• Carbon letters
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• 제16권1호
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• pp.57-61
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• 2015

Carbon aerogel is a porous carbon material possessing high porosity and high specific surface area. Nitrogen doping reduced the specific surface area and micropores, but it furnished basic sites to improve the $CO_2$ selectivity. In this work, N-doped carbon aerogels were prepared with different ratios of resorcinol/melamine by using the sol-gel method. The morphological properties were characterized by scanning electron microscopy (SEM). Nitrogen content was studied by X-ray photoelectron spectroscopy (XPS) and the specific surface area and micropore volume were analyzed by $N_2$ adsorption-desorption isotherms at 77 K. The $CO_2$ adsorption capacity was investigated by $CO_2$ adsorption-desorption isotherms at 298 K and 1 bar. Melamine containing N-doped CAs showed a high nitrogen content (5.54 wt.%). The prepared N-doped CAs exhibited a high $CO_2$ capture capacity of 118.77 mg/g (at resorcinol/melamine = 1:0.3). Therefore, we confirmed that the $CO_2$ adsorption capacity was strongly affected by the nitrogen moieties.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2002년도 가을 학술발표회 논문집
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• pp.382-389
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• 2002

Recently, auger-drilled piling has been widely used in urban area to reduce the air pollution and noise. But this construction method that its basic theory was introduced from Japan may be changed depending on the each piling company and construction field condition. Therefore, the design code and management method for auger-drilled piling is not defined yet. Especially, the lack of research on the bearing capacity of auger-drilled piling leads to the absence of rational bearing capacity prediction equation. This paper presents the optimum design code and economical construction method of the auger-drilled piling by proposing the new bearing capacity prediction equation based on the site specific soil types and construction conditions. In this paper, existing bearing capacity prediction equations and current pile load tests were compared. And the end bearing capacity and skin friction characteristics were also analyzed by comparing the results of CAPWAP. From the results of analysis, a reliable bearing capacity prediction equation considered soil types is proposed.

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1507-1510
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• 2011

In this study, mercury vapor adsorption behaviors for some kinds of porous materials having various pore structures were investigated. The specific surface area and pore structures were studied by BET and D-R plot methods from $N_2$/77 K adsorption isotherms. It was found that the micropore materials (activated carbons, ACs) showed the highest mercury adsorption capacity. In a comparative study of mesoporous materials (SBA-15 and MCM-41), the adsorption capacity of the SBA-15 was higher than that of MCM-41. From the pore structure analysis, it was found that SBA-15 has a higher micropore fraction compared to MCM-41. This result indicates that the mercury vapor adsorptions can be determined by two factors. The first factor is the specific surface area of the adsorbent, and the second is the micropore fraction when the specific surface areas of the adsorbent are similar.

• 대한기계학회논문집
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• 제18권8호
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• pp.2123-2138
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• 1994

A study on the dynamic mechanical properties of the high strength carbon fiber epoxy composite beam was carried out. The macromechanical model was used for the theoretical analysis of the symmetric laminated composite beam. The anisotropic plate theory and Bernoulli-Euler beam theory were used to predict the effective flexural elastic modulus and the specific damping capacity of laminated composite beam. The free flexural vibration and torsional vibration tests were carried out to determine the specific damping capacities of the unidirectional laminated composite beam. The vibration tests were performed in a vacuum chamber with laser vibrometer system and electromagnetic hammer to obtain accurate experimental data. From the computational and experimental results, it was found that the theoretical values with the macromechanical analysis and the experimental data of symmetric laminated composite beam were in good agreement.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2003년도 춘계 학술발표회논문집
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• pp.275-285
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• 2003

Pinching is an important property of reinforced concrete member which characterizes its cyclic behavior. In the present study, numerical studies were performed to investigate the characteristics and mechanisms of pinching behavior and the energy dissipation capacity of flexure-dominated reinforced concrete members. By analyzing existing experimental studies and numerical results, it was found that energy dissipation capacity of a member is directly related to energy dissipated by re-bars rather than concrete that is a brittle material, and that it is not related to magnitude of axial compressive force applied to the member. Therefore, for a member with specific arrangement and amount of re-bars, the energy dissipation capacity remains uniform regardless of the flexural strength that is changed by the magnitude of axial force applied. Due to the uniformness of energy dissipation capacity pinching appears in axial compression member. The flexural pinching that is not related to shear force becomes conspicuous as the flexural strength increases relatively to the uniform energy dissipation capacity. Based on the findings, a practical method for estimating energy dissipation capacity and damping modification factor was developed and verified with existing experiments.

• Bulletin of the Korean Chemical Society
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• 제31권5호
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• pp.1267-1269
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• 2010

The pure crystalline $Li_{1.1}V_{0.9}O_2$ powder has been prepared by a simple solid state reaction of $Li_2CO_3$ and $V_2O_3$ precursors under nitrogen gas containing 10 mol % hydrogen gas flow. The structure of $Li_{1.1}V_{0.9}O_2$ powder was analyzed using Xray diffraction (XRD) and scanning electron microscope (SEM). The stoichiometric $Li_{1.1}V_{0.9}O_2$ powder was used as anode active material for lithium secondary batteries. Its electrochemical properties were investigated by cyclic voltammetry and constant current methods using lithium foil electrode. The observed specific discharge capacity and charge capacity were 360 mAh/g and 260 mAh/g during the first cycle, respectively. In addition, the cyclic efficiency of this cell was 72.2% in the first cycle. The specific capacity of $Li_{1.1}V_{0.9}O_2$ anode rapidly declines as the current rate increases and retains only 30 % of the capacity of 0.1C rate at 1C rate. The crystallinity of the $Li_{1.1}V_{0.9}O_2$ anode decrease as discharge reaction proceeds. However, the relative intensity of main peaks was almost recovered when the cell was charged up to 1.5 V.

• 한국세라믹학회지
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• 제21권1호
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• pp.41-50
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• 1984

The ion-exchange porous glasses were prepared by heat treating and subsequently acid treating the (95-y) $SiO_2$.$yB_2O_3$.$5Na_2O+xAl_2O_3$ glasses with y=55, 45, 35, 25. mole% and x=0, 2, 5, 9 mole% It was then investigated how the cation exchange capacity was affected by the phase separation in these glasses. For that matter such quantities as alkali extraction amount pore volume and specific surface area of the glasses were measured. The phase separation in these glasses was in general suppressed by the addition of $Al_2O_3$ maximally around the composition of 5 mole% $Al_2O_3$ This may be because the micro-phase separation prevailed in the glass of that composition over the macro-phase separation increasing thereby the specific surface area as well as the residual amount Al of after acid-treatment and accordingly the cation exchange capacity. The maximum values of the cation exchange capacity was observed to be about 150meq/100g for the glasses of (40-50) $SiO_2$ (55~45)$yB_2O_3$. $5Na_2O+5Al_2O_3$.

• Journal of Contemporary Eastern Asia
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• 제10권1호
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• pp.15-23
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• 2011

This study focuses on the knowledge-transfer activities of Korean universities at the organisational level. Considering the idiosyncratic characteristics of the Korean university system, as well as those of universities in other recently developed Asian countries experienced a rapid economic catch-up, this study is more interested in the relationship between the scientific capacity of universities and their knowledge-transfer activities, and between universities' funding sources and their knowledge-transfer activities. According to the results of the study, scientific capacity in a specific discipline, such as engineering, is important for universities in both other developed countries and in Korea, while scientific capacity (regardless of the discipline) is apparently not important for Korean universities, particularly in the area of domestic publication. Furthermore, this result supports the proposition suggested that strategically chosen industrial sectors in rapid catch-up countries are closely related to the scientific capacity of universities in specific disciplines. In terms of funding sources, the amount of funding from industry is strongly related to the knowledge-transfer activities of universities, whereas the proportion of funding from industry relative to the total amount of funding is not as significantly related to knowledge-transfer activities. The failure to identify a significant relationship between central government funding and knowledge-transfer activities may be due to less strict requirements for commercialisation in central government R&D programmes. Otherwise, central government funding fails to generate meaningful knowledge-transfer activities in universities.

• 한국지반공학회논문집
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• 제32권5호
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• pp.49-55
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• 2016

본 연구는 도심지의 도로 환경을 고려하여, 기능성 포장 재료 중 하나인 이산화티타늄($TiO_2$)을 포함한 시멘트 모르타르의 실질적인 일산화질소(NO) 제거 성능을 평가하고자 하였다. 실험은 크게 두 가지로, 유입되는 기체의 습도에 따른 NO 제거율 변화 실험과 시편의 포화도에 따른 NO 제거율 변화 실험으로 구성되었다. 습도 변화 실험에서는 건조 상태의 시편을 대상으로 유입 기체의 습도를 변화시키며 NO 제거율을 관찰하였다. 습도-NO 제거율 곡선은 로그 정규 분포 형상으로, 특정 습도에서 최대 NO 제거율이 나타났다. 포화도 변화 실험은 강우 및 생활 하수로 인하여 불포화 상태인 도로를 반영하고자 습윤 상태인 시편을 대상으로 하였다. 습윤 상태의 시편은 건조 상태보다 낮은 NO 제거 성능을 보였으며 증발이 진행되면서 $TiO_2$가 노출되어 NO 제거 성능이 증가하였다. 그리고 시편의 특정 깊이 아래에 존재하는 $TiO_2$는 NO 제거 성능에 크게 기여하지 않는 것으로 나타났다.

• STI Policy Review
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• 제1권2호
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• pp.1-18
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• 2010

The development and maintenance of human capacity in economies is critical to long term competitiveness, but also for the overall health and environment of regions. Yet, human science and technology-based capacity is multidimensional and has interrelated characteristics which present certain policy challenges. This paper addresses a range of issues specific to a discussion on human capacity in S&T. First, the paper emphasizes the importance of acknowledging the complexity of human capacity issues and how they evolve along the STEM (science, technology, engineering, and mathematics) pipeline. The pipeline is an often used reference to describe the training and development in STEM disciplines, from early childhood education, to more advanced training, and finally to professional collaboration and interaction and serves as a useful organizing framework for the discussion of capacity along the career evolution process. Second, the paper offers an organizing framework for discussion of policy mechanisms that have been developed to address issues and gaps that occur along this STEM pipeline. Specifically, it contrasts the traditional mechanisms of building human capacity in STEM areas with newer "gap filling" and integrated approached to addressed human capacity disparities and priorities. Third, the paper addresses core challenges in human capacity in STEM, including the education and training, participation of women and underrepresented groups, brain drain/brain circulation issues, and the globalization of science. The paper concludes with a discussion of policy implication for the development of human capacity.