• Advances in materials Research
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• 제13권3호
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• pp.173-181
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• 2024

Fly ash, plastic waste, and clay are mineral materials and residues commonly found in Malaysia. In this study, these materials were fully utilized as raw materials for synthesizing carbon nanotubes (CNTs). Recycled polypropylene, previously used as a food container, served as a carbon source. Fly ash and clay were explored as potential substrates for CNTs growth. The recycled polypropylene was thermally decomposed at 900 ℃ in an inert environment for 90 minutes. Carbon atoms released during this process were deposited on fly ash and clay substrates, which had been immersed in a ferrocene solution to provide a metal catalyst for CNTs growth. The deposited products were characterized using a Scanning Electron Microscope (SEM) and X-Ray Diffraction (XRD). Morphological analysis revealed that both fly ash and clay were coated with fiber-like structures, confirmed to be CNTs based on a diffraction peak around 26° from the XRD pattern. In conclusion, clay and fly ash demonstrate the potential to be utilized as substrates for CNTs formation.

• 공업화학
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• 제17권2호
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• pp.229-234
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• 2006

공기분위기에서 PVC와 PS의 혼합 분해시 ZnO의 영향에 관한 연구를 혼합비율 및 반응온도를 변화시키며 TG와 GC-MS를 이용하여 수행하였다. 본 연구로부터 혼합물에 있어서 PS의 양이 증가할수록 액상 생성물은 증가하였으며 기상 생성물은 감소함을 알 수 있었다. 또한 혼합물에 있어서 ZnO의 첨가량이 증가할수록 가스 생성물과 염화수소의 발생량은 감소하였으며 ZnO/Mixture = 0.5인 경우 ZnO의 영향에 의하여 염화수소가 거의 생성되지 않음을 확인할 수 있었다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2003년도 추계학술발표대회 논문집
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• pp.21-24
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• 2003

In general, to enhance physical properties of PET-layered silicate nanocomposites $(P_{et}LSNs)$, it has been well known that the organic modifiers should introduce into gallery regions. However, the organic modifiers in$(P_{et}LSNs)$ may result in thermal decomposition by melt processing at high temperature, and it necessarily lead to deteriorate various physical properties of final products. Therefore, in this study, $(P_{et}LSNs)$ excluding and including organic modifiers were prepared by solution method $(S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom})$ and we (focused on the effects of the organic modifiers in $P_{et}$ LSNs with exfoliation structure on the crystallization behaviors, the optical transparency, the thermal stability and the mechanical property. The absence and existence of organic modifiers in $S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom}$ were investigated by EA and TGA, and nano-structure of silicate layers in $S-P_{et}LSNs$ was evaluated by using WXRD, SAXS and TEM. $S-P_{et}LSNs_{eom} and S-P_{et}LSNs_{iom}$ were mixed with neat PET as masterbatches by melt method $(M-P_{et}LSNs_{eom} and M-P_{et}LSNs_{iom})$, and also neat PET was mixed with organically modified layered silicates (OLS) by conventional direct melt method $(D-P_{et}LSNs) at 270^{\circ}C$. As results, it was found that $M-P_{et}LSNs_{eom}, M-P_{et}LSNs_{iom}, and D-P_{et}LSN$ showed a exfoliated structure and exhibited faster crystallization rate, better thermal stability and mechanical property than those of neat PET due to the dispersed and detaminated silicate layers in PET matrix. Whereas, considering organic modifiers effect, $M-P_{et}LSNs_{eom} and D-P_{et}LSN$ exhibited slower crystallization rate, poorer optical, thermal and mechanical properties, in comparison to $M-P_{et}LSNs_{eom}> due to the thermal decomposition of organic modifier in $D-P_{et}LSNs$ during melt method.

• 한국수소및신에너지학회논문집
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• 제24권5호
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• pp.413-420
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• 2013

Effect of inherent volatile matters in fuels on electrochemical reactions of anode was investigated for a single direct carbon fuel cell (DCFC). Raw coals used as power source in the DCFC release light gases into the atmosphere under the operating temperature of DCFC ($700^{\circ}C$) by thermal decomposition and only char remained. These exhausted gases change the gas composition around anode and affect the electrochemical oxidation reaction of system. To investigate the effect of produced gases, comparative study was conducted between Indonesian sub-bituminous coal and its char obtained through thermal treatment, carbonizing. Maximum power density of raw coal ($52mW/cm^2$) was appeared higher than that of char ($37mW/cm^2$) because the gases produced from the raw coal during thermal decomposition gave additional positive results to electrochemical reaction of the system. The produced gases from coals were analyzed using TGA and FT-IR. The influence of volatile matters on anodic electrolyteelectrode interface was observed by the equivalent circuit induced from fitting of impedance spectroscopy data.

• KDI Journal of Economic Policy
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• 제32권3호
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• pp.33-69
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• 2010

본 논문에서는 1990년대 중반 이후 우리나라 교역조건의 추세적 하락요인을 Baxter and Kouparitsas(2000)의 분해방법론을 이용하여 분석해 보았다. 주요 분석결과는 다음과 같다. 교역조건의 변화의 분해방법을 통해 우리나라 교역조건의 하락추세가 대부분 공산품 대비 연료의 상대가격 상승으로 인한 재화상대가격효과에 기인함이 나타났다. 또한 전 세계 55개국의 교역조건 변화를 동일한 방법론으로 분해해 본 결과, 1990년대 중반 이후 재화상대가격효과에 의한 교역조건의 추세적 하락이 선진국 개도국을 불문하고 공산품 수출국의 공통적인 현상임을 보였다. 이는 우리나라 교역조건 하락의 주요 원인이 우리나라 내부적 요인보다는 예를 들어 중국의 무역확대 등 외부적 요인에 기인함을 시사한다. 회귀분석 결과 중국의 무역확대는 우리나라의 교역조건 하락의 중요한 원인이 되었으며, 특히 2000년대의 원유와 원자재 수입가격의 상승과 공산품의 수출가격을 하락시킨 것으로 나타났는데, 이는 교역조건 분해결과가 시사하는 바와 부합한다.

• Bulletin of the Korean Chemical Society
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• 제24권3호
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• pp.350-356
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• 2003

The mechanism of the decomposition of a bronchodilator, S-nitroso-N-acetyl-D,L-penicillamine (SNAP) by a bronchoconstrictor, aqueous sulfite, has been investigated in detail. The decomposition was studied using a conventional spectrophotometer at 336 nm over the ranges: 0.010 ≤ $[S^{IV}]_T$ ≤ 0.045 mol $dm^{-3}$, 3.96 ≤ pH ≤ 6.80 and 15.0 ≤ θ≤ 30.0 ℃, 0.60 ≤ I ≤ 1.00 mol $dm^{-3}$, and at ionic strength 1.00 mol $dm^{-3}$ (NaCl). The rate of reaction is dependent on the total sulfite concentration and pH in a complex manner, i.e., $k_{obs}\;=\;k_1K_2[S^{IV}]_T/ ([H^+]\;+\;K_2)$. At 25.0 ℃, the second order rate constant, $k_1$, was determined as $12.5\;{\pm}\;0.15\;mol^{-1}\;dm^3\;s^{-1}$. ${\Delta}H^{neq}\;=\;+32\;{\pm}\;3 kJ\;mol^{-1}\;and\;{\Delta}S^{\neq}\;=\;-138\;{\pm}\;13\;J\;mol^{-1}K^{-1}$. The N-nitrosohydroxylamine-N-sulfonate ion was detected as an intermediate before the formation of any of the by-products, namely, N-acetyl-D,L-penicillamine. The effect of concentration of aqueous copper(Ⅱ) ions on this reaction was also examined at pH 4.75, but there was no dependence on $[Cu^{2+}]$. In addition, the $pK_a$ of SNAP was determined as 3.51 ± 0.06 at 25.4 ℃ [I = 1.0 mol $dm^{-3}$ (NaCl)].

• 한국수소및신에너지학회논문집
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• 제27권1호
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• pp.13-21
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• 2016

The Sulfur-Iodine thermochemical hydrogen production process (SI process) consists of the Bunsen reaction section, the $H_2SO_4$ decomposition section, and the HI decomposition section. The $HI_x$ solution ($I_2-HI-H_2O$) could be recycled to Bunsen reaction section from the HI decomposition section in the operation of the integrated SI process. The phase separation characteristic of the Bunsen reaction using the $HI_x$ solution was similar to that of $I_2-H_2O-SO_2$ system. On the other hands, the amount of produced $H_2SO_4$ phase was small. To investigate the effects of $SO_2$ solubility on Bunsen reaction, the continuous Bunsen reaction was performed at variation of the amounts of $SO_2$ gas. Also, it was carried out to make sure of the effects of partial pressure of $SO_2$ in the condition of 3bar of $SO_2-O_2$ atmosphere. As the results, the characteristic of Bunsen reaction was improved with increasing the amounts and solubility of $SO_2$ gas. The concentration of Bunsen products was changed by reverse Bunsen reaction and evaporation of HI after 12 h.

• 한국안전학회지
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• 제15권3호
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• pp.66-70
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• 2000

In order to cope with environmental problems caused by harmful gases emitted from various industrial sources, a new technology which employs discharge plasma formed in ordinary atmospheric pressure has been intensively investigated in many industrialized nations. Although a plenty of useful outcomes and suggestions have been made public by scientists in this field, few commercial products which effectively decompose pollutant gases have appeared as yet. This is partly because that the energy efficiency of a most effective plasma reactor has not reached a satisfactory level in comparison with those of devices using conventional technologies. In an attempt to solve the problem mentioned above, we noticed to combine heterogeneous electrical discharges. This concepts is based on that each plasma reactor has its specific spatial region in which chemical reaction are active and by electrically affected with another reactor of different type, the activated region would increase - which may lead to cutting down the energy consumption. To prove this concept experimentally, two different discharge equipments, a plane ceramic-based surface discharge electrode and a corona electrode with tungsten needle may, are selected and combined to fabricate a hybrid plasma reactor. The results are summarized as follows; (1) Ozone concentration generated in the plasma region drastically increases when the positive corona discharge is added to the surface discharge. The rate of increase of ozone depends on the frequency of the surface discharge. The negative corona, however, does not contribute to the improvement of the ozone generation. (2) NO(nitrogen monoxide) decomposition rate also improves by simultaneously applying the surface and the positive corona discharges. The effect of the corona superposition is more evident when the level of the surface discharge is moderate. (3) By adjusting the corona level, the net energy efficiency during NO decomposition improves in comparison with the simple surface discharge reactor.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.216-219
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• 2000

목질계 바이오매스의 아세톤상 가용매분해는 목재의 구성성분인 셀룰로오스, 헤미셀룰로오스, 리그닌중에 가장 전환율이 낮은 리그닌의 전환율을 증가시킴으로 전체적인 목재의 전환율의 증가에 기여하였다 그러나 $300^{\circ}C$ 이상에서는 리그닌의 전환율이 감소하였다. 아세톤의 첨가에 관계없이 셀룰로오스와 헤미셀룰로오스의 전환율의 변화는 온도에 의존하기 때문에 주어진 열분해 온도에 따라 생성물을 선택적으로 얻을 수 있었다. 자일란의 경우 $250^{\circ}C$ 이하에서 전환되고 셀룰로오스의 경우 $250^{\circ}C$이하에서는 거의 전환되지 않지만 $250^{\circ}C$와 $300^{\circ}C$ 사이에서 급격한 전환율의 증가가 나타났다. 생성물은 주로 방향족류와 페놀류이며, 특히 리그닌의 아세톤 상 가용매 분해의 경우 $300^{\circ}C$에서의 메톡시 페놀류가 가장 많이 얻어졌다. $400^{\circ}C$이상의 반응에서는 메톡시기가 없는 methyl-, dimethyl-, trimethyl-, phenol 류가 생성되는 것으로 나타났다. 이것은 메톡시기를 제거시킬 만한 에너지가 $350^{\circ}C$ 이상에서 공급되는 것으로 사료된다.

• 보건행정학회지
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• 제26권4호
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• pp.333-342
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• 2016

Background: The use of therapeutic materials based on new health technology has increased in recent years in the field of medicine, raising concerns for medical practitioners regarding increased spending on the new therapeutic materials amid the rapid population ageing and increase of chronic diseases in Korea. While therapeutic materials have significant importance in the health care system, they have not been given appropriate attention in the academic world of Korea. The purpose of this study is to identify factors that affect the growth of expenditure on therapeutic materials and to derive implications for an effective management considering the diversity of therapeutic materials. Methods: Using the claims data of the National Health Insurance Services, specific utilization patterns of groups of therapeutic materials in the middle classification level of Health Insurance Review and Assessment Service from 2007 to 2014 were analyzed. Four categories (J5083: drug eluting coronary stent, D0302: nonmetallic anchor, K6014: gauze, K6023: gauze) that exhibit unique patterns with respect to price and volume were selected. Then, decomposition analysis was performed to identify the largest contributor to the spending growth by dividing the products into existing, new, and abandoned products for the period between 2010 and 2013. Results: The effect of new products had larger impact on spending growth than the effect of core items in drug eluting coronary stent (J5083) and nonmetallic anchor (D0302). In addition, existing products in general included items priced relatively lower when compared with another item manufactured by the same company. In the gauze category, however, existing products had the largest impact on expenditure and the effect of volume was greater than that in other categories. Conclusion: This study provides evidence that appropriate management measures classified by the characteristics of therapeutic materials are required for therapeutic materials pricing and reassessment in Korea.