다차원 특징 및 가중블록 투표방식을 이용한 얼굴 인식 성능 향상 기법

장재윤(Jae-Yoon Jang),윤호섭(Ho-Sub Yoon) 대한전자공학회 2015 대한전자공학회 학술대회 Vol.2015 No.6

This paper proposes novel block voting measure for improving user face recognition system performance. In order to exploit sample’s global and local characteristic, We use various feature and make large dimension feature by concatenation. After then, compare gallery set with probe image. In this step, we divide feature into some block, and recognize each block using cosine similarity. And we obtain probe image class using weighted voting which calculated by block recognition result. This proposed method has advantage that is robustness for noise or outlier data. Because this method depend on the number of sub-block, if enough sub-blocks are guaranteed, it can make improved performance on face recognition system.

셀룰로스계 혼화제를 사용한 수중불분리성 콘크리트의 최적 배합

진치섭,엄장섭,박현재,윤재환 부산대학교 생산기술연구소 2001 生産技術硏究所論文集 Vol.60 No.-

수중불분리성 콘크리트는 통상적인 수중 콘크리트와는 개념부터 다르다. 콘크리트에 수중불분리성 혼화제를 혼합하면 콘크리트의 점성이 증가되고 수중에서의 재료분리에 대한 저항성이 현저히 증가된다. 이 효과는 수중콘크리트 자체의 신뢰성을 높여줄 뿐만 아니라 타설지역의 환경보존에도 현저한 기여를 하게 된다. 본 연구에서는 셀룰로스계 수중불분리성 혼화제 (수용성 셀룰로스 에틸계)와 고유동화제 (고축합 트리아진계)의 첨가량 변화에 따른 수중불분리성 콘크리트의 제반 물성 변화를 검토하고 비교적 정온 상태의 해상 환경에 적용할 수 있는 수중불분리성 콘크리트의 치적 배합을 결정하였다. Antiwashout underwater concrete is quite different in concept from conventional underwater concrete. By mixing an antiwashout admixture with concrete, the viscosity of the concrete is increased and its resistance to segregation under the washing action of water is enhanced. The effect of this is not only to greatly improve the reliability of concrete placed under water, but it also has remarkable effects on environmental preservation in the construction area. In this study, property tests of antiwashovt underwater concrete have been carried out, as variable add of special admixture, i.e antiwashout underwater agent (Hydroxy Ethyl Cellulose), superplasticizer (High condensate Tri - Azine). We made the antiwashout underwater concrete have enough strength to endure with easy construction. And we have decided the optimal mix proportion far antiwashout underwater concrete under standard state.

개인방사선피폭선량평가

이형섭,김장렬,윤석철,이상윤 대한방사선 방어학회 1994 방사선방어학회지 Vol.19 No.2

최근, 개인방사선피폭선량평가에 관한 기술기준이 과학기술처에 의해 고시됨에 따라 국내에서도 개인선량계를 이용한 체외피폭선량평가결과의 신뢰성 문제가 크게 대두되고 있다. 한국원자력연구소에서는 이러한 구내의 상황을 인식하고 자체적인 신뢰성 확보를 위해 미국의 Oak Ridge국립연구소의 주관하에 개인피폭선량의 평가에 관한 국제상호비교검증시험(Personnel Dosimetry Intercomparison Study ; PDIS) 을 수행하였다. 비교 검증시험에는 한국원자력연구소에서 사용하고 있는 Teledyne PB-3 열형광선량계가 사용되였으며 선량게산 알고리즘은 Teledyne PB-3 version1.5-1989를 사용하였다. 본 연구에서는 지금까지 실시된 PDIS의 결과를 요약하고 현재 PB-3 시스템의 개인선량평가성능에 대해 고찰하였으며, 선량평가절차에 대한 문제점 도출을 통하여 직업적 방사선피폭선량 평가능력의 향상을 위한 방안을 제시하였다. Recently, the Ministry of Science and Technology issued a Ministerial Ordinance (N0 1992-15) about the technical criteria on personnel radiation dosimetry. In today's climate, it is important to demonstrate and document that the processor's systems and services to others meet national standards of quality. The purpose of this study is to verify the performance of the Teledyne PB-3 personnel dosimetry system that is generally used in Korea Atomic Energy Research Institute (KAERI) by intercomparison with Oak Ridge National Laboratory. The KAERI has been participated in this personnel dosimetry intercomparison study(PDIS) program since 1991 and it could be possible to test and calibrate personnel monitoring system. This report presents a summary and analysis of by about 50 does equivalent measurements reported for PDIS-16 through 18 (1991-1993) with emphasis on neutron does equivalent sensitivity, accuracy and methods to improve personnel dosimetry performance are also discussed.

Exceptional electrochemical performance of freestanding electrospun carbon nanofiber anodes containing ultrafine SnO_<i>x</i> particles

Zhang, Biao,Yu, Yang,Huang, Zhendong,He, Yan-Bing,Jang, Donghyuk,Yoon, Won-Sub,Mai, Yiu-Wing,Kang, Feiyu,Kim, Jang-Kyo The Royal Society of Chemistry 2012 ENERGY AND ENVIRONMENTAL SCIENCE Vol.5 No.12

<P>SnO<SUB><I>x</I></SUB>–carbon nanofiber (CNF) composites are synthesized using the electrospinning technique for use as freestanding electrodes in Li-ion batteries. The electrodes made from the composites carbonized at 750 °C (SnO<SUB><I>x</I></SUB>–CNF-750) with 14.5 wt% SnO<SUB><I>x</I></SUB> deliver a remarkable capacity of 674 mA h g<SUP>−1</SUP> after 100 cycles when discharged at 0.5 A g<SUP>−1</SUP>. This result is considered the highest among those reported in the literature for anodes made from similar electrospun carbon fibers containing SnO<SUB><I>x</I></SUB> nanoparticles. An increase in carbonization temperature to 950 °C (SnO<SUB><I>x</I></SUB>–CNF-950) results in a significant reduction of the particle content in the fiber due to aggregation of Sn to form nanoparticles external to the fibers, with concomitant degradation of capacities. The presence of amorphous SnO<SUB><I>x</I></SUB> particles at the atomic scale embedded in the conductive CNFs is thought to be responsible for the exceptional electrochemical performance of the SnO<SUB><I>x</I></SUB>–CNF-750 electrodes. These ultrafine particles facilitate the reaction Sn + <I>x</I>Li<SUB>2</SUB>O → SnO<SUB><I>x</I></SUB> + 2<I>x</I>Li<SUP>+</SUP> + 2<I>x</I>e<SUP>−</SUP>, making it highly reversible, which is confirmed by the growing peak currents with increasing scan rate indicated by cyclic voltammetry, and the absence of Sn–Sn bonds in the particles revealed by the extended X-ray absorption fine structure spectroscopy (EXAFS). Both the SnO<SUB><I>x</I></SUB> particle size and content in the fiber play important roles in controlling the rate and cyclic performance of the SnO<SUB><I>x</I></SUB>–CNF composite electrodes.</P> <P>Graphic Abstract</P><P>This paper presents novel SnO<SUB><I>x</I></SUB>–carbon nanofiber composites with embedded ultrafine SnO<SUB><I>x</I></SUB> particles. The composites deliver remarkable power/energy densities as well as excellent cyclic performance due to their high reversibility and stability. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c2ee23145j'> </P>

Deciphering the thermal behavior of lithium rich cathode material by <i>in situ</i> X-ray diffraction technique

Muhammad, Shoaib,Lee, Sangwoo,Kim, Hyunchul,Yoon, Jeongbae,Jang, Donghyuk,Yoon, Jaegu,Park, Jin-Hwan,Yoon, Won-Sub Elsevier 2015 Journal of Power Sources Vol.285 No.-

<P><B>Abstract</B></P> <P>Thermal stability is one of the critical requirements for commercial operation of high energy lithium-ion batteries. In this study, we use <I>in situ</I> X-ray diffraction technique to elucidate the thermal degradation mechanism of 0.5Li<SUB>2</SUB>MnO<SUB>3</SUB>-0.5LiNi<SUB>0.33</SUB>Co<SUB>0.33</SUB>Mn<SUB>0.33</SUB>O<SUB>2</SUB> lithium rich cathode material in the absence and presence of electrolyte to simulate the real life battery conditions and compare its thermal behavior with the commercial LiNi<SUB>0.33</SUB>Co<SUB>0.33</SUB>Mn<SUB>0.33</SUB>O<SUB>2</SUB> cathode material. We show that the thermal induced phase transformations in delithiated lithium rich cathode material are much more intense compared to similar single phase layered cathode material in the presence of electrolyte. The structural changes in both cathode materials with the temperature rise follow different trends in the absence and presence of electrolyte between 25 and 600 °C. Phase transitions are comparatively simple in the absence of electrolyte, the fully charged lithium rich cathode material demonstrates better thermal stability by maintaining its phase till 379 °C, and afterwards spinel structure is formed. In the presence of electrolyte, however, the spinel structure appears at 207 °C, subsequently it transforms to rock salt type cubic phase at 425 °C with additional metallic, metal fluoride, and metal carbonate phases.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Thermal degradation mechanism of lithium rich electrode material is investigated. </LI> <LI> In the absence of electrolyte, LMC shows better thermal stability compared to NMC. </LI> <LI> In the presence of electrolyte, thermal decomposition of LMC is accelerated. </LI> <LI> Catalytic activity of electrolyte in thermal decomposition is electrode dependent. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Amorphous germanium oxide nanobubbles for lithium-ion battery anode

Lim, Seh-Yoon,Jang, Wonseok,Yun, Soyeong,Yoon, Won-Sub,Choi, Jae-Young,Whang, Dongmok Elsevier 2019 Materials research bulletin Vol.110 No.-

<P><B>Abstract</B></P> <P>Germanium (Ge) is a promising anode material for lithium-ion batteries (LIBs) due to its large theoretical specific capacity (1600 mA h g<SUP>−1</SUP>), high Li diffusivity and large intrinsic electrical conductivity. Despite these merits, its large volumetric change during lithiation/delithiation process and relatively high production cost make it difficult to use in commercial batteries. In this paper, we report a facile, easy to scale up, and environmentally friendly method to prepare an amorphous phase GeO<SUB>x</SUB> (x < 1) hollow composite at a hydrothermal condition using an aqueous precursor solution containing GeO<SUB>2</SUB> particles, and citric acid. The citric acid induces gas bubble templates and frameworks to improve the structural strain for Li<SUP>+</SUP> ion conduction during cycling. The resulting GeO<SUB>x</SUB>-C hallow composite anode shows enhanced cyclability with a reversible capacity of 930 mA h g<SUP>−1</SUP> after 100 cycles at a current density of 0.3 C.</P> <P><B>Highlights</B></P> <P> <UL> <LI> One-pot hydrothermal synthesis of the 3D bubble amorphous GeO<SUB>x</SUB> hollow composite. </LI> <LI> Control of the hollow shell thickness for optimized electrode performance. </LI> <LI> Bubble-templated nanoscale pores for effective accommodation of volume change during cycling process. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Comparison of the Binding Modes of [Ru(2,2'-bipyridine)₃]²⁺ and [Ru(2,2':6',2"-terpyridine)₂]²⁺ to Native DNA

Jang, Yoon-Jung,Lee, Hyun-Mee,Jang, Kyeung-Joo,Lee, Jae-Cheol,Kim, Seog-K.,Cho, Tae-Sub Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.5

The $[Ru(tpy)_2]Cl_2$ (tpy:2,2':6',2"-terpyridine) complex was synthesized and its structure was confirmed by $^1H$-NMR and elemental analysis. Its binding mode toward DNA was compared with the well-known $[Ru(bpy)_3]Cl_2$ (bpy:2,2-bipyridyl), using isotropic absorption, linear dichroism(LD) spectroscopy, and an energy minimization study. Compared to $[Ru(bpy)_3]^{2+}$, the $[Ru(tpy)_2]^{2+}$ complex exhibited very little change in its absorption pattern, especially in the MLCT band, upon binding to DNA. Furthermore, upon DNA binding, both Ru(II) complexes induced a decrease in the LD magnitude in the DNA absorption region. The $[Ru(tpy)_2]^{2+}$ complex produced a strong positive LD signal in the ligand absorption region, which is in contrast with the $[Ru(bpy)_3]^{2+}$ complex. Observed spectral properties led to the conclusion that the interaction between the ligands and DNA bases is negligible for the $[Ru(tpy)_2]^{2+}$ complex, although it formed an adduct with DNA. This conclusion implies that both complexes bind to the surface of DNA, most likely to negatively charged phosphate groups via a simple electrostatic interaction, thereby orienting to exhibit the LD signal. The energy minimization calculation also supported this conclusion.

Structural and Electrochemical Properties of Doped LiFe_0.48Mn_0.48Mg_0.04PO₄ as Cathode Material for Lithium ion Batteries

Jang, Donghyuk,Palanisamy, Kowsalya,Kim, Yunok,Yoon, Won-Sub The Korean Electrochemical Society 2013 Journal of electrochemical science and technology Vol.4 No.3

The electrochemical properties of Mg-doped $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ and pure $LiFe_{0.5}Mn_{0.5}PO_4$ olivine cathodes are examined and the lattice parameters are refined by Rietveld analysis. The calculated atomic parameters from the refinement show that $Mg^{2+}$ doping has a significant effect in the olivine $LiFeMnPO_4$ structure. The unit cell volume is 297.053(2) ${\AA}^3$ for pure $LiFe_{0.5}Mn_{0.5}PO_4$ and is decreased to 296.177(1) ${\AA}^3$ for Mg-doped $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ sample. The doping of $Mg^{2+}$ cation with atomic radius smaller than $Mn^{2+}$ and $Fe^{2+}$ ion induces longer Li-O bond length in $LiO_6$ octahedra of the olivine structure. The larger interstitial sites in $LiO_6$ octahedra facilitate the lithium ion migration and also enhance the diffusion kinetics of olivine cathode material. The $LiFe_{0.48}Mn_{0.48}Mg_{0.04}PO_4$ sample with larger Li-O bond length delivers higher discharge capacities and also notably increases the rate capability of the electrode.

Crystal Structure Changes of LiNi_0.5Co_0.2Mn_0.3O₂ Cathode Materials During the First Charge Investigated by in situ XRD

Lee, Sang-Woo,Jang, Dong-Hyuk,Yoon, Jeong-Bae,Cho, Yong-Hun,Lee, Yun-Sung,Kim, Do-Hoon,Kim, Woo-Seong,Yoon, Won-Sub The Korean Electrochemical Society 2012 Journal of electrochemical science and technology Vol.3 No.1

The structural changes of $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode material for lithium ion battery during the first charge was investigated in comparison with $Li_{1-x}Ni_{0.8}Co_{0.15}Al_{0.05}O_2$ using a synchrotron based in situ X-ray diffraction technique. The structural changes of these two cathode materials show similar trend during first charge: an expansion along the c-axis of the unit cell with contractions along the a- and b-axis during the early stage of charge and a major contraction along the c-axis with slight expansions along the a- and b-axis near the end of charge at high voltage limit. In $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode, however, the initial unit cell volume of H2 phase is bigger than that of H1 phase since the c-axis undergo large expansion while a- and b- axis shrink slightly. The change in the unit cell volume for $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ during charge is smaller than that of $Li_{1-x}Ni_{0.8}Co_{0.15}Al_{0.05}O_2$. This smaller change in unit cell volume may give the $Li_{1-x}Ni_{0.5}Co_{0.2}Mn_{0.3}O_2$ cathode material a better structural reversibility for a long cycling life.

Structural study of the coating effect on the thermal stability of charged MgO-coated LiNi0.8Co0.2O2 cathodes investigated by in situ XRD

Yoon, Won-Sub,Nam, Kyung-Wan,Jang, Donghyuk,Chung, Kyung Yoon,Hanson, Jonathan,Chen, Jin-Ming,Yang, Xiao-Qing Elsevier 2012 Journal of Power Sources Vol.217 No.-