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간경변증 환자에서 도플러 초음파를 이용한 신저항 계수(RI)의 임상적 의의
홍영선,박사영,심기남,김도영,문일환,유정현 梨花女子大學校 醫科大學 醫科學硏究所 1996 EMJ (Ewha medical journal) Vol.19 No.1
Cirrhotic patients may exhibit circulatory derangement and renal dysfunction during the clinical course. Renal dysfunction on cirrhosis can occur without specific causative factors. This functional renal failure in cirrhosis is considered as a consequence of renal vasoconstriction. These alteratons of renal hemodynamics are already present in the early phase of the disease, even in the condition that the conventional kidney function tests are normal. A new method for noninvasive evaluation of arterial tone is duplex Doppler sonography. Among the various sonographic indices proposed, the renal resistive index(RI) is the most widely used for the estimation of intrarenal arteriolar vascular resistence. This study was performed to evaluate the role of Doppler sonography in early detection of renal dysfunction and to assess the clinical significance of RI. In 25 cirrhotic patients without overt kidney failure and ten control subjects, the RI of the acurate artery in both kidneys was measured by Doppler sonography. The mean RI of cirrhotic group was significangly higher than that of control subjects(0,68±0.08 vs -0.62 ±0.05,p<0). Accordiing to Child class, the RI showed increasing tendency from A to C, through witout statistical significance. In this study, the RI was significantly inversely correlated with 24hr urinary sodium amount(r=-0.39, p<0,05)and correlated with serum creatinine(r=6.60,p<0.01). This study indicates that the measurement of RI is a sensitive method to assess intarenal hemodynamics and to detect early changes of the renal dysfunction in cirrhotic patients.
와편의 연대결정에서 SAAD방법과 SAR방법으로 측정한 연대측정 결과 비교
김현식,홍사용,서만철 공주대학교 문화재보존과학연구소 2003 문화재과학기술 Vol.2 No.1
경기도 하남시 천왕사지에서 채취한 와편으로부터 석영을 분리하여 SAAD방법과 SAR방법을 적용 연대를 측정하였다. SAAD 방법에 의한 자연축적선량 값은 5.37±0.32Gy, SAR 방법에 의한 값은 5.40±0.22Gy이었다. 이것은 오차범위 내에서 일치하는 값이다. 연간선량은 4.31±0.17Gy/ka로, 측정연대는 SAAD방법의 경우 AD 756±53년, SAR방법의 경우 AD 750±45년이다. The roof tiles excavated from Cheonwangsaji at Hanam-shi in Gyeonggi province were dated by using SAAD and SAR protocols. The paleodoses by SAAD and SRR protocols were 5.37±0.32 Gy and 5.40±0.22 Gy, which were agreed with in the range of the measurement error. The evaluated dose rate from the soil around the excavated roof tiles and the tile themselves was 4.31±0.17Gy/ka and the ages of the roof tiles were determined to be (756±53)AD by SAAD and (750±45)AD by SAR.
벡터드라이버를 이용한 편측형 선형유도전동기 구동특성에 관한 연구
장용해,임홍우,신사현,조금배,백형래 조선대학교 에너지.자원신기술연구소 2001 에너지·자원신기술연구소 논문지 Vol.23 No.2
The input voltage of Single-sided linear induction motors (SLIMs) is involved with the time harmonics because most LIM is driven by inverter. Therefore the equivalent circuit for an inverter-fed SLIM has t o be modifided to represent every harmonic present in supply voltage. This paper describes that the dynamic characteristic can be used effectively for analyzing the characteristics of a single-sided linear induction motor using vector driver for PI controller.
Experimental Study on Impact Loads Acting on Free-falling Modified Wigley
Hong, Sa-Young,Kim, Young-Shik,Kyoung, Jo-Hyun,Hong, Seok-Won,Kim, Yong-Hwan Korean Society of Ocean Engineers 2012 International journal of ocean system engineering Vol.2 No.3
The characteristics of an impact load and pressure were experimentally investigated. Drop tests were carried out using a modified Wigley with CB = 0.56. The vertical force, pressures, and vertical accelerations were measured. A 6-component load cell was used to measure the forces, piezo-electric sensors were used to capture the impact pressure, and strain-gauge type accelerometers were used to measure the vertical accelerations. A 50-kHz sampling rate was applied to capture the peak values. The repeatability of the measured data was confirmed and the basic characteristics of the impact load and pressure such as the linearity to the falling height were observed for all of the measurements. A simple formula was derived to extract the physical impact load from the measured force based on a simple mass-sensor-mass diagram, which was validated by comparing impact forces with existing data using the mathematical model of Faltinsen and Chezhian (2005). The effects of the elasticity of the model and change in acceleration during the water entry were investigated. It is interesting to observe that the impact loads occurred and reached peak values at the same time duration after water entry for all drop heights.
( Hyun Soo Park ),( Won Joon Seong ),( Joon Seok Hong ),( Hyun Joo Seol ),( Han Sung Hwang ),( Kunwoo Kim ),( Hyun Sun Ko ),( Dong Wook Kwak ),( Soo Young Oh ),( Moon Young Kim ),( Sa Jin Kim ) 대한산부인과학회 2015 Obstetrics & Gynecology Science Vol.58 No.6
Objective To analyze practice patterns and checklists of second trimester ultrasonography, and to investigate management plans when soft markers are detected among Korean Society of Ultrasound in Obstetrics and Gynecology (KSUOG) members. Methods An internet-based self-administered questionnaire survey was designed. KSUOG members were invited to the survey. Checklists of the second trimester ultrasonography were also requested. In the questionnaire survey, general practice patterns of the second trimester ultrasonography and management schemes of soft markers were asked. In the checklists analysis, the number of items were counted and also compared with those recommended by other medical societies. Results A total of 101 members responded. Eighty-seven percent routinely recommended second trimester fetal anatomic surveillance. Most (91.1%) performed it between 20+0 and 23+6 weeks of gestation. Written informed consents were given by 15.8% of respondents. Nearly 60% recommended genetic counseling when multiple soft markers and/or advanced maternal age were found. Similar tendencies were found in the managements of individual soft markers. However, practice patterns were very diverse and sometimes conflicting. Forty-eight checklists were analyzed in context with the number and content of the items. The median item number was 46.5 (range, 17 to 109). Of 49 items of checklists recommended by International Society of Ultrasound in Obstetrics and Gynecology and/or American Congress of Obstetricians and Gynecologists, 14 items (28.6%) were found in less than 50% of the checklists analyzed in this study. Conclusion Although general practice patterns were similar among KSUOG members, some of which were conflicting, and there is a need for standardization of the practice patterns and checklists of second trimester ultrasonography, which also have very wide range of spectrum.
Wind Vector Retrieval for the Coastal Region and In-land Lake Areas form RADARSAT Data
Hong, Sa Hyun,Kim, Suk Jin,Moon, Wooil M. 대한원격탐사학회 2001 International Symposium on Remote Sensing Vol.17 No.1
Synthetic aperture radars (SAR) have higher spatial resolution than scatterometers and we can obtain mare detailed wind vector information from space-borne SAR data. This type of high spatial resolution wind information can be very useful particularly in coastal regions and in..land lakes, where the scatterometer wind information can be altered by the boundary effects because the larger foot-print spatial averaging of backscattered energy is unavoidable. This paper tested RADARSAT data with CMOD_4/_IFR2 and SWA algorithms for extracting wind information over selected coastal test areas around the Korean peninsula and two in-land lakes in Canada. Because the CMOD algorithms were originally developed for the C-band, VV Polarized scatterometer data, we applied currently available polarization ratio models (e.g. Kirchhaff, Elfauhaily and Thompson models,) for RADARSA'T data processing. The SAR wind algorithm (SWA) is based on a relation between the smearing effects in the SAR irriage and the wind field. Application of Space-borne SAR data for in-land lake hydrodynamics is a significant new application. Results from several test sites are compared and validated against coincident nearby meteorological station data and/or buoy data, demonstrating good wind estimation accuracy, and proving SAR resolution capabilities in operational mode.
스펙트랄요소법(SEM)을 이용한 파랑-조류 상호작용 현상 수치해석 연구
성홍근(Hong Gun Sung),홍기용(Key Yong Hong),경조현(Jo Hyun Kyung),홍사영(Sa Young Hong) 한국항해항만학회 2006 한국항해항만학회 학술대회논문집 Vol.3 No.1
본 논문에서는 Freak Wave의 생성원인에 대하여 간략히 논의하였으며, 이 중 파랑-조류 비선형 상호작용에 대한 이론 및 수치적 해석기법의 역사와 장단점 등을 기술한다. 본 연구에서는 파랑-조류 상호작용에 대한 수치모델링 및 해석 기법을 개발하고 있다. 개발 중인 수치해석 기법은 공간적으로 불균일한 조류와 파랑의 비선형 상호작용을 해석하기 위하여 Navier-Stokes 방정식을 이용하여 유동현상을 모델링하였으며, 이산화를 위하여 스펙트랄요소법(Spectral Element Method; SEM)을 이용하였다. 또한 자유표면의 운동을 효과적으로 기술하기 위하여 ALE(Arbitrary Lagrangian-Eulerian)기법을 사용하였다. 본 연구의 유동 모델과 수치해석기법의 과정과 특성, 그리고 장점 등에 대하여 논의하였으며, 초기적인 수치해석 결과를 제시하였다. 이를 바탕으로 개발된 수치해석기법의 정확성 및 수렴성을 확인할 수 있다. In this paper, generation mechanisms of ocean freak waves are briefly introduced in the context of wave-current interaction phenomena. The present model of the fluid motion is based on the Navier-Stokes equations incorporating velocity-pressure formulation because of need to model the nonlinear wave interaction with spatially non-uniform current field. In order to deal with the free surface motion, an Arbitrary Lagrangian-Eulerian (ALE) description is adopted. As on accurate and efficient numerical tool, the spectral element method is presented with general features and specific treatment for the wave-current interaction problem. As an intermediate stage of development, solution procedure and characteristic aspects of the present modeling and numerical method are addressed in detail, and preliminary numerical results prove its accuracy and convergence.