• 한국대기환경학회지
• /
• 제9권3호
• /
• pp.200-206
• /
• 1993

Since November 1990, observations of carbon monoxide(CO) levels have been carried out at Tat-ahn Peninsula(TAP) in Korea. Analysis on atmospheric data, obtained in the period from November 1990 to February 1992, is carried out and the results are included in this study. It is observed that variations of monthly average level on CO are in the range of 141.61-516.06ppb(amplitude 374.45 ppb). An average level in 1991 is 308.18 ppb. CO observed at TAP has a larger seasonal variation. One of reasons appears that CO of TAP is strongly influenced by local sources and westerly airflows. When this gas of TAP is compared with data observed at Korea National University of Education(KNU) and in Seoul, we learn that CO values of KNU are higher(in average 2.15 times) than those of TAP; CO value observed in Seoul are 7 times higher than those of TAP. We interprete that air samples taken both at KNU and in Seoul are influenced strongly by local sources than those at TAP. According to analysis of trajectories and air flows, the CO value is higher with NW airflows than the value with SW airflows.

• 전자공학회논문지A
• /
• 제33A권7호
• /
• pp.134-142
• /
• 1996

The epi-CoSi$_{2}$ layer was formed by alloying a Co(120$\AA$)/Ti(50$\AA$) bilayer. In addition, the ultra shallow p$^{+}$n junction of which depth is about not more than 40nm at the background concentration, 10$^{18}$atoms/cm$^{3}$ could be formed by annealing (RTA-II) the ion implanted epi-silicide. When the temperature of RTA-I is as low as possible and that of RTA-II is moderate, the p$^{+}$n junction that has low leakage current and stable epi-silicide layer could be obtained. That is, when th econdition of TRA-I was 900$^{\circ}C$/20sec and that of RTA-II was 900$^{\circ}C$/10sec, the reverse leakage current was as high as 11.3$\mu$A/cm$^{2}$ at -5V. The surface of CoSi$_{2}$ appeared considerably rough. However, when the conditon of RTA-I was 800$^{\circ}C$/20sec or 700$^{\circ}C$/20sec, the leakage currents were as low as 8.3nA/cm$^{2}$ and 9.3nA/cm$^{2}$, respectively and also the surfaces appeared very uniform.

• 한국지하수토양환경학회지:지하수토양환경
• /
• 제23권4호
• /
• pp.48-59
• /
• 2018

Beryllium (Be), cobalt (Co), thallium (Tl) and vanadium (V) are candidates of 21 priority soil pollutants in Korea. The distribution of their concentration in soils from three contamination sources including industrial, roadside and mining areas was investigated. Concentrations of the metals were evaluated quantitatively using pollution indices and the fractionation of metals was conducted using modified SM&T (Standards Measurements and Testing programme) sequential extraction. Concentrations of the metals for all samples from industrial and roadside soils were within the range of natural background levels, while some of Be in soils from abandoned mines exceeded that the range. Enrichment Factor (EF) and Nemerow Integrated Pollution Index (NIPI) for Be, Co, Tl and V showed that there are effects or possibilities of anthropogenic activities. Pollution Load Index (PLI) analyses indicated all investigated sites needed further monitoring. The results of sequential extractions indicated mobile fractions (F1+F2) of Be, Tl and V were below 30% except some of Co in soil, which implies their low mobility to neighboring environment media. Variable tools like sequential extraction, comparison with background/actual concentration and pollution indices, as well as aqua regia extraction should be considered when evaluating Be, Co, Tl, V in soil.

• Current Optics and Photonics
• /
• 제2권2호
• /
• pp.165-171
• /
• 2018

Fourier ptychographic microscopy (FPM) is a recently proposed computational imaging method that achieves both high resolution (HR) and wide field of view. In the FPM framework, a series of low-resolution (LR) images at different illumination angles is used for high-resolution image reconstruction. On the basis of previous research, image noise can significantly degrade the FPM reconstruction result. Since the captured LR images contain a lot of dark-field images with low signal-to-noise ratio, it is very important to apply a noise-reduction process to the FPM raw dataset. However, the thresholding method commonly used for the FPM data preprocessing cannot separate signals from background noise effectively. In this work, we propose an improved thresholding method that provides a reliable background-noise threshold for noise reduction. Experimental results show that the proposed method is more efficient and robust than the conventional thresholding method.

• Nuclear Engineering and Technology
• /
• 제14권2호
• /
• pp.64-69
• /
• 1982

동시섬광분석기를 써서, 각도범위 90$^{\circ}$에서 180$^{\circ}$에 대하여, Co-60 및 Cs-134 감마선의 방향상관을 측정하였다. 그리고, 방향-편극상관의 측정에는 컴프턴산란효과를 응용한 감마선 편광분광기를 병용하였다. 이론적인 배경과 더불어 실험방법이 기술되었으며, 측정값이 이론적인 개산치와 일치함을 보이기위해 실험결과를 도식적으로 나타내었다.

• 한국환경농학회지
• /
• 제30권2호
• /
• pp.99-104
• /
• 2011

BACKGROUND: Application of urea may increase $CO_2$ emission from soils due both to $CO_2$ generation from urea hydrolysis and fertilizer-induced decomposition of soil organic carbon (SOC). The objective of this study was to investigate the effects of increasing urea application on $CO_2$ emission from soil and mineralization kinetics of indigenous SOC. METHODS AND RESULTS: Emission of $CO_2$ from a soil amended with four different rates (0, 175, 350, and 700 mg N/kg soil) of urea was investigated in a laboratory incubation experiment for 110 days. Cumulative $CO_2$ emission ($C_{cum}$) was linearly increased with urea application rate due primarily to the contribution of urea-C through hydrolysis to total $CO_2$ emission. First-order kinetics parameters ($C_0$, mineralizable SOC pool size; k, mineralization rate) became greater with increasing urea application rate; $C_0$ increased from 665.1 to 780.3 mg C/kg and k from 0.024 to 0.069 $day^{-1}$, determinately showing fertilizer-induced SOC mineralization. The relationship of $C_0$ (non-linear) and k (linear) with urea-N application rate revealed different responses of $C_0$ and k to increasing rate of fertilizer N. CONCLUSION(s): The relationship of mineralizable SOC pool size and mineralization rate with urea-N application rate suggested that increasing N fertilization may accelerate decomposition of readily decomposable SOC; however, it may not always stimulate decomposition of non-readily decomposable SOC that is protected from microbial decomposition.

• Journal of Ecology and Environment
• /
• 제40권1호
• /
• pp.12-19
• /
• 2016

Background: Direct impact of inorganic carbon (i.e., carbon dioxide ($CO_2$)) on the periphyton community is important to understand how and to what extent atmospheric conditions can affect the structure and dynamics of these communities in lotic systems. We investigated the influence of elevated $CO_2$ concentration on the periphyton community in the artificially constructed channels during the winter period. The channels made of acrylic paneling were continuously supplied with surface water discharged from a small reservoir, which was supported with ground water, at a flow rate of 5 L/min, and water temperature ranging $4-5^{\circ}C$. The effects of elevated $CO_2$ concentrations (790 ppm) were evaluated in comparison with the control (395 ppm $CO_2$) by analyzing pH, water carbon content and nutrients in water, periphyton composition and biomass, chlorophyll-a, ash-free dry-matter at 2-day intervals for 10 days. Results: After the addition of $CO_2$, significant decreases of pH, $NH_3-N$, and $PO_4-P$ (p < 0.05) and increases of chlorophyll-a, ash-free dry-matter, and the cell density of periphyton (p < 0.01) were observed, whereas the species composition of periphyton and water carbon content did not change. Conclusions: These results suggest that elevated $CO_2$ in flowing water system with low temperature could facilitate the growth of periphyton resulting in biomass increase, which could further influence water quality and the consumers throughout the food web.

• 한국환경성돌연변이발암원학회지
• /
• 제26권2호
• /
• pp.35-40
• /
• 2006

Background: Inorganic arsenic is a human carcinogen that can target the liver, but its carcinogenic mechanisms are still unknown. Inorganic arsenic induces a spectrum of tumors including hepatocellular carcinoma in mice. Methods: Pregnant C3H mice were supplied with drinking water containing 50 ppm sodium arsenite during their pregnancy. The protein expression profile in the liver of 0.5-day-old. male offsprings exposed transplacentally to sodium arsenite was analyzed using protein 2D gel electrophoresis followed by mass spectrometry (MALDI-TOF). Results: Expression of proteins such as hydroxymethylglutaryl-CoA synthase mitochondrial precursor (HMG-CoA synthase), ${\beta}$-actin (cytoplasmic 1) and apolipoprotein A-IV precursor (Apo-AIV) were induced in mouse liver by sodium arsenite, while uricase (urate oxidase), guanine nucleotidebinding protein beta subunit 2-like 1 (RACK1) and fructose-bisphosphate aldolase B (Aldolase 2) were down-regulated. Summary: Expression of proteins that have been implicated in carcinogenesis, such as HMG-CoA, ${\beta}$-actin, and RACK1, was regulated in the liver of mice transplacentally exposed to inorganic arsenic.

• 보존과학회지
• /
• 제37권6호
• /
• pp.712-722
• /
• 2021

본 연구의 목적은 박락과 오염이 심하여 보존 상태가 좋지 않은 치성광여래 무신도에 대한 과학적 조사를 기초로 보존처리를 진행한 논문이다. 연구 방법으로는 상태 조사와 과학적 장비를 이용하여 무신도의 재질과 제작 방법을 파악하였다. 사용 장비로는 색차계와 실체현미경 그리고 휴대용 현미경, P-XRF, FT-IR, SEM-EDS를 이용하여 배접지와 바탕재의 종류와 채색 안료 성분분석을 하였다. 분석결과 배접지는 펄프지, 바탕재는 합성섬유인 폴리에스테르로 확인되었다. 또한 사용 안료는 적색 안료인 연단[Red Lead, Pb₃O₄], 백색 안료인 호분[Oyster Shell White, CaCO₃]을 제외하고 나머지는 합성안료로 확인되었다. 또한, 19세기 후반 무신도에서 주로 확인되는 녹색안료인 에메랄드그린[Emerald Green, Cu(C₂H₃O₂)₂·3Cu(AsO₂)₂]이 검출되었다. 이와 같은 분석을 통하여 확인된 재질 및 안료를 사용하여 치성광여래 무신도의 보존처리를 진행하여 보존하고자 하였다.

• 한국운동역학회지
• /
• 제29권4호
• /
• pp.247-254
• /
• 2019

Objective: The goal of this study was to determine the center of pressure (CoP) complexity pattern in approximate entropy technique between genders at different conditions of running speed. Background: It is conducted to evaluate the complexity pattern of CoP in the increment of running speed to have insights to injury prediction, stability, and auxiliary aids for the foot. Method: Twenty men (age=22.3±1.5 yrs.; height=176.4±5.4 cm; body weight=73.9±8.2 kg) and Twenty women (age=20.8±1.2 yrs.; height=162.8±5.2 cm; body weight=55.0±6.3 kg) with heel strike pattern were recruited for the study. While they were running at 2.22, 3.33, 4.44 m/s speed on a treadmill (instrumented dual belt treadmills, USA) with a force plate, CoP data were collected for the 10 strides. The complexity pattern of the CoP was analyzed using the ApEn technique. Results: The ApEn of the medial-lateral and antero-posterior CoP in the increment of running speed showed significantly difference within genders (p<.05), but there were not statistically significant between genders at all conditions of running speed. Conclusion: Based on the results of this study, CoP complexity pattern in the increment of running speed was limited to be characterized between genders as an indicator to judge the potential injury and stability. Application: In future studies, it is needed to investigate the cause of change for complexity of CoP at various running speed related to this study.