• 대한전기학회논문지
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• 제35권1호
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• pp.17-25
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• 1986

Discussions on this paper are related to the effects of organic materials to treeing phenomena of low density polyethylene. As additives, 11 kinds of organic compounds are selected by considering the respective features such as melting point, boiling point, electron affinity as well as molecular structure, and then the specimens of low density polyethylene are prepared by blending with 10wt% of the selected additives. For the comparison of effectiveness of treeing resistance and interpretation of the mechanism of compounds as treeing retardants, several investigations such as the tree acceleration test, the prestressed test and the measurement of internally occurred partial discharge are carried out. As the results, meta-Cresol is regard as the most effective retardant among those, and it is supposed that this aromatic compound to be comprised of radical having large electron affinity has strong capability to accept energetic electron to prevent or delay the growth of discharge streamer. Furthermore, by activating partial discharge at the wall of tree pit through the function of trapped electron at this material, the gas pressure in the pit is increased up to prevent the growth of streamer.

• 암석학회지
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• 제16권4호
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• pp.196-207
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• 2007

강원도 고성지역에는 여러 종류의 포획암과 포획결정을 내포한 마이오세 현무암들이 화산전(volcanic plug) 형태를 이루며 분포한다. 이들 화산전중에서 운봉산화산전의 근원마그마는 지하 160km 깊이에서 형성되어 지표로 올라왔다. 전암화학분석, 구성광물의 평형온도 및 압력은 운봉산화산전을 형성한 화산암이 알칼리현무암이며, 결핍된 석류석 페리도타이트의 $0.2{\sim}2%$의 부분용융에 의하여 형성되었음을 지시한다. 이 마그마는 감람석, 단사휘석, 사장석을 각각 $75{\sim}110km,\;40{\sim}52km,\;37{\sim}54km$ 깊이에서 정출하였으며, 맨틀포획암인 스피넬 페리도타이트를 지하 $57{\sim}67km$에서 포획하여 지표에 빠른 속도로 올라왔다.

• Progress in Superconductivity
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• 제6권2호
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• pp.129-132
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• 2005

The formation behavior of $YBa_2Cu_3O_{7-x}$(Y123) and CuO phases in the heat-treated Cu-sheathed YBCO thick films was studied. The thick films were prepared by screen-printing method using $BaCO_3$ and Y211 powders on Cu tapes. The screen-printed thick films were placed at the center of the tube furnace, heated to $930^{\circ}C$ in air atmosphere and then maintained at the temperature for 60 sec - 300 sec. The microstructure and phases formed in the thick films were investigated by using optical microscope, X-ray diffraction (XRD) and SEM image analysis. During the heat treatment, partial melting occurred rapidly in the printed layers by peritectic reaction between CuO and precursor powders, and then YBCO superconducting phases nucleated from the Cu tapes and grew in a form of thick films.

• 자원환경지질
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• 제17권2호
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• pp.109-114
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• 1984

The geophysical implications of the observed heat flow in the Korean Peninsula are examined. The Peninsula can be devided into two typical regions of high (Zone 1) and normal heat flows (Zone 2), and anomalous sharp change of heat flow between two zones is noteworthy. Zone 1 (southeastern coast of the Peninsula) to be connected to the East Sea (=Japan Sea) of high heat flow region corresponds with the region of late-Mesozoic to Tertiary igneous activity. With the radioactive elements concentrated in the crust, the observed heat flow in Zone 2 can be almostly explained. While, only a half of the heat flow in Zone 1 is explained. As a possible explanation of high heat flow in Zone 1, partial melting in the lower crust is examined. The temperature of $800-900^{\circ}C$ calculated at the bottom of the crust excludes the possibility of partial melting or magma generation in the crust. Alternatively, a remaining thermal effect of late-Mesozoic to Tertiary igneous activity is considered. However, it appears that the thermal effect already disappeared and that the vertical temperature distribution reached at steady state 30 MY ago (= 10 MY after the igneous activities came to an end). After all, the existence of some other effective heat transfer in Zone 1 is strongly suggested. The high heat flow to be same kind of anomalous one of the East Sea can be recognized as a result of the trench-back-arc thermal flux. The plate subduction in the Japan Trench will generate an induced flow above the slab of the East Sea, a typical back-arc basin, and hence the induced flow will heat the surrounding lithosphere.

• 자원환경지질
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• 제33권4호
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• pp.249-260
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• 2000

한국 남부에서 섭입 해구의 방향과 나란히 쌍으로 발달한 화산대가 발견된다. 경상분지와 영동-광주 함몰대의 화산암류는 거의 나란한 양상을 보이며, 이들은 각각 동일한 섭입 체계에 따르는 첫 번째 화산대, 두 번째 화산대이다. 경상분지와 영동-광주 함몰대 화산암류의 불호정성 원소 함량은 호를 가로지르는 변화를 뚜렷하게 보인다. 즉, 첫 번째 화산대 (경상분지 및 남해안 도서지역)용암들의 불호정성 원소 함량은 두 번째 화산대 (영동-광주 함몰대)에 비해 더욱 결핍되며 두 번째 화산대에서 더욱 증가하는 경향을 보인다. 이와 같이 호를 가로지르는 변화를 보이는 것은, 탈수과정 동안 유체상과 공존하는 고체상의 차이에 기인한 것으로 보인다. 두 번째 화산대의 불호정성 원소의 함량, Zr/Y 비, Rb/K 비는 첫 번째 화산대에 비해 더 깊은 깊이에서 더 적은 정도의 부분 용융, 그리고 용융 과정에서의 잔류 석류석에 기인할 것이다.

• 암석학회지
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• 제3권1호
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• pp.49-75
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• 1994

홍젠사화강암질암체는 구성광물의 함량과 조직의 특징에 따라 크게 흑운몬화강암질편마암과 미사장석-퍼어사이트화강암질편마암으로 구성되어 있으며 이들은 서로 점이적으로 변화하는 양상을 보이고 있다. 이들을 이루는 주구성광물은 흑운모, 백운모, 녹니석, 사장석, 미사장석, 퍼어사이트 및 석영 등이며 국부적으로 규선석, 석류석 그리고 전기석이 산출된다. 이들 광물들의 교대 및 공존 관계 등으로 볼 때 이 편마암류들은 상부앰피볼라이트의 광역변성작용, 이에 수반된 부분용융에 의한 화강암화작용, 그리고 다시 녹염석-앰피볼라이트 내지 녹색편암상에 해당되는 광역변성작용을 받아 형성된 것으로 생각된다. 이러한 변성작용 중에 생성된 흑운모, 백운모 및 녹니석의 화학조성은 암상이나 생성시기에 관계없이 각각 거의 비슷하며 공존하는 광물들 사이의 화학적 평형관계도 거의 안정되어 있다. 화강암질편마암체를 형성시킨 화강암화작용은 광역변성작용에 수반된 부분용융에 의하여 일어난 것으로 생각되며 이것은 비교적 오랜 기간에 걸쳐 광범위한 지역에서 안정되게 진행되었을 것으로 생각된다.

• 한국세라믹학회지
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• 제33권4호
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• pp.405-410
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• 1996

The partial substitution of LiTaO3 with Al2O3 caused the variation of dielectric properties and a lower melting temperature yielding an easier growth of single crystal. The lattice constants and Raman band broadening were measured for the LiTaO3 solid solution in which the cations of Li+ and Ta5+ were partially substituted by Al3+ cation. The LiTaO3 type limit phases were obtained. ; Li1.15Al0.45Ta0.7O3 for cationic excess Li1.15Al0.45Ta0.7O3 for stoichiometry Li0.85Al0.05TaO3 for cationic deficit. The second phase was formed beyond the solubility limit. The limit phase (Li0.85Al0.05TaO3) in the region of cationic deficit showed the lowest Cuire temperature of 61$0^{\circ}C$ and melting point of 152$0^{\circ}C$ compared to the solid solutions in other regions (TMp=1$650^{\circ}C$, Tc=69$0^{\circ}C$ for LiTaO3)

• 열처리공학회지
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• 제25권3호
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• pp.126-133
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• 2012

Semi-solid forming of the high melting point alloys such as steel is a promising near-net shape forming process for decreasing manufacturing costs and increasing the quality of the final products. This paper presents the microstructure characteristics of SKH51 (high speed tool steel) during heating and holding in the mushy zone between $1233^{\circ}C$ and $1453^{\circ}C$, which has been measured by differential scanning calorimetry (DSC). The results of heating/holding experiments showed that the grain size and the liquid fraction increased gradually with temperature up to $1350^{\circ}C$. The drastic grain growth occurred at heating above $1380^{\circ}C$. The strain-induced melt-activated (SIMA) process has been applied to obtain globular grains in the billet materials. Working by mechanical upsetting and successive heating of SKH51 into the temperatures in the mushy zone resulted in globular grains due to recrystallization and partial melting.

• Advances in nano research
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• 제16권4호
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• pp.325-340
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• 2024

There are several novel uses for dispersing many nanoparticles into a conventional fluid, including dynamic sealing, damping, heat dissipation, microfluidics, and more. Therefore, melting heat and mass transfer characteristics of a 3-D MHD Hybrid Nanofluid flow over a rotating disc with presenting dufour and soret effects are assessed numerically in this study. In this instance, we investigated both ferric sulfate and molybdenum disulfide as nanoparticles suspended within base fluid water. The governing partial differential equations are transformed into linked higher-order non-linear ordinary differential equations by the local similarity transformation. The collection of these deduced equations is then resolved using a Chebyshev spectral collocation-based algorithm built into the Mathematica software. To demonstrate how different instances of hybrid/ nanofluid are impacted by changes in temperature, velocity, and the distribution of nanoparticle concentration, examples of graphical and numerical data are given. For many values of the material parameters, the computational findings are shown. Simulations conducted for different physical parameters in the model show that adding hybrid nanoparticle to the fluid mixture increases heat transfer in comparison to simple nanofluids. It has been identified that hybrid nanoparticles, as opposed to single-type nanoparticles, need to be taken into consideration to create an effective thermal system. Furthermore, porosity lowers the velocities of simple and hybrid nanofluids in both cases. Additionally, results show that the drag force from skin friction causes the nanoparticle fluid to travel more slowly than the hybrid nanoparticle fluid. The findings also demonstrate that suction factors like magnetic and porosity parameters, as well as nanoparticles, raise the skin friction coefficient. Furthermore, It indicates that the outcomes from different flow scenarios correlate and are in strong agreement with the findings from the published literature. Bar chart depictions are altered by changes in flow rates. Moreover, the results confirm doctors' views to prescribe hybrid nanoparticle and particle nanoparticle contents for achalasia patients and also those who suffer from esophageal stricture and tumors. The results of this study can also be applied to the energy generated by the melting disc surface, which has a variety of industrial uses. These include, but are not limited to, the preparation of semiconductor materials, the solidification of magma, the melting of permafrost, and the refreezing of frozen land.

• 대한심미치과학회지
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• 제3권1호
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• pp.32-43
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• 1995

Ni-Ti alloy has excellent corrosion resistance, biocompatibility, shape memory effect and superelasticity, so it has been used widely in biomedical fields. But it has difficulty in casting due to its high melting temperature and oxygen affinity at high temperature. Recently it has been attempted to cast Ni-Ti alloy using new casting machine and investment. The purpose of this study was to examine the superelastic behavior of cast shape memory Ni-Ti alloy and to compare the mechanical properties of the cast shape memory alloy with those of commercial alloys for removable partial denture framework. Ni-Ti alloy(Ni 50.25%, Ti 49.75% : atomic ratio) was cast with dental argon-arc pressure casting machine and Type IV gold alloy, Co-Cr alloy, Ni-Cr alloy, pure titanium were cast as reference. Experimental cast Ni-Ti alloy was treated with heat($500{\pm}2^{\circ}C$) in muffle furnace for 1 hour. Transformation temperature range of cast Ni-Ti alloy was measured with differential scanning calorimetry. The superelastic behavior and mechanical properties of cat Ni-Ti alloy were observed and evaluated by three point bending test, ultimate tensile test, Vickers microhardness test and scanning electron microscope. The results were as follows : 1. Cast Ni-Ti alloy(Ni 50.25%, Ti 49.75% : atomic ratio) was found to have superelastic behavior. 2. Stiffness of cast Ni-Ti alloy was considerably lesser than that of commercial alloys for removable partial denture. 3. Permanent deformation was observed in commercial alloys for removable partial denture framework at three point bending test over proportional limit(1.5mm deflection), but was not nearly observed in cast Ni-Ti alloy. 4. On the mechanical properties of ultimate tensile strength, elongation and Vickers microhardness number, cast Ni-Ti alloy was similiar to Type IV gold alloy, Co-Cr alloy, Ni-Cr alloy and pure titanium. With these results, cast Ni-Ti alloy had superelastic behavior and low stiffness. Therefore, it is suggested that cast Ni-Ti alloy may be applicated to base metal alloy for removable partial denture framework.