• 한국자원식물학회지
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• 제22권6호
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• pp.535-539
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• 2009

The time of seed collection is regarded as one of major concerns to obtain sound seeds. The physical and germinal aspects of Cryptomeria japonica D. Don (Taxodiaceae) seeds were analyzed to determine the optimum harvesting time in Korea. Cones were picked every 10 days from the $30^{th}$ of July to the $30^{th}$ of October in both 2005 and 2006. Seeds were collected from picked cones. Seed size and weight were not significant in two consecutive years. The 1,000-seed weight was 3.3 g for cones picked at the $18^{th}$ of August and 5.3 g for cones picked at the $30^{th}$ of September. The size of seeds was increased as the time of collection from the $18^{th}$ of August to the $30^{th}$ of September: from 19.3 mm to 21.3 mm in length and from 15.8 mm to 18.5 mm in width. Average germination rates in 2005 was 18.3% and 19.6% in 2006. The highest germination rate was 34.3% from seeds collected at the $30^{th}$ of September in 2005. In 2006, the highest germination rate was 31.7% for seeds collected at the same date as the 2005 seeds. After the end of September, germination rate was decreased in both years. The results implied that the best cone picking time for Korean C. japonica seeds is around the end of September.

• 한국재료학회지
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• 제32권10호
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• pp.419-424
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• 2022

Halide perovskite solar cells (PSCs) have improved rapidly over the past few years, and research on the optoelectrical properties of halide perovskite thin films has grown as well. Among the characterization techniques, photoluminescence (PL), a method of collecting emitted photons to evaluate the properties of materials, is widely applied to evaluate improvements in the performance of PSCs. However, since only photons emitted from the film in the escape cone are included, the photons collected in PL are a small fraction of the total photons emitted from the film. Unlike PSCs power conversion efficiency, PL measuring methods have not been standardized, and have been evaluated in a variety of ways. Thus, an in-depth study is needed of the methods used to evaluate materials using PL spectra. In this study, we examined the PL spectra of the perovskite light harvesting layer with different measurement protocols and analyzed the features. As the incident angle changed, different spectra were observed, indicating that the PL emission spectrum can depend on the measuring method, not the material. We found the intensity and energy of the PL spectra changes were due to the path of the emitted photons. Also, we found that the PL of halide perovskite thin films generally contains limited information. To solve this problem, the emitted photons should be collected using an integrating sphere. The results of this study suggest that the emission spectrum of halide perovskite films should be carefully interpreted in accordance with PL measuring method, since PL data is mostly affected by the method.

• 한국산림과학회지
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• 제103권2호
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• pp.175-181
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• 2014

경상남도 남해군의 유사한 입지환경에서 생육한 삼나무 조림지를 대상으로 47년생의 고밀도임분($667tree{\cdot}ha^{-1}$)과 49년생의 저밀도임분($267tree{\cdot}ha^{-1}$)으로 구분한 후 임분밀도에 따른 상대생장식과 현존량 확장계수를 비교하였다. 흉고직경을 독립변수로 하고 각 부위별 건중량을 종속변수로 하는 상대생장식은 고밀도임분의 가지, 저밀도임분의 잎과 종실을 제외하고 상대생장식의 유의성이 인정되었으며(P<0.05), 결정계수($R^2$)의 값은 0.80-0.96 범위였다. 또한 각 임분밀도에 대한 상대생장식(stand density-specific allometric equations)의 회귀계수(slope)에 유의적인 차가 없어(P>0.05), 일괄 상대생장식(generalized allometric equations)의 적용이 가능한 것으로 나타났다. 그러나 현존량 확장계수는 고밀도임분 1.33, 저밀도임분 1.50으로 임분밀도 간 유의적인 차가 있었다(P<0.05). 성숙한 삼나무 조림지의 바이오매스 추정을 위한 상대생장식의 경우 임분밀도의 영향이 크지 않으나 현존량 확장계수의 경우 임분밀도에 따라 상당한 차이가 있었다.