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.

The triboelectric property of a material is important to improve an efficiency of triboelectric generator(TEG) in energy harvesting from an ambient energy. In this study, we have studied the TEG property of a semicon-ducting SnO2 which has yet to be explored so far. As a counter triboelectric material, PET and glass are used. Verticalcontact mode is utilized to evaluate the TEG efficiency. SnO2 thin film is deposited by atomic layer deposition on bareSi wafer for various thicknesses from 5.2 nm to 34.6 nm, where the TEG output is increased from 13.9V to 73.5V. Tri-boelectric series are determined by comparing the polarity of output voltage of 2 samples among SnO2, PET, and glass.In conclusion, SnO2, as an intrinsic n-type material, has the most strong tendency to be positive side to lose the electronand PET has the most strong tendency to be negative side to get the electron, and glass to be between them. Therefore,the SnO2-PET combination shows the highest TEG efficiency.

This paper describes a prototype mechanical white noise generator has a source level of more than 170.0 dB (re 1µPa at 1 m) at the frequency range of 10 Hz to 100 kHz. The results of performance evaluation of the generator are as follows. The average source level of the generator measured by a step of 15°in horizontal (0 to 360。, 25 points) was 185.2 (SD (standard deviation): 2.3) dB (re 1µPa at 1 m). The maximum and minimum source levels were appeared at the frequency range of 2.5 to 5.0 kHz and around 100 kHz, respectively. The average source levels at 0°, 90。, 180。and 270° were 162.9 (SD: 10.6), 168.4 (SD: 10.0), 162.1 (SD: 9.1) and 166.5 (SD: 11.1) dB (re 1µPa at 1 m). The average source level measured by a step of 30° in vertical was 184.9 (SD: 2.2) dB (re 1µPa at 1 m). The relative maximum variation width of the source levels in horizontal and in vertical measurement were less than 7.0 dB and 1.0 dB, respectively.

본 연구는 저온기 시설참외 재배 시 탄산가스 발생제(탄산솔)의 사용효과를 구명하기 위하여 수행하였다. 600 m2 크기 하우스에 탄산가스 발생제(100g/1봉)를 10, 20 및 30봉을 각각 매달아 무처리와 비교하였다. 그 결과 무처리구에 비해 처리구에서 탄산가스 농도가 3.0~3.2배 정도 높았다. 그리고 무처리구에 비해 처리구에서 과중이 20.2~22.0g 더 무겁고, 태좌부 당도가 1.5~2.1oBrix 더 높았으며, 색도(a값)도 우수하였다. 또한 탄산가스 발생제 처리한 것이 무처리에 비해 발효과율 및 기형과율이 각각 2.9~3.9%, 5.4~7.3% 감소하였고, 상품과율은 8.7~10.3% 증가하였다. 10a당 상품과 수량은 무처리구의 385.8kg에 비하여 탄산가스 발생제 10, 20 및 30봉 처리 한 것이 각각 10.3%, 14.8%, 16.2% 증가하였다. 이상의 결과를 보아, 저온기 참외 시설재배시 탄산가스 발생제를 시용함으로써 탄산가스 농도가 높아져 광합성이 촉진되어 품질이 향상되고 수량이 증가한 것으로 판단되었다.

The supercritical carbon dioxide Brayton cycle(S-CO2) is one of promising alternatives as a power conversion system of the sodium-cooled fast reactor due to higher cycle efficiency and less reactive working fluid to sodium, compared to the steam Rankine cycle. In a S-CO2 Brayton cycle, turbine, compressors and generator are coupled with a same axis and their rotating speeds are variable in accordance with electrical outputs. However, to synchronize the cycle with a electrical grid, the electrical output of the cycle must has the same frequency with the electrical grid regardless of amount of the turbine output. To deal with this problem, several methods were proposed but each method still has their own weaknesses. In this paper, a new idea will be presented. The idea that the generator with the two reverse rotors are introduced into S-CO2 Brayton cycle and it aims to produce a full range of electricity at a fixed frequency with high efficiency.

Over the past few decades, high-nitrogen austenitic steels have steadily received greater attention since they provide a unique combination of high strength and ductility, good corrosion resistance, and non-magnetic properties. Recently, highnitrogen 18Mn-18Cr austenitic steels with enhanced strength have been developed and widely used for generator retaining rings in order to prevent the copper wiring from being displaced by the centrifugal forces occurring during high-speed rotation. The high-nitrogen austenitic steels for generator retaining ring should be expanded at room temperature and then stress relief annealed at around 400˚C to achieve the required mechanical properties. In this study, four kinds of high-nitrogen 18Mn-18Cr austenitic steels with different nitrogen content were fabricated by using a pressurized vacuum induction melting furnace, and then the effects of nitrogen content, cold working, and stress relieving on tensile properties were investigated. The yield and tensile strengths increased proportionally with increasing nitrogen content and cold working, and they further increased after stress relieving treatment. Based on these results, a semi-empirical equation was proposed to predict the tensile strength of highnitrogen 18Mn-18Cr austenitic steels for generator retaining rings. It will be a useful for the effective fabrication of high-nitrogen 18Mn-18Cr austenitic steels for generator retaining rings with the required tensile properties.

본 연구는 온실 운영에 필요한 전력량을 확보함으로서 온실경영비 절감을 목적으로 태양광발전시스템을 온실에 인접한 건물의 옥상에 설치하여 일사량에 따른 발전량을 실험적으로 검토하였다. 연구결과를 요약하면 다음과 같다. 실험기간 동안 수평면 일사량의 최대, 평균 및 최소 값은 각각 26.1MJ · m−2, 14.0MJ · m−2 및 0.6MJ · m−2 정도였고, 일일 전력량은 각각 약 6.1kWh, 3.7kWh 및 0.01kWh 이었다. 그리고 누계 일사량과 전력량은 각각 약 4,378.2MJ · m−2 및 1,163.2kWh 정도이었다. 그리고 부하에 의해 소비된 적산전력량의 최대, 평균 및 최소값은 각각 4.5kWh, 2.4kWh 및 0.0kWh 정도이었고, 누계 전력량은 739.2kWh 정도로서 발생 전력량의 약 63.5% 에 해당하였다. 본 실험에 사용된 시스템의 평균 소비전 력량을 기준으로 보면, 온풍기의 용량 및 작동시간이 작은 경우는 충분하지만 큰 경우는 부족한 것으로 나타났다. 어레이 표면온도가 상대적으로 높아지면 일사량에 비례해서 발생 전력이 증가하지 않은 것으로 나타났지만, 두 인자 간에 상관계수는 0.851 정도로서 상관관계가 높은 것으로 나타났다.

Recently, A N2 gas generator has become a very popular issue in application to semiconductor production process. An experimental study has been carried out to investigate the production performance as a N2 purity and production of N2 gas generator. The N2 gas generator used a small size system with two adsorption towers and an air compressor as flow rate 20 m3/h. The N2 gas generator system size is width 2270 mm, length 850 mm and height 2135mm. An experimental data has been measured as the variation of a adsorption temperature, adsorption pressure and adsorption time. The results indicate that the N2 gas production increase in case of decreasing adsorption temperature, increasing adsorption pressure and decreasing adsorption time. The N2 purity is highest value of 99.93% when the governor orifice diameter is 0.5 mm.

An Emergency Diesel Generator (EDG) installed in a nuclear power plant is the primary power source, supplying AC power to Class 1E power systems when the main turbine generator and offsite power source are not available. Thus, reliability of the EGD is essential for plant safety and availability. In this paper, the EDG is selected for a Long Term Asset Management (LTAM) strategy and the results are summarized briefly. The LTAM strategy is intended to provide an effective long-term planning tool for minimizing unplanned capability loss and then optimizing maintenance programs and capital investments consistent with plant safety and an identified plant operating strategy. Such an operating strategy might include license renewal or retaining the option for license renewal.