• Radiation Oncology Journal
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• v.10 no.1
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• pp.85-93
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• 1992

We have studied the dosimetric properties of electron beam using Lyon intraoperative device for intraoperative radiation therapy. The dosimetry data had compiled in such a way that a quick and correct decision regarding the cone shape, energy, and accurate calculations could be made. Using 3 dimensional water phantom, we have got the following data: cone output ratios, surface dose, $d_{max}$, $d_{90}$, flatness, symmetry, beam profiles, isodose curve, and SSD correction factors. The cone output ratios were measured with straight and bevelled cone, respectively. As the cone size and the energy were reduced, the cone output ratios decreased rapidly. With the flattening filter, the surface dose increased by electron beam to $85.3\%$, $89.2\%$, and $93.4\%$, for 6 MeV, 9 MeV, and 12 MeV, respectively. It is important to increase the surface dose to $90\%$ or more. Inspite of diminishing dose rate and beam penetration, this flattening filter increases the treatment volume significantly. With the combination of the three levels collimation and the flattening filter, we achieved good homogeneity of the beam and better flatness and the diameter of the 90$\%$ isodose curve was increased. It is important to increase the area that is included in the $90\%$ isodose level. The value of measured and calculated SSD correction factors did not agree over the clinically important range from 100 cm to 110 cm.

• Proceedings of the Korea Information Processing Society Conference
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• 2011.04a
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• pp.382-383
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• 2011

초고전압 투과전자현미경으로부터 생산된 2D 이미지들에는 고전압(1250 kV)의 사용으로 인한 다양한 노이즈가 발생한다. 따라서 2D 이미지로부터 3D tomogram으로 재구성시 선명도 향상을 위하여 2D 이미지의 노이즈 제거 과정은 필수적이다. 본 연구에서는 band-pass filtering 기법을 활용하여 노이즈를 상당 부분 제거하였고, 필터링된 이미지로부터 3D tomogram으로 재구성한 경우 band-pass filtering의 효과가 2D 이미지에서 뿐만아니라 3D tomogram으로 재구성 했을 경우에 어떤 대역의 filter radius를 적용해야 더욱 효과가 크다는 사실을 확인하였다.

• Journal of the Korean Society of Tobacco Science
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• v.27 no.1 s.53
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• pp.75-82
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• 2005

This work investigated biodegradability for the cellulose acetate, carbon dual, paper and web used to cigarette filter materials by soil test. Also, because of demanded a lot of the time and effort in case of soil test, the possibility of biodegradation by enzyme was studied. The evaluation of degradation for the filter materials by soil test was examined with the naked eye, electron microscopy and weight loss. The biodegradability according to the filter materials was represented in the order of paper > web > carbon dual > cellulose acetate without relating to the evaluation methods. Experiment of biodegradability by the cellulase(E C 3.2.1.4, Trichoderma viride) among the several biodegradability enzymes was demanded reaction time of the $5\~10$ hours and represented the same result with that of soil test.

• Applied Microscopy
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• v.42 no.2
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• pp.105-109
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• 2012

Electron tomography (ET) of biological specimens is performed from a series of images obtained over a range of tilt angles in a transmission electron microscope. When using the high voltage electron microscope (HVEM), various noises appear in EM images acquired from thick sections by high voltage electron beam. In order to obtain an adequate result in electron tomograms that allow visualization of rather complex and mega-cellular structure such as brain tissue, it is necessary to remove the noise in each original tilt images of thick section. Using band-pass filtering of original tilt images, the filtered images are obtained and used to assemble a reconstructed tomogram. The qualified 3D tomogram from filtered images results in a considerable reduction of the noises compared to conventional tomogram. In conclusion, this study suggests that band-pass filtering is effective to improve the brightness and intensity of HVEM produced tomograms acquired from micron-thick sections of biological specimens.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.12
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• pp.873-878
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• 2014

The applicability of carbon nanotube (CNT) to slow sand filtration for the removal of bacteria was studied using scanning electron microscope and column experiments. The morphology of CNT were investigated using scanning electron microscope and the CNT looked like a skein serving bacteria favorable site for adhesion. Column experiments were performed over a range of CNT filter depth, pH, and ionic strength. Bacteria removal efficiency was found to increase from 44.15% to 99.95% as the CNT filter depth increased from 1 cm to 5 cm, and 3 cm of CNT filter depth was required for significant removal of bacteria. pH increase from 5.5 to 8.5 decreased the bacteria removal efficiency, due to the electrostatic repulsion between bacteria and CNT at higher pH. Bacteria removal efficiency decreased from 97.25% to 70.90% as the ionic strength increased from 0 mM to 50 mM. This study demonstrated that the CNT can be applied to slow sand filtration for treating microbially contaminated water.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2010.06a
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• pp.265-265
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• 2010

일반적으로 중금속이나 질산성 질소와 같은 이온성 물질들은 사람의 건강이나 생태계에 좋지 않은 영향을 미칠 수 있다. 이들 오염물질들은 그 종류에 따라 건강에 피해를 주는 정도에 차이가 있지만 안전한 생태환경을 유지하기 위해서는 이들 물질들을 효과적으로 처리할 수 있는 필터가 필요하다. 전극 필터에 최대한 많은 이온들을 흡착시키기 위해서는 전극의 비표면적을 높이는 것이 매우 중요하다. Metal Fiber Filter의 제작과 제작된 Filter의 전기적 특성과 비표면적 향상, 고정성 및 통전성, 축전용량과 전기흡착 및 탈착 경향을 관찰하기 위해 3전극 시스템을 이용하여 Cyclic Voltammetry(CV)와 Chrono-amperometry(CA)를 측정하고 표면의 기공 구조를 관찰하기 위해 주사전자현미경 (SEM;Scanning Electron Microscope)을 이용하여 전극에 생성된 미세 기공의 크기 및 크기 분포를 측정한다. 또한 제작된 Filter 전극을 이용하여 전기장 하에서 수질 속에 있는 질산성이온의 선택적 제거 효율을 측정하여 보고, 측정된 데이터 값을 통해 Metal Fiber Filter의 전기적 특성과 중금속이나 질산성 이온 물질들을 선택적으로 제거할 수 있는 Filter 전극 설계 근거를 제시하고자 한다.

• Journal of the Korean Society of Tobacco Science
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• v.21 no.2
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• pp.136-143
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• 1999

This study was conducted to evaluate the degradation characteristics of waste cigarette filters under 0, 5, 10, and 15cm in depth from soil surface by environmental conditions. Weather was the most important factor during degradation of waste cigarette filters in this study. Bulking of cellulose acetate filaments exposed on soil surface was observed after 2 months, but the form of filter was kept up after 12 months. The treated cigarette filters in soil landfill revealed a little different degradation pattern at each soil landfill depth, The sample in 5cm depth of soil was more degraded then other site. A fluffy appearance of cellulose acetate filaments in the control filter rods was also developed more strongly in soil landfill then on soil surface. From the observation of waste cigarette filters by scanning electron microscopy, much degradation of the fiber of waste cigarette filters could be ascertained in soil landfill. The weight of waste cigarette filters under 5cm from soil surface was reduced about 50%, and the tensile strength of the samples in soil surface and under 5cm from soil surface were reduced 66.0% and 92.4%, respectively. The microbial experiment date that the viable cell number in microbial population and cellulolytic microorganisms showed the maximum values under 5cm from soil surface, suggest that microorganisms in soil play an important roll in the degradation of acetate cigarette filters.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.235-244
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• 2006

A PCF(Pore Controllable Fiber Filter) process was applied as a pretreatment of water treatment for reduction of turbidity. The experimental results obtained from the PCF showed that the removal efficiency of turbidity without coagulation was around over 70 percent. However, the removal efficiency of turbidity by the coagulation-PCF process was high as much as over 95%. Thus, the coagulation pretreatment was required for the better operation of the PCF. The SEM (Scanning Electron Microscope) images of fiber before and after filtration showed that the filtration mechanism of PCF filter is both controlling attachment mechanism and Sieving mechanism through fiber pore. For the coagulation-PCF process, optimum dosage of coagulant was needed for the economical operation, and for this, determining the optimum dosage by using a filter column test. Also only 16mg/L of alum was used to obtain high algae removal efficiency over 90%. Therefore, it can be concluded that coagulation-PCF process is very effective pretreatment process for algae removal.

• Korean Chemical Engineering Research
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• v.52 no.3
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• pp.378-381
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• 2014

We studied the pasteurization effect of the microorganism involved in the water, using ion-exchanging filter made of the Radiation Induced Grafted Polymerization. This ion-exchanging filter is made by the graft polymerization of GMA, after irradiation of electron beam to the non-woven filter. Then, we made the ion-exchanging filter (EtA, DEA, SS) applying ion-exchanging base to the GMA filter. As a result, the density of the ion-exchanging base is shown as 2.38 mol/kg in case of EtA, 1.79 mol/kg in case of DEA and 0.75 mol/kg in case of SS. Through this filter made by this method, we measured the pasteurization power of E. coli. We found very high elimination rate such as log 4.65 in case of SS-dial filter, which is higher as 3.00 times in comparison with EtA, and 1.10 times in comparison with DEA. This data show the result is very excellent comparing with 3,000 CFU/ml. of city water treatment basis.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.173-176
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• 2002

An efficient design method for E-plane waveguide bandpass filter has been developed. The analysis method for E-plane discontinuities with finite length is based on Generalized Scattering Matrix (GSM) method. Furthermore, the design portion is based on the filter synthesis method. Waveguide bandpass filters designed with this method have been fabricated and measured. Excellent agreements with design have been obtained