• Korean Journal of Materials Research
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• v.17 no.6
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• pp.293-297
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• 2007

Microstructure and tensile strength of the vacuum brazed stainless steel(STS303) and Cu were investigated. For brazing, the BNi-2, 3, 4, 6 and 7 (A.W.S standard) were used as filler metals. The Oxides such as $Cr_2O_3$ and $SiO_2$ were observed at brazed layers between STS303 and Cu matrix. Also, the intermetallic compounds of Cr-B and Ni-P were observed at brazed layers. Brazed STS303-Cu specimens with BNi-2, 3, 4 filler metals showed almost elastic deformation followed by plastic yielding and strain hardening up to a peak stress. On the other hand, it is likely that the fracture of the brazed specimens with BNi-6 and 7 was occurred in elastic range without plastic yielding up to a peak stress. Among these filler metals, the BNi-2 brazed at $1050^{\circ}C$ showed excellent wettability and the highest tensile strength (101.6MPa).

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.11a
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• pp.43-49
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• 2002

A7003 alloy has characteristics of their excellent weldability, high corrosion resistance and superior plastic working however the broadening of application for the alloy has been hampered by the lower extrudability associated by Mg content. For improvement of extrudability and enhanced recovery efficiency during Al scrap recyeling, it has been generally practiced to reduce Mg content in A7003 alloy. Therefore, it is necessary to investigate the influence of Mg content on mechanical strength and extrudability of A7003 alloy. For efficient material processing which has small amounts, life cycle assessment in material processing(MLCA) is evaluated. The quantitative analysis of energy requirements and $CO_2$ emission for production of A7003 extruded bar are estimated with different Mg content and billet pre-heating process (heating source by light oil or LPG). In particular, the estimation of energy requirements was performed within shipping and gating range (except the mining and extraction stages)to investigate the influence of the variables on energy requirements and $CO_2$ emission in detail. As Mg content increased, the flow stress and the extrusion pressure for A7003 alloy increased. It has been thought that an increment in extrusion pressure with increasing Mg content is caused by the solid solution hardening of Mg atoms in the matrix and increment in volume fraction of intermetallic compound, $Mg_2Si$. The extrudability and the tensile strength are equal to, or above that of conventional A 7003 alloy even the content of Mg varied from $1.1wt.\%\;to\;0.5wt.\%$ alloy. This means that minimizing the content of Mg in A7003 alloy can enhance recovery efficiency during Al scrap recycling. It can be quoted that rather than Mg content energy source for billet heating is a prime factor to determine the atmospheric $CO_2$ emission.

• Journal of Korea Foundry Society
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• v.2 no.3
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• pp.2-15
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• 1982

In this study, the influenced of graphite shape on the boriding of cast iron and boride structure was investigated. Gray cast iron, ferritic and pearlitic ductile cast iron were borided at 750,850,900 and $950^{\circ}C$ for 1,3 and 5 hours by powder pack method with the mixture of $B_4C_9\;Na_2B_4O_7$, $KBF_4$ and Shc. The boride layer was consisted of FeB(little), $Fe_2B$ (main) and graphite. Some possibility of the existence of unknown Fe-B-C compound in the boride layer was suggested. And precipitates in the diffusion zone was $Fe_3(B,C)$. The concentration of Si and precipitation of $Fe_3(B,C)$ in the ${\alpha}$ layer raised the hardness of this Zone. The depth and hardness of boride layer increased with the increase of treating temperature and tim. But high temperature (over $950^{\circ}C)$ caused pore at graphite position and long treating time (5hrs) sometimes caused formation of graphite layer beneath the boride layer. So, for the practical application of borided cast iron, treating in short time and at low temperature was recommended. And for ductile cast iron, ferritizing or pearlitizing heat treatment was seemmed to be possible at the same time with boriding. The graphite in the boride layer was deeply concerned with the qualitx and characteristics of the boride layer. And it greatly influenced on the shape of the boride phase, structure of the boride layer. Generally speaking, the existance of graphite restrained the growth of the boride phase. But the boundary between the gsaphite and the matrix acted as the shortcut of boron diffusion. So, for gray cast iron, the graphite layed length-wise led the formation of boride layer.

• Fisheries and Aquatic Sciences
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• v.21 no.6
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• pp.16.1-16.7
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• 2018

Background: Matrix metalloproteinases (MMPs) are linked with several complications such as metastasis of cancer progression, oxidative stress, and hepatic fibrosis. Brown seaweeds are being extensively studied for their bioactive molecule content against cancer progression. In this context, Sargassum horneri was reported to possess various bioactivities including antiviral, antimicrobial, and anti-inflammatory partly due to its phenolic compound content. Methods: In this study, potential of S. horneri was evaluated through anti-MMP effect in HT1080 fibrosarcoma cells. S. horneri crude extract was fractionated with organic solvents, namely, water ($H_2O$), n-buthanol (n-BuOH), 85% aqueous methanol (85% aq. MeOH), and n-hexane. The non-toxicity of fraction samples (Sargassum horneri solvent-partitioned extracts (SHEs)) was confirmed by cell-viability assay. SHEs were tested for their ability to inhibit MMP enzymatic activity through gelatin digestion evaluation and cell migration assay. Expressions of MMP-2 and MMP-9 and tissue inhibitors of MMP (TIMPs) were evaluated by reverse transcription and Western blotting. Results: All fractions inhibited the enzymatic activities of MMP-2 and MMP-9 according to gelatin zymography. Except $H_2O$ fraction, fractions hindered the cell migration significantly. All tested fractions suppressed both mRNA and protein levels of MMP-2, MMP-9, TIMP-1, and TIMP-2. Conclusion: Overall, current results suggested that S. horneri has potential to be a good source for anti-MMP agents, and further investigations are underway for better understanding of the action mechanism and isolation and elucidation of the bioactive molecules.

• Bulletin of the Korean Chemical Society
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• v.34 no.11
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• pp.3243-3248
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• 2013

The tissue inhibitor of metalloproteinase-2 (TIMP-2) inhibits matrix metalloproteinases activity and modulates cellular proliferation and apoptosis. The human serum albumin-TIMP-2 with folic acid conjugate (termed HT2-folate) was synthesized to promote uptake through folate receptors (FRs), and a corresponding radio-labeled compound was prepared for tumor diagnosis by positron emission tomography (PET). $^{68}Ga$-NOTA-HT2-folate was synthesized from $^{68}Ga$ and the NOTA chelator with HT2-folate. The fusion protein was identified using MALDI-TOF mass spectrometry. The radioligand was prepared with a high radiochemical yield. Cell-surface association of $^{68}Ga$-NOTA-HT2-folate significantly increased over time in FR-positive tumor cells. In animal PET and biodistribution studies, tumor uptake was very high as early as 1 h after radioligand injection. Folate conjugation enhanced the selective receptor-targeting efficacy of HT2 in FRexpressing tumors, and its radioligand will be useful as an in vitro tool and for in vivo tumor diagnosis by PET imaging.

• Korean Journal of Crystallography
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• v.15 no.2
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• pp.88-92
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• 2004

An organometallic compound, $(C_{16}H_{21}B_{10}BrOSn)$, was synthesized from o-carborane, closo-1-[(methoxyl)methyl]-o-carborane $(HCab^o)$, and $SnMe_2Br_2$. The molecular structure of this complex has been determined by X-ray diffraction. Crystallographic data: orthorhombic, space group Pna2, a = 17.9292(15)$\AA$, b= 7.2066(4)$\AA$, c=13.0582(10)$\AA$, Z=4, V=1687.2(2) $\AA^3$. The structure was solved by direct methods and refined by full-matrix least-squares methods to give a model with a reliability factor R=0.0574 for 1724 reflections.

• Journal of Welding and Joining
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• v.29 no.4
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• pp.85-92
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• 2011

Microstructures and tensile properties in arc brazed joints of ferritic stainless steel, 429EM using Cu-8.6%Al insert metal was investigated as function of brazing current. The brazing speed was fixed at 800mm/min and brazing current varied in the range of 80A to 120A. The initial phase of filler metal was Cu single phase. However, the insert metal structures of brazed joints was composed of Cu matrix and intermetallic compound such as ${\gamma}_1(Al_4Cu_9)$, and flower-shape Fe-Cr. The fraction of ${\gamma}_1(Al_4Cu_9)$ phase was similar with 80A and 100A brazing currents while that of brazed with 120A was decreased. On the other hand, the fraction of Fe-Cr phase increased with increasing of the brazing current. A reaction layer at the base metal/insert metal interface was observed and this reaction layer was thickened with increasing of the brazing current. In the brazed joints with the current lower than 100A, crack was grew up along the interface which was perpendicular to the tensile stress, and then, passed through the insert metal in the final stage of fracture. As the brazing current increased to 120A, fracture occurred at the base metal.

• Korean Journal of Medicinal Crop Science
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• v.21 no.6
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• pp.466-473
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• 2013

This study investigates the effect of supercritical fluid extract (CMPB803-C) of Lithospermum erythrorhizon, shikonin and acetylshikonin isolated from Lithospermum erythrorhizon on IL-$1{\beta}$-induced chondrocytes and monosodium iodoacetate (MIA)-induced osteoarthritis in rat. Shikonin ($50{\mu}m$) and acetylshikonin ($3{\mu}M$) treatment reduced significantly the mRNA expression and enzyme activity of matrix metalloproteinase (MMP)-1, -3 and -13 in IL-$1{\beta}$-induced SW1353 chondrosarcoma cells. The chondro-protective effects of CMPB803-C and acetylshikonin were than analyzed in a rat OA model using a single intra-articular injection of MIA (1mg) in the right knee joint. CMPB803-C (200mg/kg) or acetylshikonin (5mg/kg) was orally administered daily for two weeks starting after 1 week of MIA injection. In the histological observation, CMPB803-C and acetylshikonin clearly improved OA lesions being comparable to or better that control group. Our results demonstrated that CMPB803-C and acetylshikonin as active compound of Lithospermum erythrorhizon have a strong chondro-protective effect in OA rats, which likely attributes to its anti-inflammatory activity and inhibition of MMPs production.

• Journal of Microbiology and Biotechnology
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• v.6 no.6
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• pp.445-450
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• 1996

Gelatinase A is a member of the matrix metalloproteinases that play an important role in cancer invasion and metastasis. In the course of screening gelatinase A inhibitors from microbial sources, a fungal strain PT-262 showed a strong inhibitory activity. The strain was identified as Chaunopycnis alba on the basis of its morphological characteristics. The inhibitor was isolated from acetone extract of mycelial cake by sequential chromatographies on MCI-gel, Sephadex LH-20, and a reverse-phase HPLC column. The purified inhibitor was identified as pyridoxatin by its physico-chemical properties and spectroscopic analysis. Pyridoxatin is not a peptide analog and has cyclic hydroxamic acid moiety. It inhibited activated gelatinase A with an $IC_{50}$ value of 15.2 ${\mu}M$ using fluorescent synthetic peptide. It also had a strong cytotoxicity against human cancer cell lines in vitro. Furthermore, this compound inhibited DNA synthesis with an $IC_{50}$ value of 2.92 ${\mu}M$ in PC-3 prostate cancer cells by [$^3H$]thymidine incorporation assay.

• Journal of the Korean Applied Science and Technology
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• v.28 no.2
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• pp.170-177
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• 2011

Transdermal drug delivery(TDS) offers many important advantages. For instance, it is easy and painless, it protects the active compound from gastric enzymes, and it avoids the hepatic first-pass effect. Also, it is simple to terminate the therapy if any adverse or undesired effect occurs. But skin is a natural barrier, and only a few drugs can penetrate the skin easily and in sufficient quantities to be effective. Therefore, in recent years, numerous studies have been conducted in the area of penetration enhancement. The most commonly used transdermal system is the skin patch using various types of technologies. Compared with other method of dosage, it is possible to use for a long term. It is also possible to stop the drug dosage are stopped if the drug dosage lead to side effect. Polysaccharide, such as xanthan gum and algin were selected as base materials of TDS. Also, these polymers were characterized in terms of enhancers and drug contents. Among these polysaccharide, the permeation rate of Paroxetine such as lipophilic drug was the fastest in xanthan gum matrix in vitro. We used glycerin, PEG400 and PEG800 as enhancers. Since dermis has more water content(hydration) than the stratum corneum, skin permeation rate at steady state was highly influenced when PEG400 was more effective for lipophilic drug. Proper selection of the polymeric materials which resemble and enhance properties of the delivering drug was found to be important in controlling the skin permeation rate.