• 제어로봇시스템학회:학술대회논문집
• /
• 1997.10a
• /
• pp.97-100
• /
• 1997

Fieldbuses are used as the lowest level communication network for real-time communication in factory automation and process control systems. Data generated from field devices can be divided into three categories: sporadic real-time, periodic real-time and non real-time data. Since these data share one fieldbus network medium, it needs a method that allocate the limited bandwidth of fieldbus network to the sporadic real-time, periodic real-time and non real-time traffic. This paper introduces an implementation method of bandwidth allocation scheme introduced in [51 on PROFIBUS. Using the modified PROFIBUS FDL(Fieldbus Data Link layer), the bandwidth allocation scheme introduced in [51 is verified by the experiments.

• Proceedings of the Korea Society for Simulation Conference
• /
• 2002.05a
• /
• pp.33-41
• /
• 2002

This paper deals with the development of simulation model for the container terminal consisting of 3 berths, 8 container cranes, 16 yard blocks with each yard cranes and 90 yard trucks in order to evaluate the various operational rules. The proposed operational rules are 3 ship dispatching rules, 3 berth allocation rules, 2 crane allocation rules, 2 yard allocation rules and 2 yard truck allocation rules and 4 performance measures like ship time in the terminal, ship time in the port, the number of ships processed and the number of containers handled are considered. The simulation result are as follows. 1) no difference among 3 ship dispatching rules, 2) berth allocation rules depends on performance measures 3) dynamic crane allocation is better than fixed policy 4) pooling yard allocation is better than short distance yard allocation rules and 5) fixed yard truck allocation by berth is a little better than pooling policy.

• Journal of Korea Port Economic Association
• /
• v.18 no.1
• /
• pp.27-41
• /
• 2002

This paper deals with the development of a simulation model for the container terminal, which consists of 3 berths, 8 container cranes, and 16 yard blocks with each yard crane and 90 yard trucks in order to evaluate the various operational rules. The proposed operational rules are 3 ship-dispatching rules, 3 berth allocation rules, 2 crane allocation rules, 2 yard allocation rules, and 2 yard truck allocation rules. These rules are simulated using 4 performance measures, such as ship time in the terminal, ship time in the port, the number of ships processed, and the number of containers handled. The simulation result is as follows: 1) there is no difference among 3 ship-dispatching rules, 2) berth allocation rules depend on performance measures, 3) dynamic crane allocation is better than fixed policy, 4) pooling yard allocation is better than short distance yard allocation rules, and 5) fixed yard truck allocation by berth is a little better than pooling policy.

• The KIPS Transactions:PartA
• /
• v.8A no.3
• /
• pp.189-200
• /
• 2001

This paper proposes a memory allocation model for Real-Time Linux. The proposed model allows users to create several continuous memory regions in an application, to specify an appropriate region allocation policy for each memory region, and to request memory blocks from a necessary memory region. Instead of using single memory management module in order to support the proposed model, we adopt two-layered structure that is consisted of region allocators implementing allocation policies and a region manager controlling regions and region allocator modules. This structure separates allocation policy from allocation mechanism, thus allows system developers to implement same allocation policy using different algorithms in case of need. IN addition, it enables them to implement new allocation policy using different algorithms in case of need. In addition, it enables them to implement new allocation policy easily as long as they preserver predefined internal interfaces, to add the implemented policy into the system, and to remove unnecessary allocation policies from the system, Because the proposed model provides various allocation policies implemented previously, system builders can also reconfigure the system by just selecting most appropriate policies for a specific application without implementing these policies from scratch.

• Proceedings of the KIEE Conference
• /
• 2002.11c
• /
• pp.430-433
• /
• 2002

Fieldbus traffic consists of periodic, time-critical and time-available data. A bandwidth allocation scheme allocates periodic, time-critical and time-available data traffic to the bandwidth-limited network resource. This paper presents an implementation method of the bandwidth allocation scheme in the user layer of Foundation fieldbus. In this study, an experimental model of a Foundation Fieldbus network system is developed. Using the experimental model, validity of the bandwidth allocation scheme is examined. The results obtained from the experimental model show that the proposed scheme restricts the delay of both periodic and time-critical data to a pre-specified bound. The bandwidth allocation scheme also fully utilized the bandwidth resource of the network system.

• Journal of Labour Economics
• /
• v.39 no.1
• /
• pp.57-79
• /
• 2016

This study analyses determinant factors of time allocation within married couple using 2014 Time-use survey. Findings show that husbands spend less time on child care and housework than wives do. When wives have high income and young kids, husbands' time spending on child care and housework increases. Wives' time allocation is associated with husbands' income- wives' working time is negatively associated, but wives' housework time is positively associated with husbands' income. However, both wives' and husbands' income is not related to child care time. When wives' income increases, while, husbands' time spent on housework and child care increases. There are complementary relations within time allocation, but substitute relationships between wives' and husbands' housework time. In other words, if a wife works long hours, husband spends more time on housework, but if a wife or a husband spends on housework, her husband or his wife does not spends on it. However, findings of married couple time allocation for weekend shows different patterns from weekday time use.

• Korean Management Science Review
• /
• v.25 no.2
• /
• pp.25-42
• /
• 2008

CDMA/TOD with asymmetric capacity allocation between uplink and downlink is a highly attractive solution to support the next generation mobile systems. This is because flexible asymmetric allocation of capacity to uplink and downlink usually improves the utilization of the limited bandwidth. In this paper, we mathematically formulate an optimal timeslot and code allocation problem, which is to maximize the total utility considering the numbers of codes(channels) allocated to each data class and the forced terminations of previously allocated codes. We also suggest a real-time integrated timeslot and code allocation scheme using Lagrangean relaxation and subgradient optimization techniques. Experimental results show that the proposed scheme provides high-quality solutions in a fast time.

• Journal of information and communication convergence engineering
• /
• v.15 no.1
• /
• pp.21-27
• /
• 2017

In this research, we study the outage probability for distributed space-time coding-based cooperative (DSTC) systems with amplify-and-forward relaying over Rayleigh fading channels with a high temporal correlation where the direct link between the source and the destination is available. In particular, we derive the upper and lower bounds of the outage probability as well as their corresponding asymptotic expressions. In addition, using only the average channel powers for the source-to-relay and relay-to-destination links, we propose an efficient power allocation scheme between the source and the relay to minimize the asymptotic upper bound of the outage probability. Through a numerical investigation, we verify the analytical expressions as well as the effectiveness of the proposed efficient power allocation. The numerical results show that the lower and upper bounds tightly correspond to the exact outage probability, and the proposed efficient power allocation scheme provides an outage probability similar to that of the optimal power allocation scheme that minimizes the exact outage probability.

• Journal of the Korea Society for Simulation
• /
• v.11 no.3
• /
• pp.23-34
• /
• 2002

Dynamic storage allocation (DSA) is a field fairly well studied for a long time as a basic problem of system software area. Due to memory fragmentation problem of DSA and its unpredictable worst case execution time, real-time system designers have believed that DSA may not be promising for real-time application service. Recently, the need for an efficient DSA algorithm is widely discussed and the algorithm is considered to be very important in the real-time system. This paper proposes an efficient DSA algorithm called QSB (quick semi-buddy) which is designed to be suitable for real-time environment. QSB scheme effectively maintains free lists based on quick-fit approach to quickly accommodate small and frequent memory requests, and the other free lists devised with adaptation upon a typical binary buddy mechanism for bigger requests in harmony for the .improved performance. Comprehensive simulation results show that the proposed scheme outperforms QHF which is known to be effective in terms of memory fragmentation up to about 16%. Furthermore, the memory allocation failure ratio is significantly decreased and the worst case execution time is predictable.

• Journal of Family Resource Management and Policy Review
• /
• v.21 no.3
• /
• pp.43-59
• /
• 2017

This study aimed to analyze time allocation for men who work long hours and their wives. Using 2014 time-use survey data (provided by Statistics Korea), we analyzed the amount of time spent in four areas-paid work, housework, leisure, and life essentials-of male workers who work more than 52 hours a week and of their wives. Descriptive statistics and a paired t-test were conducted using SPSS version 18.0. The results were as follows: First, the time allocation of men who worked long hours differed from their wives with the exception of personal maintenance time. Second, the working time of wives who work long hours was longer than their husbands who work long. Third, men who worked long hours did less housework when their wives were employed than when they were not employed. All the results showed gender differences in terms of time allocation. Equal role-sharing between spouses is needed for the work-life balance of both husbands and wives.