• Journal of Korean Ophthalmic Optics Society
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• v.4 no.2
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• pp.23-31
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• 1999

The purpose of this study is to evaluate the relationship between axial length/corneal radius ratio and refractive error for human eye. Ocular components were measured Baush & Lomb keratometer, Holden-Payor pachometer, and Stoz Compuscan. Refractive error was measured by subjective refraction. The results were as follows; 1) Spherical equivalent refractive error and axial length/corneal radius ratio was very highly correlated with the correlation coefficient for -0.89. 2) Axial length/corneal radius ratio and axial length, vitreous chamber depth were highly correlated that the correlation coefficients were 0.82, 0.80 respectively. 3) Axial length/corneal radius ratio and anterior chamber depth, corneal power, corneal radius, lens power were correlated with the correlation coefficients for 0.57, 0.40, -0.39, -0.35 respectively. 4) There were no significant correlation between axial length/corneal radius ratio and lens thickness, and corneal thickness.

• Journal of IKEEE
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• v.22 no.4
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• pp.916-921
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• 2018

In this paper, we analyzed the power MOSFET devices for high voltage and high current operation. 4H-SiC was used instead of Si to improve the static characteristics of the device. Since 4H-SiC has a high critical electric field due to wide band gap, 4H-SiC is more advantageous than Si in high voltage and high current operation. In the conventional VDMOSFET structure using 4H-SiC, the breakdown voltage is limited due to the electric field crowding at the edge of the p-base region. Therefore, in this paper, we propose a Curvature VDMOSFET structure that improves the breakdown voltage and the static characteristics by reducing the electric field crowding by giving curvature to the edge of the p-base region. The static characteristics of conventional VDMOSFET and curvature VDMOSFET are compared and analyzed through TCAD simulation. The Curvature VDMOSFET has a breakdown voltage of 68.6% higher than that of the conventional structure without increasing on-resistance.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.32 no.1
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• pp.55-62
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• 2014

In this study, we investigated the landslides area which occurred in Umyeonsan in 2011 and collected landslide location data. Using this field data with aerial photos and LiDAR data which is obtained before and after disaster event, we analyzed the landslide occurrence frequency per unit area about various topographic characteristics. In case of slope, we compared two kind of slopes which are calculated with Neighborhood algorithm and maximum slope algorithm. Also we used aspect, elevation, profile curvature and planform curvature in topographic analysis of landslide occurrence locations. As a result, the region of which maximum slope is $40^{\circ}-45^{\circ}$ is relatively hazardous in landslide. If the perpendicular surface to the direction of the maximum slope is concave, it is more hazardous than other case.

• The Journal of the Acoustical Society of Korea
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• v.20 no.6
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• pp.75-81
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• 2001

In this paper we analyzed the localization error of near-field detection algorithm in the sea. The near-field detection algorithms using triangulation and wavefront curvature basically assume a signal in two dimension of bearing and range. But the assumption causes localization error because there is three dimension of bearing, range, and depth in the sea. Even through three dimensional effect is considered, the localization error is occurred if multipath propagation in the sea is ignored. To analyze the localization error in the sea, we simulate the near-field localization using acoustic propagation model and focused beamforming considering wavefront curvature. The simulation results indicate that localization error always occurs in the sea and the error varied with sound velocity profile, water depth, bottom slope, source range, etc.

• Journal of the Korean Geotechnical Society
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• v.19 no.2
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• pp.199-206
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• 2003

Particle-size distribution in soils is one of the most fundamental physical properties of soils. One of the latest developments in the study of particle-size distributions has focused on the use of fractal theories. In this study, the fragmentation fractals were used for determining the characteristics of the particle-size distribution curve. It was shown that the mass-size distribution method was more practical than the cumulative number-size distribution method. From the co-relation between fractal dimensions($D_{tot}$) and the coefficient of uniformity($C_{u}$), there was a sharp increase in fractal dimensions for $C_{u}$<4, but fractal dimension converged the single value for $D_{u}$$\geq$6. Fractal dimensions were affected by small sized particles for $C_{c}$$\geq$3 and large sized particles for $C_{c}$/<3. As a result of the analysis of the influence of the effective size($D_{10}$), it was observed that the changes of $D_{tot}$/ were nominal beyond the effective size.

• Journal of Korean Ophthalmic Optics Society
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• v.16 no.3
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• pp.273-281
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• 2011

Purpose: In order to provide the fundamental information for the design development of RGP lenses and its clinical prescription, the corneal types of Korean twenties were analyzed according to corneal shapes, astigmatic degree, and the certain distance from the corneal apex. Methods: Corneal types of total 252 eyes in 20s were firstly classified, then their corneal radii from the certain distance from the corneal apex were measured by corneal topography and further analyzed based on the astigmatic degree. Results: Korean 20s' corneal types were classified as 14.3%(36 eyes) of round, 31.3%(79 eyes) of oval, 28.6%(72 eyes) of symmetric bow tie, 17.5%(44 eyes) of asymmetric bow tie, 8.3%(21 eyes) of irregular shapes. The round and oval typed corneas had mild astigmatic degree whereas the higher astigmatic degree in symmetric and asymmetric bow tie typed corneas were shown. The relative corneal radii of round and oval typed corneas at each distance from corneal apex were shown to consistently increase regardless of astigmatic degrees when they measured at certain distances from the corneal apex. However, the relative corneal radii of symmetric and asymmetric bow tie typed corneas within 1.0-1.5mm from the corneal apex were decreased, which showed steeper slope than it within 1.0 mm and somewhat different based on astigmatic degrees. Bigger change of corneal radii outer 3.5 mm from the corneal apex in symmetric bow tie typed corneas with astigmatism of 1.50-2.00 D and 2.25-2.75 D appeared. Conclusions: The consideration of radial change from the central cornea to peripheral cornea is necessary for manufacturing RGP lens and its prescription since they showed different change in corneal radii by corneal patterns and astigmatic degrees.

• Journal of Korean Society of Transportation
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• v.24 no.2 s.88
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• pp.7-18
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• 2006

The Purpose of this study is to develop landscape Preference and define elements of difference in landscape preference of the 1-span Steel Box Girder Bridge by Bridge Shape Parameters(BSP) through Design of Experiments. Lately, the 1-span Steel Box Girder Bridge is dominations much component ratio and the Steel Box Girder Bridge has strong Points that is economically Profitable and management has easy when construct. but landscape preference of the 1-span Steel Box Girder Bridge was evaluated low because impression of landscape is being surfeited and dulled. Do to consider optimization in design that give change to Bridge Shape Parameters(BSP) to supplement this shortcoming in this study. Therefore, this study changes Bridge Shape Parameters(BSP) and extract elements that influence in landscape preference of the 1-span Steel Box Girder Bridge. and based on the design that consider landscape Preference of the 1-span Steel Box Girder Bridge, some essential guidelines for rational design of the 1-span Steel Box Girder Bridge suggested.

• The Journal of Korean Society for Radiation Therapy
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• v.27 no.2
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• pp.123-129
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• 2015

Purpose : The goal of this study was to verify and analyze the source position according to the curvature of the universal applicator and 4 different angle applicators when using RALS(Remote After Loading System). Materials and Methods : An interval of 1 cm and 15 second dwell times in each source position were applied for plan. To verify the accuracy of source position, we narrowed the distance between MultiSource container and GAFCHROMIC$^{(R)}$ EBT3 film by 5 cm, 10 cm, 20 cm so that the universal applicator transfer tube had some curvature. Also 4 applicators(Intrauterine tube: $0^{\circ}$, $15^{\circ}$, $30^{\circ}$, Ovoid tube: $65^{\circ}$) were used in the same condition. The differences between desired and actual source position were measured by using Image J. Results : In case of using 4 different angles of applicator with the straight universal applicator transfer tube, the average error was the lowest for $0^{\circ}$ applicator, greatest for $65^{\circ}$ applicator. However, All average errors were within ${\pm}2mm$ recommended in TG-56. When MultiSource container was moved 5 cm, 10 cm, 20 cm towards the EBT3 film, the average errors were beyond ${\pm}2mm$. The first dwell position was relatively located in accuracy, while the second and third dwells were displaced by an increasing magnitude with increasing curvature of the transfer tube. Furthermore, with increasing the angle of applicators, the error of all other dwell positioning was increased. Conclusion : The results of this study showed that both the curvature of universal applicator transfer tube and the angle of applicators affect the source dwell position. It is recommended that using straight universal applicator transfer tubes is followed in all cases, in order to avoid deviations in the delivered source dwell position. Also, It is advisable to verify the actual dwell position, using video camera quality control tool prior to all treatments.

• Convergence Security Journal
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• v.8 no.4
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• pp.161-166
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• 2008

This paper proposes a new approach to align 3D data sets by using curvatures of feature surface. We use the Gaussian curvatures and the covariance matrix which imply the physical characteristics of the model to achieve registration of unaligned 3D data sets. First, the physical characteristics of local area are obtained by the Gaussian curvature. And the camera position of 3D range finder system is calculated from by using the projection matrix between 3D data set and 2D image. Then, the physical characteristics of whole area are obtained by the covariance matrix of the model. The corresponding points can be found in the overlapping region with the cross-projection method and it concentrates by removed points of self-occlusion. By the repeatedly the process discussed above, we finally find corrected points of overlapping region and get the optimized registration result.

• Proceedings of the Korea Information Processing Society Conference
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• 2015.10a
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• pp.1579-1580
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• 2015

본 논문에서는 3차원 메쉬 모델의 중요 영역을 표현하는 메쉬 돌출맵(mesh saliency map)을 생성하기 위하여 다중 스케일 평균 곡률 (multi-scale mean curvature)을 기반으로 정의된 전역 희소치(global rarity)를 이용하는 방법을 제안한다. 제안 방법에서는 우선, 메쉬 모델의 지역 영역 특성을 정의하기 위하여 기존 관련 연구들에서 많이 사용하고 있는 가우시안 가중치 평균곡률(Gaussian-weighted mean curvature)을 5단계 서로 다른 스케일에서 정의하고, 메쉬의 각 정점(vertex)에 대하여 중심주변 연산자(center-surround operator)를 적용하여 5단계 지역 돌출특성(local saliency)을 정의한다. 주어진 메쉬 모델의 전역 희소치를 구하기 위하여 메쉬의 모든 정점쌍 (vertex pair)에 대하여 5단계 지역 돌출 특성 공간에서의 거리를 계산하고, 각 정점별로 5단계 지역 돌출 특성 공간에서의 다른 정점과의 거리의 합으로 전역 희소치를 정의한다. 이러한 전역 희소치를 각 정점의 메쉬 돌출치로 정의한다. 서로 다른 형태의 3차원 모델에 대하여 제안방법에 의한 메쉬 돌출맵과 지역 특성만을 고려한 기존 메쉬 돌출맵을 생성하여 중요 영역 표현 결과를 비교 분석한다.