• Journal of Aquaculture
• /
• v.14 no.1
• /
• pp.43-50
• /
• 2001

To study the effect of paddle wheel on water circulation, velocity components were measured in shrimp ponds both along the longitudinal direction from a single paddle wheel and at 25 grid points of two ponds, which have mean water depth of 1.2m and aspect ratio (length/width) 1.05 and 0.68, respectively. An analysis of factors related to water quality and circulation showed that I) a single paddle wheel has an effective distance of 33m for de-stratification, 16m for particulate suspension and 25m for removal of organic material, dispersion of DO and prevention of bed sediment disturbance and ii) with doubling the number of paddle wheels at the pond corners, the flow speed increased by 13% over the ponds, while it reduced by 8.5% around the pond centres. Contrary to expectation, increasing the number of paddle wheel did not generate strong circulation around the pond centre and improve water quality.

• Journal of the Chungcheong Mathematical Society
• /
• v.34 no.3
• /
• pp.285-294
• /
• 2021

In the present work we introduce Gaussian vertex prime labeling and investigate Gaussian vertex prime labeling for gear graph, book graph, wheel graph, kayak paddle, one point union of gear graph and one point union of wheel graph.

• Korean Journal of Crystallography
• /
• v.15 no.2
• /
• pp.78-82
• /
• 2004

The solvothermal reaction of zinc(H) nitrate $(Zn(NO_3)_2\;{\cdot}\;6H_2O)$ with $ATP(2-aminoterephthalate,\;H_2N-C_6H_3-1,4-(COO)_2)$ in a mixture of solvents of DMF and ethanol, in the presence of benzene, gave a 2 dimensional zinc polymer [Zn(ATP) (DMF)] (1). X-ray structure determination revealed that two zinc metals and four ATP ligands form the paddle-wheel SBUs, which are linked by the ATP ligands to give a 2-D square-grid network. Each square grid has approximate dimensions of $11.1\times11.1\;{\AA}$ based on Zn metals. Benzene was required to produce high-quality crystals of polymer 1.

• Proceeding of EDISON Challenge
• /
• 2014.03a
• /
• pp.197-209
• /
• 2014

환경 오염에 대한 우려의 목소리가 높아지면서 Green chemistry 분야가 각광을 받고 있다. 이 분야에서는 환경에 영향을 적게 미치기 위한 방법의 일환으로 촉매를 연구하며, 그 촉매는 착화합물인 경우가 많다. 그러나 착화합물 내에서 리간드와 금속 이온간의 결합은 예측하기 어렵다. 이는 전형금속보다는 전이금속에서 더욱 심하며, 그 중 한 예로 전이금속에서는 여러 개의 금속 이온이 서로 직접적으로 결합한 채 리간드와 결합하는 착화합물이 발견되기도 한다. 다중 금속 착화합물(Multimetal Complex)로 부르는 이러한 구조는 특유의 복잡함 때문에 잘 알려져 있지 않음에도 불구하고 착화합물의 물리적, 화학적 성질에 직접적으로 영향을 주기에 촉매나 센서, 특히 이를 이용하여 구조체를 만드는 MOF(Metal-Organic Framework) 분야에서는 꼭 알고 있어야 하는 사항이다. 이 연구에서는 GAMESS로 density functional theory (B3LYP functional)를 이용한 양자계산을 수행하여 그 중 가장 간단한 구조인 Dimetal Complex, 그 중에서도 MOF 내에서 많이 발견되는 수차 형태(Paddle wheel) 착화합물에 대해서 다루었다. Cu를 기준으로 그와 비슷한 주기나 족에 있는 Ru, Ag, Zn 등의 금속으로 만든 Paddle wheel 구조의 에너지를 비교하여 Cu가 다른 금속에 비해 이 구조를 안정하게 형성할 수 있는 이유를 알아보았다. 더 나아가 이 구조가 MOF의 형성과 성질에 어떠한 연관성이 있는지 분석함으로써 어떠한 조건이 MOF의 성질을 극대화시킬 수 있는지도 알아보았다.

• Journal of the korean Society of Automotive Engineers
• /
• v.15 no.3
• /
• pp.1-9
• /
• 1993

디젤 엔진의 연소 과정에서 흡입공기와 분사된 연료의 최적 혼합기 형성이 배기성분, 연료효율 등 엔진의 성능을 향상시키는데 있어 매우 중요한 과제중의 하나이다. 이를 위하여 연료분무 현상에 대한 연구와 더불어 연소실내 공기유동 현상에 대한 연구가 주요 관심대상이 되어왔다. LDV를 이용한 3-D 유속측정 및 각종 CFD Code를 이용한 유동해석등의 방법으로 엔진 실린더 내부의 유동현상을 이해하는데 많은 도움이 되고 있으나 아직도 엔진연소실설계 등 엔진 개발에 있어서는 종래의 방법에 의한 실린더내 와류 강도의 비교평가에 크게 의존하고 있으므로 여기서는 디젤 엔진의 와류를 측정 평가하는 방법으로 Paddle Wheel회전을 이용한 Paddle Wheel식 Swirl Meter방식과 실린더내 흡입공기의 각 운동량을 측정하는 Impulse식 Swirl Meter 방식에 대해 고찰하고자 한다.

• Bulletin of the Korean Chemical Society
• /
• v.25 no.12
• /
• pp.1955-1958
• /
• 2004

• Journal of the Korean Chemical Society
• /
• v.60 no.5
• /
• pp.321-326
• /
• 2016

Two new polymeric complexes, [Zn(dpa)(pyz)_0.5]_n (1; dpa = diphenate and pyz = pyrazine) and [Mn₃(bpdc)₃(py)₄]_n (2; bpdc = biphenyl-4,4'-dicarboxylate and py = pyridine) were successfully isolated by the hydro- and solvo-thermal technique, respectively. The complexes were characterized by elemental and thermal analysis, vibrational IR spectroscopy, and by single crystal x-ray structure determination. For 2, magnetic property was also investigated. Complex 1 is a two-dimensional layer structure consisting of a paddle-wheel building unit of Zn-dpa chains bridged by pyrazine. While, complex 2 consists of linear trimeric Mn3 cluster as building unit to form 3D network. In the complexes, dpa²⁻ (1) and bpdc²⁻(2) ligands show a typical bis-monodendate bridging and two kinds of bridging modes; a typical bridging and chelating/bridging mode, respectively.

• Journal of Biosystems Engineering
• /
• v.41 no.4
• /
• pp.408-417
• /
• 2016

Purpose: Yield monitoring systems are an essential component of precision agriculture. They indicate the spatial variability of crop yield in fields, and have become an important factor in modern harvesters. The objective of this paper was to review research trends related to yield monitoring sensors for grain crops. Methods: The literature was reviewed for research on the major sensing components of grain yield monitoring systems. These major components included grain flow sensors, moisture content sensors, and cutting width sensors. Sensors were classified by sensing principle and type, and their performance was also reviewed. Results: The main targeted harvesting grain crops were rice, wheat, corn, barley, and grain sorghum. Grain flow sensors were classified into mass flow and volume flow methods. Mass flow sensors were mounted primarily at the clean grain elevator head or under the grain tank, and volume flow sensors were mounted at the head or in the middle of the elevator. Mass flow methods used weighing, force impact, and radiometric approaches, some of which resulted in measurement error levels lower than 5% ($R^2=0.99$). Volume flow methods included paddle wheel type and optical type, and in the best cases produced error levels lower than 3%. Grain moisture content sensing was in many cases achieved using capacitive modules. In some cases, errors were lower than 1%. Cutting width was measured by ultrasonic distance sensors mounted at both sides of the header dividers, and the errors were in some cases lower than 5%. Conclusions: The design and fabrication of an integrated yield monitoring system for a target crop would be affected by the selection of a sensing approach, as well as the layout and mounting of the sensors. For accurate estimation of yield, signal processing and correction measures should be also implemented.

• Korean Journal of Agricultural Science
• /
• v.51 no.1
• /
• pp.63-77
• /
• 2024

Yield monitoring systems have become integral to precision agriculture, providing insights into the spatial variability of crop yield and playing an important role in modern harvesting technology. This paper aims to review current research trends in yield monitoring systems, specifically designed for non-grain crops, including cabbages, radishes, potatoes, and tomatoes. A systematic literature survey was conducted to evaluate the performance of various monitoring methods for non-grain crop yields. This study also assesses both mass- and volume-based yield monitoring systems to provide precise evaluations of agricultural productivity. Integrating load cell technology enables precise mass flow rate measurements and cumulative weighing, offering an accurate representation of crop yields, and the incorporation of image-based analysis enhances the overall system accuracy by facilitating volumetric flow rate calculations and refined volume estimations. Mass flow methods, including weighing, force impact, and radiometric approaches, have demonstrated impressive results, with some measurement error levels below 5%. Volume flow methods, including paddle wheel and optical methodologies, yielded error levels below 3%. Signal processing and correction measures also play a crucial role in achieving accurate yield estimations. Moreover, the selection of sensing approach, sensor layout, and mounting significantly influence the performance of monitoring systems for specific crops.