• Archives of Plastic Surgery
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• v.43 no.1
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• pp.3-9
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• 2016

The reconstruction of the mandible is a complex procedure because various cosmetic as well as functional challenges must be addressed, including mastication and oral competence. Many surgical techniques have been described to address these challenges, including non-vascularized bone grafts, vascularized bone grafts, and approaches related to tissue engineering. This review summarizes different modifications of the free vascularized fibula graft, which, since its introduction by Hidalgo in 1989, has become the first option for mandibular reconstruction. The fibula free flap can undergo various modifications according to the individual requirements of a particular reconstruction. Osteocutaneous flaps can be harvested for reconstruction of composite defects. 'Double-barreling' of the fibula can, for instance, enable enhanced aesthetic and functional results, as well as immediate one-stage osseointegrated dental implantation. Recently described preoperative virtual surgery planning to facilitate neomandible remodeling could guarantee good results. To conclude, the free fibula bone graft can currently be regarded as the "gold standard" for mandibular reconstruction in case of composite (inside and outside) oral cavity defects as well as a way of enabling the performance of one-stage dental implantation.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1996.06a
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• pp.35-46
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• 1996

The powder forging process offers beneficial material utilization as well as the minimization of finishing operations over that of conventionally forged rods. In the present work, the sintering behavior of Fe-2Cu-0.6C-0.35MnS, optimum preform design and forgeability of various forging conditions were investigated. This data were generated using a newly proposed sub-scaled con-rod specimen developed specifically to simulate the powder forging process. The results of present work, powder perform is so difficult to flow material into die cavity and mass flow has no effect on improving the strength. And, applied force to increase density of the specimen flowed material is greater than that of all repessing mode. On the contrary, the specimen flowed material became increased hardness of inside in contrast with all repressing mode, but the tensile strength were decreased with residual porosity in surface. Due to material flow characteristic of powder preform, the section of lower density in powder preform became also lower density in forged con-rod. So, preform design is very important in manufacturing powder forged connecting rod.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.9
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• pp.1297-1305
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• 2004

Reliability of MEMS devices is receiving more attention as they are heading towards commercial production. In particular are the reliability and long-term stability of wafer level vacuum packaged MEMS gyroscope sensors subjected to cyclic mechanical stresses at high frequencies. In this study, we carried out several reliability tests such as environmental storage, fatigue, shock, and vibration, and we investigated the failure mechanisms of the anodically bonded vacuum gyroscope sensors. It was found that successful vacuum packaging could be achieved through reducing outgassing inside the cavity by deposition of titanium as well as by pre-taking process. The current gyroscope structure is found to be safe from fatigue failure for 1000 hours of operation test. The gyroscope sensor survives the drop and vibration tests without any damage, indicating robustness of the sensor. The reliability test results presented in this study demonstrate that MEMS gyroscope sensor is very close to commercialization.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.12 no.3
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• pp.7-12
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• 2013

In Die casting process, the problem of die degradation is often issued. In oder to increase of die life the material degradation of die steel was investigated using test core pins. Three test core pins were positioned in front of the gate entry and observed washout and soldering resistance during Mg die casting process. The test parameters are set as different commercial die materials, coatings condition and hardness of die surface. Usign 220t magnesium die casting machine was employed to cast AZ91 magnesium alloys. After 150 shots, macroscopic observation of die surface was carried out. Additional 50 cycles later, test pins were chemically cleaned with 5% HCl aqueous solution to find out the existence of washout and soldering layers. Microstructural characterization of die surface and the die roughness measurement were performed together. Computational simulation using AnyCasting program was also beneficial to correlate the extent of die damage with the position of test pin inside die cavity. As results, the optimal combination of die steel with productive coating as well as its hardness was drawn out. it will be helpful to decide the material and condition considering increasing of tool life.

• Tribology and Lubricants
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• v.22 no.4
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• pp.218-224
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• 2006

The sludge oils were produced necessarily in the ships operation, so that it will be the best way to manage the sludge oils inside ship itself from a viewpoint of the prevention of marine oil pollution. The ultra-sonic breaking system which recycle the sludge oil from ship into usable oil to be brunt is recognized as a most possible recycling device. In this regards, the purpose of this study is to examine erosion damage,on the SS400 specimen by cavitation and the effect of impact pressure generated from the demolition of the cavity of ultrasonic vibration in the marine sludge oil environment.. The erosion damage of specimen was investigated mainly on weight loss, weight loss rate and maximum erosion rate with variation of the oil temperature as well as the change of space between transducer hem and specimen. The experimental results showed that as the space between ultrasonic vibrator horn and specimen disk increased, the weight loss and weight loss rate decreased and the values were larger in SFO than in SLO. The experimental results can be useful to the development of sludge oil disposing systems and to consider a countermeasure for the prevention of erosion damages by cavitation.

• Proceedings of the KOSOMBE Conference
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• v.1990 no.05
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• pp.1-6
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• 1990

A new version of moving actuator electromechanical total artificial heart was designed to improve total efficiency, durability, and fitting inside thoracic cavity. As compared with our present type of the rolling cylinder actuator, this new model has a pendulum-type actuator with reciprocating motion around the fixed circular path, connected through the gear mechanisms to the motor. By using this mechanism, the efficiency and durability could be improved by replacing sliding mechanism with rolling contact elements. Also, the height of the pump could be decreased from 9cm to 7cm with static stroke volume 65cc. With these improvements, we have implanted this new pump in human size animal (less than 70Kg weight).

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.786-791
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• 2007

Aerodynamically generated noise is dominant when the train speed approaches 300km/h. This noise sources is caused by the turbulent flow separations or vortex shedding from the train structure. Experiments were performed to investigate the characteristics of aerodynamic noise sources generated from exterior of the KTX trains and HSR-350x, especially from the inter-coach spacing. Measurements of both the inside and outside of the cabin are carried out to investigate the characteristics of the noise. Effect of the size of the mud-flap has been investigated through an wind tunnel test and it has been found that the low frequency noise is strongly dependent on the size of the gap. Also performed is an array measurement to locate different noise sources from the high-speed train. spectral characteristics of exterior noise sources are examined.

• Korean Journal of Optics and Photonics
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• v.11 no.4
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• pp.250-254
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• 2000

We have constructed laser Doppler velocimetry system using self-mixing effect with a semiconductor laser. This technology is based on the frequency mixing phenomena which occurs when light scattered back from the moving object into the laser cavity interferes with light inside the laser. We have compared the value of Doppler shifted frequency with the velocity variation of the wheel. Frequency dependence on the angle between the moving direction of rotating aluminum wheel and the incident beam also have been proved. As an illustration of the performance of the velocimeter, velocity measurements of a rotating disk are described. Doppler signal shows a good linear relationship with velocity of rotating disk.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.4
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• pp.322-327
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• 2013

Recently many people have been troubled with perennial allergic rhinitis. But there is no way to cure for root of it until now. Therefore many medical treatments to release symptoms of perennial allergic rhinitis have been researched. One of them is localized aerosol hyperthermia, which injects $42^{\circ}C{\sim}43^{\circ}C$ vapor into nasal cavity. Vapor inhalator for localized aerosol hyperthermia has been researched in foreign country. But on the other hand it has rarely been researched inside of the country. Since most clinics and hospitals have used imported vapor inhalator, it is needed to develop domestic vapor inhalator. In the paper, a superior vapor inhalator compared to former developed one is developed. The superiority of it comes from direct-vapor heating instead of water heating to control vapor temperature. The developed vapor inhalator has shorter rising time than the existing one because of direct-vapor heating. Furthermore vapor generation part and control part of the vapor inhalator developed as one piece mock-up. It enables the vapor inhalator to have smaller size. Many laboratory tests are performed and compared to existing results to prove its performance.

• Korean Journal of Adult Nursing
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• v.16 no.3
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• pp.452-459
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• 2004

Purpose: To investigate the effect of oral care either with normal saline or with tantum solution on the oral state of the patients in intensive care unit as well as the frequency of bacteria occurrence inside their oral cavities. Method: The study was performed from March thru May of 2003 on the nonequivalent control group non-synchronized quasi-experimental design. Forty subjects were selected for each group. The data were analyzed using the SPSS 10.0 Win. The pre-experimental homogeneity and post-experimental differences between the two groups were analyzed with t-test. Result: There was a significant difference in the oral cavity state between the experimental group that had used normal saline and the control group that had used tantum solution. Conclusion: Based on the results described above, it is considered that normal saline is more effective than the tantum solution for the oral care of the patients in intensive care unit.