Evolution of Service Model and Architecture of ASP Business

ASP has been a buzzword among enterprise IT area since mid 1990s. Following after the hype cycle of new technologies like others, many market analysts say that ASP technology is now in a plateau of productivity sequence through trough of disillusionment sequence over past 5 years. In the Republic of Korea, MIC (Ministry of Information and Communication) and KT began ASP service called bizmeka® to help companies adopt the newest information technologies on KT’s information superhighway since 2000. Like other ASP players in other countries, there were similar obstacles and problems that are difficult to solve. But with the introduction of new concept of service model and architecture, the difficulties of managing business improved. In this paper, we will discuss about how ASP business of Korea started, managed and made evolution of service model and architecture to meet the various demands of enterprises over past 4 years

Optimization of Reactive Ion Etching (RIE) Parameters for Selective Removal of MOSFET Gate Dielectric and Evaluation of its Physical and Electrical Properties

The integrated circuit (IC) is dominated by technology using Complementary Metal-oxide-Semiconductor Field-effect Transistor (CMOSFET). In order to put over 300 million transistors on silicon chip requires selective removal of material by Reactive Ion Etching (RIE) which ensures vertical cut thereby increasing packing density of devices on the chip. The gate insulator of CMOS devices plays a crucial role in its electrical performance. In this research gate insulator of MOSFET has been etched by state-of-art technique RIE and its physical and electrical properties have been measured. The gate insulator etching by RIE give rise to charge accumulation on the gate dielectric resulting in change in threshold voltage. Also early breakdown of MOS devices is a direct consequence of charge accumulation on gate dielectric during RIE process. The RIE etching was performed with Technics Series 85-RIE unit, and it was optimized in respect of power, pressure, and composition of gases to achieve less charge accumulation, and stable threshold voltage. The thickness of the gate insulator was measured by the Nanospec before and after etching. Charges accumulated on gate oxide were measured by HP 4280A which is a high frequency capacitance-voltage (CV) measurement system. Annealing of the RIE etched gate oxide were performed at suitable temperature to bring the charges to minimum level. Results of the research are presented in tables and figures

PIM-Enclave: Bringing Confidential Computation Inside Memory

Demand for data-intensive workloads and confidential computing are the prominent research directions shaping the future of cloud computing. Computer architectures are evolving to accommodate the computing of large data better. Protecting the computation of sensitive data is also an imperative yet challenging objective; processor-supported secure enclaves serve as the key element in confidential computing in the cloud. However, side-channel attacks are threatening their security boundaries. The current processor architectures consume a considerable portion of its cycles in moving data. Near data computation is a promising approach that minimizes redundant data movement by placing computation inside storage. In this paper, we present a novel design for Processing-In-Memory (PIM) as a data-intensive workload accelerator for confidential computing. Based on our observation that moving computation closer to memory can achieve efficiency of computation and confidentiality of the processed information simultaneously, we study the advantages of confidential computing \emph{inside} memory. We then explain our security model and programming model developed for PIM-based computation offloading. We construct our findings into a software-hardware co-design, which we call PIM-Enclave. Our design illustrates the advantages of PIM-based confidential computing acceleration. Our evaluation shows PIM-Enclave can provide a side-channel resistant secure computation offloading and run data-intensive applications with negligible performance overhead compared to baseline PIM model

Precedence and Exogeneity of Oil to the Stock Markets

This study investigates whether changes of oil price would have precedence, exogeneity and causal prediction to the stock markets. The result shows that changes of oil price have precedence over the stock returns in the United States, Japan and Korea markets. And the evidence suggests that there be exogeneity of oil to the stock markets because the stock returns can be causally interpreted by the current or past changes of oil price during the past two decades. Thus changes of oil price would contain any information exploitable in forecasting the stock markets and have the predictive value of leading indicators

소용량 수동 소자와 직류단 보조 에너지 저장 회로를 가지는 교류 전동기 구동 시스템에 관한 연구

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2015. 8. 하정익.In power conversion system, passive components such as grid filter inductor and DC-link capacitor have been widely used. However, they have several problems that they occupy too many spaces in the entire and an electrolytic capacitor which is commonly used in DC-link has a low reliability due to its high failure rate. To reduce or replace them, novel control methods or topologies using extra active devices with low-power-rating have been proposed, and these methods match to a trend of cost reduction of high-performance switching devices. Hence this dissertation proposes control method for diode rectifier-fed system equipping small passive components and an auxiliary circuit called as DC-link shunt compensator (DSC). Owing to the absence of the electrolytic capacitor, the proposed structure is robust in terms of component failure. Moreover the diode rectifier-fed system using the proposed method can satisfy grid regulations such as IEC 61000-3-12 or -3-2 without power factor correction (PFC) or heavy grid filter inductor. The proposed method includes the grid current shaping and system operating methods which improve grid current harmonics and system performances, respectively. This dissertation also presents implementation methods by using either motor drive inverter or DSC. The former is the most cost-effective way to realize proposed method but it necessarily degrades output performances such as torque quality and system efficiency. The latter requires auxiliary switching devices and small passive components, but it has advantages in not only output performances but also system efficiency by cooperation of DSC. The proposed DSC operating strategy is presented in detail and corresponding design guideline is also provided. In this dissertation, the DSC operating method is considered for both single- and three-phase diode rectifier-fed systems. In the case of the diode rectifier system using small passive components, the waveform of DC-link voltage is totally different in accordance with the gird phase, thus the corresponding control algorithms for both single- and three-phase inputs are also established respectively. This dissertation proposes each dedicated control method and discusses the feasibility. As a practical implementation example, boost converter is selected for the structure of DSC, and the validity of proposed methods are verified by simulation and experimental results.Abstract i List of Figures vi List of Tables xi 1 Introduction 1 1.1 Backgrounds and Motivations 1 1.2 Objectives 3 1.3 Dissertation Outlines 6 2 Conventional Motor Drive System 8 2.1 Review of Motor Drive System with Passive Components 8 2.1.1 DC-Link Capacitor 9 2.1.2 Grid Harmonic Regulations and Grid Filter Inductor 14 2.1.3 Limitation of Passive Components 24 2.2 Diode Rectifier Systems with Small DC-Link Capacitor ? State of the Art and Challenges 27 2.2.1 Review of Conventional Small DC-Link Capacitor System 27 2.2.2 Limitation of Conventional Systems 38 2.3 Conventional Systems with Auxiliary Circuit for Reducing Passive Components 40 2.3.1 Current Injection Topologies 41 2.3.2 Series Compensation Topologies 43 2.3.3 Parallel Compensation Topologies 45 3 Grid Current Shaping and DSC Operating Methods in Three-Phase Diode Rectifier System 50 3.1 Grid Current Shaping Method for Three-Phase System 53 3.1.1 Operating Principle of Proposed Control Method 53 3.1.2 System Stability Analysis 61 3.2 Implementation Based on Motor Drive Inverter 63 3.2.1 Control Block Diagram 64 3.2.2 Effect on the Motor Drive System 69 3.3 Three-Phase System with DSC 73 3.3.1 System Configuration 74 3.3.2 Control Method 76 3.3.3 System Design Guideline 83 3.4 Simulation and Experimental Results 87 3.5 Discussions 101 4 Grid Current Shaping and DSC Operating Methods in Single-Phase Diode Rectifier System 104 4.1 Conventional Single-Phase Small DC-Link Capacitor System 105 4.1.1 Control Method [26] 105 4.1.2 Limitation of Single-Phase Small DC-Link Capacitor System 108 4.2 Single-Phase System with DSC 109 4.2.1 System Configuration 109 4.2.2 Operating Concept 111 4.2.3 Partial Power Assistance Operating Strategy 116 4.2.4 Control Method 121 4.2.5 System Design Guideline 126 4.3 Simulation and Experimental Results 128 4.4 Discussions 141 4.4.1 System Operating Strategies 141 4.4.2 Availability of single-phase DSC system 143 5 Conclusion and Future Works 147 Appendix 150 A.1 Case Study 1: Implementation Cost of Three-Phase DSC System 150 A.2 Case Study 2: Implementation Cost of Single-Phase DSC System 152 References 155 초 록 167Docto

A Novel Approach for Seasonal Influenza Surveillance in South Korea: Disease Burden Estimation and Temporal Trends Monitoring

Seasonal influenza is one of the most common infectious diseases with great disease burden. Public health professionals have given many afford to estimate the accurate the disease burden and monitor temporal trends of seasonal influenza. However current influenza surveillance system in South Korea could not provide full functions on disease burden estimation and temporal trends monitoring. There is a need for supporting structure to make robust surveillance. In aim 1, we aimed to estimate the burden of influenza and its related disease based on billing information from the national health insurance service – national sample cohort. We found that rural area of South Korea has more disease burden compared to the urban area and age under 5 had the highest burden of influenza infection. In aim 2, we assess the timeliness of influenza epidemiological information from billing system compared to current sentinel surveillance as temporal trends monitoring. We did not observe any delays of influenza out-patients activity compared to current sentinel surveillance in peak time and cross-correlation value comparison. We could not fully apply aberration time comparison since aberration signals highly depended on model sensitivity and specificity and model selection process itself. In aim 3, we were able to perform influenza temporal trends association analysis by subpopulations. The Seoul Capital Area showed the early signs of influenza activity in peak and cross-correlation time comparison. Age 6 to 15 showed the earlier sign of influenza activity while age over 65 showed the later sing of influenza activity. We were able to estimate the burden of influenza with different case definitions and provided stratified disease burden as WHO guided. We did not see any delays of influenza out-patient activity from billing system compared to the current sentinel surveillance. Moreover, we observed potential temporal associations of influenza activity by different subpopulations. A surveillance system based on solely billing information cannot be perfect by itself. Instead, combinations of surveillance structures with a different source for disease information can be called a robust surveillance system. The surveillance system should have different arrangements with the various data source to make concordance of observation

Towards Validating Long-Term User Feedbacks in Interactive Recommendation Systems

Interactive Recommender Systems (IRSs) have attracted a lot of attention, due to their ability to model interactive processes between users and recommender systems. Numerous approaches have adopted Reinforcement Learning (RL) algorithms, as these can directly maximize users' cumulative rewards. In IRS, researchers commonly utilize publicly available review datasets to compare and evaluate algorithms. However, user feedback provided in public datasets merely includes instant responses (e.g., a rating), with no inclusion of delayed responses (e.g., the dwell time and the lifetime value). Thus, the question remains whether these review datasets are an appropriate choice to evaluate the long-term effects of the IRS. In this work, we revisited experiments on IRS with review datasets and compared RL-based models with a simple reward model that greedily recommends the item with the highest one-step reward. Following extensive analysis, we can reveal three main findings: First, a simple greedy reward model consistently outperforms RL-based models in maximizing cumulative rewards. Second, applying higher weighting to long-term rewards leads to a degradation of recommendation performance. Third, user feedbacks have mere long-term effects on the benchmark datasets. Based on our findings, we conclude that a dataset has to be carefully verified and that a simple greedy baseline should be included for a proper evaluation of RL-based IRS approaches.Comment: Accepted to SIGIR'2

ST-RAP: A Spatio-Temporal Framework for Real Estate Appraisal

In this paper, we introduce ST-RAP, a novel Spatio-Temporal framework for Real estate APpraisal. ST-RAP employs a hierarchical architecture with a heterogeneous graph neural network to encapsulate temporal dynamics and spatial relationships simultaneously. Through comprehensive experiments on a large-scale real estate dataset, ST-RAP outperforms previous methods, demonstrating the significant benefits of integrating spatial and temporal aspects in real estate appraisal. Our code and dataset are available at https://github.com/dojeon-ai/STRAP.Comment: Accepted to CIKM'2

Capacity: Cryptographically-Enforced In-Process Capabilities for Modern ARM Architectures (Extended Version)

In-process compartmentalization and access control have been actively explored to provide in-place and efficient isolation of in-process security domains. Many works have proposed compartmentalization schemes that leverage hardware features, most notably using the new page-based memory isolation feature called Protection Keys for Userspace (PKU) on x86. Unfortunately, the modern ARM architecture does not have an equivalent feature. Instead, newer ARM architectures introduced Pointer Authentication (PA) and Memory Tagging Extension (MTE), adapting the reference validation model for memory safety and runtime exploit mitigation. We argue that those features have been underexplored in the context of compartmentalization and that they can be retrofitted to implement a capability-based in-process access control scheme. This paper presents Capacity, a novel hardware-assisted intra-process access control design that embraces capability-based security principles. Capacity coherently incorporates the new hardware security features on ARM that already exhibit inherent characteristics of capability. It supports the life-cycle protection of the domain's sensitive objects -- starting from their import from the file system to their place in memory. With intra-process domains authenticated with unique PA keys, Capacity transforms file descriptors and memory pointers into cryptographically-authenticated references and completely mediates reference usage with its program instrumentation framework and an efficient system call monitor. We evaluate our Capacity-enabled NGINX web server prototype and other common applications in which sensitive resources are isolated into different domains. Our evaluation shows that Capacity incurs a low-performance overhead of approximately 17% for the single-threaded and 13.54% for the multi-threaded webserver.Comment: Accepted at ACM CCS 202

Pion single charge exchange on the deuteron

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1995.Includes bibliographical references (leaves 233-235).by Hojoon Timothy Park.Ph.D