• Ocean and Polar Research
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• 제45권3호
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• pp.103-111
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• 2023

To evaluate the impact of effluents from land-based fish farms on the coastal ocean of Wando, Korea, we analyzed inorganic nutrients, particulate organic carbon (POC), dissolved organic carbon (DOC), and colored dissolved organic matter (CDOM) in the effluent and influent of land-based fish farms during the summer (July) of 2021. The average concentrations of nutrients (Dissolved inorganic nitrogen, phosphorus, and silicate; DIN, DIP, and DSi, respectively) in the effluents of this study area were 17±3.7 μM, 1.4±0.7 μM, and 14±1.6 μM, respectively. The average concentrations of POC and DOC were 37±22 μM and 81±13 μM, respectively, with POC accounting for about 30% for total organic carbon in effluents. The Reduced Dissolved Inorganic Nitrogen/Total Dissolved Inorganic Nitrogen ratio (0.7), potential short-period index, indicates that the discharge of nutrients excreted by the fish and unconsumed feed into coastal water results in such nutrients being deposited and accumulated in the sediment. Subsequently, this continuous accumulation triggers the release of ammonium ions during organic matter decomposition, and the ammonium-enriched waters that encroach on fish farms as influent seem to be due to the diffusion of high concentrations of ammonium from bottom sediment. Furthermore, we used fluorescence indices to examine the characteristics of organic matter sources, obtaining mean values of 1.54±0.19, 1.06±0.06, and 1.56±0.06 for the humification index, biological index, and fluorescence index, respectively, in the effluent. These results indicate that the organic matters had an autochthonous origin that resulted from microbial decomposition, and such organic matters were rapidly generated and removed by biological activity, likely supplied from the sediment. Our results suggest that the effluent from land-based fish farms could be a potential source of deoxygenation occurrence in coastal areas.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.381.1-381.1
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• 2014

In this study, we investigated the deposition behavior and the etch resistivity of plasma polymerized carbon hardmask (ppCHM) film with the variation of process temperature. The etch resistivity of deposited ppCHM film was analyzed by thickness measurement before and after direct contact reactive ion etching process. The physical and chemical properties of films were characterized on the Fourier transform infrared (FT-IR) spectroscope, Raman spectroscope, stress gauge, and ellipsometry. The deposition behavior of ppCHM process with the variation of temperature was correlated refractive index (n), extinction coefficient (k), intrinsic stress (MPa), and deposition rate (A/s) with the hydrocarbon concentration, graphite (G) and disordered (D) peak by analyzing the Raman and FT-IR spectrum. From this experiment we knew an optimal deposition condition for structure of carbon hardmask with the higher etch selectivity to oxide. It was shown the density of ppCHM film had 1.6~1.9 g/cm3 and its refractive index was 1.8~1.9 at process temperature, $300{\sim}600^{\circ}C$. The etch selectivity of ppCHM film was shown about 1:4~1:8 to undoped siliconoxide (USG) film (etch rate, 1300 A/min).

• Advances in nano research
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• 제9권4호
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• pp.251-261
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• 2020

In this article, vibration attributes of single walled carbon nanotubes based on Galerkin's method have been investigated. The influence of power law index subjected to different end supports has been overtly examined. Application of the Hamilton's variational principal leads to the formation of partial differential equations. The effects of different physical and material parameters on the fundamental frequencies are investigated for armchair and zigzag carbon nanotubes with clamped-clamped, simply supported and clamped-free boundary conditions. By using volume fraction for power law index, the fundamental natural frequency spectra for two forms of Single-Walled Carbon Nanotubes (SWCNTs) are calculated. The influence of frequencies against length-to-diameter ratios with varying power law index are investigated in detail for these tubes. MATLAB software package has been utilized for extracting tube frequency spectra. The obtained results are confirmed by comparing with available literature.

• 한국전기전자재료학회논문지
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• 제21권9호
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• pp.808-811
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• 2008

Optical and mechanical properties of diamond-like carbon (DLC) films synthesized by RF plasma enhanced chemical vapor deposition were investigated as a function the C/H ratio in gas mixture. The C/H ratio was varied from 6 to 10 %, adjusting the amount of $CH_4$ and $H_2$ as the source gas. The optical and mechanical properties of DLC films were characterized by UV spectrometer, Ellipsometer and Nano-indenter. The change of the C/H ratio during synthesis of DLC films had many effects on the growth rate, transmittance, refractive index and hardness. The growth rate of the films increased exponentially with the increase in C/H ratio. The hardness of the films showed the tendency to improve with increasing C/H ratio, whereas the transmittance decreased. The refractive index was varied from 2.03 to 2.17, and these refractive indexes close to 2.0 indicates that it can be applied to Si-based solar cell.

• 한국산업융합학회 논문집
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• 제22권3호
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• pp.273-280
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• 2019

Carbon fiber composite laminate has been widely used in the area of sports applications such as race car, golf club, fishing rods, yacht. In this study, carbon fiber composite laminate was used in the rear upright of leisure purposed small size single-seat electric race car to reduce its unsprung mass of suspension system. The focus of this research is to investigate in finding optimal stacking lay-up of rear upright laminated with carbon fiber composite in the early design phase. Forces transferred from circuit road to rear upright were estimated through MBD(Multi-Body Dynamics)model of the rear suspension geometry. To evaluate the strength of the rear upright laminated with carbon fiber composite which generally behaves in an anisotropic or orthotropic manner, FEA(Finite Element Analysis) model suitable for composite materials was built followed by its strength was evaluated depending on different stacking lay-up. The result showed that Symmetric stacking lay-up [$45^{\circ}/-45^{\circ}/90^{\circ}/0^{\circ}$]s for frontal area and symmetric stacking lay-up with 1mm aluminum core [$45^{\circ}/-45^{\circ}/90^{\circ}/Core$]s for rear area were most suitable of 16 lay-up cases from the side of both strength based on Tasi-wu failure index and weight.

• 자원ㆍ환경경제연구
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• 제26권1호
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• pp.1-35
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• 2017

본 연구에서는 탄소세를 시행하고 있는 OECD 7개 국가를 대상으로 1995년부터 2013년 기간 동안 $CO_2$ 배출량 감소에 영향을 미치는 주요 요인에 대해 분해 분석을 실시하였다. 최근까지 진행된 $CO_2$ 배출량 변화에 대한 분해 분석 연구들은 기술에 기반을 둔 물리적인 요소에만 초점을 맞추고 있으나 본 연구는 경제적 감축수단인 탄소세의 효과를 반영하여 배출량 변화요인을 분석하였다. 로그 평균 디비지아 지수(Log Mean Divisia Index, LMDI)를 이용하여 분석한 결과, OECD 7개 국가의 총 $CO_2$ 배출량 감소에 가장 큰 기여요인은 에너지 집약도 효과와 탄소세 정책 효과로 나타났다. 다음으로, OECD 7개 국가별 분해분석 결과 에너지 집약도 효과가 배출량 감소에 가장 큰 영향을 주는 것으로 나타났으나, 탄소세 정책효과와 탄소세 세수효과는 국가별 정책 상황과 여건에 따라 상이하게 나타나는 결과를 보였다.

• 대기
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• 제34권2호
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• pp.123-138
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• 2024

Using 18 multi-model-based a Shared Socioeconomic Pathway (SSP) and Representative Concentration Pathways (RCP) climate change scenarios, future changes in temperature and warmth index on the Korean Peninsula in the 21st century (2011~2100) were analyzed. In the analysis of the current climate (1981~2010), the ensemble averaged model results were found to reproduce the observed average values and spatial patterns of temperature and warmth index similarly well. In the future climate projections, temperature and warmth index are expected to rise in the 21st century compared to the current climate. They go further into the future and the higher carbon scenario (SSP5-8.5), the larger the increase. In the 21st century, in the low-carbon scenario (SSP1-2.6), temperature and warmth index are expected to rise by about 2.5℃ and 24.6%, respectively, compared to the present, while in the high-carbon scenario, they are expected to rise by about 6.2℃ and 63.9%, respectively. It was analyzed that reducing carbon emissions could contribute to reducing the increase in temperature and warmth index. The increase in the warmth index due to climate change can be positively analyzed to indicate that the effective heat required for plant growth on the Korean Peninsula will be stably secured. However, it is necessary to comprehensively consider negative aspects such as changes in growth conditions during the plant growth period, increase in extreme weather such as abnormally high temperatures, and decrease in plant diversity. This study can be used as basic scientific information for adapting to climate change and preparing response measures.

• Carbon letters
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• 제16권2호
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• pp.121-126
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• 2015

Carbon fibers are prepared by stabilizing pitch fibers accompanying electron beam (E-beam) irradiation. The carbon fibers pretreated by E-beam irradiation achieve a higher stabilization index than the carbon fibers that are only heat-stabilized. In addition, the carbon fibers subjected to E-beam irradiation in the stabilization step exhibit a comparable tensile strength to that of general purpose carbon fibers. The carbon fibers pretreated with an absorbed dose of 3000 kGy have a tensile strength of 0.54 GPa for a similar fiber diameter. Elemental, Fourier-transform infrared spectroscopy, and thermogravimetric analyses indicate that E-beam irradiation is an efficient oxidation and dehydrogenation treatment for pitch fibers by showing that the intensity of the aliphatic C-H stretching and aromatic $CH_2$ bending (out-of-plane) bands significantly decrease and carbonyl and carboxylic groups form.

• 한국재료학회지
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• 제29권12호
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• pp.735-740
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• 2019

The purpose of this study is to fabricate an ophthalmic lens by copolymerizing two types of carbon nanotubes and hydrophilic hydrogel lens materials, and to investigate its application as an ophthalmic lens material by analyzing its physical properties and antimicrobial effect. For polymerization, HEMA (2-hydroxyethyl methacrylate), EGDMA (ethylene glycol dimethacrylate), a crosslinking agent, and AIBN (azobisisobutyronitrile), an initiator, are used as a basic combination, and a single-walled carbon nanotube and a single-walled, carboxylic-acid-functionalized carbon nanotube are used as additives. To analyze the physical properties, the water content, refractive index, breaking strength, and antimicrobial effect of the fabricated lenses are measured. The fabricated lenses satisfies all the basic properties of the basic hydrogel ophthalmic lens. The water content increases with increasing amount of additive and decreases with addition of 0.2 % ratio of nanoparticles. The refractive index is inversely proportional to the water content result. As a result of the antimicrobial test of the fabricated lens, the addition of carbon nanotubes shows an excellent antimicrobial effect. Therefore, it is considered that the fabricated lens can be applied as a functional material for basic ophthalmic hydrogel lenses.

• The Journal of Asian Finance, Economics and Business
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• 제4권4호
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• pp.61-66
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• 2017

Environmental awareness and its relation to the development of economy has garnered increased attention in recent years. Researchers, over the years, have argued that sustainable development warrants for minimizing environmental degradation since one depends on the other. This study analyzes the relationship between environmental degradation (carbon emission taken as proxy for degradation), economic growth, total energy consumption and industrial production index growth in Bangladesh from year 1998 to 2013. This study uses Vector Autoregression (VAR) Model and variance decomposition of VAR to analyze the effect of these variables on carbon emission and vice-versa. The findings of VAR model suggest that industrial production and GDP per capita has significant relationship with carbon emission. Further analysis through variance decomposition shows carbon emission has consistent impact on industrial production over time, whereas, industrial production has high impact on emission in the short run which fades in the long run which is consistent with Environmental Kuznets Curve (EKC) hypothesis. Carbon emission rising along with GDP per capita and at the same time having low impact in the long run on industrial index indicates there may be other sources of pollution introduced with the rise in income of the economy over time.