• Journal of Bio-Environment Control
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• v.26 no.3
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• pp.215-220
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• 2017

This study was conducted to improve the insufficiency of fruit vegetable grafting system developed by National Institute of Agricultural Sciences, Rural Development Administration. When the rotary blade cut the stem of scions and rootstocks, the grafting failure at curved cutting surfaces happened. The cutting depth of a tomato seedling by a rotated cutter was calculated 0.11 mm even when the cutting arm length and the maximum stem diameter were 50 mm and 5 mm, respectively. Mathematical analysis and high-speed photography showed that there was no problem by cutting in straight the stem of scions and rootstocks. The compression test of seedling stems to design the optimal shape of gripper showed that stems were not completely restored when they were compressed above 0.8 mm and 0.6 mm in case of rootstocks and scion, respectively. This study found that the bending angle of stem of tomato seedlings at the grafting period was 10 degree on average. The optimal gripper finger was the edge finger type which could be precisely set center point by adjusting the distance between fingers. In addition, it was found that most of seedling could be grasped without damage when the finger-to-finger distances is set to 2.5 mm for scion and 3.0 mm for rootstocks and finger are coated by 1 mm-thick flexible material.

• Journal of computational fluids engineering
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• v.19 no.4
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• pp.80-85
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• 2014

High-volume low-speed (HVLS) fans are one category of ceiling fan installed in large enclosings such as warehouses, large barns and health clubs in order to generate comfortable air circulation. As a rotary blade, aerodynamic performance of a HVLS fan is predominantly related to its airfoil(s), and the pitch and twist angles. This paper first, investigates the effects of airfoil on the performances of three different HVLS fans with NACA 5414, 6413 and 7415 airfoils. The fans have six untwisted blades with the diameter of 6 m and rotate at 60 RPM. The blades pitch angels are $12^{\circ}$, $12^{\circ}$ and $13^{\circ}$, respectively. The results are presented in the form of the aerodynamic forces and moments, volumetric flow rate and streamlines. Regarding the volumetric flow of air, the results show that the model with NACA 7415 has the best performance. Hence, two other HVLS fans with the same airfoil but, with four and five blades are studied in order to investigate the effects of number of blades. From the point of view of air circulation still the six-bladed fan is the best one; however, the five-bladed fan is more efficient in power consumption.

• 연구논문집
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• s.27
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• pp.127-139
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• 1997

Two-for-one twister is a kind of textile machine and makes special fancy yarn which is twisted two times per one revolution in order to increase tensile strength and wear resis-tance of yarn. Spindle mechanism has to be stable and continuous motion in high speed revolution, and then optimal design is necessary to analyze dynamic characteristics of spindle unit. Spindle unit is consist of blade and rotary disc that are cylindrical body of revolution. For analysis of the dynamic characteristics of spindle unit, transfer matrix method is used and a numerical code SPINDLE also. Torsion and natural bending frequency of the spindle unit are examined. Its displacement mode is studied in function of variable revolutions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.10
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• pp.3262-3271
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• 1996

Flow patterns were measured in a shrouded centrifugal impeller. The flow rate in measurements was fixed at the value corresponding to a nearly zero incidence at the blade inlet. By using a single slanted hot-wire probe and a Kiel probe mounted on the impeller hub disk, the 3-D relative velocities and the rotary stagnation pressures were measured in seven circumferential planes from the inlet to the outlet of impeller rotating at 700 rpm, and the static pressure distribution along flow passage and the slip factor at impeller outlet were calculated from the measured values. From these measured data, the primary and secondary flows, the wake production and the static pressure rise in the impeller passage were investigated. Furthermore, the secondary flow patterns and the wake's location in this impeller passage were compared with those of the unshrouded impeller.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.337-341
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• 2004

This paper concerns the analytical modeling and dynamic analysis of advanced rotating blade structure implemented by a dual approach based on structural tailoring and viscoelastic materials technology. Whereas structural tailoring uses the directionality properties of advanced composite materials, the passive materials technology exploits the damping capabilities of viscoelastic material(VEM) embedded into the host structure. The structure is modeled as a composite thin-walled beam incorporating a number of nonclassical features such as transverse shear, warping restraint, anisotropy of constituent materials, and warping and rotary inertias. The VEM layer damping treatment is modeled by using the Golla-Mushes-McTavish(GHM) method, which is employed to account for the frequency-dependent characteristic o the VEM. The displayed numerical results provide a comprehensive picture of the synergistic implications of the application of both techniques, namely, the tailoring and damping technology on vibration response of thin-walled beam structure exposed to external time-dependent excitations.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2002.02a
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• pp.3-8
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• 2002

본 연구는 트랙터 부착형 자동 토양경도 측정 시스템의 개발에 관한 연구로서, 우리나라 토양조건이나 작업형태에 맞는 에너지 절감형 트랙터 로타리날을 개발하기 위한 전단계 연구로서, 기존에 개발된 로타리날과 개량, 보완되어 개발될 로타리날의 성능을 비교 분석하기 위하여 수동 토양경도 측정기의 부정확성을 개량하여 측정의 정확성을 통한 동일 실험조건에서의 실험을 실시하고자 자동으로 작동되며 토양경도측정을 할 수 있는 트랙터 부착형 자동 토양경도 측정 시스템을 개발하는데 목적이 있으며, 그 구체적인 연구 결과는 다음과 같다. (1) 시스템은 토양경도 측정부, 측정장치 구동부, 그리고 트랙터와의 연결부로 구성되었다. (2) 시스템 작동에 필요한 전원공급을 트랙터 배터리에서 공급하였다. (3) 토양경도 측정시 토양속에 돌이나 이물질 층이 형성되어 있는 경우에 콘 페니트로메타가 관입하다가 큰 관입저항 때문에 관입저항 한계설정치까지 가기전 더이상 관입을 못하는 경우가 발생하였다. (5) 성능실험시 관입심이 깊을수록 시험포장 전체에서 대체적으로 토양경도가 높은 것으로 나타났으며, 토양속의 돌이나 이물질 등에의해 경도가 급격히 증가하는 부분이 있는 것으로 사료된다. 이상의 결과에서 살펴보면 본 시스템은 토양경도 측정에 적절하다고 사료된다.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.7
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• pp.639-647
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• 2004

This paper concerns the analytical modeling and dynamic analysis of advanced rotating blade structure implemented by a dual approach based on structural tailoring and viscoelastic material technology. Whereas structural tailoring uses the directionality properties of advanced composite materials, the passive material technology exploits the damping capabilities of viscoelastic material (VEM) embedded into the host structure. The main structure is modeled as a composite thin-walled beam Incorporating a number of nonclassical features such as transverse shear. anisotropy of constituent materials, and rotary inertia etc. The VEM layer damping treatment is modeled by using the Golla-Hughes-McTavish (GHM) method, which is employed to account for the frequency-dependent characteristics of the VEM. The displayed numerical results provide a comprehensive picture of the synergistic implications of both techniques, namely, the tailoring and damping technology on dynamic response of a thin-walled beam structure exposed to external time-dependent excitation.

• Journal of Biosystems Engineering
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• v.36 no.6
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• pp.453-460
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• 2011

This study was carried out to test a red pepper tedding factors which is needed for design and development of an auto-tedding machine and a performance. According to this test, the results can be summarized as follows: The results of the tedding factors test according to shape of rotary blade, which is the 0.4 to 0.5 mm brush type, was found to be the most appropriate. As a result of tedding ratio which includes brush diameters, driving velocities and rotation velocities, there was generally no significance difference, but the red pepper tedding efficiency was found to be 39.7%. The moisture drying rate of red pepper was found to be 0.9 %w.b./h in prototype auto-tedding machine and 0.4 %w.b./h in traditional practice. The drying time was found to be 3 days in prototype auto-tedding machine and the traditional practice was 6 days. The average variable coefficient of the red pepper moisture content was found to be 16.8% in prototype auto-tedding machine in comparing with the traditional practice of 35.0%. This test showed a difference around two times, and this difference was evaluated to be the reason for irregular drying and different drying times.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.390-398
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• 2000

The purpose of this study was to evaluate the apical fitness of non-standardized gutta-percha cones in root canals prepared with rotary Ni-Ti root canal instruments of various tapers and apical tip sizes. Simulated sixty curved root canals of plastic blocks were prepared with crown-down technique using rotary root canal instruments of Maillefer ProFile$^{(R)}$ .04 and .06 taper (Maillefer Instrument SA, Switzerland). Specimens were divided into six groups and prepared as follows: Group 1, prepared up to size 25 of .04 taper ; Group 2, prepared up to size 30 of .04 taper ; Group 3, prepared up to size 35 of .04 taper ; Group 4, prepared up to size 25 of .06 taper ; Group 5, prepared up to size 30 of .06 taper ; Group 6 ; prepared up to size 35 of .06 taper. After cutting off the coronal portion of plastic, blocks perpendicular to the long axis of the canal with the use of a diamond saw, apical 5mm of canal space was analyzed. Prepared apical canal spaces were duplicated using rubber base impression material to evaluate two dimensional total area of apical canal space. Various sized gutta-percha cones were applied in the 5mm-apical canal space, which were size 25, size 30 and size 35 standardized gutta-percha cone, Diadent Dia-Pro ISO-.04$^{TM}$ and .06$^{TM}$(Diadent, Korea), and medium-fine (MF), fine (F), fine-medium (FM) and medium (M) sized non-standardized gutta-percha cones (Diadent, Korea). Coronal excess gutta-percha were cut off with a sharp blade. Photographs of impressed apical canal spaces and gutta-percha cones were taken with a CCD camera under a stereomicroscope and stored in a computer. Areas of the total canal space and gutta-percha cones were calculated using a digitalized image analysing program, CompuScope (Sungjin Multimedia Co., Korea). Ratio of apical fitness was obtained by calculating the area of gutta-percha cone to the total area of the canal space. The data were analysed statistically using One-way Analysis of Variance and Duncan's Multiple Range Test. The results were as follows: 1. In canals prepared up to size 25 ProFile$^{(R)}$ of .04 taper, non-standardized MF and F cones occupied significantly more canal space than Dia-Pro ISO-.04$^{TM}$ or size 25 standardized ones (p<0.05). 2. In canals prepared up to size 30 ProFile$^{(R)}$ of .04 taper, non-standardized F cones occupied significantly more canal space than Dia-Pro ISO-.04$^{TM}$ or size 30 standardized ones (p<0.05), and non-standardized MF cones occupied more canal space than size 30 standardized ones (p<0.05). 3. In canals prepared up to size 35 ProFile$^{(R)}$ of .04 taper, there was no significant difference in canal space occupation among non-standardized MF and F, size 35 standardized, and Dia-Pro ISO-.04$^{TM}$ cones (p>0.05). 4. In canals prepared up to size 25 ProFile$^{(R)}$ of .06 taper, non-standardized MF and F cones occupied significantly more canal space than Dia-Pro ISO-.06$^{TM}$, or size 25 standardized ones (p<0.05), and Dia-Pro ISO-.06$^{TM}$, cones occupied significantly more space than size 25 standardized ones (p<0.05). 5. In canals prepared up to size 30 ProFile$^{(R)}$ of .06 taper, non-standardized FM cones occupied significantly more canal space than Dia-Pro ISO-.06$^{TM}$ or size 30 standardized ones (p<0.05), and non-standardized F cones occupied significantly more canal space than size 30 standardized ones (p<0.05). 6. In canals prepared up to size 35 ProFile$^{(R)}$ of .06 taper, non-standardized M and FM, Dia-Pro ISO-.06$^{TM}$ occupied significantly more canal space than size 35 standardized ones (p<0.05). In summary, in both canals prepared with .04 or .06 taper ProFile$^{(R)}$, non-standardized cones showed better fitness than Dia-Pro ISO$^{TM}$ or standardized ones, which was more characteristic in smaller canals.

• Weed & Turfgrass Science
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• v.2 no.3
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• pp.322-326
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• 2013

This study was tried to control the weedy rice using minimum tillage direct seeding of rice on dry paddy. Minimum tillage direct seeding on dry paddy is tilled with 4 cm in width at 27 cm intervals by 1-shaped rotary blade. Using this cultivation method can control weedy rice effectively by minimizing the soil disturbance. In this study, weedy rice was firstly emerged at April 28 in 2012. After 11 days emergence rate of weedy rice at May 9 was 61.9%. At this time rice was sown and then herbicides was treated at 10 and 15 days after sowing. When herbicides was treated at 10 days after sowing the control effect was 89-96%, and when treated at 15 days the control effect was 97-99%. However emergence of weedy rice differ according to the year and year. It was thought to be affected by April average temperature and total precipitation. So, for effective weedy rice control and stable rice yield, it was considered that irrigation at April 15-20 to induce the emergence of weedy rice is required.