• International Journal of Advanced Culture Technology
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• 제11권1호
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• pp.135-146
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• 2023

Psychological support is crucial in navigating one's academic and professional lives, especially for students living abroad and pursuing higher education. This study aims to explore the narratives of social support seeking in a group of Korean international graduate students in an urban university setting in the United States. Qualitative research method of narrative approach was used to examine how three Korean graduate students exchanged psychological support. Analysis of interviews, observations, and documents found that four types of social support (informational, instrumental, appraisal, and emotional) were being exchanged and that emotional support was accessible predominantly in individual meetings than in group gatherings. Additionally, the reasons for abstaining from initiating group gatherings are discussed in relation to the Korean culture where participants were mindful of not infringing on each other's time. These findings inform theory on socio psychological support seeking and its relation to cultural values and offer practical insights into psychological support in international students in higher education settings.

• 천문학회보
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• 제45권1호
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• pp.66.2-66.2
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• 2020

We propose a deep learning analysis technique with a convolutional neural network (CNN) to predict the evolutionary track of the Epoch of Reionization (EoR) from the 21-cm differential brightness temperature tomography images. We use 21cmFAST, a fast semi-numerical cosmological 21-cm signal simulator, to produce mock 21-cm maps between z = 6 ~ 13. We then apply two observational effects, such as instrumental noise and limit of (spatial and depth) resolution somewhat suitable for realistic choices of the Square Kilometre Array (SKA), into the 21-cm maps. We design our deep learning model with CNN to predict the sliced-averaged neutral hydrogen fraction from the given 21-cm map. The estimated neutral fraction from our CNN model has great agreement with the true value even after coarsely smoothing with broad beam size and frequency bandwidth and heavily covered by noise with narrow beam size and frequency bandwidth. Our results show that the deep learning analyzing method has the potential to reconstruct the EoR history efficiently from the 21-cm tomography surveys in future.

• 한국식품저장유통학회지
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• 제31권3호
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• pp.360-373
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• 2024

Polychlorinated hydrocarbons are continuously released into the environment from various industrial processes. Trichloroethylene (TCE) and tetrachloroethylene (perchloroethylene, PCE) are of primary concern because of their large-scale production, wide industrial application, poor biodegradability, and tendency to circulate in the air and water. The common routes of human exposure to these compounds include inhalation, ingestion, and dermal adsorption. Additionally, they have been detected in various plant foods. Prolonged exposure to these contaminants is associated with certain risks. They are carcinogenic and have other toxic effects, including gastrointestinal, developmental, neurological, and hematological toxicity. To analyze these contaminants, they are generally extracted from various matrices, followed by instrumental analysis. Gas chromatography, often in combination with different detectors, is the most widely used analytical method. This review covers the toxicity, analytical methods, occurrence in foods, and risk assessment of these contaminants.

• Fisheries and Aquatic Sciences
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• 제2권1호
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• pp.1-7
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• 1999

Antioxidant activity of a methanol extract of Symphyocladia latiuscula was evaluated by the thiocyanate method in the linoleic acid system. The methanol extract inhibited the peroxidation of linoleic acid in a dose-dependent manner. The MeOH extract was then sequentially partitioned with n-hexane, $CH_2Cl_2$, EtOAc, n-BuOH and H20. The antioxidant activity of the fractions increased in order of $CH_2Cl_2$, n-hexane, EtOAc, and n-BuOH. There was no activity found in $H_2O$ partitoned fraction by the thiocyanate method. Especially, the activities of the fractions of n-hexane and $CH_2Cl_2$ were comparable to that of 2,6-di-tert­butylhydroxytoluene (BHT). Column chromatography of the $CH_2Cl_2$ fraction over silica gel yielded cholesterol (1) and 2,3,6-tribromo 4,5-dihydroxybenzyl methyl ether (2) which were identified by instrumental analysis of MS and $^1H-$ and $^{13}C-NMR$. The latter (2) demonstrated significant antioxidant activity.

• 한국의류학회지
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• 제37권6호
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• pp.827-836
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• 2013

Indigotin, indirubin, berberine, palmatine, alizarin, and purpurin are major pigments of indigo plant, Phellodendron bark, and madder. The six pigments were examined using the HPLC-DAD-MS instrument for the purpose of the simultaneous detection of the pigments in a single sample run. The HPLC-DAD-MS method examined the individual pigment solutions in DMSO, a solution containing 6 pigments, and the DMSO extract of the silk dyed with a dye solution of 5 pigments excluding indirubin. The retention times of the HPLC chromatograms, ${\lambda}_{max}$ of the uv-vis absorption bands in the DAD analyses, and the molecular ions detected for the compound peaks in the MSD analyses were consistent throughout the analyses of individual pigment solutions, mixed pigment solutions, and dye extracted from silk dyeing. The developed instrumental method of the simultaneous detection of six pigments can identify dye in an exhumed textile if the textile is dyed using any one (or multiple) pigments of indigo, Phellodendron bark, or madder plant.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
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• pp.227.1-227.1
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• 2016

플라즈마 방출광 진단법은 플라즈마에 특별한 영향을 주지 않으면서도 진단 정보를 안정적으로, 지속적으로 취득할 수 있는 우수한 진단 방법이다. 이러한 분광 진단의 신뢰성을 확보하기 위해서는 방출광의 정확한 측정과 해석이 중요하다. 방출광의 측정에 이용되는 분광 장비는 모노크로메터(monochromator)와 소형 스펙트로메터(spectrometer)가 주로 사용된다. 스펙트로메터의 경우 모노크로메터보다 분광 성능은 다소 부족하지만 가볍고 작은 크기로 인해 장비의 설치가 용이하고 가격이 저렴하다는 장점이 있다. 또한 모노크로메터에 비해 분광 성능이 낮은 대신 넓은 범위의 파장을 동시에 측정할 수 있는 장점이 있다. 따라서 스펙트로메터는 플라즈마의 모니터링에 주로 사용된다. 그런데 스펙트로메터의 기기적 선폭 증대(instrumental broadening)보다 조밀하게 위치한 스펙트럼들은 서로 중첩이 일어나 진단이 어려워진다. 특히 분자 띠 스펙트럼(molecular band spectrum)과 같은 경우 선 스펙트럼들이 매우 밀집된 형태를 이루고 있어 범용적인 스펙트로메터로 진단하기가 어렵다. 이러한 문제점을 해결하기 위하여 합성 스펙트럼 해석법(synthetic spectrum method)을 이용할 수 있다. 본 연구에서는 수소 플라즈마의 Fulcher-${\alpha}$ 띠 스펙트럼 해석에 합성 스펙트럼법을 적용하여 분자의 회전 온도가 측정 가능한지 확인하고, 고성능의 모노크로메터를 이용한 온도 측정 결과와 서로 비교하였다. 그리고 분자의 진동 상태(vibrational state)가 분자 회전 온도 측정에 미치는 영향과 이에 따른 측정의 한계 등을 제시하였다.

• 지질공학
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• 제5권3호
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• pp.309-329
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• 1995

역사지진 카탈로그 즉, 1960년대 전과 이후 1995년까지의 지진관측을 이용하여 한반도의 지진활동과 응력상태가 연구되었다. 이씨왕조의 처음 1400-1600년대의 200년동안 역사지진 카탈로그는 크게 완성되었다. 그후부터 카탈로그는 거의 강진만 완성하는데 주력했다. 강진분포를 볼때 한반도 지진대는 서울-평양 지진대, 남부지진대, 그리고 북부지진대로 나눌 수 있다. 이들 강진의 초동 메카니즘은 그리드 테스팅 방법(grid testing method)에 의해서 재분석되었다. 지진메카니즘 결과는 압축방향이 동서방향을 따라서 수평으로 놓여 있음을 발견했다.

• 한국세라믹학회지
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• 제42권6호
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• pp.417-424
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• 2005

Although a lot of studies in fracture toughness of Y-TZP ceramics for structural applications have been done, it remains an important challenge to be able to improve fracture toughness of Y-TZP ceramics. In this research, milling method adding monoclinic zirconia and $Al_2O_3$ to 3Y-TZP was introduced to improve the fracture toughness of 3Y-TZP. Experimental results showed that addition of small amount of $Al_2O_3$ causes to make lots of oxygen vacancies (VO) by substituting $Al^{3+}$ for $Zr^{4+}$. It is believed that the produced vacancies provides useful routes far mass transfer. Y-TZP ceramics having higher microhardness and better fracture toughness was fabricated by sintering at $1400^{\circ}C$.

• 한국세라믹학회지
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• 제42권6호
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• pp.411-416
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• 2005

Y-TZP(Yttria-stabilized Tetragonal Zirconia Polycrystal) ceramics are of great interest as engineering and structural materials due to their excellent mechanical properties arising from transformation toughening, it is also reported that the 3Y-TZP($3 mol\%$ Yttria-stabilized Tetragonal Zirconia Polycrystal) has the best mechanical properties in Y-TZP ceramics. But to use widely for engineering and structural materials, it remains an important challenge to be able to improve its fracture toughness. In order to produce the 3Y- TZP ceramics showing much better mechanical properties, milling method adding monoclinic zirconia to 3Y-TZP was adopted and the resultant mechanical properties containing apparent density and fracture toughness were measured by using proper techniques. Experimental results showed that the 3Y-TZP specimen containing $33 wt\%$ of monoclinic zirconia, which was sintered at $1450^{\circ}C$, has the highest fracture toughness value of $11.38 MPa{\cdot}m^{1/2}$ which is three times higher than that of normal 3Y-TZP ceramics.

• 한국대기환경학회지
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• 제18권6호
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• pp.527-538
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• 2002

In this study, the performance of sampling and of analytical methodology was examined against a number of selected volatile organic compounds (VOCs) in the ambient air. The canister-based sampling method for VOCs has been a viable and widely used approach that is based on research and evaluation performed over the past several years. VOCs were determined using canisters by GCMSD analysis. A total of target analyses in this study included approximately 30 VOCs designated in TO-l4A categories including BTEX. The methodology for QC(quality control) was intensively investigated with a wide range of performance criteria such as; (1) cleanliness of canisters, (2) reproducibility of diluter, (3) instrumental detection limits of preconcentrator and GCMSD, and (4) precision and accuracy of GCMSD. For most of the compounds tested, precision was less than $\pm$5%, IDL was 0.2 ppbv, accuracy was $\pm$5%, respectively. This study demonstrated that the combination of canister sampling and GC/MSD analysis could be reliably applied to the measurements of BTEX in ppbv levels that are typically observed in/outdoor air environment.