• Transactions on Electrical and Electronic Materials
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• 제3권3호
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• pp.34-38
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• 2002

In this paper, efficiency estimation of toxicity fee fire resistance cable experiments was measured smoke density of toxicity free fire resistance polyolefin insulation material and electric field dependence of tree shape in low density polyethylene (LDPE). One of the most serious causes of failure in high-voltage cables, can be an electrical discharge across an internal gab or void in the insulating material. Treeing due to partial discharge is one of the main causes of breakdown in the insulating materials and reduction of the insulation life. Therefore the necessity for establishing a method to diagnose the aging of insulation materials and to predict the breakdown of insulation and research of the fire resistance character has become important. First, we have studied on electric field dependence of tree shape in LDPE about treeing phenomena occurring on the high electrical field. Second, the measurement method is the attenuation quantity of irradiation by smoke accumulating with in a closed chamber due to non-flaming heat decomposition and flaming combustion. A main cause of fire-growth and generating toxic gas when, it bums, should be dealt with great care in life. safety design. The fire gases were occurred carbon monoxide and decomposition than in polyolefin due to incomplete combustion of PVC, which has high content of carbon in chemical compound.

• 공업화학
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• 제32권4호
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• pp.483-486
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• 2021

Catalytic ozonation of methyl ethyl ketone (MEK) has been examined over mesoporous MnO_x/Al₂O₃ (MA) catalysts developed by a solvent deficient method using two different manganese precursors including manganese chloride (C) and manganese sulfate (S) at room temperature. The maximum catalytic activities of MA with C (MEK removal efficiency and ozone decomposition of 98.4 and 93.7%, respectively) were higher than those of MA with S (MEK removal efficiency and ozone decomposition of 96 and 68%, respectively). Also the catalytic stability of MA with C was much higher than that of MA with S. The physico-chemical properties of catalysts are well correlated with the activity results, which confirmed that fine dispersion of MnO_x species with high ratios of Mn³⁺/Mn⁴⁺ and more acid sites are attributed to the higher catalyst stability for the MA-C catalyst.

• 한국분무공학회지
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• 제27권1호
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• pp.11-17
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• 2022

In upcoming Post Stage-V and Tier 5 regulations of construction machineries, nitrogen oxide (NOx) emissions are strictly limited in cold start conditions. In response to this, a method of improving NOx conversion efficiency has been applied by installing an electric heating catalyst (EHC) in front of conventional urea-SCR systems so that the evaporation and thermal decomposition of urea-water solution can be promoted in cold start conditions. In this strategy, the evaporation and thermal decomposition of urea-water solution and corresponding NOx conversion efficiency are governed by temperature conditions inside the EHC. Therefore, characterizing the temperature distribution in the EHC under various operating conditions is crucial for the optimized operation and control of the EHC in Urea-SCR systems. In this study, a 1-D modeling analysis was performed to predict the heater surface temperature distribution in EHC under various operating conditions. The reliability of prediction results was verified by comparing them with measurement results obtained using an infrared (IR) camera. Based on 1-D analysis results, the effects of various EHC operation parameters on the heater surface temperature distribution were analyzed and discussed.

• 자원리싸이클링
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• 제29권1호
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• pp.17-24
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• 2020

침철석을 주요 맥석광물로 하는 난용성 자원으로부터 희토류를 회수하기 위해 화학적 분해-산 침출의 2단계 방법을 이용한 맥석광물 분해 및 희토류 침출율 향상 연구를 수행하였다. 화학적 분해에는 알칼리인 NaOH를 사용하였으며 NaOH 용액 농도 20-50 wt%, 광액 농도 10% (w/w), 온도는 각 농도에서 NaOH 용액이 끓지 않는 최대 온도로 하여 분해 반응을 진행하였다. NaOH 농도가 높아질수록 경희토류 (Ce, La, Nd) 와 철은 고체상의 분해 산물 내에 농축되는 경향을 나타냈으며, 알루미늄과 인은 용액상으로 제거되어 50 wt% NaOH로 분해 시 고체상에 각각 0.96%, 0.17% 만이 잔류하는 것으로 나타났다. 또한, 주요 맥석광물인 침철석의 결정성이 분해 과정 후 감소하는 것으로 분석되었다. 50 wt% NaOH 분해 산물을 3.0 M 염산, 80 ℃ 조건에서 3시간 동안 침출했을 때, 94% 이상의 희토류 침출율을 달성하였으며 (Ce 80%), 불순물 중 알루미늄 침출율이 12%, 인 침출율이 0%로 감소하여 본 광석에 대한 최적 분해 및 침출 조건으로 선정하였다. 본 실험 결과로부터 희토류와 철의 침출율 간에 양의 상관관계가 있는 것으로 분석되었으며, 따라서 침철석의 결정성 감소가 희토류 침출율 향상에 기여한다고 할 수 있다.

• 공업화학
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• 제29권5호
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• pp.541-548
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• 2018

본 연구에서는 $N_2O$를 제거하기 위한 $N_2O$ 분해 촉매와 반응특성에 대한 연구를 수행하고자 한다. 다양한 지지체에 Rh를 활성금속으로 촉매를 제조하여 실험을 수행하였으며, $CeO_2$를 지지체로 하는 $Rh/CeO_2$ 촉매에서 가장 우수한 $N_2O$ 분해활성을 나타내었다. 특히 일정한 소성조건($500^{\circ}C$-4 hr)에서 $Rh/CeO_2$ 촉매를 제조하였을 때 가장 우수한 활성을 나타내었다. 또한 촉매의 특성이 $N_2O$ 분해 반응에 미치는 영향을 확인하고자 $H_2-TPR$ 및 XPS 분석을 수행하였다. 실험결과, 촉매의 redox 특성증진과 $Ce^{3+}$의 비율이 증가함에 따른 촉매의 산소전달능력의 증진이 $N_2O$ 분해반응에 영향을 주는 것으로 확인되었다. 또한, $N_2O$와 NO가 동시에 발생하는 조건에서 $N_2O$ 분해 반응특성과, $N_2O$와 NO를 동시에 처리 가능한 공정에 대하여 연구하고자 한다.

• 한국환경보건학회지
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• 제23권1호
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• pp.74-80
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• 1997

This study was performed to estimate the ozonation characteristics of phenol wastewater with increasing pH in the continuous packed column reactor (PCR) and the bubble column reactor (BCR). Among various influencing factors that affect phenol on decomposition through the ozonation, pH was chosen as reaction parameter. Upon increasing pH from 3 to 9, the phenol removal efficiency in PCR was improved approximately by 17% while in BCR approximately by 19.2%. The improvements in the phenol removal efficiency by increasing pH caused the enhancements in ozone utilization efficiency reaching almost 100% in PCR at pH 9. In conclusions, ozone has latent power for phenol wastewater treatment, and the performance of PCR was superior to that of BCR in the aspects of phenol removal and ozone utilization efficiency.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 춘계 학술대회논문집
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• pp.123-127
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• 2005

The numerical analyses of the complicated flows are widely attempted in these days. Because of the enormous demanding memory and calculation time, parallel processing is used for these problems. In order to obtain calculation efficiency, it is important to choose proper domain decomposition technique and numerical algorithm. In this research we enhanced the efficiency of the CFDS code developed by ADD, using parallel computation and newly developed numerical algorithms. For the huge amount of data transfer between blocks non-blocking method is used, and newly developed data transfer algorithm is used for non-aligned block interface. Recently developed RoeM scheme is adpoted as a spatial difference method, and AF-ADI and LU-SGS methods are used as a time integration method to enhance the convergence of the code. Analyses of the flows around the ONERA M6 wing and the high angle of attack missile configuration are performed to show the efficiency improvement.

• 한국태양에너지학회 논문집
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• 제32권6호
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• pp.29-36
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• 2012

The existing solar tracking sensor for 2 axial control system to trace latitude and longitude is made of four phototransistor. The phototransistor-making is difficult and it's manufacturing is more high-priced than a wide use phototransistor because they have to the same characteristics of each phototransistor output signal. This paper described the algorithm for supplement these weakness. The algorithm applied to signal normalizing method and vector decomposition law. The deviations of each a wide use phototransistor output signal are resolved by signal normalizing method and it is able to make a solar tracking sensor using three phototransistor by vector decomposition law. Therefore, in this paper, it is reduced the number of phototransistor that is composed of solar tracking sensor and possible to use a wide use phototransistor by the proposed algorithm.

• 경영과학
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• 제32권1호
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• pp.49-63
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• 2015

This paper investigates an aircraft-target assignment problem in consideration of deconfliction. The aircraft-target assignment problem is the problem to assign available aircrafts and weapons to targets that should be attacked, where the objective function is to minimize the total expected damage of aircrafts. Deconfliction is the way of dividing airspaces for aircraft flight to ensure the safety while performing the mission. In this paper, mixed integer programming model is suggested, where it considers deconfliction between aircrafts. However, the suggested MIP model is non-linear and limited to get solution for large size problem. The 2-phase decomposition model is suggested for efficiency and computation, where in the first phase target area is divided into sectors for deconfliction and in the second phase aircrafts and weapons are assigned to given targets for minimizing expected damage of aircraft. The proposed decomposition model shows outperforms the model developed for comparison in the computational experiment.

• 한국대기환경학회지
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• 제29권3호
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• pp.287-296
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• 2013

To decompose carbon dioxide, which is a representative greenhouse gas, a plasma torch was designed and manufactured. To examine the characteristics of carbon dioxide decomposition via plasma discharge, a case wherein pure carbon dioxide was supplied and a case wherein methane and/or $TiCl_4$ were injected as additives were investigated and compared. The carbon dioxide and methane conversion rate, energy decomposition efficiency, produced gas concentration, carbon monoxide and hydrogen selectivity, carbon-black and $TiO_2$ were also investigated. The maximum carbon dioxide conversion rate was 28.9% when pure carbon dioxide was supplied; 44.6% when $TiCl_4$ was injected as am additive; and 100% percent when methane was injected as an additive. Therefore, this could be explained that the methane injection showed the highest carbon dioxide decomposition. Furthermore, the carbon-black and $TiO_2$ were compared with each commercial materials through XRD and SEM. It was found that the carbon-black that was produced in this study is similar for commercial materials. It was found that the $TiO_2$ that was produced in this study is suitable for photocatalyst and pigment because it has mixed anataze and rutile.