• Economic and Environmental Geology
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• v.26 no.3
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• pp.267-278
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• 1993

Serpentinite rocks which are composed mainly of olivine, serpentine and clinopyroxene, cropped out in the anorogenic Kyongsang sedimentary basin of South Korea. The serpentinites contain high content of MgO (36.87~41.99%) and 47~67 ppm Co, 1185~2042 ppm Ni and 979~3582 ppm Cr, which are quite similar to those of ultrabasic rocks such as peridotite and dunite. Isotopic compositions of serpentinites range from -95.5 to -105.7‰ in ${\delta}D$ and +1.7 to 7.1‰ in ${\delta}^{18}O$ corresponding to the continental antigorite type. A wide variation of oxygen isotopic values and $H_2O^+$ content of serpentinites reflect the different water/rock ratios during serpentinization processes. Formation temperature of serpentine minerals are estimated to be unusually high temperature of $488{\sim}646^{\circ}C$ by serpentine-magnetite isotopic fractionation, which belong to continental antigorite type. Calculated ${\delta}^{18}O$ value of serpentinized fluid during serpentinization is suggested that the hydrothermal fluid responsible for serpentinization be originated from the magmatic fluid with a minor influx of paleo-meteoric water in this area.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.2
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• pp.225-233
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• 2014

This paper presents a Computational Fluid Dynamics(CFD) based simulation and experimental tracer test of flow pattern and turbulent energy dissipation inside a serpentine flocculation basin with continuous operation. Research focused on the evaluation of a specific flow pattern on the hydraulic behavior on the flocculation basin. From the results of CFD simulation and actual tracer test, both results were in good accordance with each other. Also, each Morill index were calculated as 1.5 from CFD simulation and 1.7 from actual tracer test, respectively. Especially, turbulence energy was dissipated relatively higher in the vicinity of inlet to the flocculation basin than other region. The differences between the CFD simulation and actual tracer test were 1.4 min in $T_{50}$, and 1.3 min in $T_p$, respectively.

• Journal of Korean Neurosurgical Society
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• v.52 no.5
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• pp.501-504
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• 2012

Objective : To report our surgical experience using in situ end-to-side bypass for giant serpentine distal anterior cerebral artery aneurysm, unsuitable for microsurgical clipping. Methods : A 49-year-old woman presented with headache and intermittent loss of consciousness. The brain computed tomography scan revealed a partially calcified mass in the interhemispheric fissure. On cerebral angiography, that was giant ($30{\times}18mm$ sized), serpentine aneurysm originating from the A2 to A3 segment of the distal anterior cerebral artery (DACA). The aneurysm was trapped with clips, and the right A3 segment to left A3 segment of DACA, end-to-side in situ bypass was performed. Surgical result was favorable, with no newly developed ischemic event in the acute recovery period. Postoperative angiography showed total occlusion of the aneurysm and good patency, with preserved distal flow. Conclusion : Giant fusiform aneurysms of the DACA are extremely rare and can be particularly challenging to treat. End-to-side A3 : A3 bypass with aneurysm trapping could be a treatment modality for these locations.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.28 no.1
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• pp.144-149
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• 1983

Experiments were conducted to develop a pelletization method of minute tobacco seeds for easy handling at seeding by hand or for mechanical seeding. Serpentine, zeolite, and talc were tested as coating materials and the resulting pills were compared in size uniformity, hardness, length of time needed for coating, percentage of pills containing a single seed, and speed of disintegration when submerged in water. Talc was the poorest and zeolite was good only in hardness. On the other hand serpentine was good in most characters above, except for brittleness. This defect, however, was overcome by double coating, first with serpentine and followed by zeolite. This new pelletizing method results in optimum hardness, uniform size, and high ratio of pellets containing one tobacco seed. When compared to bare tobacco seeds, the double-coated seeds did not differ in germination test.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.8
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• pp.604-612
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• 2009

Water management has been recognized as a crucial factor for achieving better performance and stability in polymer electrolyte membrane fuel cells (PEMFCs). Proper water management should provide favorable water conditions, including the local humidity, membrane water content, and liquid water saturation in PEMFCs, thereby leading to more uniform electrochemical reaction and current generation. In this study, computational fluid dynamics (CFD) simulation was conducted to investigate the effects of the cathode relative humidity (RH) on the performance of a 3 by $3\;cm^2$ PEMFC with serpentine flow fields. The CFD results showed that the best performance of the PEMFC was obtained for the cathode RH of 80%, but the performance variation was small for the cathode RH range of $60{\sim}100%$. However, the loss of the PEMFC performance was significant when the cathode RH was reduced below 40%. The reason for such performance variation was investigated through the detailed inspection of ohmic loss, activation and concentration overpotential, and water and current distributions.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2828-2833
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• 2008

Water management is one of many operating parameters, which influences the performance and stability of a proton exchange membrane fuel cell (PEMFC). Local humidity condition including liquid water saturation has profound impacts on the distributions of overpotentials, current density, and membrane water content. Computational fluid dynamics simulations were conducted to investigate the effect of the inlet humidity variation on the performance of a PEMFC of $9\;cm^2$ active cell area with serpentine flow fields. The results showed that the performance of the simulated PEMFC remained at an almost same level when the cathode inlet humidity was changed from 100% to 60%, while reaching its maximum at air humidity of 80%. However, further decrease in the cathode inlet humidity below 40% started to significantly deteriorate the performance of the PEMFC. The variations of overpotentials, membrane water content, etc. due to the change in the cathode inlet humidity were also discussed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.1
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• pp.86-93
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• 2007

The PEM (polymer electrolyte membrane) fuel cell is one of the promising fuel cell systems as a new small power generating device for automobiles and buildings. The optimal design of cooling plates installed between MEA (membrane electrode assembly) is very important to achieve high performance and reliability of the PEMFC because it is very sensitive to temperature variations. In this study, six types of cooling plate models for the PEMFC including basic serpentine and parallel shapes were designed and their cooling performances were analyzed by using three-dimensional fluid dynamics with commercial software. The model 3 designed by revising the basic serpentine model represented the best cooling performance among them in the aspect of uniformity of temperature distribution and thermal reliability, The serpentine models showed higher pressure drop than the parallel models due to a higher flow rate.

• The Journal of the Petrological Society of Korea
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• v.3 no.2
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• pp.156-170
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• 1994

The talc ore deposits can be divided into chloritic and dolomitic ores according to mineral assemblages. The former is mainly composed of chlorite and talc accompanied with dolomite, muscovite and opaque mineral, and the latter of dolomite and talc with serpentine, calcite and magnesite in places. Talc was originated from chlorite and serpentine. Carbonate minerals were formed either directly from the introduced hydrothermal solution or secondarily as a by-product of steatitization of chlorite and serpentine. The process of talc formation may be governed by the chemical composition of the host rocks and the amount and/or chemical composition of the hydrothermal solution which may be different in places. However, the representative reactions producing talc from chlorite and serpentine are as follows : (1) chlorite+$Mg^{++}+Si^{4+}+H_2O$=talc, (2) chlorite+$Mg^{++}+Si^{4+}+Ca^{++}+CO_2+O_2+H_2O$=talc+ dolomite+ magnesite, and (3) serpentine +$Mg^{++}+Fe^{++}+Si^{4+}+Ca^{++}+CO_2+H_2O$=talc+dolomite. The reactions indicate that the carbonate minerals can be formed when the hydrothermal solution have high $fO_2$ and $fCO_2$. The steatitization might be proceeded by the hydrothermally metasomatic reaction between chlorite schist or chlorite gneiss intercalated in the granitic gneiss and hydrothermal solution accompanied to the wet granitization.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.233-257
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• 2023

Asbestos minerals are found at rocks and soils of the Hongseong and Bibong serpentine mines, western part of Chungnam. The area consists of and metasediment, and Mesozoic igneous intrusives with minor age-known gneiss complexes and Mesozoic sediments. With detailed geological investigations, rock samples for the serpentinite and amphibolite areas are collected at sites containing asbestos. Representative asbestos and rock samples are analysed by PLM, XRD, SEM and EPMA. Serpentinites are found as steeply dipping faults with adjacent gneiss complex to the NNE direction. Repeated alteration, including serpenitization and talcification, is found at the emplacement direction for the serpentinite body. Amphibollites occur as intrusives and stratiforms within the Precambrian gneiss complex. Serpentinite and amphibolite (or amphibole schist) contain amphiboles either as asbestiform or non-asbestiform. Varying amounts of asbestos minerals, including chrysotile, tremolite asbestos and actinolite asbestos, are found within the serpentinites. The asbestos minerals are found near the cracks or fractures and along the bedding plane. They occur as cross fiber, slip fiber and mass fiber types. Varying amounts of amphibole asbestos minerals, such as tremolite and actinolite asbestos, are found within amphibolites and as a mass fiber type. Overall results suggest that rocks of the serpentine mines contain serpentine and amphibole type asbestos minerals originated from the hydrothermal alteration. Considering construction nearby the mines and environmental risks by the asbestos, additional land management plans are required.

• Economic and Environmental Geology
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• v.49 no.1
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• pp.13-22
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• 2016

The objectives of this study were to recover silica and iron oxides and $CO_2$ sequestration using serpentine via various acid dissolution and pH swing processes. Serpentine collected from Guhang-myeon in S. Korea were mainly composed of antigorite and magnetite consisting of $SiO_2$ (45.3 wt.%), MgO (41.3 wt.%), $Fe_2O_3$ (12.2 wt.%). Serpentine pulverized ($${\leq_-}75{\mu}m$$) and then dissolved in 3 different acids, HCl, $H_2SO_4$, $HNO_3$. Residues treated with acidic solution were recovered from the solution (step 1). And then the residual solution containing dissolved serpentine was titrated using $NH_4OH$. And pH of the solution increased up to pH=8.6 to obtain reddish precipitates (step 2). After recovery of the precipitates, the residual solution reacted with $CO_2$ and then pH increased up to pH=9.5 to precipitate white materials (step 3). The mineralogical characteristics of the original sample and harvested precipitates were examined by XRD, and TEM-EDS analyses. ICP-AES analysis was also used to investigate solution chemistry. The dissolved ions were Mg, Si, and Fe. The antigorite became noncrystralline silica after acid treatment (step 1). The precipitate at pH=8.6 was mainly amorphous iron oxide, of which size ranged from 2 to 10 nm and mainly consisting of Fe, O, and Si (step 2). At pH=9.5, nesquehonite [$Mg(HCO_3)(OH){\cdot}2(H_2O)$] and lasfordite [$MgCO_3{\cdot}H_2O$] were formed after reaction with $CO_2$ (step 3). The size of carbonated minerals was ranged from 1 to $6{\mu}m$. These results indicated that the acid treatment of serpentine and pH swing processes for the serpentine can be used for synthesis of other materials such as silica, iron oxides and magnesium carbonate. Also, This process may be useful for the precursor synthesis and $CO_2$ sequestration via mineral carbonation.