• Economic and Environmental Geology
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• v.55 no.5
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• pp.521-529
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• 2022

Gravity exploration was conducted to determine the distribution of igneous complex related to lithium pegmatite in the Boam deposit of Uljin, Gyeongsangbuk-do, and the spatial relationship with the regional geology and ore bodies were studied. The gravity exploration result shows that the Boam deposit area is characterized by relatively low gravity anomaly that surrounds the deposit. The Boam deposit is located near the southwest-northeast directional boundary of gravity anomalies where igneous complex (granite gneiss) contacts with the Yuli and Wonnam groups in the southeast, Janggun limestone layers in the east-west direction, and Dongsugok metasedimentary rocks. While the western boundary in the southwest-northeast direction is relatively clear, there may also be unknown igneous complex that are not exposed on the surface at the eastern and southern boundaries because a relatively low gravity anomaly surrounds the deposit. The distribution characteristics of these hidden igneous complex will be used as useful data for predicting the distribution of the lithium pegmatite in the future.

• Advances in nano research
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• v.7 no.2
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• pp.89-98
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• 2019

In this work, the thermal buckling characteristics of zigzag single-walled boron nitride (SWBNNT) embedded in a one-parameter elastic medium modeled as Winkler-type foundation are investigated using a nonlocal first-order shear deformation theory (NFSDT). This model can take into account the small scale effect as well as the transverse shear deformation effects of nanotubes. A closed-form solution for nondimensional critical buckling temperature is obtained in this investigation. Further the effect of nonlocal parameter, Winkler elastic foundation modulus, the ratio of the length to the diameter, the transverse shear deformation and rotary inertia on the critical buckling temperature are being investigated and discussed. The results presented in this paper can provide useful guidance for the study and design of the next generation of nanodevices that make use of the thermal buckling properties of boron nitride nanotubes.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.2
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• pp.168-178
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• 1983

Influence of several dehydration treatments on original structure and water behavior in the process of drying were investigated employing three hawaiian volcanic ash soils and four synthetic minerals. These three soils were developed under different rainfall condition and contained three different amount of amorphous materials in them. Measurement of water losses by oven drying at $105^{\circ}C$, $P_2O_5$ drying, freeze drying, and critical point drying revealed that more water losses were noted by oven drying than by three other drying techniques and the differences of water losses between oven and $P_2O_5$-drying were closely related to amoun: of amorphous materials in them, showing the order of Kaiwiki > Hilo > Kawaihae. This indicates that dehydration of amorphous materials by elevated temperature ($105^{\circ}C$) excluded water beyond that in the adsorbed (hygroscopic) state. The effect of dehydration treatments on initial structure was visualized by scanning electron microscopy. The micrographs showed that oven-and $P_2O_5$-dried samples formed into large mass of sub-angular blocky, dense, and closed crumbs, while the freeze dried and critical point dried samples resulted in less shrinkage, and small, fluffy and open spongy structure. However, critical point drying technique produced bulkier, softer, and greater open structure samples than even freeze drying. Additional Index Words: original structure, synthetic minerals, critical point drying, $P_2O_5$ drying. 1. This is a part of author's Ph.D. dissertation submitted to the University of Hawaii, Honolulu, Hawaii 96822 in 1979. 2. Professor of Agricultural Chemistry, Korea University.

• Geomechanics and Engineering
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• v.18 no.3
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• pp.267-275
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• 2019

Tabriz is a large Iranian city and the capital of the East Azerbaijan province. The bed rock of this city is mainly consisted of marl layers. Marl layers have some outcrops in the northern and eastern parts of city that mainly belong to the Baghmisheh formation. Based on their colors, these marls are classified into three types: yellow, green, and gray marls. The city is developing toward its eastern side wherein various civil projects are under construction including tunnels, underground excavation, and high-rise building. In this regard, the swelling behavior assessment of these marls is of critical importance. Also, in lightweight structures with foundation pressure less than swelling pressure, several problems such as walls cracking and jamming of door and windows may occur. In the present study, physical properties and swelling behavior of Baghmisheh marls are investigated. According to the X-ray diffractometer (XRD) results, the marls are mainly composed of Illite, Kaolinite, Montmorillonite, and Chloride minerals. Type and content of clay minerals and initial void ratio have a decisive role in swelling behavior of these marls. The swelling potential of these marls was investigated using one-dimensional odometer apparatus under stress level up to 10 kPa. The results showed that yellow marls have high swelling potential and expansibility compared to the other marls. In addition, green and gray marls showed intermediate and low swelling potential and swelling pressure, respectively.

• Advances in nano research
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• v.8 no.2
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• pp.135-148
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• 2020

The incorporation of carbon nanotubes in a polymer matrix makes it possible to obtain nanocomposite materials with exceptional properties. It's in this scientific background that this work was based. There are several theories that deal with the behavior of plates, in this research based on the Mindlin-Reissner theory that takes into account the transversal shear effect, for analysis of the critical buckling load of a reinforced polymer plate with parabolic distribution of carbon nanotubes. The equations of the model are derived and the critical loads of linear and parabolic distribution of carbon nanotubes are obtained. With different disposition of nanotubes of carbon in the polymer matrix, the effects of different parameters such as the volume fractions, the plate geometric ratios and the number of modes on the critical load buckling are analysed and discussed. The results show that the critical buckling load of parabolic distribution is larger than the linear distribution. This variation is attributed to the concentration of reinforcement (CNTs) at the top and bottom faces for the X-CNT type which make the plate more rigid against buckling.

• Geophysics and Geophysical Exploration
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• v.24 no.4
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• pp.202-208
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• 2021

Induced polarization (IP) was first published in a Korean academic journal in 1973, and it was soon applied to coal and metal ore exploration. Then, in universities and research institutes, IP modeling studies using the finite element approach and experimental studies on IP responses for artificial samples were conducted. In the mid-1980s, the spectral IP (SIP) measurement module was introduced to Korea, and physical scale modeling and inversion approaches were developed. Due to the decline of the mineral resource industry, this method was not actively applied. However, the SIP method was not applied In the 1990s, IP exploration was applied in the investigation of hydrothermal deposits of sulfide minerals and bentonite mineralization zones, as well as to areas where the groundwater was contaminated by intruding seawater. In the 2000s, three-dimensional inversion of the IP approach was developed, and high-precision geophysical exploration was required to secure domestic and overseas mineral resources, so SIP experiments on rock samples and approaches for field exploration were developed. The SIP approach was proven useful for the exploration of metal deposits containing sulfide minerals by applying it to explore the mineralization zone of gold-silver deposits in the Haenam region. The IP method is considered to be effective in exploring critical minerals (lithium, cobalt, and nickel) in high-tech industries. It also is expected to be useful for environmental and geotechnical investigations.

• Journal of Environmental Health Sciences
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• v.35 no.5
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• pp.426-432
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• 2009

Asbestos is a commercial term of natural occurring silicated minerals and forms long, thin fibers. Chrysotile, the serpentine asbestos, accounts for most use in commercial use. Asbestos is well known health hazard material and it is proved that inhalation of asbestos fibers leads to increased risk of developing several diseases such as lung cancer, mesothelioma, asbestosis. In these days, people most at risk for exposure are maintenance and construction workers and general citizens who are working on and close to the work area at which asbestos containing material is disturbing. Non asbestiform, though its chemical composition is same with regulated asbestos, is known to be less hazardous than asbestiform. Exposure guideline, 0.01 f/ml, is not safe level in terms of health risk. It is reasonable to take preventable action when asbestos is suspicious. In Korea, it is necessary to clarify the concept between hazard and risk, to differentiate asbestiform from non asbestiform, to make regulations for compensation for asbestos related patients, to manage future exposure for general citizens.

• Journal of the Korean Ceramic Society
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• v.19 no.1
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• pp.35-43
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• 1982

It was found that the burnability of raw mix and characteristics of clinker was affected by the difference in grades of limestones. The thermal decomposition temperature of raw mix which used low grade limestone was lower than that of high grade, and the fast formation of $C_2S$ was due to the rich content of calcite and quartz over critical grain size, which caused the bad effects in the burnability, but $C_3S$ was formed slowly. The structure of clinker had many pores, and the growth of clinker minerals was inferior.

• 한국해양학회지
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• v.18 no.1
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• pp.21-28
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• 1983

A series of experiments was performed to increase and make our puantitive understanding of the entrainuent and settling processes of fine-grained sediments, which are of critical importance to construct a predictive model of sediment experiments were performed in an annular flume. A rotating top produced a turbulent flow which in turn exerted and are shown to be dependent on the sediment concentration and the presence of clay minerals. The parameters on which entrainment strongly depends were identified to be the shear stress, water content (time ofter deposition), and the type of sediment (grain size and mineralogy).

• Advances in Energy Research
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• v.4 no.3
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• pp.203-211
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• 2016

A good understanding of the chemical composition and structural characteristics of a carbonaceous material is essential in conversion processes. Understanding how the composition and structural changes influence the burning behaviour of coal is important when assessing a coal's potential for utilization. To explore the potentials of a typical Nigerian coal, both conventional and advanced analytical techniques such as proximate analysis, ultimate analysis, calorific value, surface area analyser, SEM, FTIR, XRD and SAXS were employed. The results obtained from these characterizations agree favourable well with a typical South African coal that is of enormous contribution to the gross domestic product (GDP) of the nation economy.