• Journal of Biosystems Engineering
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• v.11 no.1
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• pp.52-63
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• 1986

This study was performed to find out drying characteristics and develop drying model for the design of an efficient dryer or drying system of red peper. The basic model which describes drying phenomenon of red pepper was firstly established, and drying tests were conducted at 14-different drying conditions. In this test, the effects of drying air temperature and relative humidity on the rate of drying were undertaken. Finally, a new drying model based on these experimental results was developed to describe the drying characteristics of red pepper. The results from this study may be summarized as follows. 1. Drying constant of the basic model established from Lewis' experimental model and diffusion equation was theoretically deduced as a function of moisture content and inner-temperature of red pepper. 2. From the results of drying tests, drying air temperature was found to have the greatest effect on the rate of drying. However, the effect of temperature was small for the condition of high relative humidity, and for low temperature, the effect of relative humidity was found to be large even though the range of relative humidity was low. 3. Modified Henderson equation was found to be better than Chung equation as the EMC model for the estimation of the equilibrium moisture content of red Pepper. 4. Constant-rate drying period did not exist in the red pepper drying test. And falling-rate drying period was divided into three distinct phases. Drying rate was dependent on the moisture content, the inner-temperature of red pepper and the change of physical property due to drying. 5. Drying constant increased with decrease of free moisture content, but it decreased at the end of the drying period. Also, drying constant was dependent on the drying air temperature and relative humidity. 6. The new drying model developed in this study was found to be most suitable in describing the drying characteristics of red pepper. Therefore, it may be concluded that drying time could be accurately estimated by the new drying model.

• Journal of the Korean Data and Information Science Society
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• v.15 no.4
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• pp.935-943
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• 2004

Most of the accelerated life tests deal with tests that use only one accelerating variable and no other explanatory variables. Frequently, however, there is a test to use more than one accelerating or other experimental variables, such as, for examples, a test of capacitors at higher than usual conditions of temperature and voltage, a test of circuit boards at higher than usual conditions of temperature, humidity and voltage. A accelerated life test is extended to M-level stress accelerated life test with k-stress variables. The optimal design for Weibull distribution is studied with k-stress variables.

• Composites Research
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• v.32 no.6
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• pp.382-387
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• 2019

A single frequency strain mode test, a stress relaxation mode test, and a creep test using RH-DMA were performed to investigate the effects of relative humidity and temperature on the viscous properties of PET film. The relative humidity was 10%, 30%, 50%, 70%, and 90%. The temperature was considered to be 30~95℃ for single frequency strain mode tests, 30℃ and 70℃ for stress relaxation mode test, and 5~95℃ for creep test. According to the results, higher relative humidity results in lower storage modulus and loss modulus, but the maximum value of the loss modulus is not significantly affected by changes in relative humidity and is almost constant. Relaxation modulus decreases rapidly at the beginning and becomes constant, and as the temperature increases, it is susceptible to changes in relative humidity. Strain recovery also increases rapidly at the beginning and is susceptible to changes in relative humidity as the temperature increases. In addition, as the temperature increases, the degree of increase in creep compliance increases, and as the temperature rises above the glass transfer temperature, the degree of increase becomes very large. The master curve determined by the time-temperature superposition provides the information to predict the long-term performance under operating conditions such as relative humidity and temperature.

• Journal of the Korea Concrete Institute
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• v.17 no.5 s.89
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• pp.853-856
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• 2005

A low water/cement ratio leads to autogenous shrinkage of cement paste at an early age. This autogenous shrinkage is related to the change of relative humidity in the pore structure that is formed during the hydration process. The relationship between autogenous shrinkage and relative humidity change are relatively well defined today, but the effects of temperature on autogenous shrinkage, relative humidity, and pore structures have been studied less systematically. This study focused on correlating alterations of these properties of cement paste hydrated at constant temperatures of 20, 40, and $60^{\circ}C$. The test results clearly indicate that increasing curing temperature resulted in increased porosity, particularly for pores between 5 to 50 nm as measured by MIP, and increased autogenous shrinkages, as a consequence of a reduction of relative humidity at early ages.

• Korean Journal of Agricultural Science
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• v.35 no.1
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• pp.19-24
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• 2008

A new compressive strength test specimen for linerboard and medium was developed, and tested for its agreement with conventional testing methods such as RCT and STFI. The new specimen enables compressive testing under the changing humidity and temperature. Experimental results showed that the new specimen gave equivalent compressive strengths as the other conventional methods at a constant temperature and humidity. We'll apply the methods under the cyclic humidity and temperature conditions.

• The Korean Journal of Applied Statistics
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• v.22 no.3
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• pp.515-530
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• 2009

Evaporation from surface water bodies is influenced by a number of meteorological parameters. The rate of evaporation is primarily controlled by incoming solar radiation, air and water temperature and wind speed and relative humidity. In the present study, influence of weekly meteorological variables such as air temperature, relative humidity, bright sunshine hours, wind speed, wind velocity, rainfall on rate of evaporation has been examined using 35 years(1971-2005) of meteorological data. Statistical analysis was carried out employing linear regression models. The developed regression models were tested for goodness of fit, multicollinearity along with normality test and constant variance test. These regression models were subsequently validated using the observed and predicted parameter estimates with the meteorological data of the year 2005. Further these models were checked with time order sequence of residual plots to identify the trend of the scatter plot and then new standardized regression models were developed using standardized equations. The highest significant positive correlation was observed between pan evaporation and maximum air temperature. Mean air temperature and wind velocity have highly significant influence on pan evaporation whereas minimum air temperature, relative humidity and wind direction have no such significant influence.

• Journal of the Korea Institute of Building Construction
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• v.4 no.4
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• pp.71-77
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• 2004

Drying Shrinkage has much complexity as it has relations with both internal elements of concrete and external factors. Therefore, experiments on Concrete Drying Shrinkage are carried out in this study under simplified circumstances applying temperature & Humidity test chamber which enables constant temperature and humidity. Comparative analyses have been made respectively according to the consequences aiming at modelling for prediction of Concrete Drying Shrinkage and making out measures to reduce it. Strain Rate of Drying Shrinkage of concrete under the condition of dry air appears to rise by about 20%-30% in proportion as the temperature rises $5^{\circ}C$ when the humidity was held below 10% compared under the condition of dry temperature & Humidity test chamber. Strain Rate of Drying Shrinkage in pit sand concrete increased 20% higher than measured when in river sand under the condition of 90-day material age. A general formula with two variables is derived as follow ${\varepsilon}={\alpha}_1＋{\beta}_1x_1＋{\beta}_2x_2＋{\beta}_3x_1^2＋{\beta}_5x_2^2$. and also graphed in 3 dimensions, enabling to apply to actual design and predict Strain Rate of Drying Shrinkage in concrete. The results of prediction of Rate of Drying Shrinkage by Response Surface Analysis are as follows. The coefficient of correlation of Drying Shrinkage in Concrete was over 90%.

• Journal of Applied Reliability
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• v.18 no.1
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• pp.8-19
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• 2018

Purpose: This study has developed the accelerated lifetime test method for smps for outdoor lighting LED through two factors of temperature and humidity. Methods: Acceleration condition was confirmed for each stress and model, and acceleration life test model was estimated according to acceleration condition. Results: As a result of confirming the accelerated life test model, in the case of humidity, acceleration was established only in the foreign products. Therefore, it is confirmed that the acceleration condition is insufficient. However, the estimated parameters for temperature are relatively constant. It is therefore suitable for power supply acceleration tests for outdoor lighting LEDs. Conclusion: The SMPS acceleration test for outdoor lighting LED can improve the availability of the product by developing an accelerated life test method that guarantees the reliability of the product.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.26 no.1
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• pp.146-152
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• 2022

Information collected from temperature, humidity, inclination, and pressure sensors using Raspberry Pi or Arduino is used in automatic constant temperature and constant humidity systems. In addition, by using it in the agricultural and livestock industry to remotely control the system with only a smartphone, workers in the agricultural and livestock industry can use it conveniently. In general, temperature and humidity are expressed in a line graph, etc., and the change is monitored in real time. The technology to visually express the temperature has recently been used intuitively by using an infrared device to test the fever of Corona 19. In this paper, the information collected from the Raspberry Pi and the DHT11 sensor is used to predict the temperature change in space through intuitive visualization and to make a immediate response. To this end, an algorithm was created to effectively visualize temperature and humidity, and data representation is possible even if some sensors are defective.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.9
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• pp.608-613
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• 2008

The purpose of the present paper is to investigate the effect of outdoor weather conditions on the performance of a heat recovery ventilator. Experiments have been performed by varying outdoor temperature/humidity conditions with the indoor conditions fixed at the standard conditions by KARSE. Results indicate humidity efficiency shows larger uncertainties than temperature efficiency in general. With the heat generation by an internal fan removed, the modified temperature efficiency remains almost constant regardless of the indoor-outdoor temperature difference. The enthalpy efficiency can have very large or negative values in case the outdoor conditions are in the vicinity of the indoor enthalpy line. The direction of heat flow, in such a case, can be opposite to that of moisture flow between two air streams. Discussions are included about various interesting features of the psychrometric processes taking place in a heat recovery ventilator.