• Proceedings of the Korean Institute of Interior Design Conference
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• 2006.05a
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• pp.131-134
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• 2006

This study aims to inspect changes of physical expression in surfaces of both building interior and exterior in contemporary architecture. Nowadays society has transformed into more complicated framework with the development of the new media and digital technology in 21 century. Surface's expressivity has been changed with design trend and material development. Although surface study has been mainly concentrated on properties of materials and structure characters, new technology and cultural acceptance enables it extend itself to a new area with various design methods, taking its place as an important contemporary architectural element. Interior surface design is expressed with several unique methods such as optical illusion, surface exposure and spacial depth and volume, and it created dynamic space within the surface itself. In case of exterior surface, whole space seems to be designed to be coordinated with structured optical illusion as well as symbolic expression. Surface's area is extends itself with the stream of the times. This study explored the nature of surfaces with categorizing and comparing them in a various views and methods.

• Earthquakes and Structures
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• v.12 no.1
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• pp.55-65
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• 2017

Earthquake resilience of substations is essential for reliable and sustainable service of electrical grids. The majority of substation equipment consists of cylindrical porcelain components, which are vulnerable to earthquake shakings due to the brittleness of porcelain material. Failure of porcelain equipment has been repeatedly observed in recent earthquakes. Hence, proper seismic modelling of porcelain equipment is important for various limit state checks in both product manufacturing stage and detailed substation design stage. Sheds on porcelain core and cemented joint between porcelain component and metal cap have significant effects on the dynamic properties of the equipment, however, such effects have not been adequately parameterized in existing design guidelines. This paper addresses this critical issue by developing a method for taking these two effects into account in seismic modelling based on numerical and analytical approaches. Equations for estimating the effects of sheds and cemented joint on flexural stiffness are derived, respectively, by regression analyses based on the results of 12 pieces of full-scale equipment in 500kV class or higher. The proposed modelling technique has further been validated by shaking table tests.

• Journal of Adhesion and Interface
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• v.7 no.4
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• pp.60-64
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• 2006

In modern vehicle construction the search for means of weight reduction, improving durability, increasing comfort and raising body stiffness are issues of priority to the design engineer. The intelligent usage of many materials such as high strength steel, light-alloys and plastics enables a significant vehicle weight reduction to be achieved. The classical joining techniques used in the automobile industry need to be newly-evaluated since they often do not present workable solutions for such mixed-material connections, for example aluminium/steel. Calculation/simulation methods have made progress as a key factor for broader and more cost-effective implementation of structural bonding. This will lead to reduction of spotwelds and accelerate the car development. A special focus of the paper is the use of high strength steel grades. It will be shown that adhesive bonding is a key tool for yielding the potential of advanced high strength steel for low gauging without compromising the stiffness. The latest status of adhesive development has been described. Improvements with physical strength and glass temperature as well as of process relevant properties are shown. Also the situation regarding occupational hygiene is treated, showing that by further spotweld point reduction the emission around the working area can be even lowered against the current praxis. High performing lightweight design cannot longer do without high performing crash durable adhesives.

• Geotechnical Engineering
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• v.2 no.2
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• pp.29-36
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• 1986

In this study, a random vibration technique to anaiyze the vertical vibration of rigid circular footings on sand whose material properties are not previously determind is proposed. Total of 11 circular model footings varing mass ratio and radius are constructed for the vibration experim eat and the elastic half space is represented by compacted sand layer From the random vibration experiments, it is found that the technique suggested in this study gives more accurate prediction of circular footing behavior under vertical vibration than the simplified analog which assumes the subsoils as elastic half space. The predicted resonant frequene iris agree very well with the measured values from the slnusoidal vibration experiments. The ratio of the predicted resonant amplitudes to the measured values vary between 0.5 and 1,35 for the site used for the vibration experiments in this study.

• Journal of Electrochemical Science and Technology
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• v.2 no.2
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• pp.103-109
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• 2011

Nanocrystalline $LiFePO_4$ powders were prepared at 660-$670^{\circ}C$ in an Ar atmosphere using two different synthetic routes, solid-state and sol-gel. Both materials showed well-developed XRD patterns without any impurity peaks. Particles composed in the range of 200-300 nm from the solid-state method, and 50-100 nm from the sol-gel method, were confirmed through scanning electron microscopy and dynamic light scattering. The $LiFePO_4$ obtained by the sol-gel method offered a high discharge capacity (153 mAh/g) and stable discharge behavior, even at elevated temperatures (50 and $60^{\circ}C$), whereas poor electrochemical performance was observed from the solid-state method. Rate capability studies for sol gel-derived $LiFePO_4$ ranged from 0.2 to 30 C, which revealed excellent retention over 70 cycles with a 99.9% capacity.

• KIEAE Journal
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• v.9 no.2
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• pp.73-80
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• 2009

In the early twentieth century, many architects still practised eclectic design elements. Emergence of new building materials such as steel, concrete and glass were not yet found fresh roles in architectural design. It was Brussels that the use of modern materials gave rise to their new forms and gave influence to not only building skins but also spatial organization. Art Nouveau architecture is often seen as revolutionary and pioneering modern architecture against eclectic classicism prevalent in the 18th and 19th centuries. Despite the fact that some scholars point out that Art Nouveau is more a transient phenomenon than modern architecture proper, no one would deny that Art Nouveau carries a good deal of modern characteristics. This paper intends to show rather ambivalent perspectives upon Art Nouveau architecture. Although it insinuates overly dynamic nature in architectural languages, it does not hamper us from reading Art Nouveau as a vital component of modern architecture. Through a careful analysis of the early domestic designs of Victor Horta, it becomes evident that his work can provide modern architecture a meaningful alibi for its growth. Victor Horta's house design is well known to the public, both for his classical tastes and for its changing implementation. Horta's modern quality is never adequately recognized, partly due to his eye catching modern iron properties and sinuous ornamentation. This paper tries to offer an insight into the complicated stage set of the fin-de-$si{\grave{e}}cle$ through the work of Victor Horta whose influence has been immense in the making of modern architecture.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.938-941
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• 2001

A tool holder system has been designed and builted to measure cutting forces in diamond turning. This system design includes a 3-component piezo-electric tranducer. Initial experiments with tool holder system included verification of its predicted dynamic characteristics as well as a detailed study of cutting parameters. In this research, tool holder system is modeled by considering the element dividing, material properties, and boundary conditions using MSC/PATRAN. Mode and frequency analysis of structure is simulated by MSC/NASTRAN, for the purpose of developing the effective design. In addition, tool holder system is verified by vibration test using accelerometer. Many cutting experiments have been conducted on 6061-T6 aluminum. Tests have involved investigation of velocity effects, and the effects of depth and feedrate on tool force. Cutting velocity has been determined to have negligible effects between 4 and 21㎧.(6) Forces generally increase with increasing depth of cut. Increasing feedrate does not necessarily lead to higher forces. Results suggest that a sample model may not be sufficient to describe the forces produced in the diamond turning process.

• Steel and Composite Structures
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• v.8 no.2
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• pp.129-144
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• 2008

This paper demonstrates an application of the perturbation based stochastic finite element method (SFEM) for predicting the performance of structural systems made of composite sections with random material properties. The composite member consists of materials in contact each of which can surround a finite number of inclusions. The perturbation based stochastic finite element analysis can provide probabilistic behavior of a structure, only the first two moments of random variables need to be known, and should therefore be suitable as an alternative to Monte Carlo simulation (MCS) for realizing structural analysis. A summary of stiffness matrix formulation of composite systems and perturbation based stochastic finite element dynamic analysis formulation of structural systems made of composite sections is given. Two numerical examples are presented to illustrate the method. During stochastic analysis, displacements and sectional forces of composite systems are obtained from perturbation and Monte Carlo methods by changing elastic modulus as random variable. The results imply that perturbation based SFEM method gives close results to MCS method and it can be used instead of MCS method, especially, if computational cost is taken into consideration.

• 한국지구물리탐사학회:학술대회논문집
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• 2006.06a
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• pp.195-200
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• 2006

Laboratory creep experiments show that compaction of unconsolidated shale is an irrecoverable process caused by viscous time-dependent deformation. Using Perzyna's viscoplasticity framework combined with the modified Cam-clay theory, we found the constitutive equation expressed in the form of strain rate as a power law function of the ratio between the sizes of dynamic and static yield surfaces. We derived the volumetric creep strain at a constant hydrostatic pressure level as a logarithmic function of time, which is in good agreement with experimental results. The determined material constants indicate that the yield stress of the shale increases by 6% as strain rate rises by an order of magnitude. This demonstrates that the laboratory-based prediction of yield stress (and porosity) may result in a significant error in estimating the properties in situ.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2010.05a
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• pp.527-528
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• 2010

Previous experimental results performed by many researchers for a couple of decades in South Korea have shown that an absorbing sheet inserted in a conventional floating slab system for thermal insulation or vibration absorption may amplify the vibration of the slab system at specific frequency ranges depending on the material properties of the sheet. The amplified vibration, consequently, results in the heavy weight floor impact noise exceeding the sound level limit for an apartment house, 50dB. In this study, the amplification mechanism is examined through numerical analysis and a new slab system is proposed to reduce the amplification and control the noise. The new slab system consists of studs connecting the base slab and upper concrete finishing yielding the dramatically increased stiffness of the slab. The numerical simulation is performed to investigate the effect of the slab system with studs on the vibration and noise control. The results show that the performance of the slab is sensitive to the number and location of studs, and the heavy weight floor impact noise can be reduced up to 6-7dB compared to the conventional slab system at the optimal stud location.