• Journal of Korean Society of Forest Science
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• v.79 no.2
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• pp.196-204
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• 1990

Pinus densiflora is not only widely distributed but also one of the most economically important timber species in Korea. In Korea, this species is classified into four local forms according to tree forms, as it has widely geographical variations. Trees of Ankang form are dwarfish nearly like shrubs, and those of Keumkang form are very tall and straight. Those of flatland and highland forms are exhibited in-between Ankang and Keumkang forms. This study was carried out to examine biomass, net production and production efficiency among four local forms of Pirzus densiflora forests growing in Korea. For the study, dimension analysis was used for trees and harvest method for shrubs and herbs in four 30-40 year-old stands showing the typical tree forms. Stand biomass of Ankang, flatland, highland and Keumkang forms were 29.87, 110.89, 133.53 and 205.42 t/ha, respectively. As going in order of Ankang, flatland, highland and Keumkang forms, the proportions of stem woods to total tree biomass increased while the proportions of stem barks, live branches, needles and roots showed a tendency to decrease. Stand net productions of Ankang, flatland, highland and Keumkang forms were 3.716, 10.796, 13.097 and 16.500 t/ha yr., respectively. As going in order of Ankang, flatland, highland and Keumkang forms, the proportions of stem woods and lire branches to total tree net production increased while the proportion of needles decreased. In case of live branches, the opposite trend of biomss and net production proportion may be resulted from the differences in the ratio of self-pruning. Net assimilation ratios of Ankang, flatland, highland and Keumkang forms were 1.406, 1.920, 1.487 and 1.677, respectively. Efficiency of needles to produce stems in those forms were 0.239, 0.714, 0.572 and 0.771, respectively. Considering the difference in measuring time, net assimilation ratio and efficiency of needles to produce stems may increase as going in order of Ankang, flatland, highland and Keumkang forms.

• Journal of the Korean Wood Science and Technology
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• v.36 no.6
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• pp.147-158
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• 2008

In this study, fermentation characteristics of waste agricultural and forest biomass for production of heat energy were focused to be used in agricultural farm households. The purpose of this study was focused on seeking practical utilization of agricultural and forest biomass wastes in agricultural farm households in the form of thermal energy by means of simple fermentation process. Fermentation process was performed in terms of different raw-materials and their mixture with different ratios. Urea, lime, and bioaids were added as fermenting aids. Moisture contents of fermenting substrates were adjusted to 55~65%. In order to optimize the fermentation process various factors, such as raw-materials, moisture contents, amount of fermenting aids, and practical measurement of hot-water temperature during fermentation were carefully investigated. The optimum condition of fermenting process were obtained from hardwood only and hardwood: softwood (50 : 50) beds. In case of hardwood only the highest temperature was recorded between 60 to $90^{\circ}C$ the lowest temperature was determined to more or less $40^{\circ}C$ and the average temperature was ranged to $50{\sim}60^{\circ}C$ and this temperature ranges were maintained up to 20~30 days. The optimum amount of additives were estimated to ca. 15 kg of urea, 20 kg of bioaids, and 10 kg of lime for 1 ton of substrate. To reach the highest temperature the optimum moisture content of fermenting substrate was proved to 55% among three moisture content treatments of 45%, 55% and 65%. The temperature of hot-water tank installed in fermenting bed of hardwood : grass (50 : 50) showed very different patterns according to measuring positions. In general, temperatures in the mid- and upper-parts of substrate piling were relative higher than lower and surface parts during 45-day fermentation process. The maximum temperature of fermenting stage was determined to $65^{\circ}C$, minimum temperature, more or less $40^{\circ}C$, and average temperature was $60^{\circ}C$. The water temperature of tank exit was ranged to $33{\sim}48^{\circ}C$ during whole measuring periods. It could be concluded that fermentation process of waste agricultural and forest biomass produces a considerable amounts of heat, averaging about $50{\sim}60^{\circ}C$ for maximum 3 months by using the heat exchanger (HX-helical type).

• The Korean Journal of Pesticide Science
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• v.16 no.4
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• pp.315-321
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• 2012

Fate of acetamiprid and imidacloprid aerially sprayed to control pine wood nematode (Bursaphelenchus xylophilus) were studied in a forest of Haman area. Acetamiprid 20% SL or imidacloprid 20% DC were diluted 100 times and applied two times as rate of 50 L/ha using an aircraft of Bell 206 L helicopter. Average acetamiprid deposits on forest floor ranged from 2 to 4% of standard aerial application rate. Following to the second application, acetamiprid deposits in the pine needle ranged 1.8~8.5 mg/kg and then gradually decreased to 1.2~2.1 mg/kg after 48 days. Deposits on the plant washed off by rainfall and reached to soil surface was ca. 17% of the application rate. All of acetamiprid on the ground resided in the forest floor covering the soil surface, where acetamiprid residues were decreased to a quarter at 48 days after the second application, but they were not detected in soil beneath it. And the only low level of acetamiprid residues, 0.0003 mg/L, was detected in the reservoir nearby the experimental forest on the day of aerial application. The acetamiprid detection was presumably due to spray drift. And average imidacloprid deposits on forest floor ranged from 1 to 3% of standard aerial application rate. Following to the second application, imidacloprid deposits in the pine needle analysed very low concentration of 0.1 mg/kg, but the amount of imidacloprid in wash-off in standard and two-fold treatment were ca. 8% and 4% of the application rate, respectively. Most of imidacloprid on the ground also resided in the forest floor, where imidacloprid residues were decreased to a twentieth at 111 days after the second application, and they were detected below 0.5% of the application rate in sol beneath it. And the low level of imidacloprid, 0.0003~0.0017 mg/L, were detected in the streams in the experimental forest. It was not to the level of contamination concerns.