티타늄 및 티타늄합금은 강도/밀도 비가 높고, 내열성, 내부식성, 피로강도가 높기 때문에 지금까지 항공, 우주, 해양 및 화학 장치용 소재로서 많이 사용되어 왔다. 최근, 자동차 산업과 레저용 제품 등의 성능과 효율향상을 위해 항공ㆍ우주 산업이나 특수화학장치 산업에 한정되어 사용되고 있던 티타늄소재를, 이들 산업으로 확대하여 응용하고 있다. (중략)

P/M high speed steels with various Co contents were fabricated by gas atomization and Canning/HIP process. As Co content in P/M high speed steel increased, hardness, transverse rupture strength and yield strength in compressive testing increased due to solid solution hardening of Co in matrix. Especially, PM high speed steels with Co have high deformation resistance to repeated compressive loading.

The purpose of this study is to develop Korean shoe-last based on the conformability of shoe. For this work, the important dimensions for the conformability of shoe were investigated and the systematic methods for evaluating the comfortable shoe were developed. Different two types of shoe-last for men and women were used in the experiment, respectively. 8000 feet dimensions of Korean adults were analyzed for developing standard shoe-last in this study. A total of 10 subjects (ranged from 21 to 25 years old) participated voluntarily. They evaluated each shoes made by developed shoe-last. A rating scale and description was used to express the degree of conformability. Also, 26 feet dimensions were measured using martin-typed gauge and footprint. The relationship between foot dimension and conformability of shoe was analyzed. As a result, Korean standard shoe-last was suggested based on the based on the conformability of shoe. The evaluating methods will be expected to help designer find more important design parameters. We will also expect that the standard shoe-last guarantee the optimal gait and minimal workload, especially in aspect of conformability.

The effect of tempering temperature on the three point bending fatigue behavior of a P/M high speed steel JYPS-23 (1.28% C, 4.20% Cr, 6.40% W, 5.00% Mo, 3.10% V, bal. Fe) was investigated. The number of cycles to failure of the specimen austenitized at drastically increased with increasing tempering temperature. As tempering temperature increased from 500 to , the volume fraction and average size of carbides (MC or M6C) did not significantly changed, while hardness decreased drastically. The reduced hardness is due to the softening of matrix, which increased the resistance of the fatigue crack propagation. For a practical application, powder compacting test were also conducted with the P/M high speed steel punches tempered at 500, 580, and . The number of compacting cycles to failure of the punches also increased with increasing tempering temperature.