경량화용 AI/CFRP 사각튜브의 적층각과 두께에 따른 압궤특성

임광희,양인영,이길성,조영재,김성훈 朝鮮大學校 機械技術硏究所 2004 機械技術硏究 Vol.7 No.2

알루미늄 튜브와 CFRP(Carbon Fiber Reinforced Plastics) 튜브는 대표적인 경량화 재료이지만, 축 하중을 받을 때 압궤되는 메커니즘이 상이하다. 알루미늄 튜브는 안정적인 소성변형에 의해서 에너지를 흡수하나, CFRP 튜브는 알루미늄 튜브에 비하여 비강도, 비강성은 높으나 불안한 취성파괴에 의해서 에너지를 흡수한다. 본 논문에서는 두 재료의 단 점을 상호 보안하고 장점에 대한 상승효과를 기대하기 위하여, CFRP의 적층각과 두께변화를 주어 알루미늄 사각튜브의 외면을 감싸 적층하여 강화시킨 Al/CFRP 튜브를 가공하여 축 압궤실험을 행하여 압궤거동과 에너지흡수특성을 고찰하였다. 그리고 알루미늄 사각튜브와 CFRP 사각튜브의 압궤실험을 행하여 Al/CFRP 사각튜브와 비교하였다. 고찰결과, Al/CFRP 사각튜브의 압궤는 알루미늄 튜브의 좌굴을 계기로 하여 CFRP 튜브의 불안한 취성파괴의 단점을 보완하여 비교적 안정적인 압궤모드를 보였다. Al/CFRP 사각튜브는 CFRP 적층각과 두께에 의해 4가지 대표적인 압궤모드를 보였으며, 압궤모드는 에너지흡수 특성을 나타내는 중요한 척도가 되었다. 또한, Al/CFRP 사각튜브가 알루미늄 튜브와 CFRP 튜브에 비하여 단위 질량당 흡수에너지가 높아 경량화 효과가 크다는 것을 알 수 있었다. An aluminum or CFRP (Carbon Fiber Reinforced Plastics) tube is representative light-weight materials but its axial collapse mechamism is different from each other. The aluminum tube absorbs energy by stable plastic deformation. while the CFRP tube absorbs energy by unstable brittle failure with higher specific strength and stiffness than those in the aluminum tube. In an attempt to achieve a synergy effect by combining the two members. aluminum/CFRP square tubes were manufactured. which are composed of aluminum tubes wrapped with CFRP outside aluminum square tubes with different fiber orientation angle and thickness of CFRP. and axial collapse tests were performed for the tubes. The crushing behavior and energy absorption capability of the tubes were analyzed and compared with those of the respective aluminum square tubes and CFRP square tubes. Test results showed that the collapse of the aluminum/CFRP square tube complemented unstable brittle failure of the CFRP square tube due to ductile characteristics of the inner aluminum square tube. The collapse modes were categorized into four modes under the influence of the fiber orientation angle and thickness of CFRP. The absorbed energy per unit mass, which is in the light-weight aspect, was higher in the aluminum/CFRP square tube than that in the aluminum square tube or the CFRP square tube alone.

균열도가 R·C 교량의 수명에 미치는 영향

김영인,박길현,양승현,황선하 朝鮮大學校 建設技術硏究所 2002 建設技術硏究 Vol.22 No.1

There are several causes. the percussion from the exterior, the decline of capacity by circumstances, the crack occured in the interior, the carbonation and soon, that can shorten the span of life of concreted construction. However, the crack itself, as the primary factor of the life-curtailment of concreted construction, is principal and should bring about the erosion of the reinforcing rod and the curtailment of sticking strength between concrete and reinforcing rod and the span of life. The span of life of construction influenced by crack will be treated in this report. Finally, I think that the Crack-Ratio found out by the outside investigation with timeworn R·C bridge should be utilized for deciding bridge's life and danger with statistics·analysis of used-life/carbonation-life, used-life/ fatigue-life.

프로그램을 이용한 합성교량의 설계에 관한 연구

김영인,박길현,양승현 조선대학교 국토개발연구소 1996 국토개발연구 Vol.16 No.1

This study is experts system about design of composite bridge that brings a simple working system and an outstanding application. By knowledge base involved deep knowledge and surface knowledge, user can execute the design of floor span and main girder and investigation stress on the ground of composite precess. Opening the program, user can notice the minium number of input-data and the easy amendment at pertinent picture. The study is the object of uninitialed education and preservation efficiency of work while the expert has been absent.

용융 AI-10Si 합금의 산화피막강도 및 표면 미세조직에 미치는 Mg첨가의 효과에 관한 연구

김길수,양중식,김기주,백영남 慶熙大學校 材料科學技術硏究所 1992 材料科學技術硏究論集 Vol.5 No.-

This study was carried out to determine the strength of oxide skins of Al-10Si alloy melts and the effect of Mg addition on the morphology of oxide skins as the practical alloy for automobile piston. This has been observed by Rotational Die Movement Equipment for the temperature range from 600℃ to 720℃, the oxidation time range from 2 min. to 60 min. and the Mg weight percent(wt %) range from 1% to 5%. As the surface temperature and the surface oxide time of alloy melts increased, the crystalization of oxide layer and the creation of oxides were verified.

應答比에 의한 R.C 슬래브교의 耐荷力 算定

김영인,박길현,양승현,김재명 朝鮮大學校 建設技術硏究所 2001 建設技術硏究 Vol.21 No.1

It is very hard to do that exactly safety-degree criticism of practical bridges as would be not agree for inspection method, judgment of engineer, who operates inspection for bridges. So, It must be operated the study to apply to criticize Loading Carrying Capacity of bridges owing to the criticism through data rational and simply, and gather them. It must be adjusted a rule rational and objective as to be anxious a loss of maintenance of bridges for minding their safety excessively according to the judgment of inspector in deciding Loading Carrying Capacity of them as chiefly purpose of safety-inspection. This study suggest that Improvement should be proper which calculates Loading Carrying Capacity from respondent-ratio, produced from displacement practical and that computed by the program(SAP 2000) in ordinary as Compressive strength is obtained for dug core of bridges, mixed Schmidt Hammer and Pulse Velocity, through Concrete and use Schmidt Hammer on bridges that were already performed safety-inspection.

2-Deoxy-D-Glucose에 의한 대사성 쇼크가 무우스의 면역 반응에 미치는 영향

김양숙,장선일,박래길,조성경,정헌택 최신의학사 1991 最新醫學 Vol.34 No.2

생쥐의 骨髓細胞에 대한 Aminopterin 과 Amethopterin의 細胞遺傳學的 影響

양재섭,강봉석,최명철,김길웅 대구대학교 기초과학연구소 1987 基礎科學硏究 Vol.4 No.-

Aminopterin and amethopterin(Methotrexate; MTX) are antifolic drugs and anti-tumour agents, which inhibit DNA biosynthesis, were previously known to have mutagenic effects on various mammalian cells. Mutagenecity and toxicity of these agents have been determined by various methods. In the present study, effects of two anti-tumour agents on cultured mouse bone marrow cells were analyzed by observing chromosome aberrations and mitotic index. The results of the present investigation were as follows; 1. The chromosome aberrations analyzed were mainly chromosome gaps and breaks, chromatid gaps and breaks. In the Group-1 (treated for 8 hours), chromosome aberrations were not shown and it seems that mutagenic actions of anti-tumour agents were not aroused due to the short period of culture and the other culture conditions. However, in the Group-2 (treated for 24 hours), as the concentrations of antifolic compounds were increased, chromosome aberrations were increased. 2. In mitotic index, the Group-I treated with aminopterin and amethopterin showed marked inhibition in the mitotic index(O. 6% in aminopterin, 0.9% in amethopterin) at the high concentrations, compared with that of control (5. 2%). Both aminopterin and amethopterin showed a dose-dependent reduction of mitotic index. In the Group-2, each group treated with two antifolic compounds showed no marked differences in the mitotic index. compared with that of control. 3. Aminopterin was a more potent agent for induction of chromosome aberration than amethopterin.

골반내에 발생한 Proximal-type 유상피성 육종 1예

길준철,이상수,전병화,김성훈,손우석,목정은,박양순,강길현 대한부인종양 콜포스코피학회 2003 Journal of Gynecologic Oncology Vol.14 No.4

유상피성 육종은 매우 드문 악성 연조직 육종으로, 전형적인 경우들은 주로 젊은 남성의 수부, 전완부와 같은 신체의 원위부에 피하 혹은 심재성 피부 종괴로 발생하며, 조직학적 소견상 적은 비정형성을 나타내는 유상피성 세포와 방추형 세포의 증식에 의한 다발성 결절 형태의 배열을 보인다. 최근에 전형적인 유상피성 육종과 조직학적 유사성을 가지나 더 공격적인 형태인 proximal-type 유상피성 육종이 보고되었으며, proximal-type은 전형적인 유상피성 육종에 비하여 현저한 유상피성 세포의 발현과 매우 심한 비정형성을 나타내며, 세포가 매우 크고, 소포성 핵과 뚜렷한 핵소체를 보이며, 자주 rhabdoid 세포의 양상을 띈다. 임상적으로는 전형적인 형태에 비하여 호발 연령이 조금 늦고, 주로 체간부에, 특히 골반, 회음부, 생식기 등과 같은 심부에 발생하고, 더욱 공격적인 양상을 나타낸다. 저자들은 13세 소녀에서 원발부위를 알 수 없는, 골반내에 발생한 proximal-type 유상피성 육종 1예를 경험하여, 문헌 고찰과 함께 보고하는 바이다. Epithelioid sarcoma is a rare malignant soft-tissue sarcoma with an unknown histiogenesis, typically presenting as a subcutaneous or deep dermal mass lesion in the distal portions of the extremities of young adults. Recently, a more aggressive, so-called 'proximal-type' epithelioid sarcoma has been reported. In contrast to conventional epithelioid sarcoma, the proximal type is characterized by a predominantly large cell epithelioid cytomorphology, marked cytologic atypia, and frequent occurrence of rhabdoid features in most patients. Proximal-type epithelioid sarcoma has a predilection for appearing in the genitalia, especially the vulva, penis, pelvis and buttocks. Also this lesion appears to be somewhat more aggressive or at least metastasizes earlier than the conventional epithelioid sarcoma. We report a 13-year-old girl who presented with a buge mass filling the pelvic cavity which was painful, hard and fixed on palpation, and was radiologically diagnosed as a malignant germ cell tumors on the CT scan. The mass was surgically excised and pathologically proved to be an proximal-type epithelioid sarcoma of unknown origin.

濟州北方,成德沿岸海域에 있어서 植物플랑크톤 群集의 季節變動 特性

尹良湖,金暎起,盧洪吉 濟州大學校海洋硏究所 1992 해양과환경연구소 연구논문집 Vol.16 No.-

Fieldsurvey for oceanographic conditions and the seasonal succession of phytoplankton were carried out in the Hamdok port from April 1989 to February 1990. Water temperature ranged between 11.4℃ in January and 27.3℃ in August, and salinity fluctuated greatly, with a maximum of 35.6 in August and minimun of 21.8‰ in April. A total of 120 species of phytoplankton belonging to 69 genera were observed in which, at least, 8 genera, Oxyphysis, Amphidinium, Cochlodinium, Torodinium, Nematodinium, Katodinium, Ebria and Streptotheca are first records in the Cheju coastal waters. The predominant species are centric diatoms, Skeletonema costatum, Chaetoceros opp. through the year, while they are unarmoured phytoflagellates, Heterosigma akashiwo, Gymnodinium sp., Gyrodinium sp. in warmer seasons. And phytoplankton cell number fluctuated between 4.1×10³cells/1 in winter and 2.4×10 cells/1 in spring blooms, and it was under the control of centric diatoms for a year. On the other hand, it is occupied by phytoflagellates including some unarmoured dinoflagellates in summer season.

AI/CFRP 혼성튜브의 적층각과 단면형상에 따른 축방향 압궤 특성

김선규,이길성,김성훈,차천석,김정호,양인영 朝鮮大學校 機械技術硏究所 2004 機械技術硏究 Vol.7 No.1

알루미늄은 수송기계용 구조부재로 널리 쓰이고 있으며 복합재료가 이러한 수송기계용 구조부재로 쓰일 때 경량화와 많은 에너지 흡수 측면이 기대된다. 알루미늄 튜브는 CFRP(탄소 섬유 강화 복합재료)튜브에 비해 압궤하중은 낮지만 안정적인 소성변형에 의해 압궤되는 반면 CFRP 튜브는 알루미늄 튜브에 비해 압궤하중은 높지만 불안정한 취성파괴에 의해 압궤된다. 따라서 알루미늄과 CFRP의 조합은 안정적이며 뛰어난 에너지흡수를 기대할 수 있다. 본 연구에서는 알루미늄 원형과 사각튜브의 외측을 CFRP로 감싸 Al/CFRP 혼성튜브를 제작하여 축방향 압궤특성에 관하여 연구하였다. 알루미늄 튜브와 CFRP 튜브의 압궤특성을 기초로 하여, Al/CFRP 흔성튜브의 이방성 재료인 CFRP의 적층각과 단면형상의 변화를 주었다. 실험결과, Al/CFRP 흔성튜브는 알루미늄 튜브의 좌굴을 계기로 하여 CFRP 튜브의 불안정한 취성파괴의 단점을 보완하였다. 경량화 측면에서 단위 질량당 흡수에너지는 원형튜브가 사각튜브에 비해 약 45~70% 이상 높았으며 CFRP 적충각이 90˚일 때 가장높았다. Aluminum materials have been widely used in various vehicle structures. If composite materials are applied to vehicle structures, it is expected that not only the weight of the vehicle is decreased but also it absorb large amounts of energy. Aluminum tubes are lower than CFRP (Carbon Fiber Reinforced Plastics) tubes in the collapse load but absorb energy by stable plastic deformation. On the other hand, CFRP tubes are higher than aluminum tubes in the collapse load but absorb energy by unstable brittle failure. The combination of aluminum and composite may result in stable deformation and excellent energy absorption efficiency. The compressive axial collapse tests were performed to investigate collapse characteristics of Al/CFRP compound tubes which are aluminum tubes wrapped with CFRP outside the aluminum circular and square tubes. Based on collapse characteristics of aluminum tubes and CFRP tubes respectively, the axial collapse tests were performed for Al/CFRP compound tubes which have different CFRP orientation angles and cross-sections. Test results showed that Al/CFRP compound tubes supplemented the unstable brittle failure of CFRP tubes due to ductile nature of inner aluminum tubes. In the light-weight aspect, Absorbed energy per unit mass of circular tubes was higher than square tubes'. Absorbed energy per unit mass showed highest when CFRP orientation angle was 90 degrees.