• Journal of the Korean Regional Science Association
• /
• v.11 no.1
• /
• pp.93-111
• /
• 1995

This study investigated the nature of spatial concentration and dispersion of corporate control within an international system of decision-making centers. It introduces a simplified model of the global evolution of quaternary places. Linked to the national quaternary place model, the proposed model is useful for examinations involving real world situations associated with international corporations. This five stage model emphasizes the importance of the organizational structure of large corporations, industrial networks and the development of information technology. It suggests the dispersion of international quaternary places along with the diversification of corporate control linkages among quaternary centers. A case study for 1974-1991 uses information statistics to identify the current stage of the international quaternary system. The result is in general agreement with major elements of the stage model. This theoretical concept and empirical research contribute to the expansion of quaternary place theory to the global scale in particular, and to the development of location analysis in general.

• Proceedings of the Computational Structural Engineering Institute Conference
• /
• 2003.10a
• /
• pp.527-534
• /
• 2003

This paper presents the LRB-based hybrid base isolation systems employing additional active/semiactive control devices for seismic protection of cable-stayed bridges by examining the ASCE first generation benchmark problem for a cable-stayed bridge. In this study, ideal hydraulic actuators (HAs) and ideal magnetorheological dampers (MRDs) are considered as additional active and semiactive control devices, respectively. Numerical simulation results show that all the hybrid base isolation systems are effective in reducing the structural responses of the benchmark cable-stayed bridge under the historical earthquakes considered. The simulation results also demonstrate that the hybrid base isolation system employing semiactive MRBs is robust to the stiffness uncertainty of the structure, while the hybrid system with active HAs is not. Therefore, the LRB-based hybrid base isolation system employing MRDs could be more appropriate in real applications for full-scale civil infrastructures.

• Structural Engineering and Mechanics
• /
• v.52 no.3
• /
• pp.541-558
• /
• 2014

A 1/4-scale two-bay eight-storey reinforced concrete frame was tested on shaking table. Initial shaking table tests were carried out through a set of real seismic excitations to investigate the seismic behavior of the RC frame. Subsequently, the damaged frame was repaired using epoxy injection technique, and then subjected to the tests with the same records. The purpose of this study was to investigate experimentally the dynamic characteristics, cracking pattern and lateral inter-story stiffness of RC frames using epoxy injection technique. The test results indicate that epoxy-injection technique appears to be a satisfactory method for repairing earthquake-damaged structure.

• Journal of Korean Society of Industrial and Systems Engineering
• /
• v.34 no.4
• /
• pp.138-144
• /
• 2011

The design flexibility and robustness have become key factors to handle various sources of uncertainties at the early phase of design. Even though designers are uncertain about which single values to specify, they usually have a preference for certain values over others. In the first and second reports of a four-part paper, a set-based design approach has been proposed for achieving design flexibility and robustness while capturing designer's preference, and its effectiveness has been illustrated with a simple vehicle side-door impact beam design problem. This report presents the applicability of the proposed design approach to the large-scale multi-objective design optimization with a successful implementation of real vehicle side-door structure design.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2004.11a
• /
• pp.421-424
• /
• 2004

Model updating is a very active research field, in which significant efforts has been invested in recent years. Model updating methodologies are invariably successful when used on noise-free simulated data, but tend to be unpredictable when presented with real experimental data that are-unavoidably-corrupted with uncorrelated noise content. In this paper, Reanalysis using frequency response functions for correlating and updating dynamic systems is presented. A transformation matrix is obtained from the relationship between the complex and the normal frequency response functions of a structure. The transformation matrix is employed to calculate the modified damping matrix of the system. The modified mass and stiffness matrices are identified from the normal frequency response functions by using the least squares method. Full scale pseudo dynamic pier test is employed to illustrate the applicability of the proposed method. The result indicate that the damping matrix of correlated finite element model can be identified accurately by the proposed method. In addition, the robustness of the new approach uniformly distributed measurement noise is also addressed.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.48 no.1
• /
• pp.76-81
• /
• 1999

The degree of relative similarity between 2D patterns is obtained using Open-Ball Scheme. Open-Ball Scheme employs a method of transforming the geometrical information on 3D objects or 2D patterns into the features to measure the relative similarity for object(patten) recognition, with invariance on scale, rotation, and translation. The feature of an object is used to obtain the relative similarity and mapped into [0, 1] the interval of real line. For decades, Moment-Invariant Method has been used as one of the excellent methods for pattern classification and object recognition. Open-Ball Scheme uses the geometrical structure of patterns while Moment Invariant Method uses the statistical characteristics. Open-Ball Scheme is compared to Moment Invariant Method with respect to the way that it interprets two-dimensional patten classification, especially the paradigms are compared by the degree of closeness to human's intuitive understanding. Finally the effectiveness of the proposed Open-Ball Scheme is illustrated through simulations.

• International Journal of High-Rise Buildings
• /
• v.1 no.1
• /
• pp.37-51
• /
• 2012

New generation of tall and complex buildings systems are now introduced that are reflective of the latest development in materials, design, sustainability, construction, and IT technologies. While the complexity in design is being overcome by the availability and advances in structural analysis tools and readily advanced software, the design of these buildings are still reliant on minimum code requirements that yet to be validated in full scale. The involvement of the author in the design and construction planning of Burj Khalifa since its inception until its completion prompted the author to conceptually develop an extensive survey and real-time structural health monitoring program to validate all the fundamental assumptions mad for the design and construction planning of the tower. The Burj Khalifa Project is the tallest structure ever built by man; the tower is 828 meters tall and comprises of 162 floors above grade and 3 basement levels. Early integration of aerodynamic shaping and wind engineering played a major role in the architectural massing and design of this multi-use tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria established at the onset of the project design. Understanding the structural and foundation system behaviors of the tower are the key fundamental drivers for the development and execution of a state-of-the-art survey and structural health monitoring (SHM) programs. Therefore, the focus of this paper is to discuss the execution of the survey and real-time structural health monitoring programs to confirm the structural behavioral response of the tower during construction stage and during its service life; the monitoring programs included 1) monitoring the tower's foundation system, 2) monitoring the foundation settlement, 3) measuring the strains of the tower vertical elements, 4) measuring the wall and column vertical shortening due to elastic, shrinkage and creep effects, 5) measuring the lateral displacement of the tower under its own gravity loads (including asymmetrical effects) resulting from immediate elastic and long term creep effects, 6) measuring the building lateral movements and dynamic characteristic in real time during construction, 7) measuring the building displacements, accelerations, dynamic characteristics, and structural behavior in real time under building permanent conditions, 8) and monitoring the Pinnacle dynamic behavior and fatigue characteristics. This extensive SHM program has resulted in extensive insight into the structural response of the tower, allowed control the construction process, allowed for the evaluation of the structural response in effective and immediate manner and it allowed for immediate correlation between the measured and the predicted behavior. The survey and SHM programs developed for Burj Khalifa will with no doubt pioneer the use of new survey techniques and the execution of new SHM program concepts as part of the fundamental design of building structures. Moreover, this survey and SHM programs will be benchmarked as a model for the development of future generation of SHM programs for all critical and essential facilities, however, but with much improved devices and technologies, which are now being considered by the author for another tall and complex building development, that is presently under construction.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.27 no.6
• /
• pp.138-143
• /
• 2023

In this study, the crack healing performance of each crack healing agent manufacturing method was analyzed by adding crack healing agents in the form of alginate gel and spore suspension inoculated with endospores of calcium carbonate-forming bacteria to mortar. In addition, by applying it to an full-scale structure in the form of a box-type culvert, we attempted to create an environment in which the developed crack healing agent can be applied not only to a laboratory environment but also to an actual field. The crack healing agent using the dry heat drying method showed crack healing performance, but in the case of the freeze drying method, many spores were killed by freeze hardening and therefore the crack healing performance was lost. As a result of SEM and XRD pattern analysis of the presumed crack healing material extracted from the crack of a full-scale structure, it was found to be calcite, one of the calcium carbonate crystals produced by microorganisms applied to the crack healing agent. In conclusion, it was found that the crack healing by microorganisms can be implemented in a real structure.

• Korean Journal of Poultry Science
• /
• v.20 no.2
• /
• pp.107-114
• /
• 1993

The structure change in the broiler industry of Korea has been taking place very rapidly toward the direction of integrated production and marketing system. During the course of the evolution into the integrated structure, however, a number of small business entities, uncountable nationally but a minimum of a dozen, that previously engaged in the supply of production factors or live bird transaction also tended to get involved in the new system as a disguised or pseudo-integrator, having brought a lot of problems not only to the farmers but also to the development of integrated structure. The pseudo-integrator is generally characterized by limited functions in such a way of supplying chicks and feeds to and collecting grown birds from farmers under the contract at a fixed farmer's payment in practically the same pattern as a partial or quasi-integration, which intends to act as if an integrator in a stratagem to simply enjoy a margin simply from selling supplies and buying products for a certain period of time. The grower making a contract with appears to be a farmer who used to be an Independent and speculating but not able to join in the normal system of evolving integration. The problems of a pseudo-integrator center on the financial loss to a contract farmer, because the falsified integrator has to become easily bankrupt and run away when the price of live broiler continually stays below the cost of production, even though he is able to make a tremendous profit otherwise which is the real purpose of the operation for. It is true that the volatile market, fluctuating the price up more than doubled in a month and down to a half in a few weeks, makes the pseudo-integrator find the room for such a fraudulence. In addition, its activity also adversely affect the evolution of the integration due to rather negative image on structure change in general. It is recommended that the farmers need to better understand the real picture of the integrated system so as not to be swindled by a disguised, small scale agribusiness agent. By the same token, it is also equally required to have the whole industry integrated completely as early as possible. The Joint effort to get rid of pseudo-integrators' problems shall be put for the industry development moving toward the integration. No doubt a pseudo-integrator must be a temporary player for chance emerging during the course of structure change into the integrated, though.

• International Journal of Naval Architecture and Ocean Engineering
• /
• v.6 no.2
• /
• pp.459-470
• /
• 2014

During ship design, welding-induced distortions are roughly estimated as a function of the size of the component as well as the welding process and residual stresses are assumed to be locally in the range of the yield stress. Existing welding simulation methods are very complex and time-consuming and therefore not applicable to large structures like ships. Simplified methods for the estimation of welding effects were and still are subject of several research projects, but mostly concerning smaller structures. The main goal of this paper is the application of a multi-layer welding simulation to the block joint of a ship structure. When welding block joints, high constraints occur due to the ship structure which are assumed to result in accordingly high residual stresses. Constraints measured during construction were realized in a test plant for small-scale welding specimens in order to investigate their and other effects on the residual stresses. Associated welding simulations were successfully performed with fine-mesh finite element models. Further analyses showed that a courser mesh was also able to reproduce the welding-induced reaction forces and hence the residual stresses after some calibration. Based on the coarse modeling it was possible to perform the welding simulation at a block joint in order to investigate the influence of the resulting residual stresses on the behavior of the real structure, showing quite interesting stress distributions. Finally it is discussed whether smaller and idealized models of definite areas of the block joint can be used to achieve the same results offering possibilities to consider residual stresses in the design process.