원형톱에 의한 속성수 절단 소요 동력에 관한 연구

최윤성 ( Yun Sung Choi ),김대현 ( Dae Hyun Kim ),오재헌 ( Jae Heun Oh1 ) 한국임학회 2014 산림과학 공동학술대회 논문집 Vol.2014 No.-

본 연구에서는, 단벌기 바이오매스 생산림(Short rotation forest, SRF)에 식재되어 있는 속성수인 이태리포플러( Populus euramericana)을 이용하여 수확 시 소요되는 동력을 측정하여 수확기계동력원을 선정하기 위한 기초자료를 제공하기 위하여 수행되었다. 실험 수준은 밀기속도(0.41, 1.25,2.5 m/s) 3수준, 절단속도(800, 1,000, 1,200 rpm) 3수준, 직경(50, 70, 90, 110, 130 ㎜) 5수준으로 선정하였다. 실험결과, 밀기속도에 따른 최대토크는 0.41 m/s 일 때 30.4 N-m, 최소동력은 191.37 W로나타났다. 밀기속도 1.25 m/s 일 때 최대토크와 최소동력은 각각 30.1 N-m, 194.88 W, 2.5 m/s 일때 최대토크와 최소동력은 각각 31.9 N-m, 204.10 W로 나타났다. 또한 밀기속도 0.41 m/s 보다 2.5m/s 일 때 최대토크는 각각 4.8, 10, 7.2%, 최소동력은 6.8, 10, 11.8%가 증가하였으며, 밀기속도 0.41m/s 인 경우보다 6.8% 많은 동력을 필요로 하는 것으로 나타났다. 따라서, 실험결과를 바탕으로 측정된 소요 동력 기준으로 수확기계의 동력원을 선정할 수 있을 것으로 판단된다. In this study, Italy poplar( Populus euramericana) was selected for test specimen to measure cutting power when it harvested. Three levels of feed rate (0.41, 1.25, 2.5 m/s), three levels of sawing speed (800, 1,000, 1,200 rpm), and five levels of stem diameter (50, 70, 90, 110, 130 ㎜) were used as test variables. As results, the maximum torque, 30.4 N-m for feed rate 0.41 m/s, the minimum power, 191.37 W. The maximum torque and power, such as 30.1 N-m, 191.37 W for feed rate 1.25 m/s. The maximum torque and power, such as 31.9 N-m, 204.10 W for feed rate 2.5 m/s. Also, feed rate 0.41 m/s than feed rate 1.25 m/s, the maximum torque such as 4.8, 10, 7.2%, minimum power 6.8, 10, 11.8% increased. The feed rate 0.41 m/s than 6.7% many power to required. Using the results of this experiment as the base, The measured power source of the power requirements by the harvesting machine is determined to be able to select.

교목류 뿌리의 비탈면 안정효과 분석 -뿌리의 인장강도를 중심으로-

오재헌 ( Jae Heun Oh ),황진성 ( Jin Sung Hwang ),차두송 ( Du Song Cha ) 한국환경생태학회 2011 한국환경생태학회지 Vol.25 No.1

본 연구는 사면안정해석에 필요한 기초자료를 제공하고자 잣나무, 낙엽송, 소나무, 신갈나무, 오리나무를 대상으로 교목류 뿌리의 인장력 및 인장강도를 측정·분석하였다. 그 결과 인장력은 대부분 뿌리 직경의 거듭제곱의 형태로 증가하는 것으로 나타났다. 또한 뿌리의 평균 인장강도는 잣나무 165.38kgf/㎠, 낙엽송 172.78kgf/㎠, 소나무 176.25kgf/㎠, 오리나무 214.29kgf/㎠, 신갈나무 224.19kgf/㎠로 나타났으며, 뿌리의 직경이 커질수록 인장강도가 감소하는 경향을 나타냈다. 측정·분석된 인장강도를 기초자료로 토양의 전단강도 증가값을 산출한 결과 잣나무 0.099kgf/ ㎠, 낙엽송 0.104kgf/㎠, 소나무 0.106kgf/㎠, 오리나무 0.129kgf/㎠, 신갈나무 0.135kgf/㎠인 것으로 나타났다. To provide the basic information about slope stability analysis, tensile force and strength of tree roots like Pinus koraiensis, Larix leptolepis, Pinus densiflora, Quercus mongolica, and Alnus japonica were measured and analyzed. As a result, tensile force increases in forms of involution of root diameter. The mean tensile strength of roots like P. koraiensis, L. leptolepis, P. densiflora, A. japonica and Q. mongolica were calculated as 165.38kgf/㎠, 172.78kgf/㎠, 176.25kgf/㎠, 214.29kgf/㎠and 224.19kgf/㎠respectively. It was shown that tensile strength decreasing tendency as root diameter increases. Also, recalculated soil shear strength by tensile strength of the roots like P. koraiensis, L. leptolepis, P. densiflora, A. japonica and Q. mongolica were 0.099kgf/ ㎠, 0.104kgf/㎠, 0.106kgf/㎠, 0.129kgf/㎠and 0.135kgf/㎠respectively.

집재견인력 예측을 위한 수학적 모델의 개발과 평가

오재헌 ( Jae Heun Oh ),황진성 ( Jin Sung Hwang ),차두송 ( Du Song Cha ) 한국산림과학회 2007 한국산림과학회지 Vol.96 No.4

수종별 벌채부산물의 압축 변형 특성

오재헌 ( Jae Heun Oh ),최윤성 ( Yun Sung Choi ),김대현 ( Dae Hyun Kim ) 한국산림과학회 2015 한국산림과학회지 Vol.104 No.2

The aim of this study was to provide the basic design parameters for developing logging residue compression machines by investigating compressive deformation characteristics of different types of logging residues. To achieve these objectives, Pinus rigida, Pinus koraensis and Quercus mongolica were selected as specimens, and compression-deformation tests by UTM(universial testing machine) were conducted. The experimental dataset were used to set up the model based on the compression-deformation ratio in the form of exponential function. The results showed that stress coefficient in terms of mechanical properties of logging residues was decreased, whereas strain coefficient tended to be increased as the number of compression increased at target density of 350 kg/m3 and 400 kg/m3. The model presented that the required stress was decreased as the number of compression increased, and the stress growth rate was swelled compared to the change of the deformation rate. Therefore, it showed that proper initial compression force was a significant variable in order to achieve the target density of logging residue.

자주식 반송기를 이용한 가선집재작업의 안정성분석

오재헌 ( Jae Heun Oh ),박문섭 ( Mun Seub Park ),김재원 ( Jae Won Kim ),차두송 ( Du Song Cha ) 한국산림과학회 2006 한국산림과학회지 Vol.95 No.4

벌도 및 가지제거작업에서 세 가지 인간공학적 위험 평가기법의 비교분석

조민재 ( Min-jae Cho ),정응진 ( Eung-jin Jeong ),오재헌 ( Jae-heun Oh ),한상균 ( Sang-kyun Han ) 한국산림과학회(구 한국임학회) 2021 한국산림과학회지 Vol.110 No.2

우리나라 모든 산업에서 근골격계질환은 작업자들의 안전에 큰 영향을 미치고 있으며, 산림작업은 산업안전보건법에 따라 근골격계 부담작업으로 분류된다. 특히 벌도 및 가지제거작업은 주로 인력작업으로 실시되고 있으며, 작업원의 안정성 확보를 위해 작업자세에 대한 평가가 필요하다. 따라서 본 연구는 체인톱을 이용한 벌도 및 가지제거작업의 작업자를 대상으로 세가지 인간공학적 분석 도구(OWAS, RULA, REBA)를 이용하여 위험도를 평가하고, 평가기법별 작업자세에 대한 영향인자를 분석하였다. 벌도와 가지제거작업자세의 위험도는 RULA, OWAS, REBA 순으로 높게 평가되었으며, 대부분 2∼3단계로 작업자세의 즉각 변경조치는 요구되지 않았다. 하지만 벌도작업에서 허리와 다리를 굽힌자세와 가지제거작업에서 벌도목 위에서 작업하는 자세는 위험도가 매우 높게 분석되었다. 또한 벌도작업의 경우 산지경사, 가지제거작업의 경우는 지상에서부터 벌도목 높이가 작업위험도 평가에 영향이 높은 것으로 분석되었다. 따라서 산림작업에 있어서 작업자의 안전성을 확보하기 위해 작업부하가 낮은 자세(벌도작업: 쪼그리는 자세, 가지제거작업: 허리와 다리가 곧은 자세)로 작업하는 것이 바람직한 것으로 사료된다. Musculoskeletal disorders affect workers' safety in most industries, and forest operations are classified as a musculoskeletal burden according to the Occupational Safety and Health Act in South Korea. In particular, felling and delimbing operations are mainly conducted by manpower, and then, it is necessary to evaluate ergonomic risk assessment for safety of felling and delimbing workers. Three ergonomic risk assessment methods, such as Ovako Working posture Analysis System (OWAS), Rapid Upper Limb Assessment (RULA), and Rapid Entire Body Assessment (REBA), are available for assessing exposure to risk factors associated with timber harvesting operations. Here, three ergonomic risk assessment methods were applied to examine ergonomic risk assessments in chainsaw felling and delimbing operations. Additionally, exposure to risk factors in each method was analyzed to propose an optimal working posture in felling and delimbing operations. The risk levels of these operations were evaluated to be highest in the RULA method, followed by the OWAS and REBA methods, and most of the exposed working postures were examined with a low-risk level of two and three without requiring any immediate working posture changes. However, two significant working postures, including the bending posture of the waist and leg in felling operation and standing posture on the fallen trees in delimbing operation, were assessed as the high-risk level and needed immediate working posture changes. Low-risk work levels were examined in the squatting posture for felling operation and the straightened posture of the waist and leg for delimbing operation. Moreover, the slope in felling operation and the tree height in delimbing operation significantly affected risk level assessment of working posture. Therefore, our study supports that felling and delimbing workers must operate with low-risk working postures for safety.

타워야더에 의한 집재작업 생산성 및 비용 분석

조민재 ( Min Jae Cho ),조구현 ( Koo Hyun Cho ),오재헌 ( Jae Heun Oh ),한한섭 ( Han Sup Han ),차두송 ( Du Song Cha ) 한국임학회 2014 산림과학 공동학술대회 논문집 Vol.2014 No.-

본 연구는 강원도 양양군 서면 지역의 소나무, 활엽수 혼효임분을 대상으로 임목집재작업에서 사용된 두 기종의 타워야더(Koller K301-4, Koller K300)의 작업생산성 및 비용을 검토하였다. 이용된 작업방식은 모두 전간집재이고, 집재방향 상향집재로 동일한 작업조건이였다. K301-4를 이용한 작업지의 임지경사는 20°이였고, K300를 이용한 작업지의 임지경사는 15°였다. 집재작업 생산성 분석에서 K301-4의 시간당 생산성(4.7㎥/hr)이 K300의 시간당 생산성(2.3㎥/hr) 보다 높았으며, 집재작업 비용은 K300이 61,316원/㎥이고, K301-4는 29,484원/㎥이였다. 두 기종의 동일한 작업조건(평균가로집재거리 7m, 평균 집재본수 2본, 임목재적 0.417㎥)에서, 집재효율성 비교를 위한 집재거리에 따른 민감도분석 결과는 집재거리 50m를 기준으로, 50m 이상은 타워야더(K301-4)를 이용한 작업이, 50m 미만에서는 타워야더(K300)을 이용한 집재가 더 효율적인 것으로 나타났다. This study was conducted to examine harvesting productivity and cost using two different tower-yarders(Koller K301-4 and Koller K300) in a Pine( Pinus densiflora) and Oak spp. mixed stand of Seo-myeon, Yangyang-gun, Kangwon-do. There were the same operation conditions(tree-length logs and uphill yarding) but slope gradients of the site were 20 °(K301-4) and 15 °(K300), respectively. Harvesting productivity by K301-4(4.7 ㎥/hr) was higher than that of K300(2.3 ㎥/hr). Also, harvesting cost by K300(￦ 61,316/㎥) was more expensive than that of K301-4(￦ 29,484/㎥). Under the same operation conditions(average lateral yarding distance (7 m); average the number of logs (2); average volume (0.417 ㎥/log)), the sensitivity consideredthe yarding distance showed that K301-4 had high harvesting productivity at the yarding distance(longer than 50 m), while K300 was efficient at the yarding distance(less than 50 m).

무인항공기 사진측량 방법에 의한 산림 미세지형 평가

조민재 ( Min-jae Cho ),최윤성 ( Yun-sung Choi ),오재헌 ( Jae-heun Oh ),이은재 ( Eun-jai Lee ) 한국산업융합학회 2021 한국산업융합학회 논문집 Vol.24 No.3

Unmanned aerial vehicles(UAV) photogrammetry provides a cost-effective option for collecting high-resolution 3D point clouds compared with UAV LiDAR and aerial photogrammetry. The main objectives of this study were to (1) validate the accuracy of 3D site model generated, and (2) determine the differences between Digital Elevation Model(DEM) and Digital Surface Model(DSM). In this study, DEM and DSM were shown to have varying degree of accuracy from observed data. The results indicated that the model predictions were considered tend to over- and under-estimated. The range of RMSE of DSM predicted was from 8.2 and 21.3 when compared with the observation. In addition, RMSE values were ranged from 10.2 and 25.8 to compare between DEM predicted and field data. The predict values resulting from the DSM were in agreement with the observed data compared to DEM calculation. In other words, it was determined that the DSM was a better suitable model than DEM. There is potential for enabling automated topography evaluation of the prior-harvest areas by using UAV technology.

임목수확방법별 벌도작업 생산성 및 비용 분석

조민재 ( Min-jae Cho ),최윤성 ( Yun-sung Choi ),문호성 ( Ho-seoung Mun ),이충건 ( Chung-geon Lee ),이은재 ( Eun-jai Lee ),정응진 ( Eung-jin Jung ),오재헌 ( Jae-heun Oh ),한상균 ( Sang-kyun Han ),김대현 ( Dae-hyun Kim ),차두송 ( Du 한국임학회 2016 한국산림과학회지 Vol.105 No.4

본 연구는 동일한 임분조건에서 작업자 2명(A: 작업경력 5년 이하, B: 작업경력 15년 이상)을 대상으로 임목수확방법별(전목수확·전간수확·단목수확)에 따른 벌도작업의 작업생산성과 비용을 분석하였다. 전목작업에서 작업자A의 생산성은 10.3 m³/SMH, 작업비용은 2,066원/m³이며, 작업자 B는 생산성 12.7 m³/SMH, 작업비용 2,201원/m3으로 산출되었으며, 시간당 생산성은 작업자 B가 다소 높았지만, 작업비용은 작업자 B의 높은 임금으로 작업자 A가 약간 낮게 나타났다(p>0.05). 전간작업의 경우 작업자 A와 B의 생산성은 각각 2.2 m³/SMH과 3.3 m3/SMH이며, 작업비용은 각각 9,890원/m³과 8,459원/m³으로, 작업자 B가 A보다 생산성은 높게, 작업비용은 낮게 산출되어 작업의 숙련도에 따라 큰 차이를 보이고 있었다(p< 0.05). 단목작업에서 작업자 A와 B의 생산성은 2.3 m³/SMH과 3.0 m³/SMH, 작업비용은 9,584원/m3, 9,395원/m³으로, 작업자 B의 생산성이 높고, 작업비용은 낮게 산출되었다(p >0.05). 이와 같이 벌도작업 중에서도 임목의 절단작업과 같이 높은 숙련도를 요구하지 않는 단순작업에서는 오히려 작업자의 임금이 생산비용에 크게 영향을 미치는 것으로 나타났다. 또한 가지정리와 같이 임지 내 벌도목 사이를 이동하며, 작업하는 것은 작업자의 높은 숙련도가 작업경비의 저감에 영향을 미치는 것으로 판단된다. The purpose of this study was to broaden our knowledge on the productivity and costs of felling operation in three different harvesting methods(whole tree, tree-length and cut-to-length). Felling was conducted in three different harvesting methods with two workers who have different work experiences. Worker A and B have had felling experiences for about 5 years and 15 years, respectively. Felling productivity in whole tree method was 10.3 m³/SMH for worker A and 12.7 m³/SMH for worker B. Felling costs for worker A and B were 2,066 won/m3 and 2,201won/m³, respectively. Although felling productivity of worker B in whole tree method was higher than worker A, felling costs of worker A were similar to worker B because the wage of worker B was more expensive than the wage of worker A (p>0.05). In tree-length method, felling cost of worker B were cheaper than that of worker A. Felling productivity and cost in tree-length method were 2.2 m³/SMH and 9,890 won/m3 for worker A and 3.3 m³/SMH and 8,459 won/m³ for worker B, respectively (p< 0.05). In cut-to-length method, felling productivity and cost were 2.3 m³/SMH and 9,584 won/m³ for worker A and 3.0 m³/SMH and 9,395 won/m³ for worker B, respectively. Felling productivity of worker B was higher than that of worker A (p >0.05). Our preliminary results found that harvesting methods and worker`s experiences highly affect on the productivity and costs of felling operations. These results should be useful for forest managers when planning cost-effective harvesting operations.

일면전단실험에 의한 수목뿌리의 토양보강효과 평가

차두송 ( Du Song Cha ),오재헌 ( Jae Heun Oh ) 한국산림과학회 2005 한국산림과학회지 Vol.94 No.4