• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.434-438
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• 2005

Nitrification characteristics and performance of wastewater treatment plants depend on not only temperature, pH, and dissolved oxygen of the wastewater but also species, distribution, and their metabolic stages of nitrifying bacteria. Due to their low specific growth rate, nitrifying bacteria are easy to wash out of the reactor and need long time to start-up and recover from damaged nitrifiers community. In order to overcome this limitation, nitrifying bacteria were coated on a polyurethane-based media. Laboratory and pilot-scale reactor had been designed and operated to compare the effect of coated nitrifying bacteria on wastewater nitrification efficiency and performance. Furthermore, the species and quantitative distribution of nitrifying bacteria were also investigated in the suspension and on the media. The results showed that nitrifier-coated reactor had better nitrification efficiency and performance than the control experiments. It also demonstrated that the amounts of total nitrifying bacteria of a coated reactor was higher than other reactors and it increased with operation time and wastewater temperature.

• KSBB Journal
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• v.5 no.3
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• pp.269-277
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• 1990

Methylobacillus sp. SK1, an obligate methylotroph, was cultivated in a fed-batch culture using DO as a methanol feeding indicator with a micro computer-aided control system. While 2.07g/l of cell density was obtained after 13 hr in the batch culture (initial methanol concentration: 1.0%(v/v)),45.3g/l of cell density was obtained after 17 hr by feeding methanol and metal ions in the fed-batch culture with oxygen supply. The high-density biomass was obtained in short cultuivation time by fed-batch culture with feedback control, and consequently the biomass productivity was significantly increased. It was mainly due to extension of logarithmic growth period by methanol feeding without methanol inhibition and intensive aeration without DO limitation with microcomputer-aided control system.

• Journal of Korean Society of Water and Wastewater
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• v.29 no.1
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• pp.33-38
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• 2015

In this study, flat-type photocatalytic reaction system is applied to reduce toxic hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)) in aqueous solution under UV irradiation. To overcome the limitation of conventional photocatalysis, a novel approach toward photocatalytic system for reduction of hexavalent chromium including nanotubular $TiO_2$ (NTT) on two kinds of titanium substrates (foil and mesh) were established. In addition, modified Ti substrates were prepared by bending treatment to increase reaction efficiency of Cr(VI) in the flat-type photocatalytic reactor. For the fabrication of NTT on Ti substrates, Ti foil and mesh was anodized with mixed electrolytes ($NH_4F-H_2O-C_2H_6O_2$) and then annealed in ambient oxygen. The prepared NTT arrays were uniformly grown on two Ti substrates and surface property measurements were performed through SEM and XRD. Hydraulic retention time(HRT) and substrate type were significantly affected the Cr(VI) reduction. Hence, the photocatalytic Cr(VI) reduction was observed to be highest up to 95% at bended(modified) Ti mesh and lowest HRT. Especially, Ti mesh was more effective as NTT substrate in this research.

• Natural Product Sciences
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• v.26 no.1
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• pp.28-49
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• 2020

The efficacy and side effects associated with anticancer drugs have attracted an extensive research focus. Onconephrology is an evolving field of nephrology that deals with the study of kidney diseases in cancer patients. Most renal diseases in cancer patients are unique, and management of renal disease can be challenging especially in the presence of continuing use of the nephrotoxic drugs. Cisplatin is one of the most important chemotherapeutic agents used in the treatment of various malignancies, such as head, neck, ovarian, and cervical cancers. The major limitation in the clinical use of cisplatin is its tendency to induce adverse effects, such as nephrotoxicity. Recently, plant-derived phytochemicals have emerged as novel agents providing protection against cisplatin-induced renal cytotoxicity. Owing to the diversity of phytochemicals, they cover a wide spectrum of therapeutic indications in cancer and inflammation and have been a productive source of lead compounds for the development of novel medications. Of these agents, the effectiveness of triterpenoids, isolated from various medicinal plants, against cisplatin-induced renal cytotoxicity has been reported most frequently compared to other phytochemicals. Triterpenes are one of the most numerous and diverse groups of plant natural products. Triterpenes ameliorate cisplatin-induced renal damage through multiple pathways by inhibiting reactive oxygen species, inflammation, down-regulation of the MAPK, apoptosis, and NF-κB signaling pathways and upregulation of Nrf2-mediated antioxidant defense mechanisms. Here, we reviewed recent findings on the natural compounds with protective potential in cisplatin-induced renal cytotoxicity, provided an overview of the protective effects and mechanisms that have been identified to date, and discussed strategies to reduce renal cytotoxicity induced by anticancer drugs.

• The Korean Journal of Food And Nutrition
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• v.28 no.6
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• pp.965-972
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• 2015

This study was conducted to evaluate the neuroprotective effects of Cheonggukjang extract in in-vitro and in-vivo models. T98G-human glioblastoma cells were pretreated with various concentrations (1~10 mg/mL) of Cheonggukjang extract for 24 h and then exposed to $H_2O_2$ (1 mM) for 3 h. The neuroprotective effects of Cheonggukjang extract were measured using a CCK-8 kit assay, total antioxidant capacity (TAC) assay, reactive oxygen species (ROS) assay, and lactate dehydrogenase (LDH) release assay. The early stage focal ischemia rodent model was used as the in-vivo neurotoxicity model. Various concentrations (10~200 mg) of Cheonggukjang extract were administered to the animal models for 1 week. Peripheral blood was analyzed for glutathione peroxidase (GPx) expression by ELISA, and infarct volume reduction was analyzed by TTC staining. Cheonggukjang extract significantly (p<0.05) increased cell viability in T98G cells against $H_2O_2$ as well as against the induced neurotoxicity. Indeed, treatment with the Cheonggukjang extract induced a decrease in ROS and LDH expression and increased TAC significantly (p<0.05). However, Cheonggukjang extract did not induce a decrease in infarct volume or an increase in GPx expression in the in-vivo model. Despite the limitation in neuroprotection, Cheonggukjang extract may be useful for treating ROS injury.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.5
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• pp.542-548
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• 2005

A fluidized bed reactor containing porous media has been known to be effective for nitrogen and organic matters removal in wastewater. The porous media which attached microbes plays important roles in simultaneous nitrification/denitrification (SND) due to coexistence of oxic, anaerobic and anoxic zone. For SND reaction, oxygen and organic substrates should be effectively diffused from wastewater into the intra-carrier zone. However, the overgrowth heterotrophic microbes at the surface of porous media may restrict from substrates diffusion. From these viewpoints, the existence and effect of heterotrophic bacteria at surface of porous media might be the key point for nitrogen removal. A porous media-membrane hybrid process was found to have improved nitrogen removal efficiency, due to stimulated denitrification as well as nitrification. Microelectrode studies revealed that although intra-media denitrification rate in a conventional fluidized bed was limited by organic carbon, this limitation was reduced in the hybrid process, resulting in the increased denitrification rate from 0.5 to $4.2\; mgNO_3-N/L/hr$.

• Applied Chemistry for Engineering
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• v.16 no.2
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• pp.217-225
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• 2005

Because of the limitation of controllable operation variables for the wastewater treatment process with variable hydrodynamic flow patterns, it may preclude the use of this type of nutrient removal activated sludge process. As the operation variables, only temperature and dissolved oxygen (DO) have been used to operate the process. This study made an effort to improve treatment efficiency and operability of the process by the following methodologies: 1) process and operation data analysis using process simulation, 2) determination of optimal control logic or algorithm using a pilot-scaled experimental apparatus and its operations, and 3) application of experimental and simulation results to find the optimal process operation modes. In this study, it was found that the optimal operation mode named 'save mode' in the basis of process variables, such as the ammonia-nitrogen concentration of inlet flow, temperature and flow rate, can reduce the operation cost comparing with the present normal operation mode. And the stable conditions in nitrification were also shown by the proportional control of DO with the inlet air flow rate of blower and the mixing rate of mechanical aeration.

• Journal of The Korean Society of Emergency Medicine
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• v.29 no.6
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• pp.585-594
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• 2018

Objective: This study was designed to report on the progress of the fire at Jecheon sports complex and to assess the adequacy of Disaster Medical Assistant Team (DMAT)'s activities in response to the fire disaster. Methods: We conducted a retrospective review based on camera recordings and medical records that were recorded at the disaster site for assessment of activities. We cooperated with firefighters, police officers, local hospital medical staffs and public health personnel in Jecheon in order to classify patients in the disaster field and to understand the patients' progress. Results: At 15:53, the first request for emergency rescue came to the 119 general emergency call center, and a request for DMAT activation came at 16:28. DMAT arrived at the site at 17:04 and remained active until the following day at 00:43. The total number of casualties was 60, including 27 minimal (Green) patients, 29 expectant (Black) patients, three delayed (Yellow) patients, and one immediate (Red) patient. There were 32 patients who received on-site care by DMAT. Two patients were transferred from a local hospital to Wonju Severance Christian Hospital for hyperbaric oxygen therapy. Conclusion: Twenty-nine victims were found in the sports complex building, and there were 31 mildly to moderately injured patients in this fire disaster. The main cause of death was thought to be smoke suffocation. Although DMAT was activated relatively quickly, it was not able to provide effective activity due to the late rescue and difficulty with fire suppression.

• Journal of the Korean Society of Propulsion Engineers
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• v.24 no.3
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• pp.59-70
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• 2020

Obtaining external forced convection heat transfer from bubble boiling and validating it with experimental results using cryogenic liquids are suggested to derive total heat transfer coefficient with pool boiling condition in the case of coil type heat exchanger with a bundle of tubes and to overcome the limitation of using the empirical correlation. Experiment is conducted with pool boiling heat transfer of saturate liquid nitrogen with helical coil type heat exchanger using liquid oxygen as hot stream fluid. Experimentally measured heat transfer coefficient is well-agreed with the estimated curve considering nucleate boiling and forced convection induced by bubble rise.

• Journal of Electrochemical Science and Technology
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• v.15 no.1
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• pp.168-177
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• 2024

Ni-rich cathode is one of the promising candidates for high-energy lithium-ion battery applications. Due to its specific capacity, easy industrialization, and good circulation ability, Ni-rich cathode materials have been widely used for lithium-ion batteries. However, due to the limitation of the co-precipitation method, including sewage pollution, and the instability of the long production cycles, developing a new efficient and environmentally friendly synthetic approach is critical. In this study, the Ni_0.91Co_0.06Mn_0.03CO₃ precursor powder was successfully synthesized by an efficient spray-drying method using carbonate compounds as a raw material. This Ni_0.91Co_0.06Mn_0.03CO₃ precursor was calcined by mixing with LiOH·H₂O (5 wt% excess) at 480℃ for 5 hours and then sintered at two different temperatures (780℃/800℃) for 15 hours under an oxygen atmosphere to complete the cathode active material preparation, which is a key component of lithium-ion batteries. As a result, LiNi_0.91Co_0.06Mn_0.03O₂ cathode active material powders were obtained successfully via a simple sintering process on the Ni_0.91Co_0.06Mn_0.03CO₃ precursor powder. Furthermore, the obtained LiNi_0.91Co_0.06Mn_0.03O₂ cathode active material powders were characterized. Overall, the material sintered at 780℃ shows superior electrochemical performance by delivering a discharge capacity of 190.76 mAh/g at 1^st cycle (0.1 C) and excellent capacity retention of 66.80% even after 50 cycles.