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한상균,한한섭 한국산림과학회 2020 Forest Science And Technology Vol.16 No.1
Cable yarding systems are often used to reduce hazardous fuels in dense overstocked forest stands on steep terrain (>35%) in the western United States. However, treatment costs tend to be high. The aim of this study was to broaden our knowledge by evaluating two different harvesting methods (whole-tree (WT) and tree-length (TL)) used for fuel reduction thinning treatment on mixed-conifer forest stand. Different harvesting methods greatly affected the productivity and cost of fuel reduction thinning, especially in felling and yarding operations. Total sawlog removal costs (stump-to-truck) were US$26.13/m3 in the WT-harvested unit and US$24.01/m3 in TL harvested unit. TL thinning resulted in higher felling time and lower production rate due to increased amounts of time for processing trees at the stump. In yarding operation, however, TL method had a higher production rate than WT method because TL method had higher number of pieces per yarding cycle. Processing production rates at a landing were relatively similar throughout treatments although trees in a TL thinning unit were already limbed and bucked at the stump. Loading productivity was consistent throughout treatments because loading occurred independently from other activities. For fuel reduction thinning treatments using a cable yarding system, TL thinning was more cost-effective than WT thinning if leaving tree tops and branches on site is acceptable from a fuels management perspective.
서영완,한한섭,Edward M. (Ted) Bilek,최정기,차두송,이정수 한국산림과학회 2017 Forest Science And Technology Vol.13 No.3
Economic analysis was conducted on the feasibility of operating a small-sized (500kW/hour) gasification power plant producing heat and electricity in a rural town surrounded by forests in the Republic of Korea. Cost factors that were considered over the plant’s 20-year life included wood procurement, a wood grab loader, a chipper, a chip dryer, a gasifier, a generator, land and building, wages, and office management. All the cost factors were calculated based on the 2016 market values for logs, information from machine manufacturers, and a literature review. Revenues were estimated from selling heat and electricity using the 2016 average prices that were sourced from Korea District Heating Corporation and Korea Power Exchange, respectively. Using a spreadsheet program, cash flows for costs and revenues were arranged to calculate net present value, internal rate of return, and payback period of the plant. Also, sensitivity analyses were performed on the cost of wood procurement and revenues from selling heat and electricity, which were the most significant factors affecting the economic feasibility. The results, as reinforced by the sensitivity analysis, suggest an investment in the small-sized gasification power plant may be attractive from a financial standpoint, especially if the owners are in a position to get additional revenue from heat sales and to take advantage of Renewable Energy Credits.
◇ 3분과 : 임업기능인 임금조사를 통한 직종별 기준임금 산정에 관한 연구
한상균 ( Sang Kyun Han ),한한섭 ( Han Sup Han ),우희성 ( Hee Sung Woo ),최병구 ( Byoung Koo Choi ),조민재 ( Min Jae Cho ),차두송 ( Du Song Cha ) 한국임학회 2015 한국산림과학회지 Vol.104 No.4
산림작업은 험준한 산악지에서 주로 작업이 이루어지고 있기 때문에 임업노동자에게 높은 위험수준을 부담하는 노동형태를 띠고 있다. 하지만 이러한 중노동에도 불구하고 건설공사 품셈을 바탕으로 하는 비현실적인 임금체계의 적용으로 인하여 효율적인 작업수행이 이루어지지 않을 뿐만 아니라 임업기능인의 노동생산성도 점차 저하되고 있는 실정이다. 따라서 본 연구에서는 국·사유림 임업기능인 영림단을 대상으로 현행 임금체계의 문제점과 합리적인 임금체계 수립을 위한 설문지 조사를 실시하였다. 또한 설문내용을 바탕으로 임업의 특수성을 고려한 새로운 직종별 적정 임금체계를 개발하였다. 설문조사는 총 19문항으로, 총 659명에게 우편을 통하여 실시하였고, 이 중28.5%의 회신율을 보였다. 조사된 영림단의 평균 적정임금은 지역별로 다소차이를 보였으나, 보통인부가 97,680원/일, 특별인부 127,559원/일, 벌목부는 152,403원/일로 나타났다. 이는 건설협회의 노임단가와 비교했을 때, 적정한 수준이라 판단된다. 또한 현재 분류되고 있는 3개 직종(보통인부, 특별인부, 벌목부)구분 보다는 좀 더 산림작업의 특수성을 반영할 수 있는 5개 직종(산림환경작업부, 초급산림작업인, 중급산림작업인, 고급산림작업인, 산림장비운전사)으로 구분한다면 임업기능인을 위한 현실적이고 안정된 임금체계를 제시 할 수 있을 것으로 사료된다. Working in the forest would require a wide range of skills and experience for specific tasks which involve with a high level of risks to worker’s safety. However, there has been a concern on the current standard wage system for forest workers because it does not effectively reflect the characteristics of typical working conditions in the forest. In addition, the current standard wages for forestry workers was estimated based on the construction industry``s wage system. Therefore, the purpose of this study is to assess a current wage system through the mail survey method and to develop a new wage system for forest worker which effectively reflects skill sets and experience required for successful completion of the work in the forest. We mailed the survey questionnaire consisting of 19 questions to 659 forest workers and received 188 responses resulting in a 28.5% response rate. The results showed that the current average optimal wages of forest worker, special worker and feller were 97,680won/day, 127,559won/day and 152,403won/day, respectively though there were variations depending on the regions. In developing the new standard wage system, this study suggest the current work types(worker, special worker and feller) could be divided into 5 work types (forest-environment workers, forest operations in beginner, forest operations in intermediate, forest operations in advanced and forest equipment operator) reflecting specialty of forest operation thereby stabilizing the new wage system for forest workers.
Yoader를 이용한 간벌작업 시 작업비용 및 생산성 분석
한상균 ( Sang Kyun Han ),한한섭 ( Han Sup Han ) 한국임학회 2014 산림과학 공동학술대회 논문집 Vol.2014 No.-
Unmanaged second-growth forests in Redwood National Park have resulted in high tree density consisting of non-redwood species. These stands generally require forest restoration treatments to alter tree density and to promote redwood dominance. In this study, a yoader yarding system was implemented on steep ground. Restoration treatment costs of the yoader operations were investigated under two different thinning prescriptions, 25% and 40% basal area reductions. Treatment costs were estimated by detailed time studies. A stand damage survey was also conducted to assess the amount of damage to residual trees during thinning operations. The amount of volume removed had a significant effect on operational costs, regardless of operational methods. Yoader thinning costs increased directly with the amount of volume removed ($6,313/ha at 25% thinning unit and $25,664/ha at 40% thinning unit). The cost difference was due to large amounts of small trees removed and lack of operator experience at the beginning of the thinning operation. When comparing all incurred costs and total revenues estimated in this study, total revenue in the 40% thinning unit was not enough to offset additional costs incurred by recovering biomass for energy production. Yarding was the most expensive component in the thinning operation and the sensitivity analysis showed that high yarding productivity is critical in minimizing overall treatment costs. Thinning intensities significantly affected residual stand damage: the 40% thinning unit had more severe residual stand damage than the 25% thinning unit.