Correlation Between Primary Si and Silicide Refinement Induced by Ultrasonic Treatment of Multicomponent Al–Si Alloy Containing Ti, Zr, V, and P

Jae‑Gil Jung,Young‑Hee Cho,Tae‑Young Ahn,Jae‑Hee Yoon,Sang‑Hwa Lee,Jung‑Moo Lee 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.5

The correlation between primary Si and silicide refinement induced by ultrasonic treatment (UST) of multicomponent Al–Sialloy containing Ti, Zr, V, and P was investigated. UST significantly refined the primary Si phase owing to cavitation-inducedwetting and deagglomeration of MgAl2O4particles. Lowering the UST finish temperature caused deterioration of the degreeof primary Si refinement, instead leading to silicide refinement. Cavitation-induced silicide nucleation on wetted MgAl2O4consumed the MgAl2O4particles, particularly in the case of primary Si nucleation. Similarly, the formation of an AlP phaseon the silicide phase reduced the nucleation efficiency of the AlP phase. Poisoning of the MgAl2O4and AlP phases by thesilicide phase was responsible for the deterioration in primary Si refinement. Room-temperature tensile strength and hightemperatureelongation were increased by UST and were dependent on the size of primary Si.

과량의 방사선에 노출된 흰쥐 소뇌외측핵의 미세구조

정재삼,양남길,안의태,고정식,박경호,김진국 대한해부학회 1992 Anatomy & Cell Biology Vol.25 No.3

Al5083-O 용접부의 보호가스 혼합비율에 따른 저온 인성 평가

이동길,이상열,양훈승,정재강 朝鮮大學校 機械技術硏究所 2002 機械技術硏究 Vol.5 No.1

본 연구에서는 저온용기 등에 많이 사용되고 있는 알루미늄 합금 A15083-O재에 대한 보호가스 혼합비율과 저온인성과의 관계를 규명하고자 혼합가스 비율을 여러 가지로 달리 하여 GMA 용접을 하였다. 시험온도는 상온에서 극저온까지 단계적으로 낮추어가며 계장화 샬피충격시험을 실시하였다. 최대하중은 시험온도가 낮아질수록 증가하였으나 변위는 25℃부터 -85℃까지는 시험온도에 관계가 없었으나 -196℃에서는 크게 감소하였으며, 모든 시험온도 및 불활성가스 혼합비율에서 흡수에너지는 용착금속부, 용융선 및 HAZ 순으로 증가하였다. 용착금속부의 흡수에너지는 시험온도 및 불활성가스 혼합비율에 관계없이 매우 낮게 나타난 반면, 용융선 및 HAZ시험편의 흡수에너지는 모재와 거의 유사한 값을 나타내었다. 또한, 모든 시험온도에서 흡수에너지는 He의 혼합량이 증가할수록 증가하는 경향을 보여 Ar33%+He67%에서 가장 우수한 인성을 나타내었다. In this study, the low temperature toughness was evaluated by using the instrumented Charpy impact testing procedures for A15083-O aluminum alloy used in the LNG carrying and storing tank. The specimens were GMA(Gas Metal Arc) welded with four different mixing shield gas ratios (Ar100% + He0%, Ar67%+He33%, Ar50%+He50%, and Ar33%+He67%), and tested at four different temperatures(+25, -30, -85, and -196℃) in order to investigate the influence of the mixing shielding gas ratio and the low temperature. The specimens were divided into base metal, weld metal, fusion line, and HAZ specimen according to the notch position. From experiment, the maximum load was increased a little up to -85℃, and the maximum load and maximum displacement were shown the highest and the lowest at -196℃ than the test temperatures because of the brittle behavior. The absorption energy of weld metal notched specimens was not nearly depends on test temperature and mixing shield gas ratio because the casting structure was formed in weld metal zone by melting welding wire. In the other hand, the others specimens was shown that the lower temperature, the higher absorption energy slightly up to -85℃ but the energy was decreased so much at -196℃.

ISI 프로토콜에서의 인증에 관한 연구

최길림,이재동,정광민 慶南專門大學 2000 論文集 Vol.28 No.1

접촉각 측정을 통한 Alkanethiol로 표면 처리한 은 분말의 표면 특성 연구

이길재,신승일,오성근 한국공업화학회 2004 공업화학 Vol.15 No.1

은 분말을 alkanethiol로 표면 처리한 후, alkanethiol의 탄소 개수 변화에 따른 은 입자의 표면 특성변화를 접촉각 측정을 통해 연구하였다. 이때 은 입자 표면에 alkanethiol의 흡착여부를 DRIFT (diffuse reflectance infrared fourier transform) spectrum를 통해 확인하였다. 접촉각은 Washburn 식을 바탕으로 한 liquid penetration 방법으로 측정하였고, 이 측정법의 보완을 위해 분말에 압력을 가하여 원판형태로 만들어 그 표면에서 접촉각을 측정하는 sessile drop 방법을 함께 사용하였다. 그 결과 순수한 은 입자의 물에 대한 접촉각은 두 가지 방법에 대해 각각 58°, 40° 나왔고, 다양한 탄소개수(C_(4)-C_(12))의 alkanethiol로 표면 처리한 입자는 모두 90° 이상의 결과를 얻었다. 즉 alkanethiol로 처리한 은 입자의 표면이 소수성으로 변했음을 의미한다. 여기서 처리한 alkanethiol의 탄소개수가 증가할수록 접촉각은 계속 증가했으나, 접촉각의 증가 폭은 상대적으로 점차 감소하였다. Contact angles of silver powders were measured for investigation of surface properties of silver particles as changing alkyl chain length of alkanethiol. Silver powders were modified by various alkanethiol (C4∼C12). Adsorption of alkanethiol on silver particles was confirmed by DRIFT (diffuse reflectance infrared fourier transform) spectrum. Contact angles were measured by liquid penetration method based on Washbum equation and sessile drop method on tablet of compressed powder. In result. the value of contact angles on water were 53°, 40°about two method. Contact angles of surface treated particles by alkanethiol of varied alkyl chain length were larger than 90°. Because of bonding between silver and sulfur in alkanethiol, silver surface was surrounded by alkyl groups of alkanethiol. Surface properties of silver particles were increased on hydrophobicity with alkyl chain length of alkanethiol. In comparison with increase of contact angle accordingto increase of alkyl chain length of alkanethiol. the widths of increasing contact angle were relatively decreased.

可動性關節 捻挫指壓占에 關한 硏究

李栽吉 군산대학교 1993 群山水産專門大學 硏究報告 Vol.27 No.1

The health care consists fo the health exemination, preventive medicine, therapeutics epidemic prevention, first-aid treatment, etc. This thesis studies the first-aid treatment for the bone-inframmation in the joints of the body. Also, this thesis, being on the basis of the acupuncture and moxacatery, studies the treatment effects of the finger-pressure therapy for the bone-inflammation in the shoulder, finger, ankle, and the disjoint of the shoulder as a first- aid treatment.

대청호 대전취수탑 수역에 있어서의 수질특성에 관한 연구

이길영,노장성,허재영 大田大學校 産業技術硏究所 1995 산업기술연구소 論文集 Vol.1995 No.9

In order to survey the cause of the eutrophication in Taechong reservoir, the water body around Taejon intake tower were divided into 5 groups, and the samples were taken to analyse the quality of water, deposits and algae. The relationship between the water quality and the meteorological factors in the study area was investigated and the contamination mechanism in the reservoir was explained. Finally, the relation between T-N concentration and inflow volume was established.

구조용강의 유한요소해석 및 온도변화에 따른 피로수명 평가에 관한 연구

이동길,이상열,정재강 朝鮮大學校 機械技術硏究所 1999 機械技術硏究 Vol.2 No.2

본 연구에서는 국산 승용차의 전륜구동축 재료인 S43C와 S5OC를 대상으로 유한요소해석과 회전굽힘피로실험을 통해 고주파열처리와 온도조건에 따른 피로크랙의 발생, 전파거동을 고찰하였다. 유한요소해석 결과 하중이 가해지는 방향에 따라 반복적으로발생되는 인장응격 및 압축응력은 미소원공결함 부분에서 가장 크게 나타났다. 이러한원인은 미소원공결함이 응력의 국부적인 집중원으로 작용했기 때문으로 생각되며, 이러한 응력의 반복으로 인하여 미소원공결함을 기점으로 크랙이 발생∙성장하였음을 알 수있다. 회전굽힘피로실험 결과 두가지 재료 모두 저온(-3O℃) 피로수명은 비열처리재의 경우 상온(25℃)보다 약 110% 증가하였고, 열처리재는 약 120% 증가함으로서 온도의 저하가 피로수명을 크게 증가시킨 반면 고온(80℃) 피로수명은 상온 피로수명과 비교시 비열처리재가 약 35%. 열처리재가 약 5%의 피로수명 감소를 나타냈다. In this study, the rotary bending fatigue test was carried out with two kind of material, S43C and S5OC, using in the front engine and front wheel drive shaft of vehicle. The specimens were heat-treated by high frequency induction method and tested at room(+25℃), high(+80) and low temperature(-3O℃) in order to look over the fatigue crack initiation and propagation behavior by the heat treatment and the temperatures. Based on the FEM result, the tensile and compressive stress repeatedly generated by load direction were largest on the small circular defect due to the stress concentration. So the small crack was initiated and grew from the defect Fatigue lifts of the specimens tested at low temperature showed about 110% for as-received. 120% for heat-treated higher than at room temperature, It was found that low temperature increased so much the fatigue life. At room and high temperature, the fatigue life of as-received specimens were decreased about 35%, but that of heat-treated specimens were decreased about only 5% at high temperature more than at room temperature, Therefore, fatigue life under high temperature will be considered at design of front engine and front wheel drive shaft materials of vehicle.

전계발광소자용 유기물 초박막의 상거동과 피막특성

신길재,박상권,안택,심홍구 동국대학교 산업기술연구원 2000 산업기술논문집 Vol.11 No.1

최근, 여러 가지 형태의 디스플레이 중 고분자 전계발광 디스플레이(ELD)는 여러 가지 장점 때문에 차세대 디스플레이로서 기대를 모으고 있다. 본 연구에서는 ELD용 적색발광체로서 사용가능한 poly(2-methoxy-5-(2.-ethylhexyloxy)-1,4-phenylene vinylene (MEH-PPV)을 합성하고, MEH-PPV와 전하수송층 단분자막을 공기/물 계면에 형성시켰다. 이 Langmuir 단분자막의 상거동과 EL 소자 양극으로 쓰이는 indium-tin oxide (ITO) glass 상으로의 피막특성을 조사하였다. Recently, polymer electroluminescence display (ELD) of various display techniques has drawn much attention due to its advantages such as fast response, low operation voltage and easy fabrication of huge size device. In this study, we synthesized a luminescence material for polymer ELD, poly(2-methoxy-5-(2-ethylhexyloxy)-1,4 -phenylene vinylene (MEH-PPV). The Langmuir monolayers of charge transport layers as well as the MEH-PPV were formed at the air/water interface. We investigated the phase behaviors and the deposition characteristics into indium=tin oxide substrate of the Langmuir monolayers.

폐Al dust와 폐주물사를 이용한 재료 개발

黃龍吉,金蓮洙,金宰逸 동아대학교 환경문제연구소 1986 硏究報告 Vol.19 No.2

The results of sulphuric acid leaching Aluminium dust and of making hydraulic-setting cement stone using Aluminium dust are as follows. 1. Sulphuric acid leaching efficient of Al is better when concentration of sulphuric acid is 200gr/ℓ, over 60℃, for lhours. 2. The aqueous solution recovered from sulphuric acid leaching of Aluminium dust contains Al^(+3) 13.5gr/ℓ and Fe^(2+) 1.65g/ℓ. 3. The hydraulic-setting cement stone making from mixture of cement, foundry sand, fly ash and Aluminium dust pulp(Na₂O·Al₂O₃) has more compressive strength comparing to other cement stones which make from mixture of cement, foundry sand and Aluminium dust pulp and mixture of cement and sand only. 4. Aluminium dust pulp has rapid hydraulic-setting effect in making cement stone.