• The Journal of Korean Institute of Communications and Information Sciences
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• v.39B no.7
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• pp.425-432
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• 2014

This paper proposes a wear-leveling algorithm that exploits the properties of SSD memories with multi-channel and multi-way architecture. When a write request arrives, the proposed algorithm classifies the stored data in DRAM buffer into hot or cold according to logical address access frequency, and performs data allocation to reduce deviation of block erase counts. It lowers the chance of increasing erase count by allocating cold data to blocks which have high erase count. Effectiveness of the proposed algorithm is verified by executing various applications on a multi-channel, multi-way SSD simulator. Experimental results show that differences in erase count among blocks is reduced by an average of 9.3%, and total erase count decreases by 4.6%, when compared to previous wear-leveling algorithm.

• The Journal of Fisheries Business Administration
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• v.32 no.2
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• pp.51-72
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• 2001

This study intends to review the development of Squid Angling Fisheries of Korea and Japan and subsequent changes in the fisheries regime as well as management conditions and to examine reorganization directions. Although catches and productivity are all increasing in Korea and Japan as the squid resource in the East Sea is improving, the number of fishing vessels and the conditions of fisheries management are showing a symmetrical relationship. The former is increasing in Korea and decreasing in Japan while the latter is aggravating in Korea and rather stable in Japan. And while the competition between the two countries for more fishing grounds and catches are not that serious since the resource is relatively increasing, the catch and price competition with other domestic fisheries is a more significant problem. Furthermore, even though light restriction is implemented in both countries in order to suppress over-competition, it is adopted as a means to curtail management costs and block over-investment rather than to adjust international or inter-fisheries circumstances. Japan has been implementing the TAC system on squid resources since 1998. However, it has a different meaning than as a resource management method in its original sense because it is based on the highest catch level of the past and takes into consideration the fishermen's management conditions. In case of Korea, it is necessary to establish a plan to strengthen its fisheries management competence to address its shrinking catch in the Japanese waters. The developments mentioned so far have appeared amidst the increase of squid resources, and if such conditions disappear, problems such as international allocation of catches and fishing seasons, access to fishing grounds, and domestic conflicts among different fisheries will emerge.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.106-114
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• 2020

It is very important for beginners in networking to build, test, and operate an IP network system, which is the key infrastructure of the fourth industrial revolution. An IP network system consists of the IP network itself, covering both the internet and underlying layers, plus the basic network system supporting fundamental network services, with a DNS, the DHCP, email, WWW, and application service systems, such as VoIP. This paper suggests an open software-based practice platform with a minimal network configuration on which beginners can practice on nearly all of the IP network system, and it presents a practice scenario and results. In addition, it adds both IP address allocation and routing table manipulation functions to the network simulator software, which will allow beginners to learn table-based datagram routing schemes in advance. This platform may be useful for networking beginners in order to practice on an IP network system on their own personal computers without additional equipment and costs.

• Journal of KIISE:Computing Practices and Letters
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• v.9 no.5
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• pp.578-587
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• 2003

The DSTM (Dual Stack Transition Mechanism), one of tunneling mechanism, is considered as the best solution in IPv4/IPv6 transition recently. The DSTM provides a method to assure IPv4/v6 connectivity based on 4over6 (IPv4-over-IPv6) tunneling and temporal allocation of a global IPv4 address to a host requiring such communication. A TEP (Tunnel End Point) operates as a border router between IPv6 domain and IPv4 Internet, which performs encapsulation and decapsulation of 4over6 tunneling packets to assure hi-directional forwarding between both networks. In this paper, we analyze basic standards of the IPv6 protocol. And, we design and implement a DSTM TEP daemon block. The TEP daemon analyzes a fevers tunneling packet that is forwarded by the DSTM node, establishes the TEP's 4over6 interface, and supplies communication between a DSTM and a IPv4-only node. Finally, we construct a DSTM testbed and measure performance of the DSTM TEP. Our observation results show that performance of TEP supports the DSTM service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.4
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• pp.229-239
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• 2013

Recently, device-to-device (D2D) communications have been highlighted to improve the spectral efficiency and offer various user experiences in cellular networks. In this paper, we survey standards and literatures related to the D2D technology and address various advantages of D2D technology, and the problems to be resolved before practically implemented. Especially, by considering an important interference issue between cellular and D2D links, five resource allocation and interference management scenarios are provided and their performances are evaluated through the system level simulations. The simulation results show that the use of D2D significantly improve the cell capacity and the D2D user rate due to the effects of frequency reuse and data off-loading. Notably, it is also shown that an optimal D2D communication range exists to maximize the system performance.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.6A
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• pp.420-425
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• 2012

A forward error correction (FEC) coding techniques is one of time diversity techniques with which the effect of channel impairments due to noise and fading are spreaded over independently, and thus the performance could be improved. Therefore, the performance of the FEC scheme can be maximized if we minimize the correlation of channel information across over a codeword. In this paper, we propose a block turbo code with the maximized time diversity effect which may be reduced due to utilization of high order modulation schemes and due to transmission over a comparatively fast fading environment. Especially, we propose a very simple formula to calculate the address of coded bit allocation, and thus we do not need any additional outer interleavers, i.e., inter-codeword interleavers. The simulation resuts investigated in this paper reveal that the proposed scheme can provide the performance gain of more than a few decibels compared to the conventional schemes.

• Journal of Digital Contents Society
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• v.4 no.2
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• pp.127-137
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• 2003

A Web crawler is an important Internet software technology used in a variety of Internet application software which includes search engines. As Internet continues to grow, implementations of high performance web crawlers are urgently demanded. In this paper, we study how to support dynamic scheduling for a multiprocess-based web crawler. For high performance, web crawlers are usually based on multiprocess in their implementations. In these systems, crawl scheduling which manages the allocation of web pages to each process for loading is one of the important issues. In this paper, we identify issues which are important and challenging in the crawl scheduling. To address the issue, we propose a dynamic crawl scheduling framework and subsequently a system architecture for a web crawler with dynamic crawl scheduling support. This paper presents the design of the Web crawler with dynamic scheduling support.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.4
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• pp.64-72
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• 2003

A Web crawler is an important Internet software technology used in a variety of Internet application software which includes search engines. As Internet continues to grow, implementations of high performance web crawlers are urgently demanded. In this paper, we study how to support dynamic scheduling for a multiprocess-based web crawler. For high peformance, web crawlers are usually based on multiprocess in their implementations. In these systems, crawl scheduling which manages the allocation of web pages to each process for loading is one of the important issues. In this paper, we identify issues which are important and challenging in the crawl scheduling. To address the issue, we propose a dynamic crawl scheduling framework and subsequently a system architecture for a web crawler with dynamic crawl scheduling support. And we analysed the behaviors of Web crawler. Based on the analysis result, we suggest the direction for the design of high performance Web crawler.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.14 no.5
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• pp.1284-1294
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• 2010

The ZigBee is one of the most important technologies for composing USN. It is one of the IEEE 802.15.4 standards to support personal area networks. It uses a hierarchical routing or an on-demand route discovery strategy as an address allocation method. A hierarchical routing doesn't use a routing table but only uses a child node or a parent node as an intermediate node for data delivery. Therefore, the ZigBee network's topology greatly affects the overall network performance. In this paper, we propose a more trustworthy algorithm than only using the depth and widely variable LQI during network formation, and moreover we propose an algorithm to measure network's trustworthiness. We simulate our algorithm using the NS-2 and implement our network using the MG2400 ZigBee module for verifying performance.

• Journal of Climate Change Research
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• v.9 no.4
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• pp.453-460
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• 2018

The purpose of this study is to analyze the potential quantity of Korean Offset Credits (KOC) resulting from Certified Emission Reductions (CER) in 98 domestic Clean Development Mechanism (CDM) projects that were registered with the United Nations Framework Convention on Climate Change (UNFCCC) as of the end of 2016. Our results show that the total amount of potential KOC is 62,774 kt CO2eq. The potential KOC is only 23.4% of the total CER Issuance. During the first phase, this will be 3.2% of the allocated volume. This is because many projects are related to Renewable Portfolio Standard (RPS), HFC-23, and adipic acid N2O. There is a strong bias in some sectors and projects which could act as market distortion factors. Therefore, it is necessary to expand the target CDM project and activate non CDM offset projects. RPS projects bring fundamental changes to the energy sector, and it is worth reconsidering their acceptability. A wide variety of policy incentives are needed to address strong biases toward certain sectors and projects. The offset scheme has the advantage of allowing entities to reduce their GHG emissions cost effectively through a market mechanism as well as enabling more entities to participate in GHG reduction efforts both directly and indirectly. In contrast, having an inadequate offset scheme range and size might decrease the effort on GHG reduction or concentrate available resources on specific projects. As such, it is of paramount importance to design and operate the offset scheme in such a way that it reflects the situation of the country.