• 한국지열·수열에너지학회논문집
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• 제9권1호
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• pp.15-19
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• 2013

In this Study, effect of core position, area ratio and orientation of building on energy load is examined using TRNSYS17. This parameters are major parameters of the conceptual design stage. Reference model is square floor plan($1,444m^2$), centered core and 29% core area ratio. As the results, without considering the building orientation, the annual heating load of central building with 1:1 area ratio is lowest ($10.33kWh/m^2yr$) and the annual cooling load of off-central building with 1:1 area ratio is lowest ($59.27kWh/m^2yr$). As area ratio is bigger, cooling load is lower and heating load is higher. But if we consider building orientation, orders of heating load and cooling load are changed for area ratio and orientation.

• 대한금속재료학회지
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• 제50권7호
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• pp.531-538
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• 2012

In this study, we evaluated the fluidity of the Al-Zn based alloys which exhibit excellent mechanical properties. We conducted computer simulations of fluid flow using the results of DSC, DTA analysis and Java-based Materials Properties software (J. Mat. Pro). Such computer simulations were then compared with the results obtained from experimental observations. The computer simulation results and the experimental results were very similar in fluidity length. It was found that the fluidity length of Al-Zn alloys is improved by increasing the Zn content while decreasing the solidus temperature of an alloy. In addition, we elucidate the effect of Zn addition on variations in different mechanical properties and the microstructure characteristics of (Al-xZn3Cu0.4Si0.3Fe) x=20, 30, 40, and 45 wt% alloys fabricated by gravity casting.

• 대한금속재료학회지
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• 제48권10호
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• pp.936-941
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• 2010

Al-Zn based alloys are the most common types of wrought Al alloys. Although Al-Zn alloys have high strength, they cannot be applied to a conventional casting process. In this study, Al-Zn-based alloys applicable to a die casting process were developed successfully. The developed Al-45 wt% Zn-based alloys showed a fine equiaxed grain structure and high strength. A fine equiaxed grain having an average size of $25{\mu}m$ was obtained by the die casting process. The UTS and elongation of the new alloy are 475 MPa and ~3.5%, respectively. In addition, we elucidate the effect of a Zn addition on variations in different mechanical properties and the microstructure characteristics of (Al96.3-xZnxCu3Si0.4Fe0.3) x=20, 30, 40, and 45 wt% alloys fabricated by a die casting process.

• 대한금속재료학회지
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• 제50권4호
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• pp.293-299
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• 2012

Ultrafine-grained or nanostructured alloys usually lack the strain hardening capability needed to sustain uniform tensile deformation under high stresses. To circumvent this problem, we fabricated the Cu-based composite reinforced with the 3-dimensionally interconnected $Cu_5Zr$ phase using the combined technique of rapid quenching and subsequent hot-rolling. The alloy exhibited a tensile ductility of ~2.5% together with a strength of 1.57 GPa, which exceeds the values of most commercially available Cu-Be alloys. In this study, we elucidated the structural origin of the high strength and tensile ductility of the developed alloy by examining the thermal stability of the $Cu_5Zr$ reinforcing phase and the energy (work) absorption capability of the Cu matrix.

• 신재생에너지
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• 제18권3호
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• pp.72-84
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• 2022

As the threat of climate change escalates, 'net-zero' has become a priority for the international community, and the use of new and renewable energy sources is expected to play a significant role in reaching international carbon neutrality. Here, we evaluate technological competitiveness in terms of implementation and technology by analyzing scientific literature and patents in the new and renewable energy fields of five major countries. For the past 10 years (2009-2019), the most active areas of new and renewable energy research and development have been solar power, wind power, waste, and fuel cells. China is the forerunner in implementation, whereas the United States has the most advanced technology. Portfolio analysis revealed that Korea's fuel cell, the United States' bioenergy, China's waste, Japan's solar and fuel cell, and the European Union's wind power have shown to be in Star Field respectively. Technological competitiveness analysis found that Korea is lagging behind other countries in the new and renewable energy sector, and needs to set a new direction for future carbon-neutral research and development, investment, and policy.

• 한국환경과학회지
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• 제32권9호
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• pp.627-634
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• 2023

Tire wear particles(TWPs), regarded as a microplastic, is generated in significant quantities each year and exist in various spaces and have a negative impact on the surrounding environment. Particularly, roadside environments fall within the direct influence of TWPs, necessitating proactive investigation for contamination management and response. Therefore, this study aimed to investigate the soil acidity and electrical conductivity(EC) and TWPs in the roadside soil of six sites based on traffic volume. The analysis revealed that the soil in all sites exhibited subacidity, and there were no significant differences in EC. Microscopic and FT-IR analysis revealed the presence of microscopic particles in soil samples that exhibited common visual characteristics of TWPs. In the road with the highest traffic volume, 48,300 TWPs were detected per unit area. Furthermore, a proportional relationship between traffic volume and TWPs particles was established. However, influences other than traffic volume on TWPs particle count within the soil were observed. Therefore, for the management of TWPs contaminated roadside soil, a proactive response is necessary in areas with high traffic volumes. However, in order to effectively address the factors contributing to the generation and dispersion of TWPs, further research is required with a multidimensional approach.

• 한국전기전자재료학회논문지
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• 제35권5호
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• pp.499-503
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• 2022

La_0.7Sr_0.3MnO₃ precursor solution were prepared by a sol-gel method. La_0.7Sr_0.3MnO₃ thin films were fabricated by a spin-coating method on a Pt/Ti/SiO₂/Si substrate. Structural and electrical properties with the variation of sintering temperature were measured. All specimens exhibited a polycrystalline orthorhombic crystal structure, and the average thickness of the specimens coated 6 times decreased from about 427 nm to 383 nm as the sintering temperature increased from 740℃ to 830℃. Electrical resistance decreased as the sintering temperature increased. In the La_0.7Sr_0.3MnO₃ thin films sintered at 830℃, electrical resistivity, TCR, B-value, and activation energy were 0.0374 mΩ·cm, 0.316%/℃, 296 K and 0.023 eV, respectively.

• 멤브레인
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• 제33권6호
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• pp.439-446
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• 2023

세라믹 분리막은 높은 열적, 화학적 안정성을 갖기 때문에 극한의 조건에서 운전되는 다양한 산업 공정에 적용할 수 있다. 그러나 투과도와 기계적 강도의 trade-off 현상에 의한 세라믹 분리막 활용에 제약이 있어, 고투과성-고강도 분리막의 개발이 필요하다. 본 연구에서는 상전이-압출법으로 알루미나 중공사 분리막을 제조하고, 고분자 바인더의 종류와 그 혼합비에 따른 분리막의 특성 변화를 관찰하였다. 용매인 DMAc (Dimethylacetamide)와 고분자 바인더의 한센 용해도 인자를 비교하면, PSf (polysulfone)가 DMAc와 높은 용해도 특성을 갖기 때문에 도프 용액의 점도와 토출압력이 높게 나타나 분리막 내부가 치밀한 구조로 형성되기 때문에 높은 기계적 강도를 갖으나 수투과도가 감소하는 것으로 확인되었다. 그에 반해, PES(polyethersulfone)를 이용하여 분리막을 제조하면 기계적 강도가 다소 감소하고 수투과도가 증가하는 것으로 나타났다. 따라서 분리막 성능과 물성을 최적화하기 위해 PSf와 PES를 혼합하여 분리막을 제조하였으며, 9:1로 혼합하여 제조된 분리막에서 최적화된 수투과도와 기계적 강도를 얻을 수 있었다.

• 농약과학회지
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• 제16권4호
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• pp.294-301
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• 2012

일시에 수확하는 경채류 중 쪽파와 부추에 대한 살충제 bifenthrin와 chlorfenapyr의 잔류특성을 비교 조사하였다. 수확일을 기준으로 각각 1주일 간격으로 2회 살포한 후 수확당일, 수확 3일 전, 수확 7일 전, 수확 10일 전 및 수확 14일 전에 시료를 수거하여 잔류량을 조사하였다. 수확당일의 잔류량을 기초하여 작물 중 농약살포액의 부착량을 환산한 결과, 쪽파의 경우 123.0-125.5 mL/kg, 그리고 부추에서는 70.0-74 mL/kg으로 조사되어 쪽파가 부추에 비해 더 많은 살포액이 부착될 수 있는 것으로 나타났다. 각 작물에서 bifenthrin과 chlorfenapyr의 생육기간 중 농약의 분해소실 정도를 조사한 결과, 쪽파에서 bifenthrin의 분해소실곡선은 y = 1.0334 $e^{-0.0602x}$ ($R^2$= 0.8606), chlorfenapyr는 y = 2.2603 $e^{-0.0519x}$ ($R^2$= 0.9043)이었으며, 부추에서는 bifentrhin의 경우, y = 0.7693 $e^{-0.1823x}$ ($R^2$= 0.9756), chlorfenapyr는 y = 1.2940 $e^{-0.1051x}$ ($R^2$= 0.9782)으로 나타났다. 이 분해소실곡선을 이용하여 각 작물에서 두 농약의 분해반감기를 조사한 결과, bifenthrin의 경우, 쪽파에서 분해반감기는 11.51일이었으며, 부추에서는 3.80일로서 쪽파에서의 분해 반감기가 더 긴 것으로 나타났으며, chlorfenapyr의 경우에서도 쪽파 13.35일, 부추 6.59일로 쪽파에서의 분해반감기가 더 길었다. 쪽파와 부추에서 두 농약의 잔류특성이 비교되었을 때 농약살포 후 살포액의 부착량과 작물생육기간 중 농약의 분해반감기는 부추에서보다는 쪽파에서 더 많거나 긴 것으로 나타났다.

• Asian Journal of Innovation and Policy
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• 제12권2호
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• pp.268-276
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• 2023

As the climate crisis intensifies, the need to improve the climate resilience of developing countries is ever increasing. Hence, the international community is seeking ways to effectively conduct climate technology transfer by linking the projects with financial mechanisms. However, commercialization of climate technology in developing countries is no easy feat as comprehensive knowledge on the target country is a prerequisite for seeking a suitable technology-financial linkage measure. Hence, in-depth discussions on effective climate technology and financial linkage measures have become an important global agenda, and South Korea, as a country with long experience in climate technology transfer, and a strong ecosystem for public climate technology, should step forward to take up a leading role. Against this backdrop, this paper proposes strategies and implementation measures for linking funds from the Multilateral Development Banks (MDB) with Korea's Public Climate Technology (PCT) by examining several key areas of R&D, international cooperation, and technology commercialization.