• Journal of the Korean Society for Nondestructive Testing
• /
• v.33 no.3
• /
• pp.270-275
• /
• 2013

In this study, focusing of ultrasonic Lamb wave by negative refraction with mode conversion from antisymmetric to symmetric mode was investigated. When a wave propagates backward by negative refraction, the energy flux is antiparallel to the phase velocity. Backward propagation of Lamb wave is quite well known, but the behavior of backward Lamb wave at an interface has rarely been investigated. A pin-type transducer is used to detect Lamb wave propagating on a steel plate with a step change in thickness. Conversion from forward to backward propagating mode leads to negative refraction and thus wave focusing. By comparing the amplitudes of received Lamb waves at a specific frequency measured at different distance between transmitter and interface, the focusing of Lamb wave due to negative refraction was confirmed.

• Tuberculosis and Respiratory Diseases
• /
• v.86 no.2
• /
• pp.142-149
• /
• 2023

Background: Coronavirus disease 2019 (COVID-19) is an ongoing global public health threat and different variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have been identified. This study aimed to analyse the factors associated with negative conversion of polymerase chain reaction (PCR) and prognosis in critically ill patients according to the SARS-CoV-2 variant. Methods: This study retrospectively analysed 259 critically ill patients with COVID-19 who were admitted to the intensive care unit of a tertiary medical center between January 2020 and May 2022. The Charlson comorbidity index (CCI) was used to evaluate comorbidity, and a negative PCR test result within 2 weeks was used to define negative PCR conversion. The cases were divided into the following three variant groups, according to the documented variant of SARS-CoV-2 at the time of diagnosis: non-Delta (January 20, 2020-July 6, 2021), Delta (July 7, 2021- January 1, 2022), and Omicron (January 30, 2022-April 24, 2022). Results: The mean age of the 259 patients was 67.1 years and 93 (35.9%) patients were female. Fifty (19.3%) patients were smokers, and 50 (19.3%) patients were vaccinated. The CCI (hazard ratio [HR], 1.555; p<0.001), vaccination (HR, 0.492; p=0.033), and Delta variant (HR, 2.469; p=0.002) were significant factors for in-hospital mortality. The Delta variant (odds ratio, 0.288; p=0.003) was associated with fewer negative PCR conversion; however, vaccination (p=0.163) and remdesivir (p=0.124) treatments did not. Conclusion: The Delta variant of SARS-CoV-2 is associated with lower survival and negative PCR conversion. Contrary to expectations, vaccination and remdesivir may not affect negative PCR conversion in critically ill patients with COVID-19.

• Journal of The Korea Institute of Healthcare Architecture
• /
• v.29 no.4
• /
• pp.29-35
• /
• 2023

Purpose: The 2015 Middle East Respiratory Syndrome (MERS) outbreak and the recent COVID-19 pandemic have highlighted the lack of negative pressure isolation rooms and the fragility of the healthcare system. The need for healthcare facility transformation for respiratory infectious diseases has become more prominent due to COVID-19, and the purpose of this study is to provide a foundation for the rapid, economical, and safe construction of negative pressure isolation wards. Methods: This study analyzes the current status of hospitals that have been converted to negative pressure isolation rooms, and provides architectural plans and examples to provide a reference for bedroom change. Research data of this study have been obtained by analyzing the drawings of negative pressure isolation wards of nationally designated inpatient treatment beds and urgent isolation beds. In addition, the relevant literature of urgent isolation beds has been analyzed to derive bedroom change type. Result: In this study, a total of 21 isolation bed conversion methods have been presented. Implications: In order to change efficiently from a general ward to an isolation ward, it is necessary to consider the actual hospital's infectious disease transmission patterns and facility conditions.

• Journal of Preventive Medicine and Public Health
• /
• v.28 no.2 s.50
• /
• pp.487-496
• /
• 1995

This study was performed for the comparison of the therapeutic efficiency between 6-month (2HERZ/4HER) and 9-month (9HER) short-course chemotherapy under the programe conditions for pulmonary tuberculosis in terms of sputum AFB negative conversion rate, remedial interruption rate and cost effectiveness analysis. Two hundreds and ninty three patients treated with 9HER and 641 treated with 2HERZ/4HER had been discharged from 22 health centers in Seoul from May 1, 1993 to April 30, 1994. Seven hundreds and seventeen was subsequently analysed excluding 217 patients due to remedial interruption. The results : 1. Bacteriological negative conversion rate in 9HER regimen and 2HERZ/4HER regimen was 97.8% and 96.4% respectively(p>0.05). But the early treatment period, negative conversion rate in 2HERZ/4HER regimen was very higher than in 9HER regimen(p<0.01). 2. Remedial interruption rate for 9HER regimen and 2HERZ/4HER regimen was 34.1% and 13.6% respectively. The primary reason for the interruption was transfering to other clinics and this interruption was high within 3months. 3. Cost effectiveness for 2HERZ/4HER regimen was higher than 9HER regimen. The difference cost effectiveness ratio was 2.33 at the first sputum test and 1.69 at the last sputum test.

• Journal of Chest Surgery
• /
• v.21 no.1
• /
• pp.109-115
• /
• 1988

With the decreasing incidence of new cases and the highly effective results with antituberculous drug therapy, there is a marked decline in the need for surgery which was formerly such an important part in the successful program of management of this disease. During the period of two years and a half from Jun. 1984 to Dec. 1986, this study represents an analysis of 163 cases of several surgical management for eventual control of pulmonary tuberculosis at National Kon-ju tuberculosis Hospital. 1. Mode of surgical treatment was: Resection; 123 cases [Pneumonectomy: 83, lobectomy: 35, lobectomy plus segmentectomy; 4 segmentectomy: 1], thoracoplasty: 20 and others: 20. 2. Age distribution ranged 16and 68 with average of 34 years. Male and female ratio was 1.2: 1. 3. Surgical indications were: totally destroyed lung; 64, Destroyed lobe of segment; 13, cavity positive sputum; 10, cavity c negative Sputum; 6, Bronchostenosis c atelectasis; 2, empyema c or s BPF; 46, Aspergilloma; 8, Questions of Associated tumor; 4 and other 5. 4. Incidence of Complications was 10.4% and the mortality was 5.5 percent. The cause of mortality were analyzed. The main causes of death were respiratory insufficiency; 4, fulminant hepatitis; 1, hemorrhage; 1 and unknown; 1 in pneumonectomy, and asphyxia; 1 in lobectomy and sepsis; 1 in other procedure. 5. Conversion rare of positive sputum to negative state related to resectional surgery was 91.5%. In pneumonectomy, drug resistant group preoperatively showed 88.1% conversion rate postoperatively and drug sensitive group showed that 100% conversion rate. In lobectomy, both drug resistant and sensitive groups showed that 100% conversion rate postoperatively.

• The Korean Journal of Nuclear Medicine
• /
• v.34 no.2
• /
• pp.129-134
• /
• 2000

Purpose: It is difficult to determine the activity of tuberculosis radiologically. Therefore there have been efforts to assess the activity using radiopharmaceuticals such as $^{67}Ga,\;^{99m}Tc-tetrofosmin,\;and\;^{99m}Tc-MIBI$. But there may be some discrepancy in defining the term 'activity' between clinicians and nuclear physicians. While negative conversion of sputum acid fast bacilli (AFB) is defined as 'disappearance of activity' by clinicians, a loss of uptake in previously positive lesion is accepted as 'disappearance of activity' by nuclear physicians. We designed a prospective study to see if the negative conversion of sputum AFB could directly match the disappearance of radioactivity of the lesion. Materials and Methods: Fifteen patients with bacteriologically confirmed active localized pulmonary tuberculosis were scanned 10 and 60 min after intravenous injection of 550 MBq $^{99m}Tc$-MIBI. In 6 patients, who showed negative conversion of sputum AFB after 3-7 months of chemotherapy, $^{99m}Tc$-MIBI scan was repeated. For the purpose of comparison, target/nontarget ratios of the lesions were determined. Results: 12/15 (80%) patients with active pulmonary tuberculosis showed increased uptake of $^{99m}Tc$-MIBI in tuberculous lesion. After negative conversion of sputum AFB, 5/6 (83%) patients still showed increased uptake, although the intensity of uptake decreased. Conclusion: Uptake of radioactivity decreased but did not disappear after negative conversion of sputum AFB. $^{99m}Tc$-MIBI scan may be useful to address the degree of inflammation of pulmonary tuberculous lesion, but the uptake did not directly match the activity defined by positivity of sputum AFB. We nuclear physicians might have used the term 'activity' somewhat differently from clinicians who treat patients with tuberculosis.

• Journal of Digital Contents Society
• /
• v.15 no.6
• /
• pp.751-761
• /
• 2014

Color deficient people do not have sufficient discernment for the colors with low saturation and brightness and at the same time express their negative emotions regarding emotion distortion. The purpose of recovering the distortion of the vision which is the basis for emotion is to increase positive emotions rather than negative ones that those with color vision deficiency feel when they experience digital culture contents. Contrast increases saturation and brightness by differing the direction of their conversion and by doing so, delivers emotion distortion such as dynamic vs. static and vivid vs. somber that the original images intend to convey to those with color vision deficiency by reducing such a contrast. In this respect, this study proposes a contrast-based color conversion method to convert saturation and brightness in the zone of color conversion and identifies if this method can reduce emotion distortion by using color conversion simulation and user test.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.27 no.4
• /
• pp.283-290
• /
• 2022

This study proposes a voltage control scheme in a synchronous reference frame to improve the dynamic characteristics of double-conversion UPSs. UPSs need to control positive and negative sequence voltage, so that positive and negative sequence extractors are generally used to obtain each sequence of the voltage and current. Voltage and current controllers for each sequence are implemented. However, the extractor causes considerable delay, and the delay restricts the control performance, especially for the current controller. To improve the dynamics of the current controller, the proposed scheme adopts a unified current controller without separating positive and negative sequences. By using discrete-time current controller, the control bandwidth can be extended significantly so that negative sequence current can be controlled. To enhance the performance, an additional feed-forward technique for output voltage regulation is proposed. The validity of the proposed controller is verified by experiments.

• Korean Journal of Human Ecology
• /
• v.20 no.4
• /
• pp.849-860
• /
• 2011

This study explores a structural model to examine the relationship between web browsing motivation, retail strategy and purchase conversion for apparel on shopping websites. A self-administered questionnaire based on existing scales includes web browsing motivation, retail strategy, and purchase conversion intention of apparel on the shopping websites. A total of 499 usable questionnaires were obtained from consumers aging 20 to 49 who reside in metropolitan cities in Korea. For data analysis, descriptive statistics, exploratory factor analysis, confirmatory factor analysis, and structural equation models were used via SPSS 12.0 and LISREL 8.8. Findings concluded that web browsing motivations consisted of three factors: hedonic, informational, and recreational browsing for apparel. Hedonic browsing had a negative effect on purchase conversion intention, whereas informational browsing had a positive effect on the purchase conversion intention for apparel on shopping sites. Retail strategies on the website were classified into service, merchandise assortment, and price & promotion; the three elements of retail strategies mediated the relationship between web browsing motivations and purchase conversion intention for apparel. Specially, merchandise assortment had significantly direct effect on the purchase conversion intention of apparel on shopping websites. Managerial implications were discussed for fashion marketers to develop retail strategies and web content in order to convert web browsers or visitors into purchasers.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.9
• /
• pp.1567-1572
• /
• 2007

New pyrrolidinium and piperidinium bis(trifluoromethanesulfonyl)imide (TFSI) ionic liquids (ILs) having allyl substituents were synthesized and characterized. All of them are liquid at room temperature and stable up to 300 oC. The pyrrolidinium-based ILs showed better conductivities and lower viscosities than the corresponding piperidinium-based ILs. Among them, 1-allyl-1-methylpyrrolidinium TFSI showed the lowest viscosity of 52 cP, the highest conductivity of 5.7 mS cm?1, and the most negative cathodic voltage window of ?3.2 V (vs. Fc/Fc+) on a platinum electrode, which are the improved results compared to the corresponding analogue having a saturated substituent, 1-methyl-1-propylpyrrolidinium TFSI.