• Steel and Composite Structures
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• v.21 no.3
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• pp.517-536
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• 2016

Thick steel plate is commonly found with mega steel structures but its properties have not been fully explored. Grade Q345GJ-C steel plate with thickness ranging from 60 mm to 120 mm are studied in this paper. Both the static and cyclic performance of material in different directions (horizontal and through-thickness directions) and locations (outer surface, 1/4 thickness and mid-depth) are experimentally obtained. The accumulative damage during cyclic loading is also calculated by using bilinear mixed hardening (BMH) constitutive relationship together with the Lemaitre's damage model. Results show that the static properties are better at the outer surface of thick steel plates than those at mid-depth. Properties in through-thickness direction are similar to those at mid-depth in the horizontal direction. The cyclic performance at different locations of a given plate is similar within the range of strain amplitude studied. However, when damage parameters identified from monotonic tensile tests are included in the numerical simulation of cyclic loading tests, damage is found accumulating faster at mid-depth than close to outer surface.

• Korean Journal of Remote Sensing
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• v.38 no.4
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• pp.343-353
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• 2022

An attempt to derive the surface temperature from the Korea Multi-purpose Satellite (KOMPSAT)-3A mid-wave infrared (MWIR) data acquired over the southern California on Nov. 14, 2015 has been made using the MODerate resolution atmospheric TRANsmission (MODTRAN) radiative transfer model. Since after the successful launch on March 25, 2015, the KOMPSAT-3A spacecraft and its two payload instruments - the high-resolution multispectral optical sensor and the scanner infrared imaging system (SIIS) - continue to operate properly. SIIS uses the MWIR spectral band of 3.3-5.2 ㎛ for data acquisition. As input data for the realistic simulation of the KOMPSAT-3A SIIS imaging conditions in the MODTRAN model, we used the National Centers for Environmental Prediction (NCEP) atmospheric profiles, the KOMPSAT-3Asensor response function, the solar and line-of-sight geometry, and the University of Wisconsin emissivity database. The land cover type of the study area includes water,sand, and agricultural (vegetated) land located in the southern California. Results of surface temperature showed the reasonable geographical pattern over water, sand, and agricultural land. It is however worthwhile to note that the surface temperature pattern does not resemble the top-of-atmosphere (TOA) radiance counterpart. This is because MWIR TOA radiances consist of both shortwave (0.2-5 ㎛) and longwave (5-50 ㎛) components and the surface temperature depends solely upon the surface emitted radiance of longwave components. We found in our case that the shortwave surface reflection primarily causes the difference of geographical pattern between surface temperature and TOA radiance. Validation of the surface temperature for this study is practically difficult to perform due to the lack of ground truth data. We therefore made simple comparisons with two datasets over Salton Sea: National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory (JPL) field data and Salton Sea data. The current estimate differs with these datasets by 2.2 K and 1.4 K, respectively, though it seems not possible to quantify factors causing such differences.

• The Bulletin of The Korean Astronomical Society
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• v.44 no.2
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• pp.68.4-68.4
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• 2019

In this poster, we present a relation between the Galactic foregrounds and Galactic latitude to study the structure of the Galactic foregrounds. We propose that the standard deviation of observed values along a line of sight with Galactic latitude b ('σ_l.o.s') is inversely proportional to ${\sqrt{sin{\mid}b{\mid}}}$. To confirm this, we use synchrotron intensity data from the Planck archive and rotation measure (RM) data from the NVSS. We divided the sphere of the Galactic coordinate into bins with a constant surface area and calculated the average of standard deviation along Galactic latitude ('σ_lat'). We compared σ_lat ${\sqrt{sin{\mid}b{\mid}}}$ with σ_lat along Galactic latitude and found that σ_lat ${\sqrt{sin{\mid}b{\mid}}}$ is the most constant. These results support that the relation is reasonable.

• Journal of Korean Society for Atmospheric Environment
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• v.13 no.2
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• pp.103-113
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• 1997

The research described in this paper was conducted to estimate the stability and heat budget in planetary boundary layer (PBL) at Kimhae. The upper air observation was carried out during period from 3 Februsry 1993 to 5 February 1993 at Kimhae. The surface observation data used the one during period from 1 April 1994 to 31 March 1995. The maximum height of inversion layer observed at Kimhae was 310 m. Destruction of the inversion was simultaneously occurred at the surface and the mid-layer (200 $\sim$ 300 m), however the origin of destruction is different each other. The surface inversion is destructed by surface heating owing to growing radiation in surface but disappearance of the mid-layer inversion is related to the upper cold air movement.

• Korean Journal of Mathematics
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• v.23 no.3
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• pp.439-446
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• 2015

In this paper we consider the meromorphic function G(z) with a pole of order 1 at -a and analytic function F(z) with a zero -a of order 2 in $\mathbb{D}=\{z :{\mid}z{\mid}<1\}$, where -1 < a < 1. From these functions we obtain the regular simply-connected minimal surface $S=\{(u(z),\;{\nu}(z),\;H(z)):z{\in}\mathbb{D}\}$ in $E^3$ and the harmonic function $f=u+i{\nu}$ defined on $\mathbb{D}$, and then we investigate properties of the minimal surface S and the harmonic function f.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.5
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• pp.982-988
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• 2009

In a surface type ac PDP having $200{\mu}m$ gap between the surface electrodes, the luminous efficacy has a reciprocal dependence on the sustaining frequency. The discharge current flowing to the address electrodes are measured to investigate the phenomena and spectral intensity from visible light to infra red is measured to verify phosphor saturation with the frequency. Experiments show the discharge between the address and surface electrodes deteriorates the efficacy in high sustaining frequencies. Pulse width modulation is introduced to improve the efficacy. In optimum conditions, we obtained 1.99lm/w and 1.79lm/w at 200kHz and 250kHz, respectively.

• Korean Journal of Materials Research
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• v.25 no.12
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• pp.690-693
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• 2015

Fatigue crack growth experiments were carried out on a 304 L stainless steel compact-tension(CT) specimen under load control mode. Neutron diffraction was employed to quantitatively measure the residual strains/stresses and the evolution of stress fields in the vicinity of a propagating fatigue-crack tip. Three principal stress components (i.e. crack growth, crack opening, and through-thickness direction stresses) were examined in-situ under loading as a function of distance from the crack tip along the crack-propagation path. The stress/strain fields, measured both at the mid-thickness and near the surface of the CT specimen, were compared. The results show that much higher compressive residual stress fields developed in front of the crack tip near the surface than developed at the mid-thickness area. The change of the stresses ahead of the crack tip under loading is more significant at the mid-thickness area than it is near the surface.

• Corrosion Science and Technology
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• v.13 no.5
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• pp.170-177
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• 2014

Polyurethane coating was designed to give a hydrophobic property on its surface by modifying it with hydroxyl terminated polydimethylsiloxane and then effects of surface hydrophobic tendency, water transport behavior and hence corrosion protectiveness of the modified polyurethane coating were examined using FT-IR/ATR spectroscopy, contact angle measurement and electrochemical impedance test. As results, the surface of polyurethane coating was changed from hydrophilic to hydrophobic property due primarily to a phase separation tendency between polyurethane and modifier by the modification. The phase separation tendency is more appreciable when modified by polydimethylsiloxane with higher content. Water transport behavior of the modified polyurethane coating decreased more in that with higher hydrophobic surface property. The decrease in the impedance modulus ${\mid}Z{\mid}$ at low frequency region in immersion test for polyurethane coatings was associated with the water transport behavior and surface hydrophobic properties of modified polyurethane coatings. The corrosion protectiveness of the modified polyurethane coated carbon steel generally increased with an increase in the modifier content, confirming that corrosion protectiveness of the modified polyurethane coating is well agreed with its water transport behavior.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.5
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• pp.993-998
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• 2011

In this paper we suggest new criteria for the classification of the electrode gap between common and scan electrodes. The electrode gap is categorized as a short, middle, and long gap according to the criteria. Among these structures, we focus on the erase waveform of a mid-gap structure. we report an unstable discharge arising from the erase ramp period in a mid-gap structure. Based on the Vt close curve, we analyze the unstable discharge at various conditions. Our analysis reveals that the unstable discharge is ignited between surface electrodes and caused by un-erased wall charges accumulated on the outer edges of electrodes. By reducing the voltage level of the last sustain pulse, the problem is solved.

• Communications of the Korean Mathematical Society
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• v.10 no.4
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• pp.881-887
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• 1995

Let f be a measurable function on the unit ball B in $C^n$, then we define a maximal function $M_p(f), 1 \leq p < \infty$, by $$ M_p(f)(\zeta ) = \sup_{\delta > 0}(\frac{1}{\sigma(\beta(\zeta, \delta))} \int_{T(\beta(\zeta, \delta))} $\mid$f(z)$\mid$^p \frac{d\nu(z)}{(1-$\mid$z$\mid$^n})^{1/p} $$ where $\sigma$ denotes the surface area measure on S, the boundary of B, and $T(\beta(\zeta, \delta))$ denotes the tent over the ball $\beta(\zeta, \delta)$. We prove that the maximal operator $M_p$ belongs to the Muckenhoupt class $A_1$.