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Magnetic Resonance Imaging with Intermolecular Double Quantum Coherences
Ahn, Sang-Doo Korean Magnetic Resonance Society 2004 Journal of the Korean Magnetic Resonance Society Vol.8 No.2
Recently a new method for magnetic resonance imaging based on the detection of relatively strong signal from intermolecular multiple quantum coherences (iMQCs) is reported. Such a signal would not be observable in the conventional framework of magnetic resonance; it originates in long-range dipolar couplings that are traditionally ignored. In this paper, we present the results of experimental studies to assess the feasibility of intermolecular double quantum coherences (iDQCs) imaging in humans. We show that the iDQC images are readily observable at 4T and that they do indeed provide different contrast than appears in conventional images.
Ahn, Sang Hee,Chung, Kwangzoo,Shin, Jung Wook,Cheon, Wonjoong,Han, Youngyih,Park, Hee Chul,Choi, Doo Ho Institute of Physics in association with the Ameri 2017 Physics in medicine & biology Vol. No.
<P>Gold nanoparticles (GNPs) injected in a body for dose enhancement in radiation therapy are known to form clusters. We investigated the dependence of dose enhancement on the GNP morphology using Monte-Carlo simulations and compared the model predictions with experimental data. The cluster morphology was approximated as a body-centred cubic (BCC) structure by placing GNPs at the 8 corners and the centre of a cube with an edge length of 0.22–1.03 <I>µ</I>m in a 4 × 4 × 4 <I>µ</I>m<SUP>3</SUP> water-filled phantom. We computed the dose enhancement ratio (DER) for 50 and 260 kVp photons as a function of the distance from the cube centre for 12 different cube sizes. A 10 nm-wide concentric shell shaped detector was placed up to 100 nm away from a GNP at the cube centre. For model validation, simulations based on BCC and nanoparticle random distribution (NRD) models were performed using parameters that corresponded to the experimental conditions, which measured increases in the relative biological effect due to GNPs. We employed the linear quadratic model to compute cell surviving fraction (SF) and sensitizer enhancement ratio (SER). The DER is inversely proportional to the distance to the GNPs. The largest DERs were 1.97 and 1.80 for 50 kVp and 260 kVp photons, respectively. The SF predicted by the BCC model agreed with the experimental value within 10%, up to a 5 Gy dose, while the NRD model showed a deviation larger than 10%. The SERs were 1.21 ± 0.13, 1.16 ± 0.11, and 1.08 ± 0.11 according to the experiment, BCC, and NRD models, respectively. We most accurately predicted the GNP radiosensitization effect using the BCC approximation and suggest that the BCC model is effective for use in nanoparticle dosimetry.</P>
A New 1/4 Rate Modulation Techniques for Enhanced-xVSB System
Sung-Hoon Kim,Jae-Young Lee,Seung-Won Kim,Sooin Lee,Ahn, C.,Ki-Doo Kim IEEE 2007 IEEE transactions on broadcasting Vol.53 No.2
<P>In this paper, we describe a new 1/4 rate robust modulation techniques for Enhanced-xVSB system which is fully backward compatible with ATSC 8-VSB standard. 1/4 rate mode Enhanced-xVSB system provides broadcasters with a wide choice of trade-offs of data rate vs amount of robustness of enhanced data for pedestrian/mobile services. Lab test results of proposed Enhanced-xVSB 1/4 rate mode robust stream is a significantly improved multipath as well as AWGN reception performance for Enhanced-xVSB receiver. We suggest an Enhanced-xVSB terrestrial broadcasting system for ATSC HDTV and pedestrian/portable TV simultaneous broadcasting service providing</P>
Merging of KOMPSAT-1 EOC Image and MODIS Images to Survey Reclaimed Land
Ahn, Ki-Won,Shin, Seok-Hyo,Kim, Sang-Cheol,Seo, Doo-Chun Korean Society of Surveying 2003 Korean journal of geomatics Vol.3 No.1
The merging of different scales or multi-sensor image data is becoming a widely used procedure of the complementary nature of various data sets. Ideally, the merging method should not distort the characteristics of the high-spatial and high-spectral resolution data used. To present an effective merging method for survey of reclaimed land using the high-resolution (6.6 m) Electro-Optical Camera (EOC) panchromatic image of the first Korea Multi-Purpose Satellite 1 (KOMPSA T-l) and the multispectral Moderate Resolution Imaging Spectroradiometer (MODIS) image data, this paper compares the results of Intensity Hue Saturation (IHS) and Principal Component Analysis (PCA) methods. The comparison is made by statistical and visual evaluation of three-color combination images of IHS and PCA results based on spatial and spectral characteristics. The use of MODIS bands 1, 2, and 3 with a contrast stretched EOC panchromatic image as a substitute for intensity was found to be particularly effective in this study.
Biped Walking of a Humanoid Robot for Argentina Tango
Doo-Sung Ahn 유공압건설기계학회 2016 드라이브·컨트롤 Vol.13 No.4
The mechanical design for biped walking of a humanoid robot doing the Argentina Tango is presented in this paper. Biped walking has long been studied in the area of robotic locomotion. The aim of this paper is to implement an Argentina Tango dancer-like walking motion with a humanoid robot by using a trajectory generation scheme. To that end, this paper uses blending polynominals whose parameters are determined based on PSO (Particle Swarm Optimization) according to conditions that make the most of the Argentina Tango’s characteristics. For the stability of biped walking, the ZMP (Zero Moment Point) control method is used. The feasibility of the proposed scheme is evaluated by simulating biped walking with the 3D Simscape robot model. The simulation results show the validity and effectiveness of the proposed method.
Sung Yong Kim,Young Jin Lee,Mi Na Jang,Chun Geun Kwon,Byung Doo Lee,He Young Ahn 위기관리 이론과 실천 2017 Crisisonomy Vol.13 No.4
본 연구에서는 강원지방에 분포하는 소나무와 잣나무를 대상으로 지표층 및 수관층 연료의 특성을 파악하고 수관화 전이 및 확산 위험성을 비교·분석 하였다. 지표층 연료를 수종별로 채취하였으며, 수종별 16개의 표본목을 벌채하여 수관층 연료특성을 분석하였다. 본 연구결과에 의하면, 지표층 수분함량은 잣나무가 높았으나, 수관층 수분함량은 두 수종 간 유사하게 나타났다. 수관층 잎의 비율은 잣나무(34.4%)가 소나무(25.7%)에 비해 많이 분포하였고, 연소 가능한 연료는 소나무 55.8%, 잣나무 55.6%의 비율로 유사하였다. 수관층 연료 추정식의 조정결정계수(R 2 adj )는 모든 수관 부위에서 0.850 이상으로 나타났다. 임분 단위 수관연료특성에서는 잣나무의 수관체적 공간이 소나무보다 적었지만, 그 안에 포함된 연료량이 많아 총 수관연료밀도는 약 1.56배, 연소가능한 수관연료밀도는약 1.68배 높은 결과가 나타났다. This study identified fuel characteristics of surface and crown and analyzed crown fires on Pinus densiflora and Pinus koraiensis stands in Gangwon Province in Korea. Fifteen surface fuels of each tree type were sampled and 16 trees of each species were destructively sampled to identify crown fuel characteristics. Pinus koraiensis has higher surface fuel moisture content due to the difference in crown cover, although the two types show similar crown fuel moisture content. Pinus koraiensis (34.4%) has more crown needles than Pinus densiflora (25.7%), but two species have similar combustible of available fuel, 55.8% and 55.6%, respectively. The adjusted coefficients of determination(R 2 adj ) values were high (more than 0.850) in all crown fuel classes. The canopy bulk density of Pinus koraiensis was 1.56 times higher than that of Pinus densiflora, whereas the available canopy bulk density of Pinus koraiensis was 1.68 times higher despite the smaller canopy volume.
Ahn, Doo-Sik,Kim, So-Yeon,Lim, Goo-Il,Lee, Sungyul,Choi, Young S.,Kim, Sang Kyu WILEY-VCH Verlag 2010 Angewandte Chemie Vol.122 No.7
<B>Graphic Abstract</B> <P>Licht, Spektrometer, Action: Fano- Resonanzen liefern detaillierte Informationen über die Potentialfläche in der Nähe des Übergangszustands bei der Photodissoziation von Diazirin im S<SUB>1</SUB>-Zustand. Die Anregung entlang der asymmetrischen C-N-Streckschwingungsmode beschleunigt die Ringöffnung; folglich scheinen die beiden C-N-Bindungen von angeregtem Diazirin nacheinander aufzubrechen (siehe Schema). <img src='wiley_img/00448249-2010-122-7-ANGE200905619-content.gif' alt='wiley_img/00448249-2010-122-7-ANGE200905619-content'> </P>
Ahn, Doo-Sik,Kim, So-Yeon,Lim, Goo-Il,Lee, Sungyul,Choi, Young S.,Kim, Sang Kyu WILEY-VCH Verlag 2010 Angewandte Chemie Vol.49 No.7
<B>Graphic Abstract</B> <P>Lights, spectrometer, action: Crucial information about the detailed shape of the potential-energy surface in the vicinity of the transition state is obtained from the Fano resonances in the photodissociation cross-section of diazirine in the S<SUB>1</SUB> state. The excitation along the asymmetric C&n.bond;N stretching mode accelerates the ring-opening reaction, suggesting that two C&n.bond;N bonds of the excited diazirine break in a stepwise manner (see scheme). <img src='wiley_img_2010/14337851-2010-49-7-ANIE200905619-content.gif' alt='wiley_img_2010/14337851-2010-49-7-ANIE200905619-content'> </P>