• Transactions of the Korean hydrogen and new energy society
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• v.24 no.6
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• pp.487-494
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• 2013

In this study, solutions for a liquid pool spreading model with continuous and instantaneous release are discussed based on the model used in the FERC's report. The effects of the release time on the liquid pool volume and radius are investigated for the continuous release. For the continuous release with the frictional resistance force in the liquid pool spreading model, the vaporization time decreases as the release time increases. On the other hand, for the continuous release without the frictional resistance force in the liquid pool spreading model, the vaporization time increases as the release time increases. These phenomena are deeply related to the pool radius. In addition, the effects of the initial pool radius for the instantaneous release in the liquid pool spreading model are discussed. For the case with the frictional resistance force in the liquid pool spreading model, as reducing release time in the model with the frictional resistance force for the continuous release, the solution for a continuous release approaches to that for an instantaneous release. On the contrary to this, the pool volume and radius for the instantaneous release without the frictional resistance force are totally different from those for the continuous release without the frictional resistance force.

• Journal of the Korean Geotechnical Society
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• v.36 no.11
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• pp.107-117
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• 2020

Open-ended steel pipe piles have outside frictional force and inside frictional resistance in which blocked soil acts on the inside of the steel pipe during installation. It is expected that the ultimate load will change depending on the inside and outside resistance. And, if the ground on which the piles were constructed is clay soil, it is predicted that it will have effect on the negative skin friction caused by the ground settlement. Therefore, in this study, the behavior according to the inside and outside resistance characteristics of steel pipe piles was analyzed numerically, and the frictional force distribution, axial load and settlements before and after the occurrence of ground settlement were calculated. As a result of the analysis, the inside frictional resistance had less influence than the outside frictional resistance. However, inside frictional resistance is considered to be one of the important factors considering the effect on the overall pile behavior, and both resistance factors need to be considered in the design process.

• The korean journal of orthodontics
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• v.21 no.3
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• pp.543-560
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• 1991

Practitioners are aware of the presence of friction between bracket system and archwire during sliding movement of teeth. Clinically a mesiodistally applied force must exceed the frictional force to produce a tooth movement. The objective of this study were to determine, on a dry condition, changes in magnitude of friction with respect to load, 3rd order inclination (Torque), archwire materials and ligature type. Three wire alloys (Stainless Steel, TMA, NiTi) in two wire sizes (.016, .016x, .022 inch) were examined respect to two bracket system (Straight, Standard), and two ligature type (Metal, Plastic ligature) at three levels of load (100g, 150g, 200g). The results were as follows; 1. Frictional resistance was found to increase with increasing load for S.S., TMA, NiTi. 2. The straight bracket system was exhibited more frictional force than standard bracket system for .016x, .022 S.S. tightly ligated metal ligature. But, torque difference did not increase friction for loose metal ligature & plastic ligature. 3. Regardless of the ligature type, torque and load, stainless steel wire sliding against stainless steel exhibited the lowest friction, and TMA sliding against stainless steel exhibited the highest friction. 4. The loose stainless steel ligature generated lower frictional resistance than plastic ligature in all experimental groups. 5. The following factors affected friction in decreasing order; wire material ligature type, and load.

• The korean journal of orthodontics
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• v.23 no.4 s.43
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• pp.671-691
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• 1993

To estimate the possibility in the application of TiN ion-plating to the orthodontic appliance, this study investigated frictional force and frictional coefficient between non-ionplated and TiN ion-plated to the orthodontic appliance. The obtained results were as follows : 1. For each group, the frictional force between metal bracket and arch wire in the wet condition was exhibited lower than that in the dry condition. 2. In the dry condition, the frictional force was lowest with fourth group, and it increased in the order of the 3rd, 1st, and 2nd group. Same situation happened in the wet condition. 3. Experimental results using ceramic & plastic bracket showed that group B was lower than group A, and group D was similar to group C. 4. The surface texture after experiment showed that the scratch due to a friction with bracket was observed in an arch wire of dry contition. Also the surface of bracket was rougher than before. 5. We observed that a specimen surface processed with the TiN ion plating was smoother than that of without the TiN ion plating. 6. The surface texture of a metal bracket and an arch wire in the wet condition was observed smoother than that in the dry condition. 7. In the dry condition, the friction coefficient of each specimen was very similar to each other, but in the wet condition, the friction coefficient of specimen processed with the TiN ion plating showed lower values.

• Geotechnical Engineering
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• v.14 no.6
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• pp.139-151
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• 1998

SI anchor means the soil improvement anchor. The ground for supporting anchor is improved by JSP, and as a result, SI anchor body has about 80cm in diameter. SI anchor shows high pullout resistance by the frictional force between anchor body and ground, and the bearing capacity of anchor body. Especially the frictional force increases very much with increasing diameter of anchor body improved by JBP. In this study, model and field tests are made to analyse the mechanism of pullout resistance of SI anchor. Through model tests for the SI anchor in air dried sandy ground, strain fields of ground around SI anchor surface are analysed by a photo analysis method using the latex membrane on the wall of soil tank. The results of field tests are analysed by the strains measured by 10 strain gages attached on the inner wall of specially designed PVC pipe embedded in anchor body, and the strains of anchor body are also measured in the model tests.

• The korean journal of orthodontics
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• v.37 no.2 s.121
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• pp.137-149
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• 2007

Objective: The purpose of this study was to compare changes in frictional resistance between the bracket and wire under dry and wet conditions according to a change in moment. Methods: A stainless steel bracket of $0.022"{\times}0.028"$ slot, and $0.019"{\times}0.025"$ stainless steel, beta-titanium, and nickel-titanium wires were used. A 10 mm length lever was attached to the test (sliding) brackets to generate a moment. The experimental model was designed to allow tipping until contacts were established between the wire and the mesiodistal edges of the bracket slot. The moment was generated by suspending a 100 g or 200 g weight on the end of the lever. The moments applied were $1000g{\cdot}mm\;(100g{\times}10mm)\;and\;2000g{\cdot}mm\;(200g{\times}10mm)$. The test brackets were ligated with elastomeric ligature for a constant ligation force and the fixed brackets were ligated with stainless steel ligature. Brackets were moved along the wire by means of an universal testing machine, and maximum frictional resistances were recorded. Results: Stainless steel wire showed least frictional resistance and there was no significant difference between beta-titanium and nickel-titanium except at $2000g{\cdot}mm$ moment in wet conditions. Frictional resistance of all wires increased as the moment increased from $1000g{\cdot}mm\;to\;2000g{\cdot}mm$. Under wet conditions, the frictional resistance of stainless steel wires increased in both $1000g{\cdot}mm\;and\;2000g{\cdot}mm$ moment conditions, but frictional resistance of nickel-titanium and beta-titanium increased only in $2000g{\cdot}mm$ conditions. Conclusion: These results indicated that various conditions influence on frictional resistance. Therefore, laboratory studies of frictional resistance should simulate clinical situation.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.101-106
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• 2005

During braking at a train, thermal energy is generated due to the frictions between disk and lining and wheel and shoe. In general, the braking transfers the kinetic energy into thermal energy. Therefore. the frictional characteristics are varied according to the braking force, the thermal resistance, and the thermostable, etc. Using a Dynamo testing we have studied the frictional characteristics and the thermal distribution to investigate a stable speed and to improve the testing method through comparing and analysing in the measurement or the thermocouple temperature and infrared camera.

• Elastomers and Composites
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• v.55 no.3
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• pp.161-166
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• 2020

On the basis of the use of shoes, the outsole, which is mainly made of rubber, has various characteristics. The most important of these characteristics is abrasion resistance and friction. Generally, the abrasion resistance can be improved by adding more reinforcing filler such as silica to the rubber; however, the friction force drops. Owing to these problems, rubber having excellent abrasion resistance and rubber having excellent frictional force are blended. In this study, various characteristics, including wear resistance and friction, were evaluated by blending NBR/SBR or NBR/BR mixture with high wear resistance and CIIR with high friction. The CIIR was increased up to 60 phr, whereas the friction wear characteristics were rapidly changed in the NBR/CIIR blend ratio from 75:15 to 60:30.

• The korean journal of orthodontics
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• v.29 no.1 s.72
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• pp.107-112
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• 1999

As increasing number of adult patients, the esthetic orthodontic appliances are needed. They are tooth-colored or translucent ceramic and resin brackets. Although ceramic and resin bracket have good esthetics, there are some disadvantage such as frictions. Recently, metal-reinforced resin bracket(MRBB) were introduced. The purpose of this study is to find frictional force of MRRB, ceramic bracket and resin brackets. There is few study in frictional force about metal reinforced resin bracket(MRRB). This study used 4 orthodontic wire(.016 S-S, .0l6X.022 S-S, .016 $TMA^{\circledR}$, .0l7X.025 $TMA^{\circledR}$ and 5 brackets(one metal bracket, one ceramic bracket, one resin bracket, two MRRB). The following result is obtained using metal bracket(Ormco.Co., U.S.A), ceramic brackets($Crystalline^{\circledR}$), resin bracket( Clear Medium $Siamase^{\circledR}$). Following conclusions are obtained. 1. Ceramic and resin bracket have significantly more frictional forces than metal reinforced resin bracket and metal bracket. 2. There is no significant difference in frictional force according to the slot types of metal - reinforced resin brackets. 3. There is no significant difference in frictional force between metal reinforced resin bracket and metal bracket. 4.. Frictional force is decreased in S-S wire than TMA wire.

• Journal of the Korean Society for Marine Environment & Energy
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• v.16 no.3
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• pp.211-216
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• 2013

Most of hull resistance prediction methods which are used to calculate the towing force of disabled ships are very simple and old-fashioned. In particular, in cases of barge ships, a method similar to the US Navy Towing Manual is being used. This paper reviewed the US Navy Towing Manual and the notification method of Korea Ministry of Oceans and Fisheries and proved that these prediction methods are irrational and inaccurate. Furthermore, a new Modified-Yamagata-Barge method is introduced as a more rational and accurate resistance prediction method which can be applied in case of barge ships.