• Journal of Biosystems Engineering
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• v.9 no.1
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• pp.11-21
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• 1984

This study was intended to analyze the dynamic force system which induced the shattering of paddy grains. A model to predict the shattering of paddy grains was developed, and physical quantities, such as mass distribution and rigidity of rice plant, needed for evaluating the minimum shattering forces were also measured. Under the assumption that rice plant right before harvesting is a vibratory system, the mathematical model of the vibratory system was developed and solved with the varied conditions of forcing functions. The results of the study were summarized as follows: 1. The shattering of grain occurred at the abscission layer of grain by the bending moments resulted from the impact force due to the collision of panicles of rice plant. 2. The vibratory model developed for milyang 23 rice variety was analyzed to give the natural frequencies of 7-9 Hz, which were closely related with the excitation frequencies of 4-10 Hz caused by various machine parts besides engine. Thus, avoiding the resonance should be taken into consideration in the design of the harvesting machinery. 3. It was analyzed to predict the lowest frequency that could develop the shattering when the excitation force was applied to the lower end of stem. The lowest frequency for the Milyang 23 rice variety ranged from 8.33 Hz to 11.66 Hz as the amplitude varied from 1 cm to 2.5 cm. 4. The degree of shattering depended upon the magnitude of the impact force and its application point. For Milyang 23 rice variety, the minimum impact force developing the shattering was $5g_f$ when it was applied at 1 cm above the lower end of stern and $1g_f$ when applied at 5 cm above the lower end of stem. 5. The minimum colliding velocity of the panicle, when it was on the ground that would just develop the shattering, was given as follows, $$V=\sqrt{\frac{K_t}{m_g}{\cdot}{{\phi}^2}}$$ where V : The colliding velocity of the panicle against ground to cause the shatteering of rice grain. (cm/sec) $K_t$ : The minimum spring constant for bending at the abscission layer of grain. (dyne-cm/rad) ${\phi}$ : The minimum shattering angle of grain (rad) $m_g$ : The maximum mass of grain. (g).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.7
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• pp.867-872
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• 2010

Unused energy derived from sources in nature can be captured and stored for future use, for example, to recharge a battery or power a device; this process of capturing and storing energy is called energy harvesting. Extensive investigations are being carried out in order to use piezoelectricity to harvest the energy generated by body movements or machine vibrations. This paper presents a simple analytical model that describes the output voltage effectiveness of a Piezocomposite Generating Element (PCGE) from vibration and its experimental verification. PCGE is composed of carbon/epoxy, PZT, and glass/epoxy layers. During the manufacturing process, the stacked layers were cured at $177^{\circ}C$ in an autoclave, which created residual stresses in PCGE and altered the piezoelectric properties of the PZT layer. In the experiments, three kinds of lay-up configurations of PCGE were considered to verify the proposed prediction model and to investigate its capability to convert oscillatory mechanical energy into electrical energy. The predicted performance results are in good agreement with observed experimental ones.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1996.06c
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• pp.967-976
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• 1996

Straw and other fibrous by-products are inevitably produced during cereal production and have traditionally been used for many purposes including feeding animals . The potential of these by -products as a feed resource for ruminants is being increasingly appreciated (FAO , 1977). In the future, the amount of cereals fed to farm animals will have to be reduced and livestock will have to rely more on by-products such as straw. The method of animal production can be classified by the major portion of feed. One is animal forage and the other is grains. In Korea , livestock farmers normally depend more than 70% upon grains for the feed stuff. The livestock production system causes the unbalance of nutrition, and results in low productivity of animal farming. In many livestock farms in Korea the rice straw is using as a major forage and the amount of rice straw fed takes 46% of total amount of required forages. Especially the rice straw is mainly using during spring, fall and winte season. However, there are still lots of problems to solved such as harvesting cost, transportation between rice farm ad livestock farm, and quality loss during drying and storage . Therefore the mechanization of straw harvesting is urgently needed to use the renewable agricultural by-products and to overcome the shortage of animal forage. The objective of this research is to develope a straw harvester with new concept which can solve the problems of the quality loss and the labor cost during drying in a field, collecting , and storage. The developed straw harvester is self-propelled machine rebuilt by rice combine and equipped with the pick-up device, the macerater and the mat-forming device.

• Journal of the Korea Society for Simulation
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• v.29 no.3
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• pp.19-25
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• 2020

The field farming machine is difficult to develop due to its heavy slopes, tough roads and unformatted cultivation by growing crops. In particular, harvesting is a major problem in rural areas in Republic of Korea where aging is accelerated with work requiring a lot of time and manpower. This study seeks to analyze the dynamic characteristics of hot pepper harvester developed to replace manpower, reduce working hours and mechanize harvesting operations. To analyze the dynamic characteristics of a hot pepper harvester, the dynamic program Recurdyn was used and all analysis were performed as case of an empty vehicle. Based on the results, this study can suggest dynamic safety range of multi-purpose driving platform with hot pepper harvester.

• Journal of Forest and Environmental Science
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• v.35 no.3
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• pp.197-204
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• 2019

A tree-length harvesting system using the HAM300, which is mounted on a farm tractor prototype machine, have been recently introduced in South Korea for thinning old (>30 years) forests. However, no research has previously been conducted on the characteristics of residual stand damage associated with cable yarding systems on thinning treatment stands in South Korea. Therefore, there were assessed on the degree and quantity of residual stand damage caused by felling and yarding process to broaden the knowledge of residual stand damage on semi-mechanized skyline thinning operations. This study investigated scar size, direction, area, shape type and their distribution on the residual stand damage caused by felling and yarding operations. Damage to residual trees was generated for 7.4% and 6.9% of residual trees in felling and yarding operations, respectively. Damaged direction of scars was located in front-side (38.9%) and up-side (34.7%) for felling operations while the highest scar damage was found on down-side (44.6%) for yarding operations. Scar heights of felling damage were higher than those of yarding damage. In yarding operation, the most of the scars was located within l0m from the center of the skyline corridor. These results should be useful information for forest managers and landowners to reduce residual stand damages and retain valuable timber volume from thinning treatments.

• Journal of Forest and Environmental Science
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• v.9 no.1
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• pp.1-9
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• 1993

In the fall of 1992, growth characteristics and cone-bearing behaviour of crown top shoots were investigated on Pin us koraiensis trees, belonging to age class VII and IV, in the School Forests, College of Forestry, Kangwon National University to obtain basic information for the design of Korean pine cone harvesting machine. The results were summarized as follows. 1. The length of terminal main shoots and lateral shoots of the trees in age class IV was 27~56cm and 18~47cm, respectively, both of which were significantly higher than those of the trees in age class VII. 2. There was no significant difference between two age classes in the branching angle ($24{\sim}89^{\circ}$) of lateral shoots and in the diameter (10~30mm) of two-year-old main shoots. However, one-year-old terminal main shoots of age class IV showed the higher diameter (9~18mm) than those of age class VII. 3. Mean cone number per tree was 5, and mean fresh weight of cone was 272g. No significant difference was found in these traits between both age classes. 4. Cones, on an average, hung on the two-year-old main shoots 15cm above the basal ends in age class VII and 33cm above in age class IV. Both lengths are equivalent to one half and four fifths of the shoots, respectively. 5. The fresh weight range of crown-top shoots containing cones was 1.0~7.4kg.

• Korean Journal of Environment and Ecology
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• v.22 no.3
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• pp.301-308
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• 2008

We conducted the survey about the avian fauna, population, community and correlation between avian population and densities of the fallen rice grain in Cheonsu reclaimed area(Ganwol and Bunam Lake and reclaimed land) from Oct. 2006 to Mar. 2007. Total surveyed species number was 142 species, sum of maximum count of each species was 362,797 individuals, sum of average count of each species was 84,818 individuals. Comparing with early and late wintering season, number of species was stable in each survey time, but total population was decreased as the season progressed. Dominant species were Bean Geese Anser fabalis, Baikal Teals Anas formosa, White-fronted Geese Anser albifrons, Mallards Anas platyrhynchos and Pintails Anas acuta. Population fluctuation of the Bean Geese Anser fabalis, Baikal Teals Anas formosa, Mallards Anas platyrhynchos, PintailsAnas acuta was decreasing, but population of the White-fronted Geese Anser albifrons was stable. Number of species, total population were not significantly different among Ganwol, Bunam and Cheonsu Bay. Survey period was significantly correlated with species diversity and population in each area, and most community indices of each area were shown significant correlation. The density of the fallen rice grain was significantly different between the harvested rice paddy by big harvesting machine and small harvesting machine. Density of the fallen rice grain in stubble collected area was significantly different with area of stubble not collected. Density of the fallen rice grain was drastically decreased in the middle of wintering season, but not significantly different between Dec. 2006 and Feb. 2007. Avian population was strongly correlated with number of fallen rice grain in the same period.

• Journal of Korean Society of Forest Science
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• v.83 no.3
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• pp.299-310
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• 1994

This study was carried out to examine the optimal road spacing and road density to minimize the total harvesting cost(road construction cost plus yarding cost) for mechanized yarding system to roadside by one - and two-stage two-way in Forestry build-up region. Chunchon-kun, Kangwon-do. The estimated road construction costs were ranged from ten million won to sixty million won per km. The results have indicated that cable crane was appropriate for yarding machine by one-stage, two-way, and estimated optimal road spacing was 1,698m~4,192m, averaged 3,087m, and road density was 3.44m/ha~8.44m/ha, and averaged 5. 12m/ha. In hilly terrain, combination of medium yarder and Logging bogie was suited to yarding machine by two-stage, two-way, and calculated optimal road spacing was 1,483m~3,481m, averaged 2,589m, and road density was 4.05m/ha~9.46m/ha, averaged 5.90m/ha. In steep terrain, combination of medium yarder and jinsung winch was suited, and estimated optimal road spacing was 1,693m~3,982m, averaged 2,960m, and road density was 3.68m/ha~8.64m/ha, averaged 5.38m/ha.

• Korean Journal of Medicinal Crop Science
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• v.5 no.4
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• pp.284-288
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• 1997

In order to study on suitable harvest time of adlay utilizing self-feeding combine harvester with four rows, which is originally designed for rice harvest, harvesting were carried out at four different times (40, 50, 60 and 70 days after anthesis) . For efficient operation, appropriate working rows were 2 rows at 50 days after anthesis and working speed was 0.26m/sec at 60 days after anthesis. Theoretical working capability was 11.23a/hr at 60 days after anthesis. As the harvesting was delayed, water content of adlay decreased. Water content of culm+leaf was $69.7{\sim}55.3%$ and water content of grain was 34.2% at 60 days after anthesis. The later adlay was harvested. the higher the percent of ripened grain was. But the immature grain was decreased. Remnants was less than 1.8% at 60 days after anthesis. The later adlay was harvested, the heavier volume weight was. Yield was the highest at 60 days after anthesis. When utilizing self-feeding combine harvester with four rows, which was originally designed for rice harvest, suitable harvesting time was 60 days after anthesis. Therefore, theoretically suitable harvest time was 68 days after anthesis.

• Journal of Korean Society of Forest Science
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• v.108 no.4
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• pp.562-573
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• 2019

In a cable yarding system, a small-scale tower yarder attached to a farm tractor wasdeveloped and used for small-diameter tree harvesting operations. Based on this design, improvement of traction performance was required for medium- and large-diameter tree harvesting operations. In this study, the mechanical transmission employed for the tower yarder was modified into ahydro-mechanical transmission system. Maximum traction forces, including tractor engine speed and hydraulic power pressure, were investigated, and comparisons were made between the mechanical and hydro-mechanical transmission systems. Six tractor engine speeds (1,200, 1,400, 1,600, 1,800, 2,000, and 2,200) and three levels of power transmission mechanism pressure (4.9, 6.9, and 8.8 MPa) were investigated in the two different transmission systems. Results showed a maximum traction force of 15,146.6 N at an engine rotation speed of 757 rpm in the current mechanical transmission system, and 36,140.0 N at anengine rotation speed of 1,575 rpm in the modified hydro-mechanical transmission system. The maximum traction forces for the hydro-mechanical transmission were 2.4 times greater than those of the mechanical transmission, and may therefore be applicable to medium and large-diameter tree harvesting operations. Thus,as a modified version of the conventional transmission system, the new hydro-mechanical transmission system may be cost-effective for use in large-scale cable yarding operations. In the future, however, it will be necessary to investigate problems that may arise from field application tests.