PURPOSES : A pilot experimental study on the formation of fine particulate matter through photochemical reactions using precursor gas species (volatile organic compounds (VOCs), NH3, SO2, and NOx) was conducted to evaluate the large-scale environment chamber for investigating the pathway of aerosol formation and the subsequent assessment techniques used for reducing fine particulate matter. Two small-scale environment chambers (one experimental group and one control group), each with a width, depth, and height of 3 m, 2 m, and 2.3 m, respectively, were constructed using ethylene tetrafluoroethylene (ETFE) films. METHODS : The initial conditions of the fine particles and precursor gases (NOx and VOCs) for the small-scale environment chamber were set up by injecting diesel vehicle exhaust. NH3 and H2O2 were added to the small-scale environment chamber for the photochemical reaction to form organic and inorganic aerosols. The gas phase of the VOCs and the chemical compositions of aerosols were investigated using a proton transfer reaction time-of-flight mass spectrometer and the aerodyne high-resolution time-of-flight aerosol mass spectrometer at 1 and 10 s time resolutions, respectively. Gas phases of NO and NO2 were measured using Serinus 40 NOx at a 20 s time resolution. RESULTS : The small-scale environment chambers built using ETFE films were proved to supply sufficient natural sunlight for the photochemical reaction in the environment chambers at an average of approximately 89% natural sunlight transmission at 300–1000 nm. When the intermediates of NH3 and H2O2 for the atmospheric chemical reaction were injected for the initial condition of the small-scale environment chamber, nitrate and ammonium in the experimental group increased to 4747% and 1837%, respectively, compared to the initial concentrations (5.4 μg/m3 of nitrate and 5.2 μg/m3 of ammonium), indicating the formation of secondary inorganic aerosols of ammonium nitrate (NH4NO3). This implies that it is necessary to inject intermediates (NH3 and H2O2) for the formation of fine particulate matter when simulating the atmospheric photochemical reaction for assessing the environment chamber. CONCLUSIONS : This study has shown that small-scale environment chambers can simulate the atmospheric photochemical reaction for the reduction of fine particulate matter and the formation of the aerosol pathway. The results of this study can be applied to prevent time and economic losses that may be incurred in a full-scale environment chamber.

Scale formation is inevitable problem when seawater is treated by vacuum membrane distillation. The reason is the high concentration of calcium ion(Ca2+), sulfate ion(SO4 2-) and bicarbonate ion(HCO3 -). These ions form calcium sulfate(CaSO4) and calcium carbonate(CaCO3) on the membrane. The scale formed on membrane has to be removed, because the flux can be severely reduced and membrane wetting can be incurred. This study was carried out to investigate scale formation and effectiveness of acid cleaning in vacuum membrane distillation for SWRO brine treatment. It was found that permeate flux gradually declined until volume concentration factor(VCF) reached around 1.55 and membrane wetting started over VCF over 1.6 in the formation of precipitates containing CaSO4 during VMD operation. In contrast, when calcium carbonate formed on membrane, permeate flux was gradually reduced until VCF 3.0. The precipitates containing both CaSO4 and CaCO3 were formed on the membrane surface and in the membrane pore.

Shale gas has become increasingly important as a viable alternative to conventional gas resources. However, one of the critical issues in the development of shale gas is the generation of produced water, which contains high concentration of ionic compounds (> TDS of 100,000 mg/L). Accordingly, membrane distillation (MD) was considered to treat such produced water. Experiments were carried out using a laboratory-scale direct contact MD (DCMD). Synthetic produced water was prepared to examine its fouling propensity in MD process. Antiscalants and in-line filtration were applied to control fouling by scale formation. Fouling rates (-dJ/dt) were calculated for in-depth analysis of fouling behaviors. Results showed that severe fouling occurred during the treatment of high range produced water (TDS of 308 g/L). Application of antiscalant was not effective to retard scale formation. On the other hand, in-line filtration increased the induction time and reduced fouling.

In this study, carbon dioxide (CO2) was used as an inhibitor of scale production on the surface of RO membrane. In order to compare the effects of CO2 injection on scale production, four RO modules: 1) without CO2 injection and anti-scalant (RO module #1), 2) with only CO2 injection (RO module #2), 3) with only anti-scalant (RO module #3), 4) with both CO2 injection and anti-scalant (RO module #4), were operated for 60 days under constant flux mode. The trans-membrane pressure (TMP) was observed to decrease significantly in RO modules with CO2 injection as compared with the other RO modules. When the feed water pH was controlled at 5.0 by injecting CO2, the maximum TMP in RO modules #2 and #4 was founded to decrease by 42 aㅋnd 40%, respectively. Moreover, the Ca2+ concentration in the concentrate was 20mg/L lower in RO modules without CO2 injection which is attributed to the scale formation on the surface of the RO membranes. The SEM-EDS analysis further showed a serious fouled RO membrane surface in RO modules #1 and #3.

전기투석 공정에서 이온교환막 표면에 형성되는 스케일 영향을 조사하기 위해 장기간 동안 운전되었다. 탈염공정 동안, Ca2+과 SO42- 이온의 농도는 농축실에서 연속적으로 증가하였으며 양이온교환막(Neosepta CMX)표면에 침전이 발생하였다. 초기 스케일 형성동안, 공정성능과 막 특성의 변화는 농축실 염농도 증가에 기인하여 일어나는 양이온교환막의 하계전류밀도가 감소하는 것을 제외하곤 미미하였다. 공정운전이 진행됨에 따라 양이온교환막의 한계전류밀도는 물의 해리 현상이 진행되어 300;A/m2까지 감소하였다. 막 오염은 농축실에서 양이온교환막 표면에 형성된 스케일과 물의 해리현상에 의해 유발된다는 결론을 얻었으며, 이러한 스케일 형성은 CaSO4의 용해도에 의해 예측 가능한 것을 알 수 있었다.

Clusters of galaxies are storage rooms of cosmic rays. They confine the hadronic component of cosmic rays over cosmological time scales due to diffusion, and the electron component due to energy losses. Hadronic cosmic rays can be accelerated during the process of structure formation, because of the supersonic motion of gas in the potential wells created by dark matter. At the shock waves that result from this motion, charged particles can be energized through the first order Fermi process. After discussing the most important evidences for non-thermal phenomena in large scale structures, we describe in some detail the main issues related to the acceleration of particles at these shock waves, emphasizing the possible role of the dynamical backreaction of the accelerated particles on the plasmas involved.

Disk galaxies abound with intermediate-scale structures such as OB star complexes, giant clouds, and dust spurs in a close geometrical association with spiral arms. Various mechanisms have been proposed as candidates for their origin, but a comprehensive theory should encompass fundamental physical agents such as self-gravity, magnetic fields, galactic differential rotation, and spiral arms, all of which are known to exist in disk galaxies. Recent numerical simulations incorporating all these physical processes show that magneto-Jeans instability (MJI), in which magnetic tension resists the stabilizing Coriolis force of galaxy rotation, is much more powerful than swing-amplification or the Parker instability in forming self-gravitating intermediate-scale structures. The MJI occurring in shearing and expanding flows off spiral arms rapidly forms structures elongated along the direction perpendicular to the arms, remarkably similar to dust spurs seen in HST images of spiral galaxies. In highly nonlinear stages, these spurs fragment to form bound clumps, possibly evolving into bright arm and interarm H II regions, suggesting that all these intermediate-scale structures in spiral galaxies probably share a common dynamical origin.

국내에서 많이 재배되는 버섯 중의 하나인 느타리 P. ostreatus는 먹물버섯이나 치마버섯과는 달리 실험실 수 준에서의 자실체 발생이 힘든 것으로 알려져 있다. 본 연구 에서는 실험실에서 느타리버섯을 샤레를 이용하여 전 발 생과정을 유도하기 위한 방법을 검토하였다. 샤레상의 배 양조건은 프라스틱 샤레 (60×15 mm)의 감자배지에서 균사를 접종한 후 빛이 없는 상태에서 배양한 뒤에, 균사의 환기상태, 균사표면의 상처, 빛 그리고 저온충격 등의 여러 환경요인들이 원기 및 자실체 형성에 미치는 영향을 검토 하였다. 느타리의 최초 자실체 형성은 접종 이후 3주 내에 얻을 수도 있었으며, 균사접종 이후 10주 동안에 자실체의 형성은 균주에 따라서 76%에서 97%의 높은 빈도로 유도 될 수 있었다. 위와 같이 샤레상에서 자실체를 형성 할 수 있었으며, 정상적인 자실체의 성장을 위해서 빛은 필수적 이며, 환기도 필요하였다. 또한 균사의 상처 처리가 원기, 자실체 및 포자의 형성에 미치는 영향이 균주에 따라서 크 게 차이가 났으며, 같은 균주라 하더라도 발생단계별 그 반 응의 차이도 크다는 사실을 확인하였다. 이들 자실체에서 수집된 담자포자는 발아가 가능하였다. 샤레상의 완전한 자실체 형성 방법은 느타리버섯의 생육주기를 단축시킬 수 있을 뿐만 아니라, 다양한 재배조건의 시료 획득과 한 개의 배양 용기 내에서 버섯 발생의 전 단계를 관찰하고 분 석하는데 유용할 수 있다.

We reexamined CDM texture large-scale structure (LSS) formation model. We confirmed that texture model is consistent with 4-year COBE data both in an open and a critical matter density (Ω0 = 1) universes, and then obtained normalization for density perturbation power spectrum. We next compare the power spectrum with LSS observation data. Contrary to the previous literature, we found that texture model matches with these data in an open universe no better than in an Ω0 = 1 universe. We also found that the model is more likely to fit these data in a cosmological constant dominated (Λ-) universe.

본 실험은 오리엔탈 나리 ‘Siberia’ 품종을 유공비닐 봉지에서 인편삽시 인편 착생부위와 삽목조건에 따른 소인경의 형성과 생장을 조사하여 효과적인 소인경 생산 방법을 알아보고자 실시하였다. 착생부위에 있어서 내부보다는 외부와 중부인편이 소인경의 형성 및 생육이 양호하였다. 삽상의 온도는 15℃나 30℃보다 20℃와 25℃ 조건에서 소인경의 무게, 둘레, 높이, 수가 증가하였다. 용토 1L당 수분 400mL 처리는 타처리에 비해 소인경의 무게와 직경이 16% 정도 증가한 것으로 나타났다. 피트모스 단용과 피트모스:펄라이트:버미큘라이트를 1:1:1 혼합한 용토에서 소인경 생육이 양호하였다. 인편과 용토의 비율을 1:2하여 혼합한 후 인편삽을 하더라도 소인경 무게와 직경에는 큰 차이가 없었다.

패모의 기내 주년 생산 체계를 확립하기 위한 연구의 일환으로 cytokinin이 첨가된 배치에서 배양 방법의 차이가 자구 형성과 비대에 미치는 영향, 배지의 삼투 포텐셜 조절을 위한 mannitol 첨가나 활성 탄소 및 생장 억제제 처리가 기관 형성과 인편 비대에 미치는 영향에 대해서 실험한 결과는 다음과 같다. 1. 0mg/L kinetin과 0. 3mg/L NAA가 혼용 처리된 MS 고체 배지에서 액체 배지나 액체 현탁배지에서보다 효과적인 자구 생장과 증식율을 나타냈으며, 액체 배지나 액체 현탁처리 배지에서는 비슷한 결과를 나타냈다. 활성 탄소의 농도는 0.01%~0.1% 처리구에서 형성된 자구의 비대가 양호하였고, 0. 5% 이상 농도에서는 오히려 생장이 억제되었다. 1~2% mannitol이 첨가된 배지에서 인편으로부터의 자구 형성수 및 구비대가 양호하였으며, 그 이상의 농도에서는 생장에 저해적으로 작용하였다. 생장 억제제인 B-9과 Chloromequat 처리구에서는 10~100mg/L 처리구에서 자구 발생 및 비대가 양호하였으나, 발생 인편의 생육 상태가 억제되었으며, ABA 처리구에서는 배양 중 인편이 모두 고사하였다.