• KSII Transactions on Internet and Information Systems (TIIS)
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• 제16권9호
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• pp.3043-3067
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• 2022

With the mobile traffic in the network increases exponentially, multi-access edge computing (MEC) develops rapidly. MEC servers are deployed geo-distribution, which serve many mobile terminals locally to improve users' QoE (Quality of Experience). When the cache space of a MEC server is full, how to replace the cached videos is an important problem. The problem is also called the cache replacement problem, which becomes more complex due to the dynamic video popularity and the varied video sizes. Therefore, we proposed a new cache replacement scheme based on local video popularity and video size to solve the cache replacement problem of MEC servers. First, we built a local video popularity model, which is composed of a popularity rise model and a popularity attenuation model. Furthermore, the popularity attenuation model incorporates a frequency-dependent attenuation model and a frequency-independent attenuation model. Second, we formulated a utility based on local video popularity and video size. Moreover, the weights of local video popularity and video size were quantitatively analyzed by using the information entropy. Finally, we conducted extensive simulation experiments based on the proposed scheme and some compared schemes. The simulation results showed that our proposed scheme performs better than the compared schemes in terms of hit rate, average delay, and server load under different network configurations.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권1호
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• pp.178-203
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• 2018

In this paper, authors have been evaluated the Frame Error Rate (FER) performance of IEEE 802.11 a/g/p standard 5 GHz frequency band WLAN over Rayleigh and Rician distributed fading channels in presence of Additive White Gaussian Noise (AWGN). Orthogonal Frequency Division Multiplexing (OFDM) based transceiver is implemented by using real-time signal processing frameworks (IEEE 802.11 Blocks) in GNU Radio Companion (GRC) and Ettus USRP N200 is used to process the symbol over the wireless radio channel. The FER is calculated for each sub-carrier conventional modulation schemes used by OFDM such as BPSK, QPSK, 16, 64-QAM with different punctuated coding rates. More precise SNR is computed by modifying the SNR calculation process of YANS and NIST error rate model to estimate more accurate FER. Here, real-time signal constellations, OFDM signal spectrums etc. are also observed to find the effect of multipath propagation of signals through flat and frequency selective fading channels. To reduce the error rate due to the multipath fading effect and Doppler shifting, channel estimation (CE) and equalization techniques such as Least Square (LS) and training based adaptive Least Mean Square (LMS) algorithm are applied in the receiver. The simulation work is practically verified at GRC by turning into a pair of Software Define Radio (SDR) as a simultaneous transceiver.

• Asian Pacific Journal of Cancer Prevention
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• 제14권2호
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• pp.1107-1110
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• 2013

Intrahepatic cholangiocarcinoma (ICC), one of the primary liver cancers, is frequent in the northeastern part of Thailand. Surgical resection remains the best method of treatment, but patients suffering from ICC usually present at a late stage of the disease. Studies of survival and prognostic factors after surgery remain rare. The aim here was to evaluate the survival rate and factors affecting the survival of patients with intrahepatic cholangiocarcinoma after surgery. The study used a retrospective cohort design. The subjects were 73 consecutive patients with ICC, who were admitted for surgery to Srinagarind Hospital, Khon Kaen University, during the period 2005-2009. The censoring date was 31 December, 2011, data being evaluated using uni- and multivariate analyses. Postoperative survival analysis was performed by the Kaplan-Meier method, and the Cox proportional hazard model was used to identify independent prognostic factors. The total follow-up time was 99 person-years. The total number of deaths was 59, giving a mortality rate of 59 per 100 person-years. The cumulative 1-, 3-, and 5-year survival rates were 52.1%, 21.7%, and 11.2%, respectively. The median duration of survival after resection was 12.4 months. Univariate analysis revealed stage of disease, lymph node metastasis, histological type, histological grade and macroscopic classification to be statistically significant (p-value<0.05) prognostic factors. In the multivariate analysis, only macroscopic classification was statistically significant (p-value<0.05). In conclusion, macroscopic classification was the only independent factor found to be significantly associated with survival following surgical treatment of ICC.

• 한국실내디자인학회논문집
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• 제22권3호
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• pp.154-163
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• 2013

Current principles of designating a smoking area within a non-smoking area rely on mere compartmentalization. This causes non-smokers aversion against smokers and smokers complaints about anti-smoking policies, which means both of them are not satisfied with the current scheme. In addition, such a system, far from the original intent of the law, does not provide appropriate respect for people's rights. The biggest problem of the current scheme is that smoking areas are not separated from non-smoking areas. Japan has continued installing independent smoking areas since 2002 and witnessed a decrease in the smoking rate. The country's success is attributable to: the state's active intervention in connection with enterprises; continuous environmental improvements and creation of goods; 'smoking etiquette' campaigns; and the sociality and group consciousness of Japanese people. It is recognized that the synergy of the designation of independent smoking areas and such multi-faceted efforts has led to the nation's accomplishment. Hence, it is required to install independent smoking areas in non-smoking areas in Seoul in order to respect the rights of smokers and non-smokers and resolve conflicts between them. It is not suitable to merely model after Japan's case, however, studies and guidelines that are tailored to Korea's own environment and social atmosphere are required. To ensure that the people recognize the necessity for smoking areas, a social consensus is formed and proper smoking areas are established in a systemic manner, a system for that purpose should connote a symbol of the social consensus and consequent guidelines should take physical elements, human activities and semantic assignment into consideration. This study aims to present basic guidelines to install separated smoking areas, which will keep distance between smokers and non-smokers, form a social consensus and establish a sound smoking culture. These would ensure that the rights of both smokers and non-smokers are fully respected and that government policies are trusted by the people.

• 전기학회논문지
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• 제66권7호
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• pp.1032-1038
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• 2017

Recently, regulation on carbon emissions has been strengthened according to the new climate change convention (COP21) held in Paris, and then Korea has decided to reduce CO2 emissions by 37% until 2030. As one of countermeasures, the government has energetically performed demonstration projects of island micro-grid including solar power, wind power and energy storage system. However, in order to smoothly introduce island micro-grid, it is a critical issue to carry out the economic evaluation for power utility aspect and independent power producer aspect. Therefore, this paper proposes economic evaluation algorithms of island micro-grid which are based on the present worth method, considering cost and benefit factors in the aspect of both sides. Firstly, in case of power utility this paper proposes algorithm to estimate a period of return on investment according to the introduction capacity of distributed generators replacing diesel generator. And also, in case of independent power producer, this paper proposes evaluation algorithm to estimate weighting factor of SMP and benefit rate based on break-even point related with cost and benefit. From a case study result on real island micro-grid model, it is confirmed that proposed algorithms are useful and practical for the economic evaluation of island micro-grid.

• 전자공학회논문지T
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• 제36T권4호
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• pp.17-23
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• 1999

본 연구는 문맥 독립형 화자 인식 알고리즘을 이용하여 보안시스템을 소프트웨어와 하드웨어로 구성한 논문이다. 화자인식을 이용한 보안시스템은 윈도우상에서 사운드카드를 이용하여 음성을 입력받고, 성도 모델링을 이용한 음성 파라미터를 추출하였으며, k-means 클러스터링 알고리즘을 기반으로 하여 화자를 모델링하였다. 등록된 화자에 대한 인식된 결과는 PIC16F84 마이크로 프로세서를 이용하여 자물쇠를 개${\cdot}$폐하도록 구성하였다. OFF-LINE의 실험은 TIMIT데이터를 이용하였으며, 5명의 화자에 대하여 ON-LINE으로 인식한 결과 학습시킨 데이터에 대해서는 100%의 인식률을 얻었으며 학습을 시키지 않은 데이터에 대해서는 99%의 인식률을 얻었다. 그리고 사용자 거부율 1%, 사칭자 허용률 0%, 검증평균오류는 0.5%를 보였다.

• 유통과학연구
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• 제18권11호
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• pp.31-39
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• 2020

Purpose: This study attempts to explain why online luxury shopping malls have implemented a difficult registration process and membership fees. These features weaken online shopping convenience, one of the major reasons why people shop online instead of offline. Therefore, this study scrutinizes the effects of membership features on trust, focusing on the moderating effects of registration difficulty and membership fees. Research design, data and methodology: A survey method with a total of 296 survey data was used. A 2 × 2 × 2 factorial design was employed. The three independent variables are price discount rate (20% vs. 70%), registration difficulty (low vs. high), and membership fees (yes vs. no). Results: The results reveal that a price discount rate has a negative effect on trust, whereas membership fees and registration difficulty moderate its negative effect on trust. Conclusions: A high price discount rate lowers trust for online luxury shopping malls. Meanwhile, registration difficulty and membership fees can be used to prevent consumers from losing trust caused by the high price discount rate. Therefore, registration difficulty and membership fees are signals implying that not everyone can use these private online shopping malls, which provide low prices for luxury items.

• Communications for Statistical Applications and Methods
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• 제24권6호
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• pp.605-625
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• 2017

This paper presents proportional odds cure models to allow spatial correlations by including spatial frailty in the interval censored data setting. Parametric cure rate models with independent and dependent spatial frailties are proposed and compared. Our approach enables different underlying activation mechanisms that lead to the event of interest; in addition, the number of competing causes which may be responsible for the occurrence of the event of interest follows a Geometric distribution. Markov chain Monte Carlo method is used in a Bayesian framework for inferential purposes. For model comparison some Bayesian criteria were used. An influence diagnostic analysis was conducted to detect possible influential or extreme observations that may cause distortions on the results of the analysis. Finally, the proposed models are applied for the analysis of a real data set on smoking cessation. The results of the application show that the parametric cure model with frailties under the first activation scheme has better findings.

• 한국환경과학회지
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• 제32권3호
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• pp.161-171
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• 2023

The present study evaluated growth factors affecting oak community plantations through literature review and a field survey. Specifically, 41 related literature sources were analyzed and field surveys were conducted to collect growth data. Previous studies were analyzed to identify variables with high frequency of use. The frequency of use was in the order of tree size > environment > planting density > forest age. Analysis of factors impacting height and diameter growth revealed that the growth rate of species other than Quercus variabilis was negative in the field survey. This may be because of differences between the actual trees planted and specifications in the construction drawings, which may be attributed to the site conditions and decisions made by the project subject during construction. Furthermore, simple linear regression analysis was conducted with time, height at planting, density, and species code as the independent variables and growth rate as the dependent variable. A strong positive linear correlation was noted between height and diameter. This work builds a foundation for developing a forest restoration model and simulation program based on a regression model derived from the four variables tested.

• 전자공학회논문지B
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• 제33B권4호
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• pp.131-140
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• 1996

In this paper, we propose the method that extracts the speech feature using the hearing model through signal precessing techniques. The proposed method includes following procedure ; normalization of the short-time speech block by its maximum value, multi-resolution analysis using the discrete wavelet transformation and re-synthesize using thediscrete inverse wavelet transformation, differentiation after analysis and synthesis, full wave rectification and integration. In order to verify the performance of the proposed speech feature in the speech recognition task, korean digita recognition experiments were carried out using both the dTW and the VQ-HMM. The results showed that, in case of using dTW, the recognition rates were 99.79% and 90.33% for speaker-dependent and speaker-independent task respectively and, in case of using VQ-HMM, the rate were 96.5% and 81.5% respectively. And it indicates that the proposed speech feature has the potentials to use as a simple and efficient feature for recognition task.