• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1051-1054
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• 2013

Closo-carborane has been considered as an efficient boron-carrier for boron neutron capture therapy (BNCT) and an attractive surrogate of lipophilic phenyl or cyclohexyl ring in drug design. Despite a great number of carborane-containing ligands have been synthesized and evaluated, molecular modeling studies of carborane ligands with macromolecules have been rarely reported. We herein describe a facile docking and scoring-function strategy of 16 carborane ligands with an estrogen receptor by using the commercial Gaussian, Chem3D Pro and Discovery Studio (DS) computational programs. Docked poses of the carborane ligands in silico exhibited similar binding modes to that of the crystal ligand in the active site of estrogen receptor. Score analysis of the best docked pose for each ligand indicated that the Ligscore1 and the Dockscore have a moderate correlation with in vitro biological activity. This is the first report on the scoring-correlation studies of carborane ligands with macromolecules. The integrated Gaussian-DS approach has a potential application for virtual screening, De novo design, and optimization of carborane ligands in medicinal chemistry.

• Proceeding of EDISON Challenge
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• 2013.04a
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• pp.89-100
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• 2013

생물정보학의 다양한 이론적 내용과 계산적 방법들이 갈수록 전문화 되어짐에 따라 신약 개발, 신 물질 합성, 단백질의 구조 예측 등 다양한 분야에서 필요성이 커져가고 있다. 이 중 molecular docking 기술은 단백질과 특정 분자간의 결합 형태를 분자 모델링 기법을 통해 알아내는 방법이며 신약개발 연구에 큰 영향을 미치고 있다. Molecular docking을 통하여 분자간의 결합 형태를 예측하는 과정에서 Protein-ligand complex의 정확한 에너지 측정을 가능하게 하는 scoring function이 필요하다. 그런데 본 연구에서 사용한 B-Raf kinase protein 은 active site 부분에서 ligand와 receptor 간에 aromatic ring로 인한 ${\pi}-{\pi}$ interaction이 정확한 에너지 계산을 어렵게 한다. 이러한 ${\pi}-{\pi}$ interaction 부분의 에너지를 정확하게 계산하기 위해 양자역학 계산을 실시하였다. Active site 부분에서 ligand와 receptor에서 발생하는 각각 다른 5개의 ${\pi}-{\pi}$ interaction 구조를 준비하여 Gaussian을 통해 양자역학 에너지를 계산하였다. 그리고 이러한 결과 값들이 ligand의 활성 값과 어떤 상관관계를 갖는지 살펴보았다. 그 결과 ${\pi}-{\pi}$ interaction을 양자역학으로 계산한 값이 그렇지 않은 것보다 더 좋은 상관관계를 보여주었다. 이는 특별한 구조의 영향으로 ligand와 receptor 간의 결합에너지를 정확하게 계산하기 어려운 문제에서 양자역학을 적용할 경우 더욱 좋은 결과값을 얻을 수 있었다. 또한 이러한 데이터가 신 물질 개발이나 신약 개발 등의 다양한 분야에서 계산화학 방법이 신뢰성을 얻는데 도움 될 수 있다고 생각된다.

• Journal of the Optical Society of Korea
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• v.17 no.2
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• pp.177-181
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• 2013

We present an all-fiberized power-scalable, sub-nanosecond mode-locked laser based on a frequency-shifted-feedback ring cavity comprised of an erbium-doped fiber, a downshifting acousto-optic modulator (AOM), and a bandpass filter (BPF). With the aid of the frequency-shifted feedback mechanism provided by the AOM and the narrow filter bandwidth of 0.45 nm, we generate self-starting, mode-locked optical pulses with a spectral bandwidth of ~0.098 nm and a pulsewidth of 432 to 536 ps. In particular, the output power is readily scalable with pump power while keeping the temporal shape and spectral bandwidth. This is obtained via the consolidation of bound pulse modes circulating at the fundamental repetition rate of the cavity. In fact, the consolidated pulses form a single-entity envelope of asymmetric Gaussian shape where no discrete internal pulses are perceived. This result highlights that the inclusion of the narrow BPF into the cavity is crucial to achieving the consolidated pulses.

• Journal of the Institute of Convergence Signal Processing
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• v.10 no.3
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• pp.198-206
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• 2009

This paper presents the reduction of the positional uncertainty of an ultrasonic sensor ring with overlapped beam pattern for the efficient obstacle detection of a mobile robot. Basically, it is assumed that a relatively small number of inexpensive low directivity ultrasonic sensors are installed at regular spacings along the side of a circular mobile robot with their beams overlapped. First, for both single and double obstacles, we show that the positional uncertainty inherent to an ultrasonic sensor can be reduced using the overlapped beam pattern, and also quantify the relative improvement in positional uncertainty. Second, given measured distance data from one or two ultrasonic sensors, we devise the geometric method to determine the position of an obstacle with respect to the center of a mobile robot. Third, we examine and compare existing ultrasonic sensor models, including Gaussian distribution, parabolic distribution, uniform distribution, and impulse, and then build the sensor model of overlapped ultrasonic sensors, adequate for obstacle detection in terms of positional uncertainty and computational requirement. Finally, through experiments using our prototype ultrasonic sensor ring, the validity of overlapped beam pattern for reduced positional uncertainty and efficient obstacle detection is demonstrated.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.12
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• pp.2935-2944
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• 2000

Gas tungsten arc(GTA) welding is used to rrpiar the seat ring in swing type check valve in power plant because of its high weld quality. In order to automate the welding process, it is needed to analyze the process of inside pipe girth welding. In this study, the shapes of weld bead on pipe inside and outside were predicted and its validity was investigated. On the assumption that the welding arc had a bivariate gaussian distribution, analytical solution was derived to predict the temperature distribution in pipe weld using mapping under consideration of physical relationships. The size of weld bean could be predicted from this equation and its accuracy was verified by experiments.

• Proceedings of the IEEK Conference
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• 1999.11a
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• pp.368-371
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• 1999

In this paper, we propose a neural network processor architecture with on-chip learning and with reconfigurability according to the data dependencies of the algorithm applied. For the neural network model applied, the proposed architecture can be configured into either SIMD or SRA(Systolic Ring Array) without my changing of on-chip configuration so as to obtain a high throughput. However, changing of system configuration can be controlled by user program. To process activation function, which needs amount of cycles to get its value, we design it by using PWL(Piece-Wise Linear) function approximation method. This unit has only single latency and the processing ability of non-linear function such as sigmoid gaussian function etc. And we verified the processing mechanism with EBP(Error Back-Propagation) model.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.9
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• pp.1654-1665
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• 2008

This paper presents bit splitting methods to apply multilevel modulation to iterative codes such as turbo code, low density parity check code and turbo product code. Log-likelihood ratio method splits multilevel symbols to soft decision symbols using the received in-phase and quadrature component based on Gaussian approximation. However it is too complicate to calculate and to implement hardware due to exponential and logarithm calculation. Therefore this paper presents Euclidean, MAX, sector and center focusing method to reduce the high complexity of LLR method. Also, this paper proposes optimal soft symbol split method for three kind of iterative codes. Futhermore, 16-APSK modulator method with double ring structure for applying DVB-S2 system and 16-QAM modulator method with lattice structure for T-DMB system are also analyzed.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.2
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• pp.71.1-71.1
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• 2021

We perform disk-halo decomposition of the Large Magellanic Cloud (LMC) using a novel HI velocity field extraction method, aimed at better deriving its HI kinematics and thus mass distribution in the galaxy including both baryons and dark matter. We decompose all the line-of-sight velocity profiles of the combined HI data cube of the LMC, taken from the Australia Telescope Compact Array (ATCA) and Parkes radio telescopes with an optimal number of Gaussian components. For this, we use a novel tool, the so-called BAYGAUD which performs profile decomposition based on Bayesian MCMC techniques. From this, we disentangle turbulent non-ordered HI gas motions from the decomposed gas components, and produce an HI bulk velocity field which better follows the global circular rotation of the galaxy. From a 2D tilted-ring analysis of the HI bulk velocity field, we derive the rotation curve of the LMC after correcting for its transverse, nutation and precession motions. The dynamical contributions of baryons like stars and gaseous components which are derived using the Spitzer 3.6 micron image and the HI data are then subtracted from the total kinematics of the LMC. Here, we present the bulk HI rotation curve, the mass models of stars and gaseous components, and the resulting dark matter density profile of the LMC.

• Journal of The Korean Astronomical Society
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• v.34 no.1
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• pp.17-24
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• 2001

We have studied the central parts of M82, which is a well-known infrared luminous, starburst galaxy, by analyzing archival data from the Infrared Space Observatory (ISO). M82 was observed at 11 positions covering $\pm$45" from the center along the major axis. We analyzed 4 emission lines, [ArIII] 8.99 ${\mu}m$, $H_2$ 17.034 ${\mu}m$, [FeII] 25,98 ${\mu}m$, and [SiII] 34,815 ${\mu}m$ from $SWSO_2$ data. The integrated flux distributions of these lines are quite different. The $H_2$ line shows symmetric twin peaks at $\~$18" from the center, which is a general characteristic of molecular lines in starburst or barred galaxies. This line appears to be associated with the rotating molecular ring at around $\~$200 pc just outside the inner spiral arm. The relative depletion of the $H_2$ line at the center may be due to the active star formation activity which dissociates the $H_2$ molecules. The other lines have peaks at the center and the distributions are nearly symmetric. The line profiles are deconvolved assuming that both intrinsic and instrumental profiles are Gaussian. The velocity dispersion outside the core is found to be $\~50 km s^{-1}$. The central velocity dispersion is much higher than $50 km s^{-1}$, and different lines give different values. The large central velocity dispersion ($\sigma$) is mostly due to the rotation, but there is also evidence for a high $\sigma$ for [ArIII] line. We also generated position-velocity maps for these four lines. We found very diverse features from these maps.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4161-4164
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• 2012

Density functional MO calculations for the methylsilole anion of $[C_4H_4SiMe]^-$ and methylgermole anion of $[C_4H_4SiMe]^-$ at the B3LYP (full)/6-311+$G^*$ level (GAUSSIAN 94) were carried out and characterized by frequency analysis. The ground state structure for the methylsilole anion and methylgermole anion is that the methyl group is pyramidalized with highly localized structure. The difference between the calculated $C_{\alpha}-C_{\beta}$ and $C_{\beta}-C_{\beta}$ distances are 9.4 and 11.5 pm, respectively. The E-Me vector forms an angle of $67.9^{\circ}$ and $78.2^{\circ}$ with the $C_4E$ plane, respectively. The optimized structures of the saddle point state for the methylsilole anion and methylgermole anion have been also found as a planar with highly delocalized structure. The optimized $C_{\alpha}-C_{\beta}$ and $C_{\beta}-C_{\beta}$ distances are nearly equal for both cases. The methyl group is located in the plane of $C_4E$ ring and the angle between the E-Me vector and the $C_4E$ plane for the methylsilole anion and methylgermole anion is $2.0^{\circ}$ and $2.3^{\circ}$, respectively. The energy difference between the ground state structure and the transition state structure is only 5.1 kcal $mol^{-1}$ for the methylsilole anion. However, the energy difference of the methylgermole anion is 14.9 kcal $mol^{-1}$, which is much higher than that for the corresponding methylsilole monoanion by 9.8 kcal $mol^{-1}$. Based on MO calculations, we suggest that the head-to-tail dimer compound, 4, result from [2+2] cycloaddition of silicon-carbon double bond character in the highly delocalized transition state of 1. However, the inversion barrier for the methylgermole anion is too high to dimerize.