• The Journal of the Korea Contents Association
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• v.11 no.3
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• pp.477-486
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• 2011

In this paper, I had tried to analyze the relationship between the time assigned for computer usage and weakening eyesight. First of all, students classified by gender, school year, eyesight, and wearing glasses along demographic characters took part in a poll, and The questionnaire included questions about computer time, factors of weakening eyesight, and purpose of computer use. The finding in this analysis composed of a cross-tabulations between annual eyesight change and the factors to change their eyesight is that 63.6 % of 165 students participated in this survey weakened their eyesight within a year. To show a correlation between computer usage duration and worsening eyesight in this paper, regression analysis indicated weakened vision by computer usage duration per day and week instead of a year. In addition, according to the analysis between computer usage duration and weakened vision for the people who wear glasses or not trough Independent-Samples T test, weakened vision was shown in computer usage duration per day and week, but not shown in the duration by the year. Therefore, weakening vision was also worse for the people who didn't wear glasses than the others. This study indicated 24..5% of teenagers had poor eyesight by using their computer. According to the frequency analysis on purposes of computer usage, the biggest purpose accounting for 36.4% of the total was the computer usage as a game consol, and the computer as a learning tool was the next biggest purpose at 32.1%. This paper showed the correlation between computer usage time and a factor of weakened eyesight through an analysis of the factor. Therefore, schoolchildren's parents should be more interested in their computer usage.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.5
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• pp.724-729
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• 2008

This paper presents the calculation of the required bandwidth of common frequency bandwidth applying queueing theory for maximizing the efficiency of frequency resource of WPAN(Wireless Personal Area Network) based Digital acoustic and communication devices. It assumed that LBT device(ZigBee) and FH devices (DCP, RFID and Bluetooth) coexist in the common frequency band for WPAN based Digital acoustic and communication devices. Frequency hopping (FH) and listen before talk (LBT) have been used for interference avoidance in the short range device (SRD). The LBT system transmits data after searching for usable frequency bandwidth in the radio wave environment. However, the FH system transmits data without searching for usable frequency bandwidth. The queuing theory is employed to model the FH and LBT system, respectively. As a result, the throughput for each channel was analyzed by processing the usage frequency and the interval of service time for each channel statistically. When common frequency bandwidth is shared with SRD using 250mW, it was known that about 35 channels were required at the condition of throughput 84%, which was determined with the input condition of Gaussian distribution implying safety communication. Therefore, the common frequency bandwidth is estimated with multiplying the number of channel by the bandwidth per channel. These methodology will be useful for the efficient usage of frequency bandwidth.

• Journal of Ocean Engineering and Technology
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• v.36 no.1
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• pp.61-81
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• 2022

The available underwater acoustic spectrum is limited. Therefore, it is imperative to avoid frequency interference from overlapping frequencies of underwater acoustic equipment (UAE) for the co-existence of the UAE. Cognitive technology that senses idle spectrum and actively avoids frequency interference is an efficient method to facilitate the collision-free operation of multiple UAE with overlapping frequencies. Cognitive technology is adopted to identify the frequency usage of UAE to apply cognitive technology. To this end, we investigated two principle underwater acoustic sources: UAE and marine animals. The UAE is classified into five types: underwater acoustic modem, acoustic positioning system, multi-beam echo-sounder, side-scan sonar, and sub-bottom profiler. We analyzed the parameters of the frequency band, directivity, range, and depth, which play a critical role in the design of underwater acoustic cognitive technology. Moreover, the frequency band of several marine species was also examined. The mid-frequency band from 10 - 40 kHz was found to be the busiest. Lastly, this study provides useful insights into the design of underwater acoustic cognitive technologies, where it is essential to avoid interference among the UAE in this mid-frequency band.

• Journal of the Korean Society of Clothing and Textiles
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• v.1 no.2
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• pp.65-70
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• 1977

The purpose of this study was to investigate the relation of attitudes and usage of denim cloth-ing to masculinity femininity, attitudes toward women's role, and four aspects of clothing interests. Masculinity-femininity was assessed by The Fe Scale of the California Psychological Inventory. Attitudes toward women's role was measured by selected items from The Inventory of Feminine Values and The Sex Ideology Scale. Measures of attitudes toward denim clothing consisted of: 1) attitudes regarding practicality and youth symbol, 2) possession, and 3) frequency of wearing denim clothing. Four aspects of clothing interests in general were assessed by statements dealing with choice of design, conformity-individuality, fashion and practicality in clothing. The sample consisted of 388 students in Sookmyung Women's University in Seoul, Korea. The data, collected by means of a self-administered questionnaire, were analyzed by correlation. The results indicate that: 1) Masculinity-femininity was related to youth symbol attitudes, possession, and frequency of wear-ing denim clothing. 2) Attitudes toward women's role was related to practicality attitudes, and frequency of wearing denim clothing. 3) Practicality attitudes toward denim clothing was related to conformity-individuality, and practicality in clothing. 4) Youth symbol attitudes toward denim clothing was related to fashion in clothing. 5) Possession of denim clothing was related to fashion and the choice of design in clothing. 6) Frequency of wearing denim clothing was related to the choice of design, and conformity-individuality in clothing.

• Culinary science and hospitality research
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• v.10 no.4
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• pp.145-164
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• 2004

The purpose of this study was to find the significant relationship between the foodservice quality and the frequency of Dining-out. The participants are categorized by the purpose of dinning out. The survey was performed at restaurants of T, B, S, C, and M. The survey materials have been distributed for one-month period, from the 6th of June, 2004 to 31st of June, 2004. The general information of the participants and the occasion usage are analyzed using frequency and chi-square. The ANOVA is used to analyze relationship between each variable and the level of the satisfaction for individual restaurant.

• Korean Journal of Human Ecology
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• v.14 no.4
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• pp.561-575
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• 2005

This paper searches Internet auction sites to study consumer willingness to reuse and consumer satisfaction, along with its frequency of usage and evaluation. This study also examines the differency in the frequency of usage, the number of products purchased, consumer satisfaction and willingness to reuse, and evaluation of the auction sites according to the characteristics of consumers' socio-economic factors and the auction site itself. Determinant variables is investigated in the level of consumer satisfaction. The results of this study are as below: First, consumers used auction sites frequently, especially when they were in their 20s, intended to purchase clothes, and thought the delivery time would be short. In addition, consumers were more likely to purchase products, with low income buy first pay later, and short deliberation. Second, consumers, unemployed and in their 50s, sell-purchase among consumers were less likely to have a willingness to reuse the auction site. However, consumers with an experience to buy clothes or products with a price between 50,000 and 100,000 won were more likely to have a willingness to reuse the site. Third, consumer satisfaction with auction sites were higher among those who were females; responsible as a consumer; full of experiences; and received the product within a short period of time. Lastly, the willingness to reuse auction sites was positively related to the following type of consumers: single, employed, and responsible as a consumer.

• Journal of the Korean housing association
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• v.21 no.3
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• pp.53-65
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• 2010

The purpose of this study is to develop a checklist based on the stored items of cooking, for making a good kitchen furniture reseach. The research candidates are purposive sampled from 30 households of for 40 or 50 pyeong-type apartments in Kangnam, Seoul, The research data are is collected gotten at by a field study of the stored items of cooking, eating and utility area, by an in-depth interview to 30 households, and by a field survey of the department stores, super-markets of home appliances. Studied households in average hold about 890 items, which are classified as 239 sorts. The first step of making the checklist is to categorize items into 9 biggest categories, considering the usage of items and the stage of the preparing the food. when the item was used. Second step of making the checklist is to categorize the items into 31 smaller categories, which reflect the shape of items, the storage style and the place of storage. Third step of making the checklist is to sort the items into smallest categories by the frequency of the usage, storage type, and the additional capacity of the item. Even Although items are sorted into the same level of categories, the frequency of use make a different storage area. Also, the storage style of the items was different according to the storage area. Based on these factors, we suggested a checklist based on the stored items of cooking.

• International Journal of Fluid Machinery and Systems
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• v.2 no.4
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• pp.334-345
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• 2009

Pumped storage power plants are playing a significant role in the contribution to the stabilization of an electrical grid, above all by stable operation and fast reaction to sudden load respectively frequency changes. Optimized efficiency and smooth running characteristics both in pump and turbine operation, improved stability for synchronization in turbine mode, load control in pump mode operation and also short reaction times may be achieved using adjustable speed power units. Such variable speed power plants are applicable for high variations of head (e.g. important for low head pump-turbine projects). Due to the rapid development of power semiconductors and frequency converter technology, feasible solutions can be provided even for large hydro power units. Suitable control strategies as well as clear design criteria contribute significantly to the optimal usage of the pump turbine and motor-generators. The SIMSEN tool for dynamic simulations has been used for comparative investigations of different configurations regarding the power converter topology, types of semiconductors and types of motor-generators including the coupling to the hydraulic system. A brief overview of the advantages & disadvantages of the different solutions can also be found in this paper. Using this approach, a customized solution minimizing cost and exploiting the maximum usage of the pump-turbine unit can be developed in the planning stage of new and modernization pump storage projects.

• Korea journal of population studies
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• v.34 no.3
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• pp.85-107
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• 2011

Based on two cross-sectional Time Diary data. this study examines the change in internet use pattern of Koreans. Building on the literatures on Digital Divides, it traces the changes in frequency, diversity and specific purpose of internet use and tries to identify factors affecting these changes. The results show that the frequency and diversity of internet use increases across five years. They also reveal that the usage gap in internet between genders increases While the usage gap across social economic status still exists. The implication of these results are discussed.

• IE interfaces
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• v.22 no.4
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• pp.329-335
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• 2009

Recently, the use of soft-keyboard is widespread and increases, because various handheld devices were developed such as PDA, navigation, mobile phones with enhanced competence of touchscreen. The use of soft-keyboard requires different characteristics compared to traditional hard-keyboard like QWERTY keyboard: no standard character layout, one finger entry, and cognitive processing time. In this study, therefore, the optimal soft-keyboard layout for one finger text entry in touchscreen environment was investigated among 6 keyboard layouts which were developed based on traditional characteristic of Korean text and the usage frequency of both vowels and consonants. As a result, the interface with Korean text invention order like 'ㄱㄴㄷㄹ' or 'ㅏㅑㅓㅕㅕ' was found to be better than the interface with usage frequency-based arrangement. Especially the vowels were most efficient when separated into two parts; located at the right-hand side and at right below the consonants. In conclusion, the keyboard layout with regard to the Korean text characteristic and the invention order was a more effective layout resulted from the minimum cognitive processing time.