• Macromolecular Research
• /
• v.10 no.1
• /
• pp.2-12
• /
• 2002

The small-angle X-ray scattering (SAXS) beamline BL4C1 at the 2.5 GeV storage ring of the Pohang Accelerator Laboratory (PAL) has been in its first you of operation since August 2000. During this first stage it could meet the basic requirements of the rapidly growing domestic SAXS user community, which has been carrying out measurements mainly on various polymer systems. The X-ray source is a bending magnet which produces white radiation with a critical energy of 5.5 keV. A synthetic double multilayer monochromator selects quasi-monochromatic radiation with a bandwidth of ca. 1.5%. This relatively low degree of monochromatization is sufficient for most SAXS measurements and allows a considerably higher flux at the sample as compared to monochromators using single crystals. Higher harmonics from the monochromator are rejected by reflection from a flat mirror, and a slit system is installed for collimation. A charge-coupled device (CCD) system, two one-dimensional photodiode arrays (PDA) and imaging plates (IP) are available its detectors. The overall performance of the beamline optics and of the detector systems has been checked using various standard samples. While the CCD and PDA detectors are well-suited for diffraction measurements, they give unsatisfactory data from weakly scattering samples, due to their high intrinsic noise. By using the IP system smooth scattering curves could be obtained in a wide dynamic range. In the second stage, stating from August 2001, the beamline will be upgraded with additional slits, focusing optics and gas-filled proportional detectors.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.480-480
• /
• 2008

Vacuum circuit breaker(VCB) is now emerging as an alternative of gas circuit breaker(GCB) which uses SF6 gas as insulating material whose dielectric strength is outstanding. But we have to reduce SF6 gas because SF6 gas is one of greenhouse gas and efforts to reduce greenhouse gas are now trend of the world. Therefore, we can say VCB is the optimal alternative of GCB because vacuum is environmentally friendly. The vacuum interrupter is the core part of VCB to interrupt arcing current. There are mainly two methods to extinguish arc. One is radial magnetic field (RMF) method and the other is axial magnetic field (AMF) method. We deals with RMF method in this paper. Compared with AMP, RMF arc quenching method has different principle to extinguish arc. In case of RMF method, pinch effect is much larger than AMF method. Because of pinch effect RMF type contact electrodes have the single large spot which is severly damaged and melted while AMF type contact electrodes have small and multiple spots which are slightly damaged and melted. To prevent contact electrode being damaged and melted from high temperature-arc, RMF method uses Lorentz force to move arc. In this paper we calculated and compared the arc driving force of two cases and we analyzed the force acting on each part of arc by means of commercial finite element method software Maxwell 3D. They have 3petals and we considered two cases. One is the case when fixed(upper) and movable(lower) contacts are in mirror arrangement (Case 1). The other is the case when one of two contacts (movable contact) is revolved at maximum angle as possible as it can be (Case 2). And at each case above, we analyzed arc driving force at two positions, position 1 is the closest to the center of contact and position 2 is near the edge of petal on fixed contact. As a result we could find that Case 2 generated stronger arc driving force than Case 1 at position 1. But at position 2 Case 1 generated stronger arc driving force than Case 2. This simulation method can contribute to optimizing spiral-type electrode designs in a view of arc driving force.

• Korean Journal of Remote Sensing
• /
• v.39 no.6_1
• /
• pp.1389-1399
• /
• 2023

KOMPSAT-3/3A (K3/K3A) absolute radiometric calibration study was conducted based on a Field Line of sight Automated Radiance Exposure (FLARE) system. FLARE is a system, which has been developed by Labsphere, Inc. adopted a SPecular Array Radiometric Calibration (SPARC) concept. The FLARE utilizes a specular mirror target resulting in a simplified radiometric calibration method by minimizing other sources of diffusive radiative energies. Several targeted measurements of K3/3A satellites over a FLARE site were acquired during a field campaign period (July 5-15, 2021). Due to bad weather situations, only two observations of K3 were identified as effective samples and they were employed for the study. Absolute radiometric calibration coefficients were computed using combined information from the FLARE and K3 satellite measurements. Comparison between the two FLARE measurements (taken on 7/7 and 7/13) showed very consistent results (less than 1% difference between them except the NIR channel). When additional data sets of K3/K3A taken on Aug 2021 were also analyzed and compared with gain coefficients from the metadata which are used by current K3/K3A, It showed a large discrepancy. It is assumed that more studies are needed to verify usefulness of the FLARE system for the K3/3A absolute radiometric calibration.

• Journal of the Korean Geographical Society
• /
• v.42 no.5
• /
• pp.808-834
• /
• 2007

This study attempts to elucidate manifold dimensions of gendered accessibility experiences. How gender roles(household responsibilities) differentiate accessibility experiences between women and men is explored through the comparison of married dual-earner couples' parental status, using the US Portland activity-travel diary dataset with GIS-based geocomputation results of(time-geography based) space-time accessibility. First, this study shows how gender division of labor within the household still permeates current society, despite the widespread belief of the social change toward a gender-egalitarian society. Then, the study pays special attention to the way gender roles structure individual accessibility experiences of women and men differently, and, in turn, the way such accessibility experiences take a form of gendered spatiality. Gendered spatiality is examined through the analysis of accessibility space as well as activity space in order to ascertain women's home-attached and spatially entrapped characteristics. More household responsibilities throughout a day and, even more, the time constraint of picking up children at the daycare centers after work lead women's possible activity space to be more home-centered. The analysis of the spatio-temporal context of accessibility space makes gendered spatiality visible. However, the findings suggest that behavioral outcomes should be understood with an explicit awareness of constraints individuals face. It is because the revealed activity spaces can be not only an outcome of constraint but also an outcome of choice. Behavioral outcomes should not be treated as a straightforward expression of the level of constraints. It is problematic to expect that behavioral outcomes directly mirror the level of constraints. It is also problematic to suppose that the level of constraints can be straightforwardly elicited from revealed behavioral outcomes.