• 공업화학
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• 제25권6호
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• pp.639-644
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• 2014

국내 자동차사는 순정엔진오일을 정해놓고 일반엔진오일보다 높은 가격으로 판매하고 있다. 본 연구에서는 국내 순정엔진오일 14종과 동급의 일반엔진오일(KS제품) 14종에 대하여 품질비교 및 차량을 이용하여 10,000 km씩 주행한 뒤, 회수된 엔진오일의 물성을 분석하였다. 분석 결과, 사용하지 않은 신유는 순정엔진오일과 일반 엔진오일의 품질이 대동소이하였지만, 오히려 주행 후 회수된 일반엔진오일은 순정엔진오일에 비해 윤활성이 우수하였으며, 동점도와 전산가 변화가 작은 것으로 나타났다.

• Tribology and Lubricants
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• 제23권6호
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• pp.306-311
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• 2007

This paper presents the friction characteristics of pb-fres pin bushing bearings for an automotive gasoline engine. The external load is 100 N to 600 N and the speed of the pin bushing bearing is 1000 rpm to 3000 rpm against the rubbing surfaces. And the contact modes of rubbing surfaces between a piston pin and a pb-free pin bushing specimen are a dry friction, an oil lubricated friction and a mixed friction that is starved by a lack of engine oil. Two influential factors of a contact rubbing modes and a material property are very important parameters on the tribological performance of a friction characteristic between a piston pin and a pb-free pin bushing. The experimental result shows that the pin bushing speed of 2000 rpm shows a typical oil film lubricated sliding contact mode in which means that as the applied load is increased, the friction loss is increasing. But other contact mode depending on the speed and the load may affect to the fiction coefficient without a regular and uniform trend. In summary, the oil lubricated rubbing surface definitely decreases a running-in period in short and increase oil film stiffness, and this may leads the reduction of a friction loss.

• Journal of Biosystems Engineering
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• 제26권4호
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• pp.323-330
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• 2001

The regular maintenance and repair status of major farm machinery such as power tiller, farm tractor, rice transplanter and combine harvester etc., were surveyed and analyzed for the full-time farmers in order to get basic information for promoting farm machinery productivity. The survey was carried out through 209 farmers from 9 provinces. The results of this study can be summarized as follows; 1. The regular maintenance of farm machinery was conducted at repair shop(49.5%) or dealer agency(12.0%), and also conducted by farmers at their house(34.9%). 2. For the status on the cleanness or exchange times of engine oil, fuel filter and air cleaner, most farmers conducted fewer times than the necessary times. And, 5.3%, 7.7%, and 2.9% of surveyed farmers experienced breakdowns due to the insufficient cleanness or exchange oil, fuel filer, and air cleaner, respectively. 3. Most farmers(76.1%) recognized the necessity of farm machinery training or education, and they preferred one week for the training period, simple or easy maintenance for the training level, agricultural technical center or farm machinery manufacturer for the training agency. 4. Complete recognition of operation manual and sufficient maintenance before-, during-, and after-operation for the farm machinery can minimize the breakdowns, enlarge the endurance prevent the safety accidents, and promote productivity of farm machinery. And, these can be accomplished by the thorough training or education for agricultural machinery.

• Journal of Advanced Marine Engineering and Technology
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• 제39권4호
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• pp.381-386
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• 2015

최근에 환경오염 문제와 대체에너지 문제에 많은 관심을 가지고 있다. 디젤기관은 세계적으로 연료의 경제성 때문에 사용이 증가할 것이다. 그러므로 선박용기관의 대기오염 문제도 여러 분야에서 큰 관심사가 되고 있다. 화석연료로 부터 배출되는 유해 배기가스를 줄이기 위하여 대체연료기술이 개발되고 있다. 이러한 신재생에너지의 바이오디젤연료는 기존 디젤연료를 대체할 친환경 에너지로 각광을 받고 있으며, 일정한 비율로 디젤연료와 혼합하면 기존 디젤기관에 개조 없이 사용가능하다. 본 연구에서 바이오디젤연료가 선박디젤기관의 연소특성에 미치는 영향을 분석하기 위하여 폐식용유로부터 제조된 바이오디젤유를 엔진에 적용하여 실험을 수행하였다. 폐식용 성분에는 세탄가와 점도가 높은 성분이 있고, 탄소함유량이 적으면서 산소함유량이 잔존하고 있다. 연구 결과 연료소비율은 증가하고, 압력, 압력상승율 및 열발생율은 감소하였다.

• 한국해양공학회지
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• 제35권1호
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• pp.13-23
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• 2021

Since the introduction of the mandatory energy efficiency design index (EEDI), several studies have been conducted on the maneuverability of waves owing to the decrease in engine power. However, most studies have used the mean wave force during a single cycle to evaluate maneuverability and investigated the turning performance. In this study, we calculated the external force in accordance with the angle of incidence of the wave width and wavelengths encountered by KVLCC2 (KRISO very large crude-oil carrier) operating at low speeds in regular waves using computational fluid dynamics (CFD). We compare the model test results with those published in other papers. Based on the external force calculated using CFD, an external force that varies according to the phase of the wave that meets the hull was derived, and based on the derived external force and MMG control simulation, a maneuvering simulation model was constructed. Using this method, a weather vaning simulation was performed in regular waves to evaluate the course-keeping ability of KVLCC2 in waves. The results confirmed that there was a difference in the operating trajectory according to the wavelength and phase of the waves encountered.

• 현장농수산연구지
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• 제3권1호
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• pp.142-157
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• 2001

This study was conducted to get the basic information for promoting farm machinery productivity by surveying the regular maintenance and repair status of major farm machinery such as power tiller, farm tractor, rice transplanter and combine harvester. The survey was carried out through 9 provinces including Cheju province by direct visiting farmers with prepared questionnaire. The results of this study can be summarized as follows : 1. The average farming carrier of the surveyed farmers was 25.3 years, and 21-30 years of farming carrier showed the highest portion as 40.7%. The average carrier of using farm machinery was 9.4 years, and that was 14.9 years for power tiller, 8.3 years for farm tractor, 9.0 years for rice transplanter, 7.9 years for combine harvester, 7.5 years for mini tiller, 9.7 years for power sprayer, and 8.2 years for binder etc. 2. The regular maintenance for farm machinery was conducted mainly at repair shop (49.5%) or dealer agency (12.0%) as 61.5%, and 34.9% of farmers conducted the regular maintenance by themselves at their house. 3. The reasons for not-fully recognizing operation manual and insufficient before-, during-, after-maintenance of farm machinery were insufficient time for them (45.8%), troublesome (22.9%), unknown maintenance method (16.3%), unknown the necessity for maintenance (12.4%), and others (2.6%) in order. 4. For the annual exchange of engine oil, 3.2 times is necessary but actually 1.7 times was exchanged for power tiller, 4.3 times is necessary but actually 1.9 times was exchanged for farm tractor, 2.7 times is necessary but actually 1.7 times was exchanged for rice transplanter, 2.2 times is necessary but actually 2.3 times was exchanged combine harvester. 5. For the annual cleanness or exchange of fuel filter, 3.2 times is necessary but actually 1.1 times was done for power tiller, 4.3 times is necessary but actually 1.6 times was done for farm tractor, 2.7 times is necessary but actually 1.7 times was done for rice transplanter, 1.9 times is necessary but actually 0.8 times was done for combine harvester. 6. For the annual cleanness or exchange of air filter, 3.2 times is necessary but actually 1.4 times was done for power tiller, 4.2 times is necessary but actually 2.4 times was done for farm tractor, 2.6 times is necessary but actually 1.6 times was done for rice transplanter, 3.9 times is necessary but actually 7.0 times was done for combine harvester. 7. For the experience of breakdown related to maintenance, 5.3% of farmers experienced breakdown due to the insufficient exchange of engine oil, 7.7% of farmers experienced breakdown due to the insufficient cleanness or exchange of fuel filter, and 2.9% of farmers experienced breakdown due to the insufficient cleanness or exchange of air filter. 8. Most farmers (76.1%) recognized the necessity for agricultural machinery training or education, and most farmers preferred about one week for the training period, simple or ease maintenance for the training level, agricultural technical center or agricultural machinery manufacturer for the training agency. 9. Complete recognition of operation manual and sufficient before-, during-, and after-maintenance for farm machinery can minimize the breakdown as well as conduct suitable period farming, enlarge the endurance, prevent the safety accidents, and promote productivity of farm machinery. Therefore, these can be accomplished by the thorough training or education for agricultural machinery.

• International journal of advanced smart convergence
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• 제4권1호
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• pp.162-178
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• 2015

Petroleum based fossil fuels used to power most processes today are non-renewable fuels. This means that once used, they cannot be reproduced for a very long time. The maximum combustion of fossil fuels occurs in automobiles i.e. the vehicles we drive every day. Thus, there is a requirement to shift from these non-renenewable sources of energy to sources that are renewable and environment friendly. This is causing the need to shift towards more environmentally-sustainable transport fuels, preferably derived from biomass, such as biodiesel blends. These blends can be made from oils that are available in abundance or as waste e.g. waste cooking oil, animal fat, oil from seeds, oil from algae etc. Waste Cooking Oil(WCO) is a waste product and so, converting it into a transportation fuel is considered highly environmentally sustainable. Keeping this in mind, a life cycle assessment (LCA) was performed to evaluate the environmental implications of replacing diesel fuel with WCO biodiesel blends in a regular Diesel engine. This study uses Life Cycle Assessment (LCA) to determine the environmental outcomes of biodiesel from WCO in terms of global warming potential, life cycle energy efficiency (LCEE) and fossil energy ratio (FER) using the life cycle inventory and the openLCA software, version 1.3.4: 2007 - 2013 GreenDelta. This study resulted in the conclusion that the biodiesel production process from WCO in particular is more environmentally sustainable as compared to the preparation of diesel from raw oil, also taking into account the combustion products that are released into the atmosphere as exhaust emissions.

• Tribology and Lubricants
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• 제39권2호
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• pp.49-55
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• 2023

Currently, the demand for green technologies toward a sustainable future is rapidly increasing due to growing concern over environmental issues. Methanol is biodegradable and can provide clean combustion to reduce sulfur oxide and nitrogen oxide emissions, and therefore it is a candidate fuel for marine engines. However, the effect of methanol on tribological characteristic degradation should be addressed for methanol-fueled engines. In this study, the methanol addition effects on tribological characteristic degradation is experimentally assessed using a pin-on-disk tribo-tester. Ni-based alloy is used as a target material due to its broad applicability as an engine component material. For a lubricant, engine oil with and without methanol are used. The tests are conducted for up to 10,000 cycles under boundary lubrication while the change in friction force is monitored. Additionally, the wear rate is determined based on laser scanning confocal microscope data. An additional test in which methanol is added at regular intervals is performed with an aim to directly observe its effect on friction. Overall, the friction coefficient increases slightly with increasing methanol concentration. Furthermore, the wear rate of the pin and disk increase significantly with methanol addition. The results also indicate that the friction increases instantaneously with methanol addition at the contacting interface. These findings may be useful for better understanding the methanol effect on the tribological characteristics of Ni-based alloys for methanol-fueled engines with improved performance.