• ETRI Journal
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• v.28 no.3
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• pp.282-290
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• 2006

In vertically overlaid cellular systems, a temporary traffic concentration can occur in a hot-spot area, and this adversely affects overall system capacity. In this paper, we develop an adaptive hot-spot operating scheme (AHOS) to mitigate the negative effects from the nonuniform distribution of user location and the variation in the mixture of QoS requirements in orthogonal frequency division multiple access downlink systems. Here, the base station in a macrocell can control the operation of picocells within the cell, and turns them on or off according to the system overload estimation function. In order to determine whether the set of picocells is turned on or off, we define an AHOS gain index that describes the number of subcarriers saved to the macrocell by turning a specific picocell on. For initiating the picocell OFF procedure, we utilize the changes in traffic concentration and co-channel interference to the neighboring cells. According to computer simulation, the AHOS has been proved to have maximize system throughput while maintaining a very low QoS outage probability under various system scenarios in both a single-cell and multi-cell environments.

• Journal of the Korea Society of Computer and Information
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• v.10 no.3 s.35
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• pp.119-132
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• 2005

The health care system revolutionized by the use of information and communication technologies. Computer information processing and electronic communication technologies play an increasingly important role in the area of health care. We propose a new role based access control model for pervasive health care systems, which changed location, time, environment information. Also our model can be solved the occurrence of an reduction authority problem to pervasive health care system at emergency environment. We propose a new role based access control model for pervasive health care systems, which combines role-to-role delegations, negative permission, context concept and dynamic context aware access control. With out approach we aim to preserver the advantages of RBAC and offer groat flexibility and fine-grained access control in pervasive healthcare information systems.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.3
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• pp.346-350
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• 2010

Since sensor nodes have restriction of using resources in Zigbee network, number of study on improving efficiency is currently ongoing[1]. Clustering mechanism based on hierarchy structure provides a prevention of duplicated information and a facility of a network expansion[2]. however overheads can occurs when the cluster header is elected and the election of a incorrect cluster header causes to use resources inefficiently. In this paper, we propose that the cluster header election mechanism using distances between nodes and density of nodes in accordance with the operation of the central processing system in which the sync nodes are having information of location and energy with respect to general nodes based on hierachy clustering mechanism.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.2
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• pp.357-364
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• 2015

Tags and Readers is receiving and sending the data using the wireless communication in the RFID environment. Therefore, it could allow an attacker to participate in the network without the physical constraints, which can be easily exposed to a variety of attacks, such as taps and data forgery. Also, it is not easy to apply the security techniques to defend external attacks because the resource constraints of RFID tags is high. In this paper, new tag-reader mutual authentication protocol is proposed to protect the external cyber attacks such as spoofing attacks, replay attacks, traffic analysis attacks, location tracking attacks. The performance evaluation of the proposed mutual authentication protocol is performed and the simulation results are presented.

• The Journal of the Korea institute of electronic communication sciences
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• v.16 no.2
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• pp.363-370
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• 2021

The perimeter intrusion detection system is very important in physical security. In this study, a micro smart device (module) using MEMS sensor was developed in IoT environment for external intrusion detection. The outer intrusion detection system applying the smart device developed in this study is installed in various installation environments, such as barbed wire of various materials and shapes, the city center, the beach, and the mountain, so that it can detect external intrusion and its location as well as false alarms. As a smart sensor that can minimize the false alarm rate and economical construction cost, it is expected that it can be used for the safe operation of major facilities and prevention of disasters and crimes.

• Journal of Ecology and Environment
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• v.43 no.1
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• pp.1-8
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• 2019

Background: Hibernating bats exhibit ubiquitous winter activity in temperate zones, but there is considerable between- and within-species variety in their intensity and purpose. Bats may fly during winter for sustenance or travel to other hibernacula. This study compared inter-regional variation in the winter activity of the greater horseshoe bat (Rhinolophus ferrumequinum). We predicted that weather and hibernacula-environmental conditions would influence winter activity patterns. Results: Winter activity patterns differed between regions. In the Anseong area, we confirmed movement inside the hibernaculum, but in Hampyeong, we observed movement both inside and between hibernacula. The two regions differ by $4^{\circ}C$ in average winter temperatures. Anseong experiences 22 days during which average daily temperatures exceeded $5^{\circ}C$, whereas Hampyeong experienced 50 such days. During the hibernating period, bat body weight decreased by approximately 17-20% in both regions. Conclusions: Ambient temperatures and winter-roost environments appear to be behind regional differences in hibernating bat activity. As winter temperatures in Korea do not favor insect activity, feeding probability is low for bats. However, bats may need to access water. At Anseong, underground water flows inside the hibernaculum when the reservoir outside is frozen. At Hampyeong, the hibernaculum does not contain a water source, but the reservoir outside does not freeze during winter. In conclusion, water-source location is the most likely explanation for regional variation in the winter activity of hibernating bats.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.165-168
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• 2021

Recently, the spread of deep learning environments has increased the importance of dataset generation. In this paper, we aim to design and implement a method for capturing rotating images of objects and performing object tracking on them for efficient dataset generation. The method implemented in this paper is to obtain image data by rotating objects to capture multiple angles of objects, detect and track objects through background removal and difference image processing techniques, showing them on screen to monitor object tracking results in the current frame. It was then implemented to return object location data within the image for use as a dataset.

• Journal of Web Engineering
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• v.21 no.1
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• pp.27-52
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• 2021

With recent increases in the number of network-connected devices, the number of edge computing services that provide similar functions has increased. Therefore, it is important to recommend an optimal edge computing service, based on quality-of-service (QoS). However, in the real world, there is a cold-start problem in QoS data: highly sparse invocation. Therefore, it is difficult to recommend a suitable service to the user. Deep learning techniques were applied to address this problem, or context information was used to extract deep features between users and services. However, edge computing environment has not been considered in previous studies. Our goal is to predict the QoS values in real edge computing environments with improved accuracy. To this end, we propose a GAIN-QoS technique. It clusters services based on their location information, calculates the distance between services and users in each cluster, and brings the QoS values of users within a certain distance. We apply a Generative Adversarial Imputation Nets (GAIN) model and perform QoS prediction based on this reconstructed user service invocation matrix. When the density is low, GAIN-QoS shows superior performance to other techniques. In addition, the distance between the service and user slightly affects performance. Thus, compared to other methods, the proposed method can significantly improve the accuracy of QoS prediction for edge computing, which suffers from cold-start problem.

• Journal of Internet of Things and Convergence
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• v.10 no.4
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• pp.71-76
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• 2024

The importance of location-based services has been steadily rising, leading to the increased integration of Ultra-Wideband (UWB) technology in mobile devices and vehicles. Conventional UWB-based positioning systems typically determine the distance and direction between devices or track locations by pre-installing UWB anchors in environments like buildings or factories. This paper analyzes the characteristics of a distributed node-based Anchor-less UWB positioning system, measuring its actual ranging period and distance estimation error with varying node numbers and configured ranging periods. Experimental results show that even without anchors or node synchronization, the system achieves an average error of 0.32 meters.

• Journal of the Korean Institute of Landscape Architecture
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• v.44 no.5
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• pp.47-58
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• 2016

In modern era Busan, newspaper articles about cherry blossom attractions from FuzanNippo and ChosenJiho have changed from places of landmark cherry trees to recreational activities under the cherry blossom. This means that the place characteristics of the cherry blossom attractions helped transform modern Busan. This study is to clarify the real image of the cherry blossom attractions where they were and when it was established in modern Busan. In order to discuss the location characteristics and the timing of identification as it changed from cherry-blossom viewing spots to picnic spots under the cherry blossom, current articles published in the FuzanNippo and ChosenJiho were collected. This study results are as follows: First of all, cherry blossom attractions are located in private gardens, gardens at hot spring inns, public lands such as schools, temples, reservoirs and malls such as Dongnae hot spring and the Midoricho red-light district. The location feature was that they were found at the edges of settlement environments, at the interface of city and natural spaces in modern Busan. Secondly, newspaper articles about cherry blossom attractions gradually changed from cherry blossom viewing spots to picnic spots under the cherry blossom, which became the peak of the cherry blossom attractions in modern Busan. The main focus of cherry blossom attractions changed from cherry-blossom viewing to picnicking under cherry blossoms around 1920. This means that the establishment of cherry blossom attractions can be seen around 1920. Articles of cherry-blossom viewing picked up sites not easy to access such as private gardens and reservoirs, articles about picnic spots under cherry blossoms noted public places that everyone could access. Cherry blossom attractions sites became spring resorts in modern Busan.