• 전기학회논문지
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• 제66권11호
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• pp.1641-1646
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• 2017

This paper presents a fast method to identify an area of severity which is a network area leading to voltage sags at multiple sensitive load points, simultaneously. To assess voltage sag performance considering various sensitive loads, it is need to determine an area of severity for the load points. The area of severity can be calculated by overlapping areas of vulnerability for each sensitive load. However, as the number of sensitive loads increases, computational complexity and time for determining an area of severity are highly increased. In this paper, an efficient scheme based on line division is described. The proposed method is useful for identifying an area of severity and assessing voltage sag performance considering multiple loads together.

• 전기학회논문지
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• 제59권6호
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• pp.1034-1040
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• 2010

This paper presents a calculation method of the area of severity for the stochastic assessment of voltage sags. In general, the annual expected numbers of voltage sags at an individual load point can be estimated stochastically. However, in order to assess the system voltage sag performance considering many sensitive load points together, it is necessary to determine and analysis the area of severity for the load points. The area of severity to voltage sags is the network region where the fault occurrences will simultaneously lead to voltage sags at different load points. In this paper, the concept of the voltage sag assessment and the calculation method of the area of severity are addressed. The analysis of the area of severity is performed on the IEEE 30-bus test system by using the proposed method. The method is useful for the stochastic assesment of voltage sags and the establishment of systematic plans for voltage sag mitigation.

• 한국방재학회:학술대회논문집
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• 한국방재학회 2007년도 정기총회 및 학술발표대회
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• pp.231-237
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• 2007

To monitor process of vegetation rehabilitation at the damaged area after large-fire is required a lot of manpowers and budgets. However the analysis of vegetation recovery using satellite imagery can be obtaining rapid and objective result remotely in the large damaged area. Space and airbone sensors have been used to map area burned, assess characteristics of active fires, and characterize post-fire ecological effects. Burn severity incorporates both short- and long-term post-fire effects on the local and regional environment. Burn severity is defined by the degree to which an ecosystem has changed owing to the fire. To classify fire damaged area and analyze burn severity of Samcheok fire area occurred in 2000, Cheongyang fire 2002, and Yangyang fire 2005 was utilized Landsat TM and ETM+ imagery. Therefore the objective of the present paper is to quantitatively classify fire damaged area and analyze burn severity using normalized burn index(NBR) of pre- and post-fire's Landsat satellite imagery.

• 재활간호학회지
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• 제6권1호
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• pp.7-13
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• 2003

Purpose: To identify the essential characteristics of pain which nurse have to obtain for patients with chest pain, 92 patients who were admitted in medical units to take intensive tests for heart disease were investigated cross-sectionally. Method: Duration, severity, stress, anxiety, perceived severity, number of painful area, number of accompanying symptoms, triggering activity, and pattern were included as the characteristics of pain. Ejection fraction of left ventricle and number of involved area detected by ultrasonography and number of diseased coronary artery detected by cardiac catheterization were assessed as the variables of heart disease extent. Result: Severity of pain was found to be correlated with all three variables of heart disease extent. Perceived severity and number of accompanying symptoms were correlated with two of them. Anxiety, number of painful area and pattern were related with the number of involved area. Conclusion: Pain severity reported by patients is found to be the most important variable to be obtained from patient. Variables such as perceived severity, number of accompanying symptoms, anxiety, number of painful area and pattern also have to be carefully assessed to anticipate the extent of heart disease.

• 전기학회논문지
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• 제64권11호
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• pp.1611-1617
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• 2015

This paper presents an effective approach for establishing countermeasures against voltage sags based on the concept of area of severity. In order to apply preventive measures against faults such as lightning arrester, overhead earth wires and so on, it is important to find optimal points for installing the preventive measures. The optimal points can be determined by the calculation of the area of severity(AOS) to voltage sags and the expected sag frequency per unit length of line. In this paper, an effective method to find optimal points to apply countermeasures against voltage sags is addressed with case studies.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2005년도 학술발표회 논문집
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• pp.867-872
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• 2005

This study introduces a method to evaluate the probability of a specific area to be affected by a drought of a given severity and shows its potential for investigating agricultural drought characteristics. The method is applied to Gyeonggi as a case study. The proposed procedure includes Standard Precipitation Index(SPI) time series, which are linearly transformed by the Empirical Orthogonal Functions(EOF) method, These EOFs are extended temporally with AutoRegressive Moving Average(ARMA) method and spatially with Kriging method. By performing these simulations, long time series of SPI can be simulated for each designed grid cell in whole Gyeonggi area. The probability distribution functions of the area covered by a drought and the drought severity are then derived and combined to produce drought severity-area-frequency(SAF) curves.

• 한국지리정보학회지
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• 제10권3호
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• pp.80-92
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• 2007

산불은 우리나라 산림의 주요 교란요소중의 하나로써 산림 구조와 기능에 매우 큰 영향을 미치며, 산불피해강도에 따라 피해 후 식생회복 과정이 달라질 수 있다. 대형산불 피해지의 피해강도와 식생회복 과정을 파악하기 위해서는 많은 인력과 예산이 필요하지만 위성영상자료를 이용한 산불피해지의 피해강도 분석은 신속한 정보는 물론 대규모 피해지의 객관적인 결과를 원격적으로 취득할 수 있다. 위성과 항공기 탑재 센서들은 피해규모를 맵핑하고 진행산불 특성을 평가하며 산불피해후의 생태적 영향 특성을 규명하는데 활용되고 있다. 본 연구에서는 2000년 삼척산불, 2002년 청양산불 그리고 2005년 양양 대형산불 피해지를 구분하고 피해강도를 정량적으로 분석하기 위해 정규탄화지수(Normalized Burn Ratio: NBR)를 활용하였다. 본 연구를 위해 산불피해 전후 동일시기의 Landsat 위성영상 자료를 활용하여 정규탄화지수(NBR)를 산출하고 30m 해상도의 피해강도 패턴을 평가하였다. 산불피해강도 평가결과, 삼척산불 피해지는 피해강도 '중' 이상(${\Delta}NBR$ 152 이상) 지역이 전체의 65%를 차지하였으며 청양 예산산불피해지는 91%, 양양산불피해지는 65%로 나타나 3지역 중 청양 예산지역이 피해강도 측면에서만 보면 가장 큰 피해를 입은 것으로 분석되었다. 따라서 RS와 GIS를 이용하여 원격 탐지된 ${\Delta}NBR$은 대규모 산불피해지의 구분은 물론 산불피해강도를 공간적으로 정량화할 수 있다.

• 말소리와 음성과학
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• 제2권2호
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• pp.85-92
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• 2010

The purpose of this study was to know the differences in perceptual judgement for speech intelligibility in monosyllables by inexperienced listeners and vowel space area according to different dysarthric severity. Three dysarthric speakers with different severity(mild, moderate and severe) screened by 3 clinicians' screening tests before the experiment were conducted. Corner vowels (i, u, ae, a) in monosyllable level (CVC, 'p_p') and carrier phrases ('종이에_써') were chosen and analyzed for vowel space. Inexperience listeners (n=20) performed the intelligibility test for spoken syllables and carrier phrases by dysarthric speakers. The results show that there is a significant differences in both F1 and F2 values among 4 corner vowels. Vowel space area in the data of mildly impaired speakers was significantly higher than two others. In the scores of speech intelligibility judged by inexperienced listeners, the scores by a moderately impaired speaker were more higher than two other speakers. The discrepancy between perceptual judgement by inexperienced listeners and vowel space area will be discussed in this area.

• 한국지형학회지
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• 제28권1호
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• pp.83-99
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• 2021

Burn severity analysis using satellite imagery has high capabilities for research and management in inaccessible areas. We extracted the forest fire area of the DMZ (Demilitarized Zone) in the western Imjin Estuary which is restricted to access due to the confrontation between South and North Korea. Then we analyzed the forest fire severity and recoverability using atmospheric corrected Surface Reflectance Level-2 data collected from Landsat-8 OLI (Operational Land Imagery) / TIRS (Thermal Infrared Sensor). Normalized Burn Ratio (NBR), differenced NBR (dNBR), and Relative dNBR (RdNBR) were analyzed based on changes in the spectral pattern of satellite images to estimate burn severity area and intensity. Also, we evaluated the recoverability after a forest fire using a land cover map which is constructed from the NBR, dNBR, and RdNBR analyzed results. The results of dNBR and RdNBR analysis for the six years (during May 30, 2014 - May 30, 2020) showed that the intensity of monthly burn severity was affected by seasonal changes after the outbreak and the intensity of annual burn severity gradually decreased after the fire events. The regrowth of vegetation was detected in most of the affected areas for three years (until May 2020) after the forest fire reoccurred in May 2017. The monthly recoverability (from April 2014 to December 2015) of forests and grass fields was increased and decreased per month depending on the vegetation growth rate of each season. In the case of annual recoverability, the growth of forest and grass field was reset caused by the recurrence of a forest fire in 2017, then gradually recovered with grass fields from 2017 to 2020. We confirmed that remote sensing was effectively applied to research of the burn severity and recoverability in the DMZ. This study would also provide implications for the management and construction statistics database of the forest fire in the DMZ.

• 대한토목학회논문집
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• 제26권1B호
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• pp.69-78
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• 2006

제반 수문학적 문제 해결을 위하여 강우사상에 대해 최대평균우량깊이-유역면적-지속기간 관계곡선을 작성하고 있다. 본 연구에서는 상기 관계곡선의 항목 중 최대평균우량깊이를 가뭄심도의 항으로 대체한 가뭄심도-영향면적-지속기간 관계 곡선의 작성방법을 제시하고자 한다. 우리나라 전역의 기상청 월 강수량 자료로부터 산정된 SPI 가뭄지수는 EOF 기법을 이용하여 핵심적인 공간정보로 축약되며, 이를 다시 Kriging 기법을 이용하여 우리나라 전역에 대해 $6km{\times}6km$의 해상도를 가진 SPI 값으로 할당하였다. 격자기반의 가뭄지수 자료의 시간적 분포특성과 공간특성이 고려된 주요 가뭄사상을 식별한 후, 이를 분석하여 최종적으로 영향면적별 지속시간별 가뭄지수가 산정된다. 이에 따라 가뭄심도-가뭄면적-가뭄지속기간 관계곡선이 도시된다. 우리나라 전역에 대한 곡선 작성 결과, 지속기간이 짧고 영향면적이 작을수록 가뭄심도가 깊어지며 영향면적이 증가할수록 가뭄심도가 낮아진다는 면에서는 강우분석시와 비슷한 모양을 보여준다고 할 수 있으나, 가뭄심도의 면적에 따른 감소율은 가뭄분석시의 강우깊이의 면적에 따른 감소율보다 훨씬 작은 것으로 나타났다.