• 한국농공학회:학술대회논문집
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• 한국농공학회 2000년도 학술발표회 발표논문집
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• pp.321-326
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• 2000

This study was performed to analyze the variation of inside temperature of greenhouse according to shading methods. We used two shading method of external and internal method. The shading effect of external screen was superior to internal screen. Soil temperature of greenhouse without screen was higher than outside soil temperature, but the value of greenhouse with internal and external screen was lower than outside.

• 센서학회지
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• 제33권4호
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• pp.230-236
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• 2024

This study aimed to analyze the environmental factors affecting tomato growth by examining the correlation between weather and growth environment sensor data from P Smart Farm located in Gwangseok-myeon, Nonsan-si, Chungcheongnam-do. Key environmental variables such as the temperature, humidity, sunlight hours, solar radiation, and daily light integral (DLI) significantly affect tomato growth. The optimal temperature and DLI conditions play crucial roles in enhancing tomato growth and the photosynthetic efficiency. In this study, we developed a model to correct and predict the time-series variations in internal environmental sensor data using external weather sensor data. A linear regression analysis model was employed to estimate the external temperature variations and internal DLI values of P Smart Farm. Then, regression equations were derived based on these data. The analysis verified that the estimated variations in external temperature and internal DLI are explained effectively by the regression models. In this research, we analyzed and monitored smart-farm growth environment data based on weather sensor data. Thereby, we obtained an optimized model for the temperature and light conditions crucial for tomato growth. Additionally, the study emphasizes the importance of sensor-based data analysis in dynamically adjusting the tomato growth environment according to the variations in weather and growth conditions. The observations of this study indicate that analytical solutions using public weather data can provide data-driven operational experiences and productivity improvements for small- and medium-sized facility farms that cannot afford expensive sensors.

• The Journal of the Acoustical Society of Korea
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• 제22권2E호
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• pp.78-86
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• 2003

We analyzed the measured acoustic field to explore the characteristics of a horizontal coherence in shallow water. Signal spatial coherence data were obtained in the continental shelf off the east coast of Korea using a horizontal line array. The array was deployed on the bottom of 130 m water depth and a sound source was towed at 26 m depth in the source-receiver ranges of 1-13 ㎞. The source transmitted 200 ㎐ pure tone. Topography and temperature profiles along the source track were measured to investigate the relationship between the horizontal coherence and environment variations. The beam bearing disturbance and array signal gain degradation is examined as parameters of horizontal coherence. The results show that the bearing disturbance is about ± 8° and seems to be affected by temporal variations of temperature caused by internal waves. The array signal gains show degradation more than 5㏈ by the temporal and spatial variations of temperature and by the down-sloped topography.

• Structural Engineering and Mechanics
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• 제56권3호
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• pp.341-354
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• 2015

The dual-phase lag heat transfer model is employed to study the problem of isotropic generalized thermoelastic medium with internal heat source. The normal mode analysis is used to obtain the exact expressions for displacement components, force stress and temperature distribution. The variations of the considered variables through the horizontal distance are illustrated graphically. The results are discussed and depicted graphically.

• 한국생물환경조절학회:학술대회논문집
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• 한국생물환경조절학회 2000년도 학술발표논문집 ProceedingofBio-Environment control
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• pp.94-97
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• 2000

• 설비공학논문집
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• 제22권1호
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• pp.1-12
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• 2010

An analysis model considered the manufacturing factors and the pellet size has been developed in order to predict the performance characteristics of thermoelectric modules as generators. Since the electrical internal resistance has a significant role in the performance of thermoelectric modules, the variations of electrical internal resistance with operating temperature are experimentally measured. The modified electrical internal resistance calculated from an experimental correlation is applied to the analysis model. To verify the modified analysis model, the output voltage, output current and output power are compared with experimental results for the operating temperature conditions of $T_h=85^{\circ}C$ and ${\Delta}T=40^{\circ}C$. The modified analysis shows a good agreement with the experimental results in terms of the output voltage, current, and power.

• 한국자동차공학회논문집
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• 제10권3호
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• pp.166-175
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• 2002

Tank track rubbers, which undergo dynamic stresses and strains under various road conditions, leads to a result of considerable internal temperature rise due to the heat generation. Since rubber materials are not fully elastic, a part of the mechanical energy is converted into heat because of the hysteresis loss. Heat generation without adequate heat dissipation leads to heat build-up, i.e. internal temperature rise which, if excessive, exerts a bad influence upon the performance and the life of the tank track rubbers. The purpose of this paper is to predict temperature distributions of the rubber components off tank track subjected to complex dynamic loads under various read conditions. In steady state analysis temperature fields are displayed in contour shapes, and in unsteady analysis the temperature variations of some important nodes are represented graphically with respect to the running time of the tank.

• 한국물환경학회지
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• 제31권4호
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• pp.367-376
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• 2015

The momentum and kinetic turbulent energy carried by the wind to a stratified lake lead to basin-scale motions, which provide a major driving force for vertical and horizontal mixing. A three-dimensional (3D) hydrodynamic model was applied to Lake Tahoe, located between California and Nevada, USA, to simulate the dominant basin-scale internal waves in the deep lake. The results demonstrated that the model well represents the temporal and vertical variations of water temperature that allows the internal waves to be energized correctly at the basin scale. Both the model and thermistor chain (TC) data identified the presence of Kelvin modes and Poincare mode internal waves. The lake was weakly stratified during the study period, and produced large amplitude (up to 60 m) of internal oscillations after several wind events and partial upwelling near the southwestern lake. The partial upwelling and followed coastal jets could be an important feature of basin-scale internal waves because they can cause re-suspension and horizontal transport of fine particles from nearshore to offshore. The internal wave dynamics can be also associated with the distributions of water quality variables such as dissolved oxygen and nutrients in the lake. Thus, the basin-scale internal waves and horizontal circulation processes need to be accurately modeled for the correct simulation of the dissolved and particulate contaminants, and biogeochemical processes in the lake.

• JSTS:Journal of Semiconductor Technology and Science
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• 제16권4호
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• pp.528-533
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• 2016

A low voltage high PSRR CMOS Bandgap circuit capable of generating a stable voltage of less than 1 V (0.8 V and 0.5 V) robust to Process, Voltage and Temperature (PVT) variations is proposed. The high PSRR of the circuit is guaranteed by a low-voltage current mode regulator at the central aspect of the bandgap circuitry, which isolates the bandgap voltage from power supply variations and noise. The isolating current mirrors create an internal regulated voltage $V_{reg}$ for the BG core and Op-Amp rather than the VDD. These current mirrors reduce the impact of supply voltage variations. The proposed circuit is implemented in a $0.35{\mu}m$ CMOS technology. The BGR circuit occupies $0.024mm^2$ of the die area and consumes $200{\mu}W$ from a 5 V supply voltage at room temperature. Experimental results demonstrate that the PSRR of the voltage reference achieved -118 dB at frequencies up to 1 kHz and -55 dB at 1 MHz without additional circuits for the curvature compensation. A temperature coefficient of $60 ppm/^{\circ}C$ is obtained in the range of -40 to $120^{\circ}C$.

• 한국수소및신에너지학회논문집
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• 제34권5호
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• pp.514-525
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• 2023

This study conducted numerical simulations with the purpose of analyzing the impact of variations in outlet pressure conditions under extreme temperature conditions on the fluid dynamics and performance of a check valve utilized in hydrogen refueling systems. Under the extreme temperature conditions, changes in outlet pressure conditions of the check valve were investigated to analyze velocity distributions, pressure distributions, and temperature distributions in the operational and connection regions. The analysis results indicated that changes in outlet pressure had a significant influence on the internal temperature variation of the check valve. Furthermore, due to density variations in the connection region caused by the cooling effect of excessively cooled hydrogen, a bias in the primary flow direction towards the lower part of the valve outlet was observed in the outlet area. Through a comparison of the results of the valve's inherent flow performance, represented by the flow coefficient, it was observed that when the pressure difference between the inlet and outlet was below 0.37 MPa, sufficient flow was not ensured.