• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.9
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• pp.4429-4445
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• 2019

As low-power and low-rate WSNs are being widely used for industrial applications, the scheduling of such applications becomes a critical issue to guarantee meeting the stringent requirements of determinism and tight latencies. This paper studies the link scheduling problem for real-time industrial applications in time-slotted channel hopping (TSCH) networks. We propose a heuristic algorithm for centralized link scheduling referred to as path-collision aware least laxity first (PC-LLF) algorithm, which dynamically prioritizes the packets based on the laxity time to the end-to-end deadlines and the amount of collisions that messages might deal with along their designated paths to the destination device. We propose schedulability analysis of real-time applications scheduled under our prioritization approach over TSCH networks, based on the literature on real-time schedulability analysis of multiprocessors and distributed systems. We show that our methodology provides an improved schedulability condition with respect to the existing approaches. Performance evaluation studies quantify to quantify the performance of our proposed approach under a variety of scenarios.

• Structural Engineering and Mechanics
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• v.44 no.3
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• pp.379-403
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• 2012

In recent years, the need for optimal design of structures under time-history loading aroused great attention in researchers. The main problem in this field is the extremely high computational demand of time-history analyses, which may convert the solution algorithm to an illogical one. In this paper, a new framework is developed to solve the size optimization problem of steel truss structures subjected to ground motions. In order to solve this problem, the covariance matrix adaptation evolution strategy algorithm is employed for the optimization procedure, while a generalized regression neural network is utilized as a meta-model for fitness approximation. Moreover, the computational cost of time-history analysis is decreased through a wavelet analysis. Capability and efficiency of the proposed framework is investigated via two design examples, comprising of a tower truss and a footbridge truss.

• SUVANNABHUMI
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• v.7 no.2
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• pp.3-25
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• 2015

This paper reflects on the relationship between postcolonial criticism (PC) and Southeast Asian Studies. The emphasis is on the apparent premature retreat from PC as well as its unfulfilled promises and persistent pitfalls. I argue that it is premature to abandon PC because it remains relevant, even essential, in the context of the much ballyhooed age of "knowledge economy" or "information society." There is a need to take another look at its promises and to work towards fulfilling them, but at the same time be conscious of its persistent problems.

• Journal of Korean Academy of Oral and Maxillofacial Radiology
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• v.22 no.2
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• pp.293-303
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• 1992

Generally the patient's absorb dose and readability of radiograms are affected by the exposure time and kVp of which are related with the radiographic density and contrast The investigator carried studies to know the adequate level of exposure time and kVp to obtain the better readability of radiograms. In these studies dried human mandible with selfcuring acrylic resins attached with aluminum step wedge was used and readability of radiograms were compared with each other by videodensitometry among various combination sets of the exposure time, such as 5, 6, 8, 12, 15, 19, 24, 30, 38, 48 and 60, and varing level of kVp, such as 60, 65, 70, 80 and 90 respectively. The obtained results were as follows: 1. As exposure time and kVp were increased, radiographic density of radiograms was increased. 2. The subject contrast was increased where aluminum step wedge was thin and reduced in the reversed condition. At the thin aluminum step wedge, subject contrast was increased at the condition of lower kilovoltage than that of higher kilovoltage. 3. In the case of non-constant radiographic density, the radiographic contrast was reduced with the increment kilovoltage. The radiographic contrast was increased in the lower kilovoltage with the longer exposure time and the higher kilovoltage with the shorter exposure time. 4. At the condition of short exposure time, better readability of each reading item was obtained with the increment of the kilovoltage but at the opposite condition increasing exposure time worsened readability of radiograms. Since X-ray machine in the current dental clinics is fixed between the range of 60-70kVp and 10mA, good radiograms can be obtained by varied exposure time. But according to the conclusion of these studies, better radiograms can be obtained by using filtered high kVp and then the absorb dose to patient and exposure time can be reduced.

• Journal of the Economic Geographical Society of Korea
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• v.16 no.3
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• pp.492-511
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• 2013

According to IASB(International Accounting Standards Board), R&D(Research and Development) is defined as a tertiary sector industry combining research and development. Many studies investigated R&D industry clusters in the form of high-tech cluster(Coe et al., 2007). However, these studies only generalized various spatial cluster of R&D industries. In particular, the studies could not considers cluster formation process over time lacking statistical significance in space-time perspectives. This study, therefore, indicates the limitation of recent R&D cluster literature which only considers either time or space. In addition, this study explores space-time clusters in R&D industry together with textile and cloth industry for comparison. Discovering the existence and location of clusters, this study utilized space-time K function and space-time scan statistics. The result shows that R&D industry presents significant clusters only in spatial dimension. No significant clusters were found in space-time dimension. However, textile and clothing industry presents significant clusters in both spatial and space-time dimensions.

• Journal of Family Resource Management and Policy Review
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• v.16 no.3
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• pp.109-132
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• 2012

This study explores how unmarried workers use their leisure time according to the 2009 Korean Time Use Survey. The purposes of this study are: 1) to investigate leisure time as it relates to leisure participation rates and leisure participation time and 2) to analyze the effect of socio-demographic variables on leisure time and leisure participation by unmarried workers. The following is a summary of the major findings. First, leisure participation differed with variations in leisure activities. Unmarried workers participated in media contact, human relations activities, and hobby activities more than other activities. Participation in learning activities was higher on weekdays than on Sunday. Men participated in sports and outdoor activities more than women on Sundays. The participation rate of media contact was the highest, while the participation rate of volunteer activities was the lowest. Second, influencing factors on leisure time included gender, age, monthly income, and gender role attitudes when work time was controlled. For example, unmarried workers with egalitarian attitudes spent less leisure time. Third, gender was the strongest determinant of leisure participation. The probability of women's leisure participation was higher than men except in regards to sports and outdoor activities, and hobby activities.

• Korean Journal of Human Ecology
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• v.12 no.3
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• pp.321-336
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• 2003

This study aims at more exactly identifying current status and trend of the school violence in elementary schools. Many previous studies have addressed the issue with their own views and methodologies, and mostly ended up as one-time works without subsequent observation over years. From such respective studies, we could hardly figure out an integral and precise shape on the school violence in terms of fact and tendency. To my knowledge, this is the first time-lag design on the school violence which is conducted nation wide, where the same concepts and measures were applied to the population. The research conclusions are follows: (1) both offenders and victims of the school violence tend to increase, (2) compared 10 girls, boys have more experience of the school violence, and (3) both offenders and victims could be recruited from the same group.

• Journal of the Korean Data and Information Science Society
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• v.17 no.2
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• pp.581-598
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• 2006

In many epidemiological and medical studies, a number of cancer mortalities in categorical classification may be considered as having Poisson distribution with person-years at risk depending upon time. The cancer mortalities have been evaluated by additive or multiplicative models with regard to background and excess risks based on several covariances such as sex, age at the time of bombings, time at exposure, or ionizing radiation, cigarette smoking habits, duration of smoking habits, etc. An interest herein is to examine an additive, synergistic, or antagonistic relationship between radiation exposures and cigarette smoking habits for cancer mortalities. The results revealed a highly significant antagonistic in uence for cancer mortalities from all non-hematologic findings, lung and respiratory system with negative interaction between radiation exposures and cigarette smoking amounts.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.835-837
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• 2005

컴퓨터 산업의 빠른 발전과 더불어 근래에는 임베디드 시스템 분야가 빠르게 성장하고 있다. 이전에 작고 단순하던 임베디드 시스템이 산업의 발전과 사용자의 다양한 요구로 운영체제의 필요성이 높아지고 운영체제하에서 관리하는 실시간 프로세스들의 크기와 복잡도가 빠르게 증가하고 있다. 본 논문에서는 분산 실시간 객체 모델인 TMO-MicroC/OS-II의 실시간 스케줄러의 설계와 구현 방법을 기술하였다. TMO-MicroC/OS-II는 $Micrium^{TM}$에서 개발한 임베디드 OS인 MicroC/OS-II에 분산실시간 객체 모델인 TMO를 적용시킨 것이다. TMO (Time-triggered Message-triggered Object)는 시간조건에 의해 구동되는 객체 내의 실시간 스레드들의 동적 맴버들로 구성되는 프로그래밍 페러다임으로 본 논문에서는 TMO모델 적용을 위한 Deadline-driven 스케줄러 구현에 대해서 기술한다.

• Journal of Family Resource Management and Policy Review
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• v.10 no.1
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• pp.67-81
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• 2006

This study focused on the system regarding leave of absence in relation to family welfare, which has become a routine in some western countries, in three different perspectives. Those were the relations between reduced working hours and quality of life, maternal recreation, and finally, relations between infrastructure of vacation and culture. Systematic settlement of reduced working hours and maternal recreation in Germany allowed more time among family members and made large contribution to the improvement of family welfare in general. Since the stability of society is strongly based on the stability of family, Germany deserved to be case-studied as a good model. The recent tendency shows that Korean workers are starting to spend more time with their own family members than with their colleagues, and, as seen in the case of Germany, the stability of family welfare will improve if various infrastructures for family leisure are properly established in Korea.