Recently, the demand for shape memory alloys in the biomedical industry is increasing. Nitinol alloy, which accounts for most of the shape memory alloy market, occupies most of the biomedical field. Nitinol for biomaterials requires a clean surface without sub-micron surface integrity and surface defects in order to be used more safely in a living body. Among them, new technologies such as polishing using MR fluid are being studied, but there is a disadvantage in that it takes a long time for processing due to a low material removal rate. In this study, material removal studies were conducted for effective polishing, and excellent polishing properties of MR fluid were confirmed.

This study was performed to evaluate the pollutants removal characteristics of two types of RBFs(Riverbank filtration, Riverbed filtration) intake facilities installed in Nakdong River and in Hwang River respectively. The capacity of each RBF is 45,000 ㎥/d for riverbank filtration intake facility and 3,500 ㎥/d for riverbed filtration intake facility. According to data collected in the riverbank filtration site, removal rate of each pollutant was about BOD(Biochemical oxygen demand) 52%, TOC(Total organic carbon) 57%, SS(Suspended solids) 44%, Total coliforms 99% correspondingly. Furthermore, Microcystins(-LR,-YR,-RR) were not found in riverbank filtered water compared to surface water in Nakdong River. DOC(Dissolved organic carbon) and Humics which are precursors of disinfection byproduct were also reported to be removed about 59% for DOC, 65% for Humics. Based on data analysis in riverbed filtration site in Hwang River, removal rate of each contaminant reaches to BOD 33.3%, TOC 38.5%, SS 38.9%, DOC 22.2%, UV254 21.2%, Total coliforms 73.8% respectively. Additionally, microplastics were also inspected that there was no obvious removal rate in riverbed filtered water compared to surface water in Hwang River.

Perfluorooctanoic acid(PFOA) was one of widely used per- and poly substances(PFAS) in the industrial field and its concentration in the surface and groundwater was found with relatively high concentration compared to other PFAS. Since various processes have been introduced to remove the PFOA, adsorption using GAC is well known as a useful and effective process in water and wastewater treatment. Surface modification for GAC was carried out using Cu and Fe to enhance the adsorption capacity and four different adsorbents, such as GAC-Cu, GAC-Fe, GAC-Cu(OH)2, GAC-Fe(OH)3 were prepared and compared with GAC. According to SEM-EDS, the increase of Cu or Fe was confirmed after surface modification and higher weight was observed for Cu and Fe hydroxide(GAC-Cu(OH)2 and GAC-Fe(OH)3, respectively). BET analysis showed that the surface modification reduced specific surface area and total pore volumes. The highest removal efficiency(71.4%) was obtained in GAC-Cu which is improved by 17.9% whereas the use of Fe showed lower removal efficiency compared to GAC. PFOA removal was decreased with increase of solution pH indicating electrostatic interaction governs at low pH and its effect was decreased when the point of zero charges(pzc) was negatively increased with an increase of pH. The enhanced removal of PFOA was clearly observed in solution pH 7, confirming the Cu in the surface of GAC plays a role on the PFOA adsorption. The maximum uptake was calculated as 257 and 345 μg/g for GAC and GAC-Cu using Langmuir isotherm. 40% and 80% of removal were accomplished within 1 h and 48 h. According to R2, only the linear pseudo-second-order(pso) kinetic model showed 0.98 whereas the others obtained less than 0.870.

This study focused on using indirect filtration through riverbeds to produce high-quality drinking water. Data on water quality from a water intake facility(capacity 10,000 m3/day) and nearby rivers were collected over a three-year period. The average intake facility specifications were found to be a specific surface area of 58 balls/m2, a mean particle size of 24 mm, an inflow velocity of 2.2 cm/sec, and a burial depth of 5 m. The water quality improvement rate was assessed as grade Ia, surpassing the adjacent river’s water quality. Correlation analysis showed a weak correlation between opening ratio, Suspended Solid (SS), and Biochemical Oxygen Demand (BOD) compared to total coliforms and fecal coliforms. The correlation coefficient R value of SS was -0.614, BOD was –0.588, total coliforms -0.870, and fecal coliforms -0.958. The R value shows a negative value, which showed that the larger the opening rate, the lower the removal rate of water pollutants. The correlation coefficient R values according to the depth of burial were found to be BOD 0.914, SS-0.124, total coliforms 1.000, and fecal coliforms 0.866. The deeper the burial depth, the higher the removal rate of BOD and microbial groups.

The performance characteristics and usefulness of the duct-type gas removal system to which the catalytic combustion method was applied were investigated by experiment. Benzene, toluene, ethylbenzene, and xylene were selected for performance tests on gas detection and removal of the catalytic combustion system. Accelerated experiments were performed to evaluate the gas sensing performance, the adsorption performance of activated carbon, and the basic performance and durability of the catalytic combustion system. The amount of gas adsorption in the adsorption stage was changed according to the type of activated carbon, adsorption temperature and time. The adsorption amount increased with increasing temperature and particle size. BTEX gas removal rate was about 96%, and the performance of the module was maintained for more than 4,000 hours.

Recently, various researches have been studied, such as water treatment, water reuse, and seawater desalination using CDI (Capacitive deionization) technology. Also, applications like MCDI (Membrane capacitive deionization), FCDI (Flow-capacitive deionization), and hybrid CDI have been actively studied. This study tried to investigate various factors by an experiment on the TDS (Total dissolved solids) removal characteristics using MCDI module in aqueous solution. As a result of the TDS concentration of feed water from 500 to 2,000 mg/L, the MCDI cell broke through faster when the higher TDS concentration. In the case of TDS concentration according to the various flow rate, 100 mL/min was stable. In addition, there was no significant difference in the desorption efficiency according to the TDS concentration and method of backwash water used for desorption. As a result of using concentrated water for desorption, stable adsorption efficiency was shown. In the case of the MCDI module, the ions of the bulk solution which is escaped from the MCDI cell to the spacer during the desorption process are more important than the concentration of ions during desorption. Therefore, the MCDI process can get a larger amount of treated water than the CDI process. Also, prepare a plan that can be operated insensitive to the TDS concentration of backwash water for desorption.

Two lab-scale trickle-bed type biofilters with a single fungal species (Aspergillus fumigatus, Acidomyces acidophilus, respectively) have been studied to investigate the simultaneous removal of inorganic (hydrogen sulfide) and organic (butyl acetate) compounds. The biofilter with Aspergillus fumigatus treated simultaneously two different compounds with removal capacity of 1,511 mgS/m3/hr and 6,324 mgC/m3/hr; and the biofilter inoculated with Acidomyces acidophilus had the removal capacity of 1,254 mgS/m3/hr and 6,045 mgC/m3/hr. Stable operational performance was observed in both biofilters under an acidic condition of pH 2 to 4. Based on pseudo-first-order removal rates as a function of depth in the biofilter, Aspergillus fumigatus showed a twice faster rate of hydrogen sulfide removal than Acidomyces acidophilus, 15.9% (Aspergillus fumigatus) and 17.9% (Acidomyces acidophilus) of total sulfur removed were oxidized to produce sulfates, and 77.8% (Aspergillus fumigatus) and 79.4% (Acidomyces acidophilus) were accumulated in the form of S0 through the bed in both biofilters, respectively.

본 연구에서는 광화학 대기질 모델인 CMAQ을 활용해 화력발전소 배출량 제거에 따른 O3 농도의 변화 특성을 분석하였다. 하동 화력발전소를 대상으로 주변 지역의 O3 농도 변화에 대한 발전소 배출량의 영향을 조사하기 위해 하 동 화력발전소의 배출량 제거 전과 후의 CMAQ 수치 모의를 수행하였다. 수치 모의 결과 O3의 주요 전구 물질인 NOx (-18.87%)와 VOCs (-11.27%)의 농도가 감소한 반면에 O3 (25.24%)의 농도는 증가한 것으로 나타났다. 화력발전소 배출량 제거로 인한 NO와 O3 농도의 상대적인 변화를 비교해 본 결과 높은 음의 상관관계(R= -0.72)를 나타내는 것이 확인되었다. 이러한 결과는 O3의 농도 증가가 NO 농도 감소로 인한 O3의 적정 효과 완화로 설명 될 수 있음을 의미한 다. 해당 지역의 O3의 농도 증가가 NO의 농도 감소에 주로 영향을 받은 이유는 해당 지역이 VOC-limited (i.e., NOxsaturated) 지역이기 때문으로 분석되었다. 이러한 결과는 특정 지역의 O3의 농도가 단순히 배출량의 증감에 따라 비례하게 나타나지 않을 수 있다는 것을 암시한다. 따라서 화력발전소 배출량 저감 조치로 인한 대기 중 O3 농도 개선 효과를 정확히 예측 및 평가하기 위해서는 지역 별 O3의 생성 및 소멸 기작에 대한 심도 있는 이해가 필요하다.

The Odor-causing compounds from grilled meat restaurants are mainly ammonia, aldehydes, and volatile organic compounds (VOCs). Acetaldehyde is known to have the greatest odor contribution. This study examines the application of silica gel for acetaldehyde in gas stream. Heat-pretreated silica gel showed relatively good adsorption performance and at 150oC, its breakthrough capacity reached up to 51 mg/g. By using Thomas' dynamic model, which well estimated the adsorption performance in this study, the effects of inlet concentration and retention time on adsorption capacity were evaluated. The adsorbent saturated with acetaldehyde was regenerated by reducing the pressure, which was controlled by the vacuum pump. The design factors were found to be 10 sec−1 of space velocity, -184 kPa·hr of desorption condition, and 10 to 1 of the ratio of cross sectional area to the height for the fixed-bed. The cyclic operation of adsorption and desorption step in the fixed bed packed with silica gel appeared to have 7.0-8.8 mg/g of acetaldehyde removal capacity and 99% of regeneration.

본 논문에서는 패치 반복을 이용하여 대기광 추정을 통해 개선된 안개 제거 방법을 제안한다. 기존의 안개 제거 방법은 영상 내에 인공적인 빛이나 밝은 물체가 있는 경우 대기광 추정 시 오차가 발생 한다. 이 방법은 안개 영상의 화소들 중 가장 밝은 값으로 대기광을 추정하기 때문이다. 이러한 문제를 해결하기 위하여, 제안하는 방법은 패치 쌍 사이의 안개 양의 차이점을 이용한다. 패치 쌍은 안개의 양이 다르지만 유사한 패턴을 가지고 있기 때문에, 대기광이 동일하다고 가정할 수 있다. 이러한 특성을 통해 각 패치 쌍으로 구한 대기광에 다른 가중치를 부여함으로써 대기광을 추정할 수 있다. 실험을 통해 제안하는 방법이 기존의 방법보다 안개 제거 성능에서 우수함을 확인하였다.

대기오염물질 중 미세먼지는 심각한 사회적 환경문제로 인식되고 있다. 미세먼지의 원인 물질 중 하나인 질소산화물(NOx)은 석탄화력발전소의 연소공정에서 주로 발생하므로 효율적인 NOx 제거가 필요한 실정이다. 본 연구에서는 선택적 촉매 환원법(Selective Catalytic Reduction, SCR)을 이용한 NOx 제거에서 TiO2 광촉매의 NO 제거효율을 연구하였다. NO 제거효율을 평가하기 위해 발열제가 내장된 Al2O3 기판 표면에 TiO2 촉매와 인산염의 접착 바인더를 혼합하여 도포한 후 제조된 기판을 열처리하면서 실험을 수행하였다. 온도에 따른 촉매의 NO 제거효율을 평가하였고, 촉매의 물리화학적 특성을 위하여 XRD, SEM, TG-DTA, BET 분석을 수행하였다. NOx 제거 효율은 시간에 따른 온도변화(250℃∼500℃) 로 20분에서 제거효율은 58.7%∼65.9%이며, 30분에서 63.7%∼66.0%로 나타났다. 질소산화물 제거용 SCR로 사용되는 TiO2는 300℃가 제거효율이 가장 효율적인 것으로 판단된다.

In this study, various conditions and phenomena that occur in the process of removing odorous VOCs by using electrolyzed oxidant were examined. The formation of hypochlorous acid, which is an oxidant produced by electrolysis, was investigated and the properties of the oxidizing agent used to decompose toluene, xylene, and cyclohexane were investigated. As a result, it was found that the production rate and the final concentration of the oxidizing agent increased with the current density. It was found that the degree of removal varies depending on the property of each pollutant. Interestingly, in the batch experiments in which the pH of the produced oxidant was controlled, it was found that the degree of elimination varied depending on the pH of the substance. These results suggest that the difference in the concentration and distribution of hypochlorous acid (HOCl) and hypochlorite (OCl−) due to the pH change leads to the difference in oxidizing power on the oxidation characteristics of each substance. Styrene and terpineol showed better degradation characteristics than toluene and xylene in odorous VOC removal experiments by spraying electrolytic oxidant using a lab-scale continuous reactor. In conclusion, the removal of odorous VOCs by the electrolytic oxidant can have various applications in that it can oxidize pollutants of various spectra.

이소프로필알코올/물 혼합물은 가교된 폴리비닐알코올 복합막을 이용하여 투과특성평을 알아보았다. 검화도가 다 른 3종 PVA를 이용하여 고분자의 농도와 GA 농도에 따라서 투과특성을 확인하였다. 복합막은 PVA 용액을 PAN 지지체 위에 캐스팅한 후, 열가교를 통해 제조하였다. PVA 농도가 증가할수록 투과도는 감소하지만 선택도는 증가하는 것을 확인하였다. PVA-3이 7 wt% 농도로 코팅된 복합막에서 209 g/m2h의 투과도를 가지고, 100 이상의 선택도를 가지는 것을 확인하였다. 침지형 분리막을 제조하여 feed tank 온도와 feed 용액의 IPA 농도에 따라서 투과실험을 확인하였다. 또한 IPA 수용액에 농축실험을 지속적으로 한 결과, 60시간 후에 IPA의 농도가 99%까지 증가하는 것을 확인하였다.