• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.471.1-471.1
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• 2014

염료감응형 태양전지(DSSC)는 다양한 태양전지 중, 가장 환경친화적이고, 생산단가도 낮을 뿐만 아니라 다양한 색상과 투광성을 확보할 수 있어 많은 연구가 진행되어왔다. 하지만 액체전해질을 사용하는 기존 염료감응형 태양전지는 높은 휘발성과 열 팽창 수축에 따른 전해질 누액의 문제점으로 인하여 최근에는 고체전해질을 이용한 염료감응형 태양전지의 개발이 활발히 이루어지고 있다. 또한 기존 염료보다 높은 흡광계수와 넓은 흡수스펙트럼을 지닌 페로브스카이트가 개발되어 현재 많은 관심이 주목되고 있다. 본 연구에서는 $TiO_2$ 제조상의 중간생성물인 Metatitanic acid (MTA)를 이용하여 광전극을 형성하고 열처리 온도에 따른 나노입자의 소성거동평가을 평가하였고 시차열중량 분석, 결정상 확인을 하고 염료감응 태양전지에 적용하였다. MTA 나노입자를 Field Emission Transmission Electron Microscopy (FE-TEM), Barrett-Joyner-Halenda (BJH pore size distribution)과 Brunauer-Emmet-Teller (BET) 분석을 통해 소성거동을 평가하고, Thermogravimetry and differential thermal analysis (TG-DTA)를 통해 열중량 측정을 하였으며, X-ray Diffraction (XRD) 분석을 통해 결정상을 확인하였다. 또한 Fourier-transform infrared (FT-IR) spectroscopy를 통해 MTA 나노입자의 표면분석을 하였다. 형성된 MTA 광전극을 페로브스카이트 염료에 적용하여 5%의 효율을 달성하였다.

• Proceedings of the Materials Research Society of Korea Conference
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• 2010.05a
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• pp.42.2-42.2
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• 2010

Recently, highly porous bone substitutes, which have interconnected open pore structure, have been focused on improving their mechanical properties and modifying their functions. Especially, it is highly required to develop functional gradient structured bone substitute which is available for controlling their material properties such as bioresorption rate and elastic modulus. Porous $ZrO_2$ scaffold was fabricated by the sponge replica method using PU sponge. After 3 times of dip coating and the subsequent oven drying, burning out and microwave sintering were carried out. Various $ZrO_2$-BCP powder mixtures were prepared depending on the ratio and coated on the $ZrO_2$ scaffold by dip coating process. X-ray diffraction analysis was performed to characterize the phase identification of the scaffolds. Microstructures of the bone substitutes were observed using scanning electron microscopy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.1078-1080
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• 2002

The pressure variation of interstitial fluid is one of the most important factors in bone physiology. In order to understand the role of interstitial fluid and the biomechanical interactions between fluid and solid constituents within bone, poroelastic theory was applied. The purpose of this study is to describe the behavior of calf vertebral trabecular bone composed of the porous solid trabeculae and the viscous bone marrow by using a commercial finite element analysis program based on the poroelasticity. In this study, the model was numerically tested for 5 different strain rates, i. e., 0.001, 0.01, 0.1, 1.0, and 10 per second. The material properties of the calf vertebral trabecular bone were utilized from the previous experimental study. Two asymptotic poroelastic response, the drained and undrained deformation, were predicted. From the predicted results for the simulated five strain rate, it was found that the pore pressure generation has a linearly increasing behavior when the strain rate is the highest at 10 per second, other wise it showed a nonlinear the strain rate Increased. Based on the results of the present study, it was suggested that the calf vertebral trabecular bone could be modeled as a porous material and its strain rate dependent material behavior could be predicted.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.34 no.3
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• pp.25-31
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• 2002

The purpose of this study was to analyze how the fiber properties and mixing ratio of softwood and hardwood pulp affect on roundness of printed image. Softwood pulp and hardwood pulp were refined to 400 and 600ml CSF by Valley beater and handsheets of 70 g/$m^2$ basis weight were made at different mixing ratios of hardwood and softwood pulp. The roundness, dot area, and shape of the printed dot were measured by Image Analyzer. The depths and shapes of the acridine orange penetration into paper were measured by CLSM. With higher mixing ratio of hardwood pulp, the paper showed higher air-permeability and better formation, especially at lower freeness. The roundness of the printed image became better and the dot size became smaller when the amount of hardwood pulp increased. Penetration depth of acridine orange by CLSM became greater and roundness increased to real circle when the amount of hardwood pulp increased. It was thought that higher mixing ratio of hardwood fibers resulted in efficient penetration by better formation with uniform micro-pore distribution and it increased roundness. It was thought that fiber properties and mixing ratio affected the structure of paper and the shape of the printed dot. This study showed that the measurement of depth of the liquid penetration into paper without destruction and contact was feasible. Moreover, this method showed that the shape of the liquid penetration was measurable.

• 한국신재생에너지학회:학술대회논문집
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• 2008.10a
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• pp.186-187
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• 2008

Electrical resistivity in hydrate-bearing sediments is sensitive to porosity, gas hydrate saturation, gas content, pore fluid composition, and temperature, so electrical measurements such as well logs and electromagnetic surveys have been used to explore gas hydrate-bearing formation. The high pressure tomography cell is designed considering the effect of electrode configuration and electrical shielding on tomography measurements and the safety. The evolution of electrical conductivity during $CO_2$ hydrate formation and dissociation reflects the combined effects of concurrent changes that include ionization of dissolved $CO_2$, temperature-dependent ionic mobility, changes in the degree of saturation, ion exclusion, surface conduction, and porosity changes. Measurements during hydrate formation and dissociation require careful analysis to properly interpret signatures, in particular when out-of plane conductivity anomalies prevail.

• Analytical Science and Technology
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• v.18 no.4
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• pp.355-361
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• 2005

The objective of this paper is to compare the surface features of two kinds of activated caron fiber (ACF) treated with potassium and the variation of their properties by phosphoric acid pre-treatment. X-ray diffraction (XRD) patterns indicate that activated carbon fiber containing potassium species show better performance for metal and metal salts by pre-treatment with phosphoric acid. In order to present the causes of the differences in surface properties and specific surface area after the samples were treated with phosphoric acid, pore structure and surface morphology were investigated by adsorption analysis and SEM. For the chemical composition microanalysis for potassium leading of the activated carbon fibers pre-treated with phosphoric acid, samples were analyzed by EDX. Finally, the type and quality of oxygen groups were determined from the method proposed by Boehm.

• The Journal of Engineering Geology
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• v.11 no.3
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• pp.295-301
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• 2001

Geological and geophysical surveys were performed to examined the cause of the rock-mass slide occurred at the opening site of the Wanglim tunnel of the Seoul-Pusan High Speed Railway. The results of geophygical survey and geometrical analysis for the geological structures indicate that the rock-mass slide was triggered by the heavy rainfall which increases the groundwater level and results in high pore pressure in the N60$^{\circ}$ E-trending major fractured zone of the slope, and that the foliation dipping toward the vertical open face of the slope acted as a main sliding plane during movement.

• Food Science and Biotechnology
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• v.18 no.2
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• pp.330-335
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• 2009

The principal objective of this study was to investigate changes in ice dendrite size during the freezing of tuna, in order to formulate a mathematical model of ice dendrite size. The tuna was frozen via a uni-directional heat transfer. Thermogram analysis allowed us to determine the position of the freezing front versus time, which is referred to as the freezing front rate. The morphology of the ice dendrites was assessed via scanning electron microscopy after freeze-drying, and the retained pore size was measured as ice dendrites. We noted that the mean size of ice dendrites increased with the distance to the cooling plate; however, it decreased with reductions in the cooling rate and the cooling temperature. In addition, shorter durations of the freeze-drying process decreased the freezing front rate, resulting in a larger size of the ice dendrite pores that operate as water vapor sublimation channels. According to our results, we could derive a linear regression as an empirical mathematical model equation between the ice dendrite size and the inverse of the freezing front rate.

• Journal of Life Science
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• v.14 no.2
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• pp.301-308
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• 2004

The morphology of the apical pore complex, the first apical plate and the posterior sulcal plates in a new isolate of Alexandrium tamarense (Lebour) Balech from the Bay of Chinhae was compared with other that of toxic strains of A. tamarense previously isolated from Korean waters. Although this isolate was morphologically identical to these toxic strains, high performance liquid chromatography and mouse bioassay showed no evidence of toxin production. The nontoxic A. tamarense strain showed a strong positive binding activity with PNA lectin, indicating a high density of lactose and galactose residues on the cell surface, and in SDS-PAGE and Western blot analysis a unique protein of about 21-kDa molecular sizes was observed. These findings demonstrate that the use of PNA and immunobioassay could be used to discriminate between toxic and nontoxic strains of A. tamarense.

• Journal of the Korean Geotechnical Society
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• v.21 no.10
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• pp.27-39
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• 2005

A finite difference program with 3-D governing equation expanded from 1-D self-weight consolidation is developed to analyze the consolidation behavior of surface dredged soil with horizontal drains. Various boundary conditions with horizontal drains and seepage pressure of pore water infiltrated to the drains are considered in the program. A laboratory soil chamber experiment for the consolidation of dredged soil is performed to validate the program and the measured settlement-time result is compared with the one predicted by the program. The influence of design conditions of horizontal drains such as horizontal installation spacing, installation depth and number of drain layers, on the consolidation is analyzed.