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Measurement and Prediction of Damage Threshold of Gold Films During Femtosecond Laser Ablation
Balasubramani, T.,Kim, S.H.,Jeong, S.H. Korean Society of Laser Processing 2008 한국레이저가공학회지 Vol.11 No.4
The damage threshold measurement of gold films is carried out with ultrashort-pulse laser. An enhanced two temperature model is developed to encounter the limitation of linear modeling during ultrashort pulse laser ablation. In which the electron heat capacity is calculated using a quantum mechanical approach based on a Fermi-Dirac distribution, temperature-dependent electron thermal conductivity valid beyond the Fermi temperature is adopted, and reflectivity and absorption coefficient are estimated by applying a temperature-dependent electron relaxation time. The predicted damage threshold using the proposed enhanced modelclosely agreed with experimental results, demonstrating the importance of considering transient thermal and optical properties in the modeling of ultrashort pulse laser ablation.
Simulation of the thermionic emission during ultrashort pulse laser ablation of metals
Balasubramani, T,Jeong, S H Institute of Physics Publishing Ltd 2007 Journal of Physics: Conference Series Vol.59 No.-
<P>The characteristics of thermionic emission of metal films during ultrashort pulse laser ablation are investigated by numerical simulation. The two-temperature model is used to calculate the electron and lattice temperatures while thermionic emission is incorporated into the model as a surface phenomenon. The Richardson-Dushman equation is employed to estimate the rate of thermionic electron emission. The influence of laser irradiance and the film thickness on the emission rate is examined. The change of quantum efficiency is predicted and compared with reported experimental data. The evolution of electron and lattice temperatures and the variation of relaxation time are also investigated in accordance with thermionic emission.</P>
Effect of Tributyltin Chloride on Survival, Growth and Reproduction in Zebra Fish Danio rerio
Balasubramani, A.,Pandian, T.J. The Korean Society of Fisheries and Aquatic Scienc 2008 韓國養殖學會誌 Vol.21 No.3
Tributyltin chloride(TBTCl) was administered through discrete immersion(2 hr each) from the $18^{th}-25^{th}$ day after hatching(dph). At the doses of 1, 2, 4 and 8 ${\mu}g/L$, the immersion at 2 ${\mu}g/L$ ensured 93% masculinization and the highest survival of 75% after the treatment. TBTCl acted as a growth suppressant and the magnitude of its suppression was stronger in females. During the 300 day experiment, it postponed sexual maturity of females from 120$^{th}$ dph in the control to 240$^{th}$ dph in the females treated at 8 ${\mu}g/L$. It reduced spawning frequency(22-3 times) and cumulative fecundity(1,632-19 eggs) by reducing the number of vitellogenic eggs. In the treated males too, it reduced sperm motility(100-68 sec); consequently, fertilizability of the sperm cells drawn from these males was also reduced from 88 to 43%. Progeny testing showed that the cross between males treated at>2 ${\mu}g/L$ and normal females generated the presumed 'homogametic' males. Both the treated 'homogametic' and 'heterogametic' males could induce the females to spawn fewer eggs than that of the normal males. A normal female somehow deducted the differences between the control, treated and sex reversed males; it preferred a normal male over a treated one, and a treated one over the sex reversed male.
Ravindran, Balasubramani,Nguyen, Dinh Duc,Chaudhary, Dhiraj Kumar,Chang, Soon Woong,Kim, Jaisoo,Lee, Sang Ryong,Shin, JoungDu,Jeon, Byong-Hun,Chung, SeokJoo,Lee, JaeJoung Elsevier 2019 Journal of environmental management Vol.232 No.-
<P><B>Abstract</B></P> <P>Excessive nutrients and toxic gas emissions from animal manure management are of great global concern, with negative environmental and economic consequences worldwide. Due to biochar recalcitrance and sorption properties, this study investigated the effect of the biochar(BC) derived from bamboo, amendment on swine manure(SM) composting efficiency through physical, physio-chemical, gaseous emissions, microbiological, and phytotoxic analysis during the 56 day process of in-vessel composting. The treatments were set-up from different ratios of biochar to swine manure mixed with sawdust(SD)(i.e. SM + SD + 3%BC(T1), SM:SD + 5 %BC(T2) and SM:SD + 10 %BC (T3)), while treatment without biochar amendment was used as a control, SM:SD(C). The results showed that, compared to the control, biochar amended compost mixtures had significantly reduced (p ≤ 0.05) bulk density, organic matter(OM), C:N ratio, NH<SUB>3</SUB> emission, pathogenic microorganisms, and phytotoxicity effect (Cress seed, <I>Lepidium sativum</I> Linn.). On the other hand, biochar amendment mixtures had increased total porosity, water holding capacity, rapid thermophilic temperature, and nitrate nitrogen. However, with the most prominent effects in terms of the nutrient quality and degradation rate of compost mixtures, the amendment of 10% biochar is recommended for swine manure management through the composting process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biochar was used as amendments for swine manure composting. </LI> <LI> 10% Biochar addition enhanced organic matter degradation. </LI> <LI> 10% Biochar amendment reduced C: N ratio, NH<SUB>3</SUB> emission and pathogenic microorganisms. </LI> <LI> 10% Biochar amendment reduced the phytotoxicity and improved the compost quality. </LI> </UL> </P>
Measurement and Prediction of Damage Threshold of Gold Films During Femtosecond Laser Ablation
T,Balasubramani,S,H,Kim,S,H,Jeong 한국레이저가공학회 2008 한국레이저가공학회지 Vol.11 No.4
The damage threshold measurement of gold films in carried out with ultrashort-pulse laser. An enhanced two temperature model is developed to encounter the limitation of linear modeling during ultrashort pulse laser ablation. In which the electron heat capacity is calculated using a quantum mechanical approach based on a Fermi-Dirac distribution, temperature-dependent electron thermal conductivity valid beyond the Fermi temperature is adopted, and reflectivity and absorption coefficient are estimated by applying a temperature-dependent electron relaxation time. The predicted damage threshold using the proposed enhanced modelclosely agreed with experimental results, demonstrating the importance of considering transient thermal and optical properties in the modeling of ultrashort pulse laser ablation.
활성탄 첨가에 따른 퇴비화 공정 중 발생하는 악취물질 저감에 관한 연구
노연희 ( Ro-yeon Hee ),바라스브라마니라빈드란 ( Ravindran-balasubramani ),장순웅 ( Chang-soon Woong ),신중두 ( Shin-joung Du ),심재홍 ( Shim-jae Hong ),정우진 ( Chung-woo Jin ) 한국환경농학회 2020 한국환경농학회 학술대회집 Vol.2020 No.-
국민의 삶의 질 향상으로 육류 소비량이 증가하여 국내 축산업의 형태는 기업형으로 확대되고 있는 추세이다. 축산업의 확대는 가축분뇨 증가에 기인하였으며 런던협약에 따라 가축분뇨 해양투기가 전면 금지되어 가축분뇨 처리에 관한 연구가 활발히 진행되었다. 퇴비화 방법은 미생물을 통해 유기물질을 분해시켜 비료로 전환하는 가장 대표적인 가축분뇨 자원화 기술이다. 가축분뇨는 높은 영양염류를 함유하고 있어 토양 작물의 영양원으로 적합하다. 호기성 퇴비화 공정은 타 공정에 비해 대량 처리가 가능하여 경제적이지만 악취 발생의 문제가 있다. 발생 된 악취는 인근 지역주민들의 민원을 발생시켜 퇴비화 공정 시 악취 저감의 연구가 필요한 실정이다. 활성탄은 다공성 탄소 물질로 물리ㆍ화학적으로 안정한 구조와 높은 비표면적을 가지고 있어 유해가스 흡착이 가능하다. 따라서 본 연구에서는 가축분뇨의 퇴비화 공정 중 악취물질 저감을 위해 활성탄을 첨가하여 그 효율을 평가하였다. 가축분뇨는 우분을 사용하였으며, 수분조절제는 톱밥을 사용하였다. 활성탄은 왕겨를 원료로 제조된 것을 사용하였고 각각 0 wt%, 5 wt%, 10 wt%, 15 wt%씩 첨가하였다. 호기성 조건을 위해 공기주입량을 0.1 L/minㆍkg로 설정하였고, 퇴비화 공정 시 발생 악취는 NH<sub>3</sub>, H<sub>2</sub>S를 측정하였다. NH<sub>3</sub>는 각각 1.67 L/kg, 1.26 L/kg, 1.11 L/kg, 0.98 L/kg 발생하였으며, H<sub>2</sub>S는 0.14 L/kg, 0.12 L/kg, 0.09 L/kg,0.08 L/kg 발생하였음을 확인하였다. 두 가스 모두 활성탄 첨가량 15 wt%에서 저감효율 41.3%,42.9%로 가장 높은 악취 저감 효율을 나타냈다. 활성탄 첨가에 따른 악취 저감효율이 높아졌으며, 악취 저감량은 10 wt% 와 15 wt%이 크게 상이하지 않았으며, 이는 활성탄의 공극 내 물리ㆍ화학적 흡착을 통해 저감 된 것으로 판단된다. 따라서 본 연구에 따라 퇴비화 공정 중 활성탄 첨가는 악취 저감을 위해 유용하게 사용될 수 있으며 이에 따라 안전한 축산물 생산에 기여할 것으로 예측된다.
계분의 퇴비화과정 중 활성탄 첨가에 따른 CO<sub>2</sub> 및 NH<sub>3</sub> 저감 연구
정석주 ( Seok-joo Chung ),라빈드란 ( Ravindran Balasubramani ),김지태 ( Ji-tae Kim ) 한국폐기물자원순환학회(구 한국폐기물학회) 2020 한국폐기물자원순환학회지 Vol.37 No.1
Composting livestock manure emits various air pollutants, including greenhouse gases. Because of the sorption properties of activated carbon, the effects of palm shell activated carbon on CO<sub>2</sub> and NH<sub>3</sub> reduction during composting of chicken manure were investigated. Tests were performed using chicken manure containing four different activated carbon contents: Treatment A, 0wt. %; Treatment B, 5wt. %; Treatment C, 10wt. %; and Treatment D, 15wt. %). For these tests, the moisture content was set to 65% in order to minimize the effects of moisture on gaseous emissions. During fifty days of composting, the temperature reached a maximum of 55℃ for tests B, C, and D at the thermophilic stage. The total amount of CO<sub>2</sub> produced in treatments A, B, C, and D was 4.08 m<sup>3</sup>, 3.44 m<sup>3</sup>, 2.54 m<sup>3</sup>, and 2.08 m<sup>3</sup>, respectively. Similarly, the total amount of NH<sup>3</sup> produced in tests A, B, C, and D was 0.03 m<sup>3</sup>, 0.025 m<sup>3</sup>, 0.020 m<sup>3</sup>, and 0.018 m<sup>3</sup>, respectively. For treatments A, B, and C, emissions of CO<sup>2</sup> and NH<sup>3</sup> decreased as the activated carbon content increased, but treatment D had a relatively limited effect. In addition, the highest microbial activity was observed in treatment C, and the palm shell activated carbon significantly decreased the pathogens in the compost. When factoring in the price of palm shell activated carbon, using chicken manure containing 10% palm shell activated carbon (treatment C) during composting is recommended in order to reduce CO<sub>2</sub> and NH<sub>3</sub> emissions.