• Journal of Korea Water Resources Association
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• v.54 no.9
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• pp.643-656
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• 2021

Recently, water supply management technology is highly developed, and a computer simulation model plays a critical role for estimating hydraulics and water quality in water distribution networks (WDNs). However, a simulation of complex large water networks is computationally intensive, especially for the water quality simulations, which require a short simulation time step and a long simulation time period. Thus, it is often prohibitive to analyze the water quality in real-scale water networks. In this study, in order to improve the computational efficiency of water quality simulations in complex water networks, a hierarchical water-quality-simulation technique was proposed. The water network is hierarchically divided into two sub-networks for improvement of computing efficiency while preserving water quality simulation accuracy. The proposed approach was applied to a large-scale real-life water network that is currently operating in South Korea, and demonstrated a spatiotemporal distribution of chlorine concentration under diverse chlorine injection scenarios.

• Archives of Hand and Microsurgery
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• v.23 no.4
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• pp.296-300
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• 2018

Penile shaft reconstruction requires adequate soft tissue characteristics as well as constant vascular pedicles when considering a perforator flap. The free flap technique using various donor sites and regional conventional and perforator flaps have been utilized for penile shaft reconstruction. Still, the free flap techniques include challenging surgical procedures in addition to postoperative management. The regional flap can be applied to limited defects due to the size and shape. We performed the bilateral superficial external pudendal artery (SEPA) perforator flaps in order to reconstruct a circumferential penile shaft defect. The circumferential wound has noted necrotic tissue involving superficial (Dartos) fascia. We underwent debridement, preserving deep (Buck's) fascia and corpus spongiosum. Thereafter, the soft tissue defect was covered with bilateral SEPA perforator flaps. The patient has been observed for 27 months, showing penile resilience without deformity or wound-related problems.

• Journal of the Korean Society for information Management
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• v.36 no.2
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• pp.79-104
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• 2019

Recently, various methods of collecting and preserving social media have been discussed in the field of archives and records management as social media is actively used as a way of communicating with the public in the government. In the United States, there is a move to acquire and preserve social media at the government level, and the National Archives (UK) already provides social media archives to users through Twitter and YouTube. In this study, we proposed the features, acquisition methods of social media by type and the preservation model based on case study results in terms of acquisition and preservation of social media archiving. In order to verify the effectiveness of the proposed methods, this study was applied to the social media of Gyeongsangnamdo provincial government. The results of this study is meaningful in that it suggested acquisition and preservation methods through actual collected results and it is expected that it will be useful for establishing the models for future social media archiving.

• Journal of the Geological Society of Korea
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• v.54 no.5
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• pp.501-511
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• 2018

Geoparks are worth preserving in an environmentally and heritage. Monitoring and public attention are essential for the conservation and protection of geoparks. The use of Unmanned Aerial Vehicles and the Structure from Motion algorithm enables effective monitoring of geoparks that are difficult to manage due to their wide range of manpower, and various spatial data derived from SfM can be utilized to improve awareness of geoparks that have been lacking. In order to prove this, firstly, we created the 3D spatial data by using the UAV and the SfM algorithm, which is one of the National geoparks of the Hantan-Imjin River area. Using this 3D data for Virtual Reality and 3D printing. After that, we verified the possibility of promoting the geopark through a simple online survey. Finally, we propose a method to utilize all the generated data from each step to promote and research for geoparks.

• The Korean Journal of Archival Studies
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• no.58
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• pp.263-297
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• 2018

Archives of Government-Affiliated Organizations have responsibility for collecting and preserving valuable records produced during the business processes of their work and for actively serving users at the same time. This study applied Quality Function Deployment(QFD) techniques to analyzing user's actual requirements and proposing improvements for the archives service quality of central government agencies. In order to derive the components of the QFD, a survey was conducted among internal users of records centers in six central government agencies, as well as a literature study and interviews with working-level records researcher were also conducted. Afterwards, The House of Quality(HoQ) was constructed based on the user's requirements and technical characteristics derived, and the importance and priority of the recorder service technical characteristics were derived based on it. Based on the results, archives service of central government agencies should focus on improving the usability of records for internal user. Especially, it was confirm that the support for searching, reading and borrowing services should be strengthened.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.1
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• pp.257-264
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• 2019

This paper presents a single image haze removal method via a pixel-based joint BDCP (bright and dark channel prior) and a hierarchical bilateral filter in order to reduce computational complexity and memory requirement while improving the dehazing performance. Pixel-based joint BDCP reduces the computational complexity compared to the patch-based DCP, while making it possible to estimate the atmospheric light in pixel unit and the transmission more accurately. Moreover the bilateral filter, which can smooth an image effectively while preserving edges, refines the transmission to reduce the halo effects, and its hierarchical structure applied to edges only prevents the increase of complexity from the iterative application. Experimental results on various hazy images show that the proposed method exhibits excellent haze removal performance with low computational complexity compared to the conventional methods, and thus it can be applied in various fields.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.12
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• pp.1682-1687
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• 2020

We study the problem of sampling a subset of nodes of graphs for bandlimited graph signals such that the signal values on the sampled nodes provide the most information in order to reconstruct the original graph signal. Instead of directly minimizing the reconstruction error, we focus on minimizing the upper bound of the reconstruction error to reduce the complexity of the selection process. We further simplify the upper bound by applying useful approximations to propose a low-weight greedy selection process that is iteratively conducted to find a suboptimal sampling set. Through the extensive experiments for various graphs, we inspect the performance of the proposed algorithm by comparing with different sampling set selection methods and show that the proposed technique runs fast while preserving a competitive reconstruction performance, yielding a practical solution to real-time applications.

• Oral Biology Research
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• v.42 no.4
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• pp.208-215
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• 2018

The purpose of this study was to identify the risk of dysphagia among patients that visited prosthodontics department, and evaluate the difference in risks arising from oral conditions and disease in order to preliminarily intervene the various influencing factors of dysphagia. A questionnaire was given to patients that were aged 65 years or older who visited the prosthodontics department between September to December 2017. The data was collected and analyzed using the t-test, $x^2-test$ and logistic regression analysis. The mean age of the patients was 75 years. Out of 300 patients, 206 patients (68.7%) had a risk of dysphagia. There were statistically significant differences between the -non-risk and risk groups, which included the number of natural teeth, total number of teeth including prosthesis, denture use, denture discomfort, number of tooth brushing, oral dryness, digestive system diseases, and musculoskeletal diseases. Among these, oral dryness was a risk factor while the total number of teeth, including natural teeth and prostheses, served as a protective factor. More than half of the elderly patients were at risk of dysphagia. Oral dryness is influenced by many factors and it should continuously be managed. Patients should fully recover their masticatory function by preserving the remaining teeth and compensating for the missing teeth. A dental practitioner should be fully aware of the risk of dysphagia in elderly patients and be able to intervene and offer proper patient health care in advance through treatment guidelines and education.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.10
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• pp.3438-3457
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• 2022

As location-based services (LBS) are widely used in vehicular ad-hoc networks (VANETs), location privacy has become an utmost concern. Spatial cloaking is a popular location privacy protection approach, which uses a cloaking area containing k-1 collaborative vehicles (CVs) to replace the real location of the requested vehicle (RV). However, all CVs are assumed as honest in k-anonymity, and thus giving opportunities for dishonest CVs to submit false location information during the cloaking area construction. Attackers could exploit dishonest CVs' false location information to speculate the real location of RV. To suppress this threat, an edge-assisted Trusted Collaborative Anonymity construction scheme called TCA is proposed with trust mechanism. From the design idea of trusted observations within variable radius r, the trust value is not only utilized to select honest CVs to construct a cloaking area by restricting r's search range but also used to verify false location information from dishonest CVs. In order to obtain the variable radius r of searching CVs, a multiple linear regression model is established based on the privacy level and service quality of RV. By using the above approaches, the trust relationship among vehicles can be predicted, and the most suitable CVs can be selected according to RV's preference, so as to construct the trusted cloaking area. Moreover, to deal with the massive trust value calculation brought by large quantities of LBS requests, edge computing is employed during the trust evaluation. The performance analysis indicates that the malicious response of TCA is only 22% of the collaborative anonymity construction scheme without trust mechanism, and the location privacy leakage is about 32% of the traditional Enhanced Location Privacy Preserving (ELPP) scheme.

• KIPS Transactions on Computer and Communication Systems
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• v.11 no.8
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• pp.259-268
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• 2022

With prosperous usage of cloud services to improve management efficiency due to the explosive increase in data volume, various cryptographic techniques are being applied in order to preserve data privacy. In spite of the vast computing resources of cloud systems, decrease in storage efficiency caused by redundancy of data outsourced from multiple users acts as a factor that significantly reduces service efficiency. Among several approaches on privacy-preserving data deduplication over encrypted data, in this paper, the research results for improving efficiency of encrypted data deduplication using trusted execution environment (TEE) published in the recent USENIX ATC are analysed in terms of security and efficiency of the participating entities. We present a way to improve the stability of a key-managing server by integrating it with individual clients, resulting in secure deduplication without independent key servers. The experimental results show that the communication efficiency of the proposed approach can be improved by about 30% with the effect of a distributed key server while providing robust security guarantees as the same level of the previous research.