• Journal of the Korean Wood Science and Technology
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• v.52 no.1
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• pp.1-12
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• 2024

Betung bamboo (Dendrocalamus asper) is used as a building and handicraft material in Indonesia; however, bamboo needs to be dried to increase its stability. This study aimed to evaluate the efficiency of drying bamboo using solar energy and different drying oven designs. The betung bamboo pieces were dried using a direct solar dryer (direct drying) and an indirect solar dryer (indirect drying) and then the decrease in levels that occurred based on the relative humidity (RH) and temperature values achieved in the two dryers were compared. The highest average temperature in the direct indirect drying oven compartment was 60.1 ± 13.1℃ with 19.9 ± 16.4% RH and 60.2 ± 11.9℃ with 19.5 ± 15.5% RH, respectively. The drying defect in indirect drying was lower than that in direct drying, and indirect drying had a 61.7% greater average water loss than direct drying with significant difference (95%, analysis of variance) based on water loss/compartment volume parameters. Thus, the solar drying oven can be used to air-dry bamboo (14%) for 7 d from an initial moisture content of 70%-80% in bamboo strips. The results of this research can be used for small-scale bamboo processing industries that have limited use of electrical energy with quite good results.

• Journal of Korean Society of Forest Science
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• v.86 no.3
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• pp.378-390
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• 1997

Ten total populations of Korean fir (Abies koreana Wilson) and Manshurian fir [A. nephrolepis (Traut.) Maxim.] were sampled from south Korea to investigate patterns of intraspecific variation in these species and to evaluate a recognition of the two species. Principal components analysis and cluster analysis were performed both on seed-cone data and on needle morphology data. The characters that contributed most to the separation between A. koreana and A. nephrolepis along three principal components axis were leaf width, length of seed, width of seed wing, length of seed wing, cone width, width of scale, and length of bract tip, but these characters were not diagnostic because of overlap in reality. Therefore, all these characters were not reliable in distinguishing these two taxa including bract position (exerted and recurved vs. exerted and straight). The individuals of A. koreana from Mt. Chi-ri appeared quite unique probably on account of its larger cone size and longer scale tip, while those from Mt. Hal-la of A. koreana were generally distinct from others in terms of their larger seed and seed wing and longer scale width. The Mt. Duk-yu specimens of A. korecana appeared somewhat smaller but more data were needed due to the small sampling size. Generally, the gradual clinal geographic trends made evident by the position of resin ducts in leaves of A. koreana can be detected. The southern populations, Mt. Hal-la (an insular population) were generally distinct from the northern populations (Mt. Chi-ri, Mt. Ga-ya and Mt. Duk-yu) in terms of their position of resin duct (medial, within mesophyll vs marginal, close to epidermis : 100% vs 75 or 50%). Although no sharp boundary separating these two species could be detected based on cone and needle morphology, the observed clinal pattern was distinct in northern populations of A. koreana and southern population of A. nephrnlepis. In a preceding study of the flavonoids variation of 20 species in eastern Asia, flavanone (5-deoxyflavanone) was found to be characteristic of A. faxoniana Rehder et Wilson, A. georgei Orr of China and A. koreana of Korea. A. faxoniana, which is assumed to be primitive species, has position of resin duct relative to both the medial and the marginal, while A. georgei and A. koreana are identified by marginal position of resin duct. With respect of foliar flavonoids chemistry, A. koreana was distinct from A. nephrolepis : the southmost samples (Mt. Hal-la and Mt. Chi-ri) contained additional flavonoids derivatives (mainly flavanone) that were not found in the northmost samples of A. nephrolepis except a few individuals from Mts. Seo-rak and Tae-bak populations of Kwang-won province. The presence of A. koreana type flavonoids in two Chinese species suggested that position of resin duct may be a phyletic character. Abies koreana including two Chinese taxa, exhibited the most elaborate and specialized flavonoids profile within the Abies in eastern Asia. Contrary to our initial expectations, the apparent intermediates between A. nephrolepis and A. koreana in Duk-yu and Ga-ya mountains were found. The pattern of variation on position of resin duct and flavonoids chemistry in these populations of A. kareana suggested that genetic interchange or natural hybridization had occurred between these two species. The evidence needed to resolve the status of this taxon is still inconclusive in our opinion until intermediate individuals from Mts. Duk-yu and Ga-ya show indication of hybridization between the two species.

• Journal of Wetlands Research
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• v.19 no.1
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• pp.16-29
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• 2017

It is known that large-scale deforestation has occurred in North Korea due to economic failures since the 1990s, and this is expected to greatly change the characteristics of the hydrological cycle. In this study, hydrological cycle simulation was carried out for the period of about 30 years from 1981 to 2013 for the entire Korean peninsula using the VIC model, a land surface hydrology model. The simulation results are summarized as follow. First, the runoff ratio is 55%~70% in South Korea and 38~56% in North Korea. In particular, it is worth noting that despite the small runoff ratio, the variation is about 28% larger than the South Korea's 15%. The rate of evapotranspiration was larger than that of South Korea. That is, the rate of evapotranspiration in South Korea is 20~35% and in North Korea it is 25~46%. However, the rate of change was 21% in the case of North Korea and slightly larger than 15% in South Korea. Third, South Korea has an average of 34% in soil moisture and 27% in North Korea. However, unlike the simulated results of the runoff ratio and the evapotranspiration rate, the difference in the variation of soil moisture in South Korea and North Korea over the entire period was similar with 8%. As a result, we can confirm that the difference of hydrological cycle characteristics between South Korea and North Korea has been increased since the 1990s, when the forest destruction of North Korea became serious. In the case of South Korea, there is little difference in the hydrological cycle characteristics. In North Korea, however, there is a distinct difference, which is also a result reflecting the difference in the effects of forest destruction.

• Journal of Korean Society of Forest Science
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• v.63 no.1
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• pp.61-68
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• 1984

The oak-mushroom is one of the special minor products utilizing hardwoods, such as oaks in the mountaineous villages, as a food for health and export in Korea. However, oak-mushroom farmers have been faced the problems such as small cultivation scale, unskilled technique of production, management of cultivation, and low productivity. It is now a turning point presenting the optimum and reasonable management techniques to increase the productivity with consideration of balanced income and expenditure. This report analyzed the investment effectiveness of cultivation. The financial rate of return (FRR) of oak-mushroom cultivation is as high as 10.3 percent compared with that of other farmings. Moreover, the FRR remarkably increased with increased cultivation scales. The FRR could be highly improved if the price of both mushroom-logs and dried mushroom products, is stable and the cultivation techniques for higher productivity are developed. The policy providing the constant price of raw materials and mushroom products, and new advanced cultivation techniques enable the enhancement of investment for the oak-mushroom cultivation.

• Korean Journal of Agricultural and Forest Meteorology
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• v.20 no.2
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• pp.228-232
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• 2018

Process-based crop models have been used to assess the impact of climate change on crop production. These models are implemented in procedural or object oriented computer programming languages including FORTRAN, C++, Delphi, Java, which have a stiff learning curve. The requirement for a high level of computer programming is one of barriers for efforts to develop and improve crop models based on biophysical process. In this study, we attempted to develop a Chinese cabbage model using Microsoft Excel with Visual Basic for Application (VBA), which would be easy enough for most agricultural scientists to develop a simple model for crop growth simulation. Results from Soil-Plant-Atmosphere-Research (SPAR) experiments under six temperature conditions were used to determine parameters of the Chinese cabbage model. During a plant growing season in SPAR chambers, numbers of leaves, leaf areas, growth rate of plants were measured six times. Leaf photosynthesis was also measured using LI-6400 Potable Photosynthesis System. Farquhar, von Caemmerer, and Berry (FvCB) model was used to simulate a leaf-level photosynthesis process. A sun/shade model was used to scale up to canopy-level photosynthesis. An Excel add-in, which is a small VBA program to assist crop modeling, was used to implement a Chinese cabbage model under the environment of Excel organizing all of equations into a single set of crop model. The model was able to simulate hourly changes in photosynthesis, growth rate, and other physiological variables using meteorological input data. Estimates and measurements of dry weight obtained from six SPAR chambers were linearly related ($R^2=0.985$). This result indicated that the Excel/VBA can be widely used for many crop scientists to develop crop models.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.4
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• pp.217-224
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• 2010

This study was carried out to quantify potential effects of the surrounding ocean on the observed air temperature at coastal weather stations in the Korean Peninsula. Daily maximum and minimum temperature data for 2001-2009 were collected from 66 Korea Meteorological Administration (KMA) stations and the monthly averages were calculated for further analyses. Monthly data from 27 inland sites were used to generate a gridded temperature surface for the whole Peninsula based on an inverse distance weighting and the local temperature at the remaining 39 sites were estimated by recent techniques in geospatial climatology which are widely used in correction of small - scale climate controls like cold air drainage, urban heat island, topography as well as elevation. Deviations from the observed temperature were regarded as the 'apparent' sea effect and showed a quasi-logarithmic relationship with the distance of each site from the nearest coastline. Potential effects of the sea on daily temperature might exceed $6.0^{\circ}C$ cooling in summer and $6.5^{\circ}C$ warming in winter according to this relationship. We classified 25 sites within the 10 km distance from the nearest coastline into 'coastal sites' and the remaining 15 'fringe sites'. When the average deviations of the fringe sites ($0.5^{\circ}C$ for daily maximum and $1.0^{\circ}C$ for daily minimum temperature) were used as the 'noise' and subtracted from the 'apparent' sea effects of the coastal sites, maximum cooling effects of the sea were identified as $1.5^{\circ}C$ on the west coast and $3.0^{\circ}C$ on the east and the south coast in summer months. The warming effects of the sea in winter ranged from $1.0^{\circ}C$ on the west and $3.5^{\circ}C$ on the south and east coasts.

• Journal of Korean Society of Forest Science
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• v.90 no.5
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• pp.600-607
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• 2001

This study was conducted to estimate the capability of Populus alba ${\times}$ glandulosa and Betula schmidtii for the uptake of Pb from the lead-contaminated soil and their tolerance to lead. Rooted cuttings in the former species and germinated seedlings in the latter species were planted in pots and irrigated with Pb-containing water for 60 days. In both tree species, growth inhibition was observed in 800, and 1,500ppm of $Pb(NO_3)_2$. Most Pb was accumulated in plant roots and only a small portion was transported to the shoots. The translocation rates of Pb for B. schmidtii and P. alba ${\times}$ glandulosa were 1.6-2.6% and 1.2-1.6%, respectively. The maximum Pb content accumulated in shoots was 468.0mg/kg d.w. in P. alba ${\times}$ glandulosa, and 602.0mg/kg d.w. in B. schmidtii. Although tolerance to lead was generally higher in B. schmidtii than P. alba ${\times}$ glandulosa, the highest tolerance to lead was observed in P. alba ${\times}$ glandulosa clone, 72-16. Finally, we discussed the applicability of P. alba ${\times}$ glandulosa and B. schmidtii for phytoextraction based on their Pb uptake ability, high biomass production, and easiness in large-scale cultivation.

• Korean Journal of Remote Sensing
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• v.22 no.6
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• pp.543-551
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• 2006

Recently efforts to extract information about forests by using remote sensing techniques for efficient forest management have progressed actively. In terms of extraction of tree information using single remote sensing data, however, the accuracy of tree recognition and the quantity of extracted information is limited. The objective of this study is to carry out tree modeling in domestic environment applying the latest core technique for tree modeling using color aerial photographs and LiDAR data and to estimate the result of tree modeling. A small-scale coniferous forest was investigated in Daejeon. It was 0.77 that the $R^2$ of accuracy test of tree numbers that estimated with color aerial photography and LiDAR data. In terms of tree height, there was no difference between the estimated value and the field measurements in the case of the group accuracy test of the recently unchanged area. Moreover $R^2$ was 0.83 in the case of the individual accuracy test.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.16 no.2
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• pp.87-96
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• 2023

Recently, research on predicting the treatment results of diseases using deep learning technology is also active in the medical community. However, small patient data and specific deep learning algorithms were selected and utilized, and research was conducted to show meaningful results under specific conditions. In this study, in order to generalize the research results, patients were further expanded and subdivided to derive the results of a study predicting mortality after lung cancer diagnosis for men and women in their 80s, 90s, and 100s. Using AutoML, which provides large-scale medical information and various deep learning algorithms from the Health Insurance Review and Assessment Service, five algorithms such as Decision Tree, Random Forest, Gradient Boosting, XGBoost, and Logistic Registration were created to predict mortality rates for 84 months after lung cancer diagnosis. As a result of the study, men in their 80s and 90s had a higher mortality prediction rate than women, and women in their 100s had a higher mortality prediction rate than men. And the factor that has the greatest influence on the mortality rate was analyzed as the treatment period.

• Korean Journal of Environment and Ecology
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• v.37 no.1
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• pp.1-12
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• 2023

We analyzed the distribution area of debris slopes in Mudeungsan (Mt. Mudeung) National Park by comparing aerial photos of the past (1966) and the present (2017) and identified the vegetation characteristics that affect the change in the area of the debris slopes by investigating the vegetation status of the debris slopes and the surrounding areas. The area of debris slopes in Mt. Mudeung appears to have been reduced to a quarter of what it used to be. Debris slopes here have decreased at an average rate of 2.3 ha/yr over 51 years by vegetation covers. Notably, most of the small-area debris slopes in the low-inclination slopes disappeared due to active vegetation coverage. However, there are still west-facing, south-west-facing, south-facing, and large-area debris slopes remaining because the sun's radiant heat rapidly raises the surface temperature of rock blocks and dries moisture, making tree growth unfavorable. Because of these locational characteristics, the small-scale vegetation in the middle of Deoksan Stony Slope, which is the broadest area, showed distinct characteristics from the adjacent forest areas. Sunny places and tree species with excellent drying resistance were observed frequently in Deoksan Stony Slope. However, tree species with high hygropreference that grow well in valleys with good soil conditions also prevailed. In some of these places, the soil layer has been well developed due to the accumulation of fine materials and organic matter between the crevices of the rock blocks, which is likely to have provided favorable conditions for such tree species to settle and grow. At the top of Mt. Mudeung, on the other hand, the forest covered the debris slopes, where Mongolian oaks (Quercus mongolica) and royal azaleas (Rhododendron schlippenbachii), which typically grow in the highlands, prevailed. This area was considered favorable for the development of vegetation for the highlands because the density of rock blocks was lower than in Deoksan Stony Slope, and the soil was exposed. Moreover, ash trees (Fraxinus rhynchophylla) and Korean maple trees (Acer pseudosieboldianum) that commonly appear in the valley areas were dominant here. It is probably due to the increased moisture content in the soil, which resulted from creating a depressive landform with a concave shape that is easy to collect rainwater as rock blocks in some areas fell and piled up in the lower region. In conclusion, the area, density of the rock blocks, and distribution pattern of rock block slopes would have affected the vegetation development and species composition in the debris slope landform.