• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.2
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• pp.170-175
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• 2016

In order to transmit baseband signals through frequency dividing devices, we studied the transfer function of the device in the term of the baseband signal distortion. From the analysis, it is shown that the magnitude of the envelope signal is related to the mixer gain and the insertion loss of the low pass filter whilst the phase is the additional function with the 1/2 of the phase delay. For the purpose of the verification of the study, we designed a dynamic frequency divider at 1,400 MHz. The operating frequency range of the device is closely related to the conversion gain of mixers and the amplitude of input signal, and becomes wide as the conversion gain of mixers increases. The designed frequency divider operates between 0.9 GHz and 3.2 GHz, for -14.5 dBm input power. The circuit shows 20 mW power dissipation at $V_{DD}=2.5V$, and the simulation result shows that an amplitude modulated signal at 1,400 MHz with the modulation index of 0.9 was successfully downconverted to 700 MHz.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.11
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• pp.574-582
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• 2018

In systems such as railways, automobiles, and airplanes, system malfunctions may lead to accidents, which often cause serious personal injury and economic loss. In previous studies, failure analysis has been performed, and safety measures derived using the component level information to reduce damage when a failure occurs. However, in functional safety concept, a focus is placed on lowering the frequency of occurrence of failures by performing risks analysis, setting up safety goals, and designing safety functions. Therefore, it is necessary to study how to determine the required safety function that can reduce the failure frequency to the acceptable level. To achieve this, we first studied a failure modeling method using SysML. It was then presented how several alternatives can be assessed to determine the desired safety function by simulating the generated SysML failure models and calculating the ability to reduce the failure frequency. A case study of a railway signaling system was done, demonstrating the effectiveness of the approach. We assessed whether the safety objectives were met for the alternative design of the railway signaling system through M & S. The results can be useful in that it can be applied from the early design phase and allow to choose the appropriate safety function that satisfies safety objectives among various design alternatives.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.26 no.8
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• pp.1153-1163
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• 2002

A transient analysis on temperatures of fuel and oil in hydraulic and lubrication systems in an aircraft was studied using the finite difference method. Numerical calculation was performed by an explicit method with modified Dufort-Frankel scheme. Among various missions, air superiority mission was considered as a mission model with 20% hot day ambient condition in subsonic region. The ambience of the aircraft was assumed as turbulent flow. Convective heat transfer coefficient were used in calculating heat transfer between the aircraft surface and the ambience. For an aircraft on the ground, an empirical equation represented as a function of free-stream air velocity was used. And the heat transfer coefficient for flat plate turbulent flow suggested by Eckert was employed for in-flight phases. The governing equations used in this analysis are the mass and energy conservation equations on fuel and oils. Here, analysis of fuel and oil temperature in the engine was not carried out. As a result of this analysis, the ground operation phase has shown the highest temperature and the largest rate of temperature increase among overall mission phases. Also, it is shown that fuel flow rate through fuel/oil heat exchanger plays an important role in temperature change of fuel and oil. This analysis could be an important part of studies to ensure thermal stability of the aircraft and can be applicable to thermal design of the aircraft fuel system.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.416-419
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• 2007

In the case of domestic, related information of expenses in order to draw up cost model at the early stage haven't been stored systematically; moreover, similar projects which were accomplished in the past time have lacked data about actual results connected itself. Accordingly, a reliable object hasn't been selected because validity of cost comparing a main function is difficult to dearly decide. Consequently, This study Cost model who can procures and shares and utilizes, studies that is achieved past Cost information of similarity project and achieves in phase zero for target choice of VE activity to systematic and efficient analysis wishes to present conceptional pattern of available Web-Based VE 'Cost model analysis system (Cost Model Analysis System: CMAS)'.

• 재활복지
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• v.21 no.2
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• pp.247-259
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• 2017

We investigated the improvement of cognitive functions, activity of daily living (ADL), and quality of life (QoL) after hemorrhagic stroke and identified associated factors. For this research, twenty-five patients with a hemorrhagic stroke were enrolled. We measured cognitive function, activity of daily living (ADL), and quality of life (QoL) from 7 days to 12 months after onset of stroke. Then we analyzed the correlation between cognitive function and other risk factors. According to results, cognitive functions improved during 12 months with statistically significant differences. Other functions were similar to cognitive functions. Improvement of cognitive functions were correlated with age, the type of hemorrhagic stroke and Glasgow coma scale at 7 days after stroke. Overall, cognitive function in patients with hemorrhagic stroke recovered from acute to 12 months after onset of stroke. And, improvement of cognitive function at this phase were associated with age, the type of hemorrhagic stroke and GCS score at 7 days. These results would provide us an information to plan cognitive rehabilitation in patients with hemorrhagic stroke.

• Korean Journal of Remote Sensing
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• v.27 no.2
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• pp.163-170
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• 2011

In this paper, we analyzed the phase change of 5-triangular trihedral comer reflectors by using X-band Ground-Based Synthetic Aperture Radar (GB-SAR) system. Each reflector was set as a stationary target at a different distance from the system. We obtained total 123 full-polarization images during 40 hours continuously at 20 minute interval. Results of SAR interferometric analysis showed phase changes of maximum 2 radians and followed similar pattern with atmospheric data. Through a GB-SAR phase formula that includes refractive index in the air, we performed regression analysis for refractive index as a function of atmospheric humidity, temperature and pressure. As a result, refractive index of air in X-band showed relatively high coefficient of determination with humidity and temperature (0.72 and 0.76 on average, respectively) but not so with pressure (0.34). The refractive index of air in X -band changed by 3.14\;{\times}\;10^{-5}$ during the measuring time with a humidity range of 50% ~ 90% and a temperature range of $-1^{\circ}C$ ~ $9^{\circ}C$. We expect that a total expression of refractive index of air including humidity, temperature and pressure can be calculated when more extensive data would be collected at various atmospheric conditions.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3C
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• pp.271-280
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• 2008

M channel near-perfect-reconstruction(NPR) pseudo-QMF banks are a hybrid of conventional pseudo-QMF design and spectral factorization approach where the analysis and synthesis filters are cosine-modulated versions of the prototype-lowpass filter(p-LPF). However, p-LPF H(z) does not have linear-phase symmetry as well as magnitude-distortion optimization since it is obtained by spectral factorization of $2M^{-th}$ band filter $G(z)=z^{-(N-1)}H(z^{-1})H(z)$. A fair amount of attention, therefore, has been focused on the design of filter banks for reducing only alias-cancellation distortion without reconstructed-amplitude distortion. In this paper, we propose a new method for designing linear-phase p-LPF in NPR pseudo-QMF banks, which is based on Maxflat(maximally flat) FIR filters with closed-form transfer function. In addition, p-LPF H(z) is optimized in this approach so that the 2M-channel overall distortion response represented with $G(z)=H^2(z)$ approximately becomes an unit magnitude response. Through several examples of NPR pseudo-QMF banks, it is shown that the peek ripple of the overall magnitude distortion is less than $3.5{\times}10^{-4}\;({\simeq}-70dB)$ and analysis/synthesis filters have the sharp monotone-stopband attenuation exceeding 100 dB.

• Journal of Sasang Constitutional Medicine
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• v.8 no.2
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• pp.95-116
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• 1996

As considering a comparison study of the structure of mind and psychologic type of C.G Jung to Ji-In-Lon and Sa-Sang constituition of Lee Je Ma, I've got the following conclusion. 1. The study of the structure of mind of Jung and Ji-In-Lon of Lee Je ma have a important meaning to each theory of type of men. They developed their own peculiar theory of type men by the analysis of the mind of men. 2. Jung explained the organization of recognition by four phase theorical structure; consciousness, personal unconsciousness, collective unconsciousness, self. Lee Je Ma explained the organization of recognition by four phase theorical structure;Sa, Sim, Sin, Mul. And theory of type of men, Jung established four type; Tae-Yang-In, Tae-Um-In, So-Yang-In, So-Um-In, They all established the four phase structure, which have things in common. 3. Jung studied the consciousness and unconsciousness and Lee Je Ma studied the Sung-In, Eui, Ye, Ji, and Sim-Yock-Bi, Bak, Tam, Na. I think they have a close relationship. And I think there is relationship between consciousness, unconsciousness to Gun-Ja-Ji-Sim, So-In-Ji-Sim. 4. I think there is thought of relationship between Lee Je Ma's Dae-Dong, Gak-lip, Hang-gi-ji, Hang-gi-hang and Ho-sun, Oh-ak, Sa-sim, Tae-hang and relationship of internal organ's size to Jung's the first function, second function, third function, fourth function. 5. I think the relationship between the type of Jung;thinking type, feeling, type, sensation type, intuition type to the type of Lee Je Ma; Tae-Yang-In, Tae-Um-In, So-Yang-In, So-Yang-In, So-Um-In needs more study.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.12 no.1
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• pp.36-49
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• 1987

A planar waveguide model is presented for calculating dispersion characteristics of the normalized phase velocity and characteristic impedance with the frequency dependent effective dielectric constand and effective width in microstrip lines of the hybrid mode. Eeff(f) and Weff(f) are applied to a planar waveguide model by using an empirical relations and formula designed for CAD purposes as a function of frequency. A wide range of relative dielectric constants and the strip $h_{width}$strate height(W/h ratios), $0.5$\leq$W/h\leq2.5$ are used. These results are compared with static value, spectral domain analysis, and empirical results. As the result of a computer simulation, in the case of using a planar waveguide model, the frequency dependent normalized phase velocity is more closely approached to 1/ and characteristic impedance is more increased than the other method that has already been presented as the increasing of the frequency. And, the case of applying Eeff(f) designed for the purpose of CAD to this proposed model is show in better result than the case of using a empirical relations.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.5
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• pp.583-588
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• 2010

The nonlinearity and high deformability of rubber make accurate analysis of the behavior of cord-rubber composites a challenging task. Some researchers have adopted the third phase between cord and rubber and have carried out three-phase modeling. However, it is difficult to determine the thickness and properties of the interface in cord-rubber composites. In this study, a two-dimensional finite-element method (2D FEM) is used to investigate the effective and normalized moduli of cord-rubber composites having interfaces of various thicknesses; this model takes into account the 2D generalized plane strain and a plane strain element. The neo-Hookean model is used for the properties of rubber, several interface properties are assumed and three loading directions are selected. It is found that the properties and thickness of the interface can affect the nonlinearity and the effective modulus of cord-rubber composites.