• ETRI Journal
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• v.39 no.6
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• pp.794-802
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• 2017

In this paper, a wireless powered communication network (WPCN) consisting of a hybrid access point (H-AP) and multiple user equipment (UE), all of which operate in full-duplex (FD), is described. We first propose a transceiver structure that enables FD operation of each UE to simultaneously receive energy in the downlink (DL) and transmit information in the uplink (UL). We then provide an energy usage model in the proposed UE transceiver that accounts for the energy leakage from the transmit chain to the receive chain. It is shown that the throughput of an FD WPCN using the proposed FD UE (FD-WPCN-FD) can be maximized by optimal allocation of the UL transmission time to the UE by solving a convex optimization problem. Simulation results reveal that the use of the proposed FD UE efficiently improves the throughput of a WPCN with a practical self-interference cancellation capability at the H-AP. Compared to the WPCN with FD H-AP and half-duplex (HD) UE, FD-WPCN-FD achieved an 18% throughput gain. In addition, the throughput of FD-WPCN-FD was shown to be 25% greater than that of WPCN in which an H-AP and UE operated in HD.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.14 no.3
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• pp.227-234
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• 1989

In this paper, a new receiver for a frequency-hopped multilevel FSK system for mobile Communications is presented. This new receiver provides an implementation advantage by eliminating unecessary energy detection of all the frequency channels. A performace analysis of the proposed system is carried out by using the union bound. We show that an optimim number of message bits that minimize the word error probability exists for a given number of simultaneous users. This scheme is a generalization of the MFSK system that allows the message bits to be uaried, making it possible for designers to increase the flexibility of implementation. Error probabilities are calculated in the case of fixed bandwidth and fixed tone repetition number. The effect of using error-correcting coding is considered.

• Genomics & Informatics
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• v.11 no.4
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• pp.289-291
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• 2013

Human papillomavirus (HPV) infection is the leading cause of cancer mortality among women worldwide. The molecular understanding of HPV proteins has significant connotation for understanding their intrusion in the host and designing novel protein vaccines and anti-viral agents, etc. Genomic, proteomic, structural, and disease-related information on HPV is available on the web; yet, with trivial annotations and more so, it is not well customized for data analysis, host-pathogen interaction, strain-disease association, drug designing, and sequence analysis, etc. We attempted to design an online reserve with comprehensive information on HPV for the end users desiring the same. The Human Papillomavirus Proteome Database (hpvPDB) domiciles proteomic and genomic information on 150 HPV strains sequenced to date. Simultaneous easy expandability and retrieval of the strain-specific data, with a provision for sequence analysis and exploration potential of predicted structures, and easy access for curation and annotation through a range of search options at one platform are a few of its important features. Affluent information in this reserve could be of help for researchers involved in structural virology, cancer research, drug discovery, and vaccine design.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.207.1-207.1
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• 2013

Tantalum oxide has been extensively investigated as one of the promising Resistive switching materials applicable to Resistive Dynamic Access Memories. Impedance spectroscopy offers simultaneous measurements of electrical and dielectric information, separation of electrical origins among bulk, grain boundaries, and interfaces, and the monitoring of electrical components. Such benefits have been combined with the resistive states of resistive switching devices which can be described in terms of equivalent circuits involving resistors, capacitors, and inductors, The current work employed pulsed laser deposition in order to prepare the oxygen-deficient tantalum oxide. The fabricated devices were controlled between highresistance and low-resistance states in controlled current compliance modes. The corresponding electrical phenomena were monitored both in the dc-based current-voltage characteristics and in the ac-based impedance spectroscopy. The origins of the electrical switching are discussed towards optimized ReRAM devices in terms of interfacial effects.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.34 no.4
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• pp.113-122
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• 2018

Residentialization is in progress in the coastal areas of the cities as the number of apartment houses rapidly increase with the simultaneous provision-centered development. It would be necessary to provide quality residential environments which would not deteriorate and would be chosen by many people as a sustainable residence in the future through the demand-centered development, considering the residents' consciousness. To do so, it is necessary to understand the residents' consciousness about the residential environment in the coastal area that has differentiated characteristics as a waterfront space through an evaluation of the residential environment, different from the existing residences. This study understands the significance of the waterfront space in the residential environment through people's consciousness when they choose a residence before they reside and people's consciousness when they evaluate the residence after they reside, concerning how the environment of the waterfront space is recognized as compared to other elements of the residential environment according to the geographic characteristics of the coastal area. In addition, this study analyzes the significance of people's consciousness before and after their residence through a comparison according to the change of distance to the waterfront from the perspective of access to the waterfront, the characteristic as a residential environment in the coastal area.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.18 no.2
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• pp.511-527
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• 2024

This paper proposes a block-based self-organizing time-division multiple access (BSO-TDMA) protocol for very high frequency (VHF) data exchange system (VDES) in shipborne ad-hoc networks (SANETs). The BSO-TDMA reduces the collisions caused by the simultaneous transmission of automatic identification system (AIS) messages by uniformly allocating channel resources using a block-wise frame. For this purpose, the BSO-TDMA includes two functional operations: (1) frame configuration and (2) slot allocation. The first operation consists of block division and block selection. A frame is divided into multiple blocks, each consisting of fixed-size subblocks, by using the reporting interval (RI) of the ship. Then, the ship selects one of the subblocks within a block by considering the number of occupied slots for each subblock. The second operation allocates the slots within the selected subblock for transmitting AIS messages. First, one of the unoccupied slots within the selected subblock is allocated for the periodic transmission of position reports. Next, to transmit various types of AIS messages, an unoccupied slot is randomly selected from candidate slots located around the previously allocated slot. Experimental simulations are conducted to evaluate the performance of BSO-TDMA. The results show that BSO-TDMA has better performance than that of the existing SOTDMA.

• Journal of the Korean Society of Radiology
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• v.85 no.3
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• pp.596-606
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• 2024

Purpose To examine the technical considerations of endovascular treatment for aortoiliac occlusive disease (AIOD) based on a 10-year experience in Songklanagarind Hospital. Materials and Methods This retrospective cohort study included 210 patients who underwent endovascular treatment for symptomatic AIOD between January 2010 and December 2020. The patients' clinical and lesion characteristics, including technical considerations of the procedure, were collected, analyzed, and stratified using the Transatlantic Inter-Society Consensus (TASC). Results Most patients (80%) in this study had chronic limb-threatening ischemia lesions, with an occlusion rate of 37%. The technical success rate of TASC C & D was lower than that of TASC A & B, 84.4% vs. 99.2% p ≤ 0.001. A technical success rate of 93.3% (14/15) was found for the femoral and brachial approach, compared with a success rate of 89.0% (57/64) for the unibifemoral approach in TASC C & D, without a statistically significant difference (p = 0.076). However, the puncture site complications in this route were up to 17.6%, which is the highest rate compared with other techniques. These complications could be treated either conservatively or minimally invasively. Conclusion In cases of failed femoral access, simultaneous femoral and brachial approaches improved the technical success rate of endovascular recanalization of TASC C & D aortoiliac occlusions.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.7
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• pp.760-764
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• 2015

Wireless sensors, installed on machinery, and Time Division Multiple Access (TDMA) transmission make an ideal system for monitoring machine conditions in industrial plants because there is no need for electronic wiring. However, there has not yet been a successful field application of such a system, capable of continuously transmitting data at sample rates greater than 100 Hz. In this research, a TDMA network protocol capable of acquiring data from multiple sensors at sample rates greater than 100 Hz was developed for field application. The protocol was implemented in a single cluster-star topology network, and the system was evaluated based on the node number and transmission distance. Network simulator 2 (ns-2) was used for a real field simulation. Non-TDMA and TDMA protocol cases were compared using four sensor nodes. In the cases of 20-s and 40-s transmission times, there was little difference between the reception rates of the non-TDMA and TDMA systems. However, the difference was much greater when using a 60-s transmission time.

• Journal of the Korean Society of Radiology
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• v.84 no.3
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• pp.705-712
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• 2023

Common femoral artery pseudoaneurysm is a potentially serious complication of peripheral angiography. There have been few prior reports of simultaneous pseudoaneurysm in both common femoral arteries after percutaneous access. Here we report the case of a 58-year-old male patient who presented with phlegmon or abscess a few days after bilateral femoral access, after which newly developed bilateral femoral pseudoaneurysm with wide neck was observed on CT angiography 2 months after infection treatment. Because the patient refused surgery for pseudoaneurysm, a stent-graft was inserted in the left side, and percutaneous thrombin injection under US guidance with balloon occlusion was performed for the right side. Most pseudoaneurysms occur immediately after the causative procedure. However, there have been some cases in which pseudoaneurysms may occur several weeks or months later; it is therefore necessary to check the risk factors and to carefully observe the hemostasis site.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.2
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• pp.32-43
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• 2014

To identify major causes of the global environment changes arising from extreme and unusual weather patterns occurring these days, and to foresee future environmental changes, it is highly important to shed light on the correlation between climate changes and global environment system. To investigate the correlation between climate changes and global environment system, it calls for establishing an integrated climate-environment DB for analyzing comparatively the data on climatic changes and global environment system. In the preceding studies, we researched an XML-based integrated climate-environment DB and developed a management system for the DB. However, the existing integrated climate-environment DB, designed and installed only for individual PCs, does not allow multiple users 'simultaneous access. Accordingly, it fails to systematically update and sharing data which is being generated continuingly. Hence, this study aims to develop an easy-to-use GIS-based integrated DB management system by improving the existing integrated climate-environment DB through the adoption of the client/server model. For this, this study collected and analyzed climate and environment data prior to designing and building a DBMS-based integrated DB. In addition, in order for multidisciplinary researchers to easily get access and apply the integrated DB, this study designed and developed a GIS-based integrated DB management system using a client/server model which facilitates connections with multiple PCs. The GIS-based integrated climate-environment DB management system makes it easier to efficiently manage and locate scattered climate-environment data. It is also expected that the DB system will bring the effects in saving time and cost by avoiding the overlapping generation of data in the areas of integrated climate-environment research.