• Proceedings of the Korea Information Processing Society Conference
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• 2019.10a
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• pp.536-537
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• 2019

작물의 생육에 따라 적기에 필요한 양만큼의 양분을 공급해 최고의 생산성을 올릴 수 있는 수경재배는 정보통신기술(ICT)을 융·복합한 스마트 농업 형태로 전환되고 있으나, 기술 발전에도 불구하고 여전히 환경 및 경제성 문제 등 많은 개선점을 가지고 있다. 본 논문에서는 딸기 수경재배지의 환경 데이터 및 생육 데이터를 수집하고, 터치스크린과 스마트폰을 통하여 배양액의 배액량, pH, EC, 온도, 습도를 실시간 및 정한 기간에 따라 모니터링이 가능한 수경재배 소규모 온실을 위한 SBC기반의 모니터링 시스템을 제안한다.

• Journal of Digital Convergence
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• v.10 no.10
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• pp.247-259
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• 2012

The purpose of study is to advance current smartphone research past the limitation it faces being focused primarily on functional performance and to understand the causes of Smartphone diffusion. In order to do this, the dominant design concept was applied in examining the relationship between the determinants of the dominant design and the acceptance of smartphones. The research has yielded results which show that determinants such as technological superiority, number of installed based products, and availability of complementary goods have a positive effect on the intention to use smartphones and the attitude toward its use. Moreover, this study has contributed in broadening the understanding of dominant design by introducing the central concepts of dominant design which are not being dealt with in domestic studies and presenting the major variables which must be considered in the acceptance of smartphones.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.37-52
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• 2013

Prior to full-scale implementation of smart grid, the Korean government is conducting a smart grid testbed in Jeju island. However, the participants of the ongoing program are skeptical about the success of the expansion of smart grid. The concern rises from various reasons; the limits of the Korean electricity market mainly led by both the government and KEPCO, high stability and reliability of the existing electricity grid, insufficient utilization of renewable energy, and public fear of raised electricity bills. Five key issues in regards to facilitating the Korean smart grid market are extracted and evaluated. The issues are conflict of interest among participants, the effect of introducing real-time pricing, lack of customer participation of demand response, and absence of business models.

• Composites Research
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• v.34 no.6
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• pp.357-372
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• 2021

The energy harvesting device is known to be promising as an alternative to solve the resource shortage caused by the depletion of petroleum resources. In order to overcome the limitations (environmental pollution and low mechanical properties) of piezoelectric elements capable of converting mechanical motion into electrical energy, many studies have been conducted on a polymer matrix-based composite piezoelectric energy harvesting device. In this paper, the output performance and related applications of the reported piezoelectric composites are reviewed based on the applied materials and processes. As for the piezoelectric fillers, zinc oxide, which is advantageous in terms of eco-friendliness, biocompatibility, and flexibility, as well as ceramic fillers based on lead zirconate titanate and barium titanate, were reviewed. The polymer matrix was classified into piezoelectric polymers composed of polyvinylidene fluoride and copolymers, and flexible polymers based on epoxy and polydimethylsiloxane, to discuss piezoelectric synergy of composite materials and improvement of piezoelectric output by high external force application, respectively. In addition, the effect of improving the conductivity or the mechanical properties of composite material by the application of a metal or carbon-based secondary filler on the output performance of the piezoelectric harvesting device was explained in terms of the structure of the composite material. Composite material-based piezoelectric harvesting devices, which can be applied to small electronic devices, smart sensors, and medicine with improved performance, can provide potential insights as a power source for wireless electronic devices expected to be encountered in future daily life.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2005.04a
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• pp.1-4
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• 2005

A higher order zig-zag shell theory is developed to refine accurately predict deformation and stress of smart shell structures under the mechanical, thermal, and electric loading. The displacement fields through the thickness are constructed by superimposing linear zig-zag field to the smooth globally cubic varying field. Smooth parabolic distribution through the thickness is assumed in the transverse deflection in order to consider transverse normal deformation. The mechanical, thermal, and electric loading is applied in the sinusoidal distribution function in the in-surface direction. Thermal and electric loading is given in the linear variation through the thickness. Especially, in electric loading case, voltage is only applied in piezo-layer. The layer-dependent degrees of freedom of displacement fields are expressed in terms of reference primary degrees of freedom by applying interface continuity conditions as well as bounding surface conditions of transverse shear stresses. In order to obtain accurate transverse shear and normal stresses, integration of equilibrium equation approach is used. The numerical examples of present theory demonstrate the accuracy and efficiency of the proposed theory. The present theory is suitable for the predictions of behaviors of thick smart composite shell under mechanical, thermal, and electric loadings combined.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.5
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• pp.9-14
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• 2002

A higher order zig-zag plate theory is developed to accurately predict fully coupled mechanical, thermal, and electric behaviors. Both the in-plane displacement and temperature fields through the thickness are constructed by superimposing linear zig-zag field to the smooth globally cubic varying field. Smooth parabolic distribution through the thickness is assumed in the transverse deflection in order to consider transverse normal deformation. Linear zig-zag form is adopted in the electric field. The layer-dependent degrees of freedom of displacement and temperature fields are expressed in tern-is of reference primary degrees of freedom by applying interface continuity conditions as well as bounding surface conditions of transverse shear stresses and transverse heat flux. The numerical examples of coupled and uncoupled analysis demonstrate the accuracy and efficiency of the present theory. The present theory is suitable for the predictions of fully coupled behaviors of thick smart composite plate under mechanical, thermal, and electric loadings combined.

• Journal of Digital Convergence
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• v.10 no.5
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• pp.339-349
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• 2012

Smartphones which represent to the Mobile convergence, is the rapid spread, more than half of Korean are using. Accordingly, mobile apps that run on smartphone market is growing at a rapid pace. However, most studies on smartphone and mobile apps are focusing on the technology acceptance and improvement of function. So, this study is to suggest promotion strategy to each mobile apps, analyzed through three phases. First phase is the frequency analysis that deduct most frequently used mobile apps. Second phase is association rules that found to associate between mobile apps. Finally, to analyze deduction techniques for acquired 5 mobile apps to target variable in pre-2 phase use total 35 variables of 20 mobile apps categories, demographic variables, amount of PC, movie, music, book, game usage and fees per month.

• Journal of Digital Convergence
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• v.13 no.12
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• pp.381-390
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• 2015

One of the fundamental requirements of entertainment applications is interactivity with users. The mobile device such as the smartphone, however, does not guarantee it due to the limit of the application processor's computing power, memory size and available electric power of the battery. This paper proposes a methodology to boost responsiveness of interactive applications by taking advantage of the parallel architecture of mobile devices which, for instance, have dual-core, quad-core or octa-core. To harness the multi-core architecture, it exploits the POSIX thread, a platform-independent thread library to be able to be used in various mobile platforms such as Android, iOS, etc. As a useful application example of the methodology, a heavy matrix calculation function was transformed to a parallelized version which showed around 2.5 ~ 3 times faster than the original version in a real-world usage environment.

• Journal of Digital Convergence
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• v.15 no.5
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• pp.99-106
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• 2017

The purpose of this study is to analyze the relationship between tourist 's intention to use smartphone and the preceding factors through the questionnaire. For achieving this research purpose, this study surveyed the tourists who use smartphone to investigate the influence of interactivity such as two-way communication and synchronicity as hypotheses on the influence of flow, and the effect of attitude factors on continuous intention to use was analyzed by research model. In this study, a partial least squares based structural equation (PLS-SEM) method was applied to verify the hypothesis of the proposed research model. Finally, the validity of the proposed research model was confirmed through confirmatory factor analysis and hypothesis testing. Therefore, the results of this study show that interactivity and flow are influential for the reuse of users in utilizing information by using smartphone, and it affects the attitude of users in developing smart tourism system in the future. The results of this study can be utilized as basic data related to the acquisition of information by smartphone of tourists in the future development of smart tourism system.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.45-45
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• 2023

본 연구에서는 도시 내 및 주변 지역을 대상으로 기상학적 가뭄 발생 여부에 따른 토양수분량 변화 정도를 파악하고, 그에 따른 열섬 현상의 변동 정도를 분석·평가하였다. 먼저, 대상 지역 내 기상학적 가뭄의 시공간적 특성을 분석하기 위해 인공위성, 재분석 자료 및 지상 관측 정보를 활용하여 SPI (Standard Precipitation Index)와 SPEI (Standard Precipitation Evapotranspiration Index) 등 두 가지의 가뭄 지수를 산정하였다. 또한, ERA5 (The Fifth Generation ECMWF Atmospheric Reanalysis)와 GLDAS (Global Land Data Assimilation System) 등의 재분석 자료 및 지상 관측 정보를 활용하여 토양수분 자료 및 기타 기상 관련 주요 정보들을 얻고, 이를 ENVI-met 모형의 초기 입력자료로 고려하였다. 다양한 시나리오 기반의 모의 결과들을 바탕으로 복합 재난의 관점에서 가뭄-토양수분량-열섬 간의 연관성을 분석하고, 주요 영향 인자 및 극한 사상 유발 조건 등에 대한 정보를 파악하였다.