• Journal of Korea Water Resources Association
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• v.53 no.10
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• pp.833-843
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• 2020

Ecohydraulics is a newly born discipline in the early 1990s by the interdisciplinary approach combined with aquatic ecology in one discipline and geomorphology, hydrology, and fluid hydrodynamics in another. Major areas of ecohydraulics can be delineated as habitat hydraulics (including environmental flow), vegetation hydraulics, eco-corridor hydraulics, eutrophication hydraulics, and ecological restoration hydraulics. Reviews of relevant international journals and literature reveal that ecohydraulics has remained in the limited areas of fish response, hydraulic modeling, and physical habitat response. It has not reached a truly interdisciplinary stage. Literature reviews in Korea reveal that only 3% of the total number of the papers listed in the Journal of KWRA during the last 24 years is related to ecohydraulics. It is about 20% of the total listed in the Journal of Ecology and Resilient Infrastructure. Most of those related to ecohydraulics in Korea concern vegetation hydraulics, habitat hydraulics, and ecological restoration hydraulics. In contrast, dynamic flow modeling areas, including turbulence, fauna motion simulation, and eutrophication hydraulics, are not found. Areas of further research in ecohydraulics in Korea may be specified as follows: 1) environmental flows adapted to the traits of the rivers in Korea, 2) development of the dynamic floodplain vegetation models (DFVM) to assess the changes from the white river to green river, 3) development of the eutrophication hydraulic model to predict the freshwater algal blooms, and 4) development of the models to evaluate the physical, chemical, and biological impacts of the stream restoration, decommissioning and removal of old weirs or small dams.

• Journal of Conservation Science
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• v.27 no.4
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• pp.441-450
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• 2011

This study investigated potential damages and conservation methods for the ceramics (without glaze) by examination of physical and chemical effects from the burial environments. For this study, pottery samples excavated from Daejeon Hakha, Asan Eumbong, Hwasung Sogeunsan and Kongju Haengbokdosi were examined with released ions and extraction through desalination. The result showed that the ion inflow into the ceramics was dependent upon the porosity and the absorption of ceramics. The high temperature fired ceramics (over $1,000^{\circ}C$) have low porosity and absorption, therefore almost no salt infiltration during the burial period. However, low temperature fired ceramics (under $800^{\circ}C$) have high porosity and absorption, and most of salts were removed during the desalination. The 40 to 60% of salts were removed in two days and 60 to 80% of slats were released in a week. Furthermore, fertilizer residues such as $K_2SO_4$, in soils were detected in the ceramcis. Also the characteristics of buried soil affected ion infiltration into ceramics. Ceramics buried in sandy soil had relatively less ion contents from buried environments than those in clayey soil. Therefore, low temperature fired ceramics could do not only cleaning but also desalination if it is necessary, and the period could be decided to the condition of ceramics.

• Journal of Conservation Science
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• v.28 no.4
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• pp.343-351
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• 2012

Excavated archaeological iron objects are prevented from being corroded going through desalination which slow down being corroded. However archaeological iron objects are liable to be corroded due to the high ionization tendency even though they are stored in environment restricted from corrosion factors. Iron objects could be deteriorated more than just excavated. Therefore this study investigated about the characteristic of re-corrosion and the effect on objects. In study, archaeological iron nails in storage for 4 years after conservation treatments were tested. Optical microscopy and X-ray photography for appearance, XRD, SEM-EDS, Raman spectroscopy for chemical composition, IC for chloride ions concentration inside iron nails were used. As results, iron nails carried out conservation treatments measured a high concentration of chloride ions after the long storage period. The form of objects were not in good condition such as broken or destroyed when the high chloride ions concentration was detected. In addition, the yellow and red powdery corrosion product were detected on the boundary between corrosion products and substrates and they were identified as akaganeite which is symptom of active corrosion.

• Journal of the Mineralogical Society of Korea
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• v.30 no.4
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• pp.179-186
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• 2017

This study investigated the mineralogical characteristics of lime mortars used in pointing of Namhansanseon Yeojang from Joseon dynasty. Polarization microscopy revealed quartz, feldspar, mica, pyroxene and opaque minerals in the lime mortars. XRD analysis also confirmed clay minerals chlorite and kaolin. As a result of particle size analysis of lime mortars, the particle size distribution was wide and size was not uniform. 60% of samples were corresponded to the sand area. The chemical components detected from XRF analysis, 8.71-11.18 % of Ca as the main component of lime and $SiO_2$, $Al_2O_3$, and $Fe_2O_3$ in soil minerals were main components. The lime mortars showed an endothermic peak due to decarbonization reaction of $CaCO_3$ at $750^{\circ}C$ and weight reduction rate of 10%. The microstructures were agglomerated amorphous and observed rhombohedral calcite crystals by scanning electron microscope. It is considered that the pointing of Yeojang is a mortar mixed with lime and soil. In addition the Hanbongseong Yeojang was constructed using the same materials and construction technique because the minerals composition is not different according to the Yeojang location and use.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.4 no.3
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• pp.19-29
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• 2001

This study was carried out to examine the recovery of forest ecosystem at the burned areas of coniferous (Mt. Chosdae) and broad leaved forest (Samsinbong in Mt. Chiri) by investigating the changes of forest vegetation. The results obtained are summarized as follows; 1. In the Samsinbong, the total number of species appeared at the burned area were 5 species at tree layer, 11 species at sub-tree layer and 24 species at herb layer, and at the unburned area were 5 species at tree layer, 14 species at sub-tree layer, 18 species at shrub layer and 23 species at herb layer, respectively. In the Mt. Chosdae, the total number of species appeared at the burned area only showed to 83 species at herb layer, and at the unburned area were 7 species at tree layer, 13 species at sub-tree layer, 21 species at shrub layer and 46 species at herb layer, respectively. 2. In the soil chemical properties of the burned area of Samsinbong, pH was 5.8, and contents of Organic matter, Total nitrogen, Available $P_2O_5$, Exchangeable $K^+$, Exchange $Ca^{{+}{+}}$ and Exchange $Mg^{{+}{+}}$ were 7.42%, 0.73%, 28.5mg/kg, 1.3me/100g, 13.3me/100g and 2.2me/100g, respectively. But they showed a tendency to decrease by passing the time. In the soil chemical properties of the burned area of Mt. Chosdae, pH was 5.3, and contents of Organic matter, Total nitrogen, Available $P_2O_5$, Exchangeable $K^+$, Exchange $Ca^{{+}{+}}$ and Exchange $Mg^{{+}{+}}$ were 6.42%, 0.25%, 24.4mg/kg, 0.7me/100g, 3.7me/100g and 2.1me/100g, respectively, and they also showed a tendency to decrease by passing the time. 3. An the burned and unburned areas of Samsinbong, the total evolved amounts of soil respiration were $4,049.1mg/m^2/h$ and $9,950.0mg/m^2/h$, respectively. An the burned and unburned areas of Mt. Chosdae, the total evolved amounts of soil respiration were $4,392.4mg/m^2/h$ and $8,286.5mg/m^2/h$, respectively.

• International Journal of Highway Engineering
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• v.3 no.1 s.7
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• pp.177-184
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• 2001

A recycling agent has been manufactured on the basis of the chemical composition of reclaimed asphalt binders and virgin asphalt binders. The chemical compositions of reclaimed asphalt binders extracted from reclaimed asphalt pavements have been analyzed according to the ASTM method and the results were compared to those of virgin asphalt binder AP-3. Reclaimed asphalt binders have shown that asphaltenes was increased whereas saturates, naphthene aromatics, and polar aromatics fractions were decreased. A recycling agent made of aromatic compounds, in which its chemical composition is similar to the aromatics fraction in asphalt binders, has been produced to reduce the amount of asphaltenes in reclaimed asphalt hinders. The evaluation of the recycling agent produced was performed by testing ductility, rolling and ball softening point, penetration at $25^{\circ}C$ and viscosity at $60^{\circ}C$. It was found that, by adding the recycling agent 20% by weight to the reclaimed asphalt binders, the physical properties of reclaimed asphalt binders was recovered to the level of virgin asphalt binder AP-3.

• Journal of Microbiology and Biotechnology
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• v.15 no.1
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• pp.105-111
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• 2005

End-stage renal disease is a fatal and devastating disease that is caused by progressive and irreversible loss of functioning nephrons in the kidney. Dialysis and renal transplantation are the common treatments at present, but these treatments have severe limitations. The present study investigated the possibility of reconstructing renal tissues by transplantation of renal precursor cells to replace the current treatments for end-stage renal disease. Embryonic renal precursor cells, freshly isolated from metanephroi of rat fetus at day 15 post-gestation, were seeded on biodegradable polymer scaffolds and transplanted into peritoneal cavities of athymic mice for three weeks. Histologic sections stained with hematoxylin & eosin and periodic acid-Schiff revealed the formation of primitive glomeruli, tubules, and blood vessels, suggesting the potential of embryonic renal precursor cells to reconstitute renal tissues. Immunohistochemical staining for proliferating cell nuclear antigen, a marker of proliferating cells, showed intensive nuclear expression in the regenerated renal structures, suggesting renal tissue reconstitution by transplanted embryonic renal precursor cells. This study demonstrates the reconstitution of renal tissue in vivo by transplanting renal precursor cells with biodegradable polymer scaffolds, which could be utilized as a new method for partial or full restoration of renal structure and function in the treatment of end-stage renal disease.

• Restorative Dentistry and Endodontics
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• v.20 no.1
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• pp.129-141
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• 1995

Composite resin and glass-ionomer cement can be used for the purpose of repair of defective amalgam restoration. The purpose of this study was to evaluate of shear bond strength of esthetic restorative materials to dental amalgam. The materials used in this study were Photo Clearfil Bright(light curing composite resin), Clearfil F II(chemical curing composite resin), Fuji II LC(light curing glass-ionomer cement), Fuji II (chemical curing glass-ionomer cement), All-Bond 2(intermediary), and Scotchbond Multi-Purpose (intermediary). A total of 120 acrylic cylinders with amalgam were divided into 8 groups After amalgam condensation, all specimens were stored for 48 hours in water at $37^{\circ}C$ and tested with Instron universal testing machine between amalgam and composite resins and glass-ionomer cements. The data were analyzes statiscally by ANOVA and Duncan test. The following results obtained ; 1. The shear bond strength of bonded composite resin to amalgam was higher than bonded glass-ionomer cement(P<.001). 2. The group 4 had highest shear bond strength with 15.45kgf/$cm^2$ and the group 5 had lowest shear bond strenght with 3.26kgf/$cm^2$(P<.001). 3. In the group 3, 4, 5, 6, the group 3, 4 with All-Bond 2 had higher shear bond strength than the group 5, 6 with Scotch bond MP both in light-curing and in chemical curing. 4. Both in composite resin and glass-ionomer cement, chemical curing materials had higher shear bond stength than light curing materials(P<.001).

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.293-300
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• 1999

The maintenance for the stability of tunnel, especially on downtown area, careful check must be considered during construction stage and after. Moreover we have to achieve the stability of tunnel by ground improvement and reinforcement when ground condition is bad or tunnel failures under the various ground conditions. In this paper, it is presented the case of tunnel failure and the state of restoration by ground reinforcements at seoul subway $\bigcirc$-$\bigcirc$ construction site. For the purpose of ground reinforcement, first, curtain wall was established by chemical grouting. Secondly, cement milk grouting was carried by upper part of tunnel crown. Also Boreholes loading test and tunnel monitoring were carried by in failure site for the long term stability of tunnel.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.434-437
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• 2005

Chemical Mechanical Polishing (CMP) has become an essential step in the overall semiconductor wafer fabrication technology. In general, CMP is a surface planarization method in which a silicon wafer is rotated against a polishing pad in the presence of slurry under pressure. The polishing pad, generally a polyurethane-based material, consists of polymeric foam cell walls, which aid in removal of the reaction products at the wafer interface. It has been found that the material removal rate of any polishing pad decreases due to the so-called 'pad glazing' after several wafer lots have been processed. Therefore, the pad restoration and conditioning has become essential in CMP processes to keep the urethane polishing pad at the proper friction coefficient and to allow effective slurry transport to the wafer surface. Diamond pad conditioner employs a single layer of brazed bonded diamond crystals. Due to the corrosive nature of the polishing slurry required in low pH metal CMP such as copper, it is essential to minimize the possibility of chemical interaction between very low pH slurry (pH <2) and the bond alloy. In this paper, we report an exceptional protective coated conditioner for in-situ pad conditioning in low pH Cu CMP process. The protective Cr-coated conditioner has been tested in slurry with pH levels as low as 1.5 without bond degradation.