• Journal of Korean Ophthalmic Optics Society
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• v.13 no.2
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• pp.1-7
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• 2008

Purpose: This study was performed to evaluate the changes of lens morphology and tear stability during wearing soft contact lenses (SCLs) which were kept in drying condition like dry eye or became to be dried due to heedless care. Method: SCLs having different water content, thickness or material were rehydrated after being dehydrated artificially 2 or 4 times, and estimated their diameter and radius. Furthermore, the changes of tear film break-up time (TBUT) during SCL wearing were also measured. Result: Due to the dryness, the diameter of both 70% water content SCL and 59% water content SCL decreased, but the decrement was larger in 59% water content SCL. The more 59% water content SCL was dehydrated, the more its radius changed. However, the radius of 70% water content SCL did not change by 2 times dehydration and increased greatly by 4 times dehydration. The reduction of diameter of -1.00 D SCL was greater than that of -9.00 D SCL. Moreover, the radius of -1.00 D SCL increased depending on the frequency of dehydration but that of -9.00 D SCL did not changed. The diameter and radius changes of lotrafilcon B, silicone hydrogel lens, were less than those of hilafilcon B, copolymer of HEMA and N-vinyl pyrrolidone. TBUT during wearing SCLs decreased by wearing dehydrated SCLs. Conclusion: The diameter and radius of dehydrated SCLs as well as TBUT during wearing them were changed in spite of rehydration, which would be the important cause of uncomfortable feeling when people wore dehydrated SCL. The changes of SCL morphology and TBUT differed according to the water content, lens thickness and material.

• Journal of the Korea Society of Computer and Information
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• v.28 no.2
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• pp.99-110
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• 2023

In this paper, we propose a system termed ForestLi that can accurately estimate the diameter at breast height (DBH) and tree height using LiDAR point cloud data. The ForestLi system processes LiDAR point cloud data through the following steps: downsampling, outlier removal, ground segmentation, ground height normalization, stem extraction, individual tree segmentation, and DBH and tree height measurement. A commercial system, such as LiDAR360, for processing LiDAR point cloud data requires the user to directly correct errors in lower vegetation and individual tree segmentation. In contrast, the ForestLi system can automatically remove LiDAR point cloud data that correspond to lower vegetation in order to improve the accuracy of estimating DBH and tree height. This enables the ForestLi system to reduce the total processing time as well as enhance the accuracy of accuracy of measuring DBH and tree height compared to the LiDAR360 system. We performed an empirical study to confirm that the ForestLi system outperforms the LiDAR360 system in terms of the total processing time and accuracy of measuring DBH and tree height.

• Korean Journal of Environment and Ecology
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• v.13 no.3
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• pp.280-287
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• 1999

본 연구는 우리나라 특산식물인 히어리 군락이 지리산 국립공원 동부지역에 대규모로 분포하고 있는 것을 처음으로 발견하여 군락지의 분포 및 맹아지 특성 그리고 군락의 보호대책을 위한 기초자료를 축적하고자 수행되었다. 각 계층별 중요치는 교목층에서 소나무(134.15) 일본잎갈나무, 산벚나무, 비목나무, 신갈나무 등이 우점하였고 아교목층에서는 히어리, 거제수나무. 비목나무, 졸참나무, 노각 나무 그리고 관목층에서는 히어리가 우점하였으며 그 외에 철쭉꽃, 진달래, 생강나무 등이 출현하였다 그리고 맹아지 특성은 1개 방형구(25m2)에 평균 17.75개의 주간이 형성되고 1개 주간당 맹아지 수는 평균 6.00개 고사지는 2.80개로 조사되었다. 흉고직경급별 분포에서 생장지의 경우 흉고직경 1.0-4.0cm 구간에서 전체의 64.78%를 차지하였으며 대부분 2.0-3.0cm 구간에서 54.74%를 차지하여 히어리 군락의 중심계급이었다 흉고직경 1.0cm 이하의 고사지가 전체의 53.16%를 차지하였는데 이는 근주에서 돋아나는 1년생 맹아지가 대부분 고사하였기 때문이었다 특히 히어리의 번식습성은 실생묘에 의한 번식도 가능하지만 본 조사지에서와 같이 수관이 울폐된 지역에서는 주로 근맹아에 의한 번식을 더 선호하는 것으로 나타났다.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.250-250
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• 2013

단일벽 탄소나노튜브(Single-walled nanotubes, SWNTs)는 나노스케일의 크기와 우수한 물성으로 인하여, 전자, 에너지, 바이오 분야로의 응용이 기대되고 있다. 특히 SWNTs의 직경을 제어하게 되면 튜브의 전도성 제어가 훨씬 수월하게 되어, 차세대 나노전자소자의 실현을 앞당길 수 있으며 이러한 이유로 많은 연구들이 현재 행해지고 있다. SWNTs의 직경제어 합성을 위해서는 현재 열화학기상증착법(Thermal chemical vapor deposition; TCVD)이 가장 일반적으로 이용되고 있으며, 합성 촉매와 합성되는 튜브의 직경과의 크기 연관성이 알려진 후로는, 촉매의 크기를 제어하여 SWNTs의 직경을 제어하고자 하는 연구들이 활발하게 보고되고 있다. 특히, 촉매 나노입자의 직경이 1~2 nm 이하로 감소될 경우, SWNTs의 직경 분포가 어떻게 변화할 것인지가 최근 가장 중요한 관심사로 남아 있으나, 이러한 크기의 금속입자는 나노입자의 융점저하 현상이 발현되는 영역이므로, SWNTs의 합성온도 영역에서 촉매 금속입자는 반액체(Semi-liquid) 상태로 존재할 것으로 추측하고 있다. 본 연구에서는 고온의 SWNTs 합성환경에서 금속나노촉매의 유동성을 제한하기 위하여 나노사이즈의 기공이 규칙적으로 정렬된 다공성 물질인 제올라이트를 촉매담지체로 이용하였고, 이 때 다양한 합성변수가 SWNTs의 직경에 미치는 영향을 살펴보고자 하였다. SWNTs의 합성을 위해 실리콘 산화막 기판 위에 제올라이트를 도포한 후, 합성 촉매로서 전자빔증발법을 통하여 수 ${\AA}$에서 수 nm 두께의 철 박막을 증착하였다. 합성은 메탄을 원료가스로 하여 TCVD법으로 실시하였다. 주요변수로는 제올라이트 종류, 증착하는 철 박막의 두께, 합성온도를 설정하였으며, 이에 따라 합성된 SWNTs의 합성수율 및 직경분포의 변화를 체계적으로 살펴보았다. SWNTs의 전체적인 합성수율의 변화는 SEM 관찰결과를 이용하였으며, SWNTs의 직경은 AFM 관찰 및 Raman 스펙트럼의 분석에서 도출하였다. 실험결과, 제올라이트 종류에 따라서는 명확한 튜브직경 분포의 변화 없이 비교적 좁은 직경분포를 갖는 SWNTs가 합성되었으며, 합성온도가 $850^{\circ}C$ 이하로 감소되면 합성수율이 현저히 감소되는 것을 알 수 있었다. 촉매박막의 두께가 1 nm 이상인 경우에서는 직경 5 nm 전후의 나노입자가 형성되었으며, 이때 SWNTs의 합성수율은 높았으나 다양한 직경의 튜브가 합성이 된 것을 확인할 수 있었다. 반면, 촉매입자의 크기가 2 nm 이하에서는 합성수율은 다소 저하되었으나, SWNTs의 직경분포의 폭이 상대적으로 훨씬 좁아지는 것을 알 수 있었다. 추후, 극미세 촉매와 저온합성 환경에서의 합성수율 향상을 위한 합성공정의 개량이 지속적으로 요구된다.

• Journal of Korean Society of Steel Construction
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• v.21 no.5
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• pp.505-514
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• 2009

This paper describes the structural behavior and the ultimate strengths of circular hollow steel (CHS) sections based on a series of compression tests. The ultimate strengths of CHS section columns are mainly dependent on both diameter-thickness ratio and column slenderness ratio. For the CHS sections with a high diameter-thickness ratio, an elastic or an inelastic local buckling may occur prior to the overall buckling, and it may decrease the column strength. Test sections were fabricated from SM400 steel plate of 2.8 mm and 3.2 mm in thickness and were tested to failure. The diameter-thickness ratios of the test sections ranged from 45 to 170 to investigate the effect of local buckling on the column strength. The compression tests indicated that the CHS sections of lower diameter-thickness ratio than the yield limit in the current design specifications showed an inelastic local buckling and a significant post-buckling strength in the local mode. Their ultimate stresses were larger than the nominal yield stress. It was known that the allowable stresses of the sections predicted by the Korean Highway Bridge Design Specifications (2005) were too conservative in comparison with test results. The Direct Strength Method which was newly developed was calibrated for application to the CHS sections by the experimental and numerical results. The Direct Strength Method proposed can predict properly the ultimate strength of CHS section columns whether a local buckling and an overall buckling occur nearly simultaneously or not.

• Journal of Korean Ophthalmic Optics Society
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• v.17 no.4
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• pp.381-388
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• 2012

Purpose: In this study, the changes in the shape of silicone hydrogel lenses, dryness of lens and objective/ subjective symptoms that could be induced by repeating dryness of lens and objective/subjective symptoms were investigated. Methods: After drying and rehydrating of silicone hydrogel lenses with different lens material and thickness for 4 times, their overall diameters and base curves were compared. Subjective symptoms, non-invasive tear break-up time (NIBUTs) and blinking rate were evaluated after wearing dehydrated silicone hydrogel lens. Results: Overall diameter and base curve increased in all tested silicone hydrogel lenses by repeating dryness and rehydration. The degree of change in over all diameter and base curve were variable on the material. There were irregular change of lens parameters in thicker lens. When the subjects wore silicone hydrogel lenses after drying and rehydrating, their NIBUTs were decreased and blink rates were increased regardless of lens material or thickness. In addition, repetitive drying of silicone hydrogel lenses affected the lens fitting. Therefore, subjective symptoms such as itching, pain, irritation, foreign body sensation, dryness tended to be increased. Conclusions: The results obtained from the study may suggest to develop durable silicone hydrogel contact lenses against dry environment since the changes in parameters of silicone hydrogel lens and the subjective discomfort were observed after repetitive drying and rehydration.

• Journal of Korean Ophthalmic Optics Society
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• v.19 no.3
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• pp.285-293
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• 2014

Purpose: In order to find suitable size of soft contact lens for different ages group of elementary student to adults, visible iris diameter(horizontal, vertical) and palpebral aperture size were measured. Methods: Visible iris diameter (horizontal, vertical) and palpebral aperture size were measured in different age groups of total 514 subjects (1028 eyes) who have no eye disease and none history of surgery included cosmetic purpose. Results: No significant difference was found in iris diameter of both horizontal and vertical direction for different groups of age and sex but horizontal direction of palpebral aperture size in middle school students and university students groups and vertical direction of palpebral aperture size in high school student group shows significant difference (p<0.05) by sex. Horizontal visible iris diameter, vertical visible iris diameter, horizontal palpebral aperture size and vertical palpebral aperture size shows significant difference in difference age and sex. Conclusions: Visible iris diameter and palpebral aperture size are affective factor for soft contact lens diameter decision, especially it should considered more intensive for removing uncomfortable feeling of lens wearer.

• Korean Journal of Plant Resources
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• v.20 no.1
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• pp.7-11
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• 2007

This study was conducted by estimate of leaf characteristics and growth performance among selected 20 families progenies of Hovenia dulcis var. koreana Nakai. Mean seedling height and root-collar diameter in whole progenies showed 61.6cm, 6.98mm, respectively. Mean seedling height of KW 2-5 family was 79.3cm and it was higher than that of other families. JN 2-2 family had highest value, 9.16mm, in mean of root-collar diameter. Growth performances of KW 2-5 and JN 2-2 families showed 57% (in seedling height), 53% (in root-collar diameter) superior to those of lowest marked families. The selection level based on growth performances, which are seedling height over 75.0cm and root-collar diameter over 8.0mm, were applied on whole families, and two families selected (KW 2-5, JN 2-2). The selection effects from selected families was evaluated as 125% compared to the mean of whole families. The coefficient of variation (C.V) appeared wide range, $9.4{\sim}42.4%$, in estimated leaf characteristics. Particularly, C.V of petiole length (PL) and petiole diameter (PD) showed 42.4% and 28.7%, respectively. Their were higher value than other leaf characteristics. Analysis of variance for all leaf characteristics were significantly different among families. Also, there had positive correlation between most leaf characteristics except the correlation between leaf length (LL) and leaf morphological index (LMI, LW/LL). Particularly, the correlation between leaf length and leaf width (LW) showed the highest correlation.

• Journal of Korea Foresty Energy
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• v.7 no.1
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• pp.22-27
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• 1987

Above ground biomass production of one-year-old hybrid poplars was investigated to select the best clones which are suitable for short rotation forestry. The results were as follows: 1. Average dry weight of Populus alba X P. glandulosa Fl clones was 2.86 for stem,0.41 for branches 0.70 for leaves and 3.97 t/ha for total. and the ratios of green weight to dry weight were 0.47 for stem,0.36 for branches,0.31 for leaves and 0.42 for total. Dry weight of Populus nigra X P. maximowiczii Fl clones was 1.48 for stem, 0.54 for branches.0.71 for loaves and 2.73t/ha for total, and the ratios of green weight to dry weight were 0.42 for stem. 0.37 for branches, 0.28 for leaves and 0.36 for total. 2. Biomass production (green and dry weight)of Populus alba X P. glandulosa F1 clones can be predicted by diameter measurement only, but biomass production of Populus nigra X P. maximowiczii F1 clones can not be predicted by any of investigated characteristics. 3. Dry weight distribution of pepulus alba X P. glandulosa Fl clones were 73$\%$ for stem, 10$\%$ for branches and 17$\%$ for leaves, and dry weight distribution of P. Populus nigra X P. maximowiczii F1 clones were 54$\%$ for stem, 20$\%$ for branches and 26$\%$ for leaves.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.131-138
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• 2006

This study was conducted to assess the diameter growth patterns of Quercus mongolica and Quercus variabilis dominant species in natural deciduous forests in Korea. The diameter growth data were collected from 83 destructively sample trees for stem analysis in Gangwon-Do region. The relationship between diameter growth and 14 tree measurements was also analyzed. The average diameter growth rate of dominant trees for both species increased until ages of 15-20 years, and exhibited generally constant trend for subsequent ages. The diameter growth rate of both species ranged from 0.09-0.83 cm/yr across the all ages. Average annual diameter growth for last 5 measurement years was 0.28 cm/yr for Quercus mongolica and 0.27cm/yr for Quercus variabilis. The observed growth rate decreased with decreasing crown class. The difference between diameter growth rates for different crown classes was only statistically significant (p<0.0001) for Quercus mongolica. Pearson correlation coefficient between the diameter growth rate decreased with relative diameter (r=0.64), relative height (r=0.61), exposed crown area (r=0.58) and total crown area (r=0.56) for Quercus mongolica. For Quercus variabilis, Pearson correlation coefficient decreased with dbh (r=0.57), crown width (r=0.55), age (r=0.39), competition index (r=-0.39), and height (r=0.35).