• Journal of Ocean Engineering and Technology
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• v.35 no.5
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• pp.347-359
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• 2021

This study aims to evaluate the dynamic responses of the jacket-type offshore wind turbine using FAST software (Fatigue, Aerodynamics, Structures, and Turbulence). A systematic series of simulation cases of a 5 MW jacket-type offshore wind turbine, including wind-only, wave-only, wind & wave load cases are conducted. The dynamic responses of the wind turbine structure are obtained, including the structure displacement, rotor speed, thrust force, nacelle acceleration, bending moment at the tower bottom, and shear force on the jacket leg. The calculated time-domain results are transformed to frequency domain results using FFT and the environmental load with more impact on each dynamic response is identified. It is confirmed that the dynamic displacements of the wind turbine are dominant in the wave frequency under the incident wave alone condition, and the rotor thrust, nacelle acceleration, and bending moment at the bottom of the tower exhibit high responses in the natural frequency band of the wind turbine. In the wind only condition, all responses except the vertical displacement of the wind turbine are dominant at three times the rotor rotation frequency (considering the number of blades) generated by the wind. In a combined external force with wind and waves, it was observed that the horizontal displacement is dominant by the wind load. Additionally, the bending moment on the tower base is highly affected by the wind. The shear force of the jacket leg is basically influenced by the wave loads, but it can be affected by both the wind and wave loads especially under the turbulent wind and irregular wave conditions.

• International Journal of Naval Architecture and Ocean Engineering
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• v.12 no.1
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• pp.491-500
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• 2020

The present study proposes a time domain model for the Vortex-induced Vibration (VIV) simulation of a catenary riser under the combination of the current and oscillatory flow induced by vessel motion. In this model, the hydrodynamic force of VIV comprises excitation force, hydrodynamic damping and added mass, which are taken as functions of the non-dimensional frequency and amplitude ratio. The non-dimensional frequency is related with the response frequency, natural frequency, lock-in range and the fluid velocity. The relatively oscillatory flow induced by vessel motion is taken into account in the fluid velocity. Considering that the added mass coefficient and the non-dimensional frequency can affect each other, an iterative analysis is conducted at each time step to update the added mass coefficient and the natural frequency. This model is in detail validated against the published test models. The results show that the model can reasonably reflect the effect of the added mass coefficient on the VIV, and can well predict the riser's VIV under stationary and oscillatory flow induced by vessel motion. Based on the model, this study carries out the VIV simulation of a catenary riser with harmonic vessel motion. By analyzing the bending moment near the touchdown point, it is found that under the combination of the ocean current and oscillatory flow the vessel motion may decrease the VIV response, while increase the excited frequencies. In addition, the decreasing rate of the VIV under vessel surge is larger than that under vessel heave at small vessel motion velocity, while the situation becomes opposite at large vessel motion velocity.

• Korean Journal of Construction Engineering and Management
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• v.24 no.1
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• pp.51-60
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• 2023

This paper aims to propose a method for the systematic management of construction information using ontology. In particular, it was intended to propose a method to systematically manage the construction method information required by designers and constructors. The information used in this paper is a case of test-bed construction resulting from 10 years of modernized Hanok technology development research. The new construction methods of modernized Hanok were organized using the ontology editor, Protege. To this end, the concept of ontology and the process of constructing ontology have been summarized through a review of existing research first. A conceptual diagram for constructing a domain ontology of the modernized Hanok construction methods was then proposed, and the effectiveness of the proposed domain ontology was verified using the SPARQL Query function of Protege. Finally, the defined classes and construction method metadata were published on the web using ontology web language (OWL).

• Journal of the Korean Institute of Landscape Architecture
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• v.18 no.3 s.39
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• pp.99-113
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• 1990

The purpose of this study was to prepare some more up-dated and advanced curriculum in Landscape Architecture in Junior College education to bring up a leading professional who can meet the changing social needs. To achieve this goal, the data about the actual employment status of graduates, current relevant systems and legistations, the questionnaires of Landscape companies, graduates and undergraduates, and the current relevant curriculum of domain 6 junior colleges and Japanese relevant curriculum was gathered and analyzed The results are as follows ; 1. Currently the majority of the graduates are employed in Construction field, but the employment trend of graduates shows diversification and subdividing as following 5 fields, that is Construction, Design, Maintenance, Administration and Indoor Landscaping. 2. It is essential to bring up a Landscape Technician who has a Landscape Certificate of qualifications(esp. 2nd class). 3. Lately, the actual Practice came to be one item of the qualifying examination, so the subjects of Landscape Design, Landscape Construction and Landscape Estimation Should be emphasized, Accordingly, current curriculum should be revised. 4. Currant curriculum model(1979) made by the Ministry of Education doesn't play a real and adequate role and should be up-dated in view of the current curriculum of domain 6 junior colleges has no regular standards. In preparation for new standardized curriculum model, following criterior could be suggested, that is, ratio of the Major Required Subjects vs. The Major Optional Subjects would be 50 : 50, and the Major Optional Subject would be 48 credits which is 150% of the Required Credits(32 credits) 5. The subjects such as Basic Agriculture, Afforestation, Nature Conservation, Sketch, Civil Engineering, Landscape Seminar and Modelling Practice would be deleted in the curriculum model established in 1983. 6. The subjects such as Perspective Practice, Indoor Landscaping, Landscape Legislation and Landscape Design( III ) could be newly opened to meet the social needs, to prepare for the qualifying examination and to serve well in the employment fields. 7. The subjects of Surveying ( I ) & ( II ) would be unified into one Subject as Surveying, and some in view of the average situation of 6 junior colleges. 8. It is urgent to open some subject related to computer. At first, An Introduction to Computer could be recommended in the cultural studies course and Landscape Computer Technique as the Major Optional Subjects.

• Journal of Software Engineering Society
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• v.23 no.4
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• pp.151-163
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• 2010

In the defense software domain where large-scale software products in various application areas need to be built, reusing software is regarded as one of the important practices to build software products efficiently and economically. There have been many efforts to apply various methods to support software reuse in the defense software domain. However, developers in the defense software domain still experience many difficulties and face obstacles in reusing software assets. In this paper, we analyze practical problems of software reuse in the defense software domain, and define core requirements to solve those problems. To meet these requirements, we are currently developing the Component Grid system, a reuse-support system that provides a developer-centric software reuse environment. We have designed an architecture of Component Grid, and defined essential elements of the architecture. We have also developed the core approaches for developing the Component Grid system: a semantic-tagging-based requirement tracing method, a reuse-knowledge representation model, a social-network-based asset search method, a web-based asset management environment, and a wiki-based collaborative and participative knowledge construction and refinement method. We expect that the Component Grid system will contribute to increase the reusability of software assets in the defense software domain by providing the environment that supports transparent and efficient sharing and reuse of software assets.

• Journal of KIISE:Software and Applications
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• v.30 no.10
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• pp.955-972
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• 2003

As the next significant software abstraction, software agents have generated lots of excitements in recent years because of its promise as a new paradigm for conceptualizing, designing, and implementing software systems. This promise is particularly attractive for creating software that operates in environments that are distributed, open, and complex, such as the Internet. The effort of developing agent systems have, however, suffered from lack of generalized agent architecture because of various properties of an agent and nonexistence of a standard agent architecture. An agent architecture is an important criterion in order to not only identify agents in their domain but also determine the software architecture of the system. The major contribution of the work described here is an object-oriented design of an agent architecture that addresses fundamental properties, which are autonomy and interaction. Object-oriented design method is used for identifying the internal modules of an agent architecture and organizing correlation between the modules are identified.

• International Journal of Naval Architecture and Ocean Engineering
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• v.2 no.3
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• pp.146-154
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• 2010

In the present study, the wave excitation forces acting on an array of porous circular cylinders are examined based on diffraction problems. To calculate the wave forces, the fluid domain is divided into three regions i.e. a single exterior region, N interior regions and N beneath regions, and the diffraction in each fluid region is expressed by an eigenfunction expansion method with using 3-dimension liner potential theory (Williams and Li, 2000). Especially, the present method is extended to the case of an array of truncated porous circular cylinders to calculate the heave forces as well as surge and sway forces. To verify this method, the numerical results obtained by eigenfunction are compared with these results obtained by higher order boundary element method (Choi et al., 2000). The numerical results obtained by this study are in good agreement with those results. By changing the numbers of porous circular cylinders, the angle of incident wave and the porosity rate of circular cylinders, the wave excitation forces such as surge, sway and heave on an array of truncated porous circular cylinders are investigated.

• International Journal of Naval Architecture and Ocean Engineering
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• v.8 no.2
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• pp.188-197
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• 2016

Offshore substructures have been developed to support structures against complex offshore environments. The load at offshore substructures is dominated by waves, and deformation of waves caused by interactions with the current is an important phenomena. Wave load simulation of fixed offshore substructures in waves with the presence of uniform current was carried out by numerical wave tank technique using the commercial software, FLUENT. The continuity and Navier-Stokes equations were applied as the governing equations for incompressible fluid motion, and numerical wavemaker was employed to reproduce offshore wave environment. Convergence test against grids number was carried out to investigate grid dependency and optimized conditions for numerical wave generation were derived including investigation of the damping effect against length of the damping domain. Numerical simulation of wave and current interactions with fixed offshore substructure was carried out by computational fluid dynamics, and comparison with other experiments and simulations results was conducted.

• International Journal of Ocean System Engineering
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• v.3 no.4
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• pp.209-217
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• 2013

This paper presents a mooring design procedure for a floating offshore wind turbine. Offshore environmental data for Jeju are taken from KHOA (Korea Hydrographic and Oceanographic Administration) and used for the environmental conditions in numerical analyses. A semi-submersible-type floating wind system with a 5-MW-class wind turbine studied by the DeepCwind Consortium is applied. Catenary mooring with a studless chain is chosen as the mooring system. Design deliverables such as the nominal sizes of chain and length of the mooring line are decided by considering the long-term prediction of the breaking strength of the mooring lines where a 100-year return period is used. The designed mooring system is verified using a fatigue calculation based on rain-flow cycle counting, an S-N curve, and a Miner's damage summation of rule. The mooring tension process is obtained from time-domain motion analyses using ANSYS/AQWA.

• Journal of The Korea Institute of Healthcare Architecture
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• v.24 no.2
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• pp.55-64
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• 2018

Purpose: The ward division is a representative part of the hospital, where a variety of user activities are performed. Users can be broadly categorized as patients and carers, visitors, and medical staff (doctors and nurses). The relationship between these two is a major issue with ward planning as the patient's place of life centers around the hospital room and the task of the clinical workforce centers around the nursing station (NS). Against this backdrop, the study divides the ward units of the General Hospital of China into patient areas, medical team areas, supply areas, and public domain, with the focus on the ward areas affecting most significantly in the hospital patients. Methods: The theoretical advance studies of the standard ward unit are identified by the associated guidelines, articles, and documentation. Results: This study is a summary analysis of relevant regulations, reference literature, and drawing data from the target hospital. Further work is expected to be undertaken, including further surveys and observational surveys, to produce more detailed results. Implications: It is expected that the research in this paper will provide an effective reference for the future research of China General Hospital Ward department, so as to promote and improve the work system of China General Hospital Ward department.