• 한국콘텐츠학회논문지
• /
• 제11권3호
• /
• pp.477-486
• /
• 2011

본 논문에서는 컴퓨터 사용 시간과 시력 저하 관계를 분석했다. 우선 첫째로, 조사에 참여한 학생들을 성별, 학년, 시력과 안경 착용으로 인구학적 특성에 따라 분류 하였다. 설문은 컴퓨터 사용 시간, 시력 저하의 요인들, 그리고 컴퓨터 사용 목적에 관한 질문들을 하였다. 학생들의 연간 시력 변화와 시력 변화의 원인에 대해서 교차 분석한 결과, 설문에 참가한 165명의 학생 중 63.6%가 한 해 동안 시력이 나빠졌다. 컴퓨터 사용시간과 시력 저하 상관관계를 나타내기 위해 회귀 분석한 결과 일일과 주간 컴퓨터 사용에서는 시력저하를 나타냈고, 년 컴퓨터 사용에서는 시력저하를 나타내지 않았다. 또한 독립 표본 T검정으로 안경 착용과 미착용자의 컴퓨터 사용 시간과 시력 저하를 분석한 결과 일일과 주간 컴퓨터 사용에서는 시력저하를 나타냈고, 년 컴퓨터 사용에서는 시력저하를 나타내지 않았다. 그런데 안경 미 착용자가 안경 착용자에 비해서 시력 저하를 더 나타냈다. 본 논문에서는 24.5%의 학생들이 컴퓨터 사용으로 시력저하를 나타냈다. 컴퓨터 사용 용도의 빈도분석 결과에서는 컴퓨터 게임이 36.4%로 가장 많았고, 그 다음으로 학습목적이 32.1% 나타났다. 본 논문에서는 컴퓨터 사용 시간과 시력 저하의 요인 분석을 통해 컴퓨터 사용 시간이 시력저하에 상관관계가 있음을 나타낸다. 따라서 학생들의 컴퓨터 사용에 대한 학부모님들의 관심이 필요하다.

• 한국지능시스템학회논문지
• /
• 제18권5호
• /
• pp.724-729
• /
• 2008

본 논문에서는 WPAN(Wireless Personal Area Network) 기반의 디지털 음향기기 및 소출력 무선 통신기기를 운용함에 있어서, 한정된 주파수 자원을 효율적으로 할당하기 위한 공유 주파수 대역폭의 산출법을 제시한다. WPAN 기반의 디지털 음향기기 및 통신기기로서는 Digital Cordless Phone (DCP)과 Bluetooth를 비롯하여, RFID와 ZigBee기술을 고려하였다. 또한, 본 논문에서는 상기 WPAN 기반의 디지털 음향기기 및 통신기기간의 스펙트럼 운용 측면에 따른 적용 방식을 DCP, RFID, Bluetooth는 FH (Frequency Hopping) 방식으로, ZigBee는 LBT(Listen Before Talk) 방식으로 분류한 후 대기행렬 이론에 근거한 스펙트럼 상호운용을 위한 채널할당기법을 제시하였다. 본 논문에서는 대기행렬이론 (queuing theory)을 WPAN 기반의 디지털 음향기기 및 통신기기간의 스펙트럼 운용기법에 적용하기 위하여, FH 시스템과 LBT 시스템을 모델링하였고, 컴퓨터 시뮬레이션을 통하여 소요대역폭 산출을 수행했다. 채널수 별 user의 통신시도에 따른 throughput을 분석한 결과, throughput 84% 이상의 조건에서 FH 및 LBT 방식을 사용하는 250mW WPAN 기반의 디지털 음향기기 및 통신기기들이 공존하는 공유주파수대역의 적정 채널수는 35개를 가지며, 총 소요대역폭은 각각의 WPAN기반의 디지털 음향기기 및 통신기기들의 채널수와 채널대역폭의 곱으로 산출이 가능함을 보였다.

• 한국의류학회지
• /
• 제1권2호
• /
• pp.65-70
• /
• 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.

• 한국해양공학회지
• /
• 제36권1호
• /
• pp.61-81
• /
• 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.

• 한국주거학회논문집
• /
• 제21권3호
• /
• pp.53-65
• /
• 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.

• 한국조리학회지
• /
• 제10권4호
• /
• pp.145-164
• /
• 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.

• 한국산업융합학회 논문집
• /
• 제26권3호
• /
• pp.443-454
• /
• 2023

The purpose of this study is to reveal the Korean learners' usage pattern of '의', the genitive particle, according to semantic classification, so that it can be referred to in determining the contents and methods of related education. The method of this study adopts a quantitative analysis using learners corpus established by National Institute of Korean Language. As a result of the analysis, as proficiency increases, the overall frequency of '의' increases and the number of meaning senses used increases. However, the frequency of errors also increases with it. As for the usage pattern of each sense, the meaning of 'ownership, belonging' is the most frequent, and followed by 'acting entity', 'kinship, social relations', and 'relationship(area)'. In conclusion, the meanings of 'acting subjects' and 'relationships(area) need to be supplemented with explicit education. Other meanings need to be discussed, and decisions should be made in consideration of learning purpose and proficiency.

• 수산해양기술연구
• /
• 제58권2호
• /
• pp.175-184
• /
• 2022

This study analyzed the allocation of the skipper's attention during fishing operation in the wheelhouse of a Korean coastal composite fishing vessel by using video observation. To summarize the results, the ratio of lookout, radar and GPS monitoring, which is essential for prevention of collision at sea, was significantly lower than that of other fishing operation due to the attention concentration on the work place during hauling line. In order to reduce exposure to risk of collisions due to concentration of attention to certain tasks such as line hauling, it is necessary to develop an alert system that can notify the approach of other ships or obstruction throughout the ship using information from radar or the automatic identification system. In addition, the order of attention allocation to devices and facilities obtained in this study is expected to be used as basic data for device or facility layout based on the principle of usage frequency in designing wheelhouse for coastal composite fishing vessels in the future.

• 한국생활과학회지
• /
• 제14권4호
• /
• pp.561-575
• /
• 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.

• International Journal of Fluid Machinery and Systems
• /
• 제2권4호
• /
• pp.334-345
• /
• 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.