• Journal of the HCI Society of Korea
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• v.5 no.2
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• pp.7-14
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• 2010

Urban Data collected through Sensor Network is becoming crucial to understand and analyse a city. Thus, the Ubiquitous Sensor Network builds the foundation of the u-City development. This research aims to develop an energy monitoring application with an intuitive visualization environment which integrates energy usage information on top of urban geospatial information. Such a system will be able to facilitate effective energy supply plan at the early stages of urban planning, and eventually to encourage citizens to conserve energy by giving them real time monitoring information in an easy to understand visual environment. The system provides multiple layers of energy-related information coupled with the geospatial information layer in order to accommodate multiple viewpoints. On the other hand, the system provides logical Level of Detail control based on urban spatial information hierarchy. We defined the system concept and functions, and designed the data structure and the methods of information visualization. This paper presents the visualization methods, data structure, interactions scenarios which combines spacial information, E-GIS data and the energy related sensor data. Furthermore this research tries to introduce the concept of Social Sensor Networking to enhance the monitoring quality.

• The Journal of the Korea Contents Association
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• v.15 no.6
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• pp.616-631
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• 2015

This study proposes a mobile Augmented Reality (AR)-based "word card" learning tool for children aged 3 to 5. First, this study suggests a learning structure to improve motivation and immersion of learning, Secondly, it designs and implements the user interface applying the proposed learning structure. Also, it designs a content management tool supporting the production of the content so that instructors can easily manage the contents for various learners. This study is conducted by four steps - reference research, design of "word card" learning content for the learner, design of content management tool for the instructor and the effectiveness verification of the proposed content. The proposed content was designed based on an education content architecture for enhancement of immersion and motivation to study. Moreover, it includes an 'AR content management tool for instructor' designed to easily update AR education content. The class for six children aged 3 to 5 was given to validate the enhancement of immersion to study. Experiment results showed that the proposed content enhanced the study immersion and that special interaction design for early children was necessary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.2
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• pp.298-302
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• 2008

This study was carried out to evaluate brazing characteristics of the braze joint between superhard alloy particles and carbon steel. Two types of insert metals that made by mechanical alloying process were selected for this study. One is composed of Cu, Zn and Ag(MIM-1) and the other one is composed of Cu, Zn, Ag and Cd.(MIM-2) The chemical compositions of these insert metals were similar to AWS BAg-20 and BAg-2a system. And the commercial insert metals(CIM-1, CIM-2) were also evaluated for the comparative study. The characterization of the insert metals were conducted by wettability tests, shear tensile test and microstructural analyses. The results indicated that wettability tests displayed that MIM-1 and CIM-1 insert metals had the larger wetting angle than MIM-2 and CIM-2 and the wetting angle of the MIM-1 showed higher value than that of CIM-1. However these values are less than $25^{\circ}$ that is recommended for standard value for usual insert metals. The highest value of shear tensile tests was obtained from the brazed joint that made by MIN-1 and the value was $2.29{\times}10^2MPa$. This value is appeared to be higher or same as the commercial insert metals. The microstructures of the inserts metals were composed of Cu-rich proeutectic structure for matrix and Ag-rich eutectic structure. The braze joint between superhard alloy particles and carbon steel produced by the MIM-1(Ag-Cu-Zn) system showed sound joint showing stable microstructures. However there was also some porosities at the interface.

• Korean Journal of Materials Research
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• v.10 no.2
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• pp.160-165
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• 2000

We have investigated the electrical and diffusion barrier properties of MgO produced on the surface of Cu (Mg) alloy. Also the diffusion barrier property of the interfacial MgO between Cu alloy and $SiO_2$ has been examined. The results show that the $150\;{\AA}$-MgO layer on the surface remains stable up to $700^{\circ}C$, preventing the interdiffusion of C Cu and Si in Si/MgO/Cu(Mg) structure. It also has the breakdown voltage of 4.5V and leakage current density of $10^{-7}A/\textrm{cm}^2/$. In addition, the combined structure of $Si_3N4(100{\AA})/MgO(100{\AA})$ increases the breakdown voltage up to lOV and reduces the leakage current density to $8{\tiems}10^{-7}A/\textrm{cm}^2$. Furthermore, the interfacial MgO formed by the chemical reac­t tion of Mg and $SiO_2$ reduces the diffusion of copper into $SiO_2$ substrate. Consequently, Cu(Mg) alloy can be applied as a g gate electrode in TFT /LCDs, reducing the process steps.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.9 no.3
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• pp.132-139
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• 1997

CTD and current observation were taken to investigate the structure of the cold water in the Western Channel of the Korea Strait in October 1993. Thickness of the cold water in the deep trough of the strait changes from 20 m to 70 m according to the water depth. Thermocline between the Tsushima Warm Water and the cold water deepens from north to south with 0.00057 in slope. Temporal variation of the thickness appears to be related with the tidal current. The maximum variation is 20 m for 48 hours. Mean velocity of the cold water for 72 hours is 17 cm/sec southward. A simple model was used to understand dynamically the southward flow of the cold water and the return flow at the upper part in the lower layer. Calculated maximum southward flow and eddy viscosity coefficient are 7 cm/sec and 0.038 $m^2$/sec respectively in the model. Southward transport is $0.032$\times$10^6㎥/sec$ at the northern part in the trough and decreases from north to south due to the presence of the return flow. Southward transport increases with the increase in the upper layer transport but is not affected by the density of the upper layer or the interface slope.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.2
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• pp.85-91
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• 2012

Purpose: The object of this study was to determine if the low-priced alloy and metal UCLA abutment could be available for manufacturing bar-retained framework of implant prosthesis. Materials and methods: Bar structure was classified into 4 groups, The specimen of group 1 and 2 were based on casting high noble metal alloys and noble metal alloys with gold UCLA abutment. The specimen of group 3 and 4 were based on casting noble metal alloys and base metal alloys with metal UCLA abutment. Cast bar structure was installed in an acrylic resin model and only the screw on the hexed abutment side was tightened to 20 Ncm. On the opposite side, vertical discrepancy was measured with stereo microscope from front, back, and lateral side of the implant-abutment interface. One-way ANOVA was performed to analyze the marginal fit discrepancy. Results: One-way ANOVA test showed significant differences among all groups ($P$<.05) except for Group 1 and 3. Among them, difference between Group 1 and 2 was noticeable. Measured vertical discrepancies were all below $70{\mu}m$ except to Group 2. Conclusion: Base metal alloy and metal UCLA abutment could be used as an alternative to high-priced gold alloy for implant bar-retained framework.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.2
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• pp.81-92
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• 1990

We developed the technologies of wuperlattice and HEMT structures grown by MOCVD, and their characterization. In the case of GaAs/AlGaAs superlattice, the periodicity, interface abruptness and Al compositional uniformity were confirmed through the shallow angle lapping technique and double crystal x-ray measurement. Photoluminesence spectra due to quantum size effect of isolated quantum wells were also observed. The heterojunction abruptness was estimated to be within 1 monolayer fluctuation by the analysis of the relation between PL FWHM(Full Width at Half Maximum) and well width. HEMT structure was successfully grown by MOCVD. The 2 dimensional electron gas formation at heterointerface in HEMT structure were evidenced through the C-V profile, SdH (Shubnikov-de Haas)oscillation and low temperature Hall measurement. Low field mobility were as high as $69,000cm^2/v.sec$ for a sheet carrier density of $5.5{\times}10^{11}cm^-2$ at 15K, and $41,200cm^2/v.sec$ for a sheet carrier density of $6.6{\times}10^{11}cm^-2$ at 77K. In addition, well defined SdH oscillation and quantized Hall plateaues were observed.

• Journal of the Mineralogical Society of Korea
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• v.26 no.2
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• pp.119-127
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• 2013

Borosilicate glass dissolution is an important chemical process that impacts the glass durability as nuclear waste form that may be used for high-level radioactive waste disposal. Experiments reported that the glass dissolution rates are strongly dependent on the bulk composition. Because some relationship exists between glass composition and molecular-structure distribution (e.g., non-bridging oxygen content of $SiO_4$ unit and averaged coordination number of B), the composition-dependent dissolution rates are attributed to the bulk structural changes corresponding to the compositional variation. We examined Na borosilicate glass structures by performing classical molecular dynamics (MD) simulations for four different chemical compositions ($xNa_2O{\cdot}B_2O_3{\cdot}ySiO_2$). Our MD simulations demonstrate that glass surfaces have significantly different chemical compositions and structures from the bulk glasses. Because glass surfaces forming an interface with solution are most likely the first dissolution-reaction occurring areas, the current MD result simply that composition-dependent glass dissolution behaviors should be understood by surface structural change upon the chemical composition change.

• Korean Journal of Agricultural and Forest Meteorology
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• v.1 no.1
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• pp.29-35
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• 1999

Soil structure and organic matter have been known to strongly affect water flow and solute transport, yet little information is available concerning soil hydraulic properties related to soil physical and chemical properties in the forest site. The purpose of this study was to quantify the spatial variability and spatial correlation of the measured parameter values from the plots established with the rainfall simulator on Japanese larch(Larix leptolepis) dominated site in Kwangju. Kyunggi-Do. Measurement of soil water flux and retention were made with the inherent soil texture, soil structure, and organic matter. The method was based on the observation that when water was applied at a constant rate to the soil surface on each plot. The method was simple to apply and consists of following steps: (i) Wet the soil from a rainfall simulator with several known discharge rates on a relatively leveled soil surface with and without organic matter. (ii) Once the borders of the ponded zone were steady, saturated hydraulic conductivity( $K_{s}$) and the matric flux function(F) was evaluated from a regression of flux vs. the reciprocal of the ponded area. A conductivity of the form $K_{i+}$$_1$ $_{c}$= $K_{i}$( $_{c}$) [1-d /dz] where flux continuity implies. For this, continuity of matric potential at the interface at all times are as follows: $_1$( $Z_{c}$) = $_2$( $Z_{c}$) = $_{c}$ for steady state intake from water ponded on the soil surface. Results of this investigation showed the importance of understanding spatial variability in wide differences of water retention and saturated hydraulic conductivity with respect to pore geometry and organic matter contents which influenced the water flux throughout the soil profile.l profile.ile.

• Journal of the Korean Geotechnical Society
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• v.15 no.3
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• pp.83-97
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• 1999

This paper presents the results of a parametric study on the interaction between buried pipes and surface load using the finite element method of analysis. A series of laboratory model tests were also performed in order to validate the adopted finite element model and to capture essential features of the physical behavior of buried pipes subjected to surface load. In the parametric study, a wide range of boundary conditions were analyzed with emphasis on the response of the buried pipes to surface load. The results of analysis such as contact stress distribution at the soil/pipe interface and axial thrust of the pipe were thoroughly analyzed, and a database on the response of buried pipe under surface load was established for future development of a semi-empirical design/analysis method. The results indicated that the degree of interaction between buried pipes and surface load significantly varies with the vertical and lateral location of pipe with respect to surface load, and that the current design method, which does not consider soil-structure interaction, cannot correctly capture the pipe response to surface loading. Furthermore, based on the results of analysis, a semi-empirical equation was suggested, which estimates the maximum pipe thrust due to surface load for flexible buried pipes.