• Journal of the Korean Magnetic Resonance Society
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• v.9 no.1
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• pp.67-73
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• 2005

$^{27}AI$ triple quantum magic angle spinning (3QMAS) NMR spectra of several mordenite (MOR) sample were simulated with the point charge model method and compared with experimental 3QMAS spectra. Signal positions from different tetrahedral (T) sites in 3QMAS spectra are mainly governed by local structures of T sites such as T-O-T angles and T-O bond lengths. When preparation methods, cations in addition to Si/Al rations vary, the local structures of T sites in MOR change enough to alter signal patterns in 3QMAS of MOR. This inhibits to study the of Al distribution variation over 4 different T sites in mordenite during process such as dealumination by 3QMAS spectra.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.103-111
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• 2003

전자/통신기기에 대한 전자파 장해(EMl/EMS) 문제를 제품개발 기간 내에 완전하게 해결하기란 이론만큼 쉽지 않으며, 전자기적 적합성(EMC)에 대한 지식이 충분하지 못한 회로/기구 설계자들은 전자 파장해 문제를 반복적인 설계 수정 및 디버깅 작업으로 밖에 해결할 수 없는 골치 아픈 Black Magic으로 생각하고 있다. 그러나 분명히 전자기적 간섭(EMI) 문제도 이론 및 해석적인 접근으로 그 해답을 충분히 찾을 수가 있다, 본 고에서는 이러한 PCB Level에서의 전자파장해 문제를 해결하기 위한 체계적인 접근 방법과 오랜 현장 경험에서 나오는 EMC 전문가의 경험적인 지식을 통합한 인공 지능형 EMC 전문가 시스템에 대한 소개와 연구개발 동향 및 극복 과제 등에 대해서 기술하고자 한다.

• Journal of the Korean Magnetic Resonance Society
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• v.19 no.1
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• pp.29-35
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• 2015

The microscopic dynamics of $CsH_2PO_4$, with two distinct hydrogen bond lengths, are studied by static nuclear magnetic resonance (NMR) and magic angle spinning (MAS) NMR. The proton dynamics of the two crystallographically inequivalent hydrogen sites were discussed in terms of the $^1H$ NMR and $^1H$ MAS NMR spectra. Although the hydrogen bonds have two inequivalent sites, H(1) and H(2), distinct proton dynamics for the two sites were not found. Further, the $^{133}Cs$ spectrum is more or less continuous near $T_{C1}$ (=153 K). Finally, the phase transition mechanism of $T_{C1}$ in $CsH_2PO_4$ is related to the ordering of protons.

• International Journal of Computer Science & Network Security
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• v.23 no.6
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• pp.84-90
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• 2023

In this article the problem of computing floating-point reciprocal cube root functions is considered. Our new algorithms for this task decrease the number of arithmetic operations used for computing $1/{\sqrt[3]{x}}$. A new approach for selection of magic constants is presented in order to minimize the computation time for reciprocal cube roots of arguments with movable decimal point. The underlying theory enables partitioning of the base argument range x∈[1,8) into 3 segments, what in turn increases accuracy of initial function approximation and decreases the number of iterations to one. Three best algorithms were implemented and carefully tested on 32-bit microcontroller with ARM core. Their custom C implementations were favourable compared with the algorithm based on cbrtf(x) function taken from C ＜math.h＞ library on three different hardware platforms. As a result, the new fast approximation algorithm for the function $1/{\sqrt[3]{x}}$ was determined that outperforms all other algorithms in terms of computation time and cycle count.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.1
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• pp.15-20
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• 2011

[ $^7Li$ ]Magic Angle Spinning (MAS) NMR spectroscopy has been used to study the lithium local environments in $Li_4P_2O_7$ and$LiFePO_4$ materials. The purpose of this study was to know the structure of the solid electrolyte interphase (SEI) in lithium ion cells composed of $LiFePO_4$ as cathode material. $Li_4P_2O_7$ and $LiFePO_4$ were prepared by a solid-state reaction. The $^7Li$ MAS NMR experiments were carried out at variable temperatures in order to observe the local structure changes at the temperatures in $Li_4P_2O_7$ system. The $^7Li$ MAS NMR spectra of in $Li_4P_2O_7$ indicate that the lithium local environments in $Li_4P_2O_7$ were not changed in the temperature range between $27^{\circ}C$ and $97^{\circ}C$ Through this work, we confirmed that the small amount of $Li_4P_2O_7$ less than 5.0 wt% in $LiFePO_4$ could be clearly measured by the $^7Li$ MAS NMR spectroscopy at high spinning rate over than 11 kHz.

• The Journal of Korean Philosophical History
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• no.35
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• pp.385-413
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• 2012

This thesis is a study on the relation of between Xiangshu Zhouyi Theory and mathematics, Zhouyi Theory as the one of the study of Chinese classics, was formed by Zhouyi' Eight Diagrams, the theory of Yinyangwuxing and the knowledge of natural science in Han dynasty. 'Xiangshu' had been regarded as the important concept and theory in the history of Zhouyi Theory From the beginning of Han dynasty to the end of Qing dynasty. At this developing of this Periodical Change, 'Xiangshu' had been endoded in the expression system of mathematics. This thesis considers binary system and surplus nembers, multiple and progression, magic square and circular constant, a proportional expression from Zhouyi Theory point of view. Xiangshu Zhouyi theory got the answer of these questions like the origin of Zhouyi, interpreting Guayao-word and Cosmology by using those expression systems of mathematics. Besides mathematics, Xiangshu Zhouyi theory was also related to astronomy, medicine, etc. Xiangshu Zhouyi theory had kept the pace with the general development of natural science. This thesis from the premise that Xiangshu Zhouyi theory kept the pace with natural science, summing up the mathematical expression system in the history of Zhouyi theory, proves that Xiangshu Zhouyi theory had developed according as the conditions of natural science.

• Journal of Computing Science and Engineering
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• v.4 no.4
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• pp.368-387
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• 2010

We propose a novel method for the registration of 3D CT scans to 2D endoscopic images during the image-guided medialization laryngoplasty. This study aims to allow the surgeon to find the precise configuration of the implant and place it into the desired location by employing accurate registration methods of the 3D CT data to intra-operative patient and interactive visualization tools for the registered images. In this study, the proposed registration methods enable the surgeon to compare the outcome of the procedure to the pre-planned shape by matching the vocal folds in the CT rendered images to the endoscopic images. The 3D image fusion provides an interactive and intuitive guidance for surgeon by visualizing a combined and correlated relationship of the multiple imaging modalities. The 3D Magic Lens helps to effectively visualize laryngeal anatomical structures by applying different transparencies and transfer functions to the region of interest. The preliminary results of the study demonstrated that the proposed method can be readily extended for image-guided surgery of real patients.

• Journal of the Korean Magnetic Resonance Society
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• v.4 no.1
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• pp.12-18
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• 2000

Metakaolinite produced by thermal transformation from kaolinite was studied by 27Al multiple quantum magic angel spinning (MQMAS) NMR technique in addition to 1-dimensional 27Al and 29Si MAS NMR. Our results confirm that 4-, 5-, 6- coordinated aluminum sites co-exit with some distribution of isotropic chemical shifts. This is consistent with amorphous character of metakaolinite observed with X-ray diffraction. In addition, characterization with MQMAS is briefly discussed in comparison with other NMR techniques to identify different aluminum sites especially when peaks are severely overlapped in 1-dimensional 27Al MAS NMR spectra.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.384-388
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• 2002

X-band(8-12㎓)에서 50W의 고출력을 내는 진행파관 증폭기를 설계하고 제작하여 측정하였다. 본 연구에서는 전자빔과 전자파가 상호작용을 일으키는 Interaction Circuit을 나선형구조로 구성하였고 저속파구조의 분산특성을 얻기 위해 Sheath helix 모델링 이론을 적용하였고 HFSS(High Frequency Structure Simulator) Code를 사용해 분산특성을 얻었으며 이를 바탕으로 제작하여 측정하였다. 또한 2D-MAGIC Code를 통해 전파 빔과 전자파와의 상호작용관계와 증폭기의 성능을 예측하였다. 시뮬레이션 결과 포화입력전력 100 mW를 넣었을 때 10㎓에서 43W의 출력전력과 26㏈의 이득을 얻을 수 있었으며 측정을 통해 입력전력 30mw일 때 8W의 출력, 24㏈의 이득을 얻을 수 있었다.

• Journal of Korean Vacuum Science & Technology
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• v.3 no.1
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• pp.59-65
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• 1999

There has been an interest to develop an efficient, compact microwave device using field-emitter-arrays (FEA)-based cathode. Toe valuate the optimum device-efficiency in a compact size, the propagation properties of the premodulated electron beam for the FEA-based cathode is studied in detail by the computer simulation using a PIC code, MAGIC. For the premodulated electron beam whose phase of the energy leads the phase of the current by $\pi$/2, the amplitude of the downstream current modulation can be kept as high as the initial modulation level. Using the beam parameters with the beam voltage of 6kV and the current of 2.0A, 30% of efficiency is predicted when the quality factor of 800 is chosen. the device length is reduced about twice compared with that of the conventional device. The design of practical planar cathode is carried out to meet the minimum diameter of the electron beam as 0.5 mm.