• International journal of advanced smart convergence
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• 제6권4호
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• pp.33-40
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• 2017

In this paper, complex quadruplet zeros of microwave filter systems are investigated. For the cascaded systems the chain matrices are most conveniently used to derive the voltage transfer function of Laplace transform with cascaded two-port subsystems. The convenient relations of transfer function and chain matrix are used in order to find the transmission zeros. Starting from a ladder network, we introduced a crossed-coupled lumped element, in order to show the improved response of bandpass filter. By solving the transmission zero characteristic equation derived from the cascaded subsystems, we found the zeros of filter system with externally cross-coupled lumped elements. With the cross-coupled elements of capacitors, the numerator polynomial of system transfer function is used to locate the quadruplet zeros in complex plane. When the two pairs of double are on the zeros -axis, with the perturbed values of element, we learned that the transition band of lowpass filter is improved. By solving the characteristic equation of cascaded transfer function, we can obtain the zeros of the cross-coupled filter system, as a result of perturbed values on lumped element.

• 한국초등과학교육학회지:초등과학교육
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• 제37권4호
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• pp.416-429
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• 2018

In social constructivist teaching, knowledge construction is achieved through learners' collective social interaction. Vygotsky argued that this process is mediated with language use, and the development of higher order thinking is realized through the transition from inter-personal psychological functions to intra-personal psychological functions. In so doing scientific concepts are internalized to learners. This study examined the third grade elementary students' inter/intra-personal psychological functions and their internalization processes during social constructivist teaching plan about strata and fossils. The lessons were designed along with Wells' dialogic inquiry and Leach and Scott's social constructivist teaching-learning sequences. Results showed that a teacher's utterances of talking with questioning to switch attention, creating cognitive disequilibrium, and expanding the width of students' opinions could make effective inter-personal psychological function. In addition, a learner's inner speech expressed into social discourse through talking about personal experiences, comparing epistemic idea with visual representation, or applying to different situation showed his/her intra-personal psychological function. Some cases of learners' internalization through language use could be at the stage of knowledge building and understanding of the spiral of knowing, but not all. Thus it is argued that a teacher's deeper insight into Vygotskian social constructivist teaching can make elementary science classroom teaching more effective in their inter/intra-psychological functions.

• 대한화학회지
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• 제60권6호
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• pp.410-414
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• 2016

The anharmonic frequency of a local OH stretching mode of a water monomer and dimer was calculated using various levels of density functional theory. The quantum chemical potential energy curves as a function of the OH bond distance were calculated, and they were fitted with the Morse potential function to analytically obtain the fundamental transition frequency. By comparing those values with the frequencies similarly calculated using an ab initio quantum chemical method, the coupled cluster theory including both single and double excitations with the perturbative inclusion of triple excitation in the complete basis limit, the accuracy of various density functional methods in the calculation of anharmonic vibration frequency of water molecules was assessed. For a water monomer, X3LYP and B3LYP methods give the best accuracy, whereas for a water dimer, B972, LCBLYP, ${\omega}B97X$, ${\omega}B97$ methods show the best performance.

• Applied Science and Convergence Technology
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• 제25권6호
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• pp.154-157
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• 2016

The energy dispersion and magnetization of a modified magnetic dot are investigated numerically. The effects of additional electrostatic potential, magnetic field non-uniformity, and Zeeman spin splitting are studied. The modified magnetic quantum dot is a magnetically formed quantum structure that has different magnetic fields inside and outside of the dot. The additional electrostatic potential prohibits the ground-state angular momentum transition in the energy dispersion as a function of the magnetic field inside the dot, and provides oscillation of the magnetization as a function of the chemical potential energy. The magnetic field non-uniformity broadens the shape of the magnetization. The Zeeman spin splitting produces additional peaks on the magnetization.

• Bulletin of the Korean Chemical Society
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• 제32권4호
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• pp.1336-1340
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• 2011

Molecular dynamics simulations have been performed to investigate the transport properties of self-diffusion coefficients in the penetrable-sphere model system. The resulting simulation data for the product of the packing fraction and the self-diffusion coefficient exhibit a transition from an increasing function of density in lower repulsive systems, where the soft-type collisions are dominant, to a decreasing function in higher repulsive systems, where most particle collisions are the hard-type reflections due to the low-penetrability effects. A modified Enskog-like equation implemented by the effective packing fraction with the mean-field energy correction is also proposed, and this heuristic approximation yields a reasonably good result even in systems of high densities and high repulsive energy barriers.

• 한국경영과학회지
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• 제19권3호
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• pp.93-109
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• 1994

Even though sojourn time distributions are essential information in analyzing queueing networks, there are few methods to compute them accurately in non-product form queueing networks. In this study, we model the location process of a typical customer as a GMPH semi-Markov chain and develop computationally useful formula for the transition function and the first-passage time distribution in the GMPH semi-Markov chain. We use the formula to develop an effcient method for approximating sojourn time distributions in the non-product form queueing networks under quite general situation. We demonstrate its validity through numerical examples.

• 항공우주시스템공학회지
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• 제2권3호
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• pp.1-6
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• 2008

The tilt rotor aircraft has the flight characteristics which takes off vertically like a helicopter and flies forward like an airplane. Especially, the transition process from a helicopter to an airplane mode requires not only the mixing of control inputs but also the stability and controllability augmentation system(SCAS) in order to keep the safe flight because there are compound flight dynamic characteristics of a helicopter and an airplane including non-linearity, uncertainty. This paper describes the design of SCAS in a lateral motion for the tilt rotor aircraft based on the $H_{\infty}$ control method, which was performed from mathematical model with weighting matrix based on the relationship between the $H_{\infty}$ norm and the sensitivity function. Through simulation analysis for the controller designed on the $H_{\infty}$ control theory, it was shown that this method may be applied to the control design of the tilt rotor aircraft.

• 한국재료학회지
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• 제8권8호
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• pp.678-684
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• 1998

정압분자동역학 시뮬레이션에 의하여 주기경계조건을 지닌 L-J 입자들로 구성된 계의 액체-유리-결정 전이를 연구하였다. 원자체적과 엔탈피는 가열 및 냉각과정에서 온도의 함수로 계산되었다. 반경분포함수로부터 유도된 Wendt-Abraham비와 단거리규칙도를 나타내는 각도분포함수를 분석하여 액체, 유리 및 결정상태를 구분하였다. 초기 fcc 결정을 가열하여 얻은 액체상은 급냉시에 비정질화하나 서냉시엔 결정화하였다. 급냉으로 생긴 유리는 다시 서서히 가열하면 fcc로 결정화하였다. 자유표면을 지닌결정은 표면에서부터 용해가 시작되어 벌크에 비하여 낮은 온도에서 녹고 냉각시에는 빠른 냉각속도에서도 결정화가 쉽게 일어나는 경향을 보였다.

• 한국실내디자인학회논문집
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• 제15권1호
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• pp.106-112
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• 2006

Buildings undergo changes by various factors according as pass at time. Due to that social requests and issues form one common sense of value and this would influence the architect's design intention. In fact, the form and function of buildings have coped with transition of the common sense of value by each times. Hospital architecture is also changed in function, scale and technology since, Kwanghyewon which was the first western style hospital in Korea was established in 1885. It is changing that the social needs for hospital which was a basic function of healing to laying emphasis on the function of precaution. According to this, the change of hospital spaces means that it can promote healing environment which is expanded from the modern concept of isolation, accommodation and urban sanitation. These changed concepts were adopted limited areas in hospitals at first however, nowadays they are expanding to other areas. So, this is caused to make the image of the hospital. From this point of view, Entry space is an example to show the changes. This study is intended to determine the overall space structure of entry area and to classify and analyze the difference.

• 한국표면공학회지
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• 제36권5호
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• pp.413-417
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• 2003

The effect of 0-0.7 ㏖% addition of $Cr_2$$O_3$on the dielectric, pyroelectric, and piezoelectric properties were studied in the (Mg$0.7Pb_{1}$$3/Nb_{2}$3/)$O_3$-$0.3PbTiO_3$(0.7PMN-0.3PT) ceramics with composition near the morphotropic phase boundary. The dielectric constant and loss of the ceramics samples were measured as a function of temperature at various frequencies (0.1-100 KHz). The pyroelectric coefficient was measured by using the Byer-Roundy method as a function of temperature. Dielectric, pyroelectric, and piezoelectric constant achieved the maximum values of 0.4 ㏖% $Cr_2$$O_3$The transition temperature is continuously shifted to lower temperature with an increase of a small amount of $Cr_2$$O_3$.