• Journal of Korean Society of Coastal and Ocean Engineers
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• v.34 no.6
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• pp.211-221
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• 2022

The wave runup height is one of the most important parameters for affecting the design of coastal structures such as dikes, revetments, and breakwaters. In this study, SWASH (Zijlema et al., 2011), a non-hydrostatic pressure numerical model, was used to analyze the effect of reducing The wave runup height of solitary waves by submerged and floating rectangular obstacles. It was confirmed that the SWASH model reproduces the propagation, breaking, and runup of solitary waves quite well. In addition, it was confirmed that the wave deformation of the solitary wave by submerged and floating rectangular obstacles was well reproduced. Finally, we conducted an examination of the effect of reducing the runup height of submerged and floating rectangular obstacles. Reduced runup heights are calculated and the characteristics of runup height reduction according to the dimensions of the obstacle were analyzed. The energy attenuation effect of the floating obstacle is greater than the submerged obstacle, and it is shown to be more effective in reducing the runup height.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.64 no.7
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• pp.1081-1087
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• 2015

Recently, the researches of aerial drones are actively executed in various areas, the researches of surface drones and underwater drones are also executed in marine areas. In case of surface drones, they essentially utilize acoustic information by the sonar and consequently have the local information in the obstacle avoidance as the sonar has the limitations due to the beam width and detection range. In order to overcome this, more global method that utilizes optical images by the camera is required. Related to this, the aerial drone with the camera is desirable as the obstacle detection of the surface drone with the camera is impossible in case of the existence of clutters. However, the dynamic-floating aerial drone is not desirable for the long-term operation as its power consumption is high. To solve this problem, a collaborative obstacle avoidance method based on the acoustic information by the sonar of the surface drone and the optical image by the camera of the static-floating aerial drone is proposed. To verify the performance of the proposed method, the collaborative obstacle avoidances of a MSD(Micro Surface Drone) with an OAS(Obstacle Avoidance Sonar) and a BMAD(Balloon-based Micro Aerial Drone) with a camera are executed. The test results show the possibility of real applications and the need for additional studies.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.3
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• pp.248-257
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• 2011

In the present study, we proposed a new numerical wave tank model to analyze the vertical tension-leg circular floating bodies, using a 2-D Navier-Stokes solver. An IBM(Immersed Boundary Method) capable of handling interactions between waves and moving structures with complex geometry on a standard regular Cartesian grid system is coupled to the VOF(Volume of Fluid) method for tracking the free surface. Present numerical results for the motions of the floating body were compared with existing experimental data as well as numerical results based on FAVOR(Fractional Area Volume Obstacle Representation) algorithm. For detailed examinations of the present model, the additional hydraulic experiments for floating motions and free surface transformations were conducted. Further, the versatility of the proposed numerical model was verified via the numerical and physical experiments for the general rectangular floating bodies. Numerical results were compared with experiments and good agreement was archived.

• Journal of Environmental Science International
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• v.21 no.7
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• pp.825-835
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• 2012

This study for the development of water purification Artificial floating island maximizing domestic Artificial floating island patent trends and product development, according to the timing of patent registration was analyzed for trends. In addition, domestic invention patent technology Artificial floating island typed according to the purpose and characteristics of domestic patents were Artificial Floating Island. In particular, domestic leisure space with a growing population and the need for securing emerging role as a reservoir of water only in the past, who do appeal as a tourist destination or as an ecological space utilized, and accordingly will transform and the need to secure a hydrophilic, degrade water quality problems using this aquatic environment (water acquisition and hydrophilic), the requirements are a big obstacle is the reality factor. This patented product differentiation strategy through the analysis of the development of technology progressiveness (Field Application) in terms of water quality improvement and maintenance side, and the hydrophilic side scenery, ecological restoration aspects, and applicability to the field and taking into account existing technology economic aspects of distinction were presented and advertised a lot in terms of cost compared to other techniques without the use of highly efficient methodology for building a water purification and also appears identity appeal, wetlands, rivers, etc. can be applied broadly technician widespread deployment and installation time to less simple and more are expected to spread.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.25 no.4
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• pp.247-252
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• 2012

IGBT (insulated gate bipolar transistor) has been widely used around the power industry as it has good switching performance and its excellent conductance. In order to reduce power loss during switch turn-on state, it is essential to reduce its resistance. However, trade off relationship between breakdown voltage and device conductance is the greatest obstacle on the way of improvement. Floating island structure is one of the solutions. Still, under optimized device condition for the best performance, improvement rate is negligible. Therefore, this paper suggests adding trench gate on floating island structure to eliminate JFET (junction field effect transistor) area to reduce resistance and activate floating island effect. Experimental result by 2D simulation using TCAD, shows 20% improvement of turn-on state voltage drop.

• Current Photovoltaic Research
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• v.10 no.4
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• pp.121-132
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• 2022

The need for floating photovoltaic is being emphasized to expand renewable energy but low residents' acceptance is a major obstacle to the deployment of floating photovoltaic. Using the discrete choice experiment, this study analyzed the preferences for community-based floating photovoltaic projects and proposed a method to increase the residents' acceptance of floating photovoltaic projects. The estimates of the marginal willingness to accept (MWTA) of the distance, the coverage ratio, the landscape, the project owner (public institution), and the project owner (large company) are -0.69%p/km, 0.13%p/%p, -0.57%p, -2.95%p, -1.73%p, respectively. According to the result of simulation analysis, the residents' acceptance is significantly higher when the project is operated by a public institution, with a choice probability of 58%, than when the project is operated by a private company, with a choice probability of 29%, 12% for a large and small company, respectively. In addition, as a result of the analysis of the expected returns, the results show that the closer the distance from the residence to the power plant, the higher the expected return.

• IEMEK Journal of Embedded Systems and Applications
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• v.7 no.3
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• pp.143-150
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• 2012

In this paper, we introduce an intelligent quadruped walking robot that can perform stable walking and a couple of intelligent behaviors. The developed robot has two sets of ultrasonic sensors and six sets of infrared sensors and can perform obstacle avoidance by detecting obstacles and estimating the distances and directions of those obstacles. The robot also has a stereo camera and can paly soccer by detecting a ball and estimating the 3 dimensional coordinates of the ball. In performing those intelligent behaviors, the robot needs to have the capability of generating its walking patterns, solving the inverse kinematics problem, and interfacing several sensors in realtime. Therefore we designed a hierarchical controller that consists of a main controller and an auxiliary controller. The main controller is a 32-bit DSP that can perform fast floating-point opertaion and the auxiliary one is a 8-bit micro-controller. We showed that the developed quadruped walking robot successfully perform those intelligent behaviors through experiments.

• Journal of computational fluids engineering
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• v.20 no.2
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• pp.103-108
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• 2015

Fluid-body interaction analysis of floating body with six degree-of-freedom motion is presented. In this study, three-dimensional incompressible Navier-Stokes equations are employed as a governing equation. The numerical method is based on a finite-volume approach on a cartesian grid together with a fractional-step method. To represent the body motion, the immersed boundary method for direct forcing is employed. In order to simulate the coupled six degree-of-freedom motion, Euler's equations based on rigid body dynamics are utilized. To represent the complex body shape, level-set based algorithm is utilized. In order to describe the free surface motion, the volume of fluid method utilizing the tangent of hyperbola for interface capturing scheme is employed. This study showed three different continuums(air, water and body) are simultaneously simulated by newly developed code. To demonstrate the applicability of the current approach, two different problems(dam-breaking with stationary obstacle and water entry) are simulated and all results are validated.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.490-490
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• 2013

In semiconductor industry, it is expected that plasma process which use 450 mm source will be used at next generation. However, main obstacle of the large area plasma source is plasma uniformity from it. When electrode is enlarged, field difference between center area and side area reduces the plasma uniformity [1-3]. Therefore we investigate multi-electrode which diminish this field difference.We designed two multi-electrode models. One has two segments and the other has five segments. Each multi-electrode model is connected with two power generator and two matchers. One generator and one matcher is connected with center electrode part. The other one generator and the other one matcher is connected with side electrode part. The ion density is measured at 29 points by using floating harmonic method [4-6]. After measuring the data of each multi-electrode model, we discuss the difference of profile between two models' data.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.1
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• pp.172-178
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• 2021

In the ship repair market, interest in maintenance and repair is steadily increasing due to the reinforcement of prevention of environmental pollution caused by ships and the reinforcement of safety standards for ship structures. By reflecting this effect, the number of requests for repairs by foreign shipping companies increases to repair shipbuilders in the Southwest Sea. However, because most of the repair shipbuilders in the southwestern area are small and medium-sized companies, it is difficult to lead to the integrated synergy effect of the repair shipbuilding companies. Moreover, the infrastructure is not integrated; hence, using the infrastructure jointly is a challenge, which acts as an obstacle to the activation of the repair shipbuilding industry. Floating docks are indispensable to operating the repair shipbuilding business; in addition, most of them are operated through renovation/repair after importing aging caisson docks from overseas. However, their service life is more than 30 years; additionally, there is no structure inspection standard. Therefore, it is vulnerable to the safety field. In this study, the finite element analysis program of ANSYS was used to evaluate the structural safety of the modified caisson dock and obtain additional structural reinforcement schemes to solve the derived problems. For the floating docks, there are classification regulations; however, concerning structural strength, the regulations are insufficient, and the applicability is inferior. These insufficient evaluation areas were supplemented through a detailed structural FE-analysis. The reinforcement plan was decided by reinforcing the pontoon deck and reinforcement of the side tank, considering the characteristics of the repair shipyard condition. The final plan was selected to reinforce the side wing tank through the structural analysis of the decision; in addition, the actual structure was fabricated to reflect the reinforcement plan. Our results can be used as reference data for improving the structural strength of similar facilities; we believe that the optimal solution can be found quickly if this method is used during renovation/repair.