본 연구는 대기압 유전체장벽방전 플라즈마 처리에 따른 식품유해 미생물 사멸효과를 조사하기 위해 수행되었다. 플라즈마 처리 시, 활성종 생성 및 농도에 영향을 미치는 노출시간, 노출거리, 산소비율, 전력 변화에 따른 E. coli의 사멸효과를 조사한 결과, E. coli의 사멸율은 플라즈마 처리를 위한 노출시간, 산소비율, 전력의 증가에 따라 증가한 반면, 노출거리의 증가에 따라서는 사멸율이 감소하였다. 이 결과는 미생물 시료가 플라즈마에 노출되는 시간이 증가됨으로서 시료 내 NO 농도가 증가되고, E.coli의 사멸율 역시 증가되는 결과로 뒷받침할 수 있고, 미 생물 사멸효과를 높이기 위해서는 활성종의 농도가 증가 되어야 함을 의미한다. E. coli와 함께 B. cereus, B. subtilis, B. thuringiensis, B. atrophaeus를 대상으로 대기압 유전체 장벽방전 플라즈마에 의한 살균효과를 조사한 결과, 72.3~91.3%의 높은 사멸율을 나타내었다. 이러한 결과로 미루어, 대기압 유전체장벽방전 플라즈마기술은 다양한 미생물에 적용될 수 있는 유용한 살균기술임을 확인하였다.

In this study, using the surface dielectric barrier discharge (DBD) produced at atmospheric pressure to improve the physiological activities of quercetin was investigated. Quercetin (at 200 ppm) was treated using air DBD with an input power of 250 W. The tyrosinase inhibition effect and total phenolic content of quercetin increased from 38.96 to 91.58% and from 134.53 to 152.93 ppm, respectively, after 20 min of plasma treatment. The antioxidant activity of quercetin treated for 20 min in the lipid models was higher than that of quercetin treated for 0, 5, and 10 min. Furthermore, plasma-treated quercetin exhibited antimicrobial activity against Listeria monocytogenes, Salmonella Typhimurium, and Staphylococcus aureus, whereas activity was not shown in the control. Structural modifications of the quercetin molecule induced by plasma might be responsible for the improvements in its physiological activity. These results indicate that DBD plasma could be used to enhance the physiological activity of quercetin for various applications in food.

Electrolyzed water (EW) has been regarded as a new sanitizer by food industry. In this study, EW was used for perilla leaves sanitization. The optimum EW was produced at flow rates of brine and water of 100 mL/min and 300 mL/min, respectively. By soaking in EW only, the initial microbial counts of aerobic bacteria were reduced by 1.73 log(CFU/g), while 1.94 log(CFU/g) reduction was noted by using EW soaking followed by CDPJ treatment. In similar manner, counts of yeasts and molds were reduced by 1.83 and 2.06 log(CFU/g); coliform were reduced by 1.13 and 1.3 log(CFU/g), respectively. Combination of EW and CDPJ was more effective for microbial reduction. EW treatment did not affect sensory properties, instrumental color characteristics. However, it was observed that total phenolics and DPPH radical scavenging activity of perilla leaves were significantly increased with EW soaking time.

Benthic macroinvertebrates were investigated in thermal discharge that flows Buso stream region from December 2015 to February 2016, Korea. Study site was selected for the upstream, downstream relative to the mixing station and mixing station which thermal effluent flows, water quality analysis and benthic macroinvertebrates composition, taxa of EPT-group individuals, analysis of biological water quality. As a result, a total of 4,015 individuals including 50 species, 30 families, 11 orders, 4 classes, and 3 phyla were recognized. Taxa of species is Ephemeroptera 16 species (32.0%) including 6 families, the density composition was highest in 1,848 individuals (46.03%) Diptera. EPT-group occupied during the study period were a total of 1,876 individuals (46.72%) including 32 species and 17 family, lowest in the mixing station for study period. As a results of community analysis, mixing station in the Limnodrilus gotoi and Chironomidae sp.2, which is dominated by the analysis was Ecdyonurus levis, Cincticostella levanidovae, Nemoura KUa. The dominant species showed a difference in the upstream and downstream. In the functional feeding groups, in the upstream and mixing station Gathering-Collectors, downstream it was analyzed that the ratio of the highest Filtering-Collectors and decreased the ratio of Shredders increasing from upstream to downstream. Habitat orientation group is analyzed that accounted for most of the Clingers and Burrowers, from upstream to downstream toward the higher the ratio of Clingers. Biological water quality assessment results were analyzed the worst state in the mixing station with an average 2.73 (±0.41). Correspondence analysis, correlation analysis results of water temperature and the cold-water species, as the water temperature increases were analyzed by reducing cold-water species and EPT-group.

The Youngsan River estuary was physically changed by the construction of a sea embankment at near the mouth of estuary. Weirs were also constructed recently in the freshwater zone and it was reported that algal blooms occur more frequently. The freshwater introduced into saltwater zone from sluice gates of the embankment affects water quality but it has not been addressed that how the freshwater inputs influence the health of marine ecosystem. In this study, we used the data of water properties and phytoplankton communities collected at three stations for 4 days including before the freshwater discharge, during the discharge and after 1 and 2 days of discharge events. WQI (water quality index), TRIX (trophic status index) and P-IBI (phytoplankton index of biotic integrity) were used to evaluate the ecosystem health and long-term data were also utilized to determine the criteria for P-IBI. The results showed that grades of the ecosystem health assessed by the indices were low at the station near the gates and increased as downstream. However, the temporal pattern of grades was different depending on methods. Grades of WQI and TRIX decreased during the discharge and restored after the discharge whereas the grades of P-IBI decreased slightly even after the discharge. This suggests that P-IBI is more applicable to estuarine systems where experience extreme change of water properties than WQI and TRIX since P-IBI includes phytoplankton that can respond quickly to the change.

본 연구에서는 2010년 여름에 천수만에서 저층해수를 채집하여 용존산소와 영양염 농도를 측정하였다. 또한 benthic chamber내의 해수시료를 시계열로 채집하는 자동화된 Benthic Lander를 설치하여 해수-퇴적물간 영양염 플럭스를 측정하였다. 오염된 인공호수 유출수가 들어오는 천수만 북쪽에서는 저층수의 용존산소는 2 mg/l로 hypoxia의 존재 가능성이 확인되었다. 반면 남쪽 천수만 입구의 저층 용존산소는 5 mg/l이었다. 영양염은 용존산소와 반대의 분포 경향을 보였고, N/P ratio의 변화는 hypoxia에 의해 발생된 인산염의 탈착과 용출 때문으로 보인다. 만 북쪽 해역의 유기탄소 산화율과 산소소비율은 남쪽 만 입구 해역보다 약 2배 큰 값을 보였고, 영양염 benthic flux는 천수만 북쪽에서 4내지 6배 높았다. 이러한 결과는 해수-퇴적물간 물질 플럭스를 정확히 추정하기 위해서는 hypoxia의 역할에 대한 이해가 중요하다는 점을 시사해준다.

In this study, the use of corona discharge plasma jet (CDPJ) for the improvement of hygienic quality of semi-dried mackerel pike (Gwamegi) was investigated. Different microbial contaminants, namely aerobic and marine bacteria, coliform bacteria, Staphylococcus aureus and yeasts and mold, were detected in the range 4.2-6.2 log CFU/g in Gwamegi samples. The CDPJ generated using 20 kV DC and at 58 kHz frequency was used for the treatment of Gwamegi for 0-10 min. The bacterial contaminants were inactivated in the range of 1.9-3.3 log CFU/g on the treatment for 10 min. Additionally, yeasts and mold were inactivated by 3.2 log CFU/g. The inactivation pattern fitted well to the first-order kinetics model. The CDPJ treatment for 10 min did not exert statistically significant changes (P > 0.05) in pH, moisture content, water activity, peroxide value, acid value and volatile basic nitrogen content of Gwamegi in comparison to untreated control samples. On the contrary, significant changes (P < 0.05) were noted in color and thiobarbituric acid reactive substances levels upon the CDPJ treatment. However, the CDPJ-treated Gwamegi samples displayed better sensory properties in terms of appearance, visual color, and flavor as compared to controls.

Hydrogen sulfide (H2S) emitted from various sources is a major odorous compound, and non-thermal plasma (NP) has emerged as a promising technique to eliminate H2S. This study was conducted to investigate lab-scale and pilot-scale NP reactors using corona discharge for the removal of H2S, and the effects of relative humidity, applied electrical power on reactor performance and ozone generation were determined. A gas stream containing H2S was injected to the lab-scale NP reactor, and the changes in H2S and ozone concentration were monitored. In the pilotscale NP experiment, the inlet concentration and flow rate were modified to determine the effect of relative humidity and applied power on the NP performance. In the lab-scale NP experiments, H2S removal was found to be the 1st-order reaction in the presence of ozone. On the other hand, when plasma reaction and ozone generation were initiated after H2S was introduced, the H2S oxidation followed the 0th-order kinetics. The ratio of indirect oxidation by ozone to the overall H2S removal was evaluated using two different experimental findings, indicating that approximately 70% of the overall H2S elimination was accounted for by the indirect oxidation. The pilotscale NP experiments showed that H2S introduced to the reactor was completely removed at low flow rates, and approximately 90% of H2S was eliminated at the gas flow rate of 15 m3/min. Furthermore, the elimination capacity of the pilot-scale NP was 3.4 g/m3·min for the removal of H2S at various inlet concentrations. Finally, the experimental results obtained from both the lab-scale and the pilot-scale reactor operations indicated that the H2S mass removal was proportional to the applied electrical power, and average H2S masses removed per unit electrical power were calculated to be 358 and 348 mg-H2S/kW in the lab-scale and the pilot-scale reactors, respectively. To optimize energy efficiency and prevent the generation of excessive ozone, an appropriate operating time of the NP reactor must be determined.

아산만의 해양수질의 계절적인 변화를 이해하기 위하여 2011년 12월부터 2013년 2월까지 4계절 동안 수질을 관찰하고, 담수유입으로 인한 해양수질 변화 관계를 통계적인 기법으로 분석하였다. 아산만의 해양수질 자료에 대한 요인분석 결과는 해양수질 변화를 주도하는 가장 중요한 요인은 담수유입(37.7 %)이며, 그 다음으로는 외해수의 영향(24.4 %)으로 나타났다. 아산만에서 담수의 주요 공급원은 만의 가장 안쪽에 위치한 아산호와 삽교호이며, 이들의 방류로 인해 아산만의 전체적인 수질의 공간 분포가 결정되는 것으로 보인다. 반면 담수 방류가 적은 겨울철에는 저층 재부유에 기인한 영향이 상대적으로 중요해진다. 전체적으로 담수 방류량의 계절적인 변화가 아산만 전체의 환경변화를 주도하고 있으며, 이로 인하여 DIP가 식물플랑크톤의 성장을 제한하는 요소로 나타났다.

In order to reuse the photocatalyst and enhance the photolysis efficiency, we have used atmospheric pressure dielectric barrier discharge (APDBD) to clean and activate TiO2 powder. The photocatalytic activity of the TiO2 powder before and after APDBD treatment was evaluated by the degradation of methylene blue (MB) in aqueous solution. The apparent reaction rate constant of photolysis of the first sample of reused TiO2 cleaned by APDBD improved to a level up to 0.32h- 1 higher than the 30 % value of the initial TiO2 powder. As the number of photolysis reactions and APDBD cleanings increased, the apparent rate constants gradually decreased; however, the fourth photolysis reaction still showed a value that was greater than 10% of the initial value. In addition, APDBD treatment enhanced the process by which TiO2 effectively adsorbed MB at every photolysis stage.

The current disinfection method of vehicles being applied in South Korea has various shortcomings. So, the epidemic has generated continuously at livestock farms. It is very important to develop an effective disinfection system for reduction of the epidemic. And various basic data is required for this development. Therefore, this study was performed to identify the nozzle type and proper discharge pressure of sprayers. The experiment was conducted from January 10, 2012 until February 28, 2012. All the performance measurement experiments were repeated five times. The subjects of experiment were the A, B and C company’s products. The sprayed capacity, angle of spray and the covering area ratio were measured for each product. As a result, the sprayed capacity, angle of spray and the covering area ratio were increased as the discharge pressure of the sprayer was increased. In conclusion, the conical shaped of the nozzle is considered more appropriate than V-shaped, and the proper discharge pressure is expected to be at least 20kg/cm2.

본 연구에서는 항 내부에서 부하되는 오염물질이 파랑 및 흐름 조건으로 인하여 항외로 유출되는 과정을 수리실험을 통해 알아보았다. 월성원자력발전소 항내에 오염물질이 부하 되었을 시, 실험인자를 변화시켜가며 추적자를 활용한 흐름거동 조 사를 수행하였다. 각 실험의 결과는 지수 함수에 따른 항내 오염물이 감소하는 경향이 나타나며, 항외 유출에 걸리는 시간의 기울기는 각각 다른 결과를 보여주었다. 관측된 데이터로부터 회귀식을 도출한 결과, 흐름 관측의 경우 유입되는 모터의 회 전 속도 30, 20, 10 rpm에서 좌측 항내의 오염물이 50% 유출률에 도달하는 시간은 각각 2.70, 10.40, 26.39 days를 보였다. 모터의 회전속도가 30 rpm인 실험에서 유출되는 감소 추세가 가장 뚜렷하게 나타났으며, 회전속도 10 rpm인 실험에서 기 울기는 완만하였다. 파랑 관측의 우측 영역의 오염물이 50% 유출률에 도달하는 시간은 4.59 days로 나타났으며, 좌측영역 의 경우 15.35 days의 결과를 보였다.

This work investigated the decomposition of aqueous anatoxin-a originated from cyanobacteria using an underwater dielectric barrier discharge plasma system based on a porous ceramic tube and an alternating current (AC) high voltage. Plasmatic gas generated inside the porous ceramic tube was uniformly dispersed in the form of numerous bubbles into the aqueous solution through the micro-pores of the ceramic tube, which allowed an effective contact between the plasmatic gas and the aqueous anatoxin-a solution. Effect of applied voltage, treatment time and the coexistence of nutrients such as NO3 -, H2PO4 - and glucose on the decomposition of anatoxin-a was examined. Chemical analyses of the plasma-treated anatoxin-a solution using liquid chromatography-mass spectrometry (LC-MS) and ion chromatography (IC) were performed to elucidate the mineralization mechanisms. Increasing the voltage improved the anatoxin-a decomposition efficiency due to the increased discharge power, but the energy required to remove a given amount of anatoxin-a was similar, regardless of the voltage. At an applied voltage of 17.2 kV (oxygen flow rate: 1.0 L min-1), anatoxin-a at an initial concentration of 1 mg L-1 (volume: 0.5 L) was successfully treated within 3 min. The chemical analyses using LC-MS and IC suggested that the intermediates with molecular weights of 123~161 produced by the attack of plasma-induced reactive species on anatoxin-a molecule were further oxidized to stable compounds such as acetic acid, formic acid and oxalic acid.

비료를 유도용액으로 사용하는 정삼투를 하수처리수(2차 침전지 유출수)의 재이용에 적용하여 유도용액의 성능을 평가하였다. 일반적으로 많이 사용되고 있는 비료 중에서 삼투압, 용해도 및 pH 등을 고려하여 NH4H2PO4, KCl, KNO3, NH4Cl, (NH4)2HPO4, NH4NO3, NH4HCO3 및 KHCO3을 유도용액 후보군으로 선정하고, 수투과선속 및 역용질선속을 측정하 여 유도용액의 성능을 평가하였다. 평균 수투과선속은 KCl > NH4Cl > NH4NO3 > KNO3 > KHCO3 > NH4HCO3 > NH4H2PO4 > (NH4)2HPO4의 순서로 나타났으며, KCl을 유도용액으로 사용하였을 때, 평균 수투과선속은 13.49 LMH이었다. 하수처리장 2차 침전지 유출수의 삼투압은 탈이온수의 삼투압에 비해 큰 차이가 없었다. 역용질선속은 NH4H2PO4 < NH4Cl < (NH4)2HPO4 < KNO3 < NH4HCO3 < NH4NO3의 순서로 나타났으며, NH4H2PO4를 유도용액으로 사용하였을 때, 역용질선 속은 4.96 × 10-3 mmol/m2⋅sec이었다.

비열 처리 기술인 유전체 장벽 방전 저온 플라즈마(dielectric barrier discharge cold plasma, DBD-CP)를 이용하여 양 파 분말에 접종된 Salmonella Enteritidis, Escherichia coli O157:H7, 그리고 Listeria monocytogenes의 저해 효과를 조사 하였다. DBD-CP 처리 조건으로서 DBD-CP 형성 가스는 헬륨이었고, 독립 변인은 처리 전압(4, 5, 6, 7, 8, 그리고 9 kV)과 처리 시간(5, 10, 12, 15, 그리고 20분)이었다. 미생물 저해율과 양파 분말의 표면 온도를 종속 변인으로 하여 DBD-CP 최적화 조건을 확립하였고, 이를 바탕으로 S. Enteritidis 저해율에 대한 예측 모델을 구축하였다. 또한 양파 분말의 입자 크기와 수분활성도(Aw)에 따른 S. Enteritidis 저해 효과를 알아보았다. 또다른 처리 조건으로서 헬륨-물 혼 합 가스를 형성 가스로 사용하여 9 kV에서 5분 동안 주파수(15, 25, 그리고 35 kHz)에 따른 미생물 저해율과 시료 표면 온도에 대한 영향을 관찰하였다. DBD-CP 처리에 의해 양파 분말에 접종된 S. Enteritidis, E. coli O157:H7, 그리고 L. monocytogenes는 각각 ≤2.3 ± 0.1, ≤1.4 ± 0.2, 그리고 ≤0.7 ± 1.2 log CFU/cm 2까지 저해되었고, 시료의 최고 온도는 38.5 ± 1.52℃이었다. 양파 분말에 접종된 S. Enteritidis의 저해율에 대한 DBD-CP 최적 조건은 9 kV와 20분이었고, S. Enteritidis 저해율을 가장 적절하게 예측한 모델은 Fermi’s model (R 2 =0.93)이었다. 수분활성도가 0.4, 0.8인 양파 분말의 S. Enteritidis 저해율은 각각 2.3 ± 0.1, 1.8 ± 0.1 log CFU/cm 2로 유의적인 차이가 없었고(p>0.05), 입자 크기가 0.25, 1.00 cm 2인 양파 분말의 S. Enteritidis 저해율은 각각 2.3 ± 0.1, 1.0 ± 0.5 log CFU/cm 2로 입자의 크기가 작을수록 저해율이 높았다. 헬륨-물 혼합 가스로 DBD-CP 처리시 모든 식중독균에서 주파수가 작을수록 저해율이 증가하였고, 헬륨의 단 독 처리에 비해 미생물 저해율이 유의적으로 증가하였다(p<0.05). 현 연구를 통해 DBD-CP 처리 기술은 분말 식품의 품질 보존 및 미생물 안전성을 향상시키기 위한 살균 방법으로서의 가능성을 보여주었다.

Non-thermal techniques for microbial decontamination in foods are becoming more promising. This work aims to evaluate suitability and effectiveness of corona discharge plasma jet (CDPJ) for the inactivation of microbial contaminants of dried squid shreds. CDPJ was generated at 20 kV DC and at 58 kHz frequency. Upon the CDPJ treatment for 3 min of the shreds, bacterial contaminants namely aerobic, marine and Staphylococcus aureus were inactivated by 2.0, 1.6, and 0.9 log units, respectively. Also, a 0.9 log reduction of yeasts and molds contaminants was observed. The inactivation pattern fitted well to the pseudo-first-order model rather than first-order kinetic model. The CDPJ treatment did not exert statistically significant (P>0.05) changes in color characteristics and volatile basic nitrogen content of the shreds, as compared to untreated controls. In contrast, the moisture and thiobarbituric acid reactive substances levels were significantly (P<0.05) altered by the plasma exposure. However, the treatment exerted no significant (P>0.05) impact on the sensory characteristics of the shreds. The CDPJ was found effective for bio-decontamination of real-world samples of dried squid. This technology can readily be applied to commercial dried squid processing.

Different pathogenic microorganisms have been reported to cause sprouts-associated outbreaks. This work aimed to evaluate the effect of corona discharge plasma jet (CDPJ) on disinfection of the natural bio-contaminants of broccoli seed and also studied the plasma effect on sprout seed germination rate and physico-chemical properties of sprouts. Aerobic bacteria, molds and yeasts, B. cereus, E. coli, Salmonella spp. were detected on the broccoli seed surface. After 0-3 min treatment using CDPJ, the detected microorganisms were reduced in the range of 1.2-2.3 log units. Inactivation patterns were better explained using pseudo-first-order kinetics. The plasma treatment of seeds up to 2 min exhibited positive effects on the germination rate and the seedling growth. The physico-chemical and sensory characteristics of sprouts were unaffected due to the CDPJ treatment of their respective seeds. The CDPJ can potentially be used for microbial decontamination of broccoli seeds.

The morphology, crystal structure and size of aerosol nanoparticles generated by erosion of electrodes made of different materials (titanium, copper and aluminum) in a multi-spark discharge generator were investigated. The aerosol nanoparticle synthesis was carried out in air atmosphere at a capacitor stored energy of 6 J, a repetition rate of discharge of 0.5 Hz and a gas flow velocity of 5.4 m/s. The aerosol nanoparticles were generated in the form of oxides and had various morphologies: agglomerates of primary particles of TiO2 and Al2O3 or aggregates of primary particles of Cu2O. The average size of the primary nanoparticles ranged between 6.3 and 7.4 nm for the three substances studied. The average size of the agglomerates and aggregates varied in a wide interval from 24.6 nm for Cu2O to 46.1 nm for Al2O3.

Most of the soundproof tunnels generate significant discharge noise through their inlets and outlets so that the length of the tunnel has been extended frequently than required to minimize the effect on such discharge noise. Thus, in this paper, we investigate reduction capability of discharge noise from the sound proof tunnel installed with lateral sound-absorbing panels on the partitioned truss members in the longitudinal direction of the tunnel. In conclusion, noise field analysis results shows that the sound proof tunnels with lateral sound-absorbing panels have an effect on discharge noise abatement and thereby tunnel’s length reduction.