• 대한의용생체공학회:의공학회지
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• 제7권1호
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• pp.75-79
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• 1986

In this paper, a multigate pulsed doppler system with parallel signal processing which enables the transcutaneous assesment of the blood-flow velocities of five adjacent sample volumes is developed. The outputs of the system are audio signals, velocity curves and velocity profiles of 5 adjacent sample volumes. We have applied to the major superficial arteries and obtained the detailed information about the time dependent blood-flow behavior.

• Journal of Trauma and Injury
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• 제31권1호
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• pp.1-5
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• 2018

Purpose: Although there has been substantial progress for the treatment of thoracic trauma, the mortality of the penetrating neck injury is still high, has been reported about 10-15%. However, there has not been a report which is reflecting Korean medical present. We retrospectively analyzed the penetrating neck injury patients based on the Korean Trauma Data Base. Methods: Between December 2013 and June 2017 at the trauma center of the Pusan National University Hospital, Busan, Korea, total of 36 patients with isolated low-velocity penetrating neck injuries were included. We analyzed the patients' age, gender, injury mechanism and causes by medical chart review. Results: Among total of 36 patients, 26 (72.2%) were male and 10 (27.8%) were female. Homicidal neck injuries were most common, followed by accidental and suicidal injuries (47% vs. 33% vs. 19%, respectively). All penetrating injuries in our study were low-velocity trauma such as following: knife (n=16, 44.4%); glass or glass bottle (n=11, 30.6%); scissors (n=4, 11.1%); grinder (n=2, 5.6%); and three (8.3%) of miscellaneous injuries. Twenty-seven (75.0%) patients underwent emergency surgery, and only one (2.8%) patient underwent elective surgery. Eleven (30.6) patients were diagnosed with superficial injuries, including six patients who had conservative treatment. Twelve (33.3%) patients had arterial injuries and 10 (27.8%) patients had venous injuries. The patients who had deep injuries showed significant difference against the patient with superficial injury (98.0 vs. 129.1, p=0.008). Conclusions: Low velocity penetrating injury confined to the neck is able to be successfully treated with prompt surgical management. Regardless of the conditions which are evaluated at emergency department, all penetrating neck injury patients should be regarded as urgent surgical candidates.

• 대한약침학회지
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• 제6권2호
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• pp.91-104
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• 2003

Objective : This study was carried to make out the connection between cerebral artery blood flow velocity and ischemic theory that presumed the cause of Bell's palsy. Method : We measured cerebral artery blood flow velocity each external carotid artery, internal carotid artery, common carotid artery, siphon, superficial temporal artery by TCD to 20 patients who diagnosed as facial nerve palsy from march 2001 to July 2001 and all objectives devided two groups as palsy side. A group is right side facial nerve palsy and B group is left facial nerve palsy. Results : 1. There is no effective change of blood flow in external carotid artery either A, B group. 2. There is no effective change of blood flow in internal carotid artery either A, B group. 3. There is no effective change of blood flow in common carotid artery either A, B group. 4. There is no effective change of blood flow in siphon artery either A, B group. 5. There is no effective change of blood flow in superficial temporal artery either A, B group.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.136-141
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• 2000

A study of counter-current two-phase flow in narrow rectangular channels has been performed. Two-phase flow regimes were experimentally studied in 760 mm long and 100 mm wide test sections with 2.0 and 3.0mm gaps. The resulting data have been compared to previous transition models. For the transition from bubbly to slug flow the superficial velocity of gas increased as the gap width increased. The comparison of experimental data to the transition model developed by Taitel and Barnea showed relatively good agreement for the bubbly-to-slug transition in the case of 2mm gap width. For the criteria of Mishima and Ishii to be applicable to the slug-to-churn transition the distribution parameter should be well defined for narrow channels. Even though the gap width of narrow channels increased the superficial gas velocity did not change for the transition form chum to annular flow regime. For the chum-to-annular transition the model of Taitel and Barnea showed discrepancies with experimental data, especially in the channel with larger gap.

• Ocean and Polar Research
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• 제25권3호
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• pp.269-275
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• 2003

Effects of different operating factors including superficial air velocity (SAV), hydraulic residence time (HRT), protein concentration, and foam overflow height on protein removal by a foam fractionator in simulated seawater aquaculture system were investigated. This experiment was conducted on batch and consecutive modes at different combinations of the affecting factors. The foam fractionator had a diameter of 20cm and a height of 120cm and the experiment was conducted with synthetic wastewater. In 5 consecutive trials, protein concentrations in culture tank water decreased faster when the foam fractionator was operated at higher SAVs and lower HRTs. In batch trials, protein removal rates increased with an increase in SAV but decreased with an increase in URT. Higher protein concentrations in the bulk solution resulted in higher protein removal rates. Protein concentrations in the collected foam condensates increased but the foam overflow rates decreased with the increase of foam overflow heights. The results of this experiment indicate that foam fractionation would be an effective way for protein removal in seawater aquaculture systems and the performance of the foam fractionator depends largely on the operating parameters, especially SAV.

• 대한기계학회논문집
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• 제19권9호
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• pp.2365-2372
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• 1995

The objective of this study is to get the basic data for the development of fluidized bed combustor. For this purpose, various rake angles(.theta.=20.deg., 25.deg., 30.deg., 35.deg.) of finned tubes and a smooth tube were installed horizontally in the fluidized bed combustor of 410*250mm. The effect of fluidized bed temperature, superficial velocity in bed, size of bed materials, rake angle of finned tubes on the heat transfer coefficient was experimentally investigated. The following results were obtained. (1) Under the fluidized bed temperature(750.deg. C-900.deg. C), and the gas velocity in bed(1.1-2.8m/sec), The highest heat transfer coefficient was measured with the rake angle of finned tubes was .theta.=25.deg. and .theta.=35.deg. for the average fluidized material particle size of 1.22mm and 1.54mm, respectively. Generally, the heat transfer coefficient of finned tubes is 1.4 to 2.4 times larger than that of smooth tubes. (2) The size of bed materials influences the rake angle of finned tubes which can have the highest heat transfer coefficient. As the temperature in bed gets higher, the effect of the rake angle of finned tubes on the heat transfer coefficient becomes greater.

• Korean Chemical Engineering Research
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• 제44권2호
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• pp.200-206
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• 2006

세라믹 담체가 충진된(공극률 32％) 생물여과 반응기(BAF)를 이용하여 암모니아성 질소폐수를 처리할 때, 수리학적 체류시간(HRT) 및 폭기량의 변화가 아질산 축적에 미치는 영향에 대해서 고찰하였다. 암모니아성 합성 폐수 및 석유화학 실폐수를 $1.6kgNH_4^+-N/m^3{\cdot}d$ 내외의 질소 부하로 BAF에 공급하였을 때, 암모니아성 질소의 제거율은 폭기량 증가에 비례하였으나 아질산 축적률은 폭기량 외에도 HRT의 영향을 받았다. 0.23시간의 HRT에서(공탑 체류시간 기준 0.7시간)는 0.23, 0.45, 0.56 cm/s로 공기 선속도를 증가시키면, 암모니아성 질소 제거율은 각각 73, 90, 92％로 증가하였으나 아질산 축적비($NO_2-N/NO_x-N$)는 0.92, 0.82, 0.48로 점차 감소하였다. 반면에 HRT 0.9시간, 공기 선속도 0.34~0.45 cm/s 범위에서는 암모니아성 질소 제거율 89％, 아질산 축적비 0.13 내외로 아질산 축적률이 급격하게 감소하였다. 공기 선속도 0.34 cm/s, HRT 1.4시간에서는 암모니아성 질소 제거율의 감소로 free ammonia(FA, $NH_3-N$) 농도가 상승하였고, 이후 약 50일에 걸쳐 아질산 축적비는 0.95 이상까지 점차 증가하였다. 본 연구에서는 HRT 0.23시간에서의 FA 농도 및 폭기 조건이 HRT 0.9시간 조건에 비해 아질산 축적에 더 불리했음에도 HRT 0.23시간에서의 아질산 축적률이 더 높게 나타났다. 따라서 FA 농도, 폭기 조건 외에도 HRT, 질소 부하 조건에 따라 BAF에서 아질산 축적량이 영향을 받았다. 반면에 FA 농도가 매우 높게(FA 5~15 mgN/L) 유지되는 조건에서는 운전 조건에 상관없이 아질산 축적이 안정하게 일어났으며 이 경우는 암모니아성 질소 제거율이 감소하였다.

• Biotechnology and Bioprocess Engineering:BBE
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• 제4권1호
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• pp.51-58
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• 1999

A mathematical model for a three phase fluidized bed bioreactor (TFBBR) was proposed to describe oxygen utilization rate, biomass concentration and the removal efficiency of Chemical Oxygen Demand (COD) in wastewater treatment. The model consisted of the biofilm model to describe the oxygen uptake rate and the hydraulic model to describe flow characteristics to cause the oxygen distribution in the reactor. The biofilm model represented the oxygen uptake rate by individual bioparticle and the hydrodynamics of fluids presented an axial dispersion flow with back mixing in the liquid phase and a plug flow in the gas phase. The difference of setting velocity along the column height due to the distributions of size and number of bioparticle was considered. The proposed model was able to predict the biomass concentration and the dissolved oxygen concentration along the column height. The removal efficiency of COD was calculated based on the oxygen consumption amounts that were obtained from the dissolved oxygen concentration. The predicted oxygen concentration by the proposed model agreed reasonably well with experimental measurement in a TFBBR. The effects of various operating parameters on the oxygen concentration were simulated based on the proposed model. The media size and media density affected the performance of a TFBBR. The dissolved oxygen concentration was significantly affected by the superficial liquid velocity but the removal efficiency of COD was significantly affected by the superficial gas velocity.

• 한국안전학회지
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• 제14권3호
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• pp.84-92
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• 1999

The effects of air velocity and excess air on combustion characteristics were studied in a fluidized bed combustor. The domestic low-grade anthracite coal with heating value of 2010 kcal/kg and the imported bituminous coal from Australia with heating value of 6520 kcal/kg were used as coal samples. The combustion characteristics of mixed fuels in a fluidized bed combustor could be interpreted by pressure fluctuation properties, ash distribution and gas emission. The properties of the pressure fluctuations, such as the standard deviation, cross-correlation function, dominant frequency and the power spectral density function, were obtained from the statistical analysis. From this study, the combustion region increased with increasing air velocity but decreased with excess air due to combustion characteristics of anthracite and bituminous coal.

• 대한화학회지
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• 제4권1호
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• pp.78-80
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• 1957

Up to now, only superficial studies on the combustion velocity of smokeless fuels have been reported, while it should be a basical factor on the utilization of low quality coals and some other smokeless solid fuels. It was, therefore, difficult to choose raw material coals in manufacturing gaseous fuels. With the intent to solve above problem, we have determined combustion velocity of domestic anthracites, graphites, coalites of lignite and cokes from Japanese bituminous coal. The results show that the cokes from Japanese bituminous coal which has been used as raw material in the manufacturing gaseous fuels such as water gas, or producer gas in Korea can be replaced by some sources of domestic anthracite or coalite of lignite.