PURPOSES : This study aimed to evaluate the performance of carbon-reduced asphalt mixtures based on asphalt binder and asphalt mixture tests. METHODS : A carbon-reducing asphalt additive was developed, and samples were prepared by mixing the additive(0.85%, 1.35%, and 1.85%) with virgin asphalt binder to measure changes in the asphalt’s physical properties based on the content of the developed additive. The basic physical properties the penetration, softening point, ductility, and rotational viscosity and performance grade of the samples were measured, and the optimal content of the additive was determined to be 1.35%. An asphalt mixture was produced using the optimal additive content of 1.35%, and stability, indirect tensile strength, tensile strength ratio(TSR), and dynamic stability tests were conducted to compare its performance with that of hot mixed asphalt(HMA). Additionally, a dynamic modulus test that could simulate various loading conditions was conducted. Fuel consumption and CO2 emission were measured at the plant. RESULTS : The developed additive had the effect of reducing the viscosity of the binder while maintaining properties similar to those of the base binder when used at the selected content. The mixture test confirmed that the physical properties related to strength tended to decrease slightly when the additive were applied; however, all specifications were satisfied. In the dynamic modulus test, the results were confirmed to be similar to those of HMA. The fuel consumption and CO2 emission were reduced by 25-30%. CONCLUSIONS : Evidently, asphalt mixtures with carbon-reducing additives can perform at a level equivalent to that of HMA. To bolster this conclusion, it is necessary to track the long-term performance of low-carbon asphalt mixtures on pilot roads.

The study used the whole-life carbon assessment method to conduct a thorough carbon-neutral evaluation of a standard steel structure. To further assess carbon emissions, 11 design-changed models were evaluated, with changes made to the span between beams and columns. The results of the carbon emission assessment showed savings of approximately 13.1% by implementing the stage of the beyond life cycle. Additionally, the evaluation of carbon emissions through design changes revealed a difference of up to 42.2%. These findings confirmed that recycling and structural design changes can significantly reduce carbon emissions by up to 48.6%, making it an effective means of achieving carbon neutrality. It is therefore necessary to apply the stage of beyond life cycle and structural change to reduce carbon emissions.

Feasibility is investigated for reduction of chromium ore by Si sludge with mixed silicothermic and carbothermic reaction. The reduction behavior of chromium ore using Si sludge is investigated precisely to determine the effects of carbon addition, reaction time, and reaction temperature. The pellets are dropped into the furnace after temperature stabilized. As the amount of C addition increases, the amounts of CO and CO2 gas generation increase. After the dropping of the pellets, the pellets are heated and the reaction starts at about 1,573 K or higher. The pellets maintain their shape until 10 min after the drop, and then melted. As the holding time increased, the size of the reduced metal particles increased. The chromium ore is rapidly reduced by the Si sludge, and the slag penetrated into the chromium ore and reduction progressed inside. As the reduction temperature increased, the reaction initiation time is shortened and the reaction fraction of the reduction reaction increased. As the reaction temperature increased, agglomeration of reduced ferrochrome metal is promoted.

Spherical Li3V2(PO4)3 (LVP) and carbon-coated LVP with a monoclinic phase for the cathode materials are synthesized by a hydrothermal method using N2H4 as the reducing agent and saccharose as the carbon source. The results show that single phase monoclinic LVP without impurity phases such as LiV(P2O7), Li(VO)(PO4) and Li3(PO4) can be obtained after calcination at 800 oC for 4 h. SEM and TEM images show that the particle sizes are 0.5~2 μm and the thickness of the amorphous carbon layer is approximately 3~4 nm. CV curves for the test cell are recorded in the potential ranges of 3.0~4.3 V and 3.0~4.8 V at a scan rate of 0.01 mV s–1 and at room temperature. At potentials between 3.0 and 4.8 V, the third Li+ ions from the carbon-coated LVP can be completely extracted, at voltages close to 4.51 V. The carbon-coated LVP exhibits an initial specific discharge capacity of 118 mAh g–1 in the voltage region of 3.0 to 4.3 V at a current rate of 0.2 C. The results indicate that the reducing agent and carbon source can affect the crystal structure and electrochemical properties of the cathode materials.

In this study, carbon dioxide (CO2) was used as an inhibitor of scale production on the surface of RO membrane. In order to compare the effects of CO2 injection on scale production, four RO modules: 1) without CO2 injection and anti-scalant (RO module #1), 2) with only CO2 injection (RO module #2), 3) with only anti-scalant (RO module #3), 4) with both CO2 injection and anti-scalant (RO module #4), were operated for 60 days under constant flux mode. The trans-membrane pressure (TMP) was observed to decrease significantly in RO modules with CO2 injection as compared with the other RO modules. When the feed water pH was controlled at 5.0 by injecting CO2, the maximum TMP in RO modules #2 and #4 was founded to decrease by 42 aㅋnd 40%, respectively. Moreover, the Ca2+ concentration in the concentrate was 20mg/L lower in RO modules without CO2 injection which is attributed to the scale formation on the surface of the RO membranes. The SEM-EDS analysis further showed a serious fouled RO membrane surface in RO modules #1 and #3.

PURPOSES: This study intends to develop an inorganic soil pavement material using industrial by-products and to evaluate its applicability as a road pavement material. METHODS: In this study, a compressive strength experiment was conducted based on the NaOH solution molarity and water glass content to understand the strength properties of the soil pavement material according to the mixing ratio of alkali activator. In addition, the strength characteristic of the inorganic soil pavement material was analyzed based on the binder content. The performance of the soil pavement was evaluated by conducing an accelerated pavement test and a falling weight deflectometer (FWD) test. RESULTS: As a result of the soil pavement material test based on the mixture ratio of alkali activator, it was identified that the activator that mixed a 10 M NaOH solution to water glass in a 5:5 ratio is appropriate. As a result of the inorganic soil pavement materials test based on the binder content, the strength development increased sharply when the amount of added binder was over 300 kg; this level of binder content satisfied 28 days of 18 MPa of compression strength, which is the standard for existing soil pavement design. According to the measured results of the FWD test, the dynamic k-value did not show a significant difference before or after the accelerated pavement testing. Furthermore, the effective modulus decreased by approximately 50%, compared with the initial effective modulus for pedestrian pavement. CONCLUSIONS: Based on these results, inorganic soil pavement can be applied by changing the mixture proportions according to the use of the pavement, and can be utilized as road pavement from light load roads to access roads.

배출권거래제도는 경제성과 유연성을 제공하는 제도이다. 즉, 비용경제적인 방법으로 오염배출량을 감소하게 된다. 배출권거래제도하에서 오염원인자는 ① 부여된(할당받은) 배출권량 수준의 준수, ② 부여된 배출권량 수준이하의 배출 및 이에 따라 발생한 잉여분의 타 오염원인자에게의 판매, ③부여받은 배출권량 수준 이상으로의 초과배출을 위한 매수 등의 방안을 선택하게 된다. 구체적으로, 배출권거래제도는 오염원으로 하여금 가능한 한 적은 비용을 들이면서 오염배출량을 감소토록 하고, 그에 따라 발생하는 잉여분을 타에 판매토록 유인하는 작용을 한다. 그리고 배출권거래제도는 오염물질의 총배출한도 및 이에 따른 배출권 점진적인 감소는 배출권의 취득가격을 상승시키고, 일정 시점에서는 배출권의 구입비용보다 배출을 줄이는 비용이 적게 되어, 급기야 개별오염원으로 하여금 오염배출의 감소를 선택하게 된다. 또한, 배출권거래제도는 정부에 의하여 시장에 부여된 오염총량을 가장 비용효율적으로 달성할 수 있도록 함을 주된 목적으로 하는 제도이다. 아울러, 배출권거래제도는 전통적인 명령규제방식보다 민주적인 의사결정 과정을 제공한다는 장점을 가지고 있으며, 배출권거래제도는 오염배출량을 감소하는 기술혁신을 끊임없이 조장한다. 잉여분을 타에 판매하는 것은 기업의 이익을 의미하는바, 그 판매는 오염배출량을 저감시키는 연구개발, 기술 및 자본투자를 촉진하게 된다. 우리나라는 배출권거래제도와 관련하여 대기오염이 심각한 수도권지역의 대기환경을 개선하기 위하여 2003년 12월 31일 제정된 수도권대기환경개선에관한특별법이 있으며, 2010년 1월 13일 제정된 저탄소녹색성장기본법이 있다. 특히, 수도권대기환경개선에관한특별법에 있어서는 배출허용총량의 이전이 금지되는 오염물질 등의 확대, 배출허용총량의 할당 및 배출권거래의 이전 절차와 방법 등에 있어서 경매를 통한 배출허용총량의 할당 및 이전, 자발적인 사업자의 참여 조장 등의 거래시장의 활성화 확대가 요구된다. 그리고, 저탄소녹색성장기본법의 원활한 시행을 위해서는 적용대상 오염물질, 적용대상 사업장 또는 적용 대상지역, 탄소거래소 설치 등에 대한 제도(규정화)화가 선행되어야 한다. 그 다음 배출권거래가 원활히 이루어질수 있도록 거래시장의 활성화가 이루어져야 하며, 국제시장과의 연계방안을 적극 고려해야 할 것이다. 그리고 온실가스 배출저감을 위한 과학적인 조사·연구, 회수·재사용 및 대체물질의 개발 등의 시책을 강구하여야 한다.