• 전자공학회논문지B
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• 제32B권3호
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• pp.24-30
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• 1995

The process of conventional floating-point additio $n_traction operation consists of alignment, additio $n_traction, normalization, and rounding stage. Because rounding stage needs an incrementor or adder, it occupies much time and chip area. In addition, it needs additional time and hardware for renormalization which occurs in overflow due to rounding In this paper, floating-point adde $r_tractor performing rounding and additio $n_traction in parallel is presented by using the feature of additio $n_traction and carry select adder used in additio $n_tracting stage. Proposed floating point adde $r_tractor doesn't need time and incrementor nor adder for rounding. Also, renormalization doesn't occur since rounding is performed prior to normalization.to normalization.

• 한국BIM학회 논문집
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• 제9권1호
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• pp.22-31
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• 2019

In this paper, we construct a prototype model for city data prediction by using time series data of floating population, and use machine learning to analyze urban data of complex structure. A correlation prediction model was constructed using three of the 10 data (total flow population, male flow population, and Monday flow population), and the result was compared with the actual data. The results of the accuracy were evaluated. The results of this study show that the predicted model of the floating population predicts the correlation between the predicted floating population and the current state of commerce. It is expected that it will help efficient and objective design in the planning stages of architecture, landscape, and urban areas such as tree environment design and layout of trails. Also, it is expected that the dynamic population prediction using multivariate time series data and collected location data will be able to perform integrated simulation with time series data of various fields.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.83-88
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• 2013

The purpose of this study is to develop the algorithm for dynamic interaction analysis of submerged floating tunnel and vehicles. The dynamic behavior characteristic of submerged floating tunnel is certainly different with general structures, because the submerged floating tunnel is floating in the middle of water, and subjected to constant buoyance. Therefore the analyses in various aspects should be carried out to secure structural stability and practicality of structures. To conduct the dynamic interaction analysis, the structure is modeled by commercial FEM program ABAQUS to investigate modal characteristic. Also the added mass concept is applied to represent the inertial force by a fluid, and then dynamic interaction analyses are conducted with superposition method when the KTX is moving along the submerged floating tunnel. And the time histories are presented for vertical and lateral displacement at the center of the tunnel.

• 대한조선학회논문집
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• 제54권2호
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• pp.90-95
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• 2017

In case of working for the construction of blocks of any ship in a floating dry dock, there may exist deflection in the pontoon deck of the floating dock due to the ballast loading and the self weight of the ship and the floating dock. This paper is on the development of the measuring system and the GUI program to show the real time variation of the deflections at even-spaced positions by several pressure gages and the calculated inclination of the floating dock. The measured and calculated data produced by this developed system could be used to prepare the protection plan on site like ballast adjustment to ensure the safety of working during the floating dock operation.

• 한국해양공학회지
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• 제29권3호
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• pp.255-262
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• 2015

The present study developed a numerical simulation tool for the coupled dynamic analysis of multiple turbines on a single floater (or Multiple Unit Floating Offshore Wind Turbine (MUFOWT)) in the time domain, considering the multiple-turbine aero-blade-tower dynamics and control, mooring dynamics, and platform motions. The numerical tool developed in this study was designed based on and extended from the single-turbine analysis tool FAST to make it suitable for multiple turbines. For the hydrodynamic loadings of floating platform and mooring-line dynamics, the CHARM3D program developed by the authors was incorporated. Thus, the coupled dynamic behavior of a floating base with multiple turbines and mooring lines can be simulated in the time domain. To investigate the effect of asymmetric aerodynamic loading on the global performance and mooring line tensions of the MUFOWT, one turbine failure case with a fully feathered blade pitch angle was simulated and checked. The aerodynamic interference between adjacent turbines, including the wake effect, was not considered in this study to more clearly demonstrate the influence of the asymmetric aerodynamic loading on the MUFOWT. The analysis shows that the unbalanced aerodynamic loading from one turbine in MUFOWT may induce appreciable changes in the performance of the floating platform and mooring system.

• 한국해양공학회지
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• 제24권5호
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• pp.16-21
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• 2010

During the loading/offloading operation of a liquefied natural gas carrier (LNGC) that is moored in a side-by-side configuration with an offshore plant, sloshing that occurs due to the partially filled LNG tank and the interactive effect between the two floating bodies are important factors that affect safety and operability. Therefore, a time-domain software program, called CHARM3D, was developed to consider the interactions between sloshing and the motion of a floating body, as well as the interactions between multiple bodies using the potential-viscous hybrid method. For the simulation of a floating body in the time domain, hydrodynamic coefficients and wave forces were calculated in the frequency domain using the 3D radiation/diffraction panel program based on potential theory. The calculated values were used for the simulation of a floating body in the time domain by convolution integrals. The liquid sloshing in the inner tanks is solved by the 3D-FDM Navier-Stokes solver that includes the consideration of free-surface non-linearity through the SURF scheme. The computed sloshing forces and moments were fed into the time integration of the ship's motion, and the updated motion was, in turn, used as the excitation force for liquid sloshing, which is repeated for the ensuing time steps. For comparison, a sloshing motion coupled analysis program based on linear potential theory in the frequency domain was developed. The computer programs that were developed were applied to the side-by-side offloading operation between the offshore plant and the LNGC. The frequency-domain results reproduced the coupling effects qualitatively, but, in general, the peaks were over-predicted compared to experimental and time-domain results. The interactive effects between the sloshing liquid and the motion of the vessel can be intensified further in the case of multiple floating bodies.

• 한국태양에너지학회 논문집
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• 제37권1호
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• pp.1-14
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• 2017

A series of coupled time domain simulations considering stochastic waves and wind based on five 1-h time-domain analyses are performed in normal operating conditions. Power performance and tower base Fore-Aft bending moment and pitching motion response of the floating spar-buoy wind turbine with 2 MW direct-drive PMSG have been analyzed by using HAWC2 that account for aero-hydro-servo-elastic time domain simulations. When the floating spar-buoy wind turbine is tilted in the wind direction, maximum of platform pitching motion is close to $4^{\circ}$. Statistical characteristics of tower base Fore-Aft bending moment of floating spar-buoy wind turbine are compared to that of land-based wind turbine. Maximum of tower base Fore-Aft bending moment of floating spar-buoy wind turbine and land-based wind is 94,448 kNm, 40,560 kNm respectively. This results is due to changes in blade pitch angle resulting from relative motion between wave and movement of the floating spar-buoy wind turbine.

• 국제강구조저널
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• 제18권4호
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• pp.1191-1199
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• 2018

Concepts of submerged floating tunnels (SFTs) for land connection have been continuously suggested and developed by several researchers and institutes. To maintain their predefined positions under various dynamic environmental loading conditions, the submerged floating tunnels should be effectively moored by reasonable mooring systems. With rational mooring systems, the design of SFTs should be confirmed to satisfy the structural safety, fatigue, and operability design criteria related to tunnel motion, internal forces, structural stresses, and the fatigue life of the main structural members. This paper presents a feasibility study of a submerged floating tunnel moored by an inclined tendon system. The basic structural concept was developed based on the concept of conventional cable-stayed bridges to minimize the seabed excavation, penetration, and anchoring work by applying tower-inclined tendon systems instead of conventional tendons with individual seabed anchors. To evaluate the structural performance of the new type of SFT, a hydrodynamic analysis was performed in the time domain using the commercial nonlinear finite element code ABAQUS-AQUA. For the main dynamic environmental loading condition, an irregular wave load was examined. A JONSWAP wave spectrum was used to generate a time-series wave-induced hydrodynamic load considering the specific significant wave height and peak period for predetermined wave conditions. By performing a time-domain hydrodynamic analysis on the submerged floating structure under irregular waves, the motional characteristics, structural stresses, and fatigue damage of the floating tunnel and mooring members were analyzed to evaluate the structural safety and fatigue performance. According to the analytical study, the suggested conceptual model for SFTs shows very good hydrodynamic structural performance. It can be concluded that the concept can be considered as a reasonable structural type of SFT.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2011년도 추계학술대회
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• pp.3-4
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• 2011

This paper presents a survey of floating power supply based on bootstrap operation for three-level voltage-source inverters. The floating power supply for upper switches is achieved by the bootstrap capacitor charged during on-time of the switch underneath. Hence, a large number of bulky isolated DC/DC power supplies for each gate driver are reduced. The Pspice simulation results show the behavior of bootstrap devices and the performance of bootstrap capacitor voltage.

• Structural Engineering and Mechanics
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• 제74권4호
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• pp.521-532
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• 2020

A floating dry dock is an advanced structure that can provide a solution for dry dock space shortages. The critical point in floating dock operation is compensating the deflection caused by a heavy payload by adjusting the water level in the ballast system. An appropriate ballasting plan warrants safe and precise construction on a floating dock. Particularly, in the case of a 2D floating dock, ballasting plan evaluation is crucial due to complex deformation modes. In this paper, we developed a method to calculate the optimal ballasting plan for accurate and precise construction on a 2D floating dock. The finite element method was used for considering the flexibility of the floating dock as well as the construction blocks. Through a gradient-based optimization algorithm, the optimal ballasting plan for the given load condition was calculated in semi-real time (5 min). The present method was successfully used for the actual construction of an offshore structure on the 2D floating dock.