(A) study on application of metamaterials to control seismic and tsunami waves = 지진파와 쓰나미파를 제어하는 메타물질 응용에 대한 연구

다국어 초록 (Multilingual Abstract)

Earthquakes are a natural phenomenon, it is formed by the slide,
breaking the surface and inside Earth. According to the The United
States Geological Survey, there are about 1,000,000 earthquakes
occurring around the world in a year. Earthquakes occur frequently
unleash a huge energy and creates seismic waves. This wave creates
damage to buildings and infrastructure as they move through. Not only
that, the earthquake was one of the main reasons to form offshore
tsunami.
Earthquake and tsunami disaster that two people often face. It caused
enormous losses of human lives and property. December 2004,
magnitude earthquake occurred about 9.3 Ritcher, Indian Ocean, it has
created a tsunami with wave heights of about 20 meters when approach
a shore. According to estimates more than 200,000 people died and lost
hundreds of millions of people affected as homeless ... In 2011, off the
coast of Japan and an earthquake occurred with magnitude of about 9.0
Ritcher, then a tsunami wave was formed. According to estimates of
organized Japan, approximately 15,000 people died in the tsunami, more than 300 bridges broken and so much other infrastructure ruined.
This is also the earthquake, tsunami caused nuclear leakage.
There are many buildings damaged by the displacement and relocation
of the building which is caused by the displacement of the ground. The
solution reduces the movement of building, displacements of structures
during ground movement is one of the current methods are engineers
build is capacitance. In addition to the damage being caused by the
motion, other works damaged by the energy of the earth when the quake
occurred on the building, to minimize the damage caused by this,
engineers commonly used methods of energy absorption when
designing structures
So far, engineer’s coastal protection has many methods to prevent and
mitigate the impact of the waves, but the methods to prevent the impact
of the tsunami is still used seawall. In terms of structure, the barrier wall
tsunami waves just another wall, but the height of the tsunami as it
approached the coast is huge so a height tsunami wall is also huge. A
new form seawall has a height change on the water level to be studied
by a team of Japanese researchers.
In 1968, Russian scientist published his study, he pointed out that it is
possible to create materials with a negative refractive index. He laid the
foundation for the development of metamaterials today. In recent
decades, scientists have a lot of research on metamaterials and it also
has a lot of achievements. A material that can adjust the path of the
waves. But most of the studies are applied to electromagnetic waves,
there are few studies on the acoustic wave and not have to publish
applications in the construction field.
In this study, two lenses with interesting properties, the lens has the
ability to converge the rays at a point on the edge of the lens, often
called lens Luneburg. Other lens capable of bending wave beam enters
in the lens and turn back the broadcast source commonly known as
Eaton lens 180, will be introduced and applied. The two lenses are
research and development for electro-magnetic waves and it is made
from homogeneous material are modified to obtain near refractive index
as desired.
Two lenses will be redesigned to be able to deploy the practical easier.
The structure of the two lenses are constructed from steel bars with
circular cross-sections for the two-dimensional lens and spherical for 3D. In the two-dimensional space of the different positions of the
crystal size circular cross section will have different radii. Similarly, to
the three-dimensional space, the different positions, the radius of the
sphere will be different.
For convergence Luneburg lens in two-dimensional space is built by
the steel bars with circular cross-sections will be tested at some position
to confirm the results of design and simulation.