• Economic and Environmental Geology
• /
• v.26 no.4
• /
• pp.433-444
• /
• 1993

Electrum (32~73 atom. % Ag)-sulfide mineralization of the Bodeok mine in the Boseong area was deposited in two stages of mineralogically simple, massive quartz veins that fill the fractures along fault shear zones in Precambrian gneiss. Radiometric dating indicates that mineralization is Late Jurassic age ($155.9{\pm}2.3$ Ma). Fluid inclusion data show that ore mineralization was formed from $H_2O-CO_2$ fluids with variable $CO_2$ contents ($X_{CO_2}=0.0$ to 0.7) and low salinities (0.0 to 7.4 wt. % eq. NaCl) at temperatures between $200^{\circ}$ and $370^{\circ}C$. Evidence of fluid unmixing ($CO_2$ effervescence) indicates pressures up to 1 kbar. Gold-silver deposition occurred later than base-metal sulfide deposition, at temperatures near $250^{\circ}C$ and was probably a result of cooling and decreasing sulfur activity caused by sulfide precipitation and/or $H_2S$ loss (through fluid unmixing). Calculated sulfur isotope compositions of ore fluids (${\delta}^{34}S_{{\Sigma}S}=1.7$ to 3.3‰) indicate an igneous source of sulfur in hydrothermal fluids. Measured and calculated O and H isotope compositions of ore fluids (${\delta}^{18}O_{water}=4.8$ to 7.2‰, ${\delta}D_{water}=-73$ to -76‰) indicate that mesothermal auriferous fluids at Bodeok were likely mixtures of $H_2O-rich$, isotopically evolved meteoric waters and magmatic $H_2O-CO_2$ fluids.

• Journal of Korean Society of Environmental Engineers
• /
• v.39 no.1
• /
• pp.9-18
• /
• 2017

Arsenic (As) has been considered as the most toxic one among various hazardous materials and As contamination can be caused naturally and anthropogenically. Major forms of arsenic in groundwater are arsenite [(As(III)] and/or arsenate [(As(V)], depending on redox condition: arsenite and arsenate are predominant in reduced and oxidized environments, respectively. Because arsenite is much more toxic and mobile than arsenate, there have been a number of studies on the reduction of its toxicity through oxidation of As(III) to As(V). This study was initiated to develop photocatalytic oxidation process for treatment of groundwater contaminated with arsenite. The performance of two types of light sources (UV lamp and UV LED) was compared and the feasibility of goethite as a photocatalyst was evaluated. The highest removal efficiency of the process was achieved at a goethite dose of 0.05 g/L. Based on the comparison of oxidation efficiencies of arsenite between two light sources, the apparent performance of UV LED was inferior to that of UV lamp. However, when the results were appraised on the basis of their emitting UV irradiation, the higher performance was achieved by UV LED than by UV lamp. This study demonstrates that environmentally friendly process of goethite-catalytic photo-oxidation without any addition of foreign catalyst is feasible for the reduction of arsenite in groundwater containing naturally-occurring goethite. In addition, this study confirms that UV LED can be used in the photo-oxidation of arsenite as an alternative light source of UV lamp to remedy the drawbacks of UV lamp, such as long stabilization time, high electrical power consumption, short lifespan, and high heat output requiring large cooling facilities.

• Journal of Animal Environmental Science
• /
• v.16 no.3
• /
• pp.205-215
• /
• 2010

Geothermal heat pump system (GHPS) is an energy-efficient technology that use the relatively constant and renewable energy stored in the earth to provide heating and cooling. With the aim of using GHPS as a heating source, it's possibilities of application in farrowing house were examined by measuring environmental assessment and sow's performance. A total of 96 sows were assigned to 2 pig housings (GHPS and conventional housing) with 48 for four weeks in winter season. During the experimental period, indoor maximum temperature in GHPS-housing was measured up to $26.7^{\circ}C$, average temperature could maintain $21.2^{\circ}C$. The mean value of dust levels and $CO_2$, $NH_3$ and $H_2S$ gas emissions were decreased in GHPS-housing compare with those of conventional housing. Litter size, birth weight, parity and weaning weight did not differ between housings. However, feed intake of sow in GHPS-housing was lower than that of conventional housing. In energy consumption for heating, electric power consumption increased in GHPS-housing than the conventional housing, a 2,250 kwh increase, whereas there is no fuel usage for heater in GHPS-housing. Amount of ground water circulated for heating in cold weather for earth heat exchanger was 8.4-12.9 ton per day. In conclusion, GHPS may have environmental benefits and effectiveness of heating in farrowing housing and affect the performance in sows.

• Journal of the Korean Institute of Gas
• /
• v.27 no.3
• /
• pp.52-58
• /
• 2023

With the increasing awareness of the importance of carbon neutrality in response to global climate change, the utilization of hydrogen as a carbon-free fuel source is also growing. Hydrogen is commonly used in fuel cells (FC), but it can also be utilized in internal combustion engines (ICE) that are based on combustion. Particularly, ICEs that already have established infrastructure for production and supply can greatly contribute to the expansion of hydrogen energy utilization when it becomes difficult to rely solely on fuel cells or expand their infrastructure. However, a disadvantage of utilizing hydrogen through combustion is the potential generation of nitrogen oxides (NOx), which are harmful emissions formed when nitrogen in the air reacts with oxygen at high temperatures. In particular, for the EURO-7 exhaust regulation, which includes cold start operation, efforts to reduce exhaust emissions during the warm-up process are required. Therefore, in this study, the characteristics of nitrogen oxides and fuel consumption were investigated during the warm-up process of cooling water from room temperature to 88℃ using a 2-liter direct injection spark ignition (SI) engine fueled with hydrogen. One advantage of hydrogen, compared to conventional fuels like gasoline, natural gas, and liquefied petroleum gas (LPG), is its wide flammable range, which allows for sparser control of the excessive air ratio. In this study, the excessive air ratio was varied as 1.6/1.8/2.0 during the warm-up process, and the results were analyzed. The experimental results show that as the excessive air ratio becomes sparser during warm-up, the emission of nitrogen oxides per unit time decreases, and the thermal efficiency relatively increases. However, as the time required to reach the final temperature becomes longer, the cumulative emissions and fuel consumption may worsen.

• Journal of the Korean earth science society
• /
• v.45 no.2
• /
• pp.121-135
• /
• 2024

This study examined the influence of near-surface atmospheric warming in the Arctic-East Asia region during spring (March-May) from 1991 to 2020 on the synoptic-scale meteorology of dust storm-induced dust days in Seoul, Korea, in response to the Arctic Oscillation. Increased springtime warming in the Arctic-East Asia region correlated with a reduction of six days in the occurrence of dust storm-induced dust days in Seoul, Korea, along with a decline in the intensity of these days by -1.6 ㎍ m^-3yr^-1 in PM₁₀ mass concentration. The declining number of dust storm-induced dust days in Korea during the 2010s was the result of synoptic-scale meteorological analysis, which showed increased high-pressure activity as indicated by the negative potential vorticity unit. Moreover, a distinct pattern emerged in the distribution of dust storm-induced dust days in Korea based on the Arctic Oscillation Index (AOI), showing an increase in negative AOI and a decrease in positive AOI. Although the northward shift of the polar jet weakened the southerly low-pressure system activity over Mongolia and northern China, a reinforced high-pressure system formed over the Chinese continent during dust-storm-induced dust days with a negative AOI. This resulted in both a decrease in the frequency of dust-storm-induced dust days and reduction in wind speeds, facilitating their transport from source regions to Korea. Conversely, on days with positive AOIs, an extensive warm and stagnant high-pressure system dominated mainland China, accompanied by further cooling of the northern segment of the polar jet. A notable decline in wind speed in the lower troposphere across the Mongolia-northern China-Korea region diminished the occurrence of dust storm-induced dust days and also weakened their long-range transport.

• Journal of Haehwa Medicine
• /
• v.8 no.2
• /
• pp.211-243
• /
• 2000

This study was performed to investigate the cause, symptom, treatment, medicine of Wei symptom through the literature of oriental and western medicine. The results obtained were as follows: 1. Wei symptom is the symptom that reveals muscle relaxation without contraction and muscle relaxation occures in the lower limb or upper limb, in severe case, leads to death. 2. Since the pathology and etiology of Wei symptom was first described as "pe-yeol-yeop-cho"(肺熱葉焦) in Hung Ti Nei Ching(黃帝內經), for generations most doctors had have accepted it. but after Dan Ge(丹溪), it had been classified into seven causes, damp-heat(濕熱), phlegm-damp(濕痰), deficiency of qi(氣虛), deficiency of blood(血虛), deficiency of yin(陰處), stagnant blood(死血), stagnant food(食積). Chang Gyeng Ag(張景岳) added the cause of deficiency of source qi(元氣). 3. The concept of "To treat Yangming, most of all"(獨治陽明) was emphasized in the treatment of Wei symptom and contains nourishment of middle warmer energy(補益中氣), clearance of yangming-damp-heat(淸化陽明濕熱). 4. Since Nei-ching era(內經時代), Wei and Bi symptom(痺症) is differenciated according to the existence of pain. After Ming era(明代) appeared theory of co-existence of Wei symptom and pain or numbness but they were accepted as a sign of Wei symptom caused by the pathological factor phelgm(痰), damp(濕), stagnancy(瘀). 5. In the western medical point of view, Wei symptom is like paraplegia, or tetraplegia. and according to the causative disease, it is accompanied by dysesthesia, paresthsia, pain. thus it is more recommended to use hwal-hyel-hwa-ae(活血化瘀) method considering damp-heat(濕熱), qi deficiency of spleen and stornach(脾胃氣虛) as pathological basis than to simply differenciate Wei and Bi symptom according to the existence of pain. 6. The cause of Gullian-Barre syndrome(GBS) is consist of two factors, internal and external. Internal factors include asthenia of spleen and stomach, and of liver and kidney. External factors include summur-damp(暑濕), damp-heat(濕熱), cold-damp(寒濕) and on the basis of "classification and treatment according to the symptom of Zang-Fu"(臟腑辨證論治), the cause of GBS is classified into injury of body fluid by lung heat(肺熱傷津), infiltration of damp-heat(濕熱浸淫), asthenia of spleen and kidney(脾腎兩虛), asthenia of spleen and stomach(脾胃虛弱), asthenia of liver and kidney (肝腎兩虛). 7. The cause of GBS is divided by according to the disease developing stage: Early stage include dryness-heat(燥熱), damp(濕邪), phlegm(痰濁), stagnant blood(瘀血), and major treatment is reducing of excess(瀉實). Late stage include deficiency of essence(精虛), deficiency with excess(虛中挾實), and essencial deficiency of liver and kidney(肝腎精不足) is major point of treatment. 8. Following is the herbal medicine of GBS according to the stage. In case of summur-damp(暑濕), chung-seu-iki-tang(淸暑益氣湯) is used which helps cooling and drainage of summer-damp(淸利暑濕), reinforcement of qi and passage of collateral channels(補氣通絡). In case of damp-heat, used kun-bo-hwan(健步丸), In case of cool-damp(寒濕), used 'Mahwang-buja-sesin-tang with sam-chul-tang'(麻黃附子細辛湯合蓼朮湯). In case of asthenia of spleen and kidney, used 'Sam-lyeng-baik-chul san'(蔘笭白朮散), In case of asthenia of liver and kidney, used 'Hojam-hwan'(虎潛丸). 9. Following is the herbal medicine of GBS according to the "classification and treatment according to the symptom of Zang-Fu"(臟腑辨證論治). In the case of injury of body fluid by lung heat(肺熱傷津), 'Chung-jo-gu-pae-tang'(淸燥救肺湯) is used. In case of 'infiltration of damp-heat'(濕熱浸淫), us-ed 'Yi-myo-hwan'(二妙丸), In case of 'infiltration of cool-damp'(寒濕浸淫), us-ed 'Yui-lyung-tang', In case of asthenia of spleen, used 'Sam-lyung-bak-chul-san'. In case of yin-deficiency of liver and kidney(肝腎陰虛), used 'Ji-bak-ji-hwang-hwan'(知柏地黃丸), or 'Ho-jam-hwan'(虎潛丸). 10. Cervical spondylosis with myelopathy is occuered by compression or ischemia of spinal cord. 11. The cause of cervical spondylosis with myelopathy consist of 'flow disturbance of the channel points of tai-yang'(太陽經兪不利), 'stagnancy of cool-damp'(寒濕凝聚), 'congestion of phlegm-damp stagnant substances'(痰濕膠阻), 'impairment of liver and kidney'(肝腎虛損). 12. In treatment of cervical spondylosis with myelopathy, are used 'Ge-ji-ga-gal-geun-tang-gagam'(桂枝加葛根湯加減), 'So-hwal-lack-dan-hap-do-hong-eum-gagam(小活絡丹合桃紅飮加減), 'Sin-tong-chuck-ue-tang-gagam(身痛逐瘀湯加減), 'Do-dam-tang-hap-sa-mul-tang-gagam'(導痰湯合四物湯加減), 'Ik-sin-yang-hyel-guen-bo-tang'(益腎養血健步湯加減), 'Nok-gakyo-hwan-gagam'(鹿角膠丸加減). 13. The cause of muscle dystropy is related with 'the impairement of vital qi'(元氣損傷), and 'impairement of five Zang organ'(五臟敗傷). Symptoms and signs are classified into asthenia of spleen and stomach, deficiency with excess, 'deficiency of liver and kidney'(肝腎不足) infiltration of damp-heat, 'deficiency of qi and blood'(氣血兩虛), 'yang deficiency of spleen and kidney'(脾腎陽虛). 14. 'Bo-jung-ik-gi-tang'(補中益氣湯), 'Gum-gang-hwan'(金剛丸), 'Yi-gong-san-hap-sam-myo-hwan'(異功散合三妙丸), 'Ja-hyel-yang-gun-tang'(滋血養筋湯), 'Ho-jam-hwan'(虎潛丸) are used for muscle dystropy. 15. The causes of myasthenia gravis are classified into 'insufficiency of middle warmer energy'(中氣不足), 'deficiency of qi and yin of spleen and kidney'(脾腎兩處), 'asthenia of qi of spleen'(脾氣虛弱), 'deficiency of qi and blood'(氣血兩虛), 'yang deficiency of spleen and kidney'(脾腎陽虛). 16. 'Bo-jung-ik-gi-tang-gagam'(補中益氣湯加減), 'Sa-gun-ja-tang-hap-gi-guk-yang-hyel-tang'(四君子湯合杞菊地黃湯), 'Sa-gun-ja-tang-hap-u-gyi-eum-gagam'(四君子湯合右歸飮加減), 'Pal-jin-tang'(八珍湯), 'U-gyi-eum'(右歸飮) are used for myasthenia gravis.

• Economic and Environmental Geology
• /
• v.30 no.4
• /
• pp.289-301
• /
• 1997

The Boguk cobalt mine is located within the Cretaceous Gyeongsang Sedimentary Basin. Major ore minerals including cobalt-bearing minerals (loellingite, cobaltite, and glaucodot) and Co-bearing arsenopyrite occur together with base-metal sulfides (pyrrhotite, chalcopyrite, pyrite, sphalerite, etc.) and minor amounts of oxides (magnetite and hematite) within fracture-filling $quartz{\pm}actinolite{\pm}carbonate$ veins. These veins are developed within an epicrustal micrographic granite stock which intrudes the Konchonri Formation (mainly of shale). Radiometric date of the granite (85.98 Ma) indicates a Late Cretaceous age for granite emplacement and associated cobalt mineralization. The vein mineralogy is relatively complex and changes with time: cobalt-bearing minerals with actinolite, carbonates, and quartz gangues (stages I and II) ${\rightarrow}$ base-metal sulfides, gold, and Fe oxides with quartz gangues (stage III) ${\rightarrow}$ barren carbonates (stages IV and V). The common occurrence of high-temperature minerals (cobalt-bearing minerals, molybdenite and actinolite) with low-temperature minerals (base-metal sulfides, gold and carbonates) in veins indicates a xenothermal condition of the hydrothermal mineralization. High enrichment of Co in the granite (avg. 50.90 ppm) indicates the magmatic hydrothermal derivation of cobalt from this cooling granite stock, whereas higher amounts of Cu and Zn in the Konchonri Formation shale suggest their derivations largely from shale. The decrease in temperature of hydrothermal fluids with a concomitant increase in fugacity of oxygen with time (for cobalt deposition in stages I and II, $T=560^{\circ}C-390^{\circ}C$ and log $fO_2=$ >-32.7 to -30.7 atm at $350^{\circ}C$; for base-metal sulfide deposition in stage III, $T=380^{\circ}-345^{\circ}C$ and log $fO_2={\geq}-30.7$ atm at $350^{\circ}C$) indicates a transition of the hydrothermal system from a magmatic-water domination toward a less-evolved meteoric-water domination. Sulfur isotope data of stage II sulfide minerals evidence that early, Co-bearing hydrothermal fluids derived originally from an igneous source with a ${\delta}^{34}S_{{\Sigma}S}$ value near 3 to 5‰. The remarkable increase in ${\delta}^{34}S_{H2S}$ values of hydrothermal fluids with time from cobalt deposition in stage II (3-5‰) to base-metal sulfide deposition in stage III (up to about 20‰) also indicates the change of the hydrothermal system toward the meteoric water domination, which resulted in the leaching-out and concentration of isotopically heavier sulfur (sedimentary sulfates), base metals (Cu, Zn, etc.) and gold from surrounding sedimentary rocks during the huge, meteoric water circulation. We suggest that without the formation of the later, meteoric water circulation extensively through surrounding sedimentary rocks the Boguk cobalt deposits would be simple veins only with actinolite + quartz + cobalt-bearing minerals. Furthermore, the formation of the meteoric water circulation after the culmination of a magmatic hydrothermal system resulted in the common occurrence of high-temperature minerals with later, lower-temperature minerals, resulting in a xenothermal feature of the mineralization.

• Economic and Environmental Geology
• /
• v.36 no.6
• /
• pp.391-405
• /
• 2003

The Daebong gold-silver deposit consists of mesothermal massive quartz veins thar are filling the fractures along fault shear (NE, NW) Bones within banded or granitic gneiss of Precambrian Gyeonggi massif. Based on vein mineralogy, ore textures and paragenesis, ore mineralization of this deposits is composed of massive white quartz vein(stage I) which was formed in the same stage by multiple episodes of fracturing and healing, and transparent quartz vein(stage II) which is separated by a major faulting event. Stage I is divided into the 3 substages. Ore minerals of each substages are as follows: 1) early stage I=magnetite, pyrrhotite, arsenopyrite, pyrite, sphalerite, chalcopyrite, 2) middle stage I=pyrrhotite, arsenopyrite, pyrite, marcasite, sphalerite, chalcopyrite, galena, electrum and 3) late stage I=pyrite, sphalerite, chalcopyrite, galena, electrum, argentite, respectively. Ore minerals of the stage II are composed of pyrite, sphalerite, chalcopyrite, galena and electrum. Systematic studies (petrography and microthermometry) of fluid inclusions in stage I and II quartz veins show fluids from contrasting physical-chemical conditions: 1) $H_2O-CO_2-CH_4-NaCl{\pm}N-2$ fluid(early stage I=homogenization temperature: 203∼3$88^{\circ}C$, pressure: 1082∼2092 bar, salinity: 0.6∼13.4 wt.%, middle stage I=homogenization temperature: 215∼28$0^{\circ}C$, salinity: 0.2∼2.8 wt.%) related to the stage I sulfide deposition, 2) $H_2O-NaCl{\pm}CO_2$ fluid (late stage I=homogenization temperature: 205∼2$88^{\circ}C$, pressure: 670 bar, salinity: 4.5∼6.7 wt.%, stage II=homogenization temperature: 201-3$58^{\circ}C$, salinity: 0.4-4.2 wt.%) related to the late stage I and II sulfide deposition. $H_2O-CO_2-CH_4-NaCl{\pm}N_2$ fluid of early stage I is evolved to $H_2O-NaCl{\pm}CO_2$ fluid represented by the $CO_2$ unmixing due to decrease in fluid pressure and is diluted and cooled by the mixing of deep circulated meteoric waters ($H_2O$-NaCl fluid) possibly related to uplift and unloading of the mineralizing suites. $H_2O-NaCl{\pm}CO_2$ fluid of stage II was hotter than that of late stage I and occurred partly unmixing, mainly dilution and cooling for sulfide deposition. Calculated sulfur isotope compositions ({\gamma}^{34}S_{H2S}$) of hydrothermal fluids (3.5∼7.9%o) indicate that ore sulfur was derived from mainly an igneous source and partly sulfur of host rock. Measured and calculated oxygen and hydrogen isotope compositions ({\gamma}^{18}O_{H_2O}$, {\gamma}$D) of ore fluids (stage I: 1.1∼9.0$\textperthousand$, -92∼-86{\textperthansand}$, stage II: 0.3{\textperthansand}$, -93{\textperthansand}$) and ribbon-banded structure (graphitic lamination) indicate that mesothermal auriferous fluids of Daebong deposit were two different origin and their evolution. 1) Fluids of this deposit were likely mixtures of $H_2O$-rich, isotopically less evolved meteoric water and magmatic fluids and 2) were likely mixtures of $H_2O$-rich. isotopically heavier $\delta$D meteoric water and magmaticmetamorphic fluids.