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Chiral Symmetry Breaking and Deracemization of Sodium Chlorate in Turbulent Flow
Ahn, Jaekyu,Kim, Do Hyun,Coquerel, Gerard,Kim, Woo-Sik The American Chemical Society 2018 CRYSTAL GROWTH AND DESIGN Vol.18 No.1
<P>The chiral symmetry breaking and deracemization of sodium chlorate were investigated when varying the agitation speed and cooling rate in cooling crystallization. At a low agitation speed, almost zero crystal enantiomeric excess occurred at the induction period. When increasing the agitation speed, the crystal enantiomeric excess at the induction period (called the “initial CEE”) increased due to the promotion of chiral symmetry breaking. The chiral symmetry breaking at the induction period (called the “initial chiral symmetry breaking”) also varied with the cooling rate. At a low cooling rate of 0.0738 °C/min, the initial CEE reached up to about 90% and was rapidly reduced when increasing the cooling rate. The experiments also showed enhanced deracemization of the chiral crystals when increasing the initial CEE. Thus, complete deracemization was achieved when the initial CEE was over 60%. The influence of the agitation speed and cooling rate on the initial CEE originated from secondary nucleation depending on the supersaturation at the induction period (called the “induction supersaturation”). Using a nucleation rate equation, the initial CEE was found to correlate well with the induction supersaturation. Also, varying the final setting temperature and agitator confirmed that secondary nucleation was significantly involved in the chiral symmetry breaking at the induction period.</P><P>The chiral symmetry breaking in the induction period was caused by the secondary nucleation in the crystallization. The secondary nucleation in the induction period was predominantly controlled by the turbulent flow supersaturation. The supersaturation in the induction was markedly dependent on the agitation speed and cooling rate in the crystallization.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cgdefu/2018/cgdefu.2018.18.issue-1/acs.cgd.7b01247/production/images/medium/cg-2017-01247b_0012.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cg7b01247'>ACS Electronic Supporting Info</A></P>
H.264/AVC에서 3차원 변환에 기반을 둔 효율적인 동영상 압축 방법
조재규(Jaekyu Jo),조혜정(Hye-Jeong Cho),이진호(Jinho Lee),정세윤(Seyoon Jeong),안창범(Changbeom Ahn),오승준(Seoungjun Oh) 한국방송·미디어공학회 2010 방송공학회논문지 Vol.15 No.3
In this paper, we propose 3DTE(3-Dimensional Transform Environment) that is based on 3DT(Dimensional Transform) that performs 2-dimensional integer DCT(Discrete Cosine Transform) based on 4x4 block and 1-dimensional integer DCT based on 4x1 block after collecting same frequency coefficients in neighboring 4x4 block and supports it's additional coding tools for high performance. The transform of 3DT can keep prediction error by using 4x4 block and reduce spatial redundancy additionally. The proposed 3DTE can provide coding tools to improve the coding efficiency with using 3DT. The performance of 3DTE compared to JM11.0 is average 3.58% and 5.40% bit savings for all test sequences and HD sequences, respectively, with keeping subjective video quality in High profile.
Two-module robotic pipe inspection system with EMATs
이진혁,김대현,문형필,한상철,Jaekyu Ahn 국제구조공학회 2014 Smart Structures and Systems, An International Jou Vol.13 No.6
This work introduces a two-module robotic pipe inspection system with ultrasonic NDE device to evaluate the integrity of pipe structures. The proposed robotic platform has high mobility. The two module mobile robot platform overcomes pipe obstacle structures such as elbow, or T-branch joints by cooperative maneuvers. Also, it can climb up the straight pipeline at a fast speed due to the wheel driven mechanism. For inspection of pipe structure, SH-waves generated by EMAT are applied with additional signal processing methods. A wavelet transform is implemented to extract a meaningful and specific signal from the superposed SH-wave signals. Intensity ratio which is normalized the defect signals intensity by the maximum intensity of directly transmitted signals in the wavelet transforms spectrum is applied to evaluate defects quantitatively. It is experimentally verified that the robotic ultrasonic inspection system with EMAT is capable of non-destructive inspection and evaluation of defects in pipe structure successfully by applying signal processing method based on wavelet transform.
Two-module robotic pipe inspection system with EMATs
Lee, Jin-Hyuk,Han, Sangchul,Ahn, Jaekyu,Kim, Dae-Hyun,Moon, Hyungpil Techno-Press 2014 Smart Structures and Systems, An International Jou Vol.13 No.6
This work introduces a two-module robotic pipe inspection system with ultrasonic NDE device to evaluate the integrity of pipe structures. The proposed robotic platform has high mobility. The two module mobile robot platform overcomes pipe obstacle structures such as elbow, or T-branch joints by cooperative maneuvers. Also, it can climb up the straight pipeline at a fast speed due to the wheel driven mechanism. For inspection of pipe structure, SH-waves generated by EMAT are applied with additional signal processing methods. A wavelet transform is implemented to extract a meaningful and specific signal from the superposed SH-wave signals. Intensity ratio which is normalized the defect signals intensity by the maximum intensity of directly transmitted signals in the wavelet transforms spectrum is applied to evaluate defects quantitatively. It is experimentally verified that the robotic ultrasonic inspection system with EMAT is capable of non-destructive inspection and evaluation of defects in pipe structure successfully by applying signal processing method based on wavelet transform.