A Study on the Map Building and Traveling Algorithm for Mobile Robots with Ultrasonic Sensors

In order for a mobile robot to move in unknown or uncertain environment, it must have an environmental information. In collecting environmental information, the mobile robot can use various sensors. In case of using ultrasonic sensors to collect an environmental information, it is able to comprise a low-cost environmental recognition system compared with using other sensors such as vision and laser range-finder. This paper proposes a map building algorithm which can collect environmental information using ultrasonic sensors. And also this paper suggests a traveling algorithm using environmental information which leads to the map building algorithm and the A* algorithm. In order to accomplish the proposed traveling algorithm, this paper additionally discusses a position revision algorithm and a path amendment algorithm. For the purpose of verifying the proposed algorithms, several simulations and experiments are executed based on a UI-based simulation program and a mobile robot physically designed in this paper. The conclusion is that the proposed algorithm is very effective and is applicable to mobile robots especially requiring a low-cost environmental information.제 1 장 서론 = 1 1.1 기존 연구 현황 = 1 1.2 본 논문의 목적 = 3 제 2 장 이동로봇의 구성 = 5 2.1 이동로봇의 구조 = 5 2.1.1 기구부 = 5 2.1.2 센서부 = 8 2.1.3 구동부 = 13 2.1.4 제어부 = 14 2.2 이동로봇의 기구학 = 16 제 3 장 맵 빌딩 알고리즘 = 18 3.1 맵 빌딩의 필요성과 방법 = 18 3.1.1 맵 빌딩의 필요성 = 18 3.1.2 기존의 맵 빌딩 방법 = 19 3.1.3 개선한 맵 빌딩 방법 = 20 3.2 맵 빌딩 수행 = 20 3.2.1 맵 빌딩 수행 환경 = 20 3.2.2 맵 빌딩 수행 과정 = 22 3.3 위치 보정 알고리즘 = 27 3.3.1 위치 보정 알고리즘의 필요성 = 27 3.3.2 위치 보정 알고리즘 = 28 3.4 호스트 UI 프로그램 = 31 3.4.1 호스트 UI 프로그램의 필요성 = 31 3.4.2 호스트 UI 프로그램 = 33 제 4 장 주행 알고리즘 = 34 4.1 A* 알고리즘과 최적화 방법 = 35 4.1.1 A* 알고리즘 = 35 4.1.2 A* 알고리즘의 최적화 방법 = 40 4.2 경로 수정 알고리즘 = 41 4.2.1 경로 수정 알고리즘의 필요성 = 41 4.2.2 경로 수정 알고리즘 = 42 4.3 주행 알고리즘 = 45 제 5 장 실험 및 고찰 = 48 5.1 시뮬레이션 = 48 5.1.1 시뮬레이션의 구성 = 48 5.1.2 시뮬레이션 결과 = 48 5.2 실제 주행 = 60 5.2.1 실제 주행 환경의 구성 = 60 5.2.2 실제 주행 결과 = 61 제 6 장 결론 = 67 참고문헌 = 6

Differences in Abdominal Body Composition According to Glycemic Status: An Inverse Probability Treatment Weighting Analysis

Background: Several studies have reported that abdominal fat and muscle changes occur in diabetic patients. However, there are few studies about such changes among prediabetic patients. In this study, we evaluated the differences in abdominal fat and muscles based on abdominopelvic computed tomography in prediabetic and diabetic subjects compared to normal subjects. Methods: We performed a cross-sectional study using health examination data from March 2014 to June 2019 at Ulsan University Hospital and classified subjects into normal, prediabetic, and diabetic groups. We analyzed the body mass index corrected area of intra-abdominal components among the three groups using inverse probability treatment weighting (IPTW) analysis. Results: Overall, 8,030 subjects were enrolled; 5,137 (64.0%), 2,364 (29.4%), and 529 (6.6%) subjects were included in the normal, prediabetic, and diabetic groups, respectively. After IPTW adjustment of baseline characteristics, there were significant differences in log visceral adipose tissue index (VATI; 1.22 +/- 0.64 cm(2)/[kg/m(2)] vs. 1.30 +/- 0.63 cm(2)/[kg/m(2)] vs. 1.47 +/- 0.64 cm(2)/[kg/m(2)], P<0.001) and low-attenuation muscle index (LAMI; 1.02 +/- 0.36 cm(2)/[kg/m(2)] vs. 1.03 +/- 0.36 cm(2)/[kg/m(2)] vs. 1.09 +/- 0.36 cm(2)/[kg/m(2)], P<0.001) among the normal, prediabetic, and diabetic groups. Prediabetic subjects had higher log VATI (estimated coefficient=0.082, P<0.001), and diabetic subjects had higher log VATI (estimated coefficient=0.248, P<0.001) and LAMI (estimated coefficient=0.078, P<0.001) compared to normal subjects. Conclusion: Considering that VATI and LAMI represented visceral fat and lipid-rich skeletal muscle volumes, respectively, visceral obesity was identified in both prediabetic and diabetic subjects compared to normal subjects in this study. However, intra-muscular fat infiltration was observed in diabetic subjects only

Ticagrelor versus prasugrel in patients with acute myocardial infarction

Background: Ticagrelor and prasugrel are the mainstay of antithrombotic therapy for patients with acute myocardial infarction (MI). However, direct comparative data on clinical outcomes of potent P2Y12 inhibitors are limited, especially in East Asian populations. We aimed to evaluate the effect of ticagrelor versus prasugrel on clinical outcomes in patients with acute MI. Methods: From the Korean nationwide National Health Insurance database, 10,797 patients with acute MI who received either ticagrelor or prasugrel in combination with aspirin after percutaneous coronary intervention (PCI) were enrolled. The primary outcome was net clinical benefit, defined as a composite of death, MI, stroke, or major bleeding. Secondary outcomes included the individual components of the primary outcome as effectiveness and safety measures. Results: Among 10,797 patients, 9591 (88.8%) received ticagrelor and 1206 (11.2%) received prasugrel. During a median follow-up of 1.8 years, the primary outcome occurred in 1051 (16.6%) and 131 (14.4%) patients in the ticagrelor and prasugrel groups, respectively. In the propensity score matched cohort (n = 5979), the risk for the primary outcome was similar between the two groups (hazard ratio [HR] 0.949 for prasugrel; 95% confidence interval [CI]: 0.780-1.154). The risks for the composite of death, MI, or stroke (HR 0.938; 95% CI: 0.752-1.169) and major bleeding (HR 1.022; 95% CI: 0.709-1.472) were also comparable. Conclusions: In patients with acute MI undergoing PCI, ticagrelor and prasugrel appeared to have similar net clinical benefits. The risks for death, MI, or stroke and major bleeding were not significantly different between the two groups

Angiotensin-Converting Enzyme Inhibitor-based Versus Angiotensin Receptor Blocker-based Optimal Medical Therapy After Percutaneous Coronary Intervention: A Nationwide Cohort Study

Optimal medical therapy (OMT) plays a crucial role in the secondary prevention of established coronary artery disease. The renin-angiotensin system (RAS) is an important target of OMT. However, there is limited evidence on whether there is any difference in the combined effect of OMT according to the classes of RAS blockade [angiotensin-converting enzyme inhibitor (ACEI) vs. angiotensin receptor blocker (ARB)]. Based on the nationwide National Health Insurance database in South Korea, 39,096 patients who received OMT after percutaneous coronary intervention between July 2013 and June 2017 were enrolled. Patients were stratified into either acute myocardial infarction (AMI) or angina cohort and analyzed according to the class of RAS blockade included in OMT at discharge (ACEI vs. ARB). The primary end point was all-cause mortality. The study population had a median follow-up of 2.3 years (interquartile range, 1.3-3.3 years). In the propensity score-matched AMI cohort (8219 pairs), the risk for all-cause mortality was significantly lower in patients with ACEI-based OMT than in those with ARB-based OMT (hazard ratio 0.83 of ACEI, 95% confidence interval 0.73-0.94, P = 0.003). However, in the propensity score-matched angina cohort (6693 pairs), the mortality risk was comparable, regardless of the class of RAS blockade (hazard ratio 1.13, 95 confidence interval 0.99-1.29, P = 0.08). In conclusion, in this nationwide cohort study involving patients receiving OMT after percutaneous coronary intervention, ACEI-based OMT was associated with a significantly lower risk of all-cause mortality in patients with AMI in comparison with ARB, but not in those with angina