http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
정대한,정훈,류은웅,박철언,변재용,여승근,박문서 대한이비인후과학회 2010 대한이비인후과학회지 두경부외과학 Vol.53 No.5
Background and ObjectivesZZIt is essential to understand gas physiology of mastoid cavity to study the pathophysiology of middle ear diseases, and the surface area and volume of mastoid mucosa are important parameters for evaluating gas physiology. However, the surface area and mastoid volume of the mastoid cavity have not been practically measured yet. Therefore, we measured and compared surface area and volume of the mastoid cavity before and after mastoidectomy using a virtual mastoidectomy model. Subjects and MethodZZWe performed a virtual mastoidectomy using 10 cases of temporal bone CT indicating pneumatic mastoid. First, we removed all air cells after outlining with irregular AOI function after loading axial CT images to Image-Pro Plus 4.0. Then we filled the removed area with equal planes using local equalization filter. Finally, we calculated and compared the total surface area, volume and area to volume (A/V) ratio by estimating their circumference and area. ResultsZZThe mean surface area of pneumatized mastoid cavity was 127.8 cm2 (range: 94.2-165.3 cm2), and the mean volume was 7.1 cm3 (range: 5.2-11.0 cm3). The mean surface area and volume were altered to 42.8 cm2 (range: 35.9-55.0 cm2) and 12.6 cm3 (range: 10.3-18.7cm3), respectively, after virtual mastoidectomy. As a result, the A/V ratio decreased from 18 to 3.4 after a virtual mastoidectomy in the pneumatic mastoid cavity. ConclusionZZWhen a complete mastoidectomy is performed in the pneumatic mastoid, the surface area is decreased by one third compared to a relatively minor increase in volume. Therefore,the surface area per unit volume is expected to greatly decrease after mastoidectomy. Some physiologic problems occurring after mastoidectomy could be more accurately explained using a virtual mastoidectomy model. Korean J Otorhinolaryngol-Head Neck Surg 2010;53:284-9
T-103 훈련기의 환기와 난방 시스템 개선에 관한 연구
정대한,Jung, Daehan 한국군사과학기술학회 2013 한국군사과학기술학회지 Vol.16 No.3
In this paper, the ventilating and heating system of T-103 trainer aircraft were investigated and redesigned to improve its poor performance. The ventilation system of the trainer was designed to increase the mass flow rate of fresh air by using air intake valves. The flow-in air through the air intake valve is supplied to the cabin by the ram effect of aircraft and the propeller. And the additional heating system was installed to improve the temperature of the cabin inside. The wasted heat from the exhaust gas of the engines was used as heat source of the additional heating system by installing an heat exchanger around the exhaust nozzle. The additional fresh air and the heated air enter the cabin via two ducts mounted under the instrument panel and behind the pedal in the cabin. The additional ventilating and heating system can be controlled by the first pilot and the secondary pilot individually using the control knob equipped separately. After mounting the additional ventilating and heating system, evaluations such as inspection of parts and component, ground run-up test, in-flight test, user test, etc. were conducted. The result of the tests was sufficient to meet the requirements of the manuals, and the pilots were satisfied with the additionally mounted systems.
날아가는 섬광탄이 연료탱크 수평핀에 미치는 복사열전달 연구
정대한,강치행,김시태,Jung, Daehan,Kang, Chihang,Kim, Sitae 한국군사과학기술학회 2014 한국군사과학기술학회지 Vol.17 No.2
In this paper, the effect of unsteady radiation on the horizontal fin of an external fuel tank by flame of a flying flare was analysed to see the temperature increase of the fin and the thermal impact on the fin. Radiation between two surfaces was calculated using the concept of radiation resistance of surface and space including radiation, irradiation and shape factor for two flying trajectories of a flare, maximum temperature of 2200 K, emissivity of 0.95, flying velocity of 30 m/s, and thermal surface area of $0.01m^2$. The result shows that the temperature increase of the fin is 0.236 K, and the thermal effect on the fin is ignorable. And it was found that temperature is increased a little because small amount of heat energy can be radiated due to the short exposure time to the heat source.
인발공정에 의해 강소성 가공된 AA1070선재의 미세조직 및 기계적 특성
정대한,이성희,Jeong, Dae-Han,Lee, Seong-Hee 한국재료학회 2020 한국재료학회지 Vol.30 No.6
A commercial AA1070 alloy for electrical wire is severely deformed by drawing process in which a rod with an initial diameter of 9mm into is reduced to a wire of 2mm diameter. The drawn AA1070 wire is then annealed at various temperatures from 200 to 450 ℃ for 2h. Changes in microstructure, mechanical properties and electrical properties of the specimens with annealing temperature are investigated in detail. The specimen begins partially to recrystallize at 250 ℃; above 300 ℃ it is covered with equiaxed recrystallized grains over all regions. Fiber textures of {110}<111> and {112}<111> components are mainly developed, and {110}<001> texture is partially developed as well. The tensile strength tends to decrease with annealing temperature due to the occurrence of recovery or/and recrystallization. On the other hand, the elongation of the annealed wire increases with the annealing temperature, and reaches a maximum value of 33.3 % at 300 ℃. Electric conductivity of the specimens increases with annealing temperature, and reaches a maximum value of 62.6 %IACS after annealing at 450 ℃. These results are discussed in comparison with those for the other aluminum alloy.