• 대한금속재료학회지
• /
• 제49권9호
• /
• pp.732-738
• /
• 2011

Silicon oxide thin films were deposited by using a plasma-enhanced chemical-vapor deposition technique to investigate the light emission properties. The photoluminescence characteristics were divided into two categories along the relative ratio of the flow rates of $SiH_4$ and $N_2O$ source gases, which show light emission in the broad/visible range and a light emission peak at 380 nm. We attribute the broad/visible light emission and the light emission peak to the quantum confinement effect of nanocrystalline silicon and the Si=O defects, respectively. Changes in the photoluminescence spectra were observed after the post-annealing processes. The photoluminescence spectra of the broad light emission in the visible range shifted to the long wavelength and were saturated above an annealing temperature of $900^{\circ}C$ or after 1 hour annealing at $970^{\circ}C$. However, the position of the light emission peak at 380 nm did not change at all after the post-annealing processes. The light emission intensities at 380 nm initially increased, and decreased at annealing temperatures above $700^{\circ}C$ or after 1 hour annealing at $700^{\circ}C$. The photoluminescence behaviors after the annealing processes can be explained bythe size change of the nanocrystalline silicon and the density change of Si=O defect in the films, respectively. These results support the possibility of using a silicon-based light source for Si-optoelectronic integrated circuits and/or display devices.

• 한국대기환경학회:학술대회논문집
• /
• 한국대기환경학회 2008년도 춘계학술대회 논문집
• /
• pp.251-253
• /
• 2008

• 한국농공학회논문집
• /
• 제62권6호
• /
• pp.33-42
• /
• 2020

Emission factors for ammonia and particulate matters (PMs) from livestock buildings are of increasing importance in view of the environmental protection. While the existing emission factors were determined based on the emission inventory of other countries, in situ measurement of emission factors is required to construct an accurate emission inventory for Korea. This study is to report measurements of ammonia and PMs emissions from mechanically-ventilated pig houses, which are common types of pig barns in Korea. Ventilation rates and concentrations of ammonia and PMs were measured at the ventilation outlets of a weaner unit, a growing pig unit and a fattening pig unit to calculated the emission factors. The PMs emission was characterized with different aerodynamic diameters (PM_2.5, PM₁₀, and total suspended particulates (TSP)). The measured ammonia emission factors for weaners, growing pigs and fattening pigs were 0.225, 0.869 and 1.679 kg animal^-1 yr^-1, respectively, showing linear increase with pigs' age. The PMs emission factors for three growing stages were 0.023, 0.237 and 0.241 kg animal^-1 yr^-1, respectively for TSP, 0.017, 0.072 and 0.223 kg animal^-1 yr^-1, respectively for PM₁₀, and 0.011, 0.016 and 0.151 kg animal^-1 yr^-1, respectively for PM_2.5. PMs emissions were increased with pigs' age due to increasing feed supply and animal movement. The measured emission factors were smaller than those of the existing emission inventory indicating that the existing ones overestimate the emissions from pig buildings and also suggesting that long-term in situ monitoring at various livestock buildings is required to construct the accurate emission inventory.

• 한국환경농학회지
• /
• 제38권4호
• /
• pp.245-253
• /
• 2019

BACKGROUND: Weathering of bottom ash (BA) might induce change of its surface texture and pH and affect physical and chemical properties of soil associated with greenhouse gas emission, when it is applied to the arable soil. This study was conducted to determine effect of weathering of BA in mitigating emission of greenhouse gases from upland soil. METHODS AND RESULTS: In a field experiment, methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O) emitted from the soil was periodically monitored using closed chamber. Three month-weathered BA and non-weathered BA were applied to an upland soil at the rates of 0, 200 Mg ha^-1. Maize (Zea mays L.) was grown from July 1_st to Oct 8_th in 2018. Both BAs did not affect cumulative CH₄ emission. Cumulative CO₂ emission were 23.1, 19.8, and 18.8 Mg/ha/100days and cumulative N₂O emission were 35.8, 20.9, and 17.7 kg/ha/100days for the control, non-weathered BA, and weathered BA, respectively. Weathering of BA did not decrease emission of greenhouse gases significantly, compared to the weathered BA in this study. In addition, both BAs did not decrease biomass yields of maize. CONCLUSION: BA might be a good soil amendment to mitigate emissions of CO₂ and N₂O from arable soil without adverse effect on crop productivity.

• 한국토양비료학회지
• /
• 제45권6호
• /
• pp.1187-1193
• /
• 2012

Water control is mainly one of the key factors that can affect nitrous oxide ($N_2O$) emissions from soils. This study was undertaken to determine the effect of intermittent drainage compared to continuous flooding (conventional water regime) on $N_2O$ emission to global warming potential (GWP) with NPK (standard cultivation practice), NPK+Straw, and PK fertilizations. Nitrous oxide emission rates were collected twice a week using a closed chamber method. With continuous flooding, nitrogen (N) application increased $N_2O$ emission by 106.6% ($0.64kg\;ha^{-1}$ in NPK) with respect to the PK treatment ($0.31kg\;ha^{-1}$), and straw addition to NPK enhanced 148.3% of seasonal $N_2O$ flux ($0.77kg\;ha^{-1}$ in NPK+Straw). Although seasonal $N_2O$ emission slightly increased by 16.1-42.9% with intermittent irrigation, its seasonal $CH_4$ emission drastically reduced at 43.5-52.8% resulting in a lower GWP at 48.9-58.5% with respect to that of continuously flooded treatments ($4.51Mg\;CO_2\;ha^{-1}$, PK; $7.60Mg\;CO_2\;ha^{-1}$, NPK; $14.55Mg\;CO_2\;ha^{-1}$, NPK+Straw). Rice yield, at similar fertilization with the continuously-flooded rice field, was not affected by intermittent irrigation. Conclusively, intermittent irrigation can be very effective and a rational soil management strategy to mitigate GWP with considering rice productivity in a temperate paddy rice field like Korea.

• 한국환경농학회지
• /
• 제30권2호
• /
• pp.99-104
• /
• 2011

BACKGROUND: Application of urea may increase $CO_2$ emission from soils due both to $CO_2$ generation from urea hydrolysis and fertilizer-induced decomposition of soil organic carbon (SOC). The objective of this study was to investigate the effects of increasing urea application on $CO_2$ emission from soil and mineralization kinetics of indigenous SOC. METHODS AND RESULTS: Emission of $CO_2$ from a soil amended with four different rates (0, 175, 350, and 700 mg N/kg soil) of urea was investigated in a laboratory incubation experiment for 110 days. Cumulative $CO_2$ emission ($C_{cum}$) was linearly increased with urea application rate due primarily to the contribution of urea-C through hydrolysis to total $CO_2$ emission. First-order kinetics parameters ($C_0$, mineralizable SOC pool size; k, mineralization rate) became greater with increasing urea application rate; $C_0$ increased from 665.1 to 780.3 mg C/kg and k from 0.024 to 0.069 $day^{-1}$, determinately showing fertilizer-induced SOC mineralization. The relationship of $C_0$ (non-linear) and k (linear) with urea-N application rate revealed different responses of $C_0$ and k to increasing rate of fertilizer N. CONCLUSION(s): The relationship of mineralizable SOC pool size and mineralization rate with urea-N application rate suggested that increasing N fertilization may accelerate decomposition of readily decomposable SOC; however, it may not always stimulate decomposition of non-readily decomposable SOC that is protected from microbial decomposition.

• Membrane and Water Treatment
• /
• 제8권2호
• /
• pp.171-184
• /
• 2017

This study presents the effect of hydraulic retention time (HRT) on the characteristics of emission of three major greenhouse gases (GHGs) including $CH_4$, $CO_2$ and $N_2O$ during operation of a sequencing batch reactor for aerobic oxidation of methane with denitrification (AeOM-D SBR). Dissolved $N_2O$ concentration increased, leveled-off and slightly decreased as the HRT increased from 0.25 to 1d. Concentration of the dissolved $N_2O$ was higher at the shorter HRT, which was highly associated with the lowered C/N ratio. A longer HRT resulted in a higher C/N ratio with a sufficient carbon source produced by methanotrophs via methane oxidation, which provided a favorable condition for reducing $N_2O$ formation. With a less formation of the dissolved $N_2O$, $N_2O$ emission rate was lower at a longer HRT condition due to the lower C/N ratio. Opposite to the $N_2O$ emission, emission rates of $CH_4$ and $CO_2$ were higher at a longer HRT. Longer HRT resulted in the greater total GHGs emission as $CO_2$ equivalent which was doubled when the HRT increased from 0.5d to 1.0 d. Contribution of $CH_4$ onto the total GHGs emission was most dominant accounting for 98 - 99% compared to that of $N_2O$ (< 2%).

• 대한환경공학회지
• /
• 제28권7호
• /
• pp.713-720
• /
• 2006

일본 관동지역을 대상으로 PCBs의 대기 중 거동을 해석하기 위해 단일 구획상자모델을 사용하였으며, 대기 중 기온과 PCBs의 각 동족체의 거동사이의 관계를 시뮬레이션하였다. 또한 모델을 이용하여 대상 지역에 있어서의 PCBs의 년간 배출량과 침적량을 추산하였으며, 년간 배출량은 3,320 kg, 년간 침적량은 1,480 kg으로 예측되었다. 대기 중 PCBs의 제거기작(이류, 건성-습성 침적 및 반응) 중 이류의 기여는 전체의 약 $20{\sim}38%$로 나타났으며, OH라디칼 반응에 의한 감소는 무시할 정도로 작았다. 본 연구에서 사용한 단일 구획상자모델이 대기 중 PCBs의 거동을 이해하는데 활용될 수 있을 것으로 생각된다.

• 펄프종이기술
• /
• 제40권1호
• /
• pp.23-28
• /
• 2008

Functional hanji was manufactured using the bast fiber of Broussonetia kazinoki and various inorganic compounds such as kaolin, talc, elvan, and ocher, and the physical and optical properties were investigated. The residual percentages of kaolin, talc, elvan and ocher in the functional hanji were above 50%. The density of the hanji increased with the increase of the content of inorganic compounds. The hanji manufactured using ocher showed the highest density. The breaking length and burst factor decreased with the increase of inorganic materials, indicating that physical properties of hanji were not improved by adding inorganic materials. The emission rates of far-infrared radiation increased in the hanji manufactured using inorganic materials. The higher emission rates were observed in the hanji with elvan or ocher. Addition of inorganic compounds to hanji showed the flame retardative effect. The colorfastness to light of the hanji with elvan or ocher was the degree of 4, which explained by the characteristic color of the inorganics.

• 화훼연구
• /
• 제16권1호
• /
• pp.85-92
• /
• 2008

난의 종류별로 심비디움, 심비디움 교배종, 덴팔레, 온시디움, 호접란, 그리고 나도풍란의 음이온 발생량을 조사하였으며, 심비디움 20, 40, 60, 80%와 심비디움 교배종 25, 50, 75, 100%의 투입율에 따른 음이온 발생량의 변화를 조사하였다. 그 결과 심비디움 332개/$cm^3$, 심비디움 교배종 323개/$cm^3$로 심비디움 속이 가장 발생량이 많았으며, 그 다음이 덴팔레 250개/$cm^3$, 온시디움 203개/$cm^3$, 나도풍란 119개/$cm^3$, 호접란이 77개/$cm^3$ 순이었다. 투입율 증가에 따라 심비디움은 40%, 심비디움 교배종은 75%까지는 음이온 발생량이 증가하였으나, 그 이상 투입율에서는 다소 감소하는 경향이었다. 따라서 식물 종류별로 음이온 발생량을 상호 비교하기 위해서는 식물 투입율이 40% 이하가 적절하며, 상대습도 등을 감안할 경우 약 30% 정도가 가장 적절한 것으로 보인다.