• 해양환경안전학회:학술대회논문집
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• 해양환경안전학회 2018년도 공동국제학술발표회
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• pp.132-132
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• 2018

• 한국안전학회지
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• 제15권4호
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• pp.35-40
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• 2000

The influence of cyclic loading history on the creep behavior of the 30 vol% hot-pressed $SiC_f/Si_3N_4copmposite was experimentally investigated at $1200^{\circ}C$. The duration of loading/unloading had great effects on the creep behaviors. The short term duration cyclic loading history test results showed significant reduction in the primary and steady-state creep rates. For example, 300sec loading/300sec unloading history resulted in 70% lower steady-state creep rate than that of the continuous loading. However the long term duration cyclic loading history test results showed little change in creep rates compared to those of the continuous one. The reason for the significant change in the short term duration cycles was estimated due to the change in the stress redistribution between the fiber and matrix during the creep recovery in the primary stage.

• 자원ㆍ환경경제연구
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• 제28권3호
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• pp.437-465
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• 2019

본 연구에서는 장기 전력 수요와 GDP 사이의 소득계수를 시간과 GDP의 값에 따라 변화하도록 모형화한 Chang et al.(2016)에 기반을 두어 장기 에너지 수요의 예측에 관련된 새로운 방법을 제안한다. 본 논문에서는 장기 에너지와 GDP 사이의 소득계수를 함수로 표현하고, 함수 주성분 분석(Functional Principal Component Analysis)을 통하여 함수계수(Functional Coefficient)를 예측하고 이를 장기 에너지 수요 예측에 적용한다. 또한 함수계수를 비모수적으로 추정할 때 너비띠 모수를 예측 실험 오차를 최소화하도록 설정하는 방식을 제안하였고 개별 국가의 함수계수 변화 패턴을 반영하여 개별 국가의 특수성을 반영하는 예측 방법도 제시한다. 실증분석에서는 전 세계 에너지 데이터를 이용하여 한국의 장기 에너지 수요 예측을 본 논문에서 제시한 방법으로 예측하고, 기존의 방법들 보다 안정적인 장기 에너지 수요 예측이 가능함을 보였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.2
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• pp.814-817
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• 2003

As additive Pt of a little to $SnO_2$ that gas sensing property is superior oxide-semiconductor material to fabricate gas sensor that operation is possible at room temperature and fabricated ceramic gas sensing devices. And, the change amount and sintering temperature of addition material investigated gas sensitivity by change of operation temperature, humidity relativity, Long-term stability and hysteresis. And achieved SEM and XRD analysis for characteristics searching examination of devices.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.214-215
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• 2007

Int this paper, we studied the analysis on long-term durability and output power characteristics of PV modules by variation on local thermal property. Using 5 modules(80W), we measured the maximum output power change during the test period. And the optical transmittance of glass was compared with PV module's maximum power fluctuation. The external environment change effected contamination on the entire or local surface of module. This caused the local temperature variation of each solar cell on PV module. The specific analysis is shown in the following paper.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2003년도 봄 학술발표회 논문집
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• pp.655-662
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• 2003

Slope stability is an important issue ill civil engineering works or in open pit mines where both economy and efficiency is required. These are the long-term stability problems which depend on the change of physical properties under a certain weather condition. These can also result in progress of weathering which can change mechanical or hydro-geological properties of rock mass considerably. In this study, weathering in nature was simulated by freeze-thaw test and Soxhlet test which represent mechanical and chemical weathering respectively. Measured were elastic wave velocities, absorption rate, volume change. Uniaxial compression strengths before and after the weathering tests were also measured. The change in weight and volume of the specimens were not clearly related to the weathering process, but P, S wave velocities were clearly decreased as weathering progresses. For some class of rocks, P-wave velocity was increased probably because of the saturation due to improved connectivity of the pre-existing pores. Based on the test results, stability of the slopes were analyzed using FLAC$\^$2D/. Due to the reduced strength parameters, the factors of safety were decreased for the selected sites.

• 한국조경학회지
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• 제35권3호
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• pp.105-113
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• 2007

This study was conducted to analyze the effects of environmental factors such as soil moisture, light intensity, temperature and humidity on changes in cambial electrical resistance. To improve data quality, cambial electrical resistance was continuously measured at fixed points by using a data logger isolated from alternating current. The relationship between environmental factors and changes in cambial electrical resistance was also analyzed. The results are as follows: 1. Cambial electrical resistance is highly correlated to the temperature of the measured area(r=-0.934). Therefore, temperature compensation is needed to analyze the effects of other environmental factors on cambial electrical resistance changes. 2. If temperature is compensated for, the change of cambial electrical resistance is highly correlated to water vapor pressure(r=-0.836). 3. If temperature and humidity are compensated for, the change of cambial electrical resistance is highly correlated to intensity of light(r=-0.738). 4. Diurnal deviation of soil water potential is not more significantly related than the change of cambial electrical resistance. However, in the long-term, soil water potential and cambial electrical resistance are highly correlated(r=-0.831). This indicates that soil moisture significantly influences the long-term change of cambial electrical resistance.

• 한국해안해양공학회지
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• 제16권1호
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• pp.10-17
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• 2004

지본 연구에서는 장기해안선변화를 조사, 해석함에 있어서 정사사진해석에 비해 비교적 손쉬운 affine 변환 해석방법을 이용하여 항공사진 자료를 분석하고, 정확도 평가를 수행하였다. 검토결과, 대상해안은 과거에 비해 해안선이 현저히 후퇴하여 침식되고 있음을 확인할 수 있었다. 또한, 정확도 평가 분석에서 나타난 RMS 오차는 1∼2m 미만의 오차에 불과하다는 것이 확인되었다. 항공사진측량작업내규에서 제시하는 최대허용오차범위가 2m인 점을 감안한다면, 본 연구에서 도출된 해안선변화 분석결과는 신뢰성이 높은 것이라 사료된다.

• 한국방재학회 논문집
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• 제8권1호
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• pp.103-108
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• 2008

Riverbed change is greatly influenced by artificial factors such as dam construction, gravel collection, and river improvement. This study simulated a long-term bed change based on the GSTARS3 model using actual data from the area downstream of the Geum River Daecheong Dam and compared the estimation with a section of the actual measurement. As a result, it was found that the section of the actual measurement was far lower than the result of the simulation in terms of long-term bed change. While the area downstream of Daecheong Dam displayed approximately an average of 2.29 m of streambed degradation on average while the upper stream area showed approximately 0.63 m of bed degradation over 24 years. In the simulation of the area downstream of Daecheong Dam based on the GSTARS3 model, similar bed degradation was observed. However, a great difference was detected between the result and the actual measurement. According to the cause analysis, the riverbed in the area downstream of Daecheong Dam has continuously degraded due to the dam construction and mass collection of gravel. The mass collection of gravel was the main cause of riverbed change. It was found that about 76% of all riverbed degradation was caused by the mass collection of gravel.

• 한국농공학회논문집
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• 제62권4호
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• pp.99-110
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• 2020

The objective of this study is to analyze the trend of changes in the water circulation rates under climate change by adopting the concept of WCR defined by the Ministry of Environment. With the need for sound water circulation recovery, the MOE proposed the idea of WCR as (1-direct flow/precipitation). The guideline for calculating WCR suggests the SCS method, which is only suitable for short term rainfall events. However, climate change, which affects WCR significantly, is a global phenomenon and happens gradually over a long period. Therefore, long-term trends in WCRs should also be considered when analyzing changes in WCR due to climate change. RCP (Representative Concentration Pathway) 4.5 and 8.5 scenarios were used to simulate future runoff. SWAT (Soil and Water Assessment Tool) was run under the future daily data from GCMs (General Circulation Models) after the calibration. In 2085s, monthly WCR decreased by 4.2-9.9% and 3.3-8.7% in April and October. However, the WCR in the winter increased as the precipitation during the winter decreased compared to the baseline. In the aspect of yearly WCR, the value showed a decrease in most GCMs in the mid-long future. In particular, in the case of the RCP 8.5 scenario, the WCR reduced 2-3 times rapidly than the RCP 4.5 scenario. The WCR of 2055s did not significantly differ from the 2025s, but the value declined by 0.6-2.8% at 2085s.