• Journal of Navigation and Port Research
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• v.41 no.3
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• pp.93-102
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• 2017

When VTSOs (Vessel Traffic Service Operator) determine the degree of collision risk for two vessels, they consider comprehensive information about each vessel's course, speed, DCPA, TCPA, and encountering situation. In this study, we proposed a utility function based on the risk attitudes of VTSOs toward the Risk Index (RI). The RI was calculated using the risk of encounter, the risk of approach, and the risk of time for two vessels in order to predict each ship's collision risk from the VTS viewpoint. We obtained each coefficient of the RI and the risk attitude through a survey of collision risks among VTSOs of Korea. In order to verify whether the proposed utility is reasonable, we validated by applying the degree of collision risk to some historical cases of accidents in Busan port along with the Ship of ES value($ES_S$) of ES(Environmental Stress) model.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.8
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• pp.3701-3727
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• 2016

Recently Service Function Chaining (SFC) is promising to innovate the network service mode in modern networks. However, a feasible implementation of SFC is still difficult due to the need to achieve functional equivalence with traditional modes without sacrificing performance or increasing network complexity. In this paper, we present a configurable network service chaining (CNSC) mechanism to provide services for network traffics in a flexible and optimal way. Firstly, we formulate the problem of network service chaining and design an effective service chain construction framework based on integrating software-defined networking (SDN) with network functions virtualization (NFV). Then, we model the service path computation problem as an integer liner optimization problem and propose an algorithm named SPCM to cooperatively combine service function instances with a network utility maximum policy. In the procedure of SPCM, we achieve the service node mapping by defining a service capacity matrix for substrate nodes, and work out the optimal link mapping policies with segment routing. Finally, the simulation results indicate that the average request acceptance ratio and resources utilization ratio can reach above 85% and 75% by our SPCM algorithm, respectively. Upon the prototype system, it is demonstrated that CNSC outperforms other approaches and can provide flexible and scalable network services.

• Journal of Information Technology Services
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• v.11 no.2
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• pp.107-118
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• 2012

Recently, as the clouding computing begins to receive a great attention from people all over the world, it became the most popular buzz word in recent IT magazines or journal and heard it in many different services or different fields. However, a notion of the cloud service is defined vaguely compared to increasing attentions from others. Generally the cloud service could be understood as a specific service model base on the clouding computing, but the cloud, the cloud computing, the cloud computing service and cloud service, these four all terms are often used without any distinction of its notions and characteristics so that it's difficult to define the exact nature of the cloud service. To explore and analyze the cloud service systematically, an accurate conception and scope have to be preceded. Therefore this study is to firstly clarify its definition by Delpi method using expert group and then tries to provide the foundation needed to enable relative research such as establishing business model or value chain and policies for its activation to set off. For the Delpi, 16 experts participated in several surveys from different fields such industry, academy and research sector. As a result of the research, Characteristics of the Cloud Service are followings : Pay per use, Scalability, Internet centric Virtualization. And the scope as defined including Grid Computing, Utility Computing, Server Based Computing, Network Computing.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.3 no.6
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• pp.575-596
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• 2009

Facing limited network resources such as bandwidth and processing capability, the Internet will have congestion from time to time. In this paper, we propose a scheme to maximize the total utility offered by the network to the end user during congested times. We believe the only way to achieve our goal is to make the scheme application-aware, that is, to take advantage of the characteristics of the application. To make our scheme scalable, it is designed to be class-based. Traffic from applications with similar characteristics is classified into the same class. We adopted the RED queue management mechanism to adaptively control the traffic belonging to the same class. To achieve the optimal utility, the traffic belonging to different classes should be controlled differently. By adjusting link bandwidth assignments of different classes, the scheme can achieve the goal and adapt to the changes of dynamical incoming traffic. We use the control theoretical approach to analyze our scheme. In this paper, we focus on optimizing the control on two types of traffic flows: TCP and Simple UDP (SUDP, modeling audio or video applications based on UDP). We derive the differential equations to model the dynamics of SUDP traffic flows and drive stability conditions for the system with both SUDP and TCP traffic flows. In our study, we also find analytical results on the TCP traffic stable point are not accurate, so we derived new formulas on the TCP traffic stable point. We verified the proposed scheme with extensive NS2 simulations.

• Journal of Korean Society of Forest Science
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• v.98 no.3
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• pp.297-304
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• 2009

Bukhansan National Park is facing dramatic increase of visitors since no entrance fee charge effected in January of 2007. This study was carried out to estimate socio-psychological carrying capacity of Bukhansan National Park based on marginal utility theory model, provide management tactics by stages. 512 visitors to Bukhansan National Park were surveyed during the October of 2008. The data analysis indicated that sociopsychological carrying capacity was estimated as approximately 65,000 people per day for Bukhansan National Park.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.1
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• pp.149-158
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• 2010

The domestic specialized coffee branch market is growing both in size and sales, and the competition between different brands is increasing. The goal of this study was to divide the customer's consumption motivations into utility usage motivation, hedonic usage motivation, and ostentation usage motivation and to determine how each motivation influences the attitude, satisfaction and loyalty toward the brand. The results can be summarized as follows. (1) Hedonic motivation and ostentation motivation with the exception of utility motivation were shown to have an effect on brand attitude. (2) Brand attitude was shown to have an effect on satisfaction and loyalty. (3) Satisfaction had an effect on loyalty. However, if the satisfaction was low, the intentions for subsequent visits and positive oral transmissions decrease. The result of this study showed that establishing positive brand attitude, satisfaction and loyalty to customers with pleasure and ostentation motivations is effective. Moreover, marketing activities such as cultural and playful events should be emphasized for customers with hedonic motivations, while environments with better atmosphere and careful service should be provided to customers with ostentation motivation.

• ETRI Journal
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• v.27 no.6
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• pp.777-787
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• 2005

In this paper, we propose an urgency- and efficiency-based wireless packet scheduling (UEPS) algorithm that is able to schedule real-time (RT) and non-real-time (NRT) traffics at the same time while supporting multiple users simultaneously at any given scheduling time instant. The UEPS algorithm is designed to support wireless downlink packet scheduling in an orthogonal frequency division multiple access (OFDMA) system, which is a strong candidate as a wireless access method for the next generation of wireless communications. The UEPS algorithm uses the time-utility function as a scheduling urgency factor and the relative status of the current channel to the average channel status as an efficiency indicator of radio resource usage. The design goal of the UEPS algorithm is to maximize throughput of NRT traffics while satisfying quality-of-service (QoS) requirements of RT traffics. The simulation study shows that the UEPS algorithm is able to give better throughput performance than existing wireless packet scheduling algorithms such as proportional fair (PF) and modified-largest weighted delay first (M-LWDF), while satisfying the QoS requirements of RT traffics such as average delay and packet loss rate under various traffic loads.

• KIPS Transactions on Computer and Communication Systems
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• v.1 no.3
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• pp.119-124
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• 2012

As an energy network infrastructure, which is capable of integrating energy related services such as AMR/AMI, Smart Grid, and Smart Water Grid, the Smart Utility Network (SUN) enables a paradigm shift from user-oriented networks to device-oriented networks. The SUN has some similarities to sensor networks in application and network requirements. Therefore it is required to investigate and analyze thoroughly existing related work in advance to design new network protocols for SUN. In this paper we analyze service requirements and design considerations for SUN and then present a design guideline of new network protocols for SUN by investigating existing low power protocols, data aggregation methods, and in-network storages.

• Journal of the Korean Society of Clothing and Textiles
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• v.29 no.11
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• pp.1475-1484
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• 2005

The purposes of this study were 1) to examine the dimension of fashion shopping mall attributes and shopping value related to online shopping, and 2) to investigate the effects of fashion shopping mall attributes and shopping value on purchase intention in online shopping. Data were obtained from 423 online fashion shopping mall consumers who have experiences of buying products or visiting to online fashion shopping mall in Busan, and were analyzed using by factor analysis, Cronbach's alpha, path analysis of LISREL 8.53. The results showed online fashion shopping mall attributes were composed of Visual information, Loading speed Space composition, Product assortment, Checkout service, and Help desk. Shopping value perceived by online fashion shopping mall consumers were consisted two factors: Hedonic value and Utility value. Hedonic value and Utility value Perceive by online consumers were influenced by Product assortment, Visual information, Help desk, and Space composition of shopping mall. Additionally, hedonic and utility shopping values perceive by online consumers impacted online purchase intention. Findings suggest that fashion shopping mall attributes mediated by shopping values are important in predicting purchase intention of online shopping mall. Implications are drawn for the information useful to consumer behavior researchers and retailers of online fashion shopping mall.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4848-4863
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• 2016

The explosive wireless data service requirement accompanied with carbon dioxide emission and consumption of traditional energy has put pressure on both industria and academia. Wireless networks powered with the uneven and intermittent generated renewable energy have been widely researched and lead to a new research paradigm called green communication. In this paper, we comprehensively consider the total generated renewable energy, QoS requirement and channel quality, then propose a utility based renewable energy allocation policy. The utility here means the satisfaction degree of users with a certain amount allocated renewable energy. The energy allocation problem is formulated as a constraint optimization problem and a heuristic algorithm with low complexity is derived to solve the raised problem. Numerical results show that the renewable energy allocation policy is applicable not only to soft QoS, but also to hard QoS and best effort QoS. When the renewable energy is very scarce, only users with good channel quality can achieve allocated energy.