• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1992.05a
• /
• pp.57-57
• /
• 1992

Teicoplanin은 actinoplanes teicomyceticus의 발효산물로서 vancomycin과 같은 glycopeptide 계열의 항균제이며, 그 작용기전은 세포벽 합성과정중 peptidoglycan의 중합을 억제하는 것으로 vancomycin과 유사하나 vancomycin과 달리 근육에 주사할 수 있으며 "red man's syndrome"이 생기지 않고 vancomycin보다 반감기가 길다. 그람양성균 감염증에 대한 teicoplanin의 효능 및 안전성을 조사하기 위하여, 그람양성균에 의한 감염증 또는 그람양성균과 그람음성균에 의한 혼합감염증이 확인되거나 의심되었던 환자 46명을 대상으로 teicoplanin과 vancomycin을 투여하였다. 투약 환자중 임상적인 반응을 평가할 수 있는 환자의 수는 vancomycin의 경우 투약환자 22명중 21명, teicoplanin의 경우 24명중 19명이였다. Vancomycin군중 임상적 반응의 평가에서 제외된 1명은 수술 후 흉막강에 MRSA 에 의한 농양으로 투약 29일째에 뇌출혈로 사망하였던 예로, 추적-배양검사에서는 MRSA가 제거 되었다. Teicoplanin군에서는 항균제 투여 중 간경변증에 의한 식도출혈 1예, 수술후 위장관 출혈 1예, 뇌 색전중 1예가 사망하였고, 1예는 Teicoplanin에 의한 심한 피부발진으로, 다른 1예는 봉와직염의 임상진단이 조직검사결과 악성종양의 근육침범으로 밝혀져 투약을 중단하였다.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.9
• /
• pp.773-779
• /
• 2014

A qualitative and quantitative analysis on flame dynamics is required to model combustion instability characteristics in gas turbine lean premixed combustors. The current paper shows the flame transfer function modeling results using CFD(Computational Fluid Dynamics) techniques for the flame dynamics study. It is generally known that flame shapes determine the basic characteristics of the flame transfer function. The comparisons of the modeled flame shapes with the measured ones were made using the optimized heat transfer conditions. Modeling results of the flame transfer function show the close behaviors to the measured data with a reasonable accuracy if the flame geometry can be exactly captured.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.15 no.4
• /
• pp.35-40
• /
• 2011

An experimental study of the flame response in a turbulent premixed combustor has been conducted in order to investigate mechanisms for combustion instabilities in a lean premixed gas turbine combustor. A lab-scale combustor and mixing section system were fabricated to measure the flame transfer function. Measurements are made of the velocity fluctuation in the nozzle using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The results show that the flame transfer functions are greatly dependent on the modulation frequency as well as operating conditions such as equivalence ratio. Flame dynamics can be generalized as a function of Strouhal number which is a ratio of flame length to modulation wave length.

• Clean Technology
• /
• v.23 no.1
• /
• pp.42-53
• /
• 2017

Numerical analysis was done to evaluate the fluid distribution inside of the mixing quencher to increase the reaction efficiency of the aqueous hydrogen peroxide solution in the scrubbing column which is used for simultaneous desulfurization and denitrification. Effective injection of the aqueous hydrogen peroxide ($H_2O_2$) solution in the mixing quencher has major effects for improving the reaction efficiency in the scrubbing column by enhancing the mixing of the aqueous $H_2O_2$ solution with the exhaust gas. The current study is to optimize the array of nozzles and the spray angles of the aqueous $H_2O_2$ solution in the mixing quencher by using the computational method. Main concerns of the analysis are how to enhance the uniformity of the $H_2O_2$ concentration distribution in the internal flow. Numerical analysis was done to check the distribution of the internal flow in the mixing quencher in terms of RMS values of the $H_2O_2$ concentration at the end of quencher. The concentration distribution of $H_2O_2$ at the end of is evaluated with respect to the different array of the nozzle pipes and the nozzle tip angles, and we also analyzed the turbulence formation and fluid mixing in the zone. The effect of the spray angle was evaluated with respect to the mixing efficiency in different flow directions. The optimized mixing quencher had the nozzle array at location of 0.3 m from the inlet duct surface and the spray angle is $15^{\circ}$ with the co-current flow. The RMS value of the $H_2O_2$ concentration at the end of the mixing quencher was 12.4%.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.34 no.2
• /
• pp.197-202
• /
• 2010

A combustion chamber with a branch tube was built to investigate the characteristics of a spontaneous oscillating laminar premixed Bunsen flame. The flame behavior was observed, and the relation between the flame surface area and heat release rate was inspected. The equivalence ratio and mean velocity were fixed at 1.1 and 1.75 m/s, respectively. The amplitude of the pressure fluctuation in the combustion chamber was changed and the flame behavior was affected when the length ratio between the branch tube and combustion chamber (L:R) was varied. The $OH^*$, $CH^*$, and flame chemiluminescence had similar behavior qualitatively. There was linearity between the flame surface area and heat release rate.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.1
• /
• pp.51-57
• /
• 2013

This study aims to experimentally investigate the combustion characteristics of a lean premixed swirl-stabilized burner with dual-stage fuel injection arrays. The results show that a variation in the fuel distribution to fuel stages 1 (upstream) and 2 (downstream) produces a noticeable change in the NOx and CO emissions. Reducing the confined ratio, defined as the ratio of the nozzle exit diameter to the liner diameter, may reduce NOx and CO emissions owing to reduced combustion loading and longer residence time, respectively. A nozzle exit velocity of 30 m/s shows the optimum characteristics in terms of NOx and CO emissions and flame stability: increasing or decreasing the nozzle exit velocity leads to a degradation in emissions or flame stability, respectively.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.4
• /
• pp.24-30
• /
• 2004

As the environmental pollution becomes serious global problem, the regulation of emission exhausted from automobiles is strengthened. Therefore, it is very important to know how to reduce the NOx and PM simultaneously in diesel engines, which has lot of merits such as high thermal efficiency, low fuel consumption and durability. By this reason, the new concept called as Homogeneous Charge Compression Ignition(HCCI) engines are spotlighted because this concept reduced NOx and P.M. simultaneously. However, there is trade off between output and NOx in a HCCI engine. In this study, output and emission characteristics for a gasoline direct injection type HCCI engine were investigated to clarify the effects of intake air temperature, injection time and mixture formation. From these experiments, we found that the smoke was not produced when the fuel was injected earlier than BTDC 90$^{\circ}$. In addition, the output was increased because of delay of ignition time and NOx emission was decreased because of homogeneous charge of first injection in case of split injection.

• 한국가시화정보학회:학술대회논문집
• /
• 2005.04a
• /
• pp.115-154
• /
• 2005

SI 엔진의 연소특징은 비정상 난류 예혼합 화염이며 여기서 내부 유동은 직접 화염 전파에 영향을 미치며 난류와 거시적 유동의 패턴 모두 중요한 역할을 한다. 내연기관 연소에서 난류는 매우 중요한 역할을 하고 통상 엔진 속도($\approx$흡입유동 속도)에 비례하며 그 주요 역할은 고속 운전 시 해당 사이클 내에 연소가 완료되는 데 기여하지만 출력저하, 제어 및 측정 그리고 사이클 변동과 관련하여 실질적으로 난류 제어를 통한 엔진 성능 개선은 사실상 불가능하다. 실물 엔진의 성능 파라미터로 주로 유동의 거시적 거동이 사용되며 이 유동과 연료 분사계가 혼합기 분포 상태와 화염 전파 방향을 결정하여 최종적으로 엔진의 성능을 지배한다. 따라서 가시화를 통한 연소 진단도 이 현상에 주목할 필요가 있으며 거시적 파라미터를 성능에 연관하는 다양한 기법이 존재하고 이들은 매우 풍부한 데이터베이스를 통해 비교적 정확한 성능의 예측을 가능하게 하고 이 점에 주목한 엔진만 성공을 거두었다. 이 거시적 현상에 주목하여 가시화를 통해 성층화 현상을 실험적으로 해석한 예를 제시하였다. SI 엔진 가시화에서 기법보다 중요한 것은 현상의 이해이다. 이를 위해 성공적 가시화 진단을 위해서는 우선 현상에 대한 모델링이 필요하고 이 모델에서 가시화를 통해 규명 가능한 현상을 추출해 내는 것이다.

• Journal of ILASS-Korea
• /
• v.20 no.3
• /
• pp.135-140
• /
• 2015

Flame transfer function is used to determine the relationship between flow fluctuations and heat release perturbations in a lean premixed gas turbine combustor. The characteristics of flame transfer function are known to depend greatly on flame geometries in addition to other various flow conditions. However, it is not easy to experimentally measure the flame transfer function under various actual combustor operating conditions in terms of time and cost. The current research tries to model the flame transfer function using CFD(Computational Fluid Dynamics). From the results, it is shown that the calculated steady flame geometry can be exactly captured with consideration of the wall heat transfer and radiations. Also, unsteady analysis results show the close characteristics of the flame transfer function to the measured one in both gain and phase.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.17 no.3
• /
• pp.8-14
• /
• 2009

Effect of heterogeneity of combustion chamber has been thought as one of the way to avoid dramatically generating heat in HCCI Combustion. The purpose of this research is to investigate the effect of heterogeneity, especially thermal stratification and fuel strength stratification on HCCI Combustion fueled with DME and n-Butane. Thermal stratification is formed in Combustion Chamber of Rapid Compression Machine with 3 Kinds of pre-mixture has different properties. The stratified charge mixture is adiabatic compressed and on that process, in cylinder gas pressure and two-dimensional chemiluminescence images are measured and analyzed.