• 대한토목학회논문집
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• 제30권5B호
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• pp.479-486
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• 2010

신뢰성 있는 수문자료의 획득은 효율적인 물 관리를 위한 가장 기본적인 조건인 동시에 가장 필수적인 조건이다. 특히 최근 이상기후의 영향으로 빈번하게 발생하고 있는 도시홍수에 대응하기 위한 경보체계 등을 구축하는데 있어 사용자가 관측하고자 하는 임의 지점에서 유황자료의 획득은 매우 중요하다. 지속적인 하천정비 사업을 통해 외수범람에 의한 홍수 발생빈도는 점차 낮아지고 있지만, 하수관거의 노후화, 관리 소홀 등의 원인으로 내수배제가 원활하지 못해서 발생하는 내수침수로 인한 도시홍수는 지속적으로 발생하고 있다. 이러한 도시홍수 저감을 위해서는 도시배수시스템에 대한 지속적인 관리와 현황파악이 필수적이다. 본 연구에서는 CDMA(Code Division Multiple Access) 무선통신기술과 Bluetooth 근거리 무선통신기술을 사용하여 전문적인 지식이 없는 사용자라도 누구나 언제, 어디서든 도시배수시스템의 임의의 지점에서 유황을 파악하고, 배수관망에서는 유황 관측과 동시에 유출 경로 추적이 가능한 도시배수관망 유속측정 시스템의 개발을 목표로 하였다. 도시배수관망 유속측정 시스템은 세 단계로 구성되어 운영된다. 첫 번째 단계에서 ubiquitous floater를 사용하여 획득한 유황 정보를 서버로 전송하면, 두 번째 단계에서 서버 컴퓨터를 통해 도시 배수시스템의 현황을 판단하고, 마지막 단계에서 정보를 GUI(Graphic User Interface)를 통해 사용자에게 제공하게 된다. 개발된 도시배수관망 유속측정 시스템을 경기도 수원의 원천천에 위치한 배수관망에 적용하여 현장 실험한 결과, 도시 배수관리를 위해 필요한 정보들을 실시간으로 획득하고 관리할 수 있었다.

• ETRI Journal
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• 제46권3호
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• pp.513-525
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• 2024

Deep neural networks trained on labeled medical data face major challenges owing to the economic costs of data acquisition through expensive medical imaging devices, expert labor for data annotation, and large datasets to achieve optimal model performance. The heterogeneity of diseases, such as Alzheimer's disease, further complicates deep learning because the test cases may substantially differ from the training data, possibly increasing the rate of false positives. We propose a reconstruction-based self-supervised anomaly detection model to overcome these challenges. It has a dual-subnetwork encoder that enhances feature encoding augmented by skip connections to the decoder for improving the gradient flow. The novel encoder captures local and global features to improve image reconstruction. In addition, we introduce an entropy-based image conversion method. Extensive evaluations show that the proposed model outperforms benchmark models in anomaly detection and classification using an encoder. The supervised and unsupervised models show improved performances when trained with data preprocessed using the proposed image conversion method.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.619-624
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• 2001

A performance test facility for turbopump inducer cavitation was developed and the inducer cavitation performance tests were performed. Major components of the performance test facility are driving unit, test section, piping, water tank, and data acquisition and control system. The maximum of testing capability of this facility are as follows: flow rate - 30kg/s; pressure - 13 bar; rotational speed 10,000rpm. This cavitation test facility is characterized by the booster pump installed at the outlet of the pump that extends the flow rate range, and by the pressure control system that makes the line pressure down to vapor pressure. The vacuum pump is used for removing the dissolved air in the water as well as the line pressure. Performance tests were carried out and preliminary data of test model inducer were obtained. The cavitation performance test and cavitation bubble flow visualization were also made. This facility is originally designed for turbopump inducer performance test and cavitation test. However it can be applied to the pump impeller performance test in the future with little modification.

• 한국지능정보시스템학회:학술대회논문집
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• 한국지능정보시스템학회 2001년도 The Pacific Aisan Confrence On Intelligent Systems 2001
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• pp.211-218
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• 2001

This paper introduces a method of constructing expert systems in an integrated environment for automatic software design. This integrated environment may be applicable from top-level system architecture design, data flow diagram design down to flow chart and coding. The system is integrated with three CASE tools, FSD (Functional Structure Diagram), DFD (Data Flow Diagram) and structured chart PAD (Problem Analysis Diagram), and respective expert systems with automatic design capability by reusing past design. The construction way of these expert systems is based on systematic acquisition of design knowledge stemmed from a systematic design work process of well-matured developers. The design knowledge is automatically acquired from respective documents and stored in the respective knowledge bases. By reusing it, a similar software system may be designed automatically. In order to develop these expert systems in a short period, these design knowledge is expressed by the unified frame structure, functions of th expert system units are partitioned mono-functions and then standardized components. As a result, the design cost of an expert system can be reduced to standard work procedures. Another feature of this paper is to introduce the integrated environment for automatic software design. This system features an essentially zero start-up cost for automatic design resulting in substantial saving of design man-hours in the resulting in substantial saving of design man-hours in the design life cycle, and the expected increase in software productivity after enough design experiences are accumulated.

• 동아시아식생활학회지
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• 제15권5
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• pp.606-612
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• 2005

This study was performed to provide basic data that predict the application of Saengmaegsan(SMS) as medicinal food. SMS has been used in oriental medicine for many years as a therapeutic agent for cerebral disease. We examined the effects of SMS on physiological function in isolated abdominal aorta and femoral artery from rabbit and measured the changes of regional cerebral hood flow(rCBF), which was continually monitored by laser-doppler flowmeter and pressure transducer in anesthetized adult Spargue-Dawley rats through the data acquisition system composed of MacLab and Macintosh computer. The contraction forces by injection of norephinephrine in isolated abdominal aorta and femoral artery were significantly decreased in each concentration of SMS treatment compared with control. rCBF was increased by SMS in a dose-dependent manner. These results suggest that SMS causes a diverse response of rCBF and arterial diameter. These mechanism in rCBF increase may be mediated by prostaglandis, cyclic GMP and adrenergic $\beta-receptor$. Also mechanism in artery contraction decrease is also mediated by prostaglandis and cyclic GMP. These results indicate that SMS can be nsed as a safe and clinically applicable as a supplementation of diet therapy for cerebral cardiovascular disease patients.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.1295-1299
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• 2003

The Mass Flow Controller(MFC) has become crucial in semiconductor manufacturing equipments. It is an important element because the quality and the yield of a semiconductor process are decided by the accurate flow control of gas. Therefore, the demand for the high speed and the highly accurate control of MFCs has been requested. It is hard to find an article of the control algorithm applied to MFCs. But, it is known that commercially available MFCs have PID control algorithms. Particularly, when the system detects the flow by way of heat transfer, MFC control problem contains the time delay and the nonlinearity. In this presentation, MFC control algorithm with the superior performance to the conventional PID algorithm is discussed and the superiority is demonstrated through the experiment. Fuzzy controller was utilized in order to compensate the nonlinearity and the time delay, and the performance is compared with that of a product currently available in the market. The control system, in this presentation, consists of a personal computer, the data acquisition board and the control algorithm carried out by LabWindows/CVI program on the PC. In addition, the method of estimating an actual flow from sensor output containing the time delay and the nonlinearity is presented. In conclusion, according to the result of the experiment, the proposed algorithm shows better accuracy and is faster than the conventional controller.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집E
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• pp.380-385
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• 2001

In the present study, flow characteristics of turbulent oscillatory flow in a square-sectional $180^{\circ}$ curved duct are investigated experimentally. In order to measure wall shear stress and pressure distributions, experimental studies for air flow are conducted in a square-sectional $180^{\circ}$ curved duct by using the LDV system with the data acquisition and the processing system. The wall shear stress measuring point bend angle of the $150^{\circ}$ and pressure distribution of the inlet (${\phi}=0^{\circ}$) to the outlet (${\phi}=180^{\circ}$) at $10^{\circ}$ intervals of the duct. The results obtained from the experimentation are summarized as follows: A wall shear stress value in an inner wall is larger than that in an outer wall, except for the phase angle (${\omega}t/{\pi}/6$) of 3, because of the intensity of secondary flow. The pressure distributions are the largest in accelerating and decelerating regions at the bend angle(${\phi}$) of $90^{\circ}$ and pressure difference of inner and outer walls is the largest before and after the ${\phi}=90^{\circ}$.

• Journal of Mechanical Science and Technology
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• 제18권6호
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• pp.1002-1009
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• 2004

Direct contact air conditioning systems, in which heat and mass are transferred directly between air and water droplets, have many advantages over conventional indirect contact systems. The purpose of this research is to investigate the cooling and heating performances of direct contact air conditioning system for various inlet parameters such as air velocity, air temperature, water flow rate and water temperature. The experimental apparatus comprises a wind tunnel, water spray system, scrubber, demister, heater, refrigerator, flow and temperature controller, and data acquisition system. The inlet and outlet conditions of air and water are measured when the air contacts directly with water droplets as a counter flow in the spray section of the wind tunnel, and the heat and mass transfer rates between air and water are calculated. The droplet size of the water sprays is also measured using a Malvern Particle Analyzer. In the cooling conditions, the outlet air temperature and humidity ratio decrease as the water flow rate increases and as the water temperature, air velocity and temperature decrease. On the contrary, the outlet air temperature and humidity ratio increase in the heating conditions as the water flow rate and temperature increase and as the air velocity decreases.

• 오토저널
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• 제15권2호
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• pp.92-104
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• 1993

In the present study, the velocity profiles and entrance length of developing transitional pulsating flows are investigated both analytically and experimentally in the entrance region of a square duct. The systems of conservation equations for transitional pulsating flows in a square duct are solved analytically by linearizing the non-linear convective terms. Analytical solutions are obtained in the form of infinite series for velocity pofiles. The experimental study for the air flow in a square duct(40mm*40mm*4000mm) is carried out to measure velocity profiles and other parameters by using a hot-wire anemometer with a data acquisition and processing system. The distribution of velocity profiles( $u_{ps}$ / $u_{m,ta}$) in the decelerating period is higher than in the accelerating period. The distribution of the axial component of the axial component of velocity in the transitional flow is nearly uniform in the central region of the duct, and decrease rapidly near the wall. The entrance length correlation of the transitional pulsating flows in a square duct is obtained to be $L_{e}$/ $D_{h}$=0.83 $A_{1}$R $e_{ta}$ /(.omega. sup+1)$^{2}$TEX>

• 한국산학기술학회논문지
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• 제14권4호
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• pp.1533-1539
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• 2013

본 논문에서는 층류 및 난류 유동 특성 중 경계층 두께와 배제 두께, 그리고 모멘텀 두께에 대한 기존의 이론값과 실제 CFD 해석을 통한 수치해석의 데이터를 비교하였다. Freestream velocity는 Reynolds 수에 영향을 주게 되고, airfoil 주변에서의 유동의 층류 및 난류에 영향을 주게 된다. 층류 및 난류의 경우 유동특성이 달라 경계층 두께 및 배제두께, 그리고 모멘텀 두께가 달라지게 되고, 결국 airfoil의 공력특성인 양력과 항력, 그리고 pitching moment에 영향을 주며, separation point도 다양한 angle of attack에서 바뀌게 된다. 이번 연구에서의 목적은 비점성 유동과, 층류 및 난류 각 경우에 대한 유동특성에 대해 알아보는 것이다. 연구에서 사용된 airfoil의 경우 c=1인 Joukowski airfoil을 사용하였으며, CFD는 상용 프로그램인 Fluent 6.0을 통해 NACA-0012 airfoil을 사용하였다. 층류 및 난류에서의 $Re_c$는 $Re_c$=3,000, 700,000이며 각각에 해당하는 속도는 0.045, 10 m/s이다. 본 연구를 통해 기존의 실험값과 수치해석의 결과가 잘 일치함을 알 수 있으며, 이를 통해 다양한 airfoil의 형상을 모델링할 수 있는 근거를 마련하였다.