• Korean Journal of Remote Sensing
• /
• v.25 no.6
• /
• pp.501-505
• /
• 2009

Quasi-linear bright features persistently appeared on ENVISAT ASAR images as well as X-SAR images along the tidal channels in Gyung-Gi Bay, Korea during the ebb tides. These features are induced by spatial backscatter variations caused by surface convergence (divergence) through the interaction between tidal currents and bathymetry. In order to validate this mechanism, a numerical tidal model simulation is performed on the realistic bathymetry with the tidal boundary conditions. The tide model reproduces the current convergence zone along the tidal channel during the ebb tides, which exactly coincides with the location of bright line features on SAR images.

• Current Optics and Photonics
• /
• v.2 no.6
• /
• pp.595-605
• /
• 2018

The two-photon process of microscopy provides good spatial resolution and optical sectioning ability when observing quasi-static endogenous fluorescent tissue within an in vivo animal model skin. In order to extend the use of such systems, we developed a two-photon laser scanning microscopy system capable of also capturing $512{\times}512$ pixel images at 90 frames per second. This was made possible by incorporating a 72 facet polygon mirror which was mounted on a 55 kRPM motor to enhance the fast-scan axis speed in the horizontal direction. Using the enhanced temporal resolution of our high-speed two-photon laser scanning microscope, we show that rapid processes, such as fluorescently labeled erythrocytes moving in mouse blood flow at up to 1.2 mm/s, can be achieved.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.22 no.2
• /
• pp.39-52
• /
• 1994

Existing natural resources were analyzed in regional scale in order to suggest natural park guidelines as a previous step of conservation plan. Results of both existing natural resources and land potentiality in preceding paper were combined to suggest comprehensive and qualitative method for understanding of natural land. Regional characteristics of natural park were, then, analyzed by this method, and specific planning guidelines were discussed. The existing natural resources were analyzed by the degree of location quotient, which were found by comparison of the grade of vegetation naturalness and the bio-physical land unit in preceding paper. Then, allowance of existing natural resources was identified, and importance of protection was described based on this result. The bio-physical land unit on Tokyo Province was found to be composed by smaller land units, which had a variety of relationship with grade of vegetation naturalness: from the specific(1st) to many stages(5th). This meant a characteric of each land unit. By this combined approach, the characteristics and spatial distribution of natural land were discussed in the regional scale, and characteristic of nateral park were analyzed in terms of natural location. National park were located in the land unit where both land capability and importance of portection were the 6th. Quasi national park and 1 province natural park were located in the land unit where land capability was the 6th and importance of protection were the 5th. Seven province natural parks were located in the land unites were both criteria under the 5th were mixed. based on the results of this study, the followings were suggested for specific planning guidelines in the case of Takao quasi nation park: (a) conservative land use within the limit of carrying capacity of this area by the conservation of biotic and abiotic natural resources, (b) conservation of both natural and semi-natural vegetation, (c) utilization of this area as a urban forest.

• Journal of the Korean Association of Geographic Information Studies
• /
• v.11 no.3
• /
• pp.52-67
• /
• 2008

Recently, frequent occurrence of flash floods caused by climactic change has necessitated prompt and quantitative prediction of precipitation. In particular, the usability of rainfall radar that can carry out real-time observation and prediction of precipitation behavior has increased. Moreover, the use of distributed hydrological model that enables grid level analysis has increased for an efficient use of rainfall radar that provides grid data at 1km resolution. The use of distributed hydrologic model necessitates grid-type spatial data about target basins; to enhance reliability of flood runoff simulation, the use of visible and precise data is necessary. In this paper, physically based $Vflo^{TM}$ model and ModClark, a quasi-distributed hydrological model, were used to carry out flood runoff simulation and comparison of simulation results with data from Imjin River Basin, two-third of which is ungauged. The spatial scope of this study was divided into the whole Imjin River basin area, which includes ungauged area, and Imjin River basin area in South Korea for which relatively accurate and visible data are available. Peak flow and lag time outputs from the two simulations of each region were compared to analyze the impact of uncertainty in topographical parameters and soil parameters on flood runoff simulation and to propose effective methods for flood runoff simulation in ungauged regions.

• Journal of Cadastre & Land InformatiX
• /
• v.49 no.1
• /
• pp.157-179
• /
• 2019

The Seoul's 2030 Youth-Housing has been regarded as the only option to procure rental housing sites in downtown Seoul. But its supply did not catch up with the initial expectation, and the criticism that it may disrupt the current zoning system of the city has persisted. Consequently, the 2030 Youth-Housing policy has undergone amendments for six times within the last three years, and the significant changes in its guideline also have been made within the last one year. The study, in this context, tries to figure out the tendencies of those changes made in the guidelines so far by analyzing the aspects of the parcels allowable for Youth-Housing as well as the areas allowable for up-zoning. In the process, the propositional logic is to be adopted to draw the scope of the buildable areas for Youth-Housing. For this, the study refines the raw GIS data, inputs the values for each proposition, and proceeds the logical operation to judge every parcel of the city to discern whether it is eligible for a buildable site and/or for up-zoning for Youth-Housing. It is seen that: 1) the buildable sites rather evenly distribute around the peripheral subway-station areas while more concentrating on the quasi-residential and commercial areas; and 2) the areas eligible for up-zoning have the tendency to concentrate more on quasi-residential areas than others.

• Journal of the Architectural Institute of Korea Planning & Design
• /
• v.35 no.5
• /
• pp.73-83
• /
• 2019

The purpose of this study is to analyze the spatial transformational patterns according to the spectator and the exhibition environment and to examine the role of 'the middle space' organically linking the exhibition space with MoA which is a representative example of 'sequential exhibition space'. The concept of sequential exhibition space in MoA is applied not only to building but also to extended continental concepts including neighborhood. MoA's exhibition space consists of the library area and the exhibition area. In particular, the spaces of library area perform a complex function as a quasi-exhibition space, and the exhibition spaces have variable spatial transformation through an associated structure of the library area and the educational area. The types of exhibition space those constitute the sequential exhibition space of MoA appear as 'Room type', 'Free plan type', and 'Gallery type'. Each exhibition space maintains independence, but it is changed according to the situation of exhibition. The flow is based on the spiral induction around the central void space, but with selective circulation considering the visitors. Therefore, through the transformation of the exhibition area and the division of the flow, the whole museum space appears as the area differentiation.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.11 no.10
• /
• pp.4865-4886
• /
• 2017

The user experience of practical indoor power line communication (PLC) applications is greatly affected by the system quality-of-service (QoS) criteria. With a general broadcast-and-multi-access (BMA) relay scheme, in this work we investigate the joint source and relay power optimization of the amplify-and-forward (AF) relay systems used under indoor broad-band PLC environments. To achieve both time diversity and spatial diversity from the relay-involved PLC channel, which is time-varying in nature, the source node has been configured to transmit an identical message twice in the first and second signalling phase, respectively. The QoS constrained power allocation problem is not convex, which makes the global optimal solution is computationally intractable. To solve this problem, an alternating optimization (AO) method has been adopted and decomposes this problem into three convex/quasi-convex sub-problems. Simulation results show the fast convergence and short delay of the proposed algorithm under realistic relay-involved PLC channels. Compared with the two-hop and broadcast-and-forward (BF) relay systems, the proposed general relay system meets the same QoS requirement with less network power assumption.

• Journal of Magnetics
• /
• v.21 no.3
• /
• pp.450-459
• /
• 2016

Experimental results and data of numerical simulations are presented, concerning generation of wideband radio frequency (RF) oscillations in a nonlinear transmission line (NLTL) which contains a pre-magnetized core of ferrite material. Emphasis is made on the means for extracting the RF signal from the line, in order to radiate it into free space. Antennas of two types that can be used for the purpose are considered, both featuring a coaxial design. This permits availing of the principal advantages of coaxial systems, such as operation in the mode of a traveling TEM wave; wide range of the transmitted frequencies, and a reasonably simple design. The antennas studied, specifically a disc-cone dipole (DCD) and an impulse reflector antenna ('Half-IRA', or HIRA type) differ significantly in effective width of the radiated spectrum and in spatial characteristics of the radiated field in far region.

• Journal of The Korean Astronomical Society
• /
• v.44 no.2
• /
• pp.49-58
• /
• 2011

We calculate the energy spectra of cosmic ray (CR) protons and electrons at a plane shock with quasi-parallel magnetic fields, using time-dependent, diffusive shock acceleration (DSA) simulations, including energy losses via synchrotron emission and Inverse Compton (IC) scattering. A thermal leakage injection model and a Bohm type diffusion coefficient are adopted. The electron spectrum at the shock becomes steady after the DSA energy gains balance the synchrotron/IC losses, and it cuts off at the equilibrium momentum $p_{eq}$. In the postshock region the cutoff momentum of the electron spectrum decreases with the distance from the shock due to the energy losses and the thickness of the spatial distribution of electrons scales as $p^{-1}$. Thus the slope of the downstream integrated spectrum steepens by one power of p for $p_{br}$ < p < $p_{eq}$, where the break momentum decreases with the shock age as $p_{br}\;{\infty}\;t^{-1}$. In a CR modified shock, both the proton and electron spectrum exhibit a concave curvature and deviate from the canonical test-particle power-law, and the upstream integrated electron spectrum could dominate over the downstream integrated spectrum near the cutoff momentum. Thus the spectral shape near the cutoff of X-ray synchrotron emission could reveal a signature of nonlinear DSA.

• Journal of computational fluids engineering
• /
• v.6 no.4
• /
• pp.26-34
• /
• 2001

The flow past a circular cylinder forced to vibrate transversely is numerically simulated by solving the two-dimensional Navier-Stokes equations modified by the vibration velocity of a circular cylinder at a Reynolds number of 164. The higher-order finite difference scheme is employed for the spatial discretization along with the second order Adams-Bashforth and the first order backward-Euler time integration. The calculated cylinder vibration frequency is between 0.60 and 1.30 times of the natural vortex-shedding frequency. The calculated oscillation amplitude extends to 25% of the cylinder diameter and in the case of the lock-in region it is 60%. It is made clear that the cylinder oscillation has influence on the wake pattern, the time histories of the drag and lift forces, power spectral density and phase diagrams, etc. It is found that these results include both the periodic (lock-in) and the quasi-periodic (non-lock-in) state. The vortex shedding frequency equals the driving frequency in the lock-in region but is independent in the non-lock-in region. The mean drag and the maximum lift coefficient increase with the increase of the forcing amplitude in the lock-in state. The lock-in boundaries are also established from the present direct numerical simulation.