8 research outputs found
Construction and Verification of a High-Precision Base Map for an Autonomous Vehicle Monitoring System
For autonomous driving, a control system that supports precise road maps is required to monitor the operation status of autonomous vehicles in the research stage. Such a system is also required for research related to automobile engineering, sensors, and artificial intelligence. The design of Google Maps and other map services is limited to the provision of map support at 20 levels of high-resolution precision. An ideal map should include information on roads, autonomous vehicles, and Internet of Things (IOT) facilities that support autonomous driving. The aim of this study was to design a map suitable for the control of autonomous vehicles in Gyeonggi Province in Korea. This work was part of the project “Building a Testbed for Pilot Operations of Autonomous Vehicles”. The map design scheme was redesigned for an autonomous vehicle control system based on the “Easy Map” developed by the National Geography Center, which provides free design schema. In addition, a vector-based precision map, including roads, sidewalks, and road markings, was produced to provide content suitable for 20 levels. A hybrid map that combines the vector layer of the road and an unmanned aerial vehicle (UAV) orthographic map was designed to facilitate vehicle identification. A control system that can display vehicle and sensor information based on the designed map was developed, and an environment to monitor the operation of autonomous vehicles was established. Finally, the high-precision map was verified through an accuracy test and driving data from autonomous vehicles
High-Pressure Chemistry of a Zeolitic Imidazolate Framework Compound in the Presence of Different Fluids
Pressure-dependent structural and
chemical changes of the zeolitic
imidÂazolate framework compound ZIF-8 have been investigated
using different pressure transmitting media (PTM) up to 4 GPa. The
unit cell of ZIF-8 expands and contracts under hydrostatic pressure
depending on the solvent molecules used as PTM. When pressurized in
water up to 2.2(1) GPa, the unit cell of ZIF-8 reveals a gradual contraction.
In contrast, when alcohols are used as PTM, the ZIF-8 unit cell volume
initially expands by 1.2% up to 0.3(1) GPa in methanol, and by 1.7%
up to 0.6(1) GPa in ethanol. Further pressure increase then leads
to a discontinuous second volume expansion by 1.9% at 1.4(1) GPa in
methanol and by 0.3% at 2.3(1) GPa in ethanol. The continuous uptake
of molecules under pressure, modeled by the residual electron density
derived from Rietveld refinements of X-ray powder diffraction, reveals
a saturation pressure near 2 GPa. In non-penetrating PTM (silicone
oil), ZIF-8 becomes amorphous at 0.9(1) GPa. The structural changes
observed in the ZIF-8-PTM system under pressure point to distinct
molecular interactions within the pores
Method for clearance of contaminated buildings in Korea research reactor 1 and 2
The objective of this study was the establishment of clearance method that can ensure radiological safety and reasonably minimize radioactive waste when demolishing contaminated buildings at KRR-1&2. By reviewing Korean and international laws related to decommissioning, the method for clearance of contaminated buildings presented in this study is to first decontaminate the building and then conduct a radiological safety assessment, such as measuring residual radioactivity, to determine whether the radiation dose criteria for clearance are satisfied. The measurement results meet the radiation dose criteria, the contaminated buildings are regarded as clearance and can be converted into the general buildings. The demolition of the cleared buildings is carried out using conventional demolition methods. The waste generated during the demolition is classified as general construction waste and is disposed of according to relevant laws. The proposed method significantly optimized the number of samples analyzed and reduced the time and cost associated with the decommissioning. The established method will be applied to the ongoing decommissioning of contaminated buildings at KRR-1&2, and its application will be verified by regulatory bodies. The study suggests that this method could be used for the decommissioning of contaminated buildings at other Korean nuclear facilities in the future.© 2017 Elsevier Inc. All rights reserved
Pressure-Induced Metathesis Reaction To Sequester Cs
We
report here a pressure-driven metathesis reaction where Ag-exchanged
natrolite (Ag<sub>16</sub>Al<sub>16</sub>Si<sub>24</sub>O<sub>80</sub>·16H<sub>2</sub>O, Ag-NAT) is pressurized in an aqueous CsI
solution, resulting in the exchange of Ag<sup>+</sup> by Cs<sup>+</sup> in the natrolite framework forming Cs<sub>16</sub>Al<sub>16</sub>Si<sub>24</sub>O<sub>80</sub>·16H<sub>2</sub>O (Cs-NAT-I) and,
above 0.5 GPa, its high-pressure polymorph (Cs-NAT-II). During the
initial cation exchange, the precipitation of AgI occurs. Additional
pressure and heat at 2 GPa and 160 °C transforms Cs-NAT-II to
a pollucite-related, highly dense, and water-free triclinic phase
with nominal composition CsAlSi<sub>2</sub>O<sub>6</sub>. At ambient
temperature after pressure release, the Cs remains sequestered in
a now monoclinic pollucite phase at close to 40 wt % and a favorably
low Cs leaching rate under back-exchange conditions. This process
thus efficiently combines the pressure-driven separation of Cs and
I at ambient temperature with the subsequent sequestration of Cs under
moderate pressures and temperatures in its preferred waste form suitable
for long-term storage at ambient conditions. The zeolite pollucite
CsAlSi<sub>2</sub>O<sub>6</sub>·H<sub>2</sub>O has been identified
as a potential host material for nuclear waste remediation of anthropogenic <sup>137</sup>Cs due to its chemical and thermal stability, low leaching
rate, and the large amount of Cs it can contain. The new water-free
pollucite phase we characterize during our process will not display
radiolysis of water during longterm storage while maintaining the
Cs content and low leaching rate
Pressure-Dependent Structural and Chemical Changes in a Metal–Organic Framework with One-Dimensional Pore Structure
Pressure-dependent structural and
chemical changes of the metal–organic
framework (MOF) compound MIL-47Â(V) have been investigated up to 3
GPa using different pore-penetrating liquids as pressure transmitting
media (PTM). We find that at 0.3(1) GPa the terephthalic acid (TPA)
template molecules located in the narrow channels of the as-synthesized
MIL-47Â(V) are selectively replaced by methanol molecules from a methanol–ethanol–water
mixture and form a methanol inclusion complex. Further pressure increase
leads to a gradual narrowing of the channels up to 1.9(1) GPa, where
a second irreversible insertion of methanol molecules leads to more
methanol molecules being inserted into the pores. After pressure release
methanol molecules remain within the pores and can be removed only
after heating to 400 °C. In contrast, when MIL-47Â(V) is compressed
in water, a reversible replacement of the TPA by H<sub>2</sub>O molecules
takes place near 1 GPa. The observed structural and chemical changes
observed in MIL-47Â(V) demonstrate unique high pressure chemistry depending
on the size and type of molecules present in the liquid PTM. This
allows postsynthetic nonthermal pressure-induced removal and insertion
of organic molecules in MOFs forming novel and stable phases at ambient
conditions
Enhanced Hydrogen-Storage Capacity and Structural Stability of an Organic Clathrate Structure with Fullerene (C<sub>60</sub>) Guests and Lithium Doping
An
effective combination of host and guest molecules in a framework
type of architecture can enhance the structural stability and physical
properties of clathrate compounds. We report here that an organic
clathrate compound consisting of a fullerene (C<sub>60</sub>) guest
and a hydroquinone (HQ) host framework shows enhanced hydrogen-storage
capacity and good structural stability under pressures and temperatures
up to 10 GPa and 438 K, respectively. This combined structure is formed
in the extended β-type HQ clathrate and admits 16 hydrogen molecules
per cage, leading to a volumetric hydrogen uptake of 49.5 g L<sup>–1</sup> at 77 K and 8 MPa, a value enhanced by 130% compared
to that associated with the β-type HQ clathrate. A close examination
according to density functional theory calculations and grand canonical
Monte Carlo simulations confirms the synergistic combination effect
of the guest–host molecules tailored for enhanced hydrogen
storage. Moreover, the model simulations demonstrate that the lithium-doped
HQ clathrates with C<sub>60</sub> guests reveal exceptionally high
hydrogen-storage capacities. These results provide a new playground
for additional fundamental studies of the structure–property
relationships and migration characteristics of small molecules in
nanostructured materials