냉매 R-10(CCl4)과 CH4 혼소 화염특성 전산해석 연구

신미수,김용주,장동순,이용국,이강우 한국폐기물자원순환학회 2014 한국폐기물자원순환학회지 Vol.31 No.8

Considering the high potential of the widely-used halogenated hydrocarbons on the global warming and ozone depletion, the development of effective thermal destruction methods of these compounds are quite urgent and indispensible. As part of the research efforts of this area, the destruction of CCl4 and flame characteristics have been investigated numerically by the co-firing CCl4 with CH4 in an industrial LNG-fired combustor as a function of molar ratio of the CCl4 to CH4 using a commercial code of STAR-CCM+. Considering a broad range of Damkohler number associated with the process of intensive CHCs (Chlorinated hydrocarbons) combustion with auxiliary fuel together with the inhibition reaction especially near flammability limits, a proper combustion modeling of CCl4 thermal destruction is quite desirable. In this study, however, after careful review of the literature about the flame characteristics of halogenated hydrocarbon together with the previous study about the modeling of the CCl4 flame based on the data of burning velocity, the eddy breakup turbulent combustion model was employed since it is quite reasonably assumed that chain branching reaction looks dominant in most flame region over the halogenated inhibition effect in strong turbulent reacting flows. One of the most useful results based on this study is that; without any incorporation of flame inhibition effect, the length of co-fired flame increases steadily as the ratio of CCl4 to CH4 (R) increases from 0.0, 0.1, 0.2 to 0.5, and 1.0 together with the increase of the maximum flame and exit gas temperature. The reason of the increase of the flame length with the increase of flame temperature can be explained by the presence of the additional CCl4 fuel with low heating value. Further a detailed discussion has been made on the thermal destruction of CCl4 together with the Cl2 concentration by Deacon reaction.

냉매 R-10(CCl4)과 CH4 혼소 화염특성 전산해석 연구

신미수,김용주,장동순,이용국,이강우 한국폐기물자원순환학회 2014 한국폐기물자원순환학회지 Vol.31 No.8

Considering the high potential of the widely-used halogenated hydrocarbons on the global warming and ozone depletion, the development of effective thermal destruction methods of these compounds are quite urgent and indispensible. As part of the research efforts of this area, the destruction of CCl4 and flame characteristics have been investigated numerically by the co-firing CCl4 with CH4 in an industrial LNG-fired combustor as a function of molar ratio of the CCl4 to CH4 using a commercial code of STAR-CCM+. Considering a broad range of Damkohler number associated with the process of intensive CHCs (Chlorinated hydrocarbons) combustion with auxiliary fuel together with the inhibition reaction especially near flammability limits, a proper combustion modeling of CCl4 thermal destruction is quite desirable. In this study, however, after careful review of the literature about the flame characteristics of halogenated hydrocarbon together with the previous study about the modeling of the CCl4 flame based on the data of burning velocity, the eddy breakup turbulent combustion model was employed since it is quite reasonably assumed that chain branching reaction looks dominant in most flame region over the halogenated inhibition effect in strong turbulent reacting flows. One of the most useful results based on this study is that; without any incorporation of flame inhibition effect, the length of co-fired flame increases steadily as the ratio of CCl4 to CH4 (R) increases from 0.0, 0.1, 0.2 to 0.5, and 1.0 together with the increase of the maximum flame and exit gas temperature. The reason of the increase of the flame length with the increase of flame temperature can be explained by the presence of the additional CCl4 fuel with low heating value. Further a detailed discussion has been made on the thermal destruction of CCl4 together with the Cl2 concentration by Deacon reaction.

Decomposition of gas-phase aromatic hydrocarbons by applying an annular-type reactor coated with sulfur-doped photocatalyst under visible-light irradiation

Jo, Wan-Kuen,Kim, Jong-Tae John Wiley Sons, Ltd. 2010 Journal of chemical technology and biotechnology Vol.85 No.4

<P>BACKGROUND: Unlike many water pollution applications, visible-light-driven photocatalysis of gas-phase pollutants has been reported only rarely. The present study was performed to investigate the feasibility of applying S-doped visible-light-induced TiO<SUB>2</SUB> to treat gas-phase aromatic hydrocarbons, using a continuous air-flow annular-type reactor.</P><P>RESULTS: The prepared S-enhanced TiO<SUB>2</SUB> powders, along with a commercially available TiO<SUB>2</SUB> powder (Degussa P-25), were characterized using diffuse reflectance UV-VIS-NIR spectrophotometry, Fourier transform infrared (FTIR) spectrophotometry, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and thermogravimetry (TG) analyses. A photocatalytic activity test exhibited an increasing trend in degradation reaction rates with increase in flow rate but a decreasing trend in terms of degradation efficiencies. Several experimental conditions induced reasonably high decomposition efficiencies with respect to toluene, ethyl benzene and o,m,p-xylenes (close to or above 90%), although benzene exhibited a somewhat lower decomposition efficiency.</P><P>CONCLUSIONS: The S-doped TiO<SUB>2</SUB> and undoped P25 TiO<SUB>2</SUB> powders exhibited different catalyst characteristics. The results demonstrate that an annular-type reactor coated with visible-light-activated S-doped TiO<SUB>2</SUB> can serve as an effective tool to treat gas-phase aromatic hydrocarbon streams. Copyright © 2009 Society of Chemical Industry</P>

저온 탄화한 바이오매스와 석탄 그리고 혼합물의 연소특성 평가

박상우 한국폐기물자원순환학회 2013 한국폐기물자원순환학회지 Vol.30 No.6

The following are the results from an evaluation of the combustion characteristics of biomass processed with lowtemperature carbonization and coal, and those of a blend of both. Differential thermo-gravimetric (DTG) analysis has revealed that the number of curves was reduced as a result of carbonization and that the fuel quality was improved due to the increase of initial temperature (IT). It was also confirmed that the carbonized samples consisting only of the biomass required less combustion time (tq), while samples blended with coal burned longer than the weighted average value. The combustion time of a blended sample was shorter at an carbonization temperature of 400oC than at 300oC, and the combustion stability was achieved due to a narrow range of change in the combustion characteristics. The reaction rate constant (k) of the samples blended with coal was found to be smaller for all blend ratios, when compared with that of the unblended samples (raw, carbonized biomass). The combustion reaction models that were applicable for the devolatilization-combustion zone were diffusion (D1, D3) and Reaction order (O3) models; diffusion (D1-D4) model was primarily employed in the char combustion zone. In summary, low-temperature carbonization contributed to minimizing the change in the combustion characteristics of the biomass/coal blend.

Production of poorly crystalline tricalcium phosphate nanopowders using different mechanochemical reactions

Bahman Nasiri-Tabrizi,Abbas Fahami 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

Poorly crystalline nano-sized tricalcium phosphate powders were successfully synthesized by two distinct mechanochemical reactions. Results revealed that the structural features as well as morphological characteristics were influenced by the chemical composition of reagents. The obtained nanopowders exhibited average sizes about 21 and 28 nm. According to the TEM/SEM observations, the synthesized powders showed cluster-like structures composed of spheroidal particles with a mean size of about 23 nm and ellipsoidal particles with an average size of about 30 nm. The proposed method as a new vision in powder technology can be used for mass production of nanostructured tricalcium phosphates.

고령운전자의 도시부 교차로 주행특성 분석에 관한 연구

정상민,최재성,이종학,민동찬 한국도로학회 2017 한국도로학회논문집 Vol.19 No.1

PURPOSES : Because elderly drivers are more prone to becoming confused when approaching an urban intersection and thus may yield prolong judgment and decision times than non-elderly drivers, to increase the comfort and safety of the intersection environment for elderly drivers, this study applied autonomous driving tests at an urban intersection to examine their driving characteristics. METHODS: To obtain a more comprehensive understanding of driving features, this study collected drive data of non-elderly drivers and elderly drivers via an autonomous experiment using OBD2 and an eye-tracker, in addition to performing a literature review on the measured visibility range of elderly drivers at intersections. This literature review was conducted considering the general knowledge of elderly drivers having relatively reduced visibility. Additionally, as they are commonly more vulnerable, this study analyzes characteristics of elderly drivers as compared to those of non-elderly drivers. CONCLUSIONS: The results of this study can be summarized as follows: 1) the peripheral visible distance of elderly drivers is reduced as compared to that of non-elderly drivers; 2) elderly drivers approach and proceed through intersections at slower speeds than non-elderly drivers; and 3) elderly drivers yield increased driving distances when performing a right or left turn as compared to non-elderly drivers as a result of their reduced speed and acceleration and larger turning radii relative to non-elderly drivers.

기업의 정보보안 투자에 시장이 어떻게 반응하는지에 대한 탐색적 연구

박재영,정우진,김범수 한국IT서비스학회 2018 한국IT서비스학회지 Vol.17 No.1

Recently, many South Korean firms have suffered financial losses and damaged corporate images from the data breaches. Accordingly, a firm should manage their IT assets securely through an information security investment. However, the difficulty of measuring the return on an information security investment is one of the critical obstacles for firms in making such investment decisions. There have been a number of studies on the effect of IT investment so far, but there are few researches on information security investment. In this paper, based on a sample of 76 investment announcements of firms whose stocks are publicly traded in the South Korea’s stock market between 2001 and 2017, we examines the market reaction to information security investment by using event study methodology. The results of the main effects indicate that self-developed is significantly related to cumulative average abnormal returns (CAARs), while no significant effect was observed for discloser, investment characteristics and firm characteristics. In addition, we find that the market reacts more favorably to the news announced by the subject of investment than the vendor, in case of investments with commercial exploitation. One of main contributions in our study is that it has revealed the factors affecting the market reaction to announcement of information security investment. It is also expected that, in practice, corporate executives will be able to help make an information security investment decision.

주의산만을 주소로 소아정신과를 내원한 아동의 인지적 특성 : T.O.V.A. 양상을 중심으로

신의진,이수진,이혜란,고려원 대한소아청소년정신의학회 2000 소아청소년정신의학 Vol.11 No.2

본 연구에서는 주의산만을 주소로 내원하는 아동을 진단 준거에 따라 분류하고 각 진단 집단을 설명할 수 있는 인지적 특성을 T.O.V.A. 양상을 중심으로 설명하였다. 소아정신과를 방문한 65명의 아동을 각각 주의력결핍 과잉행동장애(38명), 틱장애(17명), 그리고 기타 정서장애(10명) 집단으로 분류한 후 주의산만의 정도에 영향을 미칠 수 있는 집단의 연령 및 지능(전체 지능, 동작성 지능, 언어성 지능)을 먼저 파악한 후 T.O.V.A.의 중다구인(누락오류, 오경보오류, 정반응시간, 반응시간 표준편차, 예기반응, 다중반응)을 통해 주의산만의 양상을 살펴보았다. 세 집단 간에 연령에서 집단 간에 유의미한 차이가 나타나 연령 수준의 차이에서 기인한 효과를 배제한 결과, 언어성 지능에서 세 집단 간에 유의미한 차이가 나타났다. 또한, T.O.V.A.의 정반응 시간(전반부, 후반부, 전체)에서 세 집단간에 유의미한 차이가 있는 것으로 나타났다. 주의력결핍 과잉행동장애 집단은 틱장애 및 기타 정서장애 집단보다 T.O.V.A.의 정반응 시간이 길어 정보처리의 지연을 시사해 주었다. 한편 주의산만을 주소로 내원하는 아동의 경우 T.O.V.A. 양상과 더불어 연령과 지능의 효과에 대해 신중히 고려해야 할 필요가 있겠다. 중심 단어 : 인지적 특성ㆍ주의산만ㆍT.O.V.A.ㆍ정반응시간ㆍ주의력결핍 과잉행동장애ㆍ틱장애ㆍ기타 정서장애. Objective : This study aims to investigate the cognitive characteristics of clinically referred children with symptoms of inattention, cash as having ADHD, tic disorder, and emotional disorder. Methods : 65 boys(38 with ADHD, 17 with Tic disorder, and 10 with Emotional disorder) were individually assessed using the KEDI-WISC(FIQ, VIQ, PIQ) and T.O.V.A.(errors of omission, errors of commission, reaction time, variability, anticipatory response, multiple response), and the results of those tests were analyzed. Results : There was significant difference among three diagnostic groups of the VIQ of KEDI-WISC and the reaction time of T.O.V.A. after the correction of the effect of age difference. Conclusion : The finding suggest that the reaction time of T.O.V.A. might be the useful variable to differentiate the ADHD from other psychiatric disorders and the effect of age and IQ difference should be considered carefully to diagnose in clinical setting. KEY WORDS : Cognitive characteristicㆍInattentionㆍT.O.V.A.ㆍReaction time.

Decoupling Method Between Digital Signals on FPCB and Mobile Handset Antenna

Joonchul Kim,김형동 한국전자통신연구원 2011 ETRI Journal Vol.33 No.1

Digital harmonics, which may reduce the radio frequency sensitivity of a system, can be coupled with an antenna in a mobile handset. This paper presents a decoupling method for increasing the isolation between digital harmonics on a flexible printed circuit board (FPCB) and an antenna in terms of the ground mode current and the concept of reaction. We model the signal and ground lines in an FPCB as a loop circuit exciting a ground mode current and demonstrate a simple but efficient decoupling method for reducing the excited ground mode current.

L-BTC 공정에 의한 Cacao Nib Reaction과 Roasting의 특성

이신영,유승석,김관필,이만종,권익부,변유량 한국산업식품공학회 2001 산업 식품공학 Vol.5 No.1