• Journal of Navigation and Port Research
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• v.31 no.8
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• pp.675-681
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• 2007

A numerical procedure is described for estimating the effects of the multi-directional irregular waves on the structural responses of the Tension Leg Platform (TLP). The numerical approach is based on a three dimensional source distribution method for hydrodynamic forces, a three dimensional frame analysis method for structural responses, in which the superstructure of TLP is assumed to be flexible instead of rigid. Hydrodynamic and hydrostatic forces on the submerged surface of a TLP have been accurately calculated by excluding the assumption of the slender body theory. The hydrodynamic interactions among TLP members, such as columns and pontoons, and the structural damping are included in structural analysis. The spectral description used in spectral analysis of directional waves for the linear system of a TLP in the frequency domain is sufficient to completely define the structural responses. This is due to both the wave inputs and responses are stationary Gaussian random process of which the statistical properties in the amplitude domain are well known. The numerical results for the linear motion responses and tension variations in regular waves are compared with the experimental and numerical ones, which are obtained in Yoshida et al.(1983). The results of comparison confirmed the validity of the proposed approach.

• Resources Recycling
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• v.22 no.2
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• pp.62-70
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• 2013

Electric arc furnace slag is made in ironworks during steel refining, it is been increasing chemical and physical resistibility using ageing method of unstable state of melting steel slag for using concrete's fine aggregates. Which is been changing stable molecular structure of aggregates, it restrains moving of ion and molecule. In Korea, KS F 4571 has been prepared for using the electric arc furnace slag to concrete aggregates. In this study, Electric arc furnace slag is used in the PMC(Polymer Modified Concrete) which is applied a bridge pavement of rehabilitation, largely. In that case, this study evaluates the structural safety about increasing the specific weight. The 4-type bridges(RC slab bridge, RC rigid-frame bridge, PSC Beam bridge, Steel box girder bridge) pavement's increasing the total dead load is in 1 ~ 2%. Design moments in a load combination are increased less then 2%. safety factor is decreased less than 3%. Therefore, the structural safety has no problem for applying the electric arc furnace slag within PMC in bridge.

• Journal of the Korea Concrete Institute
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• v.29 no.1
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• pp.43-51
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• 2017

As per current seismic design codes, diagonally reinforced coupling beams are restricted to coupling beams having aspect ratio below 4. However, a grouped diagonally reinforcement detail makes distribution of steel bars in the beam much harder, furthermore it may result in poor construction quality. This paper describes the experimental results of concrete coupling beam reinforced with high-strength steel bars (SD500 & SD600 grades). In order to improve workability for fabricating coupling beams, a headed large diameter steel bar was used in this study. Two full-scale coupling beams were fabricated and tested with variables of reinforcement details and aspect ratio. To reflect real behavior characteristic of the beam coupling shear walls, a rigid steel frame system with linked joints was set on the reaction floor. As a test result, it was noted that cracking and yielding of reinforcement were initially progressed at the coupling beam-to-shear wall joint, and were progressed to the mid-span of the coupling beam, based on the steel strain and failure modes. It was found that the coupling beams have sufficient deformation capacity for drift ratio of shear wall corresponding to the design displacement in FEMA 450-1. In this study, the headed horizontal steel bar was also efficient for coupling beams to exhibit shear performance required by seismic design codes. For detailed design for coupling beam reinforced with high-strength steel, however, research about the effect of variable aspect ratios on the structural behavior of coupling beam is suggested.

• Journal of Korea Society of Industrial Information Systems
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• v.12 no.5
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• pp.39-46
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• 2007

Research on human identification in ubiquitous environment has recently attracted a lot of attention. As one of those research, gait recognition is an efficient method of human identification using physical features of a walking person at a distance. In this paper, we present a human shape extraction and tracking for gait recognition using geodesic active contour models(GACMs) combined with mean shift algorithm The active contour models (ACMs) are very effective to deal with the non-rigid object because of its elastic property. However, they have the limitation that their performance is mainly dependent on the initial curve. To overcome this problem, we combine the mean shift algorithm with the traditional GACMs. The main idea is very simple. Before evolving using level set method, the initial curve in each frame is re-localized near the human region and is resized enough to include the targe region. This mechanism allows for reducing the number of iterations and for handling the large object motion. The proposed system is composed of human region detection and human shape tracking modules. In the human region detection module, the silhouette of a walking person is extracted by background subtraction and morphologic operation. Then human shape are correctly obtained by the GACMs with mean shift algorithm. In experimental results, the proposed method show that it is extracted and tracked efficiently accurate shape for gait recognition.

• Smart Structures and Systems
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• v.14 no.2
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• pp.209-224
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• 2014

With more and more built long-term structural health monitoring (SHM) systems, it has been considered to apply monitored data to learn the reliability of bridges. In this paper, based on a long-term SHM system, especially in which the sensors were embedded from the beginning of the construction of the bridge, a method to calculate the localized reliability around an embedded sensor is recommended and implemented. In the reliability analysis, the probability distribution of loading can be the statistics of stress transferred from the monitored strain which covered the effects of both the live and dead loads directly, and it means that the mean value and deviation of loads are fully derived from the monitored data. The probability distribution of resistance may be the statistics of strength of the material of the bridge accordingly. With five years' monitored strains, the localized reliabilities around the monitoring sensors of a bridge were computed by the method. Further, the monitored stresses are classified into two time segments in one year period to count the loading probability distribution according to the local climate conditions, which helps us to learn the reliability in different time segments and their evolvement trends. The results show that reliabilities and their evolvement trends in different parts of the bridge are different though they are all reliable yet. The method recommended in this paper is feasible to learn the localized reliabilities revealed from monitored data of a long-term SHM system of bridges, which would help bridge engineers and managers to decide a bridge inspection or maintenance strategy.

• Journal of Korean Society of Steel Construction
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• v.19 no.2
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• pp.233-245
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• 2007

Previous finite element studies have shown that AASHTO Standard load distribution factor (LDF) equations appear to be conservative for longer spans and larger girder spacing, but too permissible for short spans and girder spacing. AASHTO LRFD specification defines the distribution factor equation for girder spacing, span length, slab thickness, and longitudinal stiffness. However, this equation requires an iterative procedure to correctly determine the LDF value due to an initially unknown longitudinal stiffness parameter. This study presents a simplified LDF equation for interior and exterior girders of two-span continuous I-girder bridges that does not require an iterative design procedure. The finite element method was used to investigate the effect of girder spacing, span length, slab thickness, slab width, and spacing and size of bracing. The computer program, GTSTRUDL, was used to idealize the bridge superstructures as the eccentric beam model, the concrete slab by quadrilateral shell elements, steel girders by space frame members, and the composite action between these elements by rigid links. The distribution factors obtained from these analyses were compared with those from the AASHTO Standard and LRFD methods. It was observed through the parametric studies that girder spacing, span length, and slab thickness were the dominant parameters compared with others. The LRFD distribution factor for the interior girder was found to be conservative in most cases, whereas the factor for the exterior girder to be unconservative in longer spans. Furthermore, a regression analysis was performed to develop simplified LDF formulas. The formulas developed in this study produced LDF values that are always conservative to those from the finite element method and are generally smaller than the LDF values obtained from the AASHTO LRFD specification. The proposed simplified equation will assist bridge engineers in predicting the actual LDF in two-span continuous I-girder bridges.

• Journal of the Earthquake Engineering Society of Korea
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• v.12 no.1
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• pp.1-9
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• 2008

In seismic response analysis of building structures, the input ground accelerations have considerable effect on the nonlinear response characteristics of structures. The characteristics of soil and the locality of the site where those ground motions were recorded affect on the contents of earthquake waves. Therefore, it is difficult to select appropriate input ground motions for seismic response analysis. This study describes a generation of artificial earthquake wave compatible with seismic design spectrum, and also evaluates the seismic response values of multistory reinforced concrete structures by the simulated earthquake motions. The artificial earthquake wave are generated according to the previously recorded earthquake waves in past major earthquake events. The artificial wave have identical phase angles to the recorded earthquake wave, and their overall response spectra are compatible with seismic design spectrum with 5% critical viscous damping. The input ground motions applied to this study have identical elastic acceleration response spectra, but have different phase angles. The purpose of this study is to investigate their validity as input ground motion for nonlinear seismic response analysis. As expected, the response quantifies by simulated earthquake waves present better stable than those by real recording of ground motion. It was concluded that the artificial earthquake waves generated in this paper are applicable as input ground motions for a seismic response analysis of building structures. It was also found that strength of input ground motions for seismic analysis are suitable to be normalize as elastic acceleration spectra.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.33 no.3
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• pp.84-94
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• 2015

This study is to examine how the admiration for Chutzu(朱子)'s achievement while he was preaching his policies after renouncing the world in Wuyi-Gugok(武夷九曲), Mt. Wuyi and Joseon-style transformation culture were unfolded and developed through Gugok management cases such as position, name, poetic diction, Jungsa(精舍) architecture and engraving of Muyi-Gugok set in Mt. Gugok, Snacheong. The results were as follows: Myungam(明庵) Jeong Sik(鄭拭, 1683~1746)'s Muyi-Gugok, which consists of Suhongkyo(垂虹橋, gok 1) - Oknyeobong(玉女峰) - Nhongwhaldam(弄月潭) - Nacwhadam(落花潭) - Daeeunbyeong(大隱屛) - Gwangpyungryea(光風瀨) - Jaewhaldae(霽月臺) - Gorooam(鼓樓巖) - Wharyongpok(臥龍瀑, gok 9) is the representative case where Chutzu's Wuyi-Gugok was exactly copied and fulfilled to the Joseon Dynasty. In a large frame, Gugok Wonlim culture, Myungam's Muyi-Gugok management has a will of succession of Dotong(道統) through admiration for Chutzu in a rigid way. Another name of Mt. Gugok is Mt. Muyi and Gugok's name is Muyi-Gugok and the residence existed between gok 4 and gok 5. In addition, the name of Jeongsa for Gugok management is also 'Muyi Jeongsa(武夷精舍)' and Gugok name and contents of Poetry are also similar and all of these are clear evidence that Myungam tries to copy Chutzu's Wuyi-Gugok to Mt. Gugok. Also, Gugok set before Myungam were located in Mt. Gugok and among them, verified four Gugok names are corresponded to those of Chutzu's Wuyi-Gugok and it tells that conforming behavior as one of admiration ways for Chutzu already arrived at Mt. Gugok before Myungam and this was an oppotunty to widen Mt. Gugok Muyi-Gugok's tradition and horizon. Also, considering that Myungam's gok 6, Gwangpyungryea and gok 7, Jewoldae are names from 'Gwangpungjewol(光風霽月)' Based on Chutzu's poem and they are closely related to Joseon's classical scholar spirit, they are associated with Joseon-style transformation of Chutzu's Muyi-Gugok. Meanwhile, gok 5 'Daeeunbyeong' was transformed to 'Nangaam(爛柯巖)' in gok 5 - "Deoksan-Gugok(德山九曲) of Jooko(竹塢) Ha Beom-Woon(河範運, 1792~1858) and those characters's engravings are handed down. In "Pome of Deoksan Gugok" transformed from Myungam's Muyi-Gugok, respect and admiration for Chutzu is weaken while Ha Beom-Woon admires Nammyeong(南冥) Cho shik(曺植, 1501~1572), a symbolic character of himself's school and from this, a movement to promote partisan unity is identified. After Myungam died, Muyi-Gugok in Mt. Gugok was transformed from a space to succeed Chutzu's Dotonga to one to commemorate the memory of ancient sages, but, it is a typicality case that widen the spectrum of Joseon's Gugok-Wonlim culture through Muyi-Gugok's imitation and transformation.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.73-80
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• 2022

In this study, details of NRC beam-column connections were developed in which beam and columns pre-assembled in factories using steel angles were bolted on site. The developed joint details are NRC-J type and NRC-JD type. NRC-J type is a method of tensile joining with TS bolts to the side and lower surfaces of the side plate of the NRC column and the end plate of the NRC beam. NRC-JD type has a rigid joint with high-strength bolts between the NRC beam and the side of the NRC column for shear, and with lap splices of reinforcing bar penetrating the joint and the beam main reinforcement for bending. For the seismic performance evaluation of the joint, three specimens were tested: an NRC-J specimen and NRC-JD specimen with NRC beam-column joint details, and an RC-J specimen with RC beam-column joint detail. As a result of the repeated lateral load test, the final failure mode of all specimens was the bending fracture of the beam at the beam-column interface. Compared to the RC-J specimen, the maximum strength of the specimen by the positive force was 10.1% and 29.6% higher in the NRC-J specimen and the NRC-JD specimen, respectively. Both NRC joint details were evaluated to secure ductility of 0.03 rad or more, the minimum total inter-story displacement angle required for the composite intermediate moment frame according to the KDS standard (KDS 41 31 00). At the slope by relative storey displacemet of 5.7%, the NRC-J specimen and the NRC-JD specimen had about 34.8% and 61.1% greater cumulative energy dissipation capacity than the RC specimen. The experimental strength of the NRC beam-column connection was evaluated to be 30% to 53% greater than the theoretical strength according to the KDS standard formula, and the standard formula evaluated the joint performance as a safety side.