• Journal of Chest Surgery
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• v.57 no.1
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• pp.36-43
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• 2024

Background: Coronavirus disease 2019 (COVID-19) can lead to acute respiratory failure, which frequently necessitates invasive mechanical ventilation and extracorporeal membrane oxygenation (ECMO). However, the limited availability of ECMO resources poses challenges to patient selection and associated decision-making. Consequently, this retrospective single-center study was undertaken to evaluate the characteristics and clinical outcomes of patients with COVID-19 receiving ECMO. Methods: Between March 2020 and July 2022, 65 patients with COVID-19 were treated with ECMO and were subsequently reviewed. Patient demographics, laboratory data, and clinical outcomes were examined, and statistical analyses were performed to identify risk factors associated with mortality. Results: Of the patients studied, 15 (23.1%) survived and were discharged from the hospital, while 50 (76.9%) died during their hospitalization. The survival group had a significantly lower median age, at 52 years (interquartile range [IQR], 47.5-61.5 years), compared to 64 years (IQR, 60.0-68.0 years) among mortality group (p=0.016). However, no significant differences were observed in other underlying conditions or in factors related to intervention timing. Multivariable analysis revealed that the requirement of a change in ECMO mode (odds ratio [OR], 366.77; 95% confidence interval [CI], 1.92-69911.92; p=0.0275) and the initiation of continuous renal replacement therapy (CRRT) (OR, 139.15; 95% CI, 1.95-9,910.14; p=0.0233) were independent predictors of mortality. Conclusion: Changes in ECMO mode and the initiation of CRRT during management were associated with mortality in patients with COVID-19 who were supported by ECMO. Patients exhibiting these factors require careful monitoring due to the potential for adverse outcomes.

• Clinical Nutrition Research
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• v.13 no.1
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• pp.1-7
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• 2024

Nutritional support in critically ill patients is an essential aspect of treatment. In particular, the benefits of enteral nutrition (EN) are well recognized, and various guidelines recommend early EN within 48 hours in critically ill patients. However, there is still controversy regarding EN in critically ill patients with septic shock requiring vasopressors. Therefore, this case report aims to provide basic data for the safe and effective nutritional support in septic shock patients who require vasopressors. A 62-year-old male patient was admitted to the intensive care unit with a deep neck infection and mediastinitis that progressed to a septic condition. Mechanical ventilation was initiated after intubation due to progression of respiratory acidosis and deterioration of mental status, and severe hypotension required the initiation of norepinephrine. Due to hemodynamic instability, the patient was kept nil per os. Subsequently, trophic feeding was initiated at the time of norepinephrine dose tapering and was gradually increased to achieve 75% of the energy requirement through EN by the 7th day of enteral feeding initiation. Although there were signs of feeding intolerance during the increasing phase of EN, adjusting the rate of EN resolved the issue. This case report demonstrates the gradual progression and adherence to EN in septic shock patient requiring vasopressors, and the progression observed was relatively consistent with existing studies and guidelines. In the future, further case reports and continuous research will be deemed necessary for safe and effective nutritional support in critically ill patients with septic shock requiring vasopressors.

• Tuberculosis and Respiratory Diseases
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• v.44 no.5
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• pp.1072-1082
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• 1997

Background : To characterize the clinical features and determine the prognostic factors of severe community-acquired pneumonia. This study is the first of its kind in Korea. Methods : Recruited were 40 patients diagnosed as severe community-acquired pneumonia in Hallym University Hospital from January 1, 1989 through July 31, 1996. Patients were analysed retrospectively for age, sex, underlying disease, respiration rate, hypoxemia, requirement of mechanical ventilation, involvement on chest radiograph, shock, and the serum concentration of BUN and albumin. All parameters were compared between survived and dead group. Results : Male to female ratio was 2.07 : 1. The mean age was $63.1{\pm}17.5$years(range 25~90years) with 65% of patients aged equal to or more than 60. The major underlying diseases were old pulmonary tuberculosis(12.5%), chronic obstructive pulmonary disease(7.5%), bronchial asthma(5%), bronchiectasis(2.5%), and diabetes mellitus(22.5%). Microbiologic diagnosis was made in 26 out of 40 patients(65%). The most common causative organism was S. pneumoniae(17.5%, 7/40) followed by S. aureus(15.0%, 6/40), K. Pneumoniae(12.5%, 5/40), M. tuberculosis(7.5%, 3/40), H. influenzae(2.5%, 1/40), coagulase negative staphylococcus(2.5%, 1/40), P. aeruginosa(2.5%. 1/40), E. cloaceae(2.5%, 1/40), and E. coli(2.5%, 1/40). M. pneumoniae was detected in no patient. The most frequent drugs administered in single or combination therapy were aminoglycosides(75%, 30/40), second- and third-generation cephalosporin(40%, 16/40 and 27.5%, 11/40), macrolides(27.5%, 11/40), and amoxicillin/clavulanic acid(22.5%, 9/40). Of the 40 patients, 14 died of severe community-acquired pneumonia(37.5%). Among them, seven patients (50%) expired within 72h of hospital arrival. According to multivariate analysis, mortality was significantly associated with requirement of mechanical ventilation, bilateral pulmonary involvement, and serum albumins$\leq$3.0g/dl. Conclusion : An understanding of the clinical characteristics and prognostic factors in severe community-acquired pneumonia identified in this study will optimize therapeutic approach in this disease and help decreasing its notorious mortality rate.

• Journal of Energy Engineering
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• v.23 no.1
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• pp.90-94
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• 2014

Environmental qualification (EQ) for safety-related equipment is required to ensure that those equipment will perform their required function even under the harsh environment conditions arising from design basis accident in the nuclear power plant. As a part of EQ program, the room temperature analysis in case of a loss of Heating, Ventilation, and Air Conditioning(HVAC) system was carried out to ensure the operability of the safety-related equipment of a nuclear power plant randomly chosen among the Korean nuclear power plants. In this paper, this analysis was performed in the conservative perspective using GOTHIC code. The room temperature analysis includes selecting the rooms in which the safety related equipment are located but not supported by safety related HVAC and determining the temperature of the selected rooms. Target rooms for the analysis consist of W229/W237 (Aux. feedwater pump room), W232 (Aux. feedwater tank room) and W230 (Equipment passageway). The results showed the temperature range from $43^{\circ}C$ to $83^{\circ}C$, in 72 hours after a loss of HVAC. Those values are far below of generic EQ temperature($171^{\circ}C$). Therefore, it is satisfied with EQ requirement of temperature limits on safety related equipment.

• Journal of Biosystems Engineering
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• v.12 no.2
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• pp.16-27
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• 1987

Greenhouse farming was introduced to the Korean farmers in the middle of 1950's and its area has been increased annually. The plastic greenhouse, which is covered with polyethylene or polyvinyl chloride film, has been rapidly spread in greenhouse farming since 1970. The greenhouse farming greatly contributed to the increase of farm household income and the improvement of crop productivity per unit area. Since the greenhouse farming is generally practiced during winter, from November to March, the thermal environment in the plastic greenhouse should be controlled in order to maintain favorable condition for plant growing. Main factors that influence the thermal environment in the plastic greenhouse are solar radiation, convective and radiative heat transfer among the thermal component of the greenhouse, and the use of heat source. The objective of this study was to develop a simulation model for thermal environment of the plastic greenhouse in order to determine the characteristics of heat flow and effects of various ambient environmental conditions upon thermal environments within the plastic greenhouse. The results obtained are summarized as follows: 1. Simulation model for thermal environment of the plastic greenhouse was developed, resulting in a good agreement between the experimental and predicted data. 2. Solar radiation being absorbed in the plant and soil during the daytime was 75 percent of the total solar radiation and the remainder was absorbed in the plastic cover. 3. About 83 percent of the total heat loss was due to convective and radiative heat transfer through the plastic cover. Air ventilation heat loss was 5 to 6 percent of total heat loss during the daytime and 16 to 17 percent during the night. 4. The effectiveness of thermal curtain for the plastic greenhouse at night was significantly increased by the increase of the inside air temperature of the greenhouse due to the supplementary heat. 5. When the temperature difference between the inside and outside of the greenhouse was small, the variation of ambient wind velocity did not greatly affect on the inside air temperature. 6. The more solar radiation in the plastic greenhouse was, the higher the inside air temperature. Because of low heat storage capacity of the plant and soil inside the greenhouse and a relatively high convective heat loss through the plastic cover, the increase of solar radiation during the daytime could not reduce the supplymentary heat requirement for the greenhouse during the night.

• Korean Journal of Environmental Agriculture
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• v.18 no.4
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• pp.310-315
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• 1999

The feasibility of an absorbent biofilter system was examined for rural wastewater treatment. Hydraulic loading rates varied from 50 to 250 cm/day. Effluent of the septic tank was fed into the absorbent biofilter, and small ventilation fan was provided to supply air at the rate of 250 L/min to aerate the biofilter. The biofilter system demonstrated high removal rates for $BOD_5$ and TSS at the loading rate of 150 cm/day, generally meeting the Korean effluent water quality standard of 20 mg/L applicable to both. The nutrient removal was less satisfactory than the results of $BOD_5$ and TSS, but it was within the expected range of biological treatment processes. Considering the abnormally high influent concentration of nutrients during the experiment, better performance results could have been obtained if ordinary domestic wastewater was used. The system performance was not significantly affected by the hydraulic loading up to 150 cm/day, which is far more than the loading limit of the sand filter systems. Maintenance requirement was minimal, and no problems with noise, odor, flies or sludge arose. Since the biofilter system can be operated at a distance, operation in remote rural area and multi-system connected to one control office might be advantageous to the rural area. Overall, considering the cost-effectiveness, stable performance, and minimum maintenance, the biofilter system was thought to be a competitive alternative to treat wastewater in Korean rural communities.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.6 no.2
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• pp.119-128
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• 2008

Thermal assessment of a new CANDU spent fuel disposal system, which improves the retrievability of the spent fuel and enhances the densification factor compared with the Korean Reference disposal System, is carried out in this study. The canisters for CANDU spent fuels are stored for long term and cooled by natural convection in the proposed disposal system for the retrievability. The steady state thermal analyses for proposed CANDU disposal system are carried out with the ANSYS 10.0 CFX code. The thermal analyses are performed through two steps. At the first step, the sensitivity of the disposal tunnel spacing is analysed. The differences of maximum temperatures by several tunnel spacings are calculated at three points in the disposal tunnel. The result shows that the differences of the temperature at the three points are almost negligible because 99% of the decay heat is removed by natural convection. At the second procedure, 60m tunnel spacing with a ventilation system instead of natural convection is considered. The result is applied to the calculation of the canister surface temperature in disposal tunnel as boundary conditions. Consequently, the average and the maximum surface temperature of disposal canisters are $79.9^{\circ}C$ and $119^{\circ}C$, respectively. The inner maximum temperature of a basket in the disposal canister is calculated as $140.9^{\circ}C$. The maximum temperature of the basket meets the thermal requirement for the CANDU spent fuel cladding.

• Nuclear Engineering and Technology
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• v.26 no.1
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• pp.140-148
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• 1994

A qualification test was performed for the iron removal chemical cleaning of the secondary side of nuclear steam generators at the selected temperature, 1$25^{\circ}C$, higher than the standard application temperature, 93$^{\circ}C$. The field cleaning condition for a nuclear unit was tested in a bench scale test loop including a SUS 316 stainless steel autoclave with one gallon capacity as a test vessel. The kinetics of sludge dissolution, corrosion of the secondary side materials and change of solvent chemistry were monitored. Test results indicated that more thorough cleaning was accomplished in less than half of the cleaning time required at 93$^{\circ}C$. And the total corrosions of the secondary side materials were found to be less than the values at 93$^{\circ}C$. While the solvent is recirculated and heated by an external chemical cleaning equipment for the conventional 93$^{\circ}C$ process, the secondary side is heated by the lateral heat of the primary coolant without the recirculation of the cleaning solution, and the solvent is mixed by vigorous boiling induced by periodic ventilation for the high temperature process. The requirement that the reactor coolant pumps should be running during the cleaning operation is the major disadvantage of the high temperature process which also should be considered when chemical cleaning is planned for steam generators under operation.

• Tuberculosis and Respiratory Diseases
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• v.63 no.1
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• pp.59-66
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• 2007

Background: Surgical lung biopsy is required to establish the etiology and stage of interstitial lung disease(ILD). and this procedure can be safe and meaningful for making clinical decisions. We wanted to determine the safety of surgical lung biopsy(SLB) in patients with interstitial lung disease(ILD). Methods: We conducted a retrospective review of 40 patients with suspected ILD and they underwent surgical lung biopsy from January 2001 to June 2006 at Chungnam University Hospital. We analyzed retrospectively according to their age, gender, pulmonary function, chest tube duration, the arterial blood gases, the procedural technique, and the requirement for supplemental oxygen and mechanical ventilation(MV) at the time of SLB. Results: The mean age of the patients was 56.4${\pm}$16.13 years(range: 21 to 77 years). Overall, the 30-day and 90-day mortality rates were 15% and 20%, respectively. The predictors of perioperative mortality were either the need for mechanical ventilation(MV) at the time of SLB or the need for supplemental oxygen prior to undergoing SLB. Among the 32 patients who were 90-day survivors, the proportion of those patients using the oxygen supplement was 28.1% (n=9). All 8 patients who were 90-day non-survivors used oxygen supplement (p=0.000). The use of the MV was 12.5% (n=4) in the 90-day survivors (n=32) and 62.5% (n=5) in the 90-day non-survivors (n=8); there was a significant difference between the 90-day survivors and non-survivors (p=0.000). Conclusion: Patients who require MV and supplemental oxygen are associated with an increased risk for death following SLB.

• Tuberculosis and Respiratory Diseases
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• v.61 no.3
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• pp.265-272
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• 2006

Background: Chest wall deformities such as kyphoscoliosis, thoracoplasty, and fibrothorax cause ventilatory insufficiency that can lead to chronic respiratory failure, with recurrent fatal acute respiratory failure(ARF). This study evaluated the frequency and outcome of ARF, the physiologic status, and the long-term prognosis of these patients. Methods: Twenty-nine patients with chest wall disorders, who experienced the first requirement of ventilatory support from ARF were examined. The mortality and recurrence rate of ARF, the pulmonary functions with arterial blood gas analysis, the efficacy of home oxygen therapy, and the long-term survival rate were investigated. Results: 1) The mortality of the first ARF was 24.1%. ARF recurred more than once in 72.7% of the remaining 22 patients, and overall rate of successful weaning was 73.2%. 2) Twenty-two patients who recovered from the first ARF showed a restrictive ventilatory impairment with a mean FVC and TLC of 37.2% and 62.4 % of predicted value, respectively, and a mean $PaCO_{2}$ of 57mmHg. Among the parameters of pulmonaty functions. the FVC(p=0.01) and VC(p=0.02) showed a significant correlation with the $PaCO_{2}$ level. 3) There were no significant differences between the patients treated with conservative medical treatment only and those with additional home oxygen therapy due to significant hypoxemia in the patients with recurrent ARF and the mortality. 4) The 1, 3, 5-year survival rates were 75%, 66%, and 57%, respectively, in the 20 patients who had recovered from the first ARF, excluding the two patients managed by non-invasive nocturnal ventilatory support. Conclusion: These results suggest that active ventilatory support should be provided to patients with ARF and chest wall disorders. However, considering recurrent ARF and weak effect of home oxygen therapy, non-invasive domiciliary ventilation is recommended in those patients with these conditions to achieve a better long-term prognosis.