• 한국가축번식학회지
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• 제23권1호
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• pp.37-43
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• 1999

계절번식 조류인 꿩을 대상으로 번식기와 비번식기에 따른 세정관과 각 정자형성세포들의 직경, 길이와 면적 등의 변화상을 영상분석기를 이용하여 계측하였다. 그 결과는 다음과 같다. 1. 비번식기 곡세정관은 번식기보다도 약 2.56 배(38.94%) 위축되었다. 비번식기 세정관내에는 세르툴리세포와 정조세포만이 출현하였다. 2. 번식기 정조세포 핵과 세포질의 면적비는 28.71%이었으며, 비번식기의 면적비는 29.11%로 유의성은 없었다. 하지만 비번식기의 정조세포핵과 세포질 면적, 직경 및 둘레는 번식기보다는 증가했다. 3. 번식기 정모세포의 발달과정 중에서 태사기 상태에서 세포면적에 대한 핵의 면적비는 37.40%로 각 정자형성세포들 중에서 가장 높았다. 4. 원형에 가까운 정자세포의 세포면적에 대한 핵 면적비는 22.53%이었다.

• 한국동물학회지
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• 제8권1호
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• pp.11-14
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• 1965

The object to this study is to identify the genus and species of the microfilariae which were recently found in the area of Youngju-Gun. THe identification of the microfilariae was made on the morphologicla aspects. 1. Blood samples were collected through vena punction from known microfilariae carriers living in the newly confirmed filaria endemic area of Youngju0Gun in Jyongsang Pukdo Province. Youngju-Gun is located in the mountainous central part of Korean Peninsula. 2. The following fixation and staining techniques were applied. (1) Fixation by drying in the air, followed by staining with Azeo or Giemsa. (2) Knott's fixation method (2% formalin), followed by staining with Azur II. 3. A comparative study of the body length of the microfilariae after different fixation and staining techniques were applied. (1) Knott's fixation method followed by staining with Azur II : average body length found was 28.4$\mu$. (2) Dry fixation followed by staining with Giemsa : average body length found was 209.4$\mu$. (3) Dry fixation followed by staining with Azeo : average body length found was 205.4$\mu$. 4. The locations of the different body cells were measured in 60 individuals of microfilariae in the wet preparation fixed by Knott's method and stained with Azur II. The distance of the different body cells to cephalic apex of microfilariae was measured and calculated as a percentage of the total body length. The average results are as follows : BNC , 3.04% ; N, 22.74%, EP, 31.4% ; EC, 37.77%, G1 cell , 67.94%; G2 cell, 73.54% : G3 cell , 75.55% ; G4 cell, 77.65% ; AP, 82.02%%. 5. As a result of the above findings the microfilariae found in the above mentioned area could be identified as Brugia malai(BRUG, 1927) BUCKLEY, 1960.

• 대한전자공학회논문지SP
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• 제45권3호
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• pp.103-110
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• 2008

이 논문에서는 8K/2K-Point FFT Radix-4 알고리즘을 CORDIC 연산을 이용하여 효율적으로 나비연산 구조를 설계할 수 있음을 보였다. 즉 CORDIC 연산을 사용하여 cosine 과 sine 값을 저장하지 않고 4개의 복소 곱셈연산을 효과적으로 수행할 수 있음을 보였다. 제안된 CORDIC 나비연산기 구조를 Verilog HDL 코딩으로 구현한 결과, 기존의 승산기를 사용한 나비연산기 구조와 비교하여 36.9%의 cell area 감소 효과를 보였다. 또한 전체 8K/2K-point Radix-4 FFT 구조의 Verilog-HDL 코딩을 기존의 승산기를 사용한 구조의 코딩과 비교한 결과, 11.6%의 cell area 감소효과를 볼 수 있었다. 따라서 제안된 FFT 구조는 DMB용 OFDM 모뎀과 같은 큰 크기의 FFT에 효율적으로 사용될 수 있는 구조임을 보였다.

• Journal of Mechanical Science and Technology
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• 제17권9호
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• pp.1358-1370
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• 2003

The effects of anode, cathode, and cooling channels for a Proton Exchange Membrane Fuel Cell (PEMFC) on flow fields have been investigated numerically. Continuous open-faced fluid flow channels formed in the surface of the bipolar plates traverse the central area of the plate surface in a plurality of passes such as a serpentine manner. The pressure distributions and velocity profiles of the hydrogen, air and water channels on bipolar plates of the PEMFC are analyzed using a two-dimensional simulation. The conservation equations of mass, momentum, and energy in the three-dimensional flow solver are modified to include electro-chemical characteristics of the fuel cell. In our three-dimensional numerical simulations, the operation of electro-chemical in Membrane Electrolyte Assembly (MEA) is assumed to be steady-state, involving multi-species. Supplied gases are consumed by chemical reaction. The distributions of oxygen and hydrogen concentration with constant humidity are calculated. The concentration of hydrogen is the highest at the center region of the active area, while the concentration of oxygen is the highest at the inlet region. The flow and thermal profiles are evaluated to determine the flow patterns of gas supplied and cooling plates for an optimal fuel cell stack design.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1308-1310
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• 1997

Several methods for electrode fabrication of phosphoric acid fuel cell(PAFC) have been studied. The conventional methods that include a coating method and a rolling method, have disadvantages of a very complicated drying process and a hot pressing process for making a large electrode. In this study, to solve these problems, the mixing method of coating and rolling processes has been developed. In the mixing method, the electrode was coated on the electrode support and, after drying the coated layer, was rolled at room temperature and then sintered at $350^{\circ}C$. The single cell performances of the electrodes fabricated by several methods were examined and the mixing method appeared a good cell performance of 0.65 V, $260\;mA/cm^2$. Also the single cell with an area of $2000\;cm^2$ was manufactured and its performance attained 0.593 V, 300 A.

• 한국항해항만학회지
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• 제45권5호
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• pp.231-237
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• 2021

Enhancing the performance of maritime wireless communication has been highlighted by the issue of cell planning in the sea area because of lack of an appropriate Propagation Loss Model (PLM). To resolve the cell planning issue in vast sea areas, it was essential to develop the (PLM) matching the intended sea area. However, there were considerable gaps between the prediction of legacy PLMs and field measurement in propagation loss and there was a need to develop the adjusted PLM (A-PLM). Therefore, cell planning was performed on this adjusted model, including modification of the base station's location, altitude, and antenna azimuth to meet the quality objectives. Furthermore, in order to verify the availability of the cell planning, Communication Service Quality Monitoring System (CS-QMS) was developed in the LTE-Maritime project to collect LTE signal quality information from the onboard equipment at regular intervals and to ensure that the service quality was high enough to satisfy the goals in each designated grid. As a result of verification, the success rate of RSRP was 95.7% for the intensive management zone (IMZ) and 96.4% for the interested zone (IZ), respectively.

• 한국수소및신에너지학회논문집
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• 제20권3호
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• pp.208-215
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• 2009

PEMFC stack power output is needed to be around 100 kW to meet the requirements of automotive application and scaling-up the active area of the stack cells will allow a higher power. In the case of scaling-up the active area of cells, it is difficult to obtain uniform in-plane internal conditions such as temperature, relative humidity and stoichiometry of the feed gas. These ununiformity with the location in the cell would affect both the performance and durability of the stack, so it is important to understand phenomena in the cell for improving them. In this study, the current density, electrochemical resistance and performance distribution measurement was performed to understand the ununiformity in a single cell using in-situ method; (1) Current Density Distribution (CDD) Device and (2) Segmented Cell Fixture. The influence of location of feed gas on the performance of a single cell was experimentally measured and discussed by using a segmented single cell which was composed of 8 compartments. The correlation between the location and performance in a single cell was discussed by these two tools and it was extended between the local characterization and the durability in a MEA by comparing the used cell with a fresh one. It was also studied in terms of electrochemistry by Electrochemical Impedance Spectroscopy.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.101-104
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• 2006

Water management is considered to be one of the main issues to be addressed for the performance improvement of proton exchange membrane (PEM) fuel cell. For good water management, the detailed information on the water distribution inside an operating PEM fuel cell should be available to main an adequate level of hydration in the PEM While avoiding performance decline due to liquid rater flooding. For the PEM fuel cell to be commercially viable as vehicle applications, the flooding on the cathode side should be minimized during the fuel ceil operation. In this study to investigate cathode flooding and its relation with temperature distribution in flow channels, visualization study was performed on the cathode side of a PEM fuel cell. For the direct visualization of temperature field and water transport in cathode flow channels, a transparent cell was designed and manufactured using quartz window. Water transport and its two-phase flow characteristics in flow channels were investigated experimentally. Also, the visualization of temperature distribution In cathode flow channels was made by using IR camera. Results indicated that the temperature rise near the exit of cathode flow channel was found. It is found that this area corresponds to the flooding area from both temperature and flooding visualization results It is expected that this study can effectively contribute to get the detailed data on water transport linked with heat management during the operation of a PEM fuel cell

• 한국농업기계학회:학술대회논문집
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• 한국농업기계학회 2000년도 THE THIRD INTERNATIONAL CONFERENCE ON AGRICULTURAL MACHINERY ENGINEERING. V.II
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• pp.227-235
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• 2000

Agricultural products are easily deformable its shape because of some external forces. However, these force behavior is difficult to measure quantitatively. Until now, many researches on the mechanical property was performed with various methods such as material testing, chemical analysis and non-destructive methods. In order to investigate force behavior on the cellular unit of agricultural products, electro-microscope based 3D image processing method will contribute to analysis of plant cells behavior. Before image measurement of plant cells, plant sample was cut off cross-sectioned area in a size of almost 300-400 ${\mu}$ m units using the micron thickness device, and some of preprocessing procedure was performed with fixing and dyeing. However, the wall structure of plant cell is closely neighbor each other, it is necessary to separate its boundary pixel. Therefore, image merging and shrinking algorithm was adopted to avoid disconnection. After then, boundary pixel was traced through thinning algorithm. Each image from the electro-microscope has a information of x,y position and its height along the z axis cross sectioned image plane. 3D image was constructed using the continuous image combination. Major feature was acquired from a fault image and measured area, thickness of cell wall, shape and unit cell volume. The shape of plant cell was consist of multiple facet shape. Through this measured information, it is possible to construct for structure shape of unit plant cell. This micro unit image processing techniques will contribute to the filed of agricultural mechanical property and will use to construct unit cell model of each agricultural products and information of boundary will use for finite element analysis on unit cell image.

• Journal of Biosystems Engineering
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• 제38권1호
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• pp.55-63
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• 2013

Purpose: The present study aimed at image processing methods for automatic cell pattern recognition and morphological analysis for tissue engineering applications. The primary aim was to ascertain the novel algorithm of adaptive brightness correction from microscopic images for use as a potential image analysis. Methods: General microscopic image of cells has a minor problem which the central area is brighter than edge-area because of the light source. This may affect serious problems to threshold process for cell-number counting or cell pattern recognition. In order to compensate the problem, we processed to find the central point of brightness and give less weight-value as the distance to centroid. Results: The results presented that microscopic images through the brightness correction were performed clearer than those without brightness compensation. And the classification of mixed cells was performed as well, which is expected to be completed with pattern recognition later. Beside each detection ratio of hBMSCs and HeLa cells was 95% and 92%, respectively. Conclusions: Using this novel algorithm of adaptive brightness correction could control the easier approach to cell pattern recognition and counting cell numbers.