모드변환 가능한 단권변압기를 이용한 CMOS 전력증폭기

류현식(Hyunsik Ryu),남일구(Ilku Nam),이동호(Dong-Ho Lee),이옥구(Ockgoo Lee) 대한전자공학회 2014 전자공학회논문지 Vol.51 No.4

본 논문에서는 전력증폭기의 효율을 증가시키기 위해서 모드변환 가능한 단권변압기를 제안한다. 모드변환 가능한 단권변압기를 통해 전력증폭기의 저 전력 모드 동작 시 효율을 개선할 수 있다. 이 논문에서는 0.18-㎛ CMOS 표준 공정을 이용하여 듀얼모드 단권변압기를 이용한 CMOS 전력증폭기를 설계하였다. 고 전력 모드와 저 전력 모드에서 단권변압기의 1차 권선의 권선수를 조절하여 전력증폭기의 동작을 최적화하였다. EM 시뮬레이션 및 전체 회로 시뮬레이션 결과 제안된 멀티모드 CMOS 전력증폭기의 출력전력이 24dBm일 때 전력부가효율(PAE)이 10.4%에서 멀티모드 동작으로 26.1% 로 상승하여 전력증폭기의 성능 개선되었다. In this paper, in order to improve efficiency performance of power amplifiers, a mode changeable autotransformer is proposed. Efficiency performance at the low-power mode can be improved by adopting the mode changeable autotransformer. A dual-mode autotransfomrer CMOS power amplifier using a standard 0.18-㎛ CMOS process is designed in this work. Number of turns in a primary winding is re-configurated according to mode change between the high-power mode and the low-power mode. Thus, the efficiency performance of the power amplifier at each mode is optimized. EM and total circuit simulation results verify that low-power mode power added efficiency(PAE) at 24dBm output power is improved from 10.4% to 26.1% using the proposed multi-mode operation.

주요 수면유도제인 독실라민과 디펜히드라민의 급성 중독 비교

류현식 ( Hyun Sik Ryu ),이미진 ( Mi Jin Lee ),박성수 ( Seong Soo Park ),정원준 ( Won Joon Jeong ),김현진 ( Hyun Jin Kim ) 대한임상독성학회 2010 대한임상독성학회지 Vol.8 No.2

Purpose: The previous studies on H1 antihistamine overdose have generally been limited to cases of acute doxylamine succinate (DS) poisoning, yet there have been some studies on diphenhydramine (DPH) overdosing. But many clinicians consider the two drugs to be very similar and to have similar ingredients. The purpose of this study was to clarify the toxicologic characteristics and clinical outcomes between DS and DPH poisoning/overdose. Methods: We reviewed the medical and intensive care records of the patients with acute DS or DPH poisoning and who admitted to our emergency department from January 2008 and April 2010. We collected patient information regarding the features of the poisoning and the clinical and demographic characteristics. The patients were assessed for the clinical outcomes, the GCS, the PSS (Poisoning Severity Score) and the SOFA (Sequential Organ Failure Assessment). Results: Fifty seven patients (45 cases of DS poisoning and 12 cases of DPH poisoning) were enrolled. Compared with the DS group, the DPH group had higher incidences of intubation, serious mental change, QTc prolongation and ECG conduction abnormality (p=0.041, <0.001, 0.014 and 0.044, respectively). The DPH group had a higher PSS and a longer ICU stay. The peak CPK time and the CPK normalization time were longer for the patients with rhabdomyolysis due to DS poisoning. Conclusion: Two common H1 antihistamines, doxylamine and diphenhydramine, are in the same ethanolaminestructural class, but the toxico-clinical outcomes are different according to many aspects. Therefore, clinicians could take a careful approach for the differential diagnosis and management between DS and DPH poisoning.

모바일 망서버기반의 디지털 멀티미디어 플레이어 구현

윤달환,류현식 한국특허학회 2011 특허학연구 : 한국특허학회지 Vol.13 No.2

본 논문에서는 모바일 단말기를 통하여 촬영한 영상이미지를 송신하면, 영상데이터가 통신사 서버에 저장되고, 동시에 디지털 멀티미디어 프레임에 저장되는 시스템에 관한 것이다. 이때 디지털 멀티미디어 프레임은 네트워크로 통신사 서버에 가입되어 있어야 하며, 독립적으로 영상을 플레이할 수 있거나 저장할 수 있다. 저장 매체로서 멀티미디어 프레임 자체의 메모리 하드웨어, SD 또는 CF 메모리 스틱장치 및 USB를 이용할 수 있다.

중증 급성 담낭염 환자에서 응급실 내원 후 경피적 담낭배액술 시행까지의 적절한 시간

최준영,류현식,박성수,이재광,최현수,황승연,장지연,이세종,이혜지 대한응급의학회 2023 대한응급의학회지 Vol.34 No.1

Objective: Severe acute cholecystitis is an infectious disease that requires immediate gallbladder drainage. Although percutaneous transhepatic gallbladder drainage (PTGBD) is the most common method of gallbladder drainage, the optimal timing remains unclear. Methods: This study is a retrospective analysis of patients diagnosed with severe acute cholecystitis who underwent PTGBD between July 2018 to June 2021. This study investigated the effect of time from emergency department arrival to PTGBD (tPTGBD) on patient prognosis. Results: Totally, 48 patients were included in this study. Based on the cutoff value calculated using the Youden index, the group with tPTGBD of <5.93 hours had a shorter hospital stay (10 vs. 13.5 days, P=0.021), lower portion of progression (27:5 [15.6%] vs. 7:9 [56.3%], P=0.004), even they had a higher initial SOFA score (6 vs. 4.6, P=0.049). However, no statistical difference was obtained for the length of ICU stay between both groups (1 vs. 2, P=0.617). Conclusion: Executing PTGBD to severe acute cholecystitis patients within 5.93 hours after presenting at the emergency department is associated with reduced progression and hospital stay.

코로나바이러스감염증-19 범유행이 한국 대도시 응급실 이용에 미치는 장기 영향

황승연,이재광,류현식,박성수,최준영,이혜지,허승호,박영근,최현수 대한소아응급의학회 2021 대한소아응급의학회지 Vol.8 No.2

Purpose: As coronavirus disease 2019 pandemic has been prolonged, it became crucial to analyze the long-term impact of the pandemic on emergency department (ED) utilization for efficient use of emergency medicine resources. Methods: We reviewed the data of children (≤ 18 years) who visited the ED in Daejeon, Korea, from February 2019 through January 2021. This period was dichotomized by February 2020 into the reference and pandemic periods. The latter period was further divided into the early (February-August 2020) and late pandemic periods. Between the reference and pandemic periods, and between the early and late pandemic periods, we respectively compared proportions of children in all patients (including adults), age groups, high acuity (the Korean Triage and Acuity Scale 1-2), diagnostic codes, visits via ambulances, ED length of stay, and ED disposition. Results: Compared to the reference and early pandemic periods, the pandemic and late pandemic periods respectively showed changes as follows: proportion of children in all patients (from 29.8% to 19.0% and from 19.8% to 18.1%; all Ps < 0.001), children younger than 5 years (from 56.7% to 49.9% and from 52.1% to 47.4%; all Ps < 0.001), high acuity (from 12.0% to 7.8% [P < 0.001] and from 8.8% to 6.7% [P = 0.004]), “Injury, poisoning and certain other consequences of external causes (S00-T98; from 30.0% to 49.0% and from 48.3% to 49.8%),” and “Diseases of the respiratory system (J00-J99; from 29.6% to 10.3% and from 12.8% to 7.5%).” Increases in the visits via ambulances, ED length of stay, children undergoing intensive care unit hospitalization or death were noted only in comparison between the reference and pandemic periods. Conclusion: A long-term impact of the pandemic on ED use may be a decrease in the proportion of young or ill children.

디펜하이드라민 음독 후 의식 변화와 심전도 변화를 주소로 내원한 환자 1례

박철상,강인구,류현식,박성수,이미진,정원준 대한응급의학회 2010 大韓應急醫學會誌 Vol.21 No.3

The antihistaminic drug diphenhydramine is mainly used as a sedative, hypnotic and antiemetic. In many countries it is available over-the-counter, very common, and generally regarded as a harmless drug. However, diphenhydramine overdose can result in cardiotoxicity due to its ability to block fast sodium channels in a manner analogous to classic Vaughan-Williams type IA antidysrhythmic agents. As such, cardiotoxicity from diphenhydramine resembles that of the tricyclic antidepressant agents. Here we report a case of a 52 year old man who ingested 2,000 mg of diphenhydramine and presented with an altered mental state and an electrocardiographic change. His electrocardiogram showed sinus tachycardia with a rate 145beat/min, a QRS interval of 88 ms, and a QTc of 556 ms. He had a wide anion gap metabolic acidosis. He was treated with intravenous sodium bicarbonate and supportive therapy. His clinical manifestations waned and he was transferred to another hospital nearby his hometown

광천광산 주변 토양 중 석면 비산성 평가

김정욱,박창구,류현식,정명채 한국폐기물자원순환학회(구 한국폐기물학회) 2012 한국폐기물자원순환학회 춘계학술발표논문집 Vol.2012 No.-

석면 비산 장비를 이용한 토양 중 석면 비산 특성 및 위해성 평가

김인자,김정욱,류현식,정명채,Kim, In Ja,Kim, Jeong-Wook,Ryu, Hyun Sik,Jung, Myung Chae 한국지하수토양환경학회 2012 지하수토양환경 Vol.17 No.5

The objective of this study is to examine a releasable asbestos sampler developed for measuring friable asbestos from soil to air controlled by wind velocity and water contents. Asbestos contaminated soil with 3.75% at the Sinsuk-asbestos mine was sampled, air-dried and sieved to 100 mesh, then homogenized during 24 hours' agitation. Various wind velocities, 1 m/s, 2 m/s, 3 m/s, and 5 m/s, were applied to evaluate releasable characteristics of the releasable asbestos sampler. In addition, soils with 1.0%, 3.4%, 4.4%, 11.0%, 16.2%, and 20.0% of water contents were also examined the amount of friable asbestos by the releasable asbestos sampler. Collected soil and air samples were analyzed by polarized light microscopy (PLM) and phase contrast microscopy (PCM), respectively. Those contents were applied to calculate an excess life cancer risk (ELCR). This study also discussed the relationship with risk assessment by a weeding scenario of activity based sampling (ABS) and field applied releasable asbestos sampler. The result was shown that friability of asbestos in soil increased with wind velocity and decreased with water content. In comparison with ELCR results, over 10E-4 of cancer risk was found in condition on < 5% water content and > 3m/s wind velocity.

파라쿼트 중독 환자에서 sodium dithionite를 이용한 소변 발색의 정도를 색도계로 측정하여 혈중 파라쿼트 농도를 추정할 수 있는가?

강인구,정원준,박철상,류현식,김현진,박성수,이미진,이원석 대한응급의학회 2011 대한응급의학회지 Vol.22 No.6

Purpose: Plasma Paraquat level is one of the most important prognostic factors used in identifying Paraquat poisoning. Urine sodium dithionite tests are widely used in clinical settings for detecting the presence of Paraquat chemicals and predicting prognosis, but this test is subjective and qualitative. In this prospective study, we evaluated the correlation between sodium dithionite test results as measured by a colorimeter,versus actual plasma or urine Paraquat levels. Methods:Plasma and urine sample were taken from patients upon arrival at a local emergency center (ED) within 12 hours after Paraquat ingestion. Urine was tested using sodium dithionite reaction and the resulting urine color was measured by colorimeter to result in an L (lightness) value. Results: A total of 23 patients were enrolled in this study with a mean age of 57 years old, mean Paraquat intoxication volume of 94 mL, and mean Paraquat intoxication prior to ED arrival of 3.2 hours. The patients’ mean blood Paraquat concentration was 82.23 μg/ml and urine Paraquat concentration was 169.19 μg/ml. Using the sodium dithionite test, 17 patients were diagnosed as beyond ‘strong positive’. L values were correlated with intoxication volumes, blood Paraquat concentrations, and urine Paraquat concentrations. Blood Paraquat concentrations showed significant correlation with L value, poison volume,urine Paraquat volume, and creatinine values. Conclusion: The greater the intoxicated Paraquat volume,blood Paraquat concentration, and urine Paraquat concentration,the lower the L value.

냉동 타조육의 선도관리를 위한 최적의 해동속도산출에 관한 연구

김혜경,박진구,김양규,류현식,박성희,민상기 한국축산식품학회 2004 심포지움 및 학술발표회 Vol.- No.34

본 연구는 풍속을 다양하게 적용하여 냉동 타조육을 해동시킨 뒤 육의 이화학적 상태 변화를 조사함으로써 타조육 본연의 품질을 유지할 수 있는 최적의 해동조건을 찾고자 실시하였다. 타조 신선육의 pH는 5.87로서 일반 원료육의 pH 범위인 5.8~6.2 내에 있었고 해동속도가 빠를수록 타조육의 pH는 감소했다. 타조육의 thawing loss는 해동속도가 빨라질수록 감소했다. 해동속도에 따른 WHC는 대부분 신선육의 경우와 비슷했으나, 자연대류인 0.3027cm/h와 강제대류 중 0.6787cm/h의 경우에는 신선육보다 4~7% 보수력이 낮게 나타났다. 해동온도에 따른 color의 변화는 조건별로 거의 차이가 나지 않았다. 또한 해동육의 경우 신선육에 비해 TBA 값이 큰 폭으로 상승했고, 특히 강제대류 중 해동 속도가 가장 느린 0.3261cm/h의 경우 가장 높았다. VBN 값은 해동속도에 상관없이 12~13mg% 대였으며 동결육은 신선육보다 2.5배나 높은 값을 나타내었다.