• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.7
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• pp.884-891
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• 2016

A secondary injection system in a diesel engine has benefits: it can be controlled independently without interrupting engine control, it can be adapted to various layouts for exhaust systems, and it pose no reductant dilution problems compared to post injection systems in the combustion chamber or other supplemental reductant injections. In a secondary injection system, the efficiency of the catalyst depends on the method of reducing the supply. The reductant needs to be maintained and optimized with constant pressure, the positions and angles of injector is a very important factor. The concentration and amount of reductant can be changed by adjusting secondary injection conditions. However, secondary injection is highly dependent upon the type of injector, injection pressure, atomization, spray technology, etc. Therefore, it is necessary to establish injection conditions the spray characteristics must be well-understood, such as spray penetration, sauter mean diameter, spray angle, injection quantity, etc. Uniform distribution of the reductant corresponding to the maximum NOx reduction in the DeNOx catalyst system must also assured. With this goal in mind, the spray characteristics and impingement plate types of a secondary injector were analyzed using visualization and digital image processing techniques.

• Clean Technology
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• v.14 no.2
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• pp.136-143
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• 2008

The objective of this study is to investigate the visibility of plume at the Y power plant stack, which fires the orimulsion as a fuel. The plume contains numerous primary particles under $1\;{\mu}m$ size and inorganic ions possibly inferred by the chemicals of secondary aerosol formation. We evaluated the visibility of the plume using the modified PLUVUE-II model. The monitoring data on the particle size distribution (PSD) and secondary aerosols of sulfate were applied to estimate and evaluate the main factors of plume opacity. The chemical reactions were applied to the model for the secondary aerosol formation of $(NH_4)_2SO_4(s)$. The maximum plume length was estimated by an optic method using threshold contrast. The results showed that the plume length was strongly dependent upon the PSD and $(NH_4)_2SO_4(s)$ concentration of the plume emitted from the stack.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.2
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• pp.170-176
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• 2005

This study was conducted to investigate the level of PCBs and distribution of PCB congeners in the ambient air of Korea and Japan. The source of PCBs were also studied by a statistical method. The TEQ concentration of PCB in the ambient air of Korea and Japan were between 0.003 and $1.01\;pgTEQ/m^3$(mean value : $0.22\;pgTEQ/m^3$) and between 0.002 and $0.014\;pgTEQ/m^3$ (mean value: $0.007\;pgTEQ/m^3$), respectively. The ambient air of industrial area of Korea showed a fluctuation in PCB concentration than other sampling area. The isomer distribution patterns in the ambient air was more or less similar in all sampling places. In addition, highly chlorinated homologues ($7{\sim}10CB$) were detected in the only Korea industrial area. This observation suggests that there is a possibility of specific source of PCBs in the industrial area. The source identification of PCB in ambient air was performed using multivariate statistical analysis(principal component analysis). As a result, it is estimated that the Korean ambient air was more influenced by combustion process than the ambient air of Japan and also the effect of PCB commercial products was relatively a small.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.2
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• pp.155-164
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• 2010

Emission from biomass combustion such as meat charbroiling is an important source of organic aerosol. Since source profiles are necessary input profiles for source apportionment of aerosol by a chemical mass balance model, meat cooking organic source profiles are developed by measuring organic marker compounds, including palmitic acid, stearic acid, oleic acid and cholesterol as well as PAH compounds. Emissions from meat and pork charbroiling are collected on quartz filters with a PM10-high volume sampler, extracted with organic solvents, derivatized with diazomethane/TMS and analyzed by GC/MS isotope dilution method. Organic and elemental carbon are also analyzed by an OCEC analyzer. Wt.% of cholesterol to the organic carbon(OC) content from beef and pork charbroiling is only 0.056 and 0.062, but wt. % of all saturated fatty acids to the OC content from beef and pork charbroiling is 2.727 and 2.022, and the wt% of all unsaturated fatty acids to the OC content is 0.278 and 0.438, respectively. Content of total PAH compounds to the OC content from beef charbroiling is higher than that from pork charbroiling, and those are 0.116 wt% and 0.044 wt%. Among PAH compounds benzo(a)pyrene as a single compound is account for 0.0071 wt% and 0.0023 wt% of OC content from beef and pork charbroiling. Ratios of marker compound to cholesterol are calculated, and those values are in good agreement with the values already reported at the food cooking emission, indicating that they can be used as organic source profiles for the apportionment of organic aerosol.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.7
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• pp.565-572
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• 2009

Greenhouse gas(GHG) inventories and basic strategies for Jeonbuk regional government were established to reduce greenhouse gas emissions. The method to construct GHG inventories of Jeonbuk followed the 'Revised IPCC 1996 Guidelines'which was used for the 'Third National Communication of the Republic of Korea under UNFCCC'. Korean government could use primary energy consumption for the energy industries section in the national GHG inventories. However, regional governments should use secondary energy consumption (included electricity consumption) for the energy industries section for their GHG inventories because they could not control the emission of energy transformation section. In the result of Jeonbuk GHG inventories in 2006, carbon dioxide($CO_2$) emissions from fuel combustion covered 87.1% of total emissions. Methane($CH_4$), carbon dioxide($CO_2$) from other sections, nitrous oxide($N_2O$) and F-gas(HFCs, PFCs, $SF_6$) accounted for 8.1, 2.2, 1.6 and 1.0% of total emissions, respectively. The sectional emission decreased in the order of the energy(88.0%), agriculture(7.6%), waste(2.3%) and industrial processes(2.1%) section. The energy industries section that contained electricity consumption was the most dominant emission source in the energy section. F-gas consumption, rice cultivation and waste incineration were main emission sources in the industrial processes, agriculture and waste section, respectively. In this study, basic directions of each section were established by the results of Jeonbuk GHG inventories in 2006.

• Journal of the Society of Disaster Information
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• v.15 no.4
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• pp.634-647
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• 2019

Purpose: Currently, many chemicals are used in industrial and real life, and many substances are used in the form of a single substance, but most of them are used in the form of a mixture, and there is a need for a criterion for judging the danger of these substances. Method: Therefore, this study aims to confirm the risk criteria of the mixture through experimental studies on flammable mixtures in order to secure the effectiveness of the details of the existing Dangerous Goods Safety Management Act angerous Goods Judgment Criteria and to ensure the reliability and reproducibility of the dangerous goods judgment. Result: Experimental results show that alcohol flash point is mixed with water, which is a non-flammable liquid. Similar flash point trends occurred around 60% on an alcohol basis. In addition, in the case of flammable-combustible mixtures, there was little change in flash point if the flash point difference of the two materials was not large, and if the flash point difference of the two materials was low, the flash point tended to increase with the increase of the high flash point material. Conclusion: In the future, the test results may provide reference data on the experimental criteria for the flammable liquids that are cracked at the fire site.

• Nuclear Engineering and Technology
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• v.27 no.4
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• pp.562-570
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• 1995

The recent ABB/CE(Asea Brown Boveri Combustion Engineering) type pressurized oater reactor-s have the on-line monitoring system, i.e., the COLSS(core operating limit supervisory system), to prevent the specified acceptable fuel design limits from being violated during normal operation and anticipated operational occurrences. One of the main functions of COLSS is the on-line monitoring of the DNB(departure from nucleate boiling) overpower margin by calculating the MDNBR(mini-mum DNB ratio) for the measured operating condition at every second. The CETOP-D model, used in the MDNBR calculation of COLSS, is benchmarked conservatively against the TORC mod-el using an inlet flow factor of hot assembly in CETOP-D as an adjustment factor for TORC. In this study, a technique to optimize the CETOP-D inlet flow factor has been developed by elim-inating the excessive conservatism in the ABB/CE's. A correlation is introduced to account for the actual variation of the CETOP-D inlet flow factor within the core operating limits. This technique was applied to the core operating range of the YongGwang Units 3&4 Cycle 1, which results in the increase of 2％ in the DNB overpower margin at the normal operating condition, compared with that from the ABB/CE method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1996.10a
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• pp.65-70
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• 1996

엔진소음을 소음특성에 따라 분류하면 공력소음(Aerodynamic Noise), 연소소음(Combustion Noise), 기계적인 소음(Mechanical Noise)으로 나눌 수 있으며 소음원의 종류에 따라 분류하면 배기계소음(Exhaust System Noise)으로 나눌 수 있으며 소음원의 종류에 따라 분류하면 배기계소음(Exhaust System Noise), 흡기계소음(Intake System Noise), 냉각계소음(Cooling System Noise), 엔진표면소음(Engine System Noise)등으로 분류할 수 있다. 이러한 여러소음중 엔진 내부의 유동에 의한 흡배기계통으로의 소음방출은 자동차 실 내외 소음의 중요한 문제로 대두되는데, 이를 줄이기 위해 그 동안 소음기 등의 서브시스템의 형태와 그 위치조정에 관한 연구가 수행되어 왔다. 그러나 이것이 비용 또는 성능에 영향을 미치므로 본질적인 소음원을 규명해 내는 것이 필요하게 되었다. 흡배기계의 소음은 엔진의 흡입, 배기행 정시 피스톤의 운동에 의해 팽창 및 압축파 형태의 압력파(pressure wave)로 발생하게 되고, 밸브근방에서는 유동의 박리(separation)에 의해 발생하게 된다. 소음기 등의 서브시스템에서도 유동의 박리에 의해 발생하게 되며 특히 배기행정시 발생하는 압력파는 비선형영역에 있게된다. 흡기소음은 배기에 비해 그 크기가 작아서 그동안 등한시 되어왔으나 이것이 소비자의 불평요인으로 작용하므로써 이에 대한 연구도 활발히 수행되어야 한다. Bender, Bramer[1]는 흡배기계 소음의 외부 방사에 관하여 전반적으로 기술하였고 Sierens등[2]은 흡기계에서 1차원 MOC(Method of Characteristics)방법으로 비정상 유동해석을 하고 실험결과와 비교하였다. J.S.Lamancusa 등[3]은 흡기 소음원을 실험을 통해 예측하였고, 흡기소음도 비선형 거동을 보인다고 밝혔다. Yositaka Nishio 등[4]은 새로운 흡기실험장치를 고안하여 공명기(resonator)의 위치 변화에 의한 저소음 흡기계를 설계 초기단계에서부터 적용하려 하였다. 일반적으로 흡배기계의 복잡한 형상 때문에 대부분 실험을 통해 문제를 해결하려 하였고, 수치해석은 피스톤의 운동을 배제한 단순화한 흡배기계의 정상상태 유동해석이 주를 이루어왔다. Taghaui and Dupont 등[5]은 KIVA코드를 사용하여 흡기포트와 연소실 그리고 밸브의 움직임을 동시에 고려한 수치해석을 도입하였다. 하지만 이들이 밸브의 운동을 고려하기 위해 사용한 이동격자는 격자점은 시간에 따라 변화하지만 그 격자의 수가 일정하게 유지되어 있어서 밸브의 완전개폐를 해석할 수가 없다. 강희정[6]은 단일 실린더와 단일 배기밸브를 갖는 문제로 단순화하여 피스톤과 밸브의 움직임을 고려하므로써 배기행정 후 소음이 어떻게 전파해 나가는가를 연구하였다. 본 연구에서도 최소밸브간격과 최대밸브간격 사이에서만 계산이 가능하나 흡기의 경우는 밸브가 닫힐 때 생기는 압력파가 중요하므로 실린더와 밸브사이에 벽면조건을 주어 밸브의 개폐를 모사하였다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.26 no.4
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• pp.614-619
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• 1997

To examine effects of drying methods on the formation of N-nitrosamine(NA) in squid during its drying. Three different types of dried products, which were made by sun, hot-air and traditional drying of squid after removal of intestines, were utilized. NA was analyzed by a gas chromatography-thermal energy analyzer. The contents of nitrate and nitrite nitrogen in dried products were in the range of 0 to 5.2mg/kg and 0 to 2.7mg/kg, respectively. The contents of TMAO and betain nitrogen in squid during its drying decreased, while those of TMA and DMA nitrogen increased. The contents in dried products were 27.8~29.2mg% and 10.4~12.3mg/kg, respectively. N-Nitrosodimethylamine (NDMA) was only detected in squid during its drying, recovery from raw sample and its dried pro- ducts spiked with 10$\mu\textrm{g}$/kg for NDPA was 81.0~ 100.0%. NDMA in raw samples was found to be below 0.05$\mu\textrm{g}$/kg. The levels of NDMA in squid increased remarkably during its drying and those in dried products were ranged from 2.7 to 42.7$\mu\textrm{g}$/kg. The effects of drying methods in squid were found to be quite different. the levels of NDMA in traditionally dried products were 11~16 and 3~4 times higher than those in sun dried and hot-air dried products, respectively It is believed that high levels of NDMA were detected in traditionally dried products because NDMA was formed from reaction between various amines and nitrogen oxide produced by combustion of briquet during drying of squid.

• Journal of Korea Society of Waste Management
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• v.35 no.7
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• pp.606-615
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• 2018

Over the past two decades, the options for solid waste management have been changing from land disposal to recycling, waste-to-energy, and incineration due to growing attention for resource and energy recovery. In addition, the reduction of greenhouse gas (GHG) emission has become an issue of concern in the waste sector because such gases often released into the atmosphere during the waste management processes (e.g., biodegradation in landfills and combustion by incineration) can contribute to climate change. In this study, the emission and reduction rates of GHGs by the municipal solid waste (MSW) management options in D city have been studied for the years 1996-2016. The emissions and reduction rates were calculated according to the Intergovernmental Panel on Climate Change guidelines and the EU Prognos method, respectively. A dramatic decrease in the waste landfilled was observed between 1996 and 2004, after which its amount has been relatively constant. Waste recycling and incineration have been increased over the decades, leading to a peak in the GHG emissions from landfills of approximately $63,323tCO_2\;eq/yr$ in 2005, while the lowest value of $35,962tCO_2\;eq/yr$ was observed in 2016. In 2016, the estimated emission rate of GHGs from incineration was $59,199tCO_2\;eq/yr$. The reduction rate by material recycling was the highest ($-164,487tCO_2\;eq/yr$) in 2016, followed by the rates by heat recovery with incineration ($-59,242tCO_2\;eq/yr$) and landfill gas recovery ($-23,922tCO_2\;eq/yr$). Moreover, the cumulative GHG reduction rate between 1996 and 2016 was $-3.46MtCO_2\;eq$, implying a very positive impact on future $CO_2$ reduction achieved by waste recycling as well as heat recovery of incineration and landfill gas recovery. This study clearly demonstrates that improved MSW management systems are positive for GHGs reduction and energy savings. These results could help the waste management decision-makers supporting the MSW recycling and energy recovery policies as well as the climate change mitigation efforts at local government level.