• Journal of Korea Foundry Society
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• v.25 no.1
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• pp.23-29
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• 2005

Mechanical characteristics of Hi-Cr cast irons containing 16.8%Cr and 3.0%C were studied with various heat treatments. After as-cast Y-block ingots were annealed fully, the ingots were machined into cylinderical specimens with the size of 9mm in diameter and 20mm in length in order to investigate the effect of heat-treatments on mechanical characteristics of high Cr cast irons. All specimens were heat-treated by quenching- tempering, austempering and cyclic heat at the various temperatures(950, 1000, 1050 and $1100^{\circ}C$) respectively. The wear amount was measured for each heat-treated specimens against the counterpart of a hardened SKD11 steel at the following conditions; wearing velocity: 0.7 m/s, load: 100N and sliding distance: 70 km. After as-cast specimens were annealed, fine $M_{3}C$ carbides were formed, which affected the hardness and the wear resistance of Hi-Cr specimens. High hardness and good wear resistance were appeared on the specimens treated at 950 and $1000^{\circ}C$ and the austempered specimens show excellent wear resistance as well as high hardness.

• Corrosion Science and Technology
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• v.11 no.2
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• pp.48-55
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• 2012

Clamping force of a high strength bolt is reduced by a certain period of time after the initial set-up. In case of special treatments on faying surfaces such as protective coating, clamping force is relaxed more severely. Tests for slip critical joints subject to various faying surface parameters were conducted. Five different surface treatments were tested including mill scale surface, blast surface, rust surface and coated surfaces. Each specimen was composed of F10T M20 of high strength bolts and steel plates. Based on the result of slip coefficient test, blast treatment surface showed 0.59, rust treatment surface showed 0.54 and inorganic zinc treatment surface exhibited 0.44. Clean mill treatment surface and red lead paint treatment surface were 0.23, 0.21 respectively. It is identified that the slip coefficient in Korean structural design guide should be determined for various surface conditions. Subsequently from long term relaxation test of ASTM A 490 high strength bolts, relaxation of no-coated surfaces such as blast, clean mill, rust treatment, the loss of initial clamping load was 10.5%, 13.6% and 7.9% for 1,000 hours, while the loss of initial clamping force was reached as 15.0%, 18.7% more than the required redundancy 10% in case of inorganic zinc and red lead painted treatment. It is required that the limit of relaxation on coated faying surface should be established separately for various surfaces.

• Journal of the Korea Furniture Society
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• v.23 no.4
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• pp.364-371
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• 2012

I designed a dietary life kitchen utensils which is focused by the shape of split bamboo that has meaning of health and safety and the shaman who is the religion and incantation performer, and who solve problems, which are impossible to solve in common methods, by borrowing the power and granting the meaning which is connected with transcendent existence and principal. Having closest relation with human being's diet culture is being changed with adding beauty instead of the part of simple practical aspect in our normal life. I tried to show incantation effect with keeping the characteristic of kitchen utensils by granting the symbolic meaning of shamanism which is the shelter that is projected the desire of human beings. the materials were produced of an ebony and steel and varnished with lacquer for coloring. For hand shape, which is hard to treat in irregular forms, the religious image of shamanism was formed by casting which expresses the touch of an ebony and the cold characteristic of metal. an overall design doesn't detail excessively distort or largely transform the form of dietary utensils, keeps its individuality, and emphasizes the image by figuring a grip part which a human can see and a body can approach. in addition, I try to show a point that shamanism has affected human life for long time and symbolic meaning of bamboo-shape shows health and safety. And these things vest with each dietary life tools and should be the role of enzyme about the effect of human life.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.1
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• pp.9-18
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• 2019

Modular system can be divided into two types based on the methods of resisting load. The one is the open-sided modular system composed of beams and columns. The other is the enclosed modular system composed of panels and studs. Of the Modular systems, the use of open-sided modular system is limited because it consists of closed member sections. In order to solve this problem, Choi et al.(2017) proposed a composite modular system with folded steel members filled with concrete. However, it was assumed in the previous study that the connections between modules are composed of rigid joint. Therefore it didn't identify the effect of connection behavior in structure. This study used finite element analysis to calculate stiffness of the connections in the proposed modular system. The linearization method presented in FEMA 440 is used for seismic performance assessment of structures, considering the connection stiffness computed in this study. The result of analysis shows that the capacity and story drift ratio obtained in the model considering stiffness of connection are less than those in the model not considering connection stiffness. Based on this observation, it is concluded that the stiffness of connection has a considerable effect on structural behavior.