• The Journal of Asian Finance, Economics and Business
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• v.8 no.4
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• pp.263-276
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• 2021

This study examines the effect of international capital flows on corporate capital structures in Vietnam by analyzing panel data from all non-financial listed firms from 2005 to 2014 using pooled ordinary least square (OLS) with a variance estimator. The analysis includes a comparison of the signs and significance of the variable coefficients from the perking order and static trade-off theories to the empirical results to determine the optimum approach to the corporate capital structure given Vietnam's high-inflation environment. The results indicate that international capital flows have a positive relation to the debt ratio in the long term, and the relationship is more robust for 2005-2009 than for 2010-2014. Corporate capital structures adjusted to changes in the business environment in different sub-periods (2005-2009 and 2010-2014). When the economic environment became more favorable, the pecking order theory's predictive power increased, and that of trade-off theory lessened. Manufacturing and non-manufacturing firms required different capital structure decisions to fuel their operations and grow under foreign competition. The analysis demonstrates that firms should intensify their use of long-term debt relative to the availability of capital, which is an implication not only for firms in particular but also for industrial innovation overall.

• Steel and Composite Structures
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• v.51 no.2
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• pp.173-183
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• 2024

This study investigates a new seismic retrofit system that utilizes rotational friction dampers and axial springs. The retrofit system involves a steel frame with rotational friction dampers (RFD) at beam-column joints and linear springs at the corners, providing energy dissipation and self-centering capabilities to existing structures. The axial spring acts as a self-centering mechanism that eliminates residual deformations, while the friction damper mitigates seismic damage. To evaluate the seismic performance of the proposed retrofit system, a series of cyclic loading tests were carried out on a steel beam-column subassembly equipped with the proposed devices. An analytical model was then developed to validate the experimental results. A performance point ratio (PPR) was presented to optimize the design parameters of the retrofit system, and a performance-based seismic design strategy was developed based on the PPR. The retrofit system's effectiveness and the presented performance-based design approach were evaluated through case study models, and the analysis results demonstrated that the developed retrofit system and the performance-based design procedure were effective in retrofitting structures for multi-level design objectives.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.5
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• pp.20-28
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• 2016

A Ubiquitous City (U-city, Smart City) is one that ties information communications technologies (ICT) into many facets of city construction, thereby implicitly intending to function as a smart city that aims to be efficiently managed as well as provide an enhanced standard of living for its residents. Laws related to the construction of such ubiquitous cities point to integrated city management centers, intelligent facilities, and U-City infrastructure, among others, as central components of U-Cities, but do not provide a standard for these structures. Consequently, building of U-Cities by local governments are based on arbitrary judgments constrained the myriad of practical limitations that they face. Such ambiguity brings to light the need to find ways to improve the quality of these efforts. The first and second stages of this research examine the status of the components of a U-City -ubiquitous planning, technology, infrastructure, and services - and undertakes a comprehensive review thereof, with evaluation criteria formulated on the characteristics of stability, connectivity, goal-orientation, and development potential. In the research's third stage, a realistic and detailed evaluation index by which U-Cities can be renewed, demonstrated, and applied (???) is introduced in a step-by-step fashion, which will allow for local governments to properly assess the standard of their U-City in relation to the realities of the locality. Through the research result, it is expected that the index will become a part of the continued development and advancement of the "smart" character of an autonomous U-City at the local scale, and contribute to the overall revitalization of the U-City.

• Steel and Composite Structures
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• v.47 no.2
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• pp.167-184
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• 2023

In this study, a new recentering friction device (RFD) to retrofit steel moment frame structures is introduced. The device provides both self-centering and energy dissipation capabilities for the retrofitted structure. A hybrid performance-based seismic design procedure considering multiple limit states is proposed for designing the device and the retrofitted structure. The design of the RFD is achieved by modifying the conventional performance-based seismic design (PBSD) procedure using computational intelligence techniques, namely, genetic algorithm (GA) and artificial neural network (ANN). Numerous nonlinear time-history response analyses (NLTHAs) are conducted on multi-degree of freedom (MDOF) and single-degree of freedom (SDOF) systems to train and validate the ANN to achieve high prediction accuracy. The proposed procedure and the new RFD are assessed using 2D and 3D models globally and locally. Globally, the effectiveness of the proposed device is assessed by conducting NLTHAs to check the maximum inter-story drift ratio (MIDR). Seismic fragilities of the retrofitted models are investigated by constructing fragility curves of the models for different limit states. After that, seismic life cycle cost (LCC) is estimated for the models with and without the retrofit. Locally, the stress concentration at the contact point of the RFD and the existing steel frame is checked being within acceptable limits using finite element modeling (FEM). The RFD showed its effectiveness in minimizing MIDR and eliminating residual drift for low to mid-rise steel frames models tested. GA and ANN proved to be crucial integrated parts in the modified PBSD to achieve the required seismic performance at different limit states with reasonable computational cost. ANN showed a very high prediction accuracy for transformation between MDOF and SDOF systems. Also, the proposed retrofit showed its efficiency in enhancing the seismic fragility and reducing the LCC significantly compared to the un-retrofitted models.

• Journal of the Korean Society of Safety
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• v.25 no.6
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• pp.123-127
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• 2010

A fire disaster is very serious in the closing space like subway station. In this study, the simulation on fire diffusion is performed to get the temperature history curve, which is used for the fire resisting structural analysis. Most of subway stations are built by the reinforced concrete structure, but recently steel structures are selected for the larger space or beauty. Steel structures relatively have more weaknesses against fire, so it is necessary to develop the method for evaluating fire-resisting capacity in this kind of structures. The developed method is applied to the subway station in Daegu city. It shows that the developed method can be used to simulate the fire disaster and to get the temperature history curve and evaluate the safety of steel structures against the fire.

• Structural Engineering and Mechanics
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• v.16 no.5
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• pp.581-595
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• 2003

Since the conventional direct approaches are hard to be applied for damage diagnosis of complex large-scale structures, a two-step approach for diagnosing the joint damage of framed structures is presented in this paper by using artificial neural networks. The first step is to judge the damaged areas of a structure, which is divided into several sub-areas, using probabilistic neural networks with natural Frequencies Shift Ratio inputs. The next step is to diagnose the exact damage locations and extents by using the Radial Basis Function (RBF) neural network with the second Element End Strain Mode of the damaged sub-area input. The results of numerical simulation show that the proposed approach could diagnose the joint damage of framed structures induced by earthquake action effectively and has reliable anti-jamming abilities.

• Journal of Environmental Science International
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• v.24 no.3
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• pp.303-316
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• 2015

The relationship between urban spatial structures and GHG-AP integrated emissions was investigated by statistically analyzing those from 25 administrative districts of Seoul. Urban spatial structures, of which data were obtained from Seoul statistics yearbook, were classified into five categories of city development, residence, environment, traffic and economy. They were further classified into 10 components of local area, population, number of households, residential area, forest area, park area, registered vehicles, road area, number of businesses and total local taxes. GHG-AP integrated emissions were estimated based on IPCC(intergovernmental panel on climate change) 2006 guidelines, guideline for government greenhouse inventories, EPA AP-42(compilation of air pollutant emission factors) and preliminary studies. The result of statistical analysis indicated that GHG-AP integrated emissions were significantly correlated with urban spatial structures. The correlation analysis results showed that registered vehicles for GHG (r=0.803, p<0.01), forest area for AP (r=0.996, p<0.01), and park area for AP (r=0.889, p<0.01) were highly significant. From the factor analysis, three groups such as city and traffic categories, economy category and environment category were identified to be the governing factors controlling GHG-AP emissions. The multiple regression analysis also represented that the most influencing factors on GHG-AP emissions were categories of traffic and environment. 25 administrative districts of Seoul were clustered into six groups, of which each has similar characteristics of urban spatial structures and GHG-AP integrated emissions.

• Journal of Korea Entertainment Industry Association
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• v.14 no.3
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• pp.181-190
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• 2020

Asura: The City of Madness, which was released in 2017, attracted great attention even prior to its release with the combination of Director Kim Sung-su, and actors, Jung Woo-sung, Hwang Jung-min, Ju Ji-hoon and Kwak Do-won. Faithful to its genre as a crime film of film noir, Asura: The City of Madness created multi-layered issues by the overthrow of the archetypal hero character and variation of the heroic narrative structure drew diverse interpretations among both critics and viewers alike. This study aims at analyzing the heroic narrative structure of Asura: The City of Madness based on Christopher Vogler's "The Hero's Journey" and examining how the universality and typicality of narrative structures as mentioned by Vogler are applied to this film. Although the universal and typical characteristics of all narrative structures cannot be analyzed through Christopher Vogler's The Hero's Journey, five atypical characteristics could be derived from this film that deviate from the universality mentioned by Christopher Vogler by looking at the characteristics of the heroic narrative structure implemented as Han Do-kyung, the leading character and a "hero," proceeds through the 12 stages. This study examines which variations such atypical characteristics brought to the heroic narrative structures in crime films what has changed in audiences' expectations, and how it could work as an alternate narrative.

• Korean Journal of Heritage: History & Science
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• v.45 no.3
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• pp.28-59
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• 2012

The $Sh{\grave{a}}ngdu$ site in the Yuan Dynasty of China, a capital city located in the northern steppe area characterised by the nomadic life, has received great attentions from a number of travellers, historians and archaeologists. Several famous European travellers described vividly the city structure and civil life of $Sh{\grave{a}}ngdu$ from the Yuan Dynasty onwards. Since the begging of the modern era, a number of foreign expeditionists and historians explored $Sh{\grave{a}}ngdu$ and published research reports. From the 20th century, mainly Chinese and Japanese historians and archaeologists carried out the relatively detailed historical researches and archaeological surveys to the $Sh{\grave{a}}ngdu$ site; and published books, articles and excavation reports. More detailed and scientific archaeological investigations, mappings and excavations have been conducted since 1990s. This paper aims to progress basic discussion to the city structures of the $Sh{\grave{a}}ngdu$ site based on the previously conducted researches by expeditionists, geographers and archaeologists and the full scale investigations, which have been carried out since the late 20th century.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.4 s.19
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• pp.71-78
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• 2005

The principal basic concepts of aseismic design minimize damage of human-life and have little probability during life of structures. For detailed understanding of the design, the best reasonable countermeasure can be possible equally the smallest damage of human-life and economic loss. As a result, it can be achieved by notion of not structure-centered but city-centered, the notion is actualized by development of a macro-level evaluation. A seismic damage between city and country is different. And the larger the city then, the greater the loss by rather collateral hazards than collapse of structures. Hence, the macro-evaluation of an earthquake disaster is suitable for an old city where is center of political and economic activity, and is concentration of population and infrastructure. This study aims to develop comprehensive earthquake desaster risk index, and assesses relative earthquake risk of six zones in Seoul metropolitan area.