• Korean Journal of Applied Biomechanics
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• v.17 no.1
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• pp.41-52
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• 2007

The present study analyzed the two hand backhand stroke motion of six female high school tennis players who won the championship at the National Athletic Meeting in 2006, and drew conclusions as follows. The open angle of the racket at the moment of impact was 90 degree without significant difference among the players, making a wide contact between the ball and the racket. The racket angle was 43 degree at take back and 91 at impact, showing a style of holding the racket rather upright in general. In back swing from the top to the impact, the shoulders and the hips turned by 97 degree and 40 degree, respectively. At the moment of impact, the height of the impact was 54%H, and the position of the impact was 10%H ahead of and 37%H left from the central axis of the body. The right hand made a continental grip and the left hand made a Western or semi Western grip. Through the entire swing motion, the grip angle of the left hand was smaller than that of the right hand, and those who maintained a large grip angle of the right hand at the moment of take back put the racket head slightly farther from the body. In the swing of the racket head from the lowest point to the impact, the vertical length of movement was 11%H and the horizontal length of movement was 60%H, quite long.

• Journal of the Korean Home Economics Association
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• v.36 no.6
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• pp.41-56
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• 1998

The Yo-Dae(belt) was made of cloths and leather orginally. Then, it was decorated with metal decoration to become more developed luxury one. The Kwa-Dae of the Three Kingdom period is called as final shape among those ancient mode. Dae-Gu(The origin of belt buckle) was the metallic decoration of the leather belt that the northern nomadic tribe used to wear it. It was considered that the Dae-Gu was more decorated and changed to Kwa-Dae with Yo-Pae. The first stage Dae-Gu didn't have the hook, but a short hook only could move the belt itself was created, and then a movable short hook(China-Jin period Kwa-Dae, etc) to be inside of belt was showed, after that an axis was necessary when it became to long one, It was completed as a belt buckle. The stick shape hook was main stream in China an dthe other northern countries. Meanwhile, Korea has mostly "T" shape hook, and it shows that we developed our own unique style. Classifying the type of the belt plague, there are five types due to the scarved shapes on the Kwa-Dae and the changes. Mainly based on the excavated tomb articles of the three kingdoms and referred to Chinese and Japanese ones. It showed that the belt plague was lightly influenced by the times and area, but was slowly changed and developed to different types through those each ages generally.

• Transactions of The Korea Fluid Power Systems Society
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• v.7 no.4
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• pp.9-14
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• 2010

Most power steering systems work by using a hydraulic system to turn the vehicle's wheels. The pressure is usually provided by a hydraulic pump driven by the vehicle's engine. A double-acting hydraulic cylinder applies a force to the steering gear, which in turn applies a torque to the steering axis of the road wheels. The flow to the cylinder is controlled by valves operated by the steering wheel ; the more torque the driver applies to the steering wheel and the shaft it is attached to, the more fluid the valves allow through to the cylinder, and so the more force is applied to steer the wheels in the appropriate direction. Since the pumps employed are of the positive displacement type, the flow rate they deliver is directly proportional to the speed of the engine. And for a long time, the type of hydraulic pump pulley was boss welding type. But recently, monolith type driving pulley is widely used. Therefore in this paper we studied the safety of monolith type driving pulley to the extracting force and endurance by FEM analysis and experiments.

• Journal of the Korean Chemical Society
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• v.21 no.6
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• pp.434-439
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• 1977

The electronic structures of 4-pyridone and lutidone are studied by the SCF MO-CI PPP method and by the configuration analysis method. The spectral data are consistent with the values calculated by the method. The polarization of $S_1({\pi},{\pi}^*)$ state is along the long molecular axis in both compounds. The lowest $({\pi},{\pi}^*)$1 state shows significant charge transfer (16∼18%) from ${\pi}$ bonding orbital of C=O moiety to ${\pi}^*$ antibonding orbital of divinyl amine moiety. The lowest triplet state shows much larger charge transfer (24∼29 %) but in opposite direction compared to that of $S_1({\pi},{\pi}^*)$ state.

• Journal of Technologic Dentistry
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• v.37 no.3
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• pp.115-120
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• 2015

Purpose: The purpose of this study is a finite element analysis of supporting bone according to custom abutment angle. Methods: Implant fixture was selected with a diameter of 4 mm and the length of 13 mm. The fixture and abutment was designed by a combination of the abutment screw clamping force to produce a custom abutment model of $0^{\circ}$, $15^{\circ}$, $25^{\circ}$ and $35^{\circ}$. The loading condition of 176 N was applied to the lingual surface of the crown, near to the incisor edge, and horizontal load. An oblique load of $90^{\circ}$ was applied long axis of the implant fixture analyze the stress of supporting bone. Results: The result of mechanical analysis was observed that the supporting bone stress analysis of the horizontal load, the von Mises stress values (MPa) are given in the order of TH00 (432.6) > TH25 (418.0) > TH15 (417.4) > TH35 (415.8), the oblique load, the von Mises stress values are given in the order of TO00 (459.3) > TO15 (399.6) > TO25 (374.8) > TO35 (343.4) Conclusion: The $35^{\circ}$ abutment over the current clinical tolerance limits will be available for clinical application.

• Journal of Dental Rehabilitation and Applied Science
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• v.18 no.4
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• pp.313-320
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• 2002

The purpose of the present study was to evaluate the marginal discrepancy and topography of artificial crown on teeth extracted due to severe periodontal disease. Twenty specimens were invested into metamethylacrylate resin and cutted into vertical slices along with the long axis of tooth. The selected marginal discrepancy between the outer edge of the crown and the finishing line of abutment was examined by stereo- microscope(Olympus, PM-VSP-3, Japan) at magnification of up to 10, and the topography of finishing margin on crown was observed by stereomicroscopeat magnification of up to $70{\times}$. The results were as follows. (1) The mean marginal discrepancy between extracted tooth and artificial crown were $50.82{\mu}m$. (2) There was a considerable difference in the microstructure of finishing margins among specimens. Microscopic Structure on finishing margin showed indefinite line, poor fit (open, underextended and overextended), distorted margin, and surface roughness. This study suggested that there could be necessary to consider the response of periodontium to the emergence profile of natural tooth and precision of marginal geometry while establishing treatment planning for the reconsruction of the artificial crown.

• Journal of The Korean Astronomical Society
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• v.47 no.2
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• pp.69-76
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• 2014

We report the detection of an exoplanet candidate in orbit around ${\sigma}$ Persei from a radial velocity (RV) survey. The system exhibits periodic RV variations of $579.8{\pm}2.4$ days. The purpose of the survey is to search for low-amplitude and long-period RV variations in giants and examine the origin of the variations using the fiber-fed Bohyunsan Observatory Echelle Spectrograph installed at the 1.8-m telescope of Bohyunsan Optical Astronomy Observatory in Korea. We present high-accuracy RV measurements of ${\sigma}$ Per made from December 2003 to January 2014. We argue that the RV variations are not related to the surface inhomogeneities but instead a Keplerian motion of the planetary companion is the most likely explanation. Assuming a stellar mass of $2.25{\pm}0.5$ $M_{\odot}$, we obtain a minimum planetary companion mass of $6.5{\pm}1.0$ $M_{Jup}$, with an orbital semi-major axis of $1.8{\pm}0.1$ AU, and an eccentricity of $0.3{\pm}0.1$ around ${\sigma}$ Per.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1988.10a
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• pp.54-57
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• 1988

A film is fabricated by depositing several slices ultra thin films on a slide glass. The UV-absorbance outcomed on a multi-layered bulky ultra thin film with (N-docosyl pyridinium)-TCNQ (1:2) complex results tat the quantity of UV-absorbances becomes more linearly according to the number of layer becomes higher. In addition, it is found that the capacitance of this film gets smaller as the number of layer gets higher. Finally, the conductivity of this film is measured by the direction of the long axis of the TCNQ radical anion, and is resulted in a remarkably low value (about 1.66∼3.78 x 10$\^$-14/S/cm).

• Structural Engineering and Mechanics
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• v.8 no.1
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• pp.39-51
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• 1999

The dynamic response of buried pipelines has gained considerable importance because these pipelines perform vital role in conducting energy, water, communication and transportation. After realizing the magnitude of damage, and hence, the human uncomfort and the economical losses, researchers have paid sincere attention to this problem. A number of papers have appeared in the past which discuss the different aspects of the problem. This paper presents a theoretical analysis of non-axisymmetric dynamic response of buried orthotropic cylindrical shell subjected to a moving load along the axis of the shell. The orthotropic shell has been buried in a homogeneous, isotropic and elastic medium of infinite extent. A thick shell theory including the effects of rotary inertia and shear deformation has been used. A perfect bond between the shell and the surrounding medium has been assumed. Results have been obtained for very hard (rocky), medium hard and soft soil surrounding the shell. The effects of shell orthotropy have been brought out by varying the non-dimensional orthotropic parameters over a long range. Under these conditions the shell response is studied in axisymmetric mode as well as in the flexural mode. It is observed that the shell response is significantly affected by change in orthotropic parameters and also due to change of response mode. It is observed that axial deformation is large in axisymmetric mode as compared to that in flexural mode.

• Journal of Plant Biology
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• v.30 no.4
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• pp.225-247
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• 1987

Meiosis and postmeiotic mitosis in Boletus rubinellus were examined ultrastructurally. Meriosis occurred at the apex of the basidium. A sausage-shaped spindle pole body(SPB) was observed along with the presence of synaptonemal complexes during pachytene and a diglobular SPB was present on late pachytene or diplotene nuclei. During metaphase I, the monoglobular SPB at the spindle pole was surrounded bya membrane and the nuclear enveloope was discontinuous. At anaphase I, the chromosomes became better defined and formed a central spindle. The nucleolus was extruded from the nucleus. During anaphase I, the SPB was excluded from the chromosomal region by a membrane and both poles were fully separated to opposite sides of the basidial wall. In meiosis II, the two nuclei divided synchronously and the spindles were parallel. The spindles were smaller than in meiosis I, while the SPB was approximately the same size as that of the similar stage in meiosis I. During anaphasetelophase II, the SPB was surrounded by a cap of endoplasmic reticulum (ER) that delimited it from the spindle. The postmeiotic interphase nuclei migrated to the mid-region of the basidium before migration to the spores. The SPB at this stage was diglobular. A postmeiotic mitosis occurred within the basidiospore, and the plane of the spindle was obique to the long axis of the spore. The spindle and SPB were smaller than at meiosis I and there were fewer nonchromosomal microtubules. At anaphase, the nucleolus was present inside the nuclear envelope but lateral to the spindle.