우크라이나 침공에 대한 국제법적 검토

남승현 국립외교원 외교안보연구소 2022 (IFANS)주요국제문제분석 Vol.2022 No.16

회전근개 봉합술에서 나사못의 모양과 재질이 고정력에 미치는 영향

남승현,최대경,박원만,김경수,장승호,김윤혁 대한기계학회 2014 대한기계학회 춘추학술대회 Vol.2014 No.4-4

VIDEO 신호처리용 VLSI FIR Filter 구현 방법의 비교 ( A Comparison of Implementation Methods for Video-Rate VLSI FIR Filter )

남승현,이종복,성원용 대한전자공학회 1991 대한전자공학회 학술대회 Vol.1991 No.1

MAC Video 신호의 보간을 위한 Programmable Poly-phase FIR Filter ( Programmable Poly-phase FIR Filter for Interpolation of MAC Video Signals )

남승현,성원용 대한전자공학회 1992 대한전자공학회 학술대회 Vol.1992 No.1

시간 연속성을 갖는 비음수 행렬 분해를 이용한 음질 개선

남승현,Nam, Seung-Hyon 한국음향학회 2015 韓國音響學會誌 Vol.34 No.3

본 논문은 시간 연속성을 갖는 비음수 행렬 분해(Nonnegative Matrix Factorization, NMF)를 이용하여 잡음에 열화된 음성 신호의 음질을 개선하는 문제를 다룬다. 음성과 잡음 신호는 포아송 분포로 모델되며, NMF의 기본 벡터와 이득 벡터는 감마 분포로 모델된다. 이득 벡터의 시간 연속성은 음질 개선에 중요한 영향을 미치는 것으로 알려져 있다. 본 논문에서 시간의 연속성은 이득 벡터를 감마-마르코프 연쇄(Gamma-Markov chain, GMC) 사전 분포로 모델함으로써 이루어진다. 실험 결과는 제안된 알고리즘이 잡음 신호의 시간 연속성을 효과적으로 모델하는 것을 보여준다. In this paper, speech enhancement using nonnegative matrix factorization with temporal continuity has been addressed. Speech and noise signals are modeled as Possion distributions, and basis vectors and gain vectors of NMF are modeled as Gamma distributions. Temporal continuity of the gain vector is known to be critical to the quality of enhanced speech signals. In this paper, temporal continiuty is implemented by adopting Gamma-Markov chain priors for noise gain vectors during the separation phase. Simulation results show that the Gamma-Markov chain models temporal continuity of noise signals and track changes in noise effectively.

객관적인 오디오 음질 평가 방식 연구 ( Objective Audio Quality Assessment )

남승현,최동준,채종석 대한전자공학회 1995 대한전자공학회 학술대회 Vol.1995 No.1

911 이후 무력사용에 관한의 변화

남승현 국방부군사편찬연구소 2006 군사 Vol.- No.61

This article explores the international law governing self-defence. Developments since the conclusion of World WarⅡ, such as the emergence of international terrorism and rogue states and the easier availability of weapons of mass destruction, have placed enormous strain on the bright line rules of the UN Charter system. Particulary, after 9⋅11 attack so many international law professor argue that more temporal imminence and more on the magnitude of potential harm and the probability of an attack. Among of them, professor John Yoo, further argues that the consensus academic view on self-defence-that force is justified only as a necessary response to an imminent attack. Firstly he criticizes the current UN Charter system's regulation of the use of force and describes challenges that have emerged during postwar period. He also criticizes current self-defence doctrine and argues that it must take into account threats that go beyond the great power conflicts that worried the creators of the UN Charter system. Working within the existing legal structure, it develops an approach that expands the concept of imminence to include the magnitude and probability of an attack. Finally he conclude by suggesting a different model for the use of force that maximize the stability of the international system. Like this, re-interpretation of international law very closely related to international system. It means that the standards of using force changing now, and will change more than before. In this situation, I argue that we must know about international-law exactly and also know about changeable situation.

MPEG 오디오용 심리음향모델의 비교 ( Comparison of Psychoacoustic Models for MPEG Audio )

남승현,어윤,박재홍 대한전자공학회 1997 대한전자공학회 학술대회 Vol.1997 No.1

순환 확률분포를 이용한 다중 음원 방향 추정

남승현,김용호,Nam, Seung-Hyon,Kim, Yong-Hoh 한국음향학회 2011 韓國音響學會誌 Vol.30 No.6

본 논문에서는 주기성을 갖는 순환 확률분포를 이용하여 $0^{\circ}{\sim}360^{\circ}$ 범위의 다중 음원의 방향을 추정하는 기법을 제안한다. 음원의 방향 정보를 담고 있는 마이크로폰간의 위상차는 확률분포의 혼합물로 간주될 수 있으며, 음원 방향은 이 확률분포의 혼합물에 적용된 로그-우도함수 (log-likelihood function)를 최대화함으로써 추정된다. 주기성을 갖는 데이터의 분석에 von Mises 확률분포가 널리 활용된다는 사실은 잘 알려져 있지만, 본 논문에서는 기존의 Gaussian이나 Laplacian 확률분포에 $2{\pi}$ 모듈로 (modulo) 연산을 적용함으로써 $0^{\circ}{\sim}360^{\circ}$ 범위의 주기성을 갖는 순환 확률분포를 정의하고 이를 방향 추정에 활용한다. 순환 확률분포의 혼합물에 대한 로그-우도함수를 최대가 되게 하는 음원의 방향은 EM (Expectation-Maximization) 알고리즘을 이용하여 추정된다. 다양한 반향 환경에서의 실험 결과 Laplacian 확률분포가 von Mises나 Gaussian 확률분포보다 우수한 성능을 제공함을 확인할 수 있다. This paper presents techniques for estimating directions of multiple sound sources ranging from $0^{\circ}$ to $360^{\circ}$ using circular probability distributions having a periodic property. Phase differences containing direction information of sources can be modeled as mixtures of multiple probability distributions and source directions can be estimated by maximizing log-likelihood functions. Although the von Mises distribution is widely used for analyzing this kind of periodic data, we define a new class of circular probability distributions from Gaussian and Laplacian distributions by adopting a modulo operation to have $2{\pi}$-periodicity. Direction estimation with these circular probability distributions is done by implementing corresponding EM (Expectation-Maximization) algorithms. Simulation results in various reverberant environments confirm that Laplacian distribution provides better performance than von Mises and Gaussian distributions.

INNOVATIVE CONCEPT FOR AN ULTRA-SMALL NUCLEAR THERMAL ROCKET UTILIZING A NEW MODERATED REACTOR

남승현,PAOLO VENNERI,김용희,이정익,장순흥,정용훈 한국원자력학회 2015 Nuclear Engineering and Technology Vol.47 No.6

Although the harsh space environment imposes many severe challenges to space pioneers,space exploration is a realistic and profitable goal for long-term humanity survival. One ofthe viable and promising options to overcome the harsh environment of space is nuclearpropulsion. Particularly, the Nuclear Thermal Rocket (NTR) is a leading candidate for neartermhuman missions to Mars and beyond due to its relatively high thrust and efficiency. Traditional NTR designs use typically high power reactors with fast or epithermal neutronspectrums to simplify core design and to maximize thrust. In parallel there are a series ofnew NTR designs with lower thrust and higher efficiency, designed to enhance missionversatility and safety through the use of redundant engines (when used in a clusteredengine arrangement) for future commercialization. This paper proposes a new NTR designof the second design philosophy, Korea Advanced NUclear Thermal Engine Rocket(KANUTER), for future space applications. The KANUTER consists of an Extremely HighTemperature Gas cooled Reactor (EHTGR) utilizing hydrogen propellant, a propulsion system,and an optional electricity generation system to provide propulsion as well as electricitygeneration. The innovatively small engine has the characteristics of high efficiency,being compact and lightweight, and bimodal capability. The notable characteristics resultfrom the moderated EHTGR design, uniquely utilizing the integrated fuel element with anultra heat-resistant carbide fuel, an efficient metal hydride moderator, protectively coolingchannels and an individual pressure tube in an all-in-one package. The EHTGR can bebimodally operated in a propulsion mode of 100 MWth and an electricity generation modeof 100 kWth, equipped with a dynamic energy conversion system. To investigate the designfeatures of the new reactor and to estimate referential engine performance, a preliminarydesign study in terms of neutronics and thermohydraulics was carried out. The resultindicates that the innovative design has great potential for high propellant efficiency andthrust-to-weight of engine ratio, compared with the existing NTR designs. However, thebuild-up of fission products in fuel has a significant impact on the bimodal operation of the moderated reactor such as xenon-induced dead time. This issue can be overcome bybuilding in excess reactivity and control margin for the reactor design.