• 한국전자파학회논문지
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• 제9권4호
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• pp.483-490
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• 1998

The reflectivity of a grid ferrite electromagnetic wave absorber is analyzed using finite difference time domain (FDTD) method, which is usually used in anechoic chambers for EMI / EMS test. The frequency dispersive characteristics of ferrite medium and its boundary condition are modeled using magnetic flux in addition to E- and H-fields. By applying Floquets theorem, FDTD analysis of the grid ferrite absorber with periodic infinite array is simplified as a unit cell problem. The method of homogenization which is mainly utilized in the calculation of absorber reflectivity as a low frequency technique takes only into account volume fraction of the unit cell of the absorber except for the structure of medium geometry. However, the presented method in this paper can analyze the geometry effect of the unit cell with its medium characteristics up to high frequency region.

• 한국전기전자재료학회논문지
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• 제22권5호
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• pp.382-385
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• 2009

In this study, we studied switching characteristics of germanium selenide(Ge-Se)/silver(Ag) contact formed by photodoping for use in programmable metallization cell devices. We have been investigated the switching characteristics of Ag-doped chalcogenide thin films. Changed resistance range by direction of applied voltage is about $1\;M{\Omega}$ $\sim$ hundreds of $\Omega$. The cause of these resistance change can be thought the same phenomenon such as resistance variation of PMC-RAM. The results imply that the separated Ag-ions react the atoms or defects in chalcogenide thin films.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.373-374
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• 2015

This paper proposes a dynamic thermo-electric model that links electrical parameters with thermal parameters. In this model, the irradiance and ambient temperature are used to calculate the cell temperature based on a four-layer model that includes the PV cell and surround materials. The calculated cell temperature is then used in the electrical model to accurately adjust the PV electrical characteristics. Dynamic PV characteristics, parallel capacitive and series inductive components, are added to the conventional single-diode model. The results show the effectiveness of this model rather than other conventional models of a PV panel.

• 한국발생생물학회지:발생과생식
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• 제4권1호
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• pp.19-28
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• 2000

암컷 미꾸라지, Misgurnus mizolepis와 수컷 미꾸리, M. anguillicaudatus간 잡종과 잡종 3배체를 생산하였으며, 잡종화 및 잡종 3배체화가 망막, 시개 및 trunk kidney에 미치는 영향을 조직학적으로 조사하였다. 잡종은 일부 조직의 핵과 세포 크기에서 양친과 거의 유사하였다. 잡종 3배체는 잡종에 비해 적혈구 세포 및 핵 크기, 망막 내과립층 horizontal cell 핵 크기, 망막신경절 신경세포 층의 신경세포, 시개과립층의 신경세포 핵 및 trunk kidney 2차 근위뇨세관 세포 및 핵 크기에서 증가한 반면 망막 외과립층 수와 2차 근위뇨세관 핵 수에서는 감소하였다. 본 연구 결과 잡종에 비해 잡종 3배체의 일부 조직에서 세포 및 핵 크기 증가를 동반한 세포 수 감소 특성은, 미꾸리류에서의 잡종 및 잡종 3배체의 판별 및 배수화 수준 평가의 한 방편으로 사용 가능할 것이다.

• 한국자동차공학회논문집
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• 제14권5호
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• pp.65-72
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• 2006

In new generation vehicle technologies, a fuel cell vehicle becomes more important, by virtue of their emission merits. In addition, a fuel cell is considered as a major source to generate the electricity for vehicles in near future. This paper focuses on modeling of not only an electric vehicle and but also a fuel cell vehicle to estimate performances. And an EV cart is manufactured to verify the modeling. Speed, voltage, and current of the vehicle and modeling are compared to estimate them at acceleration test and driving mode test. The estimations are also compared with the data of the Ballard Nexa fuel cell stack. In order to investigate a fuel cell based vehicle, motor and fuel cell models are integrated in a electric vehicle model. The characteristics of individual components are also integrated. Calculated fuel cell equations show good agreements with test results. In the fuel cell vehicle simulation, maximum speed and hydrogen fuel consumption are estimated. Even though there is no experimental data from vehicle tests, the vehicle simulation showed physically-acceptable vehicle characteristics.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2005년도 춘계 학술발표회 논문집
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• pp.982-989
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• 2005

In this study, a series of laboratory tests based on 'Unit-cell concept' are performed to investigate improvement characteristics of clay ground in sand compaction pile method. Settlement reduction characteristics of composite ground and improvement characteristics of clay part could be qualified. In these procedure, the new strain-compression index($C_{\epsilon}$) of composite ground are adopted to show compressibility of composite ground according to the area replacement ratio, which is similar to the compression index($C_c$) in pure clay ground. Also, using normalization of reduction of water content in composite ground to the initial water content, improvement characteristics of clay part are investigated.

• 한국기계가공학회지
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• 제12권5호
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• pp.30-35
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• 2013

In order to increase cell efficiency in crystalline silicon solar cell, reduction of light reflection is one of the essential problem. Until now silicon wafer was textured by wet etching process which has random patterns along crystal orientation. In this study, high aspect ratio patterns are manufactured by nano imprint process and reflectance could be minimized under 1%. After that, screen printed solar cell was fabricated on the textured wafer and I-V characteristics was measured by solar simulator. Consequently cell efficiency of solar cell fabricated using the wafer textured by nano imprint process increased 1.15% than reference solar cell textured by wet etching. Internal quantum efficiency was increased in the range of IR wave length but decreased in the UV wavelength. In spite of improved result, optimization between nano imprinted pattern and solar cell process should be followed.

• Biotechnology and Bioprocess Engineering:BBE
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• 제8권6호
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• pp.349-353
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• 2003

The physiological characteristics of cultures of very high cell mass (e.g. 10g cell mass/L), termed“ultrahigh cell density cultures”is reviewed. A close relationship was found between the length of the optical path (OP) in flat-plate reactors and the optimal cell density of the culture as well as its areal (g m$\^$-2/ day$\^$-1/) productivity. Cell-growth inhibition (GI) unfolds as culture density surpasses a certain threshold. If it is constantly relieved, a 1.0cm OP reactor could produce ca. 50% more than reactors with longer OP, e.g. 5 or 10cm. This unique effect, discovered by Hu et al. [3], is explained in terms of the relationships between the frequency of the light-dark cycle (L-D cycle), cells undergo in their travel between the light and dark volumes in the reactor, and the turnover time of the photosynthetic center (PC). In long OP reactors (5cm and above) the L-D cycle time may be orders of magnitude longer than the PC turnover time, resulting in a light regime in which the cells are exposed along the L-D cycle, to long, wasteful dark periods. In contrast, in reactors with an OP of ca. 1.0 cm, the L-D cycle frequency approaches the PC turnover time resulting in a significant reduction of the wasteful dark exposure time, thereby inducing a surge in photosynthetic efficiency. Presently, the major difficulty in mass cultivation of ultrahigh-density culture (UHDC) concerns cell growth inhibition in the culture, the exact nature of which is awaiting detailed investigation.

• 한국컴퓨터정보학회논문지
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• 제9권3호
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• pp.195-200
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• 2004

셀 지연 변이(CDV)에 의한 트래픽 문제를 해결하기 위하여 본 논문에서는 RDT에서의 지연 누적을 보완하면서 RDT의 장점을 활용하기 위하여 RAT방식에서의 셀 도착 시간을 기준으로 하며, 간격 제어기에 따로 데이터 버퍼를 두지 않고 시스템 내의 데이터 버퍼를 사용하여 셀들을 저장하고 저장된 셀들을 이론적 셀 간격시간으로 재방출하는 방식을 제안하였다. 제안한 방식의 성능을 비교하기 위하여 셀 간격 뿐만 아니라 간격제어기에서의 셀 평균 지연특성과 UPC/NPC에서 협상된 트래픽 파라미터의 준수 정도를 나타내기 위해 CDV허용치를 적용하고 분석하였으며, 출력 트래픽의 연속 셀 분산 형태를 분석하였다.

• 한국생산제조학회지
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• 제26권1호
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• pp.1-5
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• 2017

This study investigated the mechanical tearing of a cell membrane using a nanostructured alumina filter for easy and quick mechanical cell disruption. Nanostructured alumina filters were prepared by a multi-step aluminum anodizing process and nanopore etching process. Six different types of nanostructures were formed on the surface of the nanoporous alumina filters to compare the mechanical cell disruption characteristics according to the shape of the nanostructure. The prepared alumina filter was assembled in a commercial filter holder, and then, NIH3T3 fibroblast cells in a buffer solution were passed through the nanostructured alumina filter at a constant pressure. By measuring the concentration of proteins and DNA, the characteristics of mechanical cell disruption of the nanostructured alumina filter were investigated.