• Journal of Biosystems Engineering
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• v.13 no.2
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• pp.18-27
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• 1988

The basic model of impeller was developed for the theoretical analysis of performance. The developed model was tested with two different blade radius of curvature based on the pumping efficiency under the operating conditions in Korea. And the pump performance of the impeller was also tested for the various speeds. The results obtained are summarized as follows; 1. There was no significant effect on the different blade radius of curvatures on the discharge and pump efficiency. 2. Head and power requirement was increased in proportion to the blade radius of curvature. 3. In the mathematical approach of the blade radius of curvature, the method of involute curve was more recommendable as compared with the method of circular arc curve. 4. The pump efficiency of the model impeller developed based on the theoretical analysis increased about 10% more than that of the existing impeller.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.1614-1621
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• 2008

I accomplished a curve section traveling safety assessment analysis followed with railway condition for elevation of a curve passage speed of train utilizing trail analysis model. As a result, we confirmed that excess cant influence in badly traveling safety of train followed with cant change and cant shortage influence in badly traveling safety in case of large a curve radius and traveling safety of originally a curve section is most wrong. Also we confirmed that shortage of relief a curve length influence in badly traveling safety followed with change of relief a curve length.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05e
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• pp.15-18
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• 2003

In this paper, We explained the best shape design of electrode for discharge on the water. Electrode with rounding was reduced maximum electric field of over 40% to electrode without rounding for discharge on the water and the best shape of electrode for discharge on the water designed when shape of electrode had a curve radius of over $60^{\circ}$ at electrode's face to electrode's face with minimum distance and a curve radius of under $120^{\circ}$ at electrode's side face to electrode's front face. And When dielectric beads are used between electrodes, the life of electrodes is improved by lower stress of electric field on surface of electrodes.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.823-829
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• 2005

The extent of slack is correlative with the wheelbase of vehicle as well as the distance between the inner faces of flanges. Since the movable clearance of wheel flange is getting reduced in curved track, the vehicle is more difficult to negotiate the track. By this reason, a certain extent of slack is normally designed for curved track to allow the movable clearance corresponding to that of straight track. In case of some foreign railways,. the fixed extent of slack has been classified by the ranges of curve radius. In case of KNR, the slack is calculated by a formula for each case of curve radius and it therefore seems quite precise method. However, since there is a wide range of slack adjustment $(S'=0\~15mm)$ in calculation formula itself, too excessive or too little slack can be calculated. This study is to approach the technical review on slack calculation and to offer the reasonable slack design through the full-scale experiment at sharp curved track without slack.

• Journal of Korean Ophthalmic Optics Society
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• v.5 no.2
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• pp.65-72
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• 2000

The study investigated the effects of base curve radius art the fit of thin, mid-water contact lenses. It was found that central corneal curvature(as measured with the keratometer) was not predictive of the best fitting base curve. Proper lens fit may be the single most important factor that ultimately determines the success of contact lens wear. Comfort, vision, and physiological response are all dependent on the fit of the lens. The percent of optimal fits was highest with the 8.4 mm base curve lens for all three ranges of keratometry values. When fit with the 8.4 mm lens. For most eyes, fitting a flatter lens led to greater decentration, decreased comfort, and no increase in lens movement. The 8.4 mm lens was found to provide on "optimal" fit in over 60% of eyes tested and a fit of "good" or "better" in nearly 90% of eyes tested. Comparisons of different manufactures' lens found that similiar lenses do not always fit in the same way due to subtle design and production differences. Therefore, different products may require different base curve radii to fit the same patient. This is even true when water content, center thickness, and diameter are approximately the same. A praditioner fitting a new patient in this lenses should begin with the 8.4 mm base curve radius.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.113-119
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• 2000

There are two major factors which affect the cam design : the pressure angle and the radius of curvature, Cam shape will have an instantaneous radius of curvature at every point. Even though the design constraint of the pressure angle has been satisfied the follower may still not complete the desired contact motion. If the radius of the follower roller is larger than the concave(negative) radius on the cam it occurs the gap between the cam and the follower roller at the contact point. And also if the curvature of the pitch curve of the cam is too sharp the cam profile may be undercut. This paper proposes a new approach which uses the relative velocity of the follower roller parallel to the tangent line at the contact point on the cam surface for determining the pressure angle and the relative acceeration for determining the radius of curvature.

• Proceedings of the KOR-KST Conference
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• 2007.05a
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• pp.620-629
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• 2007

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.222-227
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• 2004

Korean High Speed Train(KHST) has been tested on the high speed test line in Osung site, since it was developed through the G7 Project Plan in 2002. It was also tested on the conventional line such as KyongBu and Honan Line to know the possibility of increasing the limited speed for the high speed trains. This paper introduces the method to improve the speed on the conventional line with body lateral acceleration among the several considered issues and explains the parameters related to those analysis, such as the cant deficiency, the radius of curve, speed and etc. When a train pass on the curved track, the lateral accelerations of body are divided into the quasi-static and the maximum accelerations according to the UIC 518 which is the international specification for testing and approval of railway vehicles from the point of view of their dynamic behaviour, especially for safety and ride comfort. This paper shows that it is safe and comfort from the results of test when KHST runs on the conventional line with the curves and proposes that the limited speed of conventional curved line could be changed to a little higher speed if the analysises of other fields are completed.

• The Bulletin of The Korean Astronomical Society
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• v.36 no.1
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• pp.28.1-28.1
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• 2011

We observed the transiting exoplanet, TrES-2b, with 1.5m telescope at Maidanak Observatory in Uzbekistan. We observed TrES-2 system for six nights, which contained two orbital periods of the planet. Therefore, we obtained the entire light curve of TrES-2b, which covered not only the whole primary transit containing both ingress and egress part, but also non-transit region. We used both R and Y band filters. Especially, Y filter is used first for transit observation and covers relatively longer wavelength ($1.02{\mu}m$ of center wavelength), to provide the light curve less affected by limb darkening. By fitting best model light curve for the obtained one, we determined these observables, transit depth, transit length, and planet's orbital period, which led to the determination of five physical parameters, stellar radius R*, stellar mass M*, inclination i, semi-major axis a, and planetary radius Rp. We will discuss of these results.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.637-643
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• 2014

Recently there have been an increasing amount of bicycle accidents along with the increased usage of bicycles. Bicycle accidents occur frequently by perpendicular collision at the inner intersection. Bicycle traffic is especially concentrated in residential areas and around schools which results in the vulnerability of cyclists. This paper is to inform the potential risks of collisions between bicycles and cars turning right at the intersections using simulation analysis which focuses on the pavement edge of intersection geometric designs factor and checks on the drivers behavior. The result of the analysis shows that as the curve radius of pavement edge at the intersection becomes larger and the more attention drivers are paying to the rear by turning their heads to the right, the potential risk of collisions between bicycles and cars turning right will decrease.