• International journal of steel structures
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• v.18 no.5
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• pp.1483-1496
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• 2018

Negligible research has been conducted to date on how to analyse weakened columns, thus safety risks are still involved when structures are weakened prior to demolition. There are various methods available for demolishing steel structures. One of the most effective methods that has been developed involves pre-cutting steel columns at a certain height, so that the least effort can be used to collapse the structure by means of pulling out some of the columns. This paper presents (a) an experimental setup developed to test the capacity of axially loaded weakened columns, which is used to (b) validate a finite element (FE) model. The two pre-cuts that are presented in this paper are (1) the double window cut and (2) the triangular window cut, which are both commonly used in industry. A column weakened with a double window cut or triangular window cut reduces the axial load capacity by up to 50 and 40%, respectively. The FE models developed predict the axial failure load of weakened columns for a double window cut and triangular window cut are generally within an accuracy of less than 8 and 10%, respectively. It is shown at higher slendernesses the influence of column cuts is less than would be intuitively expected because global buckling becomes dominant.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2019.05a
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• pp.242-243
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• 2019

In recent years, road cutting work has been frequently performed for the repair of old road pavement and the development of underground space. However, the existing pavement cutting machine in Korea generates a lot of noise and dust. In this study, it was found out that the pavement cutting machine that cuts off noise and sucks cutting dust is used in overseas. Therefore, in this study, the concept of eco - friendly pavement cutter suitable for domestic situation is derived. The results will be used in prototype modeling and experimentation.

• Smart Structures and Systems
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• v.33 no.3
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• pp.227-241
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• 2024

Safety and structural integrity of civil structures, like bridges and buildings, can be substantially enhanced by employing appropriate structural health monitoring (SHM) techniques for timely diagnosis of incipient damages. The information gathered from health monitoring of important infrastructure helps in making informed decisions on their maintenance. This ensures smooth, uninterrupted operation of the civil infrastructure and also cuts down the overall maintenance cost. With an early warning system, SHM can protect human life during major structural failures. A real-time online damage localization technique is proposed using only the vibration measurements in this paper. The concept of the 'Degree of Scatter' (DoS) of the vibration measurements is used to generate a spatial profile, and fractal dimension theory is used for damage detection and localization in the proposed two-phase algorithm. Further, it ensures robustness against environmental and operational variability (EoV). The proposed method works only with output-only responses and does not require correlated finite element models. Investigations are carried out to test the presented algorithm, using the synthetic data generated from a simply supported beam, a 25-storey shear building model, and also experimental data obtained from the lab-level experiments on a steel I-beam and a ten-storey framed structure. The investigations suggest that the proposed damage localization algorithm is capable of isolating the influence of the confounding factors associated with EoV while detecting and localizing damage even with noisy measurements.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.53 no.4
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• pp.226-234
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• 2004

A rapid Prototyping system that laser-cuts and laminates thick layers can fabricate 3D objects promptly with a variety of materials. Building such a system must consider the surface distortions due to both vertical-cut layers and triangular surfaces. We developed a tangential layer-cutting algorithm by rearranging tangential lines such that they reconstruct 3D surfaces more closely and also constitute smoother laser trajectories. An energy function that reflects the surface-closeness with the tangential lines was formulated and then the energy was minimized by a gradient descent method. Since this simple method tends to cause many local minima for complex 3D objects, we tried to solve this problem by adding a simulated annealing process to the proposed method. To view and manipulate 3D objects, we also implemented a 3D visual environment. Under this environment, experiments on various 3D objects showed that our algorithm effectively approximates 3D surfaces and makes laser-trajectory feasibly smooth.

• Journal of Advanced Information Technology and Convergence
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• v.9 no.1
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• pp.89-102
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• 2019

Collagen can be used in building artificial skin replacements for treatment of burns and towards the reconstruction of bone as well as researching cell behavior and cellular interaction. The strength of collagen in connective tissue rests on the characteristics of collagen fibers. 3D confocal imaging of collagen fibers enables the characterization of their spatial distribution as related to their function. However, the image stacks acquired with confocal laser-scanning microscope does not clearly show the collagen architecture in 3D. Therefore, we developed a new method to reconstruct, visualize and characterize collagen fibers from fluorescence confocal images. First, we exploit the tensor voting framework to extract sparse reliable information about collagen structure in a 3D image and therefore denoise and filter the acquired image stack. We then propose to segment the collagen fibers by defining an energy term based on the Hessian matrix. This energy term is minimized by a min cut-max flow algorithm that allows adaptive regularization. We demonstrate the efficacy of our methods by visualizing reconstructed collagen from specific 3D image stack.

• KIEAE Journal
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• v.17 no.1
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• pp.69-75
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• 2017

Purpose: Heat transfer analysis of recently developed 'slim type double-skin system window' were presented. This window system is designed for curtain wall type façade that main energy loss factor of recent elegant buildings. And the double skin system is the dual window system integrated with inner shading component, enclosed gap space made by two windows when both windows were closed and shading component effectively reflect and terminate solar radiation from outdoor. Usually double-skin system requires much more space than normal window systems but this development has limited by 270mm, facilitated for curtain wall façade buildings. In this study, we estimated thermophysical phenomena of our double-skin curtain wall system window with solar load conditions at the summer season. Method: A fully 3-Dimentional analysis adopted for flow and convective and radiative heat transfer. The commercial CFD package were used to model the surface to surface radiation for opaque solid region of windows' frame, transparent glass, fluid region at inside of double-skin and indoor/outdoor environments. Result: Steep angle of solar incident occur at solar summer conditions. And this steep solar ray cause direct heat absorption from outside of frame surface rather than transmitted through the glass. Moreover, reflection effect of shading unit inside at the double-skin window system was nearly disappeared because of solar incident angle. With this circumstances, double-skin window system effectively cuts the heat transfer from outdoor to indoor due to separation of air space between outdoor and indoor with inner space of double-skin window system.

• Architectural research
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• v.20 no.2
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• pp.35-43
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• 2018

This article explores the complex modes of experiencing the modern city that are engaging and disengaging by nature, which thus negates any simple ways of understanding what it means by 'the urban' in a Manichean comparison. What follows is an in-depth case study of Gordon Matta-Clark's 1976 film titled City Slivers. Influenced by the countercultural practices prevalent in the 1960s and 1970s, Matta-Clark produced a number of works roughly grouped together under the rubric of "building cuts." Among many others, City Slivers is distinctive among Matta-Clark's extensive cutting projects, in the sense that he actively utilizes film as a primary expressive medium and poetically reassembles fragmentary images of cityscape in order to bring forth an alternative urban scenario where the tension between institution-bound urbanization and dispersed daily urban practices is highlighted. Instead of simply being critical against the changing urban conditions of Manhattan in the 1970s, Matta-Clark aims to actively grasp ambivalent instances of urban life that are at once attractive and alienating, thereby excavating the subconscious terrain of contemporary urbanism that is prevalent but often dismissed over glamorous urban projects.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.910-913
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• 2001

Rapid Prototyping(RP) techniques have unique characteristics according to their working principle: the stair-stepped surface of a part due to layer-by-layer stacking, low building speed, and additional post-processing to improve surface roughness. A new RP process, Variable Lamination Manufacturing by using expandable polystyrene foam(VLM-S), has been developed to overcome the unfavorable characteristics. The objective of this study is to investigate the thermal characteristics and skeleton size effects as the hotwire cuts EPS foam sheet in order to improve dimensional accuracy of the parts, which is produced by VLM-S. Empirical and analytical approaches are performed to find the relationship between cutting speed and heat input, and the relationship between maximum available cutting speed and heat input. In addition, empirical approaches are carried out to find the relationship between cutting error and skeleton size, and cutting deviation and skeleton size. Based on these results, the optimal hotwire cutting condition and available minimum skeleton size are derived. The outcomes of this study are reflecting in the enhancement of VLM-S input data generation S/W.

• Journal of the Korean Society for Precision Engineering
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• v.34 no.1
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• pp.35-39
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• 2017

We used a construction method using a CNC milling machine, where free-formed molds were made by cutting EPS (Expanded PolyStyrene) foam with the CNC machine, to build free-formed buildings. CNC milling is off-the-shelf technology that can easily cut EPS foam; however its production cost is too high and the time to manufacture an EPS mold is too long. This paper proposes a novel cutting machine with a fast and cost effective mechanism to manufacture EPS concrete molds. Our machine comprises a cutter and Cartesian coordinate type moving mechanism, where the cutter cuts EPS foam using a hotwire in the shape of '$\sqcap$' and is capable of adjusting its cutting angle in real-time while keeping its cutting width. We proved through cutting experiments on the CNC machine that cutting time was greatly shortened compared to the conventional method and that the resulting concrete mold satisfied manufacturing precision.

• Asian-Australasian Journal of Animal Sciences
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• v.18 no.4
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• pp.590-600
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• 2005

The present report has been aimed at reviewing important factors which need to be closely analyzed or considered when increasing the market weight of finishing pigs. The pig market weight has increased worldwide during the past few decades, which is attributable primarily to an increased lean gain potential of finishing pigs. To increase the market weight, however, the acceptability of larger pigs by the packer as well as pork consumers should be met first. By increasing the market weight, total number of breeding stock, as well as the facility for them, necessary for producing a given weight of pork can be reduced, whereas more building space for finishing pigs and an additional nutrition program for the later finishing period are needed. Additionally, a more thorough disease prevention program especially against ileitis and mycoplasma pneumonia may also be needed, because outbreaks of these are known to increase with increasing body weight over 110 kg. Some larger finishing pigs may deposit excessive fat that may be reduced or prevented by using hormonal and/or nutritional agents. Backfat thickness increases linearly with increasing body weight between 110 and 130 kg, whereas intramuscular fat content does not change significantly. With increasing live weight within this range, the ratios of belly and loin to carcass weight also are known to increase. Some physicochemical characteristics related to fresh and cooked meat quality including color, firmness, juiciness, etc. are known to be unaffected or slightly changed following an increase of slaughter weight. In conclusion, ratios of primal cuts and pork quality characteristics are not significantly affected by increasing the market weight. Moreover, increasing the market weight of lean-type pigs approximately up to 130 kg is normally profitable to producers, as long as packers and consumers accept larger pigs.