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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
정대한,김상만,신귀현,노회은,이종인 경상대학교 농업생명과학연구원 2017 농업생명과학연구 Vol.51 No.2
The purpose of this study is to find methods of enhancing arboretum’s competitiveness and suggest efficient ways in making other arboretum afterwards by grasping decision factors that make people visit an arboretum operating in Korea. For this study it was conducted monova and discriminant analysis, multiple regression analysis. I researched the relationship between satisfaction and visitor’s characteristic, and then found there are some differences only in revisitors, though other factors had nothing to do with results. The satisfaction of facility and tour effect is higher in revisitors compared with first visitors. In the gender aspect, women were satisfied with the distinctive things more highly than men among five lower factors of satisfaction. Also, in the age group aspect, the overall satisfaction and satisfaction in the scenary were ranked higher from 20 to 30 than from 40 to 50. The findings will provide imformation on the satisfaction of the arboretum visitors and enhance arboretum’s competitiveness.
정대한,서미경,강호민,이준석,박문서,여승근 대한이비인후과학회 부산,울산,경남 지부회 2011 임상이비인후과 Vol.22 No.1
Background and Objectives:Stress is defined as excited state resulted from interaction of body and mind. It is subjective notion in that the amount of stress can be different in each person from same event. Nevertheless, there have been many studies to find objective measure to assess stress and many questionnaires have been developed. In our study, we tried to measure the amount of stress of representative diseases of Otorhinolaryngology and head and neck surgery using ‘Daily Hassless Scale’, one of well known stress questionnaire. Materials and Methods:276 people including 36 people of normal control, 20 patients of chronic sinusitis, 20 of laryngopharyngeal reflux, 20 of obstructive sleep apnea, 19 of nasal septal deviation, 20 of facial palsy, 20 of vocal nodule, 21 of allergic rhinitis, 20 of hearing disturbance, 20 of dizziness, 21 of tinnitus, 23 of chronic otitis media and 16 of preauricular fistula were enrolled to our study. They were made to fill up the questionnaire form when they visited our clinic. The questionnaire is composed of 36 questions and each is 4 point scale. We statistically compared total stress score and health related score. Results:Laryngopharyngeal reflux and allergic rhinitis patients group showed significantly higher stress score than control group (p=0.003). Laryngopharyngeal reflux, facial palsy, vocal nodule, allergic rhinitis patients group showed significantly higher score than control group in sum of four health related questions (p=0.000). Conclusion : Laryngopharyngeal reflux, facial palsy, vocal nodule, allergic rhinitis patients group were suffered from higher stress than other otolaryngology disesases and these shoud be considered during managing patients.
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.