• Ocean and Polar Research
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• v.45 no.2
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• pp.57-69
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• 2023

Growth responses along the gradient of water temperature, salinity, and light intensity and cytotoxicity against Artemia nauplii were explored using Ostreopsis sp. and Coolia canariensis strains, representing the two potentially toxic epiphytic dinoflagellate (EPD) species from Jeju coastal waters of Korea. Variation in maximum growth rate (GRmax) and maximum biomass yield (Ymax) along the environmental gradients was quite contrasting between the two strains, which appears to be reflected in the in situ abundance distribution of the corresponding genera. The more eurythermal characteristics of Ostreopsis sp. strain were in good agreement with the relative distribution of Ostreopsis spp. and Coolia spp. in 520 macroalgal samples collected from 6 stations. The more stenohaline C. canariensis strain was well matched by a markedly narrower range of salinities in the in situ distribution of Coolia spp. than the salinity range for Ostreopsis species. The differences in light adaptation between the high light-preferring Ostreopsis sp. strain and the more euryphotic C. canariensis strain were remarkably consistent with the distinct vertical profiles of Ostreopsis spp. and Coolia spp. abundance in the red alga Amphiroa sp. off Moom-seom. Cytotoxicity against Artemia nauplii in the Ostreopsis sp. preparation with 1000 cells ml^-1 was similar to that in C. canariensis preparation with 12000 cells ml^-1, which is noteworthy. Thus, the new potential cytotoxicity risks from C. canariensis along with the well-known toxic genus Ostreopsis may be introduced to Jeju coasts, which necessitates further exploration into the contrasting ecological niches occupied by EPD species in relation to their cytotoxicity.

• Journal of The Korean Astronomical Society
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• v.53 no.3
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• pp.59-67
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• 2020

We propose semi-analytic models for the electron momentum distribution in weak shocks that accounts for both in situ acceleration and re-acceleration through diffusive shock acceleration (DSA). In the former case, a small fraction of incoming electrons is assumed to be reflected at the shock ramp and pre-accelerated to the so-called injection momentum, p_inj, above which particles can diffuse across the shock transition and participate in the DSA process. This leads to the DSA power-law distribution extending from the smallest momentum of reflected electrons, p_ref, all the way to the cutoff momentum, p_eq, constrained by radiative cooling. In the latter case, fossil electrons, specified by a power-law spectrum with a cutoff, are assumed to be re-accelerated from p_ref up to p_eq via DSA. We show that, in the in situ acceleration model, the amplitude of radio synchrotron emission depends strongly on the shock Mach number, whereas it varies rather weakly in the re-acceleration model. Considering the rather turbulent nature of shocks in the intracluster medium, such extreme dependence for the in situ acceleration might not be compatible with the relatively smooth surface brightness of observed radio relics.

• Environmental Engineering Research
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• v.25 no.3
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• pp.281-289
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• 2020

Environmental fate of ionizable organic pollutants such as perfluoroalkyl acids (PFAAs) are of increasing interest but has not been well understood because of uncertain values for parameters related with atmospheric interphase partitioning behavior. In the present study, not only the values for air-water partition coefficient (K_AW) and dissociation constant (pKa) of PFAAs were induced by adjusting to in situ measurements of air-water distribution coefficient between vapor phase and rainwater but also gas-particle partition coefficients were also estimated using three-phase partitioning model of ionizable organic pollutants, in situ measurements of PFAAs in aerosol and air vapor phase, and obtained parameter values. The pKa values of PFAAs we obtained were close to the minimum values suggested in literature except for perfluorooctane sulfonic acids, and COSMOtherm-modeled K_AW values were assessed to more appropriate among suggested values. When applying parameter values we obtained, it was predicted that air particle-associated fate and transport of PFAAs could be negligible and PFAAs could distribute ubiquitously along the transection from urban to rural region by pH-dependent phase transfer in air. Our study is expected to have some implications in prediction of the environmental redistribution of other ionizable organic compounds.

• Journal of the Korean Society of Radiology
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• v.83 no.4
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• pp.898-903
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• 2022

The incidence of ductal carcinoma in situ has increased with the rise in screening mammography; currently, ductal carcinoma in situ constitutes 20%-25% of all breast cancers, and up to half of them may become invasive. Its early detection is critical in improving the cure rate. Moreover, MRI has higher sensitivity for its detection than mammography. Herein, we report an unusual case of ductal carcinoma in situ presenting as a continuous, serpentine, linear enhancement with regional distribution on MRI.

• Journal of Radiation Protection and Research
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• v.43 no.3
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• pp.85-96
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• 2018

Background: A variety of inorganic scintillators have been developed and improved for use in radiation detection and measurement, and in situ gamma-ray spectrometry in the environment remains an important area in nuclear safety. In order to verify the feasibility of promising scintillators in an actual environment, a performance test is necessary to identify gamma-ray peaks and calculate the radioactivity from their net count rates in peaks. Materials and Methods: Among commercially available scintillators, $LaBr_3(Ce)$ scintillators have so far shown the highest energy resolution when detecting and identifying gamma-rays. However, the intrinsic background of this scintillator type affects efficient application to the environment with a relatively low count rate. An algorithm to subtract the intrinsic background was consequently developed, and the in situ calibration factor at 1 m above ground level was calculated from Monte Carlo simulation in order to determine the radioactivity from the measured net count rate. Results and Discussion: The radioactivity of six natural radionuclides in the environment was evaluated from in situ gamma-ray spectrometry using an $LaBr_3(Ce)$ detector. The results were then compared with those of a portable high purity Ge (HPGe) detector with in situ object counting system (ISOCS) software at the same sites. In addition, the radioactive cesium in the ground of Jeju Island, South Korea, was determined with the same assumption of the source distribution between measurements using two detectors. Conclusion: Good agreement between both detectors was achieved in the in situ gamma-ray spectrometry of natural as well as artificial radionuclides in the ground. This means that an $LaBr_3(Ce)$ detector can produce reliable and stable results of radioactivity in the ground from the measured energy spectrum of incident gamma-rays at 1 m above the ground.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.52.1-52.1
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• 2020

We propose semi-analytic models for the electron momentum distribution in weak shocks that accounts for both in situ acceleration and reacceleration through diffusive shock acceleration (DSA). In the former case, a small fraction of incoming electrons is assumed to be reflected at the shock ramp and pre-accelerated to the so-called injection momentum, pinj, above which particles can diffuse across the shock transition and participate in the DSA process. This leads to the DSA power-law distribution extending from the smallest momentum of reflected electrons, pref, all the way to the cutoff momentum, peq, constrained by radiative cooling. In the latter case, fossil electrons, specified by a power-law spectrum with a cutoff, are assumed to be re-accelerated from pref up to peq via DSA. We show that, in the in situ acceleration model, the amplitude of radio synchrotron emission depends strongly on the shock Mach number, whereas it varies rather weakly in the re-acceleration model.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.215-222
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• 2001

Uncertainty study of shear strength characteristics of the marine clays was carried out based ell In-situ tests and laboratory tests on tile south-east coastal region of the Korean peninsula. Theoretical analyses were studied using both tile spherical cavity expansion theory in finite soil mass and the strain path method to determine tile cone factor using the undrained shear strengths obtained by in-situ tests, and the empirical methods in accordance with the ultimate resistance theory were also discussed. Analysis show that the empirical methods suggest more reasonable value than that of theoretical methods in terms of comparing the cone factor estimated using linear regression and frequency distribution analyses. The cone factors obtained by the empirical methods are 18, 15, and 6 respectively, from the results of total cone resistance, effective cone resistance, and excess porewater cone resistance method, and the estimated were similar to those of previous researcher's.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.987-990
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• 2007

The accuracy of sound strength (G) measurement method in ISO 3382 has been questioned. One of the main reason is the difficulty in measuring a reference sound level in an anechoic chamber with the same set-up which was applied for the actual hall measurements. In the present paper, an in-situ measurement method for G was proposed by investigating the present G measurement method shown in ISO 3382. In addition, the sound radiation characteristics of typical omnidirectional loudspeakers were investigated and Phi (O) of auto correlation function (ACF) parameters was also calculated from an actual music excerpt to characterize the sound energy distribution in concert halls.

• Journal of the Semiconductor & Display Technology
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• v.5 no.1 s.14
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• pp.45-49
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• 2006

In this paper, a new method that monitors the quantity of particles using ion-counter in vacuum environment is introduced. In-situ particle monitoring (ISPM) system is composed by Gerdien type ion-counter (house-made), DC power supply and electrometer. The ion-counter applied by positive voltage detects only positive charged particles. Therefore the particles to be detected should be in known charge state for further data analysis. ion-counter is installed at the exhaust line of process equipment where the pressure loss is structurally low. ISPM system performance has been verified with SMPS (Scanning Mobility Particle Sizer) system. The correlation coefficient is above 0.98 at the particle size range of $20{\sim}300nm$ in diameter with identified charge distribution under $0.1{\sim}10.0$ Torr.

• Proceedings of the Korean Geotechical Society Conference
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• 2000.03b
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• pp.167-172
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• 2000

In this study, the behaviors of a cast-in-situ concrete pile embedded in the weathered rock were analysed by a 3D numerical analysis using PENTAGON 3D and the results were compared with those of the field load test. The load-settlement relation and the load transfer relationship were evaluated from the numerical analysis. As a result, the load-settlement relation at the pile top and the axial load distribution with depth were predicted reasonably. And those results were similar with those of the field load test.