• Analytical Science and Technology
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• v.15 no.2
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• pp.127-134
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• 2002

Analytical method to determine rare earth elements which were extracted to organic phase by inductively coupled plasma mass spectrometry(ICP-MS) was investigated. Organic phase which had extracted rare earth elements was directly aspirated into ICP-MS by ultrasonic nebulizer(USN) in order to reduce solvent load to the plasma. Then, the count rate increased when MIBK(methyl isobutyl ketone) was added to EtOH(ethanol) but decreased when 0.03 M HEH(2-ethylhexyl-2-ethylhexyl phosphonic acid, $P_{507}$, PC88A) was added to solvent which mixed MIBK with EtOH. The optimal temperatures of desolvation system were -10 $^{\circ}C$ for the condenser and 150 $^{\circ}C$ for the heating tube. The optimal nebulizer flow rate which gave maximum count rate and minimum reflect power was 0.7 L/min. The optimal pH and extraction time were 4.3 and 10 min for MIBK-0.03 M HEH system. Detection limits which were obtained through calibration curves at the range of 0.2 ${\sim}$ 20 ng/mL were 0.02 ${\sim}$ 0.05 ng/mL under the optimal experimental conditions.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.337-343
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• 2023

Olivine is a complete solid solution of fayalite and forsterite that is abundant in Earth and extraterrestrial materials such as rocky planets, meteorites, asteroids, and interplanetary dust. Due to the wide range of olivine compositions, diverse olivine standards are required for quantitative mineralogical analysis of olivine-bearing materials. Olivine standards were synthesized using an electric furnace and stainless steel tubes at temperatures ranging from 1000~1100 ℃. Overall, olivine was synthesized covering the full range of composition, with some synthetic impurities and unreacted material. The synthesized olivine showed a linear increase in the unit cell dimension in proportion to the molar ratio of fayalite in the starting materials, and the diffraction intensity was consistent with that of natural olivine. However, iron-rich synthetic olivine samples tend to have a higher content of impurity, suggesting that not all synthetic olivine can be used as a standard material yet, and improvements in the synthesis process, such as using high purity starting materials and control of reaction time and temperature, are required.

• Journal of the Korean Geosynthetics Society
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• v.5 no.4
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• pp.11-18
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• 2006

Geotextile has been used for various types of containers, such as small hand-filled sandbags, 3-dimensional fabric forms for concrete paste, large soil and aggregate filled geotextile gabion, prefabricated hydraulically filled containers. They are hydraulically filled with dredged materials and have been applied in coastal protection and scour protection, dewatering method of slurry, temporary working platform for bridge construction, temporary embankment for spill way dam construction. Recently, geotextile tube technology is no longer alternative construction technique but suitable desired solution. The paper presents the stability behavior of geotextile tube composite structure by 2-D limit equilibrium and slope stability analysis. 2-D limit equilibrium analysis was performed to evaluate the stability of geotextile tube composite structure to the lateral earth pressure and also transient seepage and stability analysis were conducted to determine the pore pressure distribution by tide variation and slope stability. Based on the results of this paper, the three types of geotextile tube composite structure is stable and also slope stability of overall geotextile tube composite structures is stable with the variation of tidal conditions.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1256-1261
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• 2009

Seawater amounts to 70% of the earth and represents a quite unlimited resource for the production of fresh water by desalination processes and for the extraction of dissolved salts present in it. Recently, the falling film evaporation has increased in interest as an efficient method for seawater desalination system. In the desalination system, the flow characteristics of the falling film is very important issue to make highly efficient system. So, this study is taken to investigate numerically the falling film thickness on the inlet Renold Number ranges are 400 to 700. Numerical simulations are performed using FLUENT6.3.26, a commercial CFD code.

• The Journal of Engineering Geology
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• v.30 no.3
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• pp.327-345
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• 2020

The effects of ground vibration on lava tubes during construction were studied to aid design of management and preservation measures for lava tubes. Ground conditions were assessed by RMR (Rock mass rating) and Q-system classifications for the Geomunoreum lava tubes, and vibration velocity was measured during in situ blasting tests in the Manjanggul and Yongcheondonggul lava tubes. Results indicate that the higher the rock quality, the greater the effect of vibration, although there is no clear linear relationship due to ground heterogeneity. A relationship derived between vibration velocity (PPV) and intensity (dB(V)) on the basis of blasting tests indicates that a vibration level of < 0.285 cm/sec meets the regulatory limit of 0.371 cm/sec and 65 dB(V) during daytime, and 0.285 cm/sec and 60 dB(V) during night. For blasting vibrations, square- and cube-root scaled distances are linearly correlated, with R² ≥ 0.76. On the basis of this correlation, explosive-charge weights meeting the 0.2 cm/sec vibration criterion for cultural heritage were estimated to be 2.88 kg at 50 m distance, and 11.52 kg at 100 m.

• Journal of the Mineralogical Society of Korea
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• v.16 no.2
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• pp.171-180
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• 2003

The objective of this study is to investigate biogeochemical processes to sequester $CO_2$and metals utilizing metal-rich fly ash (MRFA). Microbial conversion of $CO_2$into sparingly soluble carbonate minerals has been studied using MRFA under different $pCO_2$and different bicarbonate concentrations. Scaling from test tube to fermentation vessels (up to 4-L) using metal-reducing bacteria and MRFA has proved successful at sequestering carbon dioxide and metals. $CO_2$sequestration via precipitation processes using MRFA may complement the process of $CO_2$capture from fossil fuel plants while potentially stabilizing fly ash wastes.

• International Journal of High-Rise Buildings
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• v.3 no.1
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• pp.35-48
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• 2014

In designing a 300 meter high skyscraper expected to be the tallest building in Japan, an earthquake-ridden country, we launched on the full-scale performance based design to ensure redundancy and establish new specifications using below new techniques. The following new techniques are applied because the existing techniques/materials are not enough to meet the established design criteria for the large-scale, irregularly-shaped building, and earth-conscious material saving and construction streamlining for reconstructing a station building are also required: ${\bullet}$ High strength materials: Concrete filled steel tube ("CFT") columns made of high-strength concrete and steels; ${\bullet}$ New joint system: Combination of outer diaphragm and aluminium spray jointing; ${\bullet}$ Various dampers including corrugated steel-plate walls, rotational friction dampers, oil dampers, and inverted-pendulum adaptive tuned mass damper (ATMD): Installed as appropriate; and ${\bullet}$ Foundation system: Piled raft foundation, soil cement earth-retaining wall construction, and beer bottle shaped high-strength CFT piles.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.2
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• pp.110.1-110.1
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• 2014

The optics of Space telescope is one of the major parts of space mission used for imaging observation of astronomical targets and the Earth. These kinds of space mission have a bulky and complex opto-mechanics with a long optical tube, but there are attempts have been made to observe a target with a small satellite in many ways. In this paper, we describe an optical design of a reflecting telescope for use in a CubeSat mission. For this design, we adopt the off-axis segmented method of astronomical observation techniques based on the Ritchey-Chr$\acute{e}$tien type telescope. The primary mirror shape is a rectangle with dimensions of $8cm{\times}8cm$, and a secondary mirror has dimensions of $2.4cm{\times}4.1cm$. The focal ratio is 3 which can obtain a $0.3{\times}0.2$ degree diagonal angle in a $1280{\times}800$ CMOS color image sensor with a pixel size of $3{\mu}m{\times}3{\mu}m$. This optical design can capture a ${\sim}4km{\times}{\sim}2.3km$ area of the earth's surface at 700 km altitude operation. Based on this conceptual design, we will keep trying to study more for astronomical observation with Attitude control system.

• Journal of the Optical Society of Korea
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• v.17 no.6
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• pp.533-537
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• 2013

Space telescope optics is one of the major parts of any space mission used to observe astronomical targets or the Earth. This kind of space mission typically involves bulky and complex opto-mechanics with a long optical tube, but attempts have been made to observe a target with a small satellite. In this paper, we describe the optical design of a reflecting telescope for use in a CubeSat mission. For this design we adopt the off-axis segmented method for astronomical observation techniques based on a Ritchey-Chr$\acute{e}$tien type telescope. The primary mirror shape is a rectangle with dimensions of $8cm{\times}8cm$, and the secondary mirror has dimensions of $2.4cm{\times}4.1cm$. The focal ratio is 3 which can yield a 0.383 degree diagonal angle in a $1280{\times}800$ CMOS color image sensor with a pixel size of $3{\mu}m{\times}3{\mu}m$. This optical design can capture a ${\sim}4km{\times}{\sim}2.3km$ area of the earth's surface at 700 km altitude operation.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.2
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• pp.138.2-138.2
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• 2012

Cave on the Moon is considered as the most appropriate place for human to live during the frontier lunar exploration. While the lava flows, the outer crust gets cooled and solidified. Then, the empty space is remained inside after lava flow stops. Such empty space is called the lava caves. Those lava tubes on the Earth are formed mostly by volcanic activity. However, the lava tubes on satellite like Moon and planet like Mars without volcanic activity are mostly formed by the lava flow inside of the crater made by large meteorite impact. Some part of lava tube with collapsed ceiling appears as the entrance of the cave. Such area looks like a deep crater so called a pit crater. Four large pit craters with diameter of > 60 m and depth of > 40 m are found without difficulty from Kaguya and LRO mission image archives. However, those are too deep to use as easily accessible human frontier base. Therefore, now we are going to identify some smaller lunar caves with accessible entrances using LRO camera images of 0.5 m/pixel resolution. Earth's lava caves and their entrances are well photographed by surface and aerial camera in immense volume. Thus, if the image data are sorted and archived well, those images can be used in comparison with the less distinct lunar cave and entrance images due to its smaller size. Then, we can identify the regions on the Moon where there exist caves with accessible entrances. The database will be also useful in modeling geomorphology for lunar and Martian caves for future artificial intelligence investigation of the caves in any size.