• International Journal of Naval Architecture and Ocean Engineering
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• v.9 no.2
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• pp.199-208
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• 2017

We perform an experiment on lacquer formation with simple test device. The anti-lacquer is one of important issues to increase durability, and to improve performance in the engines because the lacquer formation cause sticking of fuel injection pump, scuffing of cylinder liners, and increase of lubricant oil consumption in the marine diesel engines. We suggest this simple test in order to save enormous experimental cost in marine diesel engines, and in order to have ease in performing the various tests. The influences of the Base Number (BN) of lubricant oils and the sulfur content of fuel oils in the formation of lacquer are investigated. In order to investigate physical and chemical properties of lacquer, we perform a variety of tests such as, visual inspection, EDS. In addition, we investigate adhesion of lacquer by pull-off test quantitatively, and perform dissolution test with dilute sulfuric acid.

• Journal of the Korean Solar Energy Society
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• v.37 no.3
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• pp.23-32
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• 2017

This paper presents losses comparison and analysis results for different types of fault modes of grid-connected photovoltaic system generated for long-term operation. The approach of losses comparison and analysis by faults is to identify relationship between measured and estimated values of five loss factors which are quantified from irradiance to system output power. This paper presents the symptom results for faults such as snow, shading, sensor defect, blackout, soiling and so on from three years or more monitored data. These results will indicate that it is useful to develop fault detection and diagnosis tool to enhance capacity factor and save operation and maintenance cost of grid-connected photovoltaic system in the field.

• Proceedings of the KSR Conference
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• 2002.10a
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• pp.414-423
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• 2002

Keep pace with economic development, the quality of transportation means such as railway, road, harbors has changed and those changes have affected to economic activities. It means that economic development and the changes of transportation quality have an inter-systemic relationship. So to speak, transportation means are major factor of national economic activities to implement economic and consumption activities by promoting supply of goods through the network between regions and industries. Currently, it is needed to connect railway and road between South and North Korea due to the economic cooperation of two sides and meeting of separated families based on the peacemaking mood. Moreover, to connect to T.C.R. and T.S.R. route will contribute to save time and cost of transporting freight to Europe comparing with shipping when South-North railway is connected. The possibility and method of connecting railway between South and North Korea will be introduced in this paper.

• Journal of the Korean housing association
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• v.14 no.4
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• pp.97-108
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• 2003

In 1990’ idyllic housing complex is spreading surrounding metropolitan areas of Korea as a result of needs for quality change of housing environment, which was caused by the increase of income, the spread of cars and the change of working environment. On the contrary to the idea of idyllic housing, however, while it is just surrounded by natural environment, it has some critical problems such as the lack of public facilities and its development which often damages the nature. The row houses which this study deals with are popular with working class especially in Europe as an idyllic urban housing. It is noticeable that they have separate private gardens which satisfy the residents'basic needs and save lot areas and building costs more than detached houses. This study intends to suggest row houses as an appropriate housing type for environmentally friendly housing in Korea through the analysis of cases of row houses.

• Proceedings of the KIEE Conference
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• summer
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• pp.800-802
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• 2004

When an accident is happen due to using a bad Wire Compressor, some public resentments are caused and It cause lawsuit for we. In case, we will undergo a colossal financial loss. in addition to, Guide to improve quality of operation by using the number of times of pressing and pressing pressure with cooperative private enterprise. And because of needs for Thermal, Electrical and Chemical factor analysis of connection point of sleeve, expect to try improving problems of wire presser whole our company. We expect that reduce fault and save cost by this process. Consequently, we will prevent power losing and black out due to line faults by expulsion of inferiority equipment and prevent heating and line fault. This is possible using Alarming and Auto Locking Wire Compressor that is improve on this study.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.150-151
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• 2007

In hydraulic oil pump system, pressure has a linear relationship with output torque of motor. Torque control of pump drive can easily output stable pressure, and it can retain required pressure at minimum speed to save power consumption. Switched reluctance motor(SRM) has many advantages such as low cost and low inertia. It can generate high torque at low speed. But inherent high torque ripple of SRM influences performance of pressure control in hydraulic oil system. This paper presents direct instantaneous torque control(DITC) of hydraulic oil pump system. DITC method can reduce inherent torque ripple of SRM, and output smoothing torque to load. So the proposed hydraulic oil pump system can support smooth pressure and fast dynamic power supply to the hydraulic pump system. At last the proposed hydraulic oil pump system is verified by computer simulation and experimental results.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.1
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• pp.8-13
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• 2016

Public institutions should replace their luminaires with LED lighting by 2020 to save energy. Because the LED lighting installation rate in schools has not yet reached the legal goal, the ESCO program feasibility was investigated. The amount of electricity used, electric rates, times of use in classrooms and fluorescent lighting maintenance costs etc., as well as the elements of lighting maintenance were analyzed. In the case of schools, the lamp usage time was so short that the ESCO projects with only energy savings were impossible. In order to execute the ESCO projects, the maintenance cost savings by replacing an existing luminaire should be considered and the introduction of the relatively cheaper tube type LED lamp than the flat type LED luminaire was required.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.6
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• pp.827-831
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• 2012

Passengers and mounted equipments on a vehicle are exposed to the vibration when it is driven on the road. To minimize the vibration and improve the dynamic characteristics of a vehicle are important factors. Those are changed by modifying parameters of the vehicle. To save development cost and time, simulation methods using vibration model have been widely used before making the real vehicle. In this paper two aimed functions, displacement between wheels and the body and acceleration of the body, have been defined for the parameter sensitivity analysis of the large vehicle. Full Vehicle Model having 11 degrees of freedom applied to solve those issues.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.153-158
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• 2014

The food waste that occurs in one year is very high in our country and disposal is expensive. However, disposers for food waste are not used wisely at real life. This is because most of them some kind of problem, for example big volume, complicated construction, high cost, lots of troubles, low energy efficiency and so on. In this study, we propose the new dryer system to decrease drying times by injecting hot air in down the side of the drying bucket. The designed drying bucket has inclined inlet holes down both sides. The inlet holes have variable gradients, we adjust the inlet velocity of the hot air to find a suitable vortex in the drying bucket. We verify the properties of the proposed system though simulation. The results show the proposed dryer system can improve the drying time and save energy for food waste disposal.

• Journal of Korean Society of Water and Wastewater
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• v.20 no.2
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• pp.303-309
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• 2006

Yongdam reservoir located in Jeoliabuk-do has had a lot of concerns for its algal blooming since it has started to fill water. Many water utilities near Yongdam area use reservoirs even though they have some problems with certain algae that cause tastes and odors and clog filters. In this research, dissolved air flotation (DAF) technology was examined for feasibility for removal of algae. OAF can save the capital cost for its compactness, because its hydraulic loadings (overflow rates) are 10 times higher than sedimentation, and hydraulic detention times are much shorter, typically 5 to 15 minutes. As a result of this research, PAC is effective rather than Alum to DAF for pretreatment. Higher DOC plays an important role to change zetapotential negatively to inhibit destabilization of particle to coagulation. The length of pipeline to carry pressurized water into reactor does not affect reaction.