• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.291-294
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• 2000

The production of polyhydroxybutrate(PHB) by Alcaligenes eutrophus NCIB 11599 was studied in a synthetic medium from whey as a sole carbon source. Especially pH-effect was treated and compared in this study. At the end of fermentation (A) unadjusted to pH, the dry cell weight, PHB concentration, and PHB conversion rate were 10.3g/L, 3.1g/L, and 30%, respectively. At the end of fermentation (B) adjusted to $pH(7.0{\sim}7.5)$, the dry cell weight, PHB concentration, and PHB conversion rate were 12.5g/L, 4.8g/L, and 41%, respectively. PHB conversion rate was about 10% higher on the fermentation (B) than on the fermentation (A).

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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• pp.1397-1400
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• 2008

Frame rate conversion became key technology due to recent advances in LCD panel refresh rates. Although many FRC algorithms have been developed and applied for LCD TV sets, they still suffer from well-known halo artifact. This paper discusses about the artifacts and method to handle them.

• 동력기계공학회지
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• 제18권3호
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• pp.14-19
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• 2014

The purpose of the study is to investigate the effect of additive catalyst according to the thermal aging of vanadia SCR catalysts. At a fresh condition, the $3V_2O_5-5WO_5-92TiO_2$ SCR showed the highest NOx conversion rate of about 30%, the performance of 5 kinds of SCR to which additive catalysts were added was not improved due to the insignificant effect of acid site control. For catalysts aged for 12h at $700^{\circ}C$, the SCR to which 3wt% Zeolite was added decreased in NOx conversion rate by 2.5% on average compared to the fresh SCR, it showed higher thermal durability than other additive catalyst. For 3Zeolite with high performance of NOx conversion rate during thermal aging, the Zeolite with stronger durability at a high temperature than other 5 kinds of SCR catalysts decreased the sintering of catalysts.

• 방송공학회논문지
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• 제24권5호
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• pp.785-790
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• 2019

본 논문에서는 적응적 중첩 블록 움직임 보상 방법을 이용한 새로운 양방향 프레임 율 향상 방법을 제안한다. 제안한 방법에서는 참조 영역의 움직임 복잡도에 기반한 적응적 중첩 블록 음직임 보상 방법이 사용된다. 움직임 복잡도는 이전에 부호화된 움직임 추정과정에서 판단되므로 중첩 블록 움직임 보상 방법에 적응적 기법을 추가적인 계산 복잡도 없이 적용 가능하다. 실험결과는 제한한 방법이 기존 방법에 비해 객곽적, 주관적 화질에서 우수함을 보여준다.

• 산업융합연구
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• 제18권5호
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• pp.1-13
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• 2020

본 연구는 투자자 입장에서 전환사채(CB)의 투자효과가 어느 정도 인지를 규명하고 효율적인 투자방안을 투자자들에게 제시하는 것이 연구목적이다. 연구방법은 2015년부터 2020년 6월까지 발행한 CB에 대한 표면이자율, 만기이자율, 채권만기일, 전환가격, 전환일 등을 조사한 후, 전환일 이후 일별주가변동과 연결하여 CB에 대한 투자효율성 및 주식전환효과가 어느 정도인지를 파악하였다. 연구 결과, 전환가격초과일수비율이 전환 가능한 날짜의 1/4 정도에 불과하여 CB의 투자효율성은 낮은 것으로 분석되었다. 전환일수익률은 평균 -6.3%, 만기일수익률은 평균 -5.2%여서 평균적으로 마이너스 수익률을 보여 투자자 기대와 다르게 투자효과가 산출되었다. 전환일수익률이 마이너스인 종목수가 플러스인 종목수 보다 2.4배, 만기일수익률이 마이너스인 종목수가 플러스인 종목수 보다 3.7배 많아서 CB의 주식전환 기대 수익률은 낮은 것으로 분석되었다.

• Macromolecular Research
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• 제11권5호
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• pp.311-316
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• 2003

The kinetics of photoinitiated polymerization of dimethacrylate macromonomers have been studied to determine the diffusion-controlled reaction parameters using attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR). A predicted kinetic rate expression with a diffusion control factor was employed to estimate an effective rate constant and to define the reaction-controlled and diffusion-controlled regimes in the photopolymerization. An effective rate constant, k$_{e}$, can be obtained from the predicted kinetic rate expression. At the earlier stages of polymerization, the average values of kinetic rate constants do not vary during the reaction time. As the reaction conversion, $\alpha$, reaches the critical conversion, $\alpha$$_{c}$, in the predicted kinetic expression, the reaction becomes to be controlled by diffusion due to the restricted mobility of dimethacrylate macromonomers. A drop in value of effective rate constant causes a drastic decrease of reaction rate at the later stages of polymerization. By determining the effective rate constants, the reaction-controlled and diffusion-controlled regimes were properly defined even in the photopolymerization reaction system.m.m.

• 대한기계학회논문집B
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• 제33권9호
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• pp.709-717
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• 2009

Heat transfer rate is a very important factor for the performance of a steam reformer because a steam reforming reaction is an endothermic reaction. Coaxial cylindrical reactor is the reactor design which can improve the heat transfer rate. Temperature, fuel conversion and heat flux in the coaxial cylindrical steam reformer are studied in this paper using numerical method under various operating conditions. Langmuir-Hinshelwood model and pseudo-homogeneous model are incorporated for the catalytic surface reaction. Dominant chemical reactions are assumed as a Steam Reforming (SR) reaction, a Water-Gas Shift (WGS) reaction, and a Direct Steam Reforming (DSR) reaction. Although coaxial cylindrical steam reformer uses 33% less amount of catalyst than cylindrical steam reformer, its fuel conversion is increased 10 % more and its temperature is also high as about 30 degree. There is no heat transfer limitation near the inlet area at coaxial-type reactor. However, pressure drop of the coaxial cylindrical reactor is 10 times higher than that of cylindrical reactor. Operating parameters of coaxial cylindrical steam reformer are the wall temperature, the inlet temperature, and the Gas Hourly Space Velocity (GHSV). When the wall temperature is high, the temperature and the fuel conversion are increased due to the high heat transfer rate. The fuel conversion rate is increased with the high inlet temperature. However, temperature drop clearly occurs near the inlet area since an endothermic reaction is active due to the high inlet temperature. When GHSV is increased, the fuel conversion is decreased because of the heat transfer limitation and short residence time.

• 대한화학회지
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• 제26권2호
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• pp.88-94
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• 1982

요소공장의 굴뚝에서 방출되는 가스상 암모니아와 입자상 암모늄을 측정하여 대기중에서 암모니아가 암모늄으로 전환되는 속도를 추정하였다. 암모니아가 암모늄으로 전환되는 것은 대기중에서의 수송시간에 따라 2단계로 나누어진다. 수송 초기 15분동안의 전환속도는 3.2%ㅡmin$^{-1}$이고 그 후는 0.26%min$^{-1}$이었다. 수송 초기단계에서 전환속도가 빠른 것은 굴뚝에서 방출된 유출가스의 온도강하에 의하여 생성된 물방울에 암모니아가 용해하고, 또 이 알칼리성 물방울에서 요소가 분해반응을 일으킴으로써 암모늄의 농도가 급격히 증가하였기 때문인 것으로 추정되었다. 암모니아 가스의 반감기는 수송 초기단계에서 약 16분이고, 그 후는 192분이었다. 측정기간에 있어서 입자상 암모늄염과 대기온도, 상대습도, 이산화황, 질소산화물 및 부유분진 농도와의 사이에는 상관관계가 관찰되지 않았다.

• 한국수소및신에너지학회논문집
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• 제33권6호
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• pp.723-732
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• 2022

Cracking ammonia inside solid oxide fuel cell (SOFC) stack is a compact and simple way. To prevent sharp temperature fluctuation and increase cell efficiency, the decomposition reaction should be spread on whole cell area. This leading to a question that, how does anode thickness affect the conversion rate of ammonia and the cell voltage? Since the 0D model of SOFC is useful for system level simulation, how accurate is it to use equilibrium solver for internal ammonia cracking reaction? The 1D model of ammonia fed SOFC was used to simulate the diffusion and reaction of ammonia inside the anode electrode, then the partial pressure of hydrogen and steam at triple phase boundary was used for cell voltage calculation. The result shows that, the ammonia conversion rate increases and reaches saturated value as anode thickness increase, and the saturated thickness is bigger for lower operating temperature. The similar cell voltage between 1D and 0D models can be reached with NH₃ conversion rate above 90%. The 0D model and 1D model of SOFC showed similar conversion rate at temperature over 750℃.

• 한국응용과학기술학회지
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• 제27권2호
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• pp.123-128
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• 2010

The continuous transesterification of mixed fat was done on the plug flow reactor packed with the static mixers. The transesterification using 0.5 wt% KOH, 0.8 wt% TMAH and mixed catalyst[40 v/v% KOH(0.5 wt%)+60 v/v% TMAH(0.8 wt%)] was conducted with the changes of molar ratios, weight percentage of beef, flow rates and number of static mixer's elements at $65^{\circ}C$. The overall conversion of mixed fat at 1:8 molar ratio, 50 wt% of beef and 24 of static mixer's elements increased until 0.7mL/min of flow rate. The overall conversion of mixed fat showed 96% at those conditions. So, the optimum operating conditions on tublar reactor were 1:8 molar ratio, 50 wt% of beef, 0.7 mL/min of flow rate and 24 of static mixer' s elements.