‘주민이 주인이 되는’ 풀뿌리 자치 실현을 기대하며

성장현 한국자치학회 2019 월간 공공정책 Vol.159 No.-

Assessment of Inter-Model Variability in Meteorological Drought Characteristics Using CMIP5 GCMs over South Korea

성장현,박준형,전종준,서승범 대한토목학회 2020 KSCE JOURNAL OF CIVIL ENGINEERING Vol.24 No.9

Although many studies have sought to characterize future meteorological droughts, a few efforts have been done for quantifying the uncertainty, inter-model variability, arises from global circulation models (GCM) ensemble. A clear understanding of the uncertainty in multiple GCMs should be preceded before future meteorological droughts are projected. Therefore, this study evaluates the uncertainty in future meteorological drought characteristics that are induced by GCM ensemble using the custom measure “the degree of GCM spreading”. Future meteorological drought indices, the standardized precipitation index (SPI) and standardized precipitation evapotranspiration index (SPEI), were computed to five different time scales: 3, 6, 9, 12 and 24 months using statistically downscaled 28 GCMs under Representative Concentration Pathway (RCP) 4.5 and 8.5 at 60 weather stations in South Korea. The frequency, duration, and severity of drought events were estimated for three different future periods; F1 (2010  2039), F2 (2040  2069), and F3 (2070  2099). It was found that the uncertainty increases as the time scale lengthens regardless of a choice of drought indices or RCP scenarios. It also turned out that the SPI exhibits larger uncertainty rather than the SPEI, because temperature data exhibit a relatively much smaller variability comparing to precipitation data. Moreover, there was a shift of regions having larger values of the increasing rate between F1 and F2, which is shift from the north-western to southern region of South Korea.

Multivariate Frequency Analysis for Streamflow Drought Having Different Time Resolution Using Archimedean Copula Functions

성장현,류영,정은성 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.4

This study explored return periods of the streamflow deficit characteristics by threshold levels with different time resolutions (daily, weekly, and monthly) using univariate and Copula functions, reflecting hydrological regimes like rapid recoveries from drought and anthropogenic dam operation by monthly basis in South Korea. As a result, the daily-based threshold had a large variability in severities and durations. This is because threshold levels include a large variability of daily streamflow with a small time interval. Joint return periods of duration under extreme droughts were similar to those from univariate frequency analysis. The severities in these extreme droughts were also around the average level, but the duration was relatively long, leading to an increase in the joint return period. This result helps to effectively manage water resource preparing for the assessment on the drought risk with a long duration.

304L 스테인레스강의 변태유기 소성에 미치는 변형온도의 영향

성장현,강창룡 동아대학교 공과대학 부설 한국자원개발연구소 1992 硏究報告 Vol.16 No.1

The effect of deformation temperature on transformation induce plasticity in 304L stainless steel with metastable austenitic phase investigaged. The result obtained from this study are summarized as follows. Tensile properties of the metastable austenitic 304L stainless steel remarkably influenced by deformation temperature and mainly controlled by transformation induced martensite. Tensile strength increased with decreasing deformation temperature and the elongation showed maximum value near 40℃ With lowering the deformation temperature, the volume fration of transformation induced martensite increased at the same strain. ε-martensite was formed at the begining stage of deformation in the low temperature region of low stability of austenite. The volume fration of ε-martensite increased with increasing strain and decreased after showing the maximum value. The maxium quantity of ε-martensite was obtained at low strain with decreasing deformation temperature.

5083 Al 합금 용접재의 조직 및 저온 인장성질에 미치는 시효처리의 영향

성장현,이해우,주동원,이준희,이태청 한국열처리공학회 2000 熱處理工學會誌 Vol.13 No.1

The microstructural characteristics and low temperature tensile properties between 25℃ and -196℃ for as-welded and age hardened specimen by using Al 5083-H321 for base metal, 5083-5356 and 5083-4043 weldments have been investigated. The hardness of 5083-5356 weldment decreases with aging treatment, whereas the weld region of 5083-4043 weldment shows remarkable increase in hardness after aging due to the precipitation of fine Si particle at the grain boundaries and interiors. Low temperature tensile properties of 5083 Al base metal, 5083-5356 and 5083-4043 weldments appear to be the increment of tensile strengths and elongations at the room temperature and -196℃, while the decrement of tensile properties around -50℃ is shown. Through the observation of fine serration to fracture in the stress-strain curve and tensile fractography, the increment of localized deformation leading to promote the neck initiation and the increment of the dimple size cause to decrease in tensile strengths and elongations around -50℃. For the tensile specimen of the 5083 base metal, 5083-5356 and 5083-4043 weldments, the reason to increase in elongation after solution and aging treatment is the diminishment of fine pit, the resolution of Mg into the matrix and the spheridization of the eutectic Si.

복합조직강의 열처리경로가 조직학적인자 및 기계적성질에 미치는 영향

성장현 東亞大學校 海洋資源硏究所 1988 硏究論文集 Vol.1 No.1

The effect of changes in heat treatment paths and the addition of alloying elements on the formation of ferrite and austenite in dual phase steel heat treated in the two phase field of both ferrite and austenite were investigated. For this investigation Fe-C-Mn-Cr and Fe-C-Mn-Mo alloys were prepared throughout the experiment. The results obtained from this study are summarized as follows. The growth rate of ferrite obtained during isothermal heat treatment in the range of ferrite plus austenite directly from austenite single phase region decreased with the addition substitutional alloying elements such as Mn, Cr and Mo. This phenomena were remarkable with increasing temperatures of isothermal heat treatment. The carbide particles exsisted in the matrix of ferrite became a source of carbon supply at the austenites which were in the vicinity of grain boundary of ferrite. The easist diffusion path of carbon atom from ferrite matrix to austenite was the dislocations formed near to the ferrite due to the continuous growth of austenite. The volume fraction of martensite for the specimens isothermally heat treated after austenitization was shown to be remarkably different compared to that for the specimens obtained by using intercritical annealing, depending on the addition of Cr and Mo. The substitutional alloying elements involved were considered to become more effective to inhibit the formation of ferrite than to accerate the austenite formation. During intercritical annealing of the steel which has the initial structure of ferrite and carbide, tensile strength increased and yield strength became lowered with the formation of austenite at the grain boundaries of ferrite and simultaneously dissolution of carbide. Yield strength and elongation became minimum and maximum respectively after remarkable dissolution of pearlite and carbides.

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.

Deep Learning-Based Prediction of Fire Occurrence with Hydroclimatic Condition and Drought Phase over South Korea

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.

고탄소 베이나이트 - 마르텐사이트 2상 혼합 조직강의 베이나이트 변태 특성 및 기계적 성질

성장현,안진환 대한금속재료학회 1987 대한금속재료학회 학술대회 개요집 Vol.1987 No.0

복합조직강의 ferrite 와 Austenite 형성에 미치는 합금원소의 영향

성장현,윤한상 대한금속재료학회 1984 대한금속재료학회 학술대회 개요집 Vol.1984 No.0