• Korean Chemical Engineering Research
• /
• v.51 no.5
• /
• pp.609-614
• /
• 2013

This study investigated the spontaneous combustion behavior of solvent-treated low rank coals. Indonesian lignite (a KBB and SM coal) and sub-bituminous (a Roto coal) were mixed with non-polar 1-methyl naphthalene (1MN) either by mechanical agitation or ultrasonication. The property change associated with 1MN treatment was then analyzed using proximate analysis, calorific value analysis, Fourier transform infrared (FT-IR), X-ray photoelectron spectroscopy and moisture re-adsorption test. Susceptibility to spontaneous combustion was evaluated using crossingpoint temperature (CPT) measurement along with gas analysis by GC. A FT-IR profile showed that oxygen functional groups and C-H bonding became weaker when treated by 1 MN. XPS results also indicated a decrease of the oxygen groups (C-O-, C=O and COO-). Increased hydrophobicity was found in the 1MN treated coals during moisture readsorption test. A CPT of the treated coals was ${\sim}20^{\circ}C$ higher than that of the corresponding raw coals and the ultrasonication was more effective way to enhance the stability against spontaneous combustion than the agitation. In the gas analysis less CO and $CO_2$ were emitted from 1MN treated coals, also indicating inhibition of pyrophoric behavior. The surface functional groups participating in the oxidation reaction seemed to be removed by the ultrasonication more effectively than by the simple mechanical agitation.

• Korean Journal of Agricultural and Forest Meteorology
• /
• v.20 no.1
• /
• pp.57-72
• /
• 2018

Time series analysis of tower flux measurement can be used to build quantitative evidence for the achievement of climate-smart agriculture (CSA). In this study, we have assessed the first objective of CSA (regarding ecosystem productivity and efficiency) for rice paddy-dominated heterogeneous farmland. A set of quantitative indicators were evaluated by analysing the time series data of carbon, water and energy fluxes over the Haenam farmland site in Korea (HFK) during the rice growing seasons from 2003 to 2015. Four different varieties of rice were cultivated during the study period in chronological order of Dongjin No. 1 (2003-2008), Nampyung (2009), Onnuri (2010-2011), and Saenuri (2012-2015). Overall at HFK, gross primary productivity (GPP) ranged from 800 to $944g\;C\;m^{-2}$, water use efficiency (WUE) ranged from 1.91 to $2.80g\;C\;kg\;H_2O^{-1}$, carbon uptake efficiency (CUE) ranged from 1.06 to 1.34, and light use efficiency (LUE) ranged from 0.99 to $1.55g\;C\;MJ^{-1}$. Among the four rice varieties, Dongjin No. 1-dominated HFK showed the highest productivity with higher WUE and LUE, but comparable CUE. Considering the heterogeneous vegetation cover at HFK, a rule of thumb comparison suggested that the productivity of Dongjin No1-dominated HFK was comparable to those of monoculture rice paddies in Asia, whereas HFK was more efficient in water use and less efficient in carbon uptake. Saenuri-dominated HFK also produced high productivity but with the growing season length longer than Dongjin No.1. Although the latter showed better traits for CSA, farmers cultivate Saenuri because of higher pest resistance (associated with adaptability and resilience). This emphasizes the need for the evaluation of other two objectives of CSA (i.e. system resilience and greenhouse gas mitigation) for complete assessment at HFK, which is currently in progress.

• Korean Journal of Environmental Agriculture
• /
• v.26 no.1
• /
• pp.62-68
• /
• 2007

Concerns about endocrine disrupting chemicals emitted from humans and animals have been increased because these compounds are detected at very low levels in environment and adversely affect on indigenous fauna. To date, there is little information regarding the concentration of these compounds in animal wastes. In this study, the female hormones, $17\beta-estradiol$ (E2), estrone (E1) and estriol, were measured to provide baseline data in animal wastes. Samples were collected from animal waste storage, methane digester and sludge separated wastewater and analyzed by gas chromatography-mass spectrometry. To measure the mass ratios of estrogen to macronutrients, nitrogen and phosphorous were also determined. Sample collected from animal waste storage had the highest estrogen concentration (98.7 ${\mu}g/L$), while sludge separated wastewater had the lowest concentration (3.4 ${\mu}g/L$). The mean concentrations of E2 and E1 in waste storage sample were (6.8 ${\mu}g/L$) and (68.7 ${\mu}g/L$), respectively. In sludge separated wastewater, the mean concentration of both E2 and E1 were reduced to (2.6 ${\mu}g/L$) and (1.9 ${\mu}g/L$), respectively. However, estriol was not detected in any of the samples collected. Mean ratios of E2 and E1 to macronutrients were significantly different between the methane wastewater and sludge separated wastewater owing to elimination of solid particles.

• Korean Journal of Organic Agriculture
• /
• v.21 no.4
• /
• pp.629-646
• /
• 2013

This study was conducted to investigate effects of terpenoids-rich plant extracts (TRPE) on the in vitro ruminal fermentation characteristics and methane production. The ruminal fluid was collected from a cannulated Hanwoo cow fed concentrate and timothy in the ratio of 6 to 4. The TRPE as Mint (Mentha arvensis var. piperascens), Pine (Pinus densiflora), Japan cedar (Cryptomeria japonica), Sichuan pepper (Zanthoxylum piperitum), Hinoki cypress (Chamaecyparis obtuse) and Japanese black pine (Pinus thunbergii) were used in this study. The 15 mL of mixture, contains McDougall buffer and rumen fluid in the ratio of 2 to 1. The mixture was dispensed anaerobically 50 mL serum bottles and it is contained 0.3 g timothy substrate and 5% TRPE. The bottles were incubated at $39^{\circ}C$ for 3, 6, 9, 12, 24, 48 and 72 hours. The pH value decrease by increased incubation times and the pH values at all times were significantly (p<0.05) higher in treatments than in control. The digestibility of dry matter at 3 hours was significantly (p<0.05) higher in mint treatment than in control. Productions of total gas and carbon dioxide at before 12 hours was significantly lower (p<0.05) in treatments than in control. The methane production at 24 hours was significantly (p<0.05) lower in treatments than in control. The concentrations of acetic acid and propionic acid at 24 hours were significantly higher (p<0.05) in mint and pine treatments than in control. In conclusion, the terpenoid-rich plant extracts were shown to decreased methane emission and without adversely affected ruminal fermentation. Therefore, the terpenoid-rich plant extracts as mint and pine were shown to decreased methane production and it has potential possibility for ruminal fermentations.

• Journal of Radiation Protection and Research
• /
• v.41 no.1
• /
• pp.49-55
• /
• 2016

Background: For the purpose of baseline data collection and enhancement of environmental monitoring the distribution studies of $^{137}Cs$ and $^{90}Sr$ in the soil of Uljin province was performed and the relation between surface soil activities and soil properties (pH, TOC and median of the surface soil) was analyzed. Materials and Methods: For 14 spots within 10 km from the NPP surface soil samples were collected and soils for depth profile were sampled for 3 spots in April 2011. Using ${\gamma}$-ray spectrometry with HPGe detector, the concentrations of $^{137}Cs$ were determined and the concentrations of $^{90}Sr$ were measured by counting ${\beta}$-activity of $^{90}Y$ (in equilibrium with $^{90}Sr$) in a gas flow proportional counter. Results and Discussion: The concentration ranges of $^{137}Cs$ and $^{90}Sr$ were $<0.479-39.6Bq{\cdot}(kg-dry)^{-1}$ (avg. $7.51Bq{\cdot}(kg-dry)^{-1}$) and $0.209-1.85Bq{\cdot}(kg-dry)^{-1}$ (avg. $0.74Bq{\cdot}(kg-dry)^{-1}$) which were similar to the reported values from other regions in Korea. The activity ratio of $^{137}Cs$ to $^{90}Sr$ in surface soils was around 9.67, which is much bigger than the initial value of 1.75 for worldwide fallouts because of faster downward movement of $^{90}Sr$ after fallout than that of $^{137}Cs$. For depth profile studies soils were collected down to 40 cm depth for the locations of Deokgu, Hujeong and Maehwa. The $^{137}Cs$ concentration distribution of the first two showed maximum values at top soils and decreased rapidly in exponential manner, while $^{90}Sr$ showed two local maximum values for soils near top and about 30 cm depth. Through linear fittings between the $^{137}Cs$ and $^{90}Sr$ concentrations of surface soil and pH, TOC and median of the surface soil, the only probable relationship obtained was between $^{137}Cs$ and TOC (determination coefficient $R^2=0.6$). Conclusion: The concentration ranges of $^{137}Cs$ and $^{90}Sr$ in Uljin were similar to the reported values from other regions in Korea. The only probable relationship obtained between activities and soil properties was between $^{137}Cs$ and TOC.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
• /
• v.7 no.1
• /
• pp.1-7
• /
• 2009

This study has been focused on determining the chemical composition of $^{14}C$ - in terms of both organic and inorganic $^{14}C$ contents - in reactor coolant from 3 different PWR's reactor type. The purpose was to evaluate the characteristic of $^{14}C$ that can serve as a basis for reliable estimation of the environmental release at domestic PWR sites. $^{14}C$ is the most important nuclide in the inventory, since it contributes one of the main dose contributors in future release scenarios. The reason for this is its high mobility in the environment, biological availability and long half-life(5730yr). More recent studies - where a more detailed investigation of organic $^{14}C$ species believed to be formed in the coolant under reducing conditions have been made - show that the organic compounds not only are limited to hydrocarbons and CO. Possible organic compounds formed including formaldehyde, formic acid and acetic acid, etc. Under oxidizing conditions shows the oxidized carbon forms, possibly mainly carbon dioxide and bicarbonate forms. Measurements of organic and inorganic $^{14}C$ in various water systems were also performed. The $^{14}C$ inventory in the reactor water was found to be 3.1 GBq/kg in PWR of which less than 10% was in inorganic form. Generally, the $^{14}C$ activity in the water was divided equally between the gas- and water- phase. Even though organic $^{14}C$ compound shows that dominant species during the reactor operation, But during the releasing of $^{14}C$ from the plant stack, chemical forms of $^{14}C$ shows the different composition due to the operation conditions such as temperature, pH, volume control tank venting and shut down chemistry.

• Journal of The Korean Society of Grassland and Forage Science
• /
• v.41 no.2
• /
• pp.102-109
• /
• 2021

In this study, the effect of forage sources in the total mixed ration (TMR) on in vitro goat rumen fermentation was investigated. Rice straw (RS), Italian ryegrass (IRG), timothy (TIM), and alfalfa (ALF) were used as forage sources. Each forage source was mixed with a commercial goat concentrate diet in the ratio of 1:1. Total 4 TMR were prepared. Rumen simulated in vitro fermentation using goat rumen fluid collected from the slaughterhouse was conducted until 72^th. For fermentation parameters, gas production (GP), volatile fatty acids (VFAs), and ammonia nitrogen (NH₃-N) were examined. All assays were performed at 24^th, 48^th, and 72^th h of incubation individually. Contents of crude protein and non-fibrous carbohydrate were greater in the order of RS < IRG < TIM < ALF. Significant treatment effects were found in valerate and NH₃-N at 24^th h of incubation (p<0.05). ALF showed the greatest contents of them and RS was the lowest. At 48^th incubation, a significant effect was detected at GP (p<0.05) and RS was greater than others. However, GP of RS was lower than others at 72^th. Significant effects on Total VFA, butyrate, and valerate productions were found at 72^th h of incubation (p<0.05). ALF showed the greatest production. Methane production from all treatments was not significantly different for each incubation time (p>0.05). The present study provided primary information on how goat rumen fermentation responds to different nutrient contents and forage sources of TMR. And the information could be used for the design or optimizing economical diet formulation for goats.

• Tuberculosis and Respiratory Diseases
• /
• v.42 no.3
• /
• pp.361-369
• /
• 1995

Background: A number of different weaning techniques can be employed such as spontaneous breathing trial, Intermittent mandatory ventilation(IMV) or Pressure support ventilation(PSV). However, the conclusive data indicating the superiority of one technique over another have not been published. Usually, a conventional spontaneous breathing trial is undertaken by supplying humidified $O_2$ through T-shaped adaptor connected to endotracheal tube or tracheostomy tube. In Korea, T-tube trial is not popular because the high-flow oxygen system is not always available. Also, the timing of extubation is not conclusive and depends on clinical experiences. It is known that to withdraw the endotracheal tube after weaning is far better than to go through any period. The tube produces varying degrees of resistance depending on its internal diameter and the flow rates encountered. The purpose of present study is to evaluate the effectiveness of weaning and extubation following a 60 minutes spontaneous breathing trial with simple oxygen supply through the endotracheal tube. Methods: We analyzed the result of weaning and extubation following a 60 minutes spontaneous breathing trial with simple oxygen supply through the endotracheal tube in 18 subjects from June, 1993 to June, 1994. They consisted of 9 males and 9 females. The duration of mechanical ventilation was from 38 hours to 341 hours(mean: $105.9{\pm}83.4$ hours). In all cases, the cause of ventilator dependency should be identified and precipitating factors should be corrected. The weaning trial was done when the patient became alert and arterial $O_2$ tension was adequate($PaO_2$ > 55mmHg) with an inspired oxygen fraction of 40%. We conducted a careful physical examination when the patient was breathing spontaneously through the endotracheal tube. Failure of weaning trial was signaled by cyanosis, sweating, paradoxical respiration, intercostal recession. Weaning failure was defined as the need for mechanical ventilation within 48 hours. Results: In 19 weaning trials of 18 patients, successful weaning and extubation was possible in 16/19(84.2 %). During the trial of spontaneous breathing for 60 minutes through the endotracheal tube, the patients who could wean developed slight increase in respiratory rates but significant changes of arterial blood gas values were not noted. But, the patients who failed weaning trial showed the marked increase in respiratory rates without significant changes of arterial blood gas values. Conclusion: The result of present study indicates that weaning from mechanical ventilation following a 60 minutes spontaneous breathing with $O_2$ supply through the endotracheal tube is a simple and effective method. Extubation can be done at the same time of successful weaning except for endobronchial toilet or airway protection.

• Analytical Science and Technology
• /
• v.24 no.4
• /
• pp.243-248
• /
• 2011

A selective determination method of mercury (II) ion in aqueous solution by luminol-based chemiluminescence system (luminol CL system) has been developed. Determination of metal ions such as copper (II), iron (III), chromium (III) ion in solution by the luminol CL system using its catalytic role in the reaction of luminol and hydrogen peroxide has been reported by several groups. In this study, the catalytic activity of mercury (II) ion in the reaction of luminol and hydrogen peroxide was observed by the enhanced CL intensity of the luminol CL system. Based on this phenomenon, experimental conditions of the luminol CL system were investigated and optimized to determine mercury (II) ion in aqueous solution. While mercury (II) ion in mixed sample solution containing mercury (I) and (II) ions highly enhanced the CL intensity of the luminol CL system, the mercury (I) ion could not enhanced the CL intensity. Thus selective determination of the mercury (II) ions in a mixture containing mercury (I) and (II) ions could be achieved. Each concentration of mercury (I) and (II) ions in aqueous solution can be obtained from the results of the CL method that give the concentration of only mercury (II) ion and the inductively coupled plasma (ICP) method that give the total concentration of mercury ions. On the optimized conditions, the calibration curve of mercury (II) ion was linear over the range from $1.25{\times}10^{-5}$ to $2.50{\times}10^{-3}M$ with correlation coefficient of 0.991. The detection limit of mercury (II) ion in aqueous solution was calculated to be $1.25{\times}10^{-7}M$.

• Tuberculosis and Respiratory Diseases
• /
• v.46 no.5
• /
• pp.645-653
• /
• 1999

Introduction : Although myocardial ischemia tends to occur more frequently than can he documented in ventilated patients, it has not been well studied on the factors related to the occurrence of the ischemia. Methods : To investigate the related factors to ischemia development, a prospective study was done in 95 cases with consecutive 73 patients who had received mechanical ventilation(MV) in MICU. In addition to 24 h holter monitoring, echocardiogram, electrolytes, cardiac enzymes, hemodynamic, and gas exchange measurements were done within 24 h after initiation of MV in 69 cases. The measurements were repeated at weaning period in 26 cases. The ischemia was defined by the ST segment changes; up-sloping depression more than 1.5 mm or down-sloping or horizontal depression more than 1.0 mm from isoelectric baseline for 80 ms following J point. Results : Twelve patients(12.6% in 95 cases) developed ischemia in total. The incidence of ischemia development showed an increased tendency in the initial 24 hr after MV (15.9%) and in patients with left-sided heart failure found by echocardiogram (18.2%) compared with that of the weaning period (3.8%) and patients without heart failure (10.9%) (P=0.12, P=0.09, in each). There were no differences in APACHE III score, baseline ECG findings, electrolytes abnormalities, use of inotropics or bronchodilators, presence of sepsis or shock, mode of ventilation, and survival rate according to the development of ischemia. Maximal heart rates and mean arterial pressure also were not different between patients with ($137.2{\pm}30.9/min$, $82.5{\pm}15.9$ mm Hg) and without ischemia ($l29.5{\pm}29.7/min$, $83.8{\pm}17.6$ mm Hg). Conclusion : Although the incidence of myocardial ischemia was 12.6% in total, there were no clinically predictable factors to the development of ischemia during mechanical ventilation.