• Journal of radiological science and technology
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• v.26 no.1
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• pp.51-62
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• 2003

We carried out studies on develop of the ultrasound tissue mimicking materials(TMM) by synthesis of polymer urethane(C, CCR, $TiO_2$, tungsten, graphite, silver type). The major finding were as follows; (1) C type TMM was shown good homogeneity, penetration, gray scale like as liver tissue and propagated speed 1,540 m/s, attenuation $0.5{\sim}0.7\;dB/cm/MHz$. (2) $TiO_2$ type TMM was shown heterogeneous dot echo pattern. (3) Silver type TMM was appear good homogeneous echo pattern like as echo texture of thyroid gland. Therefor, C type TMM will be useful for ultrasound Q/A phantom materials and previous phantom materials.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.80-84
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• 1999

$Li_{4/3}Mn_{5/3}O_4$ having a defect structure was prepared by sol-gel process using lithium acetate and manganese acetate as starting materials, and their electrode characteristics in the lithium secondary battery was investigated. The reaction mole ratio was determined as $AA/Mn(OAc)_2$ of 0.2 and $NH_4OH/Mn(OAc)_2$ to $H_2O/Mn(OAc)_2$ of 0.4. The product was obtained through heat treatment at $350^{\circ}C$ for 12hrs after 1'st heat treatment at $150^{\circ}C$ of xerogel under oxygen atmosphere. When the charge and discharge cycles were performed between 2.0 V and 3.2 V, $Li/Li_{4/3}Mn_{5/3}O_4$ cell showed the dicharge capacity of 84.23 mAh/g and the good cycleability was obtained in the plateau region.

• Journal of Food Hygiene and Safety
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• v.33 no.1
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• pp.71-76
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• 2018

Norovirus is a leading cause of sporadic pathogenic non-bacterial gastroenteritis worldwide. For the detection of norovirus, reverse transcription real-time PCR (RT qPCR) has quickly become a major tool due to its sensitivity and specificity. However, accurate viral RNA extraction methods are essential for RT qPCR analysis. TRIzol reagents are used to extract RNA from biological materials and are therefore widely used for norovirus RNA extraction. In this study, the yield of viral RNA extraction using TRIzol from genogroup II (GII) among the human norovirus genogroup I (GI) and GII, and murine norovirus (GV) depended on the pH of the virus sample solution. The yield of RNA extraction was higher at the alkaline pH than in the acidic region compared with the Ct (threshold cycle) value of the real-time PCR. From the results of this study, it was found that the pH condition is very important for the quantitative analysis of norovirus by extracting GII RNA using TRIzol.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.7
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• pp.701-708
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• 2011

Natural convection heat transfers on inclined flat plates were measured for Grashof numbers of $8.06{\times}10^7$ and $3.45{\times}10^9$ by using a copper sulfate electroplating system. The inclinations of the plates were varied from upward-facing horizontal to downward-facing horizontal. Test results for the downward-facing plate agree well with the existing theory that the Nusselt number can be calculated by replacing gravitational acceleration, g with g $cos{\theta}$ in the heat transfer correlation for the vertical plate. The natural convection flows for the upward-facing plate follow two distinct flow regimes: boundary layer regime and flow separation regime. The copper plating pattern for the upward-facing plates clearly reveals the flow separation points.

• Environmental and Resource Economics Review
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• v.13 no.1
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• pp.1-32
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• 2004

Environmental Performance Index(EPI) has shown some limitation. Since it has lack of analysis for the relation between environmental performance and business performance, and public information. Therefore it could not provide valuable information for the shareholders to decide for the investment. In this paper by using Analystic Hierarchy Process (AHP), EPI was calculated giving some weighted scale for each environmental items. Improvement of pollution treatment, general management data such as EMS system, and environmental improvement for the products and process were the main three items when decision makers in bankings are considering the investment for a company. In empirical case, companies which has Environmental-Friendly Coorperation Award from MOE and ISO 14001 certification had shown strong relation between business performance and environmental performance.

• Proceedings of the Materials Research Society of Korea Conference
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• 2011.05a
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• pp.62.2-62.2
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• 2011

산업화 이후, 석탄 석유를 중심으로 한 화석연료가 이산화탄소를 대량으로 배출하며 지구 온난화를 야기함에 따라, 기존의 화석연료를 대체할 청정하고 무한 재생 가능한 대체에너지로 가장 큰 기대를 받고 있는 것은 태양에너지이며, 이에 보조를 맞춰 태양광발전에 대한 연구개발이 국내외적으로 활발히 진행되고 있는 실정이다. 태양 전지는 빛 에너지를 직접 전기 에너지로 바꿔주는 소자로, 셀의 효율을 높이기 위해서는 최대한 많은 빛을 흡수시킬 수 있는 것이 중요하다. 빛의 반사를 줄이는 방법에는 texturing과 antireflecting coating이 있다. Antireflecting coating은 반도체와 공기의 중간 굴절율을 갖는 박막을 증착하여 측면 반사를 감소시킴으로서 빛의 손실을 감소시키는 역할을 한다. 과거에 반사방지막으로 가장 많이 사용되었던 물질은 SiO로써 굴절률은 1.8~1.9로서 최소의 반사율은 1% 미만이지만, 가시광선영역에서의 흡수에 의한 손실이 생기므로, SiNx가 대체 물질로 제안되었다. SiNx의 경우 굴절률이 약 1.5로서 Si에 쉽게 형성시킬 수 있고, texturing된 Si 표면에 적합하며 반사율을 10%에서 2%로 줄일 수 있는 장점을 가지고 있다. 따라서 본 연구에서는 high power, high frequency PECVD 방법으로 $SiH_4$와 $NH_3$ gas의 비율, $N_2$ carrier gas 등 공정 변수를 변화시켜 증착한 SiNx 박막의 결정학적 특성을 X-ray diffraction 분석과 XPS (X-ray photoelectron spectroscopy)를 통해 화학적 결합을 확인하였고, 이를 FT-IR (Fourier Transform-Infrared spectroscopy)를 통해 관찰한 결과와 연관시켜 분석하였다. 굴절율의 경우 ellipsometer를 이용하여 측정하였으며 위의 측정을 통하여 SiNx박막의 반사 방지막으로써의 가능성을 확인 하였다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.28 no.1
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• pp.42-48
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• 2017

Characteristics of ground-penetrating radar(GPR) signals for detecting buried pipes are investigated numerically. Transmitting and receiving parts of a GPR system, a subsurface soil and a plastic pipe filled with a dielectric material are modeled by using the finite-difference time-domain(FDTD) method. FDTD simulations for observing aspects of GPR signals are performed as a function of the diameter of the pipe and the permittivity of the filling material in the pipe. GPR signals scattered by a dielectric filled pipe appear as a superposition of two waves, such as the specular wave from the front convex surface of the pipe and the axial wave from the rear concave surface of the pipe. We show that the amplitude, the polarity, the delay time of two waves depend on the size of the pipe and the permittivity of the filling material in the pipe.

• Journal of The Korean Association For Science Education
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• v.20 no.2
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• pp.262-273
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• 2000

The purpose of this study was to develop a tool for K-12 science curriculum articulation analysis, especially the concept map of 'properties of matter' and the table of the key concepts of 'properties of matter' by grade. We have 5 steps for the purpose; to extract common subject of K-12 science curriculums, to analyze the contents of K-12 science curriculum related to the common subject, to develop and analyze concept maps of K-12 science curriculums, to develop common concept map and the table of key concepts by grade of K-12 science curriculum, and to modify and clear up the concept map and the table. First two steps are related to the develop of 'water' concept map, and the others are related to the 'properties of matter' concept map.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.7
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• pp.737-744
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• 2012

A mobile emission laboratory (MEL) was designed to measure the amount of traffic pollutants, with high temporal and spatial resolution under real conditions. Equipment for the gas-phase measurements of CO, NOx, $CO_2$, and THC and for the measurement of the number, concentration, and size distribution of fine and ultra-fine particles by an FMPS and CPC was placed in a minivan. The exhausts of different types of vehicles can be sampled by an MEL. This paper describes the technical details of the MEL and presents data from the experiment in which a car chases passenger vehicles fuelled by diesel and gasoline. The particle number concentration in the exhaust of the diesel vehicle was higher than that of the gasoline vehicle. However, the diesel vehicle with a DPF emitted fewer particles than the vehicle equipped with a gasoline direct injection engine, with particle diameters over 50 nm.

• Korean Journal of Optics and Photonics
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• v.14 no.1
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• pp.1-7
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• 2003

We determined the optical constants of organic light emitting material of Alq$_3$ in a spectral range between 1.5 and 6 eV using the physical model introduced by Forouhi and Bloomer［Phys. Rev. B 34, pp. 7018-7026, 1986.］. The initial parameters of $A_i,\;B_i,\;C_i$ of Forouhi-Bloomer dispersion relations were determined from the absorption peaks and widths of absorption spectra of the Alq$_3$ film. The refractive index of substrate, a fused silica, is derived from the Sellmeier equation with the measured transmittance and reflectance spectra. Then, the complex refractive index and thickness of the Alq$_3$ film were calculated by use of a nonlinear least square fitting program with the Forouhi-Bloomer dispersion relation and the measured transmittance and reflectance spectra.