• Journal of Biosystems Engineering
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• v.18 no.4
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• pp.371-381
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• 1993

Threshing operation is performed by impact, compression and friction forces inside the thresher. These values should be appropriate to the crop condition to enhance the threshing and separating efficiency and to decrease the grain damage. To analyze the threshing process inside the rasp-bar type thresher, impact, friction and compression forces were measured using transducers with strain gage circuits. To measure the impact forces and friction forces between the rasp-bar and crop, full bridge strain gage circuit was built on the rasp-bar holder. To measure the compression forces and circumferential friction forces between the concave and crop, two sets of full bridge strain gage circuits were built on the T-type concave transducer. Threshing work of wheat crop with 12% of moisture content was performed at 3 levels of compression ratio and with 3 replications. Each transducer could not measure the exact forces continuously because the transducer oscillates with the forces. However they could measure maximum forces and force distribution according to the time. Average friction coefficients between crop and concave was 0.61 not showing any significant difference according to the compression ratio. Average acceleration of the crop in the cylinder appeared from $70.6m/s^2$ to $140.8m/s^2$ according to the compression ratio. The velocity of the crop at the exit of the cylinder appeared from 10.7m/s to 15.0m/s according to the compression ratio.

• Journal of Biosystems Engineering
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• v.37 no.2
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• pp.106-112
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• 2012

Purpose: A lab-scale timber carriage using a servo motor system was built. When two motors move a carriage, wire tension is changed according to the different line speeds caused by a wire drum's changing diameter, leading to inappropriate traveling characteristics of the carriage. In order to overcome this problem, PID Control was used to control the motor speed. Methods: Ziegler-Nichols method was used to determine PID gains. Results: The initial PID gains were 1.8, 0.025, and 0.006, respectively, and optimal gains of 1.4 and 0.010 for P and I gain were obtained experimentally. Conclusions: The results showed that constant wire tension could be maintained by controlling the speed of the motor using PI control. Overshoot occurred at initial motor operation due to vibration and elasticity of the wire itself.

• Journal of Animal Science and Technology
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• v.56 no.5
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• pp.19.1-19.6
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• 2014

The purpose of this study was to investigate crucial factors on HACCP system implementation in domestic livestock product plants, and to offer job satisfaction and the career prospect of HACCP system operators. The survey was carried out by selecting 150 HACCP system operators who implemented HACCP system. The respondents claimed that the most important contents in HACCP system operation were to assemble HACCP team (21.8%), and the second was to monitoring (20.0%). Documentation and recording (16.9%) and verification (11.1%) were followed. The respondents answered the major factor in sanitation management was cleaning/washing/disinfection (18.9%) and inspection (18.4%). The results showed that there were significant differences in the prospect of occupation in HACCP system operator by the gender (p < 0.015), age, livestock product facilities, service period, and position (p < 0.001). The respondents from HACCP system operator were satisfied with their job (73%) and also showed optimistic prospect of occupation (82%).

• Journal of Biosystems Engineering
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• v.4 no.1
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• pp.67-74
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• 1979

This survey was carried out to grasp the actual condition of a power tiller utilization . Now, the power tiller has become the leading machinery in the field of agriculture throughout the country . Two hundred farm houses, located in the provincial districts of Kimcheon and kum0rung, hav etaken part in the survey from October 1, 1976 to September 30, 1977. The results are summarized as follows . 1. The average size of cultivated land of a farm household in the districts surveyed was 1.77ha which was bigger than that of whole country. And the average age of power tiller drivers was analyzed in which only 105 of total drivers was on their 30's. 2. Distribution of a power tiller utilization was appeared to be 34.4% for transporting , 24% for tilling , 23% for pumping , 11.5% for threshing and 6.6% for spraying. 3. Frequency of a power tiller utilization was high during the month of June, July and October while it was low during February and December . 4. Distribution of repairing cost was 8.5% for trailer, 7.1% for throttle lever and 6.7% for casket, respectively. The annual cost for repairing was 5,290 won.5. The annual cost for using a power tiller was composed of 51.5% of fixed cost and 48.5% of operating cost. 6. Economic analysis showed that it was not economically practical for individual ownership of a power tiller on the farm surveyed. Therefore, custom operation and joint ownership by a few farmers were recommended.

• Journal of Biosystems Engineering
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• v.19 no.2
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• pp.112-123
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• 1994

At present, no appropriate drying conditions can be found for the heated-air drying of mushroom in Korea. Usually, mushroom is being dried at the temperature range of 40 to $50^{\circ}C$ until the moisture content reaches 10~13% (wb). However, drying characteristics of the mushroom should be investigated for quality improvement and efficient drying operation of the mushroom. The results of this study may be summarized as follows ; 1. The effect of air temperature on the rate of drying was greater than that of relative humidity for drying of mushroom, and the rate of drying was increased with increase in the air temperature. 2. Drying rate for Shiitake mushroom showed falling-rate period of drying without constant-rate period of drying. Drying rate for Oyster mushroom showed a short constant-rate period at the initial stage of drying process, and followed by falling-rate period of drying. 3. Exponential and App.-Diffusion models were found to describe well the drying process of Shiitake mushroom. Exponential and Thompson models for Oyster mushroom in which Thompson model was the most suitable for Oyster mushroom. 4. The equilibrium moisture content of the mushroom decreased with decrease in the air temperature and increase in the relative humidity. In room condition($20^{\circ}C$, 54% RH), the calculated values of the equilibrium moisture content showed 11.17% for Shiitake mushroom and 13.19% for Oyster mushroom, respectively.

• Journal of Biosystems Engineering
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• v.32 no.2 s.121
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• pp.91-96
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• 2007

In this study, a prototype remote controlled weeder using solar module was developed and the evaluations of weeding, side walking and weeding performance were conducted to see if actual application was feasible in the paddy field. When traveling, the loss electric current was 8 to 15 A depending on operating and soil conditions. The average traveling speed was 0.25 m/s and the average slippage was 18%. When it side walked row by row, electric current consumption was 7 A on the average. When wheel rotors line went initially up and last down, electric current consumption was 12 to 15 A due to soil resistance. Electric current consumption when shifting wheel rotors line was less than 5 A due to no resistance. Field efficiency was 105 min/10a based on the test field. Operation was able to be done for 4.16 hours continually by 52 AH battery based on 300 W average maximum power consumption and 4.6 hours under sunny day considering solar module.

• Journal of Power System Engineering
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• v.20 no.5
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• pp.37-45
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• 2016

Exhaust gas recirculation has the advantage of being low-cost and easy to control of NOx emission. Therefore, it is most generally used to reduce NOx emission according to strengthen regulation. In the case of a non-road engine, such as the agricultural engine, since it mainly operate a middle or high-load state, NOx emission is decreased in accordance with the mapping range of the EGR rate, but results in an increase in the particulate matter which is caused to deposit and fouling problem of the EGR system. This problem has become an important issue for maintaining the performance of the engine, as well as emission performance. This study had examined the effects of cooler aging on the performance of heat transfer efficiency and NOx emission in non-road diesel engine. As a result of the EGR cooler aging during 200 hours engine operation, the cooling performance decreased about 25% compared with that of fresh cooler and the NOx emission increased about 14.6% on NRSC(non-road steady cycle) and 20% on NRTC(non-road transient cycle) compared with that of fresh cooler respectively.

• The Korean Journal of Community Living Science
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• v.26 no.2
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• pp.335-349
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• 2015

The system of School Meal Service Support Centers was established to support the supply of high-quality food ingredients for school meal services when the School Meal Service Act was amended in 2006. A case study was conducted to examine the operating effects, success factors, and major obstacles of a School Meal Service Support Center which was highly evaluated for its operational efficiency and customer satisfaction. Qualitative data were collected from eight stakeholders (two individuals each from the center, farms, schools, and distributors) through in-depth interviews in July 2013 and analyzed by using the thematic analysis method. The successful operation of the center helped to stabilize income and price among the stakeholders, increase ingredient quality, increase school meal reliability, reduce costs, and promote the consumption of agricultural products. Success factors were identified as the center director's commitment and insights, and the competitive operating system including fair operations, rational pricing, liberal consumer choice, total quality management, and partnerships with distributors. Major obstacles included a lack of diversity in supplied ingredients and a lack of administrative and financial support form the local government. The results can be used as baseline information to vitalize the system of School Meal Service Support Centers and increase the quality of school meal services.

• Journal of agricultural medicine and community health
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• v.17 no.2
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• pp.129-136
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• 1992

To evaluate the possible route of intrafamilial transmission among carriers of hepatitis B surface antigen ($HB_sAg$), epidemiologic and serologic data were obtained on 107 household contacts of 35 carriers of HBsAg and on 71 household contacts of 25 controls who were negative for serologic markers of hepatitis B virus. The HBsAg prevalence was 26.5% among the contacts of carriers compared to 0.0% among the contacts of controls. And the combined prevalence for all hepatitis markers was 48.5% among the contacts of carriers compared to 26.0% among the contacts of controls(p<0.05). Especially the offspring of carriers showed significantly higher risk in the combined prevalence for all hepatitis markers (p<0.05). There were no significant relationship between HBV infection and past history like acupuncture, transfusion, operation and tattooed. Factors associated with the risk of intrafamilial transmission of HBV were not found in the sharing of household articles such as razor, towel, drinking glass, nail clippers, toothbrush and tableware.

• Journal of Biosystems Engineering
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• v.20 no.1
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• pp.3-12
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• 1995

This study was conducted to investigate the cutting mechanism of the reciprocating knife of combine harvester. The cutting operation of reciprocating knife was demonstrated through the cutting pattern diagram which was drawn by computer graphics. Various kinds and dimensions of standard-type reciprocating knives were analyzed by the developed program. The results are summarized as follows : (1) For the 50mm standard reciprocating knife, the bunching area and the maximum stalk-deflection were decreased rapidly according to the increase of cutting velocity ratio by 1.0 and decreased very slowly over this ratio. But, the secondary cut was occurred at ratio of 1.0 and increased rapidly over this ratio. (2) The 76mm standard knife showed better cutting mechanism than the 50mm, in two respects : the larger cutting area per one stroke and the lower revolutional speed of crank shaft for the same cutting velocity. (3) In respect to the bunching area and the secondary cutting length, the adequate height of 50mm standard reciprocating knife was 45~50mm. (4) In order to maintain the proper cutting mechanism, the adequate cutting velocity at forward speed of 0.5㎧ to 1.2m/s was from 0.4m/s to 1.2m/s for the standard knife.