• Ecology and Resilient Infrastructure
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• v.10 no.4
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• pp.143-160
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• 2023

This study applied the stream physical habitat assessment system to obtain basic information for river restoration and watershed management in high-gradient and mid-gradient streams in the Naeseongcheon basin. The total length of high-gradient and mid-gradient streams in the Naeseongcheon basin is about 273 km, and as a result of the assessment, it was analyzed that suboptimal reach was about 8.2 km, normal reach was 180.3 km, and marginal reach was 84.7 km. In addition, the physical habitat quality of high-gradient streams was analyzed to be normal condition with an average of 106 points (53%), and in particular, the score of channel/hydraulic category, which is the most important for the habitat of aquatic animals, was analyzed to be normal, close to the limit, with an average of 54 points (45%). The physical habitat quality of mid-gradient streams was found to be in normal condition with an average of 90 points (45%), and the score of channel/hydraulic category was in marginal condition with an average of 39 points (32%). Overall, among 165 reaches of high-gradient and mid-gradient streams in the Naeseongcheon basin, 4 reaches (3%) were evaluated as suboptimal, 119 reaches (72%) were normal, and 42 reaches (25%) were considered marginal. These results showed that the physical habitat of Naeseongcheon was significantly disturbed. Disturbance of stream physical habitat in the Naeseongcheon basin occured due to farmland around stream, urbanization, reservoir construction, and river maintenance.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.229-236
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• 2017

Flow characteristics analysis and tracer test simulations for the rectangular typed sedimentation basins, which have been operated at D_water treatment plant in Korea, were carried out using CFD (Computational Fluid Dynamics) techniques for design ($15,864m^3/day$) and operation flowrate ($33,333m^3/day$). Also, each efficiency of the sedimentation basin was evaluated by application of the Lagrangin technique on the assumption of the particles flowing into the inlet of the sedimentation basin. From the results of simulation, the mean velocity values for making the flow in the settling basin as a plug flow region were derived as 0.00193 m/s and 0.00417 m/s, respectively. In addition, ${\beta}$ (effective contact factor) values were calculated to be 0.51 and 0.46, and the Morrill Index values were 6.05 and 3.21, respectively for both flowrate conditions.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.6
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• pp.153-162
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• 2015

In this study, we analyzed the trends of water quality along the main stream in Nakdong river basin using the recent data and seasonal Mann-Kendall test. Monthly averaged values of DO, BOD, SS, COD, TN, and TP from 1989 to 2014 for 14 stations (including 2 TMDLs stations) were used in the study. The trend analysis results showed that BOD and TP at most stations has decreasing temporal trend except a few stations while COD and SS showed increasing trend at most stations. Temporal trends in TN at 8 stations were found to be statistically significant and 5 of them showed increasing temporal trend. Temporally averaged BOD, COD, TN and TP were generally increasing as going downstream and the worst water quality were found at Goryeong and Hyunpung station. Overall, water quality of Nakdong river especially in COD, SS, and TN getting worse in time at most stations and as going downstream.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.52-56
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• 2001

In order to get information on more reliable S-wave attenuation characteristics in the Gyeongsang Basin, local earthquake data compiled during the period of years 1997~2000 are analyzed using spectral smoothing technique. Total 421 seismograms recorded at 12 local stations by 68 earthquakes of local magnitudes equal to or greater than 1.4 are examined. Among them, 155 records with good S/N ratio were analyzed. As results, statistically well constrained attenuation characteristics are fecund. Those are; (1) 0.000158362 < $x_{q}$-value (0.000196474) < 0.000234586, (2) 0.00657 < $x_{s}$-value (0.01061) < 0.01465, and (3) 1158 < Q-value (1383) < 1716, where the upper and low limits are values with 95% confidence level. We obtained remarkably well constrained $X_{s}$-value which has not been determined previously. The results can be used as input data far ground motion computations in earthquake engineering.ing.g.

• Economic and Environmental Geology
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• v.32 no.2
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• pp.141-150
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• 1999

The granitic rocks are distributed in the northeastern Gyeongsang basin, and are subdivided into the Youngduk, Younghae, Jangsadong and Onjeong granite. Based on the chondrite normalized patterns of REE by primitive mantle, the Jangsadong granite is more negative Eu anomaly than other granites. On the patterns of trace and rare earcth elements normalized by primitive mantle, Sr, P, Nd, Sm and Ti contents of t도 Youngduk and Younghae granites are higher than those of Jangsadong and Onjeong granites. Based on K-Ar ages, the Youngduk granite is 166.5 Ma for biotite, Younghae granite is 158.7 to 178.0 Ma for hornblende, Jangsadong granite is 113.8 to 118.4 Ma for K-feldspar and hornblende, and Onjeong granite is 67.4 Ma for biotite. Thus, geochemical and geochronological results suggest two plutonic episodes :the Youngduk-Younghae granites and Jangsadong-Onjeong granites suggest two plutonic episodes : the Youngduk-Younghae granites and Jangsadong-Onjeong granites. Jurassic plutonism cooled faster than Cretacous plutonism in the study area.

• Economic and Environmental Geology
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• v.28 no.5
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• pp.493-501
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• 1995

Carboniferous and Cretaceous rock samples were collected from 3 and 12 sites respectively in the vicinity of the Okcheon Zone. Mean directions of characteristic component magnetizations from Carboniferous rocks along the Honam Shearzone reveal that the Okcheon zone was considerably rotated and deformed during Triassic. The amount of rotations were clockwisely $80.3^{\circ}$ in Mungyeong and $42.4^{\circ}$ in Hwasun areas. Mean directions of characteristic component magnetizations obtained from Cretaceous Yeongdong and Neungju Basin were identical to those from the Gyeongsang Basin in the Yeongnam Block indicating no relative motion between them since Cretaceous. Cretaceous paleopole position from 4 locations, $204.9^{\circ}E$ in longitude and $65.1^{\circ}N $ in latitude.

• The Journal of the Petrological Society of Korea
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• v.8 no.1
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• pp.14-23
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• 1999

The northeastern part of the Gyeongsang Basin is widely covered by the Cretaceous Hayang Group (Aptian to Albian). The Hayang Group consists of the IIjig. Hupyeongdong, Jeomgog, and Sagog formations. Heavy mineral analysis was carried out to define the possible source rocks of the Haynag Group snadstones. Heavy minerals separated from IIjig, Hupyeongdong, and Jeomgog sandstones are hematite, ilmenite, leucoxene, magnetite, pyrite, actinolite, andalusite, apatite, biotite, chlorite, epidote, garnet, hornblende, kyanite, monazite, muscovite, rutile, sphene, spinel, staurolite, tourmaline, and zircon. Based on their close association and sensitiveness, the heavy mineral assemblages can be classified into 6 syutes: 1)apatite-green tourmaline-sphene-colorless/yellowish zircon; 2) colorless garnet-epidote-rutile-brown tourmaline; 3) rounded purple zircon-rounded tourmaline-rounded rutile; 4) augite-hornblende-color- less zircon; 5) epidote-garnet-sphene; and 6) blue tourmaline. The possible source rocks corresponding to each assemblage are 1) granitic rocks; 2) metamorphic rocks (schist and gneiss) ; 3) older sedimentary rocks; 4) andesitic rocks; 5) metamorphosed impure limestone; and 6) pegmatite, respectively. Previous paleocurrent data suggest that the sediments of the study area were mainly derived from the northeastern to southeastern directions. Thus, the most possible source areas would be the east extension part of the sobaegsan metamorphic complex to the northeast and the Cheongsong Ridge to the southeast.

• The Journal of the Petrological Society of Korea
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• v.18 no.2
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• pp.115-135
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• 2009

We have studied general orientational characteristics of microcracks distributed in Tertiary crystalline tuff from the northeastern part of the Gyeongsang Basin. 108 sets of microcracks on horizontal surfaces of 6 rock samples from Heunghae-eup and Cheongha-myeon, Pohang-si areas were distinguished by image processing. Those microcrack sets show a distinct linear array in 38 images. Whole domain of the directional angle(${\theta}$)-frequency(N) chart for crystalline tuff can be divided into 20 domains in terms of the phases of the distribution of microcracks. From the related chart, microcrack sets show preferred orientation which are coincident with the direction of vertical common joints. Consequently, the potential for macroscopic vertical joints in a rock body can be inferred from the directional angle showing high frequency in each domain of the related chart. This joint pattern is nearly the same in Mesozoic granites from Seokmo-do, Gwanghwa-gun. From the rose diagram for orientations of microcrack in crystalline tuff, orientations of dominant sets of microcracks in terms of frequency orders reflect representative orientations of maximum principal stress acted on crystalline tuff. Meanwhile, orientations of microcracks in crystalline tuff were compared with those of open microcracks in Bulgugsa granites from the southwestern part of the Gyeongsang Basin, and vertical rift/grain planes from Mesozoic granite quarries in Korea. In regional distribution chart, the agreement of distribution pattern between above two types of microcrack sets and vertical planes suggests that microcrack systems developed in crystalline tuff probably occur regionally in Mesozoic granites in Korea.

• The Journal of the Petrological Society of Korea
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• v.26 no.1
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• pp.1-11
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• 2017

We have dated the K-Ar, Ar-Ar and U-Pb ages of the Masan hornblende-biotite granite in the southern Cretaceous Gyeongsang basin to constrain its emplacement age. The ~108 Ma hornblende K-Ar age obtained in the study is similar to the previously reported Rb-Sr age. However, the single grain total fusion $^{40}Ar/^{39}Ar$ dating on hornblende failed to yield statistically meaningful ages because the isotopic system was open during its alteration. Thus the hornblende K-Ar age in the study is also unlikely to be reliable. The single grain total fusion $^{40}Ar/^{39}Ar$ dating on biotite yielded an average age of $75.8{\pm}3.0Ma$. Apart from scattered data in the range of ~45-75 Ma, the average age increased to ~80 Ma. The SHRIMP and LA-MC-ICPMS U-Pb isotopic compositions of zircon from the Masan hornblende-biotite granite yielded its emplacement age as $87.6{\pm}2.7Ma$ and $86.8{\pm}0.4Ma$, respectively. It is thus likely that the ~80 Ma $^{40}Ar/^{39}Ar$ age of biotite might reflect the cooling age of Masan hornblende-biotite granite or the thermal influences from later intense igneous activities in the Gyeongsang basin.

• Economic and Environmental Geology
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• v.22 no.1
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• pp.21-34
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• 1989

Chindong granites are classified into granodiorite, tonalite and quartz-diorite, and Yucheon - Eonyang granites into monzo-granite by the Streckeisen diagram. These granitic rocks of Cretaceous age show trend of calc-alkaline magma, and the magmatic evolution from basic to acidic rocks is consistant with the general crystallization path of the Cretaceous granitic rocks in the Gyeongsang basin. On the basis of petrological and petrochemical data, variation of major elements (K, Na, Ca, Mg) and trace elements (Rb, Sr, Ba) including ore metals (Cu, Pb, Zn) in the Cretaceous granitic rocks were studied in detail in order to investigate geochemical difference of the granitic rocks in relation to mineralization between Cu province and Pb-Zn province in the Gyeongsang basin. There is clear difference in content of the major elements between Chindong granites and Yucheon-Eonyang granites : Chindong granites have low content of K (1.62%) and Na (2.53%), and high content of Ca (3.75%) and Mg (1.42%) whereas Yucheon-Eonyang granites have high content of K (3.56-3.60%), and low content of Ca (0.96-0.26%) and Mg (0.26-0.21%). There is also clear difference in content of trace lithophile elements between Chindong granites and Yucheon-Eonyang, granites : Chindong granites have low content of Rb (86ppm) and Ba (330ppm), and high content of Sr (405ppm) while Yucheon-Eonyang, granites have high content of Rb (144-161ppm) and Ba (983-1030ppm), and low content of Sr (157-136ppm). The lithophile trace elements of Rb and Sr vary with close relationship to major elements of K and Ca, respectively. Therefore, Chindong granites are much easily distinguished from Yucheon-Eonyang granites by using relationship of K with Rb and Ca with Sr : K<3%, Rb<100ppm, Ca<2% and Sr>200ppm for Chindong granites, and K>3%, Rb>100ppm, Ca<2%, and Sr<200ppm for Yucheon-Eonyang granites. There is not clear difference in content of trace ore metals between Chindong granites and Yucheon-Eonyang granites : Chindong granites of the Cu province have low Cu content (15ppm) which is nearly equal to 13-14ppm of Yucheon-Eonyang granites of the Pb-Zn province, and Yucheon-Eonyang granites have Pb content (29-27ppm) which is rather lower than 37ppm of Chindong granites. But Cu is anomalously high in the mineralized part of Chindong granites in Gunbuk-Haman area, and Zn is apparently higher in Yucheon-Eonyang granites (51-37ppm) than in Chindong granites (29ppm). K/Pb ratio is also c1early distinguishable between Chindong granites (<850) and Yucheon-Eonyang granites (>850). Thus, it may be possible to apply geochemical difference of the granites to distinguish whether a Cretaceous granitic body is Cu related rock or Pb-Zn related rock, and whether it belongs to Cu province or Pb-Zn province in the Gyeongsang basin.