• Journal of Korea Multimedia Society
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• v.13 no.5
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• pp.740-753
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• 2010

Performance of TCP can be severely degraded in WLP-based Mobile IP wireless networks where packet loss not related to network congestion occurs frequently during WLP-based inter-subnetwork handoff by user mobility. To resolve such a problem in the networks using WLP-based Mobile IP, the packet buffering method recovering seamlessly the packets dropped due to user mobility has been proposed. The packet buffering method at a bridge station recovers those packets dropped during handoff by forwarding buffered packets at the old bridge station to the WLP device. But, when the WLP device moves to a congested bridge station in a new WLP foreign subnetwork, those buffered packets forwarded by the old bridge station are dropped and TCP transmission performance of a WLP device in the congested bridge station degrades due to increased congestion by those forwarded burst packets. In this paper, a PBM(Packet Bridge Marker) is proposed for preventing buffered out-of-profile(OUT) packets from reducing the throughput of in-profile(IN) packets of an Assured Service WLP device. From this operation, the packet losses of buffered OUT packets are avoided and the throughput of IN and Total packets of an AS WLP device are increased.

• Journal of Conservation Science
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• v.5 no.1 s.5
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• pp.20-40
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• 1996

For obtaining the basic data for establishing plan on the conservation of the Gameunsa 3-story and Naweonri 5-story Pagodas located at the Kyeongju city, the characteristics of the rock and weathering phenomena have been investigated. The former consists of quartz-rlch granite containing small amount of biotite, and the latter of alkali granite with abundant perthite, These rock phases are nearly identical to the marginal phase of medium-grained hornblende-biotite granodiorite and alkali granite respectively, which are distributed around the Kyeongju city. The rock weathering may be governed mainly by chemical weathering of feldspar following physical segregation of quartz grains and pervasive moss. The feldspar easily dissolve In the solution with pH<7 to precipitate clay mineral such as a kaolinite as a secondary phase on the feldspar surface. However, the chemical weathering of feldspar may continue when the surface is washed by the rain according to removal of the reprecipitated phase. On forwarding, the weathering may be greatly Influenced by the acid rain. Exfoliation and weathering along igneous lineation resulting in exfoliating along the structural line are the characteristic weathering phenomena. Also the secondary small cracks are irregularly developed on the rocks due to different strain on places by the overall structural unbalance of the pagodas. Along these cracks, the rain water intrudes deeply into the rocks and weathering occurs intensively compared to other parts. Weathering may be artificially promoted by the grinding or sculpturing when the pagodas were made. Because it may influence on the physical properties of the rocks as well as destruct the surface of the feldspar crystals, the major constituents of the rocks, it results in providing the environment of easy chemical weathering along time. For conservation, the pagodas must be structurally balanced by compacting the soil basement and supplementing rocks on the destroyed part. On the exfoliated part it is better not to be artifically treated as using cementing material. But the cracks may be filled up by cementing material to avoid the intrusion of acidic water. To supplement the rocks on the destroyed part, it may be better to use similar rock phases from identical biotite granite and alkali granite masses around the Kyeongju city.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5B
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• pp.475-488
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• 2003

To prevent performance degradation of TCP due to packet losses in the smooth handoff by the route optimization extension of Mobile IP protocol, a buffering of packets at a base station is needed. A buffering of packets at a base station recovers those packets dropped during handoff by forwarding buffered packets at the old base station to the mobile user. But, when the mobile user moves to a congested base station in a new foreign subnetwork, those buffered packets forwarded by the old base station are dropped and TCP transmission performance of a mobile user in the congested base station degrades due to increased congestion by those forwarded burst packets. In this paper, considering the general case that a mobile user moves to a congested base station, we analyze the influence of packet buffering on TCP performance according to handoff arrival distribution for Drop-tail and RED (Random Early Detection) buffer management schemes. Simulation results show that RED scheme can reduce the congestion increased by those forwarded burst packets comparing Drop-Tail, but RED scheme cannot avoid Global Synchronization due to forwarded burst packets by the old base station and new buffer management scheme to avoid it is needed in Mobile IP based networks.

• Journal of the Korea Safety Management & Science
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• v.21 no.4
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• pp.75-80
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• 2019

Sales of the Korean clothing industry grew to 16.9 percent on-year in 2010, but the growth rate dropped to 3 percent from 2011 to 2016 and the overall market began to slump to 1.1.6 percent in 2017. The competitiveness of clothing companies is also a major sector in logistics capability, and the average logistics cost of domestic clothing companies is 8.3 percent of sales in 2011, higher than the average 8 percent of domestic industries, and 36.4 percent of the total storage cost in 2011, higher than the 28.8 percent share of the total storage cost of domestic companies. As domestic production conditions such as wage hikes and labor disputes worsened in the 1990s, production facilities were rapidly moved overseas, which led many clothing companies to have no production facilities or a minimal production base in Korea and focus on marketing and design capabilities. The total storage capacity and storage efficiency of the logistics center became very important as the products were changed to the form of mass warehousing and small-volume forwarding. Research shows that building column spacing, a model of this research, can affect the amount of hanger rack storage empirically, so for sustainable growth of clothing companies, it is necessary to improve competitiveness in the logistics market by reducing costs and improving efficiency to overcome difficulties in corporate management. Because logistics costs are 8.3 percent and operating profit to sales ratio is 2 percent, it is expected that operating profit will increase by 41.5 percent if logistics costs are reduced by 10 percent. If 10% of storage cost is saved based on storage cost, operating profit is expected to increase by 15% To strengthen the competitiveness of the clothing industry, a reduction in logistics costs is essential. Therefore, the purpose of this study is to provide hints that logistics experts can have empirically small amounts in reducing storage costs through column spacing adjustment of logistics centers that have not been dealt with statistically until now, and to contribute to the continued growth of clothing companies and the development of the domestic logistics industry.

• Journal of Korean Medical classics
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• v.13 no.1
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• pp.184-232
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• 2000

The trend of the concept for modern medicine is gradually forwarding to preventive medicine from therapeutic medical science. One of the most remarkable characteristics of oriental medicine is that it attaches greater importance to preventive medicine scientifically. The basic theory of oriental medicine principally takes roots in Huang Di Nei Jing and it is Si Qi Tian Shen Da Lun that is deep-rooted in the principle of "growing life" grounded in theory of unity of heaven and man of oriental medicine. Therefore having translated annotation of 〈Si Qi Tian Shen Da Lun·Huang Di Nei Jing Su Wen〉 which is quoted frequently and using it for appendix and comparing each views of annotators, I would like to state the results of dissertation as below. 1. Si Qi Tian Shen of title of the paper means that it keeps our health and prevent diseases in advance to control our mind and rhythm of life to the change of Yin and Yang - that is, the grower Yin, the looser Yang - following four seasons of nature environment. 2. The summary of this dissertation is that spring means things newly sprout from old ones, things become profuse, beautiful and brilliant in the summer. Autumn stands for things is harvested and allocated evenly and finally things is closed and stored. That is, in the spring and summer. If one break this principle of growth, diseases are followed after this. Therefore an excellent physician should handle diseases before they are attacked not remedy them after outbreak of diseases. It is said that a sage governs the nation before it is put into confusion. 3. These four terms standing for each season describe definitely and realistically rural life in the agricultural environment, in other words, spouting in spring, growing in summer, harvesting in autumn, storing in winter. Going with the current of the times, they have developed to theoretical concept of getting, growth, harvest, store so that implied the principle of growth for four seasons. 4. It means in a concrete way "Yang would grow in the spring and summer and Yin would grow in autumn and winter" as follow. That is, when the day is long, things act energetically and emit the warmth of life and expand the vigor of growth. On the other hand, when the night is long, things lessen their activity to protect the warmth of life and to preserve the sprit of growth. In addition, we should be concerned about the work outward and try to concretely fulfill plan of business in spring and summer. It is in autumn and winter when we should grow Yin. It does not mean that we simply grow cold yin in our body to build Yin. But according to annotators, for example, Wang Bing stated that we need to make things be cool in spring and summer, and be warm in autumn and winter for improvement. Zhang Jie Bin noted that things should not be cold in spring and summer and not be too hot to improve in autumn and winter. Those principles theorized to unify physiological status into the principle of changing of Yang and Yin in the nature and enriched the contents. In these principles, no problems are not found logically somewhat.

• Journal of Korea Port Economic Association
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• v.26 no.2
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• pp.1-18
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• 2010

With the maturity and fierce competition of domestic logistics market, Korea government is actively working on the overseas investments in global logistics market after establishing the basic plan since 2006. In particular, India is selected one of promising countries for logistics investments since it has more 1.1 billion people and is regarded as post-China. In fact, a number of global logistics enterprises have started their businesses in the logistics market of India so that the competition already started. In this regard, it is highly necessary to find out feasible investment projects and then detemin the priority of the alternatives for successful investments. Therefore this study proposes a fuzzy-based AHP model by which the overseas investment problem was systematically structured and then evaluated. The model was established by exploiting a fuzzy theory and AHP for capturing the inexactness and vagueness of information. The results show that the investment of port operations is the number one priority in the India's logistics market and ODCY operations, road transportations, forwarding operations, inland depot operations in order. Finally the proposed model will help Korea's policy makers to have a better reliable investment strategy.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.1
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• pp.35-40
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• 2011

In this paper, we compare and analyze data aggregation methods based on event area in wireless sensor networks. Data aggregation methods consist of two methods: the direct transmission method and the aggregation node method. The direct aggregation method has some problems that are data redundancy and increasing network traffic as all nodes transmit own data to neighbor nodes regardless of same data. On the other hand the aggregation node method which aggregate neighbor's data can prevent the data redundancy and reduce the data. This method is based on location of nodes. This means that the aggregation node can be selected the nearest node from a sink or the centered node of event area. So, we describe the benefits of data aggregation methods that make up for the weak points of direct data dissemination of sensor nodes. We measure energy consumption of the existing ways on data aggregation selection by increasing event area. To achieve this, we calculated the distance between an event node and the aggregation node and the distance between the aggregation node and a sink node. And we defined the equations for distance. Using these equations with energy model for sensor networks, we could find the energy consumption of each method.

• Journal of Navigation and Port Research
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• v.37 no.6
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• pp.699-707
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• 2013

With the increase in the trade volume between countries, the market of freight forwarders industry has been gradually growing. However, not only in Korea, with the number of global freight forwarders increasing, global competition has been increasingly fierce, and domestic freight forwarders are facing enormous challenges, therefore, the relevant policy sectors have carried out a series of supportive policies, while academics have conducted various researches. But most of them have focused on the current situation or the business model, and they could not get feedback on government support policies from enterprises. Using the AHP analysis, this study decided the priority of the government's ongoing supporting policies, compared the cognitive differences among of the companies of 3 different sizes, which was further verified using t-test. Then we compared the government support policies with the actual expectations of the companies to see if they matched on the basis of the previous results of this study, in order to help to strengthen the competitiveness of our freight forwarding industry.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.12
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• pp.455-462
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• 2016

Wireless sensor networks have been researched to gather data about events on sensor fields from sources at sinks. Multipath routing is one of attractive approaches to reliably send data against the problem of frequent breakages on paths from sources to sinks due to node and link failures. As mobile events such as humans, animals, and vehicles are considered, sources may be continuously generated according to the movement of the mobile event. Thus, mobile events provide new challenging issue in multipath routing. However, the research on multipath routing mainly focus on both efficient multipath construction from sources to static sinks and fast multipath reconstruction against path breakages. Accordingly, the previous multipath routing protocols request each source continuously generated by a mobile event to construct individual multipath from the source to sinks. This induces the increase of multipath construction cost in the previous protocols in proportion to the number of source. Therefore, we propose efficient multipath routing protocol for supporting continuous sources generated by mobile events. In the proposed protocol, new source efficiently reconstructs its multipath by exploiting the existing multipath of previous sources. To do this, the proposed protocol selects one among three reconstruction methods: a local reconstruction, a global partial one, and a global full one. For a selection decision, we provide an analytical energy consumption cost model that calculates the summation of both the multipath reconstruction cost and the data forwarding cost. Simulation results show that the proposed protocol has better performance than the previous protocol to provide multipath routing for mobile events.

• Journal of KIISE:Information Networking
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• v.36 no.5
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• pp.413-424
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• 2009

Wireless sensor network is based on an event driven system. Sensor nodes collect the events in surrounding environment and the sensing data are relayed into a sink node. In particular, when events are detected, the data sensing periods are likely to be shorter to get the more correct information. However, this operation causes the traffic congestion on the sensor nodes located in a routing path. Since the traffic congestion generates the data queue overflows in sensor nodes, the important information about events could be missed. In addition, since the battery energy of sensor nodes exhausts quickly for treating the traffic congestion, the entire lifetime of wireless sensor networks would be abbreviated. In this paper, a new congestion control method is proposed on the basis of genetic algorithm. To apply genetic algorithm, the data traffic rate of each sensor node is utilized as a chromosome structure. The fitness function of genetic algorithm is designed from both the average and the standard deviation of the traffic rates of sensor nodes. Based on dominant gene sets, the proposed method selects the optimal data forwarding sensor nodes for relieving the traffic congestion. In experiments, when compared with other methods to handle the traffic congestion, the proposed method shows the efficient data transmissions due to much less queue overflows and supports the fair data transmission between all sensor nodes as possible. This result not only enhances the reliability of data transmission but also distributes the energy consumptions across the network. It contributes directly to the extension of total lifetime of wireless sensor networks.