• 한국어업기술학회:학술대회논문집
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• 한국어업기술학회 2000년도 춘계수산관련학회 공동학술대회발표요지집
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• pp.327-327
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• 2000

In the 1990's several economically important marine fisheries collapsed or showed signs of extreme hardship owing to overcapitalization and excessive fishing pressure on the resources. Public concern was raised and demands voiced for more prudent fishery management practices. The United Nations responded and developed international guidelines, such as the FAO Code of Conduct for Responsible Fishing and the UN Straddling Fish Socks and Highly Migratory Fish Stocks Agreement These guidelines task fishery managers to take prudent steps to ensure the long-term viability of fisheries and fishery resources. Included in the guidelines are two particular demands that will challenge stock assessment scientists in the new millennium. They are application of the precautionary approach and the inclusion of ecological considerations in assessments and management advice. High-lighted in the presentation are examples from the central-western Pacifi skipjack tuna fishery and the eastern Pacific thresher shark fishery where insufficien information is affecting stock assessments. The shortcomings are further linked t the new challenges of applying the precautionary approach, such as reference points, and ecological considerations, such as predator-prey and oceanographic-regime shift.(omitted)

• Journal of Biosystems Engineering
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• 제4권2호
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• pp.10-24
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• 1979

It is understood that drum speed of threshers and the moisture content of paddy grains to be threshed, respectively, have a signific:mt effect upon rice recoveries. Threshing under an increased drum speed would give a high performance rate, which is the general practice in custom work threshing in association with the use of semiauto-t hreshers. In the connection, however, it may result in the promotion of grain cracks and brokens of the rice product after milling. No reference or determination for an opti mum drum speed of the thresher is made available for various grain moisture contents at the time of the threshing operation and for different rice varieties especially for the Tongil rice varieties. This study was Conducted to find out and determine effects of the drum speeds on grain losses. The grain loss was quantified in terms of recovery rates of rice grains after treatments. Samples of each of all treatments were taken from the grain sampling plate placed in the grain conveyor of threshers. The grain sample plate was specially provided for this experiment. The brown-rice, milling, and head-rice recJveries were tes ted in the laboratory mill, respectively. Two rice varieties, Akibare and Suweon 251, each with five levels of different moist\ulcornerure contents at harvest and six levels of different drum speeds of threshers, were selected and used for treatments in this experiment. Two conditions of materials were tested in the thresher. One condition was to thresh the experimental material immediately after cutting, referred to as the wet-material thr eshing in this study. The other was to thresh the experimental :material, dried to contain about 15-16 percent of the grain moisture under the shocking operation. This is referred to as the dry-material threshing in this study. In additioon, field measurements for the grain moistures and drum-sdeeds under actual operation practices of the traditional field threshing, were conducted with a view to comparing with results of the experimental treatments. The results of the study may be summarized as follows: 1. For threshing treatments of Japonica-type rice variety (Akibare) , the effect of drum speeds and levels of grain moisture at cutting upon brown-rice, milling, and head-rice recoveries were found statistically significant. No significant difference in these recovery rates was noticed regardless of whether the material was threshed right after cutting or after drying by the shocking operation. 2. For the Tongil-sister rice variety(Suweon 251), milling recovery for the varied drum-speed and the grain~moisture level at cutting was found statististically significant. Th milling recovery was much significant when associated with the wet-material thres\ulcornerhing compared to the dry-material threshing. 3. The optimum peripheral velocity to be maintained at the edge of teeth on the thr\ulcorneresher drum was determined and may be recommanded as that of about 12 to 13 meters per second in view of the maximum recovery rate of the milled rice. 4. The effect of the drum speed on the qualitative loss of the milled rice was much greater in the case of the Tongil variety than Japonica. This effect was also greater by the wet-material threshing than by the dry-material threshing. Therefore, to apply the wet-material threshing operation for the Tongil variety, in particular, it should be very important to introduce the kind of threshing technology which would maintain the drum speed at optimum. 5. A field survey for the actual drum speed of threshing operations for 50 threshers indicated that average peripheral velccity was 12.76m/sec., and that the range was from 10.50 to 14.90m/sec. Approximately, more than 30% of the experimented and measured threshers were being operated at speeds which exceeded the optimum speed determined and assessed in this study. Accordingly, it should be highly desirable and important to take counter-measures against these threshing practices of operational overspeed.

• Journal of Biosystems Engineering
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• 제4권2호
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• pp.9-9
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• 1979

It is understood that drum speed of threshers and the moisture content of paddy grains to be threshed, respectively, have a signific:mt effect upon rice recoveries. Threshing under an increased drum speed would give a high performance rate, which is the general practice in custom work threshing in association with the use of semiauto-t hreshers. In the connection, however, it may result in the promotion of grain cracks and brokens of the rice product after milling. No reference or determination for an opti mum drum speed of the thresher is made available for various grain moisture contents at the time of the threshing operation and for different rice varieties especially for the Tongil rice varieties. This study was Conducted to find out and determine effects of the drum speeds on grain losses. The grain loss was quantified in terms of recovery rates of rice grains after treatments. Samples of each of all treatments were taken from the grain sampling plate placed in the grain conveyor of threshers. The grain sample plate was specially provided for this experiment. The brown-rice, milling, and head-rice recJveries were tes ted in the laboratory mill, respectively. Two rice varieties, Akibare and Suweon 251, each with five levels of different moist?ure contents at harvest and six levels of different drum speeds of threshers, were selected and used for treatments in this experiment. Two conditions of materials were tested in the thresher. One condition was to thresh the experimental material immediately after cutting, referred to as the wet-material thr eshing in this study. The other was to thresh the experimental :material, dried to contain about 15-16 percent of the grain moisture under the shocking operation. This is referred to as the dry-material threshing in this study. In additioon, field measurements for the grain moistures and drum-sdeeds under actual operation practices of the traditional field threshing, were conducted with a view to comparing with results of the experimental treatments. The results of the study may be summarized as follows: 1. For threshing treatments of Japonica-type rice variety (Akibare) , the effect of drum speeds and levels of grain moisture at cutting upon brown-rice, milling, and head-rice recoveries were found statistically significant. No significant difference in these recovery rates was noticed regardless of whether the material was threshed right after cutting or after drying by the shocking operation. 2. For the Tongil-sister rice variety(Suweon 251), milling recovery for the varied drum-speed and the grain~moisture level at cutting was found statististically significant. Th milling recovery was much significant when associated with the wet-material thres?hing compared to the dry-material threshing. 3. The optimum peripheral velocity to be maintained at the edge of teeth on the thr?esher drum was determined and may be recommanded as that of about 12 to 13 meters per second in view of the maximum recovery rate of the milled rice. 4. The effect of the drum speed on the qualitative loss of the milled rice was much greater in the case of the Tongil variety than Japonica. This effect was also greater by the wet-material threshing than by the dry-material threshing. Therefore, to apply the wet-material threshing operation for the Tongil variety, in particular, it should be very important to introduce the kind of threshing technology which would maintain the drum speed at optimum. 5. A field survey for the actual drum speed of threshing operations for 50 threshers indicated that average peripheral velccity was 12.76m/sec., and that the range was from 10.50 to 14.90m/sec. Approximately, more than 30% of the experimented and measured threshers were being operated at speeds which exceeded the optimum speed determined and assessed in this study. Accordingly, it should be highly desirable and important to take counter-measures against these threshing practices of operational overspeed.

• 한국작물학회지
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• 제31권2호
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• pp.150-155
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• 1986

콩을 탈곡기로 탈곡할 때 종실손상율이 낮으면서 발아율이 높은 종실의 수분함량과 탈곡기의 적정 급동속도를 구명하여 기웅탈곡시에 필요한 기초자료로 활용코자 시험을 실행하여 얻어진 결과를 요약하면 다음과 같다. 1. 성숙시 식물체 각 부위별 수분함량은 대입종인 황금콩의 경우 줄기, 종실, 콩깍지 순으로 소입종인 단엽콩은 줄기, 콩깍지, 종실 순으로 많았다. 2. 황금콩과 단엽콩의 성숙후 식물체 부위별 수분함량과 수분함량 감소정도는 줄기 및 종실에서는 비슷하였으나 콩깍지는 소입종인 단엽콩이 성숙후 7 일까지는 황금콩보다 높았고 그 후에는 차이가 없었다. 3. 성숙후 7 일의 일중의 줄기, 종실, 콩깍지의 수분함량 변이는 시간이 경과함에 따라 수분함량이 감소하는 경향이며 성숙후 14일에는 오전 11시까지 꼬투리의 수분함량이 종실의 수분함량보다 높았으나 그 이후에는 종실의 수분함량이 더 높았다. 4. 콩 탈곡시 탈곡기의 급동속도가 빨라지거나 종실수분함량이 많아질수록 종실보상율은 증가는 경향이며 대입종인 황금콩이 소입종인 단엽콩보다 종실 보상입율이 높았다. 5. 보상입율과 발아율을 고려할 때 탈곡기의 적정급동속도는 11 m/sec.가 적당한 것 같았다. 6. 탈곡에 알맞는 종실의 수분함량은 수량, 보상입율, 발아율, 작업속도 및 건조작업 등을 고려할 때 종실의 수분함양이 15∼20%가 적당한 것 같았다.

• Journal of Biosystems Engineering
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• 제26권1호
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• pp.11-20
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• 2001

Experiments under the stationary and harvesting condition, were performed in order to investigate the vibration characteristics of a head-feeding combine. 6 degrees of freedom components of acceleration at the location of the center of the gravity, and 3 degrees of freedom components of acceleration at the location of the operator seat were measured independently. The vibration characteristics of the combine were estimated with the power spectral density of the time series data of accelerations. From this research, the following results were obtained. 1. Vibration of a head-feeding combine under the stationary condition(engine, thresher and cutter are driven without harvesting) is mainly influenced by the engine. Further, 1/3, 1/2 (sub-harmonic) frequency components of the engine are observed besides engine driving frequency component(45Hz). 2. Vibration of a head-feeding combine under the harvesting condition is influenced by the engine, threshing unit and driving unit. Namely, some kinds of vibration frequency components in harvesting are observed compared with stationary condition. Further, sub-harmonic frequency components of the engine are observed besides engine driving frequency component as same as stationary condition. From these results, it may be concluded that vibration of a head-feeding combine is characteristics of semi-periodic and nonlinear vibration.

• Journal of Biosystems Engineering
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• 제43권3호
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• pp.194-201
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• 2018

Purpose: The objective of this study was to propose a formula for the theoretical grain mean transport velocities of an elliptically moving oscillator by modifying the grain mean transport velocity formula applied to linear motion and to compare the calculated values with the experimental values of grain mean transport velocity. Methods: The values of the throwing index ($K_v$) and the maximum horizontal velocities for various positions on the elliptical oscillator were obtained using kinematic analysis. To obtain the actual grain transport velocity, the mean transport velocities of perilla grains at six positions on the sieve surface were measured using a high-speed camera and compared with the theoretical values. The cam with an eccentric bearing on the oscillator was designed to be eccentric by 1.6 cm so that the lengths of the major axis of the elliptical motion were 3.2-3.6 cm. The material used in the experiments was perilla grain. Results: The experimental result was consistent with the theoretical value calculated using the proposed formula ($R^2$ is 0.80). It is considered that the angle difference between the maximum accelerations in the directions vertical and horizontal to the sieve has as much influence on the grain mean transport velocity as the value of Kv itself. Conclusions: It was possible to theoretically obtain the grain mean transport velocities through a screening device in elliptical motion by modifying the formula of the grain mean transport velocities used in linear motion.

• Journal of Biosystems Engineering
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• 제10권2호
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• pp.36-46
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• 1985

This study was intended to develop the mathematical model of the head-fed type threshing unit. As the first step, the physical model of the threshing phenomena was considered to consist of four separate processes as 1) detachment process of grains, 2) movement of grains between the cylinder and concave, 3) grain penetration through stems of bundle, and 4) grain passing through concave. The mathematical and computer models were developed based on the physical models. Threshing experiments were performed and determined the distribution of grain accumulation along the cylinder shaft by varying the moisture content of grains, feeding rate, and cylinder speed. It was found that the model developed coincided very well with the experimental results for the varied operational conditions. Greater concentration of grains passing through concave toward the thresher inlet was equally true for the model and experiment work for the threshing of grains with higher moisture content and with higher cylinder-speed. The model could be used for obtaining the optimized design or for optimizing the performance of the head-fed type threshing unit if term as to power requirement for threshing may be additionally included in the developed model.

• Journal of Biosystems Engineering
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• 제41권4호
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• pp.294-303
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• 2016

Purpose: This study aimed to evaluate the profitability of four selective mechanization systems in rice cultivation. Methods: Field experiments were conducted in the farmers' field during the wet season (June to November) of 2015 in Bangladesh. Mechanization systems were applied to evaluate four different selective levels (treatment) in eleven consequent operations. Seedlings were raised in a traditional seedbed and trays for manual and mechanical transplanting, respectively. Land preparation, irrigation, fertilizer, pesticide, carrying, and threshing and cleaning operations were performed using the same method in all the experimental plots. The mechanical options in the transplanting, weeding, and harvesting operations were changed. The mechanization systems were $S_1$ = hand transplanting + hand weeding + harvesting by sickle, $S_2$ = mechanical transplanting + Bangladesh Rice Research Institute (BRRI) weeder + reaper, $S_3$ = mechanical transplanting + BRRI power weeder + reaper, and $S_4$ = mechanical transplanting + herbicide + reaper. This experiment was performed in a randomized complete block design with four replications. Power tiller, rice transplanter, BRRI weeder, BRRI power weeder, self-propelled reaper, BRRI open drum thresher, and BRRI winnower were used in the respective operations. Accordingly, the techno-economic performances of the different technologies were calculated and compared with those of the traditional system. Results: The mechanically transplanted plot produced 6-10% more yield than the hand transplanted plot because of the use of tender-aged seedlings. Mechanical transplanting reduced 61% labor and 18% cost compared to manual transplanting. The BRRI weeder, BRRI power weeder, and herbicide application reduced 74, 91, and 98% labor, respectively. The latter also saved 72, 63, and 82% cost, respectively, compared to hand weeding. Herbicide application reduced the substantial amount of labor and cost in the weeding operation. Mechanical harvesting also saved 96% labor and 72% cost compared to the traditional method of harvesting using sickle. Selective mechanization saved 15-17% input cost compared to the traditional method of rice cultivation. Conclusions: Mechanical transplanting with the safe use of herbicide and harvesting by reaper is the most cost- and labor-saving operation. The method might be the recommended set of selective mechanization for enhancing productivity.

• 한국작물학회지
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• 제36권1호
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• pp.65-69
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• 1991

과맥에서 종자활력의 저하요인을 구명하고자 과맥 2계통(피, 과 isogenic line포함) 및 피맥 1품종의 종자의 수발아를 유도하여 손과 기계탈곡(700 rpm ) 한 종자를 이용하였다. 1. 수발아된 종자를 손 탈곡하여 배부분의 손상이 없어서 발아세, 발아율, TTC치은 수발아 정도에 따른 차이가 적었으나, 출아력은 수발아가 클수록 감소되었다. 2. 수발아된 종자는 기계탈곡시 배의 부분적인 손상이 관찰되었으며, 손 탈곡에 비해서 종자활력에 관계된 형질들이 고도로 유의적인 감소를 가져왔고 효소활력은 크게 증가되었다. 3 손 탈곡구에서 수발아 정도는 효소활력 ( r =0.9 31＊＊, 0.951＊＊) 및 발아력 ( r=0.46＊)과 정상관이 있었다.

• 한국작물학회지
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• 제38권1호
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• pp.46-54
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• 1993

최근 육성된 내한성이며 찰쌀보리인 품종들이 확대 보급을 통하여 재배지대의 북상과 수량에 대한 안정성을 제고시키기 위하여 찰과, 찰피, 메과 및 메피성의 isogenic line을 이용한 찰ㆍ메 및 피ㆍ과성인자가 발아 및 출현률에 미치는 영향을 검사한 결과는 다음과 같다. 1.수확 전일 강우시는 피성에 비하여 과성의 발아율이 4-6% 낮았으며, 5일 인공강수처리에서는 과성의 발아율로 현저히 저하되었다. 2. 탈곡기회전속도가 600rpm에서 1000rpm으로 상승할 때 피성의 발아율이 100%에서 90%로 저하되었으나, 과성은 98%에서 76%로 크게 저하되었다. 3. 과성에서 발아율보다 출현률이 피성에 비하여 큰 차이가 있었으며 파종심도가 깊을수록 그 차이가 컸다. 4. 파종심도, 고탈곡회전수가 수확시의 강우순으로 피성보다 과성의 출현율은 크게 저하되었다. 5. 탈곡시 찰성배유유부자에 따른 쌀보리의 배손상정도와는 관련이 없었으며, 6. 탈곡시 배의 손상은 겉보리는 영에 의한 보호로 적었으나 영의 보호가 없는 쌀보리는 컸다. 7. 탈곡시 탈곡시의 회전수를 600, 900rpm으로 탈곡만 하거나 또는 탈곡후 탈망회전속도를 750rpm으로 탈망한 종자의 손상입률 및 발아율은 겉보리는 큰 영향이 없었으며, 쌀보리는 매우 높아 채종시 주의가 필요하다. 8. 수발아율은 찰성인자 도입시에는 메성에 비해 높았으나 과성인자 도입시에는 차이가 없었다. 9. 과맥의 출현률 향상을 위하여는 수확후 강우피해를 방지하고 탈곡시 회전속도를 낮추며 파종심도를 적절히 조절하여 찰성인자 도입시에는 등숙과 정중 휴안성이 낮아 수발아률이 높은 점을 고려한 육종적 조치를 하여야 찰과성 품종의 육성보급시 재배면적의 북상 및 확대를 기하고 수량의 안정성을 제고할 수 있다.