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성장현,류영,성기원 대한토목학회 2022 KSCE Journal of Civil Engineering Vol.26 No.4
This study evaluates the effects of climatic conditions and drought phase on occurrence frequency (OF) of forest fire in South Korea, and suggested a deep learning-based estimator for the occurrence frequency of fire. There was a high correlation between frequency and relative humidity (RH, R = -0.663) and wind speed (WS, R = 0.532). Using these correlations, we proposed a deep learning model that can estimate the OF. Among the three deep learning models (RH-WS-AMOF, RH-AMOF, and WS-AMOF) by combining RH and WS with average monthly OF (AMOF) during 1997 − 2019, the RH-WS-AMOF model showed the best performance. R2 and NSE were 0.838 and 0.828, respectively. The higher temperatures and drought lead to increase the potential for forest fire. Standardized precipitation evapotranspiration index was introduced for exploring the link between meteorological drought and forest fire. We confirmed that SPEI can improve the performance of the DBN based on OF estimator in spring. The framework of this study can provide a predictive model for forest fire OF combined with a weather forecast model.
2013년 강우 및 홍수사상 분석: 영산강·섬진강 유역
성장현,이준호,원유승,김양수 한국방재학회 2014 한국방재학회 학술발표대회논문집 Vol.2014 No.-
본 연구에서는 2013년 영산강과 섬진강 유역에 발생한 강우 및 홍수사상을 평년 및 예년과 비교하여 분석하였다. 분석결과, 6월, 8월∼9월은 평년대비 50% 수준에 그쳤으나, 7월은 장마전선의 영향으로 4일부터 7일까지 유역평균 250mm 강우를 기록하였다. 8월은 작년과 달리 태풍의 직접적인 영향이 없었으나, 23일과 24일에는 유역평균 140mm의 호우가 집중되었다. 강우에 따른 수위 변화를 알아보면 연중 최고수위가 7월 5일에 발생하였고, 이 때에 선암(황룡강), 나주(영산강), 구례2와 송정지점(섬진강)에 홍수주의보가 발령되기도 하였다. 농업용 저수지(광주, 담양, 장성과 나주) 및 다목적 댐(섬진강, 주암, 탐진)의 11월말 수위를 보면 전반적으로 전년에 비하여 낮은 편이었고, 그 중 광주댐은 전년대비 4.60m, 섬진강댐은 9.15m으로 낮은 편이었다.
저항복비를 갖는 건축구조용 내화강의 강도 특성에 미치는 N 첨가의 영향
성장현,배동수,강창룡,추봉식,주동원,김익수 대한금속재료학회(대한금속학회) 2001 대한금속·재료학회지 Vol.39 No.11
The present study investigated the effect of N addition on the strength characteristics of 0.1%C-1%Mn-0.5%Mo-0.02%Ti fire-resistant steel for construction with low yield ratio. 0.1%C-1%Mn-0.5%Mo-0.02%Ti(A) and 0.1%C-1%Mn-0.5%Mo-0.02%Ti-0.015%N(B) specimens showed bainite phase in matrix of ferrite and pearlite phase, the addition of N suppressed the transformation of pearlite and accelerated transformation to bainite. Yield strength(Y.S) ratio, yield and tensile strength of B specimen was higher value than those of A specimen, but yield ratio(Y.R) value was lower. In the two specimens treated by air cooling or quenching and tempering after rolling, yield strength and Y.S ratio decreased slowly with increasing test temperature, and rapidly decreased at over 600℃. But Y.S ratio at 600℃ was higher than 70%. In case of specimen tempered after quenching, yield and tensile strength were higher than that of air cooling specimen but Y.S ratio was lower. With increasing finish rolling temperature, volume fraction of ferrite and pearlite phase was decreased, and volume fraction of bainite and Y.S ratio was rapidly increased, while Y.R value was unchanged. In two specimens, Y.S ratio was strongly controlled by volume fraction of second phase, but Y.R value and yield strength were affected by other factors than the volume fraction of second phase.
Al 함유 13%Cr 스테인리스강의 표면 질소침투 열처리에 미치는 첨가원소 탄소의 영향 : 13%Cr 스테인리스강의 고질소 표면침투 열처리
성장현,주동원,김기돈,유대경,박진욱 한국열처리공학회 2000 熱處理工學會誌 Vol.13 No.3
This study aims to investigate the effect of carbon content on the surface nitrogen permeation of 13%Cr-1.8%Al alloyed stainless steels. The surface nitrogen permeation was performed at 1050℃-1200℃ in the 1㎏/㎠ nitrogen gas atmosphere. The nitrogen permeated surface layer of the specimen containing 0.03%C consists of AlN, martensite and retained austenite phases, while the surface layer of the specimen containing 0.14%C appears the AlFe₃C_x phase including former three phases. The specimen containing 0.14%C shows lower total case depth than that containing 0.03%C at the nitrogen permeation temperatures of 1050℃ and 1100℃, while the total case depth of the specimen containing 0.14%C is remarkably increased at the temperature of 1150℃ and 1200℃ due to the increase in the retained austenite content. Martensitic phase, AlN and AlFe₃C_x precipitate of the nitrogen permeated surface layer cause to increase the surface hardness of 550∼600Hv.
성장현,정은성,김양수 한국방재학회 2014 한국방재학회 학술발표대회논문집 Vol.2014 No.-
하천수 가뭄을 평가하기 위하여 임계수준 방법을 이용한 하천수 가뭄지수 (streamflow drought index)를 소개하고 섬진강댐의 유입량을 대상으로 적용하였다. 사용한 임계수준은 고정, 월별 및 일별로써 연도별 가뭄의 1순 ~3순위 분석결과, 1984년, 1988년과 1995년이 수문학적 가뭄의 크기도 컸고 오랫동안 지속되었다. 총 물 부족량과 지속기간의 극한값을 연도별로 비교해 본 바, 1984년, 1988년, 1995년과 2001년에 발생하였던 사상이 심각한 수준이었다. 연구결과, 고정 임계수준은 계절 변동성을 반영하지 못하는 단점이 있어서 최소한 계절 이하의 임계수준 사용이 요구되었지만 월별과 일별로 정해진 임계수준은 적정하였다. 본 연구에서 제안한 방법론은 갈수예보 및 저수지 용량결정에 활용될 수 있겠다.
複合 組織鋼의 引張性質에 미치는 組織學的 因子에 관하여
成章鉉,韓元澤 동아대학교 공과대학 부설 한국자원개발연구소 1984 硏究報告 Vol.8 No.1
Morphological factors affecting tensile properties were investigated by metallography, tensile test and particle analysis after manufacturing Austenite Dual Phase steel (ADP steel) and Intercritical Dual Phase steel(IDP steel) by heat treatment of Fe-Mn and Fe-Mn-Cr systems. 1) The formation of austenite was largely affected by initial structures before intercritical annealing, and austenite grew from the pearlite colony in Fe-Mn system but grew discontinuously along the plate of cementite in Fe-Mn-Cr system. 2) As for the effects of Cr on the tensile properties, tensile strength and elongation are low for step quenching, but tensile strength increased and elongation decreased slightly for intercritical annealing. 3) In Fe-Mn-Cr system tensile strength and elongation of IDP steel were excellent than those of ADP steel due to the discontinuous dispersion of fine martensite particles at the same volume fraction.
What is the Impact of COVID-19 on Residential Water Use?
성장현,정은성 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.12
The characteristics of residential water use (RWU) can be impacted by climate change and anthropogenic factors. This study explored the impact of the COVID-19 pandemic and the temperature rise in RWU. First, the change in RWU was estimated based on temperature using a deep learning technique and compared with the observed RWU. As a result, there was an increase in estimated RWU due to the increase in temperature, similar to previous studies. However, the estimated RWU was smaller than the observed RWU. Second, we explored the causes of RWU that did not increase as expected. The reason for the lower-than-expected observations could be found in the number of new confirmed COVID-19 cases. As the number of new confirmed cases increased, the observed RWU decreased in a linear relationship. Due to the restrictions on gatherings of more than 5 people and restrictions on public facilities and bathhouses due to social distancing measures, commercial, public and bathhouse water use has decreased compared to before COVID-19. The COVID-19 pandemic affected RWU, which was less than the annual average in 2021. The increase in water consumption due to climate change was temporarily controlled by the COVID-19 pandemic. A sustainable long-term plan is needed to maintain this environmental benefit because of the COVID-19 pandemic, which can also contribute to preventing future epidemics.