• Tribology and Lubricants
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• 제36권3호
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• pp.147-152
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• 2020

This paper is within the framework of an adhered complete contact problem wherein the contact between a half plane and sharp edged indenter, both of which are elastic in character, is constituted. The eigensolutions of the contact shear and normal stresses, σ_rq and σ_q, respectively, are evaluated via asymptotic analysis. The ratio of σ_rq/σ_qq is investigated and compared with the coefficient of friction, μ, of the contact surface to observe the propensity to slip on the contact surface. Interestingly, there exists a region of |σ_rθ/σ_θθ| ≥ |μ|. Thus, slipping can occur, although the problem is solved under the condition of an adhered contact without slipping. Given that a tribological failure potentially occurs at the slipping region, it is important to determine the size of the slipping region. This aspect is also factored in the paper. A simple example of the adhered contact between two elastically dissimilar squares is considered. Finite element analysis is used to evaluate generalized stress intensity factors. Furthermore, it is repeatedly observed that slipping occurs on the contact surface although the size of it is extremely small compared with that of the contacting squares. Therefore, as a contribution to the field of contact mechanics, this problem must be further explained logically.

• Asian Pacific Journal of Cancer Prevention
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• 제13권8호
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• pp.3669-3673
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• 2012

A role for the xenotropic murine leukemia virus (XMRV) in prostate cancer development has been postulated. To answer questions regarding the prevalence of XMRV in Iranian patients with prostate cancer and its association with the RNASEL R462Q polymorphism, we here investigated a series of cases in Kerman, in the Southeast of Iran, and sought to verify the association with the R462Q using Real Time PCR Method. Prostate tissue specimens of 200 patients with prostate cancer were genotyped for R462Q by real time polymerase chain reaction allelic discrimination and were screened for XMRV proviral DNA by real time polymerase chain reaction specific for the envelope gene. Of 200 patients in this study 8 (4%) cases were positive for XMRV, the QQ allele being the most frequenct regarding the R426Q polymorphism while in negative patients it was the RQ allele. There was significant correlation between high pathological scores and XMRV positive samples. No significant relationship was found between age groups and XMRV results. XMRV was only found in patients with QQ and RQ alleles, not RR. XMRV is detectable in tumor prostate tissue from some patients with prostate cancer, independent of R462Q.

• Tuberculosis and Respiratory Diseases
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• 제44권2호
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• pp.309-320
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• 1997

연구배경 : 혈중 유산농도를 측정함으로써 결정되는 무산소역치(유산역치)는 관혈적이라는 제한점이 있어, 운동부하시 유산증가에 수반되는 환기적부하에 반응하는 여러환기지표에서 비관혈적으로 무산소역치 (환기성역치)를 측정하는 방법들이 제시되어 있고, 이들에는 환기 당량법, 종말호기 산소분압법, V-경사법, 호흡지수법 등이 알려져 있다. 무산소역치를 반영하는 환기성 역치의 타당도에 관하여 논란이 없는 것은 아니지만, 일관성있는 방법적 신뢰도가 유효하다면 운동능력 평가에 있어서 환기성역치의 유용성이 인정된다는 일반적인 의견이다. 그러나 이미 환기장애가 초래되어 있는 만성기도폐쇄를 보이는 환자에서는 운동증가에 따르는 유산증가에 대처하는 환기반응이 적절하지 못하므로 환기성역치가 무산소역치를 반영하지 못한다는 지적이 었다. 만성기포폐쇄를 보이는 환자에서 상기한 네가지 환기성역치 측정방법들의 역치검출율과 신뢰도를 확인하기 위하여 본 연구를 시행하였다. 방 법 : 12명의 정상대조군과 17명의 만성기도폐쇄 환자군을 대상으로 증상제한적 최대운동부하검사(정상군 : 25 W/min, 만성기도폐쇄군 10 W/min)를 실시한 후 환기당량법, 종말호기산소분압법, V-경사법, 호흡지수법 등에 의해 환기성역치를 구한 후 상관계수를 구하여 유의성을 검증하였다. 결 과 : 각 환기성역치 측정방법에 의한 역치 검출율은 정상대조군에서 호흡지수법이 100%, 환기당량법과 종말호기 산소분압법이 91.7%로 같은 빈도를 보였고, V-경사법은 83.3%의 빈도를 보여 점반적으로 비교적 높은 빈도의 검출율을 보인 반면, 만성기도폐쇄군에서 호흡지수법이 94.1%로 가장 높았으나 환기당량법과 종말호기 산소분압법이 64.7%의 같은 검출빈도로 정상대조군에 비해 현저히 감소되었고, V-경사법은 83.3%로 정상대조군과 검출율에 있으서 같은 빈도를 보였다. 각 환기성역치 측정방법들의 유의성을 검증한 결과 정상대조군에서는 호흡지수법을 제외한 환기당량법과 종말호기 산소분압법, 그리고 V-경사법 등간에 모두 유의한 상관관계를 보인 반면 만성기도폐쇄군애서는 환기당량법과 종말호기 산소분압법사이에서만 상관계수가 0.9860으로 정상대조군에서처럼 매우 높은 일치도를 보였고 나머지 방법들간에는 그 어느 조합도 유의한 상관관계를 확인할 수 없었다. 결 론 : 호흡지수법은 매우 예민하지만 신뢰성이 떨어지는 방법이고, 환기당량법과 종말호기 산소분압법은 거의 유사한 방법이며, 환기능이 정상인 사람에서는 환기성역치 측정이 무산소역치를 반영하는 유용성이 었다고 판단되지만 만성기도폐쇄 환자에서는 그 유용성이 떨어진다고 생각된다.

• 한국언론정보학보
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• 제76권
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• pp.92-123
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• 2016

이 연구의 목적은 외국인 범죄 뉴스 접촉이 수용자의 다문화수용성에 어떠한 방식으로 영향을 미치는지 체계적으로 규명하는 데 있다. 특히 미디어와 커뮤니케이션의 유형에 따라 외국인 범죄 뉴스 접촉의 효과가 어떻게 다르게 나타나는지 살폈다. 또한 범죄에 대한 위험지각을 매개변인으로 설정하여 외국인 범죄 뉴스가 어떠한 과정을 통해 수용자의 다문화수용성에 영향을 미치는지 밝혔다. 분석 결과 자신의 주변에서 외국인 범죄가 발생할 수 있다는 지각에는 다양한 정보원천과 커뮤니케이션 채널이 영향을 미치지만, 사회적으로 외국인 범죄가 만연해 있다는 지각에는 텔레비전의 영향력이 두드러지는 것으로 나타났다(연구문제 1). 대화형 매체를 통한 외국인 범죄 뉴스 접촉은 다문화수용성에 유의한 영향을 미치지 않는 반면 담론형 매체를 통한 접촉과 대면 대화를 통한 접촉은 수용자의 다문화수용성에 부정적인 영향을 미치는 것으로 나타났다(연구문제 2). 담론형 매체를 통한 범죄 뉴스 접촉이 다문화수용성에 영향을 미치는데 있어 사회 수준의 위험지각은 완전매개(full mediation) 역할을 하는 것으로 나타났다(연구문제 3). 이러한 결과를 바탕으로 이론적 함의와 실천적 함의를 논의하였다.

• Korean Journal of Radiology
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• 제19권6호
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• pp.1161-1171
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• 2018

Objective: The aim of this study was to investigate diffusion tensor (DT) imaging-derived properties of benign oligemia, true "at risk" penumbra (TP), and the infarct core (IC) during the first 3 hours of stroke onset. Materials and Methods: The study was approved by the local animal care and use committee. DT imaging data were obtained from 14 rats after permanent middle cerebral artery occlusion (pMCAO) using a 7T magnetic resonance scanner (Bruker) in room air. Relative cerebral blood flow and apparent diffusion coefficient (ADC) maps were generated to define oligemia, TP, IC, and normal tissue (NT) every 30 minutes up to 3 hours. Relative fractional anisotropy (rFA), pure anisotropy (rq), diffusion magnitude (rL), ADC (rADC), axial diffusivity (rAD), and radial diffusivity (rRD) values were derived by comparison with the contralateral normal brain. Results: The mean volume of oligemia was $24.7{\pm}14.1mm^3$, that of TP was $81.3{\pm}62.6mm^3$, and that of IC was $123.0{\pm}85.2mm^3$ at 30 minutes after pMCAO. rFA showed an initial paradoxical 10% increase in IC and TP, and declined afterward. The rq, rL, rADC, rAD, and rRD showed an initial discrepant decrease in IC (from -24% to -36%) as compared with TP (from -7% to -13%). Significant differences (p < 0.05) in metrics, except rFA, were found between tissue subtypes in the first 2.5 hours. The rq demonstrated the best overall performance in discriminating TP from IC (accuracy = 92.6%, area under curve = 0.93) and the optimal cutoff value was -33.90%. The metric values for oligemia and NT remained similar at all time points. Conclusion: Benign oligemia is small and remains microstructurally normal under pMCAO. TP and IC show a distinct evolution of DT-derived properties within the first 3 hours of stroke onset, and are thus potentially useful in predicting the fate of ischemic brain.

• Journal of Microbiology and Biotechnology
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• 제11권1호
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• pp.40-49
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• 2001

The present work presents a novel approach for the dynamic quantification of respiration rates on a small scale by using lysine-producing Corynebacterium glutamicum ATCC 21253. Cells sampeld from batch cultures at different times were incubated ina 12-ml scale bioreactor equipped with a membrane mass spectrometer. Under dynamic conditions, gas exchange across the gas-liquid phase, specific respiration rates, and RQ values were precisely measured. For this purpose, suitable mass balances were formulated. The transport coefficients for $O_2$ and $CO_2$, crucial for calculating the respiration activity, were determined as $k_La_{O2}=9.18h^{-1}$ and $k_La_{CO2}=5.10h^{-1}$ at 400 rpm. The application of the proposed method to batch cultures of C. glutamicum ATCC 21253 revealed the maximum specific respiration rates of $q_{O2}=8.4\;mmol\;g^{-1}h^{-1}\;and\;q_{CO2}=8.7\;mmol\;g^{-1}h^{-1}$ in the middle of the exponential growth phase after 5 h of cultivation. When the cells changed from growth to lysine production due to the depletion of the essential amino acids theonine, methionine, and leucine, $q_{O2}\;and\;q_{CO2}$ decreased significantly and RQ increased. The respiration data exhibited an excellent agreement with previous cultivations of the strain [13]. This confirms the potential of the developed approach to realistically reflect the metabolic activities of cells at their point of sampling. The short-term influence of added threonine, methionine, and leucine was highest during the shift from growth to lysine production, where $q_{O2}\;and\;q_{CO2}$ increased 50% within one minute after the pulse addition of these compounds. Non-growing, yet lysine-producing cells taken from the end of the batch cultivation revealed no metabolic stimulation with the addition of threonine, methionine, and leucine.

• Nutrition Research and Practice
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• 제10권2호
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• pp.175-181
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• 2016

BACKGROUND/OBJECTIVES: The anti-obesity effect of quercetin-rich onion peel extract (OPE) was suggested in rats, but information from human studies is limited. This study aimed to investigate the effects of OPE on the body composition of overweight and obese subjects. MATERIALS/METHODS: In this 12-week, randomized, double-blind, placebo-controlled study, parallel clinical trials were performed in overweight and obese Korean subjects. Randomly assigned subjects were instructed to take daily either the placebo (male, 6 and female, 30) or OPE capsules containing 100 mg of quercetin (male, 5 and female, 31). Body composition was measured by using bioimpedance and dual-energy X-ray absorptiometry (DXA). Resting energy expenditure (REE) and respiratory quotient (RQ) were evaluated by using indirect calorie measurement methods. Fasting blood levels of glucose, insulin, lipids, and leptin were determined. RESULTS: Quercetin-rich OPE supplementation significantly reduced the weight and percentage of body fat as measured by DXA (P = 0.02). These effects were not shown in the control group. Levels of blood glucose (P = 0.04) and leptin (P = 0.001 for placebo, P = 0.002 for OPE) decreased in both groups. Significant increases in REE and RQ were observed in both groups (P = 0.003 for placebo, P = 0.006 for OPE) and in the OPE group alone (P = 0.02), respectively. CONCLUSIONS: Quercetin-rich OPE supplementation changed the body composition of the overweight and obese subjects. This result suggests a beneficial role of the anti-obesity effect of OPE human subjects.

• Journal of Microbiology and Biotechnology
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• 제25권2호
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• pp.185-195
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• 2015

Glucoamylase is an important industrial enzyme. Glucoamylase production by industrial Aspergillus niger strain featured with two major problems: (i) empirical substrate feeding methods deteriorating the fermentation performance; and (ii) the high raw materials cost limiting the economics of the glucoamylase product with delegated specification. In this study, we first proposed a novel three-stage varied-rate substrate feeding strategy for efficient glucoamylase production in a 5 L bioreactor using the standard feeding medium, by comparing the changing patterns of the important physiological parameters such as DO, OUR, RQ, etc., when using different substrate feeding strategies. With this strategy, the glucoamylase activity and productivity reached higher levels of 11,000 U/ml and 84.6 U/ml/h, respectively. The performance enhancement in this case was beneficial from the following results: DO and OUR could be controlled at the higher levels (30%, 43.83 mmol/l/h), while RQ was maintained at a stable/lower level of 0.60 simultaneously throughout the fed-batch phase. Based on this three-stage varied-rate substrate feeding strategy, we further evaluated the economics of using alternative carbon sources, attempting to reduce the raw materials cost. The results revealed that cornstarch hydrolysate could be considered as the best carbon source to replace the standard and expensive feeding medium. In this case, the production cost of the glucoamylase with delegated specification (5,000 U/ml) could be saved by more than 61% while the product quality be ensured simultaneously. The proposed strategy showed application potential in improving the economics of industrial glucoamylase production.

• 전기학회논문지
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• 제64권9호
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• pp.1323-1329
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• 2015

The WO₃/Ag/WO₃ transparent thin films are fabricated by the RF magnetron sputtering. This has a transmittance of front and rear about 90% in the visible light range and surface resistance of 6.41Ω/□. In this paper, we analyzed the surface characteristics caused by the working pressure and O₂ plasma surface treatment to apply a transparent electrode that was prepared to the laminated structure with other materials. The working pressure was changed in the WO₃ film to 10mTorr, 7mTorr, and 5mTorr, it showed a lower than roughness of conventional ITO. In addition, by 55.5774 J/m² at 5mTorr, it shows the hydrophobic property with lower process pressure. O₂ plasma surface treatment was changed at the condisions of the RF power to 150W, 100W, and 50W and the process time to 240s, 180s, 120s, and 60s. The surface roughness are the maximum roughness(Rmax) 6.437nm and the average roughness(Rq) 0.827nm at RF power 150W, and the maximum roughness (Rmax) 6.880nm and the average roughness (Rq) 0.839nm at process time 240sec. It showed a lower value than the surface treatment. also about working pressure and process time is increased, it showed the hydrophobic.

• 박물관보존과학
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• 제14권
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• pp.29-35
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• 2013

백자투각연당초문지통과 같이 기형 및 장식기법이 복잡한 도자기의 경우, 기존에 사용되고 있는 복원제는 경화시간이 짧아 정교한 성형이 어려워 틀을 이용하여 복원한다. 하지만 틀을 이용한 복원 또한 시간적, 재료적인 단점이 있기 때문에 직접 복원하는 방법을 연구하고자 하였다. 복원제의 경화시간과 물성은 작업성과 밀접한 관계가 있기 때문에 복잡한 형태의 복원부를 직접 성형할 때는 충분한 가사시간이 확보되는 복원제가 필요하다. 소성점토(Original Sculpey)와 에폭시퍼티(Repair it Quik)를 각기 다른 비율로 혼합하여 가사시간, 색도 변화, 작업성에 대한 실험을 하였다. 실험결과 OS8 : RQ2의 비율로 혼합하였을 경우 가사시간이 충분하고 성형성이 좋았으며 황변도가 낮고 채색성이 좋아 가장 효과적이라는 것을 알 수 있었다.