급속 응고된 Fe Al 1-x Cu x 합금의 자기적 성질에 관한 연구

김이현,윤석길 대한금속재료학회(대한금속학회) 1987 대한금속·재료학회지 Vol.25 No.10

Magnetic measurements on the rapidly solidified Fe Al_(1-x)Cu_x series (x = 0.05-0.40) have been made at temperatures from 77˚K up to 700˚K, and compared with those of the annealed specimens. It was found that ferromagnetis appealed in the alloys with x≥0.30, and the alloys with x≤0.25 remained paramagnetic down to 77˚K. In the ferromagnetic region, magnetization increarses as x increases and so does the Curie point. Rapidly solidified specimens show higher magnetizations and Curie temperatures than those of the annealed. X-ray diffraction data revealed that both specimens, rapidly solidified or annealed, were single-phased in CsCl(B₂) structure with a virtually constant lattice parameter of 2.91A. Rapidly solidified alloys, however, exhibited some extent of disorder in the site occupancies of Al atoms and Fe atoms. The results were analized in terms of the local environmental effect of magnetic atoms.

Estimation of Rice Growth Using RADARSTA-2 SAR Images at Seosan Region

김이현,홍수경,이경도,장소영 한국토양비료학회 2013 한국토양비료학회지 Vol.46 No.4

Radar remote sensing is appropriate for monitoring rice because the areas where this crop is cultivated are often cloudy and rainy. Especially, Synthetic Aperture Radar (SAR) can acquire remote sensing information with a high temporal resolution in tropical and subtropical regions due to its all-weather capability. This paper analyzes the relationships between backscattering coefficients of rice measured by RADARSAT-2 SAR and growth parameters during a rice growth period. We examined the temporal variations of backscattering coefficients with full polarization. Backscattering coefficients for all polarizations increased until Day Of Year (DOY 222) and then decreased along with Leaf Area Index (LAI), fresh weight, and Vegetation Water Content (VWC). Vertical transmit and Vertical receive polarization (VV)-polarization backscattering coefficients were higher than Horizontal transmit and Horizontal receive polarization (HH)-polarization backscattering coefficients in early rice growth stage and HH-polarization backscattering coefficients were higher than VV-polarization backscattering coefficients after effective tillering stage (DOY 186). Correlation analysis between backscattering coefficients and rice growth parameters revealed that HH-polarization was highly correlated with LAI, fresh weight, and VWC. Based on the observed relationships between backscattering coefficients and variables of cultivation, prediction equations were developed using the HH-polarization backscattering coefficients.

Dependence of Nutrient Supplying Capacity on Chemical reactions of Paddy Soil

김이현,김명숙,강성수,조현준 한국토양비료학회 2009 한국토양비료학회지 Vol.42 No.4

The practice of supplying nutrients for paddy soil with sustaining human health and ecological soundness is to utilize indicators considering soil chemical reactions. The long-term basis experiment of fertilizer and amendment of paddy soil and an experiment of yield response of soil types on nitrogen level from 2000 till 2002 were used to search indicators of nutrient supplying capacity related to soil chemical reactions. Chemical reactions of paddy soil was composed of dissociating and/or adsorbing nutrients and of decomposing soil organic matter (SOM) into H+, e, CO2 in paddy soil. The indicators of nutrient supplying capacity, which were established by considering soil chemical reactions, were SOM or soil protein for nitrogen and available phosphate for phosphorus and cation exchangeable capacity (CEC) and exchangeable potassium for potassium. Korea has used fertilizer recommendation equations established with the indicators of nutrient supplying capacity for paddy soil which are.

서울시 행정 구역과 이웃 효과 관계 탐색: 한국종합사회조사(KGSS) 및 행정 자료 연계

김이현,김지범,강정한 한국조사연구학회 2020 조사연구 Vol.21 No.2

Studies on neighborhood-level effects in South Korea have been focusing on the level of gu, which may fail to represent regions as living environments because goon/gu have large within-region variation. This study zooms into the level of dong, which is much finer than gu and may revive research on neighborhood-level effects in South Korea. We selected Seoul residents from a dataset of Korean General Social Survey (KGSS, 2003-2016) and matched them to dong-level information from three administrative data sources: Seoul Open Data Plaza (2003-2017), National Election Commission (2006-2017), and Seoul Real Estate Information Plaza (2006-2017) (=2,656). Variance analysis of selected variables from KGSS and administrative data confirmed that between-dong variations are larger than between-gu variations and thus suggests that dong-level estimations are more promising than gu-level estimations of neighborhood effects on residents. We estimated how much Seoul citizens’ various attitudes were affected by the average price of apartment transactions and the percentage of the older population at the dong level and compared them with those at the gu level. Estimates at the dong level tended to be larger and more significant than those at the gu level. Controlling for gender, age and education levels, respondents from dongs with higher percentage of older people reported lower household income and lower self-appraised class, which were not observed in the same analysis with gu-level variables. By conducting multi-level, multisource analysis, we showed the analytic potential of combining dong-level information with social surveys from large cities in South Korea. 지금까지 사회조사 자료와 지역 단위 행정 자료를 결합하는 이웃 효과 연구는 주로 시 ‧ 군‧ 구 단위에서 진행해 왔으나, 시‧ 군 ‧ 구 단위가 생활환경 단위로서의 지역을 대변하지 못하며, 시‧ 군 ‧ 구 내의 더 작은 지역 단위 간의 이질성이 서로 상쇄되어 지역 효과를 포착하기 힘들었다. 이러한 문제의식에서 출발한 본 연구는 서울시 주민에게 미치는 동 수준의 지역 효과를 탐색하고 향후 연구의 방향을 모색하고자 하였다. 사회조사 자료는 2003~2016 한국종합사회조사(KGSS) 누적 응답자 중 서울 거주자를 선택했으며, 서울시 동 수준의 행정 정보는 2003~2017 서울열린데이터광장, 2006~2017 중앙선거관리위원회 및 2006~2017 서울부동산정보광장에서 수집, 결합하였다( =2,656). (1) 우선 지역 수준에서는 출생률, 고령자 인구 비율, 기초생활수급자 비율, 투표율, 평균 아파트 거래가격 등을 구 단위와 동 단위에서 수집한 후 분산을 분석한 결과, 동 간의이질성이 구 간의 이질성보다 큰 것으로 나타나 다수준 분석에서 동 수준 지역 효과의 잠재력이있었다. (2) 다음으로 개인 수준에서는 한국종합사회조사 응답 중 가구소득 수준, 주관적 계층, 주관적 정치 성향, 타인에 대한 신뢰 등의 분산을 분석한 결과, 역시 모든 변수에 대해 동 간의 분산이 구 간의 분산보다 더 컸다. 이는 응답자의 태도 차이가 구 간의 지역 차이보다 동 간의 지역차이로 설명될 가능성이 높음을 암시한다. (3) 실제로 다수준 분석을 통해 이러한 태도 변수들에대해 응답자의 성별, 연령, 교육수준을 통제하고 지역 수준에서 평균 아파트 거래가격과 고령자인구 비율이 미치는 효과를 살펴본 결과, 구 수준보다는 동 수준에서 이러한 변수들의 효과가 더분명한 경향이 있었다. 예를 들어 고령자 인구 비율이 높은 동에 사는 응답자일수록 소득이 낮고자신의 주관적 계층을 낮게 평가하는 경향이 통계적으로 유의했으나, 구 수준에서는 이러한 경향이 발견되지 않았다. 마지막으로 서울시민을 대상으로 한 이러한 예시 분석을 바탕으로 다수준다출처 분석이 갖는 잠재력을 토의하였다.

특수교육대상 학생을 위한 미술활동 중재연구 동향 분석 : 국내 특수교육관련 학술지를 중심으로(2007년-2022년)

김이현,정진자,이예다나 인하대학교 교육연구소 2022 교육문화연구 Vol.28 No.5

본 연구의 목적은 특수교육대상 학생의 미술활동에 대한 중재연구의 동향을 분석하는데 있다. 이를 위하여 본연구에서는 2007년부터 2022년까지 특수교육대상 학생들을 대상으로 중재를 수행하고 국내학술지인용색인 등재지및 등재후보지에 게재된 미술활동 중재연구 논문 68편을 분석하였다. 본 연구의 결과는 다음과 같다. 첫째, 특수교육대상학생을 위한 미술활동 중재연구는 지적장애학생과 초등학생을 대상으로 한 연구가 많았다. 둘째, 연구 참여 대상자수는 단일대상연구의 경우는 대상자 3명, 집단비교연구는 10명-20명 미만이 많았다. 또한 연구 설계에 있어서 집단비교연구는 집단 간 비교연구, 단일대상연구는 중다기초선설계가 많았다. 셋째, 독립변인은 표현활동이, 종속변인은 사회성발달이 많은 비율을 차지하고 있었다. 넷째, 중재 효과는 집단 연구에서는 .05수준에서 유의미한 결과값을 제시하였으며, 단일대상연구에서도 대부분 90% 이상의 효과크기를 보임을 나타내고 있었다. 이상의 연구결과는 국내에서 이루어진특수교육대상 학생을 위한 미술활동 중재연구의 방향성 및 교육적 의의를 제시하고 후속 연구를 위한 시사점을제공하고 있다는데 의의를 지닌다.

고정상수로의 만곡부에서 교량으로 인한 배수위 변화량 산정.Ⅱ : 적용 Applications

김이현 경복대학 1999 京福論叢 Vol.3 No.-

일반적으로 많이 사용되고 있는 배수위 변화량 산정방법으로는 에너지 방정식, 운동량 평형방법, Yarnell 방정식, 그리고 FHWA WSPRO 방법 등과 본 연구에서 산정한 방법을 비교·분석해 보았다. 그리고 이 모형을 검증하기 위해 모형수로를 제작하여 실험을 수행하였다. 본 연구에서 구한 값은 5가지 해석방법 중 에너지 방정식으로 구한 값과 가장 근접하였다. 배수위 증가량은 운동량 평형방법으로 구한 값이 가장 크게 나타났고, 에너지 방정식, 본 연구방법 그리고 Yarnell 방정식 순서로 나타났다. 최대 배수위 발생지점은 이론치에서는 교각 설치 직상류 단면에서 발생하였으나, 실험에서는 3개단면 상류부근에서 발생하였다. 배수위가 교각 직하류부근에서 이론치는 변화가 없으나, 실험치에서는 급격히 하강하다가 하류방향으로 내려갈수록 정상 수위를 회복하였다. 실험수로에서의 흐름은 만곡부에 진입하기 직전 단면에서의 평균수위가 가장 높게 나타났으며, 각 유량에 대하여 교각을 단면 15에 설치되는 경우가 배수위 상승량이 가장 크고, 배수위 영향거리도 가장 길게 나타났다. 고정상수로의 만곡부에서 교량으로 인해 유수 단면적이 11% 이상 감소하는 경우에는 배수위가 급격히 상승한다는 것을 알 수 있었다. Backwater variation computation method used many in general are comparison and analysis energy equation, momentum balance method, Yarnell equation, and FHWA WSPRO method, computed method in this study. And for calibration this model performed a experiment make to model flume. Determined values in this study approached a good to energy equation from among 5 analysis method. Backwater increase appeared largest momentum balance method, the next appeared order energy equation, this study method, and Yarnell equation. Maximum backwater area occur section directly upstream of the pier in theory value, but upstream of 3 section in experimental value. Backwater no variated theory value section directly downstream of pier, but get back normal stage fall downstream rapid dropping at experimental values. Flow of experiment flume appeared highest normal stage directly before section inflow bend, for each discharge highest backwater case set up section 15, backwater influence distance appeared longest. Backwater known rapid increase case decreasing over 11% to flow area due to piers in bend of fixed bed channel.

Estimation of Corn Growth by Radar Scatterometer Data

김이현,홍석영,이경도,나상일,정건호 한국토양비료학회 2014 한국토양비료학회지 Vol.47 No.2

Ground-based polarimetric scatterometers have been effective tools to monitor the growth of crop withmulti-polarization and frequencies and various incident angles. An important advantage of these systems thatcan be exploited is temporal observation of a specific crop target. Polarimetric backscatter data at L-, C- andX-bands were acquired every 10 minutes. We analyzed the relationships between L-, C- and X-bandsignatures, biophysical measurements over the whole corn growth period. The Vertical transmit and Verticalreceive polarization (VV) backscattering coefficients for all bands were greater than those of the Horizontaltransmit and Horizontal receive polarization (HH) until early-July, and then thereafter HH-polarization wasgreater than VV-polarization or Horizontal transmit and Vertical receive polarization (HV) until theharvesting stage (Day Of Year, DOY 240). The results of correlation analysis between the backscatteringcoefficients for all bands and corn growth data showed that L-band HH-polarization (L-HH) was the mostsuited for monitoring the fresh weight (r=0.95***), dry weight (r=0.95***), leaf area index (r=0.86**), andvegetation water content (r=0.93***). Retrieval equations were developed for estimating corn growthparameters using L-HH. The results indicated that L-HH could be used for estimating the vegetationbiophysical parameters considered here with high accuracy. Those results can be useful in determiningfrequency and polarization of satellite Synthetic Aperture Radar stem and in designing a future ground-basedmicrowave system for a long-term monitoring of corn.

레이더 산란계 편파 차이율을 이용한 콩 생육 추정

김이현,홍석영 한국토양비료학회 2011 한국토양비료학회지 Vol.44 No.5

The soybean is one of the oldest cultivated crops in the world. Microwave remote sensing is an important tool because it can penetrate into cloud independent of weather and it can acquire day or night time data. Especially a ground-based polarimetric scatterometer has advantages of monitoring crop conditions continuously with full polarization and different frequencies. In this study, soybean growth parameters and soil moisture were estimated using polarimetric discrimination ratio (PDR) by radar scatterometer. A ground-based polarimetric scatterometer operating at multiple frequencies was used to continuously monitor the soybean growth condition and soil moisture change. It was set up to obtain data automatically every 10 minutes. The temporal trend of the PDR for all bands agreed with the soybean growth data such as fresh weight, Leaf Area Index, Vegetation Water Content, plant height; i.e., increased until about DOY 271 and decreased afterward. Soil moisture lowly related with PDR in all bands during whole growth stage. In contrast, PDR is relative correlated with soil moisture during below LAI 2. We also analyzed the relationship between the PDR of each band and growth data. It was found that L-band PDR is the most correlated with fresh weight (r=0.96), LAI (r=0.91), vegetation water content (r=0.94) and soil moisture (r=0.86). In addition, the relationship between C-, X-band PDR and growth data were moderately correlated (r≥0.83) with the exception of the soil moisture. Based on the analysis of the relation between the PDR at L, C, X-band and soybean growth parameters, we predicted the growth parameters and soil moisture using L-band PDR. Overall good agreement has been observed between retrieved growth data and observed growth data. Results from this study show that PDR appear effective to estimate soybean growth parameters and soil moisture.

Thermally Conductive Liquid Crystalline Network Based on Reactive Mesogens

김이현,임호선 한국고분자학회 2023 한국고분자학회 학술대회 연구논문 초록집 Vol.48 No.1

한국 밭토양 화학성 변동 평가

김이현,공명석,이은진,이태구,정구복 한국환경농학회 2019 한국환경농학회지 Vol.38 No.3

BACKGROUND: Monitoring of the dynamic changes of chemical properties in agricultural land is very important for agricultural sustainability. Chemical properties of agricultural soils in Korea have been investigated at four-year interval in the order of paddy, plastic film house, upland, and orchard soils since 1999. METHODS AND RESULTS: Total 8,160 topsoil samples were taken from the upland in 2001, 2005, 2009, 2013, and 2017, respectively. Soil chemical properties such as pH, electrical conductivity (EC), organic matter (OM), available phosphate (Avail. P2O5), and exchangeable (Exch.) cations (K, Ca, and Mg) were analyzed. Soil pH and Exch. Ca contents have increased since 2001. Average concentration of Avail. P2O5 increased from 547 mg kg-1 in 2001 to 657 mg kg-1 in 2017. Average concentration of Exch. Ca in 2017 was higher than the upper limit of its optimal range for upland cultivation. Excess and deficiency of chemical properties of upland soils comply with soil analysis and fertilizer prescription. CONCLUSION: We concluded that excessive nutrient in upland needed to be properly managed with soil test.