• Transactions of the Korean Society of Mechanical Engineers B
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• v.31 no.5
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• pp.457-466
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• 2007

A numerical and experimental study on the evaluation and the prediction of cleanliness level in the mini-environment system was carried out. Using the concept of local mean air-age (LMA) and effective flow rate, the new direct method for estimating the mini-environment was developed and compared with the previous performance index of airflow pattern characteristics. It was found out that the airflow pattern analysis is a restricted method to estimate the real performance of the mini-environment. The reason is that the airflow pattern cannot predict the effect of the increment of the ventilation rate on the cleanliness level in the mini-environment. While LMA is capable of showing the effects of the contaminant accumulation caused by turbulent intensity, eddy, and the increment of the effective flow rate. This result showed that LMA is more exact and effective performance index than the previous one like the airflow pattern characteristics.

• Proceedings of the SAREK Conference
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• 2004.11a
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• pp.64-64
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• 2004

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.8
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• pp.736-745
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• 2005

This study is undertaken to evaluate the relationship between the indoor $CO_2$ concentration and the local mean air-age in the lecture room with the occupants. We conducted the experiments to examine the indoor $CO_2$ concentration and the local mean air-age with respect to the supply airflow of the ventilation system and the discharge angle and air-flow of the system air conditioner. Through the experiments, we found out that indoor $CO_2$ concentrations calculated by the prediction equation of Seidel are about 350 ppm lower than those measured by the experiments. The indoor $CO_2$ concentration is not related with the air-flow and the discharge angle of the system air-conditioner, but with the ventilation airflow. From the numerical calculation, the indoor $CO_2$ concentration is not related with the ventilation effectiveness, but strongly with the local mean air-age. In case of our model, the indoor $CO_2$ concentration is likely to fall within the acceptable air quality when the local mean air-age is averagely predicted under 400 seconds.

• Journal of the Korean Society of Visualization
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• v.14 no.1
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• pp.19-26
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• 2016

Modern people spend much time at indoor space. So, People want to make better indoor air condition. But the facade of building is made of glass to be seen urbanely, the effect of solar radiation makes indoor environment worse. This study designs an open space affected by solar radiation with 4-way cassette air-conditioner. Using numerical simulation, this paper investigates thermal comfort and ventilation performance with discharge angles $30^{\circ}$ and $45^{\circ}$. To study thermal comfort, this paper studies distribution of velocity, temperature and effective draft temperature. Also, this paper introduces concept of air age to study ventilation performance. The flow influenced by solar radiation determines thermal comfort and ventilation performance in room space. This study shows that discharge angle of 45 degree has better thermal comfort and ventilation performance than that of 30 degree.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.19 no.10
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• pp.695-702
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• 2007

In this paper, the ventilation efficiencies of an underground sewage disposal plant were investigated for ventilating system without fan, ventilating system with eleven cross flow fans and ventilating system with sixteen cross flow fans by numerical method. It has been found that the air change effectiveness of the system without fan was predicted 0.44. It means that an additional ventilating equipment is needed to maintain good indoor air quality. For the ventilating system with sixteen cross flow fans, the air change effectiveness was predicted 0.55. The air change effectiveness of the ventilating system with eleven cross flow fans was predicted 0.51. It is known that the air change effectiveness above 0.5 is enough to eliminate pollutant and bad smell in the indoor. Therefore, it is recommended to select the ventilating system with eleven cross flow fans for the underground sewage disposal plant in an economic point of view.

• Tuberculosis and Respiratory Diseases
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• v.65 no.6
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• pp.457-463
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• 2008

Background: The attenuation of the lung parenchyma increases on expiration as a consequence of decreased air in the lung. Expiratory CT scans have been used to show air trapping in patients with chronic airway disease and diffuse parenchymal disease and also in asymptomatic smokers. Although there have been several reports investigating the regional air trapping on a expiratory CT scan, there have been only a few reports evaluating the changes of whole lung attenuation with considering its clinical significance, and especially in healthy subjects. The purpose of this study was to evaluate the correlation of an expiratory increase of lung attenuation with age and smoking in healthy subjects. Methods: Asymptomatic subjects who underwent a low dose chest CT scan as part of a routine check-up and who showed normal spirometry and a normal inspiratory CT scan were recruited for this study. We excluded the subjects with significant regional air trapping seen on their expiratory CT scan. Lung attenuation was measured at 24 points of both the inspiratory and expiratory CT scans, respectively, for 100 subjects. The correlations between an expiratory increase of the lung attenuation and the amount of smoking, the patient's age and the results of spirometric test were assessed. Results: There were 87 men and 13 women included in this study. Their median age was 49.0 years old (range:25~71). Sixty current smokers, 24 ex-smokers and 16 non-smokers were included. As age increased, the expiratory increase of lung attenuation was reduced at every measuring points (r=-0.297~-0.487, Pearson correlation). The statistical significance was maintained after controlling for the effect of smoking. Smoking was associated with a reduction of the expiratory increase of lung attenuation. But the significance was reduced after controlling for the patient's age. The $FEV_1$, FVC, $FEV_1/FVC$ and $FEF_{25{\sim}75%}$ were not associated with an expiratory increase of lung attenuation. Conclusion: The expiratory increase of lung attenuation in subjects with a normal inspiratory CT scan was negatively correlated with age. It was also reduced in heavy smokers. It may reflect aging and the smoking related changes.

• Proceedings of the KOR-BRONCHOESO Conference
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• 1991.06a
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• pp.32-32
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• 1991

성대의 점막하 조직의 부종을 특징으로 하는 폴립양 성대는 음성의 남용 및 상기도에 대한 다양한 자극 요인들에 의하여 발생된다고 보고되어 있으며, 현재까지 부종의 기전 및 병태에 대하여도 혈괴의 유리화 현상(hyalinization), 또는 단순한 혈관의 투과력 증대 등의 논란이 많은 실정에 있어 치료방법 역시 학자에 따라 견해를 달리하고 있다. 이에 저자들은 폴립양 성대의 치료에 도움을 얻고자 최근 5년간 본 교실에서 경험한 폴립양 성대 34례(남자 18예, 여자 16예, 평균연령 53.7세)에 대한 임상 소견 및 저자들의 치료 성적을 분석 검토하여 다음과 같은 결과를 얻었다. 1. 측별로는 총 34예중 양측 23예(67.6%), 편측 11예(32.4%)이었다. 2. 동반질환으로 성대에 타 질환이 있었던 예가 9예(후두용 5예, 과각화증 3예, 성대마비 1예 ; 26.5%), 수면무호흡증 5예(14.7 %)이었으며 전신질환이 있었던 예가 4예(기관지 천식 2예, 폐결핵 2예 ; 11.8%)이었다. 3. 유발요인으로는 음성남용 7예(20.6%), 상기도감염 3예(8.8%), 흡연 26 예 (76.5%)이었다. 4. 공기역학검사 및 청각심리검사가 가능하였던 14예에서 최대발성지속시간이 정상이하이었던 예가 10예(71.4%), 발성율이 정상이상이었던 예가 9예 (64.3%)이었으며, 애성의 특징도 조호성(rough)이 10예(71.4%)로 가장 많았다. 5. 총 34예를 sucking technique를 적용하여 수술적 치료를 하였는데 음성이 호전된 경우는 32예(정상 15예, 호전 17예 : 94.1%)이었으며 호전되는데 걸린 평균 기간은 2.8개월이었다. 이상의 성적으로 보아 폴립양 성대는 국소 또는 전신적으로 동반질환이 많고 흡연 등의 만성 자극 요인이 있으며 술후 음성 호전에 걸리는 기간이 길어 보다 복합적인 측면에서 치료에 임하여야 할 것으로 사료된다. with such configuration.trap with 2.88[eV] deep of injected space charge from the chathode in the crystaline regions. The origin of ${\alpha}$$_2$ peak was regarded as the detrapping process of ions trapped with 0.9[eV] deep originated from impurity-ion remained in the specimen during production process of the material, in the crystalline regions. The origin of ${\beta}$ peak was concluded to be due to the depolarization process of "C=0"dipole with the activation energy of 0.75[eV] in the amorphous regions. The origin of ${\gamma}$ peak was responsible to the process combined with the depolarization of "CH$_3$", chain segment, with the activation energy of carriers from the shallow trap with 0.4[eV], in he amorphous regions.의 증발산율은 우기의 기상자료를 이용하여 구한 결과 0.05 - 0.10 mm/hr 의 범위로서 이로 인한 강우손실량은 큰 의미가 없음을 알았다.재발이 나타난 3례의 환자를 제외한 9례 (75%)에서는 현재까지 재발소견을 보이지 않고 있다. 이러한 결과는 다른 보고자들과 유사한 결과를

• Journal of Chest Surgery
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• v.34 no.12
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• pp.917-923
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• 2001

Background : Bronchial sleeve resection for centrally located primary lung cancer is a lung-parenchyma-sparing operation in patients whose predicted postoperative lung function is expected to diminished markedly. Because of its potential bronchial anastomotic complications, it is considered to be an alternative to pneumonectomy. However, since sleeve lobectomy yielded survival results equal to at least those of pneumonectomy, as well as better functional results, it became and accepted standard procedure for patients with lung cancer who have anatomically suitable tumors, regardless of lung function. In this study, from analyzing of occurrence rate of postoperative complication and survival rate, we wish to investigate the validity of sleeve resection for primary lung cancer. Material and Method : From January 1989 to December 1998, 45 bronchial sleeve resections were carried out in the Department of Thoracic Surgery of Seoul National University Hospital. We included 40 men and 5 women, whose ages ranged from 23 to 72 years with mean age of 57 years. Histologic type was squamous cell carcinoma in 35 patients, adenocarcinoma in 7, and adenosquamous cell carcinoma in 1 patients. Right upper lobectomy was peformed in 24 patients, left upper lobectomy in 11, left lower lobectomy in 3, right lower lobectomy in 1, right middle lobecomy and right lower lobectomy in 3, right upper lobectomy and right middle lobecomy in 2, and left pneumonectomy in 1 patient. Postoperative stage was Ib in 11, IIa in 3, IIb in 16, IIIa in 13, and IIIb in 2 patients. Result: Postoperative complications were as follows; atelectasis in 9, persistent air leakage for more than 7 days was in 7 patients, prolonged pleural effusion for more than 2 weeks in 7, pneumonia in 2, chylothorax in 1, and disruption of anastomosis in 1. Hospital mortality was in 3 patients. During follow-up period, bronchial stricture at anastomotic site were found in 7 patients under bronchoscopy, Average follow-up duration of survivals(n=42) was 35.5$\pm$29 months. All of stage I patients were survived, and 3 year survival rate of stage II and III patients were 63%, 21%, respectively. According to Nstage, all of N0 patients were survived and 3 year survival rates of Nl and N2 were 63% and 28% respectively. Conclusion: We suggest that this sleeve resection, which is technically demanding, should be considered in patients with centrally located lung cancer, because ttlis lung-saving operation is safer than pneumonectomy and is equally curative.