• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1993년도 Proceedings of International Conference for Agricultural Machinery and Process Engineering
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• pp.139-147
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• 1993

The rapid industrial growth, the consequent shortage of farm labour and increase in their wage level have facilitated more capitalized agricultural mechanization pattern in Korea. The efficiency of capital intensive machine is highly dependent on farm land structure. This paper describes a model explaining the relationship between farmland structure and required inputs for machine operation and to estimate required inputs for machine operation on the national basis for Korea for its paddy production system. The machine cost is closely related to operation area, but the required labour-hours are more related to machine type adopted . From the technology introduction point of view, if capital intensive machine is introduced, less labour-hours are required but machine kW-hours increase rapidly. From the plot geometry point of view, on good geometry plots, machine kW-hour and labour-hour required are less than that on the poor geometry plots. The kW-jhour per hectare of mechani al energy input id better indicator of mechanization level than kW per hectare or number of machine. If the adopted technology is more capital intensive and plot geometry is good, the cost reduction effect is highly significant.

• Advances in aircraft and spacecraft science
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• 제7권3호
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• pp.215-228
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• 2020

As is shown in the paper, the Koltunov-Rzhanitsyn singular kernel of heredity (when constructing mathematical models of the dynamics problem of the hereditary theory of viscoelasticity) adequately describes real mechanical processes, best approximates experimental data for a long period of time. A mathematical model of the problem of the flutter of viscoelastic plates moving in a gas with a high supersonic velocity is given. Using the Bubnov-Galerkin method, discrete models of the problem of the flatter of viscoelastic plates flowed over by supersonic gas flow are obtained. A numerical method is developed to solve nonlinear integro-differential equations (IDE) for the problem of the hereditary theory of viscoelasticity with weakly singular kernels. A general computational algorithm and a system of application programs have been developed, which allow one to investigate the nonlinear dynamic problems of the hereditary theory of viscoelasticity with weakly singular kernels. On the basis of the proposed numerical method and algorithm, nonlinear problems of the flutter of viscoelastic plates flowed over in a gas flow at an arbitrary angle are investigated. In a wide range of changes in various parameters of the plate, the critical velocity of the flutter is determined. It is shown that the singularity parameter α affects not only the oscillations of viscoelastic systems, but the critical velocity of the flutter as well.

• Journal of Biosystems Engineering
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• 제31권6호
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• pp.500-505
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• 2006

Jujube is one of korean most favorite fruits. Harvesting operations of the jujube farming, however, completely depend on hand labor. Especially, collecting operation requires about three times of hand labor compared with separate operation by impacting or shaking of twigs in the hand-harvesting system of jujube fruits. Consequently, jujube farmers sincerely demand the mechanization of the collecting operation of jujube fruits in the harvesting operation. A new collecting system was designed and constructed five parts-collecting pad, guide ring system, sorting system, frame with driving system, and handle with operation levers, which performed collecting operation of jujube fruits without missing fruits in five part functions, however, an extra future more deliberate study would need how to handle conveniently the collecting pad of the prototype in the narrow space of row of the jujube farm.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 학술발표대회 논문집
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• pp.154-158
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• 1996

• 화약ㆍ발파
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• 제24권1호
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• pp.29-37
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• 2006

최근 국내 터널현장에서 기계식 장전장비를 활용한 벌크에멀전 (bulk emulsion) 폭약의 수요가 증가되면서 국내 암반 및 주변여건에 적합한 발파의 합리적인 설계기준이 요구되고 있다. 본 연구에서는 현재까지 국내에서 기계식 장전장비를 활용한 벌크에멀젼 폭약을 적용하여 시공한 사례 중 굴진효율 및 여굴량이 양호한 발파결과를 근거로 암반등급별 최적 비장약량과 영역별 적정 장약량을 검토하였다. 또한, 조건을 만족하는 발파결과를 분석하여 RMR 암반분류와 벌크에멀젼 폭약의 최적 비장약량과의 상관식 $({\Upsilon}= 0.669 + (0.0154{\times}RMR),\;r=0.81)$을 얻었고, 영역별로 천공장 변화에 따른 적정 장약량 범위를 산출하였다.

• 농업과학연구
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• 제48권4호
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• pp.1039-1050
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• 2021

The purpose of this study is to measure load data for a 55 kW class agricultural tractor during a harvesting operation and to analyze the required power according to the working conditions. A field test was conducted at three different tractor speeds (1.2, 1.3, and 1.4 km·h^-1). A load measurement system was developed for the front axles, rear axles, and for power take-off (PTO). The torque and rotational speeds of the axles and PTO were measured during the field test and were calculated as the required power. The results showed that the total required power was in the range of 4.86 - 5.48 kW during the harvesting operation according to the tractor speed, and it was confirmed that this represents a ratio of 8.8 - 10.0% of the engine rated power. Also, it was confirmed that the required power of the axle and PTO increased as the tractor speed increased. In future studies, we plan to supplement the measurement system for a tractor to include a hydraulic system and perform a field test for harvesting various underground crops.

• Journal of Biosystems Engineering
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• 제27권5호
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• pp.425-432
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• 2002

This study was carried out to develop an automatic mixing system of nutrient solution for closed-loop hydroponics using ion electrodes. The results of the study are summarized as follows: 1. It appeared that ion-electrodes had not to be soaked into nutrient solution for a long time since it was much less durable than EC or PH sensors. Once ion-electrodes were soaked into real nutrient solution for a long time, they became unstable. 2. ion measurement modules, which were able to sample recirculated nutrient solution and easily wash and dry ion-electrodes, were developed in order to use ion-electrodes continuously. 3. The results of calibration tests on three kinds of ion electrodes presented that the time required to read measurement data was over 30 seconds. Using the calibration data the regression equations for the ion electrodes were developed. 4. An automatic nutrient-solution mixing system using the three kinds of ion electrodes was developed and then its accuracy was examined. The control errors of the mixing system using ion electrodes were in the range of 9.8 to 12%.

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 1996년도 International Conference on Agricultural Machinery Engineering Proceedings
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• pp.344-353
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• 1996

A fundamental study was conducted to obtain the basic data involved in nondestructive quality evaluation of the fruit and vegetables. An experimental equipment for ultrasonic propagation characteristics of the fruit and vegetables such as radish , carrot , potato, and apple was set up and also power spectrum analysis system of an ultrasonic wave through the fruit and vegetables was set up. The velocity and attenuation of ultrasonic wave through the tissue specimens from the fruit and vegetables were measured and analyzed. The elastic modulus and density by the mechanical method currently used were compared with those using by ultrasonic method. The ultrasonic tranit time was almost linearly increased with the length of the specimens and attenuation of ultrasonic was mainly affected by the internal flbrous structure of the products. The regression equation was derived from the highly correlated experimental variables.

• Journal of Forest and Environmental Science
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• 제23권2호
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• pp.109-118
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• 2007

본 연구는 임업노동력 현황과 양성방안을 분석하여 향후 임업노동력의 확보 및 임업기계화의 활성화 등을 위한 정책방안의 기초자료를 제공할 목적으로 수행하였다. 산림작업 종별 총 고용인원과 인건비는 매년 조금씩 증가하고 있는 추세이나 벌채 총 고용인력은 오히려 감소하고 있으며, 전문 기계화작업단 구성과 오퍼레이터의 양성이 필요하겠다. 현재 임업현장의 중심적인 활동을 펴고 있는 영림단의 수와 단원수가 해매다 늘어나고 있고 연간 작업일수와 소득도 늘어나고 있는 실정이다. 그러나 기능인영림단의 월평균 작업일수가 15일로 연간 작업일수가 180일에 불과하였다. 우리나라의 연간 총 숲가꾸기 사업량을 중심으로 기능인영림단 및 단원수를 산출한 결과, 약 349개의 기능인영림단이 필요하고 이에 따른 기능인영림단 1개당 단원수를 12명으로 적용했을 경우, 전체 기능인영림단의 단원수는 약 4,185명이 필요하다는 것을 알 수 있었다. 또한 우리나라의 연간 목재 생산량을 중심으로 타워야더형 임목수확작업시스템을 적용하여 적정 기계화영림단 및 단원수를 산출한 결과, 250개의 기계화영림단이 필요하고 기계화영림단당 단원수를 5명으로 적용했을 경우, 전체 기계화영림단의 단원수는 1,250명이 필요하다는 것을 알 수 있었다.

• 한국작물학회:학술대회논문집
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• 한국작물학회 1997년도 춘계 학술대회지
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• pp.74-75
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• 1997