• Asian-Australasian Journal of Animal Sciences
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• 제19권9호
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• pp.1283-1290
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• 2006

The effect of substituting potato by-products based silage (PBS) for concentrates on ruminal fermentation, methane production and nitrogen utilization in Holstein steers was evaluated. Three growing Holstein steers ($490{\pm}19kg$, initial body weight) were used in a $3{\times}3$ Latin square experiment with three experimental diets in which PBS was included at (1) 0, (2) 19 and (3) 27%, on a dry matter basis, replacing concentrates and wheat bran. Increasing replacement levels of PBS slightly increased dry matter (DM), organic matter (OM), NDF and ADF intakes by the steers (p<0.05). Inclusion of PBS at 19% increased crude protein (CP) digestibility of the experimental diets compared with the control (p<0.05). Substitution with PBS increased ADF digestibility and nitrogen retention (p<0.05), but did not affect energy retention. Energy loss as methane ranged between 5.0 and 6.1% of the total gross energy intake. There were no significant differences in carbon dioxide and methane production among all PBS levels, while daily methane production numerically increased with PBS inclusion. Substituting PBS for concentrates did not significantly affect ruminal pH and ammonia N concentration. Total VFA concentration, VFA molar proportions and blood metabolites were also unaffected by PBS replacement. These results suggest that substitution of PBS up to 27% of diet dry matter did not significantly increase methane production and was equal or superior to concentrates in ADF digestibility and nitrogen retention for growing steers.

• 자원ㆍ환경경제연구
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• 제11권3호
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• pp.377-396
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• 2002

This paper investigates whether an inverted U relationship between pollution and economic development could be found in the Seoul metropolitan region using a panel data for the period of 1985~1999. We uses a model with a more flexible random coefficients specification which allows for a greater degree of regional heterogeneity. The emissions of sulfur dioxidetotal($SO_2$), suspended particulates(TSP), nitrogen dioxide($NO_2$), and carbon monoxide(CO) were selected as four major pollutants. We found that the emissions of these pollutants per capita except sulfur dioxidetotal exhibited inverted U shapes with per capita gross regional domestic product (GRDP). We also noted that the turning points for Seoul metropolitan region occured at a range of incomes, from $3,000 to $5,000 per capita.

• International Journal of Naval Architecture and Ocean Engineering
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• 제5권4호
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• pp.559-568
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• 2013

Increased worldwide concerns about fossil fuel costs and effects on the environment lead many governments and scientific societies to consider the hydrogen as the fuel of the future. Many researches have been made to assess the suitability of using the hydrogen gas as fuel for internal combustion engines and gas turbines; this suitability was assessed from several viewpoints including the combustion characteristics, the fuel production and storage and also the thermodynamic cycle changes with the application of hydrogen instead of ordinary fossil fuels. This paper introduces the basic environmental differences happening when changing the fuel of a marine gas turbine from marine diesel fuel to gaseous hydrogen for the same power output. Environmentally, the hydrogen is the best when the $CO_2$ emissions are considered, zero carbon dioxide emissions can be theoretically attained. But when the $NO_x$ emissions are considered, the hydrogen is not the best based on the unit heat input. The hydrogen produces 270% more $NO_x$ than the diesel case without any control measures. This is primarily due to the increased air flow rate bringing more nitrogen into the combustion chamber and the increased combustion temperature (10% more than the diesel case). Efficient and of course expensive $NO_x$ control measures are a must to control these emissions levels.

• Asian Journal of Atmospheric Environment
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• 제7권2호
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• pp.105-113
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• 2013

We constructed and tested an airborne peroxyacetyl nitrate (PAN) monitoring system based on luminol chemiluminescence detection with fast gas chromatography. This system allowed for simultaneous measurement of PAN and nitrogen dioxide ($NO_2$) with a time resolution of <2 min. Actual sample masses within the fixed volume sample loop at various altitudes and temperatures were adjusted to standard atmosphere, using measured pressures and temperatures. The airborne PAN measurement system was evaluated during two field studies above the southern Korean Peninsula in August and October 2009. The detection limit based on the ISO approach was 0.035 ppbv PAN, well below the observed concentrations of 0.185-1.49 ppbv during these studies. Under these conditions, the PAN mixing ratios were positively correlated with $O_x$ ($O_x=O_3+NO_2$), with slopes varying between 0.014 and 0.033 and intercepts between 22.6 and 55.1 ppbv $O_x$. The intercepts corresponded roughly to background $O_x$ mixing ratios in central Europe; however, the slopes were above the range of slopes reported in other studies. We also enhanced the durability, safety, and ease of maintenance of the PAN monitoring system by redesigning the structure of the conventional luminol cell.

• 한국대기환경학회지
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• 제28권3호
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• pp.249-260
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• 2012

Monitoring of climate change and atmospheric environment by satellite measurements has been increased in recent years. In this study, nitrogen dioxide ($NO_2$) measurements from Ozone Monitoring Instrument (OMI) were compared with surface measurements over the Korean peninsula. $NO_2$ from OMI measurements showed high values and also showed seasonal variations such as high concentration in winter and low in summer over metropolitan areas while $NO_2$ concentration at national background station was low and did not clearly show seasonal variations. Surface measurements showed similar temporal and spatial variations to those of satellite measurement. The comparison between satellite measurements and surface measurements showed that the correlation between them was higher in urban area (r=0.64 at Seoul and r=0.63 at Daegu) than in national background stations (r=0.37 at Jeju) because the concentration in urban area was relatively high so that the variation of $NO_2$ concentration could be detected better than at national background stations by satellite. Satellite can effectively measure the emission and transport of pollutants with no limitations in spatial coverage.

• 한국환경보건학회지
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• 제28권2호
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• pp.183-192
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• 2002

Indoor air quality is affected by source strength of pollutants, ventilation rate, decay rate, outdoor level and so on. Although technologies exist to measure these factors directly, direct measurements of all factors are impractical in most field studies. The purpose of this study was to develop an alternative methods to estimate these factors by multiple measurements. Daily indoor and outdoor NO$_2$concentrations for 21 days in 20 houses in summer and winter, Seoul. Using a mass balance model and linear regression analysis, penetration factor (ventilation divided by sum of air exchange rate and deposition constant) and source strength factor(emission rate divided by sum of air exchange rate and deposition constant) were calculated. Subsequently, the ventilation and source strength were estimated. During sampling period, geometric mean of natural ventilation was estimated to be 1.10$\pm$1.53 ACH, assuming a residential NO$_2$decay rate of 0.8 hr$^{-1}$ in summer. In winter, natural ventilation was 0.75$\pm$1.31 ACH. And mean source strengths in summer and winter were 14.8ppb/hr and 22.4ppb/hr, respectively. Although the method showed similar finding previous studies, the study did not measure ACH or the source strength of the house directly. As validation of natural ventilations, infiltrations were measured with $CO_2$tracer gas in 18 houses. Relationship between ventilation and infiltration was statistically correlated (Pearson r=0.63, p=0.02).

• 한국환경보건학회지
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• 제33권2호
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• pp.92-97
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• 2007

A series of source tests were conducted to characterize emissions of nitrogen oxide(NOx, NO, $NO_2$), carbon mon oxide(CO), carbon dioxide$(CO_2)$ and total VOCs from portable combustion devices in steady-state using well-mixed chamber. Since use of portable gas range is widespread in houses and restaurants in Korea, it is important to characterize the emission of air pollutants and suggest optimum ventilation rate. Ranges of emission rates of air pollutants from portable gas ranges were $NO \;0.551\sim0.939mg/hr,\;NO_2\;0.354\sim1.080mg/hr,\;NO_x\;1.207\sim1.631mg/hr,\;CO\;1.389\sim4.21mg/hr,\;CO_2\;2426.823\sim2973.495mg/hr$, and VOCs $0\sim0.119mg/h$. Mean of personal exposure and indoor environment level of $NO_2$ by combustion of portable gas range were 74.7 ppb and 65.4 ppb, respectively, suggesting persons using portable gas range in houses and restaurants might be highly exposed. Required ventilation rate to control the air pollutants emitted from portable gas range was maximumly $3.131m^3/hr$ on the basis of $NO_2$ indoor air quality standard.

• 한국환경과학회지
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• 제32권5호
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• pp.285-301
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• 2023

This study analyzed characteristics of ozone (O₃) formation regimes in Busan over a period of recent five years (2015~2019) and compared the findings with those obtained in Seoul. We employed four observed variations: early morning commuting-hour (i.e., 06:00-09:00 LST) nitrogen dioxide (NO₂), peak-hour (i.e., 12:00-16:00 LST) O₃, 8-hour average O₃ (MDA8 O₃), and △O₃ (=O_{3_max}- O_{3_min}) in Busan and Seoul. In addition, the NO₂-O₃ relation was assessed to interpret which of NOx-limited or volatile organic compound (VOC)-limited was dominant. In Busan, the annual mean O₃ concentration was relatively higher than in Seoul, whereas there were fewer high-concentration days. The Pearson correlation coefficients (R) between Early morning-hour NO₂ and the Peak-hour O₃ was positive (but close to zero) in Busan and negative in Seoul. Likewise, the R between the Early morning-hour NO₂ and the △O₃ showed a relatively considerable positive correlation (R=+0.4~0.5)(R=+0.4~0.5) in Busan, while a weak positive correlation (R=+0.1~0.2) in Seoul. From this result, it can be inferred that the O₃ formation regime in Busan was intrepreted to be nearly neutral or relatively closer to the NO_x-limited regime than Seoul, while Seoul to the VOC-limited regime. The study findings imply that O₃ control strategies should be applied differently in Busan and Seoul. The results here were inferred from surface NO₂ and O₃ observations, and the varification studies based on in-situ VOCs measurements would be needed.

• Asian Journal of Atmospheric Environment
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• 제12권2호
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• pp.127-138
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• 2018

This study measured indoor and outdoor levels of hydrocarbon volatile organic compounds (VOCs), such as benzene, toluene, ethylbenzene, and xylene isomers (collectively referred to as BTEX), as well as 13 carbonyl compounds, at 20 homes in Seoul, South Korea. Along with the sampling of BTEX and carbonyls, indoor concentrations of the air pollutants nitrogen oxide (NO) and carbon dioxide ($CO_2$) were also measured at each home. These measurements were used to understand the characteristics of BTEX and carbonyls by calculating the various ratios and correlation coefficients between measured contaminant levels. We found that carbonyls were mostly originated from indoor sources, while BTEX were originated from both indoor and outdoor sources. A high correlation between indoor levels of NO and BTEX indicated that traffic emissions were also an important sources of BTEX.

• Environmental Engineering Research
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• 제24권4호
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• pp.591-599
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• 2019

To convert sewage sludge to energy, drying-gasification characteristics during microwave heating were studied. During the gasification of carbon dioxide, the main products were gas, followed by char, and tar in terms of the amount. The main components of the producer gas were carbon monoxide and hydrogen including a small amount of methane and light hydrocarbons. They showed a sufficient heating value as a fuel. The generated tar is gravimetric tar, which is total tar. As light tars, benzene (light aromatic tar) was a major light tar. Naphthalene, anthracene, and pyrene (light polycyclic aromatic hydrocarbon tars) were also generated, but in relatively small amounts. Ammonia and hydrogen cyanide (precursor for NO_x) were generated from thermal decomposition of tar containing protein and nitrogen in sewage sludge. In the case of sludge char, its average pore diameter was small, but specific area, pore volume, and adsorption amounts were relatively large, resulting in superior adsorption characteristics.