• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.1
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• pp.585-591
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• 2017

Turbocharging is widely used in diesel and gasoline engines as an effective way to reduce fuel consumption. But turbochargers have turbo-lag due to mechanical friction losses. Bearing friction losses are a major cause of mechanical friction losses and are particularly intensified in the lower speed range of the engine. Current turbochargers mostly use oil bearings (two journal bearings and one thrust bearing). In this study, we focus on the bearing friction in the lower speed range. Experimental equipment was made using a drive motor, load cell, magnetic coupling, and oil control system. We measured the friction losses of the turbocharger while considering the influence of the rotation speed, oil temperature, and pressure. The friction power losses increased exponentially when the turbocharger speed increased.

• Asian-Australasian Journal of Animal Sciences
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• v.13 no.7
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• pp.948-956
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• 2000

The effect of high and low level of feed intakes on nutrient digestibility, nutrient losses through methane, energy and protein utilization by goats fed on alfalfa (Medicago sativa L.) pellets based diets was investigated in this study. Twelve castrated Japanese goats were employed in two subsequent digestion and metabolism trials. The goats were divided into three groups, offered three diets. Diet 1 consisted of 100% alfalfa pellet, Diet 2 was 70% alfalfa pellet and 30% corn, and Diet 3 was 40% alfalfa pellet and 60% corn. The two intake levels were high (1.6 times) and low (0.9 times) the maintenance requirement of total digestible nutrients (TON). Rumen ammonia nitrogen ($NH_3$-N) level of Diet 1 was lower (p<0.001) compared to Diets 2 and 3, but the values were always above the critical level (I50 mg/liter), The pH values of rumen liquor ranged from 6.02 to 7.30. Apparent digestibility of nutrient components did not show differences (p>0.05) between the two intake levels but inclusion of corn significantly altered the nutrient digestibility. Diet 3 had highest (p<0.001) dry matter (DM), organic matter (OM), ether extract (EE) and nitrogen fee extract (NFE) digestibility followed by the Diet 2 and Diet 1. The crude protein (CP) digestibility values among the three diets were in a narrow range (70.1 to 70.8%). Crude fiber (CF) digestibility for Diet 3 was slight higher (p>0.05) than that for other two diets. When alfalfa was replaced by corn, there were highly significant (p<0.001) increases in DM, OM, EE and NFE apparent digestibility and a slight increase in the CF digestibility (p>0.05). There were no differences (p>0.05) in energy losses as methane ($CH_4$) and heat production among the diets but energy loss through urine was higher for the Diet 1. The total energy loss as $CH_4$ and heat production were higher for the high intake level but the energy loss as $CH_4$ per gram DM intake were same (0.305 kcal/g) between the high and low intake level. Retained energy (RE) was higher for Diet 3 and Diet 2. Nitrogen (N) losses through feces and urine were higher (p<0.001) for Diet 1. Consequently, N retention was lower (p>0.05) for Diet 1 and higher in Diets 3 and 2. It is concluded that inclusion of corn with alfalfa increased the metabolizable energy (ME) and RE, and retained N through reducing the energy and N losses. The high level of intake reduced the rate of nutrient losses through feces and urine.

• Asian-Australasian Journal of Animal Sciences
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• v.14 no.12
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• pp.1701-1704
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• 2001

The evaluation of structural carbohydrate losses and its effect on silages digestibility in alfalfa (Medicago sativa L.) and orchardgrass (Dactylis glomerata L.) was studied during 5, 21 and 56 days ensiling. About 70 and 60 kg fresh matter of the two forages were ensiled in 9 silos of 120 L capacity. The digestion trials were conducted in two phases using the two grasses in two $4{\times}4$ Latin square design according to the four treatments being the grass and the three silages. There were no differences in the DM and CP contents resulting from 5 to 56 days ensiling in both forages. The water-soluble carbohydrates (WSC), hemicelllose, pectin, and energy were slightly reduced and appeared lower in 56 days silage. The ether extract and cellulose contents slightly increased as the ensiling process advanced in the two species. Hemicellulose losses of 29 and 41 g/kg DM were obtained in alfalfa and orchardgrass, respectively, 56 days after ensiling. While the cellulose losses in both species were very little, compared to that for hemicellulose, the pectin losses, 56 days after ensiling were 15 and 12 g/kg DM in alfalfa and orchardgras respectively. The total structural carbohydrates lost (ie., hemicellulose + cellulose + pectin) in g/kg DM of fresh material forage ensiled, is about four fifths the amount lost by WSC, in alfalfa and about two thirds, in orchardgrass, by 21 days ensiling after the activity of microorganism terminated, indicating that appreciable amount was used as substrate for silage fermentation. Ensiling alfalfa and orchardgrass for 0, 5, 21 and 56 days maintained a decreasing trend of 83.8, 82.5, 79.3 and 78.9% digestibility in alfalfa and 80.5, 77.0, 77.1 and 76.4% digestibility in orchardgrass. While the digestibility of cellulose and ether extract increased in silage in both species, the digestible energy values in silage were reduced from 2.6 to 2.3 and 2.9 to 2.7 Mcal/kg DM respectively in alfalfa and orchard during 5-56 days ensiling.

• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.42-46
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• 2008

Even though fuel cell have high efficiency when pure hydrogen from gas tank is used as a fuel source, it is more beneficial to generate hydrogen from city gas (mainly methane) in residential application such as domestic or office environments. Thus hydrogen is generated by reforming process using hydrocarbon. Unfortunately, the reforming process for hydrogen production is accompanied with unavoidable impurities. Impurities such as CO, $CO_2$, $H_2S$, $NH_3$, $CH_4$, and $CH_4$ in hydrogen could cause negative effects on fuel cell performance. Those effects are kinetic losses due to poisoning of the electrode catalysts, ohmic losses due to proton conductivity reduction including membrane and catalyst ionomer layers, and mass transport losses due to degrading catalyst layer structure and hydrophobic property. Hydrogen produced from reformer eventually contains around 73% of $H_2$, 20% or less of $CO_2$, 5.8% of less of $N_2$, or 2% less of $CH_4$, and 10ppm or less of CO. This study is aimed at investigating the effect of carbon dioxide on fuel cell performance. The performance of PEM fuel cell was investigated using current vs. potential experiment, long run(10 hr) test, and electrochemical impedance measurement when the concentrations of carbon dioxide were 10%, 20% and 30%. Also, the concentration of impurity supplied to the fuel cell was verified by gas chromatography(GC).

• Journal of Korean Society of Forest Science
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• v.108 no.4
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• pp.618-627
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• 2019

An increase in damage to crops and facilities caused by wildlife such as wild boar causes serious social and economic problems to the rural economy in Korea. This study aims to estimate the economic losses incurred to rural households in mountain villages near protected areas in Korea due to the damage to agricultural and forestry production by wildlife. The case of mountain villages located in Toji-myeon, Gurye-gun near the Jirisan National Park was studied as an example. Data were collected by interviewing 84 households across six mountain villages in April and June 2016. The results indicate that the economic losses due to wildlife damage in 2015 were estimated to be 1.65 million KRW per household, which is a total of 138.63 million KRW for the 84 households. Among local products, the most damaged products were chestnut, fern-brake, wild pear, peach, and potato, whereas the most damaged products per production area were sweet potato, peach, corn, and potato. The potential economic losses caused by wildlife damage to agricultural and forestry production in whole Gurye-gun area was estimated to be around 4.0 billion KRW in 2015. However, the municipal government budget for the compensation of wildlife damage was only 0.9 percent of the potential rural economic losses caused by wildlife damage in 2015. The results of our study suggest that the compensation scheme for wildlife damage is inadequate in the respect of social justice. Considering the low financial capacity of the municipalities in mountain areas, the central government should take a progressive responsibility by allocating more financial resources for compensation of economic losses of rural households due to wildlife damage. The equitable and effective governance of wildlife conservation is required for sustainable development of rural communities near protected areas.

• Management & Information Systems Review
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• v.32 no.1
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• pp.259-272
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• 2013

This Paper document that managers' cash compensation is more sensitive to negative stock return than positive stock return. Also, this paper analyse that managers' cash compensation react symmetrically to accounting earnings and losses. Since stock returns include both unrealized gains and unrealized losses, we expect managers' cash compensation to be less sensitive to stock returns when returns contain unrealized gains(positive returns) than when returns contain unrealized losses(negative returns). But accounting earnings exclude unrealized gains and include unrealized losses, so managers' cash compensation will react symmetrically to accounting earnings and losses. Analyzing 5,815 firm-year data for 2000-2011, we find that managers' cash compensation reacts asymmetrically to stock retruns whereas managers' cash compensation reacts symmetrically to accounting performance. This finding is consistent with boards of directors seeking to mitigate ex post settling up problem that would arise of managers' cash compensation was equally sensitive to positive and negative stock return.

• International Journal of Highway Engineering
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• v.11 no.1
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• pp.203-215
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• 2009

This study was conducted to develop the design methodology of longitudinal post tensioning for the post-tensioned concrete pavement (PTCP). The longitudinal stress distribution in the PTCP slab was analyzed when post tensioning was applied. Then, the tensile stress distribution in the PTCP slab due to the environmental and vehicle loads needed for the design was investigated. In addition, prestress losses were calculated considering the losses due to the frictional resistance between the slab and underlying layer and due to various reasons related to tensioning. The tensile stresses used for the design were obtained by adding the stresses from the critical conditions under both the environmental and vehicle loads. The prestress losses were obtained by considering actual field conditions. The effective post tensioning amount was determined by considering the design loads including environmental and vehicle loads and various losses, and the effect of the allowable tensile stress on the post tensioning amount was investigated. The initial stage of the design of the longitudinal post tensioning is to obtain the stresses under the design loads and the required prestress determined by subtracting the allowable tensile stress from the design stress. Then, the optimal tendon spacing and the tensioning amount can be obtained by comparing with the effective tensioning amount including various stress losses.

• Journal of International Area Studies (JIAS)
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• v.18 no.3
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• pp.145-168
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• 2014

Given the distance from Mt. Baekdu, volcanic ash will have the direct impact on South Korea in case Mt. Baekdu erupts. Ash fall deposits or particulate matters(PM10) in the air will cause damages in various sectors. In particular, the PM10 impact on the manufacturing sector when the ash disperses in Korea is needed to be assessed since South Korea's manufacturing sector accounts for more than 30% of GDP. Meanwhile the economic impacts of PM10, including Asian dust, have been researched in Korea as the events become frequent, and losses in the manufacturing have been also reported. This study is to identify vulnerable sectors to volcanic ash in the korean industry, and to assess economic losses in case of a Mt. Baekdu eruption scenario, based on the historical loss experience with particulate matters. Study results show that airline, precision such as electronics and semiconductors, distribution, shipbuilding, car, leisure, glass, dairy farming are vulnerable to volcanic ash, or PM10. The economic losses in both car and shipbuilding industry is estimated to 46.49 billion Korean won due to shutdown for 6 hours in case of a Mt. Baekdu eruption scenario.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.4
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• pp.1798-1802
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• 1969

The experiment was carried out as one of the basic studies to improve the alkali-resistance of cement mortars and it was conducted to investigate some propetties of mortars relating to weight losses when exposed to 0.1 N salution of sodium hydroxide. The experiment and the results obtained are summarized as follow; 1. The specimens used in this experiment were made of 5 centi-meter cubes of mortar having such various ratios of mix by weight as 1 : 1, 1 : 3, 1 : 5, 1 : 7 and 1 : 10. 2. Physical tests included compressive strengths at 7 days, 28 days, 3 months, and 6 month, and 5 hour boiling absorption test. 3. In alkali test, every specimen was immersed into 0.1 N solutions of sodium hydroxide. The specimens exposed to the alkali solution were weighed to determine the weight losses of the alkail-corroded at one week interval for 7 week's exposure and the old alkali solutions were also changed to fresh solutions when weighed the weight losses by alkali attack at one week interval. 4. According to the alkail test after 7 week's exposure, no weight losses were observed on ratios of mix 1:1 and 1:3 and slight weight losses occurred on ratios of mix 1:5 and 1:7, but relatively large amount of weight losses were showed by 36.6 per-cent on ratios of mix 1:10. It was also found that the weight losses of the alkali-corroded were extremely lower than those of the acid-corroded at the some concentrations as 0.1 N of solutions. 5. In order to make better quality of alkali-resistant mortar it might recomend that a 1:7 mix or richemixes, use of small amount of mixing water for watertight, 20 per cent or less absorption by 5 hour boiling 1,600 kirogram per cubic meters or denser densities by absolute dry base are available for physical properties of mortar. It could conclude acid-resistant mortars were so high alkali-resistant, that it is expected to make and improve the acid-resistant mortars for getting rid of damages by alkali attack.

• The Korea Swine Journal
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• v.30 no.1 s.341
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• pp.164-165
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• 2008