Effect of Ultrasonic Melt Treatment on Solidification Microstructure of Al–5Ti–1B Alloy Containing Numerous Inoculant Particles

Soo‑Bae Kim,Jae‑Gil Jung,Young‑Hee Cho,Su‑Hyeon Kim,Kwangjun Euh,Jung‑Moo Lee 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.7

The effect of ultrasonic melt treatment (UST) on the solidification microstructure of an Al–5Ti–1B alloy containing highvolumefractions of Al3Tiand TiB2particles is investigated for various UST times with different melt holding times. Theas-cast Al–5Ti–1B alloy is composed of TiB2and polygonal Al3Tiparticles (present prior to UST), plate-like Al3Tiparticles,and Al grains (formed during UST and/or solidification). The UST causes a size reduction and homogeneous distributionof the TiB2-agglomerated region containing many submicron-sized TiB2particles pushed to the grain boundaries. The USTslightly decreases the size and improves the distribution of polygonal Al3Tiparticles enriched in the TiB2-agglomeratedregion. Unlike the TiB2and polygonal Al3Tiparticles, which exhibit a minor refining effect, the plate-like Al3Tiparticlesshow a significant refinement with UST application. The UST has a significant effect on the size distribution of Al grains byinducing the formation of medium-sized grains at the expense of small and large grains; however, it only has a slight effecton grain refinement. The degree of microstructure modification increases with increasing UST time but decreases with meltholding time after UST. The mechanisms for the refinement and dispersion of the TiB2and Al3Tiparticles and Al grains arediscussed considering fragmentation, nucleation, and growth behaviors induced by the UST and subsequent solidification.

Microstructure‑Strengthening Interrelationship of an Ultrasonically Treated Hypereutectic Al–Si (A390) Alloy

Soo‑Bae Kim,Young‑Hee Cho,Jae‑Gil Jung,Woon‑Ha Yoon,Young‑Kook Lee,Jung‑Moo Lee 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.6

Ultrasonic melt treatment (UST) was applied to an A390 hypereutectic Al–Si alloy in a temperature range of 750–800 °Cand its influence on the solidification structure and the consequent increase in strength was investigated. UST at such a hightemperature, which is about 100 °C above the liquidus temperature, had little effect on the grain refinement but enhanced thehomogeneity of the microstructure with the uniform distribution of constituent phases (e.g. primary Si, α-Al and intermetallics)significantly refined. With the microstructural homogeneity, quantitative analysis confirmed that UST was found tosuppress the formation of Cu-bearing phases, i.e., Q-Al5Cu2Mg8Si6, Al2Cuphases that form in the final stage of solidificationwhile notably increasing the average Cu contents in the matrix from 1.29 to 2.06 wt%. A tensile test exhibits an increasein the yield strength of the as-cast alloy from 185 to 208 MPa, which is mainly associated with the solute increment withinthe matrix. The important role of UST in the microstructure evolution during solidification is discussed and the mechanismcovering the microstructure-strengthening interrelationship of the ultrasonically treated A390 alloy is proposed.

점토굴착 사면의 거동에 관한 원심모형실험 및 수치해석

최민수,정길수,박병수,유남재 강원대학교 산업기술연구소 2005 産業技術硏究 Vol.25 No.B

This paper is the results of experimental and numerical works on analyzing the geotechnical engineering behavior and characteristics of excavated clay slope formed by the method of excavated replacement which is one of treatments in soft soil ground. For the centrifuge model tests, models of excavated clay slope were prepared by remolding the marine clayey soil sampled from the field. Tests were performed with changing the slope to investigate the behavior of them. On the other hand, numerical analyses were carried out to analyze the change of safety factor against instability of slope with time. Changes of pore water pressure, shear strength and displacement were also investigated. As results of centrifuge model tests with slopes of 1:1.5 and 1:3 using the confining body of simulating the effect of excavation, for the case of 1:1.5, slope failure occurred right after remove the confining body whereas relatively small displacements within the range of 3.2mm, implying to maintain the stability of slope, were observed for the case of 1:3 slope. From the results of numerical analyses using the software of PLAXIS to investigate the stability of slope after excavation, the minimum safety factor against slope failure was 1.28 for the case of 1:3 slope. The further researches in the future are required with considerations of build up of static pore water pressures during acceleration of centrifuge, depth of excavation influencing the behavior of the slope and permeability of the slope since excavation of the slope was not simulated well resulted from the limitations of apparatus at the stage of excavation during the centrifuge tests.

모래다짐말뚝과 널말뚝으로 처리된 연약점토지반의 거동

유남재,정길수,박병수,김경수 강원대학교 산업기술연구소 2006 産業技術硏究 Vol.26 No.B

Centrifuge model experiments were performed to investigate the confining effects of the sheet piles, installed to the sides of soft clay ground treated with sand compaction piles, on the bearing capacity and concentration ratio of composite ground. For the given g-level in the centrifuge model tests, replacement ratio of SCP and the width of surcharge loads on the surface of ground with SCP, the confining effects of installing the sheet piles on the edges of SCP ground on the bearing capacity, change of stress concentration ratio and failure mechanism were investigated. Kaolin, one of typical clay mineral, and Jumunjin standard sand were used as a soft clay ground and sand compaction pile irrespectively. As results of experiments, lateral confining effect by inserting the model sheet piles fixed to the loading plate was observed. For the strip surcharge loading condition, the yielding stress intensity in the form of the strip surcharge loads tends to increase with increasing the embedded depth of sheet piles. The stress concentration ratio was found not to be influenced consistently with the embedded depth of sheet piles whereas the effect of stress intensity on stress concentration ratio shows the general trend that values of stress concentration ratio are relatively high at the initial stage of loading and tend to decrease and converge to the certain values. For the failure mechanism in the case of reinforced with sheet piles, displacement behavior related to the punching failure, settlement right beneath the loading plate occurred since the soil was confined with sheet piles, was observed.

계약에 대한 8세기 예언자들의 침묵 : 아모스 호세아를 중심으로

서길원 목원대학교 신학연구소 1997 신학과 현장 Vol.7 No.-

아모스나 호세아는 ‘계약’이나 ‘율법’에 관하여 침묵한다. 그들이 이스라엘의 파멸을 선포한 것은 계약의 파괴 때문이 아니고, 이스라엘이 야훼의 구원행위를 잊어버리고 진실하게 사랑하지 못했기 때문이다. 예언자들은 야훼와 이스라엘의 관계를 법적인 계약관계로 보지 않고 ‘역동적인 사랑의 관계’로 파악했다. 이와 같은 예언자 운동이 있은 후에 깨어진 야훼와의 관계를 회복하고 재정립하기 위해서 야훼와 이스라엘의 관계를 법적인 계약의 관계로 이해하고 이 계약을 유지하기 위해 이스라엘 백성들이 지켜야 할 기본적인 지시와 규정이 정리되어 율법서가 되었다. 이런 면에서 예언자들은 고대 계약이나 율법 전통에 서서 그것을 해석한 사람들이 아니고 도리어 깨어진 관계를 회복하고 새롭게 긍정적인 관계로 나아가도록 길을 열어준 자들 즉 6-7세기에 등장한 계약 및 율법사상이 있게 한 자들이다. 계약사상의 출현은 8세기 예언자들의 멸망선언 이후, 이들의 예언이 적중되어갈 무렵, 즉 이스라엘의 야훼신앙이 완전한 위기에 처하게 되었을 때 새로운 가능성과 희망을 위해 나타났다. 국가 멸망에 처한 이스라엘은 절망하거나 야훼를 원망하거나 포기하지 않고 새로운 가능성을 모색하였는데 그것이 바로 계약신학이다. 이로써 이스라엘은 예언자들에게 정당성을 부여하고 또 자신들은 새로운 가능성을 갖게 된 것이다. 이처럼 계약 신학의 발견은 위기극복을 위한 야훼 하나님의 또 한번의 은총의 사건이었고 8세기 예언자들은 이 은총이 나타나도록 길을 열어 준 사람들이다.

算術平均에 의한 바닥衝擊音 遮音性能 評價에 관한 硏究

장길수,남기봉,문연준 東新大學校 1999 論文集 Vol.11 No.-

It is known that arithmetic mean values of impact sound have an unexpectedly high correlation with the loudness of the sound. This measure is simple and much more easily obtained than the measures specified in tile existing standards. This finding was obtained by psycho-acoustic experiments, however, not by field experiments. This paper aims to specify the relationship between this measure and existing measure, L value by JIS A 1419, and to review the proper range of frequencies to be considered by using 63 data of actual impact sounds for domestic floors. As a result, arithmetic mean values of sound levels showed good correlation with L values. And mean values in octave bands from 125 to 2㎑ were proper for light weight impact sound and those from 125 to 2kH were proper for heavy weight impact sound. In addition it was found that L values(by JIS A 1419) estimated from same floor could be underestimated compared to arithmetic values.

쇄석의 진동다짐 특성에 관한 실험적 고찰

정길수,박병수,홍영길,유남재 江原大學校 産業技術硏究所 2004 産業技術硏究 Vol.24 No.B

This Study is results of experimental works to investigate the characteristics of vibro-compaction of crushed stones having coarse grain sizes. For testing material, crushed stone, sieved within very narrow ranges of grain size distribution, was used. Cyclic loading apparatus was used to apply cyclic loading to the specimen prepared in the mold. Tests were performed by changing the ratio of the maximum to the minimum stress, frequency and the magnitude of the maximum and the minimum stresses. Settlement of specimen due to cyclic loading was measured to analyze the compaction efficiency and sieve analysis test after cyclic loading test was also carried out to find the crushing rate of the specimen. As results of cyclic loading test, normalized settlement in terms of specimen height tends to be converged around loading cycle number of 1500. The magnitude of normalized settlement is in the range of 3.11 ~ 8.57%. The crushing rate is in the range of 4.46 ~ 8.78%. Normalize settlement and the crushing rate tend to increase with decreasing the ratio of the maximum to the minimum stresses and they tend to increase with increasing the frequency and the magnitude of the maximum and the minimum stresses for the given ratio. In conclusions, compaction rate of crushed stone is controlled by the dynamic stress (difference between the maximum and the minimum stresses) and the crushing rate is dominated by applied energy to the specimen.

자연파열된 신혈관근지방종 2례

이길호,선판일,성영훈,최영석,조철희,김철성,장대수 朝鮮大學校 附設 醫學硏究所 1993 The Medical Journal of Chosun University Vol.18 No.1

Renal angiomyolipoma is an uncommon benign tumor of the kidney that consists of smooth muscle, blood vessels and mature adipose tissues. The most common benign renal tumor associated with spontaneous non-traumatic perirenal hemorrhage is angiomyolipoma, because of high vascularity. The ultrasonographic and computed tomographic images are sufficiently characteristic to permit accurate preoperative diagnosis. We report 2 cases of renal angiomyolipoma with spontaneous perirenal hemorrhage which were managed with nephrectomy.

견과류에서 Ganglioside 분석

김현수,전길자 이화여자대학교 생명과학연구소 1992 생명과학연구논문집 Vol.3 No.-

소수성인 지방 부분과 친수성인 당 부분을 가진 양쪽성 물질로서 N-acetylneuraminic acid를 포함하는 ganglioside가 견과류에 존재하는지를 확인하기 위해서 잣, 호도, 살구씨, 아몬드로부터 Folch-Suzuki방법으로 당지질을 분리하였다. 또한 periodate-resorcinol 방법으로 N-acetylneuraminic acid를 정량한 결과 각각 10당 잣은 0.013㎛ol, 호도는 0.015㎛ol,살구씨는 0.05㎛ol, 아몬드는 0.015㎛을 포함하고 있었다. 견과류에서 추출해낸 당지질을 HPTLC로 분석한 결과 다양한 당지질의 존재를 확인할 수 있었다. 그 중 잣과 살구씨에서 분리한 당지질을 DEAE-Sephadex A-25 column chromatography를 수행한 결과 잣에서는 여러 종류의 중성 당지질과 monosialoganglioside를, 살구씨에서는 여러 종류의 중성 당지질과 disialoganglioside를 분리할 수 있었다. 본 연구결과 식물에도 ganglioside가 존재하는 것을 밝히게 되었다. The compositions of gangliosides in Pinus koraiensis S. et Z.(pine nut), Juglans sinensis DODE (walnut), Armeniaca semen (apricot seed), and Prunus dulicis D.A. Webb(almond) were investigated by Folch partition, HPTLC. DEAE Sephadex A-25 column chromatography. Total polar glycolipid was extracted in aqueous phase by Folch-Susuki method. Extracted glycolipids were separated on HPTLC glass plate in the solvent system(chloroforn: methanol: water containing 0.02% CaCl_2 ? 2H_2O=55:45:10,v/v/v). Glycolipids including ganglioside were visualized with resorcinol reagent or orcinol-ferric chloride-sulfuric acid reagent. The amount of total N-acetylneuraminic acid was determined using the periodate-resorcinol method. Pinus koreaiensis S. et Z.,Juglans sinensis DODE, Armeniaca semen, and Prunus dulicis D. A. Webb contained 0.013,0.015,0.050, 0.010㎛ol of N-acetylneuraminic acid per 10g samples respectively. Glycolipids extracted from pine nuts 100g and apricot seeds 100g were analyzed on DEAE Sephadex A-25 column (acetate form, 1.3×14㎝). The gangliosides were eluted with continuous gradient of ammonium acetate in methanol (0 to 0.6M) and our results suggest that monosialoganglioside exists in pine nuts and disialoganglioside exists in apricot nuts.

휨이 지배하는 건축 합성지하벽의 非線型 擧動에 관한 硏究

徐洙演,崔生吉,辛同寅 충주대 2003 産業科學論文集 Vol.11 No.-

In the design of retaining wall, generally, H-PILE is used to be considered as not structural member but temporary one. However, if the H-PILE has structural resistance for horizontal earth pressure, the structural capacity of retaining wall system can be enhanced. Especially, the contribution of H-PILE to the structural resistance is to be maximized when it behavior as a composite member with retaining wall. In this paper, an analytical study is presented for Composite Basement Wall(CBW) combined H-PILE and retaining wall by shear connector. previous test results for CBW are summarized and the flexural behavior of the composite wall is estimated by the non-linear finite element program, ATENA. In the modeling of shear connectors which connect steel beam and concrete wall, simple interface element is used. From the analytical result, it is shown that the flexural behavior of CBW can be predicted by using ATENA.