Titanium and its alloys are useful for implant materials. In this study, porous Ti-Nb-Zr biomaterials were successfully synthesized by powder metallurgy using a NH4HCO3 as space holder and TiH2 as foaming agent. Consolidation of powder was accomplished by spark plasma sintering process(SPS) at 850˚C under 30 MPa condition. The effect of high energy milling time on pore size and distribution in Ti-Nb-Zr alloys with space holder(NH4HCO3) was investigated by optical microscope(OM), scanning electron microscope(SEM) & energy dispersive spectroscopy(EDS) and X-ray diffraction(XRD). Microstructure observation revealed that, a lot of pores were uniformly distributed in the Ti-Nb-Zr alloys as size of about 30-100μm using mixed powder and milled powders. In addition, the pore ratio was found to be about 5-20% by image analysis, using an image analyzer(Image Pro Plus). Furthermore, the physical properties of specimens were improved with increasing milling time as results of hardness, relative density, compressive strength and Young's modulus. Particularly Young's modulus of the sintered alloy using 4h milled powder reached 52 GPa which is similar to bone elastic modulus.

To improve coating ability and the life of the coating, Ti based composite materials with hydroxyapatite(HA) should be developed. The raw materials of Ti-26wt%, Nb-1wt%, and Si with 10wt% HA were mixed for 24 h by a mixing machine and milled for 1 h to 6 h by planetary mechanical ball milling. Ti-26%Nb-1%Si-(10%HA) composites, composed of nontoxic elements, were fabricated successfully by spark plasma sintering(SPS) at 1000˚C under 70MPa. The relative density of the sintered Ti-Nb-Si-HA composites using the 24 h mixed powder, and the 6 h milled powder, was 91% and 97 %, respectively. The effects of HA contents and milling time on microstructure and mechanical properties were investigated by SEM and hardness tester, respectively. The Vickers hardness of the composites increased with increasing milling time and higher HA content. The Young's modulus of the sintered Ti-26%Nb-1%Si-10%HA composite using the 6 h-milled powder was 55.6 GPa, as obtained by compression test. Corrosion resistance of the Ti-26wt%Nb-1wt%Si composite was increased by milling and by the addition of 10wt%HA. Wear resistance was improved with increasing milling time. Biocompatibility of the Ti-Nb-Si alloys was improved by the addition of HA.

PURPOSES : The causes of traffic accidents can be classified into the factors of highway users, vehicles, and driving environments. Traffic accidents result from the deficiency in single or combination of these three factors. The objective of this study is to define the "potentially hazardous sections of highway" in terms of traffic safety considering these three factors. METHODS : The test drivers performed repeated driving on these highway sections. The drivers and passengers recorded the sections on which the driving was uncomfortable, and the speeds on the sections excluding the uncomfortable sections were used for the development of the model. RESULTS : The model is composed of three sub-models for each of the horizontal curve, tangent, and the section where the curve starts/ends. The safe driving behavior coefficients by the horizontal curvature were derived by comparing the maximum operating speeds at which the vehicle may slide or deviate and the speeds at which the drivers feel comfort. The safety speeds on tangent were derived by the length of tangent section considering the driver's desired speeds under the traffic condition on which the drivers hardly influenced by the other vehicles. For the sections where the curve starts/ends, the driving behaviors were classified by the distances between the curves, and the safe acceleration/deceleration speeds were derived on which the drivers enter/exit the curve sections safely. CONCLUSIONS : Safety speed could then be regarded that the model suggested in this study may be useful to define the potentially hazardous highway section and contribute the improvement of highway safety.

퉁퉁마디의 약리효과를 규명하기 위하여 퉁퉁마디 추출액을 실험용 동물에 4주간 섭취시키는 실험을 하였다. 대조군은 4주간 145.5g의 체중이 증가한 반면 퉁퉁마디 추출액 20% 투여군은 128.4g의 체중이 증가하였다. 체중증가율은 대조군에서 107.8%이였으며 퉁퉁마디 20% 투여군에서는 95.1%를 보여 대조군에 비해 체중 증가율이 최대 11.8% 낮았다. 혈중 총단백질 함량과 알부민 함량은 대조군과 실험군간 유의적인 차이가 나지 않아 체중 감소에 따른 실험군간의 영양상태는 차이가 없는 것으로 판단된다. 간기능활성도 측정을 위한 GOT와 GPT 값은 각각 126.7~134.1 U/L, 41.1~46.7 U/L로 나타났다. 대조군에 비해서 퉁퉁마디 추출액 투여군의 혈중 콜레스테롤은 유의적(p〈0.05)으로 현저하게 감소하였고 HDL-콜레스테롤은 유의적(p〈0.05)으로 증가하는 경향을 보였다. 대조군에 비해서 퉁퉁마디 추출액 투여군의 혈중 총지질함량과 중성지질함량은 유의적(p〈0.05)으로 감소하는 결과를 얻을 수 있었다. 이상의 결과에서 퉁퉁마디 추출액은 동맥경화, 고지혈증, 지방간 등의 예방효과 뿐만 아니라 체중증가 억제에도 효과가 있을 것으로 판단된다.