• International Journal of Vascular Biomedical Engineering
• /
• 제1권2호
• /
• pp.20-29
• /
• 2003

A new treatment for coronary artery occlusive disease is being developed in which a shunt or conduit is placed directly connecting the left ventricle with the diseased artery at a point distal to the obstruction. To aid in assessing and optimizing its benefit, a computational model of the cardiovascular system was developed and used to explore various design conditions. Simulation results indicate that in complete LAD occlusion, flow can be returned to approximately 65% of normal if the conduit resistance is equal for forward and reverse flow, increasing to 80% in the limit in which backflow resistance is infinite. Increases in flow rate produced by asymmetric flow resistance are considerably enhanced in the case of a partial LAD obstruction since the primary effect of resistance asymmetry is to prevent leakage back into the ventricle("steal") during diastole. Increased arterial compliance has little effect on net flow with a symmetric shunt, but leads to considerable augmentation when the resistance is asymmetric. These results suggest that an LV-LAD conduit will be beneficial when stenosis resistance(Rst) > 27 PRU if resistance is symmetric.

• Radiation Oncology Journal
• /
• 제33권3호
• /
• pp.242-249
• /
• 2015

Purpose: The purpose of this study is to compare the dosimetry of electron beam (EB) plans and three-dimensional helical tomotherapy (3DHT) plans for the patients with left-sided breast cancer, who underwent breast conserving surgery. Materials and Methods: We selected total of 15 patients based on the location of tumor, as following subsite: subareolar, upper outer, upper inner, lower lateral, and lower medial quadrants. The clinical target volume (CTV) was defined as the area of architectural distortion surrounded by surgical clip plus 1 cm margin. The conformity index (CI), homogeneity index (HI), quality of coverage (QC) and dose-volume parameters for the CTV, and organ at risk (OAR) were calculated. The following treatment techniques were assessed: single conformal EB plans; 3DHT plans with directional block of left anterior descending artery (LAD); and 3DHT plans with complete block of LAD. Results: 3DHT plans, regardless of type of LAD block, showed significantly better CI, HI, and QC for the CTVs, compared with the EB plans. However, 3DHT plans showed increase in the $V_{1Gy}$ at skin, left lung, and left breast. In terms of LAD, 3DHT plans with complete block of LAD showed extremely low dose, while dose increase in other OARs were observed, when compared with other plans. EB plans showed the worst conformity at upper outer quadrants of tumor bed site. Conclusion: 3DHT plans offer more favorable dose distributions to LAD, as well as improved target coverage in comparison with EB plans.

• 한국농림기상학회지
• /
• 제8권3호
• /
• pp.183-189
• /
• 2006

건물 생산 및 수량 관련 특성들을 비교 검토하고자, 시대별로 보급 면적이 넓었던 Japonica 6품종과 통일형 3품종에 대하여 건물 생산 특성인 광소멸계수(K), 광이용효율(RUE), 누적엽면적지수(LAD) 등과 수량 및 수량구성요소를 조사하였고, 각 특성들을 비교 검토하였다. 벼 군락의 K는 70년대 이전에 보급된 품종은 0.5이상으로 높은 값을 보였으나, 그 이후에 나온 Japonica 품종과 통일형 품종은 0.5보다 낮은 값을 보였다. 출수전 RUE는 japonica 품종 중에서는 팔달벼가 가장 낮았고, 조동지와 낙동벼가 높았으며, 통일형 품종 중에서는 밀양23호가 유의하게 낮았으나 품종육성연대에 따른 일정한 변화경향은 없었다. 한편 등숙기 RUE는 품종간에 유의적인 차이가 없었다. LAD는 품종간에 유의적인 차이가 있었는데, 최근에 육성된 품종일수록 LAD가 큰 경향이었다. 출수기까지의 LAD는 출수기 건물중과 유의한 상관이 인정되지 않았으나, 출수 후 LAD 및 전 생육기간의 LAD는 등숙기 건물생산량 및 수확기 건물중과 각각 유의한 정의 상관이 있었다. 출수기 및 수확기 건물중은 품종간에 유의적인 차이는 없었으나 통일계 품종의 경우는 최근에 육성된 품종일수록 높은 경향이었다. 수량은 자포니카 품종의 경우 1900년대 이전 품종인 조동지만이 유의하게 수량이 낮았으며, 그 이후에 육성된 japonica 품종 간에는 수량의 차이는 없었다. 통일형 품종은 최근에 육성된 품종일수록 수량이 높은 경향이었다, 수량은 단위면적당 영화수와 유의한 정의 상관관계가 있었는데 통일계 품종은 최근에 육성된 품종일수록 단위면적당 영화수가 많았다. 이상의 결과를 요약하면 japonica 품종의 경우 육성보급 연대에 따른 건물생산 특성인 K, RUE 및 LAD의 일정한 변화 경향이 없었으나, 통일계 품종의 경우는 최근에 육성된 품종일수록 수량이 증가하였는데, 이는 영화수 증대에 따른 sink size 증대와 더불어 LAD증대에 따른 건물생산성 증대에 기인하는 것이었다.

• 한국디자인학회:학술대회논문집
• /
• 한국디자인학회 2005년도 춘계 학술발표대회 논문집
• /
• pp.280-281
• /
• 2005

• Korean Circulation Journal
• /
• 제48권11호
• /
• pp.1002-1011
• /
• 2018

Background and Objectives: The prognostic impact of left axis deviation (LAD) on clinical outcomes in acute heart failure syndrome (AHFS) with left bundle branch block (LBBB) is unknown. The aim of this study was to determine the prognostic significance of axis deviation in acute heart failure patients with LBBB. Methods: Between March 2011 and February 2014, 292 consecutive AHFS patients with LBBB were recruited from 10 tertiary university hospitals. They were divided into groups with no LAD (n=189) or with LAD (n=103) groups according to QRS axis <-30 degree. The primary outcome was all-cause mortality. Results: The median follow-up duration was 24 months. On multivariate analysis, the rate of all-cause death did not significantly differ between the normal axis and LAD groups (39.7% vs. 46.6%, adjusted hazard ratio, 1.01; 95% confidence interval, 0.66, 1.53; p=0.97). However, on the multiple linear regression analysis to evaluate the predictors of the left ventricular ejection fraction (LVEF), presence of LAD significantly predicted a worse LVEF (adjusted beta, -3.25; 95% confidence interval, -5.82, -0.67; p=0.01). Right ventricle (RV) dilatation was defined as at least 2 of 3 electrocardiographic criteria (late R in lead aVR, low voltages in limb leads, and R/S ratio <1 in lead V5) and was more frequent in the LAD group than in the normal axis group (p<0.001). Conclusions: Among the AHFS with LBBB patients, LAD did not predict mortality, but it could be used as a significant predictor of worse LVEF and RV dilatation (Trial registry at KorAHF registry, ClinicalTrial.gov, NCT01389843).

• Journal of Yeungnam Medical Science
• /
• 제31권1호
• /
• pp.13-16
• /
• 2014

Congenital abnormalities of the coronary arteries are found in 0.6% to 1.3% of patients in coronary angiography. Dual left anterior descending coronary artery (LAD) is a rare coronary anomaly and is incidentally detected during coronary angiography. We report a case of a 65-year-old female with a rare coronary anomaly who was diagnosed with dual LAD via coronary computed tomography and coronary angiography. The imaging studies revealed dual LAD originating from the left main stem and right coronary sinus. These angiographic findings were considered to be consistent with the type IV variety of dual LAD by Spindola-Franco classification. Recognition of dual LAD is important to prevent errors of interpretation of the coronary angiogram and for optimal surgery.

• 대한영상의학회지
• /
• 제85권2호
• /
• pp.428-433
• /
• 2024

이중 좌전하행 관상 동맥은 일반 인구에서 약 1%의 유병률을 보이는 드문 선천성 기형이다. 지금까지 이중 좌전하행 관상동맥 기형은 10가지 유형으로 보고되었다. 그중 제4형 이중 좌전하행 관상동맥은 가장 희귀한 유형 중 하나이다. 이중 좌전하행 관상동맥에 대한 지식과 인식은 정확한 진단과 관상동맥 우회 수술 및 경피적 관상동맥 중재술을 계획하는 데 중요하다. 저자들은 수개월 동안 소화불량과 발한을 주소로 내원하였고 짧은 좌전하행 관상동맥의 주요 대각분지에 약 50%-70% 협착이 있었던, 제4형 이중 좌전하행 관상동맥 기형을 가진 59세 남성의 증례를 보고하고자 한다.

• 분석과학
• /
• 제5권2호
• /
• pp.217-222
• /
• 1992

수은침투법을 이용하여 AIN의 이장성형체와 건조가압성형체의 기공구조 해석을 시도하였다. 좁은 기공크기 분포와 높은 충진밀도를 가진 이장성형체에서 소결도가 높고 2차상의 분포가 균일하였다. 수은침투법에 의한 기공크기 분포 해석은 잉크병 현상이 없을 때만 유효하지만 정량미시 분석과의 비교결과 기공률의 측정은 개기공 상태이면 유효함을 보였다.

• Communications for Statistical Applications and Methods
• /
• 제30권2호
• /
• pp.135-147
• /
• 2023

Skipped median is more robust than median when outliers are not symmetrically distributed. In this work, we propose a novel algorithm to estimate the skipped median. The idea of skipped median and the new algorithm are extended to regression problem, which is called least clipped absolute deviation (LCAD). Since our proposed algorithm for nonconvex LCAD optimization makes use of convex least absolute deviation (LAD) procedure as a subroutine, regularizations developed for LAD can be directly applied, without modification, to LCAD as well. Numerical studies demonstrate that skipped median and LCAD are useful and outperform their counterparts, median and LAD, when outliers intervene asymmetrically. Some extensions of the idea for skipped median and LCAD are discussed.

• 한국대기환경학회지
• /
• 제33권3호
• /
• pp.233-240
• /
• 2017

To distinguish between high particulate matter (HPM) and light Asian dust (LAD) events, aerosol optical properties from GOCI were investigated in Seoul from 2014 to 2016. The poor air quality case caused by fine atmospheric particulate matter (i.e., 80<$PM_{10}$<$400{\mu}g/m^3$) is clearly separated from the case of heavy Asian dust that generally shows the $PM_{10}$ concentration more than $400{\mu}g/m^3$. In this study, we have found eight cases for the poor air quality and divided them into the two events(i.e., HPM and LAD). In case of aerosol optical depth (AOD), there was no big difference between two events. However, Angstrom exponent (AE) for HPM events was greater than 1, while that for LAD events less than 1. As a result of comparing aerosol type, non-absorbing fine mode aerosols were dominant for HPM events, but coarse and absorbing coarse mode aerosols for LAD events. Therefore, AE and aerosol type from GOCI can be used to distinguish between two events effectively.