The effects of a Ni coating on the sensing properties of nano ZnO:Ni based gas sensors were studied for CH4 and CH3CH2CH3 gases. Nano ZnO sensing materials were prepared by the hydrothermal reaction method. The Ni coatings on the nano ZnO surface were deposited by the hydrolysis of zinc chloride with NH4OH. The weight % of Ni coating on the ZnO surface ranged from 0 to 10 %. The nano ZnO:Ni gas sensors were fabricated by a screen printing method on alumina substrates. The structural and morphological properties of the nano ZnO : Ni sensing materials were investigated by XRD, EDS, and SEM. The XRD patterns showed that nano ZnO : Ni powders with a wurtzite structure were grown with (1 0 0), (0 0 2), and (1 0 1) dominant peaks. The particle size of nano ZnO powders was about 250 nm. The sensitivity of nano ZnO:Ni based sensors for 5 ppm CH4 gas and CH3CH2CH3 gas was measured at room temperature by comparing the resistance in air with that in target gases. The highest sensitivity of the ZnO:Ni sensor to CH4 gas and CH3CH2CH3 gas was observed at Ni 4 wt%. The response and recovery times of 4 wt% Ni coated ZnO:Ni gas sensors were 14 s and 15 s, respectively.

In order to fabricate the porous Mo with controlled pore characteristics, unique processing by using powder as the source and camphene as the sublimable material is introduced. Camphene-based 15 vol% slurries, prepared by milling at with a small amount of dispersant, were frozen at . Pores were generated subsequently by sublimation of the camphene during drying in air for 48 h. The green body was hydrogen-reduced at , and sintered at for 1 h. After heat treatment in hydrogen atmosphere, powders were completely converted to metallic W without any reaction phases. The sintered samples showed large pores with the size of about which were aligned parallel to the camphene growth direction. Also, the internal wall of large pores and near bottom part of specimen had relatively small pores due to the difference in the camphene growth rate during freezing process. The size of small pores was decreased with increase in sintering temperature, while that of large pores was unchanged. The results are strongly suggested that the porous metal with required pore characteristics can be successfully fabricated by freeze-drying process using metal oxide powders.

The decreased fertility is frequently thought to be problem of cattle production. However, studies figure out that number of these problems is related to bull factors especially in artificial insemination setting. Therefore, this study was designed to investigate the fertility status of bull by their estimated relative conception rate of cows that were inseminated by frozen semen from Korean proven bulls. Here we use the non-return rate (NRR) to access the bull fertility whereas, the NRR was define as the proportion of bulls that semen were used to inseminate cows and the number of cows that did not return for another service within 60 days. The data from 54,388 artificial inseminations (AI) were analyzed from 88 KPN semen. The NRRs of highest and lowest fertile bull were 83.81 and 51.33%, respectively. And mean NRR was 68.27%. In comparison to previously reported study, our data shows 17.38% higher NRR and the absolute value of difference in 50%>NRR and 50%<NRR group was 22.17 and 10.51, respectively (p< 0.001). In conclusion, the decreased fertility might consider as key aspect in achieving considerable conception of cows in existing integrated farming system at Korea.

본 연구의 목적은 강제환기가 적용되는 슬러리 돈사를 대상으로 돼지 생육 단계별 돈방 유형 측면과 계절적 조건에 따른 암모니아와 황화수소의 실내 농도를 측정 분석하여 정량화하는 데 있다. 임신/분만 돈방의 경우 봄철은 5.60(±2.48) ppm과 178.4(±204.8) ppb, 여름철은 2.51(±3.08) ppm과 86.6(±112.5) ppb, 가을철은 4.96(±2.84) ppm과 182.3(±242.6) ppb, 겨울철은 6.82(±3.42) ppm과 206.3(±356.8) ppb로, 자돈방의 경우 봄철은 7.18(±3.26) ppm과 486.0(±190.2) ppb, 여름철은 4.23(±2.95) ppm과 206.4(±186.9) ppb, 가을철은 7.02(±2.65) ppm과 465.4(±156.8) ppb, 겨울철 은 9.25(±3.68) ppm과 618.4(±298.3) ppb로, 육성/비육 돈방의 경우 봄철은 9.26(±3.02) ppm과 604.4(±186.8) ppb, 여름철은 6.78(±3.88) ppm과 312.5(±215.4) ppb, 가을철은 9.34(±2.14) ppm과 578.2(±248.1) ppb, 겨울철은 14.65(±3.15) ppm과 825.3(±316.9) ppb로 분석되었다. 측정 결과 암모니아와 황화수소 모두 돼지 생육 단계별 돈사 유형 측면에서는 육성/비육 돈사>자돈사>임신/분만 돈사의 순서로 나타났고(p<0.05), 계절적 측면에서는 겨울>봄>가을>여름 순서로 조사되었으나 봄철과 가을철 데이터 간의 차이는 통계적으로 입증되지 않았다(p>0.05).

Hydrogen is in the spotlight as an alternative next generation energy source for the replacement of fossil fuels because it has high specific energy density and emits almost no pollution, with zero CO2 emission. In order to use hydrogen safely, reliable storage and transportation methods are required. Recently, solid hydrogen storage systems using metal hydrides have been under extensive development for application to fuel cell vehicles and fuel cells of MCFC and SOFC. For the practical use of hydrogen on a commercial basis, hydrogen storage materials should satisfy several requirements such as 1) hydrogen storage capacity of more than 6.5wt.% H2, moderate hydrogen release temperature below 100˚C, 3) cyclic reversibility of hydrogen absorption/desorption, 4) non toxicity and low price. Among the candidate materials, Li based metal hydrides are known to be promising materials with high practical potential in view of the above requirements. This paper reviews the characteristics and recent R&D trends of Li based complex hydrides, Li-alanates, Li-borohydrides, and Li-amides/imides.

This study is about the qualitative safety assessment for hydrogen gas filling facilities in Korea operating with one-bank type. The purpose of this safety assessment is about the development of components for design, fabrication, assembly, operability of dispenser and systems of the safety. For the qualitative safety assessment method, the study used FMEA(failure mode & effect analysis) and HAZOP(hazard & operability). This study evaluated the safety through FMEA and HAZOP then by referring to P&ID and PFD of hydrogen dispenser, thereby examining the dangerousness of the equipments, defects of the structure and problems of the operation.