• Journal of Biosystems Engineering
• /
• 제11권2호
• /
• pp.55-65
• /
• 1986

The resistance to the passage of airflow through various agricultural products is an important consideration in the design of an aeration or drying system. The amount of resistance to airflow varied widely from one kind of grain to another, and depended upon airflow rate, surface texture and shape of the particles, the size and configuration of voids, and foreign and fine material in the grain bed. The airflow rate was the major factor considered on this kind of study in the early stages. But these days, the studies on the resistance to airflow of grain affected by grain moisture content and foreign and fine material have been widely carried out. However the foreign an fine material in the grain bed could not be a major factor on the study in Korea because there were only a few grain process procedure after harvesting it. The objectives of this study were to investigate the effect of moisture content and airflow rate on airflow resistance to grain, and to develop a model to predict the static pressure drop across the grain bed as a function of moisture content and airflow rate. The rough rice varieties, Akibare, Milyang 15 (Japonica types), Samkwang, Backyang (Indica types)and covered barley variety, Olbori, which were harvested in 1985 were used in the experiment after cleaning them. Resistances to airflow of grain were investigated at four levels of moisture content (13-25%, wb.) for ten different airflow rates($0.01-0.15m^3/sm^2$). The results of this study are summarized as follows; 1. Theaverage bulk densities were $585.3kg/m^3$ for rough rice and $691.6kg/m^3$ for barley at the loose fill, and were $648.8kg/m^3$ for rough rice and $758.2kg/m^3$ for barley at the packed fill. The pressure drops at the packed fill beds were approximately 1.4 to 1.8 times higher than those at the loose fill beds. 2. The pressure drops across grain beds deceased with the increase of moisture content and increased with airflow rate. The decreasing rates of pressure drop across grain beds according to the moisture contents at the lower airflow rates were higher than those at the higher airflow rates, and the increasing rates of pressure drop according to the airflow rates at the lower moisture contents were higher those at higher moisture contents. 3. The pressure drop across barley bed were much higher than rough rice beds and the pressure drops across Japonica type rough rice beds were a little higher than Indica type. 4. The mathematical models to predict the pressure drop across grain beds as a function of moisture content and airflow rate were developed from these experiments.

• 한국전기전자재료학회논문지
• /
• 제33권4호
• /
• pp.255-262
• /
• 2020

Grain boundaries play a major role in determining device performance, particularly of polysilicon-based photodetectors. Through the post-annealing of as-deposited polysilicon and then, the analysis of electric behavior for a metal-polysilicon-metal (MSM) photodetector, we were able to identify the influence of grain boundaries. A modified model of polysilicon grain boundaries in the MSM structure is presented, which uses a crystalline-interfacial layer-SiO_x layer- interfacial layer-crystalline system that is similar to the Si-SiO₂ system in MOS device. Hydrogen passivation was achieved through a hydrogen ion implantation process and was used to passivate the defects at both interfacial layers. The thin SiO_x layer at the grain boundary can enhance the photosensitivity of an MSM photodetector by decreasing the dark current and increasing the light absorption.

• Current Research on Agriculture and Life Sciences
• /
• 제14권
• /
• pp.37-47
• /
• 1996

The main objectives of this studies are to present the most desirable rice processing complex model system in a given our situations by comparision and analyzing the major factors and, also recommend the future prospect of the rice processing complex in Korea. There are 3 different rice processing complex models in Korea. Those are concrete bin, flat type steel bin and square bin. These systems have a lot of differences and have their own characteristics such as capital requirement, efficiency, storage capacity and quality controls. The major problems of the existing rice processing centers in Korea are high fixed cost and the unbalnced systems. Following is summary to solve this problems: 1. Development of the large scale harvester and high speed continuous dryer. 2. Quality inspective system of bulk grain and large scale temporary storage facilities. 3. Large size readjustment of arable land. 4. Select the convenient location of rice processing center and formulation of well equipment facilities.

• Journal of Animal Science and Technology
• /
• 제61권1호
• /
• pp.18-27
• /
• 2019

With South Korea's limited capability of feed production because of its relatively small cultivable area, the country is pushed to depend on foreign feed imports despite the immensely fluctuating price of corn. Hence, intensive efforts to increase the total cultivable area in Korea like extending of farming to mountainous area is being practiced. Corn was planted in Goesan County, a mountainous area in the country. Grain and stover were harvested separately in three harvest periods: early-harvest (Aug 8), mid-harvest (Aug 18), and late-harvest (Aug 28). The nutrient composition such as dry matter (DM), crude protein (CP), crude fat (EE), organic matter (OM), neutral detergent fiber (NDF), acid detergent fiber (ADF), and non-fibrous carbohydrates (NFC) was determined after harvest. Effective degradability (ED) of the major nutrients (DM, NDF, ADF, and CP) were measured through in vitro fermentation of rumen fluid from Hanwoo (Korean cattle). pH, ammonia-N concentration, volatile fatty acid (VFA) concentration, and gas production were periodically measured at 0, 3, 6, 12, 24, 48, and 72 h. Corn grain showed higher nutrient content and ED than stover. It also had higher gas production but its pH, ammonia-N, and total VFA concentration were lower than corn stover. The best nutrient composition of corn grain was observed in early-harvest (high CP, EE, NDF, OM, NFC, and low ADF). Early-harvest of corn grain also had high effective degradability of dry matter (EDDM), effective degradability of neutral detergent fiber (EDNDF), effective degradability of acid detergent fiber (EDADF), and total VFA concentration. On the other hand, the best nutrient composition of stover was observed in mid-harvest (high DM, CP, NDF, and low ADF). EDDM, EDNDF, and EDADF were pronounced in early-harvest and mid-harvest of stover but the latter showed high total VFA concentration. Hence, early and mid-harvested corn stover and grain in a mountainous area preserved their nutrients, which led to the effective degradation of major nutrients and high VFA production.

• 한국지구과학회지
• /
• 제34권4호
• /
• pp.289-302
• /
• 2013

대부분 니질 퇴적물로 구성된 황해 남동부 흑산니질대 퇴적물의 기원지를 밝히기 위해 퇴적물 시료에 대해 주성분 원소와 희토류 원소(REE)를 분석하였다. 표층 퇴적물 시료는 흑산니질대 내 51지점에서 피스톤식과 박스형 시료 채취기로 획득하였다. 흑산니질대의 표층퇴적물은 니 퇴적물이 우세하게 나타나며, 평균입도는 $5-6{\phi}$이다. 공간적으로 북쪽지역은 실트함량이 높고, 남쪽지역으로 갈수록 점토함량이 증가한다. 흥미롭게도 주성분 원소와 희토류 원소 함량 특성은 퇴적물 기원 해석에 있어 다른 결과를 가져왔다. Fe/Al과 Mg/Al 함량 비, $Al_2O_3$와 MgO 함량 비, $Al_2O_3$와 $K_2O$를 각각 도시한 결과, 흑산니질대 퇴적물은 한국 기원의 퇴적물이 우세한 것으로 나타났다. 하지만 희토류 원소의 특성은 중국 기원의 퇴적물이 우세함을 반영한다. 이러한 기원 불일치는 각 원소의 함량 조절요인이 다르기 때문이다. 주성분 원소는 입도와 높은 상관관계를 고려할 때 입도에 따라 그 함량이 영향을 받는 것으로 해석된다. 반면에 희토류 원소는 입도와는 상관관계가 낮으며, 중광물 함량에 의해 조절되는 것으로 사료된다. 이와 같이, 각기 다른 추적자에 따른 기원의 불일치를 해결하기 위해 추가적인 연구가 필요하다.

• Journal of Biosystems Engineering
• /
• 제43권3호
• /
• pp.194-201
• /
• 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
• /
• 제4권2호
• /
• pp.32-45
• /
• 1979

The major objective of this study was to develope a computer simulation model to analyze drying process in a deep bed with natural air. The approach used to describe the continuous drying process in a deep bed was to divide the process into many small processes and simulate them by consecutively calculating the changes of grain and air conditions that occurred during short increment of time. Success criterion of the drying system was based on grain deterioration estimated by drymatter decomposition during drying. The results of the experimental test showed that the model satisfactory.

• Journal of Biosystems Engineering
• /
• 제3권1호
• /
• pp.33-46
• /
• 1978

To get the goal of self-supply of food grain, improvement of post-harvest grain operations in rural area is under consideration as an important task of agriculture in Korea. This is study is focused on elimination of losses and deteriorations of grain and reduction of labour requirements and funds for post-harvest grain operations. The purpose of this study are presentation of basic data referring to conventional post-harvest grain operations in rural area and suggestion of improving methods for the operations, and also finding out reasonable operating processes of the operations. The result of this study are follows; 1. Grain drying in-the-filed which is performed before threshing has major factors of grain loss during drying, and so should be restrained as possible. Combine harvesting system is recommended among other king of mechanized harvesting systems for restraining in-the-field drying and securing available labors for drying. 2. It is predicted that mechanical grain drying could be prevalent when combine harvesting is taken place. Recommended grain drier for pre-combine harvesting system and for combine harvesting system is batch-type drier and circulating -type drier, respectively. 3. As existing farm storages for grain have insufficient spaces and offer poor conditions for grain storing , it is greatly needed to build up new storage which store only grains. And it is concluded that storing grain in community common storages in desirable. 4. Power supplying system for milling machinery in local milling plants, that a large capacity prime mover supplies power to 4 to 6 kinds of milling machinery simultaeously, should be converted to a system of several small capacity prime movers supplying power to each machiner y for the purpose of reducing extra consumption of energy. 5. Governmental grain, of which Korean farms produced, should be milled and stored in the local milling plant successively for the purpose of reducing transportation fee and stroing facilities. 6. Furture post-havest grain operations-drying, storing and milling should be periormed successively in he community common plant. And average optimum processing capacity of the plant is estimated about 300 metric ton of grain every year.

• 대한영양사협회학술지
• /
• 제20권2호
• /
• pp.133-148
• /
• 2014

This study compared levels of whole grain consumption-related predisposing, reinforcing, and enabling factors according to socio-demographic variables, and examined how these factors are associated with whole grain consumption frequency among Korean adults. A survey questionnaire was administered to a convenience sample of adult males and females aged 20~59 years (n=300). The questionnaire included questions on predisposing, reinforcing, and enabling factors in relation to whole grain consumption as well as a brief whole grain food frequency questionnaire. Female subjects showed a significantly higher level of negative beliefs on health nutrition taste texture while showing a significantly lower level of social support compared to that of males. The age group of 40~59 years showed a significantly higher social support level than the age group of 20~39 years. Results from multivariate regression analyses showed that different combinations of predisposing, reinforcing, and enabling variables were significant in predicting whole grain consumption frequency according to sex and age. The study findings can be used for developing specific target-oriented nutrition intervention programs for promotion of whole grain intake among Korean adults.

• 한국세라믹학회지
• /
• 제31권8호
• /
• pp.849-860
• /
• 1994

The microstructural evolution and crystalline phases of this infiltration of Ti+Al liquids in TiC, SiC, TiC+C, and SiC+C preforms have been investigated. As the Ti and Al mixing ratio in Ti+Al infiltrated liquid changes, the newly formed reaction products, which were reacted from the Ti+Al liquid with preforms, consisted of three major phases as Ti3AlC, Al2Ti4C2 or Al4C3. The TiC grain shape was changed to spheroid, when Ti3AlC was formed. In case of Al2Ti4C2 formation, the platelet grain was formed from the original TiC grain. When Al4C3 was formed, nodular or intergranular fine-grained Al4C3 was formed around the TiC grain, while the original TiC grain shape was not changed.