• 한국세라믹학회지
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• 제53권3호
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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.

• 한국환경과학회지
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• 제29권1호
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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.

• 환경생물
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• 제19권2호
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• pp.153-157
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• 2001

2000년 춘계에 한국 농촌지역인 충남 서산에서 대기부유분진(SPM)과 곰팡이포자의 관계에 대해 조사하였다. 부유분진의 농도는 1차 황사기간(3월 23-24일)에 $199.8\mu{g}\;m^{-3}$, 2차 황사기간(4월 7-9일)에 $249.4\mu{g}\;m^{-3}$, 비황사기간(5월 12-6일)에 $98.9\mu{g}\;m^{-3}$으로 각각 나타났다. 2회의 황사기간들간에 부유분진 농도는 차이를 보였지만 $5\mu{m}$ 정도의 입경 크기를 가지는 조대분진이 2회의 황사기간 모두에서 총 부유분진 양의 대부분을 차지하였다. 그러나 비황사기간의 부유분진 입경분포 그래프는 $1\mu{m}$ 정도의 입경 크기를 가지는 미세분진과 $5-6\mu{m}$ 정도의 크기를 가지는 조대분진이 피크를 보이는 전형적인 bimodal 패턴을 나타내었다. 대기기원 곰팡이포자로부터 성장한 4종류의 사상균류가 황사시기의 부유분진 시료에서 동정되었다. 이들은 Fusarium, Aspergillus, Penicillium, Basipetospora 속으로 확인되었다.

• Annals of Clinical Neurophysiology
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• 제7권1호
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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.

• 한국해안해양공학회지
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• 제2권3호
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• pp.119-127
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• 1990

불규칙 파랑의 파향스펙트럼 추정법에 대하여 고찰하였다. 파향스펙트럼 추정이론의 근간은 Longuet-Higgins et al.(1963)이 제시한 방법으로 현재 많이 이용되고 있으나 추정정도가 매우 낮은 것으로 나타났다. 그리고 파향스펙트럼을 ［0, 2$\pi$］에서의 확률밀도함수로 간주하고 Entropy 법칙을 응용한 Kobune et al.(1986)의 최대 엔트로피법 (MEM)은 Longuet-Higgins et al.의 방법 (LHM)에 비해 파향의 분석능이 매우 좋은 것으로 나타났다. 특히 MEM은 파향스펙트럼이 Delta 함수민 경과에는 그 파향스펙트럼을 정확하게 추정하며, 단봉형 스펙트럼의 경과에도 Mitsuyasu의 방향분산계수(spreading coefficient)가 5 이상이면 정도가 매우 좋은 것으로 나타났다. 또한, 쌍봉형 파향스펙트럼의 경과에는 두 peak를 이루는 파향의 각도차가 클수록 분해능이 양호하며, peak의 첨예도(peakedness)가 큰 쪽이 평활화(smoothing)되어 이 부분의 에너지 일부가 첨예도가 작은 peak쪽으로 이동하는 것을 알 수 있었다. 한편 LHM은 쌍봉형의 경과에도 단봉형으로 추정하는 경향이 뚜렷하며, 계산시간이 빠른 점을 제외하면 MEM에 비해 분해능이 매우 뒤떨어지는 방법이라 할 수 있다.

• 한국식품과학회지
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• 제21권1호
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• pp.80-85
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• 1989

겉보리와 쌀보리의 전분 및 이들의 구성성분인 아밀로오스와 아밀로펙틴의 분자 구조적 성질을 비교 검토하였다. 쌀보리의 전분 및 아밀로오스와 아밀로펙틴의 ${\beta}-amylosis\;limit(%)$는 각각 56.3, 87 및 52% 이었고, 겉보리 58.6, 77.7 및 57.6%이었다. 쌀보리 아밀로펙틴의 outer chain length${\overline{OCL})$과 inner chain length ${\overline{ICL}}$을 각각 15.8 및 7.8 이었고 겉보리는 각각 17.0 및 7.8이었고, 두 chain 길이의 비는 각각 약 2.1:1 및 2.0:1이었다. 두 시료 전분 모두 pullulanase 로 debranching 한 후의 Sephadex G-75에 의한 용출곡선의 양상은 ${\overline{dp}}55$ 이상의 아밀로오스 성분을 나타내는 분획과 아밀로펙틴 성분으로 볼 수 있는 ${\overline{dp}}35-45$ 및 ${\overline{dp}}10-20$의 bimodal 분포를 갖는 분획 특징을 나타내었다. 또 debranching과 동시에 ${\beta}-amylase$로 처리한 경우는 가수분해 되지 않는 ${\overline{dp}}55$ 이상의 분획성분이 $0.3{\sim}1.5%$ 존재하였다. 아울러 ${\beta}-amylase$로만 가수분해한 경우도 시료차이 없이 ${\overline{dp}}\;55$ 이상의 ${\beta}-limit\;dextrin$ 성분과 ${\overline{dp}}\;10$ 이하의 과당성분으로 분획되는 비슷한 분획양상을 보였으나 분획성분의 분자량 분포사이에는 현저한 시료 차이를 나타내었다.

• Journal of Ecology and Environment
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• 제45권2호
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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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• 제22권E2호
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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.

• 대한세포병리학회지
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• 제7권1호
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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.

• 한국수산과학회지
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• 제48권5호
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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.