• Journal of the Korea Institute of Information and Communication Engineering
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• v.23 no.11
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• pp.1407-1413
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• 2019

In this paper, we assume that another transmitter can transmit its data signal in the same frequency band in order to maximize the frequency efficiency of non-orthogonal multiple access(NOMA) systems. We also focus on the improvement in fairness performance of receiver's data rates, not the maximization of sum data rate for NOMA systems. Thus, in this paper, we propose a power allocation scheme to enhance the fairness performance of average data rates of receivers considering the NOMA systems in the presence of interference. Assuming Rayleigh fading channels, the average data rates of receivers are defined, and the power allocation coefficients to improve the data-rate fairness are derived by using high signal-to-noise power ratio approximation. In addition, through simulations, it is shown that the proposed power allocation scheme can improve the data-rate fairness in the NOMA system with interference.

• Journal of Korean Society on Water Environment
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• v.39 no.6
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• pp.465-474
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• 2023

The chemical composition and molecular weight characteristics of dissolved organic matter (DOM) exert a profound influence on the efficiency of organic matter removal in water treatment systems, acting as efficiency predictive indicators. This research evaluated the primary chemical and molecular weight properties of DOM derived from diverse sources, including rivers, lakes, and biomasses, and assessed their relationship with the efficiency of coagulation/flocculation treatments. Dissolved organic carbon (DOC) removal efficiency through coagulation/flocculation exhibited significant correlations with DOM's hydrophobic distribution, the ratio of humic-like to protein-like fluorescence, and the molecular weight associated with humic substances (HS). These findings suggest that the DOC removal rate in coagulation/flocculation processes is enhanced by a higher presence of HS in DOM, an increased influence of externally sourced DOM, and more presence of high molecular weight compounds. The results of this study further posit that the efficacy of water treatment processes can be more accurately predicted when considering multiple DOM characteristics rather than relying on a singular trait. Based on major results from this study, a predictive model for DOC removal efficiency by coagulation/flocculation was formulated as: 24.3 - 7.83 × (fluorescence index) + 0.089 × (hydrophilic distribution) + 0.102 × (HS molecular weight). This proposed model, coupled with supplementary monitoring of influent organic matter, has the potential to enhance the design and predictive accuracy for coagulation/flocculation treatments targeting DOC removal in future applications.

• Clinical Endoscopy
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• v.57 no.1
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• pp.65-72
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• 2024

Background/Aims: Multiple white and flat elevated lesions (MWFL) that develop from the gastric corpus to the fornix may be strongly associated with oral antacid intake. Therefore, this study aimed to determine the association between the occurrence of MWFL and oral proton pump inhibitor (PPI) intake and clarify the endoscopic and clinicopathological characteristics of MWFL. Methods: The study included 163 patients. The history of oral drug intake was collected, and serum gastrin levels and anti-Helicobacter pylori immunoglobulin G antibody titers were measured. Upper gastrointestinal endoscopy was performed. The primary study endpoint was the association between MWFL and oral PPI intake. Results: In the univariate analyses, MWFL were observed in 35 (49.3%) of 71 patients who received oral PPIs and 10 (10.9%) of 92 patients who did not receive oral PPIs. The occurrence of MWFL was significantly higher among patients who received PPIs than in those who did not (p<0.001). Moreover, the occurrence of MWFL was significantly higher in patients with hypergastrinemia (p=0.005). In the multivariate analyses, oral PPI intake was the only significant independent factor associated with the presence of MWFL (p=0.001; odds ratio, 5.78; 95% confidence interval, 2.06-16.2). Conclusions: Our findings suggest that oral PPI intake is associated with the presence of MWFL (UMINCTR 000030144).

• Journal of Veterinary Clinics
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• v.24 no.2
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• pp.269-275
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• 2007

Two dogs referred to Veterinary Medical Center, Chungbuk National University diagnosed as multiple extrahepatic portosystemic shunt were reported. The first dog was a 20-month-old, 8 kg, male Cocker spaniel with history of peritoneal effusion, diarrhea, anorexia and stunted growth. The second dog was a 3-year-old, 13.4 kg, male Jindo with a history of severe depression. Hematologic examination of first dog revealed mild microcytosis and nonregenerative anemia. All of 2 cases, serum chemical values showed increase of serum ammonia, ALP, r-GTP and glucose. In survey radiography, microhepatia was apparent. In the color Doppler ultrasonographic examination, the first dog revealed a dilated tortuous vein communicating with caudal vena cava was observed near the left kidney and the second dog revealed numerous shunting vessels ventral to L5 and L6. Transcolonic portal scintigraphy of the first dog confirmed the presence of portosystemic shunt. In intraoperative jejunoportography, the first dog showed single congenital extrahepatic portosystemic shunt and multiple acquired extrahepatic portosystemic shunts. The second dog showed multiple acquired extrahepatic portosystemic shunts. In these dogs, the presence of congenital and acquried portosystemic shunts and histopathologic findings were considered to represent a combination of multiple extrahepatic portosystemic shunts and noncirrhotic portal hypertension or portal vein hypoplasia.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5C
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• pp.376-383
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• 2012

In this paper, we provide a general expression of spatial multiplexing gain (SMG) for two mutually interfering multiple-input multiple-output (MIMO) broadcast channels, referred to as MIMO-IBC, when some of user messages are made available to base stations through a common noiseless backbone line. The MIMO-IBC has two base stations and multiple users, each equipped with multiple antennas, where independent messages are transmitted over fixed channels. From the derived results, we observe the variation of the SMG with respect to the presence of a coordination as well as various antenna distributions, and compare the derived result to the SMG of the case with full cooperation among users.

• Investigative Magnetic Resonance Imaging
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• v.20 no.1
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• pp.66-70
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• 2016

Introduction: Distant metastases of mucoepidermoid carcinoma (MEC) are reported with the most common sites being the soft tissue of skin, lung, liver, and bone. We report here a very rare case of MEC with multiple metastases to the kidney, adrenal gland, skull and gluteus maximus muscle. Case report: A 63-year-old male patient presented with left-sided headache. Radiologic evaluations including CT and MRI showed ill-defined soft tissue lesion involving the left infratemporal fossa and left sphenoid sinus, and multiple enlarged lymph nodes in neck and mediastinum. PET-CT demonstrated multiple hypermetabolic lesions in and around the left kidney, left adrenal gland, right ischium, right gluteus maximus and skull base. These lesions were confirmed as MEC with multiple metastases through biopsy. Discussion: Only one case of metastasis to the skull has been previously reported, and moreover, there has not been a case of metastatic MEC to the kidney, adrenal gland and gluteus maximus muscle so far in the medical literature. It is important to acknowledge the possibility of every unusual MEC metastases, since the presence of metastasis has statistically significant influence on the survival of MEC.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.12
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• pp.5149-5173
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• 2016

Cooperative forwarding has shown a substantial network performance improvement compared to traditional routing in multi-hop wireless network. To further enhance the system throughput, especially in the presence of highly congested multiple cross traffic flows, a promising way is to incorporate the multi-radio multi-channel (MRMC) capability into cooperative forwarding. However, it requires to jointly address multiple issues. These include radio-channel assignment, routing metric computation, candidate relay set selection, candidate relay prioritization, data broadcasting over multi-radio multi-channel, and best relay selection using a coordination scheme. In this paper, we propose a simple and efficient cluster-based cooperative data forwarding (CCDF) which jointly addresses all these issues. We study the performance impact when the same candidate relay set is being used for multiple cross traffic flows in the network. The network simulation shows that the CCDF with MRMC not only retains the advantage of receiver diversity in cooperative forwarding but also minimizes the interference, which therefore further enhances the system throughput for the network with multiple cross traffic flows.

• Journal of Communications and Networks
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• v.18 no.4
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• pp.639-648
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• 2016

Next-generation (4G) systems are designed to support universal frequency reuse (UFR) to achieve best use of valuable spectra. However, it leads to undesirable interference level near cell borders. To control this, 4G systems adopt techniques, such as network multiple-input multiple-output (MIMO) and inter-cell interference coordination (ICIC), to improve cell-edge throughput. Network MIMO aims at mitigating inter-cell interference towards cell-edge users (CEUs) through multi-cell cooperation, where each collaborative base station serves both cell-center users (CCUs) and CEUs, including other cells' CEUs, under a power constraint. The present ICIC strategies cannot be directly applied to network MIMO because they were designed in absence of multi-cell coordination. In the presence of network MIMO, this paper investigates antenna orientations in ICIC and the method of power management. Results show that a proper antenna orientation can improve the cell-edge capacity and meantime lower the interference to CCUs. Capacity inconsistency between CCUs and CEUs is detrimental to mobile communications. Simulation results show that the proposed power management for ICIC in network MIMO systems can achieve a uniform data rate regardless users' position.

• Journal of Information Processing Systems
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• v.13 no.4
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• pp.677-688
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• 2017

In order to solve the undetected probability of multiple targets in ultra-wideband (UWB) through-the-wall radar imaging (TWRI), a time-delay and amplitude modified back projection (BP) algorithm is proposed. The refraction point is found by Fermat's principle in the presence of a wall, and the time-delay is correctly compensated. On this basis, transmission loss of the electromagnetic wave, the absorption loss of the refraction wave, and the diffusion loss of the spherical wave are analyzed in detail. Amplitude compensation is deduced and tested on a model with a single-layer wall. The simulating results by finite difference time domain (FDTD) show that it is effective in increasing the scattering intensity of the targets behind the wall. Compensation for the diffusion loss in the spherical wave also plays a main role. Additionally, the two-layer wall model is simulated. Then, the calculating time and the imaging quality are compared between a single-layer wall model and a two-layer wall model. The results illustrate the performance of the time-delay and amplitude-modified BP algorithm with multiple targets and multiple-layer walls of UWB TWRI.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.886-889
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• 2014

In this paper, we evaluate a physical layer security performance of orthogonal space-time block code(OSTBC) using one-bit feedback in the presence of an eavesdropper in wiretap channels, where we assume spatially correlated MIMO(multiple-input multiple-output) channels. In this paper, we present the one-bit feedback based OSTBC(F-OSTBC) scheme and compare security outage performances of F-OSTBC, conventional OSTBC, and transmission antenna selection schemes for various spatial correlation conditions at each node.