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.

코로나방전플라즈마제트(CDPJ) 생성장치를 제작하여 조업특성을 조사하고 비가열살균기술로서의 활용가능성을 탐색하고자 E. coli를 대상으로 살균성능을 조사하였다. CDPJ장치는 전력공급장치, 변압기, 전극, 송풍기, 시료처리부 등 다섯 부분으로 구성하였다. 전압 10.0-20.0 kV의 직류전기를 10.0-45.0 kHz 구형파 펄스형태로 텅스텐리드 전극에 투입함으로써 코로나방전 플라즈마를 생성하고 동시에 전극사이로 강한 공기를 주입함으로써 하부방향으로 토출하는 플라즈마제트를 생성하였다. CDPJ 처리는 플라즈마 토출구 하부에 처리대상 물체를 위치하고 일정시간 처리하는 방식으로 시행하였다. 주파수를 높일수록 다량의 전류가 유입되었고, 비례하여 전력소비량도 증가하였다. 플라즈마 생성을 위한 임계전류는 1.0 A, 임계주파수는 32.5 kHz이었으며, 1.5 A 이상 40.0 kHz 이상에서 안정적인 플라즈마제트가 생성되었다. 플라즈마제트의 길이는 전류에 따라 증가하였고, 2분 이하 처리 시 대상물체의 표면온도 상승은 25oC를 하회하였다. E. coli 살균력은 전류세기에 비례하여 증가하였고, 전류 1.5 A에서 1분간 CDPJ처리에 의해 4.5 log 이상의 살균효과를 보였으며, 살균패턴은 2단계 1차 반응으로 확인되었다.

The biodiesel production characteristics in a pulsed-corona plasma reactor has been investigated through parametric tests. Transesterification of rapeseed oil together with camelina oil was done with the change of such variables as voltage of power, molar ratio, KOH catalyst and temperature. The energetic electrons emitted from pulsed-corona plasma has contributed to the enhancement of yield on rapeseed oil in short time (15 min). The higher yield on camelina oil was observed in 5 min. The optimal parameters were shown as the voltage of 23 kV, the molar ratio of 5/1, the content of KOH catalyst of 0.6 wt% and the temperature of 28℃ under the rotating rate of spark gap of 900 rpm.

We investigate how plasma structures in the solar chromosphere and corona can extend to altitudes much above hydrostatic scale heights from the solar surface even under the force of gravity. Using a simple modified form of equation of motion in the vertical direction, we argue that there are two extreme ways of non-hydrostatic support: dynamical support and magnetic support. If the vertical acceleration is downward and its magnitude is a significant fraction of gravitational acceleration, non-hydrostatic support is dynamical in nature. Otherwise non-hydrostatic support is static, and magnetic support by horizontal magnetic fields is the only other possibility. We describe what kind of observations are needed in the clarification of the nature of non-hydrostatic support. Observations available so far seem to indicate that spicules in the quiet regions and dynamic fibrils in active regions are dynamically supported whereas the general chromosphere as well as prorninences is magnetically supported. Moreover, it appears that magnetic support is required for plasma in some coronal loops as well. We suspect that the identification of a coronal loop with a simple magnetic flux tube might be wrong in this regard.

We have constructed a non-spherical model for the hot oxygen corona of Mars by including the effects of planetary rotation and diurnal variation of the Martian ionosphere. Exospheric oxygen densities are calculated by integrating ensemble of ballistic and escaping oxygen atoms from the exobase over the entire planet. The hot oxygen atoms are produced by dissociative recombination of O+2, the major ion in the Martian ionosphere. The densities of hot oxygen atoms at the exobase are estimated from electron densities which have been measured to vary with solar zenith angle. Our model shows that the density difference of hot oxygen atoms between noon and terminator is about two orders of magnitude near the exobase, but reduces abruptly around altitudes of 2000 km due to lateral transport. The diurnal variation of hot oxygen densities remains significant up to the altitude of 10000 km. The diurnal variation of the hot oxygen corona should thus be considered when the upcoming Nozomi measurements are analyzed. The non-spherical model of the hot oxy-gen corona may contribute to building sophisticate solar wind interaction models and thus result in more accurate escaping rate of oxygens from Mars.

본 연구에서는 상온에서 정방성 조성인 Pb0.9888Sr0.012(Zr0.52Ti0.48)O3계 세라믹스를 소결 후 직류전계 및 코로나를 이용하는 방법으로 소결시편을 분극한 후 분극방법에 따른 시편의 압전특성을 조사하였으며, 열화현상을 평가하기 위한 방법으로 시편의 내부응력의 차이를 조사하였다. 이 결과 코로나 분극방법은 직류분극에 비하여 30˚C정도 저온에서도 최대 Kp값을 얻을 수 있었으며 열화현상이 천천히 진행되었고 절연파괴가 발생하지 않는 등의 장점이 관찰되었다. 그러나 Kp값은 직류분극의 경우가 코로나 분극에 비하여 약 9~10%정도 높은 값을 나타내었다.

Rapid industrial development has led to a serious problem of pollution in the industrial sector. With the increasing social need for environmental protection, research on air pollution prevention equipment for reducing pollutants in industrial processes is actively being undertaken. The deterioration of existent, installed facilities, their increased emission rates, and the strengthening of the effluent quality standards make complying with permissible emission standards difficult. In fact, installing new electric precipitators or complementing existent facilities is inevitable. The expansion and complementation of the installed electrical precipitators have led to improvements in dust collection efficiency, shorter working times, and lower costs. Because of its easy installation and simple manufacturing process, the production method with the discharge electrode of an electric precipitator is widely used. The following conclusions were reached by classifying discharge electrodes into four types based on the production method and mutually comparing them by their dust collection efficiency. None of the four types used in this study were damaged by impact. However, we were able to confirm some strain from the compression sites of both type A and type B. Both type B and type C are expected to have greater dust collection efficiencies than the other models due to their large vibration transmissibility. Moreover, the high vibrational energy is expected to cause rapping damage during its operation. Particularly, in the case of type B, some of the strain was found at the end of the compression site. The coupling schemes of both type C and type D are out of vibration transmissibility. On the other hand, the ability to maintain straightness and solidity of the side is regarded as outstanding and stable. Type D has outstanding on-site workability, considering the presence of locking, structural stability, and work conditions. From these experiments, we determined that type C is the most ideal connection method of discharge electrode, considering its construction period of renovation. Type C is inferior to type D with regard to on-site workability. However, type C has outstanding dedusting transmission with regard to the straightness, solidity maintenance, and vibration of shearing stress.

On the basis of the distribution of particle size measured by laser diffraction spectrometers, this research was carried out to investigate the characteristics of mist removal with the change of operating condition in the plasma reactor of impulse streamer corona. The operating parameters in this experiment were power of impulse streamer corona, gas velocity, impulse generation time, gas temperature, and SOx/NOx concentration. The collection efficiency T(d) was estimated by the distribution of particle size in the collection zone through the advanced model.