• 자원리싸이클링
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• 제7권2호
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• pp.16-22
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• 1998

최근 선진국에서는 폐플라스틱을 고로의 대체연료로 이용하려는 기술개발이 시도되고 있다. 본 연구에서는 포항제철 주물선 고로 풍구 1본을 대상으로 시험취입을 실시한 결과, 플라스틱의 취입속도는 다음과 같이 나타낼수 있었다. ${W}_{s}=0.265\frac{{delta}PA}{U}_{g}$ 여기서 Ws, ΔP, A 그리고 Ug는 각각 플라스틱 수송속도(kg/sec), 공급용기내의 압력과 송풍압력의 차이(atm), 수송배관의 단면적($m^2$) 그리고 총 수송공기 유속(m/sec)이다. 약 96시간의 조업기간중 최대 취입비 6.4kg-plastic/t-p까지의 반연속 시험취입 조업결과, 치환율은 1.38정도였다. 플라스틱이 취입됨에 따라 노정가스중 수소의 함량은 증가하였으며, 연소대 형상변화에 따라 bellyqn 노체의 온도는 상승하였다.

• 디지털산업정보학회논문지
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• 제13권2호
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• pp.53-61
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• 2017

How to manage manhole is to estimate the part without observation and maintain the sewer. To get the information about current flow rate, visiting and measuring specific manhole is positively necessary. Also, there are some problems that accurate measurement of flow rate is difficult and obtaining the information about real-time whole flow rate is impossible. This thesis will easily grasp the accurate location and type of manhole to solve the problems, and provide the manhole system conveying information through direct radio communication with a manhole cover to renewal information of manhole properly. Besides, it intends to save the information about management of waterworks, maintenance of facilities, data for flow rate, and structure of manhole. Using these, it is supposed to offer how to handle manhole. Thus, this thesis delivers the information to manhole and into central servers directly without wire and provides the system and management method for effective maintenance of manhole.

• 한국추진공학회지
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• 제8권2호
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• pp.25-31
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• 2004

본 연구에서는 유연 외팔 구조물의 내부에 유체를 흐르게 함으로써 구조물의 진동을 억제시키는 방법을 제안한다. 안정성 해석과 동적 응답은 유한 요소법에 기초를 두었다. 근 궤적 선도에 있어서 플러터 한계와 최적 안정화 유속을 결정하였다. 진동의 감쇠를 관찰하기 위하여 모드 중첩법이 사용되었다. 시스템의 내부 흐름에 의한 안정화 효과는 구조물의 내부 감쇠를 무시한 경우와 포함한 경우의 임펄스 응답을 통하여 분석하였다. 내부 흐름은 기체의 경우보다도 액체의 경우가 더 큰 안정화 효과가 있다는 결론을 얻어냈다.

• 한국시뮬레이션학회논문지
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• 제10권1호
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• pp.63-65
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• 2001

To investigate the natural frequencies of curved piping systems with various elbow angles conveying flow fluid, a simulation is performed considering Initial tension due to the inside fluid. The system is analyzed by finite element method utilizing straight beam element. Elbow part is meshed using 4 elements, and the initial tension is considered by inserting equivalent terms into the stiffness matrix. Without considering the initial tension, the system becomes unstable, that is, the fundamental natural frequency approaches to zero value fast, as the flow velocity reaches critical value. With the initial tension terms, the system becomes stable where there is no abrupt decrease of the fundamental natural frequency. The change rate of the natural frequency with respect to the flow velocity reduces. As elbow angle increases, the system becomes stiffer, then around 150 degrees of the elbow angle the natural frequency has the largest value, the value decreases after the angle of the largest natural frequency. When angle is between 170 degrees and 179 degrees, the natural frequency is very sensitive. This means that small change of angle results in great change of natural frequency, which is expected to be utilized in the control of the natural frequency of the piping system conveying flow fluid.

• Advances in Computational Design
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• 제5권3호
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• pp.261-276
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• 2020

The reasonable layout of vacuum cleaner can effectively improve the collection efficiency of iron filings generated in the process of steel production. Therefore, in this study, the CFD-DEM coupling model and two-fluid model are used to calculate the iron filings collection efficiency of vacuum cleaner with different inclination/cross-sectional area, pressure drop and inlet angle. The results are as follows: The CFD-DEM coupling method can truly reflect the motion mode of iron filings in pneumatic conveying. Considering the instability and the decline of the growth rate of iron filings collection efficiency caused by high pressure drop, the layout of 75° inclination is suggested, and the optimal pressure drop is 100Pa. The optimal simulation results based on two-fluid model show that when the inlet angle and pressure drop are in the range of 45°~65° and 70Pa~100Pa, larger mass flow rate of iron filings can be obtained. It is hoped that the simulation results can offer some suggestion to the layout of vacuum cleaner in the rolling mill.

• Journal of Biosystems Engineering
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• 제31권4호
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• pp.305-314
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• 2006

Precision farming has been known as an environment friendly farming technology. This study was conducted to develop a variable-rate granule fertilizer applicator as an attempt for introducing the precision farming technologies to rice cultivation in Korea. In this paper, concept design process and manufacturing of prototype variable rate granule applicator was reported. For concept design, some design guide lines were selected. Based on the design guide line and some engineering knowledge, concept design was conducted. The designed prototype granule applicator was mounted at the rear of riding type cultivator for paddy field and had a 10m wide boom structure with pneumatic conveying and application system as well as 1GPS receiver, 1 granule hopper, 12 blow heads, 2 metering devices and 1 controller. The fertilizer applicator had 942 ka of weight, 740m of ground clearance and 1,117mm of center of gravity from the ground. The applicator was designed to be able to $34{\sim}428kg/ha$ of granule at $0.2{\sim}0.8m/s$ of fertilizer working speed.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권6호
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• pp.964-978
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• 2015

Numerous experiments with a scaled pilot facility were carried out to compare the relative bulk transfer performance of three special devices for applications to drilling systems. The pipe diameter for bulk transportation was 3 in., which corresponds to around half of the actual system dimensions. Two different pressures, 3 and 4 bar, were considered to check the relative performance under different pressure conditions at a bulk storage tank. And to make a practical estimation method of the bulk transfer rate at the early design stages of the bulk handling system, a series of experiments were conducted for real scaled bulk handing systems of two drilling vessels. The pressure drops at each pipe element as well as the bulk transfer rates were measured under different operating conditions. Using the measured results, the friction factor for each pipe element was calculated and a procedure for transfer rate estimation was developed. Compared to the measured transfer rate results for other drilling vessels, the estimated transfer rates were within a maximum 15% error bound.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2004년도 ICCAS
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• pp.1319-1323
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• 2004

In this paper, a problem of Thai sign language recognition using a neural network is considered. The paper addresses the problem in classifying certain signs conveying quantitative meaning, e.g., large or small. By treating those signs corresponding to different quantities as derived from different classes, the recognition error rate of the standard multi-layer Perceptron increases if the precision in recognizing different quantities is increased. This is due the fact that, to increase the quantitative recognition precision of those signs, the number of (increasingly similar) classes must also be increased. This leads to an increase in false classification. The problem is due to misinterpreting the amount of quantity the quantitative signs convey. In this paper, instead of treating those signs conveying quantitative attribute of the same quantity type (such as 'size' or 'amount') as derived from different classes, here they are considered instances of the same class. Those signs of the same quantity type are then further divided into different subclasses according to the level of quantity each sign is associated with. By using this two-level classification, false classification among main gesture classes is made independent to the level of precision needed in recognizing different quantitative levels. Moreover, precision of quantitative level classification can be made higher during the recognition phase, as compared to that used in the training phase. A standard multi-layer Perceptron with a back propagation learning algorithm was adapted in the study to implement this two-level classification of quantitative gesture signs. Experimental results obtained using an electronic glove measurement of hand postures are included.

• 한국생산제조학회지
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• 제22권4호
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• pp.635-642
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• 2013

We have prepared a DEMO conveyor device for conveying a large 8G class glass sheet using ahorizontal air-cushion system. This device consists of the body frame and the driving frame that are combined to realize a frame for conveying glass without any contact.The driving frame comprises an air flotation table (bed), drive roller supported at both ends, and ASU. Part of the ASU serves to control the airflow as the chamber consists of a porous pad and fan. Fiber filters replace the porous pad and axial fans serve as an air compressor. In addition, to determine the appropriate glass levitation from the air table, this study examined the design specifications of the applied filter (discharge speed of HEPA and ULPA filters, and flow rate) as well as the height of the and the proper supporting roller height (14mm). Then, after adjusting the position of the ASU and the number of ASUs required to configure the UNIT air floating C/V, we analyzed the height and flatness of the glass and derived the appropriate layout (1140-mm distance between ASUs).

• 한국축산시설환경학회지
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• 제19권1호
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• pp.9-18
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• 2013

Currently, there was no producing system of TMR for pig feeding in Korea. In this study, we examined unrolling, cutting, and softening for the round bale silage. We designed and developed the prototype system of round bale silage for pig feeding. Unroll method were lower chain conveying and upper belt conveying which includes an hydraulic vertical fodder knife. Gathering and cutting method were rotating auger and flywheel which have 10 cutters, input roller of 280 rpm, and cutter rotating speed of 1,750 rpm. Softening device was rotating hammer in inclined cylinder adjustable to $25^{\circ}C$ and rotating speed up to 1,300 rpm. The prototype system was integrated working for unrolling, cutting, and softening. We found that when the round bale silage in unrolling apparatus cut length of 20 cm to input cutting apparatus, the cutting performance was well in continuous working up to input rate of 1,000 kg/h, the softening apparatus was working well.