• Journal of Chest Surgery
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• v.32 no.10
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• pp.874-882
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• 1999

배경: 체외순환 후의 부종현상 및 이에 따른 여러 장치의 기능 저하를 방지하기 위하여, 최근에 체외 순환 이탈 후 환자의 혈액을 짧은 시간에 관류하여 여과해 주는 변형 초여과법의 사용이 늘고 있다. 이에 대한 긍정적인 임상결과들의 보고도 있으나, 다른 한편 체외 순환 후 염증반응을 포함한 폐손상의 기전에 혈구 성분의 영향이 보고되고 있는 바, 변형 초여과법의 효과, 특히 폐 조직에 대한 영향을 밝혀 보고자 하였다. 대상 및 방법: 몸무게 15에서 22 Kg(평균 16.5$\pm$0.5)의 16 쌍의 잡견을 이용한 정소성 심장이식, 실험에서, 통상적인 인공심폐기 작동군과 인공심폐기 작동 후 변형 초여과 관류를 시행한 군으로 무작위 구분하였다. 변형초여과법은 체외순환 정지 후에 대동맥관에서 나온 혈류를 Roller pump를 거쳐 Amicon Diafilter 초여과 관에 150 mL/m 정도의 속도로 10~15 분 정도 관류시켜 정맥관을 통하여 우심방에 직접 주입하였다. 혈액 채취 및 폐생검은 심폐기 시작 전과 정지 직후, 그리고 변형초여과 시행 군은 초여과 완료 직후에, 대조군은 심폐기 정지 10~15분 후에 각각 시행하였다. 혈류역학 측정요소는 동맥압, 우심방압, 좌심방압 등이었으며, 혈액 검사 항목은 동맥혈 가스분석, 혈색소 농도, 헤마토크릿, 백혈구 수, 혈소판 수, 혈중 단백 성분, 알부민 성분 등이었다. 폐 생검 조직으로는 냉동 건조법을 이용한 수분 함유량을 측정하였고, 광학 및 전자현미경으로 관찰을 하였다. 결과: 변형 초여과 군에서 혈중 혈색소 농도는 수술전 10.3$\pm$1.7 mg/dL, 심폐기 정지 직후 6.3$\pm$1.7 mg/dL, 초여과 직후는 8.3$\pm$2.8 mg/dL의 변화를(p=0.0078, 0.0117), 혈중 총 단백질의 농도 변화는 4.3$\pm$0.9, 3.1$\pm$1.5, 4.1$\pm$1.6 mg/dL, 혈중 알부민의 농도는 1.9$\pm$0.5, 1.4$\pm$0.7, 1.8$\pm$0.8 mg/dL로서, 각각 초여과법의 시행 전후에 유의한 증가를 가져왔고(p=0.0280, 0.0277), 폐조직의 수분 함유량의 변화는 수술전 75.1$\pm$8.6%, 심폐기 정지 직후 82.8$\pm$6.0%, 초여과 직후 77.88%를 보인 반면, 대조군에서는 각각 74.7$\pm$4.9, 82.1$\pm$5.9, 82.3$\pm$5.1%의 변화를 보였다. 미세 구조의 관찰에서, 폐포의 내포세피의 융합 기저막층과 미토콘드리아에서의 부종은 변형 초여과 후에 급격히 감소하였으나, 미토콘드리아내 크리스티의 파괴성 변화와 막성 파괴 성향이 초여과 후에 심화되게 관찰되었고, 세포질 내 소체의 팽창과 공포화 현상도 심폐기 가동 후 발생하여 초여과 후에 더 심화되게 관찰되었다. 세포질 내 소체의 팽창과 공포화 현상도 심폐기 가동 후 발생하여 초여과 후에 더 심화되게 관찰되었다. 폐조직 내의 백혈구는 심폐기 작동 후에 그 수에 있어서 증가하였으며 백혈구의 괴변, 탈과립 정도도 심폐기 작동 후 및 초여과 후에 증가한 소견을 보였다. 결론: 변형 초여과법은 인공 심폐기 후의 혈색소 농도 및 혈중 단백질 농도의 복원에 효과가 있었으며 변형 초여과 관류후 폐의 미세 조직내에서 부종의 급격한 감소 등을 관찰할 수 있었다.

• Journal of the Korea Concrete Institute
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• v.22 no.2
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• pp.219-228
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• 2010

It has been well known that concrete structures exposed to acid and sulfate environments such as sewer, sewage and wastewater, soil, groundwater, and seawater etc. show significant decrease in their durability due to chemical attack. Such deleterious acid and sulfate attacks lead to expansion and cracking in concrete, and thus, eventually result in damage to concrete matrix by forming expansive hydration products due to the reaction between portland cement hydration products and acid and sulfate ions. Objectives of this experimental research are to investigate the effect of mineral admixtures on the resistance to acid and sulfate attack in concrete and to suggest high-resistance concrete mix against acid and sulfate attack. For this purpose, concretes specimens with three types of cement (ordinary portland cement (OPC), binary blended cement (BBC), and ternary blended cement (TBC) composed of different types and proportions of admixtures) were prepared at water-biner ratios of 32% and 43%. The concrete specimens were immersed in fresh water, 5% sulfuric acid, 10% sodium sulfate, and 10% magnesium sulfate solutions for 28, 56, 91, 182, and 365 days, respectively. To evaluate the resistance to acid and sulfate for concrete specimens, visual appearance changes were observed and compressive strength ratios and mass change ratios were measured. It was observed from the test results that the resistance against sulfuric acid and sodium sulfate solutions of the concretes containing mineral admixtures were much better than that of OPC concrete, but in the case of magnesium sulfate solution the concretes containing mineral admixtures was less resistant than OPC concrete due to formation of magnesium silicate hydrate (M-S-H) which is non-cementitious.

• Journal of the Korean Geosynthetics Society
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• v.12 no.2
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• pp.13-23
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• 2013

The Korean Peninsula is considered as a seasonal frozen area that is thawed in the spring and frozen in the winter. The influence of fines of the frost susceptibility of subgrade soils were established by laboratory freezing tests simulating closely the thermal conditions in the field. During the winter season, the climate is heavily influenced by the cold and dry continental high pressure. Because of siberian air mass, the temperature of January is $-6{\sim}-7^{\circ}C$ on average. This chilly weather generate the frost heaving by freezing the moisture of soil and damage potential of the geotechnical structure. In the freezing soil, the ice lenses increase the freeze portion of soil by absorbing the ground water with capillary action. However, the capillary characteristics differ from the sort of soil on the state of freezing condition. In this study, ten soil samples are prepared. The basic physical property tests were performed by following the Korean Industrial Standard and the soil specimens were classified by the Unified Soil Classification System (USCS). These classified soils are used to perform the laboratory opened systems freezing test in order to determine the frost heaving characteristics of soils such as unfrozen water content, heaving amount, and freezing depth.

• Journal of the Korean Chemical Society
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• v.37 no.3
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• pp.302-308
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• 1993

Monolayers of calcium palmitate were deposited on a piezoelectric quartz crystal plate by the Langmuir-Blodgett(LB) technique, and it was found from frequency changes of the quartz crystal deposited LB films. The usual carbonyl absorbance at 1704 cm$^{-1}C$ was replaced by the split band in the 1540~1590 cm$^{-1}C$. The two absorptions at 1580 cm$^{-1}C$ and 1540 cm$^{-1}C$ were assigned to the antisymmetric stretching vibration of the calcium carboxylate group and the hydrated species due to the lowering carbonyl stretching frequency by hydrogen bonding$^1$ respectively. Besides, it was demonstrated by X-ray diffraction analysis. The swelling behaviour of LB films in water phase at 23$^{\circ}C$ was observed from the frequency change of the LB films deposited quartz crystal with time. Calcium palmitate LB films has been found to swell substantially in water without flaking, whereas hexadecanol LB films hardly swelled in water. Amount of swelling of calcium palmitate LB films was equivalent to 47 wt.${\%}$ of the dry LB films, which means that ca. 7 water molecules were incorporated per calcium palmitate amphiphile. Chemical structure of calcium palmitate LB film was estimated as [CH$_3$(CH$_2$)$_{14}$COO]$_2$Ca${\cdot}$XH$_2$O, and the hydration number was 1.

• Journal of the Mineralogical Society of Korea
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• v.19 no.1 s.47
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• pp.31-38
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• 2006

Site environments bring about various different deterioration forms of stone cultural properties. The aim of this study is to document the influence of coarse grained sandy soil on the deterioration of stone cultural properties. Bulguksadabotap is a good example that demonstrates the problem with coarse grained sandy soil. The ground around the Bulguksadabotap is covered with coarse grained sandy soil and the pagoda is surrounded by the corridors. Coarse grained sandy soil float easily in the air and deposit in the complicated stone structure caused by strong wind in Gyeongju and numerous visitors. To explain the influence of coarse grained sandy soil on the deterioration, the coarse grained sandy soil and weathered stone pieces of Bulguksadabotap were analyzed by XRD, optical microscopy, SEM for mineralogical component and IC and ICP-AES for the soluble salts. The soil and weathered stone pieces include clay minerals, such as smectite and kaolinite, can expand with water and exert pressure on the stone. Small size of the clay minerals in the coarse grained sandy soil can easily penetrate into the weathered surfaces of the Bulguksadabotap. The weathered stone pieces also contain NaCl, which is known to contribute to increase the expandibility of clay minerals by providing with $Na^{+}$ or by dropping the equilibrium of relative humidity. These results indicates that coarse grained sandy soil is not proper to site environment for weathered stone cultural properties.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.394-400
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• 2023

In this study, the tuning phenomena, gas storage capacity, and thermal expansion behaviors of binary (cyclopentylamine + CH₄) and (cyclopropylamine + CH₄) clathrate hydrates were investigated for the potential applications of clathrate hydrates to gas storage. To understand the tuning behaviors of binary (cyclopentylamine + CH₄) and (cyclopropylamine + CH₄) clathrate hydrates, ¹³C solid-state NMR spectroscopy was used, and the results confirmed that maximum tuning factors for the binary (cyclopentylamine + CH₄) and (cyclopropylamine + CH₄) clathrate hydrates were achieved at 0.5 mol% and 1.0 mol% of guest concentration, respectively. The gas storage capacity of binary (cyclopentylamine + CH₄) and (cyclopropylamine + CH₄) clathrate hydrates were also checked, and the results showed the CH₄ capacity of our hydrate systems was superior to that of binary (tetrahydrofuran + CH₄) and (cyclopentane + CH₄) clathrate hydrates. The synchrotron diffraction patterns of these hydrates collected at 100, 150, 200, and 250 K confirmed the formation of a cubic Fd-3m hydrate. In addition, the lattice constant of clathrate hydrates with cyclopentylamine and methane were larger than that with cyclopropylamine and methane due to the effects of molecular size and shape.

• Journal of the Korea institute for structural maintenance and inspection
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• v.23 no.7
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• pp.9-15
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• 2019

The purpose of present study is to assess the maximum width of the surface cracks using the histogram analysis of image processing techniques in concrete structures. For this purpose, the concrete crack image is acquired by the camera. The image is Grayscale coded and Binary coded. After Binary coded image is Dilate and Erode coded, the image is then recognized as separated objects by applying Labeling techniques. Over time, dust and stains may occur naturally on the surface of concrete. The crack image of concrete may include shadows and reflections by lighting depending on a surrounding conditions. In general, concrete cracks occur in a continuous pattern and noise of image appears in the form of shot noises. Bilateral Blurring and Adaptive Threshold apply to the Grayscale image to eliminate these effects. The remaining noises are removed by the object area ratio to the Labeled area. The maximum numbers of pixels and its positions in the crack objects without noises are calculated in x-direction and y-direction by Histogram analysis. The widths of the crack are estimated by trigonometric ratio at the positions of the pixels maximum numbers for the Labeled objects. Finally, the maximum crack width estimated by the proposed method is compared to the crack width measured with the crack gauge. The proposed method by the present study may increase the reliability for the estimation of maximum crack width using image processing techniques in concrete surface images.

• Applied Chemistry for Engineering
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• v.10 no.7
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• pp.990-995
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• 1999

To determine the effect of chemical structure of linear amine curing agents on thermal and mechanical properties, standard epoxy resin DGEBA was cured with ethylene diamine(EDA) and hexamethylene diamine(HMDA) in a stoichiometrically equivalent ratio. From this work, the effect of linear amine curing agents on the thermal and mechanical properties is significantly influenced by the chemical structure or chain length of curing agents. In contrast, the results show that the DGEBA/EDA system having the two carbons had higher values in the thermal stability, maximum conversion of epoxide, density, glass transition temperature, tensile modulus, flexural strength, and flexural modulus than the DGEBA/HMDA system having the six carbons, whereas the DGEBA/EDA cure system had relatively low values in the shrinkage(%), thermal expansion coefficient, tensile strength, and had similar values in the maximum exothermic temperature, and conversion of epoxide compared to the DGEBA/HMDA cure system. This findings indicate that packing ability in the HMDA structure affects the thermal and mechanical properties.

• Spatial Information Research
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• v.19 no.3
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• pp.63-72
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• 2011

Urban space structure tends to have a significant change in accordance with maintenance of urban infrastructure such as a traffic route. For this reason, quantitative analysis has been needed to establish spatial distribution and location patterns by considering change of both road accessibility and urban infrastructure level, which can have the most pervasive influence in urban development process. Therefore, this paper aims to analyze spatio-temporal urban morphology through considering distribution patterns of road among transportation infrastructures, population, and spatial structure of metropolitan areas, focusing on Seoul where population growth and the size of urban area have been dramatically increased. For this, we firstly developed and constructed time-series GIS database by using satellite images and topographic maps of the last 70 years to analyze variables which affect urban growth and transportation. In particular, we analyzed the transform of the system of the street by Space Syntax which is able to grasp hierarchical spatial structure through visibility of space and spatial cognition in terms of accessibility. What's more, we analyzed and visualized the relationship urban morphology and road according the regions of Seoul through IPA(Importance Performance Analysis). In terms of the integration land-use and transportation, Space Syntax approach is expected to contribute to efficient urban planning through understanding the influence which various transportation phenomena has an effect on urban development patterns.

• Journal of the Korean Geotechnical Society
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• v.27 no.12
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• pp.17-25
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• 2011

A fabric of soil media may change due to certain factors such as dissolution of soluble particles, desiccation, and cementation. The fabric changes affect the mechanical behavior of soils. The purpose of this study is to investigate the effects of geo-material dissolution on shear strength. Experiments and numerical simulations are carried out by using a conventional direct shear and the discrete element method. The dissolution specimens are prepared with different volumetric salt fraction in sand soils. The dissolution of the specimens is implemented by saturating the salt-sand mixtures at different confining stresses in the experimental study or reducing the sizes of soluble particles in the numerical simulations. Experimental results show that the angle of shearing resistance decreases with the increase in the soluble particle content and the shearing behavior changes from dilative to contractive behavior. The numerical simulations exhibit that macro-behavior matches well with the experimental results. From the microscopic point of view, the particle dissolution produces a new fabric with the increase of local void, the reduction of contact number, the increase of shear contact forces, and the anisotropy of contact force chains compared with the initial fabric. The shearing behavior of the mixture after the particle dissolution is attributed to the above micro-behavior changes. This study demonstrates that the reduction of shearing resistance of geo-material dissolution should be considered during the design and construction of the foundation and earth-structures.