• Nuclear Engineering and Technology
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• v.48 no.5
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• pp.1273-1279
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• 2016

Production of iodine-131 by neutron activation of tellurium in tellurium dioxide ($TeO_2$) material requires a target that meets the safety requirements. In a radiopharmaceutical production unit, a new lid for a can was designed, which permits tight sealing of the target by using tungsten inert gaswelding. The leakage rate of all prepared targets was assessed using a helium mass spectrometer. The accepted leakage rate is ${\leq}10^{-4}mbr.L/s$, according to the approved safety report related to iodine-131 production in the TRIGA Mark II research reactor (TRIGA: Training, Research, Isotopes, General Atomics). To confirm the resistance of the new design to the irradiation conditions in the TRIGA Mark II research reactor's central thimble, a study of heat effect on the sealed targets for 7 hours in an oven was conducted and the leakage rates were evaluated. The results show that the tightness of the targets is ensured up to $600^{\circ}C$ with the appearance of deformations on lids beyond $450^{\circ}C$. The study of heat transfer through the target was conducted by adopting a one-dimensional approximation, under consideration of the three transfer modes-convection, conduction, and radiation. The quantities of heat generated by gamma and neutron heating were calculated by a validated computational model for the neutronic simulation of the TRIGA Mark II research reactor using the Monte Carlo N-Particle transport code. Using the heat transfer equations according to the three modes of heat transfer, the thermal study of I-131 production by irradiation of the target in the central thimble showed that the temperatures of materials do not exceed the corresponding melting points. To validate this new design, several targets have been irradiated in the central thimble according to a preplanned irradiation program, going from4 hours of irradiation at a power level of 0.5MWup to 35 hours (7 h/d for 5 days a week) at 1.5MW. The results showthat the irradiated targets are tight because no iodine-131 was released in the atmosphere of the reactor building and in the reactor cooling water of the primary circuit.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.800-808
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• 2005

The compounding resin for biodegradable wrap was developed, and its manufacturing process and physical properties were studied. For these purposes, following factors were optimized: the types and amounts of raw resin material, anti-oxidants, and lubricants used. In this work, the stable compounding resin used to make biodegradable wrap was based on poly(butylene adipate-co-butylenesuccinate) (PBAS) and poly(butyleneadipate-co-butylene succinate-co-butyleneterephthalate) (PBAST). The improved properties of resin with an additive were investigated by melting flow index (MFI). From these results, the physical properties of compounding resin, based on PBAST, were more than those of PBAS. For PBAS, the Irganox 1010, 1076 and Irgafos TNPP as the first and second anti-oxidants, respectively, were good. For PBAST, the good first and second anti-oxidants, respectively, were Irganox 1076 and Mark PEP 36. The good lubricants for feeding PBAS and PBAST were glycerol monostearate and palmityl alcohol, respectively. The stability and tensile strength experiment of wrap were also investigated by the elution of heavy metals and universal testing machine (UTM), respectively. The decomposition ratio of developed wrap was increased proportional to the reclaiming time. The degradation ratio of compounding resin sample was about 60% after 40 days.

• Journal of Welding and Joining
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• v.32 no.6
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• pp.1-7
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• 2014

For the resistance spot welds of CR1180 and GA1180 TRIP steels, the weld quality evaluation method using the digitalized X-ray transmission imaging apparatus was investigated in comparison with the crosssectional examination method. In the case of the resistance spot welding of CR1180, three circular regions, such as WZ(white zone), GZ(grey zone) and DZ(dark zone), appeared on X-ray image and they corresponded to the diameters of indentation mark, nugget and corona bond, respectively. The variation of X-ray transmission thickness due to the thickness variation of the weld seemed to be mainly responsible for the formation of those contrasts. The X-ray image contrast formed from the variation of transmission thickness at the outer border line of DZ could also enable the inspections of the notch shape, nonuniformity of the welding pressure and spatter from its sharpness, concentricity and the normal straight line, respectively. The X-ray image of the resistance spot weld of galvannealed GA1180 TRIP steel was very similar to that of CR1180 TRIP steel except the crown shaped outer border line of DZ which was considered to be due to the melting behavior of zinc having the boiling temperature even lower than the melting temperature of steel.

• Fire Science and Engineering
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• v.14 no.3
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• pp.1-5
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• 2000

In this paper, we analyzed the fire hazard of the ballast for fluorescent lamp used as the indoor lighting. In the result of being analyzed the ballast wire by stereo microscope, many melting points were discovered, it was impossible to judge a cause with the naked eye. In the Thermal-deteriorated ballast wire, elongation structure disappeared at above $700^{\circ}$, and it only showed the enlarged appearance of the copper particle. On the metallurgical microscope of short wire, as it was confirmed the regulation of the columnar structure and the void growth at the center of boundary-face, we found that electrical short-circuit generated. Also, it was confirmed the melted part on the analysis using SEM(scanning electron microscope). Not only CuL and Cuk line that is composition factor of copper but also OK line was observed uniformly on the spectra analysis using EDX(energy dispersive x-ray spectroscopy). It means that oxygen took part in reaction at the recombination process.

• Journal of Life Science
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• v.8 no.5
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• pp.526-531
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• 1998

In this study, the composition and characteristics of poly-$\beta$-hydroxybutyrate (PHB) biosynthesized by Actinobacillus sp. EL-9 are investigated. PHB produced by Actinobacillus sp. EL-9 was identified as the homopolymer of 3-hydroxy-butyric acid (PHB) by infrared spectroscopy and nuclear magnetic resonance spectroscopy analysis. The melting tem-perature (T$_{m}$), and crystallization temperature(T$_{c}$) of PHB was 169.7$^{\circ}C$ and 69.13$^{\circ}C$, respectively. The viscosity on he basis of Brookfield viscometer was 6.01 ㎗/g. The viscosity-average molecular weight estimated by Mark-Ho-wink-Sakurada equation was 1.08$\times$10$^{6}$ ($\pm$3,000).00).

• Journal of the Korean Society of Safety
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• v.11 no.1
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• pp.53-59
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• 1996

To protect the damages or the disasters caused by overheating of industrial electric equipments or electric home appliances, a temperature sensitive thermal fuse is generally used in those equipments. Thermal fuses cutoff the current flow when the temperature of the electric equipments are abnormally overheated and over the certain temperature. Therefore thermal fuse is one of the most important elements in the sense of safety. Thermal fuses are classified into two types according to thermally sensitive materials, a low temperature melting alloy and an organic chemical compound. Domestic products of thermal fuses are now only with an organic chemical compound. Domestic products tested by using cutoff test and aging test etc. are satisfied UL specification. It's shown that the accuracy and the precision of the domestic products are as good as those of the overseas products obtained UL mark. However, some of domestic products show the reclosing problem which is mainly related the safety. This problem should be solved to make the reliable thermal fuses. In this paper, our Interest is to find out the causes of reclosing. In the comparison between thermally sensitive materials occurred reclosing and those occurred no reclosing, the test effects show that the characteristics of emitting heat and absorbing heat are different.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.4 no.1
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• pp.33-40
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• 2006

The characteristics of the aluminum waste melting and the distribution of the radioactive nuclides have been investigated for the estimation on the volume reduction and the decontamination of the aluminum wastes from the decommissioning of the TRIGA MARK it and III research reactors at the Korea Atomic Energy Research Institute(KAERI). The aluminum wastes were melted with the use of the fluxes such as flux $A:NaCl-KCl-Na_3AlF_6$, flux B:NaCl-NaF-KF, flux $C:CaF_2$, and flux $D:LiF-KCl-BaCl_2$ in the DC graphite arc furnace. For the assessment of the distribution of the radioactive nuclides during the melting of the aluminum, the aluminum materials were contaminated by the surrogate nuclides such as cobalt(Co), cesium(Cs) and strontium(Sr). The fluidity of aluminum melt was increased with the addition of the fluxes, which has slight difference according to the type of fluxes. The formation of the slag during the aluminum melting added the flux type C and D was larger than that with the flux A and B. The rate of the slag formation linearly increased with increasing the flux concentration. The results of the XRD analysis showed that the surrogate nuclide was transferred to the slag, which can be easily separated from the melt and then they combined with aluminum oxide to form a more stable compound. The distribution ratio of cobalt in ingot to that in slag was more than 40% at all types of fluxes. Since vapor pressures of cesium and strontium were higher than those that of the host metals at the melting temperature, their removal efficiency from the ingot phase to the slag and the dust phase was by up to 98%.

• Nuclear Engineering and Technology
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• v.41 no.5
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• pp.575-602
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• 2009

In the wake of the Three Mile Island accident, vigorous research efforts were initiated to acquire a basic knowledge of the progression and consequences of accidents that involve a substantial degree of core degradation and melting. The primary emphasis of this research was placed on containment integrity, with: i) hydrogen combustion-detonation, ii) steam explosion, iii) direct containment heating (DCH), and iv) melt attack on the BWR Mark-I containment shell identified as energetic processes that could lead to early containment failure (i.e., within the first 24 hours of the accident). Should the core melt fail the reactor vessel, then non-condensable gas production from Molten Core-Concrete Interaction (MCCI) was identified as a mechanism that could fail the containment by pressurization over the long term. One signification question that arose as part of this investigation was the effectiveness of water in terminating an MCCI by flooding the interacting masses from above, thereby quenching the molten core debris and rendering it permanently coolable. Successful quenching of the core melt would prevent basemat melt through, as well as continued containment pressurization by non-condensable gas production, and so the accident progression would be successfully terminated without release of radioactivity to the environment. Based on these potential merits, ex-vessel corium coolability has been the focus of extensive research over the last 20 years as a potential accident management strategy for current plants. In addition, outcomes from this research have impacted the accident management strategies for the Gen III+LWR plant designs that are currently being deployed around the world. This paper provides: i) an historical overview of corium coolability research, ii) summarizes the current status of research in this area, and iii) highlights trends in severe accident management strategies that have evolved based on the findings from this work.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.11
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• pp.610-615
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• 2016

Diverse accessories are used in automobiles, such as navigation systems, front and rear cameras, spoilers, and sun visors. Sun visors block sunlight so that drivers can drive safely with a better view, and they are used in many automobile designs. However, when large plastic products are manufactured using injection molding, there are many difficulties that develop, like weld lines, short shots, flow marks, imperfections, and distortion. In this study, a CAE simulation was conducted based on previous results to predict potential problems in the injection molding of large products. The flow characteristics up to complete charge for the melting resins were captured using a computer-aided engineering simulation. The temperature departure on the front part of a flow was about $10^{\circ}C$ and very stable. The practical ejecting time of the cold runner was about 70 seconds in the simulation. Finally, the capability of a suitable injection machine was calculated and recommended by prediction of the injection pressure and the die clamping force.

• Journal of Conservation Science
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• v.32 no.2
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• pp.123-139
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• 2016

The excavated potteries of Goryeo Period from the Sandongri archaeological site in Seosan were studied on physicochemical analyses. Surface color of the samples are mainly grayish blue, and showed the natural glaze by melting the body soils during the burning. Partly, swelling surface are observed bloated marks because of blow out gas by burning. The potteries are some possibility of making the similar source clay on the basis of magnetic susceptibilities (about $1{\times}10^{-3}SI\;unit$) and general occurrences. Values of specific gravity, apparent porosity and absorption ratio are divided two groups as highly different cases of bloating surface samples. The source clay of the potteries used mainly microcrystalline clay, the mineral compositions are quartz and some colored minerals. Based on the analysis, the burning temperature of the potteries are assumed that they were around $1,100^{\circ}C$ because detection of quartz and mullite within hard and compact matrices. As geochemical variations of the samples, evolution trends of rare earth, compatible and incompatible elements showed very similar patterns excepting the some major elements, that means the potteries are interpreted to making by elutriation processes using the same raw clays from very similar basement rocks of genetically.