agent in the field of eradication of sweat glands for treating axillary hyperhidrosis and osmidrosis. So far, altered sensation, swelling, and compensatory sweating are widely known as adverse effects of MiraDry^®. Of the few reported MiraDry^®-induced neuropathy cases, median and ulnar neuropathies are common. Although, one case has described radial nerve and posterior cord damage with maximized stimulation intensity, musculocutaneous nerve damage induced by MiraDry^® has not been reported. Here, we report a case of a 30-year-old woman experiencing left hand weakness after receiving MiraDry^® at a local dermatology clinic. Left brachial plexopathy, mainly involving the median nerve and the musculocutaneous nerve with partial axonotmesis, was confirmed by electrodiagnostic studies. Ultrasound evaluation showed corresponding results. This is the first case report of the musculocutaneous neuropathy by MiraDry^®.

• Korean Journal of Radiology
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• v.25 no.9
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• pp.773-787
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• 2024

Local ablation for hepatocellular carcinoma (HCC), a non-surgical option that directly targets and destroys tumor cells, has advanced significantly since the 1990s. Therapies with different energy sources, such as radiofrequency ablation, microwave ablation, and cryoablation, employ different mechanisms to induce tumor necrosis. The precision, safety, and effectiveness of these therapies have increased with advances in guiding technologies and device improvements. Consequently, local ablation has become the first-line treatment for early-stage HCC. The lack of organized evidence and expert opinions regarding patient selection, pre-procedure preparation, procedural methods, swift post-treatment evaluation, and follow-up has resulted in clinicians following varied practices. Therefore, an expert consensus-based practical recommendation for local ablation was developed by a group of experts in radiology and hepatology from the Research Committee of the Korean Liver Cancer Association in collaboration with the Korean Society of Image-guided Tumor Ablation to provide useful information and guidance for performing local ablation and for the pre- and post-treatment management of patients.

• Clean Technology
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• v.20 no.4
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• pp.415-424
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• 2014

In this study, two kinds of polymer (PPQX-2hdPTZ (P1), POPQX-2hdPTZ (P2)) were synthesised by Suzuki coupling reaction based on phenothiazine derivative as electron-donor and quinoxaline derivative as electron-acceptor. Microwave synthesis workstation was used to shorten the polymerization time and increase the degree of polymerization. The physical, thermal stability, optical and electrochemical properties of the synthesized polymer were confirmed. The thermal stability of two polymers was outstanding as the initial decomposition temperature was $323-328^{\circ}C$. And additional substituted alkoxy chain on P2 showed higher degree of polymerization. An analysis of electrochemical properties, all polymer had similar HOMO energy level values. Device was fabricated by ITO/PEDOT:PSS/active layer/$BaF_2$/Al structure and photovoltaic properties were confirmed. Each device has a different film thickness and the resulting change in PCE was confirmed. As a result the thinner thickness of the film showed a high efficiency ($PCE_{max}:P1=1.0%$, P2 = 1.1%).

• Korean Journal of Environmental Agriculture
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• v.34 no.4
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• pp.336-344
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• 2015

BACKGROUND: This study was carried out to collect occurrence data on aluminum in 12 type agricultural products and assess dietary exposure risk to the Korean population health for aluminum concentration in agricultural products.METHODS AND RESULTS: Aluminum analysis samples were performed using microwave device and Inductively Coupled Plasma Optical Emission Spectrometer. The LOD(Limit of Detection) for aluminum was 0.851 μg/kg, while the LOQ(Limit of Quantitation) was 2.838 μg/kg and recovery was 97.6% for aluminum. The average levels of aluminum in mg/kg were 0.526 for rice, 0.546 for Korean cabbage, 1.316 for corn, 6.207 for soybean, 0.549 for sweet potato, 0.257 for potato, 6.963 for spinach, 1.213 for carrot, 0.524 for garlic, 0.950 for radish, 1.015 for leek, and 3.511 for Welsh onion. The dietary exposures of aluminum through usual intake were polished rice 89.31 μg/day, Korean cabbage 33.14 μg/day, corn 0.66 μg/day, soybean 3.72 μg/day, sweet potato 6.86 μg/day, potato 4.96 μg/day, spinach 45.96 μg/day, carrot 6.79 μg/day, garlic 2.36 μ g/day, radish 7.32 μg/day, leek 2.23 μg/day and Welsh onion 43.89 μg/day, taking 0.57%, 0.21%, 0.00%, 0.02%, 0.04%, 0.03%, 0.04%, 0.04%, 0.02%, 0.05%, 0.01% and 0.28% of PTWI(2 mg/kg b.w./week), respectively.CONCLUSION: The levels of overall dietary exposure to aluminum for Korean population through intake of agricultural product was far below the recommended JECFA level, indicating of least possibility of risk.

• Food Science of Animal Resources
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• v.33 no.5
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• pp.617-625
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• 2013

The present study was carried out to assess dietary exposure and risk for the infant population by lead (Pb), cadmium (Cd), and arsenic (As) exposure through modified milk powder and formulas. Analysis of heavy metals was performed using a microwave device and inductively coupled plasma-mass spectrometry, the method for which was fully validated. Various samples (n=204), including modified milk powder, modified milk, follow-up modified milk powder, infant formula and follow- up formula, were collected from retail outlets and markets across Korea. The mean contents of heavy metals were Pb 0.0004 (modified milk)-0.010 (infant formula) mg/kg, Cd 0.002 (modified milk)-0.007 (follow-up formula) mg/kg, and As 0.004(modified milk)-0.040 (infant formula) mg/kg, respectively. For risk assessment, daily intakes of heavy metals through maximum intake of modified milk powder and formulas were calculated and compared with reference doses established by JECFA and WHO. The dietary exposures of heavy metals were $0.78-1.04{\mu}g$ Pb/d, $0.65-0.87{\mu}g$ Cd/d, and $2.25-3.00{\mu}g$ As/d, corresponding to 2.0-4.5%, 7.1-16.0%, and 0.4-0.9% of reference doses, respectively. Therefore, the level of overall dietary exposure to heavy metals for Korean infant through food intake was below 20% of the reference dose, indicating a low risk to infant consumers.

• Korean Journal of Optics and Photonics
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• v.15 no.4
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• pp.375-384
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• 2004

Switching phenomenon of a three-waveguide optical coupler was analyzed by using the coupled mode theory, and the coupling-length of the device was calculated by means of the FDM. CPW traveling-wave electrodes were designed by the CMM and SOR simulation techniques so as to satisfy the conditions of phase-velocity and impedance matching. Traveling-wave modulators were fabricated on a z-cut LiNbO$_3$ substrate. Ti was in-diffused in LiNbO$_3$ to make waveguides and Au electrodes were built on the waveguides by the electroplating technique. Insertion loss and switching voltage of the optical modulator were about 4 ㏈ and 15.6V. Network analyzer was used to obtain S parameters and corresponding RF response. From the measurement, parameters of the traveling-wave electrodes were extracted as such Z$_{c}$=39.2 $\Omega$, Neff=2.48, and a0=0.0665/cm((GHz) (1/2)). The measured optical response R(w) was compared with the theoretically estimated and both responses were shown to agree well. The measurement results revealed that the ㏈ bandwidth turned out to be about 13 GHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.9
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• pp.987-994
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• 2010

In this paper, a simple and effective active load-pull method is proposed, and the method to improve the efficiency of X-band power amplifier using harmonic control circuit is presented. The proposed active load-pull system mainly consists of directional coupler, phase shifter, short circuit, and power amplifier, and allows a user to access reflection coefficients near the edge of the Smith chart($\Gamma$=1) easily. The device used in this paper is Mitsubishi's GaAs FET MGF1801, and the operating frequency of the power amplifier is 9 GHz, The amplifier had output power of 21.65 dBm and drain efficiency of 24.9 % at class-A, and had output power of 21.46 dBm and drain efficiency of 53.3 % at class-AB. Harmonic control circuit is designed only second and third harmonic components because of the bandwidth limitation of the microwave components. The drain efficiency is improved as much as 6.4 % compared with class-AB power amplifier.

• Journal of the Optical Society of Korea
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• v.19 no.6
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• pp.705-710
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• 2015

The fabrication process of thin boron-doped nanocrystalline diamond (B-NCD) microelectrodes on fused silica single mode optical fiber cladding has been investigated. The B-NCD films were deposited on the fibers using Microwave Plasma Assisted Chemical Vapor Deposition (MW PA CVD) at glass substrate temperature of 475 ℃. We have obtained homogenous, continuous and polycrystalline surface morphology with high sp³ content in B-NCD films and mean grain size in the range of 100-250 nm. The films deposited on the glass reference samples exhibit high refractive index (n=2.05 at λ=550 nm) and low extinction coefficient. Furthermore, cyclic voltammograms (CV) were recorded to determine the electrochemical window and reaction reversibility at the B-NCD fiber-based electrode. CV measurements in aqueous media consisting of 5 mM K₃[Fe(CN)₆] in 0.5 M Na₂SO₄ demonstrated a width of the electrochemical window up to 1.03 V and relatively fast kinetics expressed by a redox peak splitting below 500 mV. Moreover, thanks to high-n B-NCD overlay, the coated fibers can be also used for enhancing the sensitivity of long-period gratings (LPGs) induced in the fiber. The LPG is capable of measuring variations in refractive index of the surrounding liquid by tracing the shift in resonance appearing in the transmitted spectrum. Possible combined CV and LPG-based measurements are discussed in this work.