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.

초등학교 학생들을 위한 과학탐구능력 측정 도구 개발

조선형,정수길 淸州敎育大學校 科學敎育硏究所 1996 科學과 數學敎育論文集 Vol.17 No.-

The purpose of this study was to develop the science education items for 5th grade classes in Korean elementary school. The inquiry learning is recently showing more high achievement in learning method than traditional either extension of science inquiry skills or coefficiently score and experimental skills. Past quarter of a century, in spite of the inquiry learning declines its teaching method, but it should be encourage the teaching method of science and technology in society(STS) in and out of Korea on thesedays. There are no useful evaluation items of inquiry learning in elementary school, and so need good them according to teach the inquiry learning for achieved the goal of science teaching. The Author studied the development of instrument of measuring science inquiry skills of elementary school students. The 10 science inquiry skill properties were selected from SAPA program, with what are observing, classifying, measuring, predicting, inferring and operating instruments, controlling variabling and concluding or generalization on corporational inquiry skills in material things, motion and energy, life and earth science. The evaluation items are 25 with which divided into 10 skills that developed 2 dr 3 items for 40 minutes. Each point of validity and objectivity are 0.92 what same in the first treatment to 130 students and 177 students in second. In second(II) treatment, the standard deviation 3.712, the coefficient 0.568, average index of discrimination 0.347, index of response 63.9%, average index of difficulty 52.19, and measuring standard error 0.297. At last, the developing evaluation items are almostly very well by the indexes, but a few items(1,6 and some others) are need to change or to make clear once again.

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.

노랫말에 반영된 한국인의 음풍경 인식조사

장길수,신훈,조우기 東新大學校 工業技術硏究所 2004 工業技術硏究 Vol.10 No.-

It is required to understand the meaning of sound and cultural background of target spaces for soundscape design. The purpose of this study is to derive the general soundscape preserved in the mind of Korean people. Four kinds of traditional Korean songs, that is to say, Sijo (Korean verse), folk-song, Pansori (song for drama by Chang reciter), and popular songs, were used as tools of research subjects. That is because the sounds expressed in literature are very useful subjects for soundscape survey. Paragraphs containing description of sounds were selected from the lyrics of the songs. Then 11 sound categories were named, and 13 meaning categories were classified according to referential and emotional aspects, respectively.

고분자-금속착물(I) : Preparation and Characterization of Water-Soluble Ni(II)-Polyethyleneimine Complexes 물에녹는 Ni(II)-Polyethyleneimine 착물의 합성과 성질

徐吉守,朴正學,金東洙,曺泰燮 嶺南大學校附設 基礎科學硏究所 1981 基礎科學硏究 Vol.1 No.-

Ni(Ⅱ) complexes with polyethyleneimine(PEI) as ligands were prepared in absolute ethanol by varying PEI/Ni(Ⅱ) mole ratio. The effects of PEI/Ni(Ⅱ) mole ratio and reaction temperature on the yield of the resulting complexes were investigated. It was observed that two types of octahedral complexes, [Ni(PEI)Cl₂] and [Ni(PEI)]Cl₂were obtained by varying PEI/Ni(Ⅱ) mole ratio from 0.5 to 7.0, and he structures of the complexes were characterized by ir and uv spectroscopy. The solubility behavior of the complexes in various organic and ionic aqueous solutions were also studied.

안구적출에 따른 위둔덕의 칼슘결합단백질의 재구축 및 상호 연관성

안병수,고길석,안명수,김경주,권안성,정명섭,박춘매,조병옥,김진우,Samudra Acharya,Parmeshwar Narayan Amatya,장인엽 朝鮮大學校 附設 醫學硏究所 2007 The Medical Journal of Chosun University Vol.32 No.1

Background: Superior colliculus is a part of midbrain, and participates in the visual reflexes, It receives afferent fibers from optic nerve, visual cortex, and spinotectal tract. After optic deprivation, the microscopic structure of the superior colliculus changed. Calcium-binding proteins (CBPs) Play an important role in the neuronal protection, differentiation and reorganization of the central nervous system, Objectives and Methods: The effects of neonatal retinal deafferentation on a CBPs, calbindm D-28k (CB), Parvalbumin (PB) and calretimn (CR), and the existence of colocalization between the CBPs were examined immunohistochemically in the rat superior colliculus. Results: On the experimental (contralateral to enucleation) side of superior colliculus, the number of CB-immunoreactive (IR) cells was reduced (77.4% compared to control), but not fibers. The number of PB-IR neurons and fibers was also reduced on the experimental side (88.5% compared to control), In the other hand, the CR-IR cells were dramatically increased (642% compared to control), but CR-IR fibers were markedly decreased on the experimental side. The colocalization between CB-CR and PV-CR was rarely observed in the superior colliculus Conclusion: These results suggest that the changes of retinotectal projection may alter the expressional pattern of CBPs in different manners; relatively stable in CB- and PV-IR neurons and plastic in CR-IR neurons.

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.

서남해안 연근해저 퇴적물의 중금속 함량 및 분포

전수경,조영길 한국환경과학회 2002 한국환경과학회지 Vol.11 No.12

Thirty sediment samples of the <63㎛ fraction collected from the southwestem coast of Korea were analysed for their heavy metal (Fe, Mn, Cr, Co, Cu, Ni, Zn and Pb) concentration. The results show that sediment texture plays a controlling role on the total metal concentrations and their spatial distribution. A single IM HCI extraction procedure was used in order to assess the environmental risk of heavy metals in bottom sediments. The non-residual fraction was the most abundant pool for Mn and Pb in most samples, which means that this metals are highly avaliable in these sediments. Cr, Ni, Fe, Co, Zn and Cu were mainly associated with the residual fraction, suggesting that their concentrations are controlled significantly by transport processes with the fine particles as carriers from diffuse pollution source. Concentration raitos(CER) were calculated from the non-residual contents and their values allowed us to classify the sediments according to their environmental risk.

감꼭지나방(나비목:감꼭지나방과)의 발육생태

김정화,김길하,조수원,박은철,박형진 충북대학교 첨단원예기술개발연구센터 2000 연구보고서 Vol.5 No.-

충북 영동의 감나무 가로수에서 감꼭지나방(Stathmopoda masinissa)을 채집하여 온도 25±1℃,광주기 16L:8D, 상대습도 85%의 실내조건에서 이들의 발육생태를 조사하였다. 각 충태별 발육일수는 알기간 7.4일, 유충기간 34.8일, 번데기기간이 15.5일이었다. 1령에서 5령의 영기간은 각각 3.5일, 4.2일, 5.2일, 6.5일, 15.4일이었으며, 유충의 두폭은 각각 0.20, 0.40, 0.65, 0.87, 1.07mm이었다. 용화율과 우화율은 각각 68.0%, 59.9%이었다. 성충 수명은 수컷이 6.2일, 암컷이 10.1일이며, 암컷 한 마리당 평균 산란수는 24.4개였다. Persimmon fruit moth, Sathmopoda masinissa, collected from roadside persimmon trees planted as shade trees in yeongdong area was used to investigate their developmental ecology under laboratory condition; 25±1℃, 16L : 8D and 85% RH. Developmental periods for eggs, larvae, and pupae were 7.4, 34.8 and 15.5 days, respectively. The duration for each larval instar from the 1st to the 5th was 3.5, 4.2, 5.2, 6.5 and 15.4 days, respectively, and the head capsule width of corresponding stage was 0.20, 0.40, 0.65, 0.87 and 1.07mm. Rates of pupation and emergence were 68.0 and 59.9%, respectively. Longevity of adult males was 6.3 days while that of females was 10.1 days. Average fecundity was 25.4 eggs.

가정에서의 환경의식과 행동에 관한 연구

윤정숙,조길수,이숙현,김수경 연세대학교 생활과학연구소 2001 生活科學論集 Vol.15 No.-

The purpose of this study was to investigate the factors related to environment-oriented consciousness and Behavior in family life. A questionnaire was prepared with 57 questions each question used the 5 scale Likert type. The questionnaire was administered to 327 housewives who had 6-24 year old children and lived in Seoul and Kimpo. The contents of the questionnaire consisted of the questions to measure acknowledgement of environment problems, consciousness of environmental pollution and recourses, environment-oriented behavior when buying, using, and disposing the living goods. The findings were as follows: 1) The level of environment-oriented consciousness and behavior of those housewives was high, but the scores of questions containing individual sacrifice and effort were lower than the others. 2) Environment-oriented consciousness and environment-oriented behavior were significantly correlated. According to level of those two factors, three groups(high, medium, low) were divided by cluster analysis. The effect of socio-economic factors (education level of housewives, number of children, employment state of housewives, living expenses) to environment-oriented consciousness and behavior was very weak.