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저전력 2.5GHz/0.5GHz CMOS 이중 주파수합성기 완전 집적화 설계
강기섭,오근창,박종태,유종근,Kang, Ki-Sub,Oh, Gun-Chang,Park, Jong-Tae,Yu, Chong-Gun 한국전기전자학회 2007 전기전자학회논문지 Vol.11 No.1
본 논문에서는 0.2$\mu$m CMOS 공정을 사용하여 무선 LAN 응용을 위한 이중대역 주파수 합성기를 설계하였다. 회로 설계시 저전력 특성에 중점을 두었다. 특히 VCO, 프리스케일러 등 핵심회로 설계시 전력소모를 최소화하도록 하였다. 모든 구성 소자를 on-chip화하여 외부 소자의 필요성을 제거 하였으며, 다양한 주파수에 동작이 가능하도록 외부 데이터에 의해 동작 주파수를 프로그램 한 수 있도록 하였다. 설계된 주파수 합성기의 RF 대역 동작 주파수 범위는 2.3GHz$\sim$2.7GHz이며, IF 대역 범위는 250MHz$\sim$800MHz이다. 설계된 RF 블록과 IF 블록은 2.5V의 전원으로부터 각각 5.14mA@2.5GHz와 1.08mA@0.5GHz의 적은 전류를 소모한다. IF 대역에서 측정된 위상 잡음은 in-band에서는 -85dBc/Hz이고, 1MHz offset 에서는 -105dBc/Hz이다. 전체 칩 크기는 1.7mm$\times$l.7mm 이다. This paper describes a dual frequency synthesizer designed in a 0.2$\mu$m CMOS technology for wireless LAN applications. The design is focused mainly on low-power characteristics. Power dissipation is minimized especially in VCO and prescaler design. The designed synthesizer includes all building blocks for elimination of external components, other than the crystal. Its operating frequency can be programmed by external data. It operates in the frequency range of 2.3GHz to 2.7GHz (RF) and 250MHz to 800MHz (IF) and consumes 5.14mA at 2.5GHz and 1.08mA at 0.5GHz from a 2.5V supply. The measured phase noise is -85dBc/Hz in-band and -105dBc/Hz at 1MHz offset at IF band. The die area is 1.7mm$\times$1.7mm.
미분탄 바이오매스 혼소 시 연료 단계 연소를 통한 NOx 저감 특성 연구
강기섭(Kieseop Kang),오준호(Junho Oh),양주향(Joohyang Yang),양원(Won Yang),류창국(Changkook Ryu) 한국연소학회 2015 KOSCOSYMPOSIUM논문집 Vol.2015 No.5
This study investigates the co-combustion characteristics of biomass in a coal fired tangential firing boiler in a 560 MWe capacity power plant. The detailed flow, heat and reaction characteristics for different cofiring methods were evaluated using computational fluid dynamics adopting sub-models for combustion of solid fuels. The cofiring of biomass having a lower calorific value led to overall decrease in the gas temperatures of the burner zone and corresponding decrease in NOx emission. The use of dedicated burners for biomass had different temperature and NOx concentrations, compared to the cases for direct cofiring of coal/biomass blends. The results suggest that biomass cofiring method can be optimized for reduced NOx emission.
강기섭(Kieseop Kang),이용운(Yongwoon Lee),박진제(Jinjae Park),류창국(Changkook Ryu),양원(Won Yang) 한국연소학회 2013 KOSCOSYMPOSIUM논문집 Vol.- No.46
Biomass is well known for organic resources photosynthesized by carbon dioxide water in the air and thus it can be widely used in the form of energy and production for various kinds of materials. Through pyrolysis, biomass can be transformed into solid(biochar), liquid(bio-oil), and combustible gas on the different condition of temperature and heating rate. That’s why biomass can be practically used to preprocess and produce a variety of elements. This work is to analyze the characteristics of slow pyrolysis of three different kinds of biomass extracted from Indonesia. They showed similar moisture content and combinations of combustible matters and had quite a large discrepancy in the ash among them like 2.1 & of Bagasse, 91% of PKS, and 20.9% of Paddy Straw, respectively. yield of biochar, solid form of the biomass, steadily decreased when the temperature went up and that of bio-oil the highest at the temperature of 500 degrees Celsius. At the same temperature range, PKS bio-oil showed 51.4 % of yield and Bagasse had 55.1% while it turned out that Paddy straw showed the lowest yield of 37.2%. The apparent density was also measured to figure out the density of each product from the pyrolysis experiments at the temperature of 500 degrees Celsius. The result was like these; the density of biochar was 0.17, the lowest, and that of Tree stem was 1.3 when mixed by an equal amount of biochar and bio-oil.
강기섭(Ki-Sub Kang),오근창(Gun-Chang Oh),박종태(Jong-Tae Park),유종근(Chong-Gun Yu) 대한전기학회 2006 대한전기학회 학술대회 논문집 Vol.2006 No.10
This paper describes a frequency synthesizer designed in a 0.25㎛ CMOS technology for using local oscillators for the IF stages. The design is focused mainly on low-power charaeteristics. A simple ring-oscillator based VCO is used, where a single control signal can be used for variable resistors. The designed PLL includes all building blocks for elimination of external components, other than the crystal, and its operating frequency can be programmed by external data. It operates in the frequency range of 250㎒ to 800㎒ and consumes 1.08㎃ at 500㎒ from a 2.5V supply. The measured phase noise is -85㏈c/㎐ in-band and -105㏈c/㎐ at 1㎒ offset. The die area is 1.09㎟.
접선연소식 보일러에서 미분탄 연소 시 공기 배분의 영향에 대한 전산해석연구
강기섭 ( Kieseop Kang ),류창국 ( Changkook Ryu ) 한국화학공학회 2017 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.55 No.4
본 연구는 560 MWe급 접선연소식 미분탄 보일러에서 공기단계연소에 의한 연소 및 NOx 배출 특성과 슬래깅성에 대하여 분석한 것이다. 이를 위해 고급 석탄 연소 모델이 적용된 전산유체역학(CFD) 시뮬레이션을 이용하여 전체 연소공기의 당량비(SR)는 1.2로 고정하고, 버너 영역의 SR을 0.94에서 0.995까지 변화시켰다. 공기 배분의 변화에 따라 버너 영역 및 열교환기의 온도 및 전열량 분포가 변하지만 보일러의 전체 효율은 거의 동일하게 나타났다. 버너 영역의 SR이 0.94로 낮아지면 Fuel NO의 생성이 억제되어 절탄기 출구 NOx 배출량은 20% 감소하나, 미연분과 슬래깅성에는 큰 영향이 나타나지 않았다. 따라서, 이 보일러에서 NOx 배출 저감을 위해 공기배분을 조절하여 버너 영역의 SR를 낮추고 상부연소공기(OFA)의 값을 높여 운전하는 것이 타당함을 확인하였다. This study investigated the influence of air staging on combustion and NOx emission in a tangential-firing boiler at a 560 MWe capacity. For air staging, the stoichiometric ratio (SR) for the burner zone was varied from 0.995 to 0.94 while the overall value was fixed at 1.2. The temperature and heat flux in the burner zone and upper furnace corresponded to the distribution of SR, while the total boiler efficiency remained similar. The NOx emission at the furnace exit was reduced by up to 20% when the SR in the burner zone decreased to 0.94. However, the amount of unburned carbon and slagging propensity was not noticeably influenced by the changes in the SR of the burner zone. Therefore, it was favorable to lower the SR of the burner zone for reduction of NOx emission.
MB-OFDM 방식의 UWB 시스템을 위한 CMOS LNA 설계
이재경,강기섭,박종태,유종근,Lee Jae-kyoung,Kang Ki-sub,Park Jong-tae,Yu Chong-gun 한국정보통신학회 2006 한국정보통신학회논문지 Vol.10 No.1
본 논문에서는 MB-OFDM 방식의 초광대역 시스템 응용을 위한 단일 단 cascode 구조의 CMOS 저잡음증폭기를 설계하였다. 광대역 ($3.1GHz\~4.9GHz$) 입력 매칭은 칩 면적과 잡음지수를 줄이기 위해 간단한 대역 통과 필터를 사용하여 수행하였다. $0.18{\mu}m$ CMOS 공정변수를 사용하여 모의실험 한 결과, 설계된 증폭기는 9.7dB의 최대 이득, $2.1GHz\~7.1GHz$의 3dB 대역폭, 2dB의 최소잡음지수, -2dBm의 IIP3, -11.8dB 이하의 입력 반사 손실 특성을 보이며, 1.8V 공급 전원전압에 25.8mW의 전력을 소모한다. 칩면적은 패드를 포함해서 $0.74mm^2$이다. A CMOS LNA based on a single-stage cascode configuration is designed for MB-OFDM ultra-wide band(UWB) systems. Wideband($3.1GHz\~4.9GHz$) input matching is performed using a simple bandpass filter to minimize the chip size and the noise figure degradation. The simulation results using $0.18{\mu}m$ CMOS process parameters show a power gain of 9.7dB, a 3dB band width of $2.1GHz\~7.1GHz$, a minimum NF of 2dB, an IIP3 of -2dBm. better than -11.8dB of input matching while occupying only $0.74mm^2$ of chip area. It consumes 25.8mW from a 1.8V supply.
500MWe 접선연소식 석탄 보일러의 NOx 저감을 위한 SOFA 최적화 연구
조현빈(Hyunbin Jo),강기섭(Kiseop Kang),박종근(JongKuen Park),류창국(Changkook Ryu),안현수(Hyunsoo Ahn),고영건(Younggun Go) 한국연소학회 2019 KOSCOSYMPOSIUM논문집 Vol.2019 No.5
This study investigated the optimization of separated overfire air (SOFA) on combustion and NOx emission in a retrofitted tangential-firing boiler at a 500 MWe capacity. Computational fluid dynamic (CFD) simulations incorporating advanced coal combustion models were performed for two operating parameters of the boiler. First, the flow rate of SOFA was varied between 15% and 35% of the total air while the flow rate of CCOFA (Close-coupled overfire air) was fixed at 5%. Second, the proportion of SOFA was varied from 0% to 25% while holding the flow rate of total OFA was fixed at 25%. When compared with the operation data, the CFD results showed reasonable agreement in terms of the heat distribution of the boiler and NOx emission for the reference case. The NOx emission at the furnace exit was reduced by up to 33% but unburned carbon in fly ash was increased by 3 times when the flow rate of SOFA increased to 35%. When the total OFA was fixed at 25%, increasing the SOFA reduced both the NOx emission and unburned carbon up to a ceratin proportion, and then increased them. This suggests that the combustion air distribution can be optimized between SOFA and CCOFA for reduction of both NOx and unburned carbon.
500 MWe급 접선 연소 보일러 해석시 난류 혼합 속도 및 석탄 연소 모델의 영향 평가
양주향(Joo-Hyang Yang),강기섭(Kie-Seop Kang),류창국(Changkook Ryu) 한국연소학회 2015 KOSCOSYMPOSIUM논문집 Vol.2015 No.12
Computational fluid dynamics (CFD) modeling of large-scale coal-fired boilers requires a complicated set of flow, heat transfer and combustion process models based on different degrees of simplification. This study investigates the influence of coal devolatilization, char conversion and turbulent gas reaction models in CFD for a tangential-firing boiler at 500MWe capacity. Devolatilization model is found out not significant on the overall results, when the kinetic rates and the composition of volatiles were varied. In contrast, the turbulence mixing rate influenced significantly on the gas reaction rates, temperature, and heat transfer rate on the wall. The influence of char conversion by the unreacted core shrinking model (UCSM) and the 1st-order global rate model was not significant, but the unburned carbon concentration was predicted in details by the UCSM. Overall, the effects of the selected models were found similar with previous study for a wall-firing boiler.