가스상 대기오염물질에 의한 종이 기록물의 가속열화 특성 연구

정소윤(So-Yoon Jeong),전수연(Soo-Yeon Jeon),백소라(So-Ra Baek),정현석(Hyun-Seok Jeong),이진희(Jin-Hee Lee),김형진(Hyoung-Jin Kim) 한국펄프·종이공학회 2015 펄프.종이기술 Vol.47 No.4

Paper records were generally degraded by some factors from atmospheric environments, like temperature, relative humidity or air pollutants. In this study, the degradation behavior of paper records by single or mixed gases of NO₂, SO₂, HCHO and TVOC was evaluated. The mechanical, optical and chemical properties of 4 kinds of paper (acid and neutral-based printing paper, traditional Hanji, and filter paper) were directly and indirectly affected by gaseous harmful materials. The brightness and L<SUP>*</SUP> value in all papers were slightly increased by accelerated aging under gaseous HCHO and TVOCs, but highly decreased by conditions under gases NO₂ and SO₂. The optical properties of paper records were most vulnerable in acid-based paper and high stable in filter paper and traditional Hanji by air pollutant degradation. The aging treatments under mixed gas pollutants including NO₂ resulted in decrease of physical, mechanical and optical properties of paper, so it was supposed that the concentration of NO₂ gas would be strictly controlled for optimum indoor air quality management in domestic storage centers for paper records.

Assessment of Corrosion Rate of Reinforcing Steel in Concrete Using Galvanostatic Pulse Transient Technique

So, Hyoung-Seok,Millard, Stephen Geoffrey Korea Concrete Institute 2007 International Journal of Concrete Structures and M Vol.1 No.1

This paper discusses a method of measuring transient potential response of a corrosion interface to a small galvanostatic pulse perturbation for a rapid assessment of the corrosion rate of reinforcing steel in concrete structures. Measurements were taken on 100 mm sections of steel bars which were subjected to a wide range of corrosion conditions, from passive steel to actively corroding steel. The duration of the applied galvanostatic pulse was varied between 5s and 180s, and the lateral distance of the point of measurement on the steel bar varied from zero to 400 mm. The result of the electrochemical transient response was investigated using a typical sampling rate of 1 kHz. Analysis of the transient potential response to the applied galvanostatic pulse has enabled the separation of equivalent electronic components so that the components of a series of capacitances and resistances, whose values are dependent on the corrosion condition of the reinforcing steel, could be isolated. The corrosion rate was calculated from a summation of the separate resistive components, which were associated with the corrosion interface, and was compared with the corrosion rate obtained from linear polarization resistance (LPR) method. The results show that the galvanostatic pulse transient technique enables the components of the polarization resistance to be evaluated separately so as to give more reliable corrosion rate values than those obtained from the LPR method. Additionally, this paper shows how the galvanostatic pulse transient response technique can be implemented. An appropriate measurement time for passive and actively corroding reinforcing steel is suggested for the galvanostatic pulse transient response measurements in the field site.

Mechanical properties and microstructure of reactive powder concrete using ternary pozzolanic materials at elevated temperature

So, Hyoung-seok,Jang, Hong-seok,Khulgadai, Janchivdorj,So, Seung-young Springer-Verlag 2015 KSCE JOURNAL OF CIVIL ENGINEERING Vol.19 No.4

Strength and Microstructure of Reactive Powder Concrete Using Ternary Pozzolanic Materials

So, Hyoung-Seok,Janchivdorj, Khulgadai,Yi, Je-Bang,Jang, Hong-Seok,So, Seung-Young The Korean Institute of Building Construction 2013 한국건축시공학회지 Vol.13 No.1

To consider the practicality and economic feasibility of developing reactive powder concrete (RPC), the strength and microstructure properties of RPC using ternary pozzolanic materials (silica fume, blast furnace slag, fly ash) were investigated in this study. Through the investigation, it was found that the compressive strength of RPC using ternary pozzolanic materials was increased significantly compared to that of the original RPC containing silica fume only. A considerable improvement in the flexural strength of RPC using ternary pozzolanic materials was found, and then the utilization of a structural member subjected to bending was expected. The X-ray diffractometer (XRD) analysis and Scanning Electronic Microscope (SEM) revealed that the microstructure of RPC was denser using the ternary pozzolanic materials than the original RPC.

Assessment of Corrosion Rate of Reinforcing Steel in Concrete Using Galvanostatic Pulse Transient Technique

Hyoung-Seok So,Stephen Geoffrey Millard 한국콘크리트학회 2007 International Journal of Concrete Structures and M Vol.1 No.1

메타카올린을 혼입한 RPC의 미세구조와 강도발현 특성

소승영(So, Seung-Young),이제방(Yi, Je-Bang),장칩도르지(Khulgadai, Janchivdorj),소형석(So, Hyoung-Seok) 대한건축학회 2011 大韓建築學會論文集 : 構造系 Vol.27 No.12

This paper reports development characteristics of strength and microstructure of RPC (reactive powder concrete) containing meta-kaolin, in order to use meta-kaolin as the substitutive material of silica fume, which is so expensive in Korea. Various RPC containing meta-kaolin were made by replacement ratio of meta-kaolin and different curing conditions, and their mechanical properties, hydration products and pore structures were investigated. The result has shown possibility of meta-kaolin as a substitutive materials of silica fume in RPC. It was also shown use of meta-kaolin is invaluable for increase of strength at very early age (1 day), and expecially for the improvement of flexural strength than compressive strength. The effect of strength improvement in RPC containing meta-kaolin could be explained based on the analysis of hydration products and pore structure of them by XRD, SEM and MIP(mercury intrusion porosimetry) technique.

배합 및 양생조건이 폴리프로필렌섬유보강 초고강도 시멘트 복합체의 강도발현 특성에 미치는 영향

소형석(So Hyoung-Seok),진성훈(Jin Sung-Hoon) 대한건축학회 2010 大韓建築學會論文集 : 構造系 Vol.26 No.5

Fiber Reinforced Ultra-High Cementitious Composite (FR-UHCC) is an ultra high-strength and high ductility composite material which has shown some promises in the civil engineering community by its advanced mechanical properties. However, due to the use of very fine sand instead of ordinary aggregate, the cement factor of the FR-UHCC is as high as 900~1000 ㎏/㎥. And its density is as high as 3.0 g/㎤ by pressing fresh FR-UHCC samples in order to improve the strength. High density and high cement content may be a weakness for practicality and economic feasibility. This study is an elementary experiment to develop the FR-UHCC considered the practicality and economical efficiency, for that the various FR-UHCC was made using the constitute factors and curing conditions. And the influence of the parameters on the strength development of FR-UHCC was investigated. The result has shown that it is possible to produce ultra-high strength FR-UHCC with a density as low as 1.82 g/㎤ by the autoclave curing condition (160℃) and increasing of the silica fume/cement ratio (SF/C=80%). And an economical high strength FR-UHCC with the cement contents less than 600 ㎏/㎥ (which contains high-volume of the blast furnace slag) is produced in this study, and its compressive strength is 144 ㎫ and the density is 2.17 g/㎤.

철근콘크리트구조물에서 콘크리트의 전기저항 측정에 미치는 내부철근 및 환경변수의 영향

소형석(So Hyoung-Seok) 대한건축학회 2009 大韓建築學會論文集 : 構造系 Vol.25 No.6

The measurement of concrete resistivity, when used in conjunction with potential mapping, may be used to assess the probable location and severity of reinforcement corrosion problems in in-situ RC structures. However, the presence of the reinforcing steel may itself cause an error in the measurement of concrete resistivity by providing an electrical short circuit. In this paper, the rate of corrosion of steel embedded in concrete has been evaluated by the measurement of concrete resistivity using the Wenner technique (4-probe array system) and compared with the results measured by linear polarization resistance(LPR) method which has been developed to direct measure the corrosion rate of reinforcing steel in concrete. The influence of reinforcing steel on the measurement of concrete resistivity has been also investigated using steel reinforcement with a number of different diameters, cover depth of concrete and the presence of chloride ions in concrete, and observed the effect of environmental factors on the concrete resistivity measurements to assess externally exposed reinforced concrete. The results was shown that the measurement of concrete resistivity promises to be taken quickly, accurately and without causing damage to in-situ reinforced concrete structures, in the assessment of the presence and rate of corrosion of reinforcing steel in concrete. However, reading was influenced by the presence of reinforcing bars and its influence was increased with increasing of the diameter of steel bar and with decreasing of concrete cover depth and compressive strength of concrete. The measurement of concrete resistivity was significantly influenced by the ambient temperature and rainfall.

포졸란재 함유 콘크리트의 투수 및 투기성과 염화물이온 투과성

소형석(So Hyoung-Seok),소양섭(Soh Yang-Seob) 대한건축학회 2003 大韓建築學會論文集 : 構造系 Vol.19 No.11

This study was carried out to evaluate the influence of addition of a pozzolanic admixtures(fly ash and silica fume, a blast furnace slag) on the concrete permeability. The main experimental variables were the water-cementitious material ratios, the types and amount of admixtures, and the curing time. And tests have been carried out on concrete containing pozzolanic admixtures to measure their permeability coefficient using water and oxygen, chloride ion, and compressive strength, and the porosity and pore size distributions by mercury intrusion porosimetry(MIP). The results show that the concrete containing pozzolanic admixtures exhibited lower permeability coefficient than the plain concrete. The significant reduction in permeability(water and oxygen, chloride ion) of concrete with pozzolans due to formation of a discontinuous macro-pore system which inhibits flow. It is shown that there is higher relationship between permeability and parameters of pore structure(such as porosity and pore size distribution), and permeability and compressive strength, and water or oxygen permeability and chloride ion permeability(charge passed) based on electrical conductance.

철근콘크리트구조물에서 철근의 부식율 측정을 위한 직류 전기저항법의 이용에 관한 실험적 연구

소형석(So Hyoung-Seok) 대한건축학회 2008 大韓建築學會論文集 : 構造系 Vol.24 No.6

This paper discusses a new method for assessing the corrosion rate of reinforcing steel bars in concrete using the DC resistivity technique. Measurements were conducted on the reinforced concrete specimens which were made for this experiment with the different diameter of steel bars, the cover depth and compressive strength of concrete. The traditional Wenner technique (4-probe array system) was used for the concrete resistivity measurements. A DC resistivity measurement device was built for the experiment to apply the DC current perturbation. The true resistivity (pt) and apparent resistivity (Pa) were measured using the traditional Wenner technique, and DC resistivity (PDC-a) were also measured using the DC resistivity technique. Using these results, the corrosion rate of reinforcing steel was evaluated and compared with the results measured by the linear polarization resistance method which has been developed to direct measure the corrosion rate of reinforcing steel in concrete structure. As the results, it was shown that the corrosion rate of reinforcing steel can be evaluated quantitatively using the DC resistivity method and the corrosion rate results were similar to those measured using the linear polarization resistance method. However, it was also shown that the apparent resistivity (Pa) and DC resistivity (PDC-a) were strongly influenced by the cover depth of concrete, the quality of concrete and the diameter of steel bars. Therefore, the further investigations for the various parameters such as the temperature and moisture contents in concrete are needed to use the DC resistivity method for evaluating the corrosion rate of steel in concrete structures in the field.