논토양 중에 벼의 근권에 서식하여 벼에 협력적인 관계로 질소를 공급해 주는 질소고정 미생물인 Klebsiella oxytoca를 미생물 비료로 활용하기 위한 새로운 질소고정 균주의 육종을 시도하여 다음과 같은 결과를 얻었다. 1. Klebsiella oxytoca NG13, Klebsiella oxytoca SH31, Klebsiella oxytoca SH161에 pMC71A를 형질전환 한 경우, 무질소 배지에서 원래의 균주의 질소고정력에 비해 질소고정력이 각각 6.4배, 17.2배, 13.5배 증진되었다. 2. 15mM의 NH_4^+ 존재하에서, Klebsiella oxytoca NG13, Klebsiella oxytoca SH31, Klebsiella oxytoca SH161의 경우는 모두 질소고정능의 완전한 저해를 받은 반면 pMC71A가 도입된 Klebsiella oxytoca NG13 /pMC71A, Klebsiella oxytoca SH31 /pMC71A, Klebsiella oxytoca SH161/pMC71A, 의 경우는 무질소 배지에서의 질소고정력에 비해 각각 13.7%, 7.7%, 6.2%의 질소고정 활성을 보였다.

Difference in immobilization effect of heavy metal-contaminated soil between two different amendment methods was evaluated; 1) both of steel slag (i.e., consisted in solid phase) and soluble phosphate (i.e., consisted in liquid phase) were simultaneously applied to contaminated soil (i.e., simultaneous amendment methods) and 2) soluble phosphate and steel slag was applied sequentially to the contaminated soil (i.e., sequentially amendment methods). The application rate of stabilizers to soils was determinated based on weight/weight ratio of 5% for steel slag and PO4/Pb molar ratio of 2.0 for phosphates, respectively. To identify difference of immobilization effect to test soil, three different soluble phosphates, such as Na2HPO4·12H2O, Ca(H2PO4)2·H2O and (NH4)2HPO4 were used. The sequential amendment was 6 ~ 27% more effective than the simultaneous amendment in terms of the immobilization efficiency for Pb, Cu, and Cd in the contaminated soil. There was little difference in case of Zn. Among the three phosphates tested, (NH4)2HPO4 was clearly the most effective. Residual form of heavy metals concentration in sequentially methods is higher than those in simultaneously methods. At the same time, more exchangeable and carbonate-bound forms of heavy metals in simultaneously methods were observed than in sequentially case. These result implies that the sequential amendment method was more effective than the simultaneous amendment method in terms of heavy metal immobilization in the contaminated soil.

거친 바다를 운항하는 선박의 경우 횡 동요로 인해 선박 내의 장비운영 문제 및 탑승객들에게 큰 불편함을 초래한다. 따라서 횡동요 감쇠를 위한 목적으로 빌지 킬, 핀 안정기, 자이로스코프, ART(Anti-Rolling Tank), 타, 플랩 등 다양한 횡 동요 감쇠장치들이 사용되고 있다. 콴다효과는 콴다제트가 곡면의 표면을 따라 흐르며 주위 유동의 순환을 증가시켜 양력을 효과적으로 발생시키는 방법으로 핀의 양력성능을 향상시킬 수 있다. 본 연구에서는 모형시험 및 수치계산을 통해 콴다효과를 적용한 고정식 핀 안정기의 사용가능성을 검토하였다. 그 결과 받음각이 0˚에서, 제트모멘텀을 Cj = 0.25 만큼 공급할 때, 기준 핀의 최대 작동각(26˚)에서 발생되는 양력과 동일하게 발생되는 것으로 나타났다. 즉 받음각을 변화시키는 기존의 핀 안정기와 달리 받음각을 고정하고, 콴다효과를 통한 제트유동제어만으로 선박의 횡 동요를 능동적으로 제어 할 수 있을 것으로 보인다.

This study deals with the case of a fixed floating structure(FFS) at the mouth of a rectangular harbor under the action of waves represented by the linear wave theory. Modified forms of the mild-slope equation is applied to the propagation of regular wave over constant water depth. The model is extended to include bottom friction and boundary absorption. A hybrid element approximation is used for calculation of linear wave oscillation in and near coastal harbor. Modification of the model was necessary for the FFS. For the conditions tested, the results of laboratory experiments by Ippen and Goda(1963), and Lee (1969) are compared with the calculated one from this model. The cases of flat cylinderical structures, both fixed and floating, were taken to be in an intermediate water depth.