• The KIPS Transactions:PartC
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• v.14C no.3 s.113
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• pp.277-284
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• 2007

The routing algorithm many used in the wireless sensor network features the clustering method to reduce the amount of data transmission from the energy efficiency perspective. However, the clustering method results in high energy consumption at the cluster head node. Dynamic clustering is a method used to resolve such a problem by distributing energy consumption through the re-selection of the cluster head node. Still, dynamic clustering modifies the cluster structure every time the cluster head node is re-selected, which causes energy consumption. In other words, the dynamic clustering approaches examined in previous studies involve the repetitive processes of cluster head node selection. This consumes a high amount of energy during the set-up process of cluster generation. In order to resolve the energy consumption problem associated with the repetitive set-up, this paper proposes the Round-Robin Cluster Header (RRCH) method that fixes the cluster and selects the head node in a round-robin method The RRCH approach is an energy-efficient method that realizes consistent and balanced energy consumption in each node of a generated cluster to prevent repetitious set-up processes as in the LEACH method. The propriety of the proposed method is substantiated with a simulation experiment.

• The KIPS Transactions:PartC
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• v.13C no.6 s.109
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• pp.709-716
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• 2006

According to the increase of various AV media devices and contents in the digital home, the DLNA becomes to play an important role as the interoperability standard between then Since this guideline only focuses on the interoperability among home networked devices, media players, and media contents existing inside of the homenetwork, there is no retrieval and transmission method for sharing multimedia contents located over several homes via Internet. Additionally, this guideline lets device-detection and notification messages to be transmitted using W multicast methods, and current Internet environment cannot guarantee consistent IP multicast services, it has the limitation that it cannot retrieve and control DLNA devices in other digital homes remotely via the Internet. Therefore, in this paper, we propose the IHM(Inter-Home Media) proxy system and its operating mechanism to provide a way of sharing media contents distributed over multiple DLNA-based homes, through analyzing these limitations and building up a sharing method for A/V media contents distributed over the DLNA homes based on the dynamic or private IP networks. Our method removes the limitation on the user locations through sharing distributed media contents, and also makes cost-downs for storing media contents, from the view point of individual residents.

• The Transactions of the Korea Information Processing Society
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• v.6 no.1
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• pp.122-133
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• 1999

Uses can share information and use resources effectively by using TCP/IP-based networks. So, a protocol to manage complex networks effectively is needed. For the management of the distributed networks, the SNMP(Simple Network Management Protocol) has been adopted as an international standard in 1989, and the SNMPv2 in which a security function was added was published in 1993. There are two encryption schemes in SNMPv2, the one is a DES using symmetric encryption scheme and the other is a MD5(Message Digest5) hash function for authentication. But the DES has demerits that a key length is a few short and the encryption and the authentication is executed respectively. In order to solve these problems, wer use a RSA cryptography in this paper. In this paper, we examine the items related with SNMP. In addition to DES and MD5 propose in SNMPv3, we chance security functionality by adopting RSA, a public key algorithm executing the encryption and the authentication simultaneously. The proposed SNMPv3 security module is written in JAVA under Windows NT environment.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.11
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• pp.403-410
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• 2016

IoT(Internet of Things) has purpose for providing new kind of service though interaction with everything. With development of IoT, computer model which is based on internet is changed to distributed connection model between heterogeneous things. There is a problem that it is impossible to connect between each other different protocols. To solve this problem, we should abstract each of things of data through using adaptor of middleware structure in order to make consistent data unit. In this paper, we propose BLE(Bluetooth Low Energy) adaptor, which is interaction with things, based on DDS(Data Distribution Service) that is real-time standard middleware. It is possible to data interaction between BLE Devices as well as two-way data interaction with different protocol devices. Also existing BLE Devices and study have a problem that Data exchange without using a standard data format of a profile defined by the Bluetooth SIG. Using the data formats defined independently by a problem that should not exchange data according to the type and manufacturer of the device BLE. The BLE adapter to solve this problem, the classification and analysis of the 12 stand profile was applied to create a profile based on the standard data format. It is possible to get wide interoperability of not affected on the BLE devices type and manufacturer of the device because it is applied a profile that standard data format.

• The KIPS Transactions:PartD
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• v.13D no.7 s.110
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• pp.889-900
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• 2006

Even though sensor networks are different in user requests and data characteristics depending on each application area, the existing researches on stream data transmission problem focus on the performance improvement of their methods rather than considering the original characteristic of stream data. In this paper, we introduce a hierarchical or distributed sensor network architecture and data model, and then evaluate the multivariate data reduction methods suitable for user requirements and data features so as to apply reduction methods alternatively. To assess the relative performance of the proposed multivariate data reduction methods, we used the conventional techniques, such as Wavelet, HCL(Hierarchical Clustering), Sampling and SVD (Singular Value Decomposition) as well as the experimental data sets, such as multivariate time series, synthetic data and robot execution failure data. The experimental results shows that SVD and Sampling method are superior to Wavelet and HCL ia respect to the relative error ratio and execution time. Especially, since relative error ratio of each data reduction method is different according to data characteristic, it shows a good performance using the selective data reduction method for the experimental data set. The findings reported in this paper can serve as a useful guideline for sensor network application design and construction including multivariate stream data.

• Journal of the Mineralogical Society of Korea
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• v.5 no.1
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• pp.22-31
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• 1992

The Sancheong kaolin was fractionated into 9 size fractions by wet sieving, sedimentation, and centrifugation. The systematic X-ray diffraction combined with electron microscopy shows that the clay mineral composition of each size fraction is related to the original fabric of kaolin. Minerals such as halloysite (10${\AA}$), kaolinite, illite, and goethite which were formed by procipitation from solution are generally concentrated in the finer fractions, whereas verniculite which was formed by pseudomorphic transformation from other primary minerals are concentrated in the coarser factions. Kaolinits of various types which were formed by precipitation or transformation show a wide size range but they are generally concentrated in the coarser fractions. Halloysite or halloysite-kaolinite clusters in coarse fractions are the fragmentation products of the walls of original boxwork clusters in coarse fractions are the fragmentation products of the walls of original boxwork kaolin which escaped the complete dispersion even through the grinding, ultrasonic agitation, and chemical treatment. Separation of fully hydrated halloysite and kaolinite was possible by systematic wet size fractionation. The coarse-grained minerals such as vermiculite and kaolinite are usually removed during the preparation of clay fraction smaller than 2${\mu}m$, whereas the fine-grained minerals such as illite and goethite are overlooked in X-ray diffraction of the bulk samples because of their minor contents. The systematic wet size fractionation is needed for understanding of the exact mineralogy of kaolin of weathering origin.

• The KIPS Transactions:PartA
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• v.13A no.2 s.99
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• pp.111-122
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• 2006

As VOD service over the Internet becomes popular, a large sealable VOD system in P2P streaming environment has become increasing important. In this paper, we propose a new proxy caching scheme, called P2Proxy, to replace the traditional proxy with a sealable P2P proxy in P2P streaming environment. In the proposed scheme, each client in a group stores a different part of the stream from a server into its local buffer and then uses a group of clients as a proxy. Each client receives the request stream from other clients as long as the parts of the stream are available in the client group. The only missing parts of the stream which are not in the client group are directly received from the server. We represent the caching process between clients in a group and a server and then describe a group creation process. This paper proposes the directory structure to share the caching information among clients. By using the directory information, we minimize message exchange overload for a stream caching and playing. We also propose a recovery method for failures about the irregular behavior of P2P clients. In this paper, we evaluate the performance of our proposed scheme and compare the performance with the existing P2P streaming systems.

• Journal of Korea Port Economic Association
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• v.32 no.1
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• pp.135-149
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• 2016

This study analyzes the concentration ratios (CR) and the shift effect in the system of Korean container ports that concern the export and import of container cargos, especially from/to 5 overseas origin/destination (O/D) regions, using the Hirshmann-Herfindahl Index (HHI) and the Shift-Share Method. The results shows that the CR has decreased during the last 20 years, from 0.86 to 0.44, mainly because cargos from/to the Far-East/South-East Asian regions have become more dispersed to several domestic container ports, especially from the Port of Busan. This study also indicates that there has been little change in the CR for all cargos, like the value of -0.3%, in the last 5 years. However the change in CRs for the cargos from/to the North America and Europe is positive, with the value of 7.6% and 6.6%, respectively. It can be inferred that the future development of medium- and small-sized container ports in Korea is not very likely. The study also suggests that the CR and the shift effect of the Korean container ports for the cargos by the domestic O/D regions should be analyzed in the future to suggest policy implications in great detail.

• Polymer(Korea)
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• v.38 no.1
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• pp.74-79
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• 2014

Microfibrillated cellulose (MFC) was chemically modified with two different silane coupling agents (3-aminopropyltriethoxysilane and 3-mercaptopropyltriethoxysilane) and lauroyl chloride. The surface modification of MFC was confirmed by infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX), and contact angle measurements. Composite paper was successfully prepared with surface modified MFC and polyamide (PA) fiber. The surface modification of MFC not only prevented aggregation of MFC but also improved adhesive property between PA fiber and surface modified MFC. It was impossible to prepare papers of only PA fiber because there is no binder to connect PA fibers. That is, surface modified MFC as a binder in PA fiber played a crucial role in making composite paper. Composite paper with silane modified MFC showed higher tensile strength and modulus than composite paper with lauroyl moiety modified MFC. The structure, morphology, and mechanical properties of composite paper were analyzed by scanning electron microscope (SEM) and universal testing machine (UTM).

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2011.03a
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• pp.108-108
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• 2011

PLA 즉 폴리유산섬유는 옥수수를 발효하여 글루코오스(포도당)상태를 만든 후 젖산(유산, Lactic acid)으로 만들고 이것을 탈수, 축합반응시켜 polylactic acid로 만든 것이다. 생분해성이 있으므로 저탄소, 녹색성장의 모토를 대변하는 소재라는 이점이 있다. 구조는 에스테르기의 반복단위를 가지는 소수성 섬유로 벤젠환은 없으나 그 외 구조는 폴리에스테르와 비슷하며, 에스테르기가 존재하므로 분산염료와 수소결합하여 염착된다. 그러나 PLA는 융점이 $170^{\circ}C$, Tg $57^{\circ}C$로 내열성이 낮아서 염색온도, 열처리온도, 다림질에 제약이 있으며, 알칼리에 약한 단점이 있다. 따라서 PLA섬유는 낮은 염착량, 내알칼리성, 염착온도 때문에 염색 및 후가공 단계에 많은 사전 실험을 통한 조건 설정이 필요한 까다로운 섬유이다. 본 연구에서는 (주)휴비스의 PLA원사로 제직한 직물(경사:DTY 75/72SD, 위사:DTY 100/72SD, 조직:DOBBY) 생지에 대하여 열처리 시 장력의 유무, 온도, 시간에 따른 폭의 변화를 측정하여 수축률을 알아보았다. 또한, PLA직물을 온도별로 정련한 후 열처리하여 인열강도 측정을 통해 최적 전처리 조건을 조사하였다. 실험결과, PLA생지를 무장력 상태에서 열처리 시 수축이 심하게 일어나고, 장력이 주어져도 열처리 온도에 따라 수축의 정도에 차이가 나타났다. 열처리 시간은 30, 60, 90, 120초로 주었으나 큰 편차는 없었고, 경사가 위사보다 수축 정도가 더 컸으며, $130^{\circ}C$에서는 전체적으로 수축이 심하였다. 생지의 정련에는 인산에스테르계 정련제와 약알칼리인 탄산나트륨으로 조액하여 60, 70, 80, $90^{\circ}C$에서 10분간 처리한 후, Lab. tenter(Mathis, LTE)를 이용하여 110, 120, $130^{\circ}C$에서 30, 60, 90, 120초간 열처리한 다음, KS K 0535 펜듈럼법에 의거하여 인열강도를 측정하였다. 그 결과, 상기 정련온도에서는 인열강도에 영향을 주지 않았으나, 열처리 온도가 $130^{\circ}C$일 때 현저한 강도의 저하를 나타내었다. 실험조건 하에서 가장 적절한 열처리 조건은 $110^{\circ}C$, 60초로 사료된다. 따라서 PLA의 약한 내열성과 내알칼리성 실험결과, 강도나 수축 등 물성변화가 일어나지 않도록 열처리 온도의 제어에 주의가 필요함을 확인할 수 있었다. 실제 섬유가공 작업현장에서는 일반적으로 열처리기가 $180^{\circ}C$이상의 고온으로 고정된 경우가 많은데, 작업자들에게 PLA소재에 대한 사전주의 및 공정변경에 대한 주지가 요구된다.