• 한국통신학회논문지
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• 제37권5A호
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• pp.375-387
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• 2012

본 연구에서는 움직이는 CCD 카메라로부터 입력된 영상에서 색상 및 질감 성분을 기반으로 하는 파티클 필터를 이용하여 실시간으로 객체를 추적할 수 있는 알고리즘을 제안한다. 초기 영상에서 추적하고자 하는 객체를 선택하면 이를 타깃 파티클로 결정하고, 타깃 파티클로 부터 추적을 위한 초기 상태가 모델링 된다. 이후 프레임부터 N개의 파티클들이 랜덤 분포로 생성되고 각 파티클로 부터 질감 정보인 로컬 CS-LBP (Centre Symmetric Local Binary Patterns)모델과 색상 분포 모델이 특징 모델로 사용된다. 각 특징 모델에 대해 바타차리야 (Bhattacharyya) 거리를 사용하여 각 파티클과 타깃 파티클 간의 특징 관측 우도(likelihood)를 구하고 이를 각 파티클의 가중치로 설정 한다. 각 파티클의 가중치를 기반으로 가중치가 가장 높은 파티클을 새로운 타깃으로 설정하고, 각 파티클들을 재 샘플링 한다. 본 실험결과에서는 여러 가지 특징을 조합하여 실험을 하였고, 그 결과 색상 분포 모델과 로컬 CS-LBP를 조합했을 때 추적 성능이 가장 우수한 것을 확인할 수 있었다.

• 한국산학기술학회논문지
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• 제17권9호
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• pp.641-646
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• 2016

화석 연료의 연소 과정에서 발생하는 그을음 입자의 형상은 작은 구형입자들이 군집체를 이루고 있는 프랙탈 형상을 하고 있기에 기존 Rayleigh나 Mie 탄성 광 산란 이론으로 분석하는 것에는 한계가 있다. 본 논문에서는 Rayleigh-Debye Gans(RDG) 산란 이론을 적용하여 프랙탈 차원을 가지는 미세 입자의 형상을 효과적으로 해석할 수 있는 과정을 자세히 묘사하였다. 이소옥탄 확산 화염에서 발생하는 그을음 입자를 열 영동 채취법을 이용하여 채집한 후, 투과전자현미경을 이용하여 그을음 입자의 형상을 관찰하였다. RDG 산란 이론을 적용하여, 그을음 입자의 프랙탈 형상을 조사 하였고, 그을음 개별 입자의 직경, 입자 수밀도 및 부피 분율을 산출하였다. 이러한 결과들은 그을음의 성장 과정에서는 뚜렷한 증감 경향을 보이진 않았으나, 그을음 산화 과정에선 전부 뚜렷하게 감소하는 경향을 보였다. 본 연구에서 RDG 산란 이론을 이용하여 도출한 그을음 군칩체의 프랙탈 차원은 약 1.82로 이는 기존의 유사연구 결과와 동일하며, 화석연료의 종류에 상관없이 생성된 모든 그을음 입자에 동일한 값을 갖는 것으로 사료된다.

• Journal of Radiation Protection and Research
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• 제49권1호
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• pp.50-64
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• 2024

Background: The reference dose coefficients (DCs) of the International Commission on Radiological Protection (ICRP) have been widely used to estimate organ doses of individuals for risk assessments. This approach has been well accepted because individual anatomy data are usually unavailable, although dosimetric uncertainty exists due to the anatomical difference between the reference phantoms and the individuals. We attempted to quantify the individual variation of organ doses for photon external exposures by calculating and comparing organ DCs for 30 individuals against the ICRP reference DCs. Materials and Methods: We acquired computed tomography images from 30 patients in which eight organs (brain, breasts, liver, lungs, skeleton, skin, stomach, and urinary bladder) were segmented using the ImageJ software to create voxel phantoms. The phantoms were implemented into the Monte Carlo N-Particle 6 (MCNP6) code and then irradiated by broad parallel photon beams (10 keV to 10 MeV) at four directions (antero-posterior, postero-anterior, left-lateral, right-lateral) to calculate organ DCs. Results and Discussion: There was significant variation in organ doses due to the difference in anatomy among the individuals, especially in the kilovoltage region (e.g., <100 keV). For example, the red bone marrow doses at 0.01 MeV varied from 3 to 7 orders of the magnitude depending on the irradiation geometry. In contrast, in the megavoltage region (1-10 MeV), the individual variation of the organ doses was found to be negligibly small (differences <10%). It was also interesting to observe that the organ doses of the ICRP reference phantoms showed good agreement with the mean values of the organ doses among the patients in many cases. Conclusion: The results of this study would be informative to improve insights in individual-specific dosimetry. It should be extended to further studies in terms of many different aspects (e.g., other particles such as neutrons, other exposures such as internal exposures, and a larger number of individuals/patients) in the future.

• 한국콘텐츠학회논문지
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• 제17권8호
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• pp.579-585
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• 2017

비다공성 표면에 유류된 지문을 현출하기 위해서는 다양한 기법을 사용할 수 있는데, 분말법은 실무에서 주로 사용되고 있는 기법 중 하나이다. 하지만 분말의 종류가 다양해짐에 따라 각각의 분말마다 권장되는 붓질(stroke) 횟수가 정해져 있지 않아 숙련된 과학수사요원이 잠재지문의 현출정도를 파악하면서 붓질을 해야 하며 현출한 결과물 또한 개개인마다 다르다. 지문 분말은 원료배합과 제조방법에 따라 분말 입자간 서로 붙는 성질이 다양하게 나타나는데 이러한 성질을 자착성(auto-adhesion)이라고 한다. 본 연구에서는 다양한 종류의 지문 분말의 자착 정도를 알아보기 위하여 슬라이드 글라스에 지문을 유류한 후 분말을 각각 1회, 3회, 5회, 10회 적용하여 현출된 지문을 광학현미경으로 배율을 달리하여 관찰하는 실험을 진행하였다. 일부 분말은 붓질 횟수가 증가함에 따라 지문 융선이 더 진하게 현출되는 결과를 보였고 반대로 일부 분말은 약한 자착성으로 인해 붓질의 횟수가 증가함에 따라 지문이 흐려지는 결과를 나타냈다. 각 분말들이 갖는 자착성의 다양함은 분말마다 브러쉬의 사용방법이 달라져야 한다는 사실을 시사하고 있다.

• 한국양식학회지
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• 제13권3호
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• pp.223-230
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• 2000

사육수에 광물미립자를 현탁시켜 노폐물을 흡착, 분해시킨 후 이를 분리, 배출시킴으로서 사육수를 정화시켜 재 사용할 수 있다는 가설 하에 사육수조와 포말분리장치로만 구성된 사육수 재사용 시스템에서 광물미립자를 현탁시켜 넙치를 실험사육 하였다. 두 종류의 가공황토 (processed residual reddish soil, 50 $\mu$ 이하)와 돌로마이트 (dolomite, 50 ${\mu}$이하) 미립자를 사육수에 현탁시키고 포말분리장치로 이를 분리, 배출시킴으로서 사육수를 정화하였다. 직경 4.8 m의 원형사육수조(사육수량 10 $m^2$), 사육수 순환을 시간당 2회전, 재사용을 90%, 수온 17${\pm}$1$^{\circ}C$에서 평균체중 23.1 g의 넙치 치어(5,555마리, 총중량 128 kg)를 75일간 사육하여 평균체중84.6 g (5,532마리, 총중량 468 kg)으로 육성하였다. 최종수용밀도는 26.0 kg/$m^2$였다. 실험기간 동안 어병은 관찰되지 않았다. 사육수에 광물입자를 현탁시켜 사육수 중의 노폐물을 흡착, 분해시킨 후 포말분리장치로 이를 배출시킴으로서 사육수를 정화하여 재사용하는 방법은 새로운 사육수 재사용 어류양식시스템으로서 가능성이 있다.

• Journal of Photoscience
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• 제10권2호
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• pp.199-202
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• 2003

The relationship between the morphology of nanostructured TiO$_2$ films and the photo-injected electron transport has been investigated using intensity-modulated photocurrent spectroscopy (IMPS). For this purpose, three different TiO$_2$ films with 5 ${\mu}{\textrm}{m}$ thickness are prepared: The rutile TiO$_2$ film with 500 nm-sized cluster-like spherical bundles composed of the individual needles (Tl), the rutile TiO$_2$ film made up of non-oriented, homogeneously distributed rod-shaped particles having a dimension of approximately 20${\times}$80 nm (T2), and the anatase TiO$_2$ film with 20 nm-sized spherically shaped particles (T3). Cross sectional scanning electron micrographs show that all of the TiO$_2$films have a quite different particle packing density: poorly packed Tl film, loosely packed T2 film and densely packed T3 film. The electron transport is found to be significantly influenced by film morphology. The effective electron diffusion coefficient D$_{eff}$ derived from the IMPS time constant is an order of magnitude lower for T2 than for T3, but the D$_{eff}$ for the Tl sample is much lower than T2. These differences in the rate of electron transport are ascribed to differences in the extent of interparticle connectivity associated with the particle packing density.ity.

• 천문학회지
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• 제47권3호
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• pp.87-98
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• 2014

We develop a parallel cosmological hydrodynamic simulation code designed for the study of formation and evolution of cosmological structures. The gravitational force is calculated using the TreePM method and the hydrodynamics is implemented based on the smoothed particle hydrodynamics. The initial displacement and velocity of simulation particles are calculated according to second-order Lagrangian perturbation theory using the power spectra of dark matter and baryonic matter. The initial background temperature is given by Recfast and the temperature uctuations at the initial particle position are assigned according to the adiabatic model. We use a time-limiter scheme over the individual time steps to capture shock-fronts and to ease the time-step tension between the shock and preshock particles. We also include the astrophysical gas processes of radiative heating/cooling, star formation, metal enrichment, and supernova feedback. We test the code in several standard cases such as one-dimensional Riemann problems, Kelvin-Helmholtz, and Sedov blast wave instability. Star formation on the galactic disk is investigated to check whether the Schmidt-Kennicutt relation is properly recovered. We also study global star formation history at different simulation resolutions and compare them with observations.

• Advances in nano research
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• 제2권2호
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• pp.77-88
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• 2014

Solvothermal treatment of late transition metal acetylacetonates in a novel medium composed either of pure acetophenone or acetophenone mixtures with amino alcohols offers a general approach to uniform hydrophilic metal nanoparticles with high crystallinity and low degree of aggregation. Both pure metal and mixed-metal particles can be accesses by this approach. The produced materials have been characterized by SEM-EDS, TEM, FTIR in the solid state and by Nanoparticle Tracking Analysis in solutions. The chemical mechanisms of the reactions producing nanoparticles has been followed by NMR. Carrying out the process in pure acetophenone produces palladium metal, copper metal with minor impurity of $Cu_2O$, and NiO. The synthesis starting from the mixtures of Pd and Ni acetylacetonates with up to 20 mol% of Pd, renders in minor yield the palladium-based metal alloy along with nickel oxide as the major phase. Even the synthesis starting from a mixed solution of $Cu(acac)_2$ and $Ni(acac)_2$ produces oxides as major products. The situation is improved when aminoalcohols such as 2-aminoethanol or 2-dimethylamino propanol are added to the synthesis medium. The particles in this case contain metallic elements and pairs of individual metals (not metal alloys) when produced from mixed precursor solutions in this case.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.581-584
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• 2008

A generation of a particle beam is the key technique in a flow cytometry that measures the fluorescence and light scattering of individual cell and other particulate or molecular analytes in biomedical research. Recent methods performing this function require a laborious and time-consuming assembly. In the present work, we propose a novel device for the generation of an axisymmetrical focusing beam of microparticles (3-D focusing) in a single capillary without sheath flows. This work uses the concept that the particles migrate toward the centerline of the channel when they lag behind the parabolic velocity profile. Particle focusing of spherical particles was successfully made with a beam diameter of about 10 ${\mu}$m. Proposed device provides crucial solutions for simple and innovative 3-D particle focusing method for the applications to the MEMS-based micro-flow cytometry. We believe that this device can be utilized in a wide variety of applications, such as biomedical/ biochemical engineering.

• Journal of the Korean Wood Science and Technology
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• 제25권1호
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• pp.37-41
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• 1997

Hot-water soluble extracts were prepared from medium-sized barks of Siberian larch (Larix gmelineii). The extracts were fractionated by ultrafiltration method for producing uniform quality of adhesives. Molecular weight distribution of the extracts was ranged of 100 to 300.000. pH of the extracts affected amounts of flux, and the range of pH 6~pH 8 was proper for wood adhesives, because of easy concentration and fast gelation time. Removal of particles greater than $0.45{\mu}m$ from the extracts increased both filtration speed (flux) and yields of solids in the filtrates. In ultrafiltration process. operating pressure, filtrate temperature, and flow rate significantly increased with the increase of individual condition. Ultrafiltration using PM10 membrane was very effective to fractionate and concentrate the extracts. Removal of large particles greater than 0.45 m from the extracts increased filtration speed(flux) and yields of solids in the filtrates. A gelation time was accelerated with the increasing pH of the extracts and its concentration. The Stiasny precipitate(26%) from the filtrate obtained by PM 10 membrane was very lower than that(78%) of the retentates. This ultrafiltration method was efficient for obtaining high yield purified phenolic compounds.