Study on Microstructure and Mechanical Properties of the Al–25Cr–5Si (at%) Alloy Powder Using Gas-Atomization and SPS Process

Yong‑Ho Kim,Hyo‑Sang Yoo,Jeong‑Han Lee,Ik‑Hyun Oh,Hyun‑Kuk Park,Hyeon‑Taek Son 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

In order to investigate the microstructure and mechanical properties on Al–25Cr–5Si (at%) alloy, a mixed powder with pureelements and an alloy powder using a gas atomization process were used. Fine and high purity Al–25Cr–5Si (at%) alloypowder was successfully prepared by gas atomization and densified using a spark plasma sintering (SPS) process. The overallpowder size distribution of the mixed Al, Cr, and Si elemental powders was in the range of 10–15 μm. The atomized Al–Cr–Sialloy powder was fine and spherical in morphology and difficult to be formed by intermetallic formation. Densification wasclearly confirmed at 1000 °C, with almost isolated pores formed, by clear removal of pores between particles, deformationof particles, an increase in the number of contacts, and a change in size between particles. As a result of XRD analysis ofthe sintered compacts, single phase was observed using the mixed powder, but the compact using gas atomization remainedthe alloy phase even at the process temperature. The Vickers hardness of the compacts by mixed powder was observed at59.70 Hv and the compact using gas atomized powders on the temperature 1000 °C of the Vickers hardness increased to702.6 Hv. The compressive yield strength of the compact with mixed powder was 195.24 MPa and the compressive strengthof the compact with gas atomized powder increased to 802.07 MPa. It is considered not to be decomposed by the AlCrSi,Al13Cr4Si4and Al8Cr5phases sintering process, resulting from the improvement of mechanical properties.

초생재배에 관한 연구

이용하,정삼택 慶北大學校 生産技術硏究所 1970 生産技術 Vol.4 No.-

The results of sod culture from 1968 to 1969 can be summarized as follows: 1) In weed plot, the average soil temperature was 21.2℃ under the Roll's janet tree while the average temperature of orchard grass plot was 22.3℃. Red clover plots under and immediately surrounding Jonathan tree had the highest average soil temperature. The average temperature was 2-3℃ lower during the second year than the first year. The temperature of the control plot was 1 to 2℃ higher than that of the sod plot. The soil moisture content beneath Roll's janet tree was 49.0%, while the moisture content beneath Jonathan tree was 44.4%, both of which represent an 8% increase over last year. At the same time the orchard grass plot had a higher soil moisture content than both Roll's janet and Jonathan. 2) The fresh weight of the sod produced was the highest in the Ladino clover plot at Roll's janet and Jonathan orchards, whose sod fresh weight were 110.6Kgr and 113.7Kgr respectively. The fresh weight increased three times this year over last year. 3) Shoot elongation was the longest in the Ladino clover plot at 86.1㎝ while the control plot which showed the longest elongation in 1968 was retarded severely in 1969. 4) Due to the cutting of the sod, N.P. and K were increased but after one month the total content of N.P.and K decreased because of absorption of these elements by the tree. 5) Organic materials were highest in the Ladino clover plot of both the Roll's janet and Jonathan orchards, 1.82% and 2.28%, about 0.5-1.0% higher than the control plot. * Sod culture was better than clean-tillage culture for the following reasons. 1) The soil temperature of the sod plot was higher than the control plot by 1-2℃. 2) The sod plot contained 8% more moisture than control plot. 3) Shoot elongation of the sod plot was longer than that of the control plot. 4) There was more N.P. and K in the sod plot than control plot. 5) There was 0.5-1.0% more organic materials in the sod plot than in the control plot. * Comparision of the results between the sod and weed plot: 1) The sod plot was 2-3% higher in moisture content than the weed plot. 2) The sod plot produced 10-30kgr more weight of sod than the weed plot. 3) Shoot elongation of the sod plot was 5-8㎝ longer than the weed plot. 4) N.P. and K elements were 0.5-1.0% higher in the sod plot than in the weed plot. 5) Accumulation of organic materials in the soil was 0.5-1.0% higher in the sod plot than in the weed plot.

전해응집공정을 이용한 염색폐수의 처리

이용택,한승우,조영개,이현문,김태근,손인식,양병수 한국환경과학회 2000 한국환경과학회지 Vol.9 No.4

This research studied the characteristics and applicability of electrocoagulation using aluminium electrode for the color and COD removal in textile wastewater. Electrocoagulation reactor used two different electrode, Fe and Al, since in the general chemical wastewater treatment, aluminium and ferrous salts were used as coagulants. Aluminium electrode showed higher removal efficiency of color and COD than ferrous electrode did. The COD and color removal efficiency improved at the 0.192A/dm^2 current density. Thus, the electrocoagulation process with bipolar aluminium electrode showed better efficiency in the decolorization and COD removal rate of textile wastewater effluent than custom coagulants did.

경막내 척수 섬유지방성 과오종 치험 1례 - 증 례 보 고 -

이용근,조준,문창택,장상근 대한신경외과학회 1998 Journal of Korean neurosurgical society Vol.27 No.10

설계추진단계별 설계VE의 효율적 적용 방안

이승훈,서용칠,구교진,현창택 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.1

The purpose of this study is to propose an efficient design-VE job plan and applicable methods in each phase of design process. This is for more effective and practical use of VE in design phase. This study focuses on differences of the VE target selection phase and function analysis phase in each phase of design process. In the phase of preliminary design, conceptual sketch, size, use, or major spaces of project are selected for VE target and function assessment step is skipped because present cost and function cost cannot be produced easily in early in early phase of design. At the end of preliminary design phase, function review phase is added which consists of function satisfactory indices review step and unsatisfactory function removal step.

졸-겔법에 의한 Mullite 코팅막의 제조 및 특성에 관한 연구

이용택,최영우,양중식 慶熙大學校 材料科學技術硏究所 1997 材料科學技術硏究論集 Vol.10 No.-

출발원료로 알루미늄 세크 부톡사이드(ASB)와 테트라 에톡시실란(TEOS)을 사용하는 졸-겔법에 의해 뮬라이트 조성의 졸 용액을 제조하고, 지지체 표면위에 침지 시간의 변화에 따라 코팅을 실시하였다. 그 결과 뮬라이트 결정화를 위해서는 1,300℃이상의 열처리 조건으로 균열 없는 뮬라이트 코팅막을 제조하는 것이 가능하였으며 침지시간에 따라 코팅막의 두께가 선형적으로 증가하고 평균 기공의 크기는 20∼30Å까지 기공 제어가 가능하였다. Optimal Mullite sol was synthesized by sol-gel process using Aluminium sec-butoxide(ASB), Tetraethoxy-silane(TEOS) and then, Mullite films were dip-coated with various holding time in sol bath and heat-treated at 1300℃ above for crystallization. The thickness of coated film increased linearly with holding time in sol bath and average pore size was controllable within 20-30Å.

쇄골 골절에서 지연성 상완 신경총 마비 : 1예 보고 A Case Report

이우석,정환용,전택수,김용상,김남현 대한골절학회 2003 대한골절학회지 Vol.16 No.2

상완 신경총 마비는 쇄골 골절 후에 매우 드물게 발생하며, 대부분 많은 가골 형성을 동반한 쇄골의 중간1/3 부위 골절 불유합에서 발생한다. 골절의 치유 과정에서 과형성된 가골이 상완 신경총을 압박할 수 있으며, 감압술고 불유합에 대한 수술적 치료를 필요로 한다. 이에 저자들은 쇄골 골절 후 불유합과 과도한 가골 형성에 의해 발생된 지연성 상완 신경총 마비 환자를 치험 하였기에 보고하는 바이다. The brachial plexus palsies secondary to nonunion of the clavicle fracture are extremely rare. The nonunions are hypertrophic and usually in the middle third of the clavicle. Hypertrophic callus produced healing process will cause a compression of the neurovascular bundle. This lesion requires operative treatment for decompression of the brachial plexus and internal fixation of nonunion. We present a case of delayed brachial plexus palsy due to nonunion and excessive callus formation of a clavicular fracture.

유전율이 다른 두 마이크로스트립 기판 접합에 의한 불연속의 해석 : 3차원 유한차분-시간영역 방법에 의한 접근

이용택,전중창,심재륜,김태수 위덕대학교 부설 전자기술연구소 1999 전자기술연구소 논문집 : 위덕대 Vol.3 No.1

본 논문에서는 3차원 유한차분 시간영역 방법을 사용하여 유전율이 서로 다른 마이크로스트립 기판의 접합 불연속 효과를 해석하였다. 본 논문에서 구현된 FDTD 알고리듬의 정확성을 검증하기 위해서, step-in-width 불연속 해석 결과를 상용 CAD 소프트웨어 시뮬레이션 결과와 비교였으며, 18 GHz까지의 주파수 범위에서 두 결과가 잘 일치하였다. 유전율이 서로 다르더라도 특성 임피던스가 동일하도록 도체 폭이 조절되면 반사계수가 -33 dB이하로 매우 낮아지며, 유전율이 서로 다르면서 도체 폭이 균일 한 경우에는 step-in-width 불연속 효과와 비슷한 결과가 얻어졌다. 유전율이 서로 다른 마이크로스트립 기판 접합에 의한 불연속 효과는 마이크로파 회로 모듈 패키징(packaging), 안테나 피더(feeder) 등의 설계에 적용될 수 있다. In this paper, we have analysed the junction of microstrip substrates having different permittivities using the 3-dimensional finite-difference time-domain (FDTD) method The accuracy of the FDTD application is validated by the comparison between FDTD results and commercial CAD software simulation results for a conventional step-in-width discontinuity. The FDTD results for the junction of microstrip substrates having different permittivities reveal that the reflection coefficient can be very small as below -33 dB only if the widths of metal strips are adjusted so that characteristic impedances of both sides are uniform. Also, it is shown that the junction with a uniform strip width has a similar characteristics as a step-in-width discontinuity. The simulation results presented at this paper can be applied to microwave circuit packaging and antenna feeder circuits.

포트폴리오 收支論的 國際收支 調整 理論小考

李鐘燮,林龍澤 군산대학교 산업개발연구소 1987 産業開發硏究 Vol.6 No.-

세라믹막을 이용한 포도당 농축

이수은,이시철,이용택 경희대학교 산학협력기술연구원 1999 산학협력기술연구논문집 Vol.5 No.-

Aqueous glucose solution was concentrated using ceramic membrane in this study, the effects of volumetric concentration factor(VCF) were investigated on the change of flux and the transmembrane pressure(TMP). VCF was increased with the increase in operating time. The permeate flux was reduced as VCF became higher. The permeate flux was sharply decreased at about 18 of VCF, and the flux was not increased any more even in increase of TMP