• 한국자동차공학회논문집
• /
• 제10권6호
• /
• pp.59-64
• /
• 2002

The effects of EGR on emissions were investigated by using a six-cylinder, 8 litre, turbo-charged, heavy-duty diesel engine with a low pressure route EGR system. The experiments were performed at various engine loads while the EGR rates were set from 0% to 30%. Hot and cooled EGR are achieved without cooling and with cooling respectively. To verify the possibility of EGR technology for the applications, test were performed with steady state test cycle. It was found that the exhaust emissions with the EGR system resulted in a very large reduction in oxides of nitrogen at the expense of higher smoke and PM emissions. Increasing the EGR rate leads to deteriorating specific fuel consumption and power at lower speed and higher load. Also, the reduction rates of NOx emissions for hot and cooled EGR are similar.

• 한국자동차공학회논문집
• /
• 제14권2호
• /
• pp.194-201
• /
• 2006

Roof-fairing and deflector system have been used on heavy-duty trucks to minimize aerodynamic drag force not only for driving stability of the truck but also for energy saving by reducing the required driving power of the vehicle. In this study, a numerical simulation was carried out to see aerodynamic effect of the drag reducing device on the model vehicle. Drag and lift force generated on the five different models of the drag reducing system were calculated and compared them each other to see which type of device is efficient on the reduction of driving power of the vehicles quantitatively. An experiment has been done to see airflow characteristics on the model vehicles. Airflow patterns around the model vehicles were visualized by smoke generation method to compare the complexity of airflow around drag reducing device. From the results, the deflector systems(Model 5,6) were revealed as a better device for reduction of aerodynamic drag than the roof-fairing systems(Model 2,3,4) on the heavy-duty truck and it can be expected that over 10% of brake power of an engine can be saved on a tractor-trailer by the aerodynamic drag reducing device at normal speed range($80km/h{\sim}$).

• 한국분무공학회지
• /
• 제29권2호
• /
• pp.53-59
• /
• 2024

Cars are one of the main causes of air pollution in large cities, and 34.6% of domestic air pollution emissions come from mobile sources, of which cars account for 69.6%. In particular, the importance of nitrogen oxides (NOx) and particulate matter (PM), which are major pollutants in diesel vehicles, is increasing due to their high contribution to emissions. Therefore, in this study, the problem of natural regeneration caused by low exhaust gas temperature during low speed and low load operation was solved by applying a complex regeneration DPF that is not affected by temperature conditions to large diesel vehicles with higher driving time and engine displacement than small and medium-sized vehicles. And the feasibility of application to large diesel vehicles was reviewed by measuring the emission reduction efficiency. As a result of the reduction efficiency test on the actual vehicle durability product, PM showed a reduction efficiency of 84% to 86%, and the reduction efficiency of gaseous substances showed a high reduction efficiency of over 90%. The actual vehicle applicability test was completed with three driving patterns: village bus vehicle, police car, and road-going construction equipment vehicle, and no device problems occurred until the end of the test. Both load and no-load smoke measurement results showed a smoke reduction efficiency of over 96%.

• 한국토양비료학회지
• /
• 제18권4호
• /
• pp.336-347
• /
• 1985

장항제련소(長項製鍊所)의 배연(排煙)에 영향(影響)을 받는 지역(地域)의 토양(土壤)과 수도(水稻)를 대상(對象)으로 Cd, Cu, Pb 및 Zn등 중금속함량(重金屬含量)을 조사분석(調査分析)한 결과(結果)를 요약(要約)하면 다음과 같다. 1. 제연소(製鍊所)의 배기(排氣)에 의(依)한 오염(汚染)은 동(東)쪽 방향(方向)에서 가장 심(甚)하였고 Pb의 천연부존량(天然賦存量)을 기준(基準)으로 하였을 때 오염거리(汚染距離)는 5km이었으며 표토(表土)에 많이 축적(蓄積)되고 있었다. 2. 토양중(土壤中) 중금속전함량(重金屬全含量)에 대(對)한 0.1N-HCl 및 $N-NH_4Ac$에 의한 용출율(溶出率)은 표토(表土)에서 고도(高度)의 유의성(有意性)있는 상관(相關)을 나타냈다. 3. 토양중(土壤中) 유기물함량(有機物含量) 및 양(陽)ion치환용량(置換容量)과 중금속전함량간(重金屬全含量間)에는 유의성(有意性)있는 상관(相關)을 나타냈다. 4. 제연소주변(製鍊所周邊) 토양(土壤)에서 생산(生産)된 현미중(玄米中)의 중금속함량(重金屬含量)은 Cd가 0.23~1.33, Cu은 2.39~6.25, Pb은 0.95~8.32, Zn은 14.60~27.31ppm이었다. 5. 지상부(地上部) 식물체중(植物體中)의 Cd, Cu 및 Zn의 함량(含量)은 현미중(玄米中) 이들의 함량(含量)과 유의성(有意性) 있는 정(正)의 상관(相關)을 나타내었다. 6. 현미중(玄米中) Cd, Cu, Pb 및 Zn의 함량(含量)은 오염원(汚染源)으로부터 멀리 떨어질수록 감소(減少)하였다.

• 한국직업건강간호학회지
• /
• 제28권3호
• /
• pp.156-165
• /
• 2019

Purpose: The purpose of this study was to compare working condition and health status between parcel delivery workers (PDW) and food delivery workers (FDW) and to examine the factors influencing their health status. Methods: This was a secondary analysis of data collected from the fifth Korean Working Conditions Survey (KWCS). Based on existing literature, a set of variables was chosen from the KWCS. Results: The proportion of PDW who carryied/moved heavy loads and experienced high job stress and lack of rest time was significantly higher than that of FDW. However, more FDW than their counterparts worked atypical hours. The differences in fatigue and well-being between PDW and FDW were not statistically significant. The multiple logistic regression analysis revealed low temperature, tobacco smoke, standing for long periods, and job stress were significant predictors of fatigue or well-being of FDW. Among PDW, noise, tobacco smoke, sitting for long periods, quantitative demands, hiding emotions, support from colleagues, job stress, no recovery period, and night work were significant predictors of fatigue or well-being. Conclusion: The findings of this study may be useful in developing nursing interventions for disease protection health promotion of delivery workers.

• Applied Biological Chemistry
• /
• 제40권4호
• /
• pp.342-346
• /
• 1997

전라북도 군산시 연안에 위치한 공업단지의 여러 제조업체에서 배출되는 매연, 분진의 영향으로 토양오염이 우려되는 지점을 선정하여 논 토양과 현미 중 중금속함량 및 오염원들과 현미 중 중금속함량간의 상관관계를 조사하였다. 공업단지 인근 지역 논 토양 중 전중금속 평균함량은 Pb 34.33, Cd 0.50, Cu 35.49, Zn 71.67 mg/kg이었으며 제조업체별, 거리별 논 토양 중금속의 분포상태를 조사한 결과 제조업체별, 거리별로 중금속함량이 일정한 경향을 보이지 않았다. 현미 중 중금속 함량은 Pb 1.74, Cd 0.07, Cu 3.54, Zn 16.53 mg/kg이었다. 군산 공업단지 인근 논 토양중 0.1N-HCl 가용성 중금속함량과 현미 중 중금속함량과의 상관관계를 보면 Pb가 1% 유의수준에서 정의 상관율$(r=0.6853^{**})$, Zn이 5% 유의수준에서 정의 상관$(r=0.5420^*)$을 보였으며, 토양 중 전 중금속함량과 수도체 현미 중 중금속함량과의 상관관계를 보면 Pb만이 1% 유의수준에서 정의 상관$(r=0.7131^{**})$을 보였다. 군산 공업단지 인근 논토양과 현미 중 중금속 함량은 공업단지에서 배출되는 매연이나 분진 중에 함유되어 있는 중금속 오염물질의 영향을 받아 부분적으로 오염이 진행되고 있으나 아직 오염을 우려할 수준에까지 이르지는 않았다.

• 한국가시화정보학회지
• /
• 제13권1호
• /
• pp.9-14
• /
• 2015

There have been many attempts to reduce the cost of transportation. Especially, drag reduction of heavy vehicles has enormous influence on energy saving by reducing the driving power of the vehicles. In this study, the effects of drag-reducing additive devices such as side skirt, boat tail and cab-roof fairing on the drag reduction of a 5 ton truck model were experimentally investigated. The aerodynamic performance of these flow-control devices attached to heavy vehicle was evaluated through wind tunnel test. In addition, flow patterns around the truck model were visualized by using smoke tube method. The drag coefficient is reduced by up to 5.7%, 7.16% and 22.2% by the side skirt, boat tail and cab-roof fairing, respectively. The interactive effect of the side skirt and boat tail was also investigated.

• 한국응용과학기술학회지
• /
• 제35권4호
• /
• pp.1421-1432
• /
• 2018

본 연구에서는 바이오매스로서 코코넛 폐기물을 $600^{\circ}C$에서 열분해하여 생성된 수상오일(water soluble oil)을 얻었다. 선박유로 사용되는 MDO(Marine Diesel Oil)와 바이오매스로서 코코넛 폐기물을 열분해하여 생성된 수상오일을 MDO에 15~20% 까지 혼합 후 유화시켜 제조된 바이오에멀젼 연료의 연소 특성에 대하여 연구 하였다. 엔진 배출가스 및 온도, 출력을 측정하기 위하여 엔진 다이나모메터를 사용하였다. 바이오에멀젼 연료는 수분이 함유되어 있어서 연소실내의 기화잠열을 빼앗아가 배출가스의 온도를 낮춰주는 것으로 나타났다. 바이오에멀젼 연료에 함유된 수분이 연소실내에서 미세폭발을 일으켜 연료를 잘게 쪼개어 주어 매연을 감소시키는 것으로 나타났다. 바이오에멀젼 연료의 사용으로 연소실내의 온도 감소는 질소산화물 배출을 저감하는 것으로 나타났다. 바이오오일 함유량이 증가 하면 수분함량도 증가하여 전체 발열량이 줄어들게 된다. 따라서 출력이 바이오에멀젼 연료 사용량에 비례하여 감소하는 특성을 나타내었다. 선박용 연료로 사용되는 중질유는 매연과 질소산화물을 많이 배출한다. 선박용 연료로 바이오에멀젼 연료를 사용하면 매연과 질소산화물 배출을 줄여줄 수 있을 것으로 기대된다.

• 한국대기환경학회지
• /
• 제20권5호
• /
• pp.697-711
• /
• 2004

Severe haze, mist, and fog phenomena occurred in the central part of Korea during 15~25 May 2003 resulted in poor visibility and air quality. When these phenomena occurred, Korean peninsula was under the effects of anticyclone. The atmosphere was stable, and wind speed was so weak. Under this meteorological conditions, air quality was worse and worse. The characteristics of aerosol in Seoul, Incheon, and Gosan (Jeju) during this period are investigated from the $PM_{10}$. TSP concentrations and aerosol number concentrations. Concentrations of $PM_{10}$ and TSP measured at KMA increased upto 176 and 230 J.${\mu}g/m^3$ on 22 May 2003, respectively. Aerosol number concentrations of size range from 0.82 to 6.06 ${\mu}m$ increased in Seoul on 17, 19, and 21~24 May 2003, and the concentrations of $NO_2$ and $SO_2$had maximum value of 0.165 ppm at Gwanak Mt. and 0.036 ppm at Guro-dong on 23 May 2003, respectively. Result from analysis on heavy metal elements showed high concentrations of Zn, Pb, Cr, Ni, Cu, and Cd during 20~24 May 2003. This event is examined by comprehensive analyses of synoptic weather conditions, satellite images, concentrations of suspended particles and air pollutants, and heavy metal elements.

• 대한지역사회영양학회지
• /
• 제2권1호
• /
• pp.44-51
• /
• 1997

Secrum lipid and vitamin E levels were determined and smoking, alcohol drinking and exercise habits were asked in 357 healthy male subjects aged 49.4$\pm$6.7 years in Taegu. Average serum levels of total cholesterol, HDL-cholesterol and triglyceride(TG) were 189$\pm$43mg/이, 42$\pm$13mg/dl and 136$\pm$73mg/이, respectively. Serum level of lipid peroxide measured as thiobarbituric acid reactive substances(TBARS) of the subjects was 2.01$\pm$0.73MDA nmoles/ml and that of $\alpha$-tocopherol was 9.53$\pm$3.14ug/ml. The correlation coefficients between $\alpha$-tocopherol and serum lipids were 0.3631 for triglyceride, 0.2993 for cholesterol, and 0.3025 for total lipid. Heavy smokers who smoked more than 20 cigarettes a day had higher levels of TG and TBARS than those who smoke less. Alcohol drinkers had higher levels of TG and TBARS than nondrinkers. Vitamin E level(per ml serum)was significantly higher in the heavy smokers and drinkers, which was reflected by the higher level of serum lipid. When the level of $\alpha$-tocopherol was expressed as $\alpha$-tocopherol/triglyceride, it was negatively correlated with serum TBARS level and was lower in the heavy smokers than in the moderate smokers. It is concluded that vitamin E level as $\alpha$-tocopherol/triglyceride would be better compared to $\alpha$-tocopherol/total cholesterol or $\alpha$-tocopherol/total lipid for the evaluation of vitamin E status in Korean men.