• Proceedings of the KIEE Conference
• /
• 2011.07a
• /
• pp.2005-2006
• /
• 2011

Due to the advantages of small sizes, more I/O ports, etc., Ball Grid Array (BGA) has been used in the production of printed circuit board (PCB). However, BGA voids can degrade the performance of the board and cause failure. To automatically detect the voids in X-ray image, a novel blob filter that makes use of the local image gradient magnitude is proposed in this paper. The utilization of the local image gradient magnitude makes the proposed filter invariant to the image brightness, void shape, void position, and component interference. Furthermore, different sizes of box filters are employed to analyze the image in multi-scale, and as a result, the proposed blob filter is robust to void size. Experimental results show that the proposed method can obtain void detection accuracy up to 96.104% while keep low false ratio.

• Journal of Radiation Protection and Research
• /
• v.16 no.1
• /
• pp.15-24
• /
• 1991

Radon-222 exhalation rate from several domestic building materials were experimentally measured by using radon cup method, in which a CR-39 plastic is used as a passive radon detector. The radon detection factor of CR-39 detector determined in a series of calibration experiments was $0.164{\pm}0.005(tracks\;cm^{-2}/Bq\;d\;m^{-3})$, which is consistent with those reported by other investigators. The radon exhalation rates of several building materials (brick, red brick, concrete block, granite plate, concrete floor and wall) ranges from $6.8{\times}10^{-6}\;(granite plate)\;to\;75.0{\times}10^{-6}Bq/m^2-sec(brick)$ with the increasing order of granite plate, red brick, concrete wall, concrete block, concrete floor and brick. It showed that the CR39 radon cup can be efficiently utilized in measuring the radon-222 gas exhalation rate from building materials.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2010.08a
• /
• pp.38-38
• /
• 2010

낮은 세기의 레이저와 정지한 전자가 반응하면 전자는 레이저 전기장 세기에 비례하여 가속되며 레이저의 파장과 같은 파장의 빛을 낸다. 반면, 레이저의 세기가 일정 수준을 넘으면 전자의 속도가 빛의 속도에 가까워지게 되어 가속이 둔화되는 현상이 나타나며, 더 이상 전기장의 세기와 가속도가 비례하지 않게 된다. 이러한 비선형적인 전자의 운동이 레이저 기본 파장의 조화파(harmonic)를 발생시키는데, 이를 상대론적 비선형 톰슨 산란(relativistic nonlinear Thomson scattering, RNTS)이라고 한다. 단일 전자를 가정한 경우 RNTS에 의해 아토초($10^{-18}$ 초) 길이의 X선 펄스가 발생하는 것이 시뮬레이션 연구를 통해 잘 알려졌다. [1] 그러나, 실제 실험에서 적용할 수 있는 것은 단일 전자가 아니라 고체, 플라즈마, 전자 빔 등의 전자 덩어리이다. 전자덩어리를 구성하는 각각의 전자가 아토초 펄스를 발생시더라도 각각의 펄스 간에 결맞음(coherence) 조건이 맞지 않으면 아토초 펄스는 발생되지 않는다. 또한, 강한 세기의 펄스를 얻는데도 결맞음은 중요하다. 이 연구에서는 결맞음 조건으로 얇은 타깃에 대한 거울 반사 조건, 즉 레이저가 얇은 타깃에 입사되며 거울의 반사 조건을 만족하는 위치에 검출기(detector)를 위치시키는 방법을 제안하였다. 박막이 충분히 얇을 경우 각각의 전자에 대하여 레이저가 발사되어 타깃에 맞고 검출되기까지의 시간이 거의 일치하게 된다. 거울 반사 조건에 의한 아토초 펄스 발생은 particle-in-cell 방법을 통한 시뮬레이션으로 검증되었다. 결맞음 조건을 위한 얇은 타깃으로는 박막과 나노선 배열(nanowire array)을 사용하였다. 전자들 간의 쿨롱(Coulomb) 힘은 결맞음이 유지되는 것을 방해하는데, 박막에 비해 나노선 배열이 쿨롱 힘의 영향을 적게 받기 때문에 결맞음이 더 잘 유지된다.

• Proceedings of the Korea Multimedia Society Conference
• /
• 2002.05c
• /
• pp.170-175
• /
• 2002

영상분할이나 연결요소 추출 등에 의해 구해진 물체 영역의 경계 부분에 잔가지 모양으로 나타나는 잡영가지는 물체의 형상 특징 연산 및 인식 과정에서 오류를 일으키는 원인이 되므로 효과적으로 제거할 수 있는 방법이 필요하다. 기존의 연구에서는 한 픽셀 두께의 잡영가지만을 제거할 수 있는 방법이 제안되었다. 본 연구에서는 부분적으로 두 픽셀 이상이 뭉쳐져 둥그스름한 덩어리(blob, 블럽)를 형성하고 있는 잡영가지도 4-8-방향 윤곽선 추적에 의해 제거할 수 있는 방법을 제안한다. 먼저 잔가지를 구성하고 있는 픽셀과 물체 영역을 구성하는 픽셀을 개략적으로 분리한 후, 윤곽선 추적물 하면서 사용자가 정의한 크기보다 작은 블럽을 포항한 잔가지를 추출해낸다. 이어서, 이러한 잔가지를 사용자가 정의한 잡영가지의 크기와 비교하여 최종적으로 제거할 수 있도록 한다. 이와 같이 사용자 입력 변수에 따라 잡영가지에 대한 개념을 보다 확장하여 자유롭게 정의할 수 있도록 명시화 함으로써, 영상의 특성에 따라 보다 유연하게 잡영가지를 정의하여 제거할 수 있도록 하였다.

• Journal of Korea Multimedia Society
• /
• v.6 no.3
• /
• pp.419-428
• /
• 2003

Several methods have been studied to prune the parasitic branches that cause unfortunately from thinning a shape to get its skeleton. We found that the symmetric path finding method was most efficient because it followed the boundary pixels of the shape just once. In this paper, its extended method is proposed to apply to removing the noise branches that protrude out of the boundary of a segmented or extracted shape in a given image. The proposed method can remove a noise branch with one-pixel width and also remove the noise branch that includes a round shape called a noise blob. The method uses a 4-8-directional boundary-following technique to determine symmetric paths and finds noise branches with noise blobs by detecting quasi-symmetric paths. Its time complexity is a linear function of the number of boundary pixels. Interactively selectable parameters are used to define various types of noise branches flexibly, which are the branch - size parameter and the blob-size parameter. Experimental results for a practical shape and various artificial shapes showed that the proposed method was very useful for simplifying the shapes.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.5
• /
• pp.887-894
• /
• 2000

The purposes of this study are investigation of species of attached algae and the relation between attached algae and odor in tap water, Oscillatoria sp. and Mougeotia sp. were colonized at sedimentation basin in water treatment plant. Resulting from analysis, 3.7ppt of geosmin and dimethyl-disulfide with trace were detected in sample of Oscillatoria sp. only, 22 compounds were found in each of sample that had been incubated in room temperature for 5 days, 17 compounds were generated by algal decay. Decayed products were sulfur compounds of 10 species such as dimethyl-sulfide and phenol, p-cresol, indole and scatole. So, it is assumed that attached algae which tolerant to chlorine was the origin of odor in tap water. They usually formed big colonies. Colonies on the bottom were decayed because of anaerobic state. While decaying they were detached from colonies and so, odorous compounds are originated from this decayed algae.

• Journal of the Korean Magnetics Society
• /
• v.16 no.6
• /
• pp.305-308
• /
• 2006

Magnetic flux leakage (MFL) pigs are traditionally used for the detection of gross corrosion on steel pipelines used for the transmission of natural gas. Alternative nondestructive evaluation (NDE) modalities are required for the detection of stress corrosion cracking (SCC) which tends to exist in colonies oriented axially along the length of the pipeline. This paper describes the use of multiphase rotating magnetic fields in the remote region of the probe as a possible SCC detection mechanism. Details of a prototype pig and test rig are given and the challenges associated with the finite element modeling of the device are discussed. Initial experimental results show that this novel NDE modality is sensitive to axially oriented tight cracks.

• Journal of the Mineralogical Society of Korea
• /
• v.5 no.1
• /
• pp.22-31
• /
• 1992

The Sancheong kaolin was fractionated into 9 size fractions by wet sieving, sedimentation, and centrifugation. The systematic X-ray diffraction combined with electron microscopy shows that the clay mineral composition of each size fraction is related to the original fabric of kaolin. Minerals such as halloysite (10${\AA}$), kaolinite, illite, and goethite which were formed by procipitation from solution are generally concentrated in the finer fractions, whereas verniculite which was formed by pseudomorphic transformation from other primary minerals are concentrated in the coarser factions. Kaolinits of various types which were formed by precipitation or transformation show a wide size range but they are generally concentrated in the coarser fractions. Halloysite or halloysite-kaolinite clusters in coarse fractions are the fragmentation products of the walls of original boxwork clusters in coarse fractions are the fragmentation products of the walls of original boxwork kaolin which escaped the complete dispersion even through the grinding, ultrasonic agitation, and chemical treatment. Separation of fully hydrated halloysite and kaolinite was possible by systematic wet size fractionation. The coarse-grained minerals such as vermiculite and kaolinite are usually removed during the preparation of clay fraction smaller than 2${\mu}m$, whereas the fine-grained minerals such as illite and goethite are overlooked in X-ray diffraction of the bulk samples because of their minor contents. The systematic wet size fractionation is needed for understanding of the exact mineralogy of kaolin of weathering origin.

• Journal of Internet Computing and Services
• /
• v.16 no.1
• /
• pp.39-46
• /
• 2015

This paper presents an automatic method to detect and count the cells from microorganism images based on mobile environments. Cell counting is an important process in the field of biological and pathological image analysis. In the past, cell counting is done manually, which is known as tedious and time consuming process. Moreover, the manual cell counting can lead inconsistent and imprecise results. Therefore, it is necessary to make an automatic method to detect and count cells from biological images to obtain accurate and consistent results. The proposed multi-step cell counting method automatically segments the cells from the image of cultivated microorganism and labels the cells by utilizing topological analysis of the segmented cells. To improve the accuracy of the cell counting, we adopt watershed algorithm in separating agglomerated cells from each other and morphological operation in enhancing the individual cell object from the image. The system is developed by considering the availability in mobile environments. Therefore, the cell images can be obtained by a mobile phone and the processed statistical data of microorganism can be delivered by mobile devices in ubiquitous smart space. From the experiments, by comparing the results between manual and the proposed automatic cell counting we can prove the efficiency of the developed system.

• Journal of Korea Soil Environment Society
• /
• v.5 no.2
• /
• pp.55-66
• /
• 2000

A U.S EPA Synthetic soil matrix was used for reference neat soil and pyrene contaminated soil. For the contaminated soil, 4.79 wt.% pyrene was dissolved completely into the djchlorornethane, and the soil was evenly soaked with the pyrene solution. The contaminated soil samples(50$\pm$0.5mg) were heated in a modified electrical screen heater reactor which consisted of a thin stainless foil (3.5cm$\times$13cm$\times$0.00254cm, 302 stainless steel shim), two electrodes, and a 20cm dia. $\times$30cm tall cylindrical Pyrex chamber sealed at both ends by aluminum flanges. The heating rate and time conditions were selected as $455^{\circ}C$ @ $1137^{\circ}C$ /s, $760^{\circ}C$ @ $950^{\circ}C$ /s and $977^{\circ}C$ @ $977^{\circ}C$/s. Tar samples after heating the soils were collected on the aluminum foil funnel and a glass filter paper (25mm dia. filter paper) The tar sample and remnant soil on the reactor were extracted with dichloromethane covering the filters, foils and soil by sonicating each in the waterbath for 10 minutes. The extractions were run on a HPLC. At the low peak temperature(about $455^{\circ}C$ @ $1137^{\circ}C$/s) the color of tar was "white", at the middle peak temperature (about 76$0^{\circ}C$ @ 95$0^{\circ}C$/s) the color of tar was "pink brown", at the high peak temperature (about 977$^{\circ}C$ @ 977$^{\circ}C$/s) the color of tar was "dark brown". Cyclopeta(cd)pyrene (CPEP) , which is an interesting species due to mutagenic effect on human cells, was detected in tar samples only above the middle peak temperature. This species was not detected at the low peak temperature. Six isomers of bipyrene were detected. Phenanthrene(C$_{14}$ $H_{10}$) and cyclopenta(def)phenanthrene(C$_{15}$ $H_{10}$) were also detected, but their content was very small relative to the other listed compounds.to the other listed compounds.