• International Journal of Fluid Machinery and Systems
• /
• 제5권2호
• /
• pp.65-71
• /
• 2012

The objective of the present investigation is to explore the possibility of improving the performance of a centrifugal fan at low Reynolds numbers using a simple passive means, namely Gurney flap (GF). GFs of 1/$8^{th}$ inch brass angle (3.175 mm) corresponding to 15.9% of blade exit height or 5.1% of blade spacing at the impeller tip are attached to the impeller blade tip on the pressure surface. Performance tests are carried out on the centrifugal fan with vaneless diffuser at five Reynolds numbers (viz., 0.30, 0.41, 0.55, 0.69, $0.82{\times}10^5$, i.e., at five speeds respectively at 1,100, 1,500, 2,000, 2,500 and 3,000 rpm) without and with GF. Static pressures on the vaneless diffuser hub and shroud are also measured for each speed at four flow coefficients [${\phi}$=0.23 (below design flow coefficient), ${\phi}$=0.34 (design flow coefficient), ${\phi}$=0.45 (above design flow coefficient) and ${\phi}$=0.60 (above design flow coefficient)] with and without GF. From the performance curves it is found that the performance of the fan improves considerably with GFs at lower Reynolds numbers and improves marginally at higher Reynolds number. Similar improvements are observed for the static pressures on the diffuser hub and shroud. The effect of Reynolds number on the performance and static pressures is considerable. However the effect is reduced with GFs.

• 대기
• /
• 제26권1호
• /
• pp.1-18
• /
• 2016

Eleven Tropical Cyclone (TC) intensity guidance models in the western North Pacific have been validated over 2008~2014 based on various analysis methods according to the lead time of forecast, year, month, intensity, rapid intensity change, track, and geographical area with an additional focus on TCs that influenced the Korean peninsula. From the evaluation using mean absolute error and correlation coefficients for maximum wind speed forecasts up to 72 h, we found that the Hurricane Weather Research and Forecasting model (HWRF) outperforms all others overall although the Global Forecast System (GFS), the Typhoon Ensemble Prediction System of Japan Meteorological Agency (TEPS), and the Korean version of Weather and Weather Research and Forecasting model (KWRF) also shows a good performance in some lead times of forecast. In particular, HWRF shows the highest performance in predicting the intensity of strong TCs above Category 3, which may be attributed to its highest spatial resolution (~3 km). The Navy Operational Global Prediction Model (NOGAPS) and GFS were the most improved model during 2008~2014. For initial intensity error, two Japanese models, Japan Meteorological Agency Global Spectral Model (JGSM) and TEPS, had the smallest error. In track forecast, the European Centre for Medium-Range Weather Forecasts (ECMWF) and recent GFS model outperformed others. The present results has significant implications for providing basic information for operational forecasters as well as developing ensemble or consensus prediction systems.

• 한국건축시공학회지
• /
• 제3권2호
• /
• pp.119-127
• /
• 2003

Test specimen test was performed using concrete reinforced with fiber sheet and the test variables were based on the kinds of fiber and the number of reinforcement layers. Using steel-concrete reinforced with fiber sheet, compression tests were performed and the test variables were the kinds of fiber, number reinforcement layers and reinforcement layer order. The following results were obtained: 1) It was demonstrated that compressive strength of the test specimen reinforced during test specimen test and member test increased as the number of reinforcement layers increased. 2) It was shown that non-reinforced test, specimen were destroyed during the member tests, but the specimen reinforced with CFS destroyed and the GFS-reinforced specimen and composite reinforced specimen showed ductile destruction. 3) As a result of tests on kinds of reinforcement fiber, it was demonstrated that CFS-reinforced test specimen had higher compressive strength in a 공시체 test. In the member test, 2ply-and 3ply-GFS reinforced specimens except lplied one had higher compressive strength. It was because partial destruction occurred due to the rate of height/section. 4) For layer strength order, compared with test specimen reinforced only with a single reinforced material, test specimen reinforced with CFS and GFS, and test specimen reinforced with CFS first showed better results in compressive strength and ductility judgement.

• 한국환경과학회지
• /
• 제32권8호
• /
• pp.595-611
• /
• 2023

The purpose of this study is to improve the daily prediction results of PM2.5 from the air quality diagnosis and evaluation system operated by the Busan Institute of Health and Environment in real time. The air quality diagnosis and evaluation system is based on the photochemical numerical model, CMAQ (Community multiscale air quality modeling system), and includes a 3-day forecast at the end of the model's calculation. The photochemical numerical model basically has limitations because of the uncertainty of input data and simplification of physical and chemical processes. To overcome these limitations, this study applied DNN (Deep Neural Network), a deep learning technique, to the results of the numerical model. As a result of applying DNN, the r of the model was significantly improved. The r value for GFS (Global forecast system) and UM (Unified model) increased from 0.77 to 0.87 and 0.70 to 0.83, respectively. The RMSE (Root mean square error), which indicates the model's error rate, was also significantly improved (GFS: 5.01 to 6.52 ug/m³ , UM: 5.76 to 7.44 ug/m³ ). The prediction results for each concentration grade performed in the field also improved significantly (GFS: 74.4 to 80.1%, UM: 70.0 to 77.9%). In particular, it was confirmed that the improvement effect at the high concentration grade was excellent.

• Journal of Applied Biological Chemistry
• /
• 제56권2호
• /
• pp.119-129
• /
• 2013

Thirteen different Streptomyces isolates were evaluated for their ability to produce keratinase using chicken feather as a sole carbon and nitrogen sources under solid state fermentation (SSF). Streptomyces sp. NRC 13S produced the highest keratinase activity [1,792 U/g fermented substrate (fs)]. The phenotypic characterization and analysis of 16S rDNA sequencing of the isolate were studied. Optimization of SSF medium for keratinase production by the local isolate, Streptomyces sp. NRC13S, was carried out using the one-variable-at-a-time and the statistical approaches. In the first optimization step, the effect of incubation period, initial moisture content, initial pH value of the fermentation medium, and supplementation of some agro-industrial by-products on keratinase production were evaluated. The strain produced about 2,310 U/gfs when it grew on chicken feather with moisture content of 75% (w/w), feather: fodder yeast ratio of 70:30 (w/w), and initial pH 7 using phosphate buffer after 8 days. Based on these results, the Box-Behnken design and response surface methodology were applied to find out the optimal conditions for the enzyme production. The corresponding maximal production of keratinase was about 2,569.38 U/gfs.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2017년도 춘계학술대회 논문집
• /
• pp.92.2-92.2
• /
• 2017

스퍼터링은 이온화된 불활성 기체가 음의 전압이 인가된 타겟에 충돌하여 운동량 전달에 의해 타겟 물질을 떼어내어 기판에 박막을 형성하는 진공증착 기술의 하나이다. 스퍼터링은 초기에 이극 또는 삼극 스퍼터링이 사용되다가 1970년대에 마그네트론 스퍼터링이 등장하면서 고속화 및 박막의 특성향상이 이루어졌으며 현재 스퍼터링 기술의 표준으로 자리를 잡았다. 마그네트론 스퍼터링은 그러나 타겟 효율이 30%내외로 낮고 여전히 다른 증착 기술에 비해 증발율이 낮다는 단점이 지적되고 있으며 이를 극복하기 위한 많은 연구가 진행되어 왔다. 증발율을 향상시키고 타겟 효율을 향상시킬 수 있는 방안의 하나로 HC-GFS(Hollow Cathode - Gas Flow Sputtering) 소스가 연구되어 왔다. GFS란 증기가 발생하는 부분과 증착이 이루어지는 부분의 진공도를 변화시켜 압력차에 의해 증기가 이송되어 증착되는 기술을 의미하며 HC-GFS는 타겟과 타겟 사이에 할로 방전을 발생시켜 이때 발생된 플라즈마로 타겟의 물질을 스퍼터링하고 스퍼터링된 입자를 압력차로 이송하여 기판에 증착하는 기술이다. HC-GSF 소스는 증발율이 향상되고 타겟 효율이 높다는 점에서 많은 관심을 가졌으나 아직까지 상용화 실적은 미미한 상황이다. 본 연구에서는 HC-GFS 소스를 제작하고 그 특성을 평가하였으며 금속을 증착하여 상용 증발원으로써의 가능성을 검토하고자 하였다.

• 척추신경추나의학회지
• /
• 제5권1호
• /
• pp.11-22
• /
• 2010

Object: This study was planned to show the physical characteristics of soccer player and their Yangdorak measurements. Method: We categorized 5 study group. (I-Players classified by age; II, III-Players and control group; IV-Players who had positive RF and the others; V-Players who had digestive disorder and the others) And We conducted the potentiality of skin resistance(Yangdorak) and GFS, PFT, ECG and the other, then analysis that. Result: As old aged group, Yangdorak shown lower RS, but that was not significant. Player group had higher Yangdorak score at H5, F1, F2, F5 than control group. Player group was shown better cardiopulmonary function, but H1, H2, H3 score were not significant. Players who conducted RF test shown not significant difference of H4 measurement between positive and negative group. Digestive disorder group had higher F1, F6 score, but that wasn't significant.

• 한국건축시공학회지
• /
• 제8권5호
• /
• pp.43-51
• /
• 2008

This study examines shear capacity performance and structural characteristics of reinforced concrete beam using carbon fiber sheet(CFS), g)ass fiber sheet(GFS), glass fiber steel plate(GSP) and carbon fiber bar CB) which are reinforcing materials for reinforced concrete beam in order to produce similar condition to repair and reinforce actual structure and aims to provide data available In designing and constructing reinforced concrete structures under the structural damage. This study obtains the following conclusions. After considering the shear experiment results. it was indicated that the CB reinforced test object was the best in the shear capacity improvement and ductility capacity as it was contained in the concrete and was all operated, Also, GFS reinforced test object indicated the reduced flexural capacity but good shear capacity. GSP reinforced test object had bigger reinforcing strength than other reinforcing test objects. On the other hand, it showed the lowest reinforcement effect as compared section thickness of reinforced material because it showed the bigger relativity a section thickness of reinforced material. If the adherence to the concrete is improved, it will seem to show bigger reinforcement effect.

• 한국환경과학회지
• /
• 제33권6호
• /
• pp.435-442
• /
• 2024

We investigated the accuracy of surface air temperature prediction according to the selection of land-use data and initial meteorological data using the Weather Research and Forecasting model-v4.2.1. A numerical experiment was conducted at the Daegu Dyeing Industrial Complex. We initially used meteorological input data from GFS (Global forecast system)and GDAPS (Global data assimilation and prediction system). High-resolution input data were generated and used as input data for the weather model using the land cover data of the Ministry of Environment and the digital elevation model of the Ministry of Land, Infrastructure, and Transport. The experiment was conducted by classifying the terrestrial and topographic data (land cover data) and meteorological data applied to the model. For simulations using high-resolution terrestrial data(10 m), global data assimilation, and prediction system data(CASE 3), the calculated surface temperature was much closer to the automatic weather station observations than for simulations using low-resolution terrestrial data(900 m) and GFS(CASE 1).

• Pediatric Gastroenterology, Hepatology & Nutrition
• /
• 제11권1호
• /
• pp.21-27
• /
• 2008

목 적: 한국 소아청소년에서 시행되는 의식하 진정내시경 시행 실태와 부작용, 그리고 새로운 약제 등의 사용 여부 등을 다기관 연구를 통해 파악하여 적절한 지침을 세우는데 도움을 주고자 하였다. 방 법: 대한소아소화기영양학회 회원 소속 병원 중 2차 병원 이상의 병원을 대상으로 2006년 6월부터 2006년 7월까지 한 달의 기간 동안 시행된 내시경 검사를 대상으로 하였으며, 16개의 문항으로 설문지를 만들어 배포 후 수거된 결과를 조사 분석하였다. 결 과: 전체 내시경 시술 횟수 465예 중 의식하 진정 내시경은 89.0% (414예), 전신 마취하에 시술한 예는 0.9% (4예)였으며, 의식하 진정내시경의 비율은 상부소화관의 경우 89.1% (362예), 하부소화관의 경우는 88.1%(52예)였다. 의사 한 명 당 한달 평균 16.0건의 내시경을 시술하고 있었으며, 내시경을 시행하는 의사 수는 병원당 평균 1.16명, 보조자는 평균 2.58명이었다. 또한 마취과 의사의 도움을 받는 경우는 3개(12%) 병원이었다. 사용한 약물은 전체 의식하 진정내시경 414예 중 미다졸람(midazolam)만 사용한 경우가 전체 84.5% (350예), 프로포폴(propofol)을 사용한 경우는 상부소화관 내시경을 시행한 2예(0.5%)였고, 2가지 이상의 복합제재를 사용한 경우는 하부소화관검사의 경우 44예(84.6%), 역행성담관조영술(ERCP)의 경우가 2예(100%)였다. 진정내시경 시행 중 사용한 모니터링은 심전도 감시와 함께 맥박산소측정기를 사용한 경우가 91.4% (320예), 자동혈압측정기를 같이 사용한 경우 5.1% (18예)였다. 부작용으로는 일시적 산소포화도의 저하로 산소를 투여한 경우로 4.6% (16예)였다. 또한 길항제로 flumazenil을 투여한 경우는 모든 환자에서 투여한다고 답한 경우를 제외하면 2.71% (9예)였다. 진정내시경 시행 여부의 결정은 환자 혹은 환자의 보호자와 상의하여 결정하는 경우가 84% (21개 병원)였다. 의사가 느끼는 만족도는 68%에서 만족하는 것으로 나타났으며, 의사가 느끼는 환자 혹은 환자 보호자의 만족도는 만족이 84% (21개 병원)였다. 결 론: 우리나라 소아의 의식하 진정내시경 시 사용한 약물은 대부분 미다졸람 단독 투여만으로 시행하며, 하부소화관 검사 시에는 복합 약물을 투여한 경우가 많았다. 또한 환자와 의사 대부분 만족하는 것으로 나타났으며, 부작용은 거의 나타나지 않았다.