• Journal of the Korean Society of Safety
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• v.27 no.1
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• pp.26-31
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• 2012

Wood-plastic composites represents a growing class of materials used by the residential construction industry and furniture industry. In this study, the effect of flame retardants on the flammability and mechanical properties of wood flour-high density polyethylene(HDPE) composites were studied. we were manufactured wood flour-HDPE composites by modular intermeshing co-rotating twin screw extruder with L/D ratio of 42. The flame retardant properties were used limiting oxygen index(LOI) and mechanical properties were measured by universal testing machine(UTM). The Morphological analysis of composites were analyzed by Scanning electron microscope(SEM). It was found that Ammonium polyphosphate can effectively reduce the flammability of the wood flour-HDPE composites. Marginal reduction in the mechanical properties of the composites was found with addition of flame retardants. SEM images showed that the coupling agent improved wood flour-HDPE interfacial bonding.

• Journal of the Korean Society of Safety
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• v.25 no.1
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• pp.57-61
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• 2010

Formwork is a temporary structure that supports its weight and that of fresh concrete as well as construction live loads. Scaffoling is a temporary frame used to support people and material in the construction or repair of buildings and other large structures. It is usually a modular system of metal pipes, although it can be made out of other materials. Bamboo is still used in some Asian countries like China. The purpose of a working scaffold is to provide a safe place of work with safe access suitable for the work being done. In construction site, steel pipes are usually used as scaffolds. In this study, scaffolding systems which is changed according to sleeper and joist space were measured by buckling test. Buckling load of respective scaffolding system was analyzed by structural analysis program(MIDAS). Buckling load of scaffold with/without wall connection and footboard was got by test and structural analysis. According to these results，we know that scaffolding system of case 3 is suitable. Buckling load of scaffold with wall connection is higher than without wall connection. So wall connection is important in scaffoling systems. Footboard in the scaffolding systems is not effective against promotion of buckling load. Finally, the present study results will be used to design scaffolding systems safely in the construction sites.

• The Plant Pathology Journal
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• v.26 no.3
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• pp.209-215
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• 2010

Plant pathogenic oomycetes, such as Phytophthora spp., are the causal agent of the most devastating plant diseases. During infection, these pathogens accomplish parasitic colonization of plants by modulating host defenses through an array of disease effector proteins. These effectors are classified in two classes based on their target sites in the host plant. Apoplastic effectors are secreted into the plant extracellular space, and cytoplasmic effectors are translocated inside the plant cell, through the haustoria that enter inside living host cell. Recent characterization of some oomycete Avr genes showed that they encode effector protein with general modular structure including N-terminal conserved RXLR-DEER motif. More detailed evidences suggest that these AVR effectors are secreted by the pathogenic oomycetes and then translocated into the host plant cell during infection. Recent findings indicated that one of the P. infestans effector, Avrblb2, specifically induces hypersensitive response (HR) in the presence of Solanum bulbocastanum late blight resistance genes Rpi-blb2. On the other hand, another secreted RXLR protein PexRD8 originated from P. infestans suppressed the HCD triggered by the elicitin INF1. In this review, we described recent progress in characterized RXLR effectors in Phytophthora spp. and their dual functions as modulators of host plant immunity.

• Journal of Convergence for Information Technology
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• v.7 no.3
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• pp.65-71
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• 2017

The quantum logic was introduced by G. Birkhoff and 1. von Neumann in order to study projections of a Hilbert space for a formulation of quantum mechanics, and Husimi proposed orthomodular law and orthomodular lattices to complement the quantum logic. Abott introduced orthoimplication algebras and its properties to investigate an implication of orthomodular lattice. The commuting relation is an important property on orthomodular lattice which is related with the distributive law and the modular law, etc. In this paper, we define a binary operation on orthoimplication algebra and the greatest lower bound by using this operation and research some properties of this operation. Also we define a homomorphism and characterize the commuting relation of orthoimplication algebra by the homomorphism.

• Journal of Power Electronics
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• v.16 no.2
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• pp.553-563
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• 2016

This paper presents a digital hardware implementation of a real-time simulator for a multiphase drive using a field-programmable gate array (FPGA) device. The simulator was developed with a modular and hierarchical design using very high-speed integrated circuit hardware description language (VHDL). Hence, this simulator is flexible and portable. A state-space representation model suitable for FPGA implementations was proposed for a dual three-phase induction machine (DTPIM). The simulator also models a two-level 12-pulse insulated-gate bipolar transistor (IGBT)-based voltage-source converter (VSC), a pulse-width modulation scheme, and a measurement system. Real-time simulation outputs (stator currents and rotor speed) were validated under steady-state and transient conditions using as reference an experimental test bench based on a DTPIM with 15 kW-rated power. The accuracy of the proposed digital hardware implementation was evaluated according to the simulation and experimental results. Finally, statistical performance parameters were provided to analyze the efficiency of the proposed DTPIM hardware implementation method.

• Korean Institute of Interior Design Journal
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• v.23 no.4
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• pp.42-51
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• 2014

The research aims to analyze the structural meaning of mobility design on 'Furnitecture' with the works of Andrea Zittel. The study consists of the literature review and the analysis of Zittel's works. The framework for the analysis is divided into four steps: identification of visual forms/structure/function, analysis of the principles of delivering the concept of mobility, interpretation & synthesis of the relational meanings derived from the concepts of mobility, and evaluation of Zittel's tendency toward design/social background/design history, etc. Total fifteen cases are selected from Zittel's works, and each case is analyzed following the above steps. The finding shows that Zittel likes to play with geometrical forms, grid & modular system to create a minimum space for living equipped with critical furnishing. Secondly, Zittel's works deliver the concept of mobility by applying movability, adaptation, combination and transformation. Thirdly, through the concepts of mobility, Zittel reflects the ideas of high efficiency and functionalism, harmony with natural environment, search for liberty, simple & humble life and success of the designers of American modernism. Finally, it is found that modernism from the era of Bauhaus, utopian values derived from constructionism, utilitarianism inspired by Shakers and homestead act & mobile home/capsule unit suggested since 19th century in America mainly affect Zittel's works to reflect the dynamic concepts of mobility through the design of furnitecture.

• Journal of the Korean housing association
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• v.23 no.4
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• pp.41-48
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• 2012

The purpose of the study, approaching from the aspect of the construction technologies, is to determine the architectural techniques of traditional wood architects in existence, through which the systems and techniques that create the inherent characteristics of Korean Architecture are clarified. With understanding traditional construction system and focusing on the fact that built environment results from the consistent standards and technologies of architects, this study inquires into the systematic standard and its formation that present in the process of planning for the overall scale and shape of a building from the following (four) perspectives. The study determines the characteristics of '間(Kan)' (unit; fundamental unit that measures Korean traditional houses) and the methods of columns disposition of which the '間 (Kan)' is made up. Once the necessary spaces are decided according to the size of a building, then floor plans are drawn with the standard unit, '間(Kan)'. The '間(Kan)', as a modular unit, is not only composing the floor plans, but also functioning as an Area unit, Space unit and Structural unit. Composition of '間(Kan)' varies with disposition of columns, and therefore multiform of floor and spaces are created. In this study, the '間(Kan)', as a standard unit, is used in the form of specific size and area, and it is demonstrated how the floor plans are developed by organizing the columns in accordance with the spaces requested.

• Journal of Communications and Networks
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• v.17 no.2
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• pp.100-109
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• 2015

Mobile phone carriers face challenges from three synergistic dimensions: Wireless, social, and mobile. Despite significant advances that have been made about social networks and human mobility, respectively, our knowledge about the interplay between two layers remains largely limited, partly due to the difficulty in obtaining large-scale datasets that could offer at the same time social and mobile information across a substantial population over an extended period of time. In this paper, we take advantage of a massive, longitudinal mobile phone dataset that consists of human mobility and social network information simultaneously, allowing us to explore the impact of human mobility patterns on the underlying social network. We find that human mobility plays an important role in shaping both local and global structural properties of social network. In contrast to the lack of scale in social networks and human movements, we discovered a characteristic distance in physical space between 10 and 20 km that impacts both local clustering and modular structure in social network. We also find a surprising distinction in trajectory overlap that segments social ties into two categories. Our results are of fundamental relevance to quantitative studies of human behavior, and could serve as the basis of anchoring potential theoretical models of human behavior and building and developing new applications using social and mobile technologies.

• Journal of Power Electronics
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• v.10 no.6
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• pp.673-679
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• 2010

Input-series-output-parallel (ISOP) connected DC-DC converters enable low voltage rating switches to be used in high voltage input applications. In this paper, a DSP is adopted to generate digital phase-shifted PWM signals and to fulfill the closed-loop control function for ISOP connected two full-bridge DC-DC converters. Moreover, a stable output current sharing control strategy is proposed for the system, with which equal sharing of the input voltage and the load current can be achieved without any input voltage control loops. Based on small signal analysis with the state space average method, a loop gain design with the proposed scheme is made. Compared with the conventional IVS scheme, the proposed strategy leads to simplification of the output voltage regulator design and better static and dynamic responses. The effectiveness of the proposed control strategy is verified by the simulation and experimental results of an ISOP system made up of two full-bridge DC-DC converters.

• Tribology and Lubricants
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• v.38 no.2
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• pp.70-72
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• 2022

In this study, we report on a power system developed as a decelerator for a driving module in an electric vehicle. The system is to be mounted in a limited space. The research focus was on development of miniaturization, light weight, and high power density. In particular, we aimed to minimize the layout of existing external components as integrated or built-in, and to maximize the power density by applying optimal cooling technology to increased requirements for developing modular power systems applicable to various OEM models. South Korean automakers ranked fourth in global electric-vehicle sales in 2020, but domestic sales are relatively slow. Despite government's expansion in subsidies for eco-friendly cars, consumers are delaying purchases after 2021 considering the cost-effectiveness of electric vehicles. In major European markets, the demand for electric vehicles exceeded the demand for diesel cars, and sales of hybrid cars, which used to represent eco-friendly cars, are slowing down as Toyota, started selling electric vehicles. In this study, the internal lubrication characteristics of a decelerator installed in an electric vehicle were analyzed in terms of the deceleration time while driving. By selecting the proper oil and oil viscosity, it was confirmed that there is no problem in lubricating the bearings and gears of the decelerator.