• Journal of the Korean earth science society
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• v.37 no.7
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• pp.434-447
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• 2016

This study analyzed mass concentrations of PM10 and PM2.5, as measured at Tae-ahn and Gang-nae, Cheongju in central Korea over the period from 2011 to 2015. Higher mass concentrations of PM10, with the exception of dustfall cases during the period of winter and spring, reflected the influence of a prevailing westerly airflow, while the level of PM10 stayed at a low level in summer, reflecting the influence of North Pacific air mass and frequent rainfall. Accordingly, cases where a daily PM10 average of $81{\mu}gm^{-3}$ or over (exceeding the status of fine dust particles being 'a little bit bad') were often observed during the period of winter and spring, with more cases occurring in parts of Tae-ahn that are located close to the sources of pollutant emission in eastern China. Dustfall usually originated from dust storms made up of particles $2.5{\mu}m$ or over in diameter. However, anthropogenic haze displayed a high composition ratio of particulate less than $2.5{\mu}m$ in diameter. Accordingly, brightness temperature difference (BTD) values from the Communication, Ocean and Meteorological Satellite (COMS) were $-0.5^{\circ}K$ or over in haze with fine particulate. PM10 mass concentrations and NOAA 19 satellite BTD for haze cases were analyzed. Though PM10 mass concentrations were found to be lower than $200{\mu}g\;m^{-3}$, the mass concentration ratio of PM2.5/PM10 was measured as higher than 0.4 and BTD was found to be distributed in the range from -0.3 to $0.5^{\circ}K$. However, the BTD of dustfall cases exceeding $190{\mu}g\;m^{-3}$, were found to be less than 0.4 and BTD was found to be distributed in the range less than $-0.7^{\circ}K$. The result of applying BTD threshold values of the large-scale transport of haze proved to fall into line with the range over which aerosols of MODIS AOD and OMI AI were distributed.

• Journal of the korean academy of Pediatric Dentistry
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• v.27 no.1
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• pp.169-179
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• 2000

The purpose of this study is to develop the system which convert the optical difference of teeth texture between intact enamel and incipient caries lesion into shade difference by laser fluorescence and to develop new and simple caries activity test using laser fluorescence. The experimental design of this study consists of three parts. In first part, a new method for the in vitro assessment of changes in initial enamel caries lesion of Bovine teeth using laser fluorescence is tested. In second part, in vivo assessment undertaken. Number of teeth which showed incipient carious lesion on buccal surface examined by laser fluorescence was compared with the caries activity test of $Cariescreen^{(R)}$ test and other oral environmental test of dDfFtT. In third part, new caries activity test measured by laser fluorescence was developed on the basis of above results and evaluated the sensitivity, specificity, and diagnostic power. Optical density measured by laser fluorescence was increased as increasing the depth of incipient carious lesion and showed high correlation$(\gamma=0.7015)$ with lesion depth. Optical density showed direct proportion to lesion depth. Linear equation was obtained between the optical density and the lesion depth by regression analysis. The result of caries activity test with laser fluorescence showed high correlation with those of $Cariescreen^{(R)}$ test and dDfFtT examination. Caries activity test with laser fluorescence showed 48% of sensitivity, 52% of specificity, and 45% of diagnostic power on the basis of dDfFtT examination, and also showed 48% of sensitivity, 51% of specificity, and 36% of diagnostic power on the basis of $Cariescreen^{(R)}$ test. In regard above result, caries activity test with laser fluorescence considered to be reliable for caries activity test compared with other oral environmental test. and it was also considered to be practical because it would be simple, inexpensive, and time saving method.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.163-163
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• 2010

중적외선 영역 ($3{\sim}5\;{\mu}m$)은 공기 중에 존재하는 이산화탄소나 수증기에 의해 흡수가 일어나지 않기 때문에 군사적으로 중요한 파장 영역이며, 야간에 적을 탐지하는데 응용되고 있다. InSb는 77 K에서 중적외선 파장 흡수에 적합한 밴드갭 에너지 (0.228 eV)를 갖고 있으며, 다른 화합물 반도체와 달리 전하 수송자 이동도 (전자: $10^6\;cm^2/Vs$, 정공: $10^4\;cm^2/Vs$)가 매우 빠르기 때문에 적외선 화상 감지기 재료로 매우 적합하다. 또한 현재 중적외선 영역대에서 널리 사용되는 HgCdTe (MCT)와 대등한 소자 성능을 나타냄과 동시에 낮은 기판 가격, 소자의 제작 용이성 때문에 MCT를 대체할 물질로 주목 받고 있다. 하지만, 기판과 절연막의 계면에 존재하는 결함 때문에 에너지 밴드갭 내에 에너지 준위를 형성하여 높은 누설 전류 특성을 보인다. 따라서 InSb 적외선 소자의 구현을 위하여 고품질의 절연막의 연구가 필수적이라고 할 수 있겠다. 절연막의 특성을 알아보기 위해, n형 InSb 기판에 플라즈마 화학 기상 증착법 (PECVD)을 이용하여 $SiO_2$, $Si_3N_4$를 증착하였으며, 증착 온도를 $120^{\circ}C$에서 $240^{\circ}C$까지 $40^{\circ}C$ 간격으로 변화하여 증착온도가 미치는 영향에 대하여 알아보았다. 절연막과 기판의 계면 특성을 분석하기 위하여 77 K에서 커패시턴스-전압 (C-V) 분석을 하였으며, 계면 트랩 밀도는 Terman method를 이용하여 계산하였다 [1]. $Si_3N_4$를 증착하였을 경우, $120{\sim}240^{\circ}C$의 증착 온도에서 $2.4{\sim}4.9{\times}10^{12}\;cm^{-2}eV^{-1}$의 계면 트랩 밀도를 가졌으며, 증착 온도가 증가할수록 계면 트랩 밀도가 증가하는 경향을 보였다. 또한 모든 증착 온도에서 flat band voltage가 음의 전압으로 이동하였다. $SiO_2$의 경우 $120{\sim}200^{\circ}C$의 증착온도에서 $7.1{\sim}7.3{\times}10^{11}\;cm^{-2}eV^{-1}$의 계면 트랩 밀도 값을 보였으나, $240^{\circ}C$ 이상에서 계면 트랩밀도가 $12{\times}10^{11}\;cm^{-2}eV^{-1}$로 크게 증가하였다. $SiO_2$ 절연막을 사용함으로써, $Si_3N_4$ 대비 약 25% 정도 낮은 계면 트랩 밀도를 얻을 수 있었으며, 모든 증착 온도에서 양의 전압으로 flat band voltage가 이동하였다. 두 절연막에 대한 계면 트랩의 원인을 분석하기 위하여 XPS 측정을 진행하였으며, 깊이에 따른 조성 분석을 하였다. 본 실험에서 최적화된 $SiO_2$ 절연막을 이용하여 InSb 소자의 pn 접합 연구를 진행하였다. Be+ 이온 주입을 진행하고, 급속열처리(RTA) 공정을 통하여 p층을 형성하였다. -0.1 V에서 16 nA의 누설 전류 값을 보였으며, $2.6{\times}10^3\;{\Omega}\;cm^2$의 RoA (zero bias resistance area)를 얻을 수 있었다.

• Journal of Ginseng Research
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• v.11 no.2
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• pp.136-144
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• 1987

Biosynthesis of saponins from acetate, mevalonate and squalene using root slices of panax ginseng C.A. Meyer was investigated. The sliced roots (2g) were incubated with the reaction mixture containing 20 M sodium acetate ($500\mu$Ci [U-$^{l4}C$]-acetate),10 mM mevalonate ($25\mu$Ci [2-$^{l4}C$]-mevalonate) or 10 mM swidme ($10\mu$Ci [4,8,12,13,17,21-$^3H$]-squalene) respectively at $30^{\circ}C$ for 72 hours. Biosynthesis of labelled ginseng saponine from [U-l4C]-acetate, [2-$^{l4}C$]-mevalonate and [4,8,12,13,17,21-$^3H$]-squalene was confirmed by autoradiography. Analysis of the products from [U-$^{l4}C$]-acetate by T.L.C. showed that the % radioactivities in panaxadiol, panaxatriol, squalene and mevalonate were found to be 2.1%, 2.7%, 2.6% and 0.2% respectively. Some of the sugars were also highly labelled. Analysis of the products from [2-$^{l4}C$]-mevalonate by T.L.C. showed that squalene was highly labelled and the products from [4,8,12,13,17,21-$^3H$]-squalene showed that panaxadiol, panaxatriol and sterol were highly labelled. From the above results, it was suggested that saponine might be synthesized from acetate via mevalonate-squalene route as expected in ginseng root.

• Journal of Periodontal and Implant Science
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• v.35 no.2
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• pp.413-426
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• 2005

수직 치근파절은 특이성을 나타내지 않기 때문에 치과의사가 정확한 진단을 하기 어렵다. 따라서 수직 치근파절의 임상적 특징, 진단적 증상을 파악하여 향후 근관치료된 치아나 치료되지 않은 치아에서 수직 치근파절의 유발인자와의 관련성 및 고찰을 통해 수직 치근파절의 예방 및 치료에 응용할 수 있을 것으로 생각된다. 연구대상은 조선대학교 부속치과병원 치주과에 내원한 환자 중 최근 2년간 144명의 환자에서 근관치료를 받았거나 받지 않았던 치아 중 임상적 및 방사선학적으로 수직 치근파절로 진단된 156개의 증례를 대상으로 하였다. 모든 불확실한 증례에서 수직 지근파절의 최종 진단은 외과적 탐지를 통해 이루어졌고, 금이 간 치아와 관련될 수 있는 치근파절의 증례의 경우는 제외되었다. 근관치료된 치아와 치료되지 않은 치아, 환자의 나이와 성별, 치아종류 및 파절된 치근부위, 자각증상의 유무를 기준으로 각각의 수치와 백분율로 분류하였다. 수직 치근파절의 증상과 증후별로 분류하였으며, 진단방법에 의한 분류, 치료방법에 따른 분류, 근관 치료 후 수직 치근파절이 발생한 기간에 따른 분류를 시행하고 통계분석을 하여 다음과 같은 결과를 얻었다. 1. 근관치료를 받지 않았던 치아의 수직 치근파절의 발생율은 58%였다. 2. 성별에 따른 발생률에 있어서 남성의 호발양상을 나타내었다. 3. 근관치료된 치아에 있어서 치료되지 않은 치아에 비해 호발연령이 낮았다. 4. 전치부의 수직 치근파절은 관찰되지 않았으며 특히, 강한 교합력을 필요로 히는 구치부에서의 높은 발생율을 나타냈다. 5. 수직 치근파절의 가장 주된 증상 및 증후는 깊은 치주낭 깊이였다. 6. 근관 치료 후 수직 치근파절이 발생한 기간은 평균 5.7년이었다. 7. 다수 증례에 있어서 3개 이하의 결손치를 가졌고, 자각증상이 나타났다. 이상의 결괴에서 한국인에 있어서 근관치료를 받지 않은 치아의 수직 치근파절은 드문 현상이 아님을 알 수 있었고 남성과 구치부에 있어서의 높은 발생율을 알 수 있었다. 그 이유로는 강한 교합력, 딱딱한 음식의 저작습관, 치조골 흡수에 따른 낮은 저항성, 골 유연성의 저하 등으로 여겨진다. 그러나, 수직 치근파절은 아직까지 정확한 진단을 내리기는 여전히 어려운 상태이며, 이를 위한 다양한 진단방법 및 더 나은 연구가 필수적이라 하겠다. 그리고, 향후 보다 많은 증례에 대한 분석, 치주질환에 이환되지 않은 경우의 분석, 치료 후 생존 기간에 대한 고찰 등도 필요하리라 사료된다.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.2
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• pp.295-310
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• 2014

DCS (Distributed Control System), the main control system of power plants, is an automated system for enhancing operational efficiency by monitoring, tuning and real-time operation. DCS is becoming more intelligent and open systems as Information technology are evolving. In addition, there are a large amount of investment to enable proactive facility management, maintenance and risk management through the predictive diagnostics. However, new upcoming weaponized malware, such as Stuxnet designed for disrupting industrial control system(ICS), become new threat to the main control system of the power plant. Even though these systems are not connected with any other outside network. The main control systems used in the power plant usually have been used for more than 10 years. Also, this system requires the extremely high availability (rapid recovery and low failure frequency). Therefore, installing updates including security patches is not easy. Even more, in some cases, installing security updates can break the warranty by the vendor's policy. If DCS is exposed a potential vulnerability, serious concerns are to be expected. In this paper, we conduct the penetration test by using NESSUS, a general-purpose vulnerability scanner under the simulated environment configured with the Ovation version 1.5. From this result, we suggest a log analysis method to detect the security infringement and react the incident effectively.

• The Journal of the Korea Contents Association
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• v.21 no.2
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• pp.499-506
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• 2021

Hackers' cyber attack techniques are becoming more sophisticated and diversified, with a form of attack that has never been seen before. In terms of information security vulnerability standard code (CVE), about 90,000 new codes were registered from 2015 to 2020. This indicates that security threats are increasing rapidly. When new security vulnerabilities occur, damage should be minimized by preparing countermeasures for them, but in many cases, companies are insufficient to cover the security management level and response system with a limited security IT budget. The reason is that it takes about a month for analysts to discover vulnerabilities through manual analysis, prepare countermeasures through security equipment, and patch security vulnerabilities. In the case of the public sector, the National Cyber Safety Center distributes and manages security operation policies in a batch. However, it is not easy to accept the security policy according to the characteristics of the manufacturer, and it takes about 3 weeks or more to verify the traffic for each section. In addition, when abnormal traffic inflow occurs, countermeasures such as detection and detection of infringement attacks through vulnerability analysis must be prepared, but there are limitations in response due to the absence of specialized security experts. In this paper, we proposed a method of using the security policy information sharing site "snort.org" to prepare effective countermeasures against new security vulnerability attacks.

• Geophysics and Geophysical Exploration
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• v.16 no.3
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• pp.163-170
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• 2013

The amplitude variation with offset of seismic data can detect fluids in the sediment and resolve the petrophysical properties of hydrocarbons in the subsurface. We analyzed and described the amplitude variation in deep sea seismic data obtained from the Ulleung Basin, East Sea. By inspecting seismic CDP-offset and CDP-angle gathers which show a bright reflection event, we decided a target zone for amplitude variation analysis. From the seismic angle gather at the middle of Ulleung Basin, we recognized amplitude increase or decrease versus offset on the intercept-gradient curve. Using the product attribute and Poisson's ratio change attribute computed in terms of intercept with gradient, the top and the base of gas saturated sediments were described. The area of amplitude variation suggestive of the presence of gas saturated sediments is shown at the depth of 3 s traveltime. Anomalous features of seismic amplitude in the Ulleung Basin were classified by the crossplot of intercept and gradient. The background trend of crossplot between intercept and gradient shows an inverse proportional relation that is common for wet sediments. Anomalous amplitudes of Class III fall into the first and the third quadrants on crossplots. We inferred regional gas/water saturated area with the horizontal dimension of 150 m in the Ulleung Basin by cross-section with respect to cross-plot anomaly.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.2
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• pp.81-94
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• 2005

The purpose of this study is to test the applicability of landscape metrics for quantifying and monitoring the landscape structure in the Geumho River watershed, which has undergone heavy environmental disturbances. Landscape metrics were computed from land cover maps(1985, 1999) for the forest patches. The number of variables were reduced from 12 metrics to 3 factors through factor analysis. These factors accounted for above 91% of the variation in the original metrics. We also determined the relative effects of land development on the changes of forest landscape structure using multiple linear regression analysis. At the forest patches, the conversion of forest to urban areas and agriculture resulted in increased fragmentation. Patch area and patch size decreased. and patch density increased as a result of the conversion of forest to agriculture($R^2=0.696$, p<0.01). The heterogeneity of patch size and complexity of patch shape mainly decreased as a result of the conversion of forest to urban areas($R^2=0.405$, p<0.01). The density of core area and edge showed the tendency increase, but there was no relationship with the conversion of forest to urban area and agriculture The future research will be needed to analyze correlations between landscape structures and specific environmental and socioeconomic landscape functions.

• Korean Journal of Remote Sensing
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• v.28 no.1
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• pp.129-143
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• 2012

This paper demonstrates the effectiveness of advanced spatial modeling techniques for environmental monitoring and impact assessment through a case study of Chernobyl nuclear accident occurred in 1986. Land-cover types changed after the accident are analysed by a post classification comparison method using bi-temporal Landsat TM data acquired in 1986 and 1992 near the accident site. Spatial modeling including various kriging algorithms are also applied to analyze the relationships between Cesium concentrations in soil and thyroid cancer incidence rates in Belarus, which was greatly damaged by the accident. The change detection results clearly showed the decrease of croplands and the increase of abandoned lands, and concrete structures were newly built around the nuclear plant to prevent the spread of radioactive contamination. In Belarus, high Cesium concentrations were observed in southern areas with high thyroid cancer risk estimated by Poisson kriging. Geographically weighted regression, which could account for geographic variations of independent variables including Cesium concentrations and distances from the Chernobyl nuclear power plant, was applied to extract the relationships between the independent variables and the thyroid cancer risk. The estimated risk values showed a correlation coefficient value of 0.98 with respect to the thyroid cancer risk values, which implied that the thyroid cancer risk in Belarus was affected by the accident. In conclusion, it is expected that advanced spatial modeling techniques applied in this study would be useful for environmental impact assessment and public health research.