• The Journal of Korean Academy of Prosthodontics
• /
• v.54 no.2
• /
• pp.93-102
• /
• 2016

Purpose: The aim of this study was to evaluate the fit accuracy of two zirconia and titanium abutments in internal hexagonal implants. Materials and methods: One titanium abutment and two zirconia abutments were tested in internal hexagonal implants (TSV, Zimmer). Prefabricated zirconia abutments (ZirAce, Acucera) and customized zirconia abutments milled by the Zirkonzahn system (Zirkonzahn Max, Zirkonzahn) were selected and prefabricated titanium abutments (Hex-Lock, Zimmer) were used as a control. Eight abutments per group were connected to implants with 30 Ncm torque. The marginal gaps at abutment-implant interface, the internal gaps at internal hex, vertical and horizontal gaps between screws and screw seats in abutments were measured after sectioning the embedded specimens using a scanning electron microscope. Data analysis included one-way analysis of variance and the Scheffe test (n=16, ${\alpha}=0.05$). Results: The mean marginal gap of customized zirconia abutment was higher than those of two prefabricated zirconia and titanium abutments. The internal gaps at internal hex showed no significant differences between customized and prefabricated abutments and were higher than those of prefabricated titanium abutments. The mean vertical and horizontal gaps at screw in prefabricated zirconia abutment were higher than those of prefabricated titanium abutment. In the case of customized zirconia abutment, the mean horizontal gap at screw was higher than those of both the prefabricated zirconia and the titanium abutment but the mean vertical gap was not even measureable. The screw seats were clearly formed but did not match with abutment screws in prefabricated zirconia abutments. They were not, however, precisely formed in the case of customized zirconia abutments. Conclusion: Within the limitations of this study, the prefabricated titanium abutments showed better fit than the zirconia abutments, regardless of customized or prefabricated. Also, the customized zirconia abutments showed significantly higher marginal gaps and the fit was less accurate between screws and screw seats than the prefabricated abutments, titanium and zirconia.

• The Journal of Society for e-Business Studies
• /
• v.22 no.2
• /
• pp.137-152
• /
• 2017

The decline in the price of IT devices and the development of the Internet have created a new field called Internet of Things (IoT). IoT, which creates new services by connecting all the objects that are in everyday life to the Internet, is pioneering new forms of business that have not been seen before in combination with Big Data. The prospect of IoT can be said to be unlimited in its utilization. In addition, studies of standardization organizations for smooth connection of these IoT devices are also active. However, there is a part of this study that we overlook. In order to control IoT equipment or acquire information, it is necessary to separately develop interworking issues (IP address, Wi-Fi, Bluetooth, NFC, etc.) and related application software or apps. In order to solve these problems, existing research methods have been conducted on augmented reality using GPS or markers. However, there is a disadvantage in that a separate marker is required and the marker is recognized only in the vicinity. In addition, in the case of a study using a GPS address using a 2D-based camera, it was difficult to implement an active interface because the distance to the target device could not be recognized. In this study, we use 3D Depth recognition camera to be installed on smartphone and calculate the space coordinates automatically by linking the distance measurement and the sensor information of the mobile phone without a separate marker. Coordination inquiry finds equipment of IoT and enables information acquisition and control of corresponding IoT equipment. Therefore, from the user's point of view, it is possible to reduce the burden on the problem of interworking of the IoT equipment and the installation of the app. Furthermore, if this technology is used in the field of public services and smart glasses, it will reduce duplication of investment in software development and increase in public services.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.30 no.3
• /
• pp.206-214
• /
• 2014

This study is to evaluate how different bearing surface angles of abutment screw affect the mechanical stability of the joint in the conical seal design implant system. Materials and Methods: Internal connection type regular implants, two-piece cemented type abutments and tungsten carbide/carbon-coated titanium alloy abutment screws were selected. Titanium alloy screws with conical ($45^{\circ}$) and flat ($90^{\circ}$) head designs which fit on to abutment were fabricated. The abutments were tightened to implants with 30 Ncm by digital torque gauge. The loading was applied once to the central axis of abutment. The mean axial displacement was measured using micrometer before and after the tightening and loading (n = 5). The abutment was tightened to implants with 30 Ncm and T-shape stainless steel crown was cemented. Then the change in the amount of reverse-torque was measured after the repeated loading to the central axis, and the place 5 mm away from the central axis. Compressive bending and fatigue strength were measured at the place 5 mm away from the central axis (n = 5). Results: Both groups showed the largest axial displacement when abutment screw tightening and total displacement was greater in the flat head group compared to conical head group (P < 0.05). However, there were no significant differences in reverse torque value, compressive bending and fatigue strength (P > 0.05). Conclusion: Within the limitations of this study, the abutment screw head design had no effect on two groups regarding the joint stability, however the conical head design affected the settlement of abutment resulting in the reduced total displacement.

• Korean Journal of Environment and Ecology
• /
• v.35 no.2
• /
• pp.164-180
• /
• 2021

Plants Social Network(PSN) analysis combines the plant sociological method and the social network analysis to understand plant society focusing on environmental-to-plant and plant-to-plant relationships. PSN is at an early stage of research and require comparing plant society analyses in various environments and existing interspecies binding analysis. This study conducted a vegetation structural analysis of Mudeungsan National Park and compared the existing interspecies connection analysis with the PSN. A total of 60 plots were established for a survey on the Old Trail. The TWINSPAN and DCA analysis showed that the 60 survey plots were divided into the Quercus serrata-Pinus densiflora community (Community I) and the Quercus mongolica community (Community II) based on an altitude of 800 meters. We performed the interspecies correlation with more than 30% emergence frequency and the DCA analysis and compared the results with a focus on the major species in each colony. The results showed that Quercus serrata had a correlation of -0.450^** and -0.375^** with Pinus densiflora and Quercus mongolica, respectively. The DCA analysis also confirmed that Quercus serrata was located close to Pinus densiflora and far from Quercus mongolica along one axis. For the PSN analysis of PSN, 40 survey plots were added to investigate the species appearing in a total of 100 survey plots. The network structural analysis showed 378 links and a species having an average of 6 interspecies bindings. The density was 0.097, the diameter was 7, and the average path distance was 2.788, similar to the PSN analysis results of the Busan Metropolitan City. The plant social network analysis showed similar results to the existing interspecies combination analysis, enabling analyzing more data than the existing methods and observing the structure of plant society.

• Journal of the Daesoon Academy of Sciences
• /
• v.47
• /
• pp.173-202
• /
• 2023

In this study, we delve into the potential for innovative cultural education techniques that utilize the timeless tales of Princess Bari and The Tale of Shim Cheong as tailored for the upcoming generations of overseas Korean learners. With a rising number of young overseas Koreans born and raised in their host countries, there emerges a pressing need to craft an educational framework that resonates with the evolving dynamics of their generation. Our endeavor revolves around proposing educational strategies that help solidify identity while carefully considering the intrinsic motivation prevalent among most overseas Koreans. Naturally, the choice of employing the classic epics Princess Bari and The Tale of Shim Cheong as educational resources was deliberate. These narratives are rich in rites of passage and offer profound insights into the transformative journey of their protagonists. Both characters are affluent women in patriarchal societies, and both embark on quests to redefine themselves through new relationships, liberating themselves from the confines of parental ties. This narrative framework provides a unique opportunity for overseas Koreans who are often adrift in the social fabric of their adopted countries. These stories inspire them to introspect and contemplate their own identities. By intertwining their personal narratives with the empowering stories of characters, students are provided a chance to reaffirm their authentic selves. Therein, a paradigm shift can occur that allows individuals to embrace the core elements that define them. Our ultimate objective was to enable students to explore their own stories and immerse themselves in the intricate narratives of classical works. This immersive experience fosters a profound sense of unity with the characters and paves the way for a comprehensive educational plan. This plan not only celebrates the hybrid nature of identity but also cultivates a deep sense of positivity within amalgamated 'subjects.' Such an approach not only fosters a stronger connection with one's heritage but also sparks a genuine curiosity about and affinity for the rich cultural tapestry of one's home country. It's not just education; it's a transformative journey that enriches the lives of overseas Koreans and nurtures a profound bond with their cultural roots.

• Journal of the Korean association of regional geographers
• /
• v.19 no.2
• /
• pp.324-339
• /
• 2013

This study aims to investigate the characteristics of cyber communities composed of migrant workers from communities without propinquity in Korea. Its methods are both qualitative and quantitative. It further seeks to discover the relationship between the social capital formed and reproduced within these cyber communities and participants' cultural adaptation to Korean society. The study revealed that ethnic and non-ethnic communities differed in terms of strength of cohesion, space constraints, and links with the outside world. The former showed characteristics of a localized community type. The main motivations for migrant workers' participation in the ethnic cyber community were communication and friendship rather than cooperation and sharing among members. They usually used cyber communication media to communicate with one another. Conversely, the latter showed characteristics of an integrative type. Despite the difficulties in applying for membership and information provided in Korean, a high percentage of migrant workers participated in the community to obtain crucial information. The results did not show a significant correlation between social capital and migrant workers' traits within the cyber community, while a strong correlation emerged among four factors of social capital: faith, norms, networking, and political participation. The study showed that social capital in the cyber community was in direct proportion to an integrative type of cultural adaptation to Korean society. In particular, there was a strong connection between the cultural adaptation exhibited by members of the migrant subculture and their participation in discussions on political issues and human rights, with some migrants even functioning as agents of social change as participants in citizens' movements. The findings suggest that the cyber community facilitates the migrant subculture's communication with and integration into the indigenous Korean culture. Migrant workers' participation in the cyber community is therefore validated as an instrumental practice for members of this subculture to adapt to Korean society.

• Journal of Chest Surgery
• /
• v.31 no.7
• /
• pp.660-667
• /
• 1998

Background: This study is to evaluate the effectiveness and application of Lecompte procedure as a treatment for various complex cardiac anomalies with pulmonary outflow tract obstruction. Methods: Between July 1988 and December 1997, 44 patients underwent Lecompte procedure in Seoul National University Children's Hospital. The male to female ratio was 24 to 20 and the mean age was 29.2 months(range, 3 to 83). Of these patients, 28(63.6%) had transposition of great arteries with ventricular septal defect and pulmonary stenosis(or pulmonary atresia), 14(31.8%) had double outlet right ventricle with pulmonary stenosis(or pulmonary atresia), and so on. The principles of the technique are 1) extension of the ventricular septal defect or conal resection, 2) construction of a intracardiac tunnel connecting the left ventricle to the aorta, and 3) direct connection, without a prosthetic conduit, of the pulmonary trunk to the right ventricle. Results: There were 3 in-hospital deaths and their causes were sustained hypoxia, myocardial failure, and sepsis, respectively. There was 1 late death due to sepsis. Reoperations were performed in 6 patients who had pulmonary outflow tract obstructions(4 cases), residual muscular ventricular septal defect(1 case), and recurrent septic vegetation(1 case). The cumulative survival rates by the Kaplan-Meier method were 92.7%, 92.7%, and 92.7% at 1, 2, and over 4 years. The reoperation free survival rates were 92.7%, 92.7%, and 70.2% at 1, 3, and over 5 years. Among the risk factors for the operative death, aortic cross clamping time had statistical significance(p<0.05) and all the risk factors for the recurrent pulmonary stenosis such as age, pulmonary artery index, and materials used for the pulmonary outflow tract reconstruction had no statistical significance(p>0.05). Conclusions: Our review suggests that Lecompte procedure is an effective treatment modality for various complex cardiac anomalies with pulmonary outflow tract obstruction. Repair in early age is possible and the rates of mortality and morbidity are also acceptable.

• Journal of Educational Research in Mathematics
• /
• v.22 no.1
• /
• pp.1-22
• /
• 2012

The purpose of this study is to understand Korea students' characteristics as well as to give important information of improving our education using comparative analysis of framework, test booklets, test results between PISA 2009 and NAEA 2009. PISA 2009 was administered on May of 2009 and NAEA was administered on October of same year. The summary of the results of comparing two assessment is as follows First, cut score of NAEA Advance level is bigger than the cut score of level 5, which is considered as high achievement level. The cut score of Basic level of NAEA is also higher than the level 2 of PISA, which is considered as basic achievement level. This phenomenon can show that NAEA achievement level is set little bit higher than the achievement level of PISA in mathematics domain. Second, the percentage of female students on higher level was higher than that of male students. In suburban area, the percentage of high level was small and the percentage of low level was big. Third, students of Advanced level are distributed concentrating in PISA levels 4~6, Proficient achievement level concentrating in PISA levels 3~5, Basic achievement level concentrating in PISA levels 2~4, and below basic achievement levels concentrating in below level 1 and level 3 of PISA. Fourth, the correlation between NAEA 2009 and PISA 2009 achievement scores are significantly positive. However, the correlation of subscales were low. Fifth, analysis of non-equivalent group, 11 items located in 'change and relationship', 'uncertainty', 'connection cluster' domains found to be significantly different. The percent correct showed very big difference. The analysis results presents the implication of mathematics curriculum, teaching and learning methods as well as National Assessment of Educational Achievement.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.25 no.4
• /
• pp.375-390
• /
• 2009

Statement of problem: Implant supported overdenture is accepted widely as a way to restore edentulous ridge providing better retention and support of dentures. Various types of attachment for overdenture have been developed. Purpose: The purpose of this study was to investigate the influence of attachment type in implant overdentures on the biomechanical stress distribution in the surrounding bone, prosthesis and interface between implant and bone. Material and methods: Finite element analysis method was used. Average CT image of mandibular body(Digital $Korea^{(R)}$, KISTI, Korea) was used to produce a mandibular model. Overdentures were placed instead of mandibular teeth and 2mm of mucosa was inserted between the overdenture and mandible. Two implants($USII^{(R)}$, Osstem, Korea) were placed at both cuspid area and 4 types of overdenture were fabricated ; ball and socket, Locator, magnet and bar type. Load was applied on the from second premolar to second molar tooth area. 6 times of finite element analyses were performed according to the direction of the force $90^{\circ}$, $45^{\circ}$, $0^{\circ}$ and unilateral or bilateral force applied. The stress at interface between implants and bone, and prosthesis and the bone around implants ware compared using von Mises stress. The results were explained with color coded graphs based on the equivalent stress to distinguish the force distribution pattern and the site of maximum stress concentration. Results: Unilateral loading showed that connection area between implant fixture and bar generated maximum stress in bar type overdentures. Bar type produced 100 Mpa which means the most among 4 types of attachments. Bilateral loading, however, showed that bar type was more stable than other implants(magnet, ball and socket). 26 Mpa of bar type was about a half of other types on overdenture under $90^{\circ}$ bilateral loading. Conclusions: In any directions of stress, bar type was proved to be the most vulnerable type in both implants and overdentures. Interface stress did not show any significant difference in stress distribution pattern.

• Journal of Intelligence and Information Systems
• /
• v.12 no.1
• /
• pp.17-31
• /
• 2006

In this paper, passport recognition and face verification methods which can automatically recognize passport codes and discriminate forgery passports to improve efficiency and systematic control of immigration management are proposed. Adjusting the slant is very important for recognition of characters and face verification since slanted passport images can bring various unwanted effects to the recognition of individual codes and faces. Therefore, after smearing the passport image, the longest extracted string of characters is selected. The angle adjustment can be conducted by using the slant of the straight and horizontal line that connects the center of thickness between left and right parts of the string. Extracting passport codes is done by Sobel operator, horizontal smearing, and 8-neighborhood contour tracking algorithm. The string of codes can be transformed into binary format by applying repeating binary method to the area of the extracted passport code strings. The string codes are restored by applying CDM mask to the binary string area and individual codes are extracted by 8-neighborhood contour tracking algerian. The proposed RBF network is applied to the middle layer of RBF network by using the fuzzy logic connection operator and proposing the enhanced fuzzy ART algorithm that dynamically controls the vigilance parameter. The face is authenticated by measuring the similarity between the feature vector of the facial image from the passport and feature vector of the facial image from the database that is constructed with PCA algorithm. After several tests using a forged passport and the passport with slanted images, the proposed method was proven to be effective in recognizing passport codes and verifying facial images.