• Journal of the Korean Wood Science and Technology
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• v.44 no.6
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• pp.821-827
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• 2016

This study evaluates the economic feasibility of industrializing fluidized bed dryer for wood particles. The theoretically required heat energy and energy efficiency were evaluated using a pilot scale fluidized bed dryer. When Mongolian Oak wood particles with 50% initial moisture content were dried in the fluidized bed dryer with air of $70^{\circ}C$ air circulating at 1.1-1.3 m/s for 30 minutes, the total theoretically required heat energy was 2,177 kJ. Of this, 1,763 kJ (approximately 81.0%) was used to heat the air flowing in from outside the dryer and 386 kJ (approximately 17.7%) was used to heat and remove water from the wood particles. Actual energy consumed was 7,560 kJ, giving energy efficiency of 28.8%. Thus, to industrialize a drying method such as fluidized bed drying, where the dryer volume is significantly larger than the volume of wood particles, it is necessary to minimize energy loss and maximize energy efficiency by designing the dryer size considering the amount of wood particles and choosing a suitable air circulation rate.

• Journal of Korean Society of Forest Science
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• v.81 no.2
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• pp.177-182
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• 1992

Soil air $CO_2$ concentrations were measured in two soil depths (O and B horizon) by (1) the use of the Draeger direct reading chromatographic tubes and (2) syringe gas collections with gas chromatographic detection in a Spodosol supporting low elevation, commercial spruce-fir forest, Maine, USA, Mean soil air $CO_2$ concentrations(%) during the growing season of 1991 ranged from 0.11 in the O horizon by the Draeger method to 0.29 in the B horizon by the gas chromatographic method. Soil air $CO_2$ concentrations by the Draeger method were lower than those obtained using the gas chromatographic method for both soil horizons. However, data from the two methods were significantly(p<0.01) correlated and paralleled each other relative to temporal patterns. Positive and highly significant correlations existed between soil air $CO_2$ concentrations and soil temperature, although correlation coefficients only ranged from 0.13 to 0.32, depending on the method and horizon chosen.

• Journal of the Korean Wood Science and Technology
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• v.45 no.4
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• pp.399-408
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• 2017

Research on the rapid and accurate prediction of physical properties of wood using near-infrared (NIR) spectroscopy has attracted recent attention. In this study, partial least squares analysis was performed between NIR spectra and air-dried specific gravity of five domestic conifer species including larch (Larix kaempferi), Korean pine (Pinus koraiensis), red pine (Pinus densiflora), cedar (Cryptomeria japonica), and cypress (Chamaecyparis obtusa). Fifty different lumbers per species were purchased from the five National Forestry Cooperative Federations of Korea. The air-dried specific gravity of 100 knot- and defect-free specimens of each species was determined by NIR spectroscopy in the range of 680-2500 nm. Spectral data preprocessing including standard normal variate, detrend and forward first derivative (gap size = 8, smoothing = 8) were applied to all the NIR spectra of the specimens. Partial least squares analysis including cross-validation (five groups) was performed with the air-dried specific gravity and NIR spectra. When the performance of the regression model was expressed as $R^2$ (coefficient of determination) and root mean square error of calibration (RMSEC), $R^2$ and RMSEC were 0.63 and 0.027 for larch, 0.68 and 0.033 for Korean pine, 0.62 and 0.033 for red pine, 0.76 and 0.022 for cedar, and 0.79 and 0.027 for cypress, respectively. For the calibration model, which contained all species in this study, the $R^2$ was 0.75 and the RMSEC was 0.37.

• Journal of Forest and Environmental Science
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• v.34 no.2
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• pp.153-161
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• 2018

Ozone absorbs ultraviolet light which is harmful to life. However, the recent increase of ambient ozone level due to climate change is becoming the cause of stimulating human eyes, affecting respiratory system, and damaging crops. In this paper, a study was conducted at the Taehwa Research Forest (TRF) of Seoul National University with the purpose of analyzing the characteristics of forest air chemistry based on the measurement of BVOCs emitted from forests and investigating the correlation of BVOCs with ozone generation. The results showed that levels of isoprene and MVK (Methyl Vinyl Keton)+MACR (Methacrolein) were high in summer, but level of monoterpene was high in spring. Ozone level was high from the middle of May to the middle of June, which was before the rainy season. Comparison of the correlation between ozone and isoprene during the measurement period at the TRF showing limited NOx showed that the $R^2$ was correlated with a low value of about 0.4. However, when the isoprene was actively produced from 6:00 AM to 6:00 PM, correlation analysis showed that $R^2$ was about 0.9, while monoterpene started to increase in the afternoon, and decreased level of ozone at night. Correlation analysis showed negative correlation. Forests have two characteristics: not only the formation of ozone but also the decomposition of ozone.

• Korean Journal of Agricultural and Forest Meteorology
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• v.19 no.1
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• pp.19-26
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• 2017

Surface air temperature ($T_{air}$) is a key variable for the meteorology and climatology, and is a fundamental factor of the terrestrial ecosystem functions. Satellite remote sensing from the Moderate Resolution Imaging Spectroradiometer (MODIS) provides an opportunity to monitor the $T_{air}$. However, the several problems such as frequent cloud cover and mountainous region can result in substantial retrieval error and signal loss in MODIS $T_{air}$. In this study, satellite-based $T_{air}$ was estimated under both clear and cloudy sky conditions in Gangwon Province using Aqua MODIS07 temperature profile product (MYD07_L2) and GCOM-W1 Advanced Microwave Scanning Radiometer 2 (AMSR2) brightness temperature ($T_b$) at 37 GHz frequency, and was compared with the measurements from the Automated Mountain Meteorology Stations (AMOS). The application of ambient temperature lapse rate was performed to improve the retrieval accuracy in mountainous region, which showed the improvement of estimation accuracy approximately 4% of RMSE. A simple pixel-wise regression method combining synergetic information from MYD07_L2 $T_{air}$ and AMSR2 $T_b$ was applied to estimate surface $T_{air}$ for all sky conditions. The $T_{air}$ retrievals showed favorable agreement in comparison with AMOS data (r=0.80, RMSE=7.9K), though the underestimation was appeared in winter season. Substantial $T_{air}$ retrievals were estimated 61.4% (n=2,657) for cloudy sky conditions. The results presented in this study indicate that the satellite remote sensing can produce the surface $T_{air}$ at the complex mountainous region for all sky conditions.

• Journal of the Korean Wood Science and Technology
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• v.38 no.1
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• pp.66-74
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• 2010

This study was carried out to investigate the optimum condition for sap exudation of Acer mono Max. tree in a site of Mt. Baekun, Kwangyang city, Korea. Amount of sap exudation, air temperature, relative air humidity and tree diameter at breast height (DBH) were monitored for the period of January 5 through March 28, 2008, and correlation analysis of several factors affecting on sap exudation was carried out. As the diameter of Acer mono at breast height increased, the amount of sap was linearly proportional. Sap exudation initiated at February 18, and occurred intensively in the period of February 28 through March 10, resulting in 84% of total sap amount by volume. During sap exudation, the minimum temperature was averaged at $-2.4{\pm}1.5^{\circ}C$ and the maximum at $6.0{\pm}1.8^{\circ}C$, while there was no sap exudation whenever temperature was below or above $0^{\circ}C$ all the day long. The maximum temperature, range of temperature and the maximum, minimum and mean humidities in air were significant factors affecting on amount of sap. The maximum air temperature had the highest correlation coefficient with 0.768 (P < 0.01) and was also considered as the principal factor by partial-correlation analysis. These results showed that sap exudation required daily air-temperature fluctuation from below to above $0^{\circ}C$, and the amount of sap was strongly dependent on the highest daily-temperature and DBH of tree.

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2011.11a
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• pp.47-47
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• 2011

• Proceedings of The Korean Society of Agricultural and Forest Meteorology Conference
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• 2016.09a
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• pp.15-19
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• 2016

• Journal of the Korean Wood Science and Technology
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• v.42 no.5
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• pp.597-604
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• 2014

Laboratory-scale landfills (simulated landfills) were designed to determine the formaldehyde released into air and leachate from medium density fiberboard (MDF). Simulated landfills were constructed using cylindrical plastic containers containing alternating layers of soil and MDF for a total of five layers. The highest concentration of formaldehyde was found in the air and leachate from the MDF only treatment compared to treatments containing MDF and soil. At the end of the study (28 days), formaldehyde concentrations in air and leachate from treatments containing MDF and soil decreased by 70 percent and 99 percent, respectively, while the treatment containing MDF only still released formaldehyde into the air and leachate. Therefore, waste MDF after storing 4 weeks in water may be recycled as compost or mulch based on formaldehyde leaching. Also, these data indicate soil restricts formaldehyde release into air and leachate and provides new information about the fate of wood-based composite waste containing UF resin disposed in landfills.

• Journal of the Korean Wood Science and Technology
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• v.38 no.4
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• pp.349-358
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• 2010

This study was carried out to investigate the optimum condition for sap exudation of Acer mono Max. tree in a site of Mt. Jiri, Hamyang-gun, Korea. Amount of sap exudation, air temperature, relative air humidity, tree diameter at breast height (DBH) and sugar content in sap were monitored during the early springtime, and correlation analysis of several factors was carried out to explain tree-to-tree and date-to-date variations in sap exudation. The correlation, linearlyassociated between DBH and sap amount, was strengthened as daily amount of sap increased, but there was no significant tree-to-tree variation in time and period for sap exudation. When amount of sap exudation was above 10 liter/day, the mean air-temperature was averaged at $1.2{\pm}1.6^{\circ}C$, the minimum at $-4.3{\pm}1.5^{\circ}C$ and the maximum at $11.8{\pm}1.9^{\circ}C$. The maximum air temperature and mean air temperature were significant (p < 0.05) factors for amount of sap in correlation analysis to explain date-to-date variation in sap exudation. Sucrose content in sap was in the range of 1.5 and 1.7% during exudation days, but sharply reduced to 0.6% level at the end of exudation period.