• 한국작물학회지
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• 제45권3호
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• pp.207-210
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• 2000

생강의 개화특성과 화기구조를 관찰하고 약배양에 의한 캘러스 형성과 식물체 재분화에 미치는 배지내 생장조절물질의 효과에 대하여 검토한 결과는 다음과 같다. 1 화병의 형성은 국내종은 서산종, 도입종은 태국종에서만 출현되었으며 화뢰당 소화형성은 서산종 8개, 태국종이 10개 형성되었으나 종자정성은 이루어지지 않았다. 2. 개화기는 8월 18일에서 8월 25일 사이에 불규칙적으로 나타났고 1일중 개화시각은 오후 4시-5시 사이에 대부분 개화하였다. 3. 꽃은 장주화로서 주두상단에는 섬모가 나 있으며 수술은 연착약, 배낭내 태좌는 증축태좌 형태를 나타냈다. 화분은 원형과 타원형이 혼재되어 있으나 원형이 많았으며, 화분막은 2중 구조였다. 4. 약 유래 캘러스 형성에는 CM배지가 좋았고, 캘러스로부터 기관분화는 MS배지에 BA 2mg/l 를 첨가한 재생배지에 이식 후 40일경부터 부정근이 먼저 출현되고 배양 60일 후에는 줄기와 뿌리가 완전 분화된 정상적인 식물체를 얻을 수 있었다.

• 정보처리학회논문지C
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• 제8C권1호
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• pp.97-104
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• 2001

본 논문에서는 무선망에서 채널할당을 받은 호가 무선 패킷 데이터를 서비스하는 경우의 성능분석 수행을 위한 계층 모델을 제안한다. 제안된 계층 모델로는 상위계층으로 무선자원 관리를 위한 채널할당 모델을, 하위계층으로 에러발생을 고려한 패킷 재전송 프로토콜 모델을 고려하였으며 이들 모델은 모델링 도구인 SRN을 이용하여 각각 개발한다. 추계적 페트리 네트의 확장형인 SRN은 시스템 성능분석을 위한 간결한 모델링 기능을 제공해 주며 모델에 적절한 보상률(reward) 기능을 부여함으로써 원하는 성능지표를 구할 수 있다. 이들 두 계층간의 상호 연관된 매개변수의 값인 서비스 시간과 패킷 발생률은 고정점 반복순환(fixed-point iteration) 기법을 사용하여 구한다. 즉 상위계층의 호 서비스 시간은 한 호당 K개의 패킷전송을 완료할때 까지 소요되는 시간인 하위계층 모델의 지연시간으로 구할 수 있고, 하위계층 모델의 패킷 발사율은 상위계층의 새로운 호와 핸드오프 호의 발생률로부터 구할 수 있다.

• 한국재료학회지
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• 제16권3호
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• pp.178-182
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• 2006

A single electro-discharge-sintering (EDS) pulse (1.0 kJ/0.7 g), from a $300{\mu}F$ capacitor, was applied to atomized spherical Ti-6Al-4V powder in a low vacuum to produce porous-surfaced implant compacts. A solid core surrounded by a porous layer was formed by a discharge in the middle of the compact. XPS (X-ray photoelectron spectroscopy) was used to study the surface characteristics of the implant material. C, O, and Ti were the main constituents, with smaller amounts of Al, V, and N. The implant surface was lightly oxidized and was primarily in the form of $TiO_2$ with a small amount of metallic Ti. A lightly etched EDS implant sample showed the surface form of metallic Ti, indicating that EDS breaks down the oxide film of the as-received Ti-6Al-4V powder during the discharge process. The EDS Ti-6Al-4V implant surface also contained small amounts of aluminum oxide in addition to $TiO_2$. However, V detected in the EDS Ti-6Al-4V implant surface, did not contribute to the formation of the oxide film..

• 한국재료학회:학술대회논문집
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• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
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• pp.136-136
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• 2003

In fiber optic networks, system size and cost can be significantly reduced by development of optical components through planar optical waveguides. One important step to realize the compact optical devices is to develop planar optical amplifier to compensate the losses in splitter or other components. Planar amplifier provides optical gain in devices less than tens of centimeters long, as opposed to fiber amplifiers with lengths of typically tens of meters. To achieve the same amount of gain between the planar and fiber optical amplifier, much higher Er doping levels responsible for the gain than in the fiber amplifier are required due to the reduced path length. These doping must be done without the loss of homogeniety to minimize Er ion-ion interactions which reduce gain by co-operative upconversion. Sol-gel process has become a feasible method to allow the incorporation of Er ion concentrations higher than conventional glass melting methods. In this work, Er-doped $SiO_2$-A1$_2$ $O_3$ films were prepared by two different method via sol -Eel process. Tetraethylorthosilicate(TEOS)/aluminum secondary butoxide [Al (OC$_4$ $H_{9}$)$_3$], methacryloxypropylcnethoxysaane(MPTS)/aluminum secondary butofde [Al(OC$_4$ $H_{9}$)$_3$] systems were used as starting materials for hosting Er ions. Er-doped $SiO_2$-A1$_2$ $O_3$ films obtahed after heat-treating, coatings on Si substrate were characterized by X-ray din action, FT-IR, and N-IR fluorescence spectroscopy. The luminescence properties for two different processing procedure will be compared and discussed from peak intensity and life time.

• 한국항행학회논문지
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• 제12권3호
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• pp.220-226
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• 2008

본 논문에서는 ${\lambda}/4$ 임피던스 변환기를 피킹 증폭기 뒷단에 배치하고, 주 증폭기와 피킹 증폭기가 서로 다른 비대칭 구조의 도허티 증폭기 만들어 효율을 개선시키는 방법을 제시하였다. 이러한 구조는 다단 도허티 증폭기 구현 시 작은 크기로 구현이 가능하며, 기존의 전기적 특성과 동일함을 시뮬레이션을 통해서 확인하였다. 이러한 구조를 갖는 전력 증폭기를 제작하였으며, W-CDMA 기지국 송신 대역에서 IFA 신호를 인가하였을 때, 45W 출력 기준으로 8dB 백-오프 지점에서 26.3%의 전력부가효율을 얻었고, 중심 주파수에서 ${\pm}5MHz$이격 지점 에서 -40.4dBc의 인접채널 누설비 (Adjacent Channel Leakage Power : ACLR)를 확인하였다.

• Asian-Australasian Journal of Animal Sciences
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• 제14권6호
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• pp.754-758
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• 2001

Bovine oocytes with compact and complete cumulus cells were cultured for up to 24h in TCM199 buffered with 25mmol/l hepes and supplemented with 10% FBS (fetal bovine serum), 1mg/ml $17{\beta}$-estradiol, 20IU/ml hCG(human chorionic gonadotropin). All of the oocytes were divided into at 6 groups depending upon incubation times (control, 0 hour, 6 hours, 12 hours, 16 hours, 18 hours). To all experimental media, $200{\mu}g/ml$ puromycin was added at different incubation times mentioned above. Following these culture times, in vitro insemination was conducted with frozen-thawed bovine spermatozoa in medium BO (Brackett and Oliphant medium for in vitro insemination) with $10{\mu}g/ml$ BSA(bovine serum albumin) and 10 mg/ml heparin added. After 22h culture, the oocytes were fixed with acetic alcohol solution and stained with orcein acetic solution to evaluate sperm nuclear progression. Addition of puromycin after 0, 6 and 12 h of culture resulted in near of oocyte maturation at the M1 stage. Contrariwise, puromycin addition after 12 h of culture led to restoration of nuclear progression to M2 stage. On the one hand, puromycin affected the synthesis of Cyclin B protein that may be involved in the oocyte maturation and sperm capacitation for in vitro fertilization. The present study suggests the participation of protein synthesis, cyclin B, in the oocyte development from M1 to M2 stages in vitro.

• 연구논문집
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• 통권23호
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• pp.127-140
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• 1993

The drive pulley, which is employed for loading and unloading raw materials in a steel mill, is usually manufactured by use of various welding processes. In this study the weldment in the pulley, in which TIG and $CO_2$ welding processes are used, has been analyzed from view point of fracture mechanics. Fracture toughness tests have been performed according to ASTM E813. A servo-hydraulic testing machine (10kN) has been employed. Also the crack propagation tests (Mode I) have been performed with compact tension specimen in compliance with ASTM E647. To predict the critical crack size in the weldment, finite element stress analysis for the drive pulley under real operating conditions have been performed. In addition, the residual stresses at the weldment and in heat-affected zone have been obtained by hole drilling method. The planar critical crack size have been predicted for the drive pulley by considering the stress analysis results and the residual stresses due to welding process. For the drive pulley considered in this study, it has been concluded that the most important factor in determining the critical crack size is the welding residual stress in the transverse direction. Also the effect of stress concentration at the root of the weldment have been noticeable. For the planar crack, the fatigue crack growth life from an initial crack size of 2mm to the critical crack size obtained as in the above have been predicted. The predicted lives were between 55, 900 and 72, 000 cycles depending on the shape of the elliptical crack. The predicted lives were in fairly good agreement for the drive pulley considered in this study.

• 한국의상디자인학회지
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• 제16권1호
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• pp.53-64
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• 2014

The main objective of this research was to understand the characteristics of printed geometric patterns through the statistical & qualitative analysis of fashion appeared in contemporary female collections 2011 S/S to 2013 A/W. Data collection of 294 was done through review of 'pr$\hat{e}$t-$\grave{a}$-porter Collections' of three major fashion cities; Paris, Milan and NY. Statistical analysis of frequency was conducted. Also qualitative interpretation of natural print design' characteristics were completed. The main findings were as followed; 1,636 of the total 15,852 designs were printed patterns in 12 Collections and the occurrence rate of printed geometric patterns in three collections were 8.6% in Milan, 9.2% in Paris and 12.9% in N.Y. Most geometric patterns were the types of compact or medium density in a front patterns with a variety of sizes and mainly applied to the one piece dress or two piece clothing item combination styles. Formative Characteristics of printed geometric patterns were classified into four types. First, a variety of thicknesses and shapes, such as a line or a rectangle shape to take advantage of the types of the typical geometric pattern. Second types were using the motifs which inspired by geometric shapes such as point, circle star and other special geometric shapes and arranging them regularly with various sizes and density. The third was repeated particular motifs which based on complex and sophisticated mathematical formulas. Fourth were the specific diagram types of bold and free shapes or dividing the flat and arranging them without rules, or the combination type of various geometric motifs.

• 천문학회보
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• 제42권2호
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• pp.66.2-66.2
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• 2017

The Korea Astronomy and Space Science Institute plans to develop a coronagraph in collaboration with National Aeronautics and Space Administrative (NASA) and install it on the International Space Station (ISS). The coronagraph is an externally occulted one stage coronagraph with a field of view from 2.5 to 15 solar radii. The observation wavelength is approximately 400 nm where strong Fraunhofer absorption lines from the photosphere are scattered by coronal electrons. Photometric filter observation around this band enables the estimation of 2D electron temperature and electron velocity distribution in the corona. Together with the high time cadence (< 12 min) of corona images to determine the geometric and kinematic parameters of coronal mass ejections, the coronagraph will yield the spatial distribution of electron density by measuring the polarized brightness. For the purpose of technical demonstration, we intend to observe the total solar eclipse in 2017 August for the filter system and to perform a stratospheric balloon experiment in 2019 for the engineering model of the coronagraph. The coronagraph is planned to be installed on the ISS in 2021 for addressing a number of questions (e.g. coronal heating and solar wind acceleration) that are both fundamental and practically important in the physics of the solar corona and of the heliosphere.

• Toxicological Research
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• 제24권3호
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• pp.227-233
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• 2008

To detect lead ions using electrochemical voltammetric analysis, Infrared Photo-Diode Electrode(IPDE) was applied via cyclic and square wave stripping voltammetry. Lead ions were deposited at 0.5 V(versus Ag/AgCl) accumulation potential. Instrumental measurements systems were made based on a simple and compact detection system. The stripping voltammetric and cyclic voltammetric optimal parameters were searched. The results yielded a cyclic range of $40{\sim}240mgl^{-1}$ Pb(II) and a square wave stripping working range of $0.5{\sim}5.00mgl^{-1}$ Pb(II). The relative standard deviation at 2 and 4 $mgl^{-1}$ Pb(II) was 0.04% and 0.02%(n=15), respectively, using the stripping voltammetric conditions. The detection limit was found to be 0.05 $mgl^{-1}$ with a 40 sec preconcentration time. Analytical interference ions were also evaluated. The proposed method was applied to determine lead ions in various samples.