• 산업공학
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• 제4권1호
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• pp.63-69
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• 1991

In this paper, the Go-Back-N ARQ protocol with decoding in communication network is considered. The time delay and throughput are respectively analyzed as a function of window size and decoding time out. Packets arrive continuously at the decoder, and are stored in a buffer if the decoder is busy upon its arrival. The decoder devotes no more than a time-out period of predetermined length to the decoding of any single packet. If packet decoding is completed within that period, the packet leaves the system. Otherwise, it is retransimitted and its decoding starts anew. The time delay and throughput are obtained using recursive formula and difference equation. An appropriate time out and window size that satisfies the grade of service can be determined.

• Journal of applied mathematics & informatics
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• 제30권5_6호
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• pp.749-757
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• 2012

We consider the M/PH,G/1 queue with two classes of customers in which class-1 customers have deterministic impatience time and have preemptive priority over class-2 customers who are assumed to be infinitely patient. The service times of class-1 and class-2 customers have a phase-type distribution and a general distribution, respectively. We obtain performance measures of class-2 customers such as the queue length distribution, the waiting time distribution and the sojourn time distribution, by analyzing the busy period of class-1 customers. We also compute the moments of the queue length and the waiting and sojourn times.

• 한국인구학
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• 제33권1호
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• pp.27-49
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• 2010

이 연구는 시간압박의 개념을 중심으로 남녀에 따라 지각하는 시간압박수준이 어떻게 차이가 나고, 시간압박에 영향을 미치는 관련요인들에서의 성차가 무엇인지 살펴보고자 하였다. 자료는 2004년 생활시간자료를 활용하였다. 일하는 연령에 해당하는 25-54세의 기혼의 대상자들만을 선별하여 살펴본 분석결과, 첫째, 평균적으로 남성이 여성보다 시간압박을 더 많이 지각하는 것으로 나타났다. 취업여부와 성의 조합형태로 살펴본 교차분석 결과에서는 취업남녀가 유사한 시간압박 수준을 나타내는 가운데 비취업여성, 비취업남성 순으로 시간압박을 지각하는 것을 관찰할 수 있었다. 둘째, 시간압박을 종속으로 하는 순서화 로짓분석결과, 시간압박과 관련 있게 나타난 특성의 구성에서 남녀에 따른 차이점과 공통점이 함께 발견되었다. 남성의 경우 사회인구학적 특성과 직업특성과 관련된 특성 및 시간활용이 그들의 시간압박과 관련이 있는 것으로 나타났다. 여성의 경우에는 시간압박과의 관련요인들이 남성의 경우와 비교해 볼 때 더 다양하였다. 교육수준, 소득, 직종, 근무형태, 요일, 자녀연령을 비롯하여, 임금노동시간, 이동시간, 여가시간을 비롯하여, 돌봄노동시간, 가사노동시간 그리고 전화통화시간까지도 시간부족과 관련이 있는 것으로 나타났다.

• 아동학회지
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• 제30권4호
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• pp.223-239
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• 2009

In order toidentify the daily activities of five-year-old children in a daycare center, the 23 children in "Yellow" class at "Yellow" Daycare Center were observed for seven months. Research was informed by a qualitative approach. Findings were that : children were rigidly attached to a time frame built into their daily classroom schedule, arranged by time and classroom space allotted to each unit. The meaning to the children was to be found in their "busyness;" they were very busy finalizing activities imposed by teachers within a short period of time. They spent most of their time moving about from one space to another within the classroom, and they played with their mostly artificial toys under rules set by the teacher.

• ETRI Journal
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• 제36권5호
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• pp.876-879
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• 2014

In current NAND flash design, one of the most challenging issues is reducing peak current consumption (peak ICC), as it leads to peak power drop, which can cause malfunctions in NAND flash memory. This paper presents an efficient approach for reducing the peak ICC of the cache program in NAND flash memory - namely, a program Cache Busy Time (tPCBSY) control method. The proposed tPCBSY control method is based on the interesting observation that the array program current (ICC2) is mainly decided by the bit-line bias condition. In the proposed approach, when peak ICC2 becomes larger than a threshold value, which is determined by a cache loop number, cache data cannot be loaded to the cache buffer (CB). On the other hand, when peak ICC2 is smaller than the threshold level, cache data can be loaded to the CB. As a result, the peak ICC of the cache program is reduced by 32% at the least significant bit page and by 15% at the most significant bit page. In addition, the program throughput reaches 20 MB/s in multiplane cache program operation, without restrictions caused by a drop in peak power due to cache program operations in a solid-state drive.

• 한국환경교육학회지:환경교육
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• 제12권1호
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• pp.391-409
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• 1999

From the students' point of view, this study was carried out to find out barriers to environmental conservation practice of secondary school students. According to the questionare and interview with secondary school students on barriers to environmental conservation practice at home, school, society and fellow-relation conditions and in personal psychology, the following findings were resulted. The major barriers to environmental conservation practice are (1) not doing environmental conservation practice of parents, friends and neighborhood, (2) having no interest in environment and environmental problems, (3) dirty and laboriousness of environmental conservation practice, (4) lack of environmental equipments, (5) the shortage of chance and time for environmental conversation practice, (6) lack of the inducement for environmental conservaton from school, (7) little effects of individual environmental practice, (8) a busy life, (9) shortage of the voluntary courage to practice for environmental conservation, (10) lack of compensation on the environmental conservation practice, (11) anti-environmental behavior among friends, (12) urging on edcation of parents. Those barriers related with home, school, society and fellow-relation anti-environmental conditions hold back environmental conservation practice of secondary school students. Those barriers are divided into three closely correlated tipes, (1) unpleasant traits of environmental conservation practice such as cleaning, recycling were linked with personal psychology, (2) lack of the social interest and practice for environmental conservation were linked with personal psychology, (3) the social atmosphere to urge on education was linked with students' busy life and the shortage of chance and time for environmental conversation practice. According to the results, attractive environmental education programs, home environmental education, cooperative environmental conservation programs, and inducements for environmental conservation are reguired of secondary school students to promote environmental conservation practice.

• 한국통신학회논문지
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• 제17권7호
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• pp.641-655
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• 1992

본 논문에서는 이동 컴퓨터 통신망을 구현할 때 사용될 수 있는 여러 다중 엑세스 방식의 성능을 이동통신 채널의 특성을 고려하여 비교 하였다. 숨겨진 노드가 존재하는 상황에서 Code Division Multiple Access(CDMA)방식이 동시에 엑세스가 가능하기 때문에 Carrier Sensed Multiple Access(CSMA), Idle Signal Multiple Access (ISMA) 및 Busy Tone Multiple Access(BTMA) 등과 같은 패켓 엑세스 방식에 비하여 처리율면이나 평균지연 시간의 측면에서 우수함을 알 수 있었다. 또한 여러 방식중 대역확산 방식을 사용한 CDMA 방식이 페이딩 현상이나 임펄스성 잡음이 존재할 때 CSMA 등과 같은 패켓 엑세스 방식에 비하여 우수함을 컴퓨터 시뮬레이션을 통하여 확인하였다. 특히 분산망의 경우에 있어서는, CDMA 방식을 효율적으로 이용한 수신자 전송자 코드분할 다중 엑세스(Recciver Transmitter CDMA) 방식이 공통-송신자 코드분할 다중엑세스(Common Transmitter CDMA) 방식에 비하여 좋은 처리율과 적은 지연시간을 나타내었다.

• 한국농촌생활과학회지
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• 제9권1호
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• pp.67-78
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• 1998

This study compared the pattern of couples' time-use in rural areas. Wives' and husbands' time spent in household work, leisure, and agricultural labor were compared. In addition, this study examined what factors determine the amount of time of couples spent in such activities. According to the results, in general, the pattern of couple's time-use in rural area was different. Regarding the pattern of time-use, three major results could be mentioned. First of all, husband in rural area spent most agricultural labour time in busy farming season. And then husband spent much time in leisure activities and wife spent in household work. Second, wife spent more time in inactive leisure and husband spent more time in active leisure. Third, husband in rural area spent less time in household work. In particular. they spent less time in female-typed work than male-typed work. To examine what factors determine the extent of time spent in such activities, three theories were employed and tested. According to the results, the models employed in this study were realistic in explaining the amount of time of couple in rural area, and more adjustable wife than husband. In conclusion, a combination of the multidimensional theoretical perspectives used in this study helpfully explains the variation in the amount of time-use of couple in rural area.

• Management Science and Financial Engineering
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• 제2권1호
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• pp.123-145
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• 1996

We consider a priority-based multiclass queue with probabilistic feed-back. There are J service stations. Each customer belongs to one of the several priority classes, and the customers of each class arrive at each station in a Poisson process. A single server serves queued customers on a priority basis with a nonpreemptive scheduling discipline. The customers who complete their services feed back to the system instantaneously and join one of the queues of the stations or depart from the system according to a given probability. In this paper, we propose a new method to simplify the analysis of these queueing systems. By the analysis of busy periods and regenerative processes, we clarify the underlying system structure, and systematically obtain the mean for the sojourn time, i.e., the time from the arrival to the departure from the system, of a customer at every station. The mean for the number of customers queued in each station at an arbitrary time is also obtained simultaneously.

• Journal of information and communication convergence engineering
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• 제10권4호
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• pp.396-404
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• 2012

This paper proposes an analysis method to check the schedulability of a set of sporadic tasks under earliest deadline first (EDF) scheduler. The sporadic task model consists of subtasks with precedence constraints, arbitrary arrival times and deadlines. In order to determine the schedulability, we present an approach to find exact worst case response time (WCRT) of subtatsks. With the technique presented in this paper, we exploit the precedence relations between subtasks in an accurate way while taking advantage of the deadline of different subtasks. Another nice feature of our approach is that it avoids calculation time overhead by exploiting the concept of deadline busy period. Experimental results show that this consideration leads to a significant improvement compared with existing work.