• Archives of Reconstructive Microsurgery
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• v.25 no.1
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• pp.1-6
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• 2016

Purpose: The external ear is a common area of trauma on the body prone to exposure of ultraviolet light, which can lead to skin cancer. Thus, variable techniques have been developed and used for reconstruction of the external ear. The aim of this study is to review the surgical method, its area of application, as well as advantages and pitfalls of reconstruction of the external ear with inferior based retroauricular flaps. Materials and Methods: Eight patients underwent external ear reconstruction with inferior based retroauricular flap for external ear defects in our institute from September 2012 to June 2015. According to the area of the defect, patients were classified as middle 1/3 (n=4), inferior 1/3 (n=2), superior auroculo-cephalic sulcus (n=1), and external auditory canal (n=1). Results: All of the flaps survived the operation and there was no marginal necrosis. Mean size of the defect was $2.8{\times}1.8cm$ and mean size of the retroauricular flap was $5{\times}2cm$. For insetting of the flap, a subcutaneous tunneling technique was used in 6 cases and rotation without subcutaneous tunneling was used in 2 cases. Transient paresthesia occurred in 3 cases. Two cases recovered within 3 months but one case did not recover until 6 months. Conclusion: The inferior based retroauricular flap is an available technique in external ear reconstruction with one stage operation.

• The KSFM Journal of Fluid Machinery
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• v.2 no.1 s.2
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• pp.7-14
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• 1999

This simulation method is developed by using GateCycle code for the performance evaluation of the gas turbine in IGCC(Integrated Gasification Combined Cycle) power plant that uses clean coal gas fuel derived from coal gasification and gas clean-up processes and it is integrated with ASU(Air Separation Unit). In the present simulation method, thermodynamic calculation procedure is incorporated with compressor performance map and expander choking models for considering the off-design effects due to coal gas firing and ASU integration. With the clean coal gases produced through commercially available chemical processes, their compatibility as IGCC gas turbine fuel is investigated in the aspects the overall performance of the gas turbine system. The predictions by the present method show that the reduction of the air extraction from gas turbine to ASU results in a remarkable increase in the efficiency and net power of gas turbines, but it is accompanied with a shift of compressor operation point toward to surge limit. In addition, the present analysis results reveal the influence of compressor performance characteristics of gas turbine have to be carefully examined in designing the ASU integration process and evaluating the overall performance parameters of the gas turbine in IGCC Power plant.

• Nuclear Engineering and Technology
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• v.33 no.2
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• pp.175-183
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• 2001

Various welding processes are now available for end cap closure of nuclear fuel element such as TG(Tungsten Inert Gas) welding, magnetic resistance welding and laser welding. Even though the resistance and TIG welding processes are widely used for manufacturing commercial fuel elements, they can not be recommended for the remote seal welding of a fuel element at a hot cell facility due to the complexity of electrode alignment, difficulity in the replacement of parts in the remote manner and a large heat input for a thin sheath. Therefore, the Nd:YAG laser system using optical fiber transmission was selected for Zircaloy-4 end cap welding inside hot cell. The laser welding apparatus was developed using a pulsed Nd:YAG laser of 500 watt average power with optical fiber transmission. The weldability of laser welding was satisfactory with respect to the microstructures and mechanical properties comparing with TIG and resistance welding. The optimum operation processes of laser welding and the optical fiber transmission system for hot cell operation in a remote manner have been developed The effects of irradiation on the properties of the laser apparatus were also being studied.

• Solar Energy
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• v.18 no.3
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• pp.81-87
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• 1998

Solar energy has been experiencing renewed interest because of the recent economical crisis in Korea. Absorption cooling is one of the promising solar energy utilization technologies. In this study the dynamic performance of a solar driven absorption cooling machine(SDACM) was numerically investigated. The simulated machine is a commercially available water/LiBr single effect absorption chillers driven by hot water from solar collectors. The present study has been directed to investigate the dynamic behavior of a solar cooling system including an absorption chiller, solar collector, a hot water storage tank, fan coil units, and the air-conditioned space. The operation of the system was simulated for 9 hours in varying operation conditions. The variation of temperature and concentration in the system components, and that of heat transfer rates in the system were obtained. It was also found that the room temperature was maintained near the desired value by controlling the mass flow rate of hot water.

• The Journal of Korean Medicine Ophthalmology and Otolaryngology and Dermatology
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• v.17 no.3
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• pp.88-94
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• 2004

Hemifacial spasm is painless uncommon disorder characterized by involuntary paroxysmal movement of one side face. In the treatment of hemifacial spasm, the Western operation or non-operation therapy has many side effect such as hearing loss, exudative otitis media, facial paralysis etc. So we studied mainly the effect of cause, treatment frequency, diseased part of 29 cases with hemifacial spasm for effective clicical application of oriental medicine. The results of study are as follow; 1. It shows more female patients than male patients, and mostly patients in their forties. 2. The diseased part is shown more on left side than right side, and the left side hemifacial spasm is cured more effective. 3. The causes of hemifacial spasm are mainly stress, ignorance, overwork, and the stress, a cold are more effective causes than ignorance in. 4. The disease period is mainly within six months, and that period is the most effective time. 5. The palpebral site is the most frequent site, ineffective site. 6. The effect go with the treatment frequency is not available. 7. There is a 55 percent improvement of 29 cases.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.702-707
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• 2008

BTL projects for educational facilities were conceived in 2005 to supply public facilities in a timely and efficient manner After the projects were completed in March 2007, proper facility maintenance has become an increasingly important issue. However, BTL projects are still in an early developmental stage, and the data on the maintenance and operation of such facilities are not yet available because the operation of the facilities has just begun. Accordingly, this study is conducted to derive maintenance processes and to specify maintenance items for the efficient maintenance of BTL educational facilities. Then, database on the maintenance processes will be created, and a maintenance system module will be designed.

• Journal of the Korean Operations Research and Management Science Society
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• v.39 no.2
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• pp.37-48
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• 2014

Fighter squadron flight scheduling is the integrated air operation plan that is an important role for improving pilot's flight skill and maintaining combat readiness by efficient using available all air resources including pilot, aircrafts, air-weapons, fuel and supporting facilities etc. Korea airforce, however, has a limit as to an effective flight operation due to manual flight scheduling with scheduler's own experience and intuition. Therefore, in our study, we propose the optimization model of flight scheduling based on mixed integer programming. This model includes several constraints of realistic and essential quantified data related with flight schedule and can assign appropriate pilots optimally which are distinctive three type's solutions : flight, alert and duty crew schedules. Proposed solution method can be improved pilot's capability and allocated further air resources systematically and efficiently. In addition, it can be reduced a workload of flight scheduler and minimized obstructed factors of flight safety. Finally, we demonstrate the experiment's results for the check of efficiency and validity of this model.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.2
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• pp.74-83
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• 2018

It is very crucial activities that Korean army have to detect and recognize enemy's locations and types of weapon of their artillery firstly for effective operation of friendly force's artillery weapons during wartime. For these activities, one of the most critical artillery weapon systems is the anti-artillery radar (hereafter; radars) for immediate counter-fire operations against the target. So, in early wartime these radar's roles are very important for minimizing friendly force's damage because arbiters have to recognize a several enemy's artillery positions quickly and then to take an action right away. Up to date, Republic of Korea Army for tactical artillery operations only depends on individual commander's intuition and capability. Therefore, we propose these radars allocation model based on integer programming that combines ArcGIS (Geographic Information System) analysis data and each radar's performances which include allowable specific ranges of altitude, azimuth (FOV; field of view) and distances for target detection, and weapons types i.e., rocket, mortars and cannon ammo etc. And we demonstrate the effectiveness of their allocation's solution of available various types of radar asset through several experimental scenarios. The proposed model can be ensured the optimal detection coverage, the enhancement of artillery radar's operations and assisting a quick decision for commander finally.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.3
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• pp.352-357
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• 1996

Recently, Permanent Magnet Synchronous Motor(PMSM) drives are widely used for industrial applications due to its high efficiency and high power factor control strategy. PMSM generally have two classifications such as the SPMSM(Surface Permanent Magnet Synchronous Motors) and IPMSM(Inter Permanent Magnet Synchronous Motors). IPMSA has economical merits over SPMSM in higher speed range, mechanical robustness, and higher power rate by the geometric difference. The maximum torque operation in IPMSM is realized by the current angle control which is to utilize additional reluctance torque due to a rotor saliency. In traction, spindle and compressor drives, constant power operation with higher speed range are desirable. This is simply achieved in the DC motor drives by the reduction of the field current as the speed is increased. However, in the PMSM, direct control of the magnet flux is not available. The airgap flux can be weakened by the appropriate current angle control to demagnetize. In this paper, the control method of optimal current vector in IPMSM is described in order to obtain the maximum torque or maximum output with the speed and load variations. The applied algorithm is realized by the proto system with torque and speed control Experimental results show this approach is satisfied for the high performance servo applications. (author). 6 refs., 9 figs., 1 tab.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2434-2439
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• 2008

This paper was studied on the cavitation instability of a Solution Pump Inducer in an absorption chiller-heater. Inlet pressure of LiBr and rotational speed at nominal mode are 2,800 Pa and 3,500 rpm respectively. Due to the marginal operation of available NPSH, the cavitation performance of the inducer is critical for the stable operation without the deterioration of head performance. In the study, cavitation performance and its mode of instability was investigated experimentally. Water was used as the working fluid and the test inducer was scaled up as 1.75 times for detail measurements and flow visualization. Inlet pressure was controlled by a vacuum pump. This research focused on types of cavitation instability and phenomena to investigate the possibility of harmful damage due to cavitation instability. Casing wall pressure and instantaneous inlet pressure was measured to observe the unsteady flow characteristics. Through the visualization and spectrum analysis of pressure, the occurrence region and intensity of asymmetric cavitation and cavitation surge are analyzed in the test inducer.