• 한국안광학회지
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• 제9권2호
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• pp.223-231
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• 2004

기존에 이루어진 대부분의 AC/A비에 관한 연구들은 주로 Gradient AC/A비를 측정함으로써 진행되어 왔다. 본 연구는 Gradient AC/A비와 Calculated AC/A비를 함께 측정해 봄으로써 Gradient AC/A비 만을 측정했을 경우에는 나타나지 않는 근접성 폭주비 (Proximal Convergence/Accommodation)에 대한 고찰을 통해서 AC/A비의 임상 활용도를 높이는 데 그 목적이 있다. 124명의 검사대상은 최대시력을 단안 각각 1.0이상으로 원용교정을 하였으며 동적 검영법을 실시하여 조절기능의 이상 유무를 확인한 뒤 각각 Calculated AC/A비와 Gradient AC/A비를 측정하여 PC/A비를 구하였다. 연구결과 양안시 이상 그룹별 평균 Calculated AC/A비와 평균 Gradient AC/A비의 차이는 근접성 폭주 때문임을 보여주었다. 따라서, AC/A비의 임상 활용도를 높이기 위해서는 PC/A비를 포함한 근접성 (proximity)이라는 시기능변수 전반에 관한 지속적인 연구가 필요함을 확인할 수 있었다.

• 한국산업융합학회 논문집
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• 제25권2_2호
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• pp.233-238
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• 2022

This study evaluated the fatigue limit depending on microcracks using 0.57 wt.% carbon steel with different Vickers hardness. The fatigue limit was almost constant up to a certain limit regardless of the carbon content. However, the fatigue limit decreased rapidly as the size of the crack increased. As the crack aspect ratio was smaller, the fatigue limit of the depth (point A) a lot decreased. The fatigue limit ratio of the depth decreased significantly because the crack propagation in the depth direction was fast as the crack aspect ratio became smaller. On the other hand, the fatigue limit ratio of surface cracks increased as the crack aspect ratio decreased.

• International journal of advanced smart convergence
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• 제12권3호
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• pp.119-126
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• 2023

This study explores the convergence of metaverse and short-form content, proposing a new approach for viewing short-form content with a vertical aspect ratio on a metaverse platform and within a virtual museum. Short-form content has gained popularity due to the snack culture and is proving to be advantageous in e-commerce. By studying the relationship between vertical ratio screens and gaze, we confirm the effectiveness of vertical ratio short-form content in providing immersive experiences and fostering sharing and communication. The proposed virtual museum offers opportunities for innovative businesses to market through fandom. This research highlights the value of vertical proportion short-form content and its significance in the convergence of metaverse and short-form content. It aims to contribute to industry development, provide new creative directions, enhance personal visual experiences, and expand applicability in related fields.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2002년도 추계 학술대회논문집
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• pp.95-102
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• 2002

Studies of the numerical characteristics of implicit upwind schemes, such as upwind ADI, Line Gauss-Seidel(LGS) and Point Gauss-Seidel(LU) algorithms, for preconditioned Navier-Stokes equations ate performed. All the algorithms are expressed in approximate factorization form and Von Neumann stability analysis and convergence studies are made. Preconditioning is applied for efficient convergence at low Mach numbers and low Reynolds numbers. For high aspect ratio computations, the ADI and LGS algorithms show efficient and uniform convergence up to moderate aspect ratio if we adopt viscous preconditioning based on min- CFL/max- VNN time-step definition. The LU algorithm, on the other hand, shows serious deterioration in convergence rate as the grid aspect ratio increases. Computations for practical applications also verify these results.

• East Asian mathematical journal
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• 제23권2호
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• pp.261-270
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• 2007

We provide a local convergence analysis for Secant-like algorithm for solving nonsmooth variational inclusions in Banach spaces. An existence-convergence theorem and an improvement of the ratio of convergence of this algorithm are given under center-conditioned divided difference and Aubin's continuity concept. Our result compare favorably with related obtained in [16].

• 한국안광학회지
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• 제17권2호
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• pp.165-170
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• 2012

목적: 2D와 3D 영상 시청에서 나타나는 시각반응의 변화를 측정하고 평가하고자 하였다. 방법: 시기능이 정상인만 19세 이상 25세 이하의 대학생 44명을 대상으로 하였다. CA/C비(convergence accommodation/convergence ratio), 폭주로 유도되는 PD(interpupillary distance)변화와 조절반응, 3D 영상 시청 시 자각적 인지거리를 측정하였다. 결과: 폭주와 조절은 2D 영상 시청보다 3D 영상 시청에서 더 컸으며(p<0.05), CA/C비와 조절반응은 양적 상관관계(r = 0.477, p = 0.001)를 보였다. PD가 작을수록 심도지각의 깊이는 큰 것으로 나타났으며, 3D 영상에서 폭주는 인지하고 있는 거리에서의 폭주보다 더 큰 것으로 나타났다. 결론: CA/C비가 클수록, PD가 작을수록 3D 영상 시청에서 시각적 불편함은 더 심할 것으로 예상된다.

• 한국안광학회지
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• 제17권2호
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• pp.153-158
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• 2012

목적: 이 연구의 목적은 양안시가 정상인 20대 초반 성인의 폭주성조절(CA/C, convergence accommodation/convergence ratio)비를 평가하고 나이, 조절력 및 동공간거리(PD, interpupillary distance)와의 관련성을 분석하고자 하였다. 방법: 건강한 눈을 가진 44명(평균나이 $21.75{\pm}1.16$세)을 대상으로 조사하였다. CA/C비는 가우시안의 차(DOG, difference of Gaussian) 시표를 이용하여 검영법으로 측정하였다. 결과: 측정결과 CA/C비는 평균 $0.052{\pm}0.017$ D/$\Delta$이었다. CA/C비와 나이는 중간 정도의 음의 상관관계(r = -0.50, p = 0.0005)를, CA/C비와 조절력은 강한 양의 상관관계(r = 0.79, p<0.0001)를 보였으며, PD와 CA/C비의 상관관계는 없었다. 결론: 제시된 CA/C비는 19세에서 25세의 건안상태의 20대 초반 성인을 기준으로 측정한 평균값이다. 조절력과 CA/C비는 높은 상관관계를 보였다. 따라서 이 자료는 외국의 자료와 연령별, 성별, 양안시이상별 비교에 기본 정보로 활용될 것으로 본다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2009년 춘계학술대회논문집
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• pp.269-276
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• 2009

The local preconditioning method has both robust convergence and accurate solutions by using local flow properties for parameters in the preconditioning matrix. Preconditioning methods have been very effective to low speed inviscid flows. In the viscous and turbulent flows, deterioration of convergence should be overcame on the high aspect ratio grids to get better convergence and accuracy. In the present study, the local time stepping and min-CFL/max-VNN definitions are applied to compare the results and we propose the method that switches between two methods. The min-CFL definition is applied for inviscid flow problems and the min-CFL/max-VNN definition is implemented to viscous and turbulent flow problems.

• 대한전자공학회논문지
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• 제24권4호
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• pp.719-726
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• 1987

In this paper, an adaptive IIR (infinite impulse response) notch filter of lattice type is constructed and its adaptation algorithm is proposed for the detection and retrieval of a sine wave signal embedded in noise. A modified method which adapts only one coefficient of the filter is also suggested. All these methods adapt the coefficients while keepting the poles of the filter inside the unit circle on z-plane, and thus they satisfy the condition on the stability of the IIR filter after it has converged. To investigate the convergence characteristics of these methods such as convergence speed and output S/N ratio, intensive computer simulation has been performed by varying the frequency of the sine wave and the input S/N ratio. And the results of the simulation have been compared to those of Rao and Kung's which shows relatively fast convergence speed. The methods proposed here, especially the second one. shows faster convergence speed and higher output S/N ratio than the Rao and Kung's.

• 한국산업융합학회 논문집
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• 제6권2호
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• pp.149-153
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• 2003

Besides the fuel spray behavior and combustion chamber shape. an air motion has a key role on exhaust gas emission and performance in a DI diesel engine. A swirl ratio represents the ratio of the intake swirl velocity to the engine speed. The main purpose in this work is to investigate the effects of the swirl ratio to the combustion characteristics. A shroud valve machined to change the swirl ratio. Test was carry out by changing the engine speed, nozzle diameter and swirl ratio in a single cylinder diesel engine. From this study, the optimized combustion was found at swirl ratio 2.7. And it was also found that the increasing the maximum cylinder pressure with an increasing swirl ratio lead to decrease a smoke and to increase NOx.