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        검색결과 12

        1.
        2018.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        본 연구의 목적은 전국에 분포하는 일본잎갈나무 임분에 대해 산림시업 수행이 직경분포변화에 미치 는 영향에 대해 분석하였다. 본 연구에 사용한 자료는 국가산림자원조사 중 시업지 232plots, 비시업지 47plots의 고정표본점 자료를 활용하였다. 직경분포모델은 Weibull 누적분포함수를 사용하였으며, 분석 방법에는 백분위(Percentile)에 근거한 직경모형추정, 백분위(Percentile)에 대한 모수복구 방법을 사용 하였다. 개발한 모델을 이용하여 산림시업의 수행여부에 따른 시나리오(임령, 지위지수, 임분밀도) 별 임분생장량을 예측한 결과, 시업지 임분의 최대임목본수를 차지하는 평균 흉고직경의 이동이 비시업지 임분에 비해 이동량과 생장량이 더 높게 나타났으며, 대경목이 차지하는 비율 또한 시업지 임분이 높게 예측되었다. 본 연구의 결과는 직경급에 따른 목재생산량의 장기적인 예측과 동적인 임분구조 해석에 기초적인 정보를 제공할 수 있을 것으로 사료되어진다.
        4,200원
        2.
        2018.05 구독 인증기관·개인회원 무료
        The ride quality (i.e. smoothness) is a key factor for evaluating the construction quality of expressway asphalt pavement. Conventionally, three paving devices are widely used to control the surface layer thickness: leveling sensor (i.e. LS), short-range-surfacing-contact-ski (i.e. SSCS) and long-range-surfacing-contact-ski (i.e. LSCS). However, each of these levelling tools presents one major drawback. In the case of LS, if the original sub-layer evenness is poor, the final asphalt pavement surface and its smoothness will be negatively affected. The SSCS cannot assure satisfactory smoothness when relatively long paving section (in the order of 10 km) are paved. While the LSCS would reduce the drawback of the SSCS, its weight on the one hand and its length on the other discourage its use in the paving site especially for curved sections. In this paper, a next generation pavement smoothness leveling equipment, known as non-contact-digital-ski (i.e. NCDS) was implemented, evaluated and compared to the conventional equipment leveling device. The international Roughness Index (IRI m/km) was measured on sections paved with and without NCDS and the results visually and statistically compared. In addition, for the same sections, the modulus of the pavement layers was computed and compared by means of Falling Weight Deflectometer (i.e. FWD). It was observed that when NCDS is used for asphalt pavement overlay of existing concrete pavement, significant improvement in IRI (i.e. IRI<1.0m/km) and consistently uniform elastic modulus could be achieved compared to the conventional levelling and paving method.
        10.
        2004.06 KCI 등재 서비스 종료(열람 제한)
        Effects of ambient and elevated ~textrmCO2 and high temperature, and their interactions with zero and applied nitrogen supply (NN-no nitrogen and AN-applied nitrogen) were studied on soybean (Glycine max L.) in 2001. In this experiment, elevated ~textrmCO2 (650 ~mu~textrmmol.~textrmmol-1 ) and temperature (+5~circ ) increased total dry mass at final harvest by 125% and 119% and seed weight per plant by 57% and 105% for NN and AN plants, respectively. Although the influence of temperature and temperature x ~textrmCO2 were not significant, the influences of ~textrmCO2 concentration and temperature x ~textrmCO2 concentration were significant on total dry weight and seed weight, respectively. In particular, seed weight per plant was increased, while weight per one hundred seed weight was decreased with elevated ~textrmCO2 and temperature. The N supply increased biomass and seed weight per soybean plants. The results of this study suggest that the long-term adaptation of soybean growth at an elevated ~textrmCO2 concentration and high temperature might potentially result in a increase in dry matter production and yield.