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신예미 광산 철광석의 볼밀 분쇄 및 단체분리 특성 연구
이돈우,권지회,김관호,조희찬,Lee, Donwoo,Kwon, Jihoe,Kim, Kwanho,Cho, Heechan 한국자원리싸이클링학회 2020 資源 리싸이클링 Vol.29 No.3
This study aims to investigate breakage and liberation characteristics of iron ore from Shinyemi mine, Jeongseon by ball mill. Parameters of breakage functions for three grade samples of iron ore were obtained using single-sized-feed breakage test and back-calculation based on nonlinear programming. The results showed that with the increase in the grade of iron ore, the breakage rate factor decrease whereas the particle size sensitivity decreases. This results from retardation of microcrack-propagation by magnetite grain in the ore. Breakage distribution analysis showed that the breakage mechanism appear to be impact fracture dominant with the increase of grade owing to the stress distribution effect by magnetite grain. Degree of liberation (DOL) increased with the increase in grade and decrease in particle size, respectively. Using the breakage function and size-DOL relationship, a model that can predict time-dependent-DOL is established. When scale-up factors from operating condition are available, the model is expected to be capable of predicting size and DOL with time in actual mining process.
李敦宇 順天大學校 1984 論文集 Vol.3 No.1
1. In this experiment, 20 Havard commercial broiler chicks, were fed 56days for the pupose testing their growing rate and feed efficiency after 3-day fasting of an each different treatment. This test resulted in followings; The rearing rate showed 90% in fasting treatment after hatching (lot2) 2. 56days body weight showed the rate of 2.030g in lot1, 1.780g in lot2, 1.815g in lot3, 1.870g in lot4 respectively. 3. And then the fasting efficiency showed the severe tendency in after hating (lot2), the high signitcant tendency (P>0.01) was turned out in each fasting treatment as well. 4. The feed efficiency showed the rate of these orders of lot>lot3>lot2 which represents the state of reverse rate in comparison with growing rate. 5. The experiments as the above are only a part of process in researching factors. I hope to continue to study the each different factor or some others in order to carryout the above projects.
케이블 기반 개폐 막 지붕의 원통형 최적 트롤리 모델의 개발
이돈우,손수덕,이승재,Lee, Don-Woo,Shon, Sudeok,Lee, Seungjae 한국공간구조학회 2020 한국공간구조학회지 Vol.20 No.4
This study examines the optimum shape of a trolley, the driving device of the retractable membrane roof. The closed-type trolley was determined as the model of the study, and a trolley composed of cylindrical-shaped inner and outer holders was selected as the basic model. Based on this model, a cylindrical-based optimal trolley model was proposed. In the basic trolley model, steel was used for the outer holder, and steel, titanium, and aluminum were used for the inner holder. In each case, the most economical shape for the external load of the basic model was newly proposed through the topology optimization process, and the finite element analysis results of the proposed model were compared to define the durability and economics. Here, topology optimization analysis and finite element analysis used the commercial software ANSYS. As a result of optimization, the volume of the outer holder of the trolley was reduced by 58.2% and the volume of the inner holder was reduced by 25.0% compared to the basic model. In the case of stress, a stress increase of 43.2 to 79.2% occurred depending on the material of the inner holder, but it was found to be significantly lower than the yield strength, thereby ensuring safety.
용접형과 무용접형 하지철물의 수평변위 추종능력에 관한 연구
이돈우,곽의신,손수덕,이승재,Lee, Don-Woo,Kwak, Eui-Shin,Shon, Su-Deok,Lee, Seung-Jae 한국공간구조학회 2016 한국공간구조학회지 Vol.16 No.4
Building hardware joints are welded in most cases, which have risks of fire and explosion. Besides, the secondary damage of the destruction of the welded parts can be caused by the horizontal displacement of the structure due to earthquake or wind load. This paper compared the horizontal displacement following abilities of welded building hardware and non-welded building hardware. To do this, We conducted actual formation shake table test, and checked on the horizontal displacement following ability of structure by comparing their responses to earthquake load. We made the 2m-high framework to examine the responses of the actually constructed building hardwares, and analyzed the displacement responses of the welded-typed, non-welded-typed, and cruciform bracket building hardwares. We conducted the test by increasing acceleration rate until displacement reached 40mm corresponding to allowable relative story displacement II. The result of the test showed that the building hardware using welding work made cracking and breakage on welded connections of welded building hardware, but non-welded building hardware with no use of welding work and cruciform bracket building hardware make no problem, and that non-welded building hardware is superior to that of the welded building hardware in the horizontal displacement following ability due to earthquake or wind load.
무기태 인산제의 이용성에 관한 연구 5 . MAP 와 다른 사료용 인산제의 종류와 첨가수준이 육계의 성장 , 영양소이용율 , 혈액 및 경골성분에 미치는 영향
이돈우(D . W . Lee),오희정(H . J . Oh),한인규(I . K . Han),하종규(J . K . Ha) 한국축산학회 1987 한국축산학회지 Vol.29 No.5
Feeding and metabolic trials were conducted to study effects of source and level of dietary phosphorus on the growth rate, nutrient utilizability, blood and bone mineral compositions of broiler chicks. Phosphorus sources used were monoammonium phosphate (MAP), bone meal (BM), dicalcium phosphate (DCP) and tricalcium phosphate (TCP). Dietary phosphorus levels were 0.3(VL), 0.5(L), 0.7(0), 0.9(H) and 1.1%(VH), which were achieved by adding different levels of DCP. Results obtained are summarized as follows: 1. Adding BM as a dietary phosphorus source resulted in slightly better growing performance and nutrient utilization without statistical significance. Dietary phosphorus did not influence, the levels of serum Ca and P. However, bone Ca and P levels in chicks fed BM were much higher (P$lt;0.05) than those fed other phosphorus sources. 2. Optimum level of dietary phosphorus (0.7%) gave the best result in growth rate, nutrient utilization and bone calcification. Extreme phosphorus levels (0.3% and 1.1%) resulted in poor growing performance and nutrient utilization when compared with other three medium levels of dietary phosphorus (0.5, 0.7 and 0.9%).