Crack Guidance Utilizing the Orientation of Additive Manufactured Lattice Structure

이준학,박성제,양정호,연시모,홍석준,손용,박지용 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.23 No.7

We propose a method to guide the direction of cracks by utilizing the orientation of Ti-6Al-4V lattice structures produced by powder bed fusion, which has recently attracted considerable attention in additive manufacturing. The fracture characteristics and impact strengths were observed by inserting a diagonal structure with structural anisotropy into specimens of various directions and densities, and it was confirmed that the impact strength differed depending on the differences between the direction of the z-strut, impact direction, and density of the lattice structure. Using this, crack guidance specimens with optimal lattice structures were manufactured along the direction of the cracks, and it was confirmed that cracks were uniformly induced in comparison to single lattice crack guidance specimens. This crack guidance is expected to be used in future machinery in various industries for the protection of important components and shock mitigation in the event of a sudden impact.

T.S. 엘리엇과 폴 틸리히

李俊鶴 한국영어영문학회 1997 영어 영문학 Vol.43 No.3

교육에 대한 농촌지역민들의 성향과 그 사회적 요인분석

이준학 한국교육사회학회 1995 교육사회학연구 Vol.5 No.2

하복부 수술에서 경막외 Bupivacaine과 Fentanyl에 의한 선행진통법이 술후 통증관리에 미치는 효과

이준학,김인령,윤채식,정은배,이기남,문준일 예수병원 1998 예수병원학술지 Vol.19 No.-

T.S. 엘리엇의 시에 나타난 회의의 포스트모던적 성격

李俊鶴 한국영어영문학회 1996 영어 영문학 Vol.42 No.3

포스트모던 문학의 종교성 : 시론 알렌 긴즈버그와 로버트 로월의 경우 The Case of Allen Ginsberg and Robert Lowell

이준학 한국문학과종교학회 2002 문학과종교 Vol.7 No.2

Paul Tillich, who experienced "faith without God" at the front in World War I for four years, said that "Religion, in the largest and most basic sense of the world, is ultimate concern. . . . You cannot reject religion with ultimate seriousness, because ultimate seriousness, or the state of being ultimately concerned, is itself religion." Postmodernism, however, with its ultimate seriousness, expressed its ultimate concern paradoxically by denying its ultimate concern, as negative theology speaks 'what God is not' to prove 'God's presence as the presence of an absence.' Postmodernism rejects Grand Narratives. Such Big Ideas as Truth, Morality, Reason, God, Tradition and History are rejected as artificial constructions that are totalitarian by their own nature. The objects of its denials, however, have been revealed more vividly under the reflective light of the negation. To negate something we have to draw it into the light to show it to others. In the course of scrupulous trials of Truth, Reason and God, postmodernism, in a sense, has thrown light on them continuously about forty years since 1960 when it began to attract the interests of the intellectuals of the late twentieth century. Through the negative way postmodernism has created new arguments and discourses about Truth and Reason otherwise to be forgotten or to be disregarded under the attacks of rapidly developing materialism in this century. Paradoxically, postmodernism seems to have proved the importance of God and Truth by negating them for about half a century. This is why Derrida's deconstruction is thought to be related to negative theology, though Derrida repeatedly insists that deconstruction is not negative theology. Along the same negative way literary works in the postmodern period seem to contribute to proving the importance of real truth, real reason and real religion. The works of Allen Ginsberg and Robert Lowell are outstanding examples of this negative way. Ginsberg, through his widely known resistance against existing value, existing social system and existing culture, especially strongly demonstrated in his Howl and Other Poems, and Lowell, through his revolutionary poems revealing the relentless denials of the self, especially impressively manifested in his Life Studies, revived the nostalgia for the dead God and Truth in life. Lowell thought the human self is the root of all existing negative value system. Through the examples of their poems we can perceive that the religious character of postmodern literature consists in the reactionary and dynamic advocation of negative qualities which, with its unconquerable ultimate concern about existential life, paradoxically revives the seemingly disappeared concern about Value, Truth, Religion and God in their real dimensions. The sincere aspiration and pursuit of the ultimate concern on the part of these poets by way of strong negation of traditional values and ideals might be said to resemble the paradoxical way as negative theology does for the revival of the concern on God. What we must not fail to notice here is that postmodern literature is not completely and logically negative in communicating its ideas. Literature is basically the expression of powerful emotion. So, not through logic but through an artistic shaping of metaphor, symbol, a chain of events or situations, it makes us feel the reality of the human spirit and communicates it indirectly to the reader. We must bear this in mind when we read the works of postmodern literature.

자유와 운명 : T.S. Eliot의 The Confidential Clerk 연구 A Study of T.S. Eliot's The Confidential Clerk

李俊鶴 한국영어영문학회 1991 영어 영문학 Vol.37 No.1

T.S. 엘리엇의 시와 詩劇에 나타난"궁극적 관심"

李俊鶴 한국영어영문학회 1994 영어 영문학 Vol.40 No.1

알럼 슬러지 기반 흡착제를 이용한 수용액상 불소 및 비소 흡착에 관한 연구

이준학,지원현,이진수,박성숙,최궁원,강찬웅,김선준,Lee, Joon Hak,Ji, Won Hyun,Lee, Jin Soo,Park, Seong Sook,Choi, Kung Won,Kang, Chan Ung,Kim, Sun Joon 대한자원환경지질학회 2020 자원환경지질 Vol.53 No.6

본 연구에서는 정수 처리장 침전지에서 채취한 알럼 기반의 슬러지를 수열합성 방법으로 흡착제(Alum Sludge Based Adsorbent, ASBA)를 제조하고, 이를 인공 수용액 및 광산배수 내 불소와 비소의 제거에 적용하여 ASBA의 흡착 특성을 평가하였다. ASBA의 광물학적 결정 구조, 구성 성분 및 비표면적을 조사한 결과, ASBA는 표면에 불규칙한 기공과 87.25㎡ g-1의 비표면적을 갖는 흡착에 유리한 구조로 나타났다. ASBA를 구성하는 주요 광물 성분은 석영(SiO2), 몬모릴로나이트((Al,Mg)2Si4O10(OH)2·4H2O), 알바이트(NaAlSi3O8)임을 확인하였다. 다음으로 회분식 흡착실험을 수행하여 pH, 흡착 반응시간, 초기 농도 및 온도 등의 인자가 ASBA를 활용한 불소와 비소 흡착에 미치는 영향을 살펴보았다. 실험 결과, 용액의 pH 환경이 염기 영역으로 갈수록 불소와 비소의 흡착률은 감소하는 경향을 보였으며, 흡착제의 영전하점은 pH 7 부근으로 나타났다. 등온 흡착실험을 통해 확인한 불소와 비소의 최대 흡착량은 각각 7.6mg g-1, 5.6mg g-1이었고, 동적 흡착실험에서 불소와 비소는 반응이 시작한 후 각각 8h, 12h이 경과하면서 흡착농도의 증가율이 감소하는 것으로 나타났다. 한편 흡착평형 실험을 통한 ASBA의 흡착 메커니즘을 알아본 결과. 불소와 비소의 흡착은 Langmuir 등온 흡착모델 및 Freundlich 등온 흡착모델과 높은 상관관계를 가지며 일치하는 경향을 보여주었다. 또한 열역학적 연구에서는 25℃부터 35℃까지의 온도 증가에 따른 불소와 비소의 흡착 양상을 실험하여, 양의 값을 갖는 열역학적 상수 ΔH°와 ΔG°을 도출함으로써 ASBA의 흡착 특성은 흡열반응이자 비자발적인 반응임을 검증하였다. 재생실험 결과, ASBA는 1N NaOH을 이용하여 재생 가능하였으며, 광산배수를 이용한 불소와 비소의 흡착실험에서 각각 77%, 69%로 비교적 높은 제거율을 보여 현장 적용 가능성을 지닌 것을 알 수 있었다. 분석 결과를 종합하여 볼 때, 소규모 유량을 가지며 pH 환경이 산·중성 영역인 광산배수 내 불소와 비소가 흡착되어 제거되는 데 흡착제로서 ASBA가 효과적임을 제안한다. An Alum-sludge based adsorbent (ASBA) was synthesized by the hydrothermal treatment of alum sludge obtained from settling basin in water treatment plant. ASBA was applied to remove fluoride and arsenic in artificially-contaminated aqueous solutions and mine drainage. The mineralogical crystal structure, composition, and specific surface area of ASBA were identified. The result revealed that ASBA has irregular pores and a specific surface area of 87.25 ㎡ g-1 on its surface, which is advantageous for quick and facile adsorption. The main mineral components of the adsorbent were found to be quartz(SiO2), montmorillonite((Al,Mg)2Si4O10(OH)2·4H2O) and albite(NaAlSi3O8). The effects of pH, reaction time, initial concentration, and temperature on removal of fluoride and arsenic were examined. The results of the experiments showed that, the adsorbed amount of fluoride and arsenic gradually decreased with increasing pH. Based on the results of kinetic and isotherm experiments, the maximum adsorption capacity of fluoride and arsenic were 7.6 and 5.6 mg g-1, respectively. Developed models of fluoride and arsenic were suitable for the Langmuir and Freundlich models. Moreover, As for fluoride and arsenic, the increase rate of adsorption concentration decreased after 8 and 12 hr, respectively, after the start of the reaction. Also, the thermodynamic data showed that the amount of fluoride and arsenic adsorbed onto ASBA increased with increasing temperature from 25℃ to 35℃, indicating that the adsorption was endothermic and non-spontaneous reaction. As a result of regeneration experiments, ASBA can be regenerated by 1N of NaOH. In the actual mine drainage experiment, it was found that it has relatively high removal rates of 77% and 69%. The experimental results show ASBA is effective as an adsorbent for removal fluoride and arsenic from mine drainage, which has a small flow rate and acid/neutral pH environment.

Manager 기반 GPS/eLoran 통합항법시스템 M&S 소프트웨어 설계

이준학,김혜원,오상헌,소형민,황동환 제어로봇시스템학회 2017 제어로봇시스템학회 국내학술대회 논문집 Vol.2017 No.5