• International Journal of Concrete Structures and Materials
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• v.9 no.3
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• pp.345-367
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• 2015

Past earthquakes have signaled the increased collapse vulnerability of mainshock-damaged bridge piers and urgent need of repair interventions prior to subsequent cascading hazard events, such as aftershocks, triggered by the mainshock (MS). The overarching goal of this study is to quantify the collapse vulnerability of mainshock-damaged substandard RC bridge piers rehabilitated with different repair jackets (FRP, conventional thick steel and hybrid jacket) under aftershock (AS) attacks of various intensities. The efficacy of repair jackets on post-MS resilience of repaired bridges is quantified for a prototype two-span single-column bridge bent with lap-splice deficiency at column-footing interface. Extensive number of incremental dynamic time history analyses on numerical finite element bridge models with deteriorating properties under back-to-back MS-AS sequences were utilized to evaluate the efficacy of different repair jackets on the post-repair behavior of RC bridges subjected to AS attacks. Results indicate the dramatic impact of repair jacket application on post-MS resilience of damaged bridge piers-up to 45.5 % increase of structural collapse capacity-subjected to aftershocks of multiple intensities. Besides, the efficacy of repair jackets is found to be proportionate to the intensity of AS attacks. Moreover, the steel jacket exhibited to be the most vulnerable repair intervention compared to CFRP, irrespective of the seismic sequence (severe MS-severe or moderate AS) or earthquake type (near-fault or far-fault).

• Journal of Korean Elementary Science Education
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• v.29 no.4
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• pp.401-413
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• 2010

This study analyzed the kinds and frequencies of descriptors in 154 articles in ERIC data base on the 4th day of January in 2010. The titles of the articles includes the words, 'scientific literacy'. As each descriptor is constituted of two words and over, in this study the first word in the descriptor was defined as 'restrictive word' and the rest word(s) as 'target word(s)'. The results are as follows. First, the descriptors which show high frequencies of target words are the traditionally important themes of scientific literacy education. Target words which show relatively high frequency are 'education', 'literacy', 'instruction' and 'countries'. Low frequency word is 'curriculum', which has various restrictive words and represents wide differentiation. Second, among the descriptors which show low frequencies of target words, relatively high frequency descriptors are '(and)society', 'change', 'secondary education', 'concepts', and 'biology', which have been given more attention in scientific literacy research than the rest descriptors. Third, the number of the descriptors that shows largely distributed pattern A, which happens over 15 years continuously, is over the half of all analyzed descriptors, which shows that they have been the major objectives in researches about scientific literacy. Most descriptors of pattern A shows normal distribution of frequency or the trends of increasing frequency as the time is nearer. Fourth, The descriptors are divided into four groups according to the time span. Each research trends are as follows. In later 80s, the research which emphasizes the importance of the sociality and technology in all level school science curriculum. In later 90s the research for educational change of inquiry-centered science curriculum which considers technological literacy in social contexts. In earlier 2000s the research that scientists and science teachers develop science curricula mostly related to scientific principles and thinking in chemistry and biology especially. In later 2000s case studies which relates teaching methods and science process activities to students' attitudes, scientific concepts and curricula.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.217-220
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• 2006

The lift and drag forces produced by a wing of a given cross-sectional profile are dependent on the wing planform and the angle of attack. Aspect ratio is the ratio of the wing span to the average chord. For conventional fixed wing aircrafts, high aspect ratio wings produce a higher lift to drag ratio than low ones for flight at subsonic speeds. Therefore, high aspect ratio wings are used on aircraft intended for long endurance. However, birds and insects flap their wings to fly in the air and they can change their wing motions. Their wing motions are made up of translation and rotation. Therefore, we tested flapping motions with parameters which affect rotational motion such as the angle of attack and the wing beat frequency. The half elliptic shaped wings were designed with the variation of aspect ratio from 4 to 11. The flapping device was operated in the water to reduce the wing beat frequency according to Reynolds similarity. In this study, the aerodynamic forces, the time-averaged force coefficients and the lift to drag ratio were measured at Reynolds number 15,000 to explore the aerodynamic characteristics with the variation of aspect ratio. The maximum lift coefficient was turned up at AR=8. The mean drag coefficients were almost same values at angle of attack from $10^{\circ}$ to $40^{\circ}$ regardless of aspect ratio, and the mean drag coefficients above angle of attack $50^{\circ}$ were decreased according to the increase of aspect ratio. For flapping motion the maximum mean lift to drag ratio appeared at AR=8.

• Journal of the Korean Society of Costume
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• v.59 no.10
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• pp.68-84
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• 2009

A state wedding ceremony of kings and crown princes in the Chosun Dynasty was systemically formalized in a book Five National Ceremonies (1474) as one of the five major formal events of the royal auspicious ceremonies(Ga-rae). For a state wedding, Ga-rae Protocol was made by a devision for Ga-rae temporarily established for the occasion. A total number of auspicious ceremony protocols of kings and crown princes amounts to 20 in the span of 279 years. Among the proposals, the wedding of Soon-jong in the Imo Year of 1882 is described most thoroughly. Nap-bin-ui(reception of bride) comprises six rituals which are nap-chae, nap-jing, go-gyi, chaek-bin, chin-young, and dong-ryae. A grand formal costume of the crown prince is granted based on the 'Seven Parts Formal Costume' of the first year of the king Moon-jong in 1450 together with an official costume for crown prince(Gon-myeon-chil-jang) arranged in the third year of the king Young-rak. In the royal palace of the Chosun Dynasty, the granted formal costume of the crown prince is officially recorded as a code and presented in a Gwon-ji-il section of the Formalities of the Five National Ceremonies. The formal costume and its accessory set for the crown prince recorded as a code are described in Sangbang Jeong-ryae as the formal costume of the crown prince section published by the king's request at the high senate commission in the 28th year of the king Young-jo in 1752. The aim of the study is to investigate the formal costume of the crown prince as an auspicious ceremonial costume worn at the wedding in the year of Imo.

• The Journal of the Korea Contents Association
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• v.11 no.1
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• pp.422-428
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• 2011

This paper presents results from the theoretical analysis of the lateral load distribution for a railway bridge designed with PSC girders which is one of most popular types of bridge in Korea. Typically, 3 sets of intermediate cross beams within a span have been installed for lateral load distribution. In this paper, the effect on the lateral load distribution by the number of intermediate cross beams were examined by both simple grillage analysis and finite element method. This study showed that at least, one set of cross beams at midspan should be needed to ensure the proper load distribution. However, the effect of cross beams on the load distribution becomes not significant though more than one set of cross beams are installed. Therefore, only one set of cross beans at midspan is recommended for constructibility and economic efficiency.

• The Journal of the Korea institute of electronic communication sciences
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• v.7 no.2
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• pp.263-269
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• 2012

Code-Division Multiple-Access(CDMA) allows several users simultaneous access to a common channel by assigning a distinct pseudonoise sequence called spectrum code to each user. Each user in a CDMA system uses a assigned spectrum code to modulate their signal. Choosing the codes used to modulate the signal is very important in the performance of CDMA systems. The best performance will occur when there is good separation between the signal of a desired user and the signals of other users. The receiver synchronizes the code to recover the data. The use of an independent code allows multiple users to access the same frequency band at the same time. In this paper we propose a generalized model of non-linear binary sequence using trace function and analyze cross-correlation of these sequences. These sequences with low correlation, large linear span and large family size, in a direct-sequence spread spectrum communication system, help to minimize multiple access interference, increase security degree of system and enlarge user number.

• Structural Engineering and Mechanics
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• v.60 no.4
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• pp.567-594
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• 2016

The main objective of the current research is estimating the flexural behavior of ferrocement Ribbed Plates reinforced with composite material. Experimental investigation was carried out on fifteen plates; their dimensions were kept constant at 1200 mm in length, 600 mm width and 100 mm thick but with different volume fraction of steel reinforcement and number of ribs. Test specimens were tested until failure under three line loadings with simply supported conditions over a span of 1100 mm. Cracking patterns, tensile and compressive strains, deformation characteristics, ductility ratio, and energy absorption properties were observed and measured at all stages of loadings. Experimental results were compared to analytical models using ANSYS 10 program. Parametric study is presented to look at the variables that can mainly affect the mechanical behaviors of the model such as the change of plate length. The results showed that the ultimate strength, ductility ratio and energy absorption properties of the proposed ribbed plates are affected by the volume fraction and the type of reinforcement, and also proved the effectiveness of expanded metal mesh and woven steel mesh in reinforcing the ribbed ferrocement plates. In addition, the developed ribbed ferrocement plates have high strength, ductility ratio and energy absorption properties and are lighter in weight compared to the conventional RC ribbed plates, which could be useful for developed and developing countries alike. The Finite Element (FE) simulations gave good results comparing with the experimental results.

• Journal of computational fluids engineering
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• v.21 no.3
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• pp.98-109
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• 2016

The flow and heat transfer characteristics of a heat exchanger having rectangular pin-fin in the flow direction have been investigated numerically. On the bottom plate, the convective boundary conditions for the hot side was given, and the fins were arranged in a channel-type geometric model using the periodic boundary condition in the span-wise direction. Three-dimensional numerical calculations for the flow and conjugate heat transfer problem were conducted using SIMPLE algorithm and $k-{\varepsilon}$ turbulence model. For the slanted pin-fin models, it was found that the downward cooling flow is generated due to the downward pressure gradient component, which can enhance the heat transfer performance near the bottom surface and the fin stem region. Four different inclined angles were considered in the Reynolds number range of 13,500-55,000. The aero-thermal performance of the slanted pin-fin heat exchangers, such as the volume and area goodness factors, were summarized and compared with the baseline plate-fin type heat exchanger quantitatively.

• Journal of Korea Multimedia Society
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• v.16 no.5
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• pp.657-666
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• 2013

Today, many aspects of our lives are characterized by the rapid influx of large amounts of data from various application domains. The applications that produce this massive of data span a large spectrum, from social media to business intelligence or biology. This massive influx of data necessitates large scale parallelism for efficiently supporting a large class of analysis tasks. Recently, there have been extensive studies in using MapReduce framework to support large parallelism. While this technique has produced impressive results in diverse applications, the same can not be said for multimedia applications where most of users are interested in a small number of results having high or low score. Thus, in this paper, we develop the data partitioning algorithm which is able to efficiently process large data set having different data utility. The experiment results show that the proposed technique provides significant execution time gains over the existing solution.

• The Journal of Society for e-Business Studies
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• v.16 no.2
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• pp.19-37
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• 2011

With the advancement of Internet, electronic commerce has rapidly expanded and considered as a major retail channel. In the early days of the Internet, many studies compared offline and online stores on their price level and dispersion. Since e-commerce is considered matured, we need to see price change behavior in e-commerce rather than comparing it with traditional channels. Thus, this study investigated the trend of price changes in e-commerce. The data that was gathered from a price comparison site also contained six product categories. The decrease in minimum and average price was identified and the increase in maximum price was also identified. The critical factors in the increase of maximum price are number of sellers (positive effect) and the time span after a product was released (negative effect). The differences in price changes between product categories were also investigated.