• Journal of the Korean Society of Mechanical Technology
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• v.13 no.1
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• pp.113-118
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• 2011

To analyze and verify the effect of replacing thermal storage heater by a cascade cycle heat pump using midnight electricity was installed and tested at a customer's house in Wonju, Korea. The electric night storage heater is consist of 30kW electric heater and 2,700 liters of thermal storage water tank to supply hot water for warming house floor. The power for electric heater was cut off and hot water was only generated by cascade cycle heat pump. Current thermal storage water tank was not eliminated and electric heater wiring was modified. Some operation logic of the heat pump was also modified for proper operation. The required capacity of the heat pump and hot water temperature for given warming condition were estimated. The estimated capacity of heat pump was about 19kW and estimated hot water temperature for proper heating was at least $75^{\circ}C$.

• Design & Manufacturing
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• v.2 no.5
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• pp.43-47
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• 2008

Micro Electrochemical Machining(Micro ECM) has traditionally been used in highly specialized fields such as those of the aerospace and defense industries. It is now increasingly being applied in other industries where parts with difficult-to-cut material, complex geometry and tribology such as compute. hard disk drive(HDD) are required. Pulse Electrochemical Micro-machining provides an economical and effective method for machining high strength, high tension, heat-resistant materials into complex shapes such as turbine blades of titanium and aluminum alloys. Usually aluminum alloys are used bearings to hard disk drive in computer. In order to apply aluminum alloys to bearing used in hard disk drive, this paper presents the characteristics of Micro ECM for aluminum alloy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2001.04a
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• pp.956-959
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• 2001

In die and mould industry, major material such as cemented carbide is broadly used for increasing the life time and decreasing the cost. It is also required the development for the skills of wire-cut electrical discharge machining(WEDM), but the WEDMed surface was found to be worst due to the attached components of wire. Precision machining method like lapping is necessary for obtaining high quality surface. The lapping compound such as Al2O3 and SiC and cast iron lap can be used for lapping process. The components of Cu and Zn were found WEDMed surface of the specimen. As the result, the low quality of precision was obtained and the heat damage layer of the specimen was occurred. The value of surface hardness was deteriorated, and therefore finish process was required.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2005.10a
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• pp.109-112
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• 2005

Friction welding is welding method to use frictional heat of two material. A defect of friction welding is that create flash. The flash is part that must have cut after welding finished. But the welding part with flow gallery by friction welding can't cut flash. Therefore the welding part with flow gallery was designed with no effect in flow. In this research, decide the welding shape parameter of welding part with flow gallery and do friction welding analysis. In friction welding analysis, must input necessary S-S curve, friction coefficient by temperature change, upset pressure, RPM etc. According to analysis result, decided the optimal shape of welding part with no effect in flow.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.214-217
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• 2002

Micro Surface Electrochemical Machining has traditionally been used in highly specialized fields such as those of the aerospace and defense industries. It is now increasingly being applied in other industries where parts with difficult-to-cut material, complex geometry and tribology such as compute. hard disk drive(HDD) are required. Pulse Electrochemical Micro-machining provides an economical and effective method for machining high strength, high tension, heat-resistant materials into complex shapes such as turbine blades of titanium and aluminum alloys. Usually aluminum alloys are used bearings to hard disk drive in computer. In order to apply aluminum alloys to bearing used in hard disk drive, this paper presents the characteristics of Micro Surface Electrochemical machining for aluminum alloy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.109-114
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• 1992

This paper describes an effect of operating condition on surface roughness in wire-cut FDM. The experimental values of surface roughness were measured by the test pieces under the condition of changing. On time, Off time, and Feed rate after fixing other conditions. The material of the test pieces is the alloy tool steel(STD 11) and was used after heat treatment. The results are as follows: 1. The surface roughness became rapidly worse according to the increase of On time and Feed rate. 2. The surface roughness became slowly better according to the increase of Off time.

• Transactions of Materials Processing
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• v.15 no.8 s.89
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• pp.539-543
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• 2006

Experimental studies are carried out in order to investigate the effects of heat treatment on the surface machined by W-EDM. In this work, two ways of heat treatment after W-EDM are considered. As a comparison, the machined surface by a traditional method such as milling/grinding is also considered. Thereby, specimens are prepared by four different machining methods. Those are (1) milling and then grinding, (2) wire-cut electric discharge machining (W-EDM), and (3) low temperature heat treatment or (4) high temperature heat treatment after W-EDM. The resulting surface roughness are measured and the changes of surface microstructures are investigated using the scanning electron microscope (SEM) with energy dispersive X-ray spectrometer (EDS). In general, heat treatment after W-EDM result in smoother surface and better chemical composition at the machined surface. Especially, high temperature tempering could remove defects in the thermally affected zone, which cause an overall deterioration of the surface machined by W-EDM.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.947-951
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• 2002

During the hotwire cutting of EPS foam sheet, the dimensional accuracy and part quality of the cut par are highly dependent upon the thermal field in the EPS. The thermal field is determined by operating parameters such as heat input, cutting speed and cutting angle. The objective of this study is to investigate into the influence of cutting angle on the kerfwidth and part quality of the cut part in hotwire cutting of EPS foam using the experiments and the numerical analysis in the case of a single sloped cutting. In order to estimate an accurate temperature field, the transient thermal analysis using a moving coordinate system and the sloped heat flux model is carried out. From the results of the experiments and the analysis, it has been found that the effect of cutting angle on the kerfwidth and the melted area at the edge are 0.1 mm and 0.11 m$m^2$ respectively. The results of the experiments show that the surface roughness is not appreciably influenced by the cutting angle.

• Journal of the Korean Society of Combustion
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• v.22 no.1
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• pp.32-38
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• 2017

This paper shows the dynamics of the Burke-Schumann flame. To show flame dynamics, this paper measures the flame surface and heat release rate. The flame shape is divided into three types with forcing frequencies. When the forcing frequency is lower than 120 Hz, the upper region of flame is cut. The flame is stagnant with 220 to 280 Hz forcing frequencies. The rest conditions of forcing frequencies make the connected wave shape of flame. The heat release rate is expressed by the flame transfer function. The gain of the flame transfer function is similar with the oscillation magnitude of the flame area except for flame cutting conditions. The flame is cut because the fuel is not supplied to upper flame region.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.85-90
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• 2009

Although most of existing hydration heat control methods show a certain degree of hydration heat control, generally, there are many problems as mentioned above. Therefore, our laboratory previously developed a hydration heat control method using an exposed heat pipe, which solves most of these problems and simultaneously displays excellent hydration heat control. Unfortunately, even this method had some problems such as the processing, transport, and assembly of heat pipes, and the surface treatment of a cut plane after pouring, and hardening concrete. Therefore, in this study, a hydration heat control method using an embedded pipe has been developed with the expectation that this method solves those problems in hydration heat control using an exposed heat pipe. As a result of the experiment, the peak temperature of ECHP and ICHP specimen about $4.5{\sim}6.5^{\circ}C$ than the OPC specimen and the probability of thermal cracked generated in ECHP and ICHP specimen decreased up to $13{\sim}20%$. Finally, it was confirmed in this study that the hydration heat control method using an embedded heat pipe is significantly more superior and cost effective than the existing method of an exposed one.