• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.364-367
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• 2008

Earthwork is very equipment-intensive task and researches related to automated excavation have been conducted. There is an issue to secure the safety for an automated excavating system. Therefore, this paper focuses on how to improve safety for semi- or fully-automated backhoe excavation. The primary objective of this research is to develop object detection algorithm for automated safety system in excavation work. In order to satisfy the research objective, a diverse sensing technologies are investigated and analysed in terms of functions, durability, and reliability and verified its performance by several tests. The authors developed the objects detecting algorithm for user interface program using laser sensor. The results of this study would be the basis for developing the automated object detection system.

• Korean journal of communication and information
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• v.46
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• pp.9-36
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• 2009

In a competitive media environment, Internet Protocol television (IPTV) has gained appeal because of its essential characteristics, 'Internet and Interactivity'. Our study aims to explore predictors that affect IPTV-VOD adoption within the context of competing media (i.e., existing multi-channel video programming services, such as cable television and digital broadcasting satellite services). In addition, this study examines if IPTV-VOD functions as a substitute for existing multi-channel services, such as cable television and direct broadcasting satellite services. A self-report survey through face-to-face interviews was conducted in Seoul metropolitan area and other six big cities. Our findings showed that primary factors for adopting an IPTV-VOD are: age of user, subjective importance of terrestial broadcasting services, real-time terrestrial broadcasting services, and other interactive service characteristics, such as time-shifting. Also, IPTV-VOD services were found to be a substitute for existing multi-channel video programming services.

• Journal of Radiation Protection and Research
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• v.41 no.4
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• pp.424-435
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• 2016

Background: The International Commission on Radiological Protection (ICRP) recommendations and the Federal Guidance Report (FGR) published by the U.S. Environmental Protection Agency (EPA) have been widely applied worldwide in the fields of radiation protection and dose assessment. The dose conversion coefficients of the ICRP and FGR are widely used for assessing exposure doses. However, before the coefficients are used, the user must thoroughly understand the derivation process of the coefficients to ensure that they are used appropriately in the evaluation. Materials and Methods: The ICRP provides recommendations to regulatory and advisory agencies, mainly in the form of guidance on the fundamental principles on which appropriate radiological protection can be based. The FGR provides federal and state agencies with technical information to assist their implementation of radiation protection programs for the U.S. population. The system of radiation dose assessment and dose conversion coefficients in the ICRP and FGR is reviewed in this study. Results and Discussion: A thorough understanding of their background is essential for the proper use of dose conversion coefficients. The FGR dose assessment system was strongly influenced by the ICRP and the U.S. National Council on Radiation Protection and Measurements (NCRP), and is hence consistent with those recommendations. Moreover, the ICRP and FGR both used the scientific data reported by Biological Effects of Ionizing Radiation (BEIR) and United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) as their primary source of information. The difference between the ICRP and FGR lies in the fact that the ICRP utilized information regarding a population of diverse races, whereas the FGR utilized data on the American population, as its goal was to provide guidelines for radiological protection in the US. Conclusion: The contents of this study are expected to be utilized as basic research material in the areas of radiation protection and dose assessment.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.10a
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• pp.808-811
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• 2015

Cognitive radio has been proposed as a promising dynamic spectrum allocation paradigm. In cognitive radio, spectrum sensing is a fundamental procedure that enables secondary users (unlicensed) employing unused portion of spectrum of primary users (licensed) without causing harmful interference. However, the performance of single-user spectrum-sensing scheme was limited by fading, noise uncertainty shadowing and hidden node problem. Cooperative spectrum sensing was proposed to mitigate these problem. In this paper, we observe cooperative sensing scheme with energy detection using three adaptive thresholds for local decision, which can mitigate sensing failure problem and improve sensing performance at local node. In cooperative scheme we employed OR rules as decision combining at fusion center. We evaluate our scheme through computer simulation, and the results show that with OR combination rule our scheme can achieve best performance than other schemes.

• Journal of Digital Convergence
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• v.12 no.10
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• pp.211-222
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• 2014

This study investigates the antecedents of continuance intention of mobile SNS. In addition, it also explores the mediating role of perceived value in the relationship between the antecedent and continuance intention. This study posits that a social influence, perceived usefulness, privacy concern, and a perceived effort of use are major factors to influence continuance intention of SNS. By using a PLS analysis, this finding suggests that consumers' perception of the value of SNS which is previously overlooked, is a primary determinant of continuance intention, and the other exploratory factors are mediated through perceived value in cognitive aspect. This research aims to examine consumer's SNS continuance intention in terms of consumer's perspective, not just from the technology user perspective. Therefore, this research provides a useful guideline for marketing managers on how to manage Mobile SNS properly.

• The Journal of Korean Association of Computer Education
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• v.21 no.2
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• pp.59-71
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• 2018

The purpose of this study is suggesting the direction for improving web accessibility by analyzing the state of abiding by the web accessibility by the centers for teaching and learning support at the education offices in cities and provinces which provide the learning and teaching materials to the K-12 members and the interested people. For this aim, nine centers for teaching and learning support were evaluated. The primary manual evaluation by two experts and the evaluation by 18 users were conducted. The users were comprised of hearing-impaired people, visually-impaired people, brain-disabled people, the elderly, various browser users, and a variety of operating system users. As a result of the analysis, not a single center for teaching and learning support had conformed to web accessibility in the expert evaluation and the user evaluation. As a result of the expert evaluation, the errors regarding web design improvement, HTML source error correction, and provision of alternative measures for the disabled were found. This study is meaningful in the sense that it provided various discussions with regard to the direction of the future web accessibility evaluation based on the improved web accessibility evaluation method.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.4
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• pp.265-271
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• 2014

304L stainless steel sheets are used as a primary barrier for the insulation of membrane-type liquefied natural gas(LNG) carrier cargo containment system. 304L stainless steel is a transformation-induced-plasticity(TRIP) steel that exhibits complex material behavior, because it undergoes phase transformation during plastic deformation. Since the TRIP behavior is very important mechanical characteristics in a low-temperature environment, significant amounts of data are available in the literature. In the present study, a uniaxial tensile test for 304L stainless steel was performed to investigate nonlinear mechanical characteristics. In addition, a viscoplastic model and damage model is proposed to predict material fractures under arbitrary loads. The verification was conducted not only by a material-based comparative study involving experimental investigations, but also by a structural application to the LNG membrane of a Mark-III-type cargo containment system.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.5
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• pp.632-639
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• 2012

Ad-hoc networks can be used various environment, which it is difficult to construct infrastructures, such as shadowing areas, disaster areas, war area, and so on. In order to support to considerable and various wireless services, more spectrum resources are needed. However, efficient utilization of the frequency resource is difficult because of spectrum scarcity and the conventional frequency regulation. Ad-hoc networks employing cognitive radio(CR) system that guarantee high spectrum utilization provide effective way to increase the network capacity. In conventional CR based ad-hoc network, it uses constant threshold value to detect primary user signal, so the results become not reliable. In this paper, to solve this problem, we apply adaptive threshold value to the CR based ad-hoc network, and adaptive threshold is immediately changed by SNR(Signal to Noise Ratio). From the simulation results, we confirmed that proposed algorithm has the greatly better detection probabilities than conventional CR based ad-hoc network.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.2A
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• pp.99-106
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• 2009

In this paper, we propose UCA algorithms that are applied to the unified inter-cell interference mitigation through frequency plannings in OFDMA cellular systems. Under three frequency plannings, UCA algorithms allocate frequency channels to UEs(User Equipments). Proposed UCA algorithms require the information of received signal power from home sector and neighbor sectors respectively. We compare all possible combinations of UCA algorithms and frequency plannings through compute simulation. A primary performance measure is the low 5th percentile of SINR at UEs. The proposed UCA algorithms can avoid the interference to neighbor cells by allocating relatively low transmit power to centrally-located UEs and cancel inter-cell interference at cell-edge UEs by a coordinated symbol repetition. We show that UCA algorithm 2 applied in frequency planning 1 is promising among other combinations of UCA algorithms and frequency palnnings in terms of the low 5th percentile of SINR at UEs.

• Journal of the Korean association of regional geographers
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• v.4 no.2
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• pp.65-77
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• 1998

One of the fundamental, important preconditions for effective teaching of geography is to collect a variety of picture data available for class and to manage the data systematically. The purpose of this study is to present one method about how to supply basic picture data available for class of Korean geography for the high school program to teachers in service and how to collect, manage and utilize the data. A total of 233 picture data related to contents of the textbook of Korean Geography have been gathered through this study, and a database has been constructed for the data. Directories were generated for individual units of the textbook, and the collected picture data was stored in the image file of each directory. This data was recorded in a CD and attached as an appendix. Since the primary purpose of this study is to suggest one method, the picture data in a database for the present study is just a fraction of lots of data available for class of Korean geography. If the user persistently enlarges and manages data based on the results of this study, the data will become a good instructional aid. The picture data can be printed over the transparent film and used for class by using the overhead protector (OHP), or it can be also used as a remote self-study tool through the computer telecommunications network (e.g., LAN or INTERNET. etc,). Most desirable, however, is to develop teachers' own method by taking account of separate units of the textbook or diverse educational environments.