판상형 충전제의 함량과 배향에 따른 PP복합체의 열팽창계수 영향 연구

이기윤(Kee Yoon Lee),이용현(Yong Hyun Lee),정선경(Sun Kyoung Jeoung),황효연(Hyo Yeon Hwang),이승구(Seung Goo Lee) 한국고분자학회 2012 폴리머 Vol.36 No.3

두 가지의 종횡비(ρα=a1/a3 and ρβ=a1/a2)에 의해 특징지어진 3차원 타원체(a1 > a2 > a3)를 사용하여 polypropylene 복합체의 판상형 충전제 함량과 방향이 열팽창률에 미치는 영향에 대해 실험적인 연구를 수행하였다. 측정된 실험적인 값은 Lee와 그의 연구자들이 제안한 이론적인 모델에 의한 계산 값과 비교분석되었다. 판상형충전제로는 운모와 탈크가 사용되었다. 실험 결과로 운모의 경우 종횡비는 ρα= 13.5, ρβ= 1.8이 사용되 어, 20 wt% 함량일때 α11/αm는 약 0.56으로 감소하였으나, α33/αm는 오히려 1.018로 증가함을 보였다. 탈크의 경우의 종횡비는 ρα=3.7, ρβ= 1.4이었고 α11/αm는 0.63으로 감소하였다. 결국 운모와 탈크 모두 그 함량증가에 따라 종단방향과 횡단방향에서 열팽창률은 감소하였으나 수직방향에서는 초기 낮은 충전제 함량에서는 오히려 증가하는 경향을 보였다. Experimental study was performed regarding the effects of disc-like filler orientation and contents on the coefficient of thermal expansion (CTE) of polypropylene composites using the three dimensional ellipsoids (a1 > a2 > a3) analyzed by two aspect ratios(ρα=a1/a3 and ρβ=a1/a2). Measured data were compared with the theoretical approaches proposed by Lee et al. Mica and talc were useed as disk-like fillers in the composites. As experimental results, α11/αm decreased down to ca. 0.56 with mica content of 20 wt% and the aspect ratios, ρα=13.5, ρβ=1.8. However, α33/αm increased to more than 1. In the case of talc, α11/αm decreased to ca. 0.63 with 20 wt% and ρα=3.7, ρβ=1.4. Finally, the longitudinal CTEs (α11) of polypropylene composites decreased as filler contents increased, but normal CTE (α33) increased in the low filler contents like the theory.

Plant regeneration from callus of Iris odaesanensis Y. N. Lee native to Korea via organogenesis

Bae, Kee-Hwa,Yoo, Kyoung-Hwa,Lee, Mi-Hyun,Jeong, Jae-Hun,Choi, Yong-Eui,Yoon, Eui-Soo The Korean Society of Plant Biotechnology 2013 식물생명공학회지 Vol.40 No.3

Iris odaesanensis Y. N. Lee. is an important endangered and native plant belonging to the family Iridaceae in Korea. This study describes a method for rapid micropropagation of this species via from leaf, rhizome and root explants derived calli. Leaf, rhizome and root explants were cultured on Murashige and Skoog (MS) medium supplemented with 2,4-dichlorophenoxy acetic acid (2,4-D) for callus induction. Rhizome explants yielded calli at a frequency of 72% when cultured at 1.0 mg/l 2,4-D. Calli were maintained at 1.0 mg/l 2,4-D. These calli were transferred to MS medium supplemented with 0, 0.5, 1.0, and 2.0 mg/l 2,4-D in combination with 0, 0.5, 1.0, and 3.0 mg/l BA for adventitious shoot induction. The highest number of adventitious shoot (228.9 per petri-dish) were formed at 1.0 mg/l 2,4-D and 1.0 mg/l BA. WPM medium was the best to convert calli into plantlets, where up to 98.2% of calli were regenerated into plantlets. This in vitro propagation protocol should be useful for conservation of this endangered plant.

판상형 충전제의 함량과 배향에 따른 PP복합체의 영률 변화 연구

서상범(Sang Bum Seo),이용현(Yong Hyun Lee),정선경(Sun Kyoung Jeong),이승구(Seung Goo Lee),이기윤(Kee Yoon Lee) 한국고분자학회 2012 폴리머 Vol.36 No.2

이 논문은 판상형 충전제의 함량과 배향에 따라 폴리프로필렌 복합체의 영률 변화에 미치는 영향을 연구 하였다. 이론적인 예측은 Lee와 그의 연구자들에 의해 제안된 두 개의 종횡비, ρα=a1/a3과 ρβ=a1/a2 를 이용하여 3차원 타원체의 형상을 계산하였고 실험값과 비교 분석하였다. 판상형 충전제로 운모와 탈크를 사용하였다. 충전제의 형태는 SEM을 이용해 관찰하였고, 종횡비는 고분자의 흐름을 기준으로 좌표축을 설정하여 통계적 방법으로 계 산하였다. 충전제가 운모인 경우에 ρα=13.5와 ρβ=1.8이었고, 탈크의 경우는 ρα=3.8과 ρβ=1.4이었다. 또한 충전제 의 2개의 종횡비와 함량이 기계적 물성에 미치는 영향을 실험적으로 연구하였다. 운모의 경우 30 wt% 함량일 때 E11이 약 2.7배 향상되었다. 탈크의 경우는 E11이 약 2.3배 향상하였다. This paper studied the effects of the content and the orientation of the disk shape fillers on the modulus of PP composites. The experimental results were compared with the theoretical calculations which included the three dimensional ellipsoids and analyzed by two aspect ratios, ρα=a1/a3 and ρβ=a1/a2 proposed by Lee and his researchers. Mica and talc were used as disk shape fillers in the composites. The shapes of mica and talc were observed by SEM and aspect ratios were statistically calculated. For the case of mica, the average aspect ratios were ρα=13.5 and ρβ=1.8, and for the case of talc, they were ρα=3.8 and ρβ=1.4. Also, the effects of two aspect ratios and the content of filler on the mechanical properties were studied: For 30 wt% of mica, E11 increased up to about 2.7 times, and for the other case of talc, E11 increased up to about 2.3 times, respectively.

Al-Mn合金의 再結晶時의 時效析出

李海容,趙顯麒 慶北大學校 産業開發硏究所 1985 硏究報告 Vol.13 No.-

The age-precipitation during recrystallization of supersaturated cold-deformed Al-Mn alloy has been investigated by means of measurements of microvickers hardness, electrical resistivity and transmission electron microscopy. The results obtained are summarized as follows 1. Increasing Mn contents, precipitation rate in the range below the recrystallization temperature was accelerated and recrystallization temperature increased. 2. In the range below the recrystallization temperature, most of precipitation was progressed before recrystallization and in the range above the recrystallization temperature, most of precipitation was progressed after recrystallization. 3. Precipitated phases were Al_6Mn phases at all examined temperatures and precipitation hardening was negligibly small.

치과용비귀금속합금의 파단조직에 미치는 주형온도의 영향

이기대,정현곤 慶北大學校 齒科大學 1987 慶北齒大論文集 Vol.4 No.1

The purpose of this study was to investigate the effect of mold temperature on the change in fractured microstructure of Ticonium Premium 100 (Ni-Cr alloy) and Regalloy (Co-Cr alloy). Tensile specimens were casted from the types of alloys by centrifugal casting machine in mold temperatures of 500, 600, 700, 800, 900 and 1,000℃. After testing the tensile strength of castings, the microstructure and the pattern of fracture were investigated. The grain size of Ticonium Premium 100 and Regalloy increased with the increase of mold temperature.

스마트 미디어 카드를 이용한 교통사고 영상 저장 방법

이경복,박기현,한민홍 한국경영과학회 2001 한국경영과학회 학술대회논문집 Vol.- No.1(2)

This paper describes a method for saving traffic accident images in SMC(Smart Media Card), which is served as objective proof. SMC served being small-sized, strong, easy to attach and take off, which enables users image and voice-information service such as digital camera, MP3 Player, PDA and so on. Above all on account of it's high-speed in saving. The result of using SMC is saved pictures for 15 second before and after traffic accident image(320×240×8bit) into 8 frames/sec using a voice-recognition method or image recognition method. These pictures can be revived by PDA or mobile computer through up-loading serial/parallel communication or USB communication. This method could be applied to develop BLACKBOX.

체육수업 몰입의 촉진 및 방해 요인 탐색

이현주,김기웅 이화여자대학교 동작과학연구소 2007 이화체육논집 Vol.10 No.-

The purpose of this study is to find out the factors affecting students' flow in the physical class based on the flow experience theory. To do this, this research is to search the factors that facilitate or interfere flow and if such factors show at different degrees by sex. If you can make the conditions for the students to experience flow in their physical classes, physical education at school can be not only the activities of students' active participation but also self-directed ones. For the research, the researcher handed out questionnaires to 480 male and female students in middle schools and high schools in Seoul and analysed 417 of them. The collected data have been analyzed through frequency analysis and two-way ANOVA. Also, of the questions in the questionnaire, open questions have been analyzed through inductive content analysis. The result of this research shows that the factors that facilitate flow in physical classes are preference of specific activities, enjoyment, freedom, peer, the feeling of capability and confidence, physical, emotional and health, the feeling of achievement and competence, instructor, environment, evaluation factor, etc. And the factors that interfere flow in physical classes are dissatisfaction of the content of the class, environment, physical and conditional limit, evaluation, the lack of the feeling of capability and confidence, peer, instructor, management of the class, punishment factor, etc. 15 factors influence flow have been comprised through quantitative analysis and the two-way analysis of variance. They show that there are differences by sex and class in the factors of preference of specific activities, the feeling of achievement and competence, physical and condition, the feeling of capability and confidence, freedom, the lack of the feeling of capability and confidence, environment, friend, evaluation, instructor, enjoyment, and others. There was difference by sex in the dissatisfaction of the content of the class factor and there was not difference by sex and class in management of the class and punishment factor(P<.05). Such results tells that most of the factors influence How in physical classes have difference by sex or class and that these various factors should be considered according to the sex and the class.

NACK 폭주 억제를 이용한 SRM 성능 개선

李演洙,金泰勳,朴惠蓮,李基鉉 明知大學校 産業技術硏究所 2003 産業技術硏究所論文集 Vol.22 No.-

In this paper, we deal with the Negative Acknowledgement(NACK)-Implosion problem that arises in the multicasting environment, and present a scheme to cope with this problem, the modified version of the Scalable Reliable Multicast(SRM) protocol, called SRM-K. This motivates this work in which the NACK message are generated depending on the congestion level inside the network. The occurrence of congestion is determined by estimating the round trip time (RTT) for each message. As an indication of the congestion level, we introduce a counter in each node, whose value K in dynamically adapted to the change of the network situation, namely increases when the congestion builds up and decreases otherwise. The proposed SRM-K scheme is evaluated by performing the simulation, showing that it outperforms the SRM, in particular, in the scenario when the network situation dynamically varies.

Phenazine Methosulfate의 Superoxide Radical 生成作用에 미치는 光線의 影響

李民化,李起榮,梁誠烈,朴昞柱,全鉉權 全南大醫大 1985 전남의대학술지 Vol.22 No.4

NAP 공정을 이용한 하수의 질소 및 인 제거에 관한 연구

이성기,송영일,김현중,진성기 조선대학교 환경연구소 2000 環境硏究 Vol.16 No.1

In the process of NAP(Nightsoil Application Process)to get rid of organism, nitrogen and phosphorus, the retention time in an aerobic tank is set up 4hr, 5hr and 6hr with A1, A2 and A3 reactor the sludge return rate is 50% and the internal return rate is 200%. The change of DO, PH, MLSS, MLVSS, Alkalinity, SBOD, SCOD, Organism, SS, Nutrients and the removal rate of those conditions are followed as below. The removal rate of BOD in each reactor is 81.9% in A1, 83.9% in A2 and 87.2% in A3. The average removal rate of COD is 82.3% in A1, 83.6% in A2 and 88.0% in A3. The average removal rate of SS is 81.9% in A1, 83.9% in A2 and 87.2% in A3. The results show that A3 reactor, which has longer retention time than others in the aerobic tank has better removal rate of organism and SS. The average removal rate of T-N in each reactor is 51.4% in A1, 51.8% in A2 and 60.3% in A3. The average removal rate of T-N is 43.4% in A1, 46.0% in A2 and 52.78% in A3. It indicates that the removal rate is higher when the retention time in the aerobic tank is increased. NAP process can be operated that inserting nightsoil which causes to increase C/N in a reactor affects microorganism activity and increases the removal rate of nutrients in the spite of the decrease of the retention time. If the reactor conditions which are internal return rate, return sludge rate and volume of inserting nightsoil are set up properly. The removal rate can be higher in NAP process than in DNR process in which nightsoil is not inserted.