• Journal of the Korean Geotechnical Society
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• v.40 no.1
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• pp.29-37
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• 2024

In this study, recycled concrete aggregates (RCA) were treated in a 5-kg-scale prototype reactor with carbon dioxide (CO₂) to enhance their material quality and geotechnical performance. The aggregate crushing value (ACV) and California bearing ratio (CBR) were measured on untreated RCAs and CO₂-treated RCAs. After CO₂ treatment, the ACV decreased from 35.6% to 33.2%, and the CBR increased from 97.5% to 102.4%. The CO₂ treatment caused a reduction of fine particle generation and an increase in bearing capacity through carbonation. When CO₂ treatment was performed with mechanical agitation, which provided additional enhancement in mechanical quality, the ACV was reduced further to 30.3%, and the CBR increased to 137.7%. If upscaled effectively, the proposed CO₂ treatment technique would be an effective method to reduce carbon emissions in construction industries.

• Journal of Energy Engineering
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• v.23 no.1
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• pp.46-57
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• 2014

This study analyzes whether the value-added structure of Korean wind power industry exhibits a virtuous cycle through the value chain(VC) within wind power firms and the value system(VS) among the wind power industries, using a regression analysis based on a survey about Korean wind power companies. According to the VC, the government's R&D support is analyzed to have contributed to an increase in the R&D investments of the wind power companies. An increase in corporates' R&D investments has led to an increase in corporates' R&D outputs, and in turn, induced a remarkable increase in the amounts of production. But an increase in production has not led to a decrease in the costs of production, not resulting in an increase in profit rates per sales amount. In addition, while an increase in profit rates is analyzed to have contributed to an increase in production, this did not induce further investments in corporate's R&D. The virtuous cycle of the value chain in Korean wind power firms is, therefore, analyzed to be weak. Next, the VS is analyzed by dividing the whole chain into the system group including rotor blades, gear boxes, and power generators, and the structure group, such as towers. Two groups are analyzed to have mutually positive effects in the processes of the government's support for corporates' R&D, corporates' investment in R&D, R&D outputs, and profit rates per sales amount. Such mutual positive effects are, however, not found in the processes of the amounts of production and the costs of production. These results demonstrates that the value system of Korean wind power industry is not completed. This study has a policy implication to need further efforts to create the virtuous cycle in the VC and VS of Korean wind power industry.

• Proceedings of the Safety Management and Science Conference
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• 2012.11a
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• pp.105-112
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• 2012

클라우드 서비스는 사용자가 인터넷 접속만으로 언제 어디서나 데이터, 네트워크, 콘텐츠 등의 사용이 가능한 서비스이다. 공공부문과 선진기업의 클라우드 서비스 도입이 증가하면서 관련 서비스가 급속히 확대되고 있고, 향후 시장규모가 급성장 할 것으로 전망된다. 특히 클라우드 서비스는 다양한 산업 도메인에 적용되어 새로운 융 복합 서비스가 나타나고 있는데, 본 연구에서는 다양한 클라우드 기반의 융 복합 서비스의 사례를 살펴본다. 본 연구에서는 다양한 클라우드 기반의 융 복합 서비스의 사례 분석을 위한 산업군을 분류하여 클라우드 기반의 융복합 서비스의 사례 연구를 수행하였다. 사례 연구를 통하여 클라우드 기반 융 복합 서비스의 활용 방안과 융 복합 서비스의 사례를 통한 시사점 및 발전전략을 제시하였다. 궁극적으로 클라우드 기반의 융 복합 서비스를 활성화하기 위해서는 클라우드 기술과 서비스에 관한 표준화 및 법제도정비를 조속히 추진하여야 하며 관련 서비스를 활성화할 수 있는 생태계 기반 조성이 필요하며 ICT산업은 물론 다양한 산업군이 참여하므로 생태계 구성원간의 윈-윈 할 수 있는 서비스 비즈니스 모델 발굴을 통한 선순환 구조의 조기형성이 중요함을 도출하였다.

• The Safety technology
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• no.187
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• pp.19-21
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• 2013

현대글로비스는 현대자동차 그룹 계열 종합물류유통기업으로 첨단 정보시스템과 선진 물류기술을 활용해 국내 국제물류, 해상운송, 물류컨설팅 등의 업무를 수행하는 전문업체이다. 또한 최근에는 물류는 물론 유통, 자원개발 및 자원순환을 활용한 친환경 경영 인프라를 구축해나가고 있다. 이번에 소개되는 현대글로비스 아산KD센터는 현대글로비스의 핵심 사업이라 할 수 있는 해외공장 자동차 조립생산용 부품(KD: KNOCK DOWN) 공급사업을 전문으로 하는 사업장이다. 2004년 11월 현대자동차 아산공장 인근 인주지방산업단지 내에 준공된 현대글로비스 아산KD센터는 임직원 50명과 협력사 인원 300명 등 총 350영의 인력을 갖추고 KD사업의 본산지로 자리매김해 나가고 있다. 실제로 이곳 센터는 발주에서 포장, 운송은 물론 현지에서의 내륙운송 및 보관 등 KD물류에 대한 종합서비스를 제공하고 있다. 이처럼 현대글로비스 아산KD센터는 자동차조립생산용 부품을 국내외 협력사로부터 조달해 전 세계로 운송 판매하고 있는 만큼 근로자의 안전보건이 기업경영의 초석이 되고 있다. 여기에 더해 세계 자동차산업의 경쟁력을 좌우하는 부품 물류산업을 선도하는 기업인만큼 이곳의 안전관리는 전국 안전인들의 남다른 관심을 받고 있다. 근로자의 안전보건을 밑바탕으로 글로벌 물류기업으로 비상하고 있는 현대글로비스 아산KD센터 찾아가봤다.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.763-771
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• 2014

Recently, a huge amount of sulfur has been produced as a byproduct of petroleum refining processes in Korea. Sulfur concrete is made of modified sulfur binder instead of cement paste, which has advantages of reducing $CO_2$ emission from cement industry as well as utilizing surplus sulfur. Also, sulfur concrete is a sustainable material that can be repetitively recycled. In this study, the physical properties of sulfur concrete are experimentally investigated. From the test results, sulfur concrete showed compressive strengths higher than at least 50MPa. Also, the unit weight, modulus of elasticity and splitting tensile strength of sulfur concrete was similar to that of Portland cement concrete (PCC). The coefficient of thermal expansion of sulfur concrete was a little larger than that of Portland cement concrete and sulfur concrete with mineral filler is helpful to lower the coefficient of thermal expansion. recycled aggregate sulfur concrete resulted in a slight reduction in the compressive strength, but sulfur concrete with recycled aggregate can achieve the high strength characteristics.

• Journal of Animal Environmental Science
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• v.15 no.1
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• pp.59-68
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• 2009

This study investigated the evaluation of maturity, stability, nutrient and heavy metal from rotating drum composter of food waste amended with poultry manure composting inoculated with effective microorganisms(EM). Composting were performed for the first, drying reactor($15m^3$) 3 hours and the second, composting reactor($30m^3$) 24 hours, and parameters monitored this period included moisture content, NaCl, pH, electrical conductivity(EC), C/N ratio, organic matter(OM), nutrient content and heavy metal. Changes in compost temperature during composting were maintained constantly in the range of $60{\sim}80^{\circ}C$ using firewood boiler(450 MJ/h). We examined physicochemical parameters and heavy metals in order to assess their effectiveness as stability and maturity, nutrient and harmful indicators such as seed germination rate<60%, potassium 1>%, dm and NaCl>1%, dm at the end of the final compost. The finished compost obtained after decomposition phase at the end of the 2nd composter could not be utilized for land improvement or reclamation.

• Journal of the Korean Society of Propulsion Engineers
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• v.6 no.2
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• pp.29-36
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• 2002

Experiments have been performed to investigate the effect of secondary venturi tip angle on flow and spray characteristics in gas turbine combustor with a swirl cup assembly. Three variations of secondary venturi tip angle are made: converging, straight and diverging angles. It is found that the variation of venturi tip angle results in the significant changes of flow and spray characteristics in gas turbine combustors, such as the size and location of recirculation zones. drop size and mass distribution affecting combustion efficiency and NOx emissions. In diverge case, central toroidal recirculation zone(CTRZ) exists near the exit, which is known to be beneficial for flame stability. But in converge case, the finest SMD distribution and uniform mass distribution are found and CTRZ is longer than other cases. Consequently, high combustion efficiency and low pollutant emission are expected in converge case.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.469-476
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• 2022

This study developed a Recurrent Neural Network model implemented through Long Short-Term Memory (LSTM) that generates long-term tidal level data at Busan Port using tide observation data. The tide levels in Busan Port were predicted by the Korea Hydrographic and Oceanographic Administration (KHOA) using the tide data observed at Busan New Port and Tongyeong as model input data. The model was trained for one month in January 2019, and subsequently, the accuracy was calculated for one year from February 2019 to January 2020. The constructed model showed the highest performance with a correlation coefficient of 0.997 and a root mean squared error of 2.69 cm when the tide time series of Busan New Port and Tongyeong were inputted together. The study's finding reveal that long-term tidal level data prediction of an arbitrary port is possible using the deep learning recurrent neural network model.

• Korean Chemical Engineering Research
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• v.60 no.3
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• pp.433-438
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• 2022

A carbon cycle model based method is proposed in order to evaluate the effectiveness of various policies and projects to achieve carbon neutrality. The proposed model was validated by properly reproducing the increase in the concentration of carbon dioxide in the atmosphere and the rise of the global average temperature from the data of anthropogenic carbon emissions and deforestation since the industrial revolution. As a case study, a carbon cycle impact assessment was performed for deforestation, reforestation, and afforestation. It was verified that the increase of carbon dioxide in the atmosphere is attributed not only to fossil fuel usage, but also to deforestation, and that even if deforestation is immediately followed by reforestation, it takes very long to return to the initial concentration. The proposed method is expected to be eventually applicable to simulation of potential climate control in the future, contributing to safety verification of various climate engineering techniques.

• Journal of the Korean Recycled Construction Resources Institute
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• v.7 no.1
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• pp.37-43
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• 2019

This research studied production of lightweight filling production for sink hole restoration utilizing various industrial by-products(2kinds of fly ash, petro-cokes CFBC ash, blast furnace slag fine particle). For this purpose, the mixed raw material properties(compressive strength) behaviors according to the blending ratio of industrial by-products were examined by applying the experimental design method and statistical analysis was performed using the commercial program MINITAB. Compressive strengths of industrial by-products were strongly dependent on blast furnace slag powder. Compressive strength(3days aging) was 3~11MPa depending on the amount of blast furnace slag powder used. The use of CFBC fly ash was evaluated to have the least effect on compressive strength. In addition, the compressive strength and the coefficient of permeability were measured by preparing foamed concrete for the experimental batch 1 condition in the mixture experimental design. In this case, the bulk density is 0.9 to 1.0, the apparent porosity is 30 to 50%, the compressive strength(3days old) is 1 to 2MPa, and the permeability coefficient is $10^{-2}$ to $10^{-3}cm/sec$.