• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2009년도 춘계 학술대회 제21권1호
• /
• pp.543-544
• /
• 2009

고강도콘크리트의 내화성능 증진에 효과적인 것으로 알려진 섬유(NY, PP)는 섬유의 길이조합과 혼입율에 따라 유동성에 차이가 있다. 본 논문에서는 섬유의 길이조합과 혼입율이 고강도콘크리트의 유동성과 레올로지 특성에 미치는 영향을 분석하기 위하여 몰탈시험체를 대상으로 미니 슬럼프 플로우(Mini slump-flow), 간이 V-lot 및 회전점도계에 의한 점도측정을 수행하였다. 실험결과, 섬유의 길이 조합에 따른 유동특성은 큰 차이가 없으나 섬유혼입률이 증가할수록 점도는 큰 것으로 나타났다.

• 한국자동차공학회논문집
• /
• 제22권2호
• /
• pp.182-189
• /
• 2014

This paper proposes a decoupler design method to reduce interaction between exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems in passenger car diesel engines. The EGR valve and VGT vane are respectively used to control air-to-fuel ratio (AFR) of exhaust gas and intake pressure. A plant model for EGR and VGT systems is defined by a first order transfer function plus time-delay model, and the loop interaction between these systems is analyzed using a relative normalized gain array (RNGA) method. In order to deal with the loop interaction, a design method for simplified decoupler is applied to this study. Feedback control algorithms for AFR and intake pressure are composed of a compensator using PID control method and a prefilter. The proposed decoupler is evaluated through engine experiment, and the results successfully showed that the loop interaction between EGR and VGT systems can be reduced by using the proposed decoupler. Furthermore, it presents stable performance even off from the designed operating point.

• 센서학회지
• /
• 제13권6호
• /
• pp.436-445
• /
• 2004

In this study, a uroflowmetry system was developed to detect a voiding symptom conveniently at home or hospital. A implemented hardware was composed of mechanism and system circuit part, the software was developed to process uroflow data, graph display, extraction of parameter, and evaluation of congregate rate so as to analysis obtaining uroflow data. The following experiment was performed to evaluate an ability of classification and fitness. The curve pattern of uroflow was classified into each symptom. Various parameters were calculated in the curve pattern of each uroflow as follows. The parameters are MFR, AFR, VOL, VT, and FT. A significant difference among parameters was examined by a statistical analysis for extracted parameters between normal and abnormal experimental group. The uroflow data with the various symptom was divided into normal and abnormal group using fuzzy classifier. The result of the fuzzy classification using MFR and AFR was superior by 91.23 % than grouping evaluation including VOL.

• 대한핵의학회지
• /
• 제28권1호
• /
• pp.52-61
• /
• 1994

Background : The demand for refinement in noninvasive and quantitative assessment of left ventricular (LV) function is increasing. Purpose : To assess normal values of left ventricular functional parameters during both systole and diastole by scintigraphic method using computerized triple-head gamma camera and to evaluate correlations between these parameters. Methods : ECG gated blood pool scan with $^{99m}Tc$-Human serum albumin was performed in 94 normal Korean subjects. Ejection fraction (EF), systolic parameters [peak emptying rate (PER), average emptying rate (AER), time to peak emptying rate (TPER)], and diastolic parameters [peak filling rate (PFR), average filling rate (AFR), time to peak filling rate (TPFR)] were obtained by analysis of LV time-activity curve, the correlation of these parameters to the age and sex, and the correlation between these parameters were evaluated. Results : 1) Mean value of ejection fraction in study subjects was $59.6{\pm}5.25%$ and showed no significant correlation to age (r=-0.08) and sex but showed most pronounced correlation to PFR (r=0.46, p<0.001), PER (r=0.41, p<0.001), AFR (r=0.34, p<0.001) and AER (r=0.28, p<0.01). 2) Mean values of systolic parameters were as follows: $PER=3.22{\pm}0.50$ end-diastolic volume/sec, $AER=2.22{\pm}0.45$ end-diastolic volume/sec, $TPER=103.5{\pm}29.30$ msec. They showed no significant correlation to age and sex. 3) Mean values of diastolic parameters were as follows: $PFR=2.71{\pm}0.51$ end-diastolic volume/sec, $AFR=1.83{\pm}0.44$ end-diastolic volume/sec, $TPFR=132.1{\pm}33.45$ msec. They showed strong correlation to age (r=0.70, -0.64, 0.37, p<0.001). Conclusions : Left ventricular functional parameters in normal Korean subjects were obtained reliably by computerized scintigraphic method and may be applied to the evaluation of cardiac function in diseased patients.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2002년도 하계종합학술대회 논문집(5)
• /
• pp.293-296
• /
• 2002

In this study, the object is a development on uroflowmetry system to detect a voiding symptom conveniently in home or hospital. The hardware was composed of mechanism and system circuit part, the software was divided into firmware and PC program part. The following experiment was performed to evaluate an ability of classification and fitness. First, the following parameters was calculated in each flow curve pattern. The parameters are MFR, AFR, VOL, VT, FT, and TMF. A significant difference among parameters was examined through a statistical analysis for extracted parameters between normal and abnormal group. In the next work, the following experimentation was performed to classify the voiding symptom. Analysis of congregate rate was examined to find out classification possibility about each symptom of BPH, voiding difficulty, detrusor failure and hyperreflexia, unstable bladder. The uroflow data with the above symptom was divided into normal and abnormal group using fuzzy classifier. and that was performed appending the other group again. Fuzzy classification result using MFR and AFR was superior by 89.6 % more than grouping evaluation including VOL.

• Archives of Plastic Surgery
• /
• 제39권3호
• /
• pp.232-237
• /
• 2012

Background : Skin injuries, such as lacerations due to trauma, are relatively common, and patients are very concerned about the resulting scars. Recently, the use of ablative and non-ablative lasers based on the fractional approach has been used to treat scars. In this study, the authors demonstrated the efficacy and safety of ablative fractional resurfacing (AFR) for traumatic scars using a 2,940-nm erbium: yttrium-aluminum-garnet (Er:YAG) laser for traumatic scars after primary repair during the early posttraumatic period. Methods : Twelve patients with fifteen scars were enrolled. All had a history of facial laceration and primary repair by suturing on the day of trauma. Laser therapy was initiated at least 4 weeks after the primary repair. Each patient was treated four times at 1-month intervals with a fractional ablative 2,940-nm Er:YAG laser using the same parameters. Posttreatment evaluations were performed 1 month after the fourth treatment session. Results : All 12 patients completed the study. After ablative fractional laser treatment, all treated portions of the scars showed improvements, as demonstrated by the Vancouver Scar Scale and the overall cosmetic scale as evaluated by 10 independent physicians, 10 independent non-physicians, and the patients themselves. Conclusions : This study shows that ablative fractional Er:YAG laser treatment of scars reduces scars fairly according to both objective results and patient satisfaction rates. The authors suggest that early scar treatment using AFR can be one adjuvant scar management method for improving the quality of life of patients with traumatic scars.

• 한국융합학회논문지
• /
• 제4권3호
• /
• pp.43-50
• /
• 2013

This paper presents a model predictive control (MPC) based on a neural network (NN) model for air/fuel ration (AFR) control of automotive engines. The novelty of the paper is that the severe nonlinearity of the engine dynamics are modelled by a NN to a high precision, and adaptation of the NN model can cope with system uncertainty and time varying effects. A single dimensional optimization algorithm is used in the paper to speed up the optimization so that it can be implemented to the engine fast dynamics. Simulations on a widely used mean value engine model (MVEM) demonstrate effectiveness of the developed method.

• 한국분무공학회지
• /
• 제5권3호
• /
• pp.9-16
• /
• 2000

In a SI engine, three-way catalyst converter has the best efficiency when A/F ratio is near the stoichiometry. The feedback control using oxygen sensors in the commercial engine has limits caused by the system delays. So it is necessary to control fuel quantity in accordance with intake air amount in order to reduce exhaust emission and improve the specific fuel consumption. Precise A/F ratio control requires measurement of air amount with respect to the cylinder and injection fuel according to the air amount In this paper, we applied nonlinear fuel injection model and developed the algorithm of A/F ratio control. This algorithm includes the methods of measurement of transient air mass flowing into each cylinder, of calculation of injection pulse width for measured air mass, and the method of feedback and engine control by using lambda sensor. Also we developed control program for IBM-PC by using C++ Builder, and tested it in the commercial engine.

• 한국분무공학회지
• /
• 제22권1호
• /
• pp.22-28
• /
• 2017

In this study, the effects of intake valve closing timing by using Cam-in-Cam system on combustion and emission characteristics for diesel engine were investigated under GT-POWER simulation environment. As a result, it was found that volumetric efficiency and effective compression ratio were decreased as the intake valve closing(IVC) timing is retarded due to its backflow effect. Also, we found that in-cylinder pressure, heat release rate and NOx emission were decreased as IVC timing was retarded. These show that the LIVC(late intake valve closing) can be effective to control AFR and mixing rate in diffusion combustion of diesel engine.

• 한국분무공학회지
• /
• 제23권1호
• /
• pp.1-8
• /
• 2018

In this study, the effects of variation in cam phasing and valve lift of exhaust valves by using Cam-in-Cam system on combustion and emission characteristics for diesel engine were investigated under GT-POWER simulation environment. This paper showed analytic result of combustion characteristics and diesel exhaust valve's control with GT-Power 1-D detail model. As a result, it was found that volumetric efficiency and IMEP were decreased as the exhaust valve opening and closing timing is advanced due to its internal EGR effects. Also, it was found that NOx emission were decreased as EVC timing was retarded. These show that the retarding the exhaust valve closing and opening while keeping the duration at constant can be effective for controlling AFR and mixing rate in diffusion combustion of diesel engine.