The Environment of the Binary Neutron Star Merger GW170817

Levan, A. J.,Lyman, J. D.,Tanvir, N. R.,Hjorth, J.,Mandel, I.,Stanway, E. R.,Steeghs, D.,Fruchter, A. S.,Troja, E.,Schrøder, S. L.,Wiersema, K.,Bruun, S. H.,Cano, Z.,Cenko, S. B.,Postigo, A. de Ugarte American Astronomical Society 2017 ASTROPHYSICAL JOURNAL LETTERS - Vol.848 No.2

Gamma-Ray Burst Progenitors

Levan, A.,Crowther, P.,Grijs, R.,Langer, N.,Xu, D.,Yoon, S. C. D. Reidel Pub. Co 2016 Space science reviews Vol.202 No.1

<P>We review our current understanding of the progenitors of both long and short duration gamma-ray bursts (GRBs). Constraints can be derived from multiple directions, and we use three distinct strands; (i) direct observations of GRBs and their host galaxies, (ii) parameters derived from modelling, both via population synthesis and direct numerical simulation and (iii) our understanding of plausible analog progenitor systems observed in the local Universe. From these joint constraints, we describe the likely routes that can drive massive stars to the creation of long GRBs, and our best estimates of the scenarios that can create compact object binaries which will ultimately form short GRBs, as well as the associated rates of both long and short GRBs. We further discuss how different the progenitors may be in the case of black hole engine or millisecond-magnetar models for the production of GRBs, and how central engines may provide a unifying theme between many classes of extremely luminous transient, from luminous and super-luminous supernovae to long and short GRBs.</P>

Engineering Geological and Geotechnical Investigation of Landslide in Region of Zvare, Central Georgia, Alongside to New Railway Line

( Levan Maisuradze ),( Vasilios Marinos ),( Nikolaos Kazilis ) 대한지질공학회 2019 대한지질공학회 학술발표회논문집 Vol.2019 No.2

The current study deals with slope instability at the wider area of Zvare village, of Imereti region, central Georgia, central Caucasus, adjacent to railroad alignment. Conceptual engineering geological model was created in order understand better the behavior of the ground, so investigations in terms of Surface geological mapping, drilling and boring, laboratory tests and geotechnical monitoring was carried out. The landslide, of approximately 400m length and 230m wide, was activated at 13/05/2017 at the above mentioned region, due to excavations, which were carried out at the toe of old stabilized landslide, for the construction of railroad line. The mentioned landslide, although constitutes a complex system of minor landslides, generally is classified as a rotational andslide. Displacements approach 16m in lateral direction and 7m in vertical, respectively. The maximum depth of shearing due to boring and instrumentation, is estimated at depth of 40m, which through to back analysis shown shear strength of shear surface, expressed as Mohr Coulomb shear parameters, cohesion c=0 and friction angle φ=10°. This failure provides several geotechnical and social related problems. These deal with the safe construction and maintnanance of the new railway line, the maintenance of the river and the road. In addition, one main issue is the maintenance of the springs of natural carbonated water, which are also located at the left bank of the river. The area of springs is considered protected area.

순환적 폭로가 내화처리 합판의 기계적 성질에 미치는 영향

김종만,Levan, Susan L 한국목재공학회 1990 목재공학 Vol.18 No.1

合板에 耐水藥劑를 加壓法에 의하여 약 1,588㎏/(30㎝)³ (3.51bs/ft³)을 주입시켜 耐火合板을 製造한 後, 이들 合板의 含水率을 6%로 유지하면서, 기간은 0, 21, 60, 160 및 215일 동안 온도를 26.6℃ (80。F)에서 7시간, 26.6℃로 내리는데 1시간, 65℃로 올리는데 2시간씩으로 순환시켜, 耐火處理合板과 無處理合板의 기계적 성질에 미치는 영향을 조사 비교 하였다. MOE는 耐火處理合板과 無處理合板 사이에 유의성이 없었고, MOR에 있어서 耐火處理合板은 無處理合板에 비하여 15∼20% 감소하였고, WML에 있어서 耐火處理合板과 無處理合板 사이에 유의성이 있었으며, 두 耐火處理合板 사이에도 시간에 따라 유의성이 인정되었다. 따라서 WML은 耐火處理合板의 기계적 성질을 구명하는데 좋은 기준이 될 것으로 사료된다.

BIISOMETRIC OPERATORS AND BIORTHOGONAL SEQUENCES

Kubrusly, Carlos,Levan, Nhan Korean Mathematical Society 2019 대한수학회보 Vol.56 No.3

It is shown that a pair of Hilbert space operators V and W such that $V^*W=I$ (called a biisometric pair) shares some common properties with unilateral shifts when orthonormal bases are replaced with biorthogonal sequences, and it is also shown how such a pair of biisometric operators yields a pair of biorthogonal sequences which are shifted by them. These are applied to a class of Laguerre operators on $L^2[0,{\infty})$.

Early Intervention Programs Utilizing Parents as Treatment Providers for Their Low-birth-weight, Premature Infants

Nam, Sang Seok,Lim, Levan,Kwan, Celina Khuan Dai 한국특수아동학회 2002 특수아동교육연구 Vol.4 No.2

이 논문은 부모중재를 활용한 저체중 유아, 미성숙 유아를 위한 조기중재 프로그램에 대한 실험연구들을 분석하였다. 3유형의 조기중재 프로그램에 대한 효과를 조사하는데 25개의 연구결과들에 대한 메타분석과 상관분석이 이루어졌다. 유아 발달 중재, 부모-유아 상호작용 중재, 혼합중재가 그것이다. 유아발달중재 프로그램이 효과크기 면에서 가장 높았고, 부모-유아 상호작용 중재 프로그램이 뒤를 따랐으며, 혼합중재 프로그램의 효과 크기는 가장 적었다. 메타분석 결과들은 중재 프로그램의 유형이 결과에 형태에 영향을 미칠 수 있음을 암시한다. 상관분석은 출생시 체중과 전체 결과간에 전체적으로 부적 관계를 나타내었다(r=-.72, p<.05). 그리고 중재기간과 결과간에는 유의미한 상관이 없었다. This article reviewed experimental studies of early intervention programs that included parents as treatment providers for their premature and low-birth-weight infants. Meta-analysis and correlational analyses of the results of 25 studies were employed to examine the effects of three types of early intervention programs: (a) infant developmental intervention, (b) parent-infant interaction intervention, and (c) combined intervention. Infant developmental intervention programs produced the highest average effect size, followed by parent-child interaction intervention programs, and combined intervention programs achieved the least effects. The meta-analysis results indicate that the type of intervention programs can influence the type of outcomes produced. Correlational analyses found an overall negative relationship between birth weight and overall outcomes (r=-.72, p<.05) and no significant correlation between treatment duration and outcomes.

APPLICATIONS OF HILBERT SPACE DISSIPATIVE NORM

Carlos S. Kubrusly,Nhan Levan 대한수학회 2012 대한수학회보 Vol.49 No.1

The concept of Hilbert space dissipative norm was introduced in [8] to obtain necessary and sufficient conditions for exponential stabil-ity of contraction semigroups. In the present paper we show that the same concept can also be used to derive further properties of contraction semigroups, as well as to characterize strongly stable semigroups that are not exponentially stable.

피마자유를 이용한 초박층 덧씌우기용 바이오 폴리머 콘크리트의 역학적 특성 평가

박희문,최지영,김태우,안영준,LEVAN PHUC 한국도로학회 2013 한국도로학회논문집 Vol.15 No.2

PURPOSES: The objective of this study is to evaluate the mechanical characteristics of castor oil based bio-polymer concrete for use of ultra thin overlays. METHODS: To evaluate the mechanical properties of bio-polymer concrete, the various laboratory tests including compressive, tensile, and flexural strength, and elongation tests were conducted on bio-polymer concrete specimens in this study. The mechanical characteristics of biopolymer concretes were examined by changing the content of hardener and polymer binder to determine the optimum content for ultra-thin overlays. The bio-polymer concrete developed in this study was used for field trial test of the ultra-thin bridge deck pavement for verifying the workability and monitoring the long-term performance of materials. RESULTS : Test results showed that tensile and the flexural strength of bio-polymer concretes increase and the elongation of bio-polymer concrete decreases with increase of binder content. A field adhesive strength tests conducted on bridge deck pavement indicates the biopolymer concrete has more than 2MPa of adhesive strength satisfy with the design criteria. CONCLUSIONS: The bio-polymer concrete with more than 20% content of castor oil was developed for ultra-thin overlays in this study. It is found from this study that the 35% of hardener content is most appropriate for maintaining the strength characteristics and flexibility.

APPLICATIONS OF HILBERT SPACE DISSIPATIVE NORM

Kubrusly, Carlos S.,Levan, Nhan Korean Mathematical Society 2012 대한수학회보 Vol.49 No.1

The concept of Hilbert space dissipative norm was introduced in [8] to obtain necessary and sufficient conditions for exponential stability of contraction semigroups. In the present paper we show that the same concept can also be used to derive further properties of contraction semigroups, as well as to characterize strongly stable semigroups that are not exponentially stable.

ERRATUM/ADDENDUM TO "BIISOMETRIC OPERATORS AND BIORTHOGONAL SEQUENCES" [BULL. KOREAN MATH. SOC. 56 (2019), NO. 3, PP. 585-596]

Carlos Kubrusly,Nhan Levan Korean Mathematical Society 2023 대한수학회보 Vol.60 No.3

Erratum/Addendum to the paper "Biisometric operators and biorthogonal sequences" [Bull. Korean Math. Soc. 56 (2019), No. 3, pp. 585-596].