• 대한기계학회논문집A
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• 제28권1호
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• pp.31-39
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• 2004

This paper presents design solutions for cam type transfer unit in which feeding, lifting, and clamping motions are generated by cams. In order to achieve faster transfer motion, each designed cam must satisfy the given specifications such as velocity, acceleration, jerk, pressure angle, cam thickness, and torque. To reduce absolute torque magnitude and torque variation, a conjugate cam and a torque reduction cam are used respectively. The conjugate cam eliminates the redundant pre-load by using complementary cam to avoid jumping between a cam and a follower. The torque reduction cam reduces the torque variation by applying opposite torque to a cam shaft. The experimental result shows the reductions of the absolute torque value and torque variation. The improvement of working speed and life span of cam type transfer unit can be expected.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2003년도 학술대회논문집
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• pp.381-385
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• 2003

In this paper, a co-axial type ozonizer varied with discharge gap was designed and manufactured for investigating $\circled1$ discharge characteristics with variation of output voltage power supply, flow rate and gap $\circled2$ ozone generation characteristics with variation of flow rate, gap and discharge power. pure oxygen was used as process gas of the co-axial type ozonizer. In this paper, a double cylindrical type superposed silent discharge type ozonizer which internal electrode can be produced a vacuum has been designed and manufactured. Discharge and ozone generation characteristics have been investigated in accordance with output voltage of power supply, flow-rate, discharge power and vacuum of internal electrode.

• Journal of Korean Neurosurgical Society
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• 제61권2호
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• pp.194-200
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• 2018

Objective : Sometimes a vertebral artery (VA) enters the spinal canal via the C1-2 intervertebral space, a variation regarded as a C2 segmental-type VA. This paper describes the anatomy of the C2 segmental-type VA and reviews its clinical importance. Methods : Between March 2014 and November 2015, 3386 patients underwent computed tomographic angiography. I identified C2 segmental-type VAs, associated vascular variation, the origin of ipsilateral posterior inferior cerebellar arteries (PICAs), and the clinical symptoms associated with C2 segmental-type VAs. The origin of an ipsilateral PICA is divided into 5 types. A type 1 PICA originates from ipsilateral VAs coursing suboccipitally (IVASO), a type 2 originates from ipsilateral proximal C2 segmental-type VAs, a type 3 originates from ipsilateral distal C2 segmental-type VAs. For type 4, the PICA does not originate from an ipsilateral VA. For type 5, the PICA is the terminal end of an ipsilateral C2 segmental-type VA. Results : One hundred thirteen patients had 121 C2 segmental-type VAs; 47 were associated with an IVASO, and 74 were not. Four type 1, 13 type 2, 60 type 3, 42 type 4, and two type 5 PICAs were identified. Only one patient showed symptoms associated with a C2 segmental-type VA, being a 71-year-old man presenting with a C2 segmental-type VA infarction. Conclusion : For C2 segmental-type VAs, the ipsilateral IVASO and origin of the PICA are important for predicting the outcome of this type of VA infarction.

• ETRI Journal
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• 제38권1호
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• pp.195-205
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• 2016

This paper presents a novel follicular unit (FU) classification method based on an angle variation of a boundary vector according to the number of hairs in several FU images. The recently developed robotic FU harvest system, ARTAS, classifies through digital imaging the FU type based on the number of hairs with defects in the contour and outline profile of the FU of interest. However, this method has a drawback in that the FU classification is inaccurate because it causes unintended defects in the outline profile of the FU. To overcome this drawback, the proposed method classifies the FU's type by the number of variation points that are calculated using an angle variation a boundary vector. The experimental results show that the proposed method is robust and accurate for various FU shapes, compared to the contour-outline profile FU classification method of the ARTAS system.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제5권1호
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• pp.35-45
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• 2001

In this paper we point out an Ostrowski type inequality for the Riemann-Stieltjes integral ${\int}_a^b$ f (t) du (t), where f is of p-H-$H{\ddot{o}}lder$ type on [a,b], and u is of bounded variation on [a,b]. Applications for the approximation problem of the Riemann-Stieltjes integral in terms of Riemann-Stieltjes sums are also given.

• 대한치과보철학회지
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• 제35권1호
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• pp.181-210
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• 1997

The stress distribution generated in the surrounding bone was calculated and compared for various geometry of the dental implants by means of the finite element methods. The models were designed to represent the screw type endosseous implants(varing the size, shape, direction of the screw thread and the angle of the body) with supporting bone and the cylinder type endosseous implants(varing the lower portion-Round type, tapered type) with supporting bone. Static mean bite forces were applied 100N vertically and 25N horizontally on the center of the implant and three dimensional finite analysis was undertaken using software ANSYS 5.1 Version. The result demonstrated that different implant shape leads to significant variations in stress distribution in the bone. In the case of variation of the screw size, direction and shape the implant model with normally directional and triangular screw implied lower stress than with upper directional or lower directional and quadrangular screw but among models a different screw size, within a variation of 0.2mm there was no meaningful difference in maximum stress. In the case of variation of angle of body the straight implied lower stress than the tapered. As a result of analysis of cylinder type, the implants with larger radius of curvature of the round form and larger diameter of the tapered form implied lower stress.

• 한국작물학회지
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• 제23권3호
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• pp.31-46
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• 1978

In order to secure the proper use of herbicides that are frequently used in Korea, the behavior of herbicides in various type of soil were studied. This study includes the variation of phytotoxicity, leaching and movement, and residual activity period of herbicides depending upon the type of soil etc. Experiments were also conducted to establish a guideline for the selection of herbicides according to the type of soil and the proper use of each herbicide in various type of soil in Korea. Experimental results showed that the behavior of herbicides could be characterized based on the series or kind of herbicides and devided into two major groups. One group (nitrofen. CNP, benthiocarb and butachlor) of herbicides showed relatively little crop injury and was very dependable. The action of this group was not remarkably influenced by soil components, rainfall and the quantity of herbicide used with the type of soil that had small adsorption capacity such as most of soil in Korea. The other group(simazine, 2, 4-D. linuron, alachlor and simetryne) showed a wide variation in it's action and retained potentially injurious effect. This group was very susceptable to using condition as well as the type of soil itself. Based on the results of various experiments the disappearance of the residual activity period of major herbicides used in upland and paddy field and the related factors were explained. It is believed that the results of this study can be used as a base for the establishment of a guideline for the proper use of each herbicide and can suggest a direction of developing new herbicides.

• 한국데이터정보과학회:학술대회논문집
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• 한국데이터정보과학회 2004년도 추계학술대회
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• pp.17-23
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• 2004

At the conclusion from the hypothesis testing, there is a possibility of making Type I error and Type II error. The purpose of this article is to use this program in statistics teaching through developing the program for studying on the concept about these two errors, two kinds of the probability of errors by the variation of rejection region, two kinds of the probability of errors by the variation of sample size, the relations of the probability $\alpha$ and $\beta$ by these two errors, and power function, power curve.

• Journal of Advanced Marine Engineering and Technology
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• 제15권2호
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• pp.53-63
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• 1991

This study suggests a new type shaft generator driven by hydraulic power suitable for small size vessels. Since the shaft generator system is very easy to be affected by disturbances such as speed variation of main engine and load variation of the generator, a robust servo control must be implemented to obtain stable electric power with constant frequency. Thus, in this study two types of controller design method-the reference following optimal control method and robust servo control method-are adopted to the controller design. In the experiment, static and dynamic characteristics of the shaft generator system according to the variation of input frequency setting, the speed variation of the pump and the load variation of the generator are investigated. From the considerations on the computer simulation results and experimental results, it is ascertained that the shaft generator system proposed in this study has good control performances.

• 동력기계공학회지
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• 제6권2호
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• pp.82-87
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• 2002

For the dynamic behavior evaluation of a semi-active vibration control system, it is very important to use an accurate mathematical model for the hydraulic damper applied to the control system. In this study, a mathematical model for a symmetric type hydraulic damper was suggested. In this model, the effects of gas volume and oil temperature variation on the bulk modulus of oil were considered. The dynamic behavior of the damper was investigated by experiments and simulations. It was confirmed that the pressure variation, damping force, and mean pressure variation could be estimated with comparatively good precision by the suggested mathematical model. Moreover, it was shown that excessive pressure rise can be generated by the oil expansion due to the heat energy transformed from the exciting energy of the damper for a short period of the damper operation.