• Restorative Dentistry and Endodontics
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• v.24 no.1
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• pp.222-232
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• 1999

The purpose of this study was to evaluate the effect of heated spreader on the sealing ability of lateral condensation, compared with regular cold spreader. Forty two extracted human teeth with single canal were randomly placed into 3 experimental groups, and four additional teeth were used as positive and negative controls. Each group was prepared with Ni-Ti Profile #40 using step-down technique and obturated with standardized colored gutta-percha cone by standard(cold) lateral condensation technique, warm lateral condensation technique with Endotec and hot spreader soaked in glass bead sterilizer, each with Sealapex sealer. Control groups were not obturated, but prepared. After 2 days in 2% methylene blue, the teeth were invested and made into transparent resin blocks. And then, each block was sectioned horizontally with microtome at 1, 2, 3, 4, 5 mm levels from the apex. The linear extent of dye penetration was examined with stereomicroscope at ${\times}$20 magnification. At each of 5 levels, ratio of the area of gutta-percha was obtained by calculating the area of gutta-percha to the total area of the canal. The data collected were then analyzed statistically using an analysis of variance(ANOVA) and Scheffe test. The results were as follows ; 1. All experimental groups produced the apical microleakage. 2. The mean leakage was 1.57${\pm}$0.76mm for cold spreader group, 0.86${\pm}$0.95mm for Endotec spreader group, and 0.64${\pm}$0.93mm for hot spreader group. The difference between hot spreader group and cold spreader group was statistically significant(p<0.05). 1. At the 1 mm level, the mean ratio of area of gutta-percha was 74.58${\pm}$13.15(%) for cold spreader group, 65.42${\pm}$14.62(%) for Endotec spreader group, and 80.72${\pm}$14.63(%) for hot spreader group. There was statistically significant difference between hot spreader group and Endotec spreader group(p<0.05). 2. At the 2mm level, the mean ratio of area of gutta-percha was 87.86${\pm}$11.22(%) for cold spreader group, 66.55${\pm}$14.02(%) for Endotec spreader group, and 92.93${\pm}$7.24(%) for hot spreader group. There was statistically significant difference between Endotec spreader group and other two spreader groups(p<0.05). 3. At the level 3, 4, 5 mm, there was no statistically significant difference between each group. Within the limits of the results of this experiment, warm lateral condensation technique with hot spreader soaked in a glass bead sterilizer demonstrated favorable apical sealing effect and improved density of gutta-percha mass. Thus, it is thought that this obturation technique is effective for clinical use and beneficial to reduce condensation forces, also economical and easy. Lateral condensation, Heated spreader, canal sealing, Microleakage.

• Restorative Dentistry and Endodontics
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• v.19 no.2
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• pp.461-472
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• 1994

The purpose of this study was to evaluate the sealing ability according to types of spreader and compatibility of accessory cone used in lateral condensation method. 120 plastic blocks with canal preformed were instrumented with K-,H-files and Gates-Gllidden bur. Shaped plastic blocks were divided into six experimental groups according to spreader and accessory cone used in lateral condensation. Then they were obturated by lateral condensation method without -sealer. Six experimental groups were as follows: Group 1 : Filling with #30 spreader & #25 gutta-percha cone Group 2 : Filling with #30 spreader & Fine accessory cone Group 3 : Filling with #3 spreader & #25 gutta-percha cone Group 4 : Filling with #3 spreader & Fine accessory cone Group 5 : Filling with #20,#30 spreader & #25 gutta-percha cone Group 6 : Filling with #2, #3 spreader & Fine accessory cone All the blocks were stored in 100% humidor at room temperature for 2 days. Each block was placed in centrifuged for 20 minutes at 3,000 rpm. Apical leakage was mesured from the apical foramen to the most coronal level of- dye leakage in millimeter under a stereoscope. The data were analysed by ANOVA. The obtained results were as follows; 1. In groups using two spreaders(Group 5,6), the linear leakage was less than one spreader using groups(Group 1-4). 2. Tn groups using two spreaders(Group 5,6), there was no significant difference in linear leakage between standardized -spreader group and non standardized group (p>0.01). 3. When one spreader was used(Group 1-4), standardized-spreader groups showed less linear leakage than nonstandardized spreader groups(P<0.01). 4. In case of using same spreader(Groupl,2 & Group 3,4), there was no significant difference in linear leakage according to accessory cone type. 5. It needs to use one more spreaders to increase apical sealability.

• Journal of Animal Environmental Science
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• v.7 no.2
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• pp.119-126
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• 2001

For the odor test, it was chosen the conventional spreader, the hose spreader, and its combination with disk harrow and spring harrow as a slurry spreader. By the odor tester (Kalmor-$\sum$) with dairy slurry, the conventional spreader has the average $\sum$ value of 270, which means that one fells substantial odor and torment. In the cases of hose spreader and its combination with disk harrow, $\sum$ value was 217 and 182 respectively, which means a normal person does not smell any odor. Spreading the swine slurry with a conventional spreader shows $\sum$ value of 440, which means one feels unpleasant. The hose spreader shows $\sum$ value of 258, which lies in the limit one feels some odor and torment. Its combination with disk harrow has $\sum$ value 184, which means that a normal person can not smell any more. For the conventional spreader, the odor intensity indices from air dilution sensual test and 3 point odor bag as a sensual test were 66.9 and 35.4 respectively. On the other hand, the indices were 9.65 and 11.10 by hose spreader and its combination with disk harrow, which were lower than that of the regulation for industry. Therefore, the developed hose spreader showed an excellent effect on decreasing odor. The correlation between the results from odor tester and 3 point odor bag has shown 0.997 by swine slurry.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.9
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• pp.861-867
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• 2007

A spreader pose control system using dual-electric compasses has been implemented by measuring the skew angle of the spreader with dual-electric compasses. In the conventional spreader pose measurement, CCD cameras, laser sensors or tilt sensors are mostly used. However those sensors are not only sensitive to the weather and disturbances but also expensive to build the system. To overcome the shortcomings, an inexpensive and efficient system to control the spreader pose has been implemented using the dual-magnetic compasses. Since the spreader iron-structures are noise sources to the magnetic compass, it is not considered to use the magnetic compass to measure the orientation of the spreader. An algorithm to eliminate the interferences of metal structures to the dual compasses has been developed in this paper. The 10:1 reduction model of a spreader control system is implemented and the control performance is demonstrated to show the effectiveness of the dual-magnetic compasses proposed in this research.

• Proceedings of the KIEE Conference
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• 2007.04a
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• pp.366-368
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• 2007

A spreader pose control system using dual-electric compasses has been implemented by measuring the skew angle of the spreader with dual-electric compasses. In the conventional spreader pose measurement, CCD cameras, laser sensors or tilt sensors are mostly used. However those sensors are not only sensitive to the weather and disturbances but also expensive to build the system. To overcome the shortcomings, an inexpensive and efficient system to control the spreader pose has been implemented using the dual-magnetic compasses. Since the spreader iron-structures are noise sources to the magnetic compass, it is not considered to use the magnetic compass to measure the orientation of the spreader. An algorithm to eliminate the interferences of metal structures to the dual compasses has been developed in this paper. The 10:1 reduction model of a spreader control system is implemented and the control performance is demonstrated to show the effectiveness of the dual-magnetic compasses proposed in this research.

• Journal of Animal Environmental Science
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• v.12 no.3
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• pp.151-160
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• 2006

For even distribution of liquid manure in the field, a boom nozzle type spreader was designed and studied to determined its suitability for small scale crop production farms. Boom nozzle type spreader was compared in the impact triple nozzle and impact single nozzle type spreader. Spreading uniformity of the boom nozzle type liquid manure spreader showed 5.2% (C.V.) and impact single nozzle type spreader showed 6.9% (C.V.). The spreading uniformity of the impact triple nozzle type spreader was quite uneven, therefore, the spreader could be modified as twin nozzle for spreading in orchard farm. The wheel axle height adjustable type liquid manure spreader has higher the stability and it considered much useful on the hilly agricultural land.

• Proceedings of the KIEE Conference
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• 2006.04a
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• pp.339-341
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• 2006

This paper proposes a method of container position measurement using automatic landing system that is estimated by a laser range finder. In the most of container position measurement methods, CCD cameras or laser scanners have been used to get the source data. However those sensors are not only weak for disturbances, for examples, the light, fog, and rain, but also the system cost is high. When the spreader arrives the goal position, it is still swung by inertia or by wind effect. In this paper, the spreader swung data have been used to find the container position. The laser range finder is equipped in the front side of spreader. It can measure distance and relative position between spreader and container. This laser range finder can be rotated as desired by a motor. And a tilt sensor is equipped on the spreader to measure spreader sway. We estimate the relative position information between the spreader and a container using the laser range finder and tilt sensor through the geometrical analysis.

• Restorative Dentistry and Endodontics
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• v.25 no.3
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• pp.381-389
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• 2000

Lateral condensation with gutta-percha and sealer has been shown to provide an excellent apical seal; however, the lateral condensation technique has demonstrated less favorable apical leakage results in curved canals when compared with straight canals. Placement of endodontic spreaders to within 1 to 2mm of the root canal working length has been advocated for optimum gutta-percha obturation. Due to their stiffness, stainless-steel(SS) spreaders will often fail to achieve this position in curved canals. Newly marketed nickel-titanium(NT) spreaders may offer an advantage in this regard due to the increased flexibility of these instruments. The purpose of this study was to evaluate the effect of NT finger spreader on the sealing ability in lateral condensation technique, compared with conventional SS finger spreader. Twenty four standardized resin models simulating curved canals(30 degree) were randomly placed into 2 groups and instrumented to a #30 master apical file size with Ni-Ti Profile .04 taper series using step down technique. Each groups was obturated with standardized gutta-percha cone by standard lateral condensation technique using SS finger spreader, NT finger spreader. And then, each model was sectioned horizontally with microtome at 1, 2, 3, 4, 5mm levels from the apex. At each of 5 levels, ratio of the area of gutta-percha was obtained by calculating the area of gutta-percha to the total area of the canal. The data collected were then analyzed statistically using a t test for independent samples. The results as follows ; 1. The total mean ratio of area of gutta-percha was 89.20${\pm}$7.00(%) for SS spreader group. 92.20${\pm}$5.17(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). 2. At 3mm level, the mean ratio of area of gutta-percha was 88.32${\pm}$5.41(%) for SS spreader group, 95.25${\pm}$2.60(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). At 1,2,4mm levels, NT spreader group showed greater mean ratio of area of gutta-percha than SS spreader group, too. But there was no statistically significant difference. 3. At 5mm level, the mean ratio of area of gutta-percha was 91.83${\pm}$3.42(%) for SS spreader group, 87.91${\pm}$3.68(%) for NT spreader group. There was statistically significant difference between each group(p<0.05). This study concluded that the NT spreader demonstrated somewhat favorable apical sealing effect than SS spreader in prepared curved canals. The clinical use of NT spreaders may enhance our ability to create better apical seals in curved canals, but further studies in this area will help clarify some of the remaining areas with which practitioners are concerned, such as compaction forces exerted by NT spreaders.

• Journal of the Korean Solar Energy Society
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• v.31 no.4
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• pp.95-102
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• 2011

In this paper, the thermal performance of a heat spreader module for CPV(Concentrating Photovoltaic) cooling is experimentally investigated. In order to evaluate the thermal performance of the heat spreader module which consists of a Metal PCB and an aluminum alloy heat spreader, experiments are conducted with varying the type of the metal PCB, the thickness of the heat spreader, the inclination angle, and the applied heat flux. To validate the experimental data, three dimensional numerical simulations are performed using the commercial simulation tool in the present work. The experimental results are compared with the corresponding numerical results and are in close agreement with the numerical results. From the experimental results, the temperature difference between the maximum temperature and the ambient temperature increases with decreasing the thickness of the heat spreader and with increasing the applied heat flux. Also, it is found that the inclination angle significantly affects the thermal performance of the heat spreader. the maximum temperature difference of the heat spreader with the horizontal orientation is much larger than that with the vertical orientation.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1258-1263
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• 2004

The present study proposes a new structure for a heat spreader which could embody a thin thickness, any shapes and high heat flux per unit area. It is on the structure for the formation of vapor passages and the support of the case of the heat spreader. A screen mesh is used as the one. To verify the validity of the one, the heat spreader of 1.4mm and 1.6mm thickness was made with 14 mesh and 100 mesh number. In this paper, The performance test of heat spreader conducted in order to compare with the heat transfer performance of conventional heat pipe. As the results, The heat spreader has excellent cooling and heat transfer performance.