• Title/Summary/Keyword: surface program

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Towed underwater PIV measurement for free-surface effects on turbulent wake of a surface-piercing body

  • Seol, Dong Myung;Seo, Jeong Hwa;Rhee, Shin Hyung
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.5 no.3
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    • pp.404-413
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    • 2013
  • In the present study, a towed underwater particle image velocimetry (PIV) system was validated in uniform flow and used to investigate the free-surface effects on the turbulent wake of a simple surface-piercing body. The selected test model was a cylindrical geometry formed by extruding the Wigley hull's waterplane shape in the vertical direction. Due to the constraints of the two-dimensional (2D) PIV system used for the present study, the velocity field measurements were done separately for the vertical and horizontal planes. Using the measured data at several different locations, it was possible to identify the free-surface effects on the turbulent wake in terms of the mean velocity components and turbulence quantities. In order to provide an accuracy level of the data, uncertainty assessment was done following the International Towing Tank Conference standard procedure.

Research on the Correlation of the Surface Tension and Sensory Quality of Bitter Substances (쓴 맛 물질의 표면 장력과 쓴 맛의 상관 관계)

  • Kim, Jeong-Mee;Pfeilsticker, Konrad
    • Korean Journal of Food Science and Technology
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    • v.27 no.5
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    • pp.646-651
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    • 1995
  • The correlation between the bitter taste and the surface tension was found for bitter tasting, aqueous solutions. By the Szyszkowski's equation, the surface tension (STR) and taste curves (JND) were derived more clearly using the Techplot program. The specific capillary activity (log b values) for bitter tasting solutions are negatively correlated to the recognition threshold. It was shown that a more bitter substances has greater capillary activity. The correlation between the recognition threshold $(log\;C_{1})$ and the substance specific constant (a and b values) of sensory (JND) and surface tension values indicates good agreement. This means that the model of surface area adsorption in the solution/air system can apply also for the sensory model microvillus membrane in the mouth.

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Carbohydrate-electrolyte drinks exhibit risks for human enamel surface loss

  • de Melo, Mary Anne Sampaio;Passos, Vanara Florencio;Lima, Juliana Paiva Marques;Santiago, Sergio Lima;Rodrigues, Lidiany Karla Azevedo
    • Restorative Dentistry and Endodontics
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    • v.41 no.4
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    • pp.246-254
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    • 2016
  • Objectives: The aim of this investigation was to give insights into the impact of carbohydrate-electrolyte drinks on the likely capacity of enamel surface dissolution and the influence of human saliva exposure as a biological protective factor. Materials and Methods: The pH, titratable acidity (TA) to pH 7.0, and buffer capacity (${\beta}$) of common beverages ingested by patients under physical activity were analyzed. Then, we randomly distributed 50 specimens of human enamel into 5 groups. Processed and natural coconut water served as controls for testing three carbohydrate-electrolyte drinks. In all specimens, we measured surface microhardness (Knoop hardness numbers) and enamel loss (profilometry, ${\mu}m$) for baseline and after simulated intake cycling exposure model. We also prepared areas of specimens to be exposed to human saliva overnight prior to the simulated intake cycling exposure. The cycles were performed by alternated immersions in beverages and artificial saliva. ANOVA two-way and Tukey HDS tests were used. Results: The range of pH, TA, and ${\beta}$ were 2.85 - 4.81, 8.33 - 46.66 mM/L and 3.48 - $10.25mM/L{\times}pH$, respectively. The highest capacity of enamel surface dissolution was found for commercially available sports drinks for all variables. Single time human saliva exposure failed to significantly promote protective effect for the acidic attack of beverages. Conclusions: In this study, carbohydrate-electrolyte drinks usually consumed during endurance training may have a greater capacity of dissolution of enamel surface depending on their physicochemical proprieties associated with pH and titratable acidity.

The Structure and Electrical Characteristics of ZnO Varistors Surface using-Fractal (프랙탈을 이용한 ZnO 바리스터 표면 구조 및 전기적 특성)

  • Oh, Soo-Hong;Hong, Kyung-Jin;Lee, Jin;Lee, Joon-Ung;Kim, Tae-Sung
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.10
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    • pp.834-839
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    • 2000
  • The structural properties that SEM photograph of ZnO varistors surface studied by fractal mathematics program were investigated to verify the relations of electrical characteristics. The SEM photograph of ZnO varistors surface were changed by binary code and the grain shape of that were analyzed by fractal dimension. The void of ZnO varistors surface was found by fractal program. The relation between grain density and electrical properties depend on fractal dimension. The grain size in ZnO varistors surface was decreased by increasing of Sb$_2$O$_3$ addition. The spinel structure was formed by Sb$_2$O$_3$addition and it was depressed the ZnO grain formation. The grain size of ZnO by Sb$_2$O$_3$addition were from 5 to 10[${\mu}{\textrm}{m}$]. Among of ZnO varistors, fractal dimension of ZnO4 was very high as a 1.764. The density of grain boundary in ZnO2 and ZnO3 varistors surface was 15[%] by formed spinal structure. The breakdown electric field of ZnO2 that fractal dimension has 1.752 was very high to be 8.5[kV/cm]. When the fractal dimensin was high, the grain shape of ZnO varistors was complex and the serial layers of ZnO grain was increased.

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The Effect of Pelvic Inclination on Voice Production in sitting (앉은 자세에서 골반 경사도가 음성에 미치는 영향)

  • Choe, Jeong Hui
    • The Journal of the Convergence on Culture Technology
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    • v.1 no.2
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    • pp.91-95
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    • 2015
  • The purpose of this study was to evaluate the difference voice production, according to the pelvic inclination while in the sitting position. Measure the sound produced(pitch) in three positions with the Praat program. position: anterior tilt position, posterior tilt position, neutral position(seat surface tilted 15 degrees). We found that the mean values of pitch were statistically significant different according to three types of sitting positions (p<0.05). The following result was observed: anterior tilt position > posterior tilt position > neutral position. There was significant difference in the neutral position. This finding suggests that the seat surface inclinations have an effect on speech production. Especially, neutral position may be an effective posture that may help increases the speech production.

Development of the Program Road lighting Road Surface Property Measuring Apparatus (도로 조명용 프로그램과 노면특성 장치의 개발)

  • Kim, Gi-Hoon;Sim, Sang-Man;Kim, Hoon
    • Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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    • v.13 no.2
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    • pp.1-6
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    • 1999
  • Average illuminaoce and luminance can be calculated by grarhical rrethods to a certain extent, but to calculate for a wide place, a suitable software is needed. Softwares suitable for this purpose have been already developed in foreign nations, but the appropiate softwares for domestic use have not been developed 1berefore a program is develqJed which is executable in Hangul Windows. The softwares LAPRoad, is develqJed to calculate luminaoce and illuminance distribution of road surlace, as well as average luminance and illuminance, overall uniformity, longitudinal uniformity, threshold increement, veilling luminance, and glare. And an apparatus that measures road surface reflection properties is developed. Because the road surlace reflection properties is very important in luminance calculation, then concrete road surlace reflection properties were measered.asered.

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The Optimum Structural Design of the High-speed Surface Effect Ship using Composite Materials - Minimum Weight Design (복합재료 쌍동형 초고속선의 최적 구조 설계 - 최소 중량 설계)

  • Chang-Doo Jang;Ho-Kyung Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.35 no.2
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    • pp.94-103
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    • 1998
  • Recently, many researches are carried for high-speed and light craft. In this study, the optimum structural design procedure and the computer program are developed to minimize the hull weight of SES(Surface Effect Ship) built of composite materials. Three types of composite materials-Sandwich, Single Skin and Hybrid type- are considered and the efficiency of each type is investigated. In design process, the optimum design of main members is performed at first considering longitudinal strength. And then, the transverse member design is performed considering torsional strength SSDP(Structural Synthesis Design program) of U.S. Navy is adopted for design algorithm and DnV classification nile for design loads and strength criteria. For optimum structural design, ES 1+1 optimization technique is used.

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Stringer Shape Optimization of Aircraft Panel Assembly Structure (항공기 패널 조립체 구조물의 스트링거 형상 최적화)

  • Kim Hyoung-Rae;Park Chan-Woo
    • Journal of the Korean Society for Precision Engineering
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    • v.23 no.6 s.183
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    • pp.136-142
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    • 2006
  • Optimization of the aircraft panel assembly constructed by skin and stringers is investigated. For the design of panel assembly of the aircraft structure, it is necessary to determine the best shape of the stringer which accomplishes lowest weight under the condition of no instability. A panel assembly can fail in a variety of instability modes under compression. Overall modes of flexure or torsion can occur and these can interact in a combined flexural/torsion mode. Flexure and torsion can occur symmetrically or anti-symmetrically. Local instabilities can also occur. The local instabilities considered in this paper are buckling of the free and attached flanges, the stiffener web and the inter-rivet buckling. A program is developed to find out critical load for each instability mode at the specific stringer shape. Based on the developed program, optimization is performed to find optimum stringer shape. The developed instability analysis program is not adequate for sensitivity analysis, therefore RSM (Response Surface Method) is utilized instead to model weight and instability constraints. Since the problem has many local minimum, Genetic algorithm is utilized to find global optimum.

Pseudo 3D FEM analysis for wave passage effect on the response spectrum of a building built on soft soil layer

  • Kim, Yong-Seok
    • Earthquakes and Structures
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    • v.8 no.5
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    • pp.1241-1254
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    • 2015
  • Spatially variable ground motions can be significant on the seismic response of a structure due to the incoherency of the incident wave. Incoherence of the incident wave is resulted from wave passage and wave scattering. In this study, wave passage effect on the response spectrum of a building structure built on a soft soil layer was investigated utilizing a finite element program of P3DASS (Pseudo 3-dimensional Dynamic Analysis of a Structure-soil System). P3DASS was developed for the axisymmetric problem in the cylindrical coordinate, but it is modified to apply anti-symmetric input earthquake motions. Study results were compared with the experimental results to verify the reliability of P3DASS program for the shear wave velocity of 250 m/s and the apparent shear wave velocities of 2000-3500 m/s. Studied transfer functions of input motions between surface mat foundation and free ground surface were well-agreed to the experimental ones with a small difference in all frequency ranges, showing some reductions of the transfer function in the high frequency range. Also wave passage effect on the elastic response spectrum reduced the elastic seismic response of a SDOF system somewhat in the short period range.

A Study on the Development of a Real Time Simulator for the ESP (Electronic Stability Program) (전자식 차체 자세 제어 장치를 위한 실시간 시뮬레이터 개발에 관한 연구)

  • Kim, Tae Un;Cheon, Seyoung;Yang, Soon Young
    • Journal of Drive and Control
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    • v.16 no.4
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    • pp.48-55
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    • 2019
  • The Electronic Stability Program (ESP), a system that improves vehicle safety, also known as YMC (Yaw Motion Controller) or VDC (Vehicle Dynamics Control), is a system that operates in unstable or sudden driving and braking situations. Developing conditions such as unstable or sudden driving and braking situations in a vehicle are very dangerous unless you are an experienced professional driver. Additionally, many repetitive tests are required to collect reliable data, and there are many variables to consider such as changes in the weather, road surface, and tire condition. To overcome this problem, in this paper, hardware and control software such as the ESP controller, vehicle engine, ABS, and TCS module, composed of three control zones, are modeled using MATLAB/SIMULINK, and the vehicle, climate, and road surface. Various environmental variables such as the driving course were modeled and studied for the real-time ESP real-time simulator that can be repeatedly tested under the same conditions.