• 한국안전학회지
• /
• 제18권4호
• /
• pp.71-77
• /
• 2003

To inject fresh air into a fire room, Positive Pressure Ventilation (PPV) can be used and the blower of PPV increases inside pressure of the room. It makes high flow rate of products of combustion, smoke and heat from the structure, and it is very helpful to fireman on the fire extinguishing work. The flame moves to the direction of airflow and the temperature of flame can be decreased rapidly. In this experiment, a water mist system is applied to PPV to increase the effectiveness, and various effective factors are studied. n-Heptane and pine wood stick were used as fuel. Temperatures at the above and behind the combustion pan were strongly reduced by the water mist system and by the convective cooling with airflow. The smoke density was also decreased by PPV with water mist system and it can be explained by the absorption of smoke particles on the water mist droplet and by the strong exhausting effects of mobile fan.

• Journal of Biosystems Engineering
• /
• 제33권4호
• /
• pp.248-252
• /
• 2008

An experiment was conducted in order to investigate gasification characteristics of rice husks in a fixed bed, which was a pre-step to design a continuous gasification system. Two air supply levels for gasification were chosen and their effects on the producer gas amount and producer gas composition were discussed. The main components of the producer gas were CO, $CO_2$, $O_2$, $H_2$ and THC (Total HydroCarbon). As airflow rate decreased, more producer gas was produced. The peak amount of CO, $H_2$ and THC were 28%, 7.5% and 0.68% in volume when constant airflow rate of $3.36\;m^3/s$ was used in the batch operation. About 4.5 kg of ash (9%) and condensed water including tars of 6 kg (11%) were produced from 50 kg rice husks in the gasification. Excluding the byproducts, all rice husks seemed to be transformed into producer gas. This gasification study was conducted prior to developing a continuous gasification system for biomass including agricultural byproducts.

• 대한후두음성언어의학회지
• /
• 제7권1호
• /
• pp.11-19
• /
• 1996

Reinke's edema is used for describing varying degrees of chronic swelling of the vocal folds. The acoustic analysis of Reinke's edema has not been reported so far in this country. The purpose of this study is to clarify acoustic and aerodynamic characteristics of the Reinke's edema. Several acoustic evaluations ＆ aerodynamic studies were done in 20 Reinke's edema patients and the data was compared with those of 20 normal controls. Videolaryngoscopy also was done to classify the severity in grading. We used C-Speech, Doctor speech science, and Phonatory function analyser. In C-Speech, we compared jitter, shimmer, and SNR(signal to noise ratio) of normal and Rrinke's edema patient. In Doctor speech science, we compared NNE(Glottal noise energy), speech fundamental frequency, voice quality between two groups. And in phonatory function analyser for aerodynamic function test, we compared speech intensity, airflow rate, and expiratory pressure between two groups. In conclusion, Reinke's edema patients showed lower voice pitches than normal, additionally jitter, shimmer, SNR(signal to noise ratio), NNE(Glottal noise energy), airflow rate, and expiratory pressure may be meaningful parameters for diagnosis and prognosis for treatment.

• Environmental Engineering Research
• /
• 제24권4호
• /
• pp.711-717
• /
• 2019

The application of advanced oxidation for the treatment of oil refinery wastewater under UV radiation by using nanoparticles of titanium dioxide was investigated. Synthetic wastewater prepared from phenol crystals; Power Glide SAE40 motor vehicle oil and water was used. Response surface methodology (RSM) based on the Box-Behnken design was employed to design the experimental runs, optimize and study the interaction effects of the operating parameters including catalyst concentration, run time and airflow rate to maximize the degradation of oil (SOG) and phenol. The analysis of variance and the response models developed were used to evaluate the data obtained at a 95% confidence level. The use of the RSM demonstrated the graphical relationship that exists between individual factors and their interactive effects on the response, as compared to the one factor at time approach. The obtained optimum conditions of photocatalytic degradation are the catalyst concentration of 2 g/L, the run time of 30 min and the airflow rate of 1.04 L/min. Under the optimum conditions, a 68% desirability performance was obtained, representing 81% and 66% of SOG and phenol degradability, respectively. Thus, the hydrocarbon oils were readily degradable, while the phenols were more resistant to photocatalytic degradation.

• 대한설비공학회:학술대회논문집
• /
• 대한설비공학회 2007년도 동계학술발표대회 논문집
• /
• pp.99-104
• /
• 2007

Tracer gas technique is widely used to measure the ventilation rates and/or ventilation effectiveness of building spaces. However, the conventional method using a single tracer gas can measure only outdoor air change rates in a single zone. This paper deals with the multi-gas tracer technique to measure air exchange rates between rooms. Interzonal air movements are important to characterize overall ventilation performance of complicated multi-zone buildings. Experiments are conducted in a simple two-room model with known airflow rates using tracer gases of SF6 and R134a. The concentration decays of two tracer gases are measured after simultaneous injections in each room. The governing equations are derived from the continuity and the mass balance of each room. The data reduction procedure are developed to obtain the inter-room airflow rates using the governing matrix inversion, and various data manipulation methods are tested, such as data shift, interpolation, smoothing, and etc, to improve the estimate and interpretation of the results.

• 음성과학
• /
• 제9권2호
• /
• pp.167-177
• /
• 2002

Uvulopalatopharyngoplasty (UPPP) is one of the popular surgical procedure for snoring and sleep apnea syndrome. The main principle of this procedure is to reduce abundant velopharyngeal soft tissues resulting in a shortened soft palate, which may cause some alterations in speech sound. The purpose of this study is to evaluate the change of velopharyngeal function after UPPP in the view of aerodynamics. Thirty three patients who received uvulopalatopharyngoplasty for correcting snoring and sleep apnea were included in this study. The airflow, airflow rate and air pressure during the production of oral and nasal consonants were measured before surgery and 4 week and 8 week after surgery. The oral air flows and pressures for oral and nasal consonants were not changed after surgery. However, oral air pressure for nasal consonants were increased significantly after surgery. The nasal air flows for oral consonants were not changed after surgery, but for nasal consonants were decreased at 8 weeks after surgery. The nasal flow rate for oral and nasal consonants were increased at 8 weeks after surgery. The uvulopalatopharyngoplasty may result in affecting the aerodynamic air streams during speech production.

• 생물환경조절학회지
• /
• 제11권3호
• /
• pp.101-107
• /
• 2002

본 연구에서는 온실의 온풍식 난방시스템 연통에 장착할 수 있는 폐열 회수기의 성능을 개선하기 위하여 각각 상이하게 설계된 3개의 열교환 장치에 대해 열회수 성능을 실험적으로 비교 분석하였다. A형 열회수시스템의 경우, 초기 투자비용과 현재의 농용 전력요금 하에서 대체로 1년을 전후하여 투자에 대한 보상이 충분한 것으로 판단된다. B형 및 C형 열회수시스템의 경우, 열 회수용 공기 흐름방향이 180$^{\circ}$굴절로 저항이 크게 발생되어 송풍팬의 전압 증가에 따른 유속 증가가 미미하며 동일한 열 교환면적에서는 송풍팬의 공기저항 증대로 열 회수 성능이 현저히 개선되지는 못했지만, 직선형보다 B형의 경우 약 5%. C형의 경우 약 13%정도 높은 열 회수효율을 보였다. 송풍팬의 용량은 A형에 사용된 용량인 25m$^3$/min전후가 적절할 것으로 판단되며, 적정 송풍팬 용량 하에서 열회수성능은 헤어핀형이 직선형보다 효과적인 것으로 나타났다. 다만, 헤어핀형은 물론 직선형에서도 열교환 파이프의 배치밀도, 파이프 길이 및 두께 등의 변화에 따른 최적화 연구가 수반되어야 할 것으로 판단된다.

• 멤브레인
• /
• 제25권3호
• /
• pp.256-267
• /
• 2015

침지식분리막 오염을 최소화하기 위한 두 가지 공기세정방식을 비교하였다. 연속적인 공기세정과 단계별 공기량을 증가시키는 방식을 연구하였다. 15분의 여과 중에 세정공기의 증가는 5분마다 단계별로 공기량을 증가시켜주었다. 모의 여과 원수에 분말활성탄을 10 g/L 이하 그리고 카올린은 20 g/L 이하로 준비하였으며, 플러스는 80 LMH로 하였다. 단계별 공기세정방식은 연속적인 공기세정 방식보다 분리막 오염억제에 효과적이었다. 추가적으로 주입된 응집제는 분리막 오염저감을 보다 향상시켰다. 연속적인 공기세정의 오염현상은 공경막힘과 분리막 표면에 지속적인 입자의 축적에 기인하였다.

• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2005년도 제31회 KOSCO SYMPOSIUM 논문집
• /
• pp.231-237
• /
• 2005

Interruption of good fluidization in a fluidized bed ash cooler(FBAC) for discharging bed materials such as sand or coal ash particles from the CFB combustor is frequently happened because of agglomeration of the particles in the bed. This unstable operation may, in the worst case, result in an unscheduled boiler shut down. In this study, we examined the operation problems of the FBAC of Tonghae CFB boiler and studied and introduced the simple detection and solution techniques with analyzing the mixing property and the occurrence of defluidization in a simulated fluidized bed ash cooler system (0.5m-H x 0.5m-W x 1.0m-L). The bridge of the large particles at the bed surface could be observed, and this caused to form the defluidization area at the entrance of the FBAC. The defluidization was affected not only by airflow rates but also by the particles discharging rates as well as particle size distribution in the FBAC. The local defluidization could be detected by analysis of the accumulated standard deviation error at a given period of time. Also, the regulation of the overall or local airflow rate made clearing up the local defluidization possible.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2005년도 생물공학의 동향(XVII)
• /
• pp.232-237
• /
• 2005

The cellulloytic enzymes, such as FPase and amylase, production by Trichoderma inhamatum KSJ1 using 10L air circulation bioreactor were tried. Physical properties of the employed bioreactor, mixing time, $k_{L}$ a were examined in airflow conditions of enzyme production cultures. Mixing time of distilled water at 0.6, 1.2, 1.8 vvm were 25, 21, 9 sec, respectively, and mandel's medium using rice straw and pulp as carbon sources were 31, 25, 15 sec. Mixing time decreased when airflow rate increased. $k_L$ a of distilled water at 0.6, 1.2, 1.8 vvm were measured -22.52, -29.31, -39.62, respectively, and the mandel's medium were -47.8, -18.5, -21.4. The $k_L$ a values was increased linearly as the air-flow rates increased. However the values in mandel's medium showed different results, especially at 0.6 vvm. Amylase and FPase activity at the 1.2 vvm was 3.39U/mL, 0.72U/mL in 5 days cultivation. and the activities at 0.6 vvm were 2.01U/mL, 0.39U/mL, respectively. The enzyme productivity at 1.2 vvm was higher than at 0.6 vvm, indicating that high oxygen tension is requested for the efficient enzyme production culture of T. inhamatum KSJ1.