• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.885-890
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• 2002

Pseudo dynamic test is an on-line computer control method to achieve the realism of shaking table test with the economy and versatility of the conventional quasi-static approach. Pseudo dynamic tests of four full-size RC bridge piers have been carried out to investigate their seismic performance. For the purpose of precise evaluation, the experimental investigation was conducted to study the seismic performance of the real size specimen, which is constructed for highway bridge piers in Korean peninsula. Since it is believed that Korea belongs to the moderate seismicity region, three test specimens were designed in accordance with limited ductility design concept. Another one test specimen was nonseismically designed according to a conventional code. Important test parameters were transverse reinforcement and lap splicing. Lap splicing was frequently used in the plastic hinge region of many bridge columns. Furthermore, the seismic design code is not present about lap splice in Korean Roadway Bridge Design Code. The results show that specimens designed according to the limited ductility design concept exhibit higher seismic resistance. Specimens with longitudinal steel lap splice in the plastic hinge region appeared to significantly fail at low ductility level.

• ETRI Journal
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• v.42 no.2
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• pp.205-216
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• 2020

An arbiter physical unclonable function (APUF) has exponential challenge-response pairs and is easy to implement on field-programmable gate arrays (FPGAs). However, modeling attacks based on machine learning have become a serious threat to APUFs. Although the modeling-attack resistance of an MA-APUF has been improved considerably by architecture modifications, the response generation method of an MA-APUF results in low uniqueness. In this study, we demonstrate three design problems regarding the low uniqueness that APUF-based strong PUFs may exhibit, and we present several foundational principles to improve the uniqueness of APUF-based strong PUFs. In particular, an improved MA-APUF design is implemented in an FPGA and evaluated using a well-established experimental setup. Two types of evaluation metrics are used for evaluation and comparison. Furthermore, evolution strategies, logistic regression, and K-junta functions are used to evaluate the security of our design. The experiment results reveal that the uniqueness of our improved MA-APUF is 81.29% (compared with that of the MA-APUF, 13.12%), and the prediction rate is approximately 56% (compared with that of the MA-APUF (60%-80%).

• Geomechanics and Engineering
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• v.33 no.5
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• pp.453-462
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• 2023

Intermediate Geomaterials (IGMs) are natural formation materials that exhibit the engineering behavior (strength and compressibility) between soils and rocks. The engineering behavior of such material is highly unpredictable as the IGMs are stiffer than soils and weaker/softer than rocks. Further, the characterization of such material needs exposure to both soil and rock mechanics. In most conventional designs of geotechnical structures, the engineering properties of the IGMs are either aligned with soils or rocks, and this assumption may end up either in an over-conservative design or under-conservative design. Hence, many researchers have attempted to evaluate its actual engineering properties through laboratory tests. However, the test results are partially reliable due to the poor core recovery of IGMs and the possible sample disturbance. Subsequently, in-situ tests have been used in recent years to evaluate the engineering properties of IGMs. However, the respective in-situ test finds its limitations while exploring IGMs with different geological formations at deeper depths with the constraints of sampling. Standard Penetration Test (SPT) is the strength-based index test that is often used to explore IGMs. Moreover, it was also observed that the coefficient of variation of the design parameters (which represents the uncertainties in the design parameters) of IGMs is relatively high, and also the studies on the probabilistic characterization of IGMs are limited compared with soils and rocks. With this perspective, the present article reviews the laboratory and in-situ tests used to characterize the IGMs and explores the shear strength variation based on their geological origin.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.4
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• pp.55-66
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• 1991

Presented is a study on the realistic determination of design loads and design criteria for bridge structures. The current bridge design code does not consider realistically the uncertainties inherent in loads and resistances and thus the level of safety varies greatly among the bridge spans. The resonable bridge design loads and design criteria which exhibit uniform reliability among various bridge spans are therefore derived in the present paper. The proposed design loads are determined from the analysis of numerous data obtained from actual traffic survey and the design criteria are based on the advanced concept of load and resistance factor format. The live load factors take into account resonably the effects of traffic volume increase. The proposed design loads and design criteria show uniform safety level for various bridge spans and reasonably consider the effects of traffic volume increase. The present study provides useful and valuable data for new version of our bridge design code.

• Earthquakes and Structures
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• v.19 no.5
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• pp.395-409
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• 2020

With verifications through many relevant researches in the past few decades, adopting the equivalent lateral force procedure for designing seismically isolated structures as a preliminary or even final design approach has become considerably mature and publicly acceptable, especially for seismic isolation systems that mechanically exhibit bilinear hysteretic behavior. During the design procedure, in addition to a given seismic demand, structural designers still need to previously determine three parameters, such as mechanical properties of seismic isolation systems or design parameters and performance indices of seismically isolated structures. However, an arbitrary or improper selection of given parameters might cause diverse or even unacceptable design results, thus troubling structural designers very much. In this study, first, based on the criterion that at least either two design parameters or two performance indices of seismically isolated structures are decided previously, the rationality and applicability of design results obtained from different conditions are examined. Moreover, to consider variations of design parameters of seismically isolated structures attributed to uncertainties of mechanical properties of seismic isolation systems, one of the conditions is adopted to perform bounding analysis for seismic isolation design. The analysis results indicate that with a reasonable equivalent damping ratio designed, considering a specific variation for two design parameters (the effective stiffness and equivalent damping ratio) could present more conservative bounding design results (in terms of isolation displacement and acceleration transmissibility) than considering the same variation but for two mechanical properties (the characteristic strength and post-yield stiffness).

• Korean Institute of Interior Design Journal
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• v.26 no.5
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• pp.135-142
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• 2017

Recently, as human-centered design and humanization of space accelerates, the concept of physical space is changing to user-centered space. In particular, in the case of exhibition space to utilize digital media, visitors' actively experiencing exhibits and participating exhibition are regarded as an important factor, thus affordance design serves as a crucial factor to afford satisfaction with exhibition space to the visitors. Accordingly, the study is to understand the concept of the affordance and the digital media exhibition environment and to analyze the preference for each affordance design factor in the digital exhibition environment. The survey is conducted to people in the twenties who inhabit Seoul and the metropolitan area, familiar with the digital media. The results of the survey show that the most important role of the digital media in the exhibition environment is to create the atmosphere for concentration and complexity is the most preferable among interactivity, network ability and complexity, the feature of the digital media. Additionally, the results reveal that cognitive affordance presenting the feature of design to help the user when he/she want to know something is the most preferable among sensory affordance, physical affordance, cognitive affordance and functional affordance and as the time exposed to the digital media increases the importance of the affordance design is high. As the digital environment is common now in many fields, it will be regarded as a crucial factor to the visitors of an exhibit hall from now on whether affordance design is used.

• Journal of Fashion Business
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• v.23 no.1
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• pp.49-63
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• 2019

The purpose of this study is to examine the characteristics of modular design observed in Korean traditional clothing. Modular design, which is one of the noticeable characteristics of modern fashion design emerged in the 20th century. This study analyzed the Korean traditional culture to investigate the characteristics that show similarities to the modular system in design. A traditional Korean house is composed of small structures called 'chae'. A traditional Korean building is composed of a basic unit space called 'kan', and the rooms are divided and recombined. Korean traditional interior design shows furniture, bedding and art works that could be used, folded then stored. Korean cuisine is served in combination with small dishes. Korean letters are combined in square shaped form to make writing and printing easy. Korean traditional clothing has a way of washing where clothing are disassembled, washed and then re-stitched. The pattern pieces are made to be rectangular shaped so that the fabric pieces can be kept in shape during washing. The rectangular shaped pattern pieces can be replaced and reused after washing. Tops and bottoms could be interchanged for color-coordination, because the shapes of the clothing were standardized. These features exhibit modular system in Korean traditional clothing design. Modular system design has common characteristics which have basic modules, pursue practical purpose, have interchangeability adapted to circumstances, and could be disassembled and re-combined. Korean traditional clothing illustrates different ways of practicing modular system, but has some common features to contemporary modular fashion design.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2017.04a
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• pp.110-110
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• 2017

Biological systems offer unique principles for the design and fabrication of engineering platforms (i.e., popularly known as "Biomimetics") for various applications in many fields. For example, the lotus leaves exhibit unique surfaces consisting of evenly distributed micro and nanostructures. These unique surfaces of lotus leaves have the ability of superhydrophobic property to avoid getting wet by the surrounding water (i.e., Lotus effect). Inspired by the surface topographies of lotus leaves, the artificial superhydrophobic surfaces were developed using various micro- and nanoengineering. Here, we propose new platforms that can control hydrophilic and hydrophobic property of surfaces by mimicking micro- and nanosurfaces of various natural leaves such as common camellia, hosta plantaginea, and lotus. Using capillary force lithography technology and polymers in combination with biomimetic design principle, the unique micro- and nanostructures mimicking natural surfaces of common camellia, hosta plantaginea, and lotus were designed and fabricated. We also demonstrated that the replicated polymeric surfaces had different hydrophilic and hydrophobic properties according to the mimicking the natural leaf surfaces, which could be used as a simple, but powerful methodology for design and fabrication of controlled hydrophilic and hydrophobic platforms for various applications in the field of agriculture and biological engineering.

• Computers and Concrete
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• v.26 no.3
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• pp.293-307
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• 2020

The aim of this paper is to develop design-oriented models for the prediction of the ultimate strength and ultimate axial strain for concrete confined with glass fiber-reinforced polymer (GFRP) wraps. Twenty of most used and recent design-oriented models developed to predict the strength and strain of GFRP-confined concrete in circular sections are selected and evaluated basing on a database of 163 test results of concrete cylinders confined with GFRP wraps subjected to uniaxial compression. The evaluation of these models is performed using three statistical indices namely the coefficient of the determination (R²), the root mean square error (RMSE), and the average absolute error (AAE). Based on this study, new strength and strain models for GFRP-wrapped concrete are developed using regression analysis. The obtained results show that the proposed models exhibit better performance and provide accurate predictions over the existing models.

• The Research Journal of the Costume Culture
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• v.11 no.3
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• pp.340-351
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• 2003

The purpose of this study was to examine the effect of clothing type and hair style on men’s impression formation. The experimental design was 4×2×2×2 (clothing type×hair style×perceiver’s age×perceiver’s role) factorial design with between-subjects design. The stimuli of color photographs of male in his 20's model and semantic differential scale were used. The data were obtained from questionnaires completed by 881 men and women in the metropolitan area of Seoul. The SPSS package was used for data analysis which includes factor analysis, t-test, and Cronbach’s a to measure the reliability. This study showed the following results. Four factors were derived to account for the dimensions of impression formation. These were dignity, activity, individual character, and social intercourse. Men evaluated individual character factor higher than women did. Dignity factor was evaluated higher by students, while social intercourse factor was evaluated higher by office workers. The clothing type of shirts/pants was evaluated to be more active and more sociable than of jacket/pants. Men wanted to exhibit natty image and women did elegant image through clothes.