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Development of Laryngeal Stroboscopic Effect With Continuous Light Source
Kim Geun-Hyo,Wang Soo-Geun,Jang Jeon Yeob,Lee Yeon-Woo,Lee Jin-Choon,Cha Wonjae 대한후두음성언어의학회 2024 대한후두음성언어의학회지 Vol.35 No.1
Background and Objectives Most laryngeal imaging modalities used continuous light source. However, videostroboscopy adopted the unique stroboscopic flashing light triggered externally and is consistent with fundamental voice frequencies. If laryngeal stroboscopic effect could be obtained in the field of continuous illumination, it woud be more compatible with conventional video. In this study, we established the mathematical algorithm for stroboscopic effect with continuous light and tried to determine the feasibility of laryngeal stroboscopic effect with conventional laryngoscopy using continuous light in the mechanical model. Materials and Method The mechanical model of fan motor system was used to validate to the present study. Rotational images of the fan motor were captured using conventional laryngoscope with continuous light source. Results On the basis of the mathematical model, the optimal ranges of the frequency for stroboscopic effect were expected as (multiples of sampling rate [S])±(S/5). In the fan motor model, the stroboscopic effects could be confirmed on the basis of the mathematical model using conventional videolaryngoscopy with continuous light source. Conclusion Laryngeal stroboscopic effect with continuous light source might be feasible. The stroboscopic effect with continuous light would be expected to provide greater compatibility to integrate with the other imaging modalities for the vocal folds.
Myung Hyo Ryu,Byungcho Choi,Heung Geun Kim,Young Kil Cha 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-
This paper proposes a new single-stage, single-switch AC/DC converter based on the boost power factor correction (PPC) cell. The converter offers both high power factor and high efficiency. To reduce the dc voltage on the energy storage capacitor, the dc bus voltage feedback method was used. A 100W (5V/20A) prototype was built and tested to show the validity of the proposed converter.<br/>
N-methylformamide induces multiple organ toxicity in Fischer 344 rats
Lee Mi Ju,Cha Hyo-Geun,Park Ka Young,Kim Yong-Soon,Ahn Byeongwoo 한국독성학회 2023 Toxicological Research Vol.39 No.2
N-Methylformamide (NMF) is a widely used chemical (CAS No.: 123-39-7) in several industries and its usage is continuously increasing. However, studies for NMF have been focused on hepatotoxicity from now. Its toxicity profile has not yet been established owing to limited toxicity data. Therefore, we evaluated systemic toxicity via NMF inhalation. We exposed 0, 30, 100, and 300 ppm NMF to Fischer 344 rats for 6 h/day, 5 days a week for 2 weeks. Clinical signs, body weights, food consumption, hematologic parameters, serum chemistry measurements, organ weights, necropsy, and histopathology were performed. Two females exposed to 300 ppm NMF died during exposure period. Decrease of food consumption and body weight in both sexes exposed to 300 ppm in females exposed to 100 ppm were noted during exposure period. Increased RBC and HGB were noted in females exposed to 300 ppm. A decrease in the levels of ALP and K and increase in the levels of TCHO and Na were observed in both sexes exposed to 300 and 100 ppm. Increased levels of ALT, AST, BUN and decreased levels of TP, ALB, Ca were observed in females exposed to 300 and 100 ppm. The relative liver weight was elevated in both sexes exposed to 300 and 100 ppm NMF. Hypertrophy in the liver and submandibular glands and nasal cavity injuries were noted in both sexes exposed to 300 and 100 ppm NMF. Tubular basophilia of the kidneys were noted in females exposed to 300 ppm NMF. We revealed that NMF affect several organs including the kidneys not only the liver and NMF-related toxicity is predominant in female rats. These results could contribute to the development of NMF toxicity profile and may help in developing strategies for the control of occupational environmental hazards related to NMF.
차원재,왕수건,장전엽,김근효,이연우,Cha, Wonjae,Wang, Soo-Geun,Jang, Jeon Yeob,Kim, Geun-Hyo,Lee, Yeon-Woo The Korean Society of Laryngology 2017 대한후두음성언어의학회지 Vol.28 No.2
Background and Objectives : High-speed videolaryngoscopy (HSV) is the only technique that captures the true intra-cycle vibratory behavior of the vocal folds by capturing full images of the vocal folds. However, it has problems of no immediate feedback during examination, considerable waiting time for digital kymography (DKG), recording duration limited to a few seconds, and extreme demands for storage space. Herein, we demonstrate a new post-processing method that converts HSV images to two-dimensional digital kymography (2D-DKG) images, which adopts the algorithm of 2D videokymography (2D VKG). Materials and Methods : HSV system was used to capture images of vocal folds. HSV images were post-processed in Kay image-process software (KIPS), and conventional DKG images were retrieved. Custom-made post-processing system was used to convert HSV images to 2D-DKG images. The quantitative parameters of the post-processed 2D-DKG images was validated by comparing these parameters with those of the DKG images. Results : Serial HSV images for all phases of vocal fold vibratory movement are included. The images were converted by the scanning method using U-medical image-process software. Similar to conventional DKG, post-processed 2D DKG image from the HSV image can provide quantitative information on vocal fold mucosa vibration, including the various vibratory phases. Differences in amplitude symmetry index, phase symmetry index, open quotient, and close quotient between 2D-DKG and DKG were analyzed. There were no statistical differences between the quantitative parameters of vocal fold vibratory movement in 2D-DKG and DKG. Conclusion : The post-processing method of converting HSV images to 2D DKG images could provide clinical information and storage economy.
유소아 기도 이물의 임상 양상과 환기형 기관지 내시경술의 결과 : 서울대 병원의 경험 120례
차원재,최효근,문성중,하정훈,성명훈,김광현,Cha, Won-Jae,Choi, Hyo-Geun,Moon, Sung-Joong,Hah, J.-Hun,Sung, Myung-Whun,Kim, Kwang-Hyun 대한기관식도과학회 2006 大韓氣管食道科學會誌 Vol.12 No.2
Backgroud and Objectives: Inhalation of foreign bodies in respiratory tract can be fatal to infants and child. After ventilating bronchoscopy technique was widelyused, most of the pediatric airway foreign bodies could be managed effectively. In this study, we aimed to analyze clinicalfeatures and outcomes of ventilating bronchoscopic removal of pediatric airway foreign bodies. Materials and Methods: One hundred twenty cases of ventilating bronchoscopy for pediatric airway foreign bodies at Seoul National University Hospital for the past 15 years were analyzed retrospectively. Results: In 120 cases, sex ratio (male: female) was 2.2:1 and mean age was 27.0 months. Most frequent type of airway foreign was peanut (60.2%). One hundred thirteen patients, in whom a foreign body was confirmed in the airway, were successfully managed by ventilating bronchoscopy. Delayed diagnosis and management made a significantly long postoperative hospital stay. Conclusion: Great care must be given when feeding young children, especially younger than 36 months, with nuts. Early intervention with ventilating bronchoscopy following a clinical suspicion is critical to successful treatment.