• 한국산림과학회지
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• 제83권2호
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• pp.121-132
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• 1994

윤벌기(輪伐期)는 각 영급이 존재하는 삼림의 생산(生産)을 조절하기 위해서 설정된 삼림경영목표(森林經營目標)중 가장 중요한 인자중의 하나이다. 본 연구(硏究)에서는 특히 최적화(最適化)계산의 형태로 법정임(法正林)모델에서의 최적윤벌기(最適輪伐期)가 추정(推定)되었다. 그리고 법정림모델과의 연계하에 자연상태에서 여러가지 위험조건에 처해있는 현실임분(現實林分)에 더욱 접근시키기 위하여 목표임(目標林)모델이 간단작업급삼림(間斷作業級森林)모델(모델 1)과 연년보속작업급삼림(連年保續作業級森林)모델(모델 2)의 두가지로 나뉘어 전개되었으며 이 두 모델에 의해 최적윤벌기가 계산되었다. 동시에 법정림모델, 목표림모델 1, 2에 의해 추정된 최적윤벌기가 상호 비교되었다. 이때 강원대학교(江原大學校) 임과대학(林科大學) 부속(附屬) 연습림(演習林) 내(內) 잣나무임분이 최적윤벌기(最適輪伐期) 계산의 대상이 되었다.

• Journal of Forest and Environmental Science
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• 제24권3호
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• pp.143-149
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• 2008

We conduct economic analysis of the snow damage on sugi (Cryptomeria japonica) forest stands in Toyama Prefecture, Japan. We utilize a single tree and distant independent growth simulator called "Silv-Forest." With this growth simulator, we developed an optimization model by dynamic programming, called DP-Silv (Dynamic Programming Silv-Forest). The MS-PATH (multiple stage projection alternative technique) algorithm was embedded as a searching algorithm of dynamic programming. The height / DBH ratio was used to constrain the thinning regime for snow damage protection. The optimal rotation age turned out to be 65 years for the non-restricted case, while it was 50 years for the restricted case. The difference in NPV of these two cases as the induced costs ranged from 179,867 to 1,910,713yen/ha over the rotation age of 20 to 75 years. Under the optimal rotation of 65 years, the cost became 914,226 yen/ha. The estimated annual payment based on the difference in NPV, was from 9,869 yen/ha/yr to 85,900 yen/ha/yr. All in all, 10,000 yen/ha/yr to 20,000 yen/ha/yr seems to cover the payment from the rotation age of 35 to 75 years.

• 한국산림과학회지
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• 제77권1호
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• pp.109-115
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• 1988

Decrease of the planting area reduced fertilized area of forest. To accomplish the aims of natural regeneration, mini-rotation plantation, diminishing the rotation length, maintaining healthy forest and production of good quality timber, forest fertilization should be continued. In order to improve the deteriorate situation, slow-release fertilizer applied on top soil needs to be developed and aerial application will give diminished cost. Fertilization with tending before tree felling in forest will increase the effect of fertilizer more, Proper quantity of fertilizer by tree species and soil fertility should be found out in the future, Street trees, environmental forest near city and ornamental trees in the residential areas could be also included in this field.

• 한국산림과학회지
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• 제90권3호
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• pp.346-354
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• 2001

본 연구는 우리나라 수렵제도의 문제점을 고찰하여 제도의 합리적인 개선방안을 모색하기 위해서 실시되었다. 현재 우리나라에서 시행하고 있는 도별 순환수렵제도는 예산 내부화의 어려움, 엽사들의 낮은 참여율, 담당공무원들의 낮은 전문화, 관리의 부재로 인한 밀렵의 만연과 같은 문제점들을 내포하고 있다. 또한 무엇보다도 수렵제도의 효과적인 수행을 위해 필요한 인력과 조직을 강화하기 위한 전문인력의 생산과 재원확보가 필수적이며, 장기적으로는 야생동물의 보호를 위한 경찰인력의 확보가 필요할 것으로 판단된다. 현행 도별 순환수렵제도를 개선 보완하는 측면에서 엽사들의 편의제공을 통한 참여율의 증대, 지방경제 소득효과, 고용창출효과, 밀렵방지효과 등을 가대할 수 있는 시 군별 수렵제도로의 전환을 고려해 보는 것이 필요할 것으로 판단된다.

• 한국기후변화학회지
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• 제8권4호
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• pp.369-375
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• 2017

In this study, it was intended to compare the two methodologies for forest management project through extension of rotation age: Korean Forest Carbon Offset Standard (KFOS) and Verified Carbon Standard (VCS). The amount of carbon removals and offset credits based on the two methodologies and their trends were analyzed in this study. The major difference between two methodologies were found at the process of estimation of baseline carbon removals. For instance, average carbon stock during the project period was used for estimation of baseline carbon removals in KFOS, while average carbon stock change during the 100 years was used in VCS. Due to the different approach for estimation of baseline carbon removal, the estimated offset credits were also different according to the two methodologies. In this study, 15 project scenarios were considered for comparison of two methodologies : 5 major coniferous stands in Korea (Pinus densiflora in Gangwon region, Pinus densiflora in Central region, Pinus koraiensis, Larix leptolepis, Chamaecyparis obtusa) with 3 project periods (30, 35, 40 years). The results showed that estimated carbon offset credits based on the KFOS methodology were higher for all 15 scenarios compared to those based on the VCS methodology. The KFOS showed a steep decline in the annual offset credit as project period gets longer, thus it is not desirable for projects with longer period. VCS is more acceptable for longer projects with a small difference according to the project periods. The results also indicated that Pinus densiflora in Gangwon, Pinus koraiensis, and Larix leptolepis are more desirable species for forest management project through the extension of ration age.

• Journal of Computational Design and Engineering
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• 제3권4호
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• pp.337-348
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• 2016

An experimental approach is presented for the measurement of wear that is common in the threading of cold-forged steel. In this work, the first objective is to measure wear on various types of roll taps manufactured to tapping holes in microalloyed HR45 steel. Different geometries and levels of wear are tested and measured. Taking their geometry as the critical factor, the types of forming tap with the least wear and the best performance are identified. Abrasive wear was observed on the forming lobes. A higher number of lobes in the chamber zone and around the nominal diameter meant a more uniform load distribution and a more gradual forming process. A second objective is to identify the most accurate data-mining technique for the prediction of form-tap wear. Different data-mining techniques are tested to select the most accurate one: from standard versions such as Multilayer Perceptrons, Support Vector Machines and Regression Trees to the most recent ones such as Rotation Forest ensembles and Iterated Bagging ensembles. The best results were obtained with ensembles of Rotation Forest with unpruned Regression Trees as base regressors that reduced the RMS error of the best-tested baseline technique for the lower length output by 33%, and Additive Regression with unpruned M5P as base regressors that reduced the RMS errors of the linear fit for the upper and total lengths by 25% and 39%, respectively. However, the lower length was statistically more difficult to model in Additive Regression than in Rotation Forest. Rotation Forest with unpruned Regression Trees as base regressors therefore appeared to be the most suitable regressor for the modeling of this industrial problem.

• 한국자원식물학회:학술대회논문집
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• 한국자원식물학회 2018년도 추계학술대회
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• pp.24-24
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• 2018

Degraded plantation forests are increasing because of unfavorable forestry conditions prevailing in Japan, including falling timber prices, increasing operational costs, and aging and declining forestry workforce. To remedy this situation, appropriate management strategy is required. This study introduces the challenges of Odai Town, Mie Prefecture that employed a new management strategy by evaluating site suitability for conifer forests and that proposes a new forest management regime of planting deciduous trees in unsuitable sites. The site suitability for conifer forests was evaluated from two aspects: the natural site conditions and the relationship among site conditions, growth, and damage by Anaglyptus subfasciatus Pic. in Cryptomeria japonica D. Don and Chamaecyparis obtusa Sieb. Et Zucc. forests. By analyzing the relationship among site conditions, growth, and insect damage based on field data obtained in plantation forests, growth evaluation and insect damage evaluation maps were developed. Based on the natural forest investigation, natural site condition maps for C. japonica and C. obtusa were established. Furthermore, by integrating these evaluation maps with the forest road maps showing the accessibility to the forest, the forest management regime for the whole plantation area of Odai Town was established. The forest management regime map indicates the sites suitable for forestry: suitable for long-rotation, short-rotation, and potential sites for short-rotation. The sites unsuitable for forestry were considered to be more suitable for broadleaved forests. Clear-cutting was conducted in a small area and different seral stage saplings (approximately 20 deciduous tree species) suitable to the site conditions were planted in an area of $80-120m^2$ protected by deer-fences. This might establish a forest composed of many species with a multilayer vertical forest structure in a short period. The planted saplings were distributed neither randomly nor uniformly to reflect the natural distribution of trees in the forest. A challenge to develop new products using the deciduous trees has started, such as wood chips for preparing smoked food, essential oil, and deodorizer. As these challenges have just begun, their effects on enhancing sustainable resource management are still being monitored. Even with the challenges, this regime can be of high value as a management strategy to remedy the situation of expansion of degraded forests in Japan.

• 한국산림과학회지
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• 제98권5호
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• pp.513-523
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• 2009

Many species, cultivars, and hybrids in Populus have been introduced and developed by the scientists of Department of Forest Genetic Resources, Korea Forest Research Institute in Korea. P. alba ${\times}$ glandulosa, P. euramericana, P. nigra ${\times}$ maximowiczii, P. koreana ${\times}$ P. nigra var. italica, and P. davidiana have been studied from many aspects, i.e., genetics, breeding, physiology, propagation, silviculture, biomass production, biotechnology and phytoremediation. These precedent results will provide a sound basis for a newly-arising research on short-rotation coppice as one of renewable resources and phytoremediation plants. It was found that there were many promising varieties and clones for these purposes. However, minute analysis on specific gravity and caloric values for those plants should be followed under several silvicultural and rotational systems.

• 한국임산에너지학회:학술대회논문집
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• 한국산림바이오에너지학회 2011년도 정기총회 및 학술연구발표회
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• pp.68-68
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• 2011

• Journal of the Korean Wood Science and Technology
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• 제47권3호
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• pp.360-370
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• 2019

Woody crops cultivated in short-rotation coppices are attractive sources of lignocellulosic materials for bioethanol production, since they are some of the most abundant renewable resources. In this study, we evaluated the effects of the growth period on bioethanol production using short-rotation woody crops (Populus nigra ${\times}$ Populus maxiwiczii, Populus euramericana, Populus alba ${\times}$ Populus glandulosa, and Salix alba). The carbohydrate contents of 3-year-old and 12-year-old short-rotation woody crop branches were 62.1-68.5% and 64.0-67.1%, respectively. The chemical compositions of 3-year-old and 12-year-old short-rotation woody crop branches did not vary significantly depending upon the growth period. However, the 3-year-old short-rotation woody crop branches (glucose conversion: 26-40%) were hydrolyzed more easily than their 12-year-old counterparts (glucose conversion: 19-24%). Furthermore, following the fermentation of enzymatic hydrolysates from the crop branch samples (by Saccharomyces cerevisiae KCTC 7296) to ethanol, the ethanol concentration of short rotation coppice woody crops was found to be higher in the 3-year-old branch samples (~ 0.18 g/g dry matter) than in the 12-year-old branch samples (~ 0.14 g/g dry matter). These results suggest that immature wood (3-year-old branches) from short-rotation woody crops could be a promising feedstock for bioethanol production.