• Applied Microscopy
• /
• v.7 no.1
• /
• pp.45-49
• /
• 1977

For obtaining high manganese steel plates, the study has been made on the optimum conditions in melting, forging, rolling and water toughning treatment practices. The optimum water toughning temperature and time was found to be $1030^{\circ}C$ and 30 min. respectively for the plates of 1 mm thickness. The argon atmosphere is very effective for the prevention of decarburization which can be easily occured in open air. There is a close relation between the degree of c 이 d working and the hardess. The greater the cold reduction ratio is, the smaller the grain size is and it results in the increase of hardness. The improvement of tensile and bending properties can be made by the addition of small amount of nickel, chromium and vanadium.

• Journal of the Korean Society for Heat Treatment
• /
• v.2 no.2
• /
• pp.38-45
• /
• 1989

The Cu-Fe permanent magnet were prepared in situ process, which has economic and mass productive merits in producing multi filamentary composites. The purpose of this research was to study the effect of reduction ratio and heat treatment on magnetic property. As the reduction ratio of Cu-Fe wire increased, the filament structure became finer and interfilament distances decreased and the morphology of filament cross section became ribbon shape. As Fe content increased significantly. The coercivity and squareness of Cu-55 wt%Fe composite increased as a reduction ratio became higher, whereas they increased to maximum values at 0.09 mm ${\phi}$ for Cu-30 wt%Fe, and 0.066 mm ${\phi}$ for CU-45 wt%Fe respectively, and decreased for further reduction. The magnetic properties of Cu-Fe composites can be more enhanced by intermediate heat treatment. The best magnetic properties were obtained from Cu-55 wt%Fe composite deformed to 0.054 mm ${\phi}$ and annealed.

• Journal of the Korean Society for Heat Treatment
• /
• v.24 no.5
• /
• pp.262-270
• /
• 2011

Carbide precipitation and dissolution behavior at various temperatures during heat treatment has been studied in STD11 cold working die steel through confocal scanning laser microscopy; dilatometry; and X-ray diffraction analysis. The equilibrium phase diagram and phase fractions with temperature were calculated using a FactSage program. Confocal laser microscopic observation revealed that ${\alpha}$ to ${\gamma}$ transformation temperature is near $800^{\circ}C$; M7C3 carbides melt at $1245^{\circ}C$; and the melting temperature of STD11 is near $1370^{\circ}C$. XRD results indicated that the M23C6 carbides dissolve in the matrix if austenitized at over $1030^{\circ}C$; while the M7C3 carbides remain up to $1200^{\circ}C$ although their amount decreases. The calculated equilibrium phase diagram showed good agreement with experimental results on carbide dissolution and phase transformation temperatures.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2006.05a
• /
• pp.1-4
• /
• 2006

A down construction method is frequently used in these days to reduce popular discontent and to assure sufficient working space at early stage in downtown area. There are two main problems in the existing down construction method. One is a confliction between frame works and excavation works, and the other is a cold joint in retaining wall which is unavoidable due to a sequence of concrete placement and induces a water leakage. Therefore, a new method is needed to overcome these problems. The CWS (buried wale Continuous Wall System) method was developed by authors. By replacing RC perimeter beam with embedded steel wale, the steel frame works of substructure can be simplified and the water leakage can be prevented using continuous retaining wall. Consequently, the improved duality and reduction of construction period can be obtained from CWS method.

• Nuclear Engineering and Technology
• /
• v.30 no.3
• /
• pp.262-272
• /
• 1998

The experiences and causes of pressure tube cracking accidents in the CANDU reactors and the development of the fuel channel at AECL(Atomic Energy Canada Limited) have been described. Most of the accidents were caused by Delayed Hydride Cracking(DHC). In the cases of the Pickering units 3&4 and the Bruce unit 2, excessive residual stresses induced by an improper rolled joint process played a role in DHC. In the Pickering unit 2, cracks formed by contact between the pressure and calandria tubes due to the movement of the garter spring were the direct cause of the failure. To extend the life of a fuel channel, several R&D programs examining each component of the fuel channel have been carried out in Canada. For a pressure tube, the main concern is focused on changing the fabrication processes, e.g., increasing cold working rate, conducting intermediate annealing and adding a third element like Fe, V, and Cr to the tube material. In addition to them, chromium plating on the end fitting and increasing wall thickness at both ends of the calandria tube are considered. There has also been much interest in the improvement of fuel channel performance in our country and several development programs are currently under way.

• Proceedings of the SAREK Conference
• /
• 2008.06a
• /
• pp.1267-1272
• /
• 2008

OTEC power plants are studied as a viable option for the supply of clean energy. In this paper, the thermodynamic performance of OTEC system was calculated. The results show that the working fluids such as R32 and R125 would be alternatives based upon cutting down the system size, environmental preservation, and conditions without having a severe penalty in efficiency. the initial cost significantly. The regeneration system increase in energy efficiency, and the system can generate electricity when the difference in warm and cold seawater inlet temperatures are greater than $15^{\circ}C$. Also, the system efficiency of OTEC power plant using the condenser effluent from nuclear power plant instead of the surface water increased about 2%.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2007.10a
• /
• pp.322-325
• /
• 2007

Precipitation characteristics of the Fe-36Ni based high strength Invar alloy for power transmission wire was investigated in this study. High strength can be obtained in this alloy through solution hardening, precipitation hardening and strain hardening by cold working. In the present study, ingots of Fe-36Ni based Invar alloys with the contents of C, Mo and V varied. Microstructure observations by OM, SEM, and TEM were carried out to validate the simulation results. BCC phase and $FeNi_3$ phase are also expected at lower temperatures below $500^{\circ}C$. Aging treatments were carried out at temperatures ranging from 400 to $900^{\circ}C$ for time intervals from 3 min to 100hrs. Peak aging condition was obtained as $400^{\circ}C$ and 1 hr. With temperature increased, peak strength was decreased abruptly. Microstructure observation was conducted by optical microscopy, scanning electron microscopy, and transmission electron microscopy.

• Fire Science and Engineering
• /
• v.25 no.6
• /
• pp.98-103
• /
• 2011

Currently, domestic architecture has applied the building fire-fighting equipments to most buildings except conventional houses, villas and facilities, and so on. However, the use of fire-fighting equipments what are not working properly result in a human life and property damages consistently like a fire of Icheon warehouse facilities, Korea cold storage, the tragic incident of subway in Daegu and the recent issue of a fire in the high-rise efficiency apartment, etc. In this study, I'm trying to seek solutions by taking research on the actual condition of fire alarming system, fire escaping equipment, Indoor Fire Hydrant Installation.

• The KIPS Transactions:PartD
• /
• v.9D no.1
• /
• pp.135-144
• /
• 2002

Multimedia systems design generally requires a collaborative effort from a group of designers with a variety of backgrounds and tasks, such as content experts, instructional designers, media specialists, users, and so forth. The fact that the designers have totally different backgrounds and tasks may hinder their collaboration. This research develops a collaborative design tool for multimedia systems design, called the Designer's Cafe, with which multimedia designers can share their design knowledge on the Web freely. Designer's Cafe consists of three intelligent agents that are designed for supporting collaboration activities of multimedia designers. The intelligent agents are implemented by using JAVA SCRIPT and COLD FUSION. By using the tool, designers create, revise, and share their knowledge/ideas in very structured ways. The structured design process might enhance the collaboration activities of designers while designing a multimedia system within a virtual working space.

• Journal of the Korea Institute of Building Construction
• /
• v.6 no.2 s.20
• /
• pp.81-89
• /
• 2006

A down construction method is frequently used in these days to reduce popular discontent and to assure sufficient working space at early stage in downtown area. There are two main problems in the existing down construction method. One is a confliction between frame works and excavation works, and the other is a cold joint in retaining wall which is unavoidable due to a sequence of concrete placement and induces a water leakage. Therefore, a new method is needed to overcome these problems. The CWS (buried wale Continuous Wall System) method was developed by authors. By replacing RC perimeter beam with embedded steel wale, the steel frame works of substructure can be simplified and the water leakage can be prevented using continuous retaining wall. Consequently, the improved qualify and reduction of construction period can be obtained from CWS method.