• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.12
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• pp.933-940
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• 2017

A wireless power transfer system with a negative impedance converter(NIC) was designed and tested. The system was investigated to identify the effects of ferrites and conductors. To improve the power transfer efficiency(PTE), the Q-factor of the transmitter was enhanced by the negative resistance generated by the NIC. The NIC was composed of an Op-Amp and resistors. The negative resistance was obtained with respect to a resistor connected in a feedback loop. The dimension of the Tx coil was $250mm{\times}250mm{\times}0.8mm$. The impedance and Q-factor were $31+j1874{\Omega}$ and 60, respectively. The negative resistance was selected to be $30{\Omega}$, and the Q-factor was increased to 900 by reduction of the transmitter resistance, which was about 15 times higher than that of a conventional transmitter. The measured PTE was greatly improved in comparison to that of a conventional system. These results demonstrate that the PTE is enhanced by using the NIC.

• Journal of Korean Medicine Rehabilitation
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• v.23 no.4
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• pp.177-184
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• 2013

Objectives Lumbago is very common symptoms and many lumbago patients visited Korean Medicine clinic to cure lumbago. But It is not studied therapy type and pattern identification in lumbago patients. This study aim to survey therapy type and pattern identification in lumbago patients. Methods We collected data of 755 patients treated to cure lumbago in Korean Medicine Hospital from 1, Jan. to 31, Dec., 2012. The therapy variable are acupuncture, herbal acupuncture, physical therapy, Chuna Tx, herbal medicine, cupping and moxibustion. Demographic variable are age, gender, district, medical insurance code, and etc. Results 1) We collected data of 755 lumbago patients in 5 Korean medical Hospitals. 2) Age, district, insurance code, diseases were statistically significant by pattern identification. 3) Therapy types of lumbago patients were different by pattern identification. Conclusions In lumbago patients, therapy type and herbal medicine were different by Pattern identification. In the future, it is needed prospective and large scale database for pattern identification in lumbago patients.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.4
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• pp.466-473
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• 2013

In this paper, a compact planar multi-loop self-resonant coil of high quality factor with a coaxial cross section is proposed for effective wireless charging. The proposed coil has high Q-factor and a resonant frequency of a coil can be easily controlled by adjusting distributed capacitance. For designing the coil, a self-inductance and a distributed capacitance are calculated theoretically. The self-inductance is calculated from the sum of the mutual energies between small circular loops that are made by dividing the cross section of the coil. To verify its properties and calculation results, the self-resonant coils are fabricated by using a coaxial cable with characteristic impedance of $50{\Omega}$. The measured frequencies are very consistent with the calculated ones. In addition, the resonant frequency can be adjusted slightly by the tuning parameter ${\gamma}$. The resonant coils are applied to a tablet PC, the Q-factors of the Tx and Rx resonant coils are 282 and 135, respectively. As a result of measurement when height between the two resonant coils is 4.4 cm, the power transfer efficiency is more than 80 % within a radius of 5 cm.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.1
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• pp.19-25
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• 2008

In this paper, the front end module (FEM) was proposed for 2.4GHz WLAN band by LTCC multilayer application. The FEM was composed of power amplifier IC, switch IC, and LTCC module. LTCC module consists of output matching circuit and lowpass filter as Tx part, bandpass filter as Rx part. Design of output matching circuit for LTCC was used matching parameter from output matching circuit based on lumped circuit on the PCB board. The dielectric constant of LTCC substrate is 9. The substrate was composed of total 26 layers with each 30um thickness. Ag paste was used for the internal pattern as the conductor material. The size of the module is $4.5mm{\times}3.2mm{\times}1.4mm$. The fabricated FEM showed the gain of 21dB, ACPR of less than -31dBc first side lobe and Less than -59dBc second side lobe and the output power of 23Bm at P1dB.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.41 no.4
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• pp.55-62
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• 2004

In this paper, we have developed a portable acceleration measurement system to measure acceleration signals during walking and a gait analysis algorithm which can evaluate gait regularity and symmetry and estimate gait parameters automatically. Portable acceleration measurement system consists of a biaxial accelerometer, amplifiers, lowpass filter with cut-off frequency of 16Hz, one-chip microcontroller, EEPROM and RF(TX/RX) module. The algerian includes FFT analysis, filter processing and detection of main peaks. In order to develop the algorithm, eight hemiplegic patients for training set and the other eight hemiplegic patients for test set are participated in the experiment. Acceleration signals during 10m walking were measured at 60 samples/sec from a biaxial accelerometer mounted between L3 and L4 intervertebral area. The algorithm, detected foot contacts and classified right/left steps, and then calculated gait parameters based on these informations. Compared with video data and analysis by manual, algorithm showed good performance in detection of foot contacts and classification of right/left steps in test set perfectly. In the future, with improving the reliability and ability of the algerian so that calculate more gait Parameters accurately, this system and algerian could be used to evaluate improvement of walking ability in hemiplegic patients in clinical practice.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.4
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• pp.362-370
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• 2010

In this paper, a compact RF Front-end module for Wireless Fidelity(Wi-Fi) and Worldwide Interoperability for Microwave Access(WiMAX) applications is realized by low temperature co-fired ceramic(LTCC) technology. The RF Front-end module is composed of three LTCC band-pass filters, a Film Bulk Acoustic Resonator(FBAR) filter, fully embedded matching circuits, an SPDT switch for mode selection, an SPDT switch for Tx/Rx selection, and an SP4T switch for band selection. The parasitic elements of 0.2~0.3 pF are generated by the structure of stacking in the top pad pattern for DC block capacitor of SPDT switch for mode selection. These kinds of parasitic elements break the matching characteristic, and thus, the overall electrical performance of the module is degraded. In order to compensate it, we insert a parallel lumped-element inductor on capacitor pad pattern for DC block, so that we obtain the optimized performance of the RF Front-end module. The fabricated RF front-end module has 12 layers including three inner grounds and it occupies less than $6.0mm{\times}6.0mm{\times}0.728mm$.

• Journal of Gastric Cancer
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• v.3 no.4
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• pp.182-185
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• 2003

Purpose: Preoperative staging of gastric cancer is crucial because the treatment modality and the prognosis depend upon the stage of gastric cancer. Current treatment modalities for early gastric cancer have focused on the quality of life. Endoscopic ultrasonography (EUS) and abdominal computed tomography (CT) are commonly used diagnostic tools to evaluate the invasiveness (T stage) of the primary tumor. The purpose of this paper is to evaluate the sensitivity and the specificity of preoperative EUS and CT in comparison with postoperative pathology. Materials and Methods: From October 2001 to October 2002, EUS and abdominal CT were performed simultaneously on 75 patients who underwent radical gastric surgery for the treatment of gastric cancer. Through analyzing the clinical T stage and the pathologic T stage, We evaluated the diagnostic sensitivities and specificities of endoscopic ultrasonography and abdominal computed tomography. Results: The male-to-female sex ratio was 1 : 0.6 (males: 47, females: 28). The mean age was 55.4 years in males (range: $28\~81$) and 54.4 years in females (range: $23\∼77$). The clinical T stage based on EUS included 22 T1mm, 7 T1sm, 22 T2, and 24 T3. The clinical T stage based on CT included 20 Tx, 23 T2, and 32 T3. The permanent pathologic report confirmed 23 T1mm, 10 T1sm, 17 T2, 24 T3, and 1 T4. The sensitivity and specificity of EUS were $84.2\%\;and\;94.7\%$, respectively. However, the sensitivity and specificity of abdominal CT were $53.3\%\;and\;77.0\%$, respectively. Conclusion: Our data suggest that EUS is a very useful diagnostic tool for evaluating the T stage of gastric cancer because EUS has higher specificity than abdominal CT. Therefore, EUS may have a significant role as a preoperative diagnostic modality in patients undergoing minimally invasive surgery.

• Atmosphere
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• v.24 no.4
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• pp.541-554
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• 2014

Historical, RCP4.5 and RCP8.5 scenarios from HadGEM2-AO are dynamically downscaled over the northeast East Asia with WRFV3.4. The horizontal resolution of the produced data is 12.5 km and the periods of integration are 1979~2010 for historical and 2019~2100 for both RCP4.5 and RCP8.5. We analyze the time series, climatology, EOF and extreme climate in terms of 2 m-temperature and precipitation during 30-year for the Historical (1981~2010) and RCP4.5 and RCP8.5 (2071~2100) scenarios. According to the result, the temperature of the northeast Asia centered at the Korean Peninsula increase 2.9 and $4.6^{\circ}C$ in the RCP4.5 and RCP8.5 scenarios, respectively, by the end of the 21st century. The temperature increases with latitude and the increase is larger in winter rather than in summer. The annual mean precipitation is expected to increase by about $0.3mm\;day^{-1}$ in RCP4.5 scenario and $0.5mm\;day^{-1}$ in RCP8.5 scenario. The EOF analysis is also performed for both temperature and precipitation. For temperature, the EOF $1^{st}$ modes of all scenarios in summer and winter show that temperature increase with latitude. The $2^{nd}$ mode of EOF of each scenario shows the natural variability, exclusive of the global warming. The summer precipitation over the Korean Peninsula projected increases in EOF $1^{st}$ modes of all scenarios. For extreme climate, the increment of the number of days with daily maximum temperature above $30^{\circ}C$ per year ($DAY_{TX30}$) is 25.3 and 49.7 days in RCP4.5 and RCP8.5 respectively over the Korean Peninsula. The number of days with daily precipitation above $20mm\;day^{-1}$ per year ($DAY_{PR20}$) also increases 3.1 and 3.5 days in RCP4.5 and RCP8.5 respectively.

• Archives of Plastic Surgery
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• v.36 no.4
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• pp.432-436
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• 2009

Purpose: Negative pressure therapy has been used in various conditions to promote wound healing. It has also been used to secure a skin graft by improving microcirculation and improving tight adhesion between the graft and the recipient bed. To reduce post burn scar contracture and improve aesthetical result, many types of dermal substitutes have been invented and used widely. The goal of this study was evaluate usefulness of the VAC (Kinetic concepts Inc., San Antonio, TX) in improving the take rate and time to incorporation of Integra$^{(R)}$ in reconstruction of burn scar contracture. Methods: A retrospective study was performed from October, 2006 to December, 2008. The VAC was utilized for 11 patients. The average patient's age was 19.7 years (range 5 - 27) and average surface area was $785cm^2$ (range 24 - 1600). The burn scars were excised deep into normal subcutaneous tissue to achieve complete release of the scar, Integra$^{(R)}$ was sutured in place with skin staple와 Steri - strip$^{(R)}$. Then slit incisions were made on silicone sheet only with No.11 blade for effective drainage. The VAC was used as a bolster dressing over Integra$^{(R)}$. Negative - Pressure ranging from 100 to 125 mm Hg was applied to black polyurethane foam sponge trimmed to the appropriate wound size. An occlusive seal over the black polyurethane foam sponge was maintained by a combination of the occlusive dressing, OP - site$^{(R)}$. The VAC dressing changes were performed every 3 or 4 days until adequate incorporation was obtained. The neodermis appeared slightly yellow to orange color. When the Integra$^{(R)}$ deemed clinically incorporated, The VAC was removed and take was estimated with visual inspection. Very thin STSG(0.006 ~ 0.008 inches) was performed after silicone sheet removal. Result: The mean time for clinically assessed incorporation of Integra$^{(R)}$ was 10.00 days (range 9 - 12). The mean dressing change was 3.5 times until take was obtained. In All patients, Integra$^{(R)}$ had successful incorporation in tissue without serious complications. Conclusion: Integra$^{(R)}$ in combination with Vacuum - Assisted Closure(VAC) may be incorporated earlier than conventional dressing method.

• Korean Journal of Food Science and Technology
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• v.30 no.5
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• pp.1077-1084
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• 1998

The optimum conditions fer the measurement of texture profile of imitation crab-leg products were investigated by different conditions using Texture Analyser and the date were compared to those of sensory evaluations. The textural characteristics of surimi gels were compared with those of imitation crab-leg products. The TPA values of 5 different kinds of commercial imitation crab-leg product and 2 kinds of surimi gel products purchased in a market in Seoul were measured. In surimi gels, instrumental hardness and cohesiveness were higher than those of imitation crab-leg products, especially chewiness and gumminess were significantly higher than those of imitation crab-leg products. In imitation crab-leg products, hardness and cohesiveness increased and springiness decreased as the probe diameter increased from 12.5 mm to 24.6 mm. In the different compression ratio (60, 70, 80%), hardness increased and cohesiveness and springiness decreased as the compression ratio increased. The chewiness, gumminess, cohesiveness and hardness increased slightly as the cross-head speed increased from 0.8 to 2.4 mm/sec. Significant correlations between mechanical and sensory values were observed in gumminess, chewiness, cohesiveness and hardness. The optimum conditions for the TPA measurement of imitation crab-leg products were a cross-head speed of 2.4 mm/sec and 60% compression ratio with a flat probe having twice of the sample diameter (24.6 mm).