• Journal of Korean Society of Forest Science
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• v.87 no.3
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• pp.483-492
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• 1998

The objective of this study was to investigate the site and growth characteristics of Kalopanax septemlobus mixed with other hardwoods growing at Mt. Joongwang area located in Pyungchang-gun, Kangwon-do. The K. septemlobus stands were located at 1,000m to 1,200m in altitude, steep slope, and ridge-slope areas with aspects facing northeast to northwest. The K. septemlobus stands showed deep A soil layer with high soil moisture and soil nutrients. Major over-story species were Quercus mongolica, Acer pictum, Acer pseudosieboldianum and Carpinus cordata. The herbaceous vegetation was predominantly consisted with Pimpinella brachycarpa, Meehania urticifolia, Ainsliaea acerifloia and Polystichum species. The annual mean diameter increment of K. septemlobus was 2.4mm/year, with high diameter growth at lower altitude, south aspect and valley areas.

• Journal of Chest Surgery
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• v.56 no.4
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• pp.255-261
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• 2023

Background: The surgical threshold for bicuspid aortic valve (BAV)-related aortopathy is a matter of debate due to its uncertain etiology and prognosis. This study investigated the prognosis of unrepaired BAV aortopathy in patients undergoing surgical aortic valve replacement (SAVR). Methods: We retrospectively analyzed data from 720 patients (age, 60.8±11.5 years; 246 women) who underwent SAVR for BAV disease without aortic repair between 2005 and 2020 at Asan Medical Center. The clinical endpoints were defined as occurrences of sudden death, aortic dissection or rupture, and elective aortic repair. To estimate postoperative changes in the dimensions of the unrepaired aorta, the individual annual aortic expansion rate was calculated. Multiple linear regression models were used to evaluate the risk of aortic expansion. Results: The mean ascending aortic diameter was 39.5±4.6 mm, and 299 patients (41.5%) had a baseline ascending aorta diameter >40 mm. During 70.0±68.3 months of follow-up, the mean annual aortic expansion rate was 0.39±1.96 mm/yr, no aortic dissection or rupture was observed, and sudden deaths were reported in 12 patients (0.34% per person-year). Linear regression analysis revealed no significant correlation between the baseline ascending aortic diameter and postoperative aortic expansion (R²=0.004, β=-0.84, p=0.082). Conclusion: In selected patients undergoing SAVR for a BAV (<55 mm), the risk of adverse aortic events was very low. As this observation contradicts current practice guidelines advocating for proactive aortic replacement in dilated ascending aortas measuring >45 mm, the study results need further validation by studies involving larger populations or randomized controlled trials.

• Journal of the Korean Wood Science and Technology
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• v.48 no.6
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• pp.807-819
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• 2020

The aim of this study was to investigate the anatomical characteristics of Quercus mongolica infested by oak wilt disease. To analysis the anatomical characteristics of the wood specimens infested by the oak wilt, the anatomical structures of an infected wood, a dead wood, and sound wood were observed at 10-year-old intervals from 10 to 50 annual rings using both an optical and a scanning electron microscope. The fiber length was measured in units of 5 annual rings from the pith, and the diameter of the vessel element and the ratio of the vessel including the tyloses were measured for each 10 annual ring. In the cross section, on the infected and dead wood specimens, mycelium was also observed with the tyloses in the vessel. There was no signification difference between the wood specimens in the fiber length and the vessel diameter of the vessel element. The fiber length was not difference after 20-30 annual rings which is a part of juvenile wood. The average of the vessel ratio including tyloses in the infected wood was the highest. Especially, the ratio of tyloses was the highest 40-50 annual rings in the infected wood and the dead wood. Therefore, the large difference between the infested wood by oak wilt and the sound wood was the ratio of tyloses. This result can be used as a basic data to utilize the infested wood.

• Journal of Korean Society of Forest Science
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• v.60 no.1
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• pp.24-29
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• 1983

This study was carried out to compare the diameter increment of seven major selected tree species which grow wild in middle area of Korea. The results obtained were summarized as follows. 1) The difference in annual diameter increment among seven species according to D.B.H. classes showed to be the strongest in Juglang mandshurica, the second rank Corpus controversa, the third rank Betula platyphylla, the fourth rank Tilia amurensis, the second rank Fraxinus mendshurica, the sixth rank Populus davidiana, and the weakest in Ulmus davidiana. 2) Total diameter increment among seven species according to tree age classes were ranked as follows: Juglans mandshurica, Cornus controversa, Betula platyphylla, Tilia amurensis, Fraxinus mandshurica, Populus davidiana, and Ulmus davidiana. 3) Juglans mandshurica showed the highest diameter increment in comparison with other six species, while diameter increment in Ulmus davidiana and Populus davidiana decreased in earlier age than other species.

• Journal of the Korean Wood Science and Technology
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• v.25 no.2
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• pp.117-126
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• 1997

In fast grown softwood, there are very large changes in material properties going outward from the pith to bark such as anatomical, physical and mechanical characteristics. Some of variations in anatomical properties with annual ring were then examined from Pinus koraiensis, Larix leptolepis, and Chamaecyparis obtusa, which are major softwoods of plantation in Korea. The large variations of annual ring width during young age of tree tended to stabilize after 25year through the transitional period in 17~23year. The ring density was 1.5~2.4 in 1~10year period, and 3.5~6.3 in 30~35year period, in which juvenile and mature wood were certainly assumed to be formed, respectively. Variations of tracheid length showed functional relationships with annual rings as logarithm. Demarcation between juvenile wood and mature wood could be 16~19year, which was determined from increase rate of tracheid length of 0.2%. Cell wall thickness increased with increase of annual ring even though large variations were observed as well. Variations of cell wall thickness within species were pronounced in latewood than earlywood. The increase of cell wall thickness from juvenile wood to mature wood was predominant in Larix leptolepis as 2.0times, and least in Chamaecyparis obtusa as 1.1 times. Cell diameters showed trends of increase during young age of 1~15year, and consistent afterward. The variations of cell diameter between radial and tangential direction were greater in latewood, and most pronounced in Chamaecyparis obtusa.

• Journal of Environmental Health Sciences
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• v.49 no.1
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• pp.30-36
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• 2023

Background: Among various pollutants, fine particle (PM_2.5, defined as particle less than 2.5 nm in aerodynamic diameter) shows the most consistent association with adverse health effects. There is scientific evidence documenting a variety of adverse health outcomes due to exposure to PM_2.5. Objectives: This study aims to assess the health benefits of that would be achieved by meeting the World Health Organization's air quality guidelines for PM_2.5 using AirQ+ and BenMAP. Methods: We estimated PM_2.5 related health benefits in Korea from implementing the World Health Organization's air quality guidelines (annual average 5 ㎍/m³ and 10 ㎍/m³) and Korea's National Ambient Air Quality Standard (annual average 15 ㎍/m³). We used World Health Organization's AirQ+ and U.S. Environmental Protection Agency's Environmental Benefits Mapping and Analysis Program. Results: The annual number of avoided PM_2.5 related premature deaths exceeding WHO guideline levels was assessed using both AirQ+ and BenMAP. We estimated that the health benefits of attaining the World Health Organization's air quality guidelines for PM_2.5 (annual average 5 ㎍/m³) would suggest an annual reduction of 26,128 (95% confidence interval [CI]: 17,363~34,024) and 26,853 (95% CI: 18,527~34,944) premature deaths. Conclusions: Our study provided useful information to policy makers and confirms that the reduction of PM_2.5 concentration would result in significant health benefits in Korea.

• The Korean Journal of Malacology
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• v.4 no.1
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• pp.30-41
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• 1988

The gonadal development, the annual reproductive cycle and the first sexual maturity of surf clam, Mactra veneriformis Reeve were studied histologically. Speciemens were monthly collected at the intertidal zone of Naechodo, Chollabuk-do, Korea, for one year from March 1986 to February 1987. Sexuality of the clam is dioecious. The gonads were located between the subregion of mid-intestinal gland in the visceral cavity and the reticular connetive tissues of the foot, The ovary is composed of a number of ovarian sacs, and the testis comprise several testiculat lobules. The undifferentiated mesenchymal tissues and eosinophilic granular cells function as nutritive cells in the early stage. The ripe eggs were about 50-60${\mu}{\textrm}{m}$ in diameter, and they were wurroundedby the gelatinous membranes. The spawing period was from early June to September the main spawning occurred beetween July and August when the water temperature reached above 24$^{\circ}C$. The annual reproductive cycle of this species could be classified into five successive stages: multiplicative(January to March), growing(March to May), mature(April to August), spent(June to September), degenerative and resting(September to February). The monthly changes of fatness coefficient closely correlated with the annual reproductive cycle. Percentages of the first sexual maturity of female and male clams were over 50% among those individals ranging from 2.1 To 2.5cm, and 100% in those over 2.6cm in shell length.

• Journal of Forest and Environmental Science
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• v.39 no.3
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• pp.119-127
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• 2023

In this study, quantitative models were applied to case parks to estimate the carbon reduction by trees, which was compared and analyzed at the tree and park levels. At the tree level, quantitative models of carbon storage and uptake differed by up to 7.9 times, even for the same species and size. At the park level, the carbon reduction from quantitative models varied by up to 3.7 times for the same park. In other words, carbon reduction by quantitative models exhibited considerable variation at the tree and park levels. These differences are likely due to the use of different growth environment coefficients and annual diameter at breast height growth rates and the overestimation of carbon reduction due to the substitution of the same genus and group model for each tree species. Extending the annual carbon uptake per unit area of the case park to the total park area of Chuncheon a carbon uptake ranging from a minimum of 370.4 t/yr and a maximum of 929.3 t/yr, and the difference can reach up to 558.9 t/yr. This is equivalent to the carbon emissions from the annual household electricity consumption of approximately 2,430 people. These results suggest that the indiscriminate application of quantitative models to estimate carbon reduction in urban trees can lead to significant errors and deviations in estimating carbon storage and uptake in urban greenspaces. The findings of this study can serve as a basis for estimating carbon reduction in urban greening research, projects, and policies.

• Journal of the Korean Wood Science and Technology
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• v.44 no.6
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• pp.903-912
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• 2016

Morphological and anatomical evaluation of grafted P. merkusii have been undertaken to obtain the information about compatible and incompatible symptoms of 18 years old grafts based on morphological observation and microscopic analysis. Samples of compatible and incompatible grafts were obtained from previous research conducted by the Silviculture Departement Team in 1994. Result showed that compatible grafts have normal stem form and secondary growth (diameter growth), but some abnormality symptoms like undulated pattern of annual growth rings, phloem thickening and abnormality resin ducts in inner and middle parts of the union area occurred. Incompatible ones showed abnormality of the stem form, cortex-bark necrosis and swelling in the union area. Microscopic observation showed abnormality of all parts of the union, undulated pattern of annual growth rings, phloem thickening, abnormal resin ducts, low numbers and discontinuity of vascular elements in the union area.

• Biomedical Science Letters
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• v.10 no.4
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• pp.435-445
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• 2004

The characteristics of the testis and the annual cycle of the seminiferous epithelium of the Miniopterus schreibersi fuliginosus were examined by optical microscopy. The testis weight and diameter of the seminiferous tubules were increased gradually from May to July, and the highest activity was observed in August. The size then decreased rapidly from October. Spermatogenesis began in May, peaked in August, and was suspended from October to April in the following year. Spermatocytogenesis were produced from May to July. Spermiogenesis occurred from August to September. In particular, immature spematogenic cells in the seminiferous tubules were engulfed by the phagocytosis of Sertoli cells in October. From November to April, the seminiferous tubuly contained only Sertoli cells and Ad spermatogonia. Therefore, the periodic changes in the seminiferous epithelium of M. S. fuliginosus suggest that a long hibernation is an adaptive strategy for the preservation of energy and the regulation of the breeding cycle.