• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2003.05a
• /
• pp.311-314
• /
• 2003

Superconduction materials possess electrical/electronic and magnetic properties. Because superconduction materials is a ceramic powder, that can not be produced singlehandedly. So Ag sheathed Bi-2223 wire was produced by drawing process using powder-in-tube(PIT) method This superconductor has many difficulties to produce. The main difficulty is that the mechanical properties of the ceramic powder are very different from those of the Ag sheath. Actually, the fabrication of Ag sheathed Bi-2223 superconductor by PIT tends to lead to non-uniformity in the core thickness during drawing process. That is so called “Sausaging”. This study analyzed a sausaging using the finite-element method. Also, Effects of drawing process parameters on a sausaging has been carried out using finite element method. Finally, A way to prevent a sausaging has been discussed.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.10 no.6
• /
• pp.373-377
• /
• 2000

For 6H-SiC single crystals which was obtained by sublimation growth (modified Lely process), the relation between the defects and the etch pits to be formed at the site of dislocations were discussed. Typical hexagonal etch pits were formed on (0001) basal plane. The similar hexagonal etch pit shapes were formed on the site of micropipe defects and it was realized that internal planar defects was formed with the same matrix crystal structure as grown crystals, through the observation of the etching morphology at those internal defects.

• Journal of Soil and Groundwater Environment
• /
• v.18 no.3
• /
• pp.93-108
• /
• 2013

This study is aimed to prepare the effective detail survey methods(Phase II) of abandoned metal mines through the contamination assessment for mine types and facilities in the abandoned metal mine areas. The study sites of 12 abandoned mines are located in Gyeonggi-do and Gangwon-do and those were chosen among 310 sites that the Phase II survey was conducted from 2007 to 2009 after considering the results of Phase I for abandoned mines scattered all over the country. 12 study sites were classified into four types; Type I sites only have pit mouth. Type II sites have pit mouth and mine-waste field. Type III sites have pit mouth and tailing sorting field. Type IV sites have pit mouth, tailing sorting field and concentrator(s). In forest land, paddy soil and farm land of Type I, As and Cd were showed average concentration, and Cu and Pb were high on the pit mouth area in one mines where the pit mouth was developed within 500 m. In the mines of Type II, Cu and Pb were showed average concentration too, but As and Cd were slightly high in pit mouth and mine-waste field. The mines of Type III which had grinding particle process through physical separation milling or hitting showed similar tendency with Type II. However, mines of Type IV pit mouth, mine-waste field and showed various results depending on defining the contamination sources. For example, if contamination source was pit mouth, the mixed results of Type I, II, II were showed. In tailing sorting field which was regarded as the most important source and having high mobility, however, if there were no facilities or it was difficult to access directly, field sampling was missed occasionally during phase I and phase II survey. For that reason, the assessment for tailing sorting field is missed and it leads to completely different results. In the areas of Type I mines, the concentration of heavy metals exceeded precautionary standards of soil contamination or not within 1,000 meters of pit mouth. Nickel(Ni) was the largest factor of the heavy metal contamination in this type. The heavy metals except Arsenic(As) were shown high levels of concentration in Type II areas, where pit mouth and mine-waste field were operated for making powder in upriver region; therefore, to the areas in the vicinity of midstream and downstream, the high content of heavy metals were shown. The tendency of high level of heavy metals and toxic materials contained in flotation agent used during sorting process were found in soil around sorting and tailing field. In the abandoned-pit-mouth area, drygrinding area and tailing sorting field area, the content of Cupper(Cu) and Zinc(Zn) were higher than other areas. Also, the contaminated area were larger than mine reclamation area(2,000 m) and the location of tailing sorting field was one of the important factors to estimate contaminated area.

• Journal of architectural history
• /
• v.24 no.3
• /
• pp.43-56
• /
• 2015

Researches on the pit dwellings in the Joseon Dynasty era have been constantly conducted in the archeology field since the beginning of the 2000s. Most of the related researches in the past have been on the classification and chronological record of dwelling types in archeology, but architectural researches on the dwelling history that is connected from the prehistoric age to the Joseon Dynasty era are insufficient. There are no big differences between the excavated pit dwellings of the Joseon Dynasty era and those of the prehistoric age, so pit dwellings were considered to have been used as dwellings for common people until the Joseon dynasty era. This fact is confirmed by the frequency and density of pit dwellings. In this research, what space composition of the pit dwellings that are equipped with the Korean floor heating system is shown according to the plan types was examined and the development and transition process from pit dwellings to Folk houses were analyzed and their correlations with the Folk houses of the Joseon Dynasty era were examined. The Folk house form did not start with the form of the house on the ground but originate from the introduction of Ondol, the Korean floor heating system, to pit dwellings. As the Korean floor heating system is used, the room and kitchen space are composed in the pit dwelling, and the kitchen is expanded to the one that separates the fireplace for cooking to avoid heating that is unnecessary for the summer season. As the size of the dwelling was getting bigger, the division of the space is made by the pillars that support the interior space. Also, the dwelling is expanded into a single row house and a double row house according to the progress direction of Ondol. In other words, the pit dwellings in the Joseon Dynasty era develops with making up diverse floors through the combination and expansion of Ondol and kitchen according to the dweller's convenience and life style and surrounding environment. This research is significant in the sense that it helps understand the formation and development process of our traditional Folk houses and fills the gap between the pit dwellings, which have been dealt with inadequately, and traditional Folk houses in the Korean dwelling history.

• Proceedings of the Materials Research Society of Korea Conference
• /
• 1996.11a
• /
• pp.168-168
• /
• 1996

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2003.07a
• /
• pp.597-600
• /
• 2003

Bi-2223/Ag HTS wires have been fabricated by the PIT(powder in tube)process. Intermediate annealing was carried out to increase the homogenization and uniformity of the superconducting filaments embedded in the silver matrix during the deformation process that is important to sustain the engineering critical current density in long superconducting wire. Intermediate annealing act to release the deformation hardening of the superconducting wires during drawing process. Rolling parameters were investigated to roll the superconducting tapes with uniform thickness, width and winding tensions. Critical current of 60 m long superconducting tapes was measured 54.3 A continuously after final sintering heat treatment. The phase analysis of Bi-2223/Ag superconducting tapes are examined by the XRD.

• Journal of the korean academy of Pediatric Dentistry
• /
• v.33 no.2
• /
• pp.336-347
• /
• 2006

Pit and fissure sealants has been proven as safe and effective method of caries prevention. But improper application of pit and fissure sealant may masking the caries process in occlusal fissure. Dentists have to understand the correct and exact application method of pit and fissure sealant for he good result of caries prevention. A key factor to enhanced the effectiveness of caries prevention is retention of pit and fissure sealant. Deep penetration of material into fissure and least marginal leakage around the fissure orifice are the major concerns for dentists to achieve the successive application of pit and fissure sealants. This paper reviewed the literature on the pit and fissure sealants under the following subtitles for enhanced retention : (1) application timing, (2) Indication, (3) Occlusal prophylaxis, (4) Materials, (5) Penetration, (5) Recall check Dental profession must perform the exact application of pit and fissure sealant because this procedure is one of the most technique-sensitive one in dental field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1996.05a
• /
• pp.198-201
• /
• 1996

In order to investigate control factors to critical current density, Ag sheathed Bi2223 superconducting tapes were fabricated using PIT process. Optimizing the reduction ratio of rolling, critical current density 7f rolled Bi2223 tape could be improved with the value of 15,000 A/$\textrm{cm}^2$(77 K, zero field). The correlation between J$\_$c/ and work inhomogeneity was revealed as a dependence of COV of measured oxide layer thickness.

• Advances in materials Research
• /
• v.4 no.4
• /
• pp.215-226
• /
• 2015

Experiment on roughness and micro pit defects of SUS 430 ferrite stainless steel was investigated in laboratory. The relation between roughness and glossiness with reduction in height, roll surface roughness, emulsion parameters was analyzed. The surface morphology of micro pit defects was observed by SEM, and the effects of micro pit defects on rolling reduction, roll surface roughness, emulsion parameters, lubrication oil in deformation zone and work roll diameter were discussed. With the increasing of reduction ratio strip surface roughness Ra(s), Rp(s) and Rv(s) were decreasing along rolling and width direction, the drop value in rolling direction was faster than that in width direction. The roughness and glossiness were obtained under emulsion concentration 3% and 6%, temperature $55^{\circ}C$ and $63^{\circ}C$, roll surface roughness $Ra(r)=0.5{\mu}m$, $Ra(r)=0.7{\mu}m$ and $Ra(r)=1.0{\mu}m$. The glossiness was declined rapidly when the micro defects ratio was above 23%. With the pass number increasing, the micro pit defects were reduced, uneven peak was decreased and gently along rolling direction. The micro pit defects were increased with the roll surface roughness increase. The defects ratio was declined with larger gradient at pass number 1 to 3, but gentle slope at pass number 4 to 5. When work roll diameter was small, bite angle was increasing, lubrication oil in micro pit of deformation zone was decreased, micro defects were decreased, and glossiness value on the surface of strip was increased.

• Journal of architectural history
• /
• v.17 no.5
• /
• pp.7-22
• /
• 2008

The purpose of this study is to examine the function of wall posts in pit-houses in the Bronze Age, in the Kyung-nam Province. Wall posts were found as post-holes, created after wooden posts had decayed. In this research, the role of wall posts is newly defined from the perspective of a construction engineering. While existing studies in archaeology regard wall posts as sub-posts that support the roof of a pit-house, this study views wall posts as piles installed to support the soil wall, not as sub-posts. Based on the existing reports on excavation in prehistoric settlement sites by archaeologists, the study examines the remnants of the wall posts and remains after a fire. The main findings of this study are threefold. First, the wall posts were installed not as posts but as piles, cut sharply and hammered along the building lines of a pit-house. Second, wall piles were used to support the walls during earthwork, such as excavating and banking for low ground, mostly because a large amount of soil is often lost during the process. Third, wall piles were used as post piles of retaining walls that enabled the installation of transverse wall panels, which were used to prevent the soil loss.