• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.1B
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• pp.106-116
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• 2010

Sensor deployment makes an effect on not only covering of the interesting area but also reliable data acquisition and efficient resource management of sensor, so that sensors must be deployed at their better place. In traditional static wireless sensor networks, however, it is impossible to deploy the sensors manually when they are distributed in unexploited, hostile, or disaster areas. Therefore, if each sensor has locomotion capability, it can re-deploy itself using the location information of neighbor sensors. In our previous study, we showed that moving sensors to the centroids of their Voronoi polygon is efficient for extending the coverage area. In this paper, we present an improved potential-field-based sensor self-deployment scheme by combining the centroid of Voronoi polygon with the traditional potential-field scheme. Simulation results show that our scheme can achieve higher coverage in shorter time and less movement than the traditional potential-field scheme.

• Convergence Security Journal
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• v.8 no.4
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• pp.105-113
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• 2008

Mobile computing environment is known to be quite difficult to provide user with a stable Quality of Service (QoS) due to vehicle mobility nature. In order to protect the inherent characteristics of wireless network such as low bandwidth and high transmission delay along with the vehicle's mobility, many works are conducted to apply caching and prefetching methods. This paper presents a novel prefetching technique which is based on owner's profile. It is the scheme with the vehicle velocity, the visit frequency and resident time of specific region for vehicle owner's past given period, and the user profile which has owner's personal inclination about a certain place. The proposed scheme shown relatively superior performance in terms of the utilization ratio of prefetched information and the failure ratio of information retrieval than the previous methods.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.1
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• pp.255-268
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• 2017

A lot of city have different characteristics in their location, space and environment each other. These characters are the factors showing inherent placeness of each space, and those factors should be reflected sufficiently in urban planning and development. Nonetheless, there are many parts that are not actually reflected in the plan, and this creates a space of unexpected arming. Especially, port area in a port city has strong characteristics of culture, history, geography and environment of the city concerned so it must make more creative and unique space. Therefore, it is considered that not only the physical factors but also the social factors should be actively reflected to highlight the place character of the port space. In this paper we are to construct the factors forming the placeness of port space based on the Form Based Codes rising as a flexible urban planning method in order to avoid rigidity of existing use district zoning system, and establish the placeness character of each port area.

• Journal of Agricultural Extension & Community Development
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• v.20 no.1
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• pp.173-203
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• 2013

This study aims to find the effective policy devices for attracting enterprises in rural areas. In the first place, the result of this study suggest two directions fundamentally as follows: Firstly, the government works on more positive lines and from more integrated viewpoint. Secondly, it give the first consideration to the big-enterprises for attracting enterprises in rural areas. Next, the study suggest three practical policy implements also. First, the government put an emphasis on construction favorable infra structure to enterprises's activity. Second, it is necessary to strengthen the economic supports for location of enterprises in rural areas. Third, the rural self-government make effort strongly to develop the activity to attract enterprises.

• Journal of Periodontal and Implant Science
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• v.42 no.2
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• pp.39-44
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• 2012

Purpose: Special care is necessary to avoid invading important anatomic structures during surgery when presurgical planning is made based on radiographs. However, none of these types of radiography represents a perfect modality. The purpose of this study was to determine the reliability of presurgical planning based on the use of two types of radiographic image (digital panoramic radiography [DPR] and cone-beam computed tomography [CBCT]) by beginner dentists to place implants, and to quantify differences in measurements between radiographic images and real specimens. Methods: Ten fresh cadavers without posterior teeth were used, and twelve practitioners who had no experience of implant surgery performed implant surgery after 10 hours of basic instruction using conventional surgical guide based on CBCT or DPR. Two types of measurement error were evaluated: 1) the presurgical measurement error, defined as that between the presurgical and postsurgical measurements in each modality of radiographic analysis, and 2) the measurement error between postsurgical radiography and the real specimen. Results: The mean presurgical measurement error was significantly smaller for CBCT than for DPR in the maxillary region, whereas it did not differ significantly between the two imaging modalities in the mandibular region. The mean measurement error between radiography and real specimens was significantly smaller for CBCT than for DPR in the maxillary region, but did not differ significantly in the mandibular region. Conclusions: Presurgical planning can be performed safely using DPR in the mandible; however, presurgical planning using CBCT is recommended in the maxilla when a structure in a buccolingual location needs to be evaluated because this imaging modality supplies buccolingual information that cannot be obtained from DPR.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.40 no.1
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• pp.124-131
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• 2015

In this paper, we proposed indoor positioning system using RSS(Received Signal Strength) positioning method and TSS(Transmission Signal Strength). The main point in the paper is to improve reliability of accuracy positioning with the area recognition algorithm and probabilistic algorithm, which can be effectively used indoor. In the test in 1-dimensional or 2-dimensional spaces, also we checked effective positioning system considered environment of propagation that is changed by reflection, refraction and multipath in according to space form. It is necessary to find place where urgent situation happen and quickly to respond the situation for patients or the weak. Therefore, we expect the positioning system proposed can apply to the field of traffic IT.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.11
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• pp.682-689
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• 2014

Due to explosive growth of mobile data traffic, many kind of techniques based on small cell is proposed as solution for phenomenon. However, those techniques essentially demands increase of backhaul capacity and causes performance degradation if not satisfied. Based on that, the approach applying the storage capacity in place of backhaul capacity, which is known as femto-caching, is proposed to reduce data downloading delay of users in system. In this paper, we expanded previous research by proposing file placement strategy with distribution of user position, which is more practical scenario. Simulation results verify that our proposed scheme has better performance gains mainly because when coverage of helpers are overlapped, users get more opportunity to connect various helpers which enables users to download a variety kind of files from helpers, not base station.

• Journal of the Korean Institute of Gas
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• v.20 no.6
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• pp.58-64
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• 2016

Vibrational characteristics of curved pipe structures are investigated with respect to the change of inside flow velocities. Based upon the Hamilton's principle, the equations of motions are derived, and the finite element equation is constructed to solve the frequency equation for curved pipe structures. When the initial tension is neglected in cured pipes, the natural frequencies are reduced as flow velocity increases, and the rapid decreases of the natural frequencies take place. However, when the initial tension is taken into account, the natural frequencies are not changed with the change of the flow velocity. In free vibrational simulation of pipe systems, it is necessary to calculate the initial force due to the velocity and the pressure of the fluid flow from the equilibrium. The force should be included in the equation of motion of the systems to get more accurate natural frequencies. The mechanical properties like stiffness or the location of pipe support need to be changed to avoid resonance. The natural frequencies are to be isolated from the frequency range of dominant vibration modes. The angles of elbows do not affect the change of the fundamental natural frequency, but affect the change of the third or higher natural frequencies.

• Journal of the Korean Institute of Landscape Architecture
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• v.31 no.6
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• pp.41-52
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• 2004

Recently, park usage for environmental education has gained popularity in Seoul. Therefore this study was performed by analyzing the status and problems of nature classrooms in neighborhood parks and citizen's parks that are located in residential areas in Seoul, and then by suggesting improved methods and user programs. The results of this study are summarized as follows. 1) 18 out of 281 neighborhood parks and citizen's parks have nature classrooms in Seoul. Facilities of nature classroom are comprised of direction signs, plant name card, pond, pavilion, pergola, bench, green house, waste baskets, lighting, drinking fountain and others. However, they have many problems in terms of quality. Nature classrooms were classified into three types according to their location in each park. Among the three types, the most popular type was the one that is a part of a park A Total of 479 species of plant (155 species in tree, 324 species in herb) were planted in nature classrooms. There are many kinds of environmental education user programs, but these are not connected with the nature classrooms. Most nature education programs in nature classrooms were self-guided. 2) The Problems that appeared were the featureless place composition, a lack of programs related to nature classrooms, access restriction to certain natured areas, and so on. 3) Finally, this study suggests some solutions to the problems of nature classrooms in urban parks. The solutions include full access to the parks, the creation of diverse theme, and setting up interesting panel and leaflets in order to encourage more active self-guided education.

• Journal of the Korean Institute of Rural Architecture
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• v.10 no.1
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• pp.101-109
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• 2008

It is very hard to find out Tongbanga-millhouse installed nearby a streamlet to use water with Tongbanga(a kind of water-mill) to polish cereals by pounding like a visage of its old days. It plays an important part in folkloric, architectural and educational aspects. The purpose of this study is to analyse the architectural features of Tongbanga and millhouse itself so that to find the way how to build and fabricate the materials and frame members. Therefore this study has been focused on the composition principle and fabrication method of Tongbanga-millhouse on the side of architecture. The fabrication methods of its house in accordance with regular sequences are as follows. ${\cdot}$ Firstly the decision of location of Tongbanga-millhouse and Hwak(a big mortar made of stone). ${\cdot}$ Slantly three rafter installation at an angle of $50^{\circ}$ to err on the safe side and then slantly fifteen rafter installation making a circular cone shape. ${\cdot}$ Installation of twigs to be circles from bottom to top. ${\cdot}$ Manifoldly covering of trunks peeling the barks from flax plants. ${\cdot}$ Threefoldly thatching with upside barks of oak trees. ${\cdot}$ Placing woods alike rafter on the bark thatches as a weight not to fly away by wind. ${\cdot}$ Binding woods alike rafter with vines of arrowroots to maintain the proper place. The decayed Tongbanga-millhouse by means of upper ways was restored out of all recognition.