• Journal of Electrical Engineering and Technology
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• v.7 no.5
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• pp.797-806
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• 2012

Fault detection and isolation (FDI) algorithms provide fault monitoring methods in GPS measurement to isolate abnormal signals from the GPS satellites or the acquired signal in receiver. In order to monitor the occurred faults, FDI generates test statistics and decides the case that is beyond a designed threshold as a fault. For such problem of fault detection and isolation, this paper presents and evaluates position domain integrity monitoring methods by formulating various pseudorange prediction methods and investigating the resulting test statistics. In particular, precise measurements like carrier phase and Doppler rate are employed under the assumption of fault free carrier signal. The presented position domain algorithm contains the following process; first a common pseudorange prediction formula is defined with the proposed variations in pseudorange differential update. Next, a threshold computation is proposed with the test statistics distribution considering the elevation angle. Then, by examining the test statistics, fault detection and isolation is done for each satellite channel. To verify the performance, simulations using the presented fault detection methods are done for an ideal and real fault case, respectively.

• Journal of Korean Institute of Industrial Engineers
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• v.28 no.2
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• pp.139-146
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• 2002

The third generation mobile communication needs to provide multimedia service with increased data rates. Thus an efficient allocation of radio and network resources is very important. This paper models the 'burst switching' as an efficient radio resource allocation scheme and the performance is compared to the circuit and packet switching. In burst switching, radio resource is allocated to a call for the duration of data bursts rather than an entire session or a single packet as in the case of circuit and packet switching. After a stream of data burst, if a packet does not arrive during timer2 value ($\tau_{2}$), the channel of physical layer is released and the call stays in suspended state. Again if a packet does not arrive for timerl value ($\tau_{1}$) in the suspended state, the upper layer is also released. Thus the two timer values to minimize the sum of access delay and queuing delay need to be determined. In this paper, we focus on the decision of $\tau_{2}$ which minimizes the access and queueing delay with the assumption that traffic arrivals follow Poison process. The simulation, however, is performed with Pareto distribution which well describes the bursty traffic. The computational results show that the delay and the packet loss probability by the burst switching is dramatically reduced compared to the packet switching.

• Journal of computational fluids engineering
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• v.17 no.2
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• pp.53-57
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• 2012

Design of the cooling channels of a plastic injection mold affects the quality and the productivity of the injection processes. In the injection process, the melted resin with high temperature enters the mold cavity, and just after the cavity is filled the heat should be dissipated through the cooling channels simultaneously. The purpose of this study is to analyse the heat transfer phenomenon and to estimate the temperature distribution in the mold to evaluate the cooling effect of the channels. The injection mold is assumed to have cooling channels of circular cross section and each channel has the same coolant flow rate. and The cavity has a rectangular shape. The results show that as the cooling channels get closer to the cavity surface, the cooling efficiency increases as might easily be guessed. However, due to the final hot resin flow from the gate an intensive cooling is required in that region.

• Journal of Broadcast Engineering
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• v.6 no.1
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• pp.13-20
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• 2001

In this paper, we propose a new digital audio watermarking scheme In the cepstrum domain. We insert a digital watermark signal Into the cepstral components of the audio signal using a technique analogous to spread spectrum Communications, hiding a narrow band signal in a wade band channel. In our proposed method, we use pseudo-random sequences to watermark the audio signal. The watermark Is then weighted in the cepstrum domain according to the distribution of cepstral coefficients and the frequency masking characteristics of the human auditory system. The proposed watermark embedding scheme minimizes audibility of the watermark signal. and the embedded watermark is robust to mu1tip1e watermarks, MPEG audio ceding and additive noose.

• Journal of Korean Library and Information Science Society
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• v.36 no.1
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• pp.173-193
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• 2005

The modern society is one of knowledge and information, and the library is one of the important routes through which they are obtained. But the collection in the library, from the onset of its creation and the process of accumulation, could only be bent and biased due to the prejudice and distortion, inevitably acting as an agent that mires the essence of the library as a distribution channel for knowledge and information of modern society. This study is the discussion about the necessity, main assignment and the methodology of library collection study. The collection study needs to focus on the process of accumulating the collection in the library to track down the Process of becoming biased.

• Journal of Korean Neurosurgical Society
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• v.41 no.1
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• pp.30-38
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• 2007

Objective : To elucidate the role of aquaporin-4[AQP4] in cerebral edema formation, we studied the expression and subcellular localization of AQP4 in astrocytes after focal cerebral ischemia. Methods : Cerebral ischemia were induced by permanent middle cerebral artery[MCA] occlusion in rats and estimated by the discoloration after triphenyltetrazolium chloride[TTC] immersion. Change of AQP4 expression were evaluated using western blot. Localization of AQP4 was assessed by confocal microscopy and its interaction with ${\alpha}-syntrophin$ was analyzed by immunoprecipitation. Results : After right MCA occlusion, the size of infarct and number of apoptotic cells increased with time. The ratio of GluR1/GluR2 expression also increased during ischemia. The polarized localization of AQP4 in the endfeet of astrocytes contacting with ventricles, vessels and pia mater was changed into the diffuse distribution in cytoplasm. The interactions of AQP4 and Kir with ${\alpha}-syntrophin$, an adaptor of dystrophin complex, were disrupted by cerebral ischemia. Conclusion : The deranged spatial buffering function of astrocytes due to mislocalized AQP4/Kir4.1 channel as well as increased assembly of $Ca^{2+}$ permeable AMPA receptors might contribute to the development of edema formation and the excitotoxic neuronal cell death during ischemia.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.12
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• pp.5709-5715
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• 2012

Injection molding product is commonly used for reducing the weight of automotive vehicle, and door regulator guide rail with plastic material is also made by injection molding process. In order to improve the injection molding performance of plastic regulator guide rail, optimal molding condition is suggested by numerical simulation and DOE after obtaining the sensitivity of parameters for regulator rail manufacturing on warpage and fill time. Furthermore, multi direct gate method and optimal cooling circuit are introduced to get the uniform temperature distribution and better cooling efficiency in molding product. The effect of the proposed design on the injection molding performance is verified by the test of prototype of plastic regulator guide rail.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.4
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• pp.91-98
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• 2019

Dividend policy is an important business decision and is considered a channel to communicate a firm's performance to shareholders. Given the empirical findings that earnings quality significantly affects financial analysts' forecasting activities, it is predicted that higher earnings quality would positively influence forecast accuracy. Specifically, it is expected that financial analysts would forecast dividends more accurately for firms with higher earning quality. Unlike the research on financial analysts' earnings forecasts was heavily conducted, there is little study about financial analysts' dividend forecasts. This paper examines the effect of earnings quality on financial analysts' dividend forecast accuracy. We use a sample of South Korean firms for the period of 2011-2015 for multivariate regression. Earnings quality is measured by accruals quality and performance-adjusted discretionary accruals followed by prior studies. We first compare the accuracy between dividend forecasts and earnings forecasts using t-test and Wilcoxon singed-rank test. It is confirmed that financial analysts' dividend forecasts are more accurate than earnings forecasts in Korea. We find that financial analysts' dividend forecasts are more accurate for firms with higher earnings quality. We also find that the result is still valid after controlling for the accuracy of financial analysts' earnings forecasts. This confirms that earnings quality positively affects financial analysts' dividend forecasts.

• Asian Journal of Business Environment
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• v.10 no.2
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• pp.33-41
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• 2020

Purpose: This study assesses the marketing practices and value-added fish products under the Coral Reef Rehabilitation and Management Program (COREMAP) in East Indonesia. Research design, data and methodology: This study gathered qualitative and quantitative data through i) focus group discussions (FGD) with fishers, traders and COREMAP officers, ii) surveys and iii) interviews with fishermen and traders. This study surveyed 714 households (365 in COREMAP and 349 in non-COREMAP) and 33 traders (17 in COREMAP and 16 in non-COREMAP) using structured questionnaires between January and March 2016. This study used Shepherd's Index to estimate the marketing efficiency for each stage of the marketing channel. For value-added fish products, the value is determined by the difference between processed output and the raw product used. Results: Marketing cost in the non-COREMAP area was more efficient than in COREMAP as indicated by lower operational cost and higher selling price. However, no value-added fish products were produced in the non-COREMAP area. This study noted a lower catch in COREMAP area, which implies COREMAP program successfully reduced fishing pressure. Conclusions: This study identified poor infrastructure and the limited market as the major problems in developing value-added fish products in both COREMAP and non-COREMAP area.

• Journal of Communications and Networks
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• v.1 no.2
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• pp.111-117
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• 1999

Using a method recently reported in the literature for analyzing the bit error probability (BEP) performance of noncoherent Mary orthogonal signals with square-law combining in the presence of independent and identically distributed Nakagami-m faded paths, we are able to reformulate this method so as to apply to a generalized fading channel in which the fading in each path need not be identically distributed nor even distributed ac-cording to the same family of distribution. The method leads to exact expressions for the BEP in the form of a finite-range integral whose integrand involves the moment generating function of the combined signal-to-noise ratio and which can therefore be readily evaluated numerically. The mathematical formalism is illustrated by applying the method to some selected numerical examples of interest showing the impact of the multipath intensity profile (MIP) as well as the fading correlation profile (FCP) on the BEP performance of M-ary orthogonal signal over Nakagami-m fading channels. Thses numerical results show that both MIP and FCP induce a non-negligible degradition in the BEP and have therefore to be taken into account for the accurate prediction of the performance of such systems.