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수직형 U자 관 지중 열교환기를 갖는 지열원 열펌프의 동적 시뮬레이션
이명택,김영일,강병하 대한설비공학회 2007 설비공학 논문집 Vol.19 No.5
GHX (Geothermal Heat Exchanger) design which determines the performance and initial cost is the most important factor in ground source heat pump system. Performance of GHX is strongly dependent on the thermal resistance of soil, grout and pipe. In general, GHX design is based on the static simulation program. In this study, dynamic simulation has been performed to analyze the variation of system performance for various GHX parameters. Line-source theory has been applied to calculate the variation of ground temperature. The averaged weather data measured during a 10-year period (1991~2000) in Seoul is used to calculate cooling and heating loads of a building with a floor area of 100m2. The simulation results indicate that thermal properties of borehole play significant effect on the overall performance. Change of grout thermal conductivity from 0.4 to 3.0W/(m℃) increases COP of heating by 9.4% and cooling by 17%. Change of soil thermal conductivity from 1.5 to 4.0W/(m℃) increases COP of heating by 13.3% and cooling by 4.4%. Change of GHX length from 100 to 200m increases COP of heating by 10.6% and cooling by 10.2%. To study long term performance, dynamic simulation has been conducted for a 20-year period and the result showed that soil temperature decreases by 1℃, heating COP decreases by 2.7% and cooling COP decreases by 1.4%.
조정일,김영모,임정혁,김용재,이철우,이명택 대한후두음성언어의학회 2001 대한후두음성언어의학회지 Vol.12 No.1
Background and Objectives : A burn injury to the glottis differs from a burn injury to the trachea, bronchi, and lung parenchyma, in that thermal injury does not occur to any significant degree below the level of the larynx, due to the effective cooling of air by the upper airway and to reflex closure of the vocal cords from a blast of hot air. Therefore, the laryngeal inhalation injury give rise to airway problem and voice change. The objectives of this study is to assess management of laryngeal inhalation injury and voice change after management. Materials and Methods : Voice choses and laryngeal injuries of eight laryngeal inhalation patients were analyzed through questionnaire, voice dynamic laboratory, and laryngeal stroboscopy. Operative management was performed to five patients for airway patiency and vocal cord movement on laryngeal pathology ind voice therapy was performed to all patients. One-year after, voice changes and laryngeal injuries were reanalyzed with same methods. Results : Vocal breathiness, decreased voice intensity, reduced voice range, and easy fatigability were major complaints of laryngeal inhalation patients. Glottic stenosis were developed to five of eight patients, and vocal cord atrophy, bowing were developed to others. Vocal cord mucosal waves were significantly decreased in all patients. Jitter(%), Shimmer(dB) were increased and Maximal phonation time(MPT) was decreased. One-year after, subjective voice changes and objective voice parameters were improved. And vocal cord mucosal waves were recovered in all patients. Conclusions : Subjective voice quality and objective voice parameters were improved after operative management for laryngeal pathology and voice therapy. And we observed recovery of vocal fold mucosal waves by laryngeal stroboscopy. We think that early preventable tracheotomy is necessary to reduce the laryngeal contact injury in laryngeal inhalation patients.