• 한국소음진동공학회논문집
• /
• 제18권7호
• /
• pp.725-731
• /
• 2008

This paper focused on the application of finite element model updating technique to evaluate the structural properties of the reinforced concrete specimen using the data collected from shaking table tests. The specimen was subjected to six El Centre (NS, 1942) ground motion histories with different peak ground acceleration (PGA) ranging from 0.06 g to 0.50 g. For model updating, flexural stiffness values of structural members (walls and slabs) were chosen as the updating parameters so that the converged results have direct physical interpretations. Initial values for finite element model were determined from the member dimensions and material properties. Frequency response functions (i.e. transfer functions), natural frequencies and mode shapes were obtained using the acceleration measurement at each floor and given ground acceleration history. The weighting factors were used to account for the relative confidence in different types of Inputs for updating (j.e. transfer function and natural frequencies) The constraints based on upper/lower bound of parameters and sensitivity-based constraints were implemented to the updating procedure in this study using standard bounded variable least-squares(BVLS) method. The veracity of the updated finite element model was investigated by comparing the predicted and measured responses. The results indicated that the updated model replicates the dynamic behavior of the specimens reasonably well. At each stage of shaking, severity of damage that results from cracking of the reinforced concrete member was quantified from the updated parameters (i.e. flexural stiffness values).

• Tuberculosis and Respiratory Diseases
• /
• 제71권5호
• /
• pp.322-327
• /
• 2011

Background: Pneumocystis jirovecii is a fungus that has become an important cause of opportunistic infections. We present a summary of the clinical status and findings from bronchoalveolar lavage (BAL) of patients with Pneumocystis jirovecii pneumonia (PJP). Methods: We selected 30 cases of PJP that were proven through a surgical specimen evaluation. BAL fluid cytology was reviewed, and agreement with the initial diagnosis was evaluated. Results: All 30 cases of PJP occurred in immunocompromised patients. Only 15 of the 30 cases were initially diagnosed as PJP. We found PJP in 13 of the 15 cases that were negative at the initial diagnosis. The most characteristic finding of PJP was frothy exudates, and BAL fluid tended to show rare neutrophils. Two of seven patients with PJP and diffuse alveolar damage (DAD) revealed no frothy exudates in BAL fluid. Conclusion: BAL fluid cytology was reconfirmed as a sensitive and rapid method to diagnose PJP. We must be aware of the possibility of PJP to maintain high diagnostic sensitivity. We cannot exclude PJP in cases of PJP with DAD, even if frothy exudates are not observed in the BAL fluid.

• 대한토목학회논문집
• /
• 제32권5B호
• /
• pp.313-320
• /
• 2012

본 논문에서는 폰툰형 콘크리트 부유구조체의 하부슬래브에 발생하는 인장력을 억제하여 구조적 안전성을 향상시킬 수 있는 방안으로 부유구조체 외측 모듈을 반잠수식 모듈로 구성하는 구조시스템을 제시하였다. 본 시스템의 적용성을 확인하기 위해 반잠수식 모듈 제원과 전체 시스템에 대한 반잠수식 모듈의 구성비를 변화시켜 외력에 대한 구조응답과 부유구조체 중량, 흘수를 종합적으로 검토하였다. 구조성능 검토 시 효율적인 매개변수 연구를 위해 이단계 등가 정적 해석법을 도입하였으며, 본 해석법을 바탕으로 시스템 제원 변화에 따른 각 구조부 작용 외력의 변화와 구조 거동을 분석하였다. 분석 결과, 본 시스템 도입 시 콘크리트 부유구조체의 하부슬래브 발생 인장력을 충분히 억제할 수 있는 것으로 나타났으며, 적정한 반잠수식 모듈의 구성비는 부유구조체 길이대비 약 15% 이하인 것으로 분석되었다.

• Nutrition Research and Practice
• /
• 제12권1호
• /
• pp.20-28
• /
• 2018

BACKGROUND/OBJECTIVES: Perilla frutescens (L.) Britton var. (PF) sprout is a plant of the labiate family. We have previously reported the protective effects of PF sprout extract on cytokine-induced ${\beta}-cell$ damage. However, the mechanism of action of the PF sprout extract in type 2 diabetes (T2DM) has not been investigated. The present study was designed to study the effects of PF sprout extract and signaling mechanisms in the T2DM mice model using C57BL/KsJ-db/db (db/db) mice. MATERIALS/METHODS: Male db/db mice were orally administered PF sprout extract (100, 300, and 1,000 mg/kg of body weight) or rosiglitazone (RGZ, positive drug, 1 mg/kg of body weight) for 4 weeks. Signaling mechanisms were analyzed using liver tissues and HepG2 cells. RESULTS: The PF sprout extract (300 and 1,000 mg/kg) significantly reduced the fasting blood glucose, serum insulin, triglyceride and total cholesterol levels in db/db mice. PF sprout extract also significantly improved glucose intolerance and insulin sensitivity, decreased hepatic gluconeogenic protein expression, and ameliorated histological alterations of the pancreas and liver. Levels of phosphorylated AMP-activated protein kinase (AMPK) protein expression also increased in the liver after treatment with the extract. In addition, an increase in the phosphorylation of AMPK and decrease in the phosphoenolpyruvate carboxykinase and glucose 6-phosphatase proteins in HepG2 cells were also observed. CONCLUSIONS: Our results sugges that PF sprout displays beneficial effects in the prevention and treatment of type 2 diabetes via modulation of the AMPK pathway and inhibition of gluconeogenesis in the liver.

• Composites Research
• /
• 제16권3호
• /
• pp.58-67
• /
• 2003

본 연구에서는 구조의 건전성을 실시간으로 모니터링하기 위해 변형률 및 파손을 동시에 감지할 수 있는 두 가지 형태의 광섬유 센서 시스템을 제안하였다. 구성된 광섬유 센서 시스템은 파손신호 취득에 사용되는 단파장 광원의 형태에 따라 EDFA에 FBG 사용한 것과 Fabry-Perot 필터를 사용한 것으로 나뉘며 EFPI센서를 통해 복합재 시편의 인장실험을 모니터링 하는데 적용되었다. 먼저, 복합재의 초기파손모드에 해당하는 모재균열 신호의 특징을 알기 위해 압전세라믹 센서를 이용하여 시편의 두께와 폭의 변화에 따른 신호특성을 파악하였다. 정량적 파손신호의 특성 분석을 위해 STFT와 Wavelet Transform과 같은 시간 주파수 변환방법을 사용하였으며, 시편의 형상변화에 따라 모재균열 신호의 주파수영역 특성이 변화함을 확인하였다 광섬유 센서로 취득 된 파손신호 및 변형률 측정값을 각각 압전세라믹 센서와 변형률게이지의 결과 값과 서로 비교하였다. 광섬유 센서 시스템들을 이용한 장시간동안의 인장실험 결과 변형률의 값은 변형률게이지의 측정값과 잘 일치하였으며 파손감지 시스템 또한 미세한 파손신호까지 민감하게 감지해 낼 수 있음을 알 수 있었다.

• 한국식품과학회지
• /
• 제45권3호
• /
• pp.370-375
• /
• 2013

구강구취균 4종을 국내산 프로폴리스를 이용하여 프로폴리스의 농도, 열처리, pH의 변화를 통한 항균효과를 조사하였다. P. gingivalis KCTC 5352가 다소 프로폴리스에 저항적인 모습을 보였으나 그 외의 구강구취균에는 강한 항균활성을 나타내었다. 액체배지를 이용하여 프로폴리스의 농도를 조절하여 구강구치균의 민감도를 조사한 결과, 프로폴리스의 농도가 진할 수록 더 빠른 시간에 큰 활성을 보였으며 일반적으로 $0.22mg/{\mu}L$ 농도의 프로폴리스를 첨가하였을 경우 4-6시간 안에 대부분의 균이 사멸하였다. TEM을 통해 프로폴리스가 균의 세포에 어떤 영향을 미치는가 살펴보았으며 프로폴리스를 첨가한 균의 세포막이 얇아지면서 붕괴되고 안의 내부물질이 유출되면서 세포가 분해됨을 확인하였다. $0.56mg/{\mu}L$ 농도의 프로폴리스를 사용하여 열처리 후와 pH 조절 후의 프로폴리스의 항균활성을 시험한 결과 열에 안정하지 않고, pH가 높아질수록 활성이 약해지는 것으로 나타났다.

• Molecules and Cells
• /
• 제39권2호
• /
• pp.129-135
• /
• 2016

Eukaryotic translation initiation factor 2 alpha ($eIF2{\alpha}$), which is a component of the eukaryotic translation initiation complex, functions in cell death and survival under various stress conditions. In this study, we investigated the roles of $eIF2{\alpha}$ phosphorylation in cell death using the breast cancer cell lines MCF-7 and MCF-7/ADR. MCF-7/ADR cells are MCF-7-driven cells that have acquired resistance to doxorubicin (ADR). Treatment of doxorubicin reduced the viability and induced apoptosis in both cell lines, although susceptibility to the drug was very different. Treatment with doxorubicin induced phosphorylation of $eIF2{\alpha}$ in MCF-7 cells but not in MCF-7/ADR cells. Basal expression levels of Growth Arrest and DNA Damage 34 (GADD34), a regulator of $eIF2{\alpha}$, were higher in MCF-7/ADR cells compared to MCF-7 cells. Indeed, treatment with salubrinal, an inhibitor of GADD34, resulted in the upregulation of $eIF2{\alpha}$ phosphorylation and enhanced doxorubicin-mediated apoptosis in MCF-7/ADR cells. However, MCF-7 cells did not show such synergic effects. These results suggest that dephosphorylation of $eIF2{\alpha}$ by GADD34 plays an important role in doxorubicin resistance in MCF-7/ADR cells.

• 한국도로학회논문집
• /
• 제19권2호
• /
• pp.127-135
• /
• 2017

PURPOSES: The objective of this study is to evaluate the effect of anti-stripping on asphalt mixtures constituting anti-stripping agents. METHODS : Based on the literature review, asphalt mixture added with anti-stripping agents was prepared, and these asphalt mixtures were evaluated for anti-stripping properties for each anti-stripping agent through various lab tests, namely, tensile strength ratio (TSR), dynamic immersion test, uniaxial compression test, and indirect tensile strength test (IDT). The liquid anti-stripping agents used in the lab test were premixed with each asphalt binder (PG 64-22, PG 76-22) before being mixed with the aggregate. RESULTS :The result of the TSR test revealed that the effect of anti-stripping was highest when hydrated lime and liquid anti-stripping agent W were added. The correlation coefficient $R^2$ between the TSR result and cohesion ratio is 0.99, which indicates that the sensitivity of the TSR to moisture damage is reliable from the mechanical point of view. The covering ratio of the asphalt binder to the liquid anti-stripping agent W was determined to be higher than that to the other liquid anti-stripping agents. CONCLUSIONS :It is considered that the improved moisture resistance of asphalt mixture as a result of the use of anti-stripping agents can reduce the incidence of various pavement damages such as portholes caused by stripping, and the performance life of the asphalt road pavement can be prolonged.

• Journal of Biosystems Engineering
• /
• 제42권4호
• /
• pp.330-338
• /
• 2017

Purpose: The smartphone is actively being used in many research fields, primarily in medical and diagnostic applications. However, there are cases in which smartphone-based systems have been developed for agriculture, environment, and food applications. The purpose of this review is to summarize the research cases using smartphone cameras in agriculture, environment, and food. Methods: This review introduces seventeen research cases which used smartphone cameras in agriculture, food, water, and soil applications. These were classified as systems involving "smartphone-camera-alone" and "smartphone camera with optical accessories". Results: Detecting food-borne pathogens, analyzing the quality of foods, monitoring water quality and safety, gathering information regarding plant growth or damage, identifying weeds, and measuring soil loss after rain were presented for the smartphone-camera-alone system. Measuring food and water quality and safety, phenotyping seeds, and soil classifications were presented for the smartphone camera with optical accessories. Conclusions: Smartphone cameras were applied in various areas for several purposes. The use of smartphone cameras has advantages regarding high-resolution imaging, manual or auto exposure and focus control, ease of use, portability, image storage, and most importantly, programmability. The studies discussed were achieved by sensitivity improvements of CCDs (charge-coupled devices) and CMOS (complementary metal-oxide-semiconductor) on smartphone cameras and improved computing power of the smartphone, respectively. A smartphone camera-based system can be used with ease, low cost, in near-real-time, and on-site. This review article presents the applications and potential of the smartphone and the smartphone camera used for various purposes in agriculture, environment, and food.

• 한국해안·해양공학회논문집
• /
• 제24권4호
• /
• pp.287-294
• /
• 2012

연안 해역은 해안구조물 건설과 간척 등의 연안 개발로 인해 해안의 퇴적환경이 크게 변화하고 있으며, 이로 인하여 많은 환경변화가 발생하였다. 특히 점착성 퇴적물은 오염물질을 흡착하고 이동하여 환경적으로 큰 변화를 야기한다. 목포해역은 최근에 많은 해안구조물의 건설로 인해 낙조우세가 점점 심해지는 등의 환경변화가 발생하고 있는 지역이다. 이 지역의 점착성 퇴적물을 채취하여 수리실험하고 얻은 침식률 및 침식한계전단응력의 퇴적물 이동모의 활용가능성에 대해 검토하였다. 부유사 농도에 대한 모의 결과는 관측자료와 일치하는 양호한 결과를 보였다. 따라서 수리실험을 통해 결정된 침식률을 사용하는 것이 수치모의에서 정확성을 개선하는 데 기여함을 확인할 수 있었다. 모의과정에서 침식률, 침식한계응력, 침강속도, 활성층 두께 등의 민감도를 분석하였다.