• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.139-139
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• 2021

Flooding events often result from extreme precipitations driven by various climate mechanisms, which are often disregarded in flood risk assessments. To bridge this gap, we propose a climate-mechanism-based flood frequency analysis that accommodates the direct linkage between the dominant climate processes and risk management decisions. Several statistical methods have been utilized in this approach including the Markov Chain analysis, K-nearest neighbor (KNN) resampling approach, and Z-score-based jittering method. After that, the impacts of climate change are associated with the modification of the transition matrix (TM) and the application of the quantile mapping approach. For this study, we have selected the Nam River Basin, South Korea, to consider the heterogeneous impacts of the two climate mechanisms, including the Tropical Cyclone (TC) and non-TCs. Based on our results, while both climate mechanisms have significant impacts on future flood extremes, TCs have been observed to bring more significant and immediate impacts on the flood extremes. The results in this study have proven that the proposed approach can lead to a new insights into future flooding management.

• Journal of Microbiology and Biotechnology
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• 제34권4호
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• pp.828-837
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• 2024

Vancomycin (VAN) and metronidazole (MTR) remain the current drugs of choice for the treatment of non-severe Clostridioides difficile infection (CDI); however, while their co-administration has appeared in clinical treatment, the efficacy varies greatly and the mechanism is unknown. In this study, a CDI mouse model was constructed to evaluate the therapeutic effects of VAN and MTR alone or in combination. For a perspective on the intestinal ecology, 16S rRNA amplicon sequencing and non-targeted metabolomics techniques were used to investigate changes in the fecal microbiota and metabolome of mice under the co-administration treatment. As a result, the survival rate of mice under co-administration was not dramatically different compared to that of single antibiotics, and the former caused intestinal tissue hyperplasia and edema. Co-administration also significantly enhanced the activity of amino acid metabolic pathways represented by phenylalanine, arginine, proline, and histidine, decreased the level of deoxycholic acid (DCA), and downregulated the abundance of beneficial microbes, such as Bifidobacterium and Akkermansia. VAN plays a dominant role in microbiota regulation in co-administration. In addition, co-administration reduced or increased the relative abundance of antibiotic-sensitive bacteria, including beneficial and harmful microbes, without a difference. Taken together, there are some risks associated with the co-administration of VAN and MTR, and this combination mode should be used with caution in CDI treatment.

• Nuclear Engineering and Technology
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• 제56권8호
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• pp.3097-3111
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• 2024

Since the level 2 PSA of OPR-1000 was the requirement for regulatory purposes, Cs-137 release estimation was contained as the Nuclear Safety Act of ROK in which the Cs-137 release frequency exceeding 100 TBq was determined to happen less than 1.0E-6 per year after the Fukushima Daiichi Accident. However, Cs-137 release estimation from the conventional level 2 PSA of OPR-1000 provided uncertainty due to dominant accident sequence consideration. Thus, this study aimed to develop systematic methods through the overall framework to quantify realistic uncertainty concerns of radioactive material release using sensitivity and uncertainty analysis methods and apply them to OPR-1000. This framework helped to quantify confidential value for the Cs-137 release under the BEPU approach using both parametric and non-parametric methods to cover both realistic and conservative points. Uncertainty propagation analysis showed the unexpected uncertainty increase of Cs-137 release exceeding 100 TBq. The non-parametric uncertainty analysis provided higher conservative concerns for safety than the realistic concerns in terms of economics when compared with the parametric uncertainty analysis. Wilks' uncertainty analysis showed the importance to consider conservative Cs-137 release in order to reach the higher safety need. Sensitivity analysis showed reasonable relationships between engineering safety parameters with the Cs-137 release.

• 한국치위생학회지
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• 제7권1호
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• pp.91-103
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• 2007

The purpose of this study was to pave the way for the development of oral health promotion programs for children from the low-income class. The subjects in this study were 322 children from the city of Incheon. Some of them visited local childcare centers, and the others attended six different adjacent elementary schools. Their awareness of oral health, oral health behavior and preventive-treatment experience were investigated in May 2005, and whether there were any characteristics in their visit of dental institutions was checked. Besides, whether their parents advised them to brush their teeth before turning in was examined. The findings of the study were as follows: 1. 22.0 percent of the children investigated were visiting local childcare centers, and 78.0 percent weren't. The guardians of the former group largely received high-school(50.7%) and middle-school or lower education(22.5%), and those of the latter group mostly received high-school(41.0%) and college- or higher education(35.5%)(pE0.001). The common monthly mean house-hold income of the former was one million won or less(54.9%) or ranged from 1.01 to 2.00 million won(19.7%), and the most prevalent monthly mean household income of the latter was between 2.01 and 3.50 million won(28.7%). The second most dominant monthly mean household income of the latter ranged from 1.01 to 2.00 million won(28.3%), and the third most common one was 3.50 million won or more(12.0%)(pE0.001). 2. The most prevalent daily toothbrushing frequency among the local childcare center visitors was twice(39.4%), followed by three times(19.7%). The third largest group of the visitors brushed their teeth after each meal(19.7%). The most dominant daily toothbrushing frequency among the non-users of local child care centers was twice(54.2%), followed by three times(29.1%)(pE0.01). As to the way of toothbrushing, 58.2 percent of the visitors and 74.9 percent of the non-visitors brushed their teeth by turning their toothbrush or up and down(pF0.05). 62.0 percent of the former and 74.9 percent of the latter always brushed their teeth before turning in, and whether they visited local childcare centers made a significant difference to that(pE0.05). 3. 69.7 percent of the non-visitors were always advised by their parents to do toothbrushing before turning in, and the visitors who were given the same advice all the time numbered 29.6 percent(pE0.001). 4. 56.4 percent of the visitors and 72.1 percent of the non-visitors had ever visited dental institutions over the past year. Dental hospitals and clinics were identified as the dental institutions that they visited the most, and they mostly received dental-caries treatment or had a tooth out there. 49.3 percent of the visitors and 35.1 percent of the non-visitors had ever had a toothache. 5. Sealant was experienced by 42.3 percent of the visitors and 46.2 percent of the non-visitors to prevent dental caries(pF0.05). 33.8 percent of the visitors underwent fluoride application, and that rate was higher than that of the non-visitors with the same experience that stood at 22.7 percent(pE0.05). The visitors mainly acquired knowledge on oral health through other channels that weren't specified in the questionnaire(28.2%), and the non-visitors did it mostly at dental clinics(39.0%)(pE0.001).

• 환경생물
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• 제36권2호
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• pp.107-116
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• 2018

이 연구는 거머리말(Zostera marina)의 서식지와 비서식지에서 퇴적환경과 대형저서동물의 분포양상을 파악하는 것을 목적으로 조사를 수행하였다. 영흥도에 서식하는 거머리말은 1월과 4월 사이에 성장을 시작하며, 7월에 급성장을 보이고 11월부터 입과 마디 탈락이 시작되고 나서 겨울에는 성장을 멈추는 것으로 판단되었다. 퇴적환경은 서식지에서 Sand와 같은 조립질 퇴적물이 우세하고, Sand와 Mud가 혼합된 퇴적 양상이 강하게 나타났으며, 비서식지에서는 Slit와 같이 세립질 퇴적물이 우세하였으며, 계절적 변화는 뚜렷하지 않았다. 그 결과로 거머리말의 서식지가 비서식지와 상이한 입도조성 및 유기물함량을 보이며, 이에 따라 대형저서동물의 종조성에도 영향을 미친 것으로 판단되었다. 대형저서동물군집은 서식지에서 비서식지에 비하여 높은 출현종수와 서식밀도를 가지는 것으로 나타났으며, 이 종조성에 기초한 생태학적제지수의 평가결과, 군집의 안정성을 나타내는 지수들이 서식지에서 높은 수치를 보였다. 특히 종풍부도지수(J)의 경우는 2배 정도의 차이를 보일 정도로 큰 차이를 나타내며, 군집의 안정성에서 거머리말 서식지가 더욱 높은 것으로 파악되었다. 집괴분석(Cluster analysis)을 수행한 결과 Similarity 50에서 2개의 정점군으로 구분할 수 있었으며, 2개의 정점군은 거머리말의 서식지와 비서식지로 구분되어 나타났다.

• 디지털융복합연구
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• 제13권7호
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• pp.33-45
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• 2015

우리나라 여성들의 노동시장 참여는 계속 증가해 왔지만, 이 증가를 이끈 주된 고용 형태는 정규직이 아니라 비정규직이었다. 남성 배우자의 임금이 불안정해지거나 혹은 일자리를 잃게 되면 특히 저학력 저소득층의 40대 이상 여성들은 가족의 생계를 전담하거나 보조하기 위해 노동시장으로 나오지만, 우리 사회는 이들을 노동시장의 가장 하위 집단으로 취급하면서 비정규직으로 채용하는 것을 당연시한다. 여성 비정규직 속에는 20대 아르바이트생, 고학력 전문직 계약직 여성들, 학습지 교사와 같은 특수고용형태 노동자, 고령의 저학력 판매 서비스직 여성들도 포함되어 있다. 이런 배경에서 본 논문은 우리나라 비정규직 여성 중 가장 취약 집단이자 대표 집단은 누구인지 규명하는 데 일차 목적이 있으며, 아울러 그들을 위한 소득보장 제도로는 무엇이 합당할지 검토하는데 이차 목적이 있다. 문헌분석과 통계수치 분석을 연구방법으로, 본 연구는 우리나라 여성 비정규직의 중에서, 40대 이상, 저학력, 저소득이면서, 남성배우자가 부재하거나 남성 소득에만 의지할 수 없는, 판매직 서비스직 단순노무직 여성들일수록 상대적으로 더욱 비정규직으로 취업한다는 결과를 제시한다. 따라서 그들을 위한 소득보장 제도는 정규직 위주, 남성 위주의 고용보험 제도의 개선보다는 실업부조의 도입이 더 현실적이고 시급함을 주장하고자 한다.

• 자원환경지질
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• 제35권6호
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• pp.491-508
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• 2002

화산 쇄설물을 모재로 하여 발달한 제주도 토양은 많은 양의 비정질 물질을 포함하는 Andisols이 대부분을 차지하고 있으나, 강수량이 상대적으로 적은 제주도 서부 지역에서는 Andisols의 특징을 보이지 않는 토양이 발달하고 있다. 서부 해안에 접해 있는 당산봉에는 이와 같이 층상규산염광물이 우세한 non-Andic토양이 나타난다 본 연구는 당산봉 토양에 나타나는 층상 규산염 광물의 조성 및 풍화에 따른 이들 점토광물의 진화 과정을 밝히는데 그 목적이 있다. 연구 지역 토양은 A층과 C층이 발달해 있으며 B층은 나타나지 않는다. pH(($H_{2}0$)는 일반적인 화산 쇄설물 기원 토양(<6.0)보다 높은 6.6-7.3으로 하부로 갈수록 증가한다. pH(NaF)는 9.49-9.81로 비정질 물질의 존재를 지시하는 9.4보다 높게 나타나며, 선택적 용해법을 이용하여 구한 비정질 물질의 양은 0.55-1.02 wt%로 매우 낮다. 유기물 함량은 표토에서 2.00wt%로 Andisol에 비해 매우 낮다. 주 구성 광물은 석영, 장석, 감람석이며, 점토 입도를 구성하는 층상규산염 광물은 입도와 풍화정도에 따라 차이를 보인다. <0.2$\mu\textrm{m}$ 입도의 주 구성 점토 광물은 스멕타이트, 카올리나이트/스멕타이트 혼합층광물, 일라이트이다. 카올리나이트/스리타이트 혼합층광물의 카올리나이트의 비율은 85-86%로 깊이에 관계없이 일정하다. 풍화가 진행될수록 스멕타이트의 함량은 감소하며, 카올리나이트/스멕타이트 혼합층광물의 함량은 증가한다. 2-0.2$\mu\textrm{m}$ 입도의 주 구성 점토 광물은 질석, 스멕타이트, 일라이트, 카올리나이트, 녹니석이다. 녹니석은 표토에서만 나타나며, 하부에서는 나타나지 않는다. 녹니석/스멕타이트 혼합층광물 내의 녹니석 함량은 59-70%이며 풍화가 진행될수록 양은 증가한다. 그러나 풍화의 정도가 낮은 제일 하부에서는 녹니석/스멕타이드 혼합층광물이 나타나지 않는다. 질석과 스멕타이트의 일부는 층간이 hydroxy-Al/Mg/Fe으로 채워진 hydroxy-interlayered vermiculite(HIV)와 hydroxy-interlayered smectite(HIS)의 형태로 나타난다. HIV는 A층과 C층 모두에서 나타나며, 층간 물질은 hydroxy-Fe/Al이다. 층간의 hydroxy-Fe/Al의 양은 표토로 갈수록 증가하며, HIV를 형성하는 질석의 층 전하도 표토에서 높게 나타난다. HIS는 C층에서만 나타나며, 층간 물질은 hydroxy-Mg/Al이며, hydroxy-Mg가 우세하다. 본 지역의 토양에서는 풍화가 진행될수록 스멕타이트는 카올리나이트와 질석, HIS로 진화하였으며, 질석은 HIV를 거쳐 녹니석으로 진화하였을 것으로 사료된다.

• 한국기계가공학회지
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• 제19권6호
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• pp.55-60
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• 2020

The injection molding technique is a processing method widely used for the production of plastic parts. In this study, the gate position, gate size, packing time, and melt temperature were optimized to minimize both the stress and deformation that occur during the injection molding process of medical suction device components. We used a central composite design and Latin hypercube sampling to acquire the data and adopted the response surface method as an approximation method. The efficiency of the optimization of the injection molding problem was determined by comparing the results of a genetic algorithm, sequential quadratic programming, and a non-dominant classification genetic algorithm.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.1-4
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• 2001

A new non-destructive fatigue prediction model of the composite laminates is developed. The natural frequencies of fatigue-damaged laminates under extensional loading are related to the fatigue lift of the laminates by establishing the equivalent flexural stiffness reduction as a function of the elastic properties of sublaminates. The flexural stiffness is derived by relating the $90^{\circ}$-ply elastic modulus reduction, and using the laminate plate theory to the degraded elastic modulus and the intact elastic modulus of other laminate. The natural frequency reduction model, in which the dominant fatigue mode can be identified from the sensitivity scale factors of sublaminate elastic properties, provides natural frequency vs. fatigue cycle curves for the composite laminates. Vibration tests were also conducted on $[\textrm{90}_{2}\textrm{0}_{2}]_s$ carbon/epoxy laminates to verify the natural frequency reduction model. Correlations between the predictions of the model and experimental results are good.

• 설비공학논문집
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• 제12권4호
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• pp.388-397
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• 2000

Comparison of the heat conduction into a trapezoidal fin and the heat loss from the fin by convection is made in this study Also, the ratio of heat loss from each surface to the total heat loss and the temperature distribution are analyzed using a 3-D analytical method. A trapezoidal fin whose tip height is half the root height is chosen as the model. The results show that the heat transfer rates from the tip and from both sides are comparable with each other as the non-dimensional width and length vary while the heat transfer rate from the bottom and top is dominant.