방사선 생물학적 효과(Radio biological effectiveness, RBE)를 선량에 대부분 의존하는 X선과 달리 탄소빔 의 경우 LET의 변화량은 반드시 고려되어야할 사항이다. 이는 X선 과는 극히 대조적인 선량 분포도를 갖 고 있기 때문이며 LET의 변화량이 중요한 이유가 된다. 따라서 기존의 LQ 모델이나 회복생존모델의 경우 이러한 점이 감안되지 않아 탄소빔의 분할 조사 시 문제점을 보이며 오류를 보이고 있다. 본 연구에서는 약 75keV/μm의 고LET 탄소빔 분할 조사 시 Potentially Lethal Damage Repair (PLDR)의 발생양을 확인하고 약 13keV/μm 저LET 조사와 비교하여 현저히 감소하였음을 확인하였다. PLDR의 감소에 따라 생존율 또한 감소하였다. 따라서 탄소빔의 생물리학적 모델 개발에 LET의 변화량은 반드시 고려되어져야 할 것으로 보 인다.

The purpose of this study is to analyze willingness to pay (WTP) for organic agricultural products. To accomplish the objective of the study, a consumer survey was conducted. Based on the pilot survey results, parametric survival model was used to analyze the WTP for organic products. The estimation results showed that the WTP for organic agricultural products is 1.4-fold when compared with the conventional products, which is lower than the current price by about 30 percent. The analytical results also showed that such variables as gender, recognitions for organic agricultural products, and consumers’ income have very significant effects on the WTP, and that there are no differences among WTPs by consumption goals. Based on major findings, the most effective countermeasure was suggested for expanding of organic food consumption through the premium reduction of organic products. Reducing the costs of production and distribution, supporting farmers’ income by direct payment system were presented. Furthermore, it is needed to allocate more budget for promoting the consumption and distribution of organic agricultural products, and for enhancing conservation of agricultural environment.

The purpose of this study is to develop rural population model adapting cohort survival method with sift-share effects. Administrative district in this study is below Myun: about 2,000 population. Population data of rural area in 1990, 1995, and 2000 by age cohort were selected for applying developed model. Damping coefficient from population data was calculated as 7% and results applying this coefficient in rural population data below the error from 12% to 1.06%. In detail, most of cohorts fitted with developed model except from 15 to 29 age groups. Application result of small population area; DaesulMyun revealed that main factor of population change is not natural change but migration.