격자형 압력 센서 배치 구조를 이용한 다층 기반 누운 자세 판별 알고리즘

조민재(Min Jae Cho ),홍윤식(Youn-Sik Hong) 한국산학기술학회 2019 한국산학기술학회논문지 Vol.20 No.6

치매 환자나 혼자 힘으로 전혀 움직이지 못하는 노인 환자는 간병 인력 부족으로 낙상 사고 및 욕창 발생 가능성이 매우 크다. 본 논문에서는 이러한 문제를 해결하기 위해 일정 주기마다 감지한 압력 세기를 기준으로 머리, 어깨, 엉덩이 등 주요 신체 부위를 판별하여 환자의 누운 자세를 판별할 수 있는 알고리즘을 제안한다. 신체적 특성에 무관하게 신체 부위 판별이 가능하도록 격자 구조로 압력 센서를 배치한 스마트 매트를 제작하였다. 스마트 매트는 7x7 배열 크기의 2개 모듈을 조합하여 구성하였다. 각 모듈은 모두 49개의 FSR-406 센서로 구성되며 독립적으로 압력을 감지한다. 각 모듈에 대해 필터를 사용한 누적 압력 합 등 압력 분포를 이용해 상체 또는 하체에 해당하는 신체 부위를 순차적으로 판별한다. 제안한 알고리즘은 머리, 어깨, 엉덩이 부위 등 계층-1에 속한 신체 부위간 포함 관계를 조사해 5가지 누운 자세를 판별할 수 있다. Patients with dementia or elderly patients who can not move at all by themselves are at a high risk of falls and bedsore due to lack of caregivers. In this paper, to solve this problem, we propose an algorithm to determine the patient"s lying postures by discriminating the main body parts such as head, shoulders, and hips based on the pressure intensity sensed at regular intervals. A smart mat with a lattice structure in which a pressure sensor is arranged so that the body part can be discriminated irrespective of the physical characteristics has been implemented. It consists of two modules of 7x7 array size. Each module consists of 49 FSR-406 sensors and independently senses pressure. For each module, the body part corresponding to the upper body or the lower body is sequentially discriminated by using a pressure distribution such as a cumulative pressure sum using a filter. The proposed algorithm can identify five lying positions by examining the inclusion relationship between body parts belonging to layer-1 such as head, shoulder, and hip area.

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).

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.

설문조사에 의한 임업기능인의 적정 임금체계에 관한 연구

조민재 ( Min Jae Cho ),김명환 ( Myung Hwan Kim ),민도홍 ( Do Hong Min ),한원성 ( Won Sung Han ),한한섭 ( Han Sup Han ),차두송 ( Du Song Cha ) 한국임학회 2014 산림과학 공동학술대회 논문집 Vol.2014 No.-

본 연구는 국·사유림 기능인 영림단을 대상으로 임업기능인의 현실적인 적정 임금수준을 제시하고자 실시하였다. 직종구분은 현재 사용되고 있는 3가지(보통인부, 특별인부, 벌목부)로 구분하였다. 설문조사는 총 19문항으로, 총 659명에게 우편을 통하여 실시하였고, 이 중 30.3%의 회신율을 보였다. 조사된 영림단의 평균 임금은 지역별로 다소차이를 보였으나, 보통인부가 97,680원/일, 특별인부 127,559원/일, 벌목부는 152,403원/일로 나타났다. 소속별(산림사업법인, 산림조합, 국유림) 영림단임금의 차이는 작은 것으로 분석되었다. 현재 분류되고 있는 3가지(보통인부, 특별인부, 벌목부) 직종에서, 보다 산림작업의 특수성을 반영할 수 있는 5가지 직종(산림환경작업부, 초급산림작업인, 중급 산림작업인, 고급산림작업인, 산림장비운전사)으로 구분하면, 임업기능인을 위한 현실적으로 안정된 임금체계를 제시 할 수 있을 것이라 사료된다. There has been a concern on the current pay system for forest workers because it does not effectively reflect the characteristics of typical working conditions in the forest. We addressed the fair wages to forest workers by investigating the current workers wage system. The occupation was classified into 3 types(worker, special worker and feller). We mailed the survey questionnaire consisting of 19 questions to 659 forest workers and received 213 responses resulting in a 30.3% response rate. The results showed that the average wages of forest worker, special worker and feller were ￦ 97,680/day, ￦ 127,559/day and ￦ 152,403/day, respectively though there were variations depending on the regions. In addition, there were little difference in terms of the forest workers`` wage among three different workers`` contraction(private, National Forestry Cooperative Federation, government). We 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 wage system for forest workers.

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.

풋 밸브가 적용된 지열 천공 DTH 해머의 성능 특성에 대한 실험적 연구

조민재(Min Jae Cho),심정보(Jung-Bo Sim),김영원(Young Won Kim) 한국지열·수열에너지학회 2021 한국지열에너지학회논문집 Vol.17 No.1

Drilling equipment is an essential part used in various fields such as construction, mining, etc., and it has drawn increasing attention in recent years. The drilling method is generally divided into three types. There are a top hammer method that strikes on the ground, a DTH (Down-The-Hole) method that directly strikes a bit in an underground area, and a rotary method that drills by using rotational force. Among them, the DTH method is most commonly used because it enables efficient drilling compared to other drilling methods. In the conventional DTH hammer, the valve between the piston and the bit is opened and closed using a face to face method. In order to improve the power of the DTH hammer, a DTH hammer with foot valve which is capable of instantaneous opening and closing is used in the drilling field. In this study, we designed a lab-scale DTH hammer with the foot valve, and manufactured an evaluation device for the experiment of the DTH hammer. In addition, we analyzed the performance of the DTH hammer adopted with foot valve according to the pressure range of 3-10 bar. As a result, the internal pressure distribution in the DTH hammer was experimentally analyzed, and then, the movement of the piston according to the pressure was predicted. We believe that this study provides the useful results to explain the performance characteristics of the DTH hammer with the foot valve.

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.

낙엽송 개벌작업에서 타워야더 전목수확시스템의 집재 생산성 및 비용분석

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

본 연구는 강원도지방에서 타워야더(콜러 K301-4)와 최적의 집재시스템을 구축하기 위해 가선집재시스템의 생산성과 비용을 조사하여 분석하였다. 연구 대상지는 중부지방인 강원도 평창에 위치하고 있으며 낙엽송 인공림지역이다. 낙엽송은 한국의 대표 수종 중의 하나이다. 조사지는 강원도평창군 미탄면 평안리 48-라소반의 Ⅵ영급 낙엽송 조림지로 작업면적은 10㏊중 1.1㏊에서 조사하였다. 수고는 평균 16m, 흉고직경은 평균 25㎝, 임목축적은 235.2㎥/㏊이었다. 타워야더를 이용한 개벌작업에서 초커설치·해체 및 측방집재 시간은 총 집재작업 시간의 33 % 소요되었다. 가선작업에서 타워야더의 평균 집재 일일 생산성은 76.56 ㎥/일과 19.14 ㎥/인/일 (9.57㎥/시간)이었다. 집재비용은 138,638원/시간이었다. 고정비용은 41,720원/시간, 변동비용은 45,759원/시간, 노무비용은 51,159원/시간이었다. 타워야더의 총 집재비용은 14,487 원/㎥이었다. This study was conducted to investigate the productivity and cost of cable logging system in order to establish the optimal logging operation system with a tower-yarder (Koller K301-4) in Gangwon-do. The study area is located Pyeongchang-Gun (county), Gangwon-Do (province) in the middle of Korea. The forest is artificial forest of conifer stand. conifer stand is one of the popular species in Korea. The study area was artificial national forest of Pyeongan-Ri, Mitan-Myeon, Pyeongchang-Gun, Gangwon-do. In the area of operation was investigated 1.1㏊of the total 10㏊. Average height of tree was 16m. Diameter at breast height(DBH) was 25㎝. Growing stock was 235.2 ㎥/㏊. In skyline operation by tower-yarder (Koller K301-4), the choker setting·unhooking and lateral yarding time was 33 % of the total yarding time. An average cable logging productivity of a tower-yarder in the skyline thinning operation was 76.56 m3/day and 19.14 m3/person-day(9.57 m3/productive machine hour(PMH)). The total machine cost was 138,638 won/scheduled machine hour(SMH). The fixed cost was 45,759 won/SMH, variable cost was 41,720 won/SMH, and labor cost was 51,159 won/SMH. The total yarding cost of the tower yarder was 14,487 won/m3.

수질오염총량관리에 따른 진주시 남강수계 오염부하량 현황 및 수질개선에 관한 고찰

박현건 ( Hyun Geoun Park ),조민재 ( Min Jae Cho ) 한국물환경학회(구 한국수질보전학회) 2011 공동 추계학술발표회 Vol.2011 No.-

2중 무선 클램프 반송기를 이용한 굴삭기 기반 타워야더의 생산성 및 비용 분석

최윤성 ( Yun-sung Choi ),조민재 ( Min-jae Cho ),문호성 ( Ho-seong Mun ),김대현 ( Dae-hyun Kim ),차두송 ( Du-song Cha ),한상균 ( Sang-kyun Han ),오재헌 ( Jae-heun Oh ) 한국산림과학회(구 한국임학회) 2018 한국산림과학회지 Vol.107 No.3

본 연구에서는 모두베기 작업지에서 2중 무선 클램프 반송기를 적용한 굴삭기 기반 타워야더의 집재작업 생산성 및 비용을 분석하였다. 집재작업의 생산성은 6.2 ㎥/SMH(기계이용률 80.4%)이고, 비용은 13,705 won/㎥으로 나타났다. 이 결과는 기존 연구결과에 비해 최대 집재거리가 길었음에도 불구하고 가선설치용 견인줄(Straw line)을 이용한 가선설치로 집재선 가선설치 시간이 단축되었으며, 2중 무선 클램프 반송기 적용으로 인해 생산성이 향상되고 비용이 절감된 것으로 나타났다. 또한, 원료재급과 임목축적 137 ㎥/ha 기준으로 집재작업의 생산재적에 따른 최소작업량과 최소작업면적은 리기다소나무의 경우 각각 558.3 ㎥ 및 4.1 ha였고 , 신갈나무의 경우 433.7 ㎥ 및 3.2 ha로 나타났다. 향후, 다양한 작업현장에서 집재기계별 최소작업량 및 최소작업면적에 관한 데이터를 구축하면, 집재작업에 효율적인 집재기계를 선정할 수 있을 것으로 판단된다. This study was conducted in clear cutting stands. For the whole-tree yarding operation, a tower-yarder based on excavator with a radio-controlled double clamp carriage was applied to analyze yarding productivity and cost. The productivity and cost of yarding operation was 6.2 ㎥/SMH(machine utilization rate, 80.4%) and 13,705 won/㎥, respectively. Although the maximum yarding distance was longer than the previous studies, the setting up time of the tower-yarder was decreased as used straw line. The application of the radio-controlled double clamp carriage improved productivity and reduced costs. Based on the fuel log and growing stock(137.0 ㎥/ha), the minimum production(㎥) and area(ha) were 558.3 ㎥ and 4.1 ha for Pinus rigida stands and 433.7 ㎥ and 3.2 ha for Quercus mongolica stands, respectively. Based on the this study, it will be possible to select an efficient yarding machine by accumulation of data on minimum production and area for many machines in various harvesting sites.