• Journal of the Korea Convergence Society
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• v.8 no.1
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• pp.89-96
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• 2017

This study is to analyze seven fluoride varnishes remineralizing effects on early carious lesions in the clinical field. While CS, MI, CW, VV, EP, FP and FN were used for permanent teeth, CS, MI, CW and FP were used for primary teeth. The specimens were demineralized for 4 days after forming a $3{\times}3mm^2$ window with nail varnish, applied with varnishes separately, then were stirred in artificial saliva for 1 week. QLF-D analysis of carious lesion size showed that permanent teeth's ${\Delta}F$ value decreased after applying CS(4,64), MI(4.86), CW(4.50), and EP(5.50), while for primary teeth, FP(3.00) and MI(3.00) displayed a remineralizing effect. Thus, MI can be used effectively for preventing caries for both adults and children in the clinical field.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.4
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• pp.741-746
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• 2012

Transmission control protocol(TCP) widely used as a transport protocol in the Internet includes a loss recovery function that detects and recovers packet losses by retransmissions. The loss recovery function consists of the two algorithms; fast retransmit and fast recovery. There have been researches to avoid nonnecessary retransmission timeouts (RTOs), which leads to selective acknowledgement (SACK) option and limited transmit scheme that are standardized by IETF (Internet Engineering Task Force). Recently, a method that covers the case in which a retransmitted packet is lost again has been propsed. The method, however, is not proved in terms of the additive increase multiplicative decrease (AIMD) principle of TCP congestion control. In this paper, therefore, we analyzed the method in terms of the principle by ns-simulations.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.785-790
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• 2009

Widgets are the instrument for representing user's character and embossing the value of blogs. The compound word of the Windows and Gadget the application, widgets are the functional program to displayed on the screen graphical user interface (GUI) tools as a kind of service that user want to see. On the operating system, the Web, and mobile area, widgets offer the delivery of information, convenience and efficiency. However widgets have been never gave satisfaction to user because it focused transmitting information and representing circumstance than fun. This study is for recognized fun elements that user feel interest and categorized fun elements each type of widgets. Fun elements of widget never been defined, we use fun elements on design and product area and emotional word that is representative of affectivity. And we make up an online questionnaire to blog users. The widget selected by popular degree among the domestic widgets and the Japanese widget. And the results of the questionnaire that 5-scales used based on user preferences to identify the elements that are fun.

• The Journal of the Korea institute of electronic communication sciences
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• v.2 no.1
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• pp.10-18
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• 2007

In this paper, we extend the multiple time scale control framework to window-based congestion control, in particular, TCP. This is performed by interfacing TCP with a large time scale control module which adjusts the aggressiveness of bandwidth consumption behavior exhibited by TCP as a function of "large time scale" network state. i.e., conformation that exceeds the horizon of the feedback loop as determined by RTT. Performance evaluation of multiple time scale TCP is facilitated by a simulation bench-mark environment which is based on physical modeling of self-similar traffic. If source traffic is not extended exceeding, when RTT is 450ms, in self similar burst environment, performance gain of TCP-SSC is up to 45% for ${\alpha}$=1.05. However, its is acquired only 20% performance gain for ${\alpha}$=1.95 relatively. Therefore we showed that by TCP-MTS at large time scale into a rate-based feedback congestion control, we are able to improve two times performance significantly.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3C
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• pp.83-91
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• 2005

We analyze the performance of an adaptive hybrid search code acquisition algorithm for direct-sequence code division multiple access (DS-CDMA) systems under slowly-moving mobile environments. The code acquisition algorithm is designed to provide the desired feature of constant false alarm rate (CFAR) to cope with nonstationarity of the interference in CDMA forward links. An analytical expression for the mean acquisition time is first derived and the probabilities of detection, miss, and false alarm are then obtained for frequency-selective Rayleigh fading environments. The fading envelope of a received signal is assumed to be constant over the duration of post-detection integration (PDI), considering slow fading environments. Finally, the performance of the designed code acquisition algorithm shall be evaluated numerically to examine the effect of some design parameters such as the sub-window size, size of the PDI, decision threshold, and so on, considering cdma2000 environments.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.06a
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• pp.360-363
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• 2007

In sensor network, the importance of transporting data with reliability is growing gradually to support communications. Data flow from sink to nodes needs reliability for the control or management, that is very sensitive and intolerable, however relatively, data flow from nodes to sink is tolerable. In this paper, with emphasis of the data flow from sink to nodes, we proposed the mechanism that establishes confidence interval for transport. Establishing confidence interval hop-by-hop, not end to end, if errors happen or there's missing data, this mechanism recovers them with selective acknowledgement using fixed window. In addition, this mechanism supports traffic congestion control depending on the buffer condition. Through the simulation, we showed that this mechanism has an excellent performance for error recovery in sensor network.

• The KIPS Transactions:PartB
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• v.12B no.1 s.97
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• pp.39-46
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• 2005

In immersive virtual reality system, since virtual worlds do not supply users with sufficient spatial information af real world does, the users frequently experience clumsiness and roughness while manipulating virtual objects. To overcome this problem, we propose Visual Guider in this paper as a tool for enhancing user's visual space perception in immersive virtual worlds. The Visual Guider aids users to recognize exocentric distances between different scene points and egocentric distances from the observation point to other points in the scene fast and precisely. Its concept is imported from the rectangular grids frequently used in two-dimensional windows applications. We applied the proposed technique to an experimental virtual space implemented in $CAVE^(TM)-like$ system and tested its effectiveness while users grasp and move virtual objects.

• Tunnel and Underground Space
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• v.13 no.6
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• pp.455-464
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• 2003

Four assessment systems for planning and evaluation of TBM tunnelling are discussed, and their characteristics and input data are analyzed. Two of the systems are determined to be adequate for post-evaluation of TBM performance because the time, such as repair time, downtime, installation time and transport time, must be included for calculations. The others are adequate for pre-planning because the basic data of the systems consist of only the basic properties of rocks and rock masses, and the specification of TBM. In order to apply these assessment systems, a number of equations, graphs and charts are generally required, which seems to be very inconvenient and complicated. In this study, therefore, a user-friendly program operated on Windows system is developed, and each system can be selected by the corresponding input data. It will be possible fer tunnel engineers to select a system according to their objectives and available input data, and to apply the system to TBM tunnel project.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.1
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• pp.86-96
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• 2013

Unified Speech and Audio Coding (USAC) is the speech/audio codec with the best quality, approved on Final Draft International Standard (FDIS) at MPEG meeting in 2011. Since MPEG conventionally standardizes only the decoder, it is not easy to study on the encoder technologies. Furthermore, Reference Model(RM) shows extremely poor performance. To solve these problems, the open source project(JAME) proposes the methods to make the improved performance of main encoder technologies in USAC. Especially, this paper introduces the encoder modules: the signal classifier for selective operation between two coders, the psychoacoustic model in frequency domain, and window transition technology. Finally, the results of verification test for FDIS and the performance of Common Encoder are appended.

• Journal of Broadcast Engineering
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• v.16 no.5
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• pp.693-704
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• 2011

As mobile devices become multi-functional, and converge into a single platform, there is a strong need for a codec that is able to provide consistent quality for speech and music contents. MPEG-D USAC standardization activities started at the 82nd MPEG meeting with a CfP and approved Study on DIS at the 96th MPEG meeting. MPEG-D USAC is converged technology of AMR-WB+ and HE-AAC V2. Specifically, USAC utilizes three core codecs (AAC, ACELP, and TCX) for low frequency regions, SBR for high frequency regions, the MPEG Surround for stereo information, and window transition technology for smoothing transition between various core coder. USAC can provide consistent sound quality for both speech and music contents and can be applied to various applications such as multi-media download to mobile devices, digital radio, mobile TV and audio books.