• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.981-988
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• 2008

This paper describes a development of automatic measuring device for cylinder liner wear amount. An operator should regularly measure the wear amount of the cylinder liner to prevent the wear amount of the cylinder liner from exceeding the maximum limit specific to the engine type. In previous methods. an operator entered the inside of the cylinder liner on a ladder and measured the amount of wear using a inside micrometer. Such method is unpleasant in severe environments and full of hazards. In addition, in order to enter the cylinder, the piston head had to be detached. requiring much time and money. In order to solve these problems, a new measuring device that consists of two measuring units and a special install jig is developed. The measuring units are installed through the scavenging air port by the install jig and measures the wear amount during 1 revolution of crankshaft. so detaching of the cylinder head and entering inside the cylinder liner are not required.

• Journal of Advanced Marine Engineering and Technology
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• 제32권6호
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• pp.847-853
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• 2008

Although combustion is essential in most energy generation processes, it is one of the major causes of air pollution. Circle fin exhaust pipes were designed to study the effect of cooling the recirculated exhaust gases (EGR) of Diesel engines on the chemical composition of the exhaust gases and the reduction in the percentages of pollutant emissions. The designs adopted in this study were exhaust pipes with solid and hollow fins around them direct surface force measurement in water using a nano size colloidal probe Technique The direct force measurement between colloidal surfaces has been an essential topic in both theories and applications of surface chemistry. As particle size is decreased from micron size down to true Carbon nano Colloid size (<10nm), surface forces are increasingly important. Nanoparticles at close proximity or high solids loading are expected to show a different behavior than what can be estimated from continuum and mean field theories. This paper use Water and CNC fluid at normal cooling system of EGR. Experimental result showed all good agreement at Re=$2.54{\times}10^{4}$.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2000년도 추계학술대회 논문집(Proceeding of the KOSME 2000 Autumn Annual Meeting)
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• pp.99-107
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• 2000

With the results of calculation for natural frequencies, the forced reponses of coupled vibration of propulsion shafting were analysed by the modal analysis method. For the forced response analysis, axial exciting forces, axial damper/detuner, propeller exciting forces and damping coefficients were extensively investigated. As the conclusion of this study, some items are cleared as next. - The torsional amplitudes are not influenced by the radial excitation forces. - The axial vibrational amplitudes are influenced by the tangential exciting forces. An increase of amplitude is observed for the speed range in the neighbourhood of any torsional critical speed. - The coupling effect becomes larger if torsional and axial critical speed are closer together. - The axial exciting force of propeller is relatively strong, comparing with those of axial forces of cylinder gas pressure and oscillating inertia of reciprocating mechanism. Therefore, as a resume one can say, that- Torsional vibration calculation with the classical one dimension model is still valid. - The influence of torsional excitation at each crank upon the axial vibration is impotent, especially in the neighbourhood of a torsional critical speed. That means that the calculation of axial vibration with the classical one dimension model is insufficient in most of cases. - The torsional exciting torque of propeller can be neglected in most of cases. But, the axial exciting forces of propeller can not be neglected for calculating axial vibration of propulsion shafting.

• Journal of Advanced Marine Engineering and Technology
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• 제20권5호
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• pp.82-92
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• 1996

A computer simulation with predict the fuel injection rates and the fuel injection pressure behaviors in diesel engine fuel injection systems would by very useful in designing or improving fuel injection systems. In this paper we developed computer program in order to predict the behaviors of the fuel injection rate and the injection pressure for Electronic Hydraulic Ultra-High Pressure Fuel Injection System. We've applied the continuity and momentum equations for the hydraulic phenomena and the dynamics of individual components of the Electronic Hydraulic Fuel Injection System. To solve all the equations numerically we've applied the Runge-kutta IV method. Water hammer equations were applied for the hydraulic pipe solution, and the method of characteristics was employed in our calculations. The simulation results were compared with the experimental results for: Accumulator pressure, Injection pressure and unjection rate. As a result, The simulation results agree very well with our experimental results. We found that a large accumulator and the high speed solenoid valve were required, and the compression volume of the fuel had to be as small as possible in order to acheive ultra-high pressure fuel injection.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2005년도 전기학술대회논문집
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• pp.1069-1076
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• 2005

The oil crises in 1973 and 1979 caused considerable effort to decrease the fuel consumption. As a result, the main engine had been changed through the shape(from loop scavenging air system to uniflow scavenging air system), higher compression ratio, low speed and long stroke. It is difficult to make a various engine satisfied with all owner's request. So manufacturer could find a way that can change the rating through large range from the engine already manufactured. These ways are tried through large range to change rpm to 72% and engine's output to 48% of MCR with keeping the normal engine's shape almost. The important element considered in the process of derated output of the main engine is to recover the beginning overcapitalization as soon as possible through low SFOC. In this paper, it is compared and considered between rating and derating engine with several data about modifying rating which have been done by engine manufacturer so far. And the selection process of derating engine is studied also.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.549-554
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• 2013

For the past years, higher power rating 2 stroke super long stroke diesel engines having more than 8 cylinders and larger cylinder bore are installed mainly on very large containerships to save on fuel consumption. However, these engines are prone to X-mode vibration due to $2^{nd}$ node torsional vibration or the X-type moment, particularly because of the increase in total length and height. Recently, cases of excessive X-mode vibration often occurred on engine's major components. This vibration is manifested also as secondary vibration causing failure in engine-mount large structures. This study investigated the excitations caused by the $2^{nd}$ node propulsion shafting torsional vibration that influence X-mode vibration of the main engine and practical countermeasures are proposed. An 8RT-82RT-flex 8 cylinder engine and 11S90S-ME 11 cylinder engine for a container ship was used as research model.

• 한국안전학회지
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• 제34권6호
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• pp.22-28
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• 2019

In South Korea, the enact of Korean Coast Guard Act-1 manages physical and chemical oil-dispersants. Oil snare, which is made of polypropylene, is newly added to the aforementioned act, and it has advantage on the ease of recovery compare to other adsorbents. This study synthesized bunker B-oil with diesel-oil and bunker C-oil to perform an adsorption test based on three samples which were manufactured in South Korea. As a result, adsorption test revealed 5.2 g/g more adsorption than the previous results from the act. Additional toluene test revealed that all the samples satisfied 90.0%, however coloured samples could release its pigment on the marine environment. Thus, colorless samples are recommended on the risk management of marine accidents. The study on the basic direction of the calculation of the test items and the standard value for the quality control of the oil snare was also carried out.

• 해양환경안전학회지
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• 제27권7호
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• pp.1116-1123
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• 2021

해수에 유출된 유류는 대기와 해수와의 접촉을 통해 다양한 풍화 과정(증발, 확산, 분산, 유화, 용해, 산화, 침전 및 생물분해 등)을 통해 물리·화학적 변화와 함께 생물학적 분해과정을 겪는다. 본 연구에서는 여러 가지 풍화작용 중 가장 즉각적이고 빠르며 오염물질의 질량에 가장 큰 영향을 미치는 인자라고 알려진 증발(evaporation)에 대한 영향을 확인해보고자 하였다. 휘발유, 등유, 경유를 대상으로 25 ℃(해수 연평균 온도)와 35℃(적도 부근 온도) 조건에서 유류의 휘발특성을 비교하였다. 이를 위해, 일정 기간마다 채취한 유류를 전처리하여 GC/MS 분석을 수행하고, 탄화수소의 변화량을 계산하여 비교하였다.

• 한국환경과학회지
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• 제31권9호
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• pp.781-791
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• 2022

In order to investigate the characteristics of the effects of various emission sources such as ships around the Busan North Port area, PM_2.5 samples were analyzed by SEM/EDS (scanning electron microscopy with energy dispersive x-ray spectrometer). In the port city Busan, the main emission source of PM_2.5 is ships, and soot was observed as the main exhaust particles of a ship diesel engine. As a result of the individual particle analysis of PM_2.5 at the sampling site, carbonaceous particles such as soot and water droplet-shaped, which are considered to be exhausted from ships, were constantly observed. And some spherical Fe-rich particles also appeared.

• 해양환경안전학회지
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• 제22권5호
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• pp.547-553
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• 2016

선박용 디젤엔진 배기가스에 포함된 입자상물질(PM) 가운데서 블랙카본(BC)은 극지방의 해빙을 촉진시키고 온난화를 유발하는 원인물질로서 큰 주목을 받고 있다. 본 연구에서는 향후 예상되는 PM/BC 배출 규제에 선제적으로 대응하고, 저감기술 개발 및 실증을 위한 기초연구의 일환으로 한국해양대학교 실습선 한바다호를 이용하여 실제 운항 중에 주기관의 배기관 수 포인트에서 PM을 샘플링하여 HR-TEM을 통해 그 구조와 특성을 분석하였다. 또한 배기가스 분석기를 이용하여 운전조건별 배기가스 내 유해물질의 배출 경향을 확인하였다. 분석 결과 엔진에서 배출된 PM의 구조는 구형 입자들의 촘촘하지 않은 체인형 결합으로 이루어져 있으며, 과급기로부터 멀어질수록 온도 저하에 의한 응집이 더 많이 관찰되었고 BC 특유의 graphitic 구조를 잃어가면서 점점 amorphous 구조를 띠는 경향이 나타났다. 또한 배기가스 분석을 통해 엔진 회전수가 증가할수록 배기 내 PM의 농도는 감소할 것으로 예측되었다.