• Journal of the Korean Society of Industry Convergence
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• v.21 no.5
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• pp.257-263
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• 2018

It is a small injection molding machine for table top considering the material heating mechanism and the design and structure stability by securing the mechanism that compresses the inside of the material heating tube by using the electric actuator and by providing space between the body and the material heating tube to reduce heat loss Develop body. An electric actuator suitable for applying pressure to the inside of a material heating tube is a mechanical system composed of a rigid structure. Since a large force is repeatedly applied to the electric actuator and the push rod, the interaction between the moving parts and the dynamic Maximum stress through analysis and prediction of fatigue life of critical parts The pushrod reflects the structural analysis results of the electric actuator and the push rod, and pushes the inside of the material heating tube by the push rod to inject the molten material from the nozzle into the mold. The pushrod operates by the operation of the electric actuator. The material heated by the coil heater is ejected through the nozzle by the pressure of the material heating tube, and the material heating tube and the nozzle are also lowered at the same time as the push rod is lowered, so that the material is closely adhered to the mold. We want to study the completion of the injection.

• Proceedings of the KWS Conference
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• 2010.05a
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• pp.60-60
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• 2010

Since the curved hull plate was made by a series of manufacturing process including cold bending, manual local heating and correction work, the accuracy of curved plate strongly depends on the proficiency of worker. So the demands on the automatic local heating system for curved hull plate have continuously increased and the various researches relevant to it have been performed. Generally, the heat sources used for local heating were flame and induction heat. In terms of initial cost, flame heating is in a better favorable position than induction heating. However, from the viewpoint of the control of heat, induction heating has more advantage. So the various researches related to apply the induction heating to the automatic forming system has been performed. The purpose of this study is to establish the proper capacity of high frequency induction heating system for forming the curved hull plate. In order to do it, the proper coil shape for local heating was designed and the efficiency of induction heating system was determined by comparing of temperature results obtained by FEA and experiment. With the results, the extensive FEA was performed to identify the effect of heated plate dimension, cooling method and the capacity of induction heating system on the amount of heat loss introduced by induction heating. Based on the results, the proper capacity of high frequency induction heating system was proposed.

• Journal of the Korea Furniture Society
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• v.22 no.1
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• pp.72-81
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• 2011

These days, beds have been developed not as furniture to sleep in but Healthcare Furniture. The function of heating, non-electronic-waves and far-infrared rays have been added. Also, eco-friendly materials such as stone, mud, rubber and wood are combined to them together with the radiation-heating method using heat conduction through electronic coil and hot water circulation. Modern people suffer from stress and fatigue. The hot issue is "health." Focused on the health, the development of design for beds considering the influence electronic waves, anions, deep sleep and the density of toxic materials have on human bodies has become urgent. In this study, the trend, specification and efficiency of the functional health-related electronic coil technology are analyzed. Through the analysis, the environmental standards are set. According to them, technology, eco-friendly materials and additional functions for the development of the design are considered. Also, the government is promoting the IEC international standardization for the Korean traditional floor heating style beds. In preparation for that, we adopted new HPT method technology. It enables non-electronic-waves, low electricity and stable temperature maintenance control for the warm top and the cool bottom. Also, the head boards and the frames of the beds can be separated. Through this separation, the beds can be easily moved or installed. Eco-friendly materials such as Hinoki cypress wood and red clay and the existing tables function are combined to the head boards so they can be used as drawers and display shelves. If they are used as separate items, they can be used as covers. This is how we suggest the design for the heating beds.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1359-1364
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• 2004

An experiment was performed to study the evaporation heat transfer and the pressure drop characteristics of liquid nitrogen in a horizontal stainless steel tube with wire coil inserts. The inner diameter of test tube is 4.3mm and the length is 1.5m. Four wire coils having different pitch and thickness were inserted into the plain test tube. The wire coil length is 1.5m and the diameter is 3.65mm with thickness of 0.5mm and 0.9mm. Experiments were conducted at saturation temperature of $-191^{\circ}C$ mass flux from 200 to 370 $kg/m^{2}s$ and heat flux of 62 $kW/m^{2}$. Direct heating method was used to apply heat to the test section. Boiling heat transfer coefficients of both the plain and the enhanced tubes were calculated. Pressure drops between inlet and outlet side of test section were also measured, and they are used to estimate EPR(Enhancement Performance Ratio).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.8 s.239
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• pp.927-933
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• 2005

Boiling heat transfer characteristics of liquid nitrogen in a stainless steel plain tube and wire coil inserted tubes were investigated. The test tubes, which had an inner diameter of 10.6 m and a length of 1.65 m, were horizontally located. Five wire coils having different pitch and thickness were inserted into the plain tube. The pitches of the wire coils were 18.4, 27.6, and 36.8 m, and the thickness was 1.5, 2.0, and 2.5 mm respectively. Tests were conducted at a saturation temperature of $-191^{\circ}$, mass fluxes from 58 to 105 kg/$m^2s$, and heat fluxes from 22.5 to 32.7 kw/$m^2$. A direct heating method was used to apply heat to the test section. The boiling heat transfer coefficients of liquid nitrogen were represented as a function of vapor quality, which showed significant drop at the dryout vapor quality. The maximum heat transfer enhancement using the wire coil inserted tubes over the plain tube was $174\%$ for 'Wire 3' having a thickness of 2.5 mm and a pitch of 18.4 mm.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.314-314
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• 2010

For the optimal design of a tokamak-type reactor, self-consistent determination of a radial build of reactor systems is important and the radial build has to be determined by considering the plasma physics and engineering constraints which inter-relate various reactor systems. In a low aspect ratio (LAR) tokamak reactor with a superconducting toroidal field (TF) coil, the shield should provide sufficient protection for the superconducting TF coil and the shield plays a key role in determining the size of a reactor. To determine the radial build of a reactor, neutronic effects such as tritium breeding in the blanket, nuclear heating, and radiation damage to toroidal field (TF) coil has to be included in the systems analysis. In this work, the outboard blanket only is considered where tritium self-sufficiency is possible by using an inboard neutron reflector instead of breeding blanket. The reflecting shield should provide not only protection for the superconducting TF coil but also improved neutron economy for the tritium breeding in outboard blanket. Tungsten carbide, metal hydride such as titanium hydride and zirconium hydride can be used for improved shielding performance and thus smaller shield thickness. With the use of advanced technology in the shield, conceptual design of a compact superconducting LAR reactor with aspect ratio of less than 2 will be presented as a viable power plant.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.9
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• pp.361-366
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• 2016

As an alternative of well-mixed storage tank with lower coil only, we have proposed a tank with lower and upper coils and verified a superior thermal stratification in a tank, which results in increased collector efficiency and solar fraction. But the phenomenon of temperature reversal was often experimentally observed in the tank, so a revised control was successfully applied which is to heat only lower coil using three way valve if temperature reversal occurs and to operate the collector with low flow rate when the condition of solar radiation is not good. In the present study, using TRNSYS we compared the existing lower heating and the proposed lower and upper heating with a control preventing temperature reversal. The results showed that the proposed method has an increase of collector efficiency by 5.1% and solar fraction by 3.2%.

• 한국태양에너지학회:학술대회논문집
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• 2009.11a
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• pp.291-296
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• 2009

This paper investigates the energy saving potentials of a dedicated outdoor air system (DOAS) applied to a highrise apartment building. As for a typical $132-m^2$ apartment unit, two different HVAC systems; centralized DOAS-Ceiling Radiant Cooling Panel and decentralized Energy Recovery Ventilator-Packaged Air Conditioner were installed. Transient behavior and control characteristics of each system were modeled numerically using a commercial equation solver program, and annual cooling coil load and heating load reduction potentials were compared. The research shows that DOAS-Ceiling Radiant Cooling Panel system can reduce the cooling coil load over 21% annually compared with the current Energy Recovery Ventilator-Packaged Air Conditioner pair. In addition, over 40% of annual ventilation heating load can be reduced by use of DOAS.

• Journal of Power Electronics
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• v.11 no.5
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• pp.632-638
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• 2011

This paper presents a cascaded coil flux control based on a Current Source Parallel Resonant Push-Pull Inverter (CSPRPI) for Induction Heating (IH) applications. The most important problems associated with current source parallel resonant inverters are start-up problems and the variable response of IH systems under load variations. This paper proposes a simple cascaded control method to increase an IH system's robustness to load variations. The proposed IH has been analyzed in both the steady state and the transient state. Based on this method, the resonant frequency is tracked using Phase Locked Loop (PLL) circuits using a Multiplier Phase Detector (MPD) to achieve ZVS under the transient condition. A laboratory prototype was built with an operating frequency of 57-59 kHz and a rated power of 300 W. Simulation and experimental results verify the validity of the proposed power control method and the PLL dynamics.

• Journal of Energy Engineering
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• v.23 no.2
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• pp.13-20
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• 2014

The natural convection heat transfers of a helical coil in a duct were measured experimentally varying the inclination. To achieve high Rayleigh number, mass transfer experiments instead of heat transfer experiments were performed based upon the analogy. The $Ra_D$ was fixed to $4.55{\times}10^6$. The turn numbers were 1~10. the pitch to diameter ratio were 1.3~5, and the inclination of the helical coil $0^{\circ}{\sim}90^{\circ}$. The measured $Nu_D$ for a single turn of the helical coil was very close to that from McAdams heat transfer correlation for a horizontal cylinder. The heat transfers of the helical coil were varied by the pith, number of turns, and duct height in a complex manner showing the velocity, chimney, and pre-heating effects. The results of the study contributes to the phenomenological analyses of the natural convection heat transfer of a compact heat exchanger.