• Journal of Life Science
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• v.20 no.5
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• pp.717-722
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• 2010

The safety of animal feed was evaluated by analyzing the levels of heavy metals (Pb, Cr, Cd, As, Se and Ag) in cattle, swine, and poultry feeds and the levels of Cu, Zn and P in swine feed. Feeds used in the analysis were produced in Korea from 2004 through the first half of 2007. The results of the study revealed that, with the exception of Cd, the concentration of heavy metals were much lower than the Minimum Regulation Levels (MRLs). However, the Cd concentration exceeded the MRL in 1 of 987 swine feed samples in 2005, as well as in 4 of 1,239 swine feed samples and 1 of 778 poultry feed samples in 2006. The levels of Cu, Zn and P in swine feed were compared with the swine breeding standard. The results of this analysis revealed that the Cu concentrations in the samples exceeded the MRL for growing pigs by 0.97%, and that for finishing and breeding pigs by 9.9%. In addition, the Cu levels (80.98 ppm for piglet, 44.82 ppm for growing pigs, 19 ppm for finishing and breeding pigs) in swine feed showed higher levels compared to 3.5-6.0 ppm, which is the Cu requirement for swine. Furthermore, the results of the Zn analysis revealed that the samples exceeded the MRL for piglets, growing pigs, and finishing and breeding pigs by 5.7%, 7.7%, and 9.3%, respectively. Finally, the average concentration of P in swine feed was 0.74%, which is almost the same as the phosphate requirement for swine.

• Korean Journal of Metals and Materials
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• v.56 no.12
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• pp.861-869
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• 2018

To determine the origin of the inhomogeneous microstructure and texture observed in drawn and annealed high purity copper wires, two kinds of drawing process conditions and their influence was investigated. The regular condition, based on a symmetric die, and a condition designed intentionally to produce an inhomogeneous shear deformation using an asymmetric die were employed. The difference in intensity of <111>-<100> distributed texture between the two wires confirmed that the wire drawn under the asymmetric die condition experienced a higher amount of shear deformation. The extensive shear strain in the wire drawn under the asymmetric die condition gave rise to inhomogeneous primary and secondary recrystallization behavior. After annealing at $200^{\circ}C$, grains with <100> texture, which were larger than the surrounding recrystallized grains, were extensively present on one half circle of the wire drawn under the asymmetric die condition, while larger grains with <100> were sparsely observed around the middle region of the wire drawn under the regular condition. Interestingly, the area where the larger grains with <100> texture existed was identical to the area where the high shear strain occurred during drawing in both wires. During annealing at $400^{\circ}C$, grains with <112> texture started to grow abnormally at the center of both wires as a result of secondary recrystallization. After annealing at $900^{\circ}C$ grains with <112> due to secondary recrystallization occupied the entire region of the wire drawn under the regular condition. On the other hand, in the wire drawn under the asymmetric die condition and then annealed at $900^{\circ}C$, the <100> oriented grains as a result of the normal grain growth of the larger <100> grains which were observed after annealing at $200^{\circ}C$, coexisted with the abnormally grown <112> grains. These results indicate that dynamic recrystallization induced by the shear strain during drawing plays an important role in the inhomogeneity of the microstructure and texture of wires after annealing.

• Economic and Environmental Geology
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• v.26 no.1
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• pp.41-54
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• 1993

The Ulsan Fe-W deposit, which can be classified as a calcareous skarn deposit, is represented by ore pipe consisting principally of magnetite and lesser amounts of scheelite with minor sulphides, sulphosaits, arsenides, sulpharsenides, etc. At Ulsan mine, metasomatic processes of skarn growth may be divided broadly into two stages based on the paragenetic sequence of calc-silicate minerals and their chemical composition; early and late skarn stages. Early stage has started with the formation of highly calcic assemblages of wollastonite, diopsidic clinopyroxene and nearly pure grossular, which are followed by the formation of clinopyroxenes with salite to ferrosalite composition and grandite garnets with intermediate composition. Based on these calc-silicate assemblages, the temperatures of early skarn formations have been in the ranges of $550^{\circ}$ to $450^{\circ}$. The calc-silicate assemblages formed during the earlier half period of late skarn stage show the enrichment of notable iron and slight manganese, and the depletion of magnesium; clinopyroxenes are hedenbergitic, and grandite garnets are andraditic. The formation temperatures during this skarn stage are inferred to have been in the range of $430^{\circ}$ to $470^{\circ}C$ at low $X_{CO_2}$ by data from fluid inclusions of late andraditic garnets. The later half period of late skarn stage is characterized by the hydrous alteration of pre-existing minerals and the formation of hydrous silicates. The main iron-tungsten mineralization representing prominent deposition of magnetite immediately followed by minor scheelite impregnation has taken place at the middle of early skarn stage, while complex polymetallic mineralization has proceeded during and after the late skarn stage. Various metals and semimetals of Fe, Ni, Co, Cu, Zn, As, Mo, Ag, In, Sn, Sb, Te, Pb and Bi have been in various states such as native metal, sulphides, arsenides, sulphosaits, sulpharsenides and tellurides.

• Korean Journal of Heritage: History & Science
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• v.52 no.3
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• pp.160-171
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• 2019

The sword with a ring pommel, which was excavated from the first stone chamber of the ancient tombs of Jeongchon Village in Naju, is a sword with a pentagon undecorated ring pommel consisting of a mother sword and two child swords. The sword with an undecorated ring pommel of Jeongchon comprises a ring pommel, a hilt, a knife, and a knife end decoration. This sword was coated with lacquer. The ring pommel is an iron frame covered with silver plate; however the silver tarnished into a light purple due to silver chloride corrosion, and iron corrosion originated from the inside is visible on the surface. Silver chloride corrosion is produced when silver objects are exposed to water, dissolved salts, and dissolved chloride ions when in a buried state. It changes objects into powder, making it difficult to preserve original shapes. The other silver artifacts found in the Jeongchon ancient tombs show similar signs of corrosion. The results of X-ray irradiation and a CT analysis showed that the sword had a ring at the end of the handle, a T-shaped hilt, and was probably connected to the handle end of a knife. If the shape of the mother sword can be inferred from the child swords, the mother sword had a ring pommel, decorations of the handle, covered with silver plate, and a gold ring and a silver line wound around the handle. It is assumed that the ring pommel was connected to the knife by welding because no holes were observed. The end decoration of the knife was made by using an iron plate formed into a shape, half covered by silk, and the other half decorated with silver plate and a gold ring. The sword with an undecorated ring pommel excavated from the ancient tombs of Jeongchon Village comprises the metals of gold, silver, and iron, and includes features of Baekje, Silla, and Gaya, which highlights the influence of surrounding historic sites and various cultures.

• Journal of Microbiology and Biotechnology
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• v.17 no.8
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• pp.1242-1248
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• 2007

Genomic analysis of a hyperthermophilic archaeon, Thermococcus onnurineus NA1 [1], revealed the presence of an open reading frame consisting of 1,377 bp similar to ${\alpha}$-amylases from Thermococcales, encoding a 458-residue polypeptide containing a putative 25-residue signal peptide. The mature form of the ${\alpha}$-amylase was cloned and the recombinant enzyme was characterized. The optimum activity of the enzyme occurred at $80^{\circ}C$ and pH 5.5. The enzyme showed a liquefying activity, hydrolyzing maltooligosaccharides, amylopectin, and starch to produce mainly maltose (G2) to maltoheptaose (G7), but not pullulan and cyclodextrin. Surprisingly, the enzyme was not highly thermostable, with half-life ($t_{1/2}$) values of 10 min at $90^{\circ}C$, despite the high similarity to ${\alpha}$-amylases from Pyrococcus. Factors affecting the thermostability were considered to enhance the thermo stability. The presence of $Ca^{2+}$ seemed to be critical, significantly changing $t_{1/2}$ at $90^{\circ}C$ to 153 min by the addition of 0.5 mM $Ca^{2+}$. On the other hand, the thermostability was not enhanced by the addition of $Zn^{2+}$ or other divalent metals, irrespective of the concentration. The mutagenetic study showed that the recovery of zinc-binding residues (His175 and Cys189) enhanced the thermo stability, indicating that the residues involved in metal binding is very critical for the thermostability.

• Korean Journal of Environmental Biology
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• v.28 no.2
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• pp.101-107
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• 2010

Metal ions are essential to life. However, some metals such as mercury are harmful, even when present at trace amounts. Toxicity of mercury arises mainly from its oxidizing properties. Ionizing radiation (IR) is an active tool for destruction of cancer cells and diagnosis of diseases, etc. IR induces DNA double strand breaks in the nucleus, In addition, it causes lipid peroxidation, ceramide generation, and protein oxidation in the membrane, cytoplasm and nucleus. Yeasts have been a commonly used material in biological research. In yeasts, the physiological response to changing environmental conditions is controlled by the cell types. Growth rate, mutation and environmental conditions affect cell size and shape distributions. In this work, the effect of IR and mercury chloride (II) on the morphology of yeast cells were investigated. Saccharomyces cerevisiae cells were treated with IR, mercury chloride (II) and IR combined with mercury chloride (II). Non-treated cells were used as a control group. Morphological changes were observed by a scanning electron microscope (SEM). The half-lethal condition from the previous experimental results was used to the IR combined with mercury. Yeast cells were exposed to 400 and 800 Gy at dose rates of 400Gy $hr^{-1}$ or 800 Gy $hr^{-1}$, respectively. Yeast cells were treated with 0.05 to 0.15 mM mercury chloride (II). Oxidative stress can damage cellular membranes through a lipidic peroxidation. This effect was detected in this work, after treatment of IR and mercury chloride (II). The cell morphology was modified more at high doses of IR and high concentrations of mercury chloride(II). IR and mercury chloride (II) were of the oxidative stress. Cell morphology was modified differently according to the way of oxidative stress treatment. Moreover, morphological changes in the cell membrane were more observable in the frequently stress treated cells than the temporarily stress treated cells.

• Journal of the Korean Professional Engineers Association
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• v.19 no.1
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• pp.12-24
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• 1986

The number of visiters to Bukhan Mt. national park, generation quantity of solid waste and collection system were researched to consider a counterplan for the pollution control of the national park and study for developing the effective treatment of solid waste was tried through the proximate analysis of each component containing. Results obtained in this study were summerized as follows; The great part of visitors go on an excursion to the Bukhan Mt. national park during July and August and also, the solid waste was generated nearly a half of the total amount at the same period. The major collection facilities in the national park were waste basket and incineration box. But the incineration box was too large in volume and very far in distance, and its collection period was irregular, so it was cause to the congestion of solid waste and bad smell and dirty. Therefore, to complete collection of solid waste, we must set up the waste basket which able to find within 40～50m from the origination place of solid waste and induce the visitors to throw the solid waste. It was obtained as moisture content: 48.5 wt%, volatile solid: 28.4wt％, fixed solid: 23.1 wt％, lower heating value: 1,320kca1/kg from experimental analysis of solid waste. According to this analysis, the incineration operation is possible, but the generation quantity of solid waste was too small to construct incineration plant for heat recovery. It was found that it is suitable for the aerobic composting by mixing with the night soil which generate in the national park after the recovery of resources such as metals, glasses and plastics.

• Environmental Engineering Research
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• v.14 no.4
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• pp.226-236
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• 2009

The performance of phytoremediation has proven effective in the removal of nutrients and metals from aqueous systems. However, little information is available regarding the behavior of pesticides and their removal pathways in aquatic environments involving plant-uptake. A detailed understanding of the kinetics of pesticide removal by plants and information on compound/plant partition coefficients can lead to an effective design of the phytoremediation process for anthropogenic pesticide reduction. It was determined that the reduction rates of four organophosphorus (OP) and two organochlorine (OC) pesticides (diazinon, fenitrothion, malathion, parathion, dieldrin, hexachlorobenzene [HCB]) could be simulated by first-order reaction kinetics. The magnitude of k was dependent on the pesticide species and found within the range of 0.409 - 0.580 $d^{-1}$. Analytical results obtained by mass balances suggested that differential chemical stability, including diversity of molecular structure, half-lives, and water solubility, would greatly influence the removal mechanisms and pathways of OPs and OCs in a phytoreactor (PR). In the case of OP pesticides, plant accumulation was an important pathway for the removal of fenitrothion and parathion from water, while pesticide sorption in suspended matter (SM) was an important pathway for removal of dieldrin and HCB. The magnitude of the pesticide migration factor (${\Large M}_p^{pesticide}$) is a good indication of determining the tendency of pesticide movement from below- to above-ground biomass. The uncertainties related to the different phenomena involved in the laboratory phyto-experiment are also discussed.

• Korean Journal of Materials Research
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• v.23 no.8
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• pp.405-422
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• 2013

Atomic layer deposition(ALD) is a promising deposition method and has been studied and used in many different areas, such as displays, semiconductors, batteries, and solar cells. This method, which is based on a self-limiting growth mechanism, facilitates precise control of film thickness at an atomic level and enables deposition on large and three dimensionally complex surfaces. For instance, ALD technology is very useful for 3D and high aspect ratio structures such as dynamic random access memory(DRAM) and other non-volatile memories(NVMs). In addition, a variety of materials can be deposited using ALD, oxides, nitrides, sulfides, metals, and so on. In conventional ALD, the source and reactant are pulsed into the reaction chamber alternately, one at a time, separated by purging or evacuation periods. Thermal ALD and metal organic ALD are also used, but these have their own advantages and disadvantages. Furthermore, plasma-enhanced ALD has come into the spotlight because it has more freedom in processing conditions; it uses highly reactive radicals and ions and for a wider range of material properties than the conventional thermal ALD, which uses $H_2O$ and $O_3$ as an oxygen reactant. However, the throughput is still a challenge for a current time divided ALD system. Therefore, a new concept of ALD, fast ALD or spatial ALD, which separate half-reactions spatially, has been extensively under development. In this paper, we reviewed these various kinds of ALD equipment, possible materials using ALD, and recent ALD research applications mainly focused on materials required in microelectronics.

• Journal of the Korean Vacuum Society
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• v.15 no.5
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• pp.518-526
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• 2006

Nanoporous alumina film was fabricated by anodization of an aluminum sheet. Highly ordered nanowellstructured and nanonets-tructured metal films were fabricated by vacuum evaporation of several metals(Al, Sn, and Co) using the anodic nanoporous alumina film as a template. In this experiment, an anodic porous alumina film with the cell size of 100 nm and the pore diameter of 60 nm was used. The resistance heating method was adopted for evaporating a desired metal, and vapor deposition was carried out under the base pressure of torr. It was founded that whether the structure fabricated by vacuum evaporation is nanowell or nanonet is dependent on the amount of deposited material. When an anodic porous alumina film with the cell size of 100 nm and the pore diameter of 60 nm was used, a nanowell-structured film was fabricated when a sufficient amount of metal was suppled to cover the surface pores. On the other hand, nanonet-structured film was fabricated bellow a half the amount of metal required for nanowell-structured film.