• 한국추진공학회지
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• 제7권2호
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• pp.1-6
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• 2003

액체 산소와 탄화수소계 연료를 사용하는 로켓에서 삼중 충돌형(FOF, OFO) 인젝터가 흔히 사용된다. 일반적으로 FOF 형태가 OFO에 비해 낮은 성능을 보인다는 것이 알려져 있지만, 벽면 열전달에 있어서 보다 효율적인 방식이다. 한편, 산화제와 연료 분사구 직경 차가 큰 FOF 형태에서 산화제 분사구가 분리된 분리 삼중 충돌형 FOOF 인젝터(이하 FOOF 인젝터)가 제안된 바 있다. 본 연구에서는 비반응 분무 실험을 통해 FOOF 인젝터의 분무 특성을 FOF와 비교하였다. PLLIF 기법을 이용하여 산화제와 연료의 질량 분포를 측정하였고, 순간사진을 이용하여 액적의 크기를 측정하였다. 실험결과를 통해 FOOF 형태의 인젝터가 FOF에 비해 보다 안정적인 혼합 효율을 나타내며 액적 크기는 두 형태의 인젝터가 큰 차이 없이 비슷한 경향을 보임을 알 수 있었다.

• Toxicological Research
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• 제28권3호
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• pp.159-164
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• 2012

Allergic skin inflammation such as atopic dermatitis (AD) is characterized by edema and infiltration with various inflammatory cells such as mast cells, basophils, eosinophils and T cells. Thymic stromal lymphopoietin (TSLP) is produced mainly by epidermal keratinocytes, as well as dermal fibroblasts and mast cells in the skin lesions of AD. Omega-3 polyunsaturated fatty acids in fish oil can reduce inflammation in allergic patients. Fermentation has a tremendous capacity to transform chemical structures. The antiinflammatory effects of fish oil have been described in many diseases, but the beneficial effects by which fermented olive flounder oil (FOF) modulates the allergic response is poorly understood. In this study, we produced FOF and tested its ability to suppress the various allergic inflammatory responses. The ability of FOF to modulate the immune system was investigated using a mouse model of AD. The FOF-treated group showed significantly decreased immunoglobulin E (IgE) and histamine in serum. Also, the increased TSLP expression was significantly inhibited in the FOF group; the FOF-treated group was not appreciably different from the hydrocort cream treatment group. In addition, FOF treatment resulted in a smaller spleen size with reduced the thickness and length compared to the induction group. Splenocytes from mice treated with FOF produced significantly less IFN-${\gamma}$, IL-4, T-box transcription factor (T-bet) and GATA binding protein 3 (GATA3) expression compared with the induction group. These results suggest that FOF may be effective in treating the allergic symptoms of AD. 5.

• 동서간호학연구지
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• 제28권2호
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• pp.122-131
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• 2022

Purpose: This study aimed to identify the factors related to fear of falling (FOF) in different age groups from community-dwelling mid to late-adults. Methods: To identify the factors related to FOF, data of 162,684 adults over 45 years of age from 2019 Community Health Survey was analyzed using logistic regression with complex samples. Results: Factors related to FOF found in all age groups were sex, previous experience of falls, physical activity levels over moderate intensity, subjective health status, number of chronic diseases, stress, depression, and cognitive decline. In the 45-64 age group, the FOF was significantly higher in the groups of low education level and low monthly household income. In the 65-74 and over 75 age groups, the FOF was significantly higher in the groups of not living with spouse and walking not practiced. Conclusion: We suggests that understanding of risk factors and early detection of fall risk patients in each age group are necessary to establish and apply tailored fall prevention programs for prevention and management of the FOF in community-dwelling mid to late-adults.

• 한국균학회지
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• 제47권3호
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• pp.219-232
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• 2019

Chemicals related to hydrogen peroxide ($H_2O_2$) and nitric oxide (NO) generations were exogenously applied to Fusarium oxysporum f. sp. fragariae (Fof) causing Fusarium wilt disease in strawberry plants, and regulations of in vitro conidial germination and mycelial growth of the fungus by the chemical treatments were evaluated. $H_2O_2$ drastically reduced the conidial germination of Fof in a dose-dependent manner, and treatment with 3-amino-1,2,4-triazole (3-AT) catalase inhibitor also led to dose-dependent inhibition of conidial germination but relatively moderately. Gradual decreases in mycelial growth of Fof were found by high concentrations of $H_2O_2$, whilst exogenous 3-AT slightly increased the mycelial growth. Increasing sodium nitroprusside (SNP) NO donor, $N^G$-nitro-l-arginine methyl ester (L-NAME) NO synthase (NOS)-inhibitor and tungstate nitrate reductase (NR) inhibitor led to dose-dependent reductions in conidial germination of Fof in quite different levels. SNP conversely increased the mycelial growth but increasing L-NAME moderately decreased the mycelial growth. Tungstate strongly enhanced mycelial growth. Differentially regulated in vitro mycelial growths of Fof were demonstrated by SNP, L-NAME and tungstate with or without $H_2O_2$ supplement. Superoxide anion production was also regulated during the mycelial growth of Fof by nitric oxide. These results show that $H_2O_2$ and NO-associated enzymes can be suggested as fungal growth regulators of Fof as well as eco-friendly disease-managing agents in strawberry production fields.

• 보건행정학회지
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• 제32권1호
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• pp.21-28
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• 2022

Background: To investigate the association between regular physical exercise and falling experience for 2 years and fear of falling (FOF) in Korean middle-aged and elderly population. Methods: Data from the Korean Longitudinal Study on Aging was used and 3,871 participants who exercised regularly were included at 2006 and follow-up until 2018. An analysis was performed to investigate the association between exercise (exercise time per week and duration) and falls (experience over past 2 years and FOF) using the generalized estimating equation model. Results: Compared to those who exercised more than 5 hours a week (reference group), those who exercised less than 3 hours were more likely to experience falls and FOF (odds ratio [OR], 1.334; 95% confidence interval [CI], 1.059-1.682; OR, 1.218; 95% CI, 1.119-1.326, respectively). Compared to the group who exercised for more than 5 years, those who exercised for less than 1 year were more likely to experience FOF (OR, 1.310; 95% CI, 1.162-1.478). Conclusion: This study showed that there was a negative relationship between physical exercise time and falling experience and FOF in Korean 45 years or more community-dwelling adults. Based on these results, physical activity can be expected to have a positive effect on fall prevention, which implies the need for policy and research on long-term physical activity programs.

• 식물병연구
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• 제26권2호
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• pp.79-87
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• 2020

Fusarium oxysporum f. sp. fragariae (Fof) 에 의한 딸기 시들음병은 국내 딸기재배에서 가장 중요한 병해 중 하나이다. 국내 발생하는 Fof의 특성을 분석하고자 시들음병균의 유전적 다양성, 병원성과 살균제 반응을 조사하였다. 분리균은 Fo080701를 제외한 모든 균주에서 Fof 특이적 primer에 증폭되었다. 분리균의 nuclear ribosomal intergenic spacer region과 EF-1α sequences 분석 결과 3개의 lineage를 형성하였다. 대부분의 분리균은 lineage 1에 속하였으며 lineage 3에 3개 균주와 lineage 2에 1개 균주가 포함되었다. 분리된 모든 균주는 설향품종에 병원성을 보였다. Prochloraz는 DNA lineage 2에 속하는 Fo080701균주를 제외하곤 시들음병균의 EC₅₀값이 0.02-0.1 ㎍/ml로 낮은 농도에서 효과적으로 균사 생장을 억제하였다. Metconazole의 EC₅₀값도 0.04-0.22 ㎍/ml로 prochloraz와 비슷한 억제 효과를 보였다. Pyraclostrobin의 EC₅₀값은 0.23-168.01 ㎍/ml로 균주에 따라 차이가 컸다. 딸기 재배포장에서 boscalid+fludioxonil, fluxapyroxad+pyraclostrobin, prochloraz manganese이 딸기 시들음병 방제에 효과적이었다.

• 한국추진공학회지
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• 제3권3호
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• pp.31-39
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• 1999

OFO, FOF 삼중 충돌형 및 FOOF 이중 분리 충돌형 분무연소장의 3차원 수치해석을 통한 연소성능 예측 및 성능설계 방법에 대하여 고찰하였다. 예조건화 압축성 유동 지배방정식과 저 레이놀즈수 $\kappa$-$\varepsilon$ 2 방정식 난류모델을 바탕으로 LU-SGS 기법을 사용하여 시간적분 하였으며 분무과정은 DSF 방법을 사용하여 모사하였다. n-heptane 액적과 공기를 연료와 산화제로 하는 액체 추진기관 내에서의 분무 연소장을 계산하였으며 연소에서의 난류의 영향은 eddy 소산모델을 사용하여 모사하였다. 분무연소장의 특성과 연소성능이 비교되었으며, 계산 결과 FOF 삼중 충돌형 분사기의 성능이 가장 우수한 반면, OFO 삼중 충돌형 분사기의 성능이 가장 저조한 것으로 나타났다. 연소효율에 중대한 영향을 미치는 파라미터로는 운동량비에 따른 초기 분무 액적의 평균직경과 혼합효율임을 확인하였다. 연소효율은 초기 분무 액적의 평균직경과 반비례, 혼합효율에 비례하여 증가되며, 산화제/연료 혼합비도 비례하여 상승하나, 일정 운동량비 이상에서는 감소되는 것으로 나타났다. 각 분사기 형태에서 운동량비에 따른 연소효율의 변화는 혼합효율의 변화와 동일한 경향을 보이며 그 크기는 분무 액적의 평균직경에 밀접한 관계가 있음을 알 수 있었다.

• Steel and Composite Structures
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• 제12권3호
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• pp.231-248
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• 2012

This research aims to investigate the structural behavior of concentrically braced frames after element loss by performing nonlinear static and dynamic analyses such as Time History Analysis (THA), Pushdown Analysis (PDA), Vertical Incremental Dynamic Analyses (VIDA) and Performance-Based Analysis (PBA). Such analyses are to assess the potential and capacity of this structural system for occurrence of progressive collapse. Besides, by determining the Failure Overload Factors (FOFs) and associated failure modes, it is possible to relate the results of various types of analysis in order to save the analysis time and effort. Analysis results showed that while VIDA and PBA according to FEMA 356 are mostly similar in detecting failure mode and FOFs, the Pushdown Overload Factors (PDOFs) differ from others at most to the rate of 23%. Furthermore, by sensitivity analysis it was observed that among the investigated structures, the eight-story frame had the most FOF. Finally, in this research the trend of FOF and the FOF to critical member capacity ratio for the plane split-X braced frames were introduced as a function of the number of frame stories.

• 유기물자원화
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• 제30권4호
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• pp.151-163
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• 2022

본 연구는 친환경 농산물 생산을 위한 양분관리 자재로 유기질비료 처리에 따른 옥수수 재배 토양의 비옥도 및 토양 호흡에 미치는 영향을 분석하였다. 시험장소는 국립농업과학원 유기농업과 시험포장에서 수행하였으며 처리구는 퇴비 (Com), 발효비료 (FOF), 혼합 유박 (PC), 무비구 (NF)로 처리구당 3반복 완전임의 배치하였다. 처리량은 174kg N/ha로 옥수수 표준시비량의 질소기준에 준하여 처리하였다. 옥수수 정식 8주 후 토양분석 결과, 퇴비는 토양의 탄소 (C)와 질소 (N)를 각각 7.48 및 0.76g/kg으로 증가시켰고, 다른 처리구는 시험 전과 차이가 없었다. 또한 시험 후 토양의 화학적 특성은 무비구를 제외하고 유의한 차이는 없었다. 토양 CO₂ 발생량은 발효비료 처리가 다른 처리구보다 31-76% 증가시켰으며 두 번의 제초작업 후 CH₄ 발생량의 차이는 없었다. 토양의 N₂O 배출량은 발효비료 처리가 다른 처리구보다 87-96% 감소되었다. 미생물 밀도 조사 결과, 시험 전에 비해 시험 후 토양의 사상균 및 방선균 밀도를 각각 25%, 16% 증가되었다. 따라서 친환경 농산물 생산을 위한 발효비료 등 유기질 비료는 자원을 순환하며 토양 생산성을 유지하는데 기여할 것이다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1998년도 추계 학술대회논문집
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• pp.211-219
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• 1998

Propellants pressurized and fed into the combustion chamber undergoes the mechanical, chemical combustion processes. Along with their distinctive physical characteristics, propellant combustion is typically divided into the processes; injection, atomization, mixing, vaporization and chemical reaction. These processes assumed to happen in a serial manner are strongly coupled, thereby involves formidable physical complexities. In this study a numerical experiment is attempted to simulate the burning sprays due to OFO, FOF triplet / FOOF split doublet injectors. Based on Eulerian-Lagrangian frame, Navier-Stokes equation system for compressible flows is preconditioned with low Reynolds number $k-{\varepsilon}$ turbulent model and time-integrated by LU-SGS, and the sprays are described by DSF model with the characteristics initialized by experimentally determined spray characteristics. Simplified single global reaction model approximates heptane-air reaction. It was observed that FOOF split doublet injector shows better atmization with shortest residence and the FOF triplet injector produces better combustion performance.