NO(Nitric Oxide)에 의한 이자의 외분비 조절작용

한유미,김병무,민본홍,박인선 대한해부학회 2000 Anatomy & Cell Biology Vol.33 No.5

렌즈의 자동초점 구동을 위한 리니어 초음파 모터

김유민, 이한주, 오진헌, 임기조 충북대학교 컴퓨터정보통신연구소 2012 컴퓨터정보통신연구 Vol.20 No.1

In this paper, a novel type ultrasonic linear motor is proposed. The proposed motor consists of a ring type stator and a mover. They have spirals on their inner and outer surface, respectively. Along the spiral, a mover is travelled by a travelling extensional vibration mode of a ring type stator. Hence, a linear up-and-down motion is possible. Through the experimental results, we can verify the applicability regarding the autofocus lens driver. keywords : Ultrasonic linear motor, Autofocusing driver, ring type stator

中學 科學敎育의 探究學習에 대한 評價問項 開發 (Ⅱ)

閔庚德,楊洪準,李善行,鄭遠佑,이병교,金裕漢,羅長薰 경북대학교 과학교육연구소 1985 科學敎育硏究誌 Vol.9 No.-

This study was accomplished to develope the evaluation items for inquiry learning in the 2nd grade Middle School Science for the consecutive study of the evaluation items for inquiry learning in the 1st grade Middle School Science(U-Hang Ki et al, 1984). In this study, paper and pencil test items and performance test items are made by analyzing the abilities of inquiry according to the contents and four basic experiments from each unit in the 2nd grade Middle school science. These evaluation items were applied to tke five classes of the 2nd grade of middle school to test their validity. It is desirable that performance test schuld be used for the evaluation for the abilities of inquiry which can not be evaluated by paper and pencil test. In the evaluation methods of performance test, tester evaluation, peer evaluation and self-evaluation can be applied to the science class in a multi-student class. In higher grade, however tester evaluation is more desirable than peer and self evaluation. It is found that peer evaluation and self-evaluation make possible the perfect study by feedback.

Effect of Chromatin Changes in the Germinal Vesicle on the Development of Porcine Embryos In Vitro

Min‐Gu Lee,Rong‐xun Han,Jin‐Yu zhang,Yun‐Fei Diao,Reza K. Oqani,Dong‐Il Jin 한국동물생명공학회(구 한국동물번식학회) 2011 발생공학 국제심포지엄 및 학술대회 Vol.2011 No.1

In all the studies of mammalian species, chromatin in the germinal vesicle (GV) is initially decondensed with the nucleolus not surrounded by heterochromatin (the NSN configurations). During oocyte growth, the GV chromatin condenses into perinucleolar rings (the SN configurations) or other corresponding configurations with or without the perinucleolar rings, depending on species. During oocyte maturation, the GV chromatin is synchronized in a less condensed state before germinal vesicle breakdown (GVBD) in species that has been minutely studied. As not all the species show the SN configuration and gene transcription always stops at the late stage of oocyte growth, it is suggested that a thorough condensation of GV chromatin is essential for transcriptional repression. Because the GV chromatin status is highly correlated with oocyte competence, oocytes must end the NSN configuration before they gain the full meiotic competence and they must take on the SN/corresponding configurations and stop gene transcription before they acquire the competence for early embryonic development. In this study, we firstly investigated whether the layer of cumulus cells and size of oocytes could determine chromatin configurations in porcine oocytes. Using Hoechst3342 staining, the GV nucleolus and chromatin of porcine oocytes was classified into SN and NSN configurations. Next, we examined the changes in GV chromatin configurations during growth and maturation of porcine oocytes. In addition, the maturation and parthenogenetic development abilities in vitro were significant different between the SN and NSN configurations oocytes. These results indicated that chromatin changes in GV oocytes affect the development potential of parthenogenetic embryos.

수축저감제 혼입률 변화에 따른 콘크리트의 공학적 특성에 관한 연구

한민철,金光華,정규문,정평유,윤성노,한천구 대한건축학회 2003 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.23 No.2

In this paper, tests are carried out using concrete incorporating shrinkage reducing agent(SR) in order to investigate the engineering properties of concrete. The contents of SR and W/C are varied. According to test results, as for fresh concrete, as SR content increases, slump and air content shows decline tendency, and setting time is accelerated with increase of SR content and decrease of W/C. As for compressive strength, as SR contents increases compressive strength shows to be decreased. As for the effect of SR on drying shrinkage, it shows to be reduced with increase of SR content. This is due to the reduced surface tensile strength of water and tensile strength of capillary pore in concrete.

양방향 요소제거법을 이용한 신뢰성 기반 최적설계

유진식,박재용,황승민,임민규,오영규,한석영 한국공작기계학회 2008 한국공작기계학회 추계학술대회논문집 Vol.2008 No.-

This research presents a Reliability-Based Topology Optimization (RBTO) using Bi-directional Evolutionary Structural Optimization (BESO). An actual design involves uncertain conditions such as material property, operational load and dimensional variation. Deterministic Topology Optimization (DTO) is obtained without considering of uncertainties related to the uncertainty parameters. However, RBTO involves evaluation of probabilistic constraints, which can be done in two different ways, the reliability index approach (RIA) and the performance measure approach (PMA). The reliability index approach (RIA) and the performance measure approach (PMA) are adopted to evaluate the probabilistic constraints. In order to apply the BESO method to the RBTO, sensitivity number is defined as the change in the reliability index due to the addition or the removal of the ith element. In the BESO, a mesh-independency filter using nodal variables is used to remove the checkerboard patterns. The optimal topologies of RIA and PMA are obtained very similarly. It is shown that RBTO based on BESO can be effectively applied from the presented examples.

CMOS 전압표준을 이용한 온도보상 전류표준 회로

양한유,홍국태,정강민 成均館大學校 科學技術硏究所 1992 論文集 Vol.43 No.2

본 연구는 외부조건의 영향을 적게 받고 일정한 전류를 발생시켜 주는 CMOS 전류표준 회로를 설계하였다. 이 회로에서 기존에 통상 사용되어 왔던 PTAT 전압원 대신에 특히 온도변화에 독립적인 구조로서 부동전압원에 CMOS 전압표준을 사용한 구조를 제시하였다. 이로서 회로의 정확성, 간결성을 향상시킬수 있다. 시뮬레이션을 통하여 회로의 작동을 검증하고 성능을 토의 하였다. In this work, a CMOS current reference circuit is designed, which is independent of variations of external parametters. A circuit configuration using CMOS voltage reference is suggested and it is shown that this circuit is less sensitive, especially to the temperature variations, compared to the PTAT voltage source. Through simulations, the operation of the circuit is verified and its performance is discussed.

Effect of Ar Plasma Treatment for Surface of Insert Metal on Property of TLP Bonding Joint for Power Module

Baek Seungju,Yu Dong-Yurl,Son Jun-Hyuk,Bang Junghwan,Kim Jungsoo,Kim Min-Su,Lee Han-Bo-Ram,고용호 대한용접접합학회 2020 대한용접·접합학회지 Vol.38 No.4

In this study, we investigated the effect of plasma treatment for the surface of an insert bonding metal on the prop�erties of a transient liquid phase (TLP) bonding joint for a power module. Sn preforms, as the insert bonding metal for the TLP bonding, were used with and without Ar plasma treatment. To investigate the effect of Ar plasma treat�ment, the TLP bonding for two structures of Cu-finished Si chip/Sn preform/organic solderability preservative (OSP)-finished direct bond copper (DBC) substrate (Cu/Sn/Cu), and Ni-finished Si chip/Sn preform/Ni(P)-finished DBC substrate (Ni/Sn/Ni) was performed with 1 MPa at 300 ℃ and the bonding times were 10, 30, and 60 min, respectively. After the TLP bonding, we observed interfacial reactions and formations of intermetallic compounds (IMCs) under various bonding conditions. To evaluate mechanical properties, a shear test was also performed. Compared to the TLP bonding joint that used bare Sn preforms without Ar plasma treatment, growth of IMCs at the bonding joint that used Sn preforms with Ar plasma treatment occurred faster, and the IMCs could be formed through the entire joint despite the bonding time of 10 min. Meanwhile, by increasing the bonding time, Cu6Sn5 and Cu3Sn were formed at the Cu/Sn/Cu TLP bonding joint, whereas Ni3Sn4, Ni-Sn-P, and Ni3P were observed at the Ni/Sn/Ni joint. In the case of the Cu/Sn/Cu joint, we observed that increasing Cu3Sn formation while increasing the bonding time could be beneficial to the shear strength of the joint. Further, shear strengths of the joint were not sig�nificantly changed under the bonding conditions after Ni3Sn4, Ni-Sn-P, and Ni3P IMCs were formed at the entire joint of the Ni/Sn/Ni.

수축저감제와 혼화재를 병용한 콘크리트의 공학적 특성

金光華,김종,한민철,정평유,한천구 대한건축학회 2004 대한건축학회 학술발표대회 논문집 - 계획계/구조계 Vol.24 No.1(구조계)

The objective of this paper is to investigate the physical and mechanical properties of concrete incorporating shrinkage reducing admixture(SRA) and mineral admixture(MA) such as fly ash and blast furnace slag powder. According to results, for fresh concrete properties, increase of SRA content leaded to reduce the fluidity and air content sharply. For setting time, use of SRA caused concrete to accelerate setting time, and compared with plain concrete it retarded by incorporating MA. Compressive strength decreased with an increase in SRA content, and when incorporating MA, compared with plain concrete, it shows lower compressive strength in early age but similar or increase by the elapse of age due to the pozzolanic and latent hydration reaction. For drying shrinkage, concrete shows decline tendency with an increase in SRA content due to the relaxation effect at the capillary tension in concrete by SRA. In the scope of this paper, it is found that the use of SRA with 1.0% has optimum effects on the various properties of concrete, and the combinations of SRA and fly ash will ensure the stability for drying shrinkage.

엄지발가락에 발생한 건초 섬유종 1예

이경호,조유경,한예원,김진아,김형민,박철종 대한피부과학회 2006 大韓皮膚科學會誌 Vol.44 No.4