• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.5C
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• pp.177-183
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• 2012

The use of energy pile foundation has been increased for economic utilization of geothermal energy. In particular, a coil-shaped ground heat exchanger (GHE) is preferred than conventional U-shaped heat exchanger to ensure better efficiency of heat exchange rate. This paper presents experimental results by changing different pitch spaces of spiral coils. Joomunjin sand was filled in a steel box of which the size was $5m{\times}1m{\times}1m$. Thermal response tests (TRTs) were conducted to measure the ground thermal conductivity with temperatures of circulating water using line source model and ring coil model. Experimental results and analytical solutions were compared to validate the applicability of these models. Ring coil model showed more accurate similar results with experimental data rather than line source model and cylindrical source model.

• Proceeding of EDISON Challenge
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• 2016.03a
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• pp.147-154
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• 2016

Co-nonsolvency is a puzzling phenomenon that a polymer swells in a good solvent individually, but it collapses in a mixture of good solvents. This structural transition with changing solvent environment has been drawing attention due to practical application for stimuli-responsive polymer. The aim of this work is to describe the physical origin of the co-nonsolvency. In this work, we present Monte Carlo simulations for polymer solutions by using simple and general model. We simulate linear and ring polymers to compare their co-nonsolvency behaviors. Calculating Flory exponents and bridging fractions gives a good description for polymer structures. While the polymer structure shows non-monotonous behavior with increasing the cosolvent fraction, the chemical potential decreases monotonously. This indicates that coil-to-globule transition of polymers is purely controlled by free energy and can be regarded as a thermodynamics transition. We also present that ring polymers have higher looping probability than linear polymers, thus the bridging fraction remains higher at high cosolvent fraction. Our study provides a new perspective to understand polymer structure when the polymer "dissolves well" in any solvent.

• Journal of Magnetics
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• v.18 no.2
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• pp.90-94
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• 2013

We designed a model composed of a ring type magnet, a yoke, and a sensing coil embedded in a projectile for simulating the muzzle velocity. The muzzle velocity was obtained from the master curve for the induced voltage at sensing coil and the velocity as the projectile pass through the magnetic field. The induced voltage and the projectile's velocity are fitted by the $2^{nd}$ order polynomial. The skin effect difference between projectiles which consist of aluminum-aluminum and aluminum-steel was small. The projectile will surely be burst at the pre-determined target area using the flight time and the projectile muzzle velocity calculated from the voltage induced at the sensing coil on the projectile.

• Journal of the Korean Magnetics Society
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• v.26 no.2
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• pp.62-66
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• 2016

We designed a model composed a ring type magnet, a yoke, and a sensing coil buried in a projectile for calculating the muzzle velocity based on the voltage induced from sensing coil by simulation. The muzzle velocity was calculated from the master curve obtained through the voltage induced from sensing coil by simulation. The induced voltage increased with increasing the diameter of sensing coil. The projectile's velocity was proportional to the induced voltage when the sensing coil was buried in projectile. The projectile will be surely exploded at the target region by inputting the information of muzzle velocity variation corrected the diameter effect of induced voltage of sensing coil.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1041-1046
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• 2004

A proportional pressure control valve has a nonmagnetic ring which is inserted in between a coil and plunger and it can get attraction force in proportion to input current by an influence of control cone. Therefore, a proportional pressure control valve is applied to a servo system as substitution of servo valve and an on-off solenoid valve widely because control of a high level is possible and pollution level is low. The purpose of this study is to develop domestic model of a proportional pressure control valve, and a test model was designed and manufactured through valve system analysis and finite element analysis. And comparison between results of theoretical analysis and static / dynamic characteristics test were carried out on a manufactured test model, and it was confirmed that it has excellent performance in comparison with other foreign products.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.5
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• pp.483-490
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• 2016

In plant industry, sulfur storage tank is made of steel and annular plate is connected with concrete foundation of ring wall type by anchor bolt. Due to keep sulfur at high temperature in tank by coil, sulfur storage tank is expanded larger than another tank stores fluid at room temperature. Generally, structural design of tank foundation is performed analysis with loading of temperature gradient between inner and outer surface, this method can't consider the phenomenon that load is intensively transferred to concrete foundation at anchor bolt. This means that temperature load is underestimated and causes crack of concrete near anchor bolt. In this study, evaluation formula considering temperature load transfer mechanism through anchor bolt is proposed and load acting on concrete foundation is rationally decided. For this purpose, it is analyzed variation of thermal load per various anchor bolt number using finite element model including tank annular plate and anchor bolt. Solution is proposed as specified term combining result of analysis and theoretical solution for evaluating load transferred by anchor bolt. For confirmation of validation of proposed formula, it is applied in design of sulfur storage tank at plant site, it shows that the formula can be practically applied.