• Journal of Soil and Groundwater Environment
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• v.9 no.1
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• pp.63-69
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• 2004

Hematite-coated sand was examined for the application of the PRB (permeable reactive barrier) to the arsenic-contaminated subsurface in the metal mining areas. The removal efficiency of As in a batch and a flow system was investigated through the adsorption isotherm, removal kinetics and column experiments. Hematite-coated sand followed a linear adsorption isotherm with high adsorption capacity at low level concentrations of As (＜1.0 mg/L). In the column experiments, high content of hematite-coated sand enhanced the removal efficiency, but the amount of the As removal decreased due to the higher affinity of As (V) than As (III) and reduced adsorption kinetics in the flow system. Therefore. the amount of hematite-coated sand, the adsorption affinity of As species and removal kinetics determined the removal efficiency of As in a flow system.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2016.11a
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• pp.105-105
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• 2016

Recently, high power impulse magnetron sputtering (HIPIMS) has attracted considerable attentions due to its high potential for industrial applications. By pulsing the sputtering target with high power density and short duration pulses, a high plasma density and high ionization of the sputtered species can be obtained. HIPIMS has exhibited several merits such as increased coating density, good adhesion, microparticle-free and smooth surface, which make the HIPIMS technique desirable for synthesizing hard coatings. However, hard coatings present intrinsic defects (columnar structures, pinholes, pores, discontinuities) which can affect the corrosion behavior, especially when substrates are active alloys like steel or in a wear-corrosion process. Atomic layer deposition (ALD), a CVD derived method with a broad spectrum of applications, has shown great potential for corrosion protection of high-precision metallic parts or systems. In ALD deposition, the growth proceeds through cyclic repetition of self-limiting surface reactions, which leads to the thin films possess high quality, low defect density, uniformity, low-temperature processing and exquisite thickness control. These merits make ALD an ideal candidate for the fabrication of excellent oxide barrier layer which can block the pinhole and other defects left in the coating structure to improve the corrosion protection of hard coatings. In this work, CrN/Al2O3/CrN multilayered coatings were synthesized by a hybrid process of HIPIMS and ALD techniques, aiming to improve the CrN hard coating properties. The influence of the Al2O3 interlayer addition, the thickness and intercalation position of the Al2O3 layer in the coatings on the microstructure, surface roughness, mechanical properties and corrosion behaviors were investigated. The results indicated that the dense Al2O3 interlayer addition by ALD lead to a significant decrease of the average grain size and surface roughness and greatly improved the mechanical properties and corrosion resistance of the CrN coatings. The thickness increase of the Al2O3 layer and intercalation position change to near the coating surface resulted in improved mechanical properties and corrosion resistance. The mechanism can be explained by that the dense Al2O3 interlayer acted as an excellent barrier for dislocation motion and diffusion of the corrosive substance.

• Journal of the Korean Vacuum Society
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• v.22 no.2
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• pp.55-65
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• 2013

Sterilization of Neurospora crassa has been investigated in this research by using a surface air plasma with dielectric barrier discharged (DBD) structure under atmospheric pressure. The sinusoidal alternating current has been used in this experiment with discharge voltage of 1.4~2.3 kV. The phase difference between the voltage and current signals are found to be almost 80 degree due to the capacitive property of dielectric barrier. Temperature on the biomaterials has been minimized by radiating the heat with the air cooling system. It is noted that the substrate temperature remains under 37 degree for plasma exposure time of 10 minutes with operation of cooler system. It is found that the ozone, $O_3$, has been measured to be about 25~30 ppm within 1 cm region and to be about 5 ppm at the 150 cm downstream region away from the suface plasma. It is also noted that the nitric oxide, NO, and nitric dioxide, $NO_2$, are not nearly detected. Germination rate and mitochodrial activity of Neurospora crassa immersed in the deionized water have been found to be drastically decreased as the plasma treatment time and its electrical power are increased in this experiment. Here, the mitochondrial activity has been analyzed by MTT (3-(4,5-dimethy lthiazol-2yl)-2,5-diphenyl-2H-tetrazolium bromide) assay. However, sterilization of Neurospora crassa immersed in the Vogel's minimal media has been found to be low by plasma treatment, which is caused by surrounding background solution. This research shows the sterilization possibility of Neurospora crassa by using the noncontated surface DBD plasma, which is different from the plasma jet. This is mainly attibuted to the reactive species generated by the surface plasma, since they play a major role for inhibition of micobes such as Neurospora crassa.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.26 no.3
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• pp.244-253
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• 1990

For the purpose of the investigation on the selective action of trawl net, a series of fishing experiments carryed out in M. S. Pusan 402 during the years of 1986~1987, by using a set of trawl net with a few pocket nets in each part of the bagnet. The author analyzed these experimental data and derived the following results. 1. 58 species of aquatic animals were caught in totally 43 times of trawl operation and 33 species of them did not escape at all through the barrier of netting in the bagnet. 2. Sardinops melanosticta, Harengula zunasi, Thrisa kamalensis, Englausis japonicus, little size of Tracurus japonicus, Sphyraena pinguis, Trichirus lepturus, and Psenopsis anomala escaped easily through the barrier of netting after being caught inside of the codend. Especially, Englusis japonicus escaped well not only through the netting of the codend but also through the netting of the square and the baiting. 3. In the case of mesh size of 60mm in the codend, Pampus argentus, Doderleinia bercoides and Tracurus japonicus were caught all in the size of less than 10cm.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.4
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• pp.297-309
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• 2020

Coronaviruses were originally discovered as enzootic infections that limited to their natural animal hosts, but some strains have since crossed the animal-human species barrier and progressed to establish zoonotic diseases. Accordingly, cross-species barrier jumps resulted in the appearance of SARS-CoV, MERS-CoV, and SARS-CoV-2 that manifest as virulent human viruses. Coronaviruses contain four main structural proteins: spike, membrane, envelope, and nucleocapsid protein. The replication cycle is as follows: cell entry, genome translation, replication, assembly, and release. They were not considered highly pathogenic to humans until the outbreaks of SARS-CoV in 2002 in Guangdong province, China. The consequent outbreak of SARS in 2002 led to an epidemic with 8,422 cases, and a reported worldwide mortality rate of 11%. MERS-CoVs is highly related to camel CoVs. In 2019, a cluster of patients infected with 2019-nCoV was identified in an outbreak in Wuhan, China, and soon spread worldwide. 2019-nCoV is transmitted through the respiratory tract and then induced pneumonia. Molecular diagnosis based on upper respiratory region swabs is used for confirmation of this virus. This review examines the structure and genomic makeup of the viruses as well as the life cycle, diagnosis, and potential therapy.

• Applied Chemistry for Engineering
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• v.24 no.5
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• pp.544-550
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• 2013

This work investigated the environmental application of an underwater dielectric barrier discharge plasma reactor consisting of a porous hydrophobic ceramic tube to the decolorization of an azo dyeing wastewater. The reactive species generated by the plasma are mostly short-lived, which also need to be transferred to the wastewater right after the formation. Moreover, the gas-liquid interfacial area should be as large as possible to increase the decolorization rate. The arrangement of the present wastewater treatment system capable of immediately dispersing the plasmatic gas as tiny bubbles makes it possible to effectively decolorize the dyeing wastewater alongside consuming less amount of electrical energy. The effect of discharge power, gas flow rate, dissolved anion and initial dye concentration on the decolorization was examined with dry air for the creation of plasma and amaranth as an azo dye. At a gas flow rate of $1.5Lmin^{-1}$, the good contact between the plasmatic gas and the wastewater was achieved, resulting in rapid decolorization. For an initial dye concentration of $40.2{\mu}molL^{-1}$ (volume : 0.8 L; discharge power : 3.37 W), it took about 25 min to attain a decolorization efficiency of above 99%. Besides, the decolorization rate increased with decreasing the initial dye concentration or increasing the discharge power. The presence of chlorine anion appeared to slightly enhance the decolorization rate, whereas the effect of dissolved nitrate anion was negligible.

• The Korean Journal of Malacology
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• v.29 no.3
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• pp.197-205
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• 2013

Even though seedling production of Haliotis discus hannai has fully developed, the culture of benthic diatom as a live food for larvae is still a barrier to solve in commercial hatchery. The farmer depends on mixed microalgae which are non-selectively attached on the plate by flowing of natural seawater. The adequate diatom on the plate for the larvae in terms of quality and quantity is always significant bottleneck in the hatchery. In this study, two benthic diatom species, Caloneis schroederi and Rhaphoneis sp. were separately cultured in mass and inoculated to four tons' settlement tank of the larvae. And the larvae and the spats were cultured for nineteen and nine weeks, respectively. The result on seedling production of H. discus hannai with this method was compared to that of the farmer's traditional method as a control. With regard to variation of species composition of benthic diatom on the plate, C. schroederi and Rhaphoneis sp. were dominant for first three weeks after inoculation. But the diverse diatoms mainly, Navicula, Amphora, Cylindrotheca, Licmophora, Pleurosigma began to attache on the plate from the 4th week. The larvae attached 2.5 times more in C. schroederi tank than in the control tank. The final total biomass of the seeds in Rhaphoneis sp. tank was 3.2 times more than that of the control tank. The retared-spats in the seedling production also showed significantly higher growth and survival in the spat fed Rhaphoneis sp. or C. schroederi than those in the control group. We suggest that C. schroederi is proper for settlement of the larvae and Rhaphoneis sp. is appropriate for the growth of the larvae and spats in the commercial hatchery of H. discus hannai.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.22 no.1
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• pp.73-84
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• 2019

In this research, it is a basic study to investigate the population of birds using UAVs. The research area is Ardeidae species(ASP) habitat and has long-term monitoring. The purpose of the study is to compare the ASP populations which analyzed ground observational survey and UAVs imagery. We used DJI's Mavic pro and Phantom4 for this research. Before investigating the population of ASP, we measured the escape distance by the UAVs, and the escape distances of the two UAVs models were statistically significant. Such a result would be different in UAV size and rotor(rotary wing) noise. The population of ASP who analyzed the ground observation and UAVs imagery count differed greatly. In detail, the population(mean) on the ground observation was 174.9, and the UAVs was 247.1 ~ 249.9. As a result of analyzing the UAVs imagery, These results indicate that the lower the UAVs camera altitude, the higher the ASP population, and the lower the UAVs camera altitude, the higher the resolution of the images and the better the reading of the individual of ASP. And we confirmed analyzed images taken at various altitudes, the individuals of ASP was not statistically significant. This is because the resolution of the phantom was superior to that of mavic pro. Our research is fundamental compared to similar studies. However, long-term monitoring for ASP of South Korea's by ground observation is a barrier of the reliability of the monitoring result. We suggested how to use UAVs which can improve long-term monitoring for ASP habitat.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.208.1-208.1
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• 2016

히드라란 단세포 생물로써 강장동물에 속한다. 촉수가 많이 있으며, 그 촉수에는 독이 있다. 번식 방식으로는 출아법을 이용한다. 출아를 할 때에는 한 마리가 아닌 여러 마리의 히드라가 동시에 출아를 하기도 하며, 출아를 하고 있는 히드라는 촉수가 들어난 순간부터 먹이 섭취가 가능해진다. 이 출아법을 이용하여 번식을 하는 히드라가 DBD처리를 했을 시, 히드라 출아에 차이를 보인다면 다른 생물에게도 DBD 처리를 했을 시, 영향을 미친다고 생각하고 실험을 진행하였다. DBD(Dielectric Barrier Discharge)는 두 전극 사이에 유전체층이 있으며, 외부에서 교류 전압을 가해준다. 그러면 유전체 사이에서 방전이 발생되는데, 방전된 것을 플라즈마라고 한다. DBD라는 유전체 장벽 방전으로써 주위를 이온화 시켜 만드는 플라즈마에 유전체를 씌어 생물에게 최대한 해가 되지 않도록 만든 것이다. 유전체 장벽 방전에ROS(Reactive Oxygen Species)라는 산소와 결합된 기체들이 생성된다. DBD로 인해서 생성되는 ROS를 히드라에 처리했을 경우 히드라 출아수에 변화를 통해서 해를 끼치는 정도를 알아보고자 하였다. 그 결과 아르곤 기체에 의한 ROS로 처리한 히드라는 대조군 보다 히드라의 출아수의 변화가 있는 것으로 관찰되었고, 공기를 이용하여 방전한 DBD의 ROS로 처리한 히드라는 대조 군과 비교하여 큰 변화가 없어 보였다. 따라서 아르곤 대기압 DBD플라즈마를 이용하여 만든 ROS가 히드라에게 직접적인 영향을 준 것으로 보였다. 이 결과를 토대로 아르곤DBD를 이용한 ROS 처리는 생물에게 영향을 줄 수 있다는 것을 이 실험을 통해 간접적으로 확인해 볼 수 있었다.

• Progress in Superconductivity and Cryogenics
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• v.6 no.3
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• pp.27-32
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• 2004

High temperature superconducting coated conductor has a structure of /< superconducting layer>//. The buffer layer consists of multi layer, and the architecture most widely used in RABiTS approach is CeO$_2$(cap layer)/YSZ(diffusion barrier layer)/CeO$_2$(seed layer). Evaporation technique is used for the CeO$_2$ layer and DC reactive sputtering technique is used for the YSZ layer, A chamber was set up specially for DC reactive sputtering, Detailed features are as following. A separator divided the chamber into two halves a sputtering chamber and a reaction chamber. The argon gas for sputtering target elements flows out of the cap of sputtering gun, and water vapor for reaction with depositing species spouts near the substrate. Turbo pump is connected with reaction chamber. High speed deposition of YSZ film could be achieved in the chamber. Detailed deposition conditions (temperature and partial pressure of reaction gas) were investigated for the rapid growth of high quality YSZ film.