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고령 고혈압 환자에서 천일염의 혈압 감소 효과: 예비 무작위 대조시험
백승하,안주원,이혜리,조수현,김정하 대한임상건강증진학회 2015 Korean Journal of Health Promotion Vol.15 No.3
Background: High sodium and/or low mineral intake are known to be associated with elevated blood pressure. It has been reported that substituting low-sodium, mineral-rich salt for refined salt lowers blood pressure (BP). And solar salt is emerging as a low sodium high mineral salt for a healthy diet in Korea. Therefore, this double- blind, randomized, and placebo-controlled trial was conducted to explore changes in BP from substituting refined salt with solar salt among hypertensive elderly subjects. Methods: Forty-three hypertensive and institutionalized elderly individuals aged 65 years or older were enrolled. Thirty-eight subjects (88.4%) completed the study. Subjects were provided with either a solar salt- or refined salt-based diet for eight weeks. Results: Systolic BP decreased significantly in the solar salt-based diet group after 2, 4, and 8 weeks when compared to the refined salt-based diet group. And, diastolic BP was lowered significantly in the solar salt-based diet group compared to that in the refined salt-based diet group after 8 weeks. In addition, urinary sodium/potassium, and angiotension converting enzyme activity decreased significantly in the solar salt-based diet group compared to the refined salt-based group. Urinary potassium excretion was significantly increased in the solar salt-based diet group. Conclusions: These results may provide clinical evidence that solar salt has beneficial effects on BP in elderly patients. And, people such as Koreans, who do not consume enough minerals, may experience a greater anti- hypotensive effect by using solar salt. However, further large-scale studies are necessary. 연구배경: 나트륨 과다 섭취와 적은 미네랄 섭취는 혈압상승과 연관된 것으로 알려져 있으며, 정제 소금을 저염도, 고미네랄 천일염으로 대체하는 것은 혈압을 낮춘다고 보고되고 있다. 천일염은 한국에서 건강한 식습관을 위한 저염도, 고미네랄 소금으로 부상되고 있다. 따라서 정제 소금을 천일염으로 대체한 고령 고혈압 환자의 혈압 변화에 대하여 연구하기 위하여 무작위 이중 맹검 위약 대조시험을시행하였다. 방법: 43명의 65세 이상 노령 고혈압 환자가 이 실험에최초 등록되었고, 이 중 38명(88.4%)이 시험을 완료했다. 연구 대상은 실험군으로 천일염 그리고 대조군으로 정제염을섭취하는 식생활을 8주 동안 진행하였다. 결과: 천일염을 섭취하는 집단은 정제염을 섭취하는 대조집단과 비교하였을 때 수축기 혈압이 2, 4, 8주 후에 크게감소하였고, 확장기 혈압 또한 8주 후에 크게 떨어졌다. 또한 천일염을 섭취하는 집단에서는 소변 중 나트륨/칼륨과ACE 활동이 정제염을 섭취하는 집단보다 크게 감소하였다. 소변 중 칼륨 배설 또한 크게 증가하였다. 결론: 이러한 결과는 고령 환자에서 천일염이 혈압에 유익한 효과가 있다는 임상 증거를 제공하고 있으며, 한국인과 같이 충분한 미네랄 섭취가 부족한 경우에 천일염을 사용하여 더 큰 항고혈압 효과를 가질 수도 있을 것으로 보인다. 따라서 추가적인 대규모 연구가 요구된다.
백승하,조재호,김강진,안승호,명차리,박심수 한국자동차공학회 2020 International journal of automotive technology Vol.21 No.5
Worldwide regulations on particulate matter for passenger vehicles have become stricter in recent years, which makes it difficult to satisfy for gasoline direct injection (GDI) vehicles. In this study, the level of reduction efficiency of particle emissions with a metal-foam gasoline particulate filter (GPF) for the turbocharged GDI vehicle was evaluated in the federal test procedure (FTP)-75 mode operation. The particle number (PN) emissions were analyzed using the AVL particle counter (APC) and fast response differential mobility spectrometer (DMS500) for particle size distribution. The PN concentration from the base GDI vehicle with only TWC is 1.64 E+12 number/km (#/km), while the value of the GPFequipped case is 5.02 E+11 #/km with 69 % filtration efficiency in the vehicle test mode. In particular, the reduction rate of small particles under 23 nm in size was strongly improved with the additional installation of the metal-foam GPF. The maximum pressure drop through the GPF reached approximately 39 mbar at the highest acceleration point of phase 1 of the FTP-75 mode. The upstream temperature of the GPF was distributed at approximately 380 ~ 510 oC in the vehicle test. The results show that the GPF-equipped GDI vehicle can satisfy the stringent particle regulation by Euro 6 in a straightforward manner.
2차-RC 필터와 Sample-Hold 커패시터로 구성된 루프 필터와 단방향 전하펌프를 가진 PLL
백승하,최영식,Baek, Seung-Ha,Choi, Young-Shig 한국정보통신학회 2013 한국정보통신학회논문지 Vol.17 No.10
이 논문에서는 2차-RC 필터와 sample-hold 커패시터로 구성된 루프필터와 단방향 전하펌프를 가진 위상고정루프를 제안하였다. 제안된 위상고정루프의 목적은 전하펌프의 전류 불일치에 의한 기준 신호 의사 잡음을 개선 한다는 것이다. 또한 이를 통하여 위상 잡음 특성도 개선하였다. 회로는 1.8V $0.18{\mu}m$ CMOS 공정의 파라미터를 이용하여 HSPICE로 시뮬레이션을 수행하였고 회로의 동작을 검증하였다. A PLL with an unipolar charge pump and a loop filter consisting of sample-hold capacitor and 2nd-order RC filter has been proposed. The goal of the proposed PLL is the suppression of reference spur which is caused by charge pump mismatch. It also improves phase noise characteristic. It has been designed with a 1.8V $0.18{\mu}m$ CMOS process and proved by HSPICE simulation.
백승하,박성욱 대한임상독성학회 2022 대한임상독성학회지 Vol.20 No.2
Purpose: This study sought to compare the characteristics of patients with pathogen-positive and negative cultures, and to investigate factors predicting pathogen-positive culture results in patients of acute poisoning with suspected aspiration. Methods: Consecutive patients with acute poisoning admitted to an intensive care unit between January 2016 and December 2018 were retrospectively studied. Respiratory specimens were collected from the enrolled patients at the time of the suspected aspiration. We compared the characteristics of patients with pathogen-positive and negative culture results and analyzed the causative pathogens. Results: Among the 526 patients, 325 showed no clinical features that could be attributed to aspiration, and 201 patients had clinical features suggestive of aspiration. Of these, 113 patients had pathogen-positive culture, 61 were negative, and the specimens of 27 patients contained poor-quality sputum. In univariate analysis, patients with a positive culture showed a longer time to culture from ingestion (p=0.01), faster heart rate (p=0.01), and higher partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2) (p=0.02) than patients with negative culture. Multivariate analysis demonstrated that PaO2/FiO2 (adjusted odd ratio, 1.005; 95% confidence interval [CI], 1.002-1.008; p=0.005) was a significant risk factor for pathogen-positive culture. The area under the receiver operating characteristic curve of PaO2/FiO2 was 0.591 (95% CI, 0.510-0.669, p=0.05). Gram-negative pathogens (GNPs) were predominant and at least one GNP was observed in 84 (73.3%) patients among those with pathogen positive culture. Conclusion: We failed to find any clinical factors associated with positive culture results. Antibiotics that cover GNPs could be considered when deciding the initial antibiotic regimen at the time of suspected aspiration.