• Proceedings of the Korean Vacuum Society Conference
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• 1998.02a
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• pp.77-77
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• 1998

Present silicon dioxide (SiOz) 떠m as intennetal dielectridIMD) layers will result in high parasitic c capacitance and crosstalk interference in 비gh density devices. Low dielectric materials such as f f1uorina뼈 silicon oxide(SiOF) and f1uoropolymer IMD layers have been tried to s이ve this problem. I In the SiOF ftlm, as fluorine concentration increases the dielectric constant of t뼈 film decreases but i it becomes unstable and wa않r absorptivity increases. The dielectric constant above 3.0 is obtain어 i in these ftlms. Fluoropolymers such as polyte$\sigma$따luoroethylene(PTFE) are known as low dielectric c constant (>2.0) materials. However, their $\alpha$)Or thermal stability and low adhesive fa$\pi$e have h hindered 야1리ru뚱 as IMD ma따"ials. 1 The concept of a plasma processing a찌Jaratus with 비gh density plasma at low pressure has r received much attention for deposition because films made in these plasma reactors have many a advantages such as go여 film quality and gap filling profile. High ion flux with low ion energy in m the high density plasma make the low contamination and go어 $\sigma$'Oss피lked ftlm. Especially the h helicon plasma reactor have attractive features for ftlm deposition 야~au똥 of i앙 high density plasma p production compared with other conventional type plasma soun:es. I In this pa야Jr, we present the results on the low dielectric constant fluorocarbonated-SiOF film d밑JOsited on p-Si(loo) 5 inch silicon substrates with 00% of 0dFTES gas mixture and 20% of Ar g gas in a helicon plasma reactor. High density 띠asma is generated in the conventional helicon p plasma soun:e with Nagoya type ill antenna, 5-15 MHz and 1 kW RF power, 700 Gauss of m magnetic field, and 1.5 mTorr of pressure. The electron density and temperature of the 0dFTES d discharge are measUI벼 by Langmuir probe. The relative density of radicals are measured by optic허 e emission spe따'Oscopy(OES). Chemical bonding structure 3I피 atomic concentration 따'C characterized u using fourier transform infrared(FTIR) s야3띠"Oscopy and X -ray photonelectron spl:’따'Oscopy (XPS). D Dielectric constant is measured using a metal insulator semiconductor (MIS;AVO.4 $\mu$ m thick f fIlmlp-SD s$\sigma$ucture. A chemical stoichiome$\sigma$y of 야Ie fluorocarbina$textsc{k}$영-SiOF film 따~si야영 at room temperature, which t the flow rate of Oz and FTES gas is Isccm and 6sccm, res야~tvely, is form려 야Ie SiouFo.36Co.14. A d dielec$\sigma$ic constant of this fIlm is 2.8, but the s$\alpha$'!Cimen at annealed 5OOt: is obtain려 3.24, and the s stepcoverage in the 0.4 $\mu$ m and 0.5 $\mu$ m pattern 킹'C above 92% and 91% without void, res야~tively. res야~tively.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.2
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• pp.144-154
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• 1999

Masan Bay is highly polluted by the discharge of large quantities of effluents from the industrial complex and domestic sewage of Masan City, Southeast Korea. Surface sediments from 9 stations were used for geochemical and foraminiferal analyses in order to investigate foraminiferal response to sedimentary pollution in the Bay. The heavy metal concentrations in sediments are relatively higher than those in Kyeonggi Bay and Daesan area, west coastal region of Korea. Zn, Cd, Pb, and As are more concentrated than in world average shale, indicating that the municipal and industrial effluents cause sediment contamination. Responses of benthic foraminifera to the sedimentary pollution effect document a degree of pollution in Masan Bay. The species number and diversity in Masan Bay had lower values than those in Gadeog Channel. In Masan Bay, agglutinated foraminifera are abundant and calcareous foraminiferal tests were frequently pyritized. Eggerella advena and Trochammina pacifica dominated at levels of pollution and could be opportunistic species. These data will provide a baseline for future assessments of environmental quality in Masan Bay.

• Corrosion Science and Technology
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• v.7 no.1
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• pp.50-60
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• 2008

The majority of the described experimental results deal with relatively pure aluminium. Variations were made in the pretreatment of the aluminum substrates and an investigation was performed on the resulting changes in oxide layer composition and chemistry. Subsequently, the bonding behavior of the surfaces was investigated by using model adhesion molecules. These molecules were chosen to represent the bonding functionality of an organic polymer. They were applied onto the pretreated surfaces as a monolayer and the bonding behavior was studied using infrared reflection absorption spectroscopy. A direct and clear relation was found between the hydroxyl fraction on the oxide surfaces and the amount of molecules that subsequently bonded to the surface. Moreover, it was found that most bonds between the oxide surface and organic functional groups are not stable in the presence of water. The best performance was obtained using molecules, which are capable of chemisorption with the oxide surface. Finally, it was found that freshly prepared relatively pure aluminum substrates, which are left in air, rapidly lose their bonding capacity towards organic functional groups. This can be attributed to the adsorption of contamination and water to the oxide surface. In addition the adhesion of a typical epoxy-coated aluminum system was investigated during exposure to water at different temperatures. The coating was found to quite rapidly lose its adhesion upon exposure to water. This rapid loss of adhesion corresponds well with the data where it was demonstrated that the studied epoxy coating only bonds through physisorptive hydrogen bonding, these bonds not being stable in the presence of water. After the initial loss the adhesion of the coating was however found to recover again and even exceeded the adhesion prior to exposure. The improvement could be ascribed to the growth of a thin oxyhydroxide layer on the aluminum substrate, which forms a new, water-stable and stronger bond with the epoxy coating. Two routes for improvement of adhesion are finally decribed including an interphasial polymeric thin layer and a treatment in boiling water of the substrate before coating takes place. The adhesion properties were finely also studied as a function of the Mg content of the alloys. It was shown that an enrichment of Mg in the oxide could take place when Mg containing alloys are heat-treated. It is expected that for these alloys the (hydr)oxide fraction also depends on the pre-treatment and on the distribution of magnesium as compared to the aluminium hydroxides, with a direct impact on adhesive properties.

• Journal of Korean Society of Forest Science
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• v.99 no.3
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• pp.292-297
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• 2010

This study was carried out to provide preliminary data to purify contaminated sites by nickel (Ni). After rooted cuttings of Salix reichardtii had been grown in Ni solution (hydroponic culture), pH changes in the solution and the accumulated Ni amount in plant parts were measured and analyzed. When the Ni concentration was low enough for S. reichardtii cuttings to grow well, the pH value of the solution decreased considerably. As the Ni concentration got higher, the plant growth got poorer and the pH value decreased slowly. Roots accumulated the highest Ni amount. Leaves and stems followed after. When stems were older, the accumulated Ni amount was lower. more Ni was accumulated in the plant parts which had more flexible tissue and live cells. As the Ni concentration in solution got higher up to 50.0 ${\mu}mol$/L, so did the Ni accumulation in the plant parts. However, the plant individuals nearly died and the Ni accumulation tended to drop when the Ni concentration in solution was 100.0 ${\mu}mol$/L. The rooted cuttings of S. reichardtii grew poorer as the Ni concentration in solution got higher. The plants in solution with 100.0 ${\mu}mol$/L of Ni were practically dead in four weeks.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.414-421
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• 1991

High-purity alumina powder was prepared by extracting the natural alumino-silicate mineral (halloysite) in H$_2$SO$_4$ solution. For the selective precipitation of alum and aluminum hydroxide, the solubility diagram was prior calculated by also considering the formation of hydroxides and carbonates for all the metal ions in an aqueous solution, which allow us to control the contamination of impurities envolved in the natural minerals. Ammonium aluminum sulfate (alum) and alumium hydroxide could be successfully prepared at pH = 1.5∼2.5 and pH = 6∼8, respectively according to our solubility diagrams. The purity of alum-and hydroxide-derived ${\alpha}-Al_2O_3$ was determined to be 99.7${\%}$ and 99.0${\%}$, respectively, which indicates the former route would be more desirable for the large scale application. It is also worthy to note that the impurities like Na and Si were strongly reduced in the former (Na = 0.05${\%}$, Si = 0.09${\%}$) compared to the latter (Na = 0.29${\%}$, Si = 0.12${\%}$).

• Journal of Adhesion and Interface
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• v.16 no.4
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• pp.137-145
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• 2015

This study aimed to develop epoxy putty as a multi-purpose connection and restoration material that can be used for material-specific restoration work such as metal, wood, ceramics, earthenware and stone artifacts by replacing synthetic resins currently being used for preservation treatment of cultural assets. Existing synthetic resins have the issue of cutting force resulting from high strength, deflection resulting from long hardening time, contaminating the surface of artifacts through staining on tools or gloves and need for re-treatment resulting from material discoloration. Accordingly, paste type restoration material most widely being used in the field of cultural assets preservation treatment was selected and examined the property to select it as an object of comparison. Based on such process, epoxy putty was developed according to the kind of agent, hardener and filler. For the purpose of solving the issues of existing material and allowing the epoxy putty developed to have similar property, property experiments were conducted by selecting agents and hardeners with different characteristics and conditions. The study findings showed that both kinds are paste type that improved work convenience and deflection issue as a result of their work time of within 5~10 minutes that are about 3~10 times shorter than that of existing material. In regards to wear rate for increasing cutting force, it improved by about 3 times, thereby allowing easy molding. For the purpose of improving the issue of surface contamination that occurs during work process, talc and micro-ballon were added as filler to reduce the issue of stickiness and staining on hand. Furthermore, a multi-purpose restoration material with low shrinkage, low discoloration and high cutting force was developed with excellent coloring, lightweight and cutting force features.

• Korean Journal of Plant Resources
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• v.24 no.4
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• pp.472-481
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• 2011

In order to reuse remnants of medicinal herb extracts as an environment-friendly manure, fermented compost made from medicinal herb waste (MHWC), poultry manure compost (PMC) and MHWC+PMC (1:1, w/w) were applied on upland soil cultivated with 2 year-old Bokbunja plants. The results of the changes of soil chemical properties on upland soil, the yield and the sugar contents of the fruit harvested were summarized as follows. The pH in soils treated with composts (STCs) was significantly changed (p<0.05) compared with untreated control (UC) group. The electrical conductivity (EC) in MHWC group was decreased 0.46-0.56 times compared with UC, and it was different from PMC groups. The contents of organic matter and total nitrogen were increased in all of the treatments and MHWC group was the highest among the all groups. The content of available phosphorous was different by types and amounts of the composts. The content of heavy metal in all groups did not exceed the standard content for soil contamination. The yield and the sugar contents of the fruit harvested were the highest in the treatments of MHWC. In conclusion, MHWC is an effective compost resource on improvement of soil environment and promoting the fruit qualities.

• Journal of Environmental Science International
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• v.7 no.2
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• pp.149-156
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• 1998

Enoronmental problems caused by certain geologic conditions Include pollution of soil by heavy metal, acidization of souls , acid mine drainage, Pound-water pollution, and natural radioactivity, as well as zoo-logical hazards such as landslide and subsidence. The acrid mine drainage contains large amount of heavy metals nO, therefore. cause serious pollution onto the nearby drainage systems and soils. In spite of this prospective environmental danger, few studies have been done on the acid mine drainage derived from non-metallic ore deposits such as pyrophyllitefNapseok) deposits. The sudo-bearing pyrophyllite ores, alteration zones, and mine talllngs of pyrophylllte deposits produce acrid mine drainage by the okidation of weathering. Compared to the fresh host rocks, the ores and altered rocks of pyrophyllite deposits produce acidic solution which contain higher amount of heavy metals because of OeP lower buffering capacity to acrid solution. The pus of urine water and nearby stream water of pyrophyllite deposits are 2.1~3.7, which are strong- ly acidic and much lower than that (6.2~7.2) of upstream water and than that (6.8~7.6) of the stream water derived from the non-mineralized area. This study reveals that this acrid mine drainage can affect the downstream area which is 8km far from the pyrophyllite deposits, even though the drain Is diluted with abundant non-contaminated river water This suggmists that not only acid mine drainage but also the sulfide-bearing sediments originated from the pyrophyllite deposits move downstream and form acidic water through continuous oxidation reaction. The heavy metals such as Pb, Zn, Cu, Cd, Nl, Mn and Fe are enriched In the mine water of low pH, and their contents decrease as the pH of mine water Increases because of the Influx of fresh stream wainer. SoUs of the Pyrophyulte deposits are characterized by high contents of heavy metals. The stream sediments containing the yellowish brown precipitates formed by neutralization of acid mine drainage occur in all parts of the stream derived from the pyrophyllite deposits, and the sediments also contain high amounts of heavy metals. In summary, the acid mine drainage of the pyrophyllite deposits is located in the upstream part of Hoidong water reservoir in Pusan contains large amounts of heavy metals and flows into the Holdong water reservoir without any purification process. To protect the water of Holdong reservoir, the acid mine drainage should be treated with a proper purification process.

• Korean Chemical Engineering Research
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• v.54 no.2
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• pp.200-205
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• 2016

A drug transport carrier could be used for safe send of drugs to the affected region in a human body. The chitosan is adequate for the drug delivery carrier because of adaptable to living body. The gold, a metallic nanoparticles, tends to form a nano complex at rapidly when it combined with chitosan because of its negative charge. having energy from the other, outer gold nano-complex make heat due to its property to release the contained drugs to the target area. Silver could be also formed an useful biocompatible nano-composites with chitosan which should be used as an useful drug transfer carrier because its special ability to protect microbial contamination. Being one of the oxidized nano metals, $Fe_3O_4$ is nontoxic and has been used for its magnetic characteristics. In this study, the control of catalyst, reducing agent, and solvent amount. The chitosan-$Fe_3O_4$-gold & silver nanoshell have been changed to form about 100 nm size by ionic bond between the amine group, an end group of chitosan, and the metal. It was observed the change in order to seek for its optimum reaction condition as a drug transfer carrier.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.15-23
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• 2004

Deicer operations provide traffic safety during winter driving conditions in urban areas. Using large quantities of de-icing chemicals (i.e., $CaCl_2$ and NaCl) can cause serious environmental problems and may change behaviors of heavy metals in roadside sediments, resulting in an increase in mobilization of heavy metals due to complexation of heavy metals with chloride ions. To examine effect of de-icing salt concentration on the leaching behaviors and mobility of heavy metals (cadmium, zinc, copper, lead, arsenic, nickel, chromium, cobalt, manganese, and iron), leaching experiments were conducted on roadside sediments collected from Seoul city using de-icing salt solutions having various concentrations (0.01-5.0M). Results indicate that zinc, copper, and manganese in roadside sediments were easily mobilized, whereas chromium and cobalt remain strongly fixed. The zinc, copper and manganese concentrations measured in the leaching experiments were relatively high. De-icing salts can cause a decrease in partitioning between adsorbed (or precipitated) and dissolved metals, resulting in an increase in concentrations of dissolved metals in salt laden snowmelt. As a result, run-off water quality can be degraded. The de-icing salt applied on the road surface also lead to infiltration and contamination of heavy metal to groundwater.