• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.529-540
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• 2003

Recently, the researches on the durability design of concrete structures have been studied. As the examples, models to evaluate the service life prediction of the structure have been developed. The purpose of this article is to develop the model for predicting remaining service life. The final aim is to provide the user time for repairing the concrete structures. In addition, it makes possible to maintain the concrete structure economically. 70 reservoirs out of the inland concrete structures were selected and concrete structures of their components were surveyed. Two methods were used for measuring carbonation; TG/DTA method and Phenolphtalein indicator and, the value of pH was measured by the pH meter, After deriving correlations of calcium carbonate and used year, duration from completion year to 2002, pH value, and concrete cover depth the model was developed for predicting remaining service life by measuring data as small as possible. The conventional models had been developed on the basis of experiment data obtained from the restricted lab environment like as carbon gas exposure. On the other hand this model was developed on the basis of measuring data obtained from the real field that the complex deterioration actions are occurred such as freezing and thawing, carbonation, steel corrosion, and so on. The reliability of the developed model will be evaluated high in this point and this model can help to maintain concrete structures economically by providing the manager time to repair the deteriorated concrete structures in site of facility management.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.5
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• pp.9-20
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• 2005

In this paper, we propose ubiTrack, a system which tracks users' location in indoor environments by employing infrared-based proximity method. Most of recently developed systems have focussed on performance and accuracy. For this reason, they adopted the idea of centralized management, which gathers all information in a main system to monitor users' location. However, these systems raise privacy concerns in ubiquitous computing environments where tons of sensors are seamlessly embedded into environments. In addition, centralized systems also need high computational power to support multiple users. The proposed ubiTrack is designed as a passive mobile architecture to relax privacy problems. Moreover, ubiTrack utilizes appropriate area as a unit to efficiently track users. To achieve this, ubiTrack overlaps each sensing area by utilizing the TDM (Time-Division Multiplexing) method. Additionally, ubiTrack exploits various filtering methods at each receiver and utilization module. The filtering methods minimize unexpected noise effect caused by external shock or intensity weakness of ID signal at the boundary of sensing area. ubiTrack can be applied not only to location-based applications but also to context-aware applications because of its associated module. This module is a part of middleware to support communication between heterogeneous applications or sensors in ubiquitous computing environments.

• Journal of Technologic Dentistry
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• v.31 no.4
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• pp.55-66
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• 2009

This research collected the curriculum for Dental Technology from a total of 20 schools --3-year colleges and 4-year colleges-- all in Korea. And we analyzed the average credits of subjects from students. As a result of this analysis, we get the conclusion below: 1. In the arithmetic mean of the major basis subjects which graduates and undergraduates answered about each subjects; Seminar, Dental morphology I II, Dental morphology practice I II, and Dental devices & instruments don't have many credits. And averages of the major application subjects credits which are Implants(especially low), Occlusal anatomy practice I II, Dental ceramics practice I II, and Dental ceramics practice are low, mostly have a converged tendency in high points. 2. In an analysis of the correlation which is based on the major basis subjects: Dental esthetic, oral anatomy I II, Dental materal practice III, Dental casting pracedure, Oral hygiene, Health & medical law, Management administration, and Medical terminology have a meaningful difference. (${\rho}$ < 0.05) 3. In an analysis of the correlation which is based on the major application subjects; Crown and bridge prosthodontics practice IV, Complete denture prosthodontics I II III, Complete denture prosthodontics practice I II III, Dental ceramics I II, Dental ceramics practice I II, Dental ceramics practice IIII, Occlusal anatomy I II, Occlusal anatomy practice I, Operative dentistry laboratory technology I, Operative dentistry laboratory technology practice II, Dental attachment laboratory technology practice, Implants, and Dental laboratory clinical practice have meaningful difference. (${\rho}$ < 0.05) 4. In an analysis of the correlation which is based on the ratio of a theory to an actual training; 40:60(38.57%) is the highest, followed by 30:70(30.04%), 50:50(23.32%), 60:40(5.83%), and 70:30(2.24%). These have meaningful difference. (${\rho}$ < 0.05) 5. In an analysis of the correlation which is based on the distinction of sex: Partial denture prosthodontics practice I II III, Complete denture prosthodontics I II III, Complete denture prosthodontics practice I II III, Occlusal anatomy practice I II, Implants, Medical terminology have meaningful difference. (${\rho}$ < 0.05) For the purpose of training entrepreneurs of middle standing who is required by a future society, Department of Dental Technology's Curriculum need to be managed with planning a curriculum which reflects opinions of graduates, undergraduates and a society, and also are considered not focusing on a supplier but focusing on a user.

• Information Systems Review
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• v.15 no.1
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• pp.105-122
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• 2013

Given the proliferation of social network services, it has become important to understand its user's continued use behavior. As users' privacy concerns in SNS have been identified as a critical barrier against forming this continued intention, many studies have focused on inducing continued intention by mitigating privacy concerns. However, this paper suggests to approach users' continued intention not only from the perspective of mitigating privacy concerns but also from the perspective of increasing potential benefits. Under the theoretical framework of privacy calculus model, we conducted cross sectional survey on 150 Facebook and 150 KakaoTalk users. The result suggests that trust mediates the relationships between privacy concerns and continued intention and between network externality and continued intention, and the influence of support for network formation on continued intention. The effect of network externality on continued intention, however, is not significant among Facebook users while it is significant among KakaoTalk users.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.4
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• pp.79-86
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• 2016

Physical layer security is cryptography technique to protect information by using physical nature of signals. Currently, many works on physical layer security have been actively researching while those researching models still have some problems to be solved. Eavesdropper does not share its channel state information with legitimate users to hide its presence. And when node transmits signal, hardware impairments are occurred, whereas many current researches assume that node model is ideal node and does not consider hardware impairments. The main features and contributions of this paper to solve these problems are as follows. First, our proposed system model deploys torch node around legitimate user to obtain channel state information of eavesdropper and considers hardware impairments by using channel state information of torch node. Second, we derive closed-form expression of intercept probability for the proposed system model. The results of the performance evaluation through various simulations to find out the effects on proposed system model in physical layer security show that imperfect channel state information does not effect on intercept probability while imperfect node model effects on intercept probability, Ergodic secrecy capacity and secrecy capacity.

• Journal of Digital Convergence
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• v.13 no.12
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• pp.75-87
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• 2015

The current study examines whether consumers' perceived usefulness of and trust in the integrated mobile payments services positively influence consumer loyalty to the payments system as well as to the online shopping websites where they have used the payments system. Moreover, the study investigates the effects of individual characteristics and brand awareness of the provider of mobile payments on perceived usefulness and trust. Online survey was administered to consumers ranging in age from 20s to 40s. Data analysis reveals that as consumers' perceived usefulness of and trust in the mobile payments system positively influence consumer loyalty to mobile payments and shopping mall websites. The results of the study suggests that e-commerce's user interface design, particularly the transaction system, should receive greater attention as a basic web element of e-commerce building rather than a set of plug-ins or so.

• Korean Journal of Environment and Ecology
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• v.1 no.1
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• pp.66-82
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• 1987

The user's composition of socia-economic characteristics in Bukhan Mountain National Park showed that male. twenties and students were 65.4 percent. 62.7 percent and 37.4 percent respectively by sex, age and occupation. In visiting purpose, the nature-oriented motive was 67.1 percent of the total. hut the picnic patterns as of neighbourhood park and the recreation patterns as of recreation ground were appeared simultaneously. In preferable place of visitors. the well-known mountain hut, camp sites and summits were prefered. The level of scenic satisfaction was 7.8 and comparatively high on considering the maximum level of 10.0. The level of total satisfaction. however, was no more than 6.3 owing to lack of accomodation facilities along trails, 63.4 percent of visitors were opposed to construction cable-car and visitors were anxious seriously about the nature deterioration. In Jeongnung valley, the number of users was the lagest, so that the maximum number of passangers a day attained to 20.000. The peak seasons of visiting were Spring and Fall, and the peak hours during a day was 10-11 hours A.M. and 3-5 hours P.M. Therefore partitioned spatial management in consideration of hiking pattern of nature park. picnic pattern as of neighbourhood park and recreation pattern as of recreation ground shall be necessary to solve the conflicts among functions.

• Journal of Internet Computing and Services
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• v.15 no.1
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• pp.73-88
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• 2014

Online communities are getting more popular with the development of information technology. It is essential that community members participate actively and share their contents or opinions continuously for the success and growth of online communities. However, it is revealed that most of members just take the role of passive observer. They are lurking community information and contents without any contribution. In this sense, this study focuses on explore lurking behavior of online community members. This study investigates the effect of the characteristics of online community, community members, and personal traits on user's lurking intention. Member familiarity and community identity have a strong positive effect on de-lurking intention, while the perception of usefulness and ease of use for communities and member expertise have a negative effect on de-lurking intention. Interestingly, users with a low level of self-esteem have higher level of motivation of participation than those with a high level of self-esteem. Finally, this study proposes several strategies to enhance information and contents sharing in online communities.

• Journal of Internet Computing and Services
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• v.13 no.6
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• pp.9-16
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• 2012

Social Network Service (SNS) such as Twitter and Facebook has explosively grown nationwide since iPhone was introduced to Korea in 2009. In addition, KakaoStory has recently opened and joined to the SNS market, and it has grown to one of the most popular SNS in the domestic market in a short period of time. Social Network Service supports not only the formation of relationship between SNS users in common interests but also various activities such as management of personal connections and the sharing of information or contents. These three types of SNS have several common functions of sharing and distributing various contents rooted on the personal relationship formed through SNS. As each SNS user has specific reasons for the use of each service, a survey was conducted targeting those who use all of Twitter, Facebook, and KakaoStory was drawn by the statistical analyses of survey answers on users' reasons for each service. This result of study suggests factors to consider in order to exploit a new SNS or to enhance an existing service and can be used as a standard of which SNS for users to select for their own different purposes. It will also provide the basic data for the trust formation, one of the ethics in the upcoming Social Era.

• Journal of Internet Computing and Services
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• v.15 no.6
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• pp.107-115
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• 2014

Recently, increased use of the internet resulted in generation of large and diverse types of data due to increased use of social media, expansion of a convergence of among industries, use of the various smart device. We are facing difficulties to manage and analyze the data using previous data processing techniques since the volume of the data is huge, form of the data varies and evolves rapidly. In other words, we need to study a new approach to solve such problems. Many approaches are being studied on this issue, and we are describing an effective design and development to build indexing engine of big data platform. Our goal is to build a system that could effectively manage for huge data set which exceeds previous data processing range, and that could reduce data analysis time. We used large SNMP log data for an experiment, and tried to reduce data analysis time through the fast indexing and searching approach. Also, we expect our approach could help analyzing the user data through visualization of the analyzed data expression.