Seungjin Kim

Remediation of petroleum hydrocarbon-contaminated sites by DNA diagnosis-based bioslurping technology

The application of effective remediation technologies can benefit from adequate preliminary testing, such as in lab-scale and Pilot-scale systems. Bioremediation technologies have demonstrated tremendous potential with regards to cost, but they cannot be used for all contaminated sites due to limitations in biological activity. The purpose of this study was to develop a DNA diagnostic method that reduces the time to select contaminated sites that are good candidates for bioremediation. We applied an oligonucleotide microarray method to detect and monitor genes that lead to aliphatic and aromatic degradation. Further, the bioremediation of a contaminated site, selected based on the results of the genetic diagnostic method, was achieved successfully by applying bioslurping in field tests. This gene-based diagnostic technique is a powerful tool to evaluate the potential for bioremediation in petroleum hydrocarbon contaminated soil.

Evaluation of denitrification–nitrification biofilter systems in treating wastewater with low carbon: nitrogen ratios

A two-stage biological aerated/anoxic filter (BAF) system for denitrification–nitrification was developed to increase nitrogen removal in the treatment of municipal wastewater with low carbon:nitrogen (C/N) ratio . This system exhibited a high denitrification efficiency (67%), despite the low C/N ratio, and the ratio of reduced nitrate to consumed organic compounds was greater than the theoretical value due to the minimization of the conversion of organic carbon to biomass growth, the maintenance of low levels of dissolved oxygen in recycled water, and the maximization of use of organic carbon biosorbed inside biomass in the denitrification BAF. The maximum rate of nitrogen removal was achieved at a recycle ratio of 170%, and the headloss in two BAFs was maintained after a 24-h backwash. Biological nitrogen removal in a two-stage BAF system was possible in a short hydraulic retention time (1.2 h) because the maximum reaction rates of nitrifiers and denitrifiers in each column were achieved.

A UHF-band RFID transmitter with spur reduction technique using a DLL-based spread-spectrum clock generator

This paper presents a UHF-band RFID transmitter with a robust spur reduction technique using a DLL-based SSCG. By adopting an 8-bit DLL and Hershey-kiss modulated profile together, the SSCG shows more than a 20dB EMI reduction while providing up-, down-, and center-spread modes. Implemented in a 0.18μm CMOS process, the proposed transmitter achieves <; -80dBc spur suppression with 25dBm transmit power at 920MHz, which complies with the most stringent regulatory spectral mask without a SAW-filter.

A 520 pJ/pulse IR-UWB radar for short range object detection

This paper presents a low power, low complexity IR-UWB radar transceiver for short range object detection. The transceiver provides robustness against false alarms without increasing power consumption, chip size, or complexity. The receiver (RX) and the transmitter (TX) dissipate only 50 pJ/pulse and 470 pJ/pulse under a 1.2V supply, respectively. The measured TX pulse spectrum, −58 dBm maximum power, complies with the FCC spectral mask and shows 1 GHz bandwidth with 4 GHz center frequency. The measured sensitivity of the RX is −45 dBm, and the RX is fully functional to detect an object in the range of 0.45 ∼ 1.2 m. The die size of the IR-UWB transceiver implemented in a 0.13 um CMOS process is 2.1 mm2.

Degradation of polyvinyl alcohol in textile waste water by Microbacterium barkeri KCCM 10507 and Paenibacillus amylolyticus KCCM 10508

Microbacterium barkeri KCCM 10507 and Paenibacillus amylolyticus KCCM 10508 were isolated and identified for the degradation of polyvinyl alcohol (PVA) contained in textile waste water. Kinetic parameters such as growth rate and substrate utilization rate were determined using a pure culture of two isolated strains. The degradation rate by a mixed culture of two isolated strains was higher than that by single strain only. Also, the effect of polymerization degree on biodegradation was negligible, but initial PVA concentration was very sensitive to biodegradation. Forty-two per cent of PVA and 55% of chemical oxygen demand in textile waste water were removed by a mixed culture of two isolated strains after 5 days.

Spur Reduction Techniques With a Switched-Capacitor Feedback Differential PLL and a DLL-Based SSCG in UHF RFID Transmitter

This paper presents a robust spur reduction technique using a switched-capacitor feedback differential phase-locked loop (PLL) and a delay-locked-loop (DLL)-based spread-spectrum clock generation in a UHF-band RF identification transmitter (TX). The proposed differential PLL is characterized by adopting a switched-capacitor common-mode feedback and distributed varactor biasing scheme to the differential charge pump and voltage-controlled oscillator designs, respectively, which results in down to 94 dBc in reference spur rejection with all digital parts off. Additionally, by adopting an 8-bit DLL and Hershey-Kiss modulated profile together, the proposed spread-spectrum clock generator shows more than 20-dB electromagnetic-interference reduction while providing up-, down-, and center-spread modes. Implemented in a 0.18m CMOS process, the proposed TX achieves <; - 80-dBc spur suppression with 25-dBm transmit power at 920 MHz, which complies with the most stringent regulatory spectral mask without a surface acoustic wave filter.

Enhancement of carbon dioxide reduction and methane production by an obligate anaerobe and gas dissolution device.

The use of gas dissolution devices to improve the efficiency of H2 dissolution has enhanced CO2 reduction and CH4 production. In addition, the nutrients that initially existed in anaerobic sludge were exhausted over time, and the activities of anaerobic microorganisms declined. When nutrients were artificially injected, CO2 reduction and CH4 production rates climbed. Thus, assuming that the activity of the obligatory anaerobic microorganisms is maintained, a gas dissolution device will further enhance the efficiency of CO2 reduction and CH4 production.

3.7 A fully integrated TV tuner front-end with 3.1dB NF, >+31dBm OIP3, >83dB HRR3/5 and >68dB HRR7

In TV tuner systems, the RF front-end design has been a challenging issue since it must simultaneously satisfy over 65dB of harmonic rejection (HR), and have high linearity for high-power input and low noise over wide bandwidth (48-to-870MHz). In terms of harmonic rejection, even though the state-of-the-art work reports over 60dB rejections on the 3rd- and 5th- order harmonics with a single mixer [1], higher-than-5th-order harmonic rejections are still required for the low-band channels in TV tuners and thereby RF filters are indispensable at the RF front-end. However, due to the difficulties of integrating RF filters satisfying low noise and high linearity over wide bandwidth, the previous works inevitably had to use external inductors [2-4]. Although a recent work successfully integrates an RF filter satisfying all the stringent specifications by current-domain signal flow from the LNA output to the baseband stage [5], the transconductance stage at the filter input is not linear enough to drive the high-power input and thus the input signal needs to be attenuated at the RF front-end, which eventually degrades system SNR.

A Type-I

In this letter, a type-I ΔΣ fractional-N frequency synthesizer adopting a new discrete-time loop filter (DTLF) is proposed. By means of assigning an additional pair of switched capacitors to the conventional first order DTLF architecture, cascaded capacitor-sharing operation is implemented, providing a second order infinite impulse response (IIR) filtering characteristic. The sufficiently high slope of the proposed second order DTLF lessens the need for additional passive filters in quantization noise suppression, thereby reducing the active chip area. Implemented in a 65 nm CMOS process, the proposed synthesizer occupies only 0.25 mm2, operates over a frequency range of 400 to 900 MHz with less than 10 Hz resolution, and consumes 4.7 mA from a 1 V supply. The measurement shows phase noise of -100.05 dBc/Hz and -128.29 dBc/Hz at 100 kHz and 1 MHz offsets, respectively, for 773 MHz operating frequency.

\Delta\Sigma

A high-speed and low-power adaptable period SAR-based DAC gain calibration is presented for DSM quantization noise suppression, which completes within 10μs while dissipating 0.2mW. The proposed calibration scheme is applied to the fractional-N type frequency synthesizer which adopts an 8-bit noise-cancelling DAC. The frequency synthesizer has a range of 48 to 900 MHz, consumes 11mA from 1.2-V supply and occupies 1.5 × 1.4 mm2 in 0.13μm CMOS process. The measurement shows more than 30-dB quantization noise suppression at a 877MHz oscillation frequency which results in the phase noise of -100.7dBc/Hz and -134.5dBc/Hz at 100-kHz and 1.25-MHz offset frequencies respectively.