• Proceedings of the KIEE Conference
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• 1999.07f
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• pp.2733-2735
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• 1999

The conducted noises mainly emitted from PWM DC power supply have a periodicity with respect to switching frequency, and especially center at the switching frequency and the discrete harmonic frequencies. The concentration of noise energy at these discrete frequencies makes it harder to meet EMI regulations. To reduce the conducted noises, this paper presents the novel FM-PWM control method by using random switching frequency modulation control. This control makes it to generate the noises of side bands by shattering emission spectrum, and to reduce the peak level of conducted noises.

• Proceedings of the Korean Society of Crop Science Conference
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• 2018.04a
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• pp.175-175
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• 2018

• Journal of Biosystems Engineering
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• v.40 no.2
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• pp.102-109
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• 2015

Purpose: Slow manual harvesting of rain-fed chickpeas cultivated in fallow fields in developing countries have encouraged the design of a mechanical harvester. Methods: A tractor-pulled harvester was built, in which a modified stripper header detached pods from an anchored plant and a chain conveyor transferred material. The stripper harvester was redesigned to use: 1) the maneuverability of tractor-mounted frames, 2) the adaptability of floating headers, and 3) the flexibility of pneumatic conveyors. Results: A mobile vacuum conveyor, which was an innovator open system, was designed for the dilute phase transferring mode for both grain and material other than grain. A centrifugal fan transferred harvested material to a cyclone separator that settled harvested material in a grain tank 1 m high. The machine at the spot work rate of $0.42ha{\cdot}h^{-1}$ harvested chickpea pods equal to the output of 16.6 farm laborers. Conclusion: The low cost and reasonable projected purchase price are the advantages of the concept. Additionally, the shattering loss reduction confirms the feasibility of the prototype chickpea harvester for commercialization.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.62-70
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• 2008

An adaptive fuzzy backstepping controller is proposed for the motion control for a single-link flexible-joint robot in the presence of parametric uncertainties. Fuzzy logic system is used to approximate the uncertainties of functions and a backstepping technique is employed to deal with the mismatched problem. A compensation controller is also employed to estimates the bound of approximation error so that the shattering effect of the control effort can be reduced. Thus the asymptotic stability of the closed loop control system can be obtained based on a Lyapunov synthesis approach. Numerical simulation results for a single-link flexible-joint robot are included to show the effectiveness of proposed controller.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.4
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• pp.353-364
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• 2020

Recently in Korea, soybean harvesting has been delayed due to rainfall during the harvesting season, resulting in a reduction in yield and seed quality. This study was conducted to analyze the changes in yield and seed quality during delayed harvest with rainfall treatment using different harvesting methods, including field harvesting and polyethylene film covering after cutting fully-matured soybean plants (PE covering after cutting), with two major Korean soybean cultivars (Glycine max L), Pungsannamulkong and Daewonkong. The shattering rate of Pungsannamulkong, which is higher than that of Daewonkong, increased up to 41.8% when the harvest was delayed for 40 days without rainfall treatment by harvesting with PE covering after cutting. The weight of 100 seeds tended to decrease slightly as harvesting was delayed. When Daewonkong was harvested using the PE covering after cutting method with rainfall treatment, the yield decreased to the lowest level with a 0.8 kg ha^-1 daily reduction rate. Pungsannamulkong showed the lowest yield when harvested using PE covering after cutting without rainfall treatment with a 3.4 kg ha^-1 daily reduction rate. The infected seed rate increased according to the harvest delay in both cultivars, and significant differences were observed according to rainfall treatment and harvesting method. The germination rate was maintained above 95% even after 40 days of delayed harvest if there was no rainfall treatment. However, with rainfall treatment, the germination rate was significantly lowered as harvesting time was delayed. In the field harvesting with rainfall treatment, the germination rate decreased to 77.2% for Daewonkong and 76.5% for Pungsannamulkong after 40 days of harvest delay. For the 100-seed weight, effects of individual treatments and interactions between treatments were not observed. In contrast, the effect of interactions between treatments on the shattering rate was significant in both cultivars, indicating that the shattering rate had the greatest impact on the yield changes during delayed harvest.

• Journal of Biosystems Engineering
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• v.7 no.1
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• pp.17-32
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• 1982

The binders introduced in Korea were originally designed to be used for Japonica-type varieties which have relatively long stem and are highly resistant to shattering. In order to use it for Tongil varieties which are short and easy to be shattered, mechanical modifications are necessary to reduce a grain loss incurred during binder operation. This study was intended to investigate analytically and experimentally the major sources of grain losses caused by three kinds of binders now introduced in Korea. Actual modification for each of three binders was done and experimentally compared to see if any improvement on grain loss was achieved. The results obtained in this study are summarized as follows; 1. It was required that the power transmission of binder should have a shifting mechanism so that velocities of pick-up and traveling units could be changed independently as desired according to the Japonica-type and Tongil varieties. In other words, the desired velocity of traveling unit should be obtained by shifting the transmission and the velocity of pick-up unit should be selected by reaping clutch according to the variety independent of the velocity of traveling unit as shown in Fig. 6. 2. To reduce grain loss it was desired that the moving parts of the pick-up unit should have the lowest possible velocities in harvesting Tongil varieties, unless the reduction of the speed be hindered the conveyance of the material. Based on the study, it was concluded that the velocities of pick-up unit be reduced by about 35% of those of the existing units. 3. It was found that the lug at the upper rotating section of pick-up case gave a severe impact on the ears of rice to increase grain loss. The optimum design of pick-up case to protect the ears from the protruding part of the lug was recommended by the result of analysis of the trajectory of the end-point of lug at the position. 4. It was proved analytically and experimentally that pick-up unit at the lower-rotating part was the other important source of grain loss in pick-up and divider assembly. In order to reduce a grain loss incurred by lugs at their lower-rotating section, it was suggested to improve it by (1) widening the space between right and left lower-rotating section, (2) shortening the length of lugs, (3) enlargement of the angle between the pick-up case and ground-level, and (4) attaching guard to right and left dividers so that the rotating lug could not give a high impact to the paddy hill. 5. Pick-up and divider assembly of the original binder of three models studied was modified according to the suggestions that were given by the preliminary study. Field test showed that the modified binders were able to reduce grain losses by about 0.4-0.7 percentage points compared to those without modification.

• Journal of Biosystems Engineering
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• v.3 no.1
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• pp.20-36
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• 1978

The effect of binder kicking forces on the shattering losses of paddy rice, which has been widely understood as an outstanding loss factor in harvesting with a binder, were experimentally assessed in this thesis.Through the field tests the optimum time of harvest, in terms of grain moisture contents, was found by considering harvesting losses for two rice varieties, harvested by two different binders, at four or five grain moisture levels.A device was designed and manufactured to apply various kicking forces to the bundles and was used in the bundle kicking tests. It was intended to find out the optimum range of kicking force to minimize the kicking losses. Based on the study, modification of the existing binder kicking mechanism was suggested. The following is a summary of the results of this thesis. 1. In Suweon 258 variety, as the grain moisture content is reduced, so the cutting loss and the kicking loss increase. The grain losses range from 0.77 to 0.82 percent of total field yield for the cutting loss, from 1.83 to 2.01 percent for the kicking loss, and from 2.60 to 2.83 percent for the field loss, when the moisture content is about 22 percent. 2. In Jinheung variety , the field losses increased as the grain moisture content decreased . When the moisture content was 20 percent, the field loss, cutting loss and kicking loss was 0.42-0.49 % , 0.30-0.35, and 0.12 -0.14% of the total field yield, respectively. 3. The difference in the field loss , cutting loss, and kicking loss for the two binders was 0.23% , 0.05% and 0.18% respectively in Suweon 258 variety, and 0.07% , 0.02% and 0.05% respectively ini Jinheung variety. The grain losses for binder B were slightly higher than those for binder A. 4. In the statistical analysis of each variety , the kicking force and the moisture content of the grain, and its interaction were all highly significant at 1% level by T test .The optimum kicking force was found to be in the 3.0-0.4kg range. This does not interrupt the binder operation, while ioses are kept to an acceptale level. 5. To reduce the kicking force of the eXlstmg binder mechanism, the speed of rotation of the kicking arm needs to be redued by increasing the number of driving sprocket teeth, and the position and gear ratio of the knotter-bill and driving bevelgear have to be change to give a !motter-bill speed of 1110 rpm. It is also desirable to attach a belt conveyor which smoothly carries the bundle to the ground. 6. The optimum harvesting time cased on maximum field yield was found to be at a grain moisture content of around 22 percent for Suweon 258 variety, and 20 percent for Jinheung variety. Tota] field yield and field yield at the time amounted to 9, 812.5 kg/ha, 9, 302. 5kg/ha respectively for the Suweon 258, and 7, 819.5 kg/ ha, 7, 158.7 kg/ha respectively for the Jinheung variety.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.5
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• pp.425-430
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• 1992

This experiment was carried out to collect the Korean red rices and to evaluate them as useful germplasm, 1,113 lines of weedy red rices were collected from farmer's field of the Korean peninsula from 1988 to 1991. The collected red rices were classified into two groups : One was long grain type with length /width ratio of 3.01$\pm$0.11 in paddy rice and the other was short grain type with length /width ratio of 2.28$\pm$0.12. Among the collected red rices 289 lines were long grain type and 824 lines were short. The red rices of long grain type were distributed in Nagdong and Seomjin river vallies of the southern part of the Korean peninsula, and the short ones were distributed all around of the peninsula. Among the collected long grain type red rices, 90.8% was red and 9.2% was white, and among the short grain type 88.8% was red, 10.6% was brown and 0.6% was white in pericarp color. 9.3% of the long grain type and 30.7% of the short grain type of the Korean red rices reacted to phenol solution. In the short grain type, 4.3% was waxy grained, but no waxy line was found in the long grain type. All the long grained Korean red rice showed easy shattering and no awn, however in the short grained red rices, 85.2% showed easy shattering and 49.6% was awned.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.65 no.2
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• pp.142-150
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• 2020

This experiment was conducted to set ideal harvest time for itallian ryegrass (IRG) seed in reclaimed land. For IRG 'Kowinearly' variety sown in both autumn and spring, the peak growth in reclaimed land occurred in 20-30 days after heading. Plant height of IRG seedings in the spring was 90.4% of the fall-sown's plants. The yield of IRG seeds in reclaimed land was generally lower than that of farm land due to poor growth conditions. After heading, the lodging and shattering increased gradually with time. The highest yield of seed in the fall-sown trial treatment was 238 kg/10a. However, in the spring-sown treatment, the highest yield reached 169 kg/10a, which was 71% that of the fall-sown treatment. To set optimum harvesting time for IRG seed, morphological changes in the plant, moisture content of seed, and germination rate were analyzed according to time series after heading. After heading, IRG stem color had turned pink in 18 days and seed color also changed after 20 days. Following 20-25 days after heading, the seed moisture content decreased to below 55% and germination rate increased to over 90%. Therefore optimum harvesting time for IRG 'Kowinearly' variety in reclaimed land was 20-30 days after heading because germination rate and yields were high and shattering percentage was low.

• Journal of The Korean Society of Grassland and Forage Science
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• v.19 no.2
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• pp.127-132
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• 1999

No comprehensive study of yield and quality losses of forage legumes harvested and cured in spring has been conducted in Korea, therefore, this experiment was carried out to gain information on yield and quality, losses of alfalfa(Medicgo sativa L.), crimson clover (Trifolium incarnatum L.), and red clover(Trifolium pratense L.) during field curing in spring(mid-May). Alfalfa was highest in dry matter content of 15% at harvest, while crimson clover and red clover had 12.4 and 11.5%, respectively. Species differences for the dry matter content were maintained and consistent trends were observed during the field curing. Alfalfa took seven days to reach dry matter content over 80%, while both crimson clover and red clover took eight days. Crimson clover and alfalfa tended to show a higher leaf-stem ratio than red clover based on dry matter, but red clover showed a higher leaf-stem ratio than alfalfa and crimson clover based on crude protein content. Losses in dry matter of alfalfa from leaf shattering were higher than crimson clover and red clover, and similar trends were detected losses in crude protein for three different legumes. Fresh legume forages averaged higher in clude protein(CP), total digestible nutrients(TDN), and relative feed value(RFV), while dry legume forages averaged lower in acid detergent fiber(ADF) and neutral detergent fiber(NDF). Results of the experiment indicate that hay curing in spring affects crude protein concentration more than ADF and NDF, and this is due, in part, to leaf shattering caused by field operations.