• Journal of the Korean Ceramic Society
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• v.30 no.2
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• pp.157-163
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• 1993

Hot pressing after cold cyclic compaction of Al2O3 powder mixtures containing SiC whiskers or Al2O3 short fibers is studied with emphasis on the effects of cold cyclic compaction. The green density of the mixtures increases as the cycle number increases and the cyclic pressure becomes higher. The higher green density is also obtained by cold cyclic compaction with the lower pressrue than a single stroke cold compaction. To achieve a higher densification during hot pressing, cold cyclic compaction before hot pressing is more efficient compared to the conventional hot pressing process (without cold cyclic compaction). Moreover, a low cyclic pressure did not affect on toughening mechanism by whisker reinforcement.

• Journal of the Korean Wood Science and Technology
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• v.27 no.1
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• pp.64-71
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• 1999

This study was conducted to manufacture MDF panels bonded with PF resins which provide excellent durability and dimensional stability with panels, and to identify benefits and weaknesses of using PF resins for MDF panels that have been manufactured with urea-formaldehyde (UF) resins for interior applications due to its low dimensional stability under moisture conditions. The results showed that the performance of PF-bonded MDF panels satisfied the performance requirement. A six-cycle aging test also revealed that PF-bonded MDF panels had high durability. Thickness swelling after 24 hours submersion in cold water was less than 2 percent, showing good dimentioanl stability. The identified weaknesses of using PF resins were relatively high resin content and long hot-pressing time. An acceptable resin content appeared to be 8 percent which can increase the production cost of PF-bonded MDF panels. The hot-pressing time (7 minutes) used in this study is relatively long compared to that of UF-bonded MDF panels. This result also indicates that hot-pressing process has to be optimized to control various pressing variables.

• Journal of the Korea Furniture Society
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• v.21 no.3
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• pp.237-247
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• 2010

This research was carried out to examine the properties of black charcoal board, in order to find the proper manufacturing condition for the black charcoal-board made of the charcoal. The charcoal in this study was distillated from domestic wood waste, and it were also the purpose of this study to see if the black charcoal-board has the advantageous properties of charcoal as a well-being building material against the sick house problem. Domestic wood waste was consisted of MDF 40%, PB 30%, plywood 15% and wood 15%, respectively. Black charcoal board was produced by hot pressing with following conditions; temperature $170^{\circ}C$, three stage pressing cycle of $40-10-40\;kgf/cm^2$(1min.-2.5min.-5min.) and non formaldehyde adhesives [P15%+M5%:MDI(M), poly vinyl acetate emulsion(P). Fine mixed particle size [#6-12(16.9%), #12-18(16.7%), #12-40(47.2%), #40-60(9.5%), #60-100(5.9%), less than #100(3.8%)] gave better results than larger particle size [over #6(33.8%), #12-18(17.7%), #12-40(37.7%), #40-60(6.4%), #60-100(2.6%), less than #100(1.8%)]. Final moisture content of the mat was best at 36%. Black charcoal-board showed less MOR and IB(internal bond), more WA(water absorption) than that of white charcoal-board. Black charcoal board showed not only the same gas adsorption and dimensional stability as white charcoal board but also good cutting, nailing and drilling for indoor environment systems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.571-572
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• 2006

RTP (rapid thermal pressing), one of micro-pattern replication techniques like hot embossing, is focused on achieving shorter cycle time. DFSS(Design for Six Sigma) has been applied in order to enhance the completeness of the development process for RTP system. According to DIDOV roadmap, we derived design concepts and subsequently decided the main performances, design factors, and components for RTP system. In the design process of RTP system using finite element analysis, it was realized that its structural characteristics affect large area replicability. Optimizing structural design factors, based on CAE, it was checked out that its large area replicability could be improved in a virtual test. Finally, we have a plan to validate the large area replicability of the developed RTP system, by performing micro-pattern replication tests with polymeric sheets.

• Journal of the Korean Wood Science and Technology
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• v.10 no.3
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• pp.189-189
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• 1982

This study was carried out to determine the possibility of making fiberboard through the dry forming process, utilizing the tannin-like material of the Asplund pulp from the silk worm oak as a binder. The fiberboard was made through paraformaldehyde treatment, spray of NaOH solution and adjustment of mat moisture content, by hot-pressing at $220^{\circ}C$, and 50-6-50kg/$cm^2$ pressure with 6-min. (0.6-1.8-3.6) three-stage pressing cycle. The results are summarized as follows: 1. The modulus of rupture value of fiberboard treated with NaOH solution was greater than that of untreated. The value was increased in proportion to the paraformaldehyde content from I to 5%, but there was no increasing between 5 and 7% paraformaldehyde content. The value became higher along with the increase of mat moisture content from 15% to 25%. 2. The water adsorption of fiberboard treated with NaOH solution was lower than that of untreated. The value was de"creased in proportion to the paraformaldehyde content from 1 to 5%, but there was no decreasing between 5 and 7% paraformaldehyde content.. 3. A good quality fiberboard (modulus of rupture value of about 250kg/$cm^2$) was made through 5% paraformaidehyde treatment and 3% treatment of 10% NaOH solution, when the mat moisture content was 25%. was 25%.

• Journal of the Korean Vacuum Society
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• v.15 no.3
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• pp.325-330
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• 2006

In order to verify the integrity of the first wall (FW) of the International Thermonuclear Experimental Reactor (ITER), the fabricated Cu/SS mock-up is tested in the JAEA Electron Beam Irradiation Test Stand (JEBIS). To fabricate the Cu/SS mock-up, CuCrZr and 316L authentic stainless steel (SS316L) are used for Cu alloy and steel, respectively The hot isostatic pressing (HIP) is used as a manufacturing method with a $1050^{\circ}C$ and 150 MPa. The high heat flux (HHF) test is performed using an electron beam with a heat flux of $5MW/m^2$ and a cycle of 15-sec on time and 30-sec off time. The temperature measurement in the HHF test shows good agreement with the results obtained from ANSYS code analysis, which is used for determining the HHF test conditions.

• Korean Journal of Materials Research
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• v.10 no.4
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• pp.312-316
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• 2000

A study has been made to investigate the effects of hot isostatic pressing(HIP ping) on bond strength and elevated temperature characteristics of thermal barrier coating(TBC). The specimens were prepared by HIPping of TBC which is composed of the ceramic top coat(8wt%$Y_2$$O_3$-$ZrO_2$) and the metallic bond coat on the matrix of IN738LC superalloy. The results showed that the porosity and microcracks in the ceramic top coat of TBC were significantly decreased by HIP. As a result, the bond strength of the HIPped coating was increased above 48% compared to that of as-coated specimen and microstructure was homogenized. It was found that the thermal cycle resistance of HIPped coating was inferior to that of as-coated specimen. It was considered that this result was mainly caused by the reduction of internal defects in the top coat layer which could play a role in relaxing the thermal stress due to a large difference in thermal expansion between TBC and matrix.

• Journal of Powder Materials
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• v.26 no.6
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• pp.471-476
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• 2019

Additively manufactured metallic components contain high surface roughness values, which lead to unsatisfactory high cycle fatigue resistance. In this study, high cycle fatigue properties of selective laser melted Ti-6Al-4V alloy are investigated and the effect of dry-electropolishing, which does not cause weight loss, on the fatigue resistance is also examined. To reduce the internal defect in the as-built Ti-6Al-4V, first, hot isostatic pressing (HIP) is conducted. Then, to improve the mechanical properties, solution treatment and aging are also implemented. Selective laser melting (SLM)-built Ti64 shows a primary α and secondary α+β lamellar structure. The sizes of secondary α and β are approximately 2 ㎛ and 100 nm, respectively. On the other hand, surface roughness Ra values of before and after dry-electropolishing are 6.21 ㎛ and 3.15 ㎛, respectively. This means that dry-electropolishing is effective in decreasing the surface roughness of selective laser melted Ti-6Al-4V alloy. The comparison of high cycle fatigue properties between before and after dry-electropolished samples shows that reduced surface roughness improves the fatigue limit from 150 MPa to 170 MPa. Correlations between surface roughness and high cycle fatigue properties are also discussed based on these findings.

• Journal of the Korean Wood Science and Technology
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• v.33 no.3 s.131
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• pp.22-29
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• 2005

This research was carried out not only to examine the proper manufacturing condition for white charcoal board in relation to charcoal particle size and final mat moisture content (FMC), but also to maintain the advantageous properties of white charcoal as a well being building material against the sick house problem. Excellent functional white charcoal board was produced with two groups of FMC 20~25% and FMC 36~60%. The latter showed best results among tested samples in two types which are #40-60type-P15%, M5%, FMC 60% and mixed type-P15%, M5%, FMC36% with non formaldehyde adhesives [MDI (M), poly vinyl acetate emulsion (P)] and three stage pressing cycle of 30-10-$30kgf/cm^2$ (1 min.-1.5 min.-6 min.). The former gave highly acceptable results in two types which are #6 over-M15%FMC25% and mixed type-M25%FMC20%. White charcoal board gave excellent in dimensional stability, gas adsorption and far-infrared emission.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.2
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• pp.155-161
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• 2015

Technetium-99m (^99mTc) is an important, short-lived decay product of molybdenum-99 (⁹⁹Mo), and it is considered the backbone of the modern nuclear diagnostic procedures. Since fission of ²³⁵U is the main source of production of ⁹⁹Mo, either highly-enriched uranium (HEU) targets or low-enriched uranium (LEU) targets are irradiated in the research reactors. The use of LEU targets is being promoted by the international community to avoid the proliferation issues linked with the use of HEU. In order to define the waste management strategy at the planning stage of establishment of an LEU based ⁹⁹Mo production facility, the impact of the use of LEU targets on the radioactive waste stream of the ⁹⁹Mo production facility was analyzed. Because the volume of uranium waste is estimated to increase six times, the use of high uranium density targets and the utilization of hot isostatic pressing were recommended to reduce the increased waste volume from the use of LEU based targets.