국내 Y정수처리시설에 20-40 m3/m2/h의 표면부하율을 갖는 고속 용존공기부상공정을 도입하였다. 우선, 용존공기부상공정과 입상활성탄 공정이 결합된 반응기를 일처리용량 500 m3/day의 조건으로 운전하였다. 운전결과는 두 공정이 원수내 탁도, 조류, 지오스민, 2-MIB를 감소시킬 수 있음을 증명하였다. 도출된 최적 설계요소를 활용하여 현장규모의 공정(5,000 m3/day)에 용존공기부상공정을 도입하였다. 여름철 56일간 조류와 탁도 제거율을 평가하였다. 처리수 내 조류의 개체수는 20-30 cells/mL 이하로 유지되었으며, 조류 제거효율은 80-89%를 기록하였다. 침전법 및 용존공기부상공정 처리수질의 탁도 제거효율을 비교한 결과 평균 탁도 제거효율은 77%를 나타냈다. 이러한 결과들은 고속 용존공기부상공정이 여름철 음용수의 탁도 및 조류와 같은 저밀도 고형물을 제거하는데 유의미한 방법임을 나타냈으며, GAC는 맛･냄새를 유발하는 화합물(지오스민, 2-MIB)를 제거할 수 있는 공정 옵션인 것을 확인하였다.
우리나라의 수산 양식의 대부분이 이루어지는 연안과 내만에 최근 빈번한 고수온 현상으로 매년 막대한 양식 피해가 발생하고 있다. 2018년~2021년의 최근 4년간의 7월은 이례적인 고수온, 장마, 태풍 등에 의해 1990년 이후 수온의 연별 변동성이 1994년~1997년에 이 어 두 번째로 크게 나타났다. 동·서·남해의 대표적인 고수온 양식피해 우심해역(천수만, 가막만, 구룡포)에 대한 열속과 열수지 분석을 통 해 여름철 천수만과 가막만의 고수온 발생은 주로 대기로부터 해수면을 통한 열유입에 의한 것임을 확인하였다. 벌크식으로 계산한 순열 속과 수온변화로부터 계산한 해양 열 저장률로부터 4년간(2018년~2021년)의 7월 평균 해양 열 수송률을 추산한 결과, 서산 창리는 순열속 의 13.5 %, 여수 신월은 순열속의 62.3 %가 외부로 유출되는 것으로 계산되었다, 구룡포 하정은 순열속의 22.2 %가 평균적으로 외부로 유출 되는 것으로 평가되었으나, 냉수대 발생 유무에 따라 연도별로 해양 열 수송률이 순열속의 -174.5 %에서 132.5 %까지 큰 차이를 보였다.
Designing and producing a low-cost, high-current-density electrode with good electrocatalytic activity for the oxygen evolution reaction (OER) is still a major challenge for the industrial hydrogen energy economy. In this study, nanostructured Fe-doped CuCo(OH)2 was discovered to be a precedent electrocatalyst for OER with low overpotential, low Tafel slope, good durability, and high electrochemically active surface sites at reduced mass loadings. Fe-doped CuCo(OH)2 nanosheets are made using a hydrothermal synthesis process. These nanosheets are clumped together to form a highly open hierarchical structure. When used as an electrocatalyst, the Fe-doped CuCo(OH)2 nanosheets required an overpotential of 260 mV to reach a current density of 50 mA cm−2. Also, it showed a small Tafel slope of 72.9 mV dec−1, and superior stability while catalyzing the generation of O2 continuously for 20 hours. The Fe-doped CuCo(OH)2 was found to have a large number of active sites which provide hierarchical and stable transfer routes for both electrolyte ions and electrons, resulting in exceptional OER performance.
In this work, the sulfonic acid group was introduced into the resorcinol–formaldehyde (RF) microspheres by the addition of p-phenolsulfonic acid during the polycondensation process of RF. The hydrophilicity of the sulfonated RF allowed KOH to infiltrate inside the microspheres, which enhanced the formation of mesopores in the carbon microspheres during the activation process by KOH. SEM and TEM observations and N2 adsorption measurements verified the formation of abundant mesopores in the porous carbon microspheres. The BET surface area of these mesoporous carbons exceeded 2000 m2/ g. In 17 m NaClO4 “water-in-salt” (WIS) electrolyte-based supercapacitor, the synthesized mesoporous carbon exhibited high specific capacitance of 170 F/g at current density of 0.5 A/g, comparable to those in regular KOH electrolyte. When graphite was used as current collectors, the symmetric cell could operate at 2.5 V, and the mesoporous carbon exhibited an energy density of 43 Wh/kg at power density of 0.25 kW/kg, and 25 Wh/kg at power density of 6.25 kW/kg, respectively, which were superior to those using Pt or stainless steel as current collectors. The mesoporous carbon/graphite was an excellent electrode in new-generation “WIS” electrolyte-based high-voltage supercapacitor due to their high energy and power density.
The present study is designed to investigate the hypolipidemic effect of the hot-water extract from the leaves of Dendropanax morbifera L. (DMWE) in hyperlipidemic rats. Thirty male 5-week-old rats were grouped as follows: Normal control (NC) given distilled water; hyperlipidemic control (HC) administered with distilled water; drug treatment (DT) orally administered with atorvastatin (10 mg/kg body weight (BW)); DMWE-treated groups (DM-50, DM-100 and DM-200) treated with DMWE 50, 100 and 200 mg/kg BW, respectively. All groups (except for NC) were fed a high-fat diet during the experiment. After 4 weeks of administration, the BW of all groups treated with DMWEs significantly increased compared to that of HC (p<0.05) and showed no significant difference compared to that of NC. In addition, serum total cholesterol levels in all groups treated with DMWEs were meaningfully decreased, compared to that in HC (p<0.05). In serum triglyceride (TG) and low-density lipoprotein-cholesterol levels, both DM-100 and DM-200 considerably decreased compared to HC (p<0.05), and no significant differences in TG levels were between DM-100 and DM-200. In high-density lipoprotein-cholesterol levels, DM-200 was statistically different compared to HC, and there were no significant differences between DM-100, DM-200 and DT. Furthermore, aspartate transaminase and alanine aminotransferase concentrations of DM-100 and DM-200 were significantly decreased compared to those of HC (p<0.05). From results portrayed above, DMWE at the concentration of 100 mg/kg BW has been identified to be effective in the treatment of hyperlipidemic rats.
High-pressure membrane system like nanofiltration(NF) and reverse osmosis(RO) was investigated as a part of water treatment processes to produce high quality potable water with low organic matter concentration through membrane module tests and design simulation. River water and sand filtration permeate in Busan D water treatment plant were selected as feed water, and NE4040-90 and RE4040-Fen(Toray Chemical Korea) were used as NF and RO membranes, respectively. Total organic carbon(TOC) concentrations of NF and RO permeates were mostly below 0.5 mg/l and the average TOC removal rates of NF and RO membranes were 93.99% and 94.28%, respectively, which means NF used in this study is competitive with RO in terms of organic matter removal ability. Different from ions rejection tendency, the TOC removal rate increases at higher recovery rates, which is because the portion of higher molecular weight materials in the concentrated raw water with increasing recovery rate increases. Discharge of NF/RO concentrates to rivers may not be acceptable because the increased TDS concentration of the concentrates can harm the river eco-system. Thus, the idea of using NF/RO concentrate as the raw water for industrial water production was introduced. The design simulation results with feed water and membranes used in this work reveal that the raw water guideline can be satisfied if the recovery rate of NF/RO system is designed below 80%.
In the membrane process, it is important to improve water treatment efficiency to ensure water quality and minimize membrane fouling. In this study, a pilot study of membrane process using reservoir water was conducted for a long time to secure high flux operation technology capable of responding to influent turbidity changes. The raw water and DAF(Dissolved Air Flotation) treated water were used for influent water of membrane to analyze the effect of water quality on the TMP (Trans Membrane Pressure) and to optimize the membrane operation. When the membrane flux were operated at 70 LMH and 80 LMH under stable water quality conditions with an inlet turbidity of 10 NTU or less, the TMP increase rates were 0.28 and 0.24 kPa/d, respectively, with minor difference. When the membrane with high flux of 80 LMH was operated for a long time under inlet turbidity of 10 NTU or more, the TMP increase rate showed the maximum of 43.5 kPa/d. However, when the CEB(Chemically Enhanced Backwash) cycle was changed from 7 to 1 day, it was confirmed that the TMP increase rate was stable to 0.23 kPa/d. As a result of applying pre-treatment process(DAF) on unstability water quality conditions, it was confirmed that the TMP rise rates differed by 0.17 and 0.64 kPa/d according to the optimization of the coagulant injection. When combined with coagulation pretreatment, it was thought that the balance with the membrane process was more important than the emphasis on efficiency of the pretreatment process. It was considered that stable TMP can be maintained by optimizing the cleaning conditions when the stable or unstable water quality even in the high flux operation on membrane process.
This study was carried out to produce stable evening primrose oil in water emulsion by using various emulsifier with HLB (8.6, 12, 16.7), concentration (0-45%) and emulsification methods such as high-speed emulsification (7,000 rpm, 2 min) and high-pressure homogenization (10,000 psi, 1 cycle). And then properties of evening primrose oil in water emulsion was evaluated with keeping at room temperature and 40oC during 28 days. Lower HLB 8.6 and high viscosity emulsifier added emulsions were not appropriate for high-pressure homogenization and were separated in a day. The optimum emulsification condition was HLB 12 and high-pressure homogenization (10,000 psi, 1 cycle) for evening primrose oil in water emulsion. These emulsions produced by optimum condition were not separated with the aqueous phase and the oil phase and they were nano-sized around 200 nm, higher zeta-potential (±mV), mono-polydispersed (<0.3), and less oxidized (<0.4) during 28 days.
본 연구는 국내의 고온다습한 하절기에 산란계에 음용수 온도가 생산성, 호르몬 농도 및 혈액성상에 미치는 영향을 구명하고자 실행하였다. 52주령 하이라인 갈색종 산란계 432수를 3개 처리구와 8반복으로 반복당 18수씩 케이지 사육장(550 cm2/수)에 배치하였고, 처리구별로 14.5, 24.0 및 32.5℃의 음용 수를 4주간 급수하였다. 산란계의 생산성은 산란율과 난중을 매일 조사하여 계산하였고, 호르몬, 혈액 성상 및 계란품질은 사양실험 종료 후 채집하여 분석하였다. 본 연구결과 산란율과 1일 산란양은 14.5℃ 의 급수구에서 유의적으로 개선되었고(p<0.05), 사료섭취량과 난중은 14.5와 24.0℃ 급수구에서 32.5℃ 에 비하여 현저히 증가하였다(p<0.05). 계란의 난백높이와 호우유닛은 음용수 온도에 따른 처리구간 통계적 차이가 없었다. 난각강도는 14.5℃ 급수 처리구에서 증가하였고(p<0.05) 난각두께도 개선되는 경향을 보였지만 처리구간에 통계적 차이는 없었다. 또한 혈청과 간의 GH와 IGF-I 농도는 32.5, 24.0 및 14.5℃ 급여구 순서로 증가하였고(p<0.05), 코티코스테론은 감소되었는데 14.5℃에서 가장 개선되었다(p<0.05). 이외에도 혈중 AST와 콜레스테롤은 14.5℃의 음용수 처리구에서 24.0과 32.5℃에 비하여 유의적으로 감소하였고(p<0.05), HDL콜레스테롤, 단백질 및 글루코오스는 처리구간에 통계적 차이가 없 었지만, 혈중 중성지방은 14.5℃처리구에서 현저하게 감소되었다(p<0.05). 그러므로 여름철 14.5℃의 음용수를 급여하면 산란계에서 고온스트레스를 저감하므로서 생산성, 계란품질 및 혈액성상을 개선하였다.
During the winter of 2017/2018, significantly low water temperatures were detected around the western and southern coasts of Korea (WSCK). In this period, sea surface temperature (SST) in the Korea Waters was about 2℃ lower than mean temperature. Using the real-time observation system, we analyzed the temporal variation of SST during this period around the western and southern coasts. Low water temperature usually manifested over a period of about 10 ~ 20 days. The daily Arctic oscillation index was also similarly detectable with the variation of SST. From the cross-correlation function, we compared two periodic variations, which were SST around the WSCK and the Arctic oscillation index. The cross correlation coefficients between both variations were approximately 0.3 ~ 0.4. The time lag of the two time series was about 6 to 7 days. Therefore, significanlyt low water temperatures during winter in the Korean coastal areas usually became detectable 6 to 7 days after the negative peak of Arctic oscillation.