An Integrative Critical Incident Approach to Quality Management in the Smartphone Market: Product, Service, and Content

학위논문 (석사)-- 서울대학교 대학원 : 경영학과, 2012. 8. 오정석.The explosive growth of the smartphone market and furious competition among global IT (Information Technology) leaders necessitate a better understanding of consumers quality perceptions of smartphones, their related services, and contents. In this study, a critical incident approach to quality perception and management is utilized to investigate how the quality of a smartphone device, product-related services, telecommunications services, and application contents influences owner intentions of future purchases. Specifically, critical incidents that smartphone owners may confront are hypothesized to engage in forming their satisfaction level or quality perceptions of smartphones, affecting their likelihood of future purchases with regard to the three major smartphone supply chain parties: the mobile device manufacturer, the telecommunications carrier and the application content provider. The proposed model was empirically examined by regression analyses of 795 smartphone users responses. The results can be summarized as follows: Smartphone owners are affected by the critical incidents associated with their smartphones which they experienced during the ownership cyclethe owners overall quality perceptions of smartphones are influenced by the critical incidents related to phone device, product-related services, telecommunication services, and application contentsthe specific critical incident categories that significantly have an effect on each smartphone supply chain party differ with each other. Additionally, quality management through monitoring and managing critical incidents during the ownership period is verified to applicable in smartphone market in order to enhance quality perceptions of customers, leading to business prosperity as well as better quality design of smartphone products and services. Keywords: Critical IncidentQuality ManagementIntegrative ApproachSupply Chain ManagementSmartphone1. Introduction……………………………….………………..………………...………5 2. Smartphone market…………………………………………….................................9 3. Literature review……………………………………………………………...….....12 4. A framework for evaluating owner perceptions of smartphone quality................14 4.1. Data collection ……………………………………………………..…...……...20 4.2. Independent and dependent variables………………………………………..23 5. Data analysis………………………………………………………………...………25 5.1. The impact of critical incidents on the smartphones overall quality………26 5.2. The impact of critical incidents on the owners future intentions…………..29 5.3. Implication….……………………………………………………..……………38 6. Conclusion..…………………………………………………………………..…..….42 References……………………………………………………………………………...45 국문 초록…………………………………………………………………….………….51Maste

The cost-effectiveness of bisphosphonates in the treatment of postmenopausal osteoporosis of women in Korea

병원경영학과/석사연구 목적: 이전 골절 경험이 없는 폐경 후 골다공증 환자(T score≤ -2.5SD)에서 골다공증 치료의 결과로 나타난 골절 예방 효과를 통하여 골다공증 치료제의 투여 시작 연령별로 골다공증 치료제의 비용-효과성을 측정한다. 연구 방법: 이 연구에서는 골다공증 치료제의 비용-효과성을 측정하기 위하여 마르코프-코호트 모형(Markov-Cohort Model)을 사용하였다. 국내에서 가장 빈번히 골다공증 치료제로 사용되고 있는 비스포스포네이트 중 알렌드로네이트 또는 리제드로네이트를 치료제로 투여한 군과 그렇지 않은 군을 비교하였고, 분석관점은 보험자 관점으로 하였다. 분석기간은 1000명의 골다공증 환자들이 약물을 투여를 시작한 시점부터 나이가 100세가 되거나 사망할 때까지로 설정하였다. 70세를 기본 분석으로 하여 나이별로(60세, 65세, 70세, 75세, 80세, 85세) 6개의 코호트를 구성하였다. 모델에 포함된 골절은 고관절 골절, 척추 골절, 손목 골절 3가지이다. 문헌 검토를 통하여 골다공증 환자에서의 골절의 발생율, 골절 치료비용(입원, 외래), 약제비용, 골절 발생 시 감소된 효용, 골다공증 치료제의 효과 등의 국내 자료를 수집하였다. 골다공증 치료제 투여기간은 5년, 약제의 잔류효과(residual effect)는 5년으로 가정하였다. 또한 약물 순응도를 고려하였다. 골다공증 치료제의 비용-효과성에 대한 결과는 골절 예방 건수, 연장된 질 보정 수정(quality-adjusted life-years, QALYs)를 사용하였다. 비용과 결과는 연간 5%할인율을 적용하였다. 연구 결과: 기본 분석에서 (이전 골절 경험이 없으며, 70세에 골다공증 치료를 시작한 여성 환자) 골다공증 치료제의 비용-효과성을 분석한 결과, QALY에 대한 점증적 비용-효과비(incremental cost-effectiveness ratio, ICER)는 35,292,823원/QALY이었다. 80세에 약물 치료를 시작하는 경우가 가장 비용 효과적이었고(ICER=23,885,022원/QALY), 60세에 치료를 시작하는 경우(152,769,476원/QALY) 가장 비용-효과성이 낮았다. 또한 기본 분석(약물 투여시점: 70세)에서 골절 예방에 대한 점증적 비용-효과비(ICER)는 11,769,688원/one averted Fx이었다. 골절 예방에 대한 ICER는 75세에 약물투여를 시작한 경우 가장 비용-효과적이었고(10,732,892원/one averted Fx), 60세에 약물 투여를 시작한 경우 가장 비용-효과성이 낮았다(47,318,663원/one averted Fx). 대체적으로 골다공증 치료 시작 연령이 높아질수록 비용-효과적인 경향을 보였다. 기본분석을 기준으로 한 민감도 분석에서는 본 모형에서는 골다공증 치료제의 효과와 약제 투여기간에 따라 결과가 민감하게 변화하는 것을 확인할 수 있었다.결 론: 마르코프-코호트 모형을 통해 골다공증 치료제의 비용-효과성을 분석한 결과, 치료를 시작한 시점에 따라 비용-효과성이 다르게 나타났다. 비용-효과성 수용 임계값이 3,000만원/QALY인 경우, 75세 이상에서 골다공증 치료를 시작한 군에서 비용-효과적이며, 비용-효과성 수용 임계값이 4,000만원/QALY 이상인 경우 70세 이상의 연령에서 비용효과적인 것으로 나타났다.restrictio

성능을 보장할 수 있는 강인한 물체 추적 알고리즘과 로봇 네비게이션

학위논문 (박사)-- 서울대학교 대학원 : 공과대학 전기·컴퓨터공학부, 2018. 2. 오성회.Research on mobile robot includes a wide range of research elds such as path planning, target tracking, and navigation. Since these elds deal with the fundamental and necessary technologies for mobile robots, they have been actively investigated for a long period of time. Nonetheless, such algorithms have not been sufficiently developed to deploy the robot in the real environments, since the real world is uncontrolled, complicated and variable. The complex environments generate various uncertainties which can result in different consequences from the intent of the algorithm. Hence, uncertainties can lead to failure of navigation algorithms which do not take uncertainties into account. The most representative example of uncertainties is the uncertainty in the dynamic model of the robot. In general, the dynamic model of the robot is given, when we solve the navigation problem such as a path planning problem. Unfortunately, in the real world, there can be uncertainties caused by disturbances such as friction or air flow. Since the uncertainties can make the planned trajectory infeasible, it is necessary to develop a control algorithm with a high probability of success considering uncertainties. Another example is the uncertainties in motion of objects near the robot. When the robot tracks an object or avoids the obstacles, it is important to predict their motion. However, even if the prediction algorithm is quite accurate, it cannot be deterministic and uncertainties exists in the predicted value. Therefore, we need to develop a controller that is robust against uncertainties. In this dissertation, we propose robust target tracking algorithms and path planning algorithms under uncertainties. The target tracking problem aims to locate the target within the nite and fan-shaped sensing region of the robot when the motion of the target is predictable as a Gaussian distribution. We formulate a non-convex optimization problem such that the solution is the control which maximizes the success probability of tracking and minimizes the moving distance of the robot. The optimization can be solved in real time by dividing the problem into several convex problems and solving them analytically. The proposed method is successfully applied to 2D and 3D mobile robots and shows the robustness against uncertainties by guaranteeing the success probability. For more general applications, we extend the tracking algorithm to consider identity uncertainties when multiple objects are detected in the sensing region. We predict the motion of the target as a Gaussian mixture model using a multiple-hypothesis prediction algorithm which combines the motion model and the appearance model of the target. Then we propose the control which maximizes the success probability of tracking. If the success probability is guaranteed as a suciently high value, the control minimizes the moving distance of the robot. We also focus on a more complicated problem which is path planning to generate a long-period trajectory while target tracking generates a one-step control. The proposed path planning algorithm searches a trajectory which satises mission requirements specied in linear temporal logic (LTL). Since the robot does not follow the exact planned trajectory with a high probability due to uncertainties in its dynamic model, it can fail to accomplish the mission or collide with obstacles. For safety and robustness under uncertainties, we propose a multi-layered sampling based path planning, where a high-level planner generates a discrete trajectory to guide a low-level planner and the low-level planner generates a safe and robust trajectory to accomplish the mission. Our algorithm has the advantage of limiting the probability of collision below a certain threshold and increasing the probability of success. The method is extended to path planning algorithms under time-varying uncertainties. The proposed methods in this dissertation represent the uncertainty a1 Introduction 1 1.1 Main Challenges 2 1.2 Organization of the Dissertation 3 2 Related Work 5 2.1 Target Tracking 5 2.2 Chance constraints for path planning 8 2.3 Linear Temporal Logic 9 2.3.1 Path Planning with Linear Temporal Logic 10 3 Robust Target Tracking Using Sensors with Bounded Fan-Shaped Sensing Regions 13 3.1 Problem Formulation 17 3.2 Mobile Robot's Dynamic Model 20 3.3 Bounded Fan-Shaped Sensing Region 21 3.4 Motion Strategies: Analytical Solutions 25 3.4.1 Solutions to 1 26 3.4.2 Solutions to 2 28 3.4.3 Selection of N 28 3.5 Robust Target Tracking in 3D 31 3.5.1 Dynamic model 31 3.5.2 Visibility Conditions 32 3.5.3 Motion Strategies 34 3.6 Simulations 36 3.6.1 Single-Step Target Tracking in 2D 36 3.6.2 Multi-Step Target Tracking in 2D 42 3.6.3 Target Tracking Using Real Human Trajectories 44 3.6.4 Multi-Step Target Tracking in 3D 48 3.7 Experiments 50 3.8 Summary 52 4 Robust Target Tracking Under Identity Uncertainty 61 4.1 Overview 61 4.2 Problem Formulation 63 4.3 Prediction Under Identity Uncertainty 65 4.3.1 Multiple-Hypothesis Prediction 66 4.3.2 Appearance Model for a Kinect Sensor 68 4.4 Tracking Failure Probability 69 4.5 Motion Strategies 72 4.5.1 Optimization for 1 73 4.5.2 Optimization for 2 73 4.6 Experiments 74 4.6.1 Simulation: Single-Step Target Tracking 74 4.6.2 Simulation: Multi-Step Target Tracking 76 4.6.3 Pedestrian Tracking Experiments 77 4.7 Summary 79 5 Robust Multi-Layered Sampling-Based Path Planning for Temporal Logic-Based Missions 89 5.1 Overview 89 5.2 Problem Formulation 92 5.2.1 Mission Failure Probability 94 5.2.2 Feasibility 96 5.3 Proposed Method 97 5.3.1 Data Structure 97 5.3.2 High-Level Planner 98 5.3.3 Low-Level Planner 99 5.3.4 Analysis 103 5.4 Experimental results 105 5.4.1 Simulation Study 105 5.4.2 Experiments 110 5.5 Summary 110 6 Robust Multi-Objective Path Planning under time-varying disturbances 123 6.1 Problem Formulation 125 6.1.1 Fluid Flow Estimation 127 6.1.2 Mission completion 129 6.1.3 Mission Failure Probability 130 6.1.4 Feasibility 132 6.2 Proposed Method 133 6.2.1 High-Level planner 133 6.2.2 Low-Level Planner 135 6.2.3 Analysis 137 6.3 Simulations 141 6.4 Summary 150 7 Conclusion and Future Work 153Docto