• 한국ITS학회 논문지
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• 제23권1호
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• pp.146-152
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• 2024

본 논문에서는 크로스오버 접합에서 출력 위상을 고려한 회로해석 및 설계 방법을 제시한다. 먼저 even-odd 분석을 통해 임의의 위상을 가지는 크로스오버 접합이 만족시켜야 할 반사계수 및 임피던스 파라미터에 대한 일반해를 해석적으로 유도하였다. 또한 주어진 일반해를 실제적인 크로스오버 접합회로 구조에 적용하여 임의의 츨력 위상값을 가지는 크로스오버 접합의 정확한 설계 공식을 도출하였으며 그 결과가 기존의 연구에서 제시된 결과와 부합함을 확인하였다. 이를 이용하여 설계된 회로가 설계목표와 일치하는 정확한 출력 위상을 가지는 크로스오버 접합으로서의 성능을 만족하는 것을 입증하였다.

• 한국소음진동공학회논문집
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• 제18권10호
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• pp.1082-1090
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• 2008

In this paper, a general solution for the vibrational energy and intensity distribution through a compliant and dissipative joint between plate structures is derived on the basis of energy flow analysis (EFA). The joints are modeled by four sets of springs and dashpots to show their compliancy and dissipation in all four degrees of freedom. First, for the EFA, the power transmission and reflection coefficients for the joint on coupled plate structures connected at arbitrary angles were derived by the wave transmission approach. In numerical applications, EFA is performed using the derived coefficients for coupled plate structures under various joint properties, excitation frequencies, coupling angles, and internal loss factors. Numerical results of the vibrational energy distribution showed that the developed compliant and dissipative joint model successfully predicted the joint characteristics of practical structures vibrating in the medium-to-high frequency ranges. Moreover, the intensity distribution of a compliant and dissipative joint is described.

• 대한전자공학회논문지
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• 제11권6호
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• pp.38-43
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• 1974

임의의 전원임피이던스와 임의의 부하임피이던스 사이에 삽입할 때 입력반사계수가 가급적 넓은 주파수범위에서 최소가 되는 임피이던스 정합용 불균일선로 섹션을 설계하는 문제를 고찰하였다. 고려대상의 불균일선로는 수학적으로는 특수한 종류에 속하는 것이나 실제적으로는 완만하게 변하는 거의 모든 전송선로를 포괄할 수 있다. 입력반사 계수의 계산에서는 선로의 ABCD 파라미터의 테일러 급수전관식을 이용하였다. 그리고 설계문제를 비선형 구속조건을 가진 비선형 프로그래밍 문제로서 수식화하였으며 이것을 수차적비구속 최소법(Sequential Unconstrained Minimigation Technique)과 Fletcher-Powell 방법을 병용하여 풀었다. 결과적으로 이제까지 광대역 임피이던시 정합편 전송선제로서 발표된 가장 우수한 것보다 훨씬 특성이 개선된 것을 얻을 수 있었다.

• 한국정보과학회논문지:시스템및이론
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• 제28권10호
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• pp.491-498
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• 2001

컴퓨터 그래픽스 분야에서 물체나 장면을 실제 사진처럼 표현할 목적으로 표변 반사 특성에 고나한 많은 연구가 이루어져왔다. 본 논문은 물체의 표면 반산 특성을 구하기 위한 특별한 장비나 복잡한 기하학적인 정보를 필요로 하지 않는 광원 모델링 기법을 제시한다. 이 기법은 영상의 픽셀 밝기정보가 아닌. 카메라로 들어오는 실제 밝기를 나타내는 라디안스 정보를 이용하여 물체 표면의 반사 특성(BRDF)를 측정하는것이 특징이다. 본 논문에서 제안한 광원 모델링을 통하여 다양한 광원에서의 사실적인 장면을 복원할 수 있을 뿐만 아니라 다양한 광원의 조작과 카메라 센서의 노출시간을 자류롭게 조절하는것이 가능하다.

• 대한의용생체공학회:의공학회지
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• 제32권2호
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• pp.109-117
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• 2011

Assuming that photons absorbed by a vessel do not have acute variations, DC component reflect the basal blood volume (or diameter) before blood pulsation. Vascular stiffness and reflection is influenced by changes in basal blood volume (or diameter). This paper describes analysis of the characteristic variations of vascular stiffness, according to relative variations in DC components of the PPG signal (25-75%). For quantitative analysis, we have used parameters that were proposed previously, reflection and stiffness index, and the second derivative of PPG waveform, b/a and d/a. Significantly, the vascular stiffness and reflections were increased according to increase in DC component of the PPG signal for more than about 3% of baseline values. The systolic blood pressure were increased from $113.1{\times}13.18$ to $116.2{\times}13.319$ mmHg, about 2.76% (r = 0.991, P < 0.001) and the AC component of the PPG signal were decreased from $2.073{\times}2.287$ to $1.973{\times}2.2038$ arbitrary unit, about 5.09% (r = -0.993, P < 0.001). It is separated by DC median and correlation analysis was performed for analyzing vascular characteristics according to instantaneous DC variations. There are significant differences between two correlation coefficients in separated data.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.71-74
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• 1995

Diamond shaping is one of the machining strategies to make the optical micro-groove molds,and it is especially useful when rhe component is an assembly of the linear micro-groove array. A mirror-like surface and arbitrary crose-sectional curve can be easily made by diamond. Howerver, the cutting speed of shaping is relatively lower than that of the other cutting methods, and there exist an unstable cutting conditions that generate the chatter. This study is focused on the modeling of the simplified self-induced chatter of the diamond shapping. Form the chatter model and experiments, it is found that the unstable cutting conditions exist wwhen the depth of cut is low and cutting speed is high.

• 방사성폐기물학회지
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• 제5권2호
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• pp.109-112
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• 2007

나노 규모의 1차원 양자 구조물을 이용한 전자선 차폐 가능성에 관한 이론적 배경과 한계를 정리한다. 나노 구조물을 이용한 전자선 차폐는 차폐재의 경량화와 소형화에 크게 기여할 것으로 예상되나, 실용화를 위해서는 아직 연구되어야 할 분야가 많다. 임의의 1차원 포텐셜 장벽을 대상으로 양자투과계수 계산을 실행하여, 나노 구조물의 전자선 차폐와 관련된 문제점들을 살펴본다.

• ETRI Journal
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• 제20권1호
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• pp.46-54
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• 1998

An analysis method of electromagnetic scattering from periodic patch array of double-dipole elements on a grounded dielectric substrate in case of oblique incident and arbitrary polarization is considered. The basis functions are chosen to be entire consinusoidal functions are chosen to be entire consinusoidal functions covering the rectangular shaped domain in which the original dipoles are inscribed, unlike the conventional method in which basis functions are defined only for the conducting element region. To confirm the validity of the proposed analysis method, we calculate the normalized scattered power for two propagating modes and compare the results with those obtained by the previous numerical method for the double dipole elements of rectangular type and parallelogram type which have the property of frequency scanned reflection and polarizer. Good correspondence has been observed between them. Some numerical results such as variation of power and axial ratio of first-order diffracted wave by a periodic array of double-dipole elements are compared with previous results.

• 한국생산제조학회지
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• 제23권2호
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• pp.194-198
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• 2014

In recent years, RGM(roller gear mechanism) systems, wherein one of the gears of a meshing gear pair is replaced with pins or rollers, have been reintroduced, which is a consequence of, and therefore a reflection of, the rapid advances made in manufacturing technology. Three RTG(roller track gear) systems for arbitrary path transportation (e.g., L-, O-, U-, and S-shaped tracks) were constructed using two out of three RGM systems, namely, the CRP(cam rack pinion), CRG(cam ring gear), and RPG(roller pinion gear) systems, and are introduced in this paper. We also present three ways to prevent the intersection and non-contact phenomena at the teeth in the vicinity of the conversion point between two joined RGM systems.

• International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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• 제25권1호
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• pp.47-56
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• 1997

We present a theoretical study on how the plasmasphere responses to the sudden impulses in the magnetosphere. A mechanism on how Pi 2 pulsations are excited in the magnetosphere is also proposed. When impulsive disturbances associated with the substorm onset are assumed in the magnetotail, their propagation toward the sunward direction is investigated with a wave equation. The propagation speed undergoes serious variations owing to the existence of the plasmasphere, which results in various reflection and tunneling of traveling disturbances at the plasmapause. In order to examine the effect of the plasmapause on initial impulsive disturbances, we analytically solve the wave equation based on the model of reasonable Alfven speed profile. The exact solution shows that virtual resonant states exist inside the plasmaspheric cavity. We obtain the result that these unique modes strongly persist for arbitrary incoming impulses from the source in the magnetotail, which quantitatively corresponds to the signature of PI 2 pulsations.