• Radiation Oncology Journal
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• 제5권2호
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• pp.157-163
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• 1987

It is known that fixed source to skin distance (SSD) cannot be used when the treatment field is sloped or larger than the size of second collimator in electron beam irradiation and inverse square law using effective ssd should be adopted. Effective SSDs were measured in different field sizes in each 6, 9, 12, 15 and 18MeV electron energy by suing NELAC 1018D linear accelerator of Kosin Medical Center. We found important parmeters of effective SSD. 1. Minimum effective SSD was 58.8cm in small field size of $6\pm6cm$ and maximum effective SSD was 94.9cm in large field size of $25\pm25cm$, with 6MeV energy. It's difference was 36.1cm. The dose rate at measuring point was quite different even with a small difference of SSD in small field $(6\times6cm)$ and low energy (6 MeV). 2. Effective SSD increased with field size in same electron energy. 3. Effective SSDs gradually increased with the electron energies and reached maximum at 12 or 15 MeV electron energy and decreased again at 18MeV electron energy in each identical field size. And so the effective SSD should be measured in each energy and field size for practical radiotherapy.

• 한국전기전자재료학회논문지
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• 제11권1호
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• pp.26-32
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• 1998

We have studied how the characteristics degradation between effective mobility and field effect mobility of gate channel in p-MOSFET's affects the gate channel length being follow by increased stress time and increased drain-source voltage stress. The experimental results between effective and field-effect mobility were analyzed that the measurement data are identical at the point of minimum slope in threshold voltage, the other part is different, that is, the effective mobility it the faster than the field-effect mobility. Also, It was found that the effective and field-effect mobility. Also, It was found that the effective and field-effect mobility of p-MOSFET's with short channel are increased by decreased channel length, increased stress time and increased drain-source voltage stress.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권6호
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• pp.867-872
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• 2016

We have investigated the channel mobility of AlGaN/GaN-on-Si recessed-metal-oxide-semiconductor-heterojunction field-effect transistors (recessed-MOS-HFET) with $SiO_2$ gate oxide. Both field-effect mobility and effective mobility for the recessed-MOS channel region were extracted as a function of the effective transverse electric field. The maximum field effect mobility was $380cm^2/V{\cdot}s$ near the threshold voltage. The effective channel mobility at the on-state bias condition was $115cm^2/V{\cdot}s$ at which the effective transverse electric field was 340 kV/cm. The influence of the recessed-MOS region on the overall channel mobility of AlGaN/GaN recessed-MOS-HFETs was also investigated.

• Bulletin of the Korean Chemical Society
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• 제6권5호
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• pp.309-311
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• 1985

When a molecule is perturbed by an external field, the perturbed moecue can be described as a doubly perturbed system. Hartree-Fock operator in the absence of the field is the zeroth order Hamiltonian, and a correlation operator and the external field operator are perturbations. The effective Hamiltonian, which is a projection of the total Hamiltonian onto a small finite subspace (usually a valence space), has been formally derived. The influence of the external field to the molecular Hamiltonian itself has been examined within an effective Hamiltonian framework. The first order effective expectation values, for instance electromagnetic transition amplitudes, between valence states are found to be easily calculated - by simply taking matrix elements of the effective external field operator. Implications of the terms in perturbation expansion are discussed.

• 한국수학교육학회지시리즈A:수학교육
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• 제17권2호
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• pp.1-13
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• 1979

This study aimed at studying the sequence of the Figure Transformation Learning, inquiring relationship among these transformations and then researching whether there is the difference of the learning ability or not between by teaching them as it is independent and by teaching them as it is contains. (Hypothesis 1) It may be more effective to teach The Sequence of Transformation Learning by beginning with peculiar field, ending with general field than vice versa At the result of verification-C $R_{M}$=2.59, 0.005$R_{M}$=5.19, p<0.005-significant difference appeared. It is proved more effective to teach the Figure Transformation Learning the way it contains than the way it is independent. Synthesizing two hypothesises of the above, the conclusion is following The Figure Transformation Learning should be taught by beginning with peculiar field. ending with general field (congruent transformationlongrightarrowsimilar transformationlongrightarrowprojective transformationlongrightarrowtopological transformation). To teach it the way it contains is more effective.ive.

• 한국진공학회지
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• 제12권S1호
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• pp.36-39
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• 2003

Field-domain dynamics and current self-oscillations are theoretically studied in quantum-well (QW) negative-effective-mass (NEM) $p^{+}pp^{+}$ diodes when the electric field is applied along the direction of the well. The origin of current self-oscillations is the formation and traveling of electric-field domains in the p-base. We have accurately considered the scattering contributions from carrier-impurity, carrier-acoustic phonon, and carrier-optic phonon. It's indicated that, both the applied bias and the doping concentration largely influence the current patterns and self-oscillating frequencies, which lie in the THz range for the NEM $p^{+}pp^{+}$ diode with a submicrometer p-base. The complicated field-domain dynamics is presented with the applied bias as the controlling parameter.

• Current Optics and Photonics
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• 제6권4호
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• pp.420-429
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• 2022

In this paper, the details and design process of an optical system for space target detection cameras are introduced. The whole system is divided into three structures. The first structure is a short-focus visible light system for rough detection in a large field of view. The field of view is 2°, the effective focal length is 1,125 mm, and the F-number is 3.83. The second structure is a telephoto visible light system for precise detection in a small field of view. The field of view is 1°, the effective focal length is 2,300 mm, and the F-number is 7.67. The third structure is an infrared light detection system. The field of view is 2°, the effective focal length is 390 mm, and the F-number is 1.3. The visible long-focus narrow field of view and visible short-focus wide field of view are switched through a turning mirror. Design results show that the modulation transfer functions of the three structures of the system are close to the diffraction limit. It can further be seen that the short-focus wide-field-of-view distortion is controlled within 0.1%, the long-focus narrow-field-of-view distortion within 0.5%, and the infrared subsystem distortion within 0.2%. The imaging effect is good and the purpose of the design is achieved.

• 정보보호학회논문지
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• 제9권4호
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• pp.3-10
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• 1999

유한체(Galois fields)가 타원곡선 암호법 coding 이론 등에 응용되면서 유한체의 연 산은 더많은 관심의 대상이 되고 있다. 유한체의 연산은 표현방법에 많은 영향을 받는다. 즉 최적 정규기 저는 하드웨 어 구현에 용이하고 Trinomial을 이용한 다항식 기저는 소프트웨어 구현에 효과적이다. 이논문에서는 새로운 변형된 다항식 기저를 소개하고 AOP를 이용한 경우 하드웨어 구현에 효과적인 최 적 정규기저와 의 변환이 위치 변화로 이루어지고 또한 이것을 바탕으로 한 유한체의 연산이 소프트웨어적 으로 효율적 임을 보인다. More concerns are concentrated in finite fields arithmetic as finite fields being applied for Elliptic curve cryptosystem coding theory and etc. Finite fields arithmetic is affected in represen -tation of those. Optimal normal basis is effective in hardware implementation and polynomial field which is effective in the basis conversion with optimal normal basis and show that the arithmetic of finite field with the basis is effective in software implementation.

• 전자공학회논문지 IE
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• 제48권3호
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• pp.33-39
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• 2011

현장실습 제도는 대학생들의 실무능력 향상을 위한제도이다. 이러한 현장실습제도는 대학의 정규 교육과정과 산업현장의 일을 연계한 학습경험 및 활동이다. 효율적인 현장실습제도를 실천하기 위해서는 기업과 대학, 학생 그리고 정부의 관심과 도움이 필요하다. 그러나 대부분의 산업체는 현장실습을 위한 전담직원이나 별도로 확보된 예산이 없는 상태에서 현장실습 인력을 수용하기가 어려운 현실이다. 그렇기 때문에 대학은 현장실습제도를 운영하는데 가장 큰 애로사항으로 실습을 위한 산업체를 확보하는 일이라고 할 수 있다. 그리고 학생들은 보다 선진화된 시설과 장비를 갖추고 있는 산업체에서 정당한 보수를 받고 실습에 참여하고 싶지만 현실적으로는 상당히 어려운 상황이다. 그러므로 본 논문에서는 효율적인 산업체 현장실습제도를 운영하기 위해서 산업체 현장실습 운영과정을 위한 모델과 방법론을 제시하였다. 제시된 운영과정 모델과 방법론을 기반으로 현장실습제도가 운영된다면 학생들은 산업체의 현장 경험으로 창의력과 순발력을 발휘할 수 있는 기회와 다양한 차원의 교육을 받을 수 있는 현장실습 제도가 운영될 것으로 기대한다.

• Journal of the Optical Society of Korea
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• 제19권4호
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• pp.346-350
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• 2015

We report a measurement of the effective refractive index of a nematic liquid crystal (NLC) inside a Fabry-Perot (FP) etalon according to the applied electric fields. The effective refractive index of the NLC depends on the intensity of the applied electric field. A wavelength-swept laser with a polygon-scanner-based wavelength filter is used as a wide-band optical source to measure the effective refractive index of the NLC. The bandwidth of the optical source is greater than 90 nm around 1300 nm. The fabricated NLC FP etalon consists of glass substrates, gold layers as the electrodes with highly reflective surfaces, polyimide layers as the planar alignment layers, and an LC layer. Furthermore, we measured the Freedericksz transition voltages for three types of NLC FP etalons having thicknesses of $30.6{\mu}m$, $55.4{\mu}m$, and $108.8{\mu}m$. The Freedericksz transition voltages in the three cases are nearly equal. The measured effective refractive indices in the three cases decreased from 1.67 to 1.51 as the applied electric field intensity was increased. Beyond the threshold electric field, the effective refractive indices quickly decreased and eventually saturated at a value of 1.51 for all cases.