• The Transactions of the Korea Information Processing Society
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• v.6 no.4
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• pp.1058-1070
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• 1999

In this paper, we propose a control model which can control the burst input messages of the BSC(Base Station controller) in mobile communication systems more efficiently and reliably, by dividing the input messages characteristically and using multiprocessor system. Using M/M/c/K queueing model, we briefly analyze proposed model to get characteristic parameters which are required to performance improvement. On the base of the results, we compare our proposed model with the conventional one by using SLAM II with regard to the following factors : the call blocking rate of the input message, the distribution of average queue length, the utilization of process controller(server), and the distribution of average waiting time in queue. In addition, we modified our model which has overload control function for burst input messages, and analyzed its performance.

• The Journal of Korean Association of Computer Education
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• v.9 no.2
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• pp.111-124
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• 2006

Multicast services are provided on the Internet in fast increasing. Therefore it is important to keep security for multicast communication. If a member of the group is removed, new group key has to be generated and distributed to all remaining members of group. Minimizing number of messages and operation cost for generation of the composite keys to be used to encrypting group key are important evaluating criteria of multicast key management scheme since generation and distribution of new keys for rekeying require expensive operation. Periodic batch rekeying can reduce these important parameters rather than rekeying sequentially in fashion one after another. In this paper, Hamming distance is calculated between every members to be removed. In batch rekeying the members with Hamming distance less than threshold are selected for rekeying procedure. With running the round assignment algorithm in the case of removing several members simultaneously, our scheme has advantages of reducing messages and operation cost for generation of the composite keys and eliminating possibility of collusion attack for rekeying. We evaluate performance of round assignment algorithm through simulation and show that our scheme is excellent after performance comparison of existent schemes and our scheme.

• Membrane and Water Treatment
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• v.9 no.2
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• pp.69-77
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• 2018

The use of membrane as an innovative technology for water treatment process has now widely been accepted and adopted to replace the conventional water treatment process in increasing fresh water production for various domestic and industrial purposes. In this study, ultrafiltration (UF) membranes with different formulation were fabricated via phase inversion method. The membranes were fabricated by varying the polymer concentration (16 wt%, 18 wt%, 20 wt%, and 21 wt%). A series of tests, such as field emission scanning electron microscope (FESEM), pore size and porosity, contact angle, and zeta potential were performed to characterize the membranes. The membrane performance in terms of permeation flux and rejection were evaluated using a laboratory bench-scale test unit with mine water, lake water and tube well as model feed solution. Long hour filtration study of the membranes provides the information on its fouling property. Few pore blocking mechanism models were proposed to examine the behaviour of flux reduction and to estimate the fouling parameters based on different degree of fouling. 21 wt% PVDF membrane with smaller membrane pore size showed an excellent performance for surface water treatment in which the treated water complied with NWQS class II standard.

• Journal of Digital Convergence
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• v.17 no.9
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• pp.153-161
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• 2019

Discrimination of media object segments in wireless home proxies has a significant impact on caching delay, and caching delay degrades the performance of the proxy. In this paper, we propose a Single Fetching Smart Caching (SFSC) strategy and a Multi-Fetching Smart Caching (MFSC) strategy to improve the proxy performance of the home network and improve the caching performance for media object segments. The SFSC strategy is a technique that performs caching by sequential fetching of object segments requested by the home node one at a time, which guarantees a faster cache hit rate, and the MFSC strategy is a technique that caches the media object segments by blocking object segments requested by the home node one at a time, which improves the throughput of cache. Simulation results show that the cache hit rate and the caching delay are more efficient than the MFSC technique, and the throughput of the object segment is more efficient than that of the SFSC technique.

• Journal of Internet of Things and Convergence
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• v.9 no.6
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• pp.125-134
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• 2023

The purpose of this paper is to propose a method to improve the performance of the previous research is characterized by recognizing facial gestures from the 3D coordinates of seven landmarks selected from the MediaPipe Face Mesh model, generating corresponding user events, and executing corresponding commands. The proposed method applied adaptive moving average processing to the cursor positions in the process to stabilize the cursor by alleviating microtremor, and improved performance by blocking temporary opening/closing discrepancies between both eyes when opening and closing both eyes simultaneously. As a result of the usability evaluation of the proposed facial gesture interface, it was confirmed that the average recognition rate of facial gestures was increased to 98.7% compared to 95.8% in the previous research.

• Journal of the Korea Institute of Building Construction
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• v.21 no.5
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• pp.459-468
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• 2021

Blocking electromagnetic waves on the exterior walls of buildings effectively reduces the intensity of electromagnetic fields in buildings, which leads to attenuation of electromagnetic disturbances, so there is a great interest in developing technologies. In this study, SiC by-products and graphite generated in the semiconductor field were selected and mixed into mortar after pretreatment such as pulverization to evaluate their physical properties and electromagnetic wave shielding performance. Considering the economic efficiency of each shielding material, only 10% volume of the outermost side of the experiment was mixed with each shielding material to evaluate the shielding performance. The shielding performance was predicted when the experiment was manufactured by mixing the shielding material with the entire volume of the experiment using the shielding effect evaluation formula. The results of the experiment showed that the shielding performance was up to 20 dB when SiC grains were mixed with shielding materials, the shielding performance was up to 18 dB when graphite powder was mixed with shielding materials, and the shielding performance was up to 28 dB when SiC powder was mixed with shielding materials, and the shielding performance was close to 30 dB, which is known to have a shielding rate of 99.9%.

• The Journal of the Acoustical Society of Korea
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• v.41 no.6
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• pp.621-628
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• 2022

The most realistic way to reduce noise outside the building, such as road traffic noise and aircraft noise, is to strengthen the sound insulation performance at the sound collecting points such as balconies, windows, and exterior walls of each building. However, in light of the reality that shading devices outside buildings are not yet widely used, there are not many studies on sound insulation performance improvement using external windows and window devices such as louvers and blinds. In particular, external blinds can not only block the inflow of strong sunlight in the morning and evening from the outside of the building, but also target the sound insulation effect that blocks the peak noise that occurs during commuting hours. In this study, a study was conducted to improve sound insulation performance against external noise by using an external electric blind (EEB), which is one of the most efficient window and door external shading devices. Various sound insulation performance tests were conducted while changing the configuration of external electric blinds developed for light blocking purposes. Through this, it was verified that an additional sound insulation performance of 6 dB can be obtained by installing an external electric blind compared to the reduction performance of general windows.

• Journal of Korean Home Economics Education Association
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• v.23 no.3
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• pp.139-160
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• 2011

The purpose of this study is twofold: (i) to develop a teaching and learning plan and practical performance assessment tools for the improvement of teenager-parent communication and relationships as well as explore their effects on the communication in the everyday family life; and (ii) to find the underlying problems of teenager- parent communication through conversation analysis and to provide a improved dialogue model. We provided the experimental group with a performance task of communication training between teenagers and their parents in the real family situation while the control group practiced communication skills in a learning situation. However for both classes, before and after performance tasks were equally provided. The experimental group exhibited a longer conversation time with their parents, better communication skills, and higher degrees of relational satisfaction than the control group. Conversation analysis revealed that the experimental group reduced the use of blocking techniques in the teenager-parent conversations more than the control group, and all so raised the frequency of functional communications more than the control group. In both areas of communication in the experimental group was significantly improved, Most notably, a problem-solving case through no-lose conflict resolution methods was effective, succeeding by 70% in the e experimental group and 43.3% in the control group. Parents use blocking techniques like admonition, lecturing, blaming. sarcastic remarking, ordering and so forth, while teenagers use dispute, avoidance, blaming, and teasing in this order. The communication problems during the conversation process, teenagers' evasive and rebellious way of speaking instigates adverse communication responses from parents, so their conversation tends to unfold as ambiguous evasion opposed to: inquiring or evasion by short answers vs. ordering-preaching, or disputing vs. criticizing-making sarcastic, disputing vs. disputing-teaching, and criticizing vs. criticizing.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.957-965
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• 2011

Recently, railway industry has been developed not only functional parts such as acceleration and high performance of the railway but also emotional parts such as improved ride comfort and blocking noise. However, some important components of railway such as wheel and rail always had exposed too much operation time, cyclic load and rolling contact directly. The variations of load, vibration and chemical compositions were caused of wheel and rail having a lot of different types of contact fatigue damages. Therefore, It is necessary to improve inspection and maintenance technology in order to ensure safety and reliability of railway. Many researchers have already been reported the technology. Magnetic camera, one of the non-destructive testing technique can be used to inspect and evaluate the changes of magnetic field in ferromagnetic and paramagnetic materials with cracks. When an electromagnetic is applied to a specimen, a magnetic field will be distorted around a crack on the specimen. In present paper, the distribution of magnetic property in wheel with cracks using magnetic camera had investigated. The crack can be detected and evaluated by distribution analysis of magnetic field. The magnetic camera technique can be detected and evaluated the crack by rolling contact fatigue.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.838-856
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• 2014

Enhanced network speed and the appearance of various applications have recently resulted in the rapid increase of Internet users and the explosive growth of network traffic. Under this circumstance, Internet users are eager to receive reliable and Quality of Service (QoS)-guaranteed services. To provide reliable network services, network managers need to perform control measures involving dropping or blocking each traffic type. To manage a traffic type, it is necessary to rapidly measure and correctly analyze Internet traffic as well as classify network traffic according to applications. Such traffic classification result provides basic information for ensuring service-specific QoS. Several traffic classification methodologies have been introduced; however, there has been no favorable method in achieving optimal performance in terms of accuracy, completeness, and applicability in a real network environment. In this paper, we propose a method to classify Internet traffic as the first step to provide stable network services. We integrate the existing methodologies to compensate their weaknesses and to improve the overall accuracy and completeness of the classification. We prioritize the existing methodologies, which complement each other, in our integrated classification system.