• 생물환경조절학회지
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• 제12권2호
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• pp.101-105
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• 2003

양파 plug묘 육묘시 일장조절에 의한 우량묘 생산을 위해 자연일장을 대비로 하여 11.5시간, 12.5시간 및 13.5시간의 일장 하에서 월륜과 창녕대고 품종을 200공 plug tray에 육묘한 후에 직경 16cm pot에 이식하여 16시간의 일장 하에서 재배하였다. 엽수, 엽초경, 초장 및 엽초장은 시기가 경과할수록 증가하였으나 13.5시간 일장에서의 초장과 엽초경은 일장처리 20일 후에는 감소하였다. 일장에 따른 생육은 엽수 및 엽초경은 장일조건에서 생육이 좋았으나 초장 및 엽초장은 장일에서 억제되는 경향을 나타내었다. 장일조건에서 육묘한 것일수록 이식 후에 구가 크고 비대도 빨랐다. 이상의 결과로 볼 때 육묘기간 중의 장일처리로서 도장의 억제 및 우량묘 생산의 가능성을 보여주고 있다.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2005년도 연구개발 발표회 논문집
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• pp.178-184
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• 2005

The present study investigates the effects of bleed flow on heat/mass transfer and pressure drop in a rotating channel with transverse rib turbulators. The hydraulic diameter ($D_h$) of the square channel is 40.0 mm. The bleed holes are located between the rib turburators on leading surface and the hole diameter (d) is 4.5 mm. The square rib turbulators are installed on both leading and trailing surfaces. The rib-to-rib pitch is 10.0 times of the rib height (e) and the rib height-to-hydraulic diameter ratio ($e/D_h$) is 0.055. The tests were conducted at various rotation numbers (0, 0.2, 0.4), while the Reynolds number and the rate of bleed flow to main flow were fixed at 10,000 and 10%, respectively. The results suggest that the heat/mass transfer characteristics in the internal cooling passage are influenced by rib turbulators, bleed flow and the Cariolis force induced by rotation. For the rotating ribbed passage with bleed flow, the heat/mass transfer on the leading surface is hardly affected by bleed flow, but that on the trailing surface decreases due to the diminution of main flow. The results also show that the friction factor decreases with the bleed flow.

• 한국방재학회 논문집
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• 제3권2호
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• pp.139-145
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• 2003

본 연구에서는 다양한 크기의 원환에 따른 균등원통교각 주위의 세굴심을 분석하여 세굴심 감소효과 및 원환의 적정 크기를 제시하였다. 이를 위하여 수리모형실험을 실시하였으며, 교각에 원환을 설치한 경우 원환을 하상 위보다 하상 아래에 설치하는 것이 더욱 효과적이었으며, 원환의 크기가 클수록 세굴심 감소 효과가 뚜렷하였다. 교각 직경에 대한 원환 직경의 비(W/D)가 2인 경우 약 67% 세굴심이 감소하였으며, 퇴적고는 약 70%정도 증가하였다. 세굴심 감소 효과, 세굴공 및 퇴적고의 분석 결과를 토대로 W/D=2인 원환을 최적 크기로 제안하였다.

• 생명과학회지
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• 제13권6호
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• pp.889-895
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• 2003

장미 삽목묘에 돌리도를 주기적으로 관주하여 초장, 경직경, 엽수, 엽면적, 최대 근장 등 생육반응을 검정한 결과 돌리도의 관주처리는 삽목묘의 초기생육에 큰 차이는 없었으나 60일 후의 후기생육은 향상되었다. 장미 유목에 돌리도를 관주 처리하면 초장, 경직경의 향상과 줄기의 부피생장 더불어 엽수 및 엽면적이 증가되었다. 돌리도를 주기적으로 관주한 장미유목은 이를 처리하지 않은 대조구에 비해 초장이 6.4∼11.0 cm, 경직경은 0.70∼l.14 cm증가하였고, 엽면적도 $136cm^2$ 높았다. 또한 돌리도의 처리에 의해 총 생체중 및 총 건물중을 증가시켰는데, 그 효과는 생육후기로 갈수록 현저하였다.

• 태양에너지
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• 제10권3호
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• pp.3-12
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• 1990

본 실험연구에서는 탱크의 직경에 대한 높이의 비(H/D)가 3이고 유입 유량이 8LPM, 유입수의 온도와 기존 저장수와의 온도차, ${\Delta}T=30^{\circ}C$일때, 운동량교환을 최소화하여 가장 좋은 성층을 얻었고 또한 실험에서 사용한 유입구(Inlet Port)의 경우 수정 Richardson수(Modified Richardson Number), Ri가 0.004(Q=10LPM, ${\Delta}T=30^{\circ}C$) 이하의 값에서는 완전 혼합(Fully Mixing)이 발생하고 H/D가 작아질수록 혼합층의 두께($H^*/H$)가 증가하여 성층 축열에는 바람직하지 못하였다. 그리고 성층은 성층을 촉진시키기 위하여 Distributor를 사용했을 때가, Distributor를 사용하지 않은 유입구(Inlet Port)의 경우 보다 잘 형성되어 저장효율이 Distributor를 사용한 경우(Q=8LPM, ${\Delta}T=30^{\circ}C$, H/D=3)에 Distributor를 사용하지 않은 유입구(Inlet Port)의 최저효율 63%(Q=12LPM, ${\Delta}T=30^{\circ}C$, H/D=3인 경우)보다는 31% 정도, 최대효율 84%(Q=8LPM, ${\Delta}T=30^{\circ}C$, H/D=3인 경우)보다는 11% 정도 높은 95%까지 저장 효율을 증가시킬 수 있었다. 더 나아가서 단면이 균일한 원형 Distributor(A=D=Constant)의 경우에, 유량이 8LPM인 경우에 관내의 압력차가 작아 부분혼합(Partial Mixing)이 감소하여 안정된 성층을 얻을 수 있었다. 그리고, Distributor의 직경을 다음식과 같이 $$\frac{D}{D_L}=(\frac{x}{L})^{1/2}(1+\frac{fL}{2D})-\frac{fx}{2D_L}$$ 길이에 대하여 변화시켜 Distributor를 제작함으로써, 보다 안정된 열성층과 높은 열저장 효율을 얻을 수 있을 것으로 예상한다.

• Journal of Forest and Environmental Science
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• 제39권1호
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• pp.20-26
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• 2023

Cow pea (Vigna unguiculata) was intercropped with Ziziphus spina-christi as summer forage in two consecutive seasons of 2017 and 2018. The aims to find out suitable agroforestry practice for saline soils of Khartoum State. And to investigate effect of tree spacing on forage biomass yield under semi -irrigated systems. Completely randomized block design with 3 replicates was conducted for this trial. Thus Z.spina-christi that fixed at 4×4 m was intercropped with cowpea at 1 m and 1.5 m spacing from trees trunk. Tree growth parameters were measured in terms of tree height, tree collar diameter, tree crown diameter and fruit yield per tree. While crop were parameters were determined in terms of plant height, number of plant, forage biomass yield per ha and land equivalent ratio. Soil profile of 1×1 m and 1.5 m depth was excavated and its features were described beside its chemical and physical properties were analyzed for 0-10 cm, 0-30 cm, and 30-60 cm and 60-100 cm layers. The results revealed that soil pH, CaCO₃, SAR, ESP, and EC ds/m were increased by increasing soil depths. Meanwhile tree growth in terms of tree height was significant in the first season 2017 when compared with tree collar diameter and tree crown diameter. Also significant differences were recorded for tree growth when compared with sole trees in the second season in 2018. Tree fruit showed marked variations between the two seasons, but it was higher under intercropping particularly at ZS2. Crop plant height was highly significant under sole cropping than intercropping in first season in 2017. In contrast forage biomass yield was significant under intercropping in ZS1 and ZS2 treatments. Land equivalent ratio was advantageous under this agroforestry system particularly under ZS2. Thus it recorded 5 and 9 for ZS2 in the two consecutive seasons respectively. Therefore, it is feasible to introduce this agroforestry system under such arid lands to provide summer forage yield of highly nutritive value and low cost for animals feed as well as to increase farmers' income and to halt desertification and to sequester carbon.

• 한국마이크로전자및패키징학회:학술대회논문집
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• 한국마이크로전자및패키징학회 2001년도 추계 기술심포지움
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• pp.67-73
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• 2001

To investigate the relationships of solder joint characteristics with solder composition and A:V ratio (solder volume per pad area), Sn-37Pb and Sn-4.0Ag-0.5Cu solder balls with 330, 400, 450 and $457{\mu}{\textrm}{m}$ size were reflowed on same substrate. Sn-37Pb and Sn-4.0Ag-0.5Cu was reflowed at $220^{\circ}C$ and $240^{\circ}C$ respectively by IR-type soldering machine. As a result of reflowed solder- ball diameter(D) and height(H) measurement, D/H was decreased with solder ball size increment in range of 330~450 ${\mu}{\textrm}{m}$. But, D/H was increased in the solder joint for 457 ${\mu}{\textrm}{m}$ size, it was caused possibly by decrement of solder ball height increment compared with solder volume increment. As a result of shear and pull test, joint strength with A:V ratio was high. Joint strength of Sn-4.0Ag-0.5Cu was higher than Sn-37Pb. However, Sn-37Pb had more stable solder joint of small standard deviation. A thick and clean scallop type Ni-Cu-Sn intermetallic compound layer was formed in high A:V ratio and Sn-4.0Ag-0.5Cu solder joint interface.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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• pp.178-179
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• 2005

Numerical and experimental investigation of incompressible turbulent flow and heat transfer through square channels with varying number of ribbed walls were conducted to determined pressure drop and heat transfer. The CFX solver used for the computation. The rough walls have a $45^0$ inclined square rib. Uniform heat flux is maintained on whole inner heat transfer channel area. The numerical results agreed well with experimental data that obtained for 7600$D_h$) of 0.0667. The results show that values of local heat transfer coefficient and friction factor increase with an increasing number of ribbed walls.

• Journal of Advanced Marine Engineering and Technology
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• 제29권3호
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• pp.281-289
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• 2005

An experimental study on the heat transfer and friction characteristics of a fully developed turbulent air flow in a square channel with $45^{\circ}$ inclined ribs on one, two, and four walls is reported. Tests were performed for Reynolds number ranging from 7,600 to 24,900. The pitch-to-rib height ratio, p/e, was kept at 8 and rib height-to-channel hydraulic diameter ratio, $e/D_h$, was kept at 0.0667. The heat transfer coefficient and friction factor values were enhanced with the increase in the number of ribbed walls. Results of this investigation could be used in various applications of internal channel turbulent flows involving different number of roughened walls.

• Computers and Concrete
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• 제28권6호
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• pp.559-566
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• 2021

In this paper, frequency analysis has been done for functionally graded cylindrical shell with ring supports using Sander's shell theory. The vibrations of rotating cylindrical shells are analyzed for different physical factors. The fundamental natural frequency is investigated for different parameters such as: ratios of length-to-diameter ring supports. By increasing different value of height-to-radius ratio, the resulting backward and forward frequencies increase and frequencies decrease on increasing height-to-radius ratio. The frequencies for different position of ring supports are obtained in the form of bell shaped. The backward frequencies increases and forward frequencies decrease on increasing the rotating speed. The results generated furnish the evidence regarding applicability of present shell model and also verified by earlier published literature.