• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10B
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• pp.630-638
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• 2005

As real-time media applications based on IP multicast networks spread widely, the end-to-end QoS (quality of service) provisioning for these applications have become very important. To guarantee the end-to-end QoS of multi-party media applications, it is essential to monitor the time-varying status of both network metrics (i.e., delay, jitter and loss) and system metrics (i.e., CPU and memory utilization). In this paper, targeting the multicast-enabled AG (Access Grid) group collaboration tool based on multi-Party real-time media services, a hybrid monitoring scheme that can monitor the status of both multicast network and node system is investigated. It combines active monitoring and passive monitoring approaches to measure multicast network. The active monitoring measures network-layer metrics (i.e., network condition) with probe packets while the passive monitoring checks application-layer metrics (i.e., user traffic condition by analyzing RTCP packets). In addition, it measures node system metrics from system API. By comparing these hybrid results, we attempt to pinpoint the causes of performance degradation and explore corresponding reactions to improve the end-to-end performance. The experimental results show that the proposed hybrid monitoring can provide useful information to coordinate the performance improvement of multi-party real-time media applications.

• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.11 no.1
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• pp.20-24
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• 2015

Steam generator(S/G) tubes in pressurized water reactor (PWR's) are subject to several types of degradation. This degradation includes denting, pitting, intergranular attack(IGA), intergranular stress corrosion cracking(IGSCC), fatigue, fretting and wear. Degradation can be derived from either the primary side(inside) or the secondary side(outside) of the tube. Recent issue for tube degradation in domestic steam generator is the tube end cracking on seal weld region. The seal weld region at the tube end and tube itself is regarded as a pressure boundary between the primary side and the secondary side. One of the Westinghouse Model-F S/G has experienced tube end cracking and its number of plugging approximately becomes to the operating limit up to 5% due to tube end cracking which was reported as SAI/MAI(single/multiple axial indication) or SCI/MCI(Single/multiple circumferential indication) from the results of eddy current testing. Eddy current mock-up test was carried out to determine the origin of cracking whether it is from weld zone area or parent tube. This result was helpful to analyze crack location on ECT data. Correct action on this problem was the installation of tube-end sleeve. Last year, after removing 340 installed plugs from tubes, selected 269 tubes took tube-end sleeve installation. Tube-end sleeve brought pressure boundary from parent tube to installed sleeve tube. Tube-end sleeve has the benefit of reducing outage period and increasing more revenue than replacing S/G. This paper is provided to assist interest parties in effectively understanding this issue.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.5
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• pp.2313-2318
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• 2012

With the widely applications of tactical radio networks, end-to-end secure speech communication in the heterogeneous network has become a very significant security issue. High-grade end-to-end speech security can be achieved using encryption algorithms at user ends. However, the use of encryption techniques results in a problem that encrypted speech data cannot be directly transmitted over heterogeneous tactical networks. That is, the decryption and re-encryption process must be fulfilled at the gateway between two different networks. In this paper, in order to solve this problem and to achieve optimal end-to-end speech security for heterogeneous tactical environments, we propose a novel mechanism for end-to-end secure speech transmission over ultra high frequency (UHF) and public switched telephone network (PSTN) and evaluate against the performance of conventional mechanism. Our proposed mechanism has advantages of no decryption and re-encryption at the gateway, no processing delay at the gateway, and good inter-operability over UHF and PSTN.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.66-71
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• 2014

This paper presents an analog front-end integrated circuit (IC) for medical ultrasound imaging systems using standard $0.18-{\mu}m$ CMOS process. The proposed front-end circuit includes the transmit part which consists of 15-V high-voltage pulser operating at 2.6 MHz, and the receive part which consists of switch and a low-power low-noise preamplifier. Depending on the operation mode, the output driver in the transmit pulser can be reconfigured as the switch in the receive path and thus the area of the overall front-end IC is reduced by over 70% in comparison to previous work. The designed single-channel front-end prototype consumes less than $0.045mm^2$ of core area and can be utilized as a key building block in highly-integrated multi-array ultrasound medical imaging systems.

• Journal of Korean Foot and Ankle Society
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• v.7 no.2
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• pp.223-231
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• 2003

Purpose: Achilles tendon rupture has become more common in the recent years. As suture with foreign material has been blamed for impaired healing, better results should be expected from the use of autogenous material such as plantaris tendon. We have evaluated the surgical results of end-to-end anastomosis using the plantaris tendon as suture material. Materials and Methods: Between Jan 1997 and Jan 2002, the 60 patients were included this study during one year follow-up. We performed the operations with end-to-end suture technique using modified Lynn's method. The plantaris tendon has been used as a autogenous suture material and can be utilized in the end-to-end anastomosis of ruptured Achilles tendon with modifed Bunnel suture technique. We used a clinical scoring system reported by Leppilahti to evaluate the results. Results: The overall results were excellent in thirty eight(63.3%), good in sixteen(26.6%), fair in five(8.3%) cases, and poor in only one (1.6%) case. Fifty four cases(90%) had the score more than good. We had no deep infection, rerupture, deep vein thrombosis, and skin necrosis as major complication. In just 2 cases, although there were superficial skin infection, the wounds did not proceed necrosis due to using antibiotics. Conclusion: End-to-end anastomosis using the plantaris tendon as suture material was good treatment option that had low infection rate and no foreign body reaction because of using autogenous material, and therefore we can get rapid healing of ruptured tendon due to early ragne of motion and accerlerated rehabilitation.

• Journal of the Korea Convergence Society
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• v.10 no.1
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• pp.13-24
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• 2019

Each company has different business processes. Since it is impossible that an ERP system contains every different business processes, the productivity of customizing and maintenance well-matched for the business process of a company is the key to successful implementation. This ERP UI development tool was developed for better connection to back-end in terms of customizing and maintenance, integration with design, providing various tools for higher productivity, reusability, and standardized user interface so that it enhances the productivity, meets the UI standard, and copes with upcoming changes of business process. In the further study, the study on the service automation and integrated development environment with front-end and back-end providing through the advanced user convenience development for front-end designer and front-end generator would be carried out.

• Journal of the Korea Convergence Society
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• v.10 no.6
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• pp.355-363
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• 2019

The purpose of this study was to investigate the correlation between ethical dilemma, end-of-life care stress and burnout of the nurses in long term care hospitals and descriptive correlations to identify factors affecting burnout. The subjects of study were 143 nurses who are working in the seven long-term-care hospitals in G-do and had more than one experience of end-of-life nursing care, understood the research items and agreed to participate in the research. In this study, it was founded that end-of-life care stress, age, job position, and end-of-life care education were found to be influential factors affecting burnout of the nurses in long-term care hospitals. As a result, age and occupation, end - of - life nursing education, and end - of - life stress were found to be factors affecting nurses' burnout. Therefore, in order to prevent and alleviate burnout of long-term care hospital nurses, a systematic intervention program that manages stress related to end-of-life nursing care is needed.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.7
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• pp.347-352
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• 2019

This study focused on improving the cast quality of small-sized induction motor rotors during the die casting process. A new rotor core cast model was proposed based on previous research results and parametric studies. Numerical analyses using 3-dimensional half models were performed to evaluate the filling patterns of aluminum molten metals into a mold and on-site experiment performed to verify the newly proposed cast model. The following were obtained from numerical filling analyses and experimental results. First, molten metals started to fill the lower end ring, then moved on to fill the core slot and upper end ring and finally stopped to fill at the rotor core slot. Second, significant circulation of molten metals was not observed on the lower end ring, resulting in fewer defects at the section of the lower end ring from the experimental results. Third, the new shape of a rotor core cast was effective in producing rotors with sound cast quality, and reducing the end ring cast defect area by approximately 70 %.

• Phonetics and Speech Sciences
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• v.12 no.4
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• pp.63-71
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• 2020

Speech recognition is one of the areas actively commercialized using deep learning and machine learning techniques. However, the majority of speech recognition systems on the market are developed on data with limited diversity of speakers and tend to perform well on typical adult speakers only. This is because most of the speech recognition models are generally learned using a speech database obtained from adult males and females. This tends to cause problems in recognizing the speech of the elderly, children and people with dialects well. To solve these problems, it may be necessary to retain big database or to collect a data for applying a speaker adaptation. However, this paper proposes that a new end-to-end speech recognition method consists of an acoustic augmented recurrent encoder and a transformer decoder with linguistic prediction. The proposed method can bring about the reliable performance of acoustic and language models in limited data conditions. The proposed method was evaluated to recognize Korean elderly and children speech with limited amount of training data and showed the better performance compared of a conventional method.

• The Journal of the Acoustical Society of Korea
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• v.28 no.4
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• pp.392-400
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• 2009

In this paper, we propose an effective speech reinforcement technique base on ITU-T G.729A CS-ACELP codec under the near-end background noise environments. In general, since the intelligibility of the far-end speech for the near-end listener is significantly reduced under near-end noise environments, we require a far-end speech reinforcement approach to avoid this phenomena. In contrast to the conventional speech reinforcement algorithm, we reinforce the excitation signal of the codec's parameters received from the far-end speech signal based on the G.729A speech codec under various background noise environments. Specifically, we first estimate the excitation signal of ambient noise at the near-end through the encoder of the G.729A speech codec, reinforcing the excitation signal of the far-end speech transmitted from the far-end. we specially propose a novel approach to directly reinforce the excitation signal of far-end speech signal based on the decoder of the G.729A. The performance of the proposed algorithm is evaluated by the CCR (Comparison Category Rating) test of the method for subjective determination of transmission quality in ITU-T P.800 under various noise environments and shows better performances compared with conventional SNR Recovery methods.