This study evaluates the potential of various coagulants to enhance the efficiency of total phosphorus removal facilities in a sewage treatment plant. After analyzing the existing water quality conditions of the sewage treatment plant, the coagulant of poly aluminium chloride was experimentally applied to measure its effectiveness. In this process, the use of poly aluminium chloride and polymers in various ratios was explored to identify the optimal combination of coagulants. The experimental results showed that the a coagulants combination demonstrated higher treatment efficiency compared to exclusive use of large amounts of poly aluminium chloride methods. Particularly, the appropriate combination of poly aluminium chloride and polymers played a significant role. The optimal coagulant combination derived from the experiments was applied in a micro flotation method of real sewage treatment plant to evaluate its effectiveness. This study presents a new methodology that can contribute to enhancing the efficiency of sewage treatment processes and reducing environmental pollution. This research is expected to make an important contribution to improving to phosphorus remove efficiency of similar wastewater treatment plant and reducing the ecological impact from using coagulants in the future.
There are two primary sludge drying methods such as the direct heating microwave method and the indirect heating steam one. In this study, the drying treatment facility at sewage treatment plant A applied both of these drying methods. The research aimed to investigate the optimal operation approach for the drying facility, considering the input sludge and the moisture content data after the drying process. Moisture content and removal rate data were executed at the research facility from January 2016 to December 2018. First, the microwave, a direct heating drying method, performed intensive drying only on the outer surface of the sludge by directly applying heat to the sludge using far infrared rays, so effective sludge drying was not achieved. On the other hand, the steam method of the indirect heating method used steam from a gas boiler to maximize the utilization of the heat transfer area and reduce energy of the dryer, resulting in an effective sludge drying efficiency. The sludge moisture content brought into the sludge drying facility was about 80%, but the moisture content of the sludge that went through the drying facility was less than 10% of the design standard. Therefore, the steam method of the indirect heating method is more effective than the microwave method of the previous direct heating method and is more effective for maintenance It has proven that it is an efficient method of operating construction facilities.
본 연구를 통해 국내에 분포하는 중기문응애류 중 파리응애과의 Holostaspella crenulata Krantz, 1967 (톱니무늬파리응애, 신칭) 와 화살응애 과의 Lasioseius floridensis Berlese, 1916 (가슴선화살응애, 신칭) 를 처음으로 확인하고, 각 종에 대한 분류학적 진단과 분포정보, 성충의 현미경사 진과 도판을 제시하였다.
Wastewater management is increasingly emphasizing economic and environmental sustainability. Traditional methods in sewage treatment plants have significant implications for the environment and the economy due to power and chemical consumption, and sludge generation. To address these challenges, a study was conducted to develop the Intermittent Cycle Extended Aeration System (ICEAS). This approach was implemented as the primary technique in a full-scale wastewater treatment facility, utilizing key operational factors within the standard Sequencing Batch Reactor (SBR) process. The optimal operational approach, identified in this study, was put into practice at the research facility from January 2020 to December 2022. By implementing management strategies within the biological reactor, it was shown that maintaining and reducing chemical quantities, sludge generation, power consumption, and related costs could yield economic benefits. Moreover, adapting operations to influent characteristics and seasonal conditions allowed for efficient blower operation, reducing unnecessary electricity consumption and ensuring proper dissolved oxygen levels. Despite annual increases in influent flow rate and concentration, this study demonstrated the ability to maintain and reduce sludge production, electricity consumption, and chemical usage. Additionally, systematic responses to emergencies and abnormal situations significantly contributed to economic, technical, and environmental benefits.
Protein is an essential nutrient for humans to sustain life, but it is predicted that it will be challenging to secure protein through the traditional livestock industry in the future. Microalgae has high future value as an alternative protein food source due to resource utilization and sustainability advantages. In order to increase productivity, the culture conditions of microalgae, Chlorella vulgaris, Dunaliella salina, and Scenedesmus obliquus were examined in this study. The optimal culture conditions of C. vulgaris were mixotrophic culture, 25oC culture temperature, 7.0 initial pH, 10% initial inoculation, stirring culture, 3000 Lux light intensity, and 24L:0D light/dark cycle period with red LED. For D. salina, the optimal culture conditions were mixotrophic culture, 20oC culture temperature, 8.0 initial pH, 10% initial inoculation, stirring culture, 6000 Lux light intensity, and 12L:12D light/dark cycle period with white LED. For S. obliquus, the optimal culture conditions were mixotrophic culture, 30oC culture temperature, 8.0 initial pH, 10% initial inoculation, stirring culture, 4500 Lux light intensity, and 14L:10D light/dark cycle period with fluorescent light. These findings can be used as important information for increasing the production of microalgae as an alternative protein material resource in the future.
Lithium (Li) is a key resource driving the rapid growth of the electric vehicle industry globally, with demand and prices continually on the rise. To address the limited reserves of major lithium sources such as rock and brine, research is underway on seawater Li extraction using electrodialysis and Li-ion selective membranes. Lithium lanthanum titanate (LLTO), an oxide solid electrolyte for all-solid-state batteries, is a promising Li-ion selective membrane. An important factor in enhancing its performance is employing the powder synthesis process. In this study, the LLTO powder is prepared using two synthesis methods: sol-gel reaction (SGR) and solid-state reaction (SSR). Additionally, the powder size and uniformity are compared, which are indices related to membrane performance. X-ray diffraction and scanning electron microscopy are employed for determining characterization, with crystallite size analysis through the full width at half maximum parameter for the powders prepared using the two synthetic methods. The findings reveal that the powder SGR-synthesized powder exhibits smaller and more uniform characteristics (0.68 times smaller crystal size) than its SSR counterpart. This discovery lays the groundwork for optimizing the powder manufacturing process of LLTO membranes, making them more suitable for various applications, including manufacturing high-performance membranes or mass production of membranes.
The demand for energy is steadily rising because of rapid population growth and improvements in living standards. Consequently, extensive research is being conducted worldwide to enhance the energy supply. Transpiration power generation technology utilizes the vast availability of water, which encompasses more than 70% of the Earth's surface, offering the unique advantage of minimal temporal and spatial constraints over other forms of power generation. Various principles are involved in water-based energy harvesting. In this study, we focused on explaining the generation of energy through the streaming potential within the generator component. The generator was fabricated using sugar cubes, PDMS, carbon black, CTAB, and DI water. In addition, a straightforward and rapid manufacturing method for the generator was proposed. The PDMS generator developed in this study exhibits high performance with a voltage of 29.6 mV and a current of 8.29 μA and can generate power for over 40h. This study contributes to the future development of generators that can achieve high performance and long-term power generation.
한우 개량에 있어서 추정된 유전체육종가와 정확도는 선발에 중요한 지표로 사용되며, 최근 육종가 추정에 있어 정확도의 신뢰도를 높이기 위해 혈통과 유전체정보를 이용한 연구가 활발히 진행되고 있다. 따라서, 본 연구는 가계 내 유전체정보량에 따라 유전체정보가 미포함된 개체의 정확도 변화를 확인하고자 동일한 부모를 가진 한우 10두로 구성된 전형매 가계 3개를 수집하였으며, 각 가계 별로 유전체정보량을 10두, 8두, 6두, 4두, 2두씩 무작위로 선별하여 5가지의 검정집단으로 가정한 후 참조집단 14,225두를 이용하여 single step genomic best linear unbiased prediction (ssGBLUP)을 통해 genomic estimated breeding value (GEBV) 및 정확도를 추정하였다. 각 검정집단과 참조집단의 혈통 및 유전체정보 를 이용하여 H-matrix를 구축하였고, BLUPF90 program을 사용하여 도체중, 등심단면적, 등지방두께, 근내지방도의 GEBV 및 정확도를 추정하였 다. 첫 번째 가계를 대상으로 살펴보면, 검정집단에서 유전체정보를 보유하고 있는 10두의 GEBV 평균 정확도는 도체중 0.734, 등심단면적 0.717, 등지방두께 0.712, 근내지방도 0.745로 추정되었다. 이후 2두씩 무작위로 유전체정보를 제거하여 추정한 GEBV 정확도를 살펴보면, 유전체정보를 보유한 개체의 경우 정확도의 변화가 나타나지 않았지만, 유전체정보가 미포함된 개체의 정확도가 평균 0.114 ~ 0.168 낮게 추정되었다. 가계 내 유전체정보량에 따른 유전체정보가 미포함된 개체의 GEBV 평균 정확도는 도체중 0.604 ~ 0.576, 등심단면적 0.6 ~ 0.573, 등지방두께 0.599 ~ 0.572, 근내지방도 0.607 ~ 0.578로 평균 0.009씩 감소하는 것을 확인하였다. 이를 통해 가계 내 유전체정보량이 개체 별 유전체정보 유무와는 상관없이 GEBV의 정확도 추정에 큰 영향이 없었으며, 신뢰도가 높은 GEBV 추정을 위해서는 개체 별 유전체정보의 유무가 더 큰 영향을 미친다는 것을 확인하였다.
To provide information needed for managing fish resources and protecting the ecosystem of Cheonsu Bay, bimonthly variations in species composition and abundance of fish eggs and larvae were investigated. The samples were collected by using bongo net at three different stations from February 2020 to December 2021. Fish eggs were divided into Engrualis japonicus and unidentified eggs, of which Engragulis japonicus accounted for 85.6% of the total eggs collected. A total of 21 species representing 17 families and 6 orders were collected. The three dominant species were Gobiidae spp, Thryssa hamiltonii and E. japonicus and these three species accounted for 74.1% in the total number of individuals. The number of species was highest in August, 2020 and lowest in February, 2020 and 2021; the number of individuals was highest in August, 2020 and lowest in February, 2020. Temporal changes in the abundances of pelagic eggs and larval fishes corresponded with temperature.
This study was carried out to examine the physical characteristics of bacterial cellulose (BC) and its optimal culture condition using coffee by-products. Recently, recycling resources and employing eco-friendly materials have been raised as significant issues in the food industry. As the coffee industry develops, interests and efforts for recycling coffee wastes are also growing. This study attempted to confirm the production of BC by utilizing spent coffee grounds filtrate as a medium. In order to confirm the optimal culture conditions for BC production, different culture methods, initial pH, culture temperature, and culture period were examined. The optimal pH and temperature were 6.0 and 30oC, and the optimal culture period was 14 days. The cultivated BC was dried by hot air drying, freezedrying, and mold drying, respectively. Then, the properties of the BC films, such as tensile strength, elongation, water-solubility, thickness, and chromaticity were compared. The drying method affected the shape and structure of the final BC films. The production of BC film is expected to expand opportunities for recycling coffee by-products and contribute to solving environmental problems caused by food waste.
As coffee consumption increases, coffee extraction's by-products increase. Research on coffee by-product recycling is fundamental as social costs and environmental problems arise from the course of coffee processing, estimated to be 270,000 tons per year. This study attempted to confirm the possibility of an eco-friendly food packaging material by solvating cellulose from spent coffee grounds. For cellulose solubility, delignification and TEMPO (2,2,6,6- tetramethylpiperidin-1-oxyl) oxidation treatment were performed. An optimal plasticizer (glycerol) and a crosslinking agent (cinnamaldehyde) were added to the film-forming solution for film manufacturing, while physical treatment (high-pressure treatment, 276 MPa, 10 times) was done to improve physical properties. Then, the film was dried by a solution-casting method. Physical properties of food packaging materials such as tensile strength, elongation, water-solubility, thickness, and chromaticity were measured. In particular, the film to which 1.5% glycerol was added showed the highest value among the physical properties of the dried film. These results indicate that TEMPOSCG films have potential as eco-friendly food packaging materials in the food industry.
목적 : 멀티포컬 콘택트렌즈(MFCL) 착용 시 시각 피질에서 발생하는 ERP 변화를 확인하기 위하여 단초점 콘택트렌즈 착용 시 나타나는 ERP 변화와 비교하였다.
방법 : 안질환이 없는 근시안 20명 (여성 15명, 남성 5명, 평균 연령 24.00±0.51세)을 대상으로 하였으며, 단안 시력 0.00 logMAR 이하, -0.75 D 이상의 난시안, 0.50 D 이상의 부등시안, 조절력이 비정상적이거나 시력교정술을 받은 경우는 제외하였다. 단초점 콘택트렌즈(SVCL)와 낮은 가입도 중심부-근용 멀티포컬 콘택트렌즈를착용시킨 후 NeuroScan SynAmps 2 프로그램을 이용하여 시피질에서 일어나는 시각반응을 ERP로 기록하였다. P100 분석은 O1, O2 채널을 사용하고, N170 분석은 P7, PO7, P8 및 PO8 채널을 사용하였다. MFCL 착용 후 나타난 P100과 N170의 활성도(amplitude)와 반응시간(latency)은 SVCL 착용 후 나타난 값과 비교하였다.
결과 : MFCL 착용 시 단안과 양안에서의 P100 활성도는 SVCL 착용 시와 차이가 없었으나 P100 반응시간은 우세안에서 SVCL 착용 상태보다 길었다(p=0.036). MFCL 착용 시 우세안의 N170 활성도는 비우세안보다 작았고(p=0.001), 비우세안은 단초점 콘택트렌즈 착용 시보다 작았다(p=0.008). 그러나 양안에서 N170 활성도와 반응시간은 SVCL 착용 상태와 차이를 보이지 않았다(p=0.200), (p=0.249).
결론 : MFCL 착용 후 초기시각반응과 인식과정은 우세안에서는 저하되었지만, 양안 상태에서는 SVCL 착용시와 차이가 없었다. 따라서 MFCL 착용 후 나타나는 망막에 맺힌 흐린 상은 양안 융합과정에서 극복되어 시기능에 영향을 주지 않는 것으로 사료된다.