Rho-Taek Jung

Application of tidal energy for purification in fresh water lake

ABSTRACT In order to preserve the quality of fresh water in the artificial lake after the reclamation of an intertidal flat at the mouth of a river, we suggest two novel methods of water purification by using tidal potential energy and an enclosed permeable embankment called an utsuro (Akai et al., 1990) in the reclaimed region. One method uses an inflatable bag on the seabed within an utsuro, while the other uses a moored floating barge out of a dyke. Each case employs a subsea pipe to allow flow between the inside and outside of the utsuro. The change in water level in the utsuro, which is pushed through the pipe by the potential energy outside, caused circulation in the artificial lake. In this paper, we analyzed the inflatable bag and floating barge motion as well as the pipe flow characteristics and drafts as given by a harmonic sea level, and compared the theoretical value with an experimental value with a simple small model basin. The numerical calculation based on theory showed good agreement with experimental values.

Recent International Development on the Technical and Operational Measures of IMO's CO 2 Emission Control From Ships

Since 2003, policies and practices related to the reduction of CO2 gas emission from ships has been discussing by the International Maritime Organization. The representative emission index and indicator are the EEDI (Energy Efficiency Design Index) for the new ships and EEOI (Energy Efficiency Operational Indicator) during the voyage. For the CO2 emission monitoring system, the SEEMP (Ship Energy Efficiency Management Plan) is also on the table. This global preparations to reduce theCO2 emission is not except for the surface transportation. This research report elucidates the recent stream on the IMO CO2 emission from ship and detail explanation on the EEDI and EEOI.

Feasibility Study on the Two-dimensional Free Surface Simulation Using the Lattice-Boltzmann Method

Abstract − The numerical simulation using the Lattice Boltzmann Method in the field of computational fluiddynamics becomes wider in the engineering applications because of its simplicity of update rules compared tothe conventional Navier-Stokes solvers. Here, a two-dimensional D2Q9 LB model is numerically tested with afew new computational treatment on the free surface. The single relaxation time is applied under the gravita-tional field where applied only in the higher density fluid because of its big density difference. At the free sur-face, the reconstruction techniques in combination with boundary conditions is adopted in order to get somedistribution function coming into the fluid site from the air one, and surface tension, early stable test for thegravitional field is considered in it. With the implementation of the gravitational profile, conserving the overallmass and grid dependency are observed during the calculations and freesurface advance track is well capturedwith an experiment.Keywords: 격자볼츠만방법(Lattice-Boltzmann Method), 댐붕괴 시뮬레이션(Dam-breaking Simulation), 2차원 9방향(D2Q9)

Study on the Free Surface Behavior Using the Lattice Boltzmann Method

Abstract − The boltzmann equation is based on the particle distribution function while the Navire-Stokes equa-tion based on the continuum theory. In order to simulate free surface flow, this paper used the Lattice Boltz-mann Method of which is the discretized form. The detail study on the characteristics of the Lattice BoltzmannMethod for the free surface simulation was investigated. The developed code was validated with the traditionaldam breaking problem by tracking the front position of the water. A basic roles of density functions in the Lat-tice Boltzmann Method is discussed. To have an engineering applications, the simulation is also conducted thefree surface behavior with an arbitrary wall geometry.Keywords: Lattice-Boltzmann Method(격자볼츠만법), Dam-breaking Simulation(댐붕괴 시뮬레이션), D2Q9(2차원 9방향), Inclined wall(경사면 ) 1. 서론 공간과 시간에 따라 변화하는 유체현상을 시뮬레이션 할 경우,관심영역(공간스케일, 시간스케일)을 정의하게 된다. 주로 유체 시뮬레이션시 활용되는 Navier-Stokes방정식은 비교적 작은 Knudsen수 1) 의 범위에 해당하며, 이것은 실제 공학적으로 관심을 가지는 스케일이다. 컴퓨터 파워가 증가됨에 따라 보다 작은 계산영역에서유체해석을 시도하고 있지만 입자 운동학적 효과가 주요한 현상을시뮬레이션하기 위해서는 한계영역이 존재 한다.Lattice Boltzmann Method(격자볼츠만법)는 Naiver-Stokes방정식의 공학적 스케일을 포함할 뿐만 아니라 입자 스케일까지도 시뮬레이션이 가능하다(분자단위 제외). Lattice Boltzmann Equation(볼츠만방정식)으로부터이산화된격자볼츠만법은보다 넓은Knudsen수의 범위를 포함하고 있고 단순한 이산화과정으로 인해전산코드개발이 쉬운 장점이 있어 원자력 분야의 비등현상(Kato etal.[1997]), 폼 기하학([Korner et al.[2005]), 결정체동력학(Lu et al.[2009])등의 Meso 스케일 분야 뿐만 아니고, 윈드터빈 블레이드 공력해석(Kim et al.[2012])등에도 유용한 전산해석법으로 활용되고있다.격자볼츠만법이 비압축성 유동을 풀수 있는 근거가 마련된 것도1990년대 후반이며(He et al.[1997]), 다상류 유동 중에서 격자볼츠만법을 이용한 자유수면 해석법은 비교적 최근에 연구된 분야이다(Thurey[2003]).본 논문에서는 2차원 9방향(D2Q9) 방식으로 중력장하에서 물-

A Study on a Practical Treatment System for the Wasted FRP Vessels in Korea

FRP(fiber-reinforced plastic) vessels, which have been abandoned on seashores, harbors and rivers on a nationwide scale, have become a matter of public concern. One of the reasons is that suitable technology and related national regulations have not been adequately addressed. As increasing the over-used FRP vessels in Korea, it is needed to develop an environment friendly treatment circumstance in a front-end process for the FRP vessels. In order to cope with the FRP vessels, we have been developed the new FRP melting system for the end process which is replaced by the incineration-after-reclamation at the past way. Also we introduce an economical assessment for several steps in the front- end process because it is related to the treatment cost for FRP vessels which are wasted or landlords who want it to be obsolete.

Development of real-time underwater acoustic equipment for deep sea survey

The marine litter is known as a major source of the destruction of the marine ecosystem and its components. Especially the problem caused by the derelict fishing nets is called the ghost fishing. In order to understand and to solve the problems raised by marine litters, we developed a practical and efficient real-time survey system for deep sea environment. This system consists of a guide frame called Tow-sled, a real-time deep-sea camera, position tracking devices and etc. The present paper shows the results of the development of the equipment to survey the marine litter such as fishing net in deep sea environment.