• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.895-905
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• 2000

This study was performed to investigate the removal efficiencies of pollutants at various filtration rates and the quality of the filtered water along the depth of filter media during treatment of a BNR process effluent by a dual-media gravitational rapid filtration. The results of the experiments at filtration rates of 200, 300 and 400 m/day using the effluent of a pilot scale 4-stage BNR plant showed that turbidity of the filtered water was below 2.6 NTU, satisfying the Korean standard for water for reuse. Even though the SS removal efficiency deteriorated as the filtration rate increased, the average SS concentration of the filtered water was 1.3 mg/L at all filtration rates. Simultaneous biological nitrification and denitrification was observed with nitrification efficiencies of 17.4, 18.8 and 14.3%, and denitrification efficiencies of 32.3, 27.7 and 21.4% respectively at filtration rates of 200, 300 and 400 m/day. At the latter period of each filtration cycle, the effluent T-P concentration was higher than influent T-P concentration by 6.1 to 21.4% due to phosphorous release under DO-deficient condition.

• Journal of the Korea Organic Resources Recycling Association
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• v.15 no.3
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• pp.106-112
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• 2007

The purpose of this study is to derive the mixing ratio with stable heating value to be used as fuel and secondary fuel by mixing sewage sludge cake, tar, peat moss, and verify the combustion property of produced solid fuel and the applicability of RDF as alternative fuel. Tar shows the highest heating value with 7,000kcal/kg and the heating value of sewage sludge cake and peat moss ranges from 4,000 to 4,500kcal/kg. Also, the solid fuel with length 1.6cm, diameter 1.3cm and weight 2.3g was produced using the heating value of over 6,000kcal/kg and proper mixing ratio (sewage sludge cake: tar: peat moss) from 1 : 4 : 1 to 1 : 7 : 1. Upon the analysis of the RDF applicability of produced solid fuel, the exhaust gas analysis finds that the composition concentration of exhaust gas occurred according to the mixing ratio did not change significantly and the flame lasting time was found to be around 5 minutes, similar to the lasting time of the same mass (2.3g) of general anthracite burned. Therefore, it can be concluded that solid fuel produced in this study can be used as fuel and secondary fuel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.4
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• pp.589-609
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• 2017

This study carried out the density and energy dispersive X-ray spectroscopy and particle size analysis which are the physical characteristics of coal dust by collecting samples of coal dust in the five domestic mines to control the coal dust through ventilation in the workplace for coal mining in the country. This will contribute to a more comfortable working environment by understanding the physical characteristics of the coal dust which is derived from any hard coal produced domestically. In particular, the result of PSA analysis showed that the size of coal dust sample for this study ranged from $0.007{\sim}88.614{\mu}m$ were the particles less than $3.5{\mu}m$, the size range responsible for pneumoconiosis. To observe the flow of coal dust collected on the wind speed, the fallout of coal dust produced by the wind tunnel for the wind was measured and the particle size analysis of coal dust fallout was carried out. In addition, airborne dust is measured according to the mine velocity by using a multi-stage Anderson sampler in the mine where fine dust is generated in a large amount and the wind speed is found out to control the coal dust below $3.5{\mu}m$. In addition, natural ventilation pressure of A mine was calculated to prevent over design of the main fan.

• Journal of Korean Society of Forest Science
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• v.95 no.1
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• pp.60-72
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• 2006

The aim of this paper is to identify and evaluate relations for forest greening and the firewood substitution for home use after 1945 Liberation of Korea. Korea faced serious forest degradation by the early 1960s due to the enormous firewood consumption, which was about ten million cubic meters annually, for home use. If the trend of firewood consumption was maintained until 1955's, the total forest area in Korea could be thoroughly degraded within 10 years. The firewood substitution for home use had to be solved as soon as possible. For this purpose, energy sector by the Ministry of Commerce and Industry carried out the substitution policy for home using the briquettes which was the only natural resources for energy produced in Korea. Firewood was prohibited being carried in the major cities by forestry sector, the Ministry of Agriculture and Forestry, from 1958. Only 5.2% of household in the cities used the forest products consumed as a fuel in 1970 because these inter-sectoral substitution measures of firewood for home use turned out a success gradually. After the 1970s, firewood consumption for home use was naturally decreased due to rural people's explosive move to cities, who were major consumers of firewood for home use at that time. Firewood for cooking was substituted by LPG gas after 1985 and firewood for house heating was substituted by coal and oil after 1980. Finally, on the basis of the firewood substitution for home use, the forest degradation that lasted over one hundred years was put a period.

• Journal of Preventive Medicine and Public Health
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• v.16 no.1
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• pp.153-156
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• 1983

1950년(年) 이후(以後) 무연탄(無煙炭)으로 만든 연탄(煉炭)을 취사(炊事), 난방용(煖房用)으로 가정(家庭)에서 광범위(廣範圍)하게 사용(使用)하게 되면서 연탄(煉炭)가스내(內)의 일산화탄소(一酸化炭素)로 인(因)한 중독사고(中毒事故)가 빈발(頻發)하여 심각(深刻)한 국민보건(國民保健)의 문제(問題)가 되어왔다. 저자(著者)들의 실태조사(實態調査)(1975년도(年度))에 의(依)하면 서울특별시일원(特別市一圓)에 있어 일산화탄소중독(一酸化炭素中毒)의 년간발생(年間發生)은 인구(人口), 10만당(萬當) 경증(輕症) 260명(名), 혼수상태(昏睡狀態)의 중증중독(重症中毒) 45명(名), 사망(死亡) 1명(名)으로 위험인구(危險人口)를 3,000만명(萬名)으로 하였을 때 전국적(全國的)으로 일산화탄소중독(一酸化炭素中毒)의 추정발생수(推定發生數)는 년간(年間) 경증(輕症) 78만명(萬名), 중증(重症) 13만(萬) 5천명(千名), 사망(死亡) 3,000명(名)으로 그 피해(被害)의 규모(規模)가 100만을 육박(肉薄)하는 가공(可恐)할 수자(數字)를 보여주고 있다. 저자(著者)들은 이러한 심각(深刻)한 국민보건(國民保健)의 문제(問題)를 우선(于先) 실천가능(實踐可能)한 제이차예방(第二次豫防)에 역점(力點)을 두어 고압산소요법(高壓酸素療法)을 보급(普及)할 목적(目的)으로 일인용고압산소장치(一人用高壓酸素裝置)를 개발(開發)하고 1969년(年) 1월(月)에 서울대학교병원(大學校病院)에 고압산소치료실(高壓酸素治療室)을 개설(開設)하여 급성일산화탄소(急性一酸化炭素) 중독환자(中毒患者)에 대(對)한 응급치료(應急治療)를 실시(實施)하여 1978년(年)까지 10년간(年間)의 치료결과(治療結果)를 요약(要約)한바 다음과 같다. 1. 총치료환자수(總治療患者數)는 2,242명(名)이고 회복(回復)된 수(數)는 2,202명(名)으로 98.2%의 회복률(回復率)을 보였다. 2. 계절적(季節的)으로 10월(月)에서 4월(月)까지가 연중최성기(年中最盛期)이나 5월(月)에서 9월(月)까지도 적지않은 환자(患者)의 발생(發生)을 볼 수 있었다. 3. 연령별분포(年齡別分布)를 보면 15세(歲)${\sim}29$세군(歲群)이 전체환자(全體患者)의 반이상(半以上)인 52.7%를 차지하고 있고 $0{\sim}14$세군(歲群)은 인구비(人口比)에 대해 발생(發生)이 훨씬 적은 결과(結果)를 보이고 있다. 4. 도착시간별(到着時間別) 입원율(入院率)은 오전(午前) 10시이후(時以後) 도착군(到着群)서부터는 입원율(入院率)이 급증(急增)하는데 이는 병원도착(病院到着)이 늦일수록 당일회복(當日回復)이 되지못하고 입원가료(入院加療)하게 됨을 나타내주는 결과(結果)라 할 수 있다. 5. 병발증(倂發症)으로는 급성욕창, 폐렴(肺炎) 및 신경학적(神經學的) 이상등(異常等)의 소견(所見)을 많이 볼 수 있었다.

• Resources Recycling
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• v.30 no.1
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• pp.66-76
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• 2021

Electric arc furnace dust (EAFD) contains compounds, such as oxides and chlorides, including large quantities of Zn, Pb and Fe. An efficient and stable method for the extraction of metal elements from EAFD is the Rotary Kiln Process. This method is used to recover Zn in the form of crude ZnO (approximately 60%) via the addition of a reducing agent (coke, anthracite) and limestone (for basicity control) to EAFD. This process is commonly used in industry as well as in research and development. Currently, this method is used in many Korean commercial plants, producing approximately 150,000 tons of Crude ZnO per year. The majority of Zn is found in crude ZnO (approximately 76%). In addition components such as Pb, Cd, Sn, In, Fe, Cl, and F are present as oxides, chlorides, and alkaline compounds. This elements have an adverse effect on the zinc smelting process. Therefore, a refining process that eliminates these impurities is essential. In this study, we developed a process technology that efficiently separates Zn and Pb from byproducts (mainly chlorides). A bag filter was used to collect Zn and Pb generated during the dry purification process of crude ZnO. Pure components were recovered as metals or metal carbonate.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.1
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• pp.115-123
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• 1990

The purpose of this study was to examine the uses of coal ash as a type of construction material. The methods of examination were chemical anlysis, soil laboratory test and the soil vibration test. Materials used were coal ash obtained as a by-product from 5 thermal power plants in Yongdong, Yongwol, Sochon(anthracite coal) and in Samchonpo and Honam (bituminous coal). Over 70% of the coal ash consisted of silica and alumina. The fly ash grain size showed a uniform distribution from fine-sand to silt, and that of the bottom ash showed from sand to gravel. The specific gravity and density of the coal ash were low. The long term strength increased gradually due to the self-setting property resulting from pozzolanic activity. The shear strength was higher than that of general soil. Cohesion and optimum moisture content of anthracite coal ash were higher than bituminous coal ash, whereas the maximum dry density was higher in bituminous coal ash. The coal ash dynamic Young's modulous curve range was similar to that of general soil. Of the results from the soil vibration test by car-running, the size relative acceleration level in the ash pond was higher than that of natural ground, but the damping ratio was lower than that of natural ground near the ash pond. The coal ash has more advantageous engineering properties than general soil with particles of the same size. For example, the California Bearing Ratio of the bottom ash at both Yongdong and Yongwol was 77~137%. Therefore we expect that if further study is done, coal ash can be used as a construction material when reclaiming seashore, construction embankments, road construction, making right-weight aggregate, or as a general construction material.

• Resources Recycling
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• v.30 no.3
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• pp.47-54
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• 2021

Palladium present in colloidal-type plated spent catalyst solution that is used in electroless plating process has not been recovered but discharged as wastewater so far. Recyclig of paladium in colloidal-type plated spent catalyst solution is achieved with this study. This study presents the estimation of resource consumption and GHG emissions during the recycling and disposal of palladium in the plated spent catalyst solution using life cycle assessment. The reduction of resources and GHG are also estimated. Based on the palladium amount of 1 kg during disposal, the GHG emission amount was estimated to be 9.67E+03 kgCO₂eq., and the amount of resource consumption was 3.94E+01 kgSb-eq. However, GHG emission was 1.96E+03 kgCO₂eq., and the amount of resource consumption was 1.54E+01 kgSb-eq. during recycling. Considering the major substances affecting GHG emissions and amount of resource consumption, CO₂ was found to significantly affect GHG emissions, accounting for 91.42% in disposal and 98.37% in recycling. The major substance affecting the amount of resource consumption was hard coal, which accounted for 40.63% in disposal and 60.73% in recycling. Upon recycling 1 kg palladium, 8,967.17 kgCO₂eq. of greenhouse gas emission was reduced, while the resource consumption was reduced to 10.10 kg Sb-eq. In addition, the direct palladium resource reduction rate due to palladium recycling was 50%.

• Journal of the Korea Organic Resources Recycling Association
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• v.17 no.3
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• pp.27-39
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• 2009

The main objective of this study is to investigate the characteristics of combustion by analyzing fuel gases from a combustion equipment with various combustion conditions for refuse-derived fuels (RDFs). CO gas is a parameter for indicating of incomplete combustion during a combustion process. The lowest CO gas was produced when the experiment conditions were m=2 under air-fuel condition and $800^{\circ}C$. $CO_2$ gas is a final product after complete combustions. The highest amount of $CO_2$ gas was produced when the experiment conditions were m=2 under air-fuel condition and $800^{\circ}C$. The highest level of $SO_2$ gas was produced in S.1 sample containing the highest sulfur. The highest level of NOx gas was produced in S.1 sample with the highest nitrogen content and air-fuel condition of m=2 under temperature of $800^{\circ}C$. HCl gas that is generated by reacting with metals catalyst through oxygen catalyst reaction during combustion process is a precursor of dioxin formation. The higher level of HCl gas was produced in the sample with higher chlorine content. The lowest level of HCl gas was produced when the experiment conditions were air-fuel condition of m=2 and $800^{\circ}C$. The lowest level of $NH_3$ gas was generated when the experiment condition was m=2 under air-fuel condition and after 3 minutes. Air-fuel condition is more important to create $NH_3$ gas than operating temperatures. Higher level of $H_2S$ gas was generated in S.1 sample with the higher sulfur content and was created in RDFs that contain higher mixture ratios of sewage sludge and food wastes. A result of combustion, gases and gases levels from the combustion of S.1 and S.2 were very similar to the combustion of a stone coal. As results of this research, when evaluating the feasibility of the RDFs, the RDFs could be used as auxiliary and main fuels.