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A Novel Dual-Mode Dual-Band Bandpass Filter Based on a Single Ring Resonator
Youngje Sung 한국전자파학회JEES 2020 Journal of Electromagnetic Engineering and Science Vol.20 No.2
In this paper, a dual-mode bandpass filter that operates in two different bands is proposed. A circular patch with a small circular hole is set as the basic resonator, and, as the circular hole moves, the linewidth of the ring resonator becomes non-uniform. Consequently, the ring resonator is structurally asymmetric and exhibits a dual-mode characteristic. A gap is formed in the middle of the resonator, a pair of inductors and capacitors is applied to the gap, and the proposed dual-mode structure operates as a dual-band filter. The first resonant frequency f1 is determined by the inductor and capacitor values, and the second resonant frequency f2 is determined by the capacitor values. In addition, the frequency ratio (f2/f1) can be adjusted by an appropriate combination of inductor and capacitor values.
Selective a-glucosidase inhibition by the extract of Ziziphus jujuba Mill. leaf
Youngje Jo,Sujin Hwang,Seokwon Lim,Young Jin Choi 한국산업식품공학회 2017 학술대회 및 심포지엄 Vol.2017 No.11
The prevalence of chronic diseases has increased steadily over the last 20 years. The side effects of drugs used to treat chronic disease have always been a problem, owing to the need for long-term medication. Many studies have attempted to discover drugs from natural sources with fewer side effects. In this study, we investigated the possibility of using jujube leaf as a potential anti-diabetic drug source or food supplement. The IC50 values of acarbose and jujube leaf extract on a-glucosidase were 2.59 and 0.37 mg/mL, respectively. In vitro tests showed that the inhibition of a-glucosidase was maintained after the jujube extract was passed through a simulated digestive system, but no inhibition of a-amylase was observed either before or after the in vitro digestion. The jujube leaf extract showed mixed non-competitive inhibition. Jujube leaf extract is expected to be safer and cheaper than synthetic inhibitors.
Youngje, Jeong,Gyehyeong, Ahn,Gwangyong, Ko,Dohyeong, Kim 한국도로학회 2018 한국도로학회 학술대회 발표논문 초록집 Vol.2018 No.05
This study suggested a new real-time traffic signal operation algorithm using combined data of travel time and occupancy rate. This study applied the travel time data to traffic signal control system, and developed the signal operation algorithm based on saturation degree that was calculated using the travel time data. This algorithm calculates a queue length using a delay model, and converts the queue length to the saturation degree. Moreover, it calculates signal timing variables using this combined saturation degree. This study conducted a microscopic simulation for effectiveness evaluation. We checked that the average intersection delay decreased by up to 27 percent. Moreover, we checked that this signal operation algorithm could respond to a traffic condition of oversaturation and loop detector error effectively and usefully. In korea, sectional traffic detection systems are being installed in various ITS projects, such as Advanced Transportation Management System(ATMS) and Urban Transportation Information System(UTIS). This study has important significance in the sense that it is new methodology to accept the sectional detection system in traffic signal control system.
Dual-Band Circularly Polarized Stack-Ring Antenna
Youngje Sung 한국전자파학회JEES 2019 Journal of Electromagnetic Engineering and Science Vol.19 No.1
A stack-ring configuration is proposed for designing a dual-band circularly polarized (CP) antenna. Each ring generates different resonant frequencies. A good CP performance at both resonant frequencies is achieved by adjusting the relative distance between the two rings. The two operating bands are separated with a small frequency ratio of 1.07. Measured results show that radiation patterns with good CP characteristics are obtained at the two resonant frequencies.
Isolation of a Natural β-d-Glucosidase Inhibitor in Jujube Leaf Extract
Youngje Jo,Seokwon Lim,Young Jin Choi 한국산업식품공학회 2016 학술대회 및 심포지엄 Vol.2016 No.10
The glucosidase inhibitors are currently interested owing to their promising therapeutic potential in the treatment of disorders such as diabetes, human immunodeficiency virus (HIV) infection, metastatic cancer, and lysosomal storage diseases. Among them, β-d-glucosidase inhibitors can be used to elucidate the mechanisms of various biochemical reactions and to treat the Gaucher disease as potential therapeutics. In this study, the natural β-glucosidase inhibitor was isolated from jujube leaf extract. The isolation and purification are vital for the structure analysis. The jujube leaf was extracted with hot water (95°C, 15 min). Then the natural β-glucosidase inhibitor was isolated using size exclusion chromatography and semi-preparative HPLC. In the first purification process, the 35 fractions were collected according to molecular size using PD-10 column packed with Sephadex G-25 medium. The strongest inhibition on the activity of β -glucosidase was observed at 6 and 7 fractions. The chromatogram of these samples showed that 3 peaks were observed comparing with baseline. For further purification, the strongest inhibitory activity peak was isolated using semi-preparative HPLC with VDS C18 column. Highly purified inhibitor, which can be used for structure analysis and characterization, was obtained. Further study is necessary to identify the natural β-glucosidase inhibitor in the jujube leaf extract.
Circularly Polarized Square Ring Slot Antenna with Arrow-Shaped Structure
Youngje Sung 한국전자통신연구원 2009 ETRI Journal Vol.31 No.5
A novel design of a compact square-ring slot microstrip antenna for achieving circular polarization (CP) operation is proposed and experimentally studied. By using an arrow-shaped slot structure as a radiating element, the resonant frequency of the proposed antenna is significantly lowered, which can lead to a large size reduction for fixed frequency operation. The CP radiation characteristics are achieved by loading with proper asymmetry, which can be placed diagonally. A prototype of the proposed design is implemented and its performance is measured. Measured results show that radiation patterns with good CP characteristics are obtained at the resonant frequency.
A Switchable Microstrip Patch Antenna for Dual Frequency Operation
Youngje Sung 한국전자통신연구원 2008 ETRI Journal Vol.30 No.4
A novel design for equilateral-triangular microstrip antennas with switchable resonant frequency is proposed. For dual-frequency operation, the proposed design is achieved by loading a pair of slits in the triangular patch, and two PIN diodes are utilized to switch the slits on or off. By increasing the length of the slits, the lower resonant frequency can be varied in the range from 1.22 GHz to 1.72 GHz whereas the upper resonant frequency remains unchanged.
A Corner-Fed Microstrip Circular Antenna with Switchable Polarization
Youngje Sung 한국전자통신연구원 2008 ETRI Journal Vol.30 No.5
In this paper, a design for a novel microstrip antenna with circular polarization diversity is proposed and experimentally investigated. This antenna is excited by a microstrip line, which is located at the corner of a circular patch. The polarization state can be switched electrically by setting a diode to on or off. The novel structure we describe here enables the optimization of the input match for both polarizations. From the measured result, good axial ratios are observed at the operating frequencies.
A Polarization Diversity Patch Antenna with a Reconfigurable Feeding Network
Youngje Sung,Sung Woo Lee 한국전자파학회JEES 2015 Journal of Electromagnetic Engineering and Science Vol.15 No.2
This paper proposes a reconfigurable square-patch antenna with polarization diversity. The proposed antenna consists of a square radiating patch and a Y-shaped feed structure with two PIN diodes. The shape of the feed structure can be changed by adjusting the bias states of the two PIN diodes, which helps switch between two orthogonal linear polarizations. The polarization diversity characteristic is validated by the simulated current distribution and the measured radiation pattern.