PURPOSES : In this study, experimental findings regarding the frost resistance of concrete incorporated with mineral admixtures such as fly ash (FA) and ground granulated blast-furnace slag (SG) are presented. METHODS : To evaluate the performance of the abovementioned concretes under repeated freezing and thawing environments, based on the ASTM C 666 standard, the relative dynamic modulus of elasticity and mass ratio measurements are performed regularly. Furthermore, based on the ASTM C 672 standard, the concretes are exposed to 4% CaCl2 and NaCl salt solutions along with repeated 50 cycles of freezing and thawing. Subsequently, the scaling resistance is evaluated based on the scaled-off mass content and visual examination. RESULTS : SG is less effective in enhancing the scaling resistance of concrete compared with FA. However, the concrete incorporated with SG is more resistant to repeated freeze-thaw actions compared with OPC concrete. Meanwhile, compared with OPC concrete, the concrete incorporated with FA indicates a similar performance in terms of scaling resistance and better resistance against repeated freeze-thaw actions. CONCLUSIONS : The frost resistance of concrete depends significantly on the types of mineral admixtures used in concrete. This emphasizes the importance of selecting the appropriate binder to achieve durable concrete pavements in cold climate regions.

PURPOSES : In this experimental study, the resistance of blended cement concrete containing air-cooled slag (AS) and water-cooled slag (WS) to freeze–thaw action was investigated. For comparison, the durable performance of ordinary Portland cement (OPC) concrete exposed to a similar damage environment was also evaluated. METHODS : Based on the ASTM C 666 standard, the relative dynamic modulus of elasticity, mass ratio, surface electric resistivity, and compressive strength of blended cement concrete specimens were periodically measured and compared with those of OPC concrete to evaluate the durability of concrete exposed to the freezing-thawing environment. In addition, microstructural characteristics of deteriorated concrete parts were evaluated using scanning electron microscopy (SEM) and energy dispersive spectroscopy techniques to detect products formed by freeze–thaw action. RESULTS : It was found that the resistance of blended cement concrete containing AS and WS to freeze–thaw action was significantly better than that of OPC concrete. Furthermore, the SEM results revealed the frost damage of OPC concrete, owing to the formation of thaumasite. CONCLUSIONS : The application of AS in concrete can effectively improve the durability of concrete, particularly in freeze–thaw environments.

PURPOSES : This paper presents the experimental results of tests conducted on concrete produced with air-cooled (AS) and water-cooled (WS) ground blast-furnace slag exposed to multi-deterioration environments of carbonation and scaling. METHODS : Carbonated and uncarbonated concrete specimens were regularly monitored according to the ASTM C 672 standard to evaluate the durability of concrete exposed to both scaling and combined carbonation and scaling conditions. Additionally, mechanical properties, such as compressive strength, flexural strength, and surface electric resistivity, were analyzed. RESULTS : It was found that concrete specimens produced with AS and WS had a beneficial effect on the mechanical properties because of the latent hydraulic properties of the AS and WS mineral admixtures. Moreover, carbonated concrete showed good scaling resistance in comparison to uncarbonated concrete, particularly for concrete produced with AS and WS. CONCLUSIONS : The improved scaling resistance of carbonated concrete showed that AS is a suitable option for binders used in cement concrete pavements subjected to combined carbonation and scaling.

PURPOSES : Durability of concrete is traditionally based on evaluating the effect of a single deterioration mechanism such as freezing & thawing action, chloride attack, carbonation and chemical attack. In reality, however, concrete structures are subjected to varying environmental exposure conditions which often results in multi-deterioration mechanism occurring. This study presents the experimental results on the durability of concrete incorporating air-cooled slag(AS) and/or water-cooled slag(WS) exposed to multi-deterioration environments of chloride attack and freezing & thawing action. METHODS: In order to evaluate durable performance of concretes exposed to single- and multi-deterioration, relative dynamic modulus of elasticity, mass ratio and compressive strength measurements were performed. RESULTS: It was observed that multi-deterioration severely affected durability of concrete compared with single deterioration irrespective of concrete types. Additionally, the replacement of cement by AS and WS showed a beneficial effect on enhancement of concrete durability. CONCLUSIONS : It is concluded that resistance to single- and/or multi-deterioration of concrete is highly dependent on the types of binder used in the concrete. Showing the a good resistance to multi-deterioration with concrete incorporating AS, it is also concluded that the AS possibly is an option for concrete materials, especially under severe environments.

PURPOSES: The scaling of a concrete surface caused by the combined effects of frost and de-icing salts is one of the main reasons for the need to repair transportation infrastructures in cold-climate regions. This study describes the results of attempts to determine the scaling resistance of concrete incorporating mineral admixtures such as fly ash, GGBFS, and silica fume, and subjected to the actions of frost and salt. METHODS : Conventionally, to evaluate the fundamental properties of concrete, flexural and compressive strength measurements are regularly performed. Based on the ASTM C 672 standard, concrete is subjected to 2%, 4%, and 8% CaCl2 salt solutions along with repeated sets of 50 freeze/thaw cycles,and the scaling resistance was evaluated based on the mass of the scale and a visual examination. RESULTS : It was observed that silica fume is very effective in enhancing the scaling resistance of concrete. Meanwhile, concrete incorporating GGBFS exhibited poor resistance to scaling, especially in the first ten freeze/thaw cycles. However, fly ash concrete generally exhibited the maximum amount of damage as a result of the frost-salt attack, regardless of the concentrations of the solutions. CONCLUSIONS: It can be concluded that the scaling resistance of concrete is highly dependent on the type of the mineral admixture used in the concrete. Therefore, to provide a durable concrete pavement for use in cold-climate regions, the selection of a suitable binder is essential.

1990년대 후반부터 미국과 유럽의 기업들은 지속적 경쟁우위를 위해 ‘기업시민행동’을 중요하게 여겨오고 있다. ‘기업시민행동’에 대한 해외의 선행 연구들은, 기업시민행동이 기업성과뿐만 아니라, 사회적으로도 긍정적인 영향을 미침으로써 기업이익과 사회이익을 모두 생산해 내는 역할을 하고 있다고 주장한다. 이러한 국제적 흐름에서, 국내 기업들도 기업시민행동을 중요한 개념으로 인식하기 시작했으며, 구체적인 제도를 통해 실행하고 있다. 하지만 그 수준들이 미국과 유럽에 비하면 아직은 초기 단계이며, 기업시민행동의 정확한 개념 정립과 그를 바탕으로 한 실증 분석이 부족하다. 그러므로 국내 기업들이 실행하는 기업시민행동이 조직구성원이나 성과에 긍정적인 영향을 미치고 있는지 확인할 필요가 있다. 또, 국내기업들의 기업시민행동이 어떤 경로를 통해 최종적인 기업성과와 연결되는지 확인하는 것도 중요하다.본 연구에서는 선행연구를 바탕으로 기업시민행동의 개념을 명확히 하고자 했으며, 인적자원성과와 주관적 재무성과, 일인당 매출액을 각각 매개변수와 종속변수로 선정하여 횡단적 회귀분석을 실시하였고,이를 통해서 기업시민행동이 기업성과에 미치는 영향을 실증적으로 검증하였다. 실증분석 결과 기업시민행동은 인적자원성과, 주관적 재무성과, 일인당 매출액에 긍정적인 영향을 미치는 것으로 나타났으며, 인적자원성과는 기업시민행동과 주관적 재무성과의 관계를 완전매개 하는 것으로 확인됐다. 그리고 기업시민행동과 일인당 매출액의 관계에서는 인적자원성과의 매개 역할을 확인할 수 없었고, 기업시민행동의 직접효과만을 확인할 수 있었다. 즉, 국내의 기업이 추구하는 기업시민행동이 인적자원성과와 기업성과를 향상시키는 것을 확인한 것이다. 그리고 인적자원성과의 매개 역할을 부분적으로 확인함으로써, 기업시민행동과 기업성과의 연결고리 일부를 밝혔다.

나노입자의 응용은 1970년대부터 발전되어 왔다. 금속 나노입자에 빛을 조사하면 나노입자 표면에서 플라즈몬 공명(SPR, surface plasmon resonance)을 일으킨다. SPR 효과는 금속표면에 입사한 빛에너지에 의해 전자가 여기하며 공명을 일으켜 진동을 발생시키는 현상을 말한다. 여기 된 전자들이 금속원자들과 충돌을 일으키며 열에너지로 전환될 수 있는데 이를 금속의 광열효과(photothermal effect)라고 한다. 우리는 광열 효과를 이용하여 온열 화장품의 개발 가능성을 제시하고자 한다. 온열 화장품의 개발을 위해 생체 독성이 적은 금 나노입자를 선택하여 광열 효과에 있어서의 세포 생체적합성과 열효율을 살펴보았다. 금 나노입자의 합성 상태는 금 나노입자가 갖는 독특한 흡광 스펙트럼으로 확인하였으며, 금 나노입자의 농도는 원자 흡광분석기로 측정하였다. 세포의 독성평가는 MTT assay와 이중 염색법을 사용하였으며, 금 나노입자의 광열 효과는 제논 램프를 광원으로 하여 금 나노입자의 농도의 증가에 따른 광열 효과증대를 적외선-열화상 카메라로 확인하였다. 금 나노입자의 광열 효과를 온열 화장품에 적용한다면 한대 지방의 기후, 또는 겨울철에 태양 에너지를 열에너지로 전환시켜 피부에 손실된 열을 공급, 피부온도 유지에 도움이 되고 피부건강에 긍정적 효과를 주리라 사료된다.