• 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 the Korea Contents Association
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• v.11 no.7
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• pp.234-238
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• 2011

This paper will evaluate the usefulness of 3D target of CBCT by comparing human body's posture and position when simulated treatment is being carried out as well as human phantom posture and position using CBCT which is applying OBI. From the Rando Phantom which is located in the datum point moved in parallel and rotationary direction using CBCT. Then the mean and standard deviation difference on images location difference that are acquired were compared with real the Rando Phantom' moved distance. To make a plan of simulated treatment with the same procedure of real radiation therapy, we are going to setup the Rando Phantom. With an assumption that the position is set in accurate place, we measured the setup errors accroding to the change of the translation and rotation. Tests are repeated 10 times to get the standard deviation of the error values. The variability in couch shift after positioning equivalent to average residual error showed lateral $0.2{\pm}0.2$mm, longitudinal $0.4{\pm}0.3$mm, vertical $-0.4{\pm}0.1$mm. The average rotation erroes target localization after simulated $0.4{\pm}0.2$ mm, $0.3{\pm}0.3$ mm, and $0.3{\pm}0.4$ mm. The detection error by rotation is $0{\sim}0.6^{\circ}$ CBCT 3D/3D matching using the Rando Phantom minimized the errors by realizing accurate matching during simulated treatment and patient caring.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.1
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• pp.42-49
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• 2018

In this paper, a dual-band microstrip-fed monopole antenna with a DGS(defected ground structure) for WLAN(wireless local area network) applications is presented. The antenna consists of a monopole and a defected ground, which were etched on both sides of the FR-4 substrate. The defected ground structure was used to obtain the dual band, while the step-by-step reduction in the monopole width was used to improve the impedance matching of the antenna. The antenna has an overall compact size of $44{\times}51{\times}1.6mm^3$, which was optimized by varying the size of the monopole and the ground plane such that it may resonate at the 2.4 GHz and 5 GHz bands of the WLAN. The measurement results showed that the antenna operates in the frequency band of 210 MHz(2.29~2.50 GHz) and 900 MHz(5.05~5.95 GHz) for a VSWR under 2, and showed omnidirectional radiation pattern at all desired frequencies.

• The Journal of the Korea Contents Association
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• v.17 no.4
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• pp.478-487
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• 2017

In recent years, developed countries have begun to pay attention to female workers through work-family balance in order to solve the problem of low fertility and aging. Korea has been building and running a women leaders database (hereafter, women leaders DB) centered on the female professionals since 2011. In particular, the Incheon women leader DB, which was built by Incheon city in 2009, is a classic example. As of 2015, about 2,735 people are registered in Incheon Women Leaders DB and it is systematically creating the database such as age, education, career years, major, occupation, and certification. However, there are administrative problems such as unspecified definition on professionalism and data trust issues including data entry, and DB personnels are concentrated in specific fields. Also, in the case of certification proving expertise, the utilization problem has been revealed including inclusion of private certification not yet verified. In order to solve these problems, we first need to clarify the concept of women leaders and establish the standard. The second is the improvement of data consistency through DB reorganization, and third is to build a system through continuous and active public relations that is used by both job seekers and recruiters.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.2
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• pp.55-68
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• 2014

Some infrastructure these days is usually constructed under the ground for it to not interfere the foot-traffic of pedestrians, and thus, it is difficult to visually confirm the accurate location of the site where the establishments must be buried. These technical difficulties increase the magnitude of the problems that could arise from over-reliance on the experience of the worker or a mere blueprint. Such problems include exposure to flood and collapse. This paper proposes a constructor-oriented visualization system via mobile gadgets in general construction sites with occluded structures. This proposal is consisted with three stages. First, "Stage of detecting manhole and extracting features" detects and extracts the basis point of occluded structures which is unoccluded manhole. Next, "Stage of tracking features" tracks down the extracted features in the previous stage. Lastly, "Stage of visualizing occluded constructions" analyzes and synthesizes the GPS data and 3D objects obtained from mobile gadgets in the previous stages. This proposal implemented ideal method through parallel analysis of manhole detection, feature extraction, and tracking techniques in indoor environment, and confirmed the possibility through occluded water-pipe augmentation in real environment. Also, it offers a practical constructor-oriented environment derived from the augmented 3D results of occluded water-pipings.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.49 no.3
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• pp.53-61
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• 2012

This paper proposes a real-time distance measurement system of high temperature and high speed target using infrared stereo camera. We construct an infrared stereo camera system that measure the difference between target and background temperatures for automatic target measurement. First, the proposed method detects target region based on target motion and intensity variation of local region using difference between target and background temperatures. Second, stereo matching by left and right target information is used to estimate disparity about real-time distance of target. In the proposed method using infrared stereo camera system, we compare distances in three dimension trajectory measuring instrument and in infrared stereo camera measurement. In this experiment from three video data, the result shows an average 9.68% distance error rate. The proposed method is suitable for distance and position measurement of varied targets using infrared stereo system.

• Journal of the Korean earth science society
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• v.41 no.5
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• pp.531-554
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• 2020

In order to provide explanations of the practice of the abductive inquiry-based outdoor geological fieldwork education, this study examined the characteristics of students' performance in geological fieldwork before and after the introduction of explicit learning of geologic knowledge and inquiry. To this end, a 21st-class program was developed in the order of pre-evaluation, initial fieldwork, explicit learning of geologic knowledge and inquiry, and post-evaluation and applied to nine middle school students. As research data, outdoor geological fieldwork class recording data and students' activity sheets were collected and analyzed qualitatively. As a result, during the initial fieldwork, students caught clues of low geological importance and used everyday experience and/or general scientific knowledge as a rule when asked to generate hypotheses about the origin of the clues. Also, students evaluated their hypotheses by the scientific accuracy of the rule or their own criterion. Meanwhile, during the final fieldwork, students frequently caught key clues in geologic perspectives and generated geological event hypotheses related to the clues by borrowing geologic knowledge as a rule. Furthermore, students scientifically evaluated their hypotheses based on the consistency of evidence and rules. Combining these results, the effects of learners' geological knowledge and inquiry (abduction) abilities as a path model were presented in order to help students carry out a proficient abductive inquiry in geological fieldwork.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.43 no.1 s.307
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• pp.45-54
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• 2006

This paper proposed color matching technique, including display characterization, chromatic adaptation model, and gamut mapping and extension, to generate consistent colors for the same input signal in each display device. It is necessary to characterize the relationship between input and output colors for display device, to apply chromatic adaptation model considering the difference of reference white, and to compensate for the gamut which display devices can represent for reproducing consistent colors on DTV display devices. In this paper, 9 channel-independent GOG model, which is improved from conventional 3 channel GOG(gain, offset gamma) model, is used to consider channel interaction and enhance the modeling accuracy. Then, the input images have to be adjusted to compensate for the limited gamut of each display device. We proposed the gamut mapping and extension method, preserving lightness and hue of an original image and enhancing the saturation of an original image in xy chromaticity diagram. Since the hmm visual system is more sensitive to lightness and hue, these values are maintained as the values of input signal, and the enhancement of saturation is changed to the ratio of input and output gamut. Also the xy chromaticity diagram is effective to reduce the complexity of establishing gamut boundary and the process of reproducing moving-pictures in DTV display devices. As a result, reproducing accurate colors can be implemented when the proposed method is applied to LCD and PDP display devices

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.8 no.2
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• pp.67-74
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• 2009

In this paper, the multi-band antenna with CPWG(Coplanar Waveguide with Ground) feed for telematics mobile devices is designed and fabricated. The proposed antenna improves the return loss characteristic by using open-circuited stub matching and rectangular slot in the radiation patch. In addition, CPWG structure makes up for the drawback of the CPW which is variation of impedance matching according to the gap variation of the feed line and the ground. The fabricated antenna has 1.4GHz ($1.43GHz{\sim}2.83GHz$, 65%) band width on -10dB (VSWR<2) and the maximum gains are 0.8dBi, 1.34dBi, 2.41dBi, 2.53dBi, 2.6dBi and 1.51dBi on each resonant frequency that are GPS $(1.564GHz{\sim}1.585GHz)$, PCS/DCS $(1.710GHz{\sim}1.984GHz)$, WCDMA $(2.170GHz{\sim}2300GHz)$, Bluetooth/Wi-Fi/WLAN $(2.4GHz{\sim}2.483GHz)$, WiBro $(2.3GHz{\sim}2.4GHz)$, SDMB $(2.605GHz{\sim}2.655GHz)$. It also has an omni-directional radiation pattern of H-Plane.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.5
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• pp.523-532
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• 2008

In this paper, we proposed a U-shaped RFID tag antenna with isotropic radiation characteristic for the stable operation of RFID system. The proposed antenna is composed of a U-shaped half wavelength dipole and a rectangular-shaped feed. In order to have good impedance matching with a tag chip, the commercial tag chip is attached to the lower center of the feed. A gain deviation characteristic of the U-shaped tag antenna can be further improved by inserting a rectangular slit in the lower center of the U-shaped antenna body. On the condition of VSWR<2, the tag antennas of two structures satisfy the Korea UHF RFID bandwidth and showed the gain deviation of less than 1.63 dB and 0.74 dB for without slit and with slit, respectively. On the condition of VSWR<5.8, the U-shaped tag antenna showed the gain deviation of less than 3.8 dB and 1.2 dB for without slit and with slit, respectively.