• Journal of KIISE
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• v.42 no.11
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• pp.1441-1451
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• 2015

As one of the most spotlighted research areas, these days, the Internet of Things (IoT) aims to provide users with various services through many devices. Since there exist so many devices in IoT environments, it is inefficient to manually configure the domain name system (DNS) names of such devices. Thus, for IPv6-based IoT environments, this paper proposes a scheme called the DNS Name Autoconfiguration (DNSNA) that autoconfigures an IoT device's DNS name and manages it. In the procedure for generating and registering an IoT device's DNS name, the standard protocols of the Internet Engineering Task Force (IETF) are used. Since the proposed scheme resolves an IoT device's DNS name into an IPv6 address in unicast through a DNS server, it generates less traffic than multicast-based mDNS (Multicast DNS) which is a legacy DNS application for the DNS name service in the smart home. Thus, the proposed scheme is more appropriate in multi-hop IoT networks than mDNS. This paper explains the design of the proposed scheme and its service scenarios, such as smart home and smart road. It also explains the implementation and testing of the proposed scheme in the smart grid.

• 전자공학회논문지 IE
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• v.48 no.1
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• pp.30-35
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• 2011

In this paper, we propose a method to improve the performance of initial channel estimation (CE) for the multiband-OFDM (MB-OFDM) UWB. The performance of the initial CE can be generally improved as increasing the number of the used preamble symbols. The MB-OFDM specification presents two CE symbols per band in preamble format. The performance of CE estimation with two CE symbols may be satisfied in relatively high sensitivity -77.5 and -72.5 dBm for 200 Mbps and 480 Mbps data rate, respectively, but can not be enough in the degraded 55 Mbps and 110 Mbps sensitivities such as -83.5 and -80.5 dBm, respectively. A method proposed in this paper achieves the performance improvement by extending CE estimation region to packet synchronization (PS) symbols and frame synchronization (FS) symbols including two CE symbols. This can improve the CE performance in the degraded SNR and increase the link-margin by reducing the error rate in physical-layer header. The link-margin improvement obtained by the proposed CE preamble can induce the decrease of error-rate in physical-layer header and increase of communication throughput. Simulation results for the proposed initial method show that the performance is improved by about 0.7 dB at 10-4 bit-error-rate using '4' symbols than initial method using only two CE symbols.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.30 no.4
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• pp.29-50
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• 2019

This study was to suggest the considerations for application profiles of 2019 revised RDA using literature reviews and case studies according to new RDA that revised in order to reflect the LRM and linked data. First, the additional elements were recommended as the contents of application profiles such as inverse element, broader element, narrow element, domain, range, alternate label name, mapping to MARC, mapping to BIBFRAME, and RDA description examples as new elements as well as element name, element ID, element URL, description method, vocabulary encoding scheme, data provenance element, data provenance value, and notes as the elements that were already suggested by previous researches. Second, RDA rules' representations in forms of flow chart and application profiles through analyzing RDA rules were suggested in order to apply the rules to RDA application profiles to structure the rules in which every element has 4 types of description method, many conditions, and options. Third, the RDA mapping to BIBFRAME was suggested in RDA application profiles because RDA and BIBFRAME are co-related in context of content standard and encoding format, and mapping BIBFRAME and RDA is necessitated for programming BIBFRAME editors with RDA as content standard. This study will contribute to find the methods for constructing RDA application profiles and BIBFRAME application profiles with RDA as content standard.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.3A
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• pp.232-239
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• 2011

IEEE 802.11n standard provides a framework for new link adaptation. A station can request that another station provide a Modulation and Coding Scheme (MCS) feedback, to fully exploit channel variations on a link. However, if the time elapsed between MCS feedback request and the data frame transmission using the MCS feedback becomes bigger, the previously received feedback information may be obsolete. In that case, the effectiveness of the feedback-based link adaptation is compromised. If a station can estimate how fast the channel quality to the target station changes, it can improve accuracy of the link adaptation. The contribution of this paper is twofold. First, through a thorough NS-2 simulation, we show how the coherence time affects the performance of the MCS feedback based link adaptation of 802.11n networks. Second, this paper proposes an effective algorithm for coherence time estimation. Using Allan variance information statistic, a station estimates the coherence time of the receiving link. A proposed link adaptation scheme considering the coherence time can provide better performance.

• Journal of the Korean Geosynthetics Society
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• v.13 no.4
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• pp.97-107
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• 2014

Finite element modelling and analysis were conducted for the roll-type steel mats which were placed on loose sand and subjected to a standard truck wheel load in this study. The roll-type steel mats mean that the steel mats can be folded as a circle shape for the carrying to fields in cold regions where workability is limited and are developed for a rapid rehabilitation method for roadway across soft ground which is caused by thawing during the summer season in cold regions. The model is composed of link elements to simulate nonlinear behavior of connections between steel mats, thick shell elements to have flexural stiffness of the steel mats, and springs to simulate characteristics of foundation soils. The structural behaviors of the shell, link elements, and springs were verified at each modelling step through experiment and analysis. Beam and shell analysis without the link elements were conducted and compared to results obtained from the model presented in this study. Significant vertical displacement is shown in the shell model with hinge connections. Therefore, the results demonstrate that the analysis model for the roll-type steel mats on loose sand needs further detail parametric studies.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.11
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• pp.3-11
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• 2015

An advanced receiver which can manage inter-cell interference is required to cope with the explosively increasing mobile data traffic. 3rd Generation Partnership Project (3GPP) has discussed network assisted interference cancellation and suppression (NAICS) to improve signal-to-noise-plus-interference ratio (SINR) and receiver performance by suppression or cancellation of interference signal from inter-cells. In this paper, we propose the advanced receiver based on soft decision to reduce the interference from neighbor cell in LTE-Advanced downlink system. The proposed receiver can suppress and cancel the interference by calculating the unbiased estimation value of interference signal using minimum mean square error (MMSE) or interference rejection combing (IRC) receiver. The interference signal is updated using soft information expressed by log-likelihood ratio (LLR). We perform the system level simulation based on 20MHz bandwidth of 3GPP LTE-Advanced downlink system. Simulation results show that the proposed receiver can improve SINR, throughput, and spectral efficiency of conventional system.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.6
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• pp.173-184
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• 2018

As the portable traffic information collection system using probe vehicles spreads, it is becoming possible to collect road hazard information such as portholes, falling objects, and road surface freezing using in-vehicle sensors in addition to existing traffic information. In this study, we developed a integration and decision algorithm that integrates time and space in real time when multiple probe vehicles detect events such as road hazard information based on GPS coordinates. The core function of the algorithm is to determine whether the road hazard information generated at a specific point is the same point from the result of detecting multiple GPS probes with different GPS coordinates, Generating the data, (3) continuously determining whether the generated event data is valid, and (4) ending the event when the road hazard situation ends. For this purpose, the road risk information collected by the probe vehicle was processed in real time to achieve the conditional probability, and the validity of the event was verified by continuously updating the road risk information collected by the probe vehicle. It is considered that the developed hybrid processing algorithm can be applied to probe-based traffic information collection and event information processing such as C-ITS and autonomous driving car in the future.

• Journal of Korean Society of Archives and Records Management
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• v.21 no.3
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• pp.61-78
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• 2021

Records on Japanese "Comfort Women" have been individually managed by private sectors or institutions, and some are provided as digital archives on the Internet. However, records of digital archives differ in the composition and representation of metadata by individual institutions. Meanwhile, there is a lack of a consistent structure to describe the relationships between and among these records, leading to their fragmentation and disconnectedness. This paper proposes a knowledge model for interlinking the digital archival resources and builds a knowledge graph by integrating the records from distributed digital archives. It derives common elements by analyzing metadata from the diverse digital archives and expresses them in standard vocabularies to semantically describe multiple entities and relationships of the digital archival resources. In particular, the study includes the refinement of collected data to search and thread dispersed records and the enrichment of external data to provide significant contextual information of records. An evaluation of the knowledge graph is performed via a query measuring the (dis)connectivity between the distributed records. As a result, the knowledge graph is capable of interlinking and retrieving fragmented records, providing substantial contextual information on the records with external data enrichment, and searching accurately to match the user's intentions through semantic-based queries.

• Korean Journal of Food Science and Technology
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• v.54 no.1
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• pp.35-42
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• 2022

A survey was conducted to investigate the conditions of meal management and the use of thickening agents for dysphagia in long-term institutions and welfare centers in Korea. The online questionnaire for the survey comprised six questions on the general characteristics of subjects, 16 on meal management, 10 on dietitians' knowledge, and 30 on dietitians' perceived performance and importance of meal management for dysphagia. The complete data from 268 questionnaires were analyzed, and Importance-Performance Analysis (IPA) was conducted. The results of the survey indicated frequent, "difficulties due to no specific guidance on managing dysphagia meal," "lack of caregiver understanding of the importance of dysphagia meal," "lack of opportunity and time for meal education/counseling," "difficulties with management due to dietitians' lack of experience and awareness of dysphagia," and "limited understanding of cooking staff in preparing dysphagia meal." Importantly, these five parts were categorized in the low-priority region in an IPA of the performance.