• 한국전자파학회논문지
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• 제13권4호
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• pp.393-400
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• 2002

본 논문에서는 원형편파를 발생시키기 위한 여러 가지 방법 중 단일 급전 십자개구 결합 방식이 가지는 협대역의 축비 대역폭을 개선하기 위해 단일 급전으로 하이브리드 급전의 효과를 가져을 수 있는 직렬 급전 십자개구 결합 마이크로스트립 안테나를 제안하고, 기존에 발표된 단일 급전 십자개구 결합 안테나와의 축비 대역폭, 이득, 방사패턴, 그리고 임피던스 대역폭 등과 비교하여 개선된 축비 대역폭 특성을 제시하여 제안된 안테나의 타당성을 보였다. 또한 제안된 단일 안테나를 이용해 2$\times$2 배열 안테나로 확장하는 과정에서 시퀀셜 로테이션 기법을 적용함으로써 더욱 넓은 축비 대역폭을 화보할 수 있도록 하였다. 직렬급전 단일 안테나와 2$\times$2 배열 안테나의 측정된 축비 대역폭은 110 MHz(4.6 %)와 420 MHz(17.5 %)를 보였고, 측정된 임피던스 대역폭 (VSWR<1.5)은 240 MHz(10%)와 500 MHz(20.8%)출 가졌으며, 이득 측정결과에서는 단일 안테나와 2$\times$2 배열 안테나 모두 3 dB 이득 대역폭에서 400 MHz(16.7%) 이상의 평탄 특성을 가지며 최대이득에서는 8.2 ㏈i와 12.5 ㏈i의 이득특성을 보여주었다.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.297-302
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• 2007

Vibrating test of vehicle component can be possible in lab-based simulators instead of field testing owing to the development of technology in control algorithm as well as computational process. Currently, Multi-Axial Simulation Table(MAST) is recommended as a vibrating equipment, which excites a target component for 3-directional translation and rotation motion simultaneously and hence, vibrational condition can be fully approximated to that of real road test. But, the vibration-free performance of target component is not guaranteed with MAST system, which is only simulator subjective to the operator. Rather, the reliability of multi-axial vibration test is dependent on the quality of input profile which should cover the required severity of vibrating condition on target component. In this paper, multi-axial vibration testing methodology of vehicle component is presented here, from data acquisition of vehicle accelerations to the obtaining the input profile of MAST using severe data at proving ground. To compare the severity of vibration condition, between real road test and proving ground one, energy principle of equivalent damage is proposed to calculate energy matrices of acceleration data and then, it is determined the optimal combination of special events on proving ground which is equivalent to real road test at the aspects of vibration fatigue using sequential searching optimal algorithm. To explain the vibration methodology clearly, seat and door component of vehicle are selected as a example.

• 정보저장시스템학회논문집
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• 제1권2호
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• pp.169-174
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• 2005

Current information storage devices read/write data on the rotating disk. The axial vibration of a rotating disk should be suppressed for the successful operation of the device. Information storage devices widely used in these days adopt relatively thick disk which is stiff enough to suppress axial vibration under allowable limit. However, the thickness of the disk is going to be thinner and thinner as the small form factor of the devices is getting preferred by the consumer. In this study, a stabilizer system, which is composed with 8 air bearings, is proposed for suppressing the axial vibration of a $95{\mu}m$ thick PC disk in a non-contacting manner. The performance of the stabilizer system is simulated by numerical computation and then confirmed its results through a series of experiment. A thin and flexible disk has various vibration modes when it rotates in high speed. The stabilizer system generates positive as well as negative pressure due to the rotation of flexible disk so that the force due to the pressure distribution pushes and pulls rotating disk in a non-contacting manner. The balance between positive and negative pressure forces can be obtained by adjusting the area and the slope of the air bearing surface. The axial vibration of the flexible disk of 120mm diameter is suppressed successfully from over $1000{\mu}m$ to $30{\mu}m$ peak-to-peak value at the rotational speed of 5,000rpm.

• 대한치과의사협회지
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• 제24권12호통권211호
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• pp.1049-1060
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• 1986

The author evaluated the effect of wunderer activator for correction of functional enterior corss-bite. The Data were obtained from super-imposition of pre. and post -treatment lateral cephalo-grams. The results were as follows. 1. Correction of anterior crossbite and improvement of facial profile were occurred. 2. Axial inclination of maxillary and mandibular anterior teeth were improved. 3. Slightly down and backwakd rotation of mandible was occurred by the increment of Y-axis angle, anterior facial height and SN-MP angle.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1634-1639
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• 2004

The present study concerns a experimental study of fully developed laminar flow of a Newtonian and non-Newtonian fluid through a concentric annulus with a combined bulk axial flow and inner cylinder rotation for the various radius ratio. This study shows the fundamental difference between Newtonian and non-Newtonian fluid flow in an annulus for various radius ratio.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 추계학술대회 논문집
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• pp.261-266
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• 1998

In this study, crush characteristics of thin-walled rectangular tube is investigated. The stiffness of the element is obtained from analytical moment-rotation relationship and approximated load-deflection relationship of thin-walled rectangular tube. A computer program is developed for the large deformation analysis of frame. An incremental displacement method is used in the program and at each incremental stage, the stiffness matrix of the total structure is checked with the state each element for bending and compression.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 1998년도 춘계학술대회 논문집
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• pp.71-75
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• 1998

This study deals with the friction weldability of A7075-T6 having high specific strength. The friction welding conditions used are rotation speed 2000rpm, friction pressure 40MPa, friction time 1.5sec, upset pressure 40~100MPa, upset time 5sec. First, upset length was measured by displacement transducer. The plastic flow in 7075-T6 weld generates convex lens shaped resion by friction and concave lens shaped resion by axial force. Under the condition of upset pressure 85MPa, the friction welds have tensile strength of 552MPa and shear strength of 262MPa.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 1997년도 제26회 추계학술대회
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• pp.239-244
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• 1997

Recently, the high speed rotation and accuracy is needed in the field of electro-optic devices. But it is difficult for ball bearing to satisfy such conditions. So, we have developed the hemispherical type aerodynamic bearing for LSU(Laser Scanning Unit) motor. The hemispherical type aerodynamic bearing is able to support radial and axial load simultaneously. In this research, We have developed mass production method and tested the perromance of aerodynamic bearing in comparision with ball bearing at the speed of 23,000rpm. In the result, we proved that the properties of aerodynamic bearing is better than ball bearing's.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 춘계학술대회 논문집
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• pp.643-647
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• 1995

The thin film flow in the clearance between the piston and cylinder is numerically analyzed to study the lubrication characteristics of the Swashplate type axial piston pumps. The Reynolds equation is solved using a finite difference method under Reynolds boundarycondition. The pressure distributions in the clearance and the lateral forces acting on the piston are compared for various operating conditions. Tilting and rotation of the piston in the cylinder gore are highly affect the lubrication characteristics, therefore, additional analysis are required.

• 대한치과교정학회지
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• 제43권6호
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• pp.263-270
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• 2013

Objective: To evaluate condylar head remodeling after mandibular set-back sagittal split ramus osteotomy (SSRO) with rigid fixation in skeletal class III deformities. The correlation between condylar head remodeling and condylar axis changes was determined using cone-beam computed tomography (CBCT) superimposition. Methods: The CBCT data of 22 subjects (9 men and 13 women) who had undergone mandibular set-back SSRO with rigid fixation were analyzed. Changes in the condylar head measurements and the distribution of the signs of condylar head remodeling were evaluated by CBCT superimposition. Results: The subjects showed inward rotation of the axial condylar angle; reduced condylar heights on the sagittal and coronal planes; and resorptive remodeling in the anterior and superior areas on the sagittal plane, superior and lateral areas on the coronal plane, and anterior-middle and anterior-lateral areas on the axial plane (p < 0.05). Conclusions: The CBCT superimposition method showed condylar head remodeling after mandibular set-back SSRO with rigid fixation. In skeletal class III patients, SSRO with rigid fixation resulted in rotation, diminution, and remodeling of the condylar head. However, these changes did not produce clinical signs or symptoms of temporomandibular disorders.