• Journal of Sleep Medicine
• /
• v.15 no.2
• /
• pp.48-54
• /
• 2018

Objectives: The aim of this study was to develop a predicting model for the optimal continuous positive airway pressure (CPAP) for obstructive sleep apnea (OSA) patient with obesity by using a machine learning. Methods: We retrospectively investigated the medical records of 162 OSA patients who had obesity [body mass index (BMI) ≥ 25] and undertaken successful CPAP titration study. We divided the data to a training set (90%) and a test set (10%), randomly. We made a random forest model and a least absolute shrinkage and selection operator (lasso) regression model to predict the optimal pressure by using the training set, and then applied our models and previous reported equations to the test set. To compare the fitness of each models, we used a correlation coefficient (CC) and a mean absolute error (MAE). Results: The random forest model showed the best performance {CC 0.78 [95% confidence interval (CI) 0.43-0.93], MAE 1.20}. The lasso regression model also showed the improved result [CC 0.78 (95% CI 0.42-0.93), MAE 1.26] compared to the Hoffstein equation [CC 0.68 (95% CI 0.23-0.89), MAE 1.34] and the Choi's equation [CC 0.72 (95% CI 0.30-0.90), MAE 1.40]. Conclusions: Our random forest model and lasso model ($26.213+0.084{\times}BMI+0.004{\times}$apnea-hypopnea index+$0.004{\times}oxygen$ desaturation index-$0.215{\times}mean$ oxygen saturation) showed the improved performance compared to the previous reported equations. The further study for other subgroup or phenotype of OSA is required.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.24 no.5
• /
• pp.21-33
• /
• 2020

In this study, the program for system analysis of an expander cycle rocket engine using liquid hydrogen as a fuel was developed. The properties of hydrogen were considered by the ratio of isomers with temperature. The analysis procedure was established with the open and closed types of the expander cycle engine and the simulation methods were suggested for each component. To validation of the analysis program, we compared the performance of the engine operating point and the analysis results performed overseas for Vinci and SE-21D, which are expander cycle engines. As a result of the analysis, the main performance factors of the system, such as the mass flow of the propellant, specific thrust, and power, except for some of the inaccurate input information, showed high accuracy with an error of around 1-2%.

• Journal of Korea Entertainment Industry Association
• /
• v.15 no.8
• /
• pp.75-89
• /
• 2021

In this paper, the results of analyzing the meaning of laughter in comedy movies of the late 1960s, focusing on comedians, Hee-Gap Kim, Bong-Seo Koo and Young-Chun Seo, are as follows. First, the narrative laughter of the comedians represents the generational conflict between the lower class and the upper class, the gender conflict between men and women, and the frustration of reality. Second the mechanism of creating laughter of the comedians shows ridicule of the conservative older generation, revelation of the immoral upper class, and caricature of the frustrated lower class. Third, the practical aspect of the comedians' laughter reveals cracks in tradition and modern, gaps in economic inequality, and expression of prohibited desires. Therefore, comedians Hee-Gap Kim, Bong-Seo Koo and Young-Chun Seo in comedy movies of the late 1960s show the semantic effect of laughter of internal/external boundaries and optimistic world views through the closed opening of informal culture and the conflict of characters/performers.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.17 no.3
• /
• pp.409-416
• /
• 2022

This paper relates to the blind noise separation method of time-delayed convolutive mixed signals. Since the mixed model of acoustic signals in a closed space is multi-channel, a convolutive blind signal separation method is applied and time-delayed data samples of the two microphone input signals is used. For signal separation, the mixing coefficient is calculated using an inverse model rather than directly calculating the separation coefficient, and the coefficient update is performed by repeated calculations based on secondary statistical properties to estimate the speech signal. Many simulations were performed to verify the performance of the proposed blind signal separation. As a result of the simulation, noise separation using this method operates safely regardless of convolutive mixing, and PESQ is improved by 0.3 points compared to the general adaptive FIR filter structure.

• The korean journal of orthodontics
• /
• v.29 no.6 s.77
• /
• pp.649-661
• /
• 1999

The goals of this study were 1) to present pre-surgical naso-alveolar molding (PNAM) appliance for bilateral cleft lip and palate treatment and 2) to evaluate the effects of the PNAM appliance on the alveolar molding of the premaxilla and the lateral segments. Subjects consisted of 8 bilateral cleft lip and palate infants (7 males and 1 female, mean age at first visit = 61.6 days after birth) who were treated with PNAM appliances in Department of Orthodontics, Seoul National University Dental Hospital. Average alveolar cleft gap between the premaxilla and the lateral segment was $8.09{\pm}5.03mm$ and average duration of alveolar molding treatment was $8.8{\pm}3.1$ weeks. These patients' models were obtained at initial visit (T0) and after alveolar molding (T1). 20 linear and 14 angular variables were measured by using photometry and digital caliper, All statistical analyses were performed by Microsoft Excel 97 program. Paired t-test was used to discriminate the effect of alveolar molding by PNAM appliance. 1. Closure of the alveolar cleft gap in bilateral cleft cases by molding therapy was completed successfully, 2. Alveolar molding inhibited outward growth of lateral segments and produced inward bending of lateral segments. 3. By bending the anterior part of the vomer, the premaxilla could be rotated and moved. posteriorly via alveolar molding. Conclusion This appliance can be applied to bilateral cleft lip and palate infants with satisfactory results before cheiloplasty.

• Tuberculosis and Respiratory Diseases
• /
• v.65 no.3
• /
• pp.183-190
• /
• 2008

Background: The control of active pulmonary tuberculosis is still an issue in community medicine. But there are also considerable needs for supportive management of symptomatic patients with post-tuberculous destroyed lung. Few studies have evaluated clinical characteristics and health-related quality of life in patients with post-tuberculous destroyed lung. Methods: We evaluated lung function, exercise tolerance, HRCT and health-related quality of life measurements using the Korean version of St. George's Respiratory Questionnaire (SGRQ) in 22 patients with parenchymal damage to more than a half of one lung due to pulmonary tuberculosis. Results: In the pulmonary function test, mixed defects and obstructive defects were observed in 10 (45.0%) and 9 (40.9%) of patients, respectively. In the cardiopulmonary exercise test, the mean $VO_2max%$ predicted ($39.0%{\pm}10.9%$) and $O_2$ pulse% predicted ($61.3%{\pm}13.6%$) were markedly decreased. In the SGRQ, the impact score (mean $27.8{\pm}18.5$) was significantly lower than the symptom score (mean $53.9{\pm}20.9$) or activity score (mean $50.8{\pm}27.3$) (p<0.05, p<0.01). Cronbach's alpha coefficient value for reliability was more than 0.7 for each subscale and total score. The total score showed a significant negative correlation with $FEV_1%$ predicted (r=-0.46, p<0.05) and $SaO_2$ (r=-0.60, p<0.05). On HRCT, a median of 9 (range 5~15) bronchopulmonary segments were destroyed by less than half, which significantly correlated with SGRQ total score (r=-0.52, p=0.02). Conclusion: The reliability and validity of the Korean version of the SGRQ was acceptable for the measurement of health-related quality of life in patients with post-tuberculous destroyed lung.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.19 no.5
• /
• pp.492-501
• /
• 2007

Coastal disasters have become one of the most important issues in every coastal country. In Korea, coastal disasters such as storm surge, sea level rise and extreme weather have placed many coastal regions in danger of being exposed or damaged during subsequent storms and gradual shoreline retreat. A storm surge is an onshore gush of water associated with a tow pressure weather system, typically in typhoon season. However, it is very difficult to predict storm surge height and inundation due to the irregularity of the course and intensity of a typhoon. To provide a new scheme of typhoon damage prediction model, the scenario which changes the central pressure, the maximum wind radius, the track and the proceeding speed by corresponding previous typhoon database, was composed. The virtual typhoon scenario database was constructed with individual scenario simulation and evaluation, in which it extracted the result from the scenario database of information of the hereafter typhoon and information due to climate change. This virtual typhoon scenario database will apply damage prediction information about a typhoon. This study performed construction and analysis of the simulation system with the storm surge/coastal inundation model at Masan coastal areas, and applied method for predicting using the scenario of the storm surge.

• Journal of Chest Surgery
• /
• v.39 no.1 s.258
• /
• pp.35-41
• /
• 2006

Background: The radial arteries are being used more often for coronary artery bypass grafting, We tried to the endoscopic radial artery harvest to reduce the cosmetic problems and neurologic complications of the conventional open harvesting and report the techniques and early results. Material and Method: The 86 patients underwent coronary artery bypass grafting between May 2003 and April 2005 had their nondominant radial artery endoscopically removed through a 2 cm incision at the wrist. The radial pedicle was dissected and was divided at antecubial area through a 5 mm counterincision. Result: The 23 patients complained of neuralgias on territory of superficial raidal none but no one complained of neuralgias on territory of lateral antebrachial cutaneous none. There was no functional impairment of the hand. There was no wound complication except a localized hematoma. All patients were contacted by telephone after postoperative 7.9$\pm$3.6 months. The 4 patients still complained of neuralgia. All the patients were satisfied with the aesthetics of the wounds. The multidetectional tomography was done on the 66 patients for the estimation of early patency of radial artery. There were 2 cases of stenosis and a case of occlusion. Conclusion: Endoscopic radial artery harvest had no functional impairment of the hand, lesser rate of neurologic complications and outstanding aesthetics. The results of early patency of the radial artery was similar to conventional methods. Therefore, we think that endoscopic radial artery harvest is the optimal procedure.

• Journal of Chest Surgery
• /
• v.30 no.12
• /
• pp.1225-1231
• /
• 1997

Spontaneous pneumothorax is the sudden collapse of a lung usually caused by air leakage from a subvisceral pleural blob. Responses to closed thoracostomy,thoracentesls and simple observation are usually prompt and effective. But in some cases, these are unsucceful and open thoracotomy is indicated. A clinical evaluation was performed on 242 cases(236 patients) of open thoracotomy in spontaneous pneumoth rax who were admitted and treated at department of Thoracic and Cardiovascular Surgery. Masan Samsung General Hospital during the past 9 years from January 1988 to December 1996. The results were as follows 1. The sex ratio was male predominance(M:F=11.7:1) 2. The most common age group were 2nd, 3rd decades(2nd=29.3%, 3rd=30.2%). 3. The most common chief complaints were chest pain and dyspnea(chest pain=41.7%. dryspnea= 36.8). 4. The etiologic factors of spontaneous pneumothorax were primary spontaneous pneumothorax(86.4%), tuberculosis(9.1%), COPD(3.7%) and pleuritis(0.8%). 5. The site of spontaneous pneumothorax was 52.1% in right, 45.4% in left and 2.5% in both. 6. The common indications of open thoracotomy were recurrence(44.2%), persistent air leakage(31.8%) and inadequate expansion(15.7%). 7. The operative procedures were bullectomy or mechanical pleurodesis through posterolateral thoracotomy or median sternotomy. 8. The most frequent location of bulla or blob were apical segme t oi RUL(35.1%) and apicoposterior segment of LUL(41.3 %). 9. The number of bulla or blob were mainly 1 to 5(88%), and there were no significant differences among operation indications. 10. The size of bulla or bleb were mainly below 5cm(81%)and small bulla($\leq$1cm) were predominant in recurrence group but large bulla(>5cm)were predominant in persistent air leakage and inadequate expansion group. 11. The pleural adhesion was seen in 54.5%.(Recurrence group 64.1%,Persistent air leakage group 51.9%,Inadequate expansion group 47.4%).

• Journal of Chest Surgery
• /
• v.37 no.8
• /
• pp.672-683
• /
• 2004

Background: The treatment results of the advanced lung carcinoma is not satisfactory with the present therapeutic modalities: surgical resection, anti-cancer chemotherapy, and radiotherapy or combination therapy. To predict the prognosis of the non-small-cell lung carcinoma, TNM classification has been was as the basic categorization; however, it has been not satisfactory. It is necessary to consider the causes and the prognosis of the lung carcinoma from another points of view rather the conventional methods. We intended to find out the relationship between the major apoptotic factor, p53 gene and the prognosis of the patient with lung carcinoma. Material and Method: Three hundreds and fifty-nine patients with lung carcinoma who underwent surgery were analysed. We observed p53 protein accumulated in the cellular nuclei. The p53 protein was detected by immuno-histo-chemical method. We collected information of the patient retrospectively. Result: p53 protein densities were observed in 40% in average as a whole. The protein density was 44 percent in man, 25 percent in woman, 49 percent in the squamous cell carcinoma, and 38 percent in the adenocarcinoma. There were significant correlations between the p53 protein density and the mortality in the squamous cell carcinoma (p=0.025), follow-up duration in TNM stage I group (p=0.010), and follow-up duration in the lobectomy patient group (p=0.043), and tumor cell differentiation (p=0.009). p53 protein densities were significantly different between the lobectomy and the pneumonectomy group (p=0.044). Conclusion: The authors found that p53 protein had some correlations with the prognosis of the lung cancer partially in some factors. We suggest the p53 protein density could be used as a marker of prognosis in the non-small-cell lung carcinoma.