• Journal of Dental Rehabilitation and Applied Science
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• v.34 no.2
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• pp.104-115
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• 2018

Purpose: The purpose of this study is to evaluate the image acquisition ability of intraoral scanners by analyzing the comprehensiveness of scanned images from standardized model, and to identify problems of the model. Materials and Methods: Cast models and 3D-printed models were prepared according to international standards set by ISO12836 and ANSI/ADA no. 132, which were then scanned by model scanner and two different intraoral scanners (TRIOS3 and CS3500). The image acquisition performance of the scanners was classified into three grades, and the study was repeated with varying surface conditions of the models. Results: Model scanner produced the most accurate images in all models. Meanwhile, CS3500 showed good image reproducibility for angled structures and TRIOS3 showed good image reproducibility for rounded structures. As for model ingredients, improved plaster model best reproduced scan images regardless of the type of scanner used. When limited to 3D-printed model, powdered surface condition resulted in higher image quality. Conclusion: When scanning structures beyond FOV (field of view) in standardized models (following ISO12836 and ANSI/ADA 132), lack of reference points to help distinguish different faces confuses the scanning and matching process, resulting in inaccurate display of images. These results imply the need to develop a new standard model not confined to simple pattern repetition and symmetric structure.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.10 no.3
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• pp.249-255
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• 2017

The finger vein recognition technology is a method to acquire a finger vein image by illuminating infrared light to the finger and to authenticate a person through processes such as feature extraction and matching. In order to recognize a finger vein, a 2D mask-based two-dimensional convolution method can be used to detect a finger edge but it takes too much computation time when it is applied to a low cost micro-processor or micro-controller. To solve this problem and improve the recognition rate, this study proposed an extraction method for the region of interest based on virtual core points and moving average filtering based on the threshold and absolute value of difference between pixels without using 2D convolution and 2D masks. To evaluate the performance of the proposed method, 600 finger vein images were used to compare the edge extraction speed and accuracy of ROI extraction between the proposed method and existing methods. The comparison result showed that a processing speed of the proposed method was at least twice faster than those of the existing methods and the accuracy of ROI extraction was 6% higher than those of the existing methods. From the results, the proposed method is expected to have high processing speed and high recognition rate when it is applied to inexpensive microprocessors.

• Journal of KIISE:Information Networking
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• v.37 no.1
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• pp.72-83
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• 2010

Group communication in a wireless mesh network is complicated due to dynamic intermediate mesh points, access control for communications between different administrative domains, and the absence of a centralized network controller. Especially, many-to-many multicasting in a dynamic mesh network can be modeled by a decentralized framework where several subgroup managers control their members independently and coordinate the inter-subgroup communication. In this study, we propose a topology-matching decentralized group key management scheme that allows service providers to update and deliver their group keys to valid members even if the members are located in other network domains. The group keys of multicast services are delivered in a distributed manner using the identity-based encryption scheme. Identity-based encryption facilitates the dynamic changes of the intermediate relaying nodes as well as the group members efficiently. The analysis result indicates that the proposed scheme has the advantages of low rekeying cost and storage overhead for a member and a data relaying node in many-to-many multicast environment. The proposed scheme is best suited to the settings of a large-scale dynamic mesh network where there is no central network controller and lots of service providers control the access to their group communications independently.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.7 no.3
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• pp.167-179
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• 2012

This research is brought to suggest the policy paradigm shift alternative and to show breakthrough by diagnosing the cons of government's current youth entrepreneurship promotion emphasizing a showup performance. More specific points, first, this paper investigate the policy limitations of government's current youth entrepreneurship promotion. Second, this paper develop upgrade model of youth entrepreneurship promotion through benchmarking the foreign successful cases. Third, this paper suggest, the alternative of taking off ver 1.0 of government's current youth entrepreneurship promotion policy paradigm, new paradigm of government policy emphasizing 'Good Quality Youth Startup.' In this research, youth entrepreneurship promotion policy should be emphasized that the implementation of the "open" system. Open systems can collaborate in the young founder of the market building, matching based entrepreneurship run in conjunction with enough experience and the founder of the startup entirely after reviewing the market, or starting to reconsider, and also will open the path be employed in the leading venture firms participating in the group market. Therefore, entrepreneurship promotion policy raising the capabilities of the current situation of young people in the business after graduating from a wide selection of alternative plan that is characterized by a large system.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.15-31
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• 2013

This paper proposes an intermediate image generation method for the viewer's view point by tracking the viewer's face, which is converted to a digital hologram. Its purpose is to increase the viewing angle of a digital hologram, which is gathering higher and higher interest these days. The method assumes that the image information for the leftmost and the rightmost view points within the viewing angle to be controlled are given. It uses a stereo-matching method between the leftmost and the rightmost depth images to obtain the pseudo-disparity increment per depth value. With this increment, the positional informations from both the leftmost view point and the rightmost view point are generated, which are blended to get the information at the wanted intermediate viewpoint. The occurrable dis-occlusion region in this case is defined and a inpainting method is proposed. The results from implementing and experimenting this method showed that the average image qualities of the generated depth and RGB image were 33.83[dB] and 29.5[dB], respectively, and the average execution time was 250[ms] per frame. Also, we propose a prototype system to service digital hologram interactively to the viewer by using the proposed intermediate view generation method. It includes the operations of data acquisition for the leftmost and the rightmost viewpoints, camera calibration and image rectification, intermediate view image generation, computer-generated hologram (CGH) generation, and reconstruction of the hologram image. This system is implemented in the LabView(R) environments, in which CGH generation and hologram image reconstruction are implemented with GPGPUs, while others are implemented in software. The implemented system showed the execution speed to process about 5 frames per second.

• Journal of Korean Society of Transportation
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• v.23 no.2
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• pp.107-116
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• 2005

The information on travel time in providing the information of traffic to drivers is one of the most important data to control a traffic congestion efficiently. Especially, this information is the major element of route choice of drivers, and based on the premise that it has the high degree of confidence in real situation. This study developed a vehicle arrival time prediction algorithm called as "VAT-DV" for 6 corridors in total 6.1Km of "Nam-san area trffic information system" in order to give an information of congestion to drivers using VMS, ARS, and WEB. The spatial scope of this study is 2.5km~3km sections of each corridor, but there are various situations of traffic flow in a short period because they have signalized intersections in a departure point and an arrival point of each corridor, so they have almost characteristics of interrupted and uninterrupted traffic flow. The algorithm uses the information on a demand volume and a queue length. The demand volume is estimated from density of each points based on the Greenburg model, and the queue length is from the density and speed of each point. In order to settle the variation of the unit time, the result of this algorithm is strategically regulated by importing the AVI(Automatic Vehicle Identification), one of the number plate matching methods. In this study, the AVI travel time information is composed by Hybrid Model in order to use it as the basic parameter to make one travel time in a day using ILD to classify the characteristics of the traffic flow along the queue length. According to the result of this study, in congestion situation, this algorithm has about more than 84% degree of accuracy. Specially, the result of providing the information of "Nam-san area traffic information system" shows that 72.6% of drivers are available.

• The Journal of Advanced Prosthodontics
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• v.11 no.5
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• pp.239-246
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• 2019

PURPOSE. The purpose of this study was to propose and assess a shade guide for pink gingival aesthetics using a Spanish population sample. MATERIALS AND METHODS. The $L^*$, $C^*$, h, $a^*$ and $b^*$ coordinates of 259 participants were measured using a spectrophotometer in 3 standardized points along the attached gingiva of the maxillary central incisors. A hierarchical clustering analysis was applied to obtain separate solutions regarding the number of shade tabs. For each of the solutions obtained, color differences (${\Delta}E^*$) were calculated using the CIELab and CIEDE2000 formulas, and the proposed shade guide was selected considering (1) the color differences between tabs and (2) the coverage error of each of the solutions. RESULTS. The proposed shade guide consisted of 8 gingival shade tabs and achieved CIELab and CIEDE2000 coverage errors of less than the respective 50:50% acceptability thresholds (${\Delta}E^*=4.6$ units and ${\Delta}E_{00}=4.1$). The coordinates for the various gingival shade tabs were as follows: Tab 1: $L^*43.3$, $a^*21.9$, $b^*12.3$ (1.6); Tab 2: $L^*42.9$, $a^*34.1$, $b^*19.1$; Tab 3: $L^*46.5$, $a^*25.8$, $b^*10.9$; Tab 4: $L^*46.5$, $a^*27.3$, $b^*15.1$; Tab 5: $L^*49.6$, $a^*23.5$, $b^*16.8$; Tab 6: $L^*51.5$, $a^*19.7$, $b^*13.6$; Tab 7: $L^*55.9$, $a^*22.0$, $b^*15.0$; and Tab 8: $L^*56.0$, $a^*19.9$, $b^*18.8$. CONCLUSION. The CIELab and CIEDE2000 coverage errors for the 8 shade tabs of the proposed gingival shade guide were significantly lower than those of other guides. Therefore, despite the limitations of this study, the proposed guide is more appropriate for matching gingival shade in the Spanish general population.

• Journal of IKEEE
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• v.25 no.2
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• pp.243-251
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• 2021

In this paper, we propose a measurement technique of indoor location based on markerless applicable to AR. The proposed technique has the following originality. The first is to extract feature points and use them to generate local patches to enable faster computation by learning and using only local patches that are more useful than the surroundings without learning the entire image. Second, learning is performed through deep learning using the convolution neural network structure to improve accuracy by reducing the error rate. Third, unlike the existing feature point matching technique, it enables indoor location measurement including left and right movement. Fourth, since the indoor location is newly measured every frame, errors occurring in the front side during movement are prevented from accumulating. Therefore, it has the advantage that the error between the final arrival point and the predicted indoor location does not increase even if the moving distance increases. As a result of the experiment conducted to evaluate the time required and accuracy of the measurement technique of indoor location based on markerless applicable to AR proposed in this paper, the difference between the actual indoor location and the measured indoor location is an average of 12.8cm and a maximum of 21.2cm. As measured, the indoor location measurement accuracy was better than that of the existing IEEE paper. In addition, it was determined that it was possible to measure the user's indoor location in real time by displaying the measured result at 20 frames per second.

• Journal of the Korea Society for Simulation
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• v.19 no.1
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• pp.143-151
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• 2010

Fingerprint classification is a step to increase the efficiency of an 1:N fingerprint recognition system and plays a role to reduce the matching time of fingerprint and to increase accuracy of recognition. It is difficult to classify fingerprints, because the ridge pattern of each fingerprint class has an overlapping characteristic with more than one class, fingerprint images may include a lot of noise and an input condition is an exceptional case. In this paper, we propose a novel approach to design a stochastic model and to accomplish fingerprint classification using a directional characteristic of fingerprints for an effective classification of various qualities. We compute the directional value by searching a fingerprint ridge pixel by pixel and extract a directional characteristic by merging a computed directional value by fixed pixels unit. The modified Markov model of each fingerprint class is generated using Markov model which is a stochastic information extraction and a recognition method by extracted directional characteristic. The weight list of classification model of each class is decided by analyzing the state transition matrixes of the generated Markov model of each class and the optimized value which improves the performance of fingerprint classification using GA (Genetic Algorithm) is estimated. The performance of the optimized classification model by GA is superior to the model before the optimization by the experiment result of applying the fingerprint database of various qualities to the optimized model by GA. And the proposed method effectively achieved fingerprint classification to exceptional input conditions because this approach is independent of the existence and nonexistence of singular points by the result of analyzing the fingerprint database which is used to the experiments.

• Economic Analysis
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• v.26 no.4
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• pp.1-38
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• 2020

In this research, we explore the effects of changes in industrial structure due to industrial restructuring on employment and growth in the Korean economy. To that end, we first investigate the impact of industrial restructuring on employment through Lilien's sectoral shift hypothesis, considering the dependence of industrial restructuring on business cycles. As a result of the analysis, we find that changes in the industrial structure have exerted a short-term effect of increasing unemployment, and that the effects of industrial restructuring are even greater during the economic downturn period. In light of these points, Lilien's sectoral shift hypothesis seems to be valid in Korea. Next, we examine the effect of industrial restructuring on economic growth in Korea by analyzing which one, between the Kuznetz hypothesis and the Baumol effect, is dominant. Empirical results reveal that the mid- to long-term effect of industrial restructuring on GDP growth is significant, which is in accordance with the Kuznets hypothesis, where resource allocation along with industrial restructuring to sectors with high productivity spurs economic growth.