• Korean Journal of Materials Research
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• v.26 no.12
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• pp.751-756
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• 2016

Graphite was diffusion-bonded by hot-pressing to W-25Re alloy using a Ti interlayer. For the joining, a uniaxial pressure of 25 MPa was applied at $1600^{\circ}C$ for 2 hrs in an argon atmosphere with a heating rate of $10^{\circ}C\;min^{-1}$. The interfacial microstructure and elemental distribution of the W-25Re/Ti/Graphite joints were analyzed by scanning electron microscopy (SEM). Hot-pressed joints appeared to form a stable interlayer without any micro-cracking, pores, or defects. To investigate the high-temperature stability of the W-25Re/Ti/Graphite joint, an oxy-acetylene torch test was conducted for 30 seconds with oxygen and acetylene at a 1.3:1 ratio. Cross-sectional analysis of the joint was performed to compare the thickness of the oxide layer and its chemical composition. The thickness of W-25Re changed from 250 to $20{\mu}m$. In the elemental analysis, a high fraction of rhenium was detected at the surface oxidation layer of W-25Re, while the W-25Re matrix was found to maintain the initial weight ratio. Tungsten was first reacted with oxygen at a torch temperature over $2500^{\circ}C$ to form a tungsten oxide layer on the surface of W-25Re. Then, the remaining rhenium was subsequently reacted with oxygen to form rhenium oxide. The interfacial microstructure of the Ti-containing interlayer was stable after the torch test at a temperature over $2500^{\circ}C$.

• Nuclear Engineering and Technology
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• v.42 no.5
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• pp.600-607
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• 2010

Rhenium-186, having a half-life of 90.64 h, is an important radionuclide, used in metabolic radiotherapy and radio immunotherapy. $^{186}Re$ hydroxyethylidene diphosphonate (HEDP) is a new compound used for the palliation of painful skeletal metastases. Its production is achieved via charged-particle-induced reactions; the data are available in EXFOR library. For the work discussed in this paper, production of $^{186}Re$ was done via $^{nat}W(p,n)^{186}Re$ nuclear reaction. Pellets of $^{nat}W$ were used as targets and were irradiated with 15, 17.5, 20, 22.5, 25 MeV proton beams at 5 ${\mu}A$ current. The radiochemical separation was performed by the ion exchange chromatography method. The production yield achieved at 25 MeV was 1.91 $MBq{\cdot}{\mu}A^{-1}{\cdot}h^{-1}$. Excitation functions for the $^{186}Re$ radionuclide, via $^{186}W(p,n)^{186}Re$ and $^{186}W(d,2n)^{186}Re$ reactions were calculated by ALICE-ASH and TALYS-1.0 codes to validate and fit the experimental data and to obtain a recommended set of data for $^{186}W(p,n)^{186}Re$ reaction. Required thickness of the targets was obtained by SRIM code for each reaction.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.44 no.1
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• pp.97-103
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• 1995

This paper reports the following two topics : $\circled1$ ozone concentration (O$\sub$3con/) and discharge characteristics in flowing O$\sub$2/ with variation of Re$\sub$3/ at high voltage nozzle (HVN) of HVN 10 type ozonizer. $\circled2$ O$\sub$3con/ with variation of Re$\sub$3/ at HVN of HVN 25 type ozonizer. The important conclusions obtained from this paper are as follows. 1) In HVN 10 type ozonizer : $\circled1$ The discharge pattern can be controlled by adjustment of the Re$\sub$3/. $\circled2$ V$\sub$c/ is inversely proportional to pulse width (P$\sub$w/) and pulse frequency (P$\sub$f) $\circled3$ O$\sub$3con/ increase as decreasing of Re$\sub$3/ for constant P$\sub$w/ and P$\sub$f/. $\circled4$ O$\sub$3con/ increase as decreasing of P$\sub$w/, O$\sub$3con/ is proportional to P$\sub$f/. 2) In HVN 25 type ozonizer : O$\sub$3con/ of HVN 25 type ozonizer can increase than that of HVN 10 type ozonizer, according to parallel circuit of applied voltage and serial of supplied gas. As a result, we can obtain O$\sub$3con/ of 825[ppm] as the maximun value.

• Journal of Powder Materials
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• v.21 no.1
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• pp.7-15
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• 2014

This study investigated the densification behavior of rhenium alloys including W-25 wt.%Re and Re-2W-1Ta (pure Re) during sintering. The dilatometry experiments were carried out to obtain the in-situ shrinkage in $H_2$ atmosphere. The measured data was analyzed through shrinkage, strain rate and relative density, and then symmetrically treated to construct the linearized form of master sintering curve (MSC) and MSC as a well-known and straightforward approach to describe the densification behavior during sintering. The densification behaviors for each material were analyzed in many respects including apparent activation energy, densification parameter, and densification ratio. MSC with a minimal set of preliminary experiments can make the densification behavior to be characterized and predicted as well as provide guideline to sinter cycle design. Considering the results of linearized form and MSC, it was confirmed that the W-25 wt.%Re compared to Pure Re is more easily densified at the relatively low temperature.

• Wind and Structures
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• v.29 no.1
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• pp.1-13
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• 2019

A numerical investigation on forces and flow around three square cylinders in side-by-side arrangement is conducted at a Reynolds number Re = 150 with the cylinder center-to-center spacing ratio L/W = 1.1 ~ 9.0, where W is the cylinder side width. The flowat this Re is assumed to be two-dimensional, incompressible, and Newtonian. The flow simulation is conducted by using ANSYS-Fluent. The flow around the three side-by-side cylinders entails some novel flow physics, involving the interaction between the gap and free-stream side flows as well as that between the two gap flows. An increase in L/W from 1.1 to 9.0 leads to five distinct flow regimes, viz., base-bleed flow (L/W < 1.4), flip-flopping flow (1.4 < L/W < 2.1), symmetrically biased beat flow (2.1 < L/W < 2.6), non-biased beat flow (2.6 < L/W < 7.25) and weak interaction flow (7.25 < L/W < 9.0). The gap flow behaviors, time-averaged and fluctuating fluid forces, time-averaged pressure, recirculation bubble, formation length, and wake width in each flow regime are discussed in detail.

• Journal of Soil and Groundwater Environment
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• v.25 no.3
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• pp.43-51
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• 2020

About 90% of groundwater wells in Jeju Island are reported to be under the threat of contamination by infiltration of the surface pollutants. Most of those wells have improperly grouted annulus which is an empty space between the well and the inner casing. As a remedy to this problem, some of the wells were re-grouted by filling the annulus with cement without lifting an inner casing. In order to evaluate whether this method is appropriate for the geological structure of Jeju Island, two wells (W1 and W2) were selected and this method was applied. The water holding capacity did not decrease while the nitrate levels decreased from 16.8 and 20.2 to 6.8 and 13.8 mg/L in W1 and W2, respectively. The higher nitrate level in W2 is deemed to be influenced by the livestock farms located in the upper area of the well. In addition, transmissivity of the vedose zone was higher in W2 than W1, potentially facilitating the transport of nitrate to the groundwater. The overall result of this study suggests re-grouting of wells for the purpose of protecting water quality of goundwater should take into account geological structure of vadose zone as well as appropriate source control of the contaminants.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.3 no.2
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• pp.80-84
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• 2017

Re-188 is an excellent and practical radioisotope produced by W-188/Re-188-generator for therapy. We prepared Re-188-tin colloid for therapy of various diseases and tried to treat peritoneal effusion in animal model. Sarcoma-180 cells were injected into ICR mice to induce peritoneal effusion and the mice were grown for 3 d. Re-188-tin colloids (0.25, 0.5, and 1 mCi/mL per 30 g body weight) were injected into the mice and the mice were grown for 90 d. Planar gamma scintigraphy showed even distribution of Re-188-tin colloid radioactivity. Bax expression was found to be dose dependent to Re-188-tin colloid. Normal saline treated group showed the shortest survival time. Among the treated groups, 0.5 mCi dose group showed the longest survival time. In conclusion, Re-188-tin colloid was prepared successfully and showed the feasibility to use as a peritoneal effusion treatment in mice.

• Journal of Korean Society of Forest Science
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• v.97 no.5
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• pp.547-551
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• 2008

The study aimed to develop a cryopreservation method for long-term storage using mature somatic embryo of Japanese larch. In this study, desiccation treatments significantly affected re-induction rates of embryogenic tissue (ET) from dried somatic embryos. In the effect of different dehydration temperature and duration on the re-initiation ET. the highest frequency was shown when somatic embryos were dehydrated at $25^{\circ}C$ for 2 (45.5%) or 1 day (43.3%), respectively. In addition, low temperatures [$4^{\circ}C$, 2 days (44.2%) or 3 days (43.5%)] were marked higher ET initiation. After that, the initiation value was declined with dehydration duration. For comparison of different relative humidity on re-induction frequency of ET, the best re-induction (43.5%) was obtained from somatic embryos pre-dried at $(NH_4)_2SO_4$ (RH 79%). Both $Na_2HPO_4$ (RH 97%) and $Na_2CO_3$ (RH 88%) treatments were showed the similar rate, 34.6, 34.2%, respectively. However the lowest rate (19.6%) was observed in distilled water (RH 100%). In comparison of the various storage temperatures and duration of the dried somatic embryos, the highest frequency (66.9%) of re-initiation was obtained when somatic embryos were cryopreserved for one day. However, the frequency was gradually decreased as the time length of storage increased regardless of types of storage. None of ET re-initiated when stored at $4^{\circ}C$ for 1, 2 and 84 days.

• KSBB Journal
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• v.10 no.4
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• pp.449-454
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• 1995

The effects of metathesis for concentrating the tocopherols from soybean and rice-bran scum oils were studied by using the batch reactor under helium atmosphere. The contents of tocopherols in the scum oils decreased consticuously when heated under air atmosphere or when kept in hexane solution above 5 days even at room temperature. The sterols in the scum oils were removed by the mixed solvent method. Metathesis of the sterol-removed scum oils in hexane was performed over Re2O7/Al2O3 and WO3/Al2O3 catalysts, and the concentrate was obtained by distillation in vacuum at $190^{\circ}C$. The effect of metathesis was evaluated as relative ratio of ${\alpha}$-tocopherol in the concentrate to that in scum oil. The maximum ratio for both scum oils was obtained on 12.8%(w/w)$Re_2O_7/Al2O_3$ catalyst which formed effectively the active sites for metathesis by the reaction between the added tetramethyltin and $Re_2O_7$ on the surface of the catalyst. The optimum amount of the catalyst was 0.5g pre l0g scum oil, and the optimum reaction temperature was $25^{\circ}C$ for both scum oils. The metathesis was more effective in rice-bran scum oil than in soybean scum oil. These facts indicated that the tocopherols in the scum oils can be highly concentrated by applying metathesis.

• Journal of Radiopharmaceuticals and Molecular Probes
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• v.5 no.1
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• pp.26-35
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• 2019

$^{188}Re$ is one of the most readily available generator derived and useful radionuclides for therapy emitting ${\beta}^-$ particles (2.12 MeV, 71.1% and 1.965 MeV, 25.6%) and imageable gammas (155 keV, 15.1%). The $^{188}W/^{188}Re$ generator is an ideal source for the long term (4-6 months) continuous availability of no carrier added (NCA) $^{188}Re$ suitable for the preparation of radiopharmaceuticals for radionuclide therapy. Rhenium-188 has been used for the preparation of therapeutic radiopharmaceuticals for the management of diseases such as bone metastasis, rheumatoid arthritis and primary cancers. Several early phase clinical studies using radiopharmaceuticals based on $^{188}Re$ -labeled phosphonates, antibodies, peptides, lipiodol and particulates have been reported. In this review, we addressed the current development status of $^{188}Re$ radiopharmaceuticals for liver cancer therapy and their applications.