• Computers and Concrete
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• v.15 no.5
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• pp.771-794
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• 2015

This paper proposes an innovative method for selection of measurement sets in static parameter identification of concrete or steel bridges. This method is proved as a systematic tool to address the first steps of Structural System Identification procedures by observability techniques: the selection of adequate measurement sets. The observability trees show graphically how the unknown estimates are successively calculated throughout the recursive process of the observability analysis. The observability trees can be proved as an intuitive and powerful tool for measurement selection in beam bridges that can also be applied in complex structures, such as cable-stayed bridges. Nevertheless, in these structures, the strong link among structural parameters advises to assume a set of simplifications to increase the tree intuitiveness. In addition, a set of guidelines are provided to facilitate the representation of the observability trees in this kind of structures. These guidelines are applied in bridges of growing complexity to explain how the characteristics of the geometry of the structure (e.g. deck inclination, type of pylon-deck connection, or the existence of stay cables) affect the observability trees. The importance of the observability trees is justified by a statistical analysis of measurement sets randomly selected. This study shows that, in the analyzed structure, the probability of selecting an adequate measurement set with a minimum number of measurements at random is practically negligible. Furthermore, even bigger measurement sets might not provide adequate SSI of the unknown parameters. Finally, to show the potential of the observability trees, a large-scale concrete cable-stayed bridge is also analyzed. The comparison with the number of measurements required in the literature shows again the advantages of using the proposed method.

• The Journal of the Korea Contents Association
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• v.18 no.9
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• pp.433-440
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• 2018

I investigated whether network structure of legislators affects legislative performance in a cosponsorship network. I presented the theoretical basis with network closure and structural holes, and analyzed the network in the 19th National Assembly of Republic of Korea. In the directed and weighted network, each tie means that cosponsors support the bill sponsors proposed. The performance was measured by the number of initiatives and the ratio of reflected legislation, and the network structure was measured by size, density, hierarchy, and constraint. I found that the legislators with brokerage structure have a lot of initiatives in making connection with many legislators in various groups and the legislators with hierarchical structure have the higher ratio of reflected legislation with the continuous and strong support from the members of their group. I also found that the network of ruling party lawmaker is more hierarchical than the network of opposition lawmaker.

• The Journal of the Korea Contents Association
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• v.18 no.9
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• pp.424-432
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• 2018

Job-wage is "a compensation system in which the basic pay is determined by the value of the task regardless of the nature of the person performing the task." The retirement age of workers in 2016 is trying to improve the wage system due to the enactment of the 60-year-old law. The performance salary system introduced in the previous administration try to switch the government of Moon Jae-in. In other words, the introduction of performance salary from the Seniority based Wage and the shift to the job payment system are taking place. This study analyzed case agencies in connection with the transition of job wage to public agencies. In other words, based on the awareness of the employees involved to the contents of the transition of the performance annual salary system to the job wage system analyze empirically. This study finds that there was strong negative perception of the performance-based pay system as a whole and the shift to a job wage system was also highly opposing. It was revealed that efforts to improve the problem are needed to improve performance annual salary system, to reverse the negative perception of job wage, to prepare fair evaluation criteria for performance and job duty and to persuade employees who oppose job change.

• Structural Monitoring and Maintenance
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• v.5 no.2
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• pp.231-242
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• 2018

Subway tunnel structure has been rapidly developed in many cities for its strong transport capacity. The model-based damage detection of subway tunnel structure is usually difficult due to the complex modeling of soil-structure interaction, the indetermination of boundary and so on. This paper proposes a new data-based method for the damage detection of subway tunnel structure. The root mean square acceleration and cross correlation function are used to derive a statistical pattern recognition algorithm for damage detection. A damage sensitive feature is proposed based on the root mean square deviations of the cross correlation functions. X-bar control charts are utilized to monitor the variation of the damage sensitive features before and after damage. The proposed algorithm is validated by the experiment of a full-scale two-rings subway tunnel lining, and damages are simulated by loosening the connection bolts of the rings. The results verify that root mean square deviation is sensitive to bolt loosening in the tunnel lining and X-bar control charts are feasible to be used in damage detection. The proposed data-based damage detection method is applicable to the online structural health monitoring system of subway tunnel lining.

• Journal of Korean Society of Steel Construction
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• v.12 no.6
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• pp.769-777
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• 2000

This paper presents the results of cyclic seismic performance in relation to beam-panel zone strength ratio of CFT Column to H-beam steel moment connections. Each test specimen consisted of $H-350{\times}175{\times}7{\times}11$ beam(SS400) and ${\boxe}-250{\times}250{\times}9$, ${\boxe}-250{\times}250{\times}12$ column(SPSR400). Main parameter is a column panel zone strength relative to beam strength. Energy absorption capacity available in the specimens ranged from 5.2 to 12.7(tm). If panel zone strength relative to beam strength is too strong or weak, the energy absorption capacity tended to be inferior. About steel moment-resisting frame, the test results of this experiment seem to support the investigation that permitting panel zone yielding shall be more advantageous to enhancing total seismic performance.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.5
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• pp.657-663
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• 2016

In this work, a novel silicon (Si) based floating body synaptic transistor (SFST) is studied to mimic the transition from short-term memory to long-term one in the biological system. The structure of the proposed SFST is based on an n-type metal-oxide-semiconductor field-effect transistor (MOSFET) with floating body and charge storage layer which provide the functions of short- and long-term memories, respectively. It has very similar characteristics with those of the biological memory system in the sense that the transition between short- and long-term memories is performed by the repetitive learning. Spike timing-dependent plasticity (STDP) characteristics are closely investigated for the SFST device. It has been found from the simulation results that the connectivity between pre- and post-synaptic neurons has strong dependence on the relative spike timing among electrical signals. In addition, the neuromorphic system having direct connection between the SFST devices and neuron circuits are designed.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.21-27
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• 2017

Internet of Things(IoT), which is developing for the hyper connection society, is based on OSHW (Open Source Hardware) such as Arduino and various small products are emerging. Because of the limitation of low performance and low memory, the IoT is causing serious information security problem that it is difficult to apply strong security technology. In this paper, we analyze the vulnerability that can occur as a result of compiling and loading the application program of Arduino on the host computer. And we propose a new attack method that allows an attacker to arbitrarily change the value input from the sensor of the arduino board. Such as a proposed attack method may cause the arduino board to misinterpret environmental information and render it inoperable. By understanding these attack techniques, it is possible to consider how to build a secure development environment and cope with these attacks.

• Architectural research
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• v.14 no.4
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• pp.125-132
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• 2012

In contemporary Korean society, urban community environment is often associated with high-density and high-rise residences that make people's relationships superficial, instrumental and impersonal. Furthermore, urban community consistently interplays with neighboring residents and childhood emotional experience are influential on their unconscious images and attitude about their current neighborhood environment, while affecting the environmental attitude and the formation of community sense. Previous research found evidences that increased level of community sense is fostering more feeling of living in so-called "real neighborhood environment." This study aimed to cross-culturally examine what the respondents' emotional perception and their attitude were about the community environment in their childhood through environmental autobiography method and to examine the effects of the results on adults' formation of sense of community for their current community environment. Extensive literature review explored a few important theoretical framework which are closely related to sense of community (SOC) as a result of emotional experience: membership, influence, integration and fulfillment of needs, shared emotional connection and community satisfaction. Chi-square and GLM analysis revealed that there were no demographic, and socio-economic differences between two groups of Korean and US residents. Correlation analysis indicated that childhood emotional experience of Koreans and US citizens was statistically significant on sense of community for their current living community. Multi-regression analysis also found that the degree of influence were the main predictors for building strong sense of current community throughout a cross-cultural group. Furthermore, the relationship between various emotional experience of each factor in previous and current community environment were statistically significantly related. It is concluded that as the positive childhood experience of influence in their past community was going up, the level of sense of community for their current community was strengthened across their cross-cultural background.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.168-168
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• 1999

Recently, Fe/Si multilayered films (MLF) have been a focus of interest due to the strong antiferromagnetic (AF) coupling observed in such kind of MLF originates from the same nature as in the metal/metal MLF. In particular, a question of whether the spacer layer in the Fe/Si MLF is metallic or semiconducting is of interest. In spite of various experimental techniques envolved in the study, the chemical composition and the properties of the interfacial regions in the MLF exhibiting the AF coupling is still questionable. The nature of the AF coupling and the interfacial properties of Fe/Si MLF are investigated in this study. A series of Fe/Si MLF with a fixed nominal thickness of Fe(3nm) and a variable thickness of Sk(1.0-2.2nm) were deposited by RF-sputtering onto glass substrates at room temperature. The atomic structures and the actual sublayer thicknesses of the Fe/Si MLF are investigated by using x-ray diffraction. The magnetic-field dependence of the equatorial Kerr effect clearly shows an appearance of the AF coupling between Fe sublayers at tsi = 1.5 - 1.8 nm. the drastic discrepancies between the experimental magnetooptical (MO) and optical properties, and based on the assumption of sharp interfaces between Fe and Si sublayers leads to a conclusion that pure si is absent in the AF-coupled Fe/Si MLF. Introducing in the model nonmagnetic semiconducting FeSi alloy layers between Fe and Si sublayers or as spacer between pure Fe sublayers only slightly improves the agreement between model and experiment. A reasonable agreement between experimental and simulated MO spectra was reached with using the fitted optical properties for the spacer with a typical metallic type of behavior. The results of the magnetic properties measured by vibrating sample magnetometer and magnetic circular dichroism are also analyzed in connection with the MO and optical properties.

• Journal of architectural history
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• v.14 no.1 s.41
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• pp.135-150
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• 2005

Historical study of Korean traditional houses have been carried, mainly, based on the geographical region of Korean peninsula. However, the case of primitive houses can not be researched according to the geographical and racial concept of modern nations. This study aims to examine the primitive houses of ethnic minorities of northeastern China, where the cultural and racial background have been deeply rooted in the history of Korea as well as Korean traditional houses. Through the field research and literary materials, the basic types of primitive houses of the five ethnic minorities could be identified. Among these types, those that have possible relationship with Korean houses, are cone shaped house, underground house, and elevated wooden house. Archeological evidences of underground houses were amply found in Korea already, but above ground evidences could not be found. However, It seems quite certain that the cone shaped houses and elevated wooden houses, too, existed in Korea as one of the earliest housing types, as can be examined in remaining examples in Korean peninsula. With no doubt, the primitive houses of Korea have strong connection with that of the ethnic minorities of northeastern China. This can be verified through the facts that the evidences of cone shaped houses, the similarities of the use of Inner space, the evidences of elevated wooden houses. Also, the combination of wooden floor and ondol, which is known to be one of the strongest characteristic of Korean traditional houses, could be originated from the combination of primitive summer house, the elevated wooden house, and the winter house, the underground house with ondol.