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朴春洙,朴修勇,李圭煥 忠南大學校 産業技術硏究所 1990 산업기술연구논문집 Vol.5 No.2
This study presents the results of prediction of rockfill Dam settlements obtained by analysing factotrs influencing Dam settlement. Several predictions such as empirical equations suggested by lawton & lester, Sowers, Soydemir & Kjaernsli, and Speeddie are compared with the observed of settlement for post-construction rockfill Dam. (1) In construction method, dumped rockfill-membrane dam show the highest settlement, compacted rockfill-mmambrane dams show the smallest settlement. (2) Lawton & Lester's equation is considerably fitted with the observed in central core dam but higher than the observed value by 17%. (3) In the case of Sloping core Dam, the predicted in largely, differ from the observed ; Soydemir & Kijaernsli's small than the predicted by 50%, other equation's high than the predicted by 67%. (4) Sower's is very similar with the predicted value of dumped rockfill-membrane dam but higher than the predicted value by 18%. Soydemir & Kjaernsli's equation only agree with compacted rockfill-membrane dam's, other equation's significantly differ from the predicted. (5) The prediction of sttlement by empirical equations cannot use to predict Dam settlmennt without strict classification of dam type so that the equations must be used after deeply consideration of dam type.
이규환,신명철,최부병,Lee, Gyu-Hwan,Sin, Myeong-Cheol,Choe, Bu-Byeong 대한의용생체공학회 1985 의공학회지 Vol.6 No.1
Development of a dental Ni-Cr alloy system for porcelain veneering crown and bridge was studied in this research. The principles of alloy design were a) It should not contain toxic beryllium. b) It should have low melting Point. c) It should be easily ground and polished. d) It should possess an adequate strength to resist the deformational force In the mouth. e) It should be bondable Ivith porcelain by chemically. After investigating the effect of minor elements such as boron and rare earth metals on the mechanical properties of the Ni-Cr alloy system, the compromised ideal composition for dental use was determined. The composition was l9.6%, Cr, 5.6% Mo, 3.4% Si, 1, 0% Fe, 0.01% Ti, 0.5-1.0% B, 0.2-0.6% misch metal, balance Ni. To compare the performance of experimental alloy with commercially available alloys, the properties such as strength, melting point, and bond strength were measured. The results Ivere as follows: a) Boron increases the strength of the alloy but reduces the elongation. b) Misch metal increases the strength when the boron content is low, but does not increase the strength when boron content is high. And it reduces the elongation drastically, c) Mechanical strength of the experimental alloy was not superior to commercially available Be containing alloy, but handling performance such as castability, ease of granting and polishing, and cuttability were superior to the Be containing alloy.
이규환,이창희,신지훈 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.2
Ti and Ti-based alloys have been widely used for the biomedical applications due to their superiorities of biocompatibilty, mechanical properties and corrosion resistance. However, there has been the limiting factor for these metals to show the low affinity to the living bone. The purpose of this study is to improve the bone-bonding ability between Ti-base alloys and living bone through the chemically activated process and thermally activated one. After those treatments, the effects of the pre-treatments on the bonding property were evaluated by in vitro test. Two kinds of Ti-based alloys, Ti-In-Nb-Ta and Ti-6Al-4V, were used in this study. These specimens were alkali treated in 5.0M NaOH solution and heat treated in vacuum furnace at 600℃ and soaked in SBF(simulated body fluid) including nearly same ion concentration as human blood plasma. The microstructural changes of activated surface were observed by OM, SEM, EDS, XRD, and AES. Two surface modified alloys showed improved bioactive behavior. And Ti-In-Nb-Ta had the better bioactivity than Ti-6Al-4V in SBF.
Dynamic Strain Gage를 이용한 제진합금의 제진특성 측정
이규환,조권구,이봉직,심명철,Lee, Gyu-Hwan,Jo, Gwon-Gu,Lee, Bong-Jik,Sim, Myeong-Cheol 한국재료학회 1994 한국재료학회지 Vol.4 No.5
dynamic strain gage와 12bit AD(analog to digital converter)를 이용한 새로운 제진특성 측정 장치를 제작하였다. 이 장치를 이용하여 일반재료와 고제진재료의 제진특성을 연구하였다. 또한 열처리 조건, 초기 진동 진폭, 그리고 내부응력의 변화에 따른 SDC(specific damping capacity)변화에 관하여 연구하였다. 일반재료와 제진재료의 비교에서, 제진재료는 진동을 가한 후 0.4초 이내에 진동 진폭이 거의 사라졌지만, 같은 시간에 일반재료의 진동 진폭은 거의 감소하지 않았다. Fe-16wt. %Cr계 합금의 제진 특성은 노냉일 때 SDC max 가 40%이상이었고, Fe-5.5wt.%Ai합금의 제진 특성은 공냉일 때 SDC max값이 30%이상이었다. 초기 진동 진폭이 증가할수록 최대 제진 특성치는 낮은 진동 진폭 영역으로 이동하였다. 제진 특성은 내부 응력이 증가할수록 급격한 감소를 보였으며, 본 연구에서 개발한 제진측정 장치는 낮은 진동 진폭의 영역에서 정확한 제진 특성 측정이 가능하였다. New damping measurement equipment was designed using the dynamic strain gage and high speed analog to digital signal 12 bit converter and compared it with existing equipment. The damping properties of general material and high damping material were also studied by this machine. The SDC (specific damping capacity) was measured with various heat treatment condition, initial vibration amplitude and internal stress. The vibration amplitude of high damping material is decreased within nearly less than 0.4 second after applying the initial forced vibration. But that of general material is still vibrating at the same time. After furnace-cooling heat treatment, SDCmax of Fe-lGwt.%Cr system was more than 40% and that of Fe-5.5wt.%Al alloy was more than 30% after air-cooling heat treatment. Upon increasing of initial vibration amplitude, it is detected the migration of SDCmax into the region of small vibraton amplitude. Damping capacity is decreased rapidly as the internal stress Increases. Damping measurement equipment in the present study was ahln to give the more accurate results of damping properties in the small vibration amplitude region.