송정환 교수

Fully first-principles calculations for the second-harmonic susceptibilities of recently synthesized alkali-metal chalcogenides such as ${\text{KPSe}}_{6}$, ${\text{K}}_{2}{\text{P}}_{2}{\text{Se}}_{6}$, ${\text{LiAsS}}_{2}$, and ${\text{NaAsSe}}_{2}$ predict a record-breaking second-harmonic generation coefficient among materials with band gaps larger than 1.0 eV, with the highest value being that for ${\text{NaAsSe}}_{2}$, namely, 324.6 pm/V. A detailed analysis of their highly precise full-po

Biclique cryptanalysis is an attack that improves the computational complexity by finding a biclique which is a kind of bipartite graph. We present a single-key full-round attack of lightweight block ciphers, HIGHT and Piccolo by using biclique cryptanalysis. In this paper, a 9-round biclique is constructed for HIGHT and a 4-round biclique for Piccolo. These new bicliques are used to recover secret keys for the full rounds of HIGHT, Piccolo-80 and Piccolo-128, the computational complexity of 212

By confining light in a small cavity, the spontaneous emission rate of an emitter can be controlled via the Purcell effect. However, while Purcell factors as large as ∼10,000 have been predicted, actual reported values were in the range of about 10-30 only, leaving a huge gap between theory and experiment. Here we report on enhanced 1.54-μm emission from Er(3+) ions placed in a very small metallic cavity. Using a cavity designed to enhance the overall Purcell effect instead of a particular compo

In this paper, we focus on multi-path transport layer mechanisms of ICN. We first provide the comprehensive analysis of design criteria and possible solutions for designing multi-path Interest forwarding and congestion control mechanisms. We then propose a Subflow-level Multi-path Interest Control (SMIC) scheme to enhance the performances of content deliveries over multiple paths, while achieving throughput-friendliness with single path flows (controlled by TCP-like congestion control). Simulati

We propose nano-optical antennas with asymmetric radiation patterns as light-driven mechanical recoil force generators. Directional antennas are found to generate recoil force efficiently when driven in the spectral proximity of their resonances. It is also shown that the recoil force is equivalent to the Poynting vector integrated over a closed sphere containing the antenna structures.

Biclique cryptanalysis is an attack which reduces the computational complexity by finding a biclique which is a kind of bipartite graph. We show a single-key full-round attack of the Crypton-256 and mCrypton-128 by using biclique cryptanalysis. In this paper, 4-round bicliques are constructed for Crypton-256 and mCrypton-128. And these bicliques are used to recover master key for the full rounds of Crypton-256 and mCrypton-128 with the computational complexities of 2 253.78 and 2 126.5 , respect

A high resolution inverse synthetic aperture radar (ISAR) technique is presented using modified Doppler history based motion compensation. To this purpose, a novel wideband ISAR system is developed that accommodates parametric processing over extended aperture length. The proposed method is derived from an ISAR-to-SAR approach that makes use of high resolution spotlight SAR and sub-aperture recombination. It is dedicated to wide aperture ISAR imaging and exhibits robust performance against unsta

Piccolo is a 64-bit lightweight block cipher which is able to be implemented in constrained hardware environments such as a wireless sensor network. Fault analysis is a type of side channel attack and cube attack is an algebraic attack finding sufficiently low-degree polynomials in a cipher. In this paper, we show a fault analysis on the Piccolo by using cube attack. We find 16 linear equations corresponding to a round function F by cube attack, which are used to fault analysis. Our attack has t

Abstract approved: Immersion energies for an impurity in a homogeneous electron gas with a uni-form positive background charge density have been calculated numerically using density functional theory. The numerical aspects of this problem are very de-manding and have not been properly discussed in previous work. The numerical problems are related to approximations of infinity and continuity, and they have been corrected using physics based on the Friedel sum rule and Friedel oscillations. The nu

암호기술의 발전으로 통신의 비밀이나 정보보호가 강화되었지만, 암호기술을 역이용하는 Cryptovirus가 등장하였고 윈도우즈 CAPI(Crypto API)를 사용하는 악성코드도 누구나 쉽게 제작하여 배포할 수 있는 환경이 되었다. CAPI를 사용하는 악성코드는 윈도우즈에서 제공하는 정상적인 API를 사용하기 때문에 IPS(Intrusion Prevention System) 등 정보보호시스템은 물론 백신프로그램에서도 탐지 및 분석이 쉽지 않다. 본 논문에서는 Cryptovirus를 비롯하여 윈도우즈 CAPI를 사용하는 악성코드 무력화 방안 연구 및 이와 관련된 Hooking 도구 구현결과를 제시하고자 한다.

In this paper, a novel high resolution inverse synthetic aperture radar (ISAR) processing technique is proposed. The proposed method employs sub-aperture recombination scheme such that target features can be effectively preserved even for wide aperture data. The proposed ISAR-to-SAR approach is introduced and Doppler history based motion compensation is described. In order to evaluate the proposed algorithm in real environment, we developed an experimental ISAR system. The proposed algorithm is

Advances in encryption technology to secret communication and information security has been strengthened. Cryptovirus is the advent of encryption technology to exploit. Also, anyone can build and deploy malicious code using windows CAPI. Cryptovirus and malicious code using windows CAPI use the normal windows API. So vaccine software and security system are difficult to detect and analyze them. This paper examines and make hooking tool against Crytovirus and malicious code using windows CAPI.

We demonstrate large enhancement of spontaneous emission (Fp>70) from Er atoms embedded in gold nano-trench structures. This is confirmed by clear correlation between increased decay rate and enhanced photoluminescence as a function of resonant wavelength.