• Journal of Biosystems Engineering
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• v.15 no.2
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• pp.143-150
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• 1990

This study was conducted to estimate the ratio of Repair & Maintenance (R&M) costs to purchasing price that is one of the important factors for calculating the management costs of farm machinery. For this purpose, hour of use and R & M costs of power tiller and its attachments utilized results that were investigated with 400 sample units, 50 units by years of use from 1 to 8 years in 1988. The results obtained are summarized as follows; 1. The ratio of R & M costs per hours and annual R & M costs, accumulated R & M costs when sercice life of power tiller is 7 years were 0.017%, 5.50% and 38.52%, respectively. And in case of rotary, these ratio when its service life is 6 years were 0.072%, 7.16% and 43.0%, respectively. 2. The relationship between accumulated hours of use(t) and accumulated R & M costs(Y) of power tiller and its attachments were $Y=19.3t^{1.3}$ in power tiller, $Y=0.03t^{2.09}$ in plow, $Y=48.84t^{1.25}$ in rotary and $Y=7.45t^{1.15}$ in trailer. 3. The ratio of accumulated R & M costs to purchasing price when service life of power tiller is 7 years was 38.5%, and in case of rotary, this ratio when its service life is 6 years was 43.0%.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.4
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• pp.160-168
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• 2018

Among the components of rotary hooks, a core component of an embroidery sewing system, a study was conducted to apply metal injection molding to the manufacture of a hook body and a housing that was very difficult to mechanical working. The correlation of feedstock, a mixture of binder and SCM 415 metal powder, and properties of the pressure-volume-temperature interrelationship, viscosity, specific heat, and thermal conductivity were measured. Injection molds for the hook body and the housing were developed through injection molding analysis using these properties and conducted injection tests. Optimal injection gate position and number, injection pressure, and injection time were obtained through a comparison of analysis results with the experiment results.

• The KSFM Journal of Fluid Machinery
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• v.8 no.2 s.29
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• pp.23-30
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• 2005

The rotary compressor is widely used in the air conditioner because it is efficient and compact. Recently, the need for silent and efficient compressors is much stronger than the past. The new type muffler was invented to reduce the noise level and to improve the efficiency. The new type muffler that has two side discharge holes and dome shape resulted in much lower overall noise level, especially noise levels around 1kHz than the old type one of one center discharge hole in the acoustic spectra. Also it showed a higher efficiency of air conditioner by lowering oil discharging amount of a compressor than old type one of a rectangular shape and two side discharge holes. The noise reduction and efficiency improvement by the new type muffler were verified by tests for votary compressors and air conditioners.

• The KSFM Journal of Fluid Machinery
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• v.14 no.3
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• pp.28-32
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• 2011

The inverter rotary compressor discharges refrigerant and compressor oil in air-conditioning systems. The compressor oil which discharged form compressor decreases the efficiency of heat exchanger and affects the compressor operation. Recently, several studies are in progress for reducing the compressor oil. Before the reduction of compressor oil discharge rate, the quantitative measurement and evaluation method are required. In order to cope with this requirement we have developed the measurement technic of oil discharge rate. The reliability assessment was carried out approximately 0.1% of the errors with compressor performance indicators. The acceptable errors were to ensure the reliability of measurement technic. In the experiment results at several conditions, The oil discharge rate of heating operation has been confirmed average 3.7 times more than cooling operation. In this study the evaluation method and the experimental results of oil discharge rate in air-conditioning systems are presented with various operating conditions.

• Journal of Biosystems Engineering
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• v.18 no.1
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• pp.15-20
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• 1993

Wearness has been a major failure criterion in Korean-made rotary blade. However, few studies have been conducted to improve it. In this study, the fundamental data obtained from the measurement of wearness and failure of rotary blade were analyzed to provide a guideline for the design of rotary blades. For the straight part(about 20-23 em from bolt hole) from the bolt hole to bending point of rotary blade, modifications were proposed for improvements, however, for the portion from bending point to tip was made no design recommendations because the failure behavior of that portion was difficult to analyze with the experimental data. The results are summarized as follows. 1. The current V-shape section has to be moved about 5 em toward the bending point of rotary blade. 2. The section modulus at the portion about 5-7 em distant from bolt hole has to be increased about 15-20 %. 3. The V-shape section has to be changed into U-shape to reduce the on account of recieving initial stress in blades. 4. The radius of curvature of the neck(the portion about 5-7 cm apart from bolt hole) has to be made larger to decrease the stress concentration.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.101-108
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• 2000

The torque loads were measured at the input shaft of the transmission and driving shaft of the tractor having a cage wheel attached to the driving tires as a traction aid during. a rotavating operation in wet paddy fields with deep hardpan. Their load spectra were also calculated. Effects of design parameters of the cage wheel on the load characteristics were analyzed. The torque load exerted on the input shaft decreased as diameter of the cage wheel increased and increased as the rotating speed of the rotavator increased. The torque load exerted on the driving shaft increased as the working speed of the tractor increased and decreased as the PTO speed increased. Both the torque loads with the cage wheel were greater than those without the cage wheel. The cage wheel was developed for this study.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.872-876
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• 1996

Most studies of rotary machinery design have been performed to establsih a new mechanism or a dramatic combination of machine elements for the power transmission. Although the rotary machine is worked very efficiently, that still has a major work to better performance which is the optimization of the selected mechanism for the mechanical efficiency, low vibration and noise, or customer interest. This work presents a practical approach used for washer's efficiency and machinery vibration and noise reduction along with a systematic procedure. Also for the confirming the study, a computer simulation program and a real working mock-up are developed and used to show very good agreement with the analytical result.

• The KSFM Journal of Fluid Machinery
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• v.7 no.6 s.27
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• pp.7-14
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• 2004

A new electrostatic rotary atomizing painting equipment using air turbine was developed for high transfer efficiency. Based on the overall design requirements of painting equipment, basic design specifications of the equipment parts such as air turbine and atomizing disk ate defined from the present conceptual design model. Air turbine is designed with the section profile of NACA airfoil, and its internal flow field is analyzed by commercial CFD code. Atomizing disk is designed to achieve the ligament type spray of paint with the use of visualization technique. Various experiments and tests are conducted to investigate the spray and the transfer characteristics of newly-designed painting equipment, and the measurement results are compared with the those of conventional painting equipments. The comparison results show the present painting equipment is superior to the conventional ones in the aspects of transfer efficiency and coating surface characteristics.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.517-522
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• 2002

본 연구는 트랙터용 로타리날의 운동특성을 분석하는 연구로서, 로타리날의 운동특성 분석장치를 이용하여 기존에 국내에서 사용되는 로타리날로 경운 작업을 할 경우, 로타리날 운동 및 형상, 구조에 따른 운동특성을 정밀 분석하였다. 본 연구에서 분석된 문제점 및 보완점을 앞으로 개발될 에너지 절감형 트랙터 로타리날 개발에 필요한 주요 인자를 결정하기 위한 수단으로 사용하는 데 목적이 있으며, 그 구체적인 연구 결과는 다음과 같다. (1) 로타리날의 운동특성을 분석할 수 있는 로타리날 운동특성 분석 시스템을 설계, 제작하였다. (2) 분석 시스템 제어용 프로그램 Visual Basic 6.0 프로그래밍 언어를 사용하여 개발하였다. (3) 국내 로타리날 제조회사 4곳 및 외국 1개사 제품의 운동특성을 분석한 결과, B, C, E maker 제품이 로타리 경운 작업에 적합한 것으로 분석되었다. (4) B, C, E maker 제품에서 살펴보면, 토양을 절단할 때의 경심별 위치를 \circled3부분이 되도록 해야하며, 단면이 확실하게 닿지 않도록 단면의 경우 B maker 형상을 따라야 한다. 또한 배면이 토양에 닿는 부위가 적어야 한다.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11b
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• pp.178-187
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• 2000

The tillage operation by rotary implements is widely done in Korea. In the case of rotary implements, the tillage depth control system is one of important implement control systems. A contact type-sensor for measurement of the ground height was designed and fabricated to evaluate the possibility of application of the sensor on the tillage depth control system. Indoor experiments were conducted to obtain static and dynamic detection characteristics of the sensor under various conditions; 1) several moisture contents for four soil samples, 2) two soil surfaces with a designed configuration, 3) four heights of the sensor from the soil surface, 4) five traveling speeds of the carrier on which the sensor was attached, and so on. The experimental results showed the detection characteristics of the sensor sufficient as the ground height sensor of the tillage depth control system.