• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.9
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• pp.1039-1046
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• 2007

In this paper, a coupled-defected ground structure(C-DGS) using negative inductive coupling is proposed and a bandstop filter(BSF) using C-DGS is designed and fabricated. The proposed C-DGS is the closely-located DGS cells for the negative coupling, the negative coupling of ground currents between adjacent DGS cells greatly improves the stopband characteristics. The proposed BSF utilizing the sharp cutoff response of the C-DGS has a -10 dB rejection band from 4 GHz to 11.3 GHz. A maximum attenuation rate is -64.3 dB/GHz in 3 cell structure, -108 dB/GHz in 5 cell structure. The C-DGS BSF shows the improved attenuation rate 3.8 times in 3 cell structure, 2.4 times in 5 cell structure, Also, the C-DGS BSF is reduced to 35.2 % and 40 % of the DGS BSF, respectively, due to the closely-located DGS cells. We fabricated the single gate mixer using C-DGS BSF. The single gate mixer has 6.6 dB conversion gain.

• Journal of Advanced Navigation Technology
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• v.18 no.1
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• pp.35-43
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• 2014

In this paper, it is about to non-contact wireless power transmission according to various conditions of self induction principle between the two planar coils at a transmission unit and a receiving unit based on the theory of wireless power transmission. The experiments are occurred in order to power transfer of noncontact method from designed wireless circuits in the primely coil and secondary coil, and the applying to Half Bridge Resonant converter transmission unit and receiving unit. and that were able to prepared circumstance to calculate of the output voltage and power source. The main power of the inductive coupling the resonant converter at the transmission unit is converted electrical energy using the solar cell module and artificial light source (halogen lamp) as a replace light and received 24 V power supply from solar power was used a input power source for the wireless power transmission device. Experimental results, to received of power is used to illuminate the lighting and to charge the battery in receiving circuit.And the wireless power transmission efficiency measured at the output side of the transmission unit is obtained about 70% to 89% compared to input power of receiving unit.In addition, efficiency were tested through ID verification method and comparing the phase difference between the voltage when foreign substances interfere with wireless power transmission.

• Journal of Periodontal and Implant Science
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• v.34 no.3
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• pp.551-562
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• 2004

The purpose of this study was to evaluate the effects of negatively electric field on bone healing in rabbit segmental long bone defects using negatively charged PTFE membrane. Ten millimeter segmental defects in the rabbit radius were used as the experimental model. After membranes were then charge injected using a corona-charging apparatus, the left defects were covered with non charged PTFE membranes as control groups, whereas the right defect was covered with negatively charged PTFE membranes as test group. The animals were divided into 4 groups of 2 rabbits each, and sacrificed at 2, 4, 6, and 8 weeks. Histomorphometric analysis showed a more newly formed bone in negatively charged membrane at early healing period. At 2 weeks, the proportion of new bone formation to total defect area was 0.32% in control group, 1.10% in experimental group. At 4 weeks, the proportion of new bone formation to total defect area was 6.86% in control, and 13.75% in experimental. At 6 and 8 weeks, no obvious difference was found between the two groups but newly formed bone in test groups were slightly more than that in control groups. In conclusion, negatively charged membranes showed more newly bone tissue than noncharged membranes at an early healing period. Although the number of samples was small, this study showed that the combination of negatively electrical stimulation and P1FE membrane may be of value in long bone healing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.401-406
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• 2016

When measuring live cable faults and their location based on reflectometry, a coupler is placed between the cable and the test system. This coupler prevents damage to the test circuits by indirectly measuring the live voltage of the cable using reflectometry. It also provides a coupling path that allows the transmission and receive signal to pass into the cable. In this study, we design and construct a contact coupler to locate faults in both dead and live cables using reflectometry. The proposed coupler is of the inductive coupling type and is constructed after the calculation of the signal transmission loss by simulation. The performance of the developed coupler is tested by measuring the transmission loss and frequency flatness. The results showed that the transmission signal loss is less than -1.98dB in the frequency bandwidth above 1 Mhz. The reflectometry system was designed based on sequence time domain reflectometry (STDR) and spread spectrum time domain reflectometry (SSTDR) in order to apply it to the detection of faults and their location in live cables and tests on live cables were performed. The test results showed that the proposed coupler can be used in a reflectometry system for live cable fault detection.

• Bulletin of the Korean Chemical Society
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• v.29 no.6
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• pp.1233-1242
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• 2008

The hydration effect on the intrinsic magnetism of natural salmon double-strand DNA was explored using electron magnetic resonance (EMR) spectroscopy and superconducting quantum interference device (SQUID) magnetic measurements. We learned from this study that the magnetic properties of DNA are roughly classified into two distinct groups depending on their water content: One group is of higher water content in the range of 2.6-24 water molecules per nucleotide (wpn), where all the EMR parameters and SQUID susceptibilities are dominated by spin species experiencing quasi one-dimensional diffusive motion and are independent of the water content. The other group is of lower water content in the range of 1.4-0.5 wpn. In this group, the magnetic properties are most probably dominated by cyclotron motion of spin species along the helical π -way, which is possible when the momentum scattering time (${\tau}_k$) is long enough not only to satisfy the cyclotron resonance condition (${\omega}_c{\tau}_k$ > 1) but also to induce a constructive interference between the neighboring double helices. The same effect is reflected in the S-shaped magnetization-magnetic field strength (M-H) curves superimposed with the linear background obtained by SQUID measurements, which leads to larger susceptibilities at 1000 G when compared with the values at 10,000 G. In particular, we propose that the spin-orbital coupling and Faraday's mutual inductive effect can be utilized to interpret the dimensional crossover of spin motions from quasi 1D in the hydrate state to 3D in the dry state of dsDNA.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.1
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• pp.253-259
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• 2015

In this paper, we propose a transformer of alternating voltage source utilizing a semiconductor, operating in bidirectional fashion. Transformer is a device transferring energy by inductive coupling between its winding circuits. Conventional transformer is a device, composed of a primary coil and a secondary coil, transforming an alternating voltage. The system we propose is designed with a single circuit transforming the level of voltage signal in two ways; from the source to the load, and vice versa. For semiconductor switches, the NPN transistor is connected to the alternating voltage source terminal, and emitter terminal is connected to the inductor in the system as an energy storage element. The control signal is applied to the base terminal of the semiconductors. We have shown that the system we propose, by adopting only one circuit, drives an alternating voltage transformer that changes the amplitudes of voltage signal in reciprocal way.

• Journal of Astronomy and Space Sciences
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• v.24 no.4
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• pp.397-408
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• 2007

Diplexer is one of core devices needed to communicate with satellite using single ground antenna by separating uplink and downlink signal. This paper presents the design of the S-band diplexer for LEO TT&C application, especially for KOMPSAT (KOrea Multi-Purpose SATellite). To cope with requirements such as high handling power, low insertion loss, air-cavity resonator with high quality factor was considered as one of design drivers. Design was started with predicting unloaded Q and equivalent circuit from the structure of air-cavity resonator. For the convenience of adjustment, the coupling factor placed between resonators was estimated from COTSEM (Electro-Magnetic) simulator, EESOF $ADS^{TM}$, and expressed with 2-order polynomial regression. To improve the isolation between transmitting part (Tx) and receiving part (Rx), the inductive and capacitive attenuation poles were inserted between $4^{th}\;and\;6^{th}$ resonator respectively. The fabricated diplexer consists of two bandpass filters and each filter has eight resonants. From the measurement, it was shown that major requirements such as 0.5dB of insertion loss, 20dB of return loss and 100dB of isolation were fully satisfied within passband.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.11 no.1
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• pp.42-47
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• 2001

The purpose of this study was to investigate for filtration efficiency of several dust masks, comparing with filtration efficiency certified by KOSHA(Korea Occupational Safety & Health Agency), and to require of the right use of protective respirators. Using a welding fume generator and chamber, several dust masks, which were widely used in the workplaces in korea, were tested for their filtering efficiency for stainless steel arc welding fume. The filtration efficiency testing system consisted of a welding fume generator, a chamber and a filtration unit. The filtration unit was made of a mask which was inserted into the sampling cassette and another sampling cassette, which contained mixed cellulose ester filter paper. These two cassettes were connected with tubing. Stainless steel arc welding fume generator was delivered into an chamber. The welding fume in the chamber was passed into the filtration unit with flow rate of 30 liter/min. The welding fume filtration efficiency was evaluated by gravimetric measurement. Metal concentrations in the welding fume before and after filtration were measured with inductive coupling plasma analyzer. Following results were obtained: Filtration efficiency of welding fume for common hygienic mask was 63.82% and the average efficiencies for A, B, C, D, E, F and G masks were 94.62%, 96.58%, 83.20%, 82.76%, 77.25%, 86.55% and 93.22%, respectively. Our results indicate that dust masks used widely in the welding workplaces in korea are not proper for protecting worker's health and then the use of fume mask should be required.

• Journal of Biomedical Engineering Research
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• v.37 no.5
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• pp.168-177
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• 2016

In this paper we present an implantable pressure sensor to measure real-time blood pressure by monitoring mechanical movement of artery. Sensor is composed of inductors (L) and capacitors (C) which are formed by microfabrication and direct bonding on two biocompatible substrates (quartz). When electrical potential is applied to the sensor, the inductors and capacitors generates a LC resonance circuit and produce characteristic resonant frequencies. Real-time variation of the resonant frequency is monitored by an external measurement system using inductive coupling. Structural and electrical simulation was performed by Computer Aided Engineering (CAE) programs, ANSYS and HFSS, to optimize geometry of sensor. Ultrafast laser (femto-second) cutting and MEMS process were executed as sensor fabrication methods with consideration of brittleness of the substrate and small radial artery size. After whole fabrication processes, we got sensors of $3mm{\times}15mm{\times}0.5mm$. Resonant frequency of the sensor was around 90 MHz at atmosphere (760 mmHg), and the sensor has good linearity without any hysteresis. Longterm (5 years) stability of the sensor was verified by thermal acceleration testing with Arrhenius model. Moreover, in-vitro cytotoxicity test was done to show biocompatiblity of the sensor and validation of real-time blood pressure measurement was verified with animal test by implant of the sensor. By integration with development of external interrogation system, the proposed sensor system will be a promising method to measure real-time blood pressure.

• Journal of Advanced Navigation Technology
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• v.19 no.3
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• pp.237-243
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• 2015

This paper presented the design of wireless power transfer (WPT) system using electromagnetic induction techniques and analysed WPT efficiency. Also, we presented the optimum coil condition by measuring the efficiency variation according to some receiving coil parameter changes. Voltage change is measured by receiving coil position for the designed transmitting and receiving circuit. Voltage change according to inductance variation at the same position and charging time are compared at the same environment by using a developed application program to realize an optimum WPT system. Developed wireless power transfer system using electromagnetic induction techniques uses 125 kHz. It takes 16 minutes by using wired charger, and 23 minutes by using wireless charger for charging from 50% to 60% charging status.