• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.2
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• pp.270-279
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• 2022

In this paper, system dynamics considering dynamics and time was examined to study the changes in system structure according to reinforcement (policy intervention) of regulation and punishment for fishing boats, and the strategizing directions were analyzed. Until now, regulations and punishments on fishing boats have been conducted temporarily and short-term as a precautionary measure to prevent accidents and imposed penalties. However, due to various anomalous side effects, the expected results were not achieved, negligent accidents occurred constantly, and follow-up measures were repeated. Resultantly, the regulation and punishment of fishing boats is a reinforced safety standard, and there is a necessity to improve facilities, equipment, and industry, and develop technology (including time delay) to prevent accidents. However, as the negative (illegal) activities continue without immediate and significant resistance, the safety blind spot for accident prevention cannot be minimized. Thus, policy intervention based on linear thinking without sufficiently considering variables of the dynamic mechanism and time can distort the basic values pursued by the policy. For the regulation and punishment of fishing boats, a strategy to supplement the mechanism should be prepared prior to the preparation of reinforced safety standards. Improvement and development of related technologies, mandatory training hours for anglers, fishing industry, and related organizations, proposal of specific action plan for Fishing Management and Promotion Act for growing fishing-related industries.

• Journal of Navigation and Port Research
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• v.47 no.4
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• pp.246-255
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• 2023

Public conflicts in the port sector can cause additional social costs and delay the supply of port infrastructure, which can negatively affect local industries and national competitiveness. Although the importance of conflict management in the port sector is gradually increasing, there is still no systematic conflict management countermeasure. Therefore, in this study, the limitations of the current conflict management system in the port sector were considered, and a Delphi survey was conducted targeting experts and stakeholders in the port sector and conflict management. In addition, criteria for diagnosing conflicts in the port sector, causes of conflicts, proactive management measures, and ex post solutions were derived. The results of the Delphi survey analysis showed that the biggest causes of conflict were the absence of stakeholder opinion collection, consultation, and communication tools. Preliminary conflict management measures including a public deliberation process to collect local opinions and discuss development directions before deciding on specific issues, and ex post conflict resolution measures including investigation of causes of conflicts and objective personnel management in the process of preparing alternatives (e.g., securing reliability) were determined as the most important factors. In addition, based on the results obtained in this study, conflict management techniques for each phase of the port development project were presented. These findings are expected to be used as a useful reference material to reflect the port sector, which has not been included in the "Public Institution Conflict Management Manual (2016)" of the Office for Government Policy Coordination.

• Journal of KIISE:Software and Applications
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• v.29 no.12
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• pp.957-965
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• 2002

Garbage collection in the CLDC typically employs a stop-the-world GC algorithm which is performing a complete garbage collection when needed. This technique is unsuitable for the interactive Java embedded system because this can lead to long and unpredictable delays. In this paper, We present a garbage collection algorithm which reduces the average delay time and supports the interactive environment. Our garbage collector is composed of the allocator and the collector. The allocator determines the allocation position of free-list according to object size, and the collector uses an incremental mark-sweep algorithm. The garbage collector is called periodically by the thread scheduling policy and the allocator allocates the objects of marked state during collection cycle. Also, we introduce a color toggle mechanism that changes the meaning of the bit patterns at the end of the collection cycle. We compared the performance of our implementation with stop-the-world mark-sweep GC. The experimental results show that our algorithm reduces the average delay time and that it provides uniformly low response times.

• Journal of the Economic Geographical Society of Korea
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• v.15 no.4
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• pp.628-641
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• 2012

This research investigates a dynamic mechanism underlying the co-evolution between network and space by applying hype-curve model, typical phenomenon which shows how new technologies and ideas initially adapted in the society. This study analysis the knowledge intensive industry of digital contents using social network analysis (SNA) in terms of structural, spatial, and temporal aspects, year of 2000, 2005, and 2010 focused on Seoul area. First of all, network and space establish 'inter-feedback' as a result of evolution and differentiation process. Second, it happen temporal 'delay' through the learning process stage of 'peak of inflated expectation' and 'trough of disillusionment.' As a result, Seoul develops with the technology commercialized-orient strategy affect government policy. This trend changes to technology-oriented development in Seoul area in the late of 2000 established 'self-organization' with geographical proximity organizations through learning process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.11A
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• pp.1106-1112
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• 2007

As a demand for high speed uplink packet services increases, the WCDMA enhanced uplink, also known as high speed uplink packet access (HSUPA), has been specified in release 6 by 3GPP. This HSUPA will provide various types of multimedia services, such as real-time video streaming, gaming, VoIP, and FTP. Generally, the performance of HSUPA is dominated by scheduling policy. Therefore, it is required to design a scheduling algorithm considering the traffic characteristics to provide QoS guaranteed services in various traffic environments. In this paper, we propose a scheduling algorithm considering the traffic characteristics to guarantee QoS in a mixed traffic environment. Finally, the performance of the proposed scheduling algorithm is evaluated in terms of average packet delay, packet delay jitter, and system throughput using a system level simulator.

• Journal of Communications and Networks
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• v.15 no.5
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• pp.476-485
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• 2013

In this paper, the effective capacity of a multiple-input multiple-output (MIMO) system in two different cases with receive antenna selection (RAS) and transmit antenna selection (TAS) schemes is investigated. A closed-form solution for the maximum constant arrival rate of this network with statistical delay quality of service (QoS) constraint is extracted in the quasi-static fading channel. This study is conducted in two different cases.When channel state information (CSI) is not available at the MIMO transmitter, implementation of TAS is difficult. Therefore, RAS scheme is employed and one antenna with the maximum instantaneous signal to noise ratio is chosen at the receiver. On the other hand, when CSI is available at the transmitter, TAS scheme is executed. In this case, one antenna is selected at the transmitter. Moreover, an optimal power-control policy is applied to the selected antenna and the effective capacity of the MIMO system is derived. Finally, this optimal power adaptation and the effective capacity are investigated in two asymptotic cases with the loose and strict QoS requirements. In particular, we show that in the TAS scheme with the loose QoS restriction, the effective capacity converges to the ergodic capacity. Then, an exact closed-form solution is obtained for the ergodic capacity of the channel here.

• Journal of Convergence Society for SMB
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• v.2 no.2
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• pp.35-41
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• 2012

The rapid development of cloud computing and mobile internet service changes to an mobile cloud service environment that can serve and pay computing source that users want anywhere and anytime. But when user misses mobile device, the respond to any threat like user's personal information exposal is insufficient. This paper proposes cloud service access control model to provide secure service for mobile cloud users to other level users. The proposed role-based model performs access authority when performs user certification to adapt various access security policy. Also, the proposed model uses user's attribute information and processes before user certification therefore it lowers communication overhead and service delay. As a result, packet certification delay time is increased 3.7% and throughput of certification server is increased 10.5%.

• Korean Journal of Construction Engineering and Management
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• v.13 no.1
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• pp.148-159
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• 2012

Recently construction companies' capital condition has been aggravated due to low profit, fierce competition and market contraction. For this reason, the companies rely on public construction projects that protect construction fee by regulations. Despite these regulations, problems regarding progress payment are constantly happening. Also, insufficient analysis on interaction between contractors makes policy making difficult. Thus, in this study, interaction between contractors are quantitatively determined according to delay of application and payment based on current public construction regulations on construction stage. A system dynamics model is used, which analyzes the problems based on an interaction between contractors, and solutions for progress payment application and payment delay are suggested according to the research results.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.3
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• pp.66-75
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• 2017

Priority disciplines are an important scheme for service systems to differentiate their services for different classes of customers. (N, n)-preemptive priority disciplines enable system engineers to fine-tune the performances of different classes of customers arriving to the system. Due to this virtue of controllability, (N, n)-preemptive priority queueing models can be applied to various types of systems in which the service performances of different classes of customers need to be adjusted for a complex objective. In this paper, we extend the existing (N, n)-preemptive resume and (N, n)-preemptive repeat-identical priority queueing models to the (N, n)-preemptive repeat-different priority queueing model. We derive the queue-length distributions in the M/G/1 queueing model with two classes of customers, under the (N, n)-preemptive repeat-different priority discipline. In order to derive the queue-length distributions, we employ an analysis of the effective service time of a low-priority customer, a delay cycle analysis, and a joint transformation method. We then derive the first and second moments of the queue lengths of high- and low-priority customers. We also present a numerical example for the first and second moments of the queue length of high- and low-priority customers. Through doing this, we show that, under the (N, n)-preemptive repeat-different priority discipline, the first and second moments of customers with high priority are bounded by some upper bounds, regardless of the service characteristics of customers with low priority. This property may help system engineers design such service systems that guarantee the mean and variance of delay for primary users under a certain bounds, when preempted services have to be restarted with another service time resampled from the same service time distribution.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.2A
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• pp.55-62
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• 2003

This paper proposes an efficient and differentiated MAC scheduling algorithm for Bluetooth systems. The proposed algorithm guarantees QoS (Quality of Service) requirement of each master-slave pair or application. Conventional MAC scheduling algorithms for Bluetooth take priority of each pair into consideration and demonstrate relatively reasonable performance. However, their performances may depend on traffic characteristic, or they are limited by overheads for signaling. In this paper, we propose a new MAC scheduling algorithm superior to the conventional algorithms from the viewpoints of throughput, delay, and supporting QoS. Our proposed algorithm is evaluated via computer simulations under various environments and compared with the conventional scheduling algorithms. Simulation results indicate that the proposed algorithm shows better performance than the existing algorithms, and can support the QoS demand of each pair.