• 대한원격탐사학회지
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• 제27권6호
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• pp.729-741
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• 2011

Wind speeds have long been estimated from C-band VV-polarized SAR data by using the CMOD algorithms such as CMOD4, CMOD5, and CMOD_IFR2. Some SAR data with HH-polarization without any observations in VV-polarization mode should be converted to VV-polarized value in order to use the previous algorithms based on VV-polarized observation. To satisfy the necessity of polarization ratio (PR) for the conversion, we retrieved the conversion parameter from full-polarized SIR-C SAR image off the east coast of Korea. The polarization ratio for SIR-C SAR data was estimated to 0.47. To assess the accuracy of the polarization ratio coefficient, pseudo VV-polarized normalized radar cross section (NRCS) values were calculated and compared with the original VV-polarized ones. As a result, the estimated psudo values showed a good agreement with the original VV-polarized data with an root mean square error by 0.99 dB. We applied the psudo NRCS to the estimation of wind speeds based on the CMOD wind models. Comparison of the retrieved wind field with the ECMWF and NCEP/NCAR reanalysis wind data showed relatively small rms errors of 1.88 and 1.91 m/s, respectively. SIR-C HH-polarized SAR wind retrievals met the requirement of the scatterometer winds in overall. However, the polarization ratio coefficient revealed dependence on NRCS value, wind speed, and incident angle.

• Current Optics and Photonics
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• 제4권3호
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• pp.174-185
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• 2020

Multiscattering occurs when a laser transmits into dense atmosphere targets (e.g. fogs, smoke or clouds), which can cause depolarization effects even though the scattering particles are spherical. In addition, multiscattering effects have additional information about microphysical properties of scatterers. Thus, multiscattering can be utilized to study the microphysical properties of the liquid water cloud. In this paper, a Monte Carlo method was used to simulate multi-scattering transmission properties of Lidar signals in the cloud. The results showed the slope of the degree of linear polarization (SLDLP) can be used to invert the extinction coefficient, and then the cloud effective size (CES) and the liquid water content (LWC) may be easily obtained by using the extinction coefficient and saturation of the degree of linear polarization (SADLP). Based on calculation results, a microphysical properties inversion method for a liquid cloud was presented. An innovative multiscattering polarization Lidar (MSPL) system was constructed to measure the LWC and CES of the liquid cloud, and a new method based on the polarization splitting ratio of the Polarization Beam Splitter (PBS) was developed to calibrate the polarization channels of MSPL. By analyzing the typical observation data of MSPL observation in the northern suburbs of Nanjing, China, the LWC and CES of the liquid water cloud were obtained. Comparisons between the results from the MSPL, MODIS and the Microwave radar data showed that, the microphysical properties of liquid cloud could be retrieved by combining our MSPL and the inversion method.

• BMB Reports
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• 제53권11호
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• pp.600-604
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• 2020

Macrophages are re-educated and polarized in response to myocardial infarction (MI). The M2 anti-inflammatory phenotype is a known dominator of late stage MI. Mesenchymal stem cells (MSCs) represent a promising tool for cell therapy, particularly heart related diseases. In general, MSCs induce alteration of the macrophage subtype from M1 to M2, both in vitro and in vivo. We conjectured that hypoxic conditions can promote secretome productivity of MSCs. Hypoxia induces TGF-β1 expression, and TGF-β1 mediates M2 macrophage polarization for anti-inflammation and angiogenesis in infarcted areas. We hypothesized that macrophages undergo advanced M2 polarization after exposure to MSCs in hypoxia. Treatment of MSCs derived hypoxic conditioned medium (hypo-CM) promoted M2 phenotype and neovascularization through the TGF-β1/Smad3 pathway. In addition, hypo-CM derived from MSCs improved restoration of ischemic heart, such as attenuating cell apoptosis and fibrosis, and ameliorating microvessel density. Based on our results, we propose a new therapeutic method for effective MI treatment using regulation of macrophage polarization.

• 유통과학연구
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• 제14권8호
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• pp.101-112
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• 2016

Purpose - The objective of this study is to identify the effects of the communication cues and anonymity on group polarization in mobile communication settings, both in terms of route and extent. Research design, data and methodology - Laboratory experiments were conducted to achieve the above research objective; the effect of communication cues on group polarization with social presence as mediation and the direct effect of anonymity, social presence, and perceived cohesion were analyzed. The experiments were conducted by the participation of 240 people, who were divided into 48 groups of 5 people. Results - According to the results, the difference in intergroup polarization due to communication cues and anonymity was insignificant. From this analysis, the structural equation model, communication cues and anonymity did not affect group polarization through social presence. Moreover, anonymity did not affect group polarization through perceived cohesion; however, anonymity directly affected group polarization. Conclusions - This research can help to explain the discussions and the related decision-making actions on internet forums, which have recently come to the rise as well as provide foundational basis in newly establishing policies for the forums.

• 지구물리와물리탐사
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• 제13권3호
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• pp.249-255
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• 2010

1990년대 이후 지진발생과 관련된 ULF 대역 지사가장의 변동이 다수 보고된 후, 분석 분석 방법을 이용한 지자기장 분석은 단기 지진예측에 큰 기여를 할 것이라 기대되고 있다. 본 연구는 기존 연구를 참조하여 개량된 분극 분석 방법을 개발하고, 이를 이용하여 청양관측소의 지자기 삼성분 자료를 분석하였다. 분석 주파수는 지진발생에 가장 민감하다고 알려진 0.01 Hz 대역이며, 수직 자기장과 수평 자기장의 분광에너지 비, 즉 분극값을 일단위로 계산하였다. 총 10개 월 동안의 사료가 분석되었으며, 분석경과를 Kp 인덱스 및 동일기간 발생한 지진이벤트와 비교하였나 청양의 분극값 변동은 Kp 인덱스와 관련성이 적었으며, 두 기간에서 지진발생과 관련한 주목할 만한 분극값의 증가가 관찰되었다. 일본 Kanoya 관측소의 자료와 비교해 본 결과, 청양의 분극값 증가는 광역적인 자기장의 변동에서는 지진발생과 밀접한 관계가 있는 것으로 생각된다. 또한, 자기장의 통계적 특성을 고려한 정규화된 분극값의 변동에서는 이러한 특징이 보다 뚜렷하게 확인된다. 따라서 분극 분석 방법은 지진전조형상 모니터링을 위해 유용하게 활용됨 수 있으며, 향후 추가적인 자료 확보 및 분석을 통해 지진발생과 관련된 ULF 변동을 탐지하는데 큰 기여를 할 수 있을 것으로 기대된다.

• 대한화학회지
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• 제41권1호
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• pp.1-11
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• 1997

0.5 M $K_2SO_4$ 용액에서 여러 가지 세 탄소전극(glassy carbon, 인조흑연, graphite foil)에 대하여 양극분극에 따른 전극표면반응에 대한 연구를 임피던스 스펙트로스코피를 통하여 실시했다. Graphite foil 전극의 경우 이중츨 capacotance는 다른 두 전극재료에 비하여 높게 나타났으며, 양극분극시 glassy carbon과 인조 흑연(PVDF 혼합 graphite)은 전극계면에서 흡착현상에 의한 capacitance C의 영향이 현저하게 나타남을 알 수 있었다. 3종류 전극재료의 전기화학적 거동은 전극표면 조직의 차이에 의해 glassy carbon의 경우는 분극시 파라데이 임피던스의 영향을 받으며, graphite foil의 경우는 field transport의 지배를 받아 전압의 변화에 의한 임피던스 파라미터의 변화는 거의 나타나지 않았다.

• 수산해양교육연구
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• 제19권3호
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• pp.323-328
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• 2007

This paper was studied on the effect of the specific resistance of water on corrosion characteristics of STS 304 for gas boiler. The electrochemical polarization test of STS 304 for gas boiler was carried out. And the polarization resistance, uniform corrosion, corrosion behavior by impressed potential and corrosion sensitivity of STS 304 with specific resistance were considered. The main results are as following: 1) With being low the specific resistance of water, the polarization resistance and corrosion potential of STS 304 decreases, while corrosion current density increases. 2) Under constant impressed potential, the corrosion sensitivity of STS 304 is large with being low the specific resistance due to synergy effect of Cl ion.

• 한국표면공학회지
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• 제48권5호
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• pp.227-232
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• 2015

Corrosion characteristic of the duplex Al-Mg-Si alloys with low, commercial and high solute contents were studied using an anodic polarization test in 1M NaCl solution at room temperature. Polarization range condition of the experiment were form .0.3V to .1.3V with a 0.2 mV scanning speed. The exchange current density means corrosion rate of the low solute alloy was low as about $16.29{\mu}A/cm^2$, and that of the high solute alloy was high as $84.92{\mu}A/cm^2$. The difference was mainly attributed to the inter-granular precipitates $Mg_2Si$ and Si which could make a galvanic corrosion on the aluminum base. The amount of precipitates was greater in high solute alloy at mainly in grain boundary. While, the extruded alloys had better corrosion resistance than the cast alloy because the silicon precipitates become coarse during the extrusion process.

• 정보교육학회논문지
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• 제25권6호
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• pp.871-878
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• 2021

본 연구에서는 가구의 월평균 전체 사교육비와 소프트웨어 및 인공지능 관련 사교육비, 그리고 학업성취 간 관계를 분석하여 소프트웨어 교육의 양극화 실태를 조명하였다. 이를 위해 전국의 초등학생 자녀를 둔 학부모 2,780명을 대상으로 설문조사를 실시하여 자료를 수집하였으며 상관분석과 차이검증을 수행하였다. 본 연구의 결과는 다음과 같다. 첫째, 소프트웨어 교육 참여 여부에 따라 자녀의 학업성취도에는 통계적으로 유의미한 차이가 나타났다. 둘째, 자녀의 학업성취도가 높을수록 소프트웨어 사교육에 참여하는 비율도 현격히 증가하는 경향성을 확인하였다. 셋째, 총 사교육비와 소프트웨어 관련 사교육비는 유의미한 정적 상관이 있었다. 넷째, 소프트웨어 사교육비와 학업성취도 간에는 통계적으로 유의미하지는 않았으나 정적 상관이 존재하는 것으로 드러났다. 본 연구를 통하여 학부모는 공교육에서 제공하는 소프트웨어 교육이 충분하지 않은 탓에 사교육 참여와 그 지출 규모를 늘리고 있고, 가구소득에 따라 미래 인재로 성장하기 위한 주요 역량을 키우는 데에 격차가 존재한다는 문제가 있음을 확인하였다.

• 수산해양교육연구
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• 제18권1호
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• pp.58-64
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• 2006

In order to examine the effect of humidity on hydrogen embrittlement of STS 444 weld zone for boiler with dry and wet welding conditions, this paper was carried out the accelerated hydrogen osmosis test and the electrochemical Tafel polarization test. In 0.5M $H_2SO_4$ + 0.01M $As_20_3$ solution, this test is added to load of $1400kg/cm^2$ together with hydrogen osmosis by current of $50 {mA/cm^2}$ for 60 min.. The electrochemical Tafel polarization test was carried out in 0.5M $H_2SO_4$ + 0.01M $As_20_3$ solution. Therefore, the effect of humidity on hydrogen embrittlement of STS 444 was considered. The main results are as following: On the basis of hydrogen embrittlement mechanism, that is, integrated electrochemical polarization characteristics with the established mechanism of hydrogen embrittlement, the reduction rate of corrosion current density of weld zone in the wet weld condition is larger than in the dry condition. We can nondestructively predict the degree of hydrogen embrittlement of STS 444 weld zone for boiler through the reduction rate of electrochemical corrosion current density.