• 한국세라믹학회지
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• 제47권6호
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• pp.509-514
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• 2010

Porous mullite-bonded SiC (MBSC) ceramics were fabricated at temperatures ranging from 1400 to $1500^{\circ}C$ for 2 h using silicon carbide (SiC), alumina ($Al_2O_3$), strontium oxide (SrO), and poly (methyl methacrylate-coethylene glycol dimethacrylate) (PMMA) microbeads. The effect of template content on porosity, pore morphology, and flexural strength were investigated. The porosity increased with increasing the template content at the same sintering temperature. The flexural strength showed maximum after sintering at $1450^{\circ}C$/2 h for all specimens due to small pores and dense strut. By controlling the template content and sintering temperature, it was possible to produce porous MBSC ceramics with porosities ranging from 30% to 54%. A maximum flexural strength of ~51MPa was obtained at 30% porosity when no template were used and specimens sintered at $1450^{\circ}C$/2 h.

• 열처리공학회지
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• 제17권6호
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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.

• 한국분말재료학회지
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• 제25권5호
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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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• 제27권10호
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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.

• 임산에너지
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• 제25권1호
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• pp.24-30
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• 2006

충북 월악산 동사면(해발 300m)에서 48년생 소나무 천연림의 바이오매스와 연간 순생산량을 추정한 결과, 소나무림의 바이오매스는 줄기부 87.3 ton/ha, 가지부 41.43 ton/ha, 잎 9.41 ton/ha로서 지상부 전체가 138.14 ton/ha로 추정되었으며, 연간 순생산량은 줄기부 5.3 ton/ha/yr, 가지부 2.93 ton/ha/yr, 잎 2.62 ton/ha/yr로서 지상부 전체 10.85 ton/ha/yr로 추정되었다. 또한 소나무림 지상부의 에너지량은 2,981 GJ/ha, 연간 에너지 고정량은 239 GJ/ha/yr로 나타났다. 한편, 월악산 지역 소나무림의 엽면적지수는 6.58로 나타났다.

• 임산에너지
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• 제25권1호
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• pp.39-45
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• 2006

경기 태화산 북서사면(해발 250m) 36년생 리기다소나무림의 바이오매스는 수간 목부 166.1ton/ha, 수간 수피부 22.4ton/ha, 가지 51.9ton/ha, 고사지 16.0ton/ha, 당년생 잎 3.8ton/ha, 전년생 잎 6.6ton/ha, 구과 1.3ton/ha로서 지상부 252.0ton/ha로 나타났다. 또한 연간 순생산량은 수간 목부 15.4ton/ha/yr, 수피 1.7ton/ha/yr, 가지 5.2ton/ha/yr, 당년생 잎 3.8ton/ha/yr, 구과 1.3ton/ha/yr, 지상부 27.4ton/ha/yr로 추정되었다. 리기다소나무림 지상부의 에너지량은 5,434GJ/ha, 연간 에너지 고정량은 597GJ/ha/yr로 나타났다. 리기다소나무림의 광합성부는 지상 5.2m부터 시작되고 최대 광합성부는 지상 11-13m 사이의 높이에 나타났다.

• Asian-Australasian Journal of Animal Sciences
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• 제21권6호
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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.

• 한국환경농학회지
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• 제24권1호
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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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• 제34권4호
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• pp.66-75
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• 2006

충북 월악산 북동 사면 지역(해발 380 m)에서 24년생 잣나무 인공림의 바이오매스와 에너지량을 조사한 결과, 잣나무림의 바이오매스는 줄기부 26.6 ton/ha, 수피부 4.3 ton/ha, 1년생 가지 0.2 ton/ha, 가지부 8.6 ton/ha, 고사지 1.5 ton/ha, 당년생 잎 1.3 ton/ha, 전년생 잎 6.1 ton/ha로서 고사지를 제외한 지상부 전체는 47.0 ton/ha으로 나타났다. 또한 연간 순생산량은 줄기부 3.0 ton/ha/yr, 수피부 0.4 ton/ha/yr, 1년생 가지 0.2 ton/ha/yr, 가지부 1.1 ton/ha/yr, 당년생 잎 1.3 ton/ha/yr이며, 지상부 합계는 6.0 ton/ha/yr로 추정되었다. 이것을 열 에너지량으로 환산하면 지상부 전체의 에너지량은 1,028 GJ/ha, 연간 에너지 고정량(지상부)은 133 GJ/ha/yr로 나타났다. 한편, 잣나무림의 엽면적 지수는 20.2로 나타났다.

• Nuclear Engineering and Technology
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• 제49권3호
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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.