• 비파괴검사학회지
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• 제33권3호
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• pp.270-275
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• 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
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• 제86권2호
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• pp.142-149
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• 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.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제29권4호
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• pp.29-35
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• 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
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• 제28권2호
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• pp.487-496
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• 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
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• 제21권1호
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• pp.109-115
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• 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.

• 대한핵의학회지
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• 제34권2호
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• pp.129-134
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• 2000

목적: 흉부방사선 사진으로 결핵의 진단과 활동성의 판정이 어려운 경우가 많다. 이에 핵의학적 방법으로 결핵의 활동성을 판정하고자 하는 시도들이 있었으며, 핵의학 검사는 결핵의 활동성을 잘 반영하는 것으로 알려져 왔다. 그러나 객담결핵균의 음전을 '활동성'의 소실이라고 표현하는 치료자와 방사능섭취 소실을 '활동성'의 소실이라고 판정하는 핵의학의사 사이에는 용어 사용상의 차이가 있을 수 있다. 객담결핵균의 음전과 방사능섭취의 소실이 서로 일치하는지 여부를 확인하여 보고자 하였다. 대상 및 방법: 세균학적으로 활동성 결핵으로 진단된 15명의 환자들에서 $^{99m}Tc$-MIBI를 이용하여 폐스캔을 시행하였다. 3-7개월간의 항결핵약물치료로 객담 결핵균이 음전된 6명의 환자에 대해 $^{99m}Tc$-MIBI 스캔을 다시 시행하였다. 결핵병소와 정상 폐 부위의 방사능을 측정하여 정상 폐에 대한 결핵병소의 방사능 섭취율을 비교하였다. 결과: 활동성 폐결핵 환자 15명 중 12명(80%)에서 $^{99m}Tc$-MIBI 스캔 양성을 보였다. 항결핵약물치료로 객담 결핵균이 음전된 후 6명에서 $^{99m}Tc$-MIBI 스캔을 반복했을 때 6명 모두에서 섭취율이 치료 전에 비해서 감소하는 경향을 보였다. 그러나 5명에서는 정상 폐에 비해서는 여전히 높았다. 결론: $^{99m}Tc$-MIBI 스캔은 폐결핵 병변에서 염증반응의 정도를 판정하는데 도움이 된다. 그렇지만 객담 결핵균의 음전으로 정의되는 '활동성'과 1:1로 일치하지는 않았다.

• 디지털콘텐츠학회 논문지
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• 제15권6호
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• pp.751-761
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• 2014

색각 이상자들은 채도와 명도가 낮은 색채들에 대해 분별력을 갖지 못할 뿐 아니라 감성 왜곡과 관련하여 부정적인 감성을 표출한다. 감성의 기본이 되는 감각에 대한 왜곡을 바로 잡고자 함은 색각이상자들이 디지털 문화콘텐츠에 접할 때 느끼는 부정적인 감성보다 긍정적인 감성을 높이기 위해서이다. 대비는 채도와 명도간의 변환되는 방향이 다르게 하여 높이고, 이를 통해 원본 이미지가 전달하는 동적과 정적, 선명함과 칙칙함이라는 감각 왜곡을 감소시켜 색각 이상자에게 전달한다. 이를 색변환이 이뤄지는 영역에 대하여 채도와 명도를 변환하는 대비기반 색변환 방법을 제안하고 이 방법이 감각 왜곡을 감소시킨다는 것을 색변환 시뮬레이션과 사용자 테스트를 사용하여 확인한다.

• 전력전자학회논문지
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• 제27권4호
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• pp.283-290
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• 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.

• 한국생활과학회지
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• 제20권4호
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• pp.849-860
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• 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
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• 제28권9호
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• pp.1567-1572
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• 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.