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.

외상성 대장 및 직장 손상

김익용,김상희,윤광수,김히욱 대한대장항문학회 1997 Annals of Coloproctolgy Vol.13 No.3

Comb Transducer를 이용한 파이프 내 유도초음파 모드의 거동에 관한 연구

박익근,김용권,조윤호,안연식,조용상 한국비파괴검사학회 2004 한국비파괴검사학회지 Vol.24 No.2

발전설비의 보수검사에 적용하기 위한 예비 연구로 comb transducer를 이용한 파이프 내에서의 유도초음파 모드의 거동을 실험적으로 검증하였다. 유도초음파의 모드식별은 STFT와 WT에 의한 시간-주파수해석을 통하여 최적의 모드를 선정하였다. 시간-주파수해석과 이론적 해석 방법인 분산 곡선을 비교한 결과 잘 일치함을 알 수 있었으며, pitch-catch법과 선단부로부터 반사된 신호를 모두 분석한 결과 L(0,1) 모두가 다른 모드에 비해 모드변화에 의한 영향이 적었다. 따라서 L(0,1)을 최적의 모드로 선정하고, 결함위치를 추정한 결과 유용함을 알 수 있었다. A preliminary study of the behavior of ultrasonic guided wave mode in a pipe using a comb transducer for maintenance inspection of power plant facilities has been verified experimentally. The mode identification has been carried out in a pipe using the time-frequency analysis methods such as the wavelet transform(WT) and the short time Fourier transform (STFT), compared with theoretically calculated group velocity dispersion curves for longitudinal and flexural modes. The results are in good agreement with analytical predictions and show the effectiveness of using the time-frequency analysis method to identify the individual modes. It was found out that the longitudinal mode(0,l) is less affected by mode conversion compared with the other modes. Therefore, L(0,l) is selected as an optimal mode for the evaluation of the surface defect in a pipe.

위암의 세포유전학적 분석

정용욱,장성익 啓明大學校 醫科大學 1994 계명의대학술지 Vol.13 No.4

In order to find out the specific chromosomal abnormalities of the gastric adenocarcinoma in Korea, author investigated one primary and two cell lines of gastric cancer with G-banding technique. All tumor cells had clonal chromosomal abnormalities : total 101 numerical and 25 structural karyotypic abnomalies were identified. The most prominent and recurring numerical abnonormalities were trisomy 1, 2, 3, 6, 9, 10, 16, X and tetrasomy 1, 7, 9, 18, 20, 21 and recurrent structural abnormalities were del(1) (q32 →qter), del(1)(p34 →qter), del(3)(p25 →qter), der(4)(4 : 1)(q32 : qter), del(10)(p13 →pter) del(X)(p22). The above results of wide variety of karyotyping in stomach cancer cells indicate that these are general due to secondary changes rather than primary changes specific to stomach cancer cells and also the break at bands 1p34, 2p24, 3p25, 4p14, 5q34, 6p11, 8q24, 11p15, 11q23 give rise to the deletion of cellular oncogenes fgr, src-2, N-myc, rafl, raf2, fms, K-rasl, myc, abl, H-ras1.

방울토마토의 揷木苗를 利用한 송이培地 養液裁培에 있어서 收良에 미치는 湛液 水立의 영향

張田益,金龍湖 濟州大學校 亞熱帶農業硏究所 1992 亞熱帶農業硏究 Vol.9 No.-

재배면적의 증가될 것으로 예상되는 방울토마토에 있어서 그 종자구입의 어려움을 덜고, 또 육묘기간의 단축을 위하여 揷木苗의 이용이 중요과제라 생각되어 Pepe, Pico, Yellow Pico 및 Petit 4품종의 측지를 삽목육모하고, 火山礫인 송이를 培地로 한 養液栽培方法으로 실시한 시험결과를 요약하면 다음과 같다. 1. 養液의 給液水位에 따른 방울토마토의 收量, 形質에는 영향을 주지 않았고 특히 糖度(Brix)도 水位에 따른 差異가 인정되지 않았다. 2. 방울토마토 品種은 Pepe와 Pico가 早熱이면서 多收性이었고 Yellow Pico와 Petit는 다소 늦게 收穫期에 이르렀으며 收量도 적은 편이었다. 3. 糖度 (Brix)는 Pepe와 Picod에서 높은 數値를 보였고 Yellow Pico와 Petit는 낮은 경향이었다. 4. 당도를 높이기 위해서는 송이 培地의 理化學的 特性을 면밀히 조사 분석하고 이를 고려하여 養液의 排液間隔을 조절한다면 可能할 것으로 思料된다. The cuttage seedlings could be used for production of cherry tomato whose acreage was expected to increase. Considering seed cost and reduction of nusery period, evaluated the effects of flooding height of nutrient solution in Scoria medium culture on yield and the other characteristics of cherry tomatoes grown using cuttage seedlings. The results obtained are summarized as follows; 1. The fruit yield and sugar concentration (Brix Scale) including the other characteristics were not by the flooding height of nutrient solution. 2. Compared to "Yellow pico" and "Petit", "Pepe" and "pico" matured earlier and high yielding cultivars. 3. Sugar concentration in "Pepe" and "Pico" was higher than in "Yellow pico" and "Petit". 4. Sugar concentration of fruit juice could be increased by controlling drainage interval of nutrient solution considering physical and chemical characteristics of Scoria

아토피 피부염(Ⅱ)

신영익,김재홍 한국의학사 1999 診斷과治療 Vol.19 No.6

크레인의 능력을 고려한 MOB 자동창고 시스템의 저장과 불출정책

조용환,손권익 江原大學校 産業技術硏究所 1996 産業技術硏究 Vol.16 No.-

This paper deals with storage and retrieval policies for S/R machine with capacity constraints in Man-On-Board AS/RS. It is assumed that storage sequence is based in SFC(spacefilling curve) routine and that storage layout is dedicated by storage policies. We present several heuristic algorithms for storage and retrieval policies which minimize total distance travelled by the S/R machine. These algorithms are based on COI.group COI, frequency of order, similarity between items and capacity of S/R machine. Experimental results of 24 combinastorial policies are provided to illustrate the performance of the heuristics under various rack utilization ratio. In storage policies, the results show that algorithms considering both similarity and frequency are better than those with COI as rack utilization is increasing. And algorithm using group COI is superior to others. In retrieval policies, the method with revision expression is shown to be better than others.

아토피 피부염(Ⅰ)

신영익,김재홍 한국의학사 1999 診斷과治療 Vol.19 No.5

한국인 양극성 장애와 5-HT_2A Receptor Gene Promoter-1438A/G Polymorphism과의 연관성 연구

오승용,지익성,이영호 대한신경정신의학회 2001 신경정신의학 Vol.40 No.1

연구목적: 최근 5-HT□수용체 유전자 promoter의 -1438A/G 다형성이 보고되었고, 이러한 -1438A/G 다형성이 기분장애와 연관이 있는지 알아보려는 연구가 시도되고 있다. 저자 등은 -1438A/G 다형성이 한국인 양극성 장애의 발병에 있어서 유전적 요인으로 작용하는지 알아보기 위하여 본 연구를 시행하였다. 방법: 양극성 장애 환자 120명과 정상 대조군 120명을 대상으로 중합효소 연쇄반응을 이용하여, 5-HT□ 수용체 유전자 promoter -1438A/G 다형성의 유전자형과 대립유전자의 빈도를 비교하였다. 결과: 1) 양극성 장애 환자군의 5-HT□수용체 유전자 promoter -1438A/G 다형성의 유전자형은 A/A 14(12%), A/G 66(55%), G/G 40(33%), 정상 대조군의 유전자형 A/A 30(25%), A/G 59(49%), G/G 31(26%)로 양군간에 유의한 차이가 있었다. 2) 대립유전자의 빈도는 양극성 장애 환자군에서 A 0.39, G 0.61, 정상대조군에서 A 0.49, G 0.51로 양군간에 유의한 차이가 있었다. 결론: 5-HT□ 수용체 유전자 promoter -1438A/G 다형성이 한국인 양극성 장애의 발병과 연관이 있을 수 있다는 가능성을 제시한다. Objectives : This study was designed to investigate the association between 5-HT□ receptor gene promoter -1438A/G polymorphism and bipolar disorder in a Korean population. Methods : 5-HT□ receptor gene promoter -1438A/G polymorphism were typed with Po-lymerase Chain Reaction in 120 patients with bipolar disorder and 120 normal controls. Results : The distributions of the genotype in the bipolar disorder with A/A, A/G, G/G were 14(12%), 66(55%), 40(33%), and in the controls were 30(25%), 59(49%), and 31(26%). The allele frequencies of the bipolar disorders with A and G were 94(39.2%), 146(60.8%), and in the controls were 119(49.6), and 121(50.4), respectively. There were significant differences in genotype distributions and allele frequencies of -1438A/G between patients with bipolar disorder and normal controls. Conclusion : These results suggest that 5-HT□ receptor gene promoter -1438A/G poly-morphism may be related to the development of bipolar disorder in a Korean population.

대화 텍스트의 분석을 위한 방법과 절차 : 텔레비젼 드라마 속에 나타난 협의대화를 예로

박용익 연세대학교 인문과학연구소 2004 人文科學 Vol.86 No.-