• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.8
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• pp.1817-1823
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• 2009

A design of cascaded distributed amplifier with a broadband amplification is described in this paper. A medium power device with 23dBm, max output power under the optimal narrow-band power matching condition is adopted for the design and fabrication of the cascaded distributed amplifier. In general, conventional distributed amplifiers with the parallel connected input ports have a low gain, and previous cascaded distributed amplifiers show a relatively low output power of 10dBm at most, which is the upper limit of small signal amplification. However, the cascaded distributed amplifier in this paper shows the gain of $18.15{\pm}0.75dB$ and output power of 20dBm over $300MHz{\sim}2GHz$ from the measurement, so it can be well adopted as a wideband driver amplifier.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.27 no.1
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• pp.87-94
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• 2023

Backgrounds/Aims: Central pancreatectomy (CP) is associated with a higher rate of postoperative pancreatic fistula (POPF), and it is less preferred over distal pancreatectomy (DP). We compared the short- and long-term outcomes between CP and DP for low-grade pancreatic neck and body tumors. Methods: This was a propensity score-matched case-control study of patients who underwent either CP or DP for low-grade pancreatic neck and body tumors from 2003 to 2020 in a tertiary care unit in southern India. Patients with a tumor >10 cm or a distal residual stump length of <4 cm were excluded. Demographics, clinical profile, intraoperative and postoperative parameters, and the long-term postoperative outcomes for exocrine and endocrine insufficiency, weight gain, and the 36-Item Short Form Survey (SF-36) quality of life questionnaire were compared. Results: Eighty-eight patients (CP: n=37 [cases], DP: n=51 [control]) were included in the unmatched group after excluding 21 patients (meeting exclusion criteria). After matching, both groups had 37 patients. The clinical and demographic profiles were comparable between the two groups. Blood loss and POPF rates were significantly higher in the CP group. However, Clavien-Dindo grades of complications were similar between the two groups (p = 0.27). At a median follow-up of 38 months (range = 187 months), exocrine sufficiency was similar between the two groups. Endocrine sufficiency, weight gain, SF-36 pain control score, and general health score were significantly better in the CP group. Conclusions: Despite equivalent clinically significant morbidities, long-term outcomes are better after CP compared to DP in low-grade pancreatic body tumors.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.694-700
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• 2009

In this paper, we propose a RFID tag antenna with low performance degradation due to nearby dielectric materials. The proposed antenna is designed to be appropriate for ink printing fabrication. The antenna is designed to operate in UHF band of $860{\sim}960$ MHz. The antenna uses a T-matching network in the middle of the main body and two parasitic patches in vicinity for complex conjugate matching with a commercial tag chip. In addition, the two parasitic patches induce currents at different dielectric constants of nearby dielectric materials. This can minimize the performance degradation due to nearby dielectric materials. The measured results show the half power matching bandwidth from 844 MHT to 1,268 MHz. It exhibits the reading distance of about 3.5 m in free space when the tag antenna is used with the commercial reader antenna (transmitting power of 20 dBm and the reader antenna gain of 6 dBi). When the tag is attached on dielectric materials of wood and FR4, the resulting reading distances are 2.61 m and 2.51 m, respectively.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.3 s.309
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• pp.25-33
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• 2006

This paper proposed device-independent color matching algorithm based on the 3D RGB lookup table (LUT) between mobile camera and mobile LCD (Liquid Crystal Display) to improve the color-fidelity. Proposed algorithm is composed of thee steps, which is device characterization, gamut mapping, 3D RGB-LUT design. First, the characterization of mobile LCD is executed using the sigmoidal function, different from conventional method such as GOG (Gain Offset Gamma) and S-curve modeling, based on the observation of electro-optical transfer function of mobile LCD. Next, mobile camera characterization is conducted by fitting the digital value of GretagColor chart captured under the daylight environment (D65) and tristimulus values (CIELAB) using the polynomial regression. However, the CIELAB values estimated by polynomial regression exceed the maximum boundary of the CIELAB color space. Therefore, these values are corrected by linear compression of the lightness and chroma. Finally, gamut mapping is used to overcome the gamut difference between mobile camera and moible LCD. To implement the real-time processing, 3D RGB-LUT is designed based on the 3D RGB-LUT and its performance is evaluated and compared with conventional method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.11A
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• pp.912-920
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• 2003

This paper is about the design of a small wide-band slot loop antenna, which consists of dual offset-fed and rectangular loop within the slot on a substrate. The proposed antenna is a novel structure generating a multi-resonances due to three geometrical resonance structures. The impedance matching of this antenna can be accomplished by changing the offset position of dual-fed at resonance frequencies. In this experiment, the slot of a fabricated antenna has a center frequency of 6.755㎓, 12.5mm${\times}$50mm in size and the rectangular loop has 10.5mm${\times}$27.5mm in size. The measured result is fractional bandwidth 63.21% with VSWR 2:1, which is agreed with the simulated result within 5% of error, and the maximum antenna gain is 7.42㏈i.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.3
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• pp.115-122
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• 2015

Global Positioning System (GPS) is used in various fields such as communications systems, transportation systems, e-commerce, power plant systems, and up to various military weapons systems recently. However, GPS receiver is vulnerable to jamming signals as the GPS signals come from the satellites located at approximately 20,000 km above the earth. For this reason, various anti-jamming techniques have been developed for military application systems especially and it is also required for commercial application systems nowadays. In this paper, we proposed a dual-channel Global Navigation Satellite System (GNSS) RF ASIC for digital pre-correlation anti-jam technique. It not only covers all GNSS frequency bands, but is integrated low-gain/attenuation mode in low-noise amplifier (LNA) without influencing in/out matching and 14-bit analogdigital converter (ADC) to have a high dynamic range. With the aid of digital processing, jamming to signal ratio is improved to 77 dB from 42 dB with proposed receiver. RF ASIC for anti-jam is fabricated on a 0.18-μm complementary metal-oxide semiconductor (CMOS) technology and consumes 1.16 W with 2.1 V (low-dropout; LDO) power supply. And the performance is evaluated by a kind of test hardware using the designed RF ASIC.

• Journal of Advanced Marine Engineering and Technology
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• v.32 no.8
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• pp.1263-1268
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• 2008

In this paper, the low noise power amplifier for GaAs FET ATF-10136 is designed and fabricated with active bias circuit and self bias circuit. To supply most suitable voltage and current, active bias circuit is designed. Active biasing offers the advantage that variations in the pinch-off voltage($V_p$) and saturated drain current($I_{DSS}$) will not necessitate a change in either the source or drain resistor value for a given bias condition. The active bias network automatically sets a gate-source voltage($V_{gs}$) for the desired drain voltage and drain current. Using resistive decoupling circuits, a signal at low frequency is dissipated by a resistor. This design method increases the stability of the LNA, suitable for input stage matching and gate source bias. The LNA is fabricated on FR-4 substrate with active and self bias circuit, and integrated in aluminum housing. As a results, the characteristics of the active and self bias circuit LNA implemented more than 13 dB and 14 dB in gain, lower than 1 dB and 1.1 dB in noise figure, 1.7 and 1.8 input VSWR at normalized frequency $1.4{\sim}1.6$, respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.43 no.7 s.349
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• pp.13-19
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• 2006

A 5Gb/s cross coupled transimpedance amplifier (TIA) & limiting amp(LA), regulated cascode(RGC) is realized in a 0.18$\mu$m CMOS technology for optical printed circuit board applications. The optical receiver demonstrates $92.8db{\Omega}$ transimpedance and limiting amplifier gain, 5Gb/s bandwidth for 0.5pF photodiode capacitance, and 9.74mW power dissipation from 1.8V, 2.4V supply. Input stage impedance is $50{\Omega}$. The circuit was implemented on an optical PCB, and the 5Gb/s data output signal was measured with a good data eye opening.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.7
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• pp.723-730
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• 2007

This paper shows how the ACLR of power amplifier can be reduced by using Anti-phase IMD linearization technique which generate anti-phase IMD in the driver stage compare to output stage's IMD. And design process proposed. From the experimental result of W-CDMA 4FA input signal, this amplifier has ACLR -55 dBc@5 MHz offset at 30 watts average power. Compare to optimum matching technique to get maximum power gain, this technique has been improved ACLR by 12 dBc. Also this amplifier meets 50 watts average output power amplifier specification in domestic market.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.8
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• pp.673-679
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• 2009

This paper proposes a resonance power-combining technique using CRLH-transmission line. The circuits using proposed technique consist of the parallel capacitances and transmission lines to satisfy matching conditions and to combine power of amplifiers. The CRLH(Composite Right/Lefi-Handed) transmission lines are used to reduce the circuit size. As a result, the power combining amplifier using proposed techniques is measured that a gain is equal and the output power is increased about 2.2 dB higher than the single amplifier. Also, a size of amplifier is 78.3 % smaller than the conventional amplifier using RH transmission line.