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.

한국산야생등줄쥐(Apodemus agrarius coreae)의 해마복합체에서 neuropeptide Y 면역반응세포에 관한 연구

김무강,송치원,이경열,박일권,정영길,이강이,김종섭 충남대학교 수의과대학 동물의과학연구소 1997 動物醫科學硏究誌 Vol.5 No.-

Neuropeptide Y(NPY) was first isolated from porcine brain. This discovery has lead some workers to study the distribution of this peptide in the central nervous system of various mammals. In this study the distribution pattern of neuropeptide Y-immunoreactive neurons was examined in the hippocampal complex of Striped field mouse in Korea(Apodemus agrarius coreae) Experimental animals were anesthesized with thiopental sodium and perfused with 4% paraformaldehyde through the left ventricle and the ascending aorta. The brains were removed and transferred 10%, 20% and 30% sucrose solution. Sections were cut on a cryostat into 40㎛-thick. The tissue was immunostained with free-floating and avidin-biotm complex(ABC) method. The results obtained in this study were summarized as followings. 1. The most of NPY-IR neurons in hippocampus proper were found in the polymorphic layer and a few was found in the pyramidal layer. 2. The process run vertically in the deep polymorphic layer and run parallel to corpus callosum in superficial polymorphic layer. 3. The shapes of neurons in hippocampus proper were varied of polymorphic, oval or round, and the nerve fibers were found in the molecular laver and the hippocampal fissure. 4. The highest density in number of NPY-IR neurons on dentate gyrus were found in hilar area of dentate gyrus. 5. The most of NPY-IR nerve fibers were found in molecular cell layer.

열린교육의 재음미 : 지식교육의 관점

김무길 한국초등교육학회 2003 초등교육연구 Vol.16 No.2

"열린교육"은 지식교육과 관련해볼 때 두 가지 상이한 관점에서 규정될 수 있다. 즉, 아동에게 교육내용의 선택권을 부여하는 "강한 의미"의 해석과 교육방법상의 다양성을 추구하는 "약한 의미"의 해석이 그것이다. 1990년대에 우리나라에서 널리 보급된 열린교육은 교육상의 실천적 열의와의 별개로, 근본적으로 이러한 의미상의 모호성을 지닌 것이었다. 분명히, 한국의 열린교육은 아동에게 무제한의 내용 선택권을 부여하는 자유 방임적인 강한 의미의 열린교육이 아니라, "주입식 수업 일변도 교육"을 지양하고 교육방법의 개선을 추구하는 약한 의미의 열린교육이었다. 이 글은 지시교육과 관련하여 한국에서 전개된 열린교육의 양상이 구체적으로 어떤 문제점과 교육적 의미를 가지고 있는지, 또한 앞으로 열린교육이 정당한 교육이론으로서 생명력을 갖고 자리 매김 되려면 어떤 방향으로 나아가야 할 지를 밝히고 있다. The purpose of this study is to reconsider critically the meaning of "open education" in relation to the knowledge education and to elucidate the source of adverse criticism about open education in korea, and to present the direction of open education in future. We can at least define the nature of "openness" in two different ways from the viewpoint of the knowledge education. One is a "strong meaning of openness" to criticize the cramming education and to seek the diversity of educational method. The fact that there are these two different viewpoints on open education, reflects the vagueness of the term of "openness". Fundamentally, open education wide practiced in 1990's in korea was related to the efforts of the improvement of instructional method such as individualized learning, but there was underlying vagueness of "openness". Certainly, open education in korea placed the focus on the diversity and improvement of instructional method. In this aspect, it can be said that open education in korea is not based on strong openness, but weak openness. If open education in future is to be placed as an warranted theory of education, it has to be emphasized that we have to research the aspect of the meaning and the interpretation of educational content as well as the diversity of educational method.

듀이의 '교호작용' 개념의 교육적 함의

김무길 성균관대학교 사범대학 교육연구소 2002 敎育硏究 Vol.1 No.1

본 연구는 듀이의 인식과정으로서의 '교호작용'(transaction)의 개념에 비추어 '상호작용'(interaction)의 성격을 해명하고, 그 교육적 시사점을 밝히는 데에 목적이 있다. 사실, 이때가지 듀이의 교육적 경험의 한 척도로 언급되어 온 '상호작용'은 그 용어 자체로 보아, 좁은 의미의 '평면적 상호작용'과 넓은 의미의 '입체적 상호작용'으로 각각 상이하게 해석될 가능성을 가지고 있었다. 듀이가 비교적 그의 후기 저작에서 '교호작용'이라는 새로운 용어를 쓰게 된 까닭은 자신이 의도한 상호작용이 자극-반응 식의 기계론적 상호작용이 아니라, 시공간상 인식의 범위가 확대된, 지적 상호작용이라는 점을 보다 명확히 하고자 하는 데에 있었다고 볼 수 있다. 교호작용은 삶의 존재적 상황에서 당면하는 상호작용을 바탕으로 해서 성립하는 것이지만, 동시에 좁은 범위의 '평면적 상호작용'의 차원을 벗어나서, 인식의 수준이 계속적으로 상승되는 '입체적 상호작용'을 의미한다. 이러한 교호작용의 전개 양상은 상호작용을 하는 양자 중 어느 한 쪽이 다른 쪽에 영향을 주는 일방적인 관계가 아니라, 상호 영향을 주고 받아, 양자 모두 변화, 발전하는, 그런 통합적인 관계에 입각해 있다. 여기에는 일체의 이원론적 분리를 부정, 극복하고자 하는, 그의 반이원론적 세계관이 반영되어 있다고 보아야 한다. 교호작용에 기초한 교육의 구체적 전개 양상은 적어도 세 가지 측면에서 조망될 수 있다. 즉, 경험의 성장을 지향하는 교육, 흥미와 교과가 통합되는 교육, 사회적 맥락과 연속적인 교육이 그것이다. 이 세 가지 양상들은 상호 병렬적인 관계로 파악되어서는 안 된다. 왜냐하면, 그것들은 공통으로 지적 사고작용을 전제로 하고 있으며, '경험의 성장'을 향하여 그 활동의 의미가 수렴되고 있기 때문이다. 교호작용에 기초한 교육론이 시사하는 바에 의하면, 교육에서는 인식수준의 계속적 향상이 이루어지도록 다양한 상호작용의 과정이 보다 풍부하게 일어나야 하며, 학습자에게 지금보다 더 많은 사고와 탐구의 기회가 주어져야 할 것이다. In his later work, Conduct and Experience, Dewey mentioned that interaction is the primary fact and it constitutes a trans-action. This statement shows us an important clue to re-interpret his theory of educative experience. The reason is that Dewey's theory of educative experience not only explains visible experience, but also presupposes transaction as cognitive process. In fact, it can be said that the term of 'interaction' spoken as a measure of educative experience in Dewey's theory, has two different meanings, keeping the literal analysis of the term itself in view. One is 'one-dimensional interaction' in a narrow sense, the other is 'three-dimensional interaction' in a broad sense. Dewey replaced 'interaction' by 'transaction' in his later works comparatively, because of the ambiguity of the meaning of interaction. In this context, the purpose of this study is to re-interpret the nature of 'interaction' in view of the concept of 'transaction' as cognitive process, and to search its implications for modern education. Dewey's transaction is not fragmentary interaction, but intellectual interaction accompanied with thinking. In other words, transaction is not based on the mechanical, stimulus-response relation such as Skinner's proposal, but on the wide knowing through 'three-dimensional interaction'. And it must be pointed out that the word of 'three-dimensional' in this study does not only mean three-dimensional space in mathematical context. Because it can be interpreted as the concept given with the continuity in time. Dewey's intention to use the term of 'transaction' is to emphasis that it is surely one step higher than mere interaction, and that in such transaction, there are plentiful, cognitive contexts : historical, cultural, and social contexts. In fact, transaction is only possible to get accomplished on the basis of interaction that is existential fact of life. But at the same time, it must be pointed out that transaction gets out of the level of mechanical interaction, and goes to the continuous progress of cognitive level. This unfolding aspect of transaction should not be interpreted as one-sided relation for one part to have influence on the other, but as integrated relation for both of them to change and develop under their reciprocal influences. This reflects Dewey's anti-dualistic viewpoint of the word that tries to reject and overcome all dualistic separations. It can be said that underlying Dewey's theory of educative experience is transaction as cognitive process. Concrete, unfolding aspects of education based on transaction shall at least be summarized in three aspects : firstly, education to the continuous growth of experience, secondly, education integrating child's interest and subject-matter's logic, thirdly, education linked with social context. But these three aspects should not be interpreted as separate, parallel relation. Because all of them commonly presuppose intellectual thinking, and identically focus on the growth of experience. According to the implications of educational theory based on transaction, various interactions should be occurred in order to achieve the continuous progress of learner's cognitive level, and many chances of thinking and inquiry should be given to learners.

야생 등줄쥐 (Apodemus agrarius coreae) 간뇌의 Dopamine성 신경세포

정영길,이남섭,민성기,김무강 대한해부학회 1997 Anatomy & Cell Biology Vol.30 No.6

殺蟲性 結晶蛋白質 特異的인 抗體의 生産

김기윤,이정민,유형진,백길현,권무식 성균관대학교 생명과학자원연구소 1996 生命資源科學硏究 Vol.3 No.1

Bacillus thuringiensis is a gram-positive soil bacterium characterized by its ability to produce crystalline inclusions during sporulation. These parasporal bodies consist of protoxins known as crystal proteins exhibiting highly specific insecticidal activities. The Lepidoptera-specific protoxin, Cry IAc, was purified from E.coli JM103 harboring the cry IAc gene. The gene was isolated from Bacillus thuringiensis kurstaki HD-73 and subcloned into an expression vector, pKK223-3. The recombinant DNA(pOS4201) was transformed into E.coli JM103. The Cry I Ac protoxin overexpressed in the E.coli was isolated from the total proteins by differential solubility. The protoxin were trypsinized to obtain activated toxin. The proteins was resolved on SDS gel. The molecular weights of the pro-and toxin were resistered about 130,000 and 65,000 Daltons respectively. The Cry IAc toxin was used as immunogen to produce anti-Cry IAc antiserum in a rabbit. The immunogen (200㎍/ 200㎕) was mixed with an equal volume of Freund's complete adjuvant, and the mixture was hypodermically injected to the hide back (30 spots) and paws (2 spots) of the rabbit. The immunization was performed four times every two weeks. The dosage of the immunogen was decreased by half, and incomplete adjuvant was substituted for the complete one from the second immunization. The serum was prepared from the blood as described elsewhere. Immunoreactivity of the serum was examined by dot-blotting with the aid of GAR-HRP indirect immunoassay kit. It has been found that the anti-Cry I Ac antiserum recognized nano-gram quantity of antigen under these experimental conditions. The antiserum will he used for the development of immunochemical mean(s) to screen transgenic plants transformed by the insecticidal characteristics of Cry I Ac.

듀이와 비트겐슈타인의 언어관 : 교육적 시사 Its Educative Implications

김무길 교육철학회 2002 교육사 교육철학 Vol.28 No.-

The purpose of this study is to compare Dewey's viewpoint of language with Wittgenstein's viewpoint, and to elucidate its educative implications. Dewey and Wittgenstein agree to the point that they identically criticize the essential, post-contextual viewpoint of language and insist on the inseparability of language from life. According to them, language should not be viewed as the integrate concept inseparable from life. But at the same time, it must be pointed out that there is one different point between the two. It can be said that in Dewey's view, process of language is emphasized while in Wittgenstein's view, tradition of language is emphasized. In Dewey's vies, language can be interpretered from the point transaction that intellectural interaction. But in Wittgenstein's view, language should be involved traditional aspect of life to be taught in educative context. Viewpoints of Dewey and Wittgenstein on language show that language is the vocabulary of life to be learned, and the means to participate in activities. Co-operate. And to inquire the problem-solving. In view of their viewpoints, language education should not be merely defined as isolated, fixed language education itself. It can only be meaningfully defined in view of two aspects-traditional aspect of "the form of lie" and active aspect of "transaction" relate to the concrete context of life. Considering this aspect of language education, teachers have to be sensitive to the learner's experience and thinking, and to lead for learners to understand the life, culture, and tradition of the society gradually.

흰쥐 해마박편에서 veratrine과 고농도 포타슘자극시 칼슘이온이 glutamic acid 유리에 미치는 영향에 관한 연구 : A role of calcium

조무길,김형룡,김관식 대한구강생물학회 1990 International Journal of Oral Biology Vol.14 No.2

Present study was performed to clarify the effect of calcium on the release of glutamic acid employing hippocampal slices. Hippocampal slices(300∼400㎛ thick) were prepared by the method of Kim et al.(1988) and pre-equilibrated in Krebs-bicarbonate medium(KBM, pH 7.4) for 1hr at 37℃. In case of veratrine induced glutamic acid release, pre-equilibrated slices were incubated in fresh KBM and then veratrine(25μM)-containing KBM for 10 min period in the presence or absence of 2.5mM Ca^++. In case of potassium-induced glutamic acid release, pre-equilibrated slices were incubated in fresh KBM and then potassium(50mM)-containing KBM for 5 min period in the presence or absence of 2.5mM Ca^++. Basal and veratrine and potassium-induced release of glutamic acid was determined from recovered medium by HPLC. The observed results were as follows: 1. The release of glutamic acid induced by the 10 min-exposure of 25μM veratrine and 5 min-exposure of 50mM potassium in the presence of 2.5mM Ca^++ was 330.9±25 nmol and 129.6±20.6 nmol, respectively. When compared with released amounts of glutamic acid during the corresponding spontaneous periods, these were 7.8 and 5.1-fold increase respectively. 2. the release of glutamic acid induced by the 10 min-exposure of 25μM veratrine and 5 min-exposure of 50mM potassium in the absence of Ca^++ was 361.8±31.9 nmol and 62.5±7.5 nmol, respectively. When compared with released amounts of glutamic acid during the corresponding spontaneous periods, these were 8.2 and 2.4-fold increase respectively.

로케트 工學에 관한 硏究 : 第1報 : 亞音速 亂流流動에서 飛行翼模型의 剝離現象 Ⅰst Report : Separation of Airfoils in Subsonic Turbulent Flow

朴煥奎,金鍾一,金鎭興,李茂錫,朴吉文,鄭洛奎,李行男,李東起 조선대학교 동력자원연구소 1984 動力資源硏究所誌 Vol.6 No.2

Separation, pressure and velocity distributions were studied fully developed two dimensinonal, incompressible flow over a flat airfoil in subsonic wind tunnel. Velocity and turbulence were measured with a two channel constant temperature hot wire anemometer and pressure with a pitot tube and pressure tranducer system. The experimental results were obtained as follow: (1) Turbulent intensity of shear layer just outside the separation point is considered to affect the size of separation bubble. (2) Static pressure coefficient is separated into three regions according to its value change. (3) Separation point is varied with the change of attack angle. (4) Velocity distributions and boundary layers normal to airfoil surface are changed as variation of attack angle of airfoil.

생체분해성 고분자의 특성 및 의학적 응용

이진호,최선웅,강길선,노승무,민병무,김용백,김학용 충남대학교 의과대학 지역사회의학연구소 1998 충남의대잡지 Vol.25 No.1

"Biomaterials" are nonviable materials used in medical devices, intended to interact with biological systems. They should have "biocompativility", which is defined as the ability of materials to perform with an appropriate host response in a specific application. It includes many materials that are often classified as biomaterials. Metals, ceramics, polymers, glasses, carbons, and composite materials are some examples. Among them, biodegradable polymers are discussed in this revies article. Since a biodegradable polymeric implant does not have to be removed surgically once it is no longer needed, biodegradable polymers are of value in short-term applications that require only the temporary presence of a polymeric implant. Main short-term medical applications of biodegradable polymers include the temporary tissue scaffold, the temporary adhesion barrier, the drug delivery device, and the multifunctional implant. In this article, the properties, processing methods, and medical applications of the biodegradable polymers are reviewed.