• KSBB Journal
• /
• v.23 no.1
• /
• pp.90-95
• /
• 2008

In this study, a combined process of sequential anaerobic-aerobic digestion (SAAD), fluidized-bed bioreactor (FBBR), and ultrafiltration (UF) for the treatment of small scale food waste leachate was developed and evaluated. The SAAD process was tested for performance and stability by subjecting leachate from food waste to a two-phase anaerobic digestion. The main process used FBBR composed of aerators for oxygen supply and fluidization, three 5 ton reaction chambers containing an aerobic mesophilic microorganism immobilized in PE (polyethylene), and a sedimentation chamber. The HRTs (hydraulic retention time) of the combined SAAD-FBBR-UF process were 30, 7, and 1 day, and the operation temperature was set to the optimal one for microbial growth. The pilot process maintained its performance even when the CODcr of input leachate fluctuated largely. During the operation, average CODcr, TKN, TP, and salt of the effluent were 1,207mg/L, 100mg/L, 50 mg/L, and 0.01 %, which corresponded to the removal efficiencies of 99.4%, 98.6%, 89.6%, and 98.5%, respectively. These results show that the developed process is able to manage high concentration leachate from food waste and remove CODcr, TKN, TP, and salt effectively.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.18 no.2
• /
• pp.94-101
• /
• 2015

To mitigate the greenhouse gas emission, many carbon capture and storage projects are underway all over the world. In Korea, many studies focus on the storage of $CO_2$ in the offshore sediment. Assurance of safety is one of the most important issues in the geological storage of $CO_2$. Especially, the assessment of possibility of leakage and amount of leaked $CO_2$ is very crucial to analyze the safety of marine geological storage of $CO_2$. In this study, the leakage of injected $CO_2$ through fault was numerically studied. TOUGH2-MP ECO2N was used to simulate the subsurface behavior of injected $CO_2$. The storage site was 150 m thick saline aquifer located 825 m under the continental shelf. It was assumed that $CO_2$ leak was happened through the fault located 1,000 m away from the injection well. The injected $CO_2$ could migrate through the aquifer by both pressure difference driven by injection and buoyancy force. The enough pressure differences made it possible the $CO_2$ to migrate to the bottom of the fault. The $CO_2$ could be leaked to seabed through the fault due to the buoyancy force. Prior to leakage of the injected $CO_2$, the formation water leaked to seabed. When $CO_2$ reached the seabed, leakage of formation water stopped but the same amount of sea water starts to flow into the underground as the amount of leaked $CO_2$. To analyze the effect of injection rate on the leakage behavior, the injection rate of $CO_2$ was varied as 0.5, 0.75, and $1MtCO_2/year$. The starting times of leakage at 1, 0.75 and $0.5MtCO_2/year$ injection rates are 11.3, 15.6 and 23.2 years after the injection, respectively. The leakage of $CO_2$ to the seabed continued for a period time after the end of $CO_2$ injection. The ratios of total leaked $CO_2$ to total injected $CO_2$ at 1, 0.75 and $0.5MtCO_2/year$ injection rates are 19.5%, 11.5% and 2.8%, respectively.

• Journal of Animal Environmental Science
• /
• v.17 no.3
• /
• pp.163-170
• /
• 2011

This study was carried out to investigate greenhouse gas (GHG), $CH_4$ and $N_2O$, emission from liquid swine manure according to aeration levels in summer. To evaluate the influence of operation methods on GHG emissions, liquid swine manure were applied with different rates of aeration (store without aeration, $1m^3/ton/h$, $2.5m^3/ton/h$, and $5m^3/ton/h$). Following are the results of this study. The liquid swine manure applied no aeration, $1m^3/ton/h$, $2.5m^3/ton/h$, and $5m^3/ton/h$ aeration rates released 315.6, 13.9, 17.9 and $9.6{\mu}g/m^2/s$ of $CH_4$ and 0.173, 0.157, 0.131, and $0.241{\mu}g/m^2/s$ of $N_2O$, respectively. Liquid swine manure applied no aeration released the most amount of GHG ($6,681.4{\mu}g/m^2/s$ $CO_2$-Eq.) and followed by $5m^3/ton/h$ ($276.4{\mu}g/m^2/s$ $CO_2$-Eq.), $2.5m^3/ton/h$ ($416.0{\mu}g/m^2/s$ $CO_2$-Eq.), and $1m^3/ton/h$ ($340.8{\mu}g/m^2/s$ $CO_2$-Eq.). Our results reveal that the aerated system may reduce GHG emissions compared to no aeration. Consequently, aeration and mixing were effective at reducing GHG emissions during liquid swine manure storage.

• Journal of the Korean Society for Marine Environment & Energy
• /
• v.15 no.2
• /
• pp.67-75
• /
• 2012

Carbon-dioxide capture and storage (CCS) process is consisted by capturing carbon-dioxide from large point source such as power plant and steel works, transporting and sequestrating captured $CO_2$ in a stable geological structure. During CCS process, it is inevitable of introducing impurities from combustion, capture and purification process into $CO_2$ stream. Impurities such as $SO_2$, $H_2O$, CO, $N_2$, Ar, $O_2$, $H_2$, can influence on process efficiency, capital expenditure, operation expense of CCS process. In this study, experimental apparatus is built to simulate the behavior of $CO_2$ transport under various impurity composition and process pressure condition. With this apparatus, $N_2$ impurity effect on $CO_2$ mixture transportation was experimentally evaluated. The result showed that as $N_2$ ratio increased pressure drop per mass flow and specific volume of $CO_2-N_2$ mixture also increased. In 120 and 100 bar condition the mixture was in single phase supercritical condition, and as $N_2$ ratio increased gradient of specific volume change and pressure drop per mass flow did not change largely compared to low pressure condition. In 70 bar condition the mixture phase changed from single phase liquid to single phase vapor through liquid-vapor two phase region, and it showed that the gradient of specific volume change and pressure drop per mass flow varied in each phase.

• Tuberculosis and Respiratory Diseases
• /
• v.50 no.2
• /
• pp.213-221
• /
• 2001

Background : There is a well recognized interlaboratory variation in the results using the polymerase chain reaction(PCR) to detect the IS6110 sequence. The clinical utility of a commercially developed PCR test(Amplicor) in bronchial washings for detecting pulmonary tuberculosis in smear negative patients was evaluated. The sensitivity and specificity of Amplicor was compared with that of an in-house PCR test used for detecting the IS6110 sequence of Mycobacterium tuberculosis(M.tbc) in the bronchial washing fluid. Methods : 66 patients whose sputum smear for M. tbc were negative or who could not produce any sputum were recruited from January 1999 to July 1999. They all had a bronchoscopy performed to determine if there were signs of hemoptysis, patients who could not cough up sputum, lung lesion that exclude pulmonary tuberculosis. Pulmonary tuberculosis was diagnosed on the basis of a positive culture or a response to anti-tuberculosis therapy. Results : 19 patients with tuberculosis were identified and samples from 16 patients were later confirmed by culture. Bronchial washing for Amplicor PCR revealed a sensitivity, specificity, positive and negative predictive values of 94.7%, 97.9%, 94.7%, 97.9%, respectively. Using IS6110 based PCR, the sensitivity, specificity, positive and negative predictive values were of 73.7%, 87.2%, 70%, 89.1% respectively. Conclusion : Bronchial washing for Amplicor PCR proved to be more useful than IS6110 based PCR in rapidly diagnosing smear negative pulmonary pulmoary tuberculosis in patients where tuberculosis was likely to be differential and rapid diagnosis was essential for optimal treatment.

• Tuberculosis and Respiratory Diseases
• /
• v.40 no.4
• /
• pp.390-394
• /
• 1993

Background: Bronchiectasis is characterized by chronic sputum production and complications such as hemoptysis and repeated infections. Even though some patients are cured by surgical resection of bronchiectatic lesions, most bronchiectasis patients can not be treated surgically because of multiple site involvement, and they are treated by medical measures such as postura1 drainage and antibiotics when indicated. Recently there have been some reports that low-dose longterm erythromycin treatment is effective on bronchiectsis, and it is well known that low-dose longterm erythromycin treatment is the treatment of choice in diffuse panbronchiolitis which is characterized by chronic sputum production and dyspnea. To evaluate the efficacy of erythromycin, we tried erythromycin on twenty five stable bronchiectasis patients for more than six months. Methods: We tried erythromycin 250 mg b.i.d. for more than 6 months. We checked respiratory symptoms, chest PA, spirometry, and side effects before treatment and after 3 and 6 months of treatment. Results: 1) 32% of the patients showed marked improvement of symptoms and PFT. 32% showed slight improvement of symptoms with little change of PFT, and 36% showed no change of symptoms and signs. 2) Analysis of the patients showing marked improvement revealed that most of them had diffuse bronchiectasis and paranasal sinus involvement. Conclusion: These results suggest that low-dose longterm erythromycin treatment can be tried on diffuse bronchiectasis patients with sinus involvement. And further studies will be followed on the mechanism of erythromycin in bronchiectasis.

• Tuberculosis and Respiratory Diseases
• /
• v.47 no.4
• /
• pp.517-524
• /
• 1999

Background : Airway inflammation and hyperresponsiveness are recognized as major characteristics of bronchial asthma. Airway inflammation has usually been assessed by invasive methods, e.g. BAL or bronchial biopsy, but recent studies proposed induced sputum as another reliable and non-invasive tool to investigate airway inflammation in asthmatic patients. Thus, the relationship between airway inflammation assessed by induced sputum and airway hyperresponsiveness was investigated in asthmatic patient. Method : Airway responsiveness was determined by the concentration that caused a 20% decrease in $FEV_1$($PC_{20}$) after inhaling incremental concentrations of methacholine. The numbers of inflammatory cells and the concentration of eosinophilic cationic protein(ECP) were assessed in induced sputum obtained by inhalation of hypertonic saline(3%). Result: We analyzed sputum induced in 15 stable asthmatic patients. The differential cell count(%) of macrophages, neutrophils, eosinophils and lymphocytes in induced sputum were $39.1{\pm}27.0%$, $29.6{\pm}21.0%$, $28.8{\pm}18.8%$, $1.3{\pm}3.1%$ respectively. The mean value of baseline FEV1(predicted) and ECP were $76.3{\pm}30.3%$ and $1,101{\pm}833{\mu}g/L$ respectively. The geometric mean value of $PC_{20}$ was 0.56 mg/mL. The relationships between the sputum eosinophil and ECP in induced sputum, and between sputum eosinophil and degree of airway responsiveness($PC_{20}$) were found to be significantly correlated (r=0.81, p<0.05 and r=-0.78, p<0.05, respectively). Sputum neutrophils and $PC_{20}$ were not correlated to each other (r=0.11, p=0.69) and a significant negative correlation was found between ECP and baseline $FEV_1$(predicted)(r=-0.62, p<0.05). Conclusion : The results of this study suggest that an induced sputum via a inhalation of hypertonic saline is useful to determine a patient's status of airway inflammation, and airway inflammation is one of the major causal factors in the development of bronchial hyperresponsiveness in asthmatic patients.

• Korean Business Review
• /
• v.13
• /
• pp.49-66
• /
• 2000

Despite the fact that understanding customers satisfaction with transportation services is a subject of great importance, authors, so far, found no systematic researches referred to that issue. From this point, studying the satisfaction with subways services can be extremely useful. Empirical study of key factors in the satisfaction with subway services is the departure point, which holds as objectives, and we believe, will contribute to overall increasing in the number of subways services used and in the amount of public benefits derived from that usage. In order to achieve these goals: First, several items referred to some key factors in the satisfaction of subway usage were systemized. Second, a research of specific weights attached to those key factors by subway passengers was conducted. Knowledge of the satisfaction variables system can provide deep insights into ones perceptual experience when using a subway. The results were as follows: Various interrelated factors compose a passengers satisfaction with subway services. People do not just use subway passively; a number of key factors, like physical and personal services, exact timing, easiness to access etc. determine the passengers satisfaction with subway. In order to find out specific weights of these key factors multiple regression analysis was employed. Results showed that satisfaction with subway is determined by (in order of importance) easiness to access, quality of physical services, friendliness of working stuff and timing exactness. According to the findings, passengers do not use subway as a simple mean of transportation, rather they perceive it as a complex combination of environmental elements and overall satisfaction depends on these various factors. Therefore, to learn passengers satisfaction with subways services, passengers subway experience must be thoroughly studied and analyzed, and this is where papers value resides.

• Economic and Environmental Geology
• /
• v.35 no.3
• /
• pp.203-210
• /
• 2002

In order to elucidate the growth mechanism of sulfide chimney formed as a result of seafloor hydrothermal mineralization, we carried out the mineralogical and fluid inclusion studies on the inactive, sulfide- and silica-rich chimney which has been recovered from a hydrothermal field in the Cleft segment of the Juan de Fuca Ridge. According to previous studies, many active and inactive vents are present in the Cleft segment. The sulfide- and silica-rich chimney is composed of amorphous silica, pyrite, sphalerite and wurtzite with minor amounts of chalcopyrite and marcasite. The interior part of the chimney is highly porous and represents a flow channel. Open spaces within chimneys are typically coated with colloform layers of amorphous silica. The FeS content of Zn-sulfides varies widely from 13.9 to 34.3 mole% with Fe-rich core and Fe-poor rims. This variation possibly reflects the change of physicochemical characteristics of hydrothermal fluids. Chemical and mineralogical compositions of the each growth zone are also varied, possibly due to a thermal gradient. Based on the microthermometric measurements of liquid-rich, two-phase inclusions in amorphous silica that was precipitated in the late stage of mineralization, minimum trapping temperatures are estimated to be about 1140 to 145$^{\circ}$C with the salinities between 3.2 and 4.8 wt.% NaCI equiv. Although the actual fluid temperatures of the vent are not available, this study suggests that the lowtemperature conditions were predominant during the mineralization in the hydrothermal field at Cleft segment. Comparing with the previously reported chimney types, the morphology, colloform texture, bulk chemistry, and a characteristic mineral assemblage (pyrite + marcasite + wurtzite + amorphous silica) of this chimney indicate that the chimney have been formed from a relatively low-temperature (<250$^{\circ}$C) hydrothermal fluid that was changed by sluggish fluid flow and conductive cooling.

• Journal of Wetlands Research
• /
• v.15 no.1
• /
• pp.149-157
• /
• 2013

The weirs built so far are mainly overflow type weirs overflowing to the upstream. Main advantages of overflow type weirs are, effective water resources management and easy design, construction and maintenance due to many accumulated studies. However, due to the special feature of the overflow type weir where water overflows through the upstream of the weir, the silt coming from the upstream is not discharged to the downstream of the weir. This increases the river bed and reduces the reservoir capacity, and as a result, the weir loses its function. A underflow type weir with a water gate has been implemented in order to solve such sediment deposit and weir maintenance problems. However due to the design problem of recently constructed underflow type weirs, the river bed of the downstream of a weir has been scoured. And this leds to a structural problem. In this study, the flow characteristics of overflow type weirs and underflow type weir, hydraulic jump length analysis depending on change of water depth and the amount of specific energy loss generated per unit length depending on a weir type have been compared and analyzed, for the effective design and management of the weirs. The experiment results show that, when identical upstream conditions of underflow type weir and an overflow type weir were maintained, the hydraulic jump length was up to twice longer with Fr(Froude number) 3.5 of the hydraulic jump length at the underflow type weir, and the hydraulic jump length gradually decreased as the downstream water depth increased. The comparative analysis result of the amount of specific energy loss generated per unit length showed that the amount of energy loss per unit length was twice higher for an overlfow type weir than a underflow type weir. Therefore, in case of a underflow type facility, an additional energy reduction facility is determined to be necessary for safety of water construction structures.