• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2005.12a
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• pp.22-30
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• 2005

1. 톱밥발효돈분으로 생산된 분립의 첨가시 벼의 생육에 미치는 영향 2)육묘용 pot 바닥의 분립무처리구에서 추정벼가 0%-20%, 흑미벼에서는 0%-10% 의 혼합비율에서 식물체의 생육이 양호하였지만, 그중에서도 이 품종 모두 5%분립혼합구가 가장 생육이 양호하였다. 3) 육묘용 pot 바닥의 분립처리구에서는 추정벼와 혹미벼 모두 0%-5% 혼합비율에서 식물체의 생육이 양호하였다. 4) 이상의 결과로부터 육묘용 상토에 분립 5%를 첨가하는 것이 식물체의 생육을 촉진시켰다고 판단된다.

• Proceedings of the Korean Society of Organic Agriculture Conference
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• 2005.12a
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• pp.31-36
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• 2005

1. 버섯폐배지로 생산된 분립의 첨가시 벼의 생육에 미치는 영향 2) 육묘용 pot 바닥의 분립무처리구에서 추정벼는 4%-6% 혼합비율에서 식물체의 생육이 양호하였다. 3) 육묘용 pot 바닥의 분립처리구에서는 추정벼가 대조구(0%) 혼합비율에서 식물체의 생육이 양호하였다. 4) 이상의 결과로부터 육묘용 상토에 분립 4%-6%를 첨가하는 것이 식물체의 생육을 촉진시켰다고 판단된다.

• Journal of Energy Engineering
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• v.10 no.1
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• pp.33-39
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• 2001

석탄화력발전소에 정착되는 고속분립체 이송용 곡관의 내마모성 향상에 관한 수치해석 및 실험적 연구를 수행하였다. 22.5$^{\circ}$와 90$^{\circ}$ 곡관을 모델로 하여, 분립체에 의한 곡관의 마모를 감소시키기 위해 유동방향이 전환되는 부분에 와류장이 형성되도록 곡관의 단면형상을 변화시켰다. 삼차원, 난류유동장의 지배방정식을 유한체적법으로 이산화시키고, SIMPLE 알고리즘을 이용하여 해를 구하였다. 수치해석을 통해 마모감소를 위한 새로운 형상의 곡관을 설계하였다. 새로운 형상의 곡관을 제작, 운전중인 국내 화력발전소에 장착하여 마모실험을 수행하였으며 내마모성이 매우 향상되었음을 알 수 있었다.

• Clean Technology
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• v.11 no.4
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• pp.181-188
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• 2005

Developed is the new gas-solid flow ball valve where air injection purging concept is applied for the control and the reduction of particle fouling. CFD analyses are conducted for investigating the interaction between gas-sold and air injection streams and the fouling phenomena in valve, and the analysis results are reflected in the design of valve geometry and air injection condition. Through the actual tests on designed ball valve, the present valve is shown to be superior in fouling reduction.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.10
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• pp.170-179
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• 2004

A vibration model of powder transfer equipment is developed by the lumped parameter method. A Powder transfer equipment does surging motion, bouncing motion and pitching motion. Motion equation becomes decoupling and removed vibration exciting source about pitching motion, and therefore designers presented the optimum design plan to be able to do adjustment with motion trajectory of powder transfer equipment. That is, way for design to be able to do motion trajectory of powder transfer equipment through change of design element as installation position and direction of motor, driving speed, mass unbalance, stiffness coefficient and installation position of support coil spring is presented. The design results, powder transfer equipment were able to know that fatigue destruction does not occur, and the reason is because maximum stress working on a basket structure is more very than fatigue strength small.

• Journal of the Korea Organic Resources Recycling Association
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• v.10 no.4
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• pp.96-102
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• 2002

The purpose of this study was estimate the optimal phosphorus and calcium levels of Korean native cow manure on the growth and cast production of earthworm(Eisenia foetida). Phosphorus and calcium levels supplemented to cow manure were 0%(without earthworm), 2% and 4%, and 0.01%, 0.02%, 0.04% and 0.06% of the cow manure by weight, respectively. The maximum fresh weight and increasing rate of earthworm were obtained with 2% phosphorus level, but there was not significant differences between calcium levels. The ratios of available phosphorus to calcium contents of cast were 1.04-1.20:1 with 2%, and 1.28-1.37:1 with 4% phosphorus levels. Conversion rate of organic matter to earthworm tissue were 0.35-0.41% with 2%, and 0.25-0.40% with 4% phosphorus levels.

• Journal of Animal Environmental Science
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• v.12 no.2
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• pp.75-84
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• 2006

The effects of the mixture ratios of swine manure and food wastes when vermicomposed on earthworm(Eisenia foefida) growth, the production amounts and the chemical properties of casts for plant growth media were evaluated to optimal mixture ratio. Earthworms were grown in swine manure, substituted with 0%, 20%, 40%, 60%, 50% and 100% food wastes. All of earthworm grown in swine manure substituted with 60%, 80%, and 100% food wastes died, therefore the process of swine manure substituted with 60%, 80%, and 100% food wastes by vermicomposting were impossible in this experiment. Worm cast produced from swine manure substituted with 0%, 20% and 40% food wastes after vermicomposting sufficiently contained required quantities of available phosphorus, exchangeable potassium, exchangeable magnesium, and cation exchange capacity. The survival rates of earthworm in swine manure substituted with 0% and 40% food wastes was significantly higher than those in swine manure substituted with 20%, 40% food wastes. Casts weight and proportion of casts weight in 100% swine manure were significantly higher than those in swine manure substituted with 20% food wastes, but was no significant difference between those in swine manure substituted with 40% food wastes. Therefore 100% swine manure was estimated to be superior than the others treatments. However an adequate mixture ratio of food wastes for processing mixture of swine manure by vermicomposting was estimated to be 40%. Because there was no significant difference in mean flesh weight, increasing rate, casts weight, proportion of casts weight, and reduction rate of volatile solids among 3 treatments and survival rate and conversion efficiency(CE) in swine manure with substituted 40% food wastes were significantly higher than the other treatments.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 2000.04a
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• pp.229-235
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• 2000

A study on the improvement of anti-abrasion nature of curved ducts for high-velocity gas-solid flow which are typically equipped in a coal-burned steam power plant has been investigated numerically and experimentally. To reduced the abrasion of pipe by particle, we have tried to form the vortex flow field in the region where flow changes its direction , modelled with two different shapes. 22.5$^{\circ}$and 90$^{\circ}$ elbows. the governing equations for three -dimensional , turbulent flow fields are discretized by FVM and solved bySIMPLE algorithm . From the numerical analysis, the new designed elbows for reducing abrasion have been developed. Numerical results are compared with the experimental abrasion data which are obtained from one of the operating coal burned steam power plants in Korea. Comparison of these results show that the developed elbows have much more durability than the original one.

• Journal of the Mineralogical Society of Korea
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• v.21 no.4
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• pp.383-395
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• 2008

To enhance the grade and recovery rate of the gold/silver ores which yield at Philippine Mankayan mine, we studied the characteristics which are the geologic and mineralogical features of gold and silver ore, the liberation by crushing and grinding, the separation by sieving and shaking table. Gold/silver ore is composed of the sulfide minerals like pyrite, sphalerite, galena; and the gangue minerals which is quartz, clay. Gold/silver element are mainly contained in a sulfide minerals like pyrite, sphalerite and galena. To increase the liberation rate of sulfide minerals containing gold/silver element, the gold/silver ore has to be grounded under $100{\mu}m$ very finely because the crystal size of sulfide minerals is distributed from $1{\mu}m$ to $100{\mu}m$. The liberation rate of gold/silver ore increases to 92% when the particle size ($d_{90}$) of ore is grounded below $100{\mu}m$ by jaw crusher $\to$ cone crusher $\to$ rod mill by steps. The grade and recovery of sulfide minerals could not be enhanced by sieving separation because those crystal size is distributed homogeneously below $100{\mu}m$. But, when we separated the sieved ore using shaking table, the gold and silver grade increased to 40 ppm and 140 ppm, respectively. Then the recovery rate of gold reach almost 100% but that of silver is no more that 50%.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.65-65
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• 2017

밭작물 중 양파와 마늘은 높은 노동투하시간, 노임의 상승, 복잡한 수거 과정 등으로 최근 재배면적이 감소하는 추세이다. 밭농업 활성화 방안으로 생산비 절감과 작업 속도 향상을 위한 수확기계 개발 연구로 줄기절단기가 개발되었다. 이 연구는 줄기절단기 예취날의 설치각이 절단부하에 미치는 영향을 분립체 해석 기법으로 분석하고자 하였다. 실험에 사용한 시뮬레이션은 EDEM으로 인장탄성계수, 전단탄성 계수, 중첩길이, 입자 반경 및 질량, 상대속도를 이용하여 충돌시 힘을 해석하고 인장 및 전단강도, 한계, 결합 길이를 통해 입자간 결합을 설정할 수 있다. 시제품으로 설계된 줄기절단기의 치수를 활용하여 프로그램 상에서 줄기 절단 시뮬레이션을 진행하여 절단부하 결과를 얻도록 하였고 칼날 설치각을 30도, 45도, 60도로 변경하여 각각의 부하를 분석하여 경향성을 파악하고자 하였다. 실험에서 사용한 프로그램은 EDEM 2.7.1 Academic Research 버전이며 시뮬레이션을 진행한 PC의 사양은 Intel(R) $Core^{TM}$ i7-4790 CPU @ 3.60GHz, Memory 16.0GB이다. 줄기 절단 시뮬레이션에 적용시킨 줄기 모델은 마늘의 조건을 적용시켜 직경 1mm의 입자로 이루어진 지름 12mm, 높이 214mm의 원통형 모델이며 60.32N의 최대절단력을 가지고 있다. 줄기절단기는 2개의 회전날을 가지고 있으나 좌우대칭을 적용하여 절반에 대한 해석으로 하나의 회전날로 절단을 하도록 줄기 모델은 4조로 하여 3열을 140mm 간격으로 위치시켰다. 줄기절단기의 칼날은 반경 350mm로 회전하며 진행속도는 1.65m/s, 회전속도는 1680rpm으로 작업하도록 하였다. 시뮬레이션은 0.5초의 시간에 대해 해석하도록 하였으며 0.003초 간격으로 칼날에 가해지는 힘을 구하여 저장하도록 하였다. 시뮬레이션 해석시간은 약 116시간이었으며 설치각별 시간에 따른 칼날에 가해지는 압축력 값과 그래프를 얻을 수 있었다. 대부분의 시간에서 절단이 이루어지지 않으므로 0의 값을 나타내었으며 절단이 이루어지는 시점에 절단부하가 나타났다. 결과 해석을 위해 그래프의 피크 값들을 이용하였으며 그 중 상위 6개의 값으로 분석하였다. 30도, 45도, 60도의 설치각에 따른 절단부하의 평균 값은 각각 105.4N, 160.5N, 215.9N으로 나타났다. 설치각에 따른 절단부하의 경향성은 유의수준은 3.93%로 각각의 차이가 유의미하게 나타났으며 상관계수는 0.489로 증가하는 경향이 보였다. 그러나 $R^2$는 0.2394로 낮은 값을 보여 데이터 처리 방법의 개선과 적절한 회귀 모델의 적용이 필요하다. 향후 포장시험을 진행하고 복합적으로 분석하여 경향성을 자세히 분석하고자 한다.