• 사상체질의학회지
• /
• 제19권2호
• /
• pp.143-154
• /
• 2007

1. Objectives The purpose of this study was to prove the correlation between risk factor of cardiovascular disease and Sasang Constitution and to investigate the effect of oxygen free radical on this correlation. 2. Methods We analyzed 129 patients who visited Cheonan oriental medical hospital from Apr 1, 2007 until May 31, 2007, for medical examination, which Includes Sasang Constitution examination, blood chemistry test and physical examination. And we classified their results into 4 groups based on with blood lipoprotein level and body mass index. 3. Results and Conclusions Mean of lipoprotein in blood was not significantly different among constitutions but with body mass index, was significantly higher in Taeumin than others. And count of dyslipoproteinemia was significantly higher in Taeumin group than soeumin. Therefore, according to our results, risk of cardiovascular disease was higher in Taeumin than other constitutions. Oxygen free radical did not have much effect on correlation between risk factor of cardiovascular disease and Sasang Constitution. However, there was some evidence in soeumin group, that oxygen free radical may have effect on origination of hyperlipidemia.

• Korean Chemical Engineering Research
• /
• 제58권4호
• /
• pp.610-617
• /
• 2020

In process installations, chemicals operate at high temperature and high pressure. Propylene is used as a basic raw material for manufacturing synthetic materials in the petrochemical industry; However, it is a flammable substance and explosive in the gaseous state. Thus, caution is needed when handling propylene. To prevent explosions, an inert gas, carbon dioxide, was used and the changes in the extent of explosion due to changes in pressure and oxygen concentration at 25 ℃, 100 ℃, and 200 ℃ were measured. At constant temperature, the increase in explosive pressure and the rates of the explosive pressure were observed to rise as the pressure was augmented. Moreover, as the oxygen concentration decreased, the maximum explosive pressure decreased. At 25 ℃ and oxygen concentration of 21%, as the pressure increased from 1.0 barg to 2.5 bar, the gas deflagration index (K_g) increased significantly from 4.71 barg·m/s to 18.83 barg·m/s.

• 한국의학물리학회지:의학물리
• /
• 제7권1호
• /
• pp.25-35
• /
• 1996

혼탁한 물질인 생체조직에서 신진대사, 혈액확산, 혈중산소의 비침습적 측정에 관한 연구를 광을 이용한 방법으로 제시하였다. 생체조직내의 산소포화도와 혈액분량을 측정하기 위하여 660nm와 880nm 의 광파장을 이용하여 측정하였으며, 생체조직에서 얻은 광 세기의 데이터는 조직내의 깊은 곳에서 생리적인 변화를 나타낸다. 데이터의 평가는 혈액분량과 산소포화도의 변화에 대한 지수의 기울기로서 조사하여 평가하였다. 여기서 곡선으로 나타낸 지수는 각각의 파장에서 기준파장의 세기와 측정부위에서의 반사광의 세기를 비율에 의한 자연대수로 나타냈다. 장단지 근육에 대한 실험 결과에 따르면 산소의 지수는 운동중에 현저하게 변화를 보여 주었다.

• Computers and Concrete
• /
• 제31권3호
• /
• pp.241-252
• /
• 2023

Corrosion of rebar is one of the major deteriorating mechanisms that affect the durability of reinforced concrete (RC) structures. The increase in CO₂ concentration in the atmosphere leads to early carbonation and deterioration due to corrosion in RC structures. In the present study, an attempt has been made to modify the existing carbonation depth prediction empirical model. The modified empirical model is verified from the carbonation data collected from selected RC structures of CSIR-SERC campus, Chennai and carbonation data available from the reported literature on in-situ RC structures. Attempt also made to study the carbonation depth in the laboratory specimens using oxygen permeability index (OPI) test. The carbonation depth measured from RC structures and laboratory specimens are compared with estimated carbonation depth obtained from OPI test data. The modified empirical model shows good correlation with measured carbonation depth from the identified RC structures and the reported RC structures from the literature. The carbonation depth estimated from OPI values for both in-situ and laboratory specimens show lesser percentage of error compared to measured carbonation depth. From the present investigation it can be said that the OPI test is the suitable test method for both new and existing RC structures and laboratory RC specimens.

• 청정기술
• /
• 제24권1호
• /
• pp.63-69
• /
• 2018

순산소 연소 기술 중 $CO_2$ 회수 비용 절감 효과가 가장 우수한 케미컬루핑연소(chemical looping combustion, CLC) 기술의 핵심인 산소전달입자의 선정을 위해 환원반응 특성 및 물리화학적 특성에 대한 연구를 진행하였다. 세 종류의 산소전달입자(SDN70, N018-R2, N016-R4)를 대상으로 기포유동층 반응기에서 환원반응기체의 농도 및 환원 반응 온도 변화에 따른 산소전달입자의 연료전화율(fuel conversion)과 $CO_2$ 선택도($CO_2$ selectivity)를 측정 및 비교 분석하였다. 또한 산소전달입자의 마모손실 정도 및 입자의 표면 특성을 분석하기 위해 내마모도(Attrition Index, AI) 및 BET surface area를 측정하였다. 결과적으로 세 종류의 산소전달입자 모두 케미컬루핑연소 시스템에 활용하기 적합함을 확인하였으며, 가장 우수한 입자는 N016-R4로 판단되었다.

• Journal of the Korean Wood Science and Technology
• /
• 제17권4호
• /
• pp.77-82
• /
• 1989

In this study the oxygen index method was used to compare the duration of flaming and the rate of weight loss at the level of 6 and 9mm panel thicknesses among solid wood, plywood, particleboard, and medium density fiberboard. The obtained results were as follows: 1. In 9mm-thick panels, the combustibility was the largest in lauan solid wood followed by medium density fiberboard. particleboard. and plywood. 2. Medium density fiberboard was burned more easily than plywood in 6mm-thick panels and the higher oxygen concentration was needed as the panel thickness increased. 3. The oxygen indices of 9mm-thick panels were 29.0 in lauan solid wood, 31.4 in medium density fiberboard, 33.0 in particleboard, and 33.4 in plywood and those of 6mm-thick panels were 28.3 in medium density fiberboard and 29.7 in plywood. 4. The rate of weight loss was the largest in lauan solid wood followed by medium density fiberboard, plywood, and particleboard.

• BMB Reports
• /
• 제32권1호
• /
• pp.25-27
• /
• 1999

Otitis media with effusion (OME) is an inflammatory disease of the middle ear cleft. Oxygen free radicals have been implicated in a variety of inflammatory disorders. Oxygen free radicals may also be involved in the pathogenesis of OME. To evaluate the involvement of oxygen free radicals in the pathogenesis of OME, the level of malondialdehyde, which gives an index of lipid peroxidation by oxygen free radicals, was measured by the reaction with thiobarbituric acid. Malondialdehyde level in the middle ear fluid from the OME group was higher than that in the normal control group. Malondialdehyde level in the middle ear fluid from a mucoid subgroup was higher than that in the serous subgroup. Malondialdehyde levels in the middle ear fluid from the serous subgroup was significantly correlated with symptom duration. The Pearson correlation coefficient between malondialdehyde levels in the middle ear fluid from the serous subgroup and symptom duration was 0.842 (P<0.05). These results indicate that lipid peroxidation by oxygen free radicals may be involved in the pathogenesis of human OME.

• 상하수도학회지
• /
• 제18권3호
• /
• pp.307-311
• /
• 2004

The objective of this work is to evaluate the hypothesis that a good technique for supplying oxygen to the saturated zone in the presence of light nonaqueous phase liquid (LNAPL) pool contamination at the water table is to pass air through the unsaturated zone above the pool. This hypothesis was evaluated in experimental studies performed using a bench-scale, sand-tank reactor, Steady-state abiotic experiments in the sand-tank reactor with air flowing through the reactor headspace demonstrated that oxygen supply through the water table interface into the saturated zone was enhanced when an LNAPL (dodecane) pool was present at the water table. These experimental results confirmed the hypothesis that an LNAPL pool can serve as a high concentration oxygen source to the oxygen-limited area beneath the pool and, as a result, enhance the in situ biodegradation rate.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2004년도 제29회 KOSCI SYMPOSIUM 논문집
• /
• pp.169-174
• /
• 2004

The NOx emission characteristics with oxygen enrichment in nonpremixed counterflow and coflow jet flame of $CH_4$ fuel have been investigated numerically. A small amount of nitrogen is included in oxygen-enriched combustion, in order to consider the inevitable $N_2$ contamination by air infiltration. The results show that the initial increase of NO with increasing oxygen enrichment is due to increasing temperature and residence time, while its subsequent decrease above 75% oxygen is due to decreasing the consumption rate of nitrogen. When oxygen addition exceeds 30%, Thermal NO gradually becomes the dominant production pathway and Prompt NO becomes negative pathway for net NO production rate. It is also seen that Thermal NO plays an important role in NO reduction when strain rate increase in oxygen-enriched combustion. Finally, the results of EINOx with oxygen enrichment in coflow jet flame show the similar profile with those of conterflow flame. It is confirmed that, with leakage of 1% nitrogen in the oxidizer stream, the corresponding EINOx is eight times of that emitted from regular $CH_4$/Air flame.

• Journal of Preventive Medicine and Public Health
• /
• 제25권1호
• /
• pp.34-43
• /
• 1992

To investigate the effect of hyperoxia on EKG findings and to evaluate the applicability of EKG as noninvasive monitoring index of oxygen toxicity, 38 rabbits were continuously exposed to 6 different conditions-3 hyperbaric oxygenations (HBO-2.5, 3.5 and 5ATA, 100% $O_2$), normobaric oxygenation (NBO,100% $O_2$), hyperbaric aeration (HBA-5ATA, 21% $O_2$) and normobaric aeration (NBA, 21% $O_2$)-for 120 minutes and their EKG and time to dyspnea and convulsion were recorded. Dyspnea and death were observed in exposure conditions of HBO-3.5 and HBO-5 (Positive rate of dyspnea 10%, 100%, death : 10%, 25%, respectively) only, and convulsion in 4 oxygenation groups (NBO;20%, HBO-2.5;20%, HBO-3.5;20%, HBO-5;88%). Abnormal EKG findings included arrhythmia and ST-T changes and the incidences was increasing with doses(partial pressure of oxygen). In addition to EKG change, findings observed during exposure were dyspnea and convulsion in the order of appearance and when non specific ST-T change was accepted as positive(abnormal) finding, the frequency of abnormal EKG was statistically significant(p<0.01), but when it was excluded from positive results, the frequency of EKG change was not significant(p>0.05). These results suggest that the effect of hyperoxia on heart is myocardial ischemia and arrhythmia, that oxygenation more than 3.5ATA causes myocardial damage in 120 minutes exposure, and that EKG is valuable as monitoring index of oxygen toxicity.