• Journal of computational fluids engineering
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• v.11 no.2 s.33
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• pp.49-55
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• 2006

This study investigates the oscillatory thermal convection of a fluid with Pr=0.02 in a wide-gap horizontal annulus with constant heat flux inner wall. When Pr=0.02, dual steady-state flows are not found. After the first Hopf bifurcation from a steady to a time-periodic flow, five successive period-doubling bifurcations are recorded before chaos. The power spectrum shows the $period-2^4\;and\;2^5$ flows clearly, and a window of period $3{\times}2^3$ flow is found in the chaotic regime. The approximate value of the Feigenbaum number for the last three period-doubling bifurcations is 4.76. The transition route to chaos of the present simulations is consistent with the period-doubling route of Feigenbaum.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.49-55
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• 2007

The quality of chaotic mixing in three-dimensional micro channel flow has been numerically studied using Fractional-step method (FSM) and particle tracking techniques such as $Poincar{\acute{e}}$ section and Lyapunov exponents. The flow was driven by pressure distribution and the chaotic mixing was generated by applying alternating current to electrodes embedded on the bottom wall at a first half period and on the top wall at a second half period. The equations governing the velocity and concentration distributions were solved using FSM based on Finite Volume approach. Results showed that the mixing quality depended significantly on the modulation period. The modulation period for the best mixing performance was determined based on the mixing index for various initial conditions of concentration distribution. The optimal values of modulation period obtained by the particle tracking techniques were compared with those from the solution of concentration distribution equation using FSM and CFX software and the comparison showed their good match.

• Journal of the Korean Society of Costume
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• v.49
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• pp.85-94
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• 1999

The fabrics attached to the remains of the Okjeon old tomb in the Kaya period were examined. Most of fabrics examined were composed of hemp and silk. Considering that silk was found in the old tomb of the Kaya period in the late 5th century and that various kinds of silk were used in the other area silk was assumed to be used before 5th century in the Kaya period. Only the structure of the densely plain weaved fabrics were analysed as silk and the other physical properties of the fabrics could not be the examined fabrics were plain weaved and altered structure with twill and plain weaving were found indicating that diverse weaving structures were used in the Kaya period. This indicate a certain level of cultural exchange between Kaya and Silla PaikJae, Kokuryo and weaving technique were almost similar in the Korean peninsula in the 5th century.

• Geomechanics and Engineering
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• v.12 no.6
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• pp.949-963
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• 2017

The main purpose of the current study is to develop the new coefficients for consideration of soil-structure interaction effects to find the elevated tank natural period. Most of the recommended relations to find the natural period just assumed the fixed base condition of elevated tank systems and the soil effects on the natural period are neglected. Two different analytical systems considering soil-structure- fluid interaction effects are recommended in the current study. Achieved results of natural impulsive and convective period, concluded from mentioned models are compared with the results of a numerical model. Two different sets of new coefficients for impulsive and convective periods are developed. The values of the developed coefficients directly depend to soil stiffness values. Additional results show that the soil stiffness not only has significant effects on natural period but also it is effective on liquid sloshing wave height. Both frequency content and soil stiffness have significant effects on the values of liquid wave height.

• Journal of Sensor Science and Technology
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• v.26 no.6
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• pp.408-413
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• 2017

In this paper, we newly developed a byte-inverted transmission method for flicker-free visible light communication (VLC). The VLC transmitter sends original data in the former half period of the clock, and inverted data and in the latter half period of the clock. The VLC receiver receives the original data in the in the former half period of the clock. In this system, we used 480Hz clock that was generated from the 60Hz power line. The average optical power of the LED array in the transmitter is constant, thus flicker-free, in the observation time longer than the period of the clock that is about 2ms. This period is shorter than the maximum flickering time period (MFTP) of 5ms that is generally considered to be safe. This configuration is very useful in constructing indoor wireless sensor networks using LED light because it is flicker-free and does not require additional transmission channel for clock transmission.

• Journal of architectural history
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• v.1 no.2 s.2
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• pp.85-100
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• 1992

This Study is to analize the transfiguration of the domestic architecture in the process of modernization. Thirty two houses which were located in Taegu province and constructed during the period from 1886 to 1945, were surveyed and analized about the characteristic and their transfiguration. The modern domestic architecture of Taegu province had been constructed greatly by the missonaries and Japanes. The history of development of modern houses in Teagu province can be devided into three period in accordance with the economic policy, housing style and the method of construction. The first period (1886-1910) was the beginning of the modern house. Most of the mission houses of that period were made with brick structure of korean-western style or colonial style. In the second period (1911-1926), colonial, Japanese-western, Japanese housing style were co-exited in Teagu province. During the third period (1927-1945) new method of construction using reinforced concrete and mortar was introduced, therefore the houses become row house (a two or three-family house) and much simpler.

• Korean Institute of Interior Design Journal
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• no.41
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• pp.19-28
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• 2003

Residential space can be stated as a decisive body compositely affected by environmental, physical, social, and cultural influences. Resulting from this idea, residential space can be defined as a mirror reflecting peoples' life at that period. Therefore, it is possible to understand the social and cultural aspects of a certain era through analyzing the residential space built and used at that period. Viewing from this point, latter term of Chosun Period, as a transitional period, was a tie of collapse for the structure of middle-class society forcing its identity system to be reorganized, and of improving upon commerce, agriculture, and manual industry to enable modernization. Following this idea, the goal of this research is to analyze characteristics of higher middle class residences built at the close of 19th century in Gyeonggi province in order to bring into light the change of social structure of the period.

• Structural Monitoring and Maintenance
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• v.4 no.4
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• pp.351-364
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• 2017

In this study effects of various parameters like a number of bays, the stiffness of the structure along with the height of the structure was examined. The fundamental period of vibration T of the building is an important parameter for evaluation of seismic base shear. Empirical equations which are given in the Indian seismic code for the calculation of the fundamental period of a framed structure, primarily as a function of height, and do not consider the effect of number of bays and stiffness of the structure. Building periods predicted by these expressions are widely used in practice, although it has been observed that there is scope for further improvement in these equations since the height alone is inadequate to explain the period variability. The aim of this study is to find the effects of a number of bays in both the directions, the stiffness of the structure and propose a new period equation which incorporates a number of bays, plan area, stiffness along with the height of the structure.

• Computers and Concrete
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• v.21 no.4
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• pp.419-429
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• 2018

Climate changes, such as increasing of $CO_2$ concentration and global warming, will impact on the carbonation service life of concrete structures. Moreover, slag blended concrete has a lower carbonation resistance than control concrete. This study presents a probabilistic numerical procedure for evaluating the impact of climate change on carbonation service life of slag blended concrete. This numerical procedure considers both corrosion initiation period and corrosion propagation period. First, in corrosion initiation period, by using an integrated hydration-carbonation model, the amount of carbonatable substances, porosity, and carbonation depth are calculated. The probability of corrosion initiation is determined through Monte Carlo method. Second, in corrosion propagation period, a probabilistic model is proposed to calculate the critical corrosion degree at surface cracking, the probability of surface cracking, and service life. Third, based on the service life in corrosion initiation period and corrosion propagation period, the whole service life is calculated. The analysis shows that for concrete structures with 50 years service life, after considering climate changes, the service life reduces about 7%.

• Journal of the Korea Furniture Society
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• v.12 no.1
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• pp.91-101
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• 2001

This study explored the trend of postwar period American furniture design and analyzes the contexts of the trend. To be more specific, this study categorized the types of the styles or "looks" of furniture which were dominant in postwar period America: the machine look ; the handicraft look ; the biomorphic look. The background and the context for each look were traced back and analyzed both diachronically and synchronically. Based on the analysis, this study provided two conclusions. First, postwar period American furniture design is in many ways indebted to the World War II, because the war itself and postwar economic revival produced high demands for furniture, which consequently produced a variety of looks of furniture. Second, the furniture design in this period is attributed to commercialism and consumer-oriented design policy formulated in the mid 1920′s when American design established its own identity separating from European avant-gardism.