• International Journal of Internet, Broadcasting and Communication
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• v.10 no.1
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• pp.1-10
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• 2018

In cognitive radio (CR), secondary users (SUs) are able to sense the absence of primary users (PUs) in the spectrum. Then, SUs use this information to opportunistically access the licensed spectrum in the PUs' absence. In this paper, we present an implementation of real-time video transmission with spectrum-sensing between two points using GNU Radio and a National Instruments 2900 Universal Software Radio Peripheral (USRP). In our project, spectrum-sensing is implemented at both transmitter and receiver. The transmitter senses the channel, and if the channel is free, a video signal (which could be a real-time signal from a video file) will be modulated and processed by GNU Radio and transmitted using a USRP. A USRP receiver also senses the channel, but in contrast, if the channel is busy, the signal is demodulated to reproduce the transmitted video signal. This project brings in several challenges, like spectrum-sensing in the devices' environment, and packets getting lost or corrupted over the air.

• Journal of Korea Society of Industrial Information Systems
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• v.13 no.5
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• pp.98-105
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• 2008

Zigbee communication is applied in the many communication system. This paper is the system development contents which applies a zigbee communication. The system which develops from this paper is apply a zigbee communication in order system Does so, Reduced the step of orders from employee or from counter. Because of that, reduced the order number of times which goes wrong and shortened a time. Reasoning is caused by prevented an order delay at busy time. Order and payment are together controlled from inside the program which is developed. The adjust of the present state of sale does not have a necessity. Because that is stored at Database.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.2
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• pp.171-183
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• 2013

We examined breakfast patterns and preferences in 420 elementary school students (216 boys, 206 girls) in the Chung-nam area. About thirty percent of the subjects had breakfast irregularly. The main reasons for skipping breakfast were having a 'poor appetite' and being 'busy'. The person who prepared breakfast was the 'mother' in both groups. Subjects were satisfied with 'Korean style' menu but dissatisfied with 'rice porridge-style'. Multiple regression analysis indicated that the 'frequency of having breakfast' was positively related to the subject's 'frequency of having breakfast with their mother'. On the other hand, the frequency of having breakfast was negatively related to feeling obligated to have breakfast. The multiple regression analysis also indicated that a Korean style 'breakfast preference' was positively related to the mother's age and negatively related to their 'wake-up time'. A 'breakfast preference for bread and milk' was positively related to 'bed time' and negatively related to the 'age of the father'. Our results will provide critical information for the nutritional education of elementary school students.

• The Transactions of the Korea Information Processing Society
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• v.4 no.11
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• pp.2849-2860
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• 1997

In this paper, we present efficient cache replacement policies for the software RAID file system. The performance of this policies is compared to two other policies previously proposed for conventional file systems and adapted for the software RAID file system. As in hardware RAID systems, we found small-writes to be the performance bottleneck in software RAID file systems. To tackle this small-write problem, we propose cache replacement policies. Using trace driven simulations we show that the proposed policies improve performance in the aspect of the average response time and the average system busy time.

• Journal of Internet of Things and Convergence
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• v.10 no.4
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• pp.35-41
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• 2024

Due to increasingly busy lifestyles, sleep time is gradually being reduced, leading to a growing interest in effective sleep methods. Traditional alarms that only ring at a set time can disrupt efficient sleep and increase fatigue. To solve this problem, a smart alarm system utilizing Raspberry Pi has been proposed. The proposed alarm not only rings at a preset time, like conventional alarms, but also helps by using an infrared sensor attached to the Raspberry Pi to detect the user's sleep onset time and calculate the optimal sleep duration, setting the alarm accordingly. Additionally, it allows for easy naps during the day by setting a fixed nap time. This Smart Alarm system was implemented using MIT App Inventor. The proposed Smart Alarm system is expected to contribute to more efficient sleep.

• The Journal of the Korea Contents Association
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• v.18 no.3
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• pp.34-40
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• 2018

In this study, the optimal buffer size is calculated for seamless video playback on a mobile device. Buffer means the memory space for multimedia packet which arrives in mobile device for video play such as VOD service. If the buffer size is too large, latency time before video playback can be longer. However, if it is too short, playback service can be paused because of shortage of packets arrived. Hence, the optimal buffer size insures QoS of video playback on mobile devices. We model the process of buffering into a discret-time queueing model. Mean busy period length and mean waiting time of Geo/G/1 queue with N-policy is analyzed. After then, we uses the main performance measures to present numerical examples to decide the optimal buffer size on mobile devices. Our results enhance the user satisfaction by insuring the seamless playback and minimizing the initial delay time in VOD streaming process.

• Culinary science and hospitality research
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• v.8 no.3
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• pp.91-106
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• 2002

To achieve these goals constituent dimensions and structural elements of the Japanese restaurants service quality are being investigated through the review of the food service industry and service. The survey about the importance and the Japanese restaurants was also conducted with a questionnaire to identify the tendency of customers who visited restaurants. These results and satisfactions hypotheses are being tested in the restaurant and the empirical research aye both conducted to achieve time research purposes. Japanese restaurants, located in the metropolitan area, are being selected as the object limits of the survey. Eighty-seven questionnaires are being distributed three kinds restaurants which means total 250 for all, and from which 230 are being analyzed. Frequency and $\chi$$^2$test were applied for the general matters and the conditions of object while Cronbach's Alpha coefficient and factor analysis were applied for reliability and validity. t-test was attempted to fine the importance and the satisfaction of the service quality. Also ANOVA was utilized. After examining the results of this survey, few facts were apparent. First the number of male ana female customers in the Japanese restaurants are divided evenly in about 55% of male customers and 45% of female customers. However, these people have a wide variety of jos. Another evident fact present on this survey shows that customers eating at a less expensive restaurants have a income of 1,000,000 won where as the expensive or high-end restaurants have customers with higher income than average. The price sensitive customers studied in this survey shows that they spend on average 30,000 to 70,000 won per person in the less expensive establishments. Therefore, with some service quality restructuring, application of new systems and ideas these restaurants could efficiently maximize their profit margin. Customers also showed that lower prices in lunch time would be an appealing incentive to deviate from standard lunch time 〈12:00~13:00〉and menu specials would be of interest to deviate from busy dinner time. In conclusion, since restaurants in the middle range category are not so many restaurants in lower range have a chance to maximize their profit. This study clearly shows that even the lower-end restaurants could raise their profit margin by incorporating new marketing techniques and by improving the service level of their restaurants.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2437-2445
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• 2012

This paper presents the efficient measurement method of radio resource by analyzing various medium occupied elements. The medium occupied time consists of 802.11 frames, wireless interference, and protocol waiting time from a wireless node on a current channel. And it is used to performance metric. Existing research is only measured partial occupied elements, and is lack of validation of measurement unit and scalability on various IEEE 802.11 radio. This paper presents the measurement method of classified occupied elements. To achieve this, we modified 802.11n based OpenHAL device driver to collect the register information of wireless chipset, and to analyze receiving frames in an virtual monitor mode. We conclude accurate medium occupied time measurement system from various validation methods.

• Journal of Family Resource Management and Policy Review
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• v.9 no.3
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• pp.17-29
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• 2005

The purpose of this study is to identify the characteristics of the household labors that are performed by dual income families. The methodology that has been applied in this study was a qualitative research based on in-depth interviews of a total of 10 people(8 housewives, 2 husbands) selected from the 8 different families. The 8 different families have been selected in order to identify the different family lives and the various household labor patterns that are conducted by both the working husband and the working wife. As a result, we have found out that working wives still had to manage their time in an extremely busy manner in order to balance their professional work with their household tasks. However, the household work that was being shared by the husbands also seemed to vary dynamically according to the different family situations. Although, it has shown that household tasks are divided by the person's sex, the amount of household tasks that are shared tended to increase according to the life cycle of each family.

• The Transactions of the Korea Information Processing Society
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• v.2 no.4
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• pp.543-553
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• 1995

While RAID 5 disk arrays offer advantages of performance and reliability on wide variety of applications, they suffer from the performance degradation with write jobs. To reduce the effect of this problem, parity logging scheme was suggested. This scheme reduces disk busy time by transforming many small random accesses into large sequential accesses. This paper presents a new parity logging technique which prevents parity update image from redundant storing in the disk buffer and reduces parity maintenance overhead. A analytical model and several simulation results of our proposed scheme are presented.