• KSBB Journal
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• v.20 no.2 s.91
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• pp.84-87
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• 2005

Toxicity test for biodiesel (BD), biodiesel-derived neopentyl polyol ester (NPE) lubricant oil base, lubricant oil for diesel engine oil (LODE) and petroleum diesel (PD) was carried out using earthworm, Eisenia fefida. According to the method by OECD 207, the $LC_{50}$ values of BD and NPE were estimated as 2,450 and 1,528 mg/kg, respectively, which indicate that these compounds are classified as slightly toxic compounds. The $LC_{50}$ values of LODE and PD were estimated as 500 and 603mg/kg, respectively, showing that theses compounds are evaluated as moderately toxic compounds.

• Restorative Dentistry and Endodontics
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• v.22 no.2
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• pp.648-658
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• 1997

The purpose of this study was to compare the effects of various techniques on the quality and quantity of instrumentation in curved canals. Instrumentation time was evaluated too. Forty eight canals of resin blocks($35^{\circ}$) were divided into three groups and filed. In group A, 16 blocks were instrumented using a step-back technique with stainless steel(SS) K-file(Mani, Matsutani Seisakusho Co.,Japan). In group B, canals were prepared with SS K-files using the Endo-Angle (Nakanishi Dental MFG.CO.,LTD.,Japan). Group C was prepared using N i-Ti engine-driven instruments (Quantec Series $2000^{TM}$ system). Group A and B were filed from # 5 to # 25 at the apex followed by a 1 mm stepback technique, and the coronal half of the canals were flared with Gates Glidden burs(#2,3,4). Group C was instrumented from # 1 to # 8. After the instrumentation time was measured, canals were filled with India ink, and photographed, which to magnify the canal images 8 times. Using these photographs the apical portions were evaluated And scored from 1 to 4 according to the severity of ledging and zipping. On the same photographs, the area of the coronal two thirds of the canals were measured using a personal computer with the computer program Brain and Digitizer (SummaSketch III). The following results were obtained. 1. Instrumentation time was significantly shorter for group C, as opposed to group A and B(ANOVA, P<0.05). 2. The qualitative evaluation of the apical portions of the canals showed no significant difference between the groups(Kruscal-Wallis, p>0.05). 3. The area removed by group C was significantly smaller than group A and B(ANOVA, P<0.05).

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.5
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• pp.1358-1364
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• 2016

Maritime accidents caused by a ship include collisions, sinking, stranding and fire etc. This study is intending to consider fire accidents among such diverse marine accidents. It is much likely that various sorts of fires break out because crewmen are living in a narrow space for long periods of time consequent on the ship's characteristic of sailing on the sea. According to the ship fire survey, about 50% of the total fire accidents occurred at an engine room, and the main fire origin was analyzed to be oil. In addition, ship fire breaks out in the order of baggage racks and living quarter. In short, the survey indicates that all sorts of fires belonging to A, B, C and D-class have occurred. This study, targeting an actual passenger ship 'A', found the response time to evacuation, during which the people on board a ship recognize the outbreak of fire, and act, and the travel time for evacuation which is the actual travel time. In addition, this study carried out a simulation through the special program for fire analysis - FDS (Fire Dynamics Simulator) in order to find the effective evacuation time, i.e. life survival time. Particularly, this study did comparative analysis of the influence on the survival of passengers and crew based on the collected simulation data by fire size and sort. As a result of the analysis, it was found that when examining the only actual evacuation movement time excepting the response time to evacuation, people are safe by completing evacuation before the effective evacuation time only in case fire size is 100Kw among all sorts of fires. In other words, in case of the outbreak of fire more than 1 MW, it was found to fail to meet evacuation safety regardless of fire size.

• Korean Journal of Agricultural Science
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• v.47 no.2
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• pp.327-335
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• 2020

The purpose of this study was to analyze the load distribution and contact safety factor for the power take off (PTO) gear of a 71 kW class agricultural tractor. In this study, a simulation model of the PTO gear-train was developed using Romax DESGINER. The face load factor and contact safety factor were calculated using ISO 6336:2006. The simulation time was set at 2,736 hours considering the lifetime of the tractor, and the simulation was performed for each PTO gear stage at the engine rated power conditions. As a result of the simulation, the face load factors for the driving gear at the PTO 1^st, 2^nd and 3^rd stages were 1.644, 1.632, and 1.341, respectively. The contact safety factors for the driving gear at the PTO 1^st, 2^nd and 3^rd stages were 1.185, 1.216, and 1.458, respectively. As the PTO gear stage was increased, the face load factor decreased, and the contact safety factor increased. The load distributions for all the PTO gears were concentrated to the right of the tooth width. This causes stress concentrations and shortens the lifespan of the gears. Therefore, it is necessary to improve the face load factor and the contact safety factor with macro-geometry and micro-geometry.

• KSBB Journal
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• v.20 no.1 s.90
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• pp.55-59
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• 2005

Toxicity test for biodiesel (BD), biodiesel-derived neopentyl polyol ester (NPE) lubricant oil base, lubricant oil for diesel engine (LODE) and petroleum diesel (PD) was carried out using microalgae, Chlorella vulgaris. According to the method of OECD 201, the $EC_{50}$ values of BD and NPE were estimated as 84 and 69 mg/L, respectively, which indicates that these compounds are classified as slightly toxic compounds. The $EC_{50}$ values of LODE and PD were measured as 42 and 24 mg/mL, respectively, showing that these compounds are considered as moderately toxic compounds.

• Journal of Navigation and Port Research
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• v.33 no.3
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• pp.175-180
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• 2009

In this study, the basic data were collected for improving the amenity of indoor environment of a super yacht and the performance of indoor environment was analyzed by utilizing measured data during summer period. Through the results of examination, the following conclusions are drawn. 1) It is estimated that, in case of closing the door of Saloon connected with outside, there is little inflow of exhaust gas, but when the door is open, the indoor-air might be polluted so fast. Therefore, it is necessary to make a counter plan about the method of ventilation and amount of ventilation to keep the indoor aerial environment agreeable. 2) It is urgent to conceive countermeasure against engine noise because the noise level of all rooms exceeds 60dB, which is regulation of noise for protecting crew established in ship's classification, during the sailing. 3) State cabin and Guest cabin are super cooled by operating air conditioner exceeding agreeableness extent and it is needed to prevent them.

• Journal of Biosystems Engineering
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• v.25 no.5
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• pp.369-378
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• 2000

The purpose of this study is to developed high-efficient rotary tillage system for a power tiller by improving the rotary blade. A kind of the rotary blade with single-edged blade(DS) was developed that requires lower tillage energy than conventional double-edged blade(CD) on the design theory for Japanese rotary blade. In order to find out the tillage characteristics between the single-edged blade and the double-edged blade for power tiller, experiments were performed in soil-bins which were filled up clay loam, loam and sandy loam, and then analyzed the effects of the factors such as soil texture, travelling speed, rotational speed, and tillage depth to each of the blades. And field tests were carried out to compare tillage performances of the two blades using rotary cultivator driven by conventional power tiller. The results of this study were summarized as follows; 1) On the soil bin experiment, it was found that tillage torque of the single-edged blade was less than the ones of the double-edged blade. The decreasing ratios of maximum tillage torque of the single-edged blade to the ones of the double-edged blade were 1 to 8% at clay loam, 5 to 20% at loam and 9 to 31% at sandy loam, respectively. 2) By the field tests, that the tillage performances with the single-edged blade compared with the double-edged blade was improved about 19% in field capacity, about 34% in fuel consumption, and 12.5% in soil breaking ratio. Furthermore, the fluctuation of engine speed, the variation of exhaust gas temperature, and the amount of soil clogging on the blade and straw wound on the rotary shaft showed lower values with the developed blade than the conventional blade. So, it may be concluded that tillage performance by the developed single-edged blade was improved compared with the one by the conventional double-edged blade.

• Tribology and Lubricants
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• v.31 no.6
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• pp.251-257
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• 2015

Heavy oil production is receiving significant attention because of increased demands for thermal power generation systems of the diesel engine and boilers. However, asphaltene, which is a heavy oil components (6-8 wt%), reduces the heat efficiency of the fuels owing to its agglomerated sludge of asphaltene during the burning process. Therefore, for hassle-free operation, we should develop asphaltene dispersants to suppress the formation of the sludge. We prepare variable salt-type polymeric dispersants using poly(isobutenyl succinic anhydride) and poly(amine) through both condensation esterification and acid-base neutralization reactions, which we subsequently evaluate for dispersing performance, using Turbiscan measurement. Total acid number (TAN) and total base number (TBN) of 75Lec-25SynDis.2 composed of lecithin and the prepared polymeric salt having the ratio of 3 : 1 are 18.9 and 33.7 mg KOH/g, respectively, which are comparable to those of the commercial dispersants (15.8 and 26.5 mg KOH/g). We determine the initial turbidity observed for 15 min of the polymeric dispersant was determined with transmittance (%), which can be calculated to separability number (SN). The SN value of 75Lec-25SynDis.2 is close to zero, which is superior to that of commercial dispersants and lecithin (0.015 and 0.017).

• Journal of the Korean Institute of Gas
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• v.25 no.5
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• pp.19-29
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• 2021

Due to the climate changing, the world's countries are tightening regulations on CO2 and air pollutants emission to solve them. In addition, eco friendly vehicles is increasing to replace automobiles in internal combustion engine. Recently, the government is supporting the expansion of hydrogen refueling infrastructure and localization of core equipment in refueling facilities according to the hydrogen economy road map. In this study, design of the Excess flow limiting device in FCEV cylinder valve using by finite element analysis and performed performance tests on prototype. Major test results as hydrostatic strength, continued operation, operation, pressure impulse, leakage showed that the excess flow limiting device meets the performance requirements according to ISO 12619-2 and ISO 12619-11.

• Journal of Biosystems Engineering
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• v.43 no.4
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• pp.311-319
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• 2018

Purpose: The aim of this study is to develop a small combine for harvesting miscellaneous cereal crops. Methods: A prototype small combine was designed and constructed. Its specifications and basic performance were investigated. Results: The prototype small combine for harvesting miscellaneous cereal crops was designed and constructed to reflect similar specifications as those of the conventional combine. The prototype small combine comprises a diesel engine with the rated power/speed of 22.0 kW/2,600 rpm, three-stage primary and two-stage speed range transmission shifts, and a double acting threshing part. The maximum travel speeds of the prototype combine are approximately 0.72 m/s, 2.50 m/s, 0.30 m/s at the low, high speed range shifts in the forward direction, and while traversing in the reverse direction, respectively. The minimum radius of turning was approximately 1.50 m. In a static lateral overturning test, the prototype combine overturned neither to the right nor to left on a $30^{\circ}$ slope. The results of an oilseed rape harvesting test included the maximum operating speed of 0.32 m/s, the grain loss ratio of approximately 9.0%, and the effective field capacity of approximately 10.3 a/h. Additionally, among the outputs in grain outlet, the whole grains, damage grains, and materials other than grain (MOG) ratios accounted for 97.4%, 0.0%, and 2.6%, respectively. Conclusions: The prototype small combine for harvesting miscellaneous cereal crops indicates good driving ability and stability. The results of the oilseed rape harvesting test reveal that the harvesting performance must be enhanced such that the separating and cleaning parts are more suitable for each type of crop, thus reducing grain loss and foreign substances among the outputs in grain outlet. An improved small prototype combine could be used effectively to mechanize the harvesting of miscellaneous cereal crops in small family farms or semi-mountainous areas.