• Tribology and Lubricants
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• 제25권2호
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• pp.125-131
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• 2009

Biodiesel produced from triglyceride which is main component of animal fats and vegetable oils by methanolysis was known for excellent lubricity. In this study, the lubricity of 12 kinds of biodiesel come from vegetable oils were analyzed using HFRR(High frequency reciprocating rig). The biodiesel synthesized from soybean oil has best lubricity by $153{\mu}m$ of wear scar in HFRR and used fried oil's biodiesel has slightly low lubricity by $299{\mu}m$. Also we have found that the lubricity of diesel was improved when mixing ratio of soybean biodiesel was increased in base diesel.

• 대한물리의학회지
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• 제15권4호
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• pp.1-9
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• 2020

PURPOSE: The current generation has shortened hamstrings due to a sedentary lifestyle, resulting in reduced flexibility of the hamstring and dysfunction. This study was undertaken to compare effects of three different release exercises on hamstring flexibility, in participants with short hamstrings. METHODS: Totally, 20 subjects having short hamstrings were involved in this study. The inclusion criterion for study participation was active knee extension test (AKET) less than 60°. All participants were subjected to 3 methods: hamstring foam roller release (HFRR), sitting self myofascial release (sitting SMR), and standing self myofascial release (Standing SMR). All participants randomly performed all three methods to avoid bias caused by learning or fatigue. Passive knee extension test (PKET), AKET, finger to floor distance test (FTFT), and pelvic tilting angle test (PTAT) were measured pre- and post-exercises. RESULTS: The PKET, AKET and FTFT were significantly increased after HFRR, sitting SMR, and standing SMR exercise (p < .05). However, PTAT was not significantly increased after the three exercises (p > .05). Furthermore, no significant differences were observed between PKET, AKET, FTFT and PTAT subsequent to HFRR, sitting SMR, and standing SMR (p > .05). CONCLUSION: Our results indicate that HFRR, sitting SMR and standing SMR were immediately effective in improving hamstring flexibility in participants with short hamstrings.

• 공업화학
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• 제21권6호
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• pp.684-688
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• 2010

동식물 유지의 주성분인 트리글리세라이드를 메탄올과 반응시켜 생산된 바이오디젤은 기존 석유디젤에 비해 윤활성이 뛰어난 것으로 알려져 있다. 본 연구에서는 대두유, 팜유, 들기름으로부터 합성된 식물성 바이오디젤과 우지, 돈지로부터 생산된 동물성 바이오디젤의 윤활성을 측정한 결과 대두유와 들기름으로부터 합성된 바이오디젤은 다른 바이오디젤보다 윤활성이 높게 측정되었다. 순수한 바이오디젤의 윤활성과 이들 바이오디젤의 구성분자 조성을 가스크로 마토그래피-질량분석기를 이용해 분석한 결과, 올레핀 함량이 높고 분자길이가 긴 바이오디젤일수록 윤활성 향상효과가 뛰어난 것을 확인할 수 있었다.

• Tribology and Lubricants
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• 제26권3호
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• pp.190-198
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• 2010

GTL(gas-to-liquid) fuel produced by the Fischer-Tropsch process using carbon monoxide(CO) and hydrogen(H2) is expected to be one of the environmental friendly fuel for alternative and blended to petrodiesel. But GTL have poor lubricity due to paraffin as main component of GTL which is not involve polar materials. In this paper, we had investigated the lubricity improvement of GTL fuels with various lubricants using HFRR(high frequency reciprocating rig).

• Tribology and Lubricants
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• 제32권3호
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• pp.95-100
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• 2016

As an alternative fuel, biodiesel has excellent lubricating property. Previously, our research group reported that the properties of biodiesels depended on their composed molecular structure. In this study, we investigate lubricity and the mechanism of lubricity improvement of synthesized biodiesel molecules. We synthesize four types of biodiesel components from fatty acid via fisher esterification and soybean biodiesel from soybean oil via transesterification in high yield (92-96%). We analyze the lubricity of the five 5 types of biodiesel using HFRR (high frequency reciprocating rig). We estimate that the mechanism of lubricity is relevant to the molecular structure and structure conversion of biodiesel. The test results indicate that the longer the length of molecules and the higher the content of olefin, the better the lubricity of the biodiesel molecules. However, the wear scar size of the first test samples’ do not show a regular pattern with the wear scar size of the second test samples’. Moreover, we investigated the structure conversion of the biodiesels by using GC-MS for the recovered biodiesel samples from the HFRR test. However, we do not detect structure conversion. Thus, we conclude that the lubricity of biodiesel depends on how effectively solid adsorption and boundary lubrication occurs based on the size of the molecule and the content of olefin in the molecule. In addition, HFRR test condition in not sufficient for Diels-Alder cyclization of biodiesel components.

• 한국분무공학회지
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• 제10권4호
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• pp.8-15
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• 2005

The use of clean gaseous fuels for the purpose of high efficiency and low emission in automotive engines has tendency to increase in order to meet the reinforcing emission regulations and to efficiently utilize limited natural resources. Automotive companies developed and commercialized a LPG liquid injection system, which is mounted on LPLi(Liquid Phase LPG Injection) engines and vehicles based on this research trend. This research examines the biggest problem in LPLi engine, that is, the leakage characteristics of low viscosity LPG fuel according to the injector design variables. This study is also aimed to improve the performance of fuel-leakage in LPLi engine through the addition of a lubrication improver in HFRR(High Frequency Reciprocating Rig) facility. The needle displacement and the spring displacement of an LPLi injector are found to be already optimized. The possibility of a maximum of 70% leakage reduction compared to a conventional case, is verified when 1000ppm of a lubrication improvement material is added and 40% increase of a injector spring constant (K) is applied.

• 공업화학
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• 제23권4호
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• pp.421-427
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• 2012

초저유황 경유의 윤활성능을 향상시킬 목적으로 식물유 기반 알칸올 아마이드 유도체를 합성하여 윤활성능을 평가하였다. 알칸올 아마이드 유도체는 폐식물유(다크오일), 팜유, 코코넛유를 메탄올과의 연속 전이에스테르화 반응을 통하여 합성한 지방산 메틸에스테르와 디에탄올아민(DEA)의 아마이드화 반응을 행하여 합성하였다. 합성한 알칸올 아마이드 유도체는 1 wt% 범위 내에서 초저유황 경유에 잘 용해되었으며, 이 유도체를 120 ppm 포함한 초저유황 경유의 윤활성능을 HFRR법으로 측정하였다. 그 결과, 초저유황 경유의 마모흔의 직경이 581 ${\mu}m$에서 아마이드 첨가 후 305~323 ${\mu}m$으로 현저히 작아져 초저유황 경유의 윤활성능을 향상하는 것으로 확인되었다. 한편, 식물유의 종류에 따른 마모흔의 차이는 크지 않아 알칸올 아마이드 유도체의 알킬기의 구조에 따른 윤활성능의 차이는 크게 나타나지 않았다. 알칸올 아마이드 한 종류를 선정하여 첨가 농도에 따른 윤활성능을 평가한 결과, 농도에 따라 마모흔의 직경이 현저히 작아지는 결과를 얻었는데 이는 윤활성능이 첨가 농도에 따라 향상되는 것을 의미한다.

• Tribology and Lubricants
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• 제26권1호
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• pp.78-87
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• 2010

Biodiesel have been studied as alternative fuel due to solution of air pollution and fossil fuel exhaustion. Biodiesel from animal fat and vegetable oil was known as eco-friendly fuel like low toxicity, biodegradable compare to petrodiesel. In particular, biodiesel have excellent lubricity due to involved ester functional group. This paper shows the biodiesel's lubricity based on worldwide biodiesel research.

• Tribology and Lubricants
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• 제36권6호
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• pp.385-390
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• 2020

It rains heavily, such as long rain and typhoons, during a typical rainy season in Korea. In this season, several fuel contamination accidents by water and vehicular problems caused by water contaminated fuel occur. Many research groups have studied the effects of water contaminated fuel on vehicles and environment. However the characteristics of water contaminated fuel have not been studied. In this study, we prepared diesel samples with a constant ratio of water (0~30 volume %) using an emulsifier. Then, we analyzed these diesel samples for their representative fuel properties. In the analytical results, diesel with 30% water showed an increase in fuel properties such as density (823→883 kg/㎥), kinematic viscosity (2.601→6.345 ㎟/s), flash point (47→56℃), pour point (-22→2℃), CFPP (cold filter plugging point) (-17→20℃) and copper corrosion number (1a→2a). The low temperature characteristics, such as low pour point and CFPP, blocks the fuel filter in the cold season. In addition, water contaminated diesel decreases lubricity (190→410 ㎛) under high frequency reciprocating rig (HFRR) and derived cetane number (54.81→34.25). The low lubricity of fuel causes vehicle problem such as pump and injector damage owing to severe friction. In addition, the low cetane diesel fuel increases exhaust gases such as NOx and particulate matters (PM) owing to incomplete combustion. This study can be used to identify the problems caused by water contamination to vehicle and fuel facilities.

• 공업화학
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• 제24권5호
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• pp.530-536
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• 2013

경유의 윤활성향상제로 사용하기 위하여 식물유 기반 다이머산 유도체를 합성하여 윤활성능을 평가하였다. 다이머산 유도체의 합성은 2단계의 반응을 거쳐 합성하였는데, 1단계 반응으로 폐식물유(다크오일)를 가수분해반응을 통하여 합성한 지방산을 사용하여 고온에서 디엘스-알더 반응을 행하여 다이머산을 합성하였다. 2단계 반응으로 합성한 다이머산을 사용하여 메탄올과 에스테르화 반응을 행하여 다이머산 유도체를 합성하였다. 합성한 다이머산 유도체는 1 wt% 범위 내에서 초저유황 경유에 잘 용해되었으며 일정량(120 ppm)을 초저유황 경유에 첨가하여 HFRR 시험법으로 마모흔을 측정하여 윤활성능을 평가하였다. 그 결과, 첨가 전 초저유황 경유의 마모흔의 직경이 $552{\mu}m$에서 첨가 후 $300{\sim}05{\mu}m$으로 현저히 작아져 초저유황 경유의 윤활성능을 향상하는 것으로 확인되었다. 한편, 식물유의 종류에 따른 마모흔의 차이는 크지 않아 다이머산 유도체의 알킬기의 구조에 따른 윤활성능의 차이는 크게 나타나지 않았으나, 카르복실산 그룹을 함유하는 다이머산 유도체가 함유하지 않은 유도체보다 윤활성능이 우수하였다.