• Tuberculosis and Respiratory Diseases
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• v.79 no.3
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• pp.184-187
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• 2016

Since IgG4-related pancreatitis was first reported in 2001, IgG4-related disease has been identified in other organs such as salivary gland, gallbladder, thyroid, retroperitoneum and kidney; but lung invasion is rare. A 63-year-old man presented with hemoptysis at the pulmonary clinic and chest computed tomography revealed about 4.1 cm irregular shaped mass with spiculated margin at the left upper lobe. Despite no elevation of serum IgG4 level, he was finally diagnosed as IgG4-related lung disease by transthoracic needle biopsy. After treatment with oral glucocorticoids, hemoptysis disappeared and the size of lung mass was decreased.

• Journal of the Korean Ceramic Society
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• v.41 no.3
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• pp.202-209
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• 2004

Hydroxyapatite(HA)/TiO$_2$ composite powders were prepared by mixing of spherical TiO$_2$ (10-15 nm, 500 nm) and needle-shaped HA (50-70 nm, 120-250 nm) powders which had been synthesized through precipitation, sol-gel and hydrothermal methods. From the three types of starting composite powders (HA/TiO$_2$ wt% of 75/25, 50/50, and 25/75), dense $\beta$-TCP/TiO$_2$ composites were prepared by hot-pressing at 800-100$0^{\circ}C$ for 30 min under the pressure of 30 ㎫ in Af atmosphere. The $\beta$-TCP/TiO$_2$ composites showed different microstructures and sintering densities depending on their powder morphology, composition and sintering temperature. With increasing the sintering temperature and the content of TiO$_2$, sintered density was increased and microstructure became more homogeneous.

• Korean Journal of Materials Research
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• v.27 no.10
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• pp.563-568
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• 2017

In this study, the coating of an Al-Cr layer on the surface of a Zircaloy-4 alloy was carried out through plasma pretreatment coating and a laser surface melting process. Two different conditions for laser treatment, severe or minimal surface melting of the Zr alloy substrate, were applied to form the final coating. When there was significant surface melting of the Zr alloy, the solidification microstructure of the newly formed coating layer was mainly composed of needle-shaped $Al_3Zr$, Al(Cr) and $Al_7Cr$ phases. On the other hand, the solidification microstructure of the coating layer was mainly composed of Al(Cr) and $Al_7Cr$ phases when there was minimal surface melting of Zr base in the laser process. However, when the coating was maintained at $1100^{\circ}C$ for 2 hours, significant inter-diffusion occurred between the phases in the coating. As a result, the upper part of the coating layer was observed to mainly consist of $Al_3Zr$ and $Al_8Cr_5$ phases, regardless of the laser treatment conditions.

• Journal of the Mineralogical Society of Korea
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• v.19 no.2 s.48
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• pp.63-69
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• 2006

When rocks are exposed to the near surface environment, they are broken down due to several factors such as physical and chemical weathering during the geologic time. The feldspar and mica, which are the main rock-forming minerals, are easily broken down relative to other minerals. In order to reproduce some weathered minerals similar to the ones exist in natural weathered granite, there was an experimental interaction between fresh minerals and acidic solution. In low pH condition, biotite initially dissolved and its surface structure broke down, whereas plagioclase dissolved and had a needle-shaped dissolved morphology with some precipitates composed of Al element. The minerals were deeply dissolved in a strong acid condition, showing the prominent dissolved structure. Some etch pits and dissolved textures developed on the natural mineral surfaces are similarly found in our experiment, suggesting the development of mineral dissolution and weathering texture by the influence of the mineral's intrinsic nature.

• Journal of Korea Foundry Society
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• v.33 no.5
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• pp.215-225
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• 2013

The alloys required for fossil power plants are altered from stainless steel that has been used below $600^{\circ}C$ to Ni-based alloys that can operate at $700^{\circ}C$ for Hyper Super Critical (HSC) steam turbine. The IN740 alloy (Special Metals Co. USA) is proposed for improved rupture strength and corrosion resistance at high temperature. However, previous studies with experiments and simulations on stable phases at about $700^{\circ}C$ indicated the formation of the eta phase with the wasting of a gamma prime phase, which is the most important reinforced phase in precipitation hardened Ni alloys, and this resulted in the formation of precipitation free zones to decrease the strength. On the basis of thermodynamic calculation, the new Ni-based superalloy named LESS 1 (Low Eta Sigma Superalloy) was designed in this study to improve the strengthening effect and structure stability by depressing the formation of topologically close packed phases, especially sigma and eta phases at high temperature. A thermal exposure test was carried out to determine the microstructure stability of LESS 1 in comparison with IN740 at $800^{\circ}C$ for 300 hrs. The experimental results show that a needle-shaped eta phase was formed in the grin boundary and it grew to intragrain, and a precipitation free zone was also observed in IN740, but these defects were entirely controlled in LESS 1.

• Journal of Conservation Science
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• v.33 no.3
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• pp.167-179
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• 2017

In this study, Sangpyeontongbo excavated at Bigyeongdo, Seosan, were investigated to determine the components of the corrosion products that were formed while they were buried underwater in an anaerobic environment. The causes of corrosion product formation were also determined. Microstructure observation, element mapping, principle component analysis for each year, and the detection of corrosion products were carried out. Results indicate that the concretions of corrosion products on the surface are needle-, hexahedral-, and octahedral-shaped; Pb, Cu, and S were among the elements detected. The Cu-S layer was clearly verified using element mapping. An analysis of major elements for each layer showed that Cu, S, and Pb were present and that most Zn was eliminated. The corrosion products detected were $PbCO_3$ (concretion) and $Cu_{1.96}S$ (metal). Accordingly, the anaerobic corrosion properties of Sangpyeongtongbo are summarized as follows: dezincification, copper sulfide, and lead compound.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.11 s.242
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• pp.1229-1238
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• 2005

The objective of the present study was to investigate the efficacy of physical water treatment (PWT) technologies using different catalytic materials and an electronic anti-fouling device in the mitigation of mineral fouling in a once-through flow system with mini-channel heat exchanger. Effects of flow velocity and water hardness on the effectiveness of PWT technologies were experimentally studied. The artificial water hardness varied from 5.0 to 10 mo1/m$^{3}$ as CaCO$_{3}$. For 10 mo1/m$^{3}$ solution, fouling resistance reduced by 13-40$\%$ depending on flow velocity and types of PWT devices. On the other hand, fouling resistance reduced by 21-29$\%$ depending on the PWT devices for 5 mo11m3 solutions. The PWT device using alloy of Cu and Zn as catalyst (CM2) was slightly more effective than the others. SEM photographs of scale produced from the 10 mol/m$^{3}$ solution at 1.0 m/s indicated that calcium carbonate scales without PWT devices were needle-shaped aragonite, which is sticky, dense and difficult to remove. Scales with the PWT devices showed a cluster of spherical or elliptic shape crystals. Both the heat transfer test results and SEM photographs strongly support the efficacy of PWT technologies using catalytic materials and an electronic anti-fouling device in the mitigation of mineral fouling.

• The Korean Journal of Mycology
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• v.13 no.2
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• pp.105-109
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• 1985

Isolates of the different species groups of Trichoderma from the mushroom culture beds were identified according to Rifai's classification and influence of antibiotics produced by them against the oyster mushroom was examined. Trichoderma islolates were identified as Trichoderma hamatum, Trichoderma viride and Trichoderma koningii. Among the Trichoderma isolates, fungistatic action of Trichoderma viride was found to be most remarkable. Pleurotus ostreatus and Pleurotus sajor-caju were the most susceptable of the edible mushrooms tested, followed by Lentinus edodes, Flammulina velutipes and Auricularia auricula. A needle-shaped crystal gained from the chloroform extract of the culture filtrate of Trichoderma viride repressed distinctively the mycelial growth of the oyster mushroom. The grade of repression of the crystal at 500ppm and 1/10 aequ­ous solution of the chloroform extract against the oyster mushroom, seemed equal to that of cycloheximide at $100{\sim}200ppm$.

• Journal of Korea Foundry Society
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• v.36 no.5
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• pp.167-173
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• 2016

The effect of various types of heat-treatment on the mechanical properties of cast Alloy 718 has been investigated. Cast Alloy 718 bars were subjected to 'standard heat-treatment'_(SHT), 'HIP (Hot Isostatic Pressing) heat-treatment'_(HHT), and 'HIP-simulated heat-treatment'_(HS). In the absence of long time high temperature heat-treatment, a small amount of Laves phase remained in the 'SHT' specimen, and needle shaped ${\delta}$ precipitated in the vicinity of the Laves phase. Due to the formation of the Laves and ${\delta}$ phases in the 'SHT' specimen, it exhibited lower tensile properties than those of the others_specimens. On the other hand, the Laves phase was completely dissolved into the matrix after 'HHT' and 'HS' treatments. It is known that isostatic pressure reduces the self-diffusion coefficient, because of the lower self-diffusivity under HIP conditions in the interdendritic region, Nb segregation and the high amount of ${\gamma}^{{\prime}{\prime}}$ precipitation that occurs. Due to the higher fraction of coarse ${\gamma}^{{\prime}{\prime}}$ phases, the 'HHT' treated Alloy 718 showed excellent tensile strength.

• Journal of Korea Foundry Society
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• v.38 no.2
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• pp.32-40
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• 2018

Changes in the microstructures and mechanical properties of an AC2B alloy through solution heat treatment were investigated using recycled AC2B cutting chips as raw material. The as-cast microstructure of the AC2B alloy comprised ${\alpha}$-Al, $Al_2Cu$, and coarse needle-shaped phases considered to be eutectic Si and an Al-Fe-Si based intermetallic compound. After solution heat treatments at $505^{\circ}C$ for 1 h and 6 h, the samples showed complete dissolution of $Al_2Cu$ and relatively fine distribution of intermetallic compounds. Hardness test results showed that the hardness rapidly increased after the solution heat treatment for 1 h by solid solution hardening, and the increase of hardness exhibited a plateau from 1 h to 6 h. The results of the hardness and tensile tests showed that there was no visible difference in the effect of 1 h and 6 h solid solution treatment.