• Journal of the Korea Society for Simulation
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• v.28 no.3
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• pp.25-40
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• 2019

Today, container terminals are fiercely competing to attract an increasing number of containers. As a way to improve terminal productivity, this study proposes two dispatching rules for yard truck allocation priorities. First, Multi-Attribute Dispatching Rule(MADR) is an allocation method to calculate the weighted sum of multiple factors affecting container terminal productivity and priority them. Especially, the workload of the quay crane was considered one of the factors to reduce the residence time of the ship. Second, Cycling Dispatching Rule(CDR) is the effective way to increase the number of double cycles that directly affect terminal productivity. To identify the effects of combinations of pooling and dispatching, a comparative experiments was performed on 8 scenarios that combined them. A simulation environment has been developed for experiments and the results have demonstrated that the combination of terminal level pooling and Multi-attribute Dispatching could be an excellent combination in KPIs consisting of GCR and delayed departure of ships, etc.

• Journal of the Korean Institute of Gas
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• v.25 no.6
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• pp.1-6
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• 2021

In this study, we developed AMI terminals of 1 (reader): N (small transmitter). Currently, the government is focusing on the Gas AMI demonstration project to advance the outdated metering system of the urban gas industry, led by the government-sponsored ministries. The supply of gas AMI meters has the advantage of resolving uncertainties in privacy violations and measurement information and preparing for consumer safety through gas leakage detection. In the case of existing AMI meters, readers and transmitters were 1:1 methods, while this technology can be extended to multiple generations with a 1:N method, and a technology that can extend battery life by implementing a low-power design is applied. We hope that this research will contribute to the gas AMI supply project in the future.

• Journal of Korean Library and Information Science Society
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• v.24
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• pp.163-187
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• 1996

The library catalog is considered an important tool to provide library users with conveniences making a search for necessary information. Accordingly, the purpose of this study is to investigate "behaviors and attitudes" of library users in a university library using online and card catalogs together, to compare their distinctions between online and card catalogs and then to bring about reforms for the development of future cataloging, thereby improving the utilization of online catalog and its service expansion. For this, this paper carried out a survey research which was randomly questionaired 280 library users of four universities in Seoul from March 28th to April 16th 1996. Major findings are as follow : 1. Library users tended to use more online catalog(50.0%) than card catalog (21.9%). 2. The main reasons the library users us online catalog were time saving(24.0%), convenience of use(21.3%), multiple searching possibility (16.2%), and the preferences of card catalog were location of library materials(34.6%), time saving(17.5%), Bibliographic information(14.9%). 3. The major access points which library users utilized mostly in their online catalog are title(30.3%), author(29.2%) and subject heading (17.6%), and for card catalog, title(40.5%), author(34.6%) and call no.(11.1%). 4. The methods library users learned to use online catalog are terminal screen(44.7%), online manual(26.1%), and for card catalog, library orientation(42.6%), librarian's help(18.5%). 5. It was shown that library users were not mostly satisfied about their searching results: the users satisfied with online catalog in the order of partly(46.2%), as expected(42.3%), more than expected(10.4%), and with the card catalog in the order of partly(54.6%), as expected(27.3%), more than expected(10.4%). It was found that although library users preferred online catalog more than card catalog, 54.8% of the total catalog users were not satisfied about the search results they have had. 6. The items which library users want to add to online catalog are catalogs of materials other libraries have(41.6%), catalogs of the materials the library has(29.3%), titles of serial articles(17.7%). And the additional services library users want are checking function of loan materials and reservation of materials(15.5%), subject headings(14.5%), more terminals(13.4%), catalog use explanations(12.9%), multiple access points(11.0%), searching function of contents, abstracts, and indexes(9.6%). Considering the fact that library users tend to use more favorably online catalog than card catalog and the trend that library change from card catalog to online catalog, it is strongly recommended to su n.0, pply students with formal and informal training programs for online catalog use.talog use.

• Journal of Korea Society of Industrial Information Systems
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• v.16 no.4
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• pp.53-65
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• 2011

As the Information and Communication Technologies continue to advance, some sensitive services (e.g. e-commerce, on-line financial service, and etc.) have spread rapidly. Accordingly, ensuring the safety of the sensitive service itself using personal Information as well as the protection of personal Information Is becoming very important. In addition, with the popularization of smart phone and the universalized use of wireless Internet, many services that have been provided on the basis of the conventional wired network are increasingly propagating to wired and wireless converged network environment. These changes in the network environment requires new paradigm for the pursuit of safe and stable communication. In this paper, we propose seamless and secure service framework that can facilitate a sustainable secure connection between the user terminal and the sensitive service system by using both the personal and network Information. The proposed service framework is capable of isolating the source of authorized use by a third party of the personal Information as far as the user terminal is not lost, although some personal Information is disclosed. Besides, it can provide a seamless and safe service environment even if the access network is changed by relocation of terminals in the heterogeneous mobile network environment.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.96-103
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• 2000

The voice traffic is one of the most important real-time objects in WATM(Wireless Asynchronous Transfer Mode) networks. In this paper, we propose a new MAC(Medium Access'Control) protocol for the efficienttransmission of voice traffic over WATM networks in the multimedia environment and compare the performanceto existing similar protocols. The new protocol separates the reservation slot period for voice and that for data toguarantee some level of QoS(Quality of Service) in voice traffic. This is denoted by a slot assignment functiondepending on the frame size. According to the characteristics of voice traffic which is repeatedly in silent states,the protocol allocates voice reservation request slots dynamically with respect to the number of silent(off state)voice sources and also sends the first block of talkspurt restarted after silent period with a reservation requestslot to reduce the access delay.The simulation results show that the proposed protocol has better performance than Slotted Aloha in bandwidthefficiency, and can serve a certain level of QoS by the given slot assignment function even when the number ofvoice terminals varies dynamically. This means we can observe that the new MAC protocol is much better thanthe NC-PRMA(None Collision-Packet Reservation Multiple Access) protocol.

• Asia-Pacific Journal of Business Venturing and Entrepreneurship
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• v.8 no.2
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• pp.93-106
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• 2013

Cloud computing services have became an hot issues in business fields while the IT-related global company such as Amazon, MS, and Google took part in. The cloud computing makes it possible to share in the form of outsourcing of hardware and software through the Internet, to build a distributed computing environment via multiple terminals, and to reduce the cost using open source. Such a cloud computing services have not shown any significant growth in Korea yet compared to other countries. Therefore, in this study focusing on public cloud computing services, it is intended to analyze the determinants of public cloud computing services using the technology model. Thus, for users using public cloud services, we conducted a questionnaire survey from the beginning of January 2013 to the end of February 2013. And we derived a research model based on the Technology Acceptance Model(TAM). As a result of this study, it shows that personal aspects significantly impacts on the perceived usability, service aspects, systems aspects, and the intent of the technology acceptances. System aspects significantly effect on the intent of technology acceptances. Perceived usability significantly effects on the service aspects and the systems aspects. The main factors effecting on the intent of the technology acceptances are system aspects and perceived usability in order. And it shows that the personal aspects decreases the intent of the technology acceptances.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38A no.1
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• pp.68-78
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• 2013

In this paper, we propose an early spectrum sensing(ESS) as an advance preparation for radio-access trial, which enables multi-mode terminals to access the most appropriate radio-access system in a cloud-conceptual base station system where multiple radio access technologies(RATs) coexist. Prior to a random access to one of RATs, a multi-mode terminal conducts a spectrum sensing over entire frequency bands of whole RATs, then select the RAT with the lowest sensing power, that is likely to have the most available spectrum. Thus, an access failure caused by that the selected RAT has no available radio spectrum could be avoidable in advance. In computer simulation, we consider as various RATs as possible. First, circuit and packet systems are taken into consideration. In addition, the packet systems are classified according to the feasibility of carrier aggregation(CA). In case of terminal, three modes are considered with circuit-only, packet-only, and multi-mode. Subsequently, packet traffic is classified into real-time and non-real-time traffic with three different tolerable delay levels. The simulation includes a call process starting with a call generation and ending up with a resource allocation reflecting individual user's QoS requirements and evaluates the proposed scheme in terms of the successful access probability, system access time, system balancing factor and packet loss probability.

• Journal of KIISE:Information Networking
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• v.37 no.5
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• pp.374-385
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• 2010

Wireless mesh networks can be deployed for various networks from home networking to last-mile broadband Internet access. Wireless mesh networks are composed of mesh routers and mesh clients. In these networks, static nodes form a multi-hop backbone of a large wireless access network that provides connectivity to end-users' mobile terminals. The network nodes cooperate with each other to relay data traffic to its destinations. In order to increase connectivity and better performance, researchers are getting interested in multi-channel and multi-interface wireless mesh networks. In these networks, non-overlapping multiple frequency channels are used simultaneously to increase the aggregate bandwidth available to end-users. Recently, researches have focused on finding suitable channel assignments for wireless network interfaces, equiped in a mesh node, together with efficient routing to improve overall system throughput in wireless mesh networks. This goal can be achieved by minimize channel interference. Less interference among using channels in a network guarantees more aggregated channel capacity and better connectivity of the networks. In this thesis, we propose interference aware channel assignment and routing algorithms for multi-channel multi-hop wireless mesh networks. We propose Channel Assignment and Routing algorithms using Traffic Profiles(CARTP) and Routing algorithms allowing detour routing(CARTP+2). Finally, we evaluate the performance of proposed algorithms in comparison to results from previous methods using ns-2 simulations. The simulation results show that our proposed algorithms can enhance the overall network performance in wireless mesh networks.