• Journal of Energy Engineering
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• v.12 no.1
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• pp.17-22
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• 2003

The present study was conducted to obtain the fundamental knowledge on the manufacturing and operating characteristics of a small scale CPL (Capillary Pumped Loop) heat pipe. CPL heat pipes are able to transfer heat effectively at any orientation in a gravitational field over long distances. An experimental model with an evaporator of a circular plate shape was designed and manufactured and its operating performances were tested. A Bronze powder sintered metal plate of 3 mm thick and $\Psi$ 50 mm was used as wick and ethanol was used as working fluid. An experimental apparatus was set up to ascertain the operating conditions oi CPL at different heat load and an surrounding temperature at the condenser was maintained about 13$^{\circ}C$.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.27 no.4
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• pp.244-249
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• 2014

In this research, it have developed a sensor that could diagnose inner deterioration of covered wires. With this sensor it observed results from simulation, and the attribute required for realization. For simulation it have used FLUX, it have considered all of geometric and electromagnetic information from coil and base metal that influences eddy current sensor's property in order to predict the final result. It assumed there is no mutual inductance in the coil with N number of turns, because equivalent current flows in coil that is continuously connected in eddy current sensor. It assumed circular coil loop draws a circle, always have self inductance, and they are connected in series and overlapped according number of turns (N) in coil, and bobbin configuration. Actual sensor was produced with consideration of inductance and number of turns (N). In conclusion, it were able to test the dependency through results from simulation, actual measurement, and modeling of simulation. It is considered that attributes of respective base metal and structure can be predicted by simulating in advance.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.2
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• pp.181-188
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• 2015

This paper present, the result of the guidance and control law for a course correction munitions(CCM) with 2sets of canards positioned in the rotating nose section. The nonlinear simulation model of the CCM was developed based on 7DOF equation of motion. The ability of correcting position was verified by open-loop control input with nonlinear model. The guidance and control command was constructed by reference trajectory which can be obtained with no control. Finally, the performance of the guidance and control law was evaluated through Monte-carlo simulation. The CEP(Circular Error Probability) was obtained by considering the errors in muzzle velocity, aerodynamic coefficient, wind, elevation and azimuth angle and density.

• Journal of Veterinary Clinics
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• v.33 no.4
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• pp.210-213
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• 2016

A 9-year-old, mixed-breed, castrated male dog presented with a one-week history of severe vomiting. Abdominal radiography showed a dilated small intestine loop. Abdominal ultrasonography showed small-intestine distension up to 5 cm in diameter without mechanical obstruction. During exploratory laparotomy, an aperistaltic ileal segment was resected. There was no narrowed cavity in the resected plane. Histopathologic and immunohistochemical findings confirmed visceral myopathy due to intestinal adenocarcinoma in the ileum and revealed partial destruction of the longitudinal and circular muscles with fibrosis. Chronic intestinal pseudo-obstruction caused by adenocarcinoma was diagnosed after considering the above investigative results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.9
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• pp.820-826
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• 2011

In this paper, an efficiency improvement method in the wireless power transfer system based on magnetic resonance is proposed. A combined helical-spiral structure is adopted for self-resonant coil and source and device coils are designed using circular loop structure. The proposed resonator utilizing combined helical-spiral structure yields 13 % efficiency improvement over that of an existing helical type resonator when the transmitting and receiving coils are separated by 120 mm. In addition, the size can be reduced by 33 % comparing to the previous resonator.

• Journal of Institute of Control, Robotics and Systems
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• v.3 no.1
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• pp.32-39
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• 1997

One of the most important performance criteria in tuning the gain of position loop controller for CNC machining center is the contour error. In this papre we analyze contour error in the linear and circular interpolations for the axis-matched and mismatched cases. To have small contour errors, it is necessary to set the P gain for each axis to be same. And the D gain should be much smaller than the P gain. Baded on the analysis in the frequency domain, we propose a gain tuning method for the P and PD controllers. We show that the PD controller is better than the P controller. The effectiveness of this method is demonstrated by experiments.

• Nuclear Engineering and Technology
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• v.23 no.3
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• pp.328-339
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• 1991

A multi-purpose research reactor called KMRR has been developed by Korea Atomic Energy Research Institute(KAERI) to generate a maximum thermal output of 30 MW. As a part of thermal hydraulics study, pressure drop characteristics of the longitudinally finned fuel rod bundles were experimentally investigated in a recirculating water test loop. The present study is focused on the investigation of fin effects on pressure drop and the development of pressure drop correlation for the finned rod bundles in a wide range of flow conditions. Friction factor correlations for each design of the finned rod bundles are developed. The value of friction factor for the finned rod bundles was higher than the analytical solution (64/Re) of laminar circular channel new but became lower than the Blasius equation as Reynolds number was increased.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.2 s.179
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• pp.88-96
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• 2006

A gerotor pump is suitable for oil hydraulics of machine tools, automotive engines, compressors, constructions and other various applications. Especially the pump is an essential machine element of an automotive engine to feed lubricant oil. The subject of this paper is the theoretical analysis of the internal lobe pump which is a particular type of positive displacement pump. The main components of the pump are rotors; usually the outer rotor profile is characterized by lobes with circular shape, while the inner rotor profile is determined as conjugate as the outer rotor profile. For this reason the topic presented here is the definition of the geometry of the rotors starting from the design parameters. The choice of these parameters is subject to some limitations in order to avoid cusp and loop between rotors. And the integrated system which is composed of three main modules has been developed through AutoLISP & Visual Basic and CAD considering various design parameters. It generates automatically an designed model for a general type of a gerotor pump and allows us to calculate two performances indexes commonly used for the study of positive displacement pumps: the flow rate and flow rate irregularity. Results obtained using the system enable the designer and manufacturer of oil pump to be more efficient in this field.

• Korean System Dynamics Review
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• v.4 no.1
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• pp.69-91
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• 2003

Using qualitative methods hinged on urban dynamics models, the paper addresses major issues concerned with new administrative capital construction. It tries to summarize the existing debates on new administrative capital construction and reinterpret diverse interacting factors in terms of reinforcing or balancing feedback structure. The paper suggests that understanding up on the dynamic mechanism imbedded in circular causal loop diagrams is the key to set up appropriate proposals and action plans for the new administrative capital, as they would reveal complicated linkages between the Capital Region and the rest, in addition to the urban dynamic of new administrative capital. In the same context, the paper can confirm similar features reflected in the relocation of capital functions at Canberra, Australia and Berlin, Germany. It has paid special attention to the fact that both Australian and German governments altogether stress the positive feedback loops as they have overcome unprecedented political confrontation among rival cities: Basically, they have encouraged gives-and-takes among major stake-holders. These research findings indicate that the future of new administrative capital construction depends on consensus buildings that can accommodate socio-economic and territorial changes between pros and cons. Although further researches and validations are needed, the system approach presented in this paper could assist Korean decision-makers in developing robust and responsive policy initiatives under uncertainties.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.5
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• pp.1032-1043
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• 1989

The heat transfer characteristics of the drag reducing polymer solutions are investigated experimentally in the thermal entrance region of circular tube flows. Fluids used in experiments are the aqueous solutions of high molecular polymer, polyacrylamide Separan AP-273 and the range of polymer concentrations is from 20 to 1000 wppm. Two stainless steel tubes with inside diameter 8.5mm(L/D=712) and 10.3mm(L/D=1160) are used for the heat transfer flow loops. The flow loop is set up to measure friction factors and heat transfer coefficients of test sections in two different modes; the recirculating flow system and once-through flow system. The test tubes are heated directly by electricity to apply the constant heat flux boundary conditions to the wall. Three different types of adaptors are used to observe the effects of the upstream flow conditions of the heat transfer test sections. The viscosity and characteristic relaxation time of the test fluids circulating in the flow system are measured by the capillary tube viscometer and falling ball viscometer at regular time intervals. The installed adaptors exhibit slight effect on the entrance heat transfer of Newtonian fluid. However, no noticeable effects are observed for the entrance heat transfer of the drag reducing fluids. The order of magnitude of the thermal entrance lengths of the drag reducing fluids which follow the minimum friction asymptote is much longer than that of Newtonian fluids in turbulent flows. A new dimensionless parameter, the viscoelastic Graetz number, is defined and all the experimental data are recasted in terms of the viscoelastic Graetz number. The local Nusselt number of the viscoelastic fluids is represented as a function of flow behavior index n and the viscoelastic Graetz number. As degradation continues the viscosity and the characteristic relaxation time of the testing fluids decrease. Weissenberg number defined by the relaxation time and D/V appears to be a proper dimensionless parameter in describing degradation effects on heat transfer of the viscoelastic fluids.