• Journal of Korea Foresty Energy
• /
• v.19 no.2
• /
• pp.69-78
• /
• 2000

This study was conducted to investigate the growth patterns of Maackia amurensis growing in natural forest of Mt. Joongwang, Pyongchang-gun, Kangwon-Do, Korea. The 28 sample plots(30m$\times$30m) wee established to examine the vegetation and environmental conditions for M. amurensis forest. Stem analysis was performed on two sample trees of M. amurensis for each of the 5 plots situated at intervals of one hundred meters by altitude. The results obtained were as follows: ⑴ Height growth of M. amurensis increased with increasing age until 10 years, and then decreased thereafter, especially at altitude of 1,020m. ⑵ M. amurensis showed rapid early growth of height and volume, indicating high biomass production under favorable environment. This growth pattern is typical of pioneer species such as Cornus controversa and Betula costata. ⑶ The rotation age of natural M. amuensis forest was estimated at above 50 years, and especially at about 60 years in 840m above the sea level. ⑷ Growth of M. amurensis increased greatly at about 40 years when released from severe competitions.

• Journal of Korean Society of Forest Science
• /
• v.55 no.1
• /
• pp.30-36
• /
• 1982

Wood biomass production at 1-year, 2-year, and 3-year rotations on both low and upper hills at 2m 2m spacing (25,000 trees/ha) was studied for a six-year period with following 12 species; Lespedeza cyrtobotrya Amorpha fruticosa. Robinia pseudoacacia, Acer saccharinum, Platanus orientalis Populus alba ${\times}$ P. glandulosa $F_1$, Salix alba, Pinus rigida, Alnus hirsuta var. sibirica, A. inokumai A. gultinosa, and A. incana. In One-year rotation, Lespedeza cyrtobotrya produced largest amoung of biomass (2.6 t/ha/year, fresh weight) and Populus alba ${\times}$ P. glandulosa $F_1$ the second largest (2.2 t/ha/year) on low hill. In two-year rotation, the latter produced the largest amount (4.8 t/ha/year) and Alnus hirsuta var. sibirica second largest (2.8 t/ha/year) on low hill. In three-year rotation, the largest weight (11.2 t/ha/year) was produced by Robinia pseudoacacia and the second largest (6.2 t/ha/year) by Alnus hirsuta var. sibirica on low hill Amorpha fruticosa, Acer saccharinum, Platanus orientalis and Salix alba were not suitable for biomass or fuelwood productio due to poor growth. Biomass yield on upper hill was reduced considerably for all tewlve species, with less than 4 t/year at maximum Only nitrogen fixing species (Robinia and Alnus species) are recommended on upper hill for biomass production wood sprouting ability of species was generally associated with good biomass production. Calori values of ovendry wood ranged from 4,485 cal/g for Salix alba to 5,125 cal/g for Alnus glutinosa. For maximum biomass production a three-year ratation with coppice is preferred to one-year and two-year roataions The best species appeared to be Robinia pseudoacacia and Alnus hirsuta var sibirica.

• Korean Journal of Agricultural Science
• /
• v.26 no.1
• /
• pp.12-20
• /
• 1999

The purpose of this study was to research the change of the forest in Myungseo-lee Sanchuk-myun, Chungju where most of the area managed the Swidden Agriculture(Shifting cultivation). The mountainous district should be used and developed the multi-purposing source among the agricultural field, grassland, forest, a recreational area, and an industrial site, and should be presupposed the establishment of synthetic and efficient change system. This study began to pay attention to observe the peculiarity of Swidden Agricultural area in terms of forest aspects and to broaden the outlook of Swidden Agriculture. In the status of Myungseo-lee, prior to the Project to Rehabilitate the Illegal Swidden, from 1973 to 1976, the private forest gets 110.9ha (23ha for Seodae-village, 26ha for Dooduk-village, 6ha for Myungdol-village, 41ha for Chungam-village, 14.9ha for Pangdae-village). In Myungseo-lee. millet and corn were harvested, and they performed the rotation of planting and temporary resting by changing the field. The cultivated acreage per a house of total 5 villages in Myungseo-lee was just 0.4ha in average. The 70ha of the Swidden in Dooduk-village. Myungseo-lee, was sold to the Miwon corp. and the 342ha of that in Myungseo-lee was sold to Seohae-devlp.(SK forest). Those areas afforested. As the regulation plan for the Swidden began, the people in the site got paid for 300,000won as a migration fee. The special feature of the Swidden in Myungseo-lee was that the whole migration village was already established before the regulation plan for the Swidden began, and the yield was harvested by more than other villages the use of chemical fertilizer. And, in the Swidden agriculture, it showed the well-cultivated aspect, and the major harvest was various grains. The regulation Swidden in Myungseo-lee started in 1974.

• Journal of Korean Society of Forest Science
• /
• v.112 no.1
• /
• pp.83-92
• /
• 2023

This study was established to investigate the site environment of mixed forests in Korea and to estimate the growth and yield of stands using national forest resources inventory data. The growth of mixed forests was derived by applying the Chapman-Richards model with diameter at breast height (DBH), height, and cross-sectional area at breast height (BA), and the yield of mixed forests was derived by applying stepwise regression analysis with factors such as cross-sectional area at breast height, site index (SI), age, and standing tree density per ha. Mixed forests were found to be growing in various locations. By climate zone, more than half of them were distributed in the temperate central region. By altitude, about 62% were distributed at 101-400 m. The fitness indexes (FI) for the growth model of mixed forests, which is the independent variable of stand age, were 0.32 for the DBH estimation, 0.22 for the height estimation, and 0.18 for the basal area at breast height estimation, which were somewhat low. However, considering the graph and residual between the estimated and measured values of the estimation equation, the use of this estimation model is not expected to cause any particular problems. The yield prediction model of mixed forests was derived as follows: Stand volume =-162.6859+6.3434 ∙ BA+9.9214 ∙ SI+0.7271 ∙ Age, which is a step- by-step input of basal area at breast height (BA), site index (SI), and age among several growth factors, and the determination coefficient (R²) of the equation was about 96%. Using our optimal growth and yield prediction model, a makeshift stand yield table was created. This table of mixed forests was also used to derive the rotation of the highest production in volume.

• Journal of Korean Society of Forest Science
• /
• v.98 no.3
• /
• pp.225-230
• /
• 2009

Using dynamic programming, which is one of operations research techniques, the best pathway was chosen to maximize the total harvest volume for a Korean white pine (Pinus koraiensis) stand. This study was carried out in an age class III at Chuncheon National Forest, Gangwon province. That stand was assumed to apply 3 different thinning intensities of none, 30% and 50% thinnings. These thinning pathways are planned to implement two times, of thinning at 35 age and 55 age. The final cutting (rotation age) is assumed to carry out in 70 years. A growth function for Korean white pine stand was developed with forest inventory data, the volume was calculated with this growth function. As a result, the best thinning pathway for this Korean white pine stand using dynamic programming is to implement 30% at the first thinning and 50%at the second thinning.

• Journal of Korean Society of Forest Science
• /
• v.110 no.3
• /
• pp.440-452
• /
• 2021

This study identified and evaluated conditions for continued participation of private forest owners in forest carbon offset programs. The probability of continuing forest carbon offset projects, which delays greenhouse gas emissions by extending harvesting periods, increases with increasing price of carbon offset credits, public recognition of forest value, and education level. Willingness to Accept (WTA) was estimated using a Multiple Bounded Dichotomous Choice Question, which was 17,039 KRW/tCO₂ for extending age to 60 years, and 23,070 KRW/tCO₂ for 100 years. The following findings aim to promote participation and supply of carbon offset programs in private forests according to the study outcomes. First, introducing policies supporting private forest owners bearing opportunity costs for avoiding greenhouse gas emissions by postponing timber harvest is needed. Second, educational programs for private forest owners whose awareness of and interests in the public value of forest is necessary. Third, although having participated from the beginning of the offset program, finding ways to lead continuous participation of forest owners who are less likely to accept WTA is also necessary.

• Journal of the Korean Wood Science and Technology
• /
• v.43 no.5
• /
• pp.566-577
• /
• 2015

White Jabon (Anthocephalus cadamba Miq.) is one of the fast growing species in Indonesia and has the potential as the raw material for pulp and paper. In this research, 3, 5, and 7 years old White Jabon woods were pulped under different active alkali charge of 15%, 18%, 21%, 24%, and 27%, and its effect on delignification degree, kappa number, pulp yield, pulp viscosity, brightness, unbeaten freeness, and delignification selectivity was investigated. The results showed that tree age and active alkali concentration influenced the quality of pulp and pulping properties, except for that of unbeaten freeness. Delignification degree increased with increasing active alkali charge, and this brought about the decrease of pulp kappa number. The pulping yield tended to decrease below the Klason lignin of approximately 4%. Even though the 3 years old wood resulted in the highest brightness and highest delignification selectivity, the highest pulp viscosity was obtained with the 5 years old wood. The dominant fiber length of all wood ages was in the range of 1.2 - 2.0 mm. The 3 years old wood was considered to be the most promising raw material for kraft pulping in the view point of pulping properties, pulp quality and harvesting rotation.

• Journal of Korea Multimedia Society
• /
• v.21 no.5
• /
• pp.617-625
• /
• 2018

Phishing website has become a crucial concern in cyber security applications. It is performed by fraudulently deceiving users with the aim of obtaining their sensitive information such as bank account information, credit card, username, and password. The threat has led to huge losses to online retailers, e-business platform, financial institutions, and to name but a few. One way to build anti-phishing detection mechanism is to construct classification algorithm based on machine learning techniques. The objective of this paper is to compare different classifier ensemble approaches, i.e. random forest, rotation forest, gradient boosted machine, and extreme gradient boosting against single classifiers, i.e. decision tree, classification and regression tree, and credal decision tree in the case of website phishing. Area under ROC curve (AUC) is employed as a performance metric, whilst statistical tests are used as baseline indicator of significance evaluation among classifiers. The paper contributes the existing literature on making a benchmark of classifier ensembles for web phishing detection.

• Journal of Multimedia Information System
• /
• v.5 no.2
• /
• pp.99-104
• /
• 2018

Phishing website has become a crucial concern in cyber security applications. It is performed by fraudulently deceiving users with the aim of obtaining their sensitive information such as bank account information, credit card, username, and password. The threat has led to huge losses to online retailers, e-business platform, financial institutions, and to name but a few. One way to build anti-phishing detection mechanism is to construct classification algorithm based on machine learning techniques. The objective of this paper is to compare different classifier ensemble approaches, i.e. random forest, rotation forest, gradient boosted machine, and extreme gradient boosting against single classifiers, i.e. decision tree, classification and regression tree, and credal decision tree in the case of website phishing. Area under ROC curve (AUC) is employed as a performance metric, whilst statistical tests are used as baseline indicator of significance evaluation among classifiers. The paper contributes the existing literature on making a benchmark of classifier ensembles for web phishing detection.

• Journal of Forest and Environmental Science
• /
• v.9 no.1
• /
• pp.81-95
• /
• 1993

The purpose of this study is to analyze the historical development process on management plan and regulation in Japan in order to contribute to the systmatic management plan of national forest in Korea. Before the World War II, remarkable national forest management plan in Japan was introduction of the normal forest ideas by the management plan of the combination system of maximum forest rent and maximum soil rent, employing the clear-cutting of small area, simplified area-period method, and about 70-80 years rotation. After World War II, enterprise management was developed from the previous combination system. During the rapid economic development period, the original working system and normal forest ideas were not recognized, so that the destructions of forest and environment were resulted from the yield of future increment and clear-cutting of large area. During the slow economic development period, on the other hand, the reproduction of forest resources was difficult, as the result of the negligent management system and the depression of management. Future management system of national forest, therefore, should establish the working system and the management plan for the purpose of both forest resources reproduction and environment maintenance, simultaneously.