• Journal of Environmental Science International
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• v.13 no.2
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• pp.175-180
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• 2004

A prompt gamma-ray neutron activation (PGNA) system was simulated by the Monte Carlo N-Particle transport code (MCNP-4A) to estimate the level at which the scattered photon fluence rate, the absolute efficiency of the HPGe-detector, the volume of the concrete sample and the $^{35}$ /Cl(n, ${\gamma}$) reaction rate in this sample contribute to the count rate in the NaCl concentration measurement. The n- ${\gamma}$ fluence rates at the ST-2 beam tube exit of the HANARO reactor were used as input data, and the GAMMA-X type HPGe detector was modeled to tally 1.1649 MeV ${\gamma}$ -rays emitted from the $^{35}$ Cl(n, ${\gamma}$) reaction in the concrete sample. For three cylindrical concrete samples of 13.8, 46.8 and 157.1 ㎤ volumes, respectively, the relations between the NaCl weight fractions of 0.1, 1, 2 and 5 % in each of the concrete samples and the 1.1 649 MeV pulses created in the HPGe detector model were studied. As a result, it was found that the count rate at the same NaCl concentration nearly depends on the volume of the samples in a simulated condition of the same NaCl concentration samples, and that the linearities of the NaCl concentration calibration curves were reasonable in the narrow range of the NaCl weight fraction.

• The Plant Pathology Journal
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• v.16 no.4
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• pp.216-221
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• 2000

Mixed infection of watermelon mosaic potyvirus II isolated from pumpkin (WMV-P) and cucumber green mottle mosaic tobamovirus from watermelon (CGMMV-W) caused extremely severe symptoms such as progressive silting and death of watermelon plants. Single infections of either WMV-P or CGMMV-W on the same hosts produced only vein clearing and/or mosaic on the upper leaves. In cells infected with WMV-P, potyvirus-characteristic inclusions of pinwheels, scrolls and cylindrical inclusions were present in the cytosol. Parallel arrays of virus particles in the tonoplast were also common. In cells infected with CGMMV-W, virus particles occurred as stacked-bands of scattered randomly in the cytosol and vacuoles in all type cells. Many cells also contained vesiculated mitochondria with fibril-containing vesicles. Cells infected mixedly with WMV-P and CGMMV-W contained structural features that were not observed in cells infected singly with the two viruses. A particle of WMV-P potyvirus was surrounded by evenly spaced nine particles of CGMMV-W tobamovirus, which made a unique nonagon ring. The angled layers having $60^{\circ}$-$135^{\circ}$ were alternating layer, herringbone, crosshatching and ladder figures.

• Transactions of the Korean Society of Automotive Engineers
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• v.9 no.6
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• pp.30-39
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• 2001

The direct injection into the cylinders has been regarded as a way of the reduction in fuel consumption and pollutant emissions. The spray produced by the high pressure injector is of paramount importance in DISI(Direct Injection Spark Ignition) engines in that the primary atomization process must meet the requirement of quick and complete evaporation, mixing with air and combustion especially to prohibit the excessive HC emissions. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of flow inside the cylinder of the DISI engine. The direct Mie scattered and shadowgraph images presented the macroscopic view of the liquid sprays and vapor fields. The velocity and particle size of fuel droplets were investigated by phase doppler anenometer(PDA) system. The processes of atomization and evaporation with a DISI injector were observed and consequently utilized to construct the data-base for the spray and fuel-air mixing mechanism as a function of the flow characteristics.

• Journal of ILASS-Korea
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• v.10 no.3
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• pp.38-44
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• 2005

The direct injection into the cylinders has been regarded as a way of the reduction in fuel consumption and pollutant emissions. The spray produced from the injector of DIS(Direct Injection Spark Ignition) engine is of paramount importance in DISI engines. Fan-spray injector as well as swirl-spray injector was developed and utilized to the DISI engines. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of flow inside the cylinder of the DISI engineer. The direct Mie scattered images presented the macroscopic view of the liquid spray fields interacted with crossflow. Particle sizes of fuel droplets were measured with phase Doppler anemometer(PDA) system. A faster cross-flow field made SMD larger and $D_{10}$ smaller. The experiments show the interaction of air flow field and the fuel spray field of fan-spray. The results can be utilized to construct the data-base for the spray and fuel-air mixing mechanism as a function of the flow characteristics.

• The Bulletin of The Korean Astronomical Society
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• v.39 no.1
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• pp.66.1-66.1
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• 2014

Radiative transfer programs to simulate the 3-micron auroral $CH_4$ emissions of Jupiter have been developed. The formalism of the radiative transfer calculations including the thermal, fluorescent, and auroral emissions of the $CH_4$ bands for an atmospheric layer having an optical depth of ${\tau}_v$ is given by: ${\mu}dI_v/d{\tau}_v=I_v-{\varpi}_v{^*}J_v(1-{\varpi}_v{^*})B_v-{\varpi}{^*}F_{ov}{e}{x}{p}(-{\tau}_v/{\mu}_o)4{\pi}-hv{\varpi}{^*}V/4{\pi}$ where ${\varpi}_v{^*}$ is the single scattering albedo of $CH_4$ consisting of Einstein A coefficient and collisional deexcitation rate. Other terms are usual radiative transfer parameters appearing in textbooks including the terms for scattered ${\varpi}_v{^*}J_v$, thermal $(1-{\varpi}_v{^*})B_v$, and attenuated solar radiations $F_{ov}$ at the certain atmospheric layer. For auroral excitations, we include V, which is the number of excited states per $cm^3$ persec by auroral particle bombardments. We apply this formalism to the high-resolution spectra of the auroral regions observed with GNIRS/Gemini North, and will present preliminary results for the 3 micron auroral processes of Jupiter.

• Journal of Korea Water Resources Association
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• v.38 no.10 s.159
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• pp.841-849
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• 2005

Two-phase flows, e.g. sediment-laden flow and bubbly flow, have two different flow profiles; flow velocity and sediment velocity. To measure velocity distributions of two-phase flows, it is necessary to use sophisticated instruments which can separate velocity profiles of two-phases. For bubbly flows, PIV (Particle Image Velocimetry) or PTV (Particle Tracking Velocimetry) has given fairly good velocity profiles of two-phases. However, for sediment-laden flows, the applications of PIV or PTV has not been so successful, because the sediment particles introduced to the flow kept the images from being analyzed. A new algorithm, which consists of several image analysis methods, is proposed to analyze sediment-laden flows. For detection algorithm, threshold method, edge detection method, and thinning method are adapted, and for finding matching pair PIV and PTV routines are combined. The proposed method can (1) detect sediment particles with irregular boundaries, (2) remove reflected images and scattered images, and (3) discriminate tracer particles from reflected images of sediment particles.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.109-110
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• 2014

주사전자현미경(Scanning Electron Microscopy: SEM)은 고체상태에서 미세조직과 형상을 관찰하는 데에 가장 다양하게 쓰이는 분석기기로서 최근에 판매되고 있는 고분해능 SEM은 수 나노미터의 분해능을 가지고 있다. 그리고 SEM의 초점심도가 크기 때문에 3차원적인 영상의 관찰이 용이해서 곡면 혹은 울퉁불퉁한 표면의 영상을 육안으로 관찰하는 것처럼 보여준다. 활용도도 매우 다양해서 금속파면, 광물과 화석, 반도체 소자와 회로망의 품질검사, 고분자 및 유기물, 생체시료 nnnnnnnnn와 유가공 제품 등 모든 산업영역에 걸쳐 있다(Fig. 1). 입사된 전자빔이 시료의 원자와 탄성, 비탄성 충돌을 할 때 2차 전자(secondary electron)외에 후방산란전자(back scattered electron), X선, 음극형광 등이 발생하게 되는 이것을 통하여 topography (시료의 표면 형상), morphology(시료의 구성입자의 형상), composition(시료의 구성원소), crystallography (시료의 원자배열상태)등의 정보를 얻을 수 있다. SEM은 2차 전자를 이용하여 시료의 표면형상을 측정하고 그 외에는 SEM을 플랫폼으로 하여 EDS (Energy Dispersive X-ray Spectroscopy), WDS (Wave Dispersive X-ray Spectroscope), EPMA (Electron Probe X-ray Micro Analyzer), FIB (Focus Ion Beam), EBIC (Electron Beam Induced Current), EBSD (Electron Backscatter Diffraction), PBMS (Particle Beam Mass Spectrometer) 등의 많은 분석장치들이 SEM에 부가적으로 장착되어 다양한 시료의 측정이 이루어진다. 이 중 결정구조, 조성분석을 쉽고 효과적으로 할 수 있게 하는 X선 분석장치인 EDS를 SEM에 일체화시킨 장비와 EDS 및 PBMS를 SEM에 장착하여 반도체 공정 중 발생하는 나노입자의 형상, 성분, 크기분포를 측정하는 PCDS(Particle Characteristic Diagnosis System)에 대해 소개하고자 한다. - EDS와 통합된 SEM 시스템 기본적으로 SEM과 EDS는 상호보완적인 기능을 통하여 매우 밀접하게 사용되고 있으나 제조사와 기술적 근간의 차이로 인해 전혀 다른 방식으로 운영되고 있다. 일반적으로 SEM과 EDS는 별개의 시스템으로 스캔회로와 이미지 프로세싱 회로가 개별적으로 구현되어 있지만 로렌츠힘에 의해 발생하는 전자빔의 왜곡을 보정을 위해 EDS 시스템은 SEM 시스템과 연동되어 운영될 수 밖에 없다. 따라서, 각각의 시스템에서는 필요하지만 전체 시스템에서 보면 중복된 기능을 가지는 전자회로들이 존재하게 되고 이로 인해 SEM과 EDS에서 보는 시료의 이미지의 차이로 인한 측정오차가 발생한다(Fig. 2). EDS와 통합된 SEM 시스템은 중복된 기능인 스캔을 담당하는 scanning generation circuit과 이미지 프로세싱을 담당하는 FPGA circuit 및 응용프로그램을 SEM의 회로와 프로그램을 사용하게 함으로 SEM과 EDS가 보는 시료의 이미지가 정확히 일치함으로 이미지 캘리브레이션이 필요없고 측정오차가 제거된 EDS 측정이 가능하다. - PCDS 공정 중 발생하는 입자는 반도체 생산 수율에 가장 큰 영향을 끼치는 원인으로 파악되고 있으며, 생산수율을 저하시키는 원인 중 70% 가량이 이와 관련된 것으로 알려져 있다. 현재 반도체 공정 중이나 반도체 공정 장비에서 발생하는 입자는 제어가 되고 있지 않은 실정이며 대부분의 반도체 공정은 저압환경에서 이루어지기에 이 때 발생하는 입자를 제어하기 위해서는 저압환경에서 측정할 수 있는 측정시스템이 필요하다. 최근 국내에서는 CVD (Chemical Vapor Deposition) 시스템 내 파이프내벽에서의 오염입자 침착은 심각한 문제점으로 인식되고 있다(Fig. 3). PCDS (Particle Characteristic Diagnosis System)는 오염입자의 형상을 측정할 수 있는 SEM, 오염입자의 성분을 측정할 수 있는 EDS, 저압환경에서 기체에 포함된 입자를 빔 형태로 집속, 가속, 포화상태에 이르게 대전시켜 오염입자의 크기분포를 측정할 수 있는 PBMS가 일체화 되어 반도체 공정 중 발생하는 나노입자 대해 실시간으로 대처와 조치가 가능하게 한다.

• Journal of Korean Society of Forest Science
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• v.76 no.1
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• pp.17-26
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• 1987

To develop the rehabilitation measures for rockily denuded forest lands which are widely distributed in Seoul metropolitan area, erosional characteristics of denudation should, first of all, be evaluated and analysed. As a fundamental study for developing such technical measures, the rockily denuded lands were classified into 6 types according to denudation features of the mountain land, and also movements of stone debris-and-sand on rock-exposed hillslopes were measured and analysed. The 6 basic types of denudation features include a) natural rock-outcrop-exposed land, b) stone debris-and-sand scattered land, c) stone debris-and-sand deposited land, d) coarse sand producing bare land susceptible to weathering and erosion, e) dwarfed pine growing land, and f) torrential valley susceptible to the debris slides. In the stone debris-and-sand scattered hillslopes (type b), average amount of moved-down debris reached to about 3.9 ton/ha/yr due to surface washing and slidings. In the particle size distribution of the moved-down debris, it amounts to about 25% of 10-25mm, about 15% of 5-10mm, about 24% of 2-5mm, and about 36% of less than 2mm in diameter class, respectively. The detailed experimental studies should be accomplished further more about the denudation processes including weathering, erosion and debris slides on rock-exposed hillslopes.

• Molecules and Cells
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• v.38 no.6
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• pp.573-579
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• 2015

Apolipoprotein A-I and A-IV are protein constituents of high-density lipoproteins although their functional difference in lipoprotein metabolism is still unclear. To compare anti-atherogenic properties between apoA-I and apoA-4, we characterized both proteins in lipid-free and lipidbound state. In lipid-free state, apoA4 showed two distinct bands, around 78 and $67{\AA}$ on native gel electrophoresis, while apoA-I showed scattered band pattern less than $71{\AA}$. In reconstituted HDL (rHDL) state, apoA-4 showed three major bands around $101{\AA}$ and $113{\AA}$, while apoA-I-rHDL showed almost single band around $98{\AA}$ size. Lipid-free apoA-I showed 2.9-fold higher phospholipid binding ability than apoA-4. In lipid-free state, $BS_3$-crosslinking revealed that apoA-4 showed less multimerization tendency upto dimer, while apoA-I showed pentamerization. In rHDL state (95:1), apoA-4 was existed as dimer as like as apoA-I. With higher phospholipid content (255:1), five apoA-I and three apoA-4 were required to the bigger rHDL formation. Regardless of particle size, apoA-I-rHDL showed superior LCAT activation ability than apoA-4-rHDL. Uptake of acetylated LDL was inhibited by apoA-I in both lipid-free and lipid-bound state, while apoA-4 inhibited it only lipid-free state. ApoA-4 showed less anti-atherogenic activity with more sensitivity to glycation. In conclusion, apoA-4 showed inferior physiological functions in lipid-bound state, compared with those of apoA-I, to induce more pro-atherosclerotic properties.

• Journal of Veterinary Clinics
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• v.18 no.1
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• pp.55-60
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• 2001

Immunohistochemical and Electron Microscopical Studies on the Initial Skin Lesions Induced Experimentally by Very Virulent Strain of Marek\`s Disease Virus in Chickens Marek\`s disease virus (MDV), which is an avian herpesvirus, causes malignant CD3+CD4+CD8-T cell lymphomas at many sites including visceral organs, muscles, peripheral nerves and skin. In the early skin lesions induced by MDV, corelationship between the translational activity of MDV early gene, pp38 and demonstration of MDV particles in the lymphoid cells are not well studied. Therefore, skin biopsies taken at weekly intervals for 2 weeks from the same specific-pathogen free chicknes inoculated with Md/5 MDV were examined immunohistochemically and electron microscopically. In the skin biopsies sampled at 1 week and 2 weeks post inoculation (PI), feather follicle epithelium (FFE) exhibited usually strong positive reaction for pp38, whereas only few lymphoblasts, which were infiltrated around FFE revealed positive reaction. Electron microscopically, small lymphocytes were detectable in the dermis and subcutaneous skin tissues sampled at 1 week PI. The number of small lymphocytes was increased and pleomorphic lymphoblasts, which were medium to large in size were scattered among the small lymphocytes at 2 weeks PI. Some of lymphoblasts revealed degenerative and necrotic changes. FFE contained a lot of MDV particles in the nucleus including mature and immature ones. Infrequently, immature virus particles were observed not only in the degenerative and necrotic lymphoblasts, but also rarely in the health lymphoblasts. From the present results, spontaneous MDV activation including translational activity of MDV pp38 gene and formation of MDV particles was occurred in the lymphoblasts of early MD skin lesions.