[en] As buildings are becoming larger, demand for mega-sized composite columns (over 1-meter diameter) is increased. We have developed and commercialized welded built-up CFT column (ACT Column I) since 2005 which are structurally stable and economical using cold-formed steel with rib. However, there has a limit in size of cross section (618 X 618mm) by a fabrication facilities. And due to charateristics of closed cross section, there has a limit to construction of connection of moment frame. Composite mega column (ACT Column II) has same concept of forming closed cross section. But in order to enlarge cross sectional size, thick plate is inserted between cold-formed steels. Since composite mega column can control thickness and width of thick plate, steel or composite beams can be directly attached to the connection. In this study, we propose strength formula of composite mega column to beam connections with T-shaped stiffener as internal diaphragm and verified through finite element analysis and simple tensile experiment. (Author)

[en] Recycled aggregate is an environmentally self-sustainable solution that can reduce construction waste and replace natural aggregates. However, there is a disadvantage in concrete such as initial strength drop and long-term strength development. Therefore, the interaction effect of the two materials can be expected by filling the cyclic aggregate concrete in the CFT column. In order to develop a concrete with compressive strength of 50MPa as a recycled aggregate, we carried out a mixing experiment and fabricated 18 specimens to confirm the compressive behavior of a RCFT (Recycled Concrete Filled Tube) column that can be applied to actual buildings. Variable is the shape and thickness of steel pipe, concrete strength and mixing ratio, and coarse aggregate and fine aggregate are all used as recycled aggregate. The optimum mixing ratio for recycled aggregate concrete to be filled in the CFT filled steel pipe was found through three concrete preliminary mixing experiments. In addition, the compression test of the RCFT column was carried out to observe and analyze the buckling shape of the CFT column. Based on the analysis of the buckling configuration and the experimental data, the load-displacement curves of the specimens were drawn and the compressive behavior was analyzed. (Author)

[en] Recycled aggregate is an environmentally self-sustainable solution that can reduce construction waste and replace natural aggregates. However, there is a disadvantage in concrete such as initial strength drop and long-term strength development. Therefore, the interaction effect of the two materials can be expected by filling the cyclic aggregate concrete in the CFT column. In order to develop a concrete with compressive strength of 50 MPa as a recycled aggregate, we carried out a mixing experiment and fabricated 18 specimens to confirm the compressive behavior of a RCFT (Recycled Concrete Filled Tube) column that can be applied to actual buildings. Variable is the shape and thickness of steel pipe, concrete strength and mixing ratio, and coarse aggregate and fine aggregate are all used as recycled aggregate. The optimum mixing ratio for recycled aggregate concrete to be filled in the CFT filled steel pipe was found through three concrete preliminary mixing experiments. In addition, the compression test of the RCFT column was carried out to observe and analyze the buckling shape of the CFT column. Based on the analysis of the buckling configuration and the experimental data, the load-displacement curves of the specimens were drawn and the compressive behavior was analyzed. (Author)

[en] The present study is concerned with nucleation and growth of α phase during heat treatment in Ti-Al-Mo-Mn intermetallic alloys processed by hot extrusion of elemental powders. TEM and X-ray diffraction analysis show that the microstructure of the as-hot extruded alloy consists of γ, α₂ and B2 phases. The volume fractions of α₂ and B2 phases are 16 and 20%, respectively, which shows that B2 phases that contain significant amounts of Mo have an orientation relationship with γ plates inside them. Microstructural evolution during heat treatment reveals that the α₂ phase nucleates and grows in lamellar form by edgewise and sidewise mechanism. Edgewise growth of the α₂ phase is more rapid than sidewise growth due to the coherent interface between α₂ and γ phases along the sidewise direction. Sidewise growth of the α₂ phase occurs by a ledge mechanism. It has been shown that α phase nucleates in γ plates located at the lamellar boundaries and grows along a direction that can produce an incoherent interface. γ phase present in the B2 phase affects the growth of the α phase by providing a preferential site for α growth

[en] Analytical studies using the FLOW-3D computer program have been performed on natural convection heat transfer of a high density molten metal pool, in order to evaluate the coolability of the corium pool. The FLOW-3D results on the temperature distribution and the heat transfer rate in the molten metal pool region have been compared and evaluated with the experimental data. The FLOW-3D results have shown that the developed natural convection flow contributes to the solidified crust formation of the high density molten metal pool. The present FLOW-3D results, on the relationship between the Nusselt number and the Rayleigh number in the molten metal pool region, are more similar to the calculated results of Globe and Dropkin's correlation than any others. The natural convection heat transfer in the low aspect ratio case is more substantial than that in the high aspect ratio case. The FLOW-3D results, on the temperature profile and on the heat transfer rate in the molten metal pool region, are very similar to the experimental data. The heat transfer rate of the internal heat generation case is higher than that of the bottom heating case at the same heat supply condition. (author)

[en] The chelating agent DOTA (1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid) forms stable complexes with beta emitting radionuclides, and these specific complexes can be used to develop tumour targeting agents when coupled with biomolecules such as peptides and antibodies. The present study was aimed at developing techniques for labelling the biomolecule DOTATATE with radionuclides such as ¹⁶⁶Ho, ¹³¹I and ¹⁷⁷ Lu. The radioisotope ¹⁶⁶Ho, produced at the HANARO multipurpose reactor in the Republic of Korea, is a candidate for therapeutic use in cancer treatment because it has a 26.8 h half-life and decays with the emission of beta particles with energies of 1.77 MeV (48%) and 1.85 MeV (51%). Two other beta emitting nuclides, ¹³¹I and ¹⁷⁷Lu, were included in the study for comparison. It was established that, of the three radionuclides studied, the best for targeted radiotherapy was ¹⁷⁷Lu when complexed with DOTATATE. The present study focused on the development of techniques for labelling peptides with ¹⁶⁶Ho, as well as quality control procedures. The labelling yield of the radiopeptide and its radiochemical purity were determined by high performance liquid chromatography and instant thin layer chromatography. In vitro assays were carried out to determine the therapeutic efficacies of ¹⁶⁶Ho labelled peptides as a radiotherapeutic agent. (author)

[en] To develop gel type ^99mTc generators by using a poly zirconium complex (PZC) and an alumina column, KAERI has been cooperating with a Japanese company since the late 1990's. In 2005, labeling tests were carried out for the quality control of ^99mTc solution, which was produced from the ⁹⁹Mo loaded PZC sample. The elution efficiency of ^99mTc was in the range of 93-95%. The synthesis of a ^99mTc-tin colloid labeled compound using the eluted solution was investigated for three consecutive days. The lyophilized vials of Tin colloid (KAERI, Korea) were used as cold kits that contained 0.19 mg of stannous chloride dihydrate and 1 mg of sodium fluoride. The ^99mTc-complex was prepared by mixing of the lyophilized compound with the Na^99mTcO₄ in 1 ml of saline and allowing it to stand for 30 min at room temperature. The labeling efficiency of the ^99mTc-complex was determined by ITLC on silica gel impregnated glass fiber sheets and by using a mixture of methyl ethyl ketone (MEK) and a physiological saline as a developing solvent. The labeling yields of ^99mTc-tin colloid were 100% at all cases. The radiochemical purity at room temperature was maintained more that at a level of 98% for more than 6 hours. (author)

[en] Full text: Brachytherapy is one of the effective treatments for in-stent restenosis. Filling the dilatation catheter balloon with radioactive solutions has the advantages of an accurate source positioning and uniform dose delivery to the vessel walls. In addition, it can be used easily with an existing catheter. Moreover, a solution based beta ray source allows for the treatment of large vessels. Of the variety of radioisotopes prepared in a soluble form for use as a liquid radiation source, Ho-166 is a good radioisotope, because it can be readily produced by irradiating a natural Ho target using a low or medium flux research reactor (¹⁶⁵Ho has 100% natural abundance). For X ray imaging, various iodinated X ray contrast agents having the 1,3,5-triiodobenzoic acid platform are used, mainly for computed tomography (CT) and angiographic applications. In the present study, we prepared a new DTPA bisamide derivative, DTPA-BTIPA (3-amino- 2,4,6-triiodoisophthalic acid) containing iodine in the structure. ¹⁶⁶Ho was labeled with DTPA-BTIPA as a possible agent for IVRT for the prevention of restenisis. The optimum condition of the radiolabeling of DTPA-BTIPA with Ho-166 was achieved by varying different reaction parameters. To estimate the ¹⁶⁶Ho-complex as a liquid radiation source for a potential clinical application of IVRT, which is readily excreted through the urinary system in the event of a balloon rupture, a dynamic imaging was acquired. ¹⁶⁶Ho-(DTPA- BTIPA) was prepared by a simple mixing at room temperature. High radiochemical stability (>98%) was maintained over a period of 6 h at room temperature. The radioactivity curve in the kidneys of the rabbit administered with ¹⁶⁶Ho-(DTPA-BTIPA) via an ear vein showed that the ¹⁶⁶Ho-(DTPA- BTIPA) was rapidly cleared through the kidneys. The average of T_max and T_1/2 of ¹⁶⁶Ho-(DTPA-BTIPA) in the kidneys were 2.26 ± 0.78 min and 7.80 ± 1.16 min, respectively. The serial static image scans of the rabbit administered with ¹⁶⁶Ho-complex revealed that none of the tissues except for the urinary system had radioactivity concentrations. Both the radiochemical and biological studies revealed that the ¹⁶⁶Ho labeled DTPA-BTIPA can be further investigated as a potential agent for vascular brachytherapy having the characteristic of a CT contrast. The use of the ¹⁶⁶Ho-DTPA-BTIPA for IVRT is a good alternative to see if the balloon has close contact with the blood vessel wall for the delivery of a sufficient radiation dose to the stenotic artery. (author)

[en] ^99mTc-MAG₃, a currently employed renal function diagnostic, is not ideal owing to its high plasma protein binding and complex synthetic procedure. Thus we developed ^99mTc tricarbonyl cysteine as a potential renal radiopharmaceutical and studied its biological characteristics in experimental animals. We synthesized ^99mTc tricarbonyl precursor and then prepared ^99mTc tricarbonyl cysteine to assess a new renal diagnostic agent. We assessed its labelling yield, biodistribution property in mice, and its dynamic imaging profiles in rabbits. Results obtained throughout the study were as follows: 1) ^99mTc(CO)₃(H₂O)₃⁺ was prepared with higher than 98% of synthetic yield, with the stability up to 8 hrs, and labelling yield of ^99mTc tricarbonyl cysteine was usually higher than 90%, on HPLC. 2) Biodistribution of ^99mTc tricarbonyl cysteine in ICR mice at 5 and 90 min showed very high accumulation in kidney and bladder, and almost 99% of ^99mTc tricarbonyl cysteine was excreted within 90 min post injection. ^99mTc tricarbonyl cysteine was rapidly excreted in vivo without any other residual concentration. 3) renogram of ^99mTc tricarbonyl cysteine in rabbits showed that its T_max (2.86 ± 0.88 min) and T_1/2 (3.78 ± 1.12 min) was similar to those of ^99mTc-MAG₃ (T_max: 1.76 ± 0.66 min; T_1/2: 2.57 ± 0.72). 4) T_max and T_1/2 of ^99mTc tricarbonyl cysteine in kidney with probenecid pretreatment were 2.30 ± 0.17 min and 17.03 ± 2.47 min, respectively. T_1/2 of ^99mTc tricarbonyl cysteine in kidney with probenecid pretreatment were significantly different from that of untreated ones (4.30 ± 0.79 min) (p<0.0001). In conclusion, ^99mTc tricarbonyl cysteine is very simple to prepared and is rapidly excreted through urinary pathway by tubular secretion. (Author)

[en] Demand for energy has increasing rapidly in the last decade. In 2021 an increase in 5% was observed. Half of this demand was covered by fossil fuels, increasing CO₂ emissions to record levels. With the need for new reliable steady supply sources to be used in places where maintenance is difficult, Radioisotope Thermoelectric Generators (RTG) have been given renewed attention in the past 10 years. RTGs uses radioactive decay to generate electricity. This work presents in a simple manner, the basics of RTG operation, the requirements for construction, and is followed by an example developed at Korea Atomic Energy Research Institute (KAERI). Basic Radiation Physics Concepts, RTG configuration requirements, Thermoelectric effect and materials, and calculations for electric power were presented. (author)