Group-velocity Dispersion Effects on Quantum Noise of a Fiber Optical Soliton in Phase Space

주형규,이은철 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.1

Group-velocity dispersion (GVD) effects on quantum noise of ultrashort pulsed light are theoretically investigated at the soliton energy level, using Gaussian-weighted pseudo-random distribution of phasors in phase space for the modeling of quantum noise properties including phase noise, photon number noise, and quantum noise shape in phase space. We present the effects of GVD that mixes the different spectral components in time, on the self-phase modulation(SPM)-induced quantum noise properties in phase space such as quadrature squeezing, photon-number noise, and tilting/distortion of quantum noise shape in phase space, for the soliton that propagates a distance of the nonlinear length ηNL = 1/(γP0) (P0 is the pulse peak power and is the SPM parameter). The propagation dependence of phase space quantum noise properties for an optical soliton is also provided.

Effect of velocity variation on carbon/epoxy composite damage behavior

Baluch, Abrar H,Kim, Chun Gon SAGE Publications 2016 Journal of composite materials Vol.50 No.15

<P>In this paper, the damage mechanism for carbon fiber-reinforced polymers composites was studied from low- to high-velocity impact for different velocity ranges. Initially, the composites were manufactured by using CU125NS prepreg in quasi-isotropic 16 layers pattern [0/+/- 45/90](2s) in autoclave by adopting standard procedures. Specimens were also exposed to the simulated LEO environment and 0.42% total mass loss occurred due to out-gassing. Afterwards, the specimens were impacted with Al2017-T4 spherical projectiles of 5.56mm in diameter, 0.25g in weight for different velocities ranging from 500m/s to 2200m/s. With the impact velocity increase, the energy absorption was found to increase in the composite specimens, while the ratio of energy absorbed to total impact energy remains the same on average. Mainly, the fiber breakage and matrix fracture play a critical role in energy absorption, but delamination contribution also found increasing trend with the increase of impactor velocity. Afterwards, C-SCAN analyses were conducted to investigate the damage patterns, and it was found that the damage area increased with higher velocities. The delamination contribution increased on average by 12.7% for the velocity range of 2200m/s in comparison to that for 502m/s. On the basis of these findings, it was concluded that the contribution of fiber breakage, matrix fracture and delamination towards the damage mechanism of composites is greater for higher velocities.</P>

입자상물질과 VOCs 동시제거 실증장치에서 자동차 페인트 부스 발생 paint aerosol과 VOCs의 동시제거 성능 특성

이재랑,전성민,이강산,김광득,박영옥,Lee, Jae-Rang,Hasolli, Naim,Jeon, Seong-Min,Lee, Kang-San,Kim, Kwang-Deuk,Park, Young-Ok 한국입자에어로졸학회 2016 Particle and Aerosol Research Vol.12 No.4

The purpose of this study is to determine the performance characteristics of the paint particulate and volatile organic compounds(VOCs) simultaneous removal from the spraying paint booth in the laboratory and real site by sticky paint particulate and VOCs simultaneous removal demonstration unit. The sticky paint particulate and VOCs simultaneous removal unit is composed of the horizontal type pleated filter modules and the zig-zag type granular activated carbon packing modules. The test conditions at the laboratory are $50.15g/m^3$ of average paint aerosol concentration and 300 ppm of VOCs concentration which were same as the working conditions of spraying paint booth in the real site. But, the demonstration conditions at the real site are varied according to the working condition of spraying paint booth for the kind of passenger car bodies. The test results at the laboratory obtained that 99% of total particulate collection efficiency at 0.62 m/min of filtration velocity and 84% at 1.77 m/min of filtration velocity. The VOCs removal efficiencies are 97% at $3500hr^{-1}$ of gas hour space velocity and 59% at $10,000hr^{-1}$ of gas hour space velocity. In the real site test, the average removal efficiency of PM10 was measured to be 99.65%, the average removal efficiency of PM2.5 was 99.38%, the average removal efficiency of PM1 was 98.52%, and the average removal efficiency of VOCs was 89%.

반응조건에 대한 Mn-Cu-TiO₂촉매와 V/TiO₂촉매의 탈질 특성

장현태(Hyun Tae Jang),차왕석(Wang Seog Cha) 한국산학기술학회 2016 한국산학기술학회논문지 Vol.17 No.7

암모니아를 환원제로 사용하는 선택적 촉매 환원법에서 Mn-Cu-TiO₂ 촉매와 V2O₅/TiO₂ 촉매를 사용하여 반응 조건에 따른 질소 산화물 전환 특성을 연구하였다. 반응 온도와 공간 속도를 변경시키면서 촉매의 질소 산화물 전환 효율 변화를 측정하였다. Mn-Cu-TiO₂ 촉매의 질소 산화물 제거 활성은 반응 온도와 공간 속도가 증가할수록 감소하였으나, V2O₅/TiO₂ 촉매의 경우 반응 온도 증가에 따라 촉매의 질소 산화물 제거 활성 또한 증가하였다. Mn-Cu-TiO₂ 촉매의 경우 200℃ 이하의 온도에서 저온 활성이 우수하였으며, 이를 H₂-TPR 및 XPS 분석 실험을 통해 확인할 수 있었다. 초기 반응 온도의 변경 실험 을 통해 Mn-Cu-TiO₂ 촉매의 경우 고온에서 열적 쇼크를 일부 받으나, V2O₅/TiO₂ 촉매의 경우는 거의 영향을 받지 않음을 확인할 수 있었다. 공간 속도에 따른 질소 산화물 전환 효율 변화는 C 촉매의 경우 전 구간에 걸쳐 공간 속도가 증가할수록 질소 산화물 전환 효율도 감소하는 경향을 보였다. 그러나 D 촉매의 경우 공간 속도가 증가할수록 질소 산화물 전환 효율은 감소하였으나, 감소 정도가 C 촉매 보다는 훨씬 적었다. The NOx conversion properties of Mn-Cu-TiO₂ and V2O₅/TiO₂ catalysts were studied for the selective catalytic reduction (SCR) of NOx with ammonia. The performance of the catalysts was investigated in terms of their NOx conversion activity as a function of the reaction temperature and space velocity. The activity of the Mn-Cu-TiO₂ catalyst decreased with increasing reaction temperature and space velocity. However, the activity of the V2O₅/TiO₂ catalyst increased with increasing reaction temperature. High activity of the Mn-Cu-TiO₂ catalyst was observed at temperatures below 200℃. H₂-TPR and XPS analyses were conducted to explain these results. It was found that the activity of the Mn-Cu-TiO₂ catalyst was influenced by the thermal shock caused by the change of the initial reaction temperature, whereas the V2O₅/TiO₂ catalyst was not affected by the initial reaction temperature. In the case of catalyst C, the NOx conversion efficiency decreased with increasing space velocity. The decrease in the NOx conversion efficiency with increasing space velocity was much less for catalyst D than for catalyst C.

PSO 알고리즘의 탐색 가능 영역 조정을 위한 새로운 기법

박경종(Kyoung-Jong Park) 한국SCM학회 2010 한국SCM학회지 Vol.10 No.2

This paper proposes a new method to control a search space varied during the optimization process of PSO(Particle Swam Optimization) algorithm. It is necessary to move a component beyond the search space into a feasible search space because the obtained component using the equations of particle and velocity of PSO method may be out of the search space. Finally, this paper makes a comparison between a new method and TRC method which is popular and simple. The results show that the new method outperforms TRC method though the population size is varied.

슬릿트형 사방댐의 배치에 따른 토석류 흐름에 대한 영향: 축소모형실험 연구

최신규,이정민,정한범,김지헌,권태혁 한국방재학회 2015 한국방재학회논문집 Vol.15 No.3

토석류는 집중호우 시 경사가 급한 비탈면에서 자연사면의 붕괴로 인한 토사가 강우와 혼합되어 빠르게 흐르는 현상이다. 중력에 의해발생되는 이러한 현상은 빠른 이동 형태를 보이고 경사가 낮은 지역을 만나면서 퇴적되는데, 이 과정에서 인명과 재산에 막대한 피해를 입히게 된다. 이러한 이유로 토석류를 막기 위한 구조물이 많이 건설되고 있다. 그 중, 슬릿트형 사방댐은 환경훼손을 최소화하기때문에 많이 사용되고 있는 추세이다. 그러나, 슬릿트형 사방댐의 배치에 따른 효율성에 관한 연구는 아직 미비한 상황이다. 본 연구에서는 슬릿트형 사방댐의 배치형태가 토석류 흐름에 미치는 영향을 토석류의 속도 감소와 포착율을 통해 분석하였다. 축소된 실내모형실험을 통해 토석류의 속도 변화와 포착율을 측정하였고, 이를 토대로 슬릿트형 사방댐의 성능 평가를 하였다. 축소모형 실험 결과는슬릿트형 사방댐 사이의 간격과 배치 각도가 슬릿트형 사방댐의 성능에 큰 영향을 주는 것으로 나타났다. Debris flows caused by heavy rainfall occur along long watersheds and travel at extremely rapid velocity. This phenomenon involves fast moving fluids induced by gravity and causes economic and societal damages when debris flows overflow to urban area. For this reason, barriers against debris flows have been widely employed. In particular, slit-type barriers are popularly used because of the minimum disturbance to surrounding environments. However, the performance of such slit-type barriers is not fully understood. This paper explores roles of spacing and angle of slit-type barriers on velocity reduction and trap ratio of the debris flows. The scaled physical modeling experiments were performed to examine the reduction of debris velocity and trap ratio and to assess the performance of debris flow barriers. The results indicate that the performance of barriers is heavily affected by spacing between slit-type barriers and angle of barriers from flow direction.

Dynamic Characteristics of a Urea SCR System for NOx Reduction in Diesel Engine

Nam, Jeong-Gil,Choi, Jae-Sung The Korean Society of Marine Engineering 2007 한국마린엔지니어링학회지 Vol.31 No.3

This paper discusses dynamic characteristics of a urea-SCR (Selective Catalytic Reduction) system. The urea flow rate to improve NOx conversion efficiency is generally determined by parameters such as catalyst temperature and space velocity. The urea-SCR system was tested in the various engine operating conditions governing the raw NOx emission levels, space velocity. and SCR catalyst temperature. These experiments include cold-transients to determine catalyst light-off temperature and urea flow rate transients. Likewise. ammonia storage dynamics was also investigated. The cold-transient results indicate the light-off temperature of the catalysts used in these experiments was $200-220^{\circ}C$. The ammonia storage and urea flow rate transients all indicate very slow dynamics (on the order of seconds) which presents control challenges for mobile applications. The results presented in this paper should provide an excellent starting point in developing a functional in-vehicle urea-SCR system.

Catalytic performance of a Ti added Pd/SiO2 catalyst for acetylene hydrogenation

Lingyu Zhao,Mingyuan Zhu,Bin Dai,Zhong Wei 한국공업화학회 2012 Journal of Industrial and Engineering Chemistry Vol.18 No.1

A series of Pd/SiO2 and Pd–Ti/SiO2 catalysts were prepared by the incipient wetness impregnation method. The catalytic performance for selective hydrogenation of acetylene to ethylene was measured under ‘‘high concentration acetylene’’, ‘‘high space velocity’’ and ‘‘no dilution gas’’ conditions. The crystal structure and particle size of the catalysts were characterized by the X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), nitrogen physisorption using the BET method and transmission electron microscope (TEM). The results showed that the titanium oxide in Pd–Ti/SiO2 catalyst was amorphous and the addition of Ti reduced the particle size of Pd significantly. Comparing to the Pd/SiO2catalyst, the ethylene yield increased from 64.1% to 88.3% under Pd–Ti/SiO2 catalytic system.

구리계 촉매를 이용한 VOC(벤젠)의 산화특성

박영성(Yeong-Seong Park),손현석(Hyun-Suk Son) 대전대학교 환경문제연구소 2007 환경문제연구소 논문집 Vol.11 No.-

Oxidation characteristics of benzene as a VOC was investigated using a fixed bed reactor system over copper base catalysts. The copper base catalysts were made by using copper nitrate reagent and various support materials such as γ-Al₂O₃, TiO₂, and zeolite. The parametric tests were conducted at the reaction temperature range of 200~500℃, benzene concentration of 1,000~2,000 ppm, and space velocity range of 5,000~20,000 hr^-1. The property analyses such as BET, SEM, XRD and the conversions of catalytic oxidation of VOC were examined. XRD analysis on copper catalysts showed CuO crystal forms and the peak intensity of CuO increased as the impregnation weight of copper grew. The experimental results showed that the conversion was increased with decreasing space velocity. It was also found that Cu/γ-Al₂O₃+TiO₂ catalyst showed the highest activity for the oxidation of benzene and 15% metal loading was the optimum impregnation level.

구리계 촉매를 이용한 VOC(벤젠)의 산화특성

박영성,손현석 대전대학교 환경문제연구소 2007 환경문제연구소 논문집 Vol.11 No.-

Oxidation characteristics of benzene as a VOC was investigated using a fixed bed reactor system over copper base catalysts. The copper base catalysts were made by using copper nitrate reagent and various support materials such as γ-Al2O3, TiO2, and zeolite. The parametric tests were conducted at the reaction temperature range of 200~500℃, benzene concentration of 1,000~2,000 ppm, and space velocity range of 5,000~20,000 hr-1. The property analyses such as BET, SEM, XRD and the conversions of catalytic oxidation of VOC were examined. XRD analysis on copper catalysts showed CuO crystal forms and the peak intensity of CuO increased as the impregnation weight of copper grew. The experimental results showed that the conversion was increased with decreasing space velocity. It was also found that Cu/γ-Al2O3+TiO2 catalyst showed the highest activity for the oxidation of benzene and 15% metal loading was the optimum impregnation level.