• Journal of the Korean Society for Heat Treatment
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• v.17 no.6
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• pp.356-364
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• 2004

The hydrides in cladding affect the corrosion and tensile properties. In this study corrosion and tensile properties were evaluated with varying the hydrogen concentration. The charged hydrogen contents were ranged from 200 to 1000 ppm. The corrosion rate in water and LiOH solution increases with the hydrogen concentration. The hydride did not affect the corrosion mechanism in the pre-transition region, but in the post-transition region the corrosion rate was accelerated. Cladding E contained higher Niobium content was slowly accelerated compared with other claddings. The yield and ultimate strengths were independent on the hydrogen content. However, the total elongation decreased gradually with increasing the hydrogen content. SEM observation of fracture surface showed that an average of depth of voids decreased with increasing the hydrogen content and small secondary crack are observed.

• Journal of Powder Materials
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• v.25 no.5
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• pp.395-401
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• 2018

The improvement of dispersion stability for the primary polishing slurry in a CMP process is achieved to prevent defects produced by agglomeration of the slurry. The dispersion properties are analyzed according to the physical characteristics of each silica sol sample. Further, the difference in the dispersion stability is confirmed as the surfactant content. The dispersibility results measured by Zeta potential suggest that the dispersion properties depend on the content and size of the abrasive in the primary polishing slurry. Moreover, the optimum ratio for high dispersion stability is confirmed as the addition content of the surfactant. Based on the aforementioned results, the long-term stability of each slurry is analyzed. Turbiscan analysis demonstrates that the agglomeration occurs depending on the increasing amount of surfactant. As a result, we demonstrate that the increased particle size and the decreased content of silica improve the dispersion stability and long-term stability.

• Bulletin of the Korean Chemical Society
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• v.27 no.10
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• pp.1641-1647
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• 2006

Vibrational relaxation and competitive C-$H_{methyl}$ and C-$H_{ring}$ bond dissociations in vibrationally excited methylpyrazine in the collision with HF have been studied by use of classical trajectory procedures. The energy lost by the vibrationally excited methylpyrazine upon collision is not large and it increases slowly with increasing total vibrational energy content between 20,000 and 45,000 $cm^{-1}$. Above the energy content of 45,000 $cm^{-1}$, however, energy loss decreases. The temperature dependence of energy loss is negligible between 200 and 400 K, but above 45,000 $cm^{-1}$ the energy loss increases as the temperature is raised. Energy transfer to or from the excited methyl C-H bond occurs in strong collisions with HF, that is, relatively large amount of translational energy is transferred in a single step. On the other hand, energy transfer to the ring C-H bond occurs in a series of small steps. When the total energy content ET of methylpyrazine is sufficiently high, either or both C-H bonds can dissociate. The C-$H_{methyl}$ dissociation probability is higher than the C-$H_{ring}$ dissociation probability. The dissociation of the ring C-H bond is not the result of the direct intermolecular energy flow from the direct collision between the ring C-H and HF but the result of the intramolecular flow of energy from the methyl group to the ring C-H stretch.

• Journal of Korea Foresty Energy
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• v.25 no.1
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• pp.24-30
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• 2006

This study was conducted to understand the biomass and the energy content of 48-year-old Pinus densiflora stand planted in Mt. Wolak, Jecheon-si, Chungcheongbuk-do, Korea. The total biomass of aboveground was 138.14 ton/ha (87.3 ton/ha from stemwood, 41.43 ton/ha from live brances, and 9.41 ton/ha from leaves). Annual net production (ANP) of aboveground was 10.85 ton/ha/yr, and the ANP of stemwood, live branches, and leaves were 5.3 ton/ha/yr, 2.93 ton/ha/yr, and 2.62 ton/ha/yr, respectively. Energy content of aboveground was 2,981 GJ/ha, and annual energy accumulation was 239 GJ/ha/yr. The leaf area index (LAI) of P. densiflora stand was 6.58.

• Journal of Korea Foresty Energy
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• v.25 no.1
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• pp.39-45
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• 2006

This study was conducted to understand the biomass and the energy content of 36-year-old Pinus rigida stand planted in Mt. Taehwa, Gwangju-si, Gyeonggi-do, Korea. The total biomass of aboveground was 252.0 ton/ha (65.9% from stemwood, 8.9% from stembark, 20.6% from live branches, 1.5% from current leaves, 2.6% from previous leaves, and 0.5% from cones). Annual net production (ANP) of aboveground was 27.4 ton/ha/yr, and the ratio of stemwood, stembark, live branches, current leaves, and cones to ANP of aboveground total, 56.3%, 6.1%, 19.1%, 13.9%, and 4.6%, respectively. Energy content of aboveground was 5,434 GJ/ha, and annual energy accumulation was 597 GJ/ha/yr. Photosynthetic layer of P. rigida was shown at about 5.2 m in height, and maximum needle amount of crown at 11 to 13 m in height.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.6
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• pp.845-852
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• 2008

The goal of this study was to determine whether galanin affects the mean plasma concentrations of metabolic parameters such as thyroxine (T4), triiodothyronine (T3), growth hormone (GH), insulin, glucagon, glucose, fatty acid and urea in goats fed diets differing in energy content. Sixteen goats were randomly divided into 4 groups. Animals in groups 1 and 2 were fed 100% and animals in groups 3 and 4 were fed 50% energy content in the diet for 20 days. After 20 days, animals in groups 1 and 3 received a daily infusion of $1{\mu}g$ galanin and groups 2 and 4 received a daily infusion of $2{\mu}g$ galanin into their third ventricle for 5 days. Blood samples were collected daily from the jugular vein before infusion on day 4 until 4 days after the last infusion of galanin. Samples were assayed for plasma T3, T4, GH, insulin and glucagon concentrations by double-antibody RIA. Glucose, fatty acid and urea concentrations were also measured. Lower dietary energy intake and infusions of 1 and $2{\mu}g$ galanin significantly (p<0.01) decreased the mean plasma concentrations of T3, T4, insulin and glucose and significantly (p<0.01) increased the mean plasma concentrations of GH, glucagon, fatty acid and urea of the animals in groups 3 and 4. Different dosages of the galanin infusions did not change the plasma concentrations of the metabolic parameters in the animals fed a normal dietary energy content. The results of this experiment indicated that galanin may negatively affect T3, T4, insulin and glucose and increase GH, glucagon, fatty acid and urea in goats with negative energy balance, but not in those with positive energy balance.

• Korean Journal of Environmental Agriculture
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• v.24 no.1
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• pp.61-65
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• 2005

This study was to evaluate whether ionizing gamma radiation could be applied to break the dormancy of a potato minituber. The respiration rate of the minitubers was significantly affected by the storage temperature and a low dose gamma radiation. Ionizing radiation of 8 Gy enhanced the respiration rate of the potato tuber stored at $10^{\circ}C$ for 20 days. The potato tuber subjected to 4 and 8 Gy after 40 days storage at 10 and $20^{\circ}C$ exhibited higher respiration rates compared to the control (non-irradiated), but not at st. However, the ionizing radiation did not exhibit on significant effect on the respiration rate of the potato tuber stored for 60 days. It was observed that minitubers stored for 20 days had significant response to the storage temperature in terms of the total sugar content the higher the storage temperature, the lower the total sugar content. It was measured that the reducing sugar content was increased under the storage conditions both 5 and $10^{\circ}C$ for 40 days, but not to $20^{\circ}C$. The total sugar contents in the minituber stored for 60 days were similar to those stored for 40 days. The data was discussed on the relationships among the storage duration, temperature and ionizing radiation.

• Journal of the Korean Wood Science and Technology
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• v.34 no.4
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• pp.66-75
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• 2006

This study was conducted to understand the biomass and the energy content of 24-year-old Pinus koraiensis stand planted in Mt. Wolak, Chungcheongbuk-do, Korea. Nine sample trees were selected and harvested for the study. Stem, bark, branches and leaves were weighed respectively with the stratified clipping method, and analyzed for productive structure. The allometric regression equations between dry weight of each component and $D^2H$ were obtained to estimate the total biomass of aboveground (47.0 ton/ha) and other parts (56.5% from stemwood, 9.1% from stembark, 0.5% from current twigs, 18.4% from live branches, 2.6% from current leaves, and 12.9% from previous leaves). Annual net production of aboveground was 6.0 ton/ha/yr, and the ratios of stemwood, stembark, current twigs, live branches, and current leaves to that of aboveground were 49.8%, 7.3%, 3.5%, 18.6%, and 20.8%, respectively. Energy content of aboveground was 1,028 GJ/ha, and annual energy content was 133 GJ/ha/yr. Leaf area index (LAI) of P. koraiensis plantation was 20.2 in Mt. Wolak.

• Nuclear Engineering and Technology
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• v.49 no.3
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• pp.549-555
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• 2017

A lead slowing-down spectrometer (LSDS) system is under development to analyze isotopic fissile content that is applicable to spent fuel and recycled material. The source neutron mechanism for efficient and effective generation was also determined. The source neutron interacts with a lead medium and produces continuous neutron energy, and this energy generates dominant fission at each fissile, below the unresolved resonance region. From the relationship between the induced fissile fission and the fast fission neutron detection, a mathematical assay model for an isotopic fissile material was set up. The assay model can be expanded for all fissile materials. The correction factor for self-shielding was defined in the fuel assay area. The corrected fission signature provides well-defined fission properties with an increase in the fissile content. The assay procedure was also established. The assay energy range is very important to take into account the prominent fission structure of each fissile material. Fission detection occurred according to the change of the Pu239 weight percent (wt%), but the content of U235 and Pu241 was fixed at 1 wt%. The assay result was obtained with 2~3% uncertainty for Pu239, depending on the amount of Pu239 in the fuel. The results show that LSDS is a very powerful technique to assay the isotopic fissile content in spent fuel and recycled materials for the reuse of fissile materials. Additionally, a LSDS is applicable during the optimum design of spent fuel storage facilities and their management. The isotopic fissile content assay will increase the transparency and credibility of spent fuel storage.

• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.3
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• pp.81-91
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• 1989

The aims of this study were to determine mechanical properties of steel-fiber reinforced concrete under splitting tensile, flexural and compressive loading, and thus to improve the possible applications of concrete. The major factors experimentally investigated in this study were the fiber content and the length and the diameter of fibers. The major results obtained are summarized as follows : 1.The strength, strain, elastic modulus and energy obsorption capability of steel-fiber reinforced concrete under splitting tensile loading were significantly improved by increasing the fiber content or the aspect ratio. 2.The flexural strength, central deflection, and flexural toughness of steel4iber reinforced beams were significantly improved by increasing the fiber content or the aspect ratio. And flexural behavior characteristic was good at the aspect ratio of about 60 to 75. 3.The strength, strain, and energy absorption capability in compression were increased with the increase of the fiber content. These effects were not so sensitive to the aspect ratio. The energy absorption capability was improved only slightly with the increase of the fiber length. 4.The elastic modulus, transverse strains, and poisson's ratios in compression were not influenced by the fiber content. 5.The steel-fibers were considered to be appropriated as the materials covering the weakness of concrete because the mechanical properties of concrete in tension and flexure were significantly improved by steel-fiber reinforcement.