The shifting role of the state in South Korea’s industrial and technological development : a review of the semiconductor industry

textDue to a weak industrial base coupled with devastation from the Korean War, South Korea was a latecomer in industrialization, and formal economic development began during the 1960s under heavy state intervention. Within this broader context of industrial development, this research examines the role of state in the development of South Korea’s semiconductor industry. The results show that government support for semiconductors has gradually shifted from full-fledged intervention through both initial technology procurement and commercialization during the 1960s, to a minimal role of developing human capital and promoting private sector investment in R&D at present. But despite the importance of adhering to principles of free trade, the Hynix crisis of 2003 and the recent economic crisis of 2008 demonstrate the continued importance of the government’s role in protecting and promoting strategic industries such as semiconductors.Public Affair

Algorithms for routing problems in stochastic time-dependent networks

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering; and, (S.M.)--Massachusetts Institute of Technology, Sloan School of Management, Operations Research Center , 2002.Includes bibliographical references (p. 185-187).by Seong-Cheol Kang.S.M

Statistical Characterization of Indoor MIMO Channel Properties at 5.8GHz in the Office Building

A wideband 4×4 MIMO (multiple-input multiple-output) channel sounding system has been developed to measure 16 Tx-Rx pair channels simultaneously using PN (pseudo noise) correlation method. Measurement campaign in the medium size office building with the developed channel sounding system is reported. Measured results are analyzed to compute channel parameters such as rms delay spread, mean excess delay, and their statistics. MIMO system capacity is also analyzed from measured channel impulse responses. Statistics of computed channel parameters can be used to develop empirical wideband MIMO channel models

Interfacial chemical bonding-mediated ionic resistive switching.

In this paper, we present a unique resistive switching (RS) mechanism study of Pt/TiO2/Pt cell, one of the most widely studied RS system, by focusing on the role of interfacial bonding at the active TiO2-Pt interface, as opposed to a physico-chemical change within the RS film. This study was enabled by the use of a non-conventional scanning probe-based setup. The nanoscale cell is formed by bringing a Pt/TiO2-coated atomic force microscope tip into contact with a flat substrate coated with Pt. The study reveals that electrical resistance and interfacial bonding status are highly coupled together. An oxygen-mediated chemical bonding at the active interface between TiO2 and Pt is a necessary condition for a non-polar low-resistance state, and a reset switching process disconnects the chemical bonding. Bipolar switching mode did not involve the chemical bonding. The nature of chemical bonding at the TiO2-metal interface is further studied by density functional theory calculations

Some Results on the Analysis of Stochastic Processes with Uncertain Transition Probabilities and Robust Optimal Control

This paper investigates stochastic processes that are modeled by a finite number of states but whose transition probabilities are uncertain and possibly time-varying. The treatment of uncertain transition probabilities is important because there appears to be a disconnection between the practice and theory of stochastic processes due to the difficulty of assigning exact probabilities to real-world events. Also, when the finite-state process comes as a reduced model of one that is more complicated in nature (possibly in a continuous state space), existing results do not facilitate rigorous analysis. Two approaches are introduced here. The first focuses on processes with one terminal state and the properties that affect their convergence rates. When a process is on a complicated graph, the bound of the convergence rate is not trivially related to that of the probabilities of individual transitions. Discovering the connection between the two led us to define two concepts which we call 'progressivity' and 'sortedness', and to a new comparison theorem for stochastic processes. An optimality criterion for robust optimal control also derives from this comparison theorem. In addition, this result is applied to the case of mission-oriented autonomous robot control to produce performance estimate within a control framework that we propose. The second approach is in the MDP frame work. We will introduce our preliminary work on optimistic robust optimization, which aims at finding solutions that guarantee the upper bounds of the accumulative discounted cost with prescribed probabilities. The motivation here is to address the issue that the standard robust optimal solution tends to be overly conservative

Reflection coefficient calculation of a feeder structure in a RLSA

RLSA(Radial line slot antenna) is slotted waveguide array antenna which is proposed for the DBS(Direct Broadcast from a Satellite) reception. Theoretically, it has lower conduction loss and higher effectiveness than the planar antenna using microstrip. DL-RLSA(Double-layered RLSA) uses radially inward travelling wave for the slot excitation in the double-layered radial line. The effectiveness of DL-RLSA is more than 75%(33.0~37dBi), which is two times as high effectiveness as other planar antenna. In spite of that advantage, SL-RLSA(Single-layered RLSA) is more popular because of the complex structure of DL-RLSA. But the radially outward travelling wave of SL-RLSA makes high tapering when the travelling wave approaches the aperture edge. To remove these troublesome thing, a effective feeder structure which has tilting rod is proposed in this paper. To find the optimum height and tilting angle of the feeder, the finitedifference time-domain(FDTD) method is employed. In other words, the simulation parameter of the FDTD algorithm is the dimension of feeder. Compared with the effectiveness of the conventional rod feeder structure, that of the proposed feeder structure in this paper is enhanced by 5dB

Performance Evaluation of Positioning Techniques Based on UWB Radio

In this paper, performances of positioning techniques based on UWB radio are evaluated. The positioning techniques for UWB systems, SS, and time based algorithms, TOA and TDOA, are the target ones to be analyzed. Using the reported CRLB of each algorithm, the location estimation error is obtained. The estimation error variation to the number of base stations is reported also.This work is supported in part by ITRC and Seoul R&BD Program (10544)

Ultra Wideband Propagation Characteristics in Office Eenvironments

Ultra Wideband (UWB) is the promising candidate for short-range high-speed wireless communication system. But, the UWB propagation characteristics, the fundamental resource for overall system design, have not fully analyzed yet. In this work, we investigated the UWB indoor propagation characteristics in office environments. So, we constructed the UWB channel measurement system using the frequency sweep method to measure the frequency responses on the 5GHz ~ 6.6GHz band. The measurements were performed in the 2 different offices, 34 receiver positions (20 positions are line-of-sight and 14 positions are non line-of-sight). From these measurement results, firstly, we modeled the path loss behavior of UWB signal. The path loss exponent and variance of log-distance law are suggested. Not only in case of full band, but also in case of each sub-band path loss parameters are analyzed. Then, the distributions of received signal powers are compared with the Gaussian distribution according to the receiver condition. Finally, for 9 receiver positions located in the corridor, the propagation characteristic difference between the case when a door is closed and the case when a door is opened is reported. The additional path loss and loss due to the door material and frequency selective characteristics are primarily analyzed

Effect of Metal Door On Indoor Radio Channel

This paper reports the variation of indoor radio channel caused by metal door. The simulation results using the Finite Difference Time Domain (FDTD) method and measurement results using the vector network analyzer in frequency domain are used for the characterization of received signal strength variation by metal door. Target frequency bands are three - sensor band, 802.11b ISM band, and 802.11a UNII band. From the simulation and measurement results, the effect of door angle to the received signal strength in three frequency bands and effect of radio frequency to variation are investigated. And, FDTD simulation parameters for different environments are suggested

Empirical Ultra Wide Band Path Loss Model in Office Environments

This paper reports the empirical path loss model of Ultra Wide Band (UWB) communications in office environments. The channel transfer functions of 46 transmitter-receiver location pairs are acquired using channel measurement system based on frequency sweep method. From the measured data, parameters of log-distance path loss formula are extracted considering propagation environments and existence of a line of sight path. The effect of frequency to the path loss properties of ultra wideband signal is presented also. Finally, statistical properties of received signal power with respect to the receiver conditions are analyzed