• Journal of Korean Society of Coastal and Ocean Engineers
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• v.26 no.1
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• pp.33-40
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• 2014

Reliability analysis of jacket type offshore wind turbine (OWT) support structure under extreme ocean environmental loads was performed. Limit state function (LSF) of OWF support structure is defined by using structural dynamic response at mud-line. Then, the dynamic response is expressed as the static response multiplied by dynamic response factor (DRF). Probabilistic distribution of DRF is found from response time history under design significant wave load. Band limited beta distribution is used for internal friction angle of ground soil. Wind load is obtained in the form of thrust force from commercial code called GH_Bladed and then, applied to tower hub as random load. In a numerical example, the response surface method (RSM) is used to express LSF of jacket type support structure for 5MW OWF. Reliability index is found using first order reliability method (FORM).

• Korean Security Journal
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• no.37
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• pp.29-50
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• 2013

With the recent global threats of terrorism as well as religious conflicts, Northeast Asian countries including South Korea, China, and Japan are experiencing particularly serious security crises as demonstrated by North Korea's threats of nuclear weapons testings and long-range missile launching as well as military provocation toward South Korea such as sinking of ROKS Cheonan and bombardment of Yeonpyeong island and the territorial dispute between China and Japan over Senkaku Islands(Diaoyu Islands). As a result, Park Geun Hye Administration of South Korea and the 2nd Abe Shinzo Cabinet of Japan, both recently established, are making efforts to improve their national security and crisis management policies. One of the key elements of such efforts is the strengthening of National Security Council(NSC) or its equivalent organization as the control tower of national security policy, modeled after the NSC of the United States. This paper compares NSC organization of Korea, the U.S., and Japan and draws policy insights focusing on the current political and national security situation South Korea is facing. Although organizational structure, function, and history of NSC of each country differs, it can be inferred from this comparison that NSC-type of organizations can play an important role as a control tower of security and emergency management policies.

• Journal of architectural history
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• v.19 no.6
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• pp.39-59
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• 2010

Seokgatap and Dabotap are representing the tower patterns in "Gyeonbotappum" of the Lotus Sutra. It is very peculiar, for the description on "Gyeonbotappum" is usually made in terms of 'the two Buddhas sitting side by side'. If 'the two Buddhas sitting side by side' is describing the situation in Dabotap, the double structure of Seokgatap and Dabotap can be said to symbolize the scriptural description in a different viewpoint. Its correct comprehension is pretty important in understanding Bulguksa. For this, this paper first arranged the critical minds and flows about the faith objects in Indian Buddhism. And, it was considered how these aspects were accumulated through Saddharma-pundarika sutra. Secondly, it was considered why "Gyeonbotappum" took the typical symbolism in Saddharma-pundarika sutra(Lotus Sutra). These parts should be necessarily considered in advance in that Seokgatap and Dabotap were derived from the form of "Gyeonbotappum". Based on this approach, the author checked the actual aspects of Seokgatap that the tower was built on a natural rock ground and the stones surrounding the tower are constituting the 8-directional Lotus site. With these two aspects, we could get the clue on the foundation time of Bulguksa that its founder had intended. In that Dabotap was formed on the basis of "Gyeonbotappum", the features of Dabotap is very important in comprehending its foundation viewpoint. As a result, the viewpoint of double towers in Bulguksa can be said to be the one that the world of suffering was to change to the Pure Land after Sakyamuni preached the Lotus Sutra on the top of Mt. Grdhrakuta and Prabhutaratna-tathagata proved it. This foundation viewpoint shows us clearly that 'the Lotus Buddhist Country' existed in parallel to the Avatamska Buddhist Country. It secures an appropriate meaning in that it can complement or adjust our understanding on the 'Buddhist country (Bulguk)' of Bulguksa where the Avatamska Idea is emphasized relatively highly as shown in the whole title of Bulguksa as 'Avatamska Bulguksa.'

• International Journal of High-Rise Buildings
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• v.5 no.1
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• pp.43-50
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• 2016

The reinforced-concrete multi-story shear-wall structure, which can free a building from beams and columns to allow the planning of a vast room, has increasingly been used in Japan as a high-rise reinforced-concrete structure. Since this structural system concentrates the seismic force onto multi-story shear walls inside, the bending deformation of the walls may cause excessive deformation on the upper floors during an earthquake. However, it is possible to control the bending deformation to within a certain level by setting high-strength and rigid beams (outriggers) at the top of the multi-story shear walls; these outriggers restrain the bending behavior of the walls. Moreover, it is possible to achieve high energy dissipation by placing vibration control devices on the outriggers and thus restrain the bending behavior. This paper outlines the earthquake response analysis of a high-rise residential tower to demonstrate the effectiveness of the outrigger frame incorporating vibration control devices.

• Structural Engineering and Mechanics
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• v.43 no.4
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• pp.545-560
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• 2012

Design codes provide the minimum requirements for the design of code-compliant structures to ensure the safety of the life and property. As for code-exceeding buildings, the requirements for design are not sufficient and the approval of such structures is vague. In mainland China in recent years, a large number of code-exceeding tall buildings, whether their heights exceed the limit for the respective structure type or the extent of irregularity is violated, have been constructed. Performance-based seismic design (PBSD) approach has been highly recommended and become necessary to demonstrate the performance of code-exceeding tall buildings at least equivalent to code intent of safety. This paper proposes the general methodologies of performance-based seismic analysis and design of code-exceeding tall buildings in Mainland China. The PBSD approach proposed here includes selection of performance objectives, determination of design philosophy, establishment of design criteria for structural components and systems consistent with the desirable and transparent performance objectives, and seismic performance analysis and evaluation through extensive numerical analysis or further experimental study if necessary. The seismic analysis and design of 101-story Shanghai World Financial Center Tower is introduced as a typical engineering example where the PBSD approach is followed. The example demonstrates that the PBSD approach is an appropriate way to control efficiently the seismic damage on the structure and ensure the predictable and safe performance.

• Structural Engineering and Mechanics
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• v.23 no.6
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• pp.635-649
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• 2006

The static and dynamic responses of guyed telecommunication towers can be determined by using two models, the space truss element model, and the equivalent beam-column element model. The equivalent beam-column analysis is based on the determination of the equivalent shear, torsion, and bending rigidities as well as the equivalent area of the guyed mast. In the literature, two methods are currently available to determine the equivalent properties of lattice structures, namely: the unit load method, and the energy approach. In this study, an equivalent beam-column analysis is introduced based on an equivalent thin plate approach for lattice structures. A finite-element modeling, using suitably modified ABAQUS software, is used to investigate the accuracy of utilizing the different proposed methods in determining the static and dynamic responses of a guyed tower of 364.5-meter high subjected to static and seismic loading conditions. The results from these analyses are compared to those obtained from a finite-element modeling of the actual structure using 3-D truss and beam elements. Good agreement is shown between the different proposed beam-column models, and the model of the actual structure. However, the proposed equivalent thin plate approach is simpler to apply than the other two approaches.

• Journal of KSNVE
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• v.8 no.5
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• pp.949-956
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• 1998

Complex and large lattice type structures are frequently used in design of bridge, tower, crane and aerospace structures. In general, in order to analyze these structures we have used the finite element method(FEM). This method is the most widely used and powerful method for structural analysis lately. However, it is necessary to use a large amount of computer memory and computational time because the FEM requires many degrees of freedom for solving dynamic problems exactly for these complex and large structures. For analyzing these structures on a personal computer, the authors developed the transfer stiffness coefficient method(TSCM). This method is based on the concept of the transfer of the nodal dynamic stiffness coefficient matrix which is related to force and displacement vector at each node. And we suggested TSCM for free vibration analysis of complex and large lattice type structures in the previous report. In this paper, we formulate forced vibration analysis algorithm for complex and large lattice type structures using extened TSCM. And we confirmed the validity of TSCM through computational results by the FEM and TSCM, and experimental results for lattice type structures with harmonic excitation.

• Wind and Structures
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• v.17 no.6
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• pp.629-646
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• 2013

One of the most common solutions adopted to reduce vibrations of skyscrapers due to wind or earthquake action is to add external damping devices to these structures, such as a TMD (Tuned Mass Damper) or TLCD (Tuned Liquid Column Damper). It is well known that a TLCD device introduces on the structure a nonlinear damping force whose effect decreases when the amplitude of its motion increases. The main objective of this paper is to describe a Hardware-in-the-Loop test able to validate the effectiveness of the TLCD by simulating the real behavior of a tower subjected to the combined action of wind and a TLCD, considering also the nonlinear effects associated with the damping device behavior. Within this test procedure a scaled TLCD physical model represents the hardware component while the building dynamics are reproduced using a numerical model based on a modal approach. Thanks to the Politecnico di Milano wind tunnel, wind forces acting on the building were calculated from the pressure distributions measured on a scale model. In addition, in the first part of the paper, a new method for evaluating the dissipating characteristics of a TLCD based on an energy approach is presented. This new methodology allows direct linking of the TLCD to be directly linked to the increased damping acting on the structure, facilitating the preliminary design of these devices.

• Journal of the Korean Institute of Landscape Architecture
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• v.33 no.6 s.113
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• pp.127-139
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• 2006

Mt. Yokmang landscape design awarded first in [North container terminal site furtherance construction in Busan new port], design competition sponsoring in the Korea Container Terminal Authority in 2005. Design guideline was to propose the symbol of new port and to establish landscape plan in consideration of view and geological location. Because landscape plan required establishment of restoration plan for cutting slope, Mt. Yokmang became the major object. The purpose of planning are as follows. The first purpose is to minimize existent natural environment damage, and the second, to connect with ambit and create new image. The third is to provide place of rest and interchange for local resident. Reflecting stratum structure and landscape characteristics, cutting slope consisted of [utilization slope], [presentation slope], [landscape slope], and [ecological slope]. Vegetation design applied ecological restoration method through restoration of stratum, and eve environment-friendly afforestation, planned program that can connect area with existing ecosystem. In process that decides form of the cutting slope, analyze view structure and visual exposure in various access routes, sensitivity etc. was accomplished. Also, symbolic tower(Ocean Polaris) that presents in architecture and landscaping features, night landscape planning could gain synergy effect by keeping consistence with landscape and ecological planning. Passing through final design and construction process, I expect that the Mt. Yokmang will be a new landmark in Busan new port.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.2
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• pp.106-110
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• 1998

The $LiNbO_3$ thin films were prepared directly on Si(100) substrates by conventional RF magnetron spurttering system for nonvolatile memory applications. RTA(Rapid Thermal Annealing) treatment was performed for as-deposited films in an oxygen atmosphere at 600 $^{\circ}C$ for 60 s. The rapid thermal annealed films were changed to poly-crystalline ferroelectric nature from amorphous of as-deposition. The resistivity of the ferroelectric $LiNbO_3$ film was increased from a typical value of $1{\sim}2{\times}10^8{\Omega}{\cdot}cm$ before the annealing to about $1{\times}10^{13}{\Omega}{\cdot}cm$ at 500 kV/cm and reduced the interface state density of the $LiNbO_3/Si$ (100) interface to about $1{\times}10^{11}/cm^2{\cdot}eV$. Ferroelectric hysteresis measurements using a Sawyer-Tower circuit yielded remanent polarization ($P_r$) and coercive field ($E_c$) values of about 1.2 ${\mu}C/cm^2$ and 120 kV/cm, respectively.