PSC-I 철도교의 가로보에 따른 동특성 및 동적안정성 분석

윤지홍,최권영,권구성,정원석 한국방재학회 2012 한국방재학회논문집 Vol.12 No.4

Railway bridges are highly susceptible to resonance due to the equidistant axle load with constant speed of train. Thus, it is inevitable verify dynamic characteristics and quantities against dynamic guidelines. Recently, PSC-I composite bridge are being used actively due to economic advantages such as 20~30 m span bridge at home and abroad. This study investigate the dynamic properties and safety of PSC-I railway bridge having length 25 m in different crossbeam. Numerical analysis is performed time series analysis by mode superposition using calculated natural vibration frequency and mode after carry out a free vibration analysis and extract modal parameter to higher modes. Consequently, the result met baseline satisfactorily in every case include virtical displacement, acceleration and distort. The result of this study shows there is no problem with safety of dynamic that consider maximum space of crossbeam, whereupon we expected as a reference for design railway bridges. 철도교량은 일정한 축 간격을 가진 열차가 주행함으로써 구조물과의 상호작용으로 공진의 가능성이 존재하게 된다. 또한 열차가 고속으로 주행함에 따라 고유진동수를 포함한 동특성, 처짐, 가속도 등의 동적물리량에 대한 검증이 필연적이다. 최근 PSC-I 단면 합성형 교량은 경제성 등의 장점으로 20~30 m 지간을 갖는 교량에 국내외에서 활발히채택되어 사용되고 있다. 본 논문에서는 경간장 25 m PSC-I 철도교를 대상으로 가로보의 개수를 달리하여 동특성을분석하고 KTX열차와 화물열차 주행시의 동적안정성을 수치해석적으로 검토하여 국내 및 국외의 동적 안정성 기준과부합여부를 검토하였다. 그 결과, 수직처짐, 가속도, 면틀림 등의 모든 경우에서 기준치를 만족하는 것으로 분석되었다, 본 연구 결과는 가로보 최대 설치간격을 고려하여도 동적안정성에 문제가 없는 것으로 분석되며 이를 근거로 보다 경제적인 가로보 설계가 가능할 것이다.

Early Left Ventricular Dysfunction in Children after Hematopoietic Stem Cell Transplantation for Acute Leukemia: A Case Control Study Using Speckle Tracking Echocardiography

윤지홍,김혜진,이은정,문세나,이재영,이재욱,정낙균,조빈,김학기 대한심장학회 2015 Korean Circulation Journal Vol.45 No.1

Background and Objectives: Cardiovascular complications are the leading cause of morbidity and mortality in childhood cancer survivors. Hematopoietic stem cell transplantation (HSCT) is a curable therapy for pediatric cancer. However, changes in cardiac function in childrenafter HSCT are not well known. We assessed left ventricular (LV) function in children after HSCT using speckle tracking echocardiography(STE). Subjects and Methods: Forty consecutive patients with median age of 11.9 years (range, 1.5–16 years) who received HSCT for acuteleukemia and had comprehensive echocardiography before and after (median 9.2 month) HSCT were included in this study. The LV functionparameters including conventional tissue Doppler imaging (TDI) and STE data were collected from pre- and post-HSCT echocardiography. These data were compared to those of 39 age-matched normal controls. Results: Compared to normal controls, post HSCT patients had similar (p=0.06) LV ejection fraction. However, the following three LV functionparameters were significantly decreased in post HSCT patients: rate-corrected velocity of circumferential fiber shortening (p=0.04),mitral inflow E velocity (p<0.001), and mitral septal annular E’ velocity (p=0.03). The following four STE parameters were also significantlydecreased in post HSCT patients: LV global circumferential systolic strain (p<0.01), strain rate (SR, p=0.01), circumferential diastolic SR(p<0.01), and longitudinal diastolic SR (p<0.001). There was no significant change in TDI or STE parameters after HSCT compared to pre-HSCT. Patients with anthracycline cumulative dose >400 mg/m2 showed significantly (p<0.05) lower circumferential systolic strain andcircumferential diastolic SR. Conclusion: Subclinical cardiac dysfunction is evident in children after HSCT. It might be associated with pre-HSCT anthracycline exposurewith little effect of conditioning regimens. Serial monitoring of cardiac function is mandatory for all children following HSCT.

Helicobacter pylori 감염과 연관된 소아 Menetrier 병 1예

윤지홍,안문배,맹이소,김상용 대한상부위장관ㆍ헬리코박터학회 2014 Korean Journal of Helicobacter Upper Gastrointesti Vol.14 No.4

Ménétrier’s disease in childhood is a rare form of gastropathy characterized by hypoalbuminemia, endoscopic and/or radiologic findings of hypertrophic gastric folds, and histologic findings of foveolar hyperplasia in the stomach. It tends to have a self-limited course compared to the chronic and complicated course in adult Ménétrier’s disease. A 7-year-old boy was referred to Incheon St. Mary’s Hospital for facial edema. Physical examination on admission showed periorbital swelling, pitting edema in both legs, and epigastric tenderness. Laboratory tests on admission indicated hypoproteinemia (3.0 g/dL) with hypoalbuminemia (2.1 g/dL) and hypogammaglobulinemia. Urinalysis showed no abnormalities. The test results for anti-cytomegalovirus immunoglobulin M and cytomegalovirus PCR were negative. Stool Helicobacter pylori antigen was positive and fecal α1-antitrypsin clearance was 40.1 mL/day, consistent with protein-losing gastroenteropathy. Gastroduodenoscopy showed hypertrophic edematous gastric folds, erythema, and superficial erosion in the body of the stomach. The duodenum was normal. Histologic findings showed foveolar hyperplasia. His symptoms improved with conservative treatment including proton pump inhibitor from day 9 of hospitalization and resolved completely. Here we reported a case of pediatric protein-losing hypertrophic gastropathy associated with Helicobacter pylori infection.

Jack London의 자연으로의 회귀

윤지홍 동아대학교 인문과학대학 영어영문학과 1993 동아영어영문학 Vol.9 No.-

빛의 종분산 실험을 수행한 학생들의 반응 조사

윤지홍,원창국,최호명 한국물리학회 2006 새물리 Vol.53 No.6

We have analyzed the responses of students who observed the depths of colors (i.e. longitudinal dispersion of light) due to chromatic aberration. Among the diverse responses from the students, 76 \% of them answered as follows: (1) The longitudinal dispersion was more pronounced for a black background than for backgrounds of any other colors. (2) The most projected colors in the black background were red, yellow, and blue in that order. This may indicate that the longitudinal dispersion of light is closely related with the wavelength. In addition, after examining the change of attitudes of the students who set up and performed the experiment by themselves throughout the entire research period, we were found that they improved aggressiveness, confidence and patience quite remarkably. This self-directive study is shown to be a very effective way to form a scientific attitude. 천연색 그림을 확대경으로 관찰하는 과정에서 색수차에 의하여 색깔별로상의 깊이가 다르게 나타나는 것(종분산)을 볼 수 있다. 이 현상을관찰하는 과정에 참가한 학생들의 반응은 여러 가지로 나타났으나 약 76 \%에 해당하는 학생들이 유사한 답을 하였다. 여러 가지의 색을바탕색으로 사용하여 관찰한 결과 검은색을 바탕색으로 두고 관찰하는경우 가장 차이가 잘 관찰되었으며 빨강색의 경우가 가장 높이 떠올라보였다고 하였으며 빨강 노랑 파랑의 순으로 갈수록 깊이가 깊어짐을관찰하였다고 하였다. 렌즈에 필터를 덮은 채로 실험을 하게 하였더니 그차이가 줄어들고 약간의 변화가 있음을 확인 하였다. 이 실험의 과정에서실험을 계획하고 수행하는 전 과정에 주도적으로 참여시킨 학생들을대상으로 수행전과 수행 후의 과학적 태도의 변화를 조사한 결과 적극성, 자진성, 계속성 및 끈기의 영역에서 두드러진 향상을 보였다.

Single Focus HCP 장치의 X-ray 특성

윤지홍,손연규,임병욱 한국물리학회 2005 새물리 Vol.51 No.5

The argon-gas plasma-focus formation and soft X-ray characteristics of an improved single focus HCP (hypocycloidal pinch) with an IPS (inverse pinch switch) were investigated. The soft X-ray emission was detected by using an XR-100 X-ray detector and the voltage spike curve. For Ar gas pressures of 80 $\sim$ 130 mTorr and HCP electrode voltages of about 9 $\sim$ 17 kV the plasma focus formation curve and a photograph of the plasma focus were observed. The X-ray measurements showed thar the wavelengths of the soft X-rays were distributed in the region of 0.18 $\sim$ 7.4 keV (0.16 $\sim$ 6.7 nm). HCP (hypocycloidal pinch) 장치의 아랫부분을 전극으로 사용하여 한개의 초점이 맺히도록 수정하였다. 방전 스위치는 IPS (inverse pinch switch)를 장착하여 설험 과정에서 스위치의 파괴를 방지하였다. 아르곤가스의 압력과 방전전압 변화에 따른 plasma focus 형성을 관찰하였다. 이 장치로부터 발생하는 X-ray의 발생 특성을 조사하였다. 아르곤 가스압력 80 $\sim$ 130 mtorr, 전압 9 $\sim$ 17 kV의 영역에서 plasma focus가 잘 형성되었다. X-ray detector를 이용하여 측정된 스펙트럼을 분석한 결과 파장 0.18 $\sim$ 7.4 keV(0.16 $\sim$ 6.7nm) 영역의 X-ray가 발생하였다.

효과적인 실험계획과 물리교육의 발전 : 독일 Gymmasium의 물리교육

윤지홍 濟州大學校 師範大學 科學敎育硏究所 1987 科學敎育 Vol.4 No.-

아르곤 기체를 주입한 HCP 장치에서 발생하는 soft X - ray의 특성

윤지홍,임병욱 한국진공학회 2005 한국진공학회 학술발표회초록집 Vol.- No.-

색소혼합에 따른 Ti:SAPPHIRE의 형광의 개선

윤지홍,양호근 안동대학교 기초과학연구소 2000 基礎科學 硏究論文集 Vol.11 No.1

The hypocyclodial pinch (HCP) equipment has been fabricated and used to improve the efficiency of Ti:Sapphire laser. The experimental result shows that the BBQ(5 ×10^(-6) mol/l) and BBO(1 ×10^(-4) mol/l) dyes turn out to be suitable converter dyes of laser dyes, which are the LD-490(4 ×10^(-4) mol/l) and C503(0.8 ×10^(-6) mol/l) dyes. The emission characteristics of the argon gas in the HCP show that the optimum output intensity yields at 20 torr of argon pressure and 8㎸ of input voltage. When the fluorescent energy converter dye has been used, the efficiency of Ti:Sapphire laser has been increased. The maximum enhancement of laser efficiency has been obtained, (i) when adding the BBO(1 ×10^(4) mol/l) dye into the LD-490(4 ×10^(-4) mol/l) dye with the same ratio, and (ii) when adding the BBQ(5 ×10^(-6) mol/l) dye into the C503(0.8 ×10^(-6) mol/l) dye with the same ratio.

MC / DCT 복합 부호화 방식에서의 루프 필터링에 의한 성능 개선 효과 ( The Effectiveness of Spatial Filtering in MC / DCT Hybrid Coding Loop )

윤지홍,김재균 대한전자공학회 1987 대한전자공학회 학술대회 Vol.1987 No.1