• 대한기계학회논문집
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• 제16권11호
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• pp.2119-2125
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• 1992

본 연구에서는 현재 사용되고 있는 산소센서의 단점을 극복할 수 있는 방법을 광역공연비센서처럼 공연비를 추정할 수 있는 방법을 연구한다. 그 방법으로 신경회 로망을 사용한 배기가스의 공연비 추정기(estimator)를 구성한다. 그리고 이 추정기 를 이용한 공연비 제어기를 설계하고 실제 MPI엔진에 적용하여 그 성능을 알아 보겠다.

• Bulletin of the Korean Chemical Society
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• 제25권5호
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• pp.699-703
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• 2004

Solvolyses of isopropylsulfonyl chloride (IPSC) in water, D_2O,\;CH_3OD$, and in aqueous binary mixtures of acetone, ethanol and methanol are investigated at 25, 35 and 45$^{\circ}C$. The Grunwald-Winstein plot of first-order rate constants for the solvolytic reaction of IPSC with $Y_{Cl}$ (based on 2-adamantyl chloride) shows marked dispersions into three separate lines for three aqueous mixtures with a small slope (m < 0.30). The extended Grunwald-Winstein plots for the solvolysis of IPSC show better correlation. The kinetic solvent isotope effects determined in water and methanol are in consistent with the proposed mechanism of the general base catalyzed and/or $S_AN/S_N2$ reaction mechanism for IPSC solvolyses based on mass law and stoichiometric solvation effect studies.

• 한국재료학회지
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• 제11권9호
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• pp.797-801
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• 2001

In this study, the solution combustion method was employed to synthesize stoichiometric mullite, and hence the attrition process was employed to prepare ultrafine mullite particles with nano size. The thermal decomposition behavior and partial pressure of equilibrium species of both oxidizer and fuel were considered during solution combustion process. The synthesized product was mullite phase with 40 nm crystalline size, and the alumina contents of the product by TEM/EDS quantity analysis was 3.12$\pm$04 mole. The result showed that the synthesized mullite was almost close to the it's stoichiometric composition. For attrition process, the dispersion behavior of the mullite suspension was controlled and was comminuted with the condition of 800 rpm for 4 hours using 0.3 mm zirconia ball media. As a result of comminution, the mean particle size was 80 nm.

• ETRI Journal
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• 제34권2호
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• pp.226-234
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• 2012

The novelty of this study resides in the fabrication of stoichiometric and stress-reduced $Si_3N_4/SiO_2/Si_3N_4$ triple-layer membrane sieves. The membrane sieves were designed to be very flat and thin, mechanically stress-reduced, and stable in their electrical and chemical properties. All insulating materials are deposited stoichiometrically by a low-pressure chemical vapor deposition system. The membranes with a thickness of 0.4 ${\mu}m$ have pores with a diameter of about 1 ${\mu}m$. The device is fabricated on a 6" silicon wafer with the semiconductor processes. We utilized the membrane sieves for plasma separations from human whole blood. To enhance the separation ability of blood plasma, an agarose gel matrix was attached to the membrane sieves. We could separate about 1 ${\mu}L$ of blood plasma from 5 ${\mu}L$ of human whole blood. Our device can be used in the cell-based biosensors or analysis systems in analytical chemistry.

• Bulletin of the Korean Chemical Society
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• 제26권8호
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• pp.1241-1245
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• 2005

Solvolyses of trifluoromethanesulfonyl chloride (TFMSC) in water and in aqueous binary mixtures of acetone, ethanol and methanol are investigated at 25, 35 and 45 ${^{\circ}C}$. The Grunwald-Winstein plot of first-order rate constants for the solvolytic reaction of TFMSC with YCl (based on 2-adamantyl chloride) shows marked dispersions into three separate curves for three aqueous mixtures. The extended Grunwald-Winstein plots for the solvolysis of TFMSC show better correlation. The large negative ${\Delta}S^{\neq}$ and relatively small positive ${\Delta}H^{\neq}$ reveals that the solvolytic reaction proceeds via a typical bimolecular reaction mechanism. The l and m values determined in various solvents are consistent with the proposed mechanism of the general base catalysis $S_AN/S_N2$reaction mechanism for TFMSC solvolyses based on mass law and stoichiometric solvation effect studies.

• Bulletin of the Korean Chemical Society
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• 제17권6호
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• pp.520-524
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• 1996

Solvolyses of phenyl chloroformate in water, D2O, CH3OD, 50% D2O-CH3OD, and in aqueous binary mixtures of acetone, ethanol and methanol are investigated at 25.0 ℃. Product selectivities are reported at 25 ℃ for a wide range of ethanol-water and methanol-water solvent compositions. The Grunwald-Winstein plots of first-order rate constants for phenyl chloroformate with YCl (based on 2-adamantyl chloride) show marked dispersions into three separate lines for the three aqueous mixtures with a small m value (m< 0.2) and a rate maximum for aqueous alcohol solvents. Third-order rate constants, kww, kaw, kwa and kaa were calculated from the observed kww and kaa values together with kaw and kwa calculated from the intercept and slope of the plot of 1/S vs. [alcohol]/[water]. The calculated rate constants, kcalc and mol % of ester agree satisfactorily with those of the observed rate constants, kobs and mol % of ester, supporting the stoichiometric solvation effect analysis. The kinetic solvent isotope effects determined in water and methanol are consistent with the proposed mechanism of the general base catalyzed and/or carbonyl addition for phenyl chloroformate solvolyses based on mass law and stoichiometric solvation effect studies.

• 한국분무공학회지
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• 제28권2호
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• pp.55-61
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• 2023

Natural gas is a high-octane fuel that is effective in controlling knocking combustion. In addition, as a low-carbon fuel with a high hydrogen-carbon ratio, it emits less carbon dioxide and almost no particulate matter compared to conventional fossil fuels. Stoichiometric combustion engines equipped with a three-way catalyst are useful in various fields such as transportation and power generation because of their excellent exhaust emission reduction performance. However, stoichiometric combustion engines have a disadvantage of lower thermal efficiency compared to lean combustion engines. In this study, a combination of high compression ratio and Atkinson cycle was implemented in a 11 liter, 6-cylinder, spark-ignition engine to improve the thermal efficiency of the stoichiometric engine. As a result, pumping and friction losses were reduced and the operating range was extended with optimized Atkinson camshaft. Based on the exhaust gas limit temperature of 730℃, the maximum load and thermal efficiency were improved to BMEP 0.66 MPa and BTE 35.7% respectively.

• 자원리싸이클링
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• 제30권6호
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• pp.61-67
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• 2021

이리듐이 함유된 염산 침출액으로부터 시멘테이션법을 이용한 이리듐 회수 연구를 실시하였다. 환원제로는 아연을 사용하였으며, 환원제 투입량, 이리듐 초기 농도, 초기 pH, 반응 시간 변화 및 초음파 처리에 따른 이리듐 회수율 특성 실험을 실시하였다. 교반기만 사용한 조건에서는 아연 투입량 증가에 따라 이리듐의 회수율이 지속적으로 증가하였으나, 아연 당량이 40 조건에서 70% 수준의 이리듐 회수율을 나타냈다. 초음파 처리에 따른 시멘테이션 조건에서는 아연 투입량이 20 당량 이하 조건에서 이리듐의 회수율이 감소하였고, 40 당량 조건에서는 이리듐 회수율이 급격히 증가하는 특성을 나타났다. 이는 초음파 처리에 따른 아연의 이온화 및 이리듐 재용해되어 나타난 결과로 판단된다. 초음파 장치를 교반기와 함께 사용한 조건에서 교반기만 사용한 동일 조건에 비해 27% 이상 이리듐 회수율이 증가함을 확인하였고, 99%의 이리듐 회수가 가능하였다(아연 40 당량, 초기 pH 0.01, 100 ml, 이리듐 초기 농도 1770 ppm, 60 min.).

• 한국방사선학회논문지
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• 제16권5호
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• pp.537-543
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• 2022

본 연구의 목적은 이중에너지 CT를 이용한 유효원자번호 정보를 통한 췌장 검출 가능성 연구이다. 10개의 다양한 인체 등가 물질의 유효원자번호를 Stoichiometric calibration을 통해 추정하였다. Stoichiometric calibration을 위해 저에너지와 고에너지에 해당하는 10개 인체 등가 물질에 대한 HU값을 이용하였다. 이를 바탕으로 반복 알고리즘을 통해 인체 등가 물질에 대한 유효원자번호 영상을 추출하였다. 연구결과에 따르면, 유효원자번호에 따른 감약의 비는 R²값이 0.9999로 추정되었고, Pancreas, water, Liver, Blood, Spongiosa, Cortical bone의 유효원자번호는 이론값과 비교하여 전체적으로 1% 이내의 정확도를 보였다. 췌장암 검사는 조영제를 사용하므로 잠재적인 조영제 부작용 가능성이 있다. 이를 해결하기 위해 조영 증강 없는 이중에너지를 이용한 유효원자번호 추출을 통해 정확하고 안전한 검사에 기여할 수 있을 것으로 사료된다. 본 연구를 바탕으로 향후 연구에서는 임상 영상을 바탕으로 췌장암의 HU값을 이용하여 췌장암 검출에 대한 연구를 수행할 것이다.

• 한국결정학회:학술대회논문집
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• 한국결정학회 2000년도 정기총회 및 구정회교수 추모 춘계학술연구발표회
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• pp.28-28
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• 2000