• 대한전기학회논문지:시스템및제어부문D
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• 제50권9호
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• pp.447-453
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• 2001

In this paper, a new auto-focusing algorithm for digital cameras is proposed. One of the primary concerns of digital image processing is to increase image quality, and the most important factor for degrading the images is the blurring effect due to inexact focusing. The blurring effect occurs when the focusing lens is located on an unsuitable position. Therefore, focusing on an object should be proceeded before acquiring images. The proposed auto-focusing algorithm is MMDT(min-max difference threshold), and the performance of the proposed algorithm is evaluated by the use of the focus curve. It is shown that the proposed algorithm is superior to other previous auto-focusing algorithms in both the focus shape and computation time aspects. Especially, the improvement of the focus curve shape in both monotonousness and slope indicates that focusing can be done rapidly in comparison with other previous proposed algorithms.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1984년도 하계학술회의논문집
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• pp.292-293
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• 1984

• Journal of the Optical Society of Korea
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• 제1권1호
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• pp.23-25
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• 1997

In this paper we will show theoretically that a refractive index grating exhibits a retro-self-focusing effect and an accompanying pinholing effect under the Gaussian intensity distribution of an incident optical field. Those effects result from an effective wave number change of the medium due to the intense optical field.

• 한국콘텐츠학회논문지
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• 제21권3호
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• pp.653-663
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• 2021

본 연구는 중년여성을 대상으로 양가적 성차별주의와 포커싱적 태도가 자기개념에 미치는 영향을 살펴보았다. 자기개념 척도, 포커싱적 태도 척도, 양가적 성차별주의 척도를 사용하여 만35세이상 만55세이하 중년여성을 대상으로 온라인 커뮤니티를 통해 실시하였다. SPSS 21.0을 사용하여 분석한 결과 적대적 성차별주의와 온정적 성차별주의와 유의한 정적 상관이 있으며 양가적 성차별주의가 자기개념에 유의한 부적영향을 나타났다. 양가적 성차별주의의 적대적 성차별주의가 높을수록 중년여성의 자기개념의 모든 요인이 낮아지는 경향을 보였으며 포커싱적 태도는 자기개념에 유의한 정적영향이 나타났으나 하위요인별로 달랐다. 포커싱적 태도의 표현하기와 받아들이기, 여유갖기가 자기개념에 유의한 정적영향을, 알아차리기는 부적영향이 있는 것으로 나타났으며, 되새겨보기는 유의한 영향이 나타나지 않았다. 마지막으로 본 연구의 한계점에 대해 논의하였다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.1505-1509
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• 2004

A novel technique for fine particle beam focusing under the atmospheric pressure is introduced using a radiation pressure assisted aerodynamic lens. To introduce the radiation pressure in the aerodynamic focusing system, a 25 mm plano-convex lens having 2.5 mm hole at its center is used as an orifice. The particle beam width is measured for various laser power, particle size, and flow velocity. In addition, the effect of the laser characteristics on the beam focusing is evaluated comparing an Ar-Ion continuous wave laser and a pulsed Nd-YAG laser. For the pure aerodynamic focusing system, the particle beam width was decreased as increasing particle size and Reynolds number. For the particle diameter of 0.5 ${\mu}m$, the particle beam was broken due to the secondary flow at Reynolds number of 694. Using the Ar-Ion CW laser, the particle beam width becomes smaller than that of the pure aerodynamic focusing system about 16 %, 11.4 % and 9.6 % for PSL particle size of 2.5 ${\mu}m$, 1.0 ${\mu}m$, and 0.5 ${\mu}m$ respectively at the Reynolds number of 320. Particle beam width was minimized around the laser power of 0.2 W. However, as increasing the laser power higher than 0.4 W, the particle beam width was increased a little and it approached almost a constant value which is still smaller than that of the pure aerodynamic focusing system. The radiation pressure effect on the particle beam width is intensified as Reynolds number decreases or particle size increases relatively. On the other hand, using 30 Hz pulsed Nd-YAG laser, the effect of the radiation pressure on the particle beam width was not distinct unlike Ar-Ion CW laser.

• 대한기계학회논문집B
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• 제25권3호
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• pp.315-321
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• 2001

Aerodynamic lenses are widely used in generating particle beams of high density and small diameter, but analytical or modeling studies are limited only in the free molecular regime. In this study, it is shown that generating particle beam is also possible in atmospheric pressure range, and the mechanism of generating particle beam using an orifice is analysed into three different parts : fluid dynamic contraction, diffusional defocusing, and inertial focusing. In laminar flow conditions, the diffusional defocusing effect can be neglected, and the effects of inertial focusing can be expressed in terms of the orifice size and Stokes number. Numerical experiments are done for two different orifices, d/D=1/5 and 1/10 and particle diameter d(sub)p=1-10 ㎛. The results for two different orifices can be made into a single curve when a modified Stokes number is used. The inertial focusing effect diminishes when the modified Stokes number becomes smaller than 10(sup)-2.

• 대한지구과학교육학회지
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• 제7권1호
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• pp.133-143
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• 2014

The purpose of this study was to examine the effect of scientific discussion classes focusing problem finding on the primary school students' scientific creative problem solving ability, science process skills and attitude toward science class. To verify this research problem, the subject of this study was fifth-grade students selected from four classes of M elementary school located in Busan city. For four months, the experimental group of 51 students was taught using the "scientific discussion classes focusing problem finding". The control group also of 53 students was taught in normal classes which used a text-book. All students were given pre and post test to verify the effects of scientific discussion classes focusing problem finding on the primary school students' scientific creative problem solving ability, science process skills and attitude toward science class. The results from this study are as the following. First, the scientific discussion classes focusing problem finding were effective in scientific creative problem solving ability among the primary school students. It is possibly because in the process where one student compare his/her own thoughts with the others' ones and discuss them. Second, the scientific discussion classes focusing problem finding were effective in science process skills among the primary school students. Third, the scientific discussion classes focusing problem finding were effective in attitude toward science class. In conclusion, the scientific discussion classes focusing problem finding had positive effects on improvement of primary school students' scientific creative problem solving ability, science process skills and also could lead to a change in students' cognition about science class to a positive way. Therefore, the scientific discussion class focusing problem finding is hopefully to be provided as an effective instructive strategy of science class in school in the future.

• 융복합기술연구소 논문집
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• 제11권1호
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• pp.7-12
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• 2021

The magnetic gear, which amplifies the torque by filtering the magnetic field generated by the low-speed permanent magnet with a modulator, can exclude gear contact and can be effectively applied when there are environmental restrictions. In this paper, we discuss the magnetic force characteristics of a magnetic gear using a magnetic focusing array that replaces a general permanent magnet array magnetized in a radial direction along the circumferential direction. The torque increasing effect of the discussed array, known as an arrangement that increases the principal component by focusing a radial magnetic field, is compared with that of a general magnetic gear. In particular, in a magnetic gear using such an array, the sensitivity of torque according to variables is analyzed to see how various variables known as factors affecting torque have an effect.

• Journal of the Optical Society of Korea
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• 제16권3호
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• pp.305-312
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• 2012

We numerically demonstrate the performance of a plasmonic lens composed of an array of nanoslits perforated on thin metallic film with slanted cuts on the output surface. Embedding Kerr nonlinear material in nanoslits is employed to modulate the output beam. A two dimensional nonlinear-dispersive finite-difference time-domain (2D N-D-FDTD) method is utilized. The performance parameters of the proposed lens such as focal length, full-width half-maximum, depth of focus and the efficiency of focusing are investigated. The structure is illuminated by a TM-polarized plane wave and a Gaussian beam. The effect of the beam waist of the Gaussian beam and the incident light intensity on the focusing effect is explored. An exact formula is proposed to derive electric field E from electric flux density D in a Kerr-Dispersive medium. Surface plasmon (SPs) modes and Fabry-Perot (F-P) resonances are used to explain the physical origin of the light focusing phenomenon. Focused ion beam milling can be implemented to fabricate the proposed lens. It can find valuable potential applications in integrated optics and for tuning purposes.

• 한국운동역학회지
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• 제24권3호
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• pp.229-238
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• 2014

This study comparatively analyzed the speed and segment coordination characteristics of Taekwondo hand techniques, while different attention focusing strategies were utilized. Ten elite Taekwondo poomsae athletes participated, and three different strategies (no focus, target focus, body focus) were utilized in random order. The hand velocity and upper body segment coordination characteristics were analyzed, with the following results. First, the maximum magnitudes of the hand velocity differed between the focus conditions for the Araenaereomakgi and Momtongjireugi techniques. Second, the angular velocity and kinetic energy transfer patterns of the segments differed between the focus conditions, and in the case of the body focus condition, the movement was more correct according to the theory. Third, the shoulder and elbow joint coordination patterns differed between the focus conditions, with more efficient movement shown with the body focus condition. In conclusion, we confirmed the potential of effectively using an attention focusing strategy in a taekwondo teaching situation. However, the effect on the movement coordination and results of the movement could be changed by a difference in the cue provided or the type of the task. In addition, depending on the task, the attention focusing strategy could affect the efficiency of the movement. Therefore, coaches and masters of Taekwondo will have to constitute determine the appropriate attention focusing cues based on the task.