• 우주기술과 응용
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• 제1권3호
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• pp.356-363
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• 2021

중적외선을 이용하여 획득한 영상은 상온 부근의 온도 측정에는 적당하지 않다는 것이 교과서적 상식이었으나, 최근 중적외선 센서를 이용한 위성 영상을 살펴보면 중적외선 센서를 이용하여 측정한 결과물도 상온 부근의 온도를 측정할 수 있다는 가능성을 보여주고 있다. 본 논문에서는 중적외선 센서를 가지는 위성영상의 상온 온도 정보 추출 가능성 및 정확도에 대해 살펴보고자 한다. 논문에서 검토된 중적외선 위성영상은 상온 부분의 온도를 잘 표시하였으며, 측정된 온도의 절대값으로서의 신뢰성에 관해서는, 태양광의 지표면 직접 반사에 의한 열전달량 영향과 대기에서 흡수되는 적외선 대기 흡수량의 영향은 비교적 작거나 일정한 값으로 볼 수 있지만, 비접촉식 온도계의 한계인 물성치의 의한 복사 계수(emissivity)의 불확실성 문제는 여전히 해결해야할 문제로 남아 있게 되었다.

• 우주기술과 응용
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• 제1권2호
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• pp.149-159
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• 2021

본 논문은 2021년 5월에 수행된 국제우주쓰레기조정위원회(IADC, Inter-Agency Space Debris Coordination Committee Reentry) 재진입 테스트 캠페인의 분석 대상인 중국 창정 5B호 발사체의 재진입 시점 예측 분석 내용을 포함하고 있다. 우주물체의 재진입 예측은 물체의 크기나 무게, 자세에 대한 정확한 정보의 부재, 대기밀도의 불확실성 등으로 정확한 예측이 어렵다. 때문에 IADC에서는 재진입 캠페인을 매년 수행하여 기관별 분석기법에 대한 검증을 수행하고 있고, 한국항공우주연구원에서도 2015년부터 이에 참여하고 있다. 본 연구에서는 우주물체가 재진입하는 시점을 예측하기 위해 탄도계수 최적화 기법을 제안하였고, 이를 활용하여 분석 대상의 재진입 시점을 예측한 결과, 실제 재진입 시점과 약 73초의 차이를 보여주어 제안한 기법의 정확도를 확인하였다.

• Nuclear Engineering and Technology
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• 제54권7호
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• pp.2367-2375
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• 2022

In this work, we propose a new mechanistic model for the treatment of helium behaviour at the grain boundaries in oxide nuclear fuel. The model provides a rate-theory description of helium inter-granular behaviour, considering diffusion towards grain edges, trapping in lenticular bubbles, and thermal resolution. It is paired with a rate-theory description of helium intra-granular behaviour that includes diffusion towards grain boundaries, trapping in spherical bubbles, and thermal re-solution. The proposed model has been implemented in the meso-scale software designed for coupling with fuel performance codes SCIANTIX. It is validated against thermal desorption experiments performed on doped UO₂ samples annealed at different temperatures. The overall agreement of the new model with the experimental data is improved, both in terms of integral helium release and of the helium release rate. By considering the contribution of helium at the grain boundaries in the new model, it is possible to represent the kinetics of helium release rate at high temperature. Given the uncertainties involved in the initial conditions for the inter-granular part of the model and the uncertainties associated to some model parameters for which limited lower-length scale information is available, such as the helium diffusivity at the grain boundaries, the results are complemented by a dedicated uncertainty analysis. This assessment demonstrates that the initial conditions, chosen in a reasonable range, have limited impact on the results, and confirms that it is possible to achieve satisfying results using sound values for the uncertain physical parameters.

• 한국지하수토양환경학회지:지하수토양환경
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• 제27권spc호
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• pp.64-74
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• 2022

The conceptual site model (CSM) is used as a key tool to support decision making in risk based management of contaminated sites. In this work, CSM was applied in Jeonju Industrial Complex where site investigation for groundwater contamination was conducted. Site background information including facility types, physical conditions, contaminants spill history, receptor exposure, and ecological information were collected and cross-checked with tabulated checklist necessary for CSM application. The CSM for contaminants migration utilized DNAPL transport model and narrative CSMs were constructed for source to receptor pathway, ecological exposure route, and contaminants fate and transport in the form of a diagram or flowchart. The component and uncertainty of preliminary CSM were reviewed using the data gap analysis while taking into account the purpose of the survey and the site management stage at the time of the survey. Through this approach, the potential utility of CSM was demonstrated in the site management process, such as assessing site conditions and planning follow-up survey work.

• Steel and Composite Structures
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• 제41권6호
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• pp.831-850
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• 2021

Surface subsidence caused by mining subsidence has an impact on neighboring structures and utilities. In other words, subsurface voids created by mining or tunneling activities induce soil movement, exposing buildings to physical and/or functional destruction. Soil-structure is evaluated employing probability distribution laws to account for their uncertainty and complexity to estimate structural vulnerability. In this study, to investigate the displacement field and surface settlement profile caused by mining subsidence, on the basis of a Winklersoil model, analytical equations for the moment-rotation response ofsoil during mining induced ground movements are developed. To define the full static moment-rotation response, an equation for the uplift-yield state is constructed and integrated with equations for the uplift- and yield-only conditions. The constructed model's findings reveal that the inverse of the factor of safety (x) has a considerable influence on the moment-rotation curve. The maximal moment-rotation response of the footing is defined by X = 0:6. Despite the use of Winkler model, the computed moment-rotation response results derived from the literature were analyzed through the ELM-SVM hybrid of Extreme Learning Machine (ELM) and Support Vector Machine (SVM). Also, Monte Carlo simulations are used to apply continuous random parameters to assess the transmission of ground motions to structures. Following the findings of RMSE and R2, the results show that the choice of probabilistic laws of input parameters has a substantial impact on the outcome of analysis performed.

• 한국환경과학회지
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• 제32권8호
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• pp.595-611
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• 2023

The purpose of this study is to improve the daily prediction results of PM2.5 from the air quality diagnosis and evaluation system operated by the Busan Institute of Health and Environment in real time. The air quality diagnosis and evaluation system is based on the photochemical numerical model, CMAQ (Community multiscale air quality modeling system), and includes a 3-day forecast at the end of the model's calculation. The photochemical numerical model basically has limitations because of the uncertainty of input data and simplification of physical and chemical processes. To overcome these limitations, this study applied DNN (Deep Neural Network), a deep learning technique, to the results of the numerical model. As a result of applying DNN, the r of the model was significantly improved. The r value for GFS (Global forecast system) and UM (Unified model) increased from 0.77 to 0.87 and 0.70 to 0.83, respectively. The RMSE (Root mean square error), which indicates the model's error rate, was also significantly improved (GFS: 5.01 to 6.52 ug/m³ , UM: 5.76 to 7.44 ug/m³ ). The prediction results for each concentration grade performed in the field also improved significantly (GFS: 74.4 to 80.1%, UM: 70.0 to 77.9%). In particular, it was confirmed that the improvement effect at the high concentration grade was excellent.

• 여성건강간호학회지
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• 제29권1호
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• pp.44-54
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• 2023

Purpose: Uncertainty and restrictions on daily life have increased fear, stress, and depression during the coronavirus disease 2019 (COVID-19) pandemic. Depression is the most common mental health problem in pregnant women. The purpose of this study was to evaluate the levels of fear and stress related to COVID-19 experienced by pregnant women, as well as their levels of depression, and to examine the factors associated with depression during pregnancy. Methods: This was a cross-sectional, correlational study conducted among 153 pregnant women who visited a maternity hospital in Busan, South Korea. A self-reported questionnaire was used for data collection from December 18, 2021 to March 8, 2022. Data were analyzed using descriptive statistics, the independent t-test, one-way analysis of variance, Pearson correlation coefficients, and multiple regression. Results: Pregnant women experienced a moderate level of fear related to COVID-19, with an average score of 21.55±4.90. The average score for depression during pregnancy was 14.86±11.10, with 50.3% of the participants experiencing depression (≥13). The factors associated with depression during pregnancy were fear of COVID-19, contact with a confirmed case of COVID-19, being in the third trimester of pregnancy, high stress levels due to difficulties experienced from social distancing measures, and unintended pregnancy. These five statistically significant factors explained 35.0% of variance in depression during pregnancy. Conclusion: Considering the prevalence of depression in pregnant women during the COVID-19 pandemic, it is necessary to develop interventions to reduce anxiety by providing correct information and alleviating the stress of social distancing.

• 한국지반공학회논문집
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• 제24권1호
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• pp.119-130
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• 2008

얕은기초 설계시 이용되는 지반의 물리적 공학적 설계변수들은 고유변동성(inherent variability) 및 측정 오차(measurement error) 등과 같은 여러 가지 요인으로 인하여 불확실성이 필연적으로 내포되어 있다. 본 논문에서는 얕은기초 설계시 기존의 결정론적 방법에서 고려하지 못하는 지반 불확실성 등을 포함한 설계 파라미터의 분산을 고려할 수 있는 확률론적 방법의 신뢰성 설계 사례를 제시하였다. 극한지지력 산정시 확률변수(random variable)인 단위중량, 점착력 및 내부마찰각 그리고 침하량 산정시 탄성계수에 대하여 국내 지반에 대한 적정 확률분포 형태 및 통계적 특성치를 결정하였다. 각 확률변수별로 채택된 분포를 적용하여 지지력과 침하량에 관한 신뢰지수와 파괴확률을 결정하였으며, 목표 신뢰지수 또는 확률에 대한 기초폭을 결정하였다. 얕은기초의 신뢰성 설계에 있어서 정규분포의 일괄적 적용보다는 각 확률변수에 해당하는 적합한 분포형태를 적용, 분석하는 것이 바람직한 것으로 나타났다.

• 천문학회보
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• 제46권1호
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• pp.60.1-60.1
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• 2021

The Balloon-borne Investigation of Temperature and Speed of Electrons in the corona (BITSE) is a technology demonstration mission launched in 2019 to observe the solar corona from ~3 Rs to 15 Rs at four wavelengths (393.5, 405.0, 398.7, and 423.4 nm). Preliminary analysis shows that BITSE imaged the solar minimum corona with the equatorial streamers on the east and west limbs. The narrow streamers observed by BITSE are in good agreement with the geometric properties obtained by the Solar and Heliospheric Observatory (SOHO) coronagraphs in the overlapping physical domain. In spite of the small signal-to-noise ratio we were able to obtain the temperature and flow speed of the western steamer. In the heliocentric distance range 4 - 7 Rs on the western streamer, we obtained a temperature of ~ 1.0 ± 0.3 MK and a flow speed of ~ 260 km s^-1 with a large uncertainty interval.

• 분석과학
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• 제22권4호
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• pp.302-306
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• 2009

철강 중의 미량 붕소는 소재의 기계적, 물리적 특성에 중요한 영향을 준다. 즉발감마선 방사화 분석법에 의해 저합금강 시료 중의 미량 붕소를 측정하였다. 시료는 한국표준과학연구원에서 제조한 저합금강 표준물질KRISS 101-01-C21~C26을 이용하였으며, 측정방법의 유효성 확인을 위해 NIST SRM 362, 364, 1761, 1762를 정확도관리용 시료로 사용하였다. NIST SRM 362를 제외하고는 측정 농도가 인증값의 불확도 범위내에서 잘 일치하였다. 불확도는 ISO guideline에 따라 평가하였으며, 포함인자 2를 적용하여 확장불확도를 산출하였다. 붕소 농도 mg/kg수준에서 상대확장불확도는 3%에서 7% 사이였다. 그 결과를 용매추출-유도결합플라스마 방출분광분석결과와 비교하여 제시하였다.