• IEMEK Journal of Embedded Systems and Applications
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• v.8 no.1
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• pp.1-9
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• 2013

Performance of smart phones has increased to conduct simple PC functions that has become essential to modern people. With the development of smart phones, not only limited inner sensors but various sensors can be connected through USB. However, there is problem that app needs to downloaded when using each sensor. In this paper, a smart phone unified app structure for USB sensor Plug&Play is presented. The structure was designed to download web pages to use various sensors in one app. Unified app communicated with the platform through ADK accessory protocol and implements structure of delivering sensor ID to the web server and downloading device driver, web page. By measurement test, it was confirmed that download time of web page in unified app was 10 times faster than original download time of original app. By managing various sensors by one app, the app is searched every time the sensor changes in which there is no need for downloading several apps.

• Nuclear Engineering and Technology
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• v.43 no.4
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• pp.361-374
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• 2011

Two types of numerical modeling techniques were considered for the dynamic response of a structure subjected to a ground acceleration. One technique is based on the equation of motion relative to ground motion, and the other is based on the equation of absolute motion of the structure and the ground. The analytic background of the former is well established while the latter has not yet been extensively verified. The latter is called a large mass method, which allocates an appropriate large mass to the ground so that it causes the ground to move according to a given acceleration time history. In this paper, through the use of a single degree-of-freedom spring-mass system, the equations of motion of the two techniques were analyzed and useful theorems are provided on the large mass method. Using simple examples, the numerical results of the two modeling techniques were compared with analytic solutions. It is shown that the theorems provide a clear insight on the large mass method.

• International conference on construction engineering and project management
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• 2022.06a
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• pp.1256-1263
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• 2022

With the advent of the Fourth Industrial Revolution, the amount of energy used in buildings has been increasing due to changes in the energy use structure caused by the massive spread of information-oriented equipment, climate change and greenhouse gas emissions. For the efficient use of energy, it is necessary to have a plan that can predict and reduce the amount of energy use according to the type of energy source and the use of buildings. To address such issues, this study presents a model embedded in a digital twin that predicts energy use in buildings. The digital twin is a system that can support a solution of urban problems through the process of simulations and analyses based on the data collected via sensors in real-time. To develop the energy use prediction model, energy-related data such as actual room use, power use and gas use were collected. Factors that significantly affect energy use were identified through a correlation analysis and multiple regression analysis based on the collected data. The proof-of-concept prototype was developed with an exhibition facility for performance evaluation and validation. The test results confirm that the error rate of the energy consumption prediction model decreases, and the prediction performance improves as the data is accumulated by comparing the error rates of the model. The energy use prediction model thus predicts future energy use and supports formulating a systematic energy management plan in consideration of characteristics of building spaces such as the purpose and the occupancy time of each room. It is suggested to collect and analyze data from other facilities in the future to develop a general-purpose energy use prediction model.

• Journal of Family Resource Management and Policy Review
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• v.27 no.4
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• pp.63-74
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• 2023

This study considered allocating and balancing time use as an important factor that determines the quality of life, and attempted to analyze the happiness of married women through the perspective of satisfaction with time use. We investigated the structure of time use, and analyzed the factors that affect happiness in the perspective of time use through the Time Use Survey data. Analyzing the happiness of married women, we found out that the level of happiness and the factors affecting happiness varied by generation. In the case of economically active women, the happiness of baby boomers and Generation X was mostly impacted by mandatory work hours, while the happiness of Generation Y was mostly impacted by the presence of care-dependent people. However, in the case of economically unactive women, the happiness of baby boomers and Generation X was mostly impacted by leisure and volunteering time that could be used freely, while the happiness of Generation Y was mostly impacted by the attitude toward gender roles. Therefore, through the perspective of time use, the happiness and the factors determining the happiness of married women differs by generation and economic activeness. This study has significant implications for the establishment of family policies for married women.

• International conference on construction engineering and project management
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• 2005.10a
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• pp.796-801
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• 2005

Time management is one of the critical tasks in project management. Based on the theories of total quality management, this authors presented a project time management method, total time management (TTM), so as to facilitate highway project time management. This paper discussed the four fundamental characteristics of TTM: total factors management, staff management, project life cycle management, and Plan-Do-Check-Action (PDCA) cycle management. Now, most managers use computer software to manage the project. In order to make the theory of TTM more executable, the authors develop a project time management system suitable for TTM. This paper presents this time management system's analysis processes including system requirement, key functions etc..

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.19 no.3
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• pp.36-41
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• 2020

Mechanical systems installed in transport devices, such as vehicles, airplanes, and ships, are mostly subject to translational accelerations at the joints during operations. This base acceleration excitation has a large influence on the performance of the system, therefore, its response must be well analyzed. However, the existing methods for dynamic analysis of structures have some limitations in use. This study presents a new numerical method using relative acceleration to solve these limitations. If the governing equation of motion is linear and the mass matrix, the damping matrix, and the stiffness matrix are constant over time in the finite element analysis, the proposed method can be applied to the transient behavior analysis and the harmonic response analysis of the structure. Because it is not necessary to introduce a virtual mass and the rigid body motions are removed from the analysis, it is possible to use not only the direct integration method in the time domain but also the mode superposition method to obtain the dynamic responses. This paper demonstrates with three examples how the present method is suitable for the dynamic analysis of a structure with multi-degree of freedom.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.6
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• pp.659-665
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• 2010

The finite element method(FEM) is proven to be an effective approximate method of structural analysis if proper element types and meshes are chosen, and recently, the method is often applied to solve complex dynamic and nonlinear problems. A properly chosen element type and mesh yields reliable results for dynamic finite element structural analysis. However, dynamic behavior of a structure may include unpredictably large strains in some parts of the structure, and using the initial mesh throughout the duration of a dynamic analysis may include some elements to go through strains beyond the elements' reliable limits. Thus, the finite element mesh for a dynamic analysis must be dynamically adaptive, and considering the rapid process of analysis in real time, the dynamically adaptive finite element mesh generating schemes must be computationally efficient. In this paper, a computationally efficient dynamically adaptive finite element mesh generation scheme for dynamic analyses of structures is described. The concept of representative strain value is used for error estimates and the refinements of meshes use combinations of the h-method(node movement) and the r-method(element division). The shape coefficient for element mesh is used to correct overly distorted elements. The validity of the scheme is shown through a cantilever beam example under a concentrated load with varying values. The example shows reasonable accuracy and efficient computing time. Furthermore, the study shows the potential for the scheme's effective use in complex structural dynamic problems such as those under seismic or erratic wind loads.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.362-367
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• 2008

Recently, the use of biaxial hollow slab is increased to reduce noise and vibration of the floor slab. Therefore, an efficient method for the vibration analysis of biaxial hollow slab is required to describe dynamic behavior of biaxial hollow slab. A finite element analysis is one of the method to analyze the biaxial hollow slab. It is necessary to use a refined finite element model for an accurate analysis of a floor slab with an effects of the hollow shape. But it would take a significant amount of computational time and memory if the entire building structure were subdivided into a finer mesh. Thus the proposed method uses equivalent plate model in this study. Dynamic analyses of an example structure subjected to walking loads were performed to verify the efficiency and accuracy of the proposed method.

• Proceedings of the KIEE Conference
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• 1999.07g
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• pp.2911-2913
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• 1999

This paper suggest an optimal identification method to complex and nonlinear system modeling that is based on Fuzzy-Neural Network(FNN). The FNN modeling implements parameter identification using HCM algorithm and optimal identification algorithm structure combined with two types of optimization theories for nonlinear systems, we use a HCM Clustering Algorithm to find initial parameters of membership function. The parameters such as parameters of membership functions, learning rates and momentum coefficients are adjusted using optimal identification algorithm. The proposed optimal identification algorithm is carried out using both a genetic algorithm and the improved complex method. Also, an aggregate objective function(performance index) with weighted value is proposed to achieve a sound balance between approximation and generalization abilities of the model. To evaluate the performance of the proposed model, we use the time series data for gas furnace, the data of sewage treatment process and traffic route choice process.

• Journal of Korea Society of Digital Industry and Information Management
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• v.15 no.2
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• pp.11-17
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• 2019

As interest in the efficiency use of energy has been recently rising, studies have been performed in utilizing various types of eco-friendly green energy and natural energy. Especially there has been rapidly increase in the fields using ESS (Energy Storage System), which is the technology for storing the energy from nature. The application fields of ESS is continuously growing and expanding to various types of technologies. However, in recent years there have been continuing problems with the safety of ESS. And related researches are going on. In this paper, we has proposed a system structure to utilize more secure ESS and has monitored the system status of ESS in real time by using smart phone app. This paper has also proposed a new method to configure secure ESS by implementing GUI (Graphical User Interface) to control the system. And then explain experimental results to investigate the efficiency of the proposed ESS.