• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.10
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• pp.1419-1426
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• 2002

An experimental study was made to elucidate critical heat flux(CHF) characteristics in a two-phase concentric-tube thermosyphon. The experiment was performed by using saturated water, over the experimental range of configuration: inner diameter of heated outer tube D=12mm, outer diameter of unheated inner tube do=3 to 10mm and heated tube length L=100 to 1000mm. The experiment shows that the CHF is enhanced with increase in the inner tube diameter, and that the CHF decreases beyond a certain diameter of the inner tube. There is an optimum diameter for inner tube that maximizes the CHF, for each tube length and test liquid. The CHF maximum is about two to eight times as large as that without an inner tube. For a large inner tube, the CHF characteristics is similar to that for natural convective boiling in a vertical annular tube.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.5
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• pp.69-76
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• 2008

Inner diameter of bearing race is automatically measured by complete inspection system after grinding process. Contact type three points supporting method is widely applied to automatic inner diameter measurement because of its excellent stability. However, the geometric consideration regarding three points supporting method is not sufficient. In this study, the error equation from geometric error analysis of three points supporting method is found. The effect of factors in the error equation is also investigated. The error equation is linear for difference of diameter in sample and master on range of tolerance. An error becomes more and more larger, when the distance of two supporting balls or the diameter of supporting ball are increased. In the result, some considerations are proposed for measurement of inner diameter by the three points supporting method.

• Korean Journal of Veterinary Research
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• v.40 no.2
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• pp.373-381
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• 2000

Serial ultrasonographic examinations were performed on pregnant Korean Jindo bitches. Measurements of inner chorionic cavity diameter and fetal head diameter were made from pregnancy day 15 to parturition. These measurements were converted retrospectively based on the day of parturition (day 0). The data of inner chorionic cavity diameter obtained from day -42 to day -25 and fetal head diameter obtained from day -24 to day -1 were used to prediction of parturition day. Formulas for the prediction of parturition day using the method of least squares were derived. These formulas were then used to predict parturition dates based on single measurements of inner chorionic cavity diameter or fetal head diameter in 17 additional pregnant Korean Jindo bitches. Predicted date of parturition was then compared to actual whelping date. In the prediction of parturition based on inner chorionic cavity diameter, 7 of 10 bitches were coincided prediction date and actual whelping date, and the prediction was accurate to within 1 day in 3 of 10 bitches. The prediction of parturition based on fetal head diameter was accurate to within 1 day in 6 of 7 bitches and within 2 days in 1 of 7 bitches. In conclusion, the ultrasound measurement of inner chorionic cavity diameter and fetal head diameter are practical and accurate tool in the prediction of parturition.

• Transactions of Materials Processing
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• v.4 no.3
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• pp.257-266
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• 1995

A simulation method based on upper bound method is developed in order to characterize forging characters in forging of spur gears. In this paper, utilizing a kinematically admissible velocity field and applying it to investigate the effect of inner diameter of holow billet. In the analysis, to predict the variation of inner diameter of hollw billet, neutral surface has been introduced. The neutral surface of each step is assumed as a circle and determined in order to have minimum forging energy by golden section method. By this method, the variation of inner diameter of billet during spur gear forging is successfully predicted. As a result, the selection of inner diameter of initial billet is very important to reduce the forging load.

• Journal of the Korean institute of surface engineering
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• v.51 no.1
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• pp.27-33
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• 2018

In the present work, we demonstrate the feasibility to form large inner diameter $TiO_2$ nanotubes by anodization of Ti in a HF/ethylene glycol electrolyte. In order to achieve the large inner diameter $TiO_2$ nanotubes, optimization of the anodization condition is required. We discover the key factors in the formation of large inner diameter $TiO_2$ nanotubes are concentration of water in the electrolyte, anodization temperatures, and high-applied potential. Under optimum conditions, the inner diameters of $TiO_2$ nanotubes are 379 nm. The results are approximately 3 folders larger than the general case.

• Design & Manufacturing
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• v.16 no.3
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• pp.16-21
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• 2022

In order to reduce the weight of parts and materials for the development of high-efficiency engines in accordance with the strengthening of automobile fuel efficiency regulations, the existing casting material is changed to a iron plate material, and plastic processing and turning operations are performed to lighten the weight and reduce the manufacturing cost. Among the pulley components applied to the damper pulley, the HUB product was manufactured by plastic machining instead of the existing casting process, and the inspection standardized for automating the inner diameter and parallelism measurement of the turning result of the new hub part with improved quality, and the inspection system for this Development of design and operation software to automate the inspection of the inner diameter and parallelism of the hub was described. The representative specifications of the development equipment are a hub inner diameter 22mm inspection system, a three-point inspection system with a parallelism of 0.15mm on the top.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.183-186
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• 1995

A simulation method basee on upper bound method is developed in order to characterize forging characters in forging of spur gears. In this paer, utlizing a kinematically admissible velocity field and applying it to study the effect of inner diameter of holow billet. To predict the variation of inner diameter of hollow billet, neutal surface has been introduced into forging of hollow gears from hollow billes with flat punch. The neutral surface of each step is assumed as a circle and determined in order to have minimum forging energy by golden section method. According to the analysis, the magnitude of inner diameter of initial billet is vary important to reduce the relative pressure and forging load. And the variation of inner diameter of billet during spur gear forging is successfully predicted.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.135-135
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• 2015

Tubes are of extreme importance in industries as for fluid channels or wave guides. Furthermore, some weapon systems such as cannons use the tubes as gun barrels. To increase the service life of such tubes, a protective coating must be applied to the tubes' inner surface. However, the coating methods applicable to the inner surface of the tubes are very limited due to the geometrical restriction. A small-diameter cylindrical magnetron sputtering gun can be used to deposit coating layers on the inner surface of the large-bore tubes. However, for small-bore tubes with the inner diameter of one inch (~25 mm), the magnetron sputtering method can hardly be accommodated due to the space limitation for permanent magnet assembly. In this study, a new approach to coat the inner surface of small-bore tubes with the inside diameter of one inch was developed. Instead of using permanent magnets for magnetron operation, an external electro-magnet assembly was adopted around the tube to confine the plasma and to sustain the discharge. The electro-magnet was operated in pulse mode to provide the strong axial magnetic field for the magnetron operation, which was synchronized with the negative high-voltage pulse applied to the water-cooled coaxial sputtering target installed inside the tube. By moving the electro-magnet assembly along the tube's axial direction, the inner surface of the tube could be uniformly coated. The inner-surface coating system in this study used the tube itself as the vacuum chamber. The SS-304 tube's inner diameter was 22 mm and the length was ~1 m. A water-cooled Cu tube (sputtering target) of the outer diameter of 12 mm was installed inside of the SS tube (substrate) at the axial position. The 50 mm-long electro-magnet assembly was fed by a current pulse of 250 A at the frequency and pulse width of 100 Hz and 100 usec, respectively. The calculated axial magnetic field strength at the center was ~0.6 Tesla. The central Cu tube was synchronously driven by a HiPIMS power supply at the same frequency of 100 Hz as the electro-magnet and the applied pulse voltage was -1200 V with a pulse width of 500 usec. At 150 mTorr of Ar pressure, the Cu deposition rate of ~10 nm/min could be obtained. In this talk, a new method to sputter coat the inner surface of small-bore tubes would be presented and discussed, which might have broad industrial and military application areas.

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.1
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• pp.29-38
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• 2004

The Condensation heat transfer coefficients of R-22 and R-l34a were measured in smooth horizontal copper tubes with inner diameters of 1.77. 3.36 and 5.35 mm. respectively. The experiments were conducted in a closed loop. which was driven by a magnetic gear pump. They were Performed for the following ranges of variables: mass flux (200 to $500\;kg/\textrm{m}^2{\cdot}s$) saturation temperature $30^{\circ}C$ and quality (0 to 1.0). The main results obtained are as follows Condensation heat transfer coefficients in the small diameter tubes (ID < 7 mm) were observed to be strongly affected by inner diameter change and to differ from those in the large diameter tubes. The heat transfer coefficients in the small diameter tubes were 20 ~ 40 % higher than those in the large diameter tubes as the inner diameter of the tube was reduced. Also. it was very difficult to apply some well-known previous predictions (Cavallini-Zecchin's. Haraguchi's and Dobson's correlation) to small diameter tubes. Based on an analogy between heat and mass transfer the new correlation is Proposed to predict the experimental data more accurately.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.06a
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• pp.3-4
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• 2007