• The Journal of Engineering Geology
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• v.34 no.1
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• pp.13-24
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• 2024

The purpose of this study is to identify the geology, geologic structure, hydrogeology and geomorphic characteristics of the Nari Basin and establish the controls on the discharge of water 20,000~40,000 m³/day from the Choosan Yongchulso, Ulleung Island, South Korea. Pumice and lapilli tuffs showing well-developed stratification are the predominant rock types surrounding the spring. The spring shows a structure whereby discharge occurs along a lens-like erosion cave formed by differential erosion of strata comprising tuff or pumice tuff. The Choosan Yongchulso is located at the point where the planation surface of the Nari Basin' ends and steep slopes begin. The basin is bounded on all sides by these steep slopes, except in the north, where the Choosan Yongchulso is located. Given these geomorphic characteristics, the Choosan Yongchulso is regarded as the ultimate outlet of the basin catchment area.

• Journal of the Korean earth science society
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• v.33 no.6
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• pp.534-543
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• 2012

The relationship between tectonic uplift and geophysical analysis of gravity anomalies and the in-situ stress fields in the Otway Ranges, SE Australia is addressed in this study to understand the nature and possible mechanism for the neotectonic movements. The uplift axis of the ranges is coincident with the regional Bouguer gravity highs whereas thick Tertiary sedimentary successions are highly correlated with the gravity lows along the basin rift geometry. This result suggests that the gravity highs are separated by the thick Tertiary sedimentary successions. Regional structural trends associated with faults and foldings of the deformed surfaces are consistent with the prevailing NW-SE $S_{Hmax}$ trend in this part of the continent. The anomalously positive correlation between topography and Bouguer gravity fields suggests possibly a lithospheric flexural deformation mode at a long wavelength (order of $10^2$ kms) in the region. It also suggests that the reactivation of pre-existing lithospheric structures driven by plate boundary forces plays a key role in this mode.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.440-440
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• 2012

Nanomaterials have emerged as new building blocks to construct light energy harvesting assemblies. Size dependent properties provide the basis for developing new and effective systems with semiconductor nanoparticles, quantized charging effects in metal nanoparticle or their combinations in 2 and 3 dimensions for expanding the possibility of developing new strategies for photovoltaic system. As top-down approach, we developed a simple and effective method for the large scale formation of self-assembled Cu(In,Ga)$Se_2$ (CIGS) nanostructures by ion beam irradiation. The compositional changes and morphological evolution were observed as a function of the irradiation time. As the ion irradiation time increased, the nano-dots were transformed into a nano-ridge structure due to the difference in the sputtering yields and diffusion rates of each element and the competition between sputtering and diffusion processes during irradiation. As bottom-up approach, we developed the growth of CIGS nanowires using thermal-chemical vapor deposition (CVD) method. Vapor-phase synthesis is probably the most extensively explored approach to the formation of 1D nanostructures such as whiskers, nanorods, and nanowires. However, unlike binary or ternary chalcogenides, the synthesis of quaternary CIGS nanostructures is challenging because of the difficulty in controlling the stoichiometry and phase structure. We introduced a method for synthesis of the single crystalline CIGS nanowires in the form of chalcopyrite using thermal-CVD without catalyst. It was confirmed that the CIGS nanowires are epitaxially grown on a sapphire substrate, having a length ranged from 3 to 100 micrometers and a diameter from 30 to 500 nm.

• Journal of the Korean Geographical Society
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• v.39 no.1
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• pp.56-69
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• 2004

We investigated the distribution and geomorphic development of alluvial fan in Gyeongju City including Cheonbuk area. According to a relative height to a river bed, alluvial fans of this area are divided into Higher surface, Middle surface, and Lower surface. As alluvial fans of Bulguk temple∼Ulsan bay area, the confluent fans in Cheonbuk and Gyeongju areas were formed by the Quaternary climatic change alternating glacial and interglacial stages, and the development of N-S and NW-SE fault lines. The Gyeongju alluvial fan, the largest in Korea, has been provided as the significant space for human activity since the prehistoric age. Bukcheon river formed the Gyeongju alluvial fan had not flowed over during the prehistoric and the ancient times. In contrast with general geomorphic characteristics, many springs in the Gyeongju alluvial fan are located in the middle part of the fan because ground water reaches to the surface. It is supposed that sedimental materials were not sufficiently piled up at lower reach of Bukcheon river due to the large deposits at upper and middle reach of the basin.

• 한국해양학회지
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• v.20 no.3
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• pp.55-61
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• 1985

Two hundred suspended-matter samples were collected from the continental shelf off the southeast coast of Korea during September, 1981, March, 1982 and April 1983. Superficial bottom sediments on the shelf were also taken. Based on the alalyses of TSM distribution and concentration patterns, it is considered that finegrained suspended matters are restricted to nearshore-inner shelf showing a band or zone paralleling with coastal morphology. This fact suggests a limitation of "modern" fine grained sediments to a nearshore and inner shelf band. The sand deposits with the lower value of mud content (<5%) adjacent to the shelf break and on the outer shelf would probably be "relict" sediments (old beach sediments) deposited in response to a lower stand of sea level during the Pleistocene ice age. The transgression did little to alter the distribution of sand on the outer shelf in this particular study area. The progress of shore line was so rapid that a given locality was in the beach zone and subject to rapid longshore drift and extensive reworking only for a few years. Probably the most pronounced effect of the transgression was sorting of the sand, and at least partial winnowing out of the finer fractions.

• Elastomers and Composites
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• v.35 no.4
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• pp.288-295
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• 2000

It has been tried to decrease the crosslink density of vulcanized EPDM (ethylone-propylene-diene terpolymer) rubber through a chemical devulcanization treatment. Phase transfer catalyst, alkali metal (i.e., sodium), and triphenylphosphine have been used as a chemical agent ul the devulcanization treatment. Also it has been estimated the effect of the devulcanization treatment in the case of utilization of 2-butanol as a devulcanization reaction solvent. In the devulcanization treatment using quaternary ammonium salt as a phase transfer catalyst. the devulcanization effect has been studied with the variation of catalyst molecular weight and the choice of bromide or chloride cation. In the devulcanization treatment using sodium, it has been estimated the devulcanization treatment effect depending upon the variation of reaction variables such as amount of sodium used, reaction temperature, pressure of hydrogen gas, which is used as a reaction environment. The $M_c$ value (number average molecular weight between two crosslink points) has been experimentally estimated by the equilibrium swelling method and it is quantitatively related to the crosslink density. The estimation of devulcanization effect for vulcanized EPDM rubber has been carried out by the comparison of the $M_c$ values between the untreated and the treated specimens.

• Korean Journal of Weed Science
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• v.32 no.3
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• pp.230-239
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• 2012

Coconut (Cocos nucifera L) is one of the predominant plantation crops in Sri Lankan economy which is known to have existed for over thousands of years. During the past decades coconut production had been reduced by a significant quantity. The usage of poor quality planting materials is a major reason for the low coconut production. Thus much attention needs to be paid in coconut nurseries. Weed management is a critical management practice in the nursery. Though glyphosate application is becoming popular in nurseries it can affect weeds as well as coconut seedlings growth. Therefore the effects of glyphosate were evaluated by determining the growth of shoot and root of coconut seedlings. Poly bag nursery was prepared and three treatments were used. Treatments were no glyphosate and manual weeding ($T_1$), application of glyphosate 1.08 ai kg $ha^{-1}$ at 2 monthly interval ($T_2$) and application of glyphosate 1.44 ai kg $ha^{-1}$ at 2 monthly interval ($T_3$). Application of glyphosate at early stage of seedling growth had a no significant effect on growth parameters tested. However, the concentrations of glyphosate negatively affected numbers, volumes and dry weights of secondary, tertiary and quaternary roots at the latter stage of seedling growth. The leaf area and the height of seedling were significantly reduced by the highest concentration of glyphosate. Among the growth parameters tested, seedling girth and shoot dry weight were not affected by the application of glyphosate. These results revealed that the usage of glyphosate at both concentrations negatively affected root growth of coconut seedlings. Based on these results, the both concentration levels of glyphosate should be applied to coconut nurseries before sprouting the seed nuts.

• Proceedings of the Mineralogical Society of Korea Conference
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• 2000.05a
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• pp.19-19
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• 2000

;Ultramafic xenoliths found in alkali basalts from Jeju-do, Korea are mostly spinel Iherzolites composed of olivine, orthopyroxene, clinopyroxene and spinel. A subordinate amount of spinel harzburgites and pyroxenites are also found. Temperatures for these xenoliths were estimated from the compositions of coexisting pyroxenes (Wood '||'&'||' Banno 1973; Wells 1977; Bertrand '||'&'||' Mercier 1985; Brey '||'&'||' Kohler 1990), the AI-solubility in orthopyroxene coexisting with olivine and spinel (Sachtleben '||'&'||' Seck 1981; Webb '||'&'||' Wood 1986), and from Fe/Mg partitioning between olivine and spinel (Ballhaus et al. 1991). Temperature estimates from the thermometers by Wells (1977) and Brey and Kohler (1990) are compatible. Average equilibrium temperatures by these two methods for spinel peridotites range from 890 to 1030$^{\circ}$C. Pressures for spinel peridotites were estimated from the geobarometer by Kohler and Brey (1991) derived from the equilibrium Ca content of olivine coexisting with clinopyroxene, and fall within the range of 12.9 to 26.3 kbar. The combination of the thermometer by Brey and Kohler (1990) and the geobarometer by Kohler and Brey (1991) yields P- T estimates for Jeju-do spinel peridotites that fall in experimentally determined spinel lherzolite field in CFMASCr system (O'Neill 1981). These P-T data sets have been used to construct the Quaternary Jeju-do geotherm, which is significantly different from the conventional conductive geotherm. The xenolith-derived geotherm has a higher T gradient at low P (13 kbar) than at high P, which may be due to perturbation of the conductive heat flow by magma underplating or overplating at the crust-mantle boundary. Temperature estimates and statistics on the xenoliths indicate that the crust/mantle boundary in Jeju-do lies at about 11 kbar (~39 km). Spinellherzolite is inferred as a main constituent rock of the uppermost lithospheric mantle beneath Jeju-do. Pyroxenites were intercalated in peridotites in similar depth and temperature as re-equilibrated veins or lens.

• Journal of The Geomorphological Association of Korea
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• v.24 no.2
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• pp.79-90
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• 2017

This study investigated the correlation between the diatom community and the environmental variables on the tidal flat surface of the eastern part of Gomso Bay in the West coast of Korea in order to utilize the quantitative sea level record as a basic data. 24 sediment samples at 10cm intervals downstream of the Galgok Stream were used for diatom analysis, grain size analysis and CCA. As a result of diatom analysis, marine diatoms dominated at lower altitudes and the ratio of diatoms to fresh water diatoms and brackish diatoms increased toward upland. As a result of CCA, the contribution of environmental variables was analyzed as 25.3% at altitude, 21.6% at sand, 13.3% at skewness, etc. This means that altitude above sea level has the greatest influence on the diatom composition in the tidal flat surface. It suggests that the contribution of environmental variables at altitude above sea level can be used as a basic data for the quantitative records for reconstruction of paleo-sea level.

• Textile Coloration and Finishing
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• v.33 no.2
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• pp.72-78
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• 2021

The purpose of this study, the purpose of this study is to activate the antibacterial effect on the Chlorinated polyvinyl chloride film by using Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride antibacterial agent with Chlorinated polyvinyl chloride polymer, which is inexpensive and has excellent properties such as heat resistance and chemical resistance. The Chlorinated polyvinyl chloride polymer was dissolved in a dimethylacetamide solvent, and film samples were prepared by varying the ratio of Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride to study the antibacterial performance. A Scanning Electron Microscope-Energy Dispersive X-ray Spectrometer and X-ray photoelectron spectroscopy were employed to confirm the elements in the samples. According to the initial decomposition temperature of the Chlorinated polyvinyl chloride film and the Chlorinated polyvinyl chloride/Octadecyldimet hyl (3-triethoxy silylpropyl) ammonium chloride(10%) film using a Thermogravimetric analyzer(TA-DTA), it was confirmed that the initial decomposition temperature was lowered due to the influence of Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride. In addition, in order to measure the mechanical properties, Universal testing machine was used and the result showed that a strength of Chlorinated polyvinyl chloride/Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride(10%) was 36.8 MPa. The antimicrobial properties of the Chlorinated polyvinyl chloride/Octadecyldimethyl (3-triethoxy silylpropyl) ammonium chloride(10%) film showed 99.9% antimicrobial properties.