• Journal of the Korean Ceramic Society
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• v.53 no.3
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• pp.367-375
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• 2016

A novel strategy for the synthesis of $CoSb_2$ nanoparticles is demonstrated via preparation of novel organometallic complexes. Hydrated cobalt oleate (CoOl) and non-hydrated antimony oleate (SbOl) complexes are synthesized as precursors. The $CoSb_2$ nanoparticles are prepared by hot injection, which involves thermolysis of CoOl and SbOl in a non-coordinating solvent at $320^{\circ}C$. The coordination modes and distinct thermal behaviors of the intermediate non-hydrated SbOl complexes are comparatively investigated by thermo-analytical techniques. When the reaction temperature is increased, the particle size is found to increase linearly. The crystallinity of the $CoSb_2$ nanoparticles prepared at $250^{\circ}C$ is amorphous phase without any peaks. $CoSb_2$ structural peaks start to appear at $300^{\circ}C$ and dominant peaks with high crystallinity are synthesized at $320^{\circ}C$. The potential chemical structures of non-hydrated SbOl and their reaction mechanisms by thermolysis are elucidated. The elemental composition and crystallographic structure of $CoSb_2$ nanoparticles suggest a bimodal interaction of the organic shell and the nanoparticle surface, with a chemical absorbed inner layer and physically absorbed outer layer of carboxylic acid.

• Journal of Environmental Science International
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• v.29 no.1
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• pp.79-93
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• 2020

To determine the size distributions of water-soluble inorganic ionic species (WSIS) in roadside aerosols, sampling experiments were carried out in the urban roadside area of Jeju City on August 2018 and January 2019 by using the eight-stage cascade impactor sampler. The mass of roadside aerosols were partitioned at 57% in fine fraction, 36-37% in coarse fraction, and 6-7% in giant fraction, regardless of summer and winter. The mass concentrations of WSIS except for Na+ and SO42- in roadside aerosols were higher in winter than in summer. The size distributions of Na⁺, Mg²⁺, Ca²⁺ and Cl^- were characterized by bimodal types with coarse particle mode peaking around 3.3-4.7 ㎛ and 5.8-9.0 ㎛. The size distributions of NO₃^- and K⁺ shifted from a single fine mode peaking around 0.7-1.1 ㎛ in winter to bimodal and/or trimodal types with peaks around coarse mode in summer. SO₄^2- and NH₄⁺ showed a single fine mode peaking around 0.7-1.1 ㎛. The MMAD of roadside aerosols was lower than that of Na⁺, Mg²⁺, Ca²⁺ and Cl-. Based on the marine enrichment factors and the ratio values of WSIS and the corresponding value for sea water, the composition of roadside aerosols in Jeju City may be practically affected by terrestrial sources rather than marine source.

• Korean Journal of Environmental Biology
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• v.19 no.2
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• pp.153-157
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• 2001

The relationship between SPM (Suspended Particulate Matter) and fungal spore in the air was investigated in Seosan, a rural county of Korea, in spring of 2000. SPM concentrations in the air were $199.8\mu{g}\;m^{-3}$, in the 1st Yellow Sand Period (March, 23-24), $249.4\mu{g}\;m^{-3}$ in the 2nd Yellow Sand Period (April, 7-9) and $98.9\mu{g}\;m^{-3}$ in the Non Yellow Sand Period (May, 12-16), respectively. Although there was somewhat difference in total SPM concentration between the two Yellow Sand Periods, majority of the total SPM were composed of $5\mu{m}$ sized coarse particles over the two periods. However, fine particles sized about $1\mu{m}$and coarse particles sized about $5-6\mu{m}$ ultimately showed peaks, which was within typical bimodal pattern at the graph of SPM size distribution in the Non Yellow Sand Period. Four mold genera grown from airborne fungal spores were finally identified in full-grown colonies at the SPM samples during the Yellow Sand Periods. These genera were Fusarium, Aspergillus, Penicillium and Basipetospora.

• Annals of Clinical Neurophysiology
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• v.7 no.1
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• pp.7-12
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• 2005

Background: Essential tremor (ET) is a common movement disorder that often causes functional disability. There have been very few investigations about the clinical characteristics of ET in Korea. Therefore, we performed a study showing the clinical features and electrophysiological findings of ET. Methods: We analyzed medical records and accelerometry data of 152 patients (male vs female; 79 vs 73) with ET, who visited the Neurology Clinic of Hospital from 2000 to 2003. Clinical characteristics of ET were summarized including the age of onset, family history, tremor type, body part involved, and associated symptoms. The frequency of tremor was recorded and the spectral analysis of tremor was performed. Results: The age of tremor onset showed bimodal distribution with peaks in the 2nd and 5th decades. Family history was found in 46 patients (30.3%). The patients with the family history presented earlier onset of tremor than patients without the history (mean age of onset, y: 35.2 vs. 49.9, P < 0.001). Tremor appeared most frequently in hands (94%), and followed by head (25%). In head tremor, "no-no" pattern was mainly observed and the head tremor was more frequently observed in female. The frequency of tremor was negatively correlated with age (r=-0.49, P<0.001). Conclusions: The present study indicated some important findings about ET: (1) bimodal distribution for an age of onset, (2) younger age of onset in patients with a family history, (3) decreasing frequency of the tremor according to age, and (4) higher prevalence of head tremor in female patients.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.2 no.3
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• pp.119-127
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• 1990

Wave directional spectrum estimation methods for irregular waves were considered in this study. Until now, the Longuet-Higgins Method (LHM) initiated by Longuet-Higgins et al. (1963) has been widely used, but resolutions of the estimation were found to be low. Kobune's Maximum Entropy Method (MEM) for the estimation of wave directional spectrum, bas-ed on the entropy Principle showed higher resolutions comparing with the LHM . If the wave directional spectrum is of Delta functions, the MEM is exact in its estimation. It was also found that for a unimodal spectrum, if the Mitsuyasu's spreading coefficient is above 5, the estimation resolutions were high. In bimodal spectrum, as the angle difference between the two peaks increased, the resolution improved. The energy seems to transfer to the smoother peak in the smoothing of peak's peakedness. LHM has a tendency to estimate bimodal spectrum as a unimodal spectrum ； thus, except for its computational speed, the resolution of LHM falls far below that of MEM.

• Korean Journal of Food Science and Technology
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• v.21 no.1
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• pp.80-85
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• 1989

The structural properties of covered and naked barley starches and those components were investigated. ${\beta}-amylosis\;limit(%)$ of covered and naked barley starches were 58.6 and 56.3%, respectively and those of their amyloses and amylopectins were 87.0, 77.7, 57.6 and 52.0%, respectively. The ratios of outer chain length ${\overline{OCL}}$ and inner chain length${\overline{ICL}}$ for amylopectins of covered and naked barley were about 2.2:1 and 2.0:1, respectively. The elution curves by Sephadex G-75 after debranching starches with pullulanase were similar patterns for two starches and yielded two peaks consisting of amylose component${\overline{dp}}>55$ and bimodal amylopectin components of ${\overline{dp}_(35-45)$ and ${\overline{dp}}(10-20)$ hydrolysates. Also, hydrolysis products by sequential hydrolysis with pullulanase and ${\beta}-amylase$ contained 0.03-0.5% non-hydrolyzed peak components of ${\overline{dp}}>55$. The elution profiles of ${\beta}-amylase$ hydrolysates yielded two peaks consisting of the inner components${\overline{dp}}>55$ and the outer chain components of amylopectin${\overline{dp}}>10$ regardless of samples. However, ${\overline{dp}}$ distributions of ${\overline{dp}>55}$ hydrolysates exhibited the significant differences due to the varieties.

• Journal of Ecology and Environment
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• v.45 no.2
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• pp.88-96
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• 2021

Background: Sika deer, Cervus nippon, were originally introduced to South Korea from Japan and Taiwan for commercial farming purposes. Unfortunately, they were released into the wild during religious events and have since begun to impact the native ecosystem and species endemic to South Korea. The study of activity patterns can improve our understanding of the environmental impact of non-native species and their association with sympatric species. Using camera traps, we studied the diel and seasonal activity patterns of non-native sika deer and quantified the temporal overlap with sympatric mammalian species in the Muljangori-oreum wetlands of Hallasan National Park, South Korea. Results: A total of 970 trap events were recorded for five mammalian species from nine locations during the camera-trap survey. Siberian roe deer (Capreolus pygargus tianschanicus) had the highest number of recorded events (72.0%), followed by sika deer (Cervus nippon) (16.2%), wild boar (Sus scrofa) (5.0%), Asian badger (Meles leucurus) (4.5%), and the Jeju weasel (Mustela sibirica quelpartis) (2.0%). Sika deer had bimodal activity patterns throughout the year, with peaks throughout the spring-autumn twilight, and day and night time throughout the winter. Relating the daily activity of sika deer with other mammalian species, roe deer expressed the highest degree of overlap (Δ₄ = 0.80) while the Asian badger demonstrated the lowest overlap (Δ₄ = 0.37). Conclusions: Our data show that sika deer are a crepuscular species with seasonal variations in daily activity patterns. Additionally, we identified the temporal differences in activity peaks between different mammals in the Muljangori-oreum wetlands and found higher degree of overlap between sika deer and roe deer during twilight hours.

• Journal of Korean Society for Atmospheric Environment
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• v.22 no.E2
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• pp.78-88
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• 2006

In order to study the characteristics of cloud, a real-scale experiment for cloud generation was carried out using an extinct vertical mine (430 m height) located in the northeastern Honshu, Japan. The dry particles generated from the three-step concentrations of NaCl solutions were used for cloud generation. The number size distributions of initial dry particles and cloud droplets were monitored by Scanning Mobility Particle Sizer (SMPS) and Forward Scattering Spectrometer Probe (FSSP) at bottom and upper sites of pit, respectively. The polymeric water absorbent film (PWAF) method was employed to measure liquid water content ($W_L$) as a function of droplet size. Moreover the chemical properties of individual droplet replicas were determined by micro-PIXE. The CCN number concentration shows the lognormal form in dependence of the particle size, while the number size distributions of droplets are bimodal showing the peaks around $9{\mu}m$ and $20{\mu}m$ for every case. In comparison to background mineral particles, right shifting of size distribution line for NaCl particles was occurred. When NaCl solutions with three-step different concentrations were neulized, $W_L$ shows the strong droplet size dependence. It varied from $10.0mg\;m^{-3}$ up to $13.6mg\;m^{-3}$ with average $11.6mg\;m^{-3}$. A good relationship between $W_L$ and cloud droplet number concentration was obtained. Both chemical inhomogeneities (mixed components with mineral and C1) and homogeneities (only mineral components or C1) in individual droplet replicas were obviously observed from micro-PIXE elemental images.

• The Korean Journal of Cytopathology
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• v.7 no.1
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• pp.23-30
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• 1996

Chromatin texture, which partly reflects nuclear organization, is evolving as an important parameter indicating cell activation or transformation. In this study, chromatin pattern was evaluated by image analysis of the electron micrographs of follicular and papillary carcinoma cells of the thyroid gland and tested for discrimination of the two neoplasms. Digital grey images were converted from the electron micrographs, nuclear images, excluding nucleolus and intranuclear cytoplasmic inclusions, were obtained by segmentation; grey levels were standardized; and grey level histograms were generated. The histograms in follicular carcinoma showed Gaussian or near-Gaussian distribution and had a single peak, whereas those in papillary carcinoma had two peaks(bimodal), one at the black zone and the other at the white zone. In papillary carcinoma, the peak in the black zone represented an increased amount of heterochromatin particles and that at the white zone represented decreased electron density of euchromatin or nuclear matrix. These results indicate that the nuclei of follicular and papillary carcinoma cells differ in their chromatin pattern and the difference may be due to decondensed chromatin and/or matrix substances.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.48 no.5
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• pp.752-759
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• 2015

We examined the feeding habits of larval Konosirus punctatus using 165 specimens collected from May to August 2011 in the Nakdong River estuary, Korea. We found that larval K. punctatus [3.9-8.4 mm notochord length (NL)] are carnivorous, consuming mainly rotifers. Their diet also included small numbers of rhizopods, tintinnids, euglenoids, copepods, larval bivalves, dinoflagellates, diatoms, and unidentified materials. To evaluate ontogenetic changes in dietary composition, we split the larvae into three size groups: < 5 mm, 5-6 mm, and > 6 mm NL. The smallest size group frequently preyed on rhizopods. As NL increased, the number of rotifers increased relative to those of rhizopods. Larvae also showed bimodal feeding for feeding incidence, with peaks in the midafternoon and at midnight, while the mean number of prey per individual peaked at 18:00-19:00 h.