• 한국대기환경학회지
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• 제13권1호
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• pp.51-63
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• 1997

Total suspended particulate matters in the ambient air were analyzed for eight chemical elements (Ca, Co, Cu, Fe, Mn, Pb, Si, and Zn) using an x-ray fluorescence spectrometry (XRF) at the Kyung Hee University - Suwon Campus during 1989 to 1994. To use these data as basis for source identification study, membership of each sample was selected to represent one of the well defined sample groups. The data sets consisting of 83 objects and 8 variables were initially separated into two groups, fine (d$_{p}$<3.3 ${\mu}{\textrm}{m}$) and coarse particle groups (d$_{p}$>3.3 ${\mu}{\textrm}{m}$). A hierarchical clustering method was examined to obtain possible member of homogeneous sample classes for each of the two groups by transforming raw data and by applying various distances. A disjoint principal component analysis was then used to define homogeneous sample classes after deleting outliers. Each of five homogeneous sample classes was determined for the fine and the coarse particle group, respectively. The data were properly classified via an application of logarithmic transformation and Euclidean distance concept. After determining homogeneous classes, correlation coefficients among eight chemical variables within all the homogeneous classes for calculated and meteorological variables (temperature. relative humidity, wind speed, wind direction, and precipitation) were examined as well to intensively interpret environmental factors influencing the characteristics of each class for each group. According to our analysis, we found that each class had its own distinct seasonal pattern that was affected most sensitively by wind direction.ion.

• 한국정보통신학회논문지
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• 제17권2호
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• pp.481-487
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• 2013

리더의 실제 명령인 payload 데이터의 시작지점을 찾아내는 비트 동기화를 위해 RFID 태그 수신부는 프리앰블을 이용한다. 국제 표준에 의해 RFID PJM(phase jitter modulation) 모드는 MFM(modified frequency modulation) 플래그를 프리앰블로 사용한다. 최근, PJM 모드 태그가 여러 개의 코릴레이터를 이용하여 비트 동기를 수행하는 기법이 발표되었다. 본 논문에서는 coarse synchronization 이후 violation 비트를 이용해서 fine synchronization을 수행하는 새로운 비트 동기화 기법을 제안한다. 시뮬레이션을 통해 제시된 기법이 하드웨어의 복잡도는 낮추면서 기존에 제시된 시스템과 거의 유사한 동기 및 복조 성능을 가짐을 보인다.

• 대한용접접합학회:학술대회논문집
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• 대한용접접합학회 2002년도 Proceedings of the International Welding/Joining Conference-Korea
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• pp.516-521
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• 2002

A study was carried out to grow an understanding of the microstructural development of friction stir welds on an AZ91D magnesium alloy, and to evaluate the mechanical properties of the welds. AZ91D plates with the thickness of 4mm were used, and the microstructural development of the weld zone was investigated using optical and scanning electron microscopes. Square butt welding joint with good quality was obtained at the conditions of under 187mm/min of travel speed with 1100 to 1250 rpm of tool rotation speed. The microstructure within the weld region consisted of fine equiaxed grains with no evidence of the original dendritic structure. The hardness tests showed slightly increased harness in the weld region, and the minimum hardness measured is in that of the parent material. Tensile strength of the weld zone was remarkably improved due to very fine recrystallized structure. XRD pattern of weld zone revealed the removal of $\beta$ intermetallic compounds, $Mg_{17}$Al$_{12}$, which had been distributed in the base metal.l.

• Asian Pacific Journal of Cancer Prevention
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• 제14권1호
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• pp.97-102
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• 2013

Objective: The aim of this study was to develop an automated computer-aided diagnostic system for diagnosis of thyroid cancer pattern in fine needle aspiration cytology (FNAC) microscopic images with high degree of sensitivity and specificity using statistical texture features and a Support Vector Machine classifier (SVM). Materials and Methods: A training set of 40 benign and 40 malignant FNAC images and a testing set of 10 benign and 20 malignant FNAC images were used to perform the diagnosis of thyroid cancer. Initially, segmentation of region of interest (ROI) was performed by region-based morphology segmentation. The developed diagnostic system utilized statistical texture features derived from the segmented images using a Gabor filter bank at various wavelengths and angles. Finally, the SVM was used as a machine learning algorithm to identify benign and malignant states of thyroid nodules. Results: The SVMachieved a diagnostic accuracy of 96.7% with sensitivity and specificity of 95% and 100%, respectively, at a wavelength of 4 and an angle of 45. Conclusion: The results show that the diagnosis of thyroid cancer in FNAC images can be effectively performed using statistical texture information derived with Gabor filters in association with an SVM.

• 한국정밀공학회지
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• 제24권5호
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• pp.97-103
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• 2007

A novel selective metallization process to fabricate the fine conductive line based on inkjet printing has been investigated. Recently, Inkjet printing has been widely used in flat panel display, electronic circuits, biochips and bioMEMS because direct inkjet printing is an alternative and cost-effective technology for patterning and fabricating objects directly from design without masks. The photosensitive etching resist used in this process is an organic polymer which becomes solidified when exposed to ultraviolet lights and has high viscosity at ambient temperature. A piezoelectric-driven inkjet printhead is used to dispense 20-30 ${\mu}m$ diameter droplets onto the copper substrate to prevent subsequent etching. Repeatability of circuitry fabrication is closely related to the formation of steady droplets, adhesion between etching resist and copper substrate. Therefore, the ability to form small and stable droplets and surface topography of the copper surface and chemical attack must be taken into consideration for fine and precise patterns. In this study, factors affecting the pattern formation such as adhesion strength, etching mechanism, UV curing have been investigated. As a result, microscale copper patterns with tens of urn high have been fabricated.

• 한국정밀공학회지
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• 제28권10호
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• pp.1141-1145
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• 2011

Recently, there are many issues about R2R printing technique for mass production of electronic devices. Among the various Roll-to-roll based printing techniques such as gravure, off-set, flexo and so on, "Gravure off-set printing technique" has an advantage of higher printing resolution. The printing unit of gravure off-set printing technique usually consists of plate roll, blanket roll and impressure roll whose. Linear velocities should be synchronized each other for fine pattern printing. However, roller's manufacturing error and printing variations such as pringting pressure, printing speed, roll stroke and so on actually affected their synchronization anf thus the quality of fine fattern. In this paper, we analyzed the effective of synchronization error on printing quality. Also, this paper reviews the relative motion with each roll. And, this paper studys the synchronization error about its generation problem.

• 약학회지
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• 제34권3호
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• pp.206-211
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• 1990

Total suspended particles were collected and size-fractionated by an Andersen high-volume air sampler at Chungang University located near the Han River, Seoul, Korea, during the period form March, 1986 to August, 1986 and from March, 1987 to February, 1988. The concentrations and the particle size distributions of anions such as chloride, nitrate and sulfate were determined by ion chromatography. The averages of concentrations were $125.43\;{\mu}g/m^3$ in 1986 and $189.19\;{\mu}g/m^3$ in 1987 for total suspended particles (TSP), $2.12\;{\mu}g/m^3$ in 1986 and $4.14\;{\mu}g/m^3$ in 1987 for chloride, $4.39\;{\mu}g/m^3$ in 1986 and $5.95\;{\mu}g/m^3$ in 1987 for nitrate and $11.98\;{\mu}g/m^3$ in 1986 and $19.29\;{\mu}g/m^3$ in 1987 for sulfate. Size distribution of TSP was found to be generally bimodal. Chloride exhibited a seasonal variation in the distribution; fine particles were predominant in the winter whereas the concentration of coarse ones was almost same through four seasons. Nitrate showed a distribution similar to that of chloride. Such variation was less significant for sulfate. For chloride and nitrate, the relationship between the monthly averaged distribution pattern and air temperature was analyzed in terms of fine fraction (FF). The FF decreased with increasing air temperature.

• 한국분말재료학회지
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• 제2권1호
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• pp.29-35
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• 1995

In this study the calcined condition and characteristic of Cu-Ni-Zn ferrite powder were investigated. The Cu-Ni-Zn ferrite powder has been synthesized by the thermal decomposition of the organic acid salt. This process did not require a strict pH control and provided the uniform composition and fine powder with about 0.3 $\mu\textrm{m}$. The XRD diffraction pattern of this powder showed about 50% spinel phase. The optimum calcination was found to be done at $700^{\circ}C$ for one hour. After the calcination, the amount of spinel increased to 90%. The distribution of the particle size showed bimodal peaks, one was about 0.5 $\mu\textrm{m}$ and the other was about 20 $\mu\textrm{m}$. The large particles of 20 $\mu\textrm{m}$ were the agglomeration of fine Particles. The mean Particle size of the powder was about 0.4 $\mu\textrm{m}$. The powder was compacted under 100 MPa pressure and sintered at 1100~ $1250^{\circ}C$ for one hour in air. The density of ferrites specimen was a function of the sintering temperature. The higher the temperature, the denser the ferrite. The maximum relative density of the sintered ferrite was about 93% at $1250^{\circ}C$. The grain size of sintered specimen at $1200^{\circ}C$ was 5 $\mu\textrm{m}$ and homogeneous.

• 대한세포병리학회지
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• 제4권1호
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• pp.57-61
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• 1993

Endodermal sinus tumor of the mediastinum is a very rare malignant tumor, usually affecting young adolescents, and its histologic findings are characteristic as that of gonadal germ cell origin. We describe the cytologic finding of fine needle aspiration of mediastinal endodermal sinus tumor in a 19-year-old male patient, comparing with tissue section. The tumor cells in smears were usually in tight clusters with large overlapping cells, which were arranged in a papillary or microacinar pattern, suggesting carcinoma. The tumor cells were large, round or oval with a small amount of cytoplasm which was occasionally vacuolated and had indistinct border. The nuclei were large, pleomorphic, and vesicular with large prominent nucleoli. The tissue sections showed typical findings of endodermal sinus tumor. Careful correlation of cytological findings and the serum alpha -fetoprotein level would be helpful to confirm the diagnosis.

• 대한세포병리학회지
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• 제4권1호
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• pp.30-34
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• 1993

A case of invasive cribriform carcinoma of the breast is presented with fine needle aspiration cytologic features. The aspiration was performed from a papable 2.0 cm mass in the upper outer quadrant of the right breast in a 53 year-old woman. The aspirate showed cellular smear composed of larger three dimensional tight clusters, smaller monolayered loose clusters, and many individual cells on the clean background. In the clusters, the tumor cells were bordering central lumina, quite similar to the cribriform in histology. The tumor cells in the clusters and individual tumor cells had uniform, small and round nuclei. The chromatin was finely granular, and nuclear membrane was smooth No discernible nucleoli were present (nuclear grade $1\sim2$). Unless the abundance of individual cells and the cribriform growth pattern are recognized in the smear, the cytologic diagnosis of invasive cribriform carcinoma is difficult.