• Journal of Korea Multimedia Society
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• v.15 no.12
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• pp.1456-1463
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• 2012

In this paper, we study the ON/OFF control policy of base stations in two-tier heterogeneous cellular networks to minimize the total power consumption of the system. Using heterogeneous cellular networks is a potential approach of providing higher throughput and coverage compared to conventional networks with only macrocell deployment, but in fact heterogeneous cellular networks often operates regardless of total power consumption, which is a very important issue of modern cellular networks. We propose a policy that controls the activation/deactivation of base stations in heterogeneous cellular networks to minimize total power consumption. Under this policy, the total power consumed can be significantly reduced when the traffic is low while the QoS requirement is satisfied.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.53 no.6
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• pp.324-333
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• 2004

This paper discusses the development of an educational web-based power flow program for undergraduate students. The interaction between lectures and users can be much enhanced via the web-based programs which result in the student's learning effectiveness on the power flow problem. However the difficulties for developing web-based application programs are that there can be the numerous unspecified users to access the application programs. To overcome the aforementioned multi-users problem and to develope the educational web-based power flow program, we have revised the system architecture, the modeling of application programs, and database which efficiently and effectively manages the complex data sets related to the power flow analysis program. The developed application program is composed of the physical three tiers where the middle tier is logically divided into two kinds of application programs. The divided application programs are interconnected by using the Web-service based on XML (Extended Markup Technology) and HTTP (Hyper Text Transfer Protocol) which make it possible the distributed computing technology Also, this paper describes the method of database modeling to handle effectively when the numerous users change the parameters of the power system to compare the results of the base case.

• Journal of Korea Port Economic Association
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• v.24 no.1
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• pp.41-60
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• 2008

Korea has been doing a two-port system as a main port development policy and developing the port of Busan and Gwangyang as the transshipment hubs in the northeast Asia. However, the growth rate of the transshipment container volume of the Gwangyang port in 2007 was sharply dropping more than 31.4%. The reasons why reduced the growth rate of transshipment cargo were from the port development in north China and the direct callings of ships. Therefore, it is time to evaluate the transshipment hub port policy of Korea. This study would recognize the decision criteria of shipping companies as customers for the transshipment hub in the northeast Asia by the AHP methodology based on Lirn et al. (2004). It has been known the costs of shipping companies and port location as the main first tier criteria for transshipment ports, and container handling charges, closeness to the main navigation route, carriers' strategy, and nearness to the feeder ports as the important second tier factors. Finally, the domestic terminal operating companies would focus on only a few attributes including the terminal cost factor, but the international shipping companies would be considering more several factors than they do. Therefore, the transshipment port strategy should be enriched in the near future.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.12 no.2
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• pp.89-100
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• 2002

In this paper, we propose a group key management architecture for the secure group communications in mobile netwowrks and authenticated key agreement protocol for this system. Most of existing group key management schemes un certificates based on the public key for the purpose of user authentication and key agreement in secure fashion however, we use the ICPK(Implicitly Certified Public key) to reduce the bandwidth for a certificate exchanging and to improve a computational efficiency. In this architecture, we use two-tier approach to deal with key management where the whole group is divided into two parts; the first is a cell groups consisted of mobile hosts and another is a control group consisted of cell group managers. This approach can provide flexibility of key management such that the affection for a membership change is locally restricted to the cell group which is an autonomous area of the CGM(Cell Group Manager).

• Journal of Communications and Networks
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• v.17 no.1
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• pp.58-66
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• 2015

Aeronautical communication networks (ACN) is an emerging concept in which aeronautical stations (AS) are considered as a part of multi-tier network for the future wireless communication system. An AS could be a commercial plane, helicopter, or any other low orbit station, i.e., Unmanned air vehicle, high altitude platform. The goal of ACN is to provide high throughput and cost effective communication network for aeronautical applications (i.e., Air traffic control (ATC), air traffic management (ATM) communications, and commercial in-flight Internet activities), and terrestrial networks by using aeronautical platforms as a backbone. In this paper, we investigate the issues about connectivity, throughput, and delay in ACN. First, topology of ACN is presented as a simple mobile ad hoc network and connectivity analysis is provided. Then, by using information obtained from connectivity analysis, we investigate two communication models, i.e., single-hop and two-hop, in which each source AS is communicating with its destination AS with or without the help of intermediate relay AS, respectively. In our throughput analysis, we use the method of finding the maximum number of concurrent successful transmissions to derive ACN throughput upper bounds for the two communication models. We conclude that the two-hop model achieves greater throughput scaling than the single-hop model for ACN and multi-hop models cannot achieve better throughput scaling than two-hop model. Furthermore, since delay issue is more salient in two-hop communication, we characterize the delay performance and derive the closed-form average end-to-end delay for the two-hop model. Finally, computer simulations are performed and it is shown that ACN is robust in terms of throughput and delay performances.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.4
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• pp.1302-1320
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• 2015

In cloud, everything can be provided as a service wherein a large number of users submit their jobs and wait for their services. hus, scheduling plays major role for providing the resources efficiently to the submitted jobs. The brainwave of the proposed ork is to improve user satisfaction, to balance the load efficiently and to bolster the resource utilization. Hence, this paper roposes an Adaptive Multilevel Scheduling System (AMSS) which will process the jobs in a multileveled fashion. The first level ontains Preprocessing Jobs with Multi-Criteria (PJMC) which will preprocess the jobs to elevate the user satisfaction and to itigate the jobs violation. In the second level, a Deadline Based Dynamic Priority Scheduler (DBDPS) is proposed which will ynamically prioritize the jobs for evading starvation. At the third level, Contest Mapping Jobs with Virtual Machine (CMJVM) is roposed that will map the job to suitable Virtual Machine (VM). In the last level, VM Scheduler is introduced in the two-tier VM rchitecture that will efficiently schedule the jobs and increase the resource utilization. These contributions will mitigate job iolations, avoid starvation, increase throughput and maximize resource utilization. Experimental results show that the performance f AMSS is better than other algorithms.

• Korean Journal of Social Welfare
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• v.48
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• pp.7-41
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• 2002

This paper analyses the proposals contained in the British Government Green Paper, A New Contract for Welfare: Partnership in Pensions for low paid workers and the potential of the new rules to guarantee a decent income in old age. The UK pension system is a partnership between the State(providing the basic state pension and the SERPS), employers(providing occupational pension scheme) and private pension providers(providing personal pensions). Although the system needs to change, this partnership remains the right foundation. However, the pension Green Paper proposes substantial changes to second tier pension provision in the UK. In particular, the Government plans to replace the SERPS with a new State Second Pension. According to the Green Paper, this will result in "dramatically better pension provision for those earning less than ${\pounds}9,000$ a year" and through increased payments to private pension schemes, will also provide "extra help to those on middle incomes(${\pounds}9,000-{\pounds}18,500$ a year). Therefore, it discusses the general principles inherent in the design of the British pension system and analyses the balance of these principles is represented in the Green Paper. The paper then examines how the Government's proposals protect individuals from a means-tested old age. This paper finds that the Green paper's proposals add up to reinventing a new two-stage basic pension. However, two key features of a such a basic pension package are missing- an 'adequate' level of payment and comprehensive entitlement. Because of these missing principles we argue that the Green Paper's proposals incorporate for the low paid. The income from the basic pension and the secondary pension which is so near the means-tested minimum that little is gained in retirement from a lifetime of work and contribution. Indeed, the shift away from collective provision and the emphasis on individual responsibility will reinforce this inequality, so that many poor will continue to experience poverty in later life.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.4
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• pp.412-417
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• 2015

The IMO MEPC has been increasingly strengthening the emission standard for marine environment protection. In particular, nitrogen oxide (NOx) emissions of all ocean-going ships built from 2016 will be required to comply with the Tier-III regulation. In this study, a vanadia based SCR (Selective Catalytic Reduction) system developed for ship application was installed on a diesel engine for power generation of the training ship T/S SAENURI in Mokpo National Maritime University. For the present study, the exhaust pipeline of the generator diesel engine was modified to fit the urea SCR system. This study investigated the NOx reduction performance according to the two kind of injection method of urea solution (40%): Auto mode through the PLC (Programable Logic Control) and Manual mode. We were able to find the ammonia slip conditions when in manual mode method. So, the optimal urea injection quantity can be controlled at each engine load (25, 35, 50%) condition. It was achieved 80% reduction on nitrogen oxide. Furthermore, we found that the NOx reduction performance was better with the load up-down (while down to 25% from 50%) than the load down-up (while up to 50% from 25%) test.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.06a
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• pp.30-33
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• 2003

In this paper the advantage of web technology applied to Rapid Prototyping is discussed. Two fabrication processes are chosen to be web-enabled. One, a post-process of FDM is developed to provide translucent plastic parts made of medical grade ABS material. The other, a system to fabricate laser machined Light Guide Panel is developed. In order to show the timesaving characteristics of the web-based tools, two websites are implemented (http://nano.gsnu.ac.kr/fdm ＆ http://nano.gsnu.ac.kr/laser). The 3-tier architecture is applied for the Internet communication between designers and manufacturing sites, The integrated design tools and physical manufacturing processes enable designers to submit a new design and to receive the fabricated parts in an expedited manner. Example parts are fabricated using the web-based system to prove the concept of the web-based design and Rapid Prototyping.

• Journal of Life Science
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• v.16 no.5
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• pp.750-758
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• 2006

Calcium-binding protein calretinin is thought to play important roles in calcium buffering. Recently, we reported on the distribution, morphology of calretinin-immunoreactive (IR) neurons and the effects of eye enucleation on the immunoreactivity of calretinin in the superficial layers of the hamster superior colliculus (SC). In the present study, we describe the distributions and types of labeled cells and effects of enucleation in the deeper layers by immunocytochemistry. We also compare this labeling to that of GABA, the major inhibitory neurotransmitter in the central nervous system. In contrast to the superficial layers, the deeper layers contained many calretinin-IR neurons which formed two tiers. The first tier, which was very distinctive, was found within the intermediate gray layer. The second tier was found in the deep gray layer. Labeled neurons varied dramatically in morphology and included vertical fusiform, stellate, round/oval, and horizontal neurons. In contrast to the superficial layers, enucleation appeared to have no effect on the distribution of calretinin immunoreactivity in the deeper layers. Two-color immunofluorescence revealed that none of calretinin-IR neurons were labeled with an antibody to GABA. The present results demonstrate that calretinin identifies unique neuronal sublaminar organizations in the hamster SC. The present results also demonstrate that none of the calretinin-IR neurons in the hamster SC is GABAergic interneurons. As many calretinin-IR cells are GABAergic interneurons in most other brain areas, this phenomenon in hamster SC is exceptional.