• Journal of the Korean Society of Environmental Restoration Technology
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• 제21권2호
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• pp.53-64
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• 2018

This study aims to quantitatively evaluate the conservation priorities of unexecuted urban parks in Seoul both from an ecological and public perspective. To this end, two methodologies, ecological network analysis based on graph and circuit theory and accessibility analysis, were employed in order to assess ecological connectivity of and public accessibility to unexecuted parks, respectively. This study applied linkage-mapping methods (shortest path and current flow betweenness centrality) of connectivity analysis to an integrated map of landscape permeability. The population-weighted accessibility to unexecuted parks was measured based on a negative exponential distance decay function. As a result, for both ecological connectivity and accessibility, Gwanaksan, Suraksan, and Bulamsan urban natural parks are found to be the most important (rank 1-3) to be conserved. For these sites, inner park areas with conservation priorities for connectivity and accessibility were identified. The findings of the study can be used for giving conservation priority to the unexecuted urban parks in terms of long-term sustainable urban planning.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 1992년도 추계학술대회 논문집
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• pp.114-117
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• 1992

This paper presents the design and calibration methods of self-integrated magnetic sensor. Also the distance response measurement of magnetic field produced a transient large current and the frequency response measurement are carried out As the integrating resistance increases. the sensitivity of the sensor is improved, but the decay time constant of response decreases, Also the experimental results are well agreed with the theoretical analysis of the equivalent circuit.

• Korean System Dynamics Review
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• 제3권1호
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• pp.5-42
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• 2002

The main purpose of this paper is analyzing long-term growth possibility of a telecommunication Company (Telco) H. First of all, to achieve this purpose, the precise understanding about causal relations among growth and decay factors of Telco H is required. Based upon the causal analysis, a basic computer simulation model is developed. Finally, several predictive examinations about growth possibility and pattern of the Telco H are conducted using three scenarios. From simulation results, the most important policy leverages are capabilities of market share sustenance, improvement of service quality and squeezing current network facility to elevate profitability and efficiency. Recently, telecommunication industry has become more and more competitive due to introduction of Internet and deregulation. Internet has brought about global competition as well as confusion between telecommunication and broadcasting industries. At the almost same time, deregulation is a universal tendency and a catalyst of unlimited competition. Telco H has been a dominant company in Korea for last century. However, the dominant position of Telco H has been threatened by the change of competition environment. The competitive environment has many elements and keeps changing dynamically. Therefore, System Dynamics simulation methodology is adopted to examine the problem.

• Journal of Magnetics
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• 제8권2호
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• pp.98-102
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• 2003

Microstructure and magnetic transport phenomina in rf sputtered AIN/CO type ten- layered discontinuous films of nanoscaled [AIN(3 nm)/Co(t nm)]…$_10$ with t$_Co$=1.0∼2.0 nm have been investigated. The microstructure and tunneling magnetic resistance of the samples are strongly dependent on the thickness of Co layer, Negative tunneling magneto-resistance due to the spin-dependent transport has been observed along the current-in-plane configuration in the samples having the Co layers below 1.6 nm thick. When the thickness of Co layer was less than 1.2 nm, randomly oriented granular Co particles were completely isolated and embedded in amorphous AIN matrix, and the films showed the superparamagnetic behavior with a high MR value of ${\Delta}p/p_0$=1.8%. As t$_Co$ increases, a transition from the regime of co-existence of superparamagnetic and ferromagnetic behaviors to ferromagnetic behavior was observed. funneling barrier called “decay length far tunneling” fur the films haying the thickness of Co layer from 1.4 to 1.6 nm was measured to be ranged from 0.004 to 0.021 ${\AA}$$^{-1}$.

• Journal of Korean Society of Coastal and Ocean Engineers
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• 제3권3호
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• pp.163-169
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• 1991

Sixty seven regular wave tests were performed in a wave-current flume to investigate proper-ties of waves breaking on irregular slope profiles. In these tests, 1/10, 1/20 beach slopes were made using angles and plywoods. A little differences were found in such properties as breaker depth and height indices. runup for plane slopes comparing with other laboratory experiments. however. for smaller deepwater wave steepness, measured breaker height and depth data values were smaller than other formulas. On wave runup agreement was good between experiments and Hunt formula. however. measured data values were influenced by number of breaking. Significant differences were found in breaker depth index for plane and barred slopes. Wave height decay after breaking was found to be smaller than Dally et al.'s formula (1984).

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 한국초전도저온공학회 2003년도 학술대회 논문집
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• pp.123-125
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• 2003

We joined 19-multifilamentary (Bi, Pb)$_2$Sr$_2$Ca$_2$Cu$_3$O$_{x}$ Superconducting tapes and fabricated double-pancake coils by using resistive- and superconducting-joint methods. The joint resistance of the coils were characterized by the field decay technique and standard four-probe method. It was evaluated that joint resistance was 3.21$\times$10$^{-11}$ $\Omega$ in the superconducting-joint coil, which is approximately 4 orders of magnitude smaller than that in the resistive-joint coil (107$\times$10$^{-9}$ $\Omega$). The low value of joint resistance obtained by superconducting-joint is expected to be suitable for the practical applications in the persistent current mode.e.

• Journal of the Korean Institute of Intelligent Systems
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• 제22권3호
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• pp.300-304
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• 2012

This paper presents a nonlinear observer design method for SOC(state-of-charge) estimation of Lithium polymer battery cell. The dynamic equation of the battery cell is modeled as a simple RC electrical circuit with a nonlinear voltage source and the parameters are obtained via nonlinear optimization. Using the sum of squares decomposition, the observer gain is designed such that the error dynamics is asymptotically stable and the decay rate is below the prescribed value. In order to illustrate the performance of the observer, a computer simulation is performed using the experimental data with the UDDS(urban dynamometer driving schedule) current profile.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.311-312
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• 2007

Polyimide is widely used as a high-temperature insulating material. Space charge distributions in polyimide (PI) films strongly depend upon electric field, temperature, water content and so on. We observed space charge distributions in PI films with various water contents. When a dc field was applied to as-received PI films or water-treated PI films, positive and negative homo space charges were observed near the respective electrodes at 333 K. In dried PI films, the homo space charges were much reduced, and positive and negative hetero space charges in the bulk were clearly observed. The space charge amounts in water-treated PI films were smaller than in as-received ones, while the current density in water-treated PI film was larger than that in as-received one by two or more orders of magnitude. These suggest not only that the charge injection from the electrode is enhanced by absorbed water but also that absorbed water makes carriers mobile. The decay of space charge was also faster in water-treated PI than in as-received or dried one. This also supports the enhancement of apparent mobilities of carriers in PI by absorbed water.

• Proceedings of the KIEE Conference
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.1984-1985
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• 2007

Polyimide is widely used as a high-temperature insulating material. Space charge distributions in polyimide (PI) films strongly depend upon electric field, temperature, water content and so on. We observed space charge distributions in PI films with various water contents. When a dc field was applied to as-received PI films or water-treated PI films, positive and negative homo space charges were observed near the respective electrodes at 333 K. In dried PI films, the homo space charges were much reduced, and positive and negative hetero space charges in the bulk were clearly observed. The space charge amounts in water-treated PI films were smaller than in as-received ones, while the current density in water-treated PI film was larger than that in as-received one by two or more orders of magnitude. These suggest not only that the charge injection from the electrode is enhanced by absorbed water but also that absorbed water makes carriers mobile. The decay of space charge was also faster in water-treated PI than in as-received or dried one. This also supports the enhancement of apparent mobilities of carriers in PI by absorbed water.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.7-8
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• 2005

Silicon(Si) nanowires have been grown by thermal chemical vapor deposition using the 20h ball-milled SiO powders under controlled conditions without the catalyst. For the synthesis of Si nanowires, $Al_2O_3$ substrates were used. Current-Voltage(I-V) and photoresponses were measured for the single Si nanowire in vacuum at room temperature. The light sources for these measurements were the 325 nm wavelength line from a He-Cd laser and the 633 nm wavelength line from a He-Ne laser. The intensity of the photoresponse is independent of the illumination time. And rise and decay times of the photoresponses are shorter than 1 sec.