• 한국화재소방학회논문지
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• 제14권2호
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• pp.7-13
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• 2000

쿠션제조용; 마네킹 제조용 및 건축내장재용 폴리우레탄 봄의 열적특성을 조사하기 위하여 시차주사열량계(DSC, Differential Scanning Calorimeter) 및 열중량 분석기(TGA, Thermogravimetric Analysis)를 이용하여 온도에 따른 발열개시온도, 무게감량 등을 조사하였으며, 발화온도 측정방법 중 정온법을 이용하여 각 폴리우레탄 폼의 발화온도를 조사하였다. 이로부터 각 폴리우레탄 폼의 연소 조건에 따라 발생할 수 있는 유독성 가스를 가스분석기와 가스텍을 이용하여 조사하였다. 연구결과 시제품인 건축내장재용 폴리우레탄 폼의 분해개시온도가 다소 낮으며, 분해열이 매우 크게 나타났다. 발화온도는 $420^{\circ}$였다. 연소 시험시 $420^{\circ}$까지 무염연소의 형태를 가졌으며, $500^{\circ}$에서 유임연소가 발생하였다. 연소형태에 관계없이 연소온도의 증가에 따라 일산화탄소, 이산화탄소의 농도는 증가하였고, 유염연소를 나타내는 $500^{\circ}$에서 질소산화물이 10 ppm 이상 관찰되었다. 한편 유독성이 매우 강한 HCN의 경우 온도의 증가에 따라 크게 증가하였다.

• 대한기계학회논문집B
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• 제28권6호
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• pp.697-704
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• 2004

Bifurcation behavior of ignition and extinction of catalytic reaction is theoretically investigated in a stagnation-point flow. Considering that reaction takes place only on the catalytic surface, where conductive heat losses are allowed to occur, activation energy asymptotics with a overall one-step Arrhenius-type catalytic reaction is employed. For the cases with and without the limiting reactant consumption, the analysis provides explicit expressions, which indicate the possibility of multiple steady-state solution branches. The difference between the solutions with and without reactant consumption is in the existence of an upper solution branch, and the neglect of reactant consumption is inappropriate for determining extinction conditions. For larger values of reactant consumption, the solution response is all monotone, suggesting that multiple solutions are not possible. It is shown that bifurcation Damkohler numbers increase (decrease) with increasing of conductive heat loss (gain) on the catalytic surface, which means that smaller (larger) values of the strain rate allow the surface reaction to tolerate larger heat losses (gains). Lewis number of the limiting reactant can also significantly affect bifurcation behavior in a similar way to the effect of heat loss.

• 환경생물
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• 제18권2호
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• pp.227-235
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• 2000

As a part of basic investigation to Fishery Purge Project for the Special Administrative in Chollanamdo Province, the sedimentary environmental characteristics of Yoja Bay at 15 stations were studied. The analysis was carried out in July, 1998, through studies of Loss On Ignition (LOI) by depth, Total Sulfide (T-5), Chemical Oxygen Demand (COD) concentrations and Grain-size distribution. The LOI value was found to be 6.20-12.20% (mean of 8.89%), with the neighboring Sunhakri and Haksanri areas showing slightly higher values. These values were similar to the LOI values observed in the Hansan-Koje Bay and Jinju Bay areas on the southern coast of Korea. T-S and COD concentrations were found to be, respectively, 0.060-0.104 mg/gㆍd (mean of 0.052 mg/gㆍd) and 5.53-29.71 mg/gㆍd(mean of 13.24 mg/gㆍd), not exceeding eutrophication limits. T-S concentration was especially high at stations close to the central areas of the bay and inland areas, which caused by organic matter input from the nearby agricultural areas. COD concentration was very high at stations nearby the bay entrance and Doonbyungdo, but the mean value was lower than that of Hansan-Koje Bay. This leads us to believe that the level of pollution in Yoja Bay is not significant. The prevailing sediment composition was mud, consisting of 61.38% silt and 34.87% clay. [Sediments in Yoja Bay, Loss On Ignition, Total Sulfide, Chemical Oxygen Demand, Grain-Size Distribution].

• 대한토목학회논문집
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• 제7권3호
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• pp.213-221
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• 1987

국내의 각 공장에서 생산된 플라이애쉬 15종류를 수집하여 콘크리트용 혼화재료로 이용하기 위한 연구의 일환으로 화학성분, 물리적 성질을 조사하고 플라이애쉬 풀의 유동성을 측정하였다. 본 연구에서 국산 플라이애쉬의 화학성분은 한국공업규격의 규정을 만족하였으나 강열감량이 약간 크게 나타났다. 한편 물리적 성질 중 비표면적과 표준체의 잔류량 및 단위중량, 표준체의 잔류량과 강열감량과의 사이에서 상관성을 알아냈다. 그리고 시멘트 풀과 동일한 유동성 을 얻기 위한 플라이애쉬 풀의 물결합재비가 크게 요구됨을 알았다.

• 대한토목학회논문집
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• 제8권2호
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• pp.117-124
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• 1988

국산 플라이애쉬 6종류에 대한 AE제의 흡착특성(吸着特性)을 살펴 본 결과 플라이애쉬 입자의 AE제흡착(吸着)은 30분 정도에서 거의 완료되었으며 강열감량이 클수록 포화흡착량이 크게 나타났다. 플라이애쉬 강열감량의 대부분은 미연소탄소(未燃燒炭素)이며 따라서 미연소탄소량이 AE콘크리트 중의 공기량을 감소시키는 요인임을 알았다. 한편, 유동화제(流動化劑)의 경우 플라이애쉬 입자의 포화흡착량은 시멘트보다 적으며 시멘트의 경우보다 분산성(分散性)도 다소 낮으나 플라이애쉬를 혼합한 콘크리트에 유동화제를 사용할 경우 유동성이 저하되는 현상은 없었다.

• 환경영향평가
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• 제7권2호
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• pp.135-143
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• 1998

In order to study the general characteristics of reservoir and stream sediments, various analysis tests were conducted. Water contents and ignition loss were measured to know the primary sediment characteristics. The COD, total phosphorus and nitrogen were contained for the determination of organic substance content. For the purpose of establishing the contamination degree of heavy metals, some heavy metal contents were investigated. In heavy metal contents, reservoir sediments showed somewhat higer value than stream sediments. As a result, the reservoir sediment content of all analysis items were higher than stream sediment.

• 한국세라믹학회지
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• 제50권6호
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• pp.384-389
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• 2013

Activated alumina was fabricated with aluminum hydroxide in this study. High-purity alumina gel and boehmite were prepared from aluminum hydroxide by a hydrothermal process and fired to activate alumina having a surface area of 380 ~ 480 $m^2/g$ with less loss of ignition. The aging and drying condition during the fabrication process affected the loss of ignition, the sedimentation time of the alumina suspension, as well as the surface area of the activated alumina. For pellet-type activated alumina, the pre-fired alumina gel and boehmite were press-formed and fired at $400^{\circ}C$ and $550^{\circ}C$ for 6 h, respectively. The fired pellets showed a low density of 2.0 ~ 2.2 $g/cm^3$ with 20% firing shrinkage and sufficient handling strength. In this study, a new fabrication process for high-quality activated alumina with aluminum hydroxide is introduced. The effects of the processing parameters on the activated alumina properties are also examined.

• 한국입자에어로졸학회지
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• 제10권4호
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• pp.131-136
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• 2014

The importance of waste treatments is increasing because of the lack of resources and environmental problems resulted from economic growth policy. Especially, the pollutant dust which is one of the wastes should be treated considerately because it could cause secondary damages on the human health as well as environmental systems. Recently, massive amount of coal fly-ash is being produced in thermoelectric power plants. In this study, we compared two general methods used in estimating the amount of unburned carbon in fly-ashes to categorize the coal fly-ashes into several groups following their carbon contents. One is the "loss on ignition(KS L 5405) method" which estimates the change of mass after combustion, and it is generally used. Another one is measuring $CO_2$ gas content by burning solid carbon in the fly-ash, and it is called "$CO_2$ analysis method."

• Nuclear Engineering and Technology
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• 제54권8호
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• pp.2960-2973
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• 2022

Since Fukushima nuclear power plant (NPP) accident in 2011, the importance of research on various severe accident phenomena has been emphasized. Particularly, detailed analysis of combustion risk is necessary following the containment damage caused by combustion in the Fukushima accident. Many studies have been conducted to evaluate the risk of local hydrogen concentration increases and flame propagation using computational code. In particular, the potential for combustion by local hydrogen concentration in specific areas within the containment has been emphasized. In this study, the process of flame propagation generated inside a reactor core to containment during a loss of coolant accident (LOCA) was analyzed using MELCOR 2.1 code. Later in the LOCA scenario, it was expected that hydrogen combustion occurred inside the reactor core owing to oxygen inflow through the cold leg break area. The main driving force of the oxygen intrusion is the elevated containment pressure due to the molten corium-concrete interaction. The thermal and mechanical loads caused by the flame threaten the integrity of the containment. Additionally, the containment spray system effectiveness in this situation was evaluated because changes in pressure gradient and concentrations of flammable gases greatly affect the overall behavior of ignition and subsequent containment integrity.

• 한국가스학회지
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• 제2권4호
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• pp.79-84
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• 1998

본 논문은 고주파 발생장치와 IEC형 불꽃점화 시험장치를 이용하여 라디오 주파수 범위내에서 발생하는 개폐불꽃에 의한 LPG-Air 5.25[Vol$\%$]의 혼합가스에 대한 최소점화한계전압을 구하였다. 그 결과 LPG-Air 혼합가스는 주파수가 높을수록 최소점화한계전압도 높아졌으며, 특히 3[KHz]에서 10[KHz]사이에서 현저히 증가함을 알 수 있었다. 이는 3[KHz]까지는 1회의 방전에너지에 의해 점화가 발생되지만 3[KHz]이상에서는 2회 이상의 방전에너지가 누적되어 점화가 일어남을 알 수 있었고 그 이유는 방전과 방전간의 휴지기간이 존재하므로써 생기는 에너지의 손실이 그 원인으로 생각된다. 본 연구결과는 가스가 존재하는 위험장소에서도 안전하게 사용될 수 있는 통신장비나 각종탐지기 등에 응용될 수 있는 본질안전 방폭형 고주파 전기기기의 연구개발을 위한 기본자료로서 뿐만 아니라 이들 장비의 방폭성능에 대한 시험자료로도 활용가능할 것으로 사료된다.