풍력발전기용 3점 지지 드라이브 트레인의 지지 강성이 기어박스 입력하중에 미치는 영향

남주석(Ju Seok Nam),남용윤(Yong Yun Nam) 한국생산제조학회 2015 한국생산제조학회지 Vol.24 No.5

The effects of suspension stiffness on the reaction load of the gearbox suspension for a three-point suspension wind turbine drive train were investigated by finite element analysis. The reaction forces of the gearbox suspension appear to increase as the gearbox suspension stiffness increases; however, the main bearing stiffness has a reverse effect on the reaction forces. The influence of the gearbox suspension stiffness is greater than that of the main bearing. Since the suspensions must provide the gearbox with proper support, it is not practical to use soft gearbox suspension for small reaction forces. It is more feasible to use stiff main bearings. As a guideline for the main bearing stiffness in the present study, we propose a relative stiffness of 100-150% of the reference.

Consumed-Power and Load Characteristics of Potato Harvesting Operation in Dry Field

Ju-Yeon Lee(이주연),Seok-Joon Hwang(황석준),Ju-Seok Nam(남주석),Jeong-Gil Kim(김정길) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.1

This study analyzed the load and the consumed power characteristics of a potato harvesting operation in a dry field. The potato harvesting operation was performed using an underground crop harvester mounted on an agricultural tractor with a rated engine power of 23.7 kW. The rotational speeds and the torque of the engine output shaft, rear axle, and power take-off (PTO) shaft were measured under various working conditions. The load spectrum and the consumed power were analyzed using the measured data. The results show that the consumed power of the rear axle increased as the working speed increased, while that of the PTO shaft decreased. The consumed power of the engine output shaft showed a similar trend with that of the PTO shaft, but the torque deviation was larger in the load spectrum. The results of previous studies were used to compare herein the consumed power and the load characteristics of the harvesting, rotary, and plow operations in a dry field. PTO and tractive power were highly consumed in the plow and rotary operations, respectively. The consumed power of the PTO shaft and the rear axle in the harvesting operation were 29–41% and 18–23% of the engine power, respectively. Compared to those in the rotary and plow operations, the engine power was relatively evenly distributed to the PTO shaft and rear axle in the harvesting operation.

Spray Pattern Analysis for a Centrifugal Fertilizer Distributor with Two Shutter Holes

Seok-Joon Hwang(황석준),Jeong-Hyeon Park(박정현),Ju-Yeon Lee(이주연),Ki-Duck Kim(김기덕),Beom-Soo Shin(신범수),Ju-Seok Nam(남주석) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.10

In this study, the spray pattern of a centrifugal fertilizer distributor with two shutter holes was analyzed and an effective driving width that satisfies proper spray uniformity was derived. The centrifugal fertilizer distributor was mounted on a tractor with a rated power of 23.7 kW and static and dynamic spray pattern tests were performed according to the standard procedure proposed by the American Society of Agricultural and Biological Engineers Standard ASAE S341.5. The height of the fertilizer distributor was 80 cm from the ground and the PTO (power take-off) shaft speed of the tractor was fixed at 540 rpm. The fertilizer scattered in space was collected using 275 evenly spaced collectors at shutter opening ratios of 25%, 50%, 75%, and 100%. The spray pattern was analyzed via the amount of sprayed fertilizer at each collector location and the coefficient of variation was used as an indicator of spray uniformity. Using the analyzed spray pattern, the effective driving width that satisfied less than 15% of the coefficient of variation was derived for different tractor driving patterns (race track mode, back and forth mode). From the results, spray uniformity increased as the shutter opening ratio decreased. The largest effective driving width was 8 m at a shutter opening ratio of 25% for both driving patterns.

제1발표장 : 노외기계시스템 분야; 비토크 하중 가력이 가능한 기어박스 시험장비 개발

남주석 ( Ju Seok Nam ),박영준 ( Young Jun Park ),이근호 ( Geun Ho Lee ),남용윤 ( Yong Yun Nam ),김흥섭 ( Heung Sub Kim ) 한국농업기계학회 2014 한국농업기계학회 학술발표논문집 Vol.19 No.1

메인 베어링 강성이 풍력발전기용 3점 지지 드라이브 트레인의 기어박스에 미치는 영향

남주석(Ju Seok Nam),남용윤(Yong Yun Nam) 한국생산제조학회 2015 한국생산제조학회지 Vol.24 No.3

The effects of the main bearing stiffness combined with vertical non-torque force on the input load and shaft deflection of a gearbox were investigated for the three-point suspension drive train of a wind turbine. A finite element analysis model for the drive train was studied experimentally, and its applicability to the present study was verified. The results show that, as the main bearing stiffness is increased, the input load of the gearbox decreases, whereas the input shaft deflection increases. The stiffness component for the pitch moment has the largest influence on the gearbox input load. Although the gearbox life increases at a higher main bearing stiffness, the economic efficiency and durability of the entire drive train system should also be considered in the selection of the main bearing stiffness.

Load and Safety Analysis for Plow Operation in Dry Fields

Ju-Yeon Lee(이주연),Ju-Seok Nam(남주석) 한국기계가공학회 2019 한국기계가공학회지 Vol.18 No.6

This study derives load characteristics and analyzes the safety of plowshares operating in dry fields. We mounted a three-blade, reversible plow on a 23.7 kW tractor and measured the plow’s tractive force as well as the torque from the engine output shaft on the rear axle under various working speeds (L4, M1, M2, M3). We chose a Korean test site of Seomyeon, Chuncheon with sandy soil texture, as determined using the USDA method. We constructed the load spectrum for torque and tractive force using measured data and derived the fatigue life of the plowshare from a stress-cycle (S-N) curve of the plow material. Our results show that the M3 gear maximizes the driving shaft torque loads and, applying the tractive force load spectrum, creates a cumulative damage sum of 4.14x10-5. Considering sampling time, we estimate a fatigue life of 805 hours while using the M3 gear. When using the other working speeds, however, all of the stress levels fell within the endurance limits and, therefore, our model predicts infinite plowshare lifetimes. For this analysis, we used a yield strength of 1,079 MPa for the plowshare and static safety factors, analyzed using the maximum stress, between 6.83 and 8.63 under each working speed.

인도네시아 중부 자바 지역의 토양 특성 조사

남주석 ( Ju-seok Nam ),정종훈 ( Jong-hoon Chung ),남상일 ( Sang-il Nam ),정회식 ( Hoi-shik Jeong ) 한국농업기계학회 2018 한국농업기계학회 학술발표논문집 Vol.23 No.2

인도네시아는 세계 4위의 인구수(약 2억 6천만명) 및 대한민국의 약 19배(약 190,000 km2)에 달하는 면적을 가진 국가이다. 2017년 기준 인도네시아의 농업은 전체 GDP의 약 13%를 차지하고 있으며 농촌 인구는 전체인구의 약 45%를 차지한다. 또한 전체 노동인구의 약 31%가 농업에 종사하고 있다. 2016년 기준 농업의 부가가치는 약 1,250억 달러이다. 주요 작물은 주로 이모작으로 1년 내내 생산이 가능한 쌀이며(전체의 50% 이상) 주요 수출 작물은 팜유, 고무, 카카오, 커피, 차, 카사바 등이다. 전체 산업에서 농업이 차지하는 비중이 크며 작물 중에서는 벼농사의 비중이 가장 높다. 그러나 벼농사의 기계화율은 2014년 기준 파종작업 10%, 제초 및 이식작업 20%, 건조 및 수확작업 50%, 경운 및 탈곡작업 80% 수준으로 저조한 실정이다. 현재 빠르게 산업화가 진행되고 있는 실정을 고려하면 농촌에서 도시로의 급격한 인구유출, 농촌 노동력 부족으로 인한 인건비 상승이 예상되며 이로 인해 벼농사 기계화는 향후 인도네시아에서 매우 중요한 이슈가 될 것으로 판단된다. 우리나라의 농기계 산업은 내수시장의 포화로 인해 수출확대가 절실하며, 그를 위해서는 시장의 다변화가 필요하다. 인도네시아는 벼농사 위주로 영농규모 및 영농방법이 우리나라와 유사하여 수출잠재력이 높지만 2012년 기준 국산 농기계의 인도네시아 수출액은 동남아 수출 총액(5,540만 달러)의 약 7.2%로 미미한 실정이다. 수출확대를 위해서는 현지의 실정에 적합한 농업기계를 제공해야 하며, 그를 위해서는 가장 먼저 현지의 토양 특성에 대한 조사가 선행되어야 한다. 따라서 본 연구에서는 인도네시아 중부 자바 지역의 토양 특성을 조사하였다. 토양 형성시기 및 관개시기가 다른 4곳의 토양을 대상으로 하여 토양의 종류를 파악하고 토양 강도를 계측하였다.

잠재프로파일(LPA)분석을 활용한 노인의 생활시간 유형의 영향요인과 유형에 따른 생활만족도

남석인(Seok In Nam),채주석(Joosuk Chae),원해솔(Hae Sol Won),이주영(Ju Young Lee) 한국노년학회 2020 한국노년학 Vol.40 No.4

본 연구의 목적은 한국 노인의 생활시간 사용을 유형화하여 유형별 영향요인과 차이를확인하고 각 유형이 생활만족도에미치는 영향을 파악하는 것이다. 이를위해 국민노후보장패널 6차 자료를활용하 여 65세 이상 노인 3,963명을 대상으로 잠재프로파일분석을 실시하였다. 생활시간 유형 분류 결과 한국 노인의 생활시간 활용은 기초생활유지형(16%), 여가자유중심형(26%), 사회활동형(58%)의 3가지로 유형화 되었다. 각 유형별 영향요인 파악을 위한 다항 로지스틱 회귀분석 결과 기초생활유지형 대비 여가자유중심형의주요 영향요인은 배우자의 유무(p<.01), 심리적 건강상태(p<.001)로 나타났고, 사회활동형의 주요 영향요인은 연령(p<.05), 경제적 활동(p<.001), 만성질환(p<.001)으로 나타났다. 생활만족도에 영향을 미치는 요인을 종합적으로 분석한 결과, 기초생활유지형에 비해 여가자유중심형과 사회활동형의 생활만족도가 더 높게 나타났다. 연구결과를바탕으로 기초생활유지형으로 시간을 활용하고 있는 노인의시간사용 유형 변화를추구하여 노년기 생활만족도를제고하기 위한 실천적 정책적 제언을 제시하였다. This study aims to categorize the daily time use of older adults into different types, examine the factors influencing them and the differences between them by type, and verify the effect of each type on life satisfaction. From the 6th wave of the Korea Retirement and Income Study (KeRIS), analysis was conducted on 3,963 older adults aged 65 (n=3,963). Using Latent Profile Analysis (LPA), three types of daily time use for older adults were identified: basic life maintenance type (16%), free-leisure oriented type (26%), and social activity type (58%). From the results of multinomial logistic regression analysis to identify the factors influencing each type of daily time use, it was found that the main factors influencing free-leisure oriented type, when compared with basic life maintenance type, were the presence of spouse (p<.01) and psychological health status (p<.001). The main factors influencing social activity type, when compared with basic life maintenance type, were age (p<.05), economic activity (p<.001), and chronic disease (p<.001). The life satisfaction seen during free-leisure oriented time and social activity time was higher than that during basic life maintenance time. From these findings, practical and policy proposals were suggested to improve life satisfaction of older adults during basic life maintenance time by pursuing changes in the use of that time.

풍력발전기용 3점 지지 기어박스에서 캐리어 핀홀 위치 오차가 유성기어의 하중분할에 미치는 정성적 영향에 관한 실험적 연구

남주석(Ju-Seok Nam),한정우(Jeong-Woo Han) 한국생산제조학회 2016 한국생산제조학회지 Vol.25 No.2

In this study, the qualitative effects of the positional error of carrier pin holes on the planet load sharing characteristics of the three-point suspension gearbox of wind turbines were investigated experimentally. A 35-kW gearbox comprising two planetary gear stages and a parallel gear stage and size one-fourth of that of a 2-MW three-point suspension gearbox was used as the test gearbox. The strain gauges attached to the ring gear teeth of the input planetary gear stage were used for the purpose of this study. The applied loading conditions were 50%, 75%, and 100% of the rated torque, and the mesh load factor was used as the load sharing index. The experimental results indicated that both the magnitude and direction of the positional error of pin holes had a significant effect on the planet load sharing characteristics of the three-point suspension gearbox. In addition, an increase in the applied torque results in uniform load sharing.

제1발표장 : 노외기계시스템 분야 ; 메인 베어링 강성이 풍력발전기용 기어박스에 미치는 영향

남주석 ( Ju Seok Nam ),남용윤 ( Yong Yun Nam ),박영준 ( Young Jun Park ),이근호 ( Geun Ho Lee ) 한국농업기계학회 2015 한국농업기계학회 학술발표논문집 Vol.20 No.1