• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.6
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• pp.545-551
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• 2017

It is very important to effectively obtain the information related to the human body shape for user-centered design. The human body shape is a huge combination of various irregular curves and is typically obtained by a 3-D Scanner. 3-D scanners show high reliability; however, they are expnsive equipment with limited mobility. 3-D models of irregular-shaped curves were created by a photogrammetric approach and the errors between the original curve and the models were evaluated. 3-D models were created based on 160, 80, 40, 20, 10, and 5 marking points evenly located on the original curve. In the case of convex curve, low levels of residuals were observed in the models from 160, 80, 40, and 20 marking points (0.13% max). In the combination of convex and concave curves, relatively low levels of residuals were observed in the models from 160, 80, and 40 marking points (0.29%). It is possible to conclude that marking points should be placed at every 5% of overall length of a convex curve and at every 2.5% of overall length of a curve with convex and concave curve in order to maintain low levels of errors. A photogrammetric approach can be used as an alternative for the 3-D scanners with advantages of low cost and mobility.

• Journal of rehabilitation welfare engineering & assistive technology
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• v.10 no.4
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• pp.321-328
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• 2016

In this paper, we propose a walk status method which can be fused with conventional walk intention method to improve convenience of an electric assistive walking system for elder people with restricted walking capabilities. The system uses a handlebar as a trigger and regards grabbing a handlebar as expressing will to walk. And the system uses a user's linear velocity and angular velocity as linear velocity and angular velocity of a system, checked by laser range finder. To achieve this, we propose a method to find a virtual central point of a human body by estimating a central point between two legs. The experiments are carried out by comparing user's linear velocity and angular velocity, and system's linear velocity and angular velocity. The results show that the error of linear velocity and angular velocity between a user and a system are 1% and 2.77%, which means the linear velocity and angular velocity of a user can be applied to a system. And it is confirmed that the proposed fusion method can prevent a user from being dragged by an assistive walking system or a malfunction caused by lack of experience

• The Journal of Korean Academy of Prosthodontics
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• v.59 no.3
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• pp.261-270
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• 2021

Purpose. The aim of this study was (1) to compare the reverse engineering technique with other existing measurement methods and (2) to analyze the effect of implant angulations and impression coping types on implant impression accuracy with reverse engineering technique. Materials and methods. Three different master models were fabricated and the distance between the two implant center points in parallel master model was measured with different three methods; digital caliper measurement (Group DC), optical measuring (Group OM), and reverse engineering technique (Group RE). The 90 experimental models were fabricated with three types of impression copings for the three different implant angulation and the angular and distance error rate were calculated. One-way ANOVA was used for comparison among the evaluation methods (P < .05). The error rates of experimental groups were analyzed by two-way ANOVA (P < .05). Results. While there was significant difference between Group DC and RE (P < .05), Group OM had no significant difference compared with other groups (P > .05). The standard deviations in reverse engineering were much lower than those of digital caliper and optical measurement. Hybrid groups had no significant difference from the pick-up groups in distance error rates (P > .05). Conclusion. The reverse engineering technique demonstrated its potential as an evaluation technique of 3D accuracy of impression techniques.

• Korean Journal of Remote Sensing
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• v.29 no.5
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• pp.555-568
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• 2013

Atmospheric optical thickness during nighttime was estimated in this study using analysis on the images of the moon taken from commercial digital camera. Basically the Langely Regression method was applied to the observations of the moon for the cloudless and optically stable sky conditions. The spectral response functions for the red(R), green(G), and blue(B) channels were employed to derive effective wavelength centers of each channel for the observations of the moon, and the correspondent Rayleigh optical thickness were also calculated. Aerosol optical thickness (AOT) was calculated by subtracting Rayleigh optical thickness from the atmospheric optical thickness derived from the Langley regression method. As there are only handful of nighttime AOT observations, the AOT from the moon observations was compared with the AOT from sun-photometers and the MODIS satellite sensor, which was taken several hours before the moon observations of this study. As a result, the values of AOT from moon observations agree with those from sun-photometers and MODIS within 0.1 for the R, G, B channels of the digital camera. On the other hand, ${\AA}$ngstr$\ddot{o}$m Exponent seems to be subject to larger errors due to its sensitiveness to the spectral errors of AOT. Nevertheless, the results of this study indicate that the method reported in this study is promising as it can provide nighttime AOT relatively easily with a low cost instrument like digital camera. More observations and analyses are warranted to attain improved nighttime AOT observations in the future.

• Proceedings of the Korea Society of Costume Conference
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• 2001.04a
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• pp.42-43
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• 2001

색상특성은 각 계열별로 차이가 있었으나 전반적 으로 고명도.저채도 중심으로 황색계열과 청색계열 은 고명도 위주의 분포특성을 보였다. 이어 반하여 적색계열은 비교적 색조의 영역이 넓었으며 고채도 의 분포특성이 두드러졌다. 자색계열은 저명도.중 채도, 녹색계열은 고명도.저채도 중심이었다. 남.녀복의 색조유형으로서 여복에서는 white보다는 tone 중심의 색조특성이 나타났으며. 남복에서는 white를 제외한 tint의 색조유형이 많았다. 이는 당시대인의 백색지향 의식을 대변하는 것으로 사료된다. 음양오행론의 배색원리에 의해 검토한 결과 여복 은 상생이 남복보다 낮게 집계되었으며, 반대로 파버 비렌의 색채조화의 배색원리에 의한 검토 철과는 남 복보다 여복의 적용수치가 높았다. 이것은 감각적인 색채조화 보다는 의례적인 성향이 좀 더 징한 남복이 서구의 색채조화의 척도에 적합하지 않은 결과로 추측된다. 전통복의 배색특성은 남녀가 매우 다른 양상을 보 이고 있었다. 여복의 기본 복식구조인 저고리/치마 는 백/청색계열, 백/황색계열과의 배색이 중심으로서 면적대비 및 명도대비에 의한 조화가 이루어지고 있었다. 반면에 저고리의 배색은 유채색과 백색계열 의 배색으로 채도대비의 성향이 강했다. 남복은 황/백색계열. 백/청색계열로 명도의 차가 크지 않았다. 포/띠의 의복 구성에 있어서는 흑색 또 는 적.자색 등의 세조대(細條帶)로 인해 채도대비, 면적대비, 명도대비의 배색효과를 찾아볼 수 있었다. 이상과 같은 분석결과를 통한 한국인의 색사용의 특정은 복식의 전면에 등장하는 백색지향과 음양오 행설을 그 배경으로 하고 있다. 백색위주의 색사용은 인공미가 배제된 자연미의 추구에 기인한 것으로 토착화된 한국의 색으로 볼 수 있다. 백색은 여러 색을 통합하고 배색된 색채착화된 한국의 색으로 볼 수 있다. 백색은 여러 색을 통합하고 배색된 색채들을 담하게 만드는 것이 특징 으로 한국전통 복식의 배색특성을 주도하고 있었다. 마지막으로 본 연구는 회화자료를 근거한 것으로 풍속화의 변색 및 탈색에 의해 당시대의 정확한 색채규명이 어려우며, 실물작품이 아닌 도판을 통한 측 색으로 색의 오차가 발생할 수 있음을 연구의 한계 점으로 언급하고자 한다.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.45 no.1
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• pp.55-63
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• 2008

Ridge orientations of fingerprint image are crucial informations in many parts of fingerprint recognition such as enhancement, matching and classification. Therefore it is essential to extract the ridge orientations of image accurately because it directly affects the performance of the system. The two main properties of ridge orientation are 1) global characteristic(gradual change in whole part of fingerprint) and 2) local characteristic(abrupt change around core and delta points). When we only consider the local characteristic, estimated ridge orientations are well around singular points but not robust to noise. When the global characteristic is only considered, to estimate ridge orientation is robust to noise but cannot represent the orientation around singular points. In this paper, we propose a novel method for estimating ridge orientation which represents local characteristic specifically as well as be robust to noise. We reduce the noise caused by scar using iterative outlier rejection. We apply adaptive measurement resolution in each fingerprint area to estimate the ridge orientation around singular points accurately. We evaluate the performance of proposed method using synthetic fingerprint and FVC 2002 DB. We compare the accuracy of ridge orientation. The performance of fingerprint authentication system is evaluated using FVC 2002 DB.

• Journal of Korean Society of Transportation
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• v.18 no.6
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• pp.89-99
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• 2000

To cope with the limits of conventional O-D trip matrix collecting methods, several approaches have been developed. One of them is bilevel Programming method Proposed by Yang(1995), which uses Sensitivity Analysis Based(SAB) algorithm to solve Generalized Least Square(GLS) problem. However, the SAB a1gorithm has revealed two critical short-comings. The first is that when there exists a significant difference between target O-D matrix and true O-D matrix, SAB algorithm may not produce correct solution. This stems from the heavy dependance on the historical O-D information, in special when gravel Patterns are dramatically changed. The second is the assumption of iterative linear approximation to original Problem. Because of the approximation, SAB algorithm has difficulty in converging to Perfect Stackelberg game condition. So as to avoid the Problems. we need a more robust and stable solution method. The main purpose of this Paper is to show the problem of the dependency of Previous models and to Propose an alternative solution method to handle it. The Problem of O-D matrix estimation is intrinsically nonlinear and nonconvex. thus it has multiple solutions. Therefore it is necessary to require a method for searching globa1 solution. In this paper, we develop a solution algorithm combined with genetic algorithm(GA) , which is widely used as probabilistic global searching method To compare the efficiency of the algorithm, SAB algorithm suggested by Yang et al. (1992,1995) is used. From the results of numerical example, the Proposed algorithm is superior to SAB algorithm irrespective of travel patterns.

• 한국HCI학회:학술대회논문집
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• 2008.02a
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• pp.210-214
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• 2008

It is actually impossible to model and store all objects which exist in real home environment into robot's database in advance. To resolve this problem, this paper proposes new object modeling method that can be available for robot self-modeling, which is capable of estimating whole model's shape from partial surface data using Generic Model. And this whole produce is conducted to cylindrical objects like cup, bottles and cans which can be easily found at indoor environment. The detailed process is firstly we obtain cylinder's initial principle axis using points coordinates and normal vectors from object's surface after we separate cylindrical object from 3D image. This 3D image is obtained from 3D sensor. And second, we compensate errors in the principle axis repeatedly. Then finally, we do modeling whole cylindrical object using cross sectional principal axis and its radius To show the feasibility of the algorithm, We implemented it and evaluated its accuracy.

• Journal of the Institute of Convergence Signal Processing
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• v.11 no.3
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• pp.232-237
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• 2010

In this paper, a slit light laser range finding method using perspective warping calibration is proposed. This approach has an advantage to acquire relatively high accuracy, although the optical system is nonlinear. In the calibration, we detect the calibration points which are marked on the calibration panel and acquire the center position of the slit light laser in the image, which are used for computing the real positions of the slit light by using perspective warping. A calibration file is obtained by integrating the calibration data with the transition of the panel. The range data is acquired by interpolating the center position of the slit light laser to the calibration coordinates. Experimental results show that the proposed method provides the accuracy of 0.08mm error in depth range of 130mm with the low cost optical system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.10
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• pp.1280-1287
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• 2020

This paper proposes a vision-based food recognition method for automated production of custom cakes. A small camera module mounted on a food art printer recognizes objects' shape and estimates their center points through image processing. Through the perspective transformation, the top-view image is obtained from the original image taken at an oblique position. The line and circular hough transformations are applied to recognize square and circular shapes respectively. In addition, the center of gravity of each figure are accurately detected in units of pixels. The test results show that the shape recognition rate is more than 98.75% under 180 ~ 250 lux of light and the positioning error rate is less than 0.87% under 50 ~ 120 lux. These values sufficiently meet the needs of the corresponding market. In addition, the processing delay is also less than 0.5 seconds per frame, so the proposed algorithm is suitable for commercial purpose.