In general, the design concepts of earth-observation satellites are established depending on the purposes of utilization such as commercial imagery business, public services, scientific research. Nowadays, The lightweight satellite structure is considered as an effective method for developing the earth-observation satellite. This paper introduces a design concept of the lightweight satellite structure for the constellation of earth-observation satellites. The modular design of the satellite structure is applied to save manpower and shorten the AIT process, in addition, a propulsion module is adopted to allow a hydrazine propulsion system to be installed on the satellite. The finite element method is used for the structural analysis of the satellite. The axial and lateral frequency requirements of satellite structure were verified by mode analysis. also, the margin of safety of satellite structure parts were satisfied with design requirements. As a result, the structural integrity of the suggested satellite structure is verified by mode analysis and static analysis.

본 연구는 염생식물인 퉁퉁마디를 대상으로 하여 신간척지에서 안정적인 재배법을 구명하고자 수행하였다. 먼저 퉁퉁마디의 발아특성을 알아보기 위해 염농도(NaCl 0 ~ 3% 농도) 별발아율 시험을 수행하였다. 10oC에서는 모든 염농도에서 발아속도는 느리나 15일까지 발아가 지속되어, 78 ~ 90%의 발아율을 나타내었다. 20oC이상에서는 4일 안에 최대의 발아율을 나타내었으며, NaCl 3%에서 온도가 올라갈수록 발아율이 저하되는 경향을 보였다. 퉁퉁마디의 질소시비량 별 생육특성을 알아보기 위해 온실포트실험을 실시한 결과, 퉁퉁마디 파종 후 5일 후부터 발아가 시작하였고, 퉁퉁마디의 생육은 질소시비량이 증가할수록초장 및 분지 등이 증가하는 경향을 나타내었다. 또한 염농도에 따른 생육특성을 조사하기 위해 양액 재배 조건에서 염농도에 따른 퉁퉁마디 생육을 실험하였다. 양액조건 상태에서NaCl을 처리하지 않으면 생육이 저조하여 1개월 이후에 고사하기 시작했으며, NaCl을 처리한 구에서는 NaCl 200 mM에서생육이 좋았고, NaCl 500 mM 이상의 염농도에서도 재배가 가능할 것이라 생각된다. 신간척지에서 퉁퉁마디의 어린 싹을6월에 이식하여 질소시비량이 퉁퉁마디 생육에 미치는 영향을조사하였다. 퉁퉁마디의 초장 및 분지수 등이 질소시비량이 증가할수록 유의적으로 증가하였으나, 인산을 비롯한 무기성분함량은 유의적인 차이가 없었다.

본 연구는 한국형 바이오에너지작물로 선발된 물억새인 ‘우람’의 미성숙 화기를 이용한 캘러스 유도 및 식물체 재분 화 조건을 확립하고자 하였다. 캘러스 유도율은 MS배지에 2,4-D 3 mg L-1 첨가에서 93.3%로 높게 나타났으며, 2,4-D 3 mg L-1과 BA 0.1 mg L-1 처리에서 86.7%로 높게 나타났 다. 식물체 재분화율은 BA가 첨가된 배지에서 유도된 캘러스 를 이용하였을 경우 BA가 첨가되지 않은 배지에서 유도된 캘 러스보다 높게 나타나는 것을 확인하였다. 재분화를 위한 배 지 조성은 BA 5 mg L-1과 NAA 0.1 mg L-1 호르몬 조합에 서 재분화율이 86.7%로 가장 효과적이었다. 재분화된 소식물 체는 캘러스로부터 분리하여 MS배지에서 발근을 유도하였을 때 배양 4주 이후 뿌리가 3 cm 이상 신장하였다. 기내에서 발 근이 된 소식물체의 순화를 위해 상토에 이식하고 온실에서 재배하였을 때, 5주 후 지상부가 20 cm 이상으로 신장하여 성공적으로 활착되었다.

This study conducted experiments on the reclaimed land of Saemangeum located in Jeongrabuk-do in order to gain basic information about growth characteristics and yield ability according to soil salinity. Having soil excluding salt as a control group, this study adjusted the specimens’ soil salinity to level 4 and then planted four varieties including Ilmichal Corn to investigate the growth or grain yield according to salinity. About the corn establishment rate according to soil salinity, over 97% up to 3.2 dS m-1 was established, and then, it was reduced gradually according to the increase of concentration. According to the salt concentration of soil more required growth duration from seeding to heading comparing to non-treatment salt was delayed, at 1.6 dS m-1, two days were delayed, at 3.2 dS m-1, four to six days were delayed differently by varieties, and at 4.8 dS m-1, six to 10 days were delayed. About the plant fresh weight according to soil salinity, Chalok 4 and Eolrukchal indicated 93%~97% or so compared with the salt-free one at 1.6 dS m-1, and Chalok No. 4 showed 79% at the salinity of 3.2 dS m-1, too, and it was a relatively higher growth percentage than those of the other varieties. In terms of dried seed weight according to soil salinity, compared with the corns cultivated in the control group, averagely 12.1% was lowered at the time of cultivation at 1.6 dS m-1, and 3.2 dS m-1 40% was lowered, and about 70% was lowered at 4.8 dS m-1. According to the result of examining the point of time that dried seed start to reduce due to soil salinity with the regression equation, soil salinity which starts the reduction of grain weight is 1.67 dS m-1~2.18 dS m-1, and it differs by varieties, and EC of 50% that the yield reduces in half is 2.96 dS m-1 ~4.45 dS m-1. And the degree of influence on each of the growth factors according to soil salinity is founded to be in the order of establishment rate<plant length=the ear’s fresh weight<the plant fresh weight<yield.

This study was performed at Rice and Winter Cereal Crops Department of NICS during 2007 and 2008 to investigate the characteristics of rice leaf emergence and to obtain basic data which can be used for rice growth simulation model by which we can forecast rice growth stage and heading date accurately under different cultivars, transplanting date, and climatic conditions. To confirm leaf emergence rate according to rice maturing ecotype, we surveyed the leaf emergence rate and heading date of Unkwangbyeo, Hwayoungbyeo and Nampyeongbyeo which are early maturing, medium maturing and medium-late maturing cultivars, respectively, according to seedling raising duration and transplanting time. When seedling duration was 15 days, the growth duration between transplanting time and completion of flag leaf emergence on main culm were 51.5~78.3 days in Unkwangbyeo, 55.3~87.9 days in Hwayoungbyeo and 58.4~98.4 days in Nampyeongbyeo, respectively. When seedling duration was 30 days, they were 50.1~75.5 days in Unkwangbyeo, 52.4~84.7 days in Hwayoungbyeo and 56.4~93.8 days in Nampyeongbyeo, respectively. As transplanting time delayed, the emerged leaf number after transplanting decreased in all rice cultivars. The cumulative temperature between transplanting time to completion of flag leaf elongation on main culm were 1,281~circC~1,650~circC in Unkwangbyeo, 1,344~circC~1,891~circC in Hwayoungbyeo and 1,454~circC~2,173~circC in Nampyeongbyeo, respectively. Leaf emergence rate on main culm were precisely represented by equation, y = y0 + a / [1 + exp( - (x - x0 ) / b)]c, when we used daily mean temperature as variable.