Advanced Photoresist Technologies by Intricate Molecular Brush Architectures

With recent technological improvements, fabrication of integrated circuit elements on shrinking scales is required to meet the demand for massive storage and fast data processing. As the fabrication of high resolution patterns requires short wavelength radiation sources, extreme ultraviolet and electron beam techniques have been developed as radiation sources for next-generation lithography. Advancements of lithography techniques accompany the evolution of resist materials for the synchronous fulfillment of high sensitivity, high resolution, and high structural integrity. Our strategy for nanofabrication is a combination of bottom-up synthesis and top-down lithography. The use of cylindrical brush polymers, which can vertically align on substrates, affords access to electron-beam-generated patterns with the minimum pixel size determined by the cylinder diameter. Cylindrical brush polymers for negative- and positive-tone photoresist materials were synthesized by controlled radical and olefin metathesis polymerization. Macromonomers with well-defined size variations were prepared by reversible addition-fragmentation chain transfer polymerization of monomers having surface energy reducing, substrate adhesion enhancing, and lithographically functioning moieties. Then, sequential ring-opening metathesis polymerization of the macromonomers via a “grafting-through” strategy allows precise control of concentric and lengthwise dimensions and compositions in the brush polymer structures. The brush polymers consist of a rigid polymeric backbone with covalently tethered side chains which allow facile access to a cylindrical morphology due to their steric repulsion. Low surface energy of fluoropolymers at one end and the high polarity of groups at the other end drive the cylindrical brush polymers to vertically align on the polar silicon wafer substrate as characterized by surface analysis techniques. The stretched conformation of the brush polymers facilitates their assembly by reducing chain entanglement. The chemically amplified resists from the brush polymers exhibit high lithographic performance with a few tens of nanometer resolution. The brush polymers with poly(p-hydroxystyrene)s yielded negative-tone features by crosslinking chemistry, while those having acid-labile tertiary esters gave positive-tone features. Cylindrical brush polymer based resists showed their superior lithographic performance over linear block copolymer precursors in both resolution and sensitivity by having each vertically aligned molecule act as a molecular pixel. As a result, the tuning of composition and dimension using bottom-up synthetic strategy allows the fine tuning of top-down lithographic performance. Cylindrical brush polymers for negative- and positive-tone photoresist materials were synthesized by controlled radical and olefin metathesis polymerization. Macromonomers with well-defined size variations were prepared by reversible addition-fragmentation chain transfer polymerization of monomers having surface energy reducing, substrate adhesion enhancing, and lithographically functioning moieties. Then, sequential ring-opening metathesis polymerization of the macromonomers via a “grafting-through” strategy allows precise control of concentric and lengthwise dimensions and compositions in the brush polymer structures. The brush polymers consist of a rigid polymeric backbone with covalently tethered side chains which allow facile access to a cylindrical morphology due to their steric repulsion. Low surface energy of fluoropolymers at one end and the high polarity of groups at the other end drive the cylindrical brush polymers to vertically align on the polar silicon wafer substrate as characterized by surface analysis techniques. The stretched conformation of the brush polymers facilitates their assembly by reducing chain entanglement. The chemically amplified resists from the brush polymers exhibit high lithographic performance with a few tens of nanometer resolution. The brush polymers with poly(p-hydroxystyrene)s yielded negative-tone features by crosslinking chemistry, while those having acid-labile tertiary esters gave positive-tone features. Cylindrical brush polymer based resists showed their superior lithographic performance over linear block copolymer precursors in both resolution and sensitivity by having each vertically aligned molecule act as a molecular pixel. As a result, the tuning of composition and dimension using bottom-up synthetic strategy allows the fine tuning of top-down lithographic performance

Physical Water Treatment for the Mitigation of Mineral Fouling in Cooling-Tower Water Applications

The physical water treatment (PWT) device is defined as a non-chemical method of water treatment utilized for the purpose of scale prevention or mitigation. Three different PWT devices, including permanent magnets, solenoid coil device, and high-voltage electrode, were used under various operating conditions. The present study proposed a bulk precipitation as the mechanism of the PWT and conducted a number of experimental tests to evaluate the performance of the PWT. The results of fouling resistances obtained in a heat transfer test section clearly demonstrated the benefit of the PWT when the PWT device was configured at an optimum condition. The results of SEM and X-ray diffraction methods were obtained to further examine the difference in scale crystal structures between the cases of no treatment and PWT. Furthermore, the surface tension of water samples was measured, and it was found that the PWT reduces the surface tension by approximately 8% under repeated treatment as in cooling-tower applications

Prevention of Cross-update Privacy Leaks on Android

Updating applications is an important mechanism to enhance their availability, functionality, and security. However, without careful considerations, application updates can bring other security problems. In this paper, we consider a novel attack that exploits application updates on Android: a cross-update privacy-leak attack called COUPLE. The COUPLE attack allows an application to secretly leak sensitive data through the cross-update interaction between its old and new versions; each version only has permissions and logic for either data collection or transmission to evade detection. We implement a runtime security system, BREAKUP, that prevents cross-update sensitive data transactions by tracking permission-use histories of individual applications. Evaluation results show that BREAKUP’s time overhead is below 5%. We further show the feasibility of the COUPLE attack by analyzing the versions of 2,009 applications (28,682 APKs). © 2018, ComSIS Consortium. All rights reserved.11Ysciescopu

Analysis Method for Determining Optimal Synthetic Aperture Time Using Estimated Range and Doppler Cone Angle at the Center of Synthetic Aperture Length

Synthetic aperture time (SAT) is a crucial component for acquiring high-quality synthetic aperture radar images with an excellent target cross-range resolution. SAT is analyzed using the range and Doppler cone angle at the center of the synthetic aperture length (SAL). However, in a real flight mission setting, only the range and Doppler cone angle at the SAL’s starting point are determined. Therefore, we present a method for estimating the range and Doppler cone angle at the center of the SAL to calculate an accurate SAT that is suitable for the spatial resolution of the assigned mission. We performed an iterative analysis of SAT at the range and Doppler cone angle at the starting point of the SAL (original SAT) and at the center of the SAL (proposed SAT). Consequently, the proposed SAT decreased by 0.69%–16.14% compared to the original SAT at a resolution of 0.1–3.0 m

Optimized Use Of Water From Multiple Sources In Micro Water Grid Systems: A Modeling Approach

Micro water grid (MWG) is a novel approach to allow high reliability, diversification of water sources, low energy consumption, and cost reduction. Although it is not well-defined, it has potential for efficient management of urban water. MWG is suitable for use in small-scale buildings and towns, which have various uses of water produced from multiple source waters. Accordingly, design of MWG is challenging without proper tools to predict its performance. This research focused on the development and application of a model for optimized use of water from multiple sources in MWG systems. The model was comprised of two modules including strategy identification and mass balance calculator. The former assists in identifying strategy under the given natural and infrastructural conditions. The latter helps to determine water demand/supply and dimension of the water treatment system. Water from various sources including tap water, ground water, rainwater, reclaimed water, and desalinated water was considered in the model. The model and its graphic user interface (GUI) were built under the Matlab environment. Results show that the simulation model was found to be effective to optimize the performance of MWG. Based on the sensitivity analysis of the model, factors affecting the effectiveness of MWG could be identified. Moreover, this model was applied to design a pilot-scale MWG system in a building, predict its water quantity and water quality, and estimate the specific energy consumption. ACKNOWLEDGEMNET This research was supported by a grant (12-TI-C01) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government

Development Of A Model-Based Decision Support System For Water Treatment In Smart Micro Water Grid

Micro water grid (MWG) is an emerging concept for decentralized water management system for residential, industrial, commercial, and institutional buildings. MWG achieves specific local goals, such as reliability, diversification of water sources, and cost reduction. Unlike micro electricity grid, MWG has not been well-established, leading to a problem of initial design and operation. Thus, a MWG system requires a “smart” infrastructure that allows autonomous control and regulation. In this study, a decision support system (DSS) was designed to select optimum combinations of water treatment unit processes in MWG. To begin, key questions on water treatment in MWG systems were identified. Then, the knowledge-based system was developed based on the inputs from experts in related research fields and the prediction of treatment efficiency from theoretical model. A series of experiments were carried out to obtain the model parameters for each unit process (i.e. media filtration, microfiltration, GAC, nanofiltration, chlorination, UV). The flow chart for decision making was created and revised upon considering virtually all possible situations in MWG. As the final step, a web-based system was developed and implemented. Although it is a first version of DSS for MWG, it has potential for an increase in the efficiency of water treatment under various situations. ACKNOWLEDGEMNET This research was supported by a grant (12-TI-C01) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government

A Smart Checkpointing Scheme for Improving the Reliability of Clustering Routing Protocols

In wireless sensor networks, system architectures and applications are designed to consider both resource constraints and scalability, because such networks are composed of numerous sensor nodes with various sensors and actuators, small memories, low-power microprocessors, radio modules, and batteries. Clustering routing protocols based on data aggregation schemes aimed at minimizing packet numbers have been proposed to meet these requirements. In clustering routing protocols, the cluster head plays an important role. The cluster head collects data from its member nodes and aggregates the collected data. To improve reliability and reduce recovery latency, we propose a checkpointing scheme for the cluster head. In the proposed scheme, backup nodes monitor and checkpoint the current state of the cluster head periodically. We also derive the checkpointing interval that maximizes reliability while using the same amount of energy consumed by clustering routing protocols that operate without checkpointing. Experimental comparisons with existing non-checkpointing schemes show that our scheme reduces both energy consumption and recovery latency

Integrated Rocket Simulation of Internal and External Flow Dynamics in an e-Science Environment

The internal and external flowfield variation of a launch vehicle has been simulated in an e-Science environment. To analyze the igniting process of a solid-rocket propellant, a fluid-structure interaction code has been developed using an ALE (arbitrary Lagrangian Eulerian) kinematical description and a staggered fluid-structure interaction algorithm. Also, unsteady motion of a detached rocket booster has been predicted by using an external flow analysis with an aerodynamic-dynamic coupled solver. A Korean e-Science environment designed for aerospace engineering, e-AIRS [15], supplies a user-friendly interface for such individual work and it can advance to an integrated rocket simulation of internal combustion and external flow variation by controlling the execution and data flow of two flow solvers. As a consequence, e-Science facilitates multi-disciplinary collaborative research, and makes individual work more convenient.The current work is a product of the Korea National e-Science project. The authors are grateful to the Korea Institute of Science and Technology Information for their financial support. Also, the authors appreciate the financial supports provided by NSL(National Space Lab.) program through the National Research Foundation of Korea funded by the Ministry of Education, Science and Technology (Grant 20090091724) and the authors are grateful to the Agency for Defence Development for financial support on solid-rocket propellant research.OAIID:oai:osos.snu.ac.kr:snu2009-01/102/0000004648/4SEQ:4PERF_CD:SNU2009-01EVAL_ITEM_CD:102USER_ID:0000004648ADJUST_YN:YEMP_ID:A001138DEPT_CD:446CITE_RATE:1.2FILENAME:article.pdfDEPT_NM:기계항공공학부EMAIL:[email protected]_YN:YCONFIRM:

A Case of a Pulmonary Arteriovenous Malformation With Ebstein's Anomaly

A pulmonary arteriovenous malformation (PAVM) is a rare pulmonary vascular anomaly presenting as dyspnea or recurrent epistaxis. Ebstein's anomaly (EA), a congenital cardiac malformation, is also a rare condition. There have been no reports concerning the co-existence of PAVM with hereditary hemorrhagic telangiectasia (HHT) and EA. A 40-year-old woman was admitted with a 2-month history of increasing dyspnea and several years of recurrent epistaxis. On transthoracic echocardiography, she was diagnosed with EA and agreed to undergo surgical treatment. A chest CT angiography showed a 12-mm serpiginous vascular structure suspicious for a PAVM and a liver CT suggested HTT. Although it is unclear whether or not a concurrent PAVM and EA have an embryologic or genetic relationship, we report a case of a PAVM with EA. Further genetic and embryonic studies are needed to identify a possible relationship of the two medical conditions