• Title, Summary, Keyword: freezing time prediction

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Studies on the Freezing Time Prediction and Factors Influencing Freezing Time Prediction (식품의 동결시간 예측 및 동결시간에 영향을 미치는 요인에 관한 연구)

  • Kong, Jai-Yul;Jeong, Jin-Woong;Kim, Min-Young
    • Korean Journal of Food Science and Technology
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    • v.20 no.6
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    • pp.827-833
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    • 1988
  • The objectives of this investigation were to develop an improved analytical method and to review with respect to experimental parameters and thermo-physical properties influencing the freezing time prediction. The results indicate that the relationship between freezing time and product size is dependent on the surface heat transfer coefficient. As the magnitude of surface heat transfer coefficient decreases, the influence of product size on freezing time becomes more profound. But the freezing time does decrease slightly as the coefficients are increased to values greater than 150 $w/m^2^{\circ}C$. In addition, influence of thermo-physical properties on the freezing time prediction shown generally density, water content, specific heat and thermal conductivity, in order of % difference. Multiple linear regression equation for freezing time prediction were obtained with respect to 4 different food materials with varying thickness.

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Studies on the Freezing Time Prediction of Foodstuffs by Plank's Equation of Modification (Plank's Equation의 변형에 의한 식품의 동결시간 예측)

  • Cheong, Jin-Woo;Kong, Jai-Yul
    • Korean Journal of Food Science and Technology
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    • v.20 no.2
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    • pp.280-286
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    • 1988
  • Freezing is becoming incressingly important in the food industry as a means of food preservation since the turn of the century. For quality, processing and economic reasons, it is important to predict the freezing time for foods. A number of models have been proposed to predict freezing time. However, most analytical freezing time prediction techniques apply only to specific freezing conditions. Therefore, it is necessary to develop an improved analytical method for freezing time prediction under various conditions. The objectives of this study, by reviewing previous experimental data obtained by uncertain freezing condition and thermo-physical data, were to develop simple and accurate analytical method for prediction freezing time, and to obtain the freezing time of various foodstuffs by still air freezing and immersion freezing method. The result of this study showed that the proposed method offered better results than the other complex method compared.

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Prediction of Freezing Time for Peeled Chestnut using Finite Difference Method (유한차분법을 이용한 깐밤의 동결시간 예측)

  • Lee, Choong-Ho;Kim, Jong-Hoon
    • Journal of Biosystems Engineering
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    • v.33 no.1
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    • pp.21-29
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    • 2008
  • In this study, the thermal properties of peeled chestnuts were measured, and the mathematical prediction model of freezing time was also developed for various interior positions from center to rind (surface). The measured thermal properties were showed that heat conductivity is $0.43W/m^{\circ}C$, specific heat is $2.7206J/m^3^{\circ}C$, latent heat is $216.9{\times}10^6J/m^3$ and freezing point is $-2.8^{\circ}C$. The entire process about reaching to the freezing time of peeled chestnuts was analyzed with its each regular depth position using the finite difference method (FDM) based on computer simulation. In case of regular freezing temperature, it was showed an that surface (rind) position is more rapidly reached into the freezing point rather than the center position, and also reaching time to the freezing point is more fast at the lower freezing temperature. Comparison results between simulation and experiments showed linear relationship. In regularly varying condition for freezing temperature, this method would give an information to predict a freezing time of the interior points for peeled chestnuts and more similar agricultural products.

Measurement of the Surface Heat Transfer Coefficients for Freezing Time Prediction of Foodstuffs (식품의 동결시간 예측을 위한 표면열전달계수 측정)

  • Jeong, Jin-Woong;Kong, Jai-Yul;Kim, Min-Yong
    • Korean Journal of Food Science and Technology
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    • v.21 no.6
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    • pp.735-741
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    • 1989
  • For the accurate prediction of freezing time, probably the most difficult factor to measure and major error source is the surface heat transfer coefficient. In this work, surface heat transfer coefficient were determined for still air freezing and immersion freezing methods by theory of the transient temperature method and confirmed by using a modification of plank's equation to predict the freezing time of ground lean beef. The results showed the cooling rate of immersion freezing was about 11 times faster than that of still air freezing method. A comparison of surface heat transfer coefficient of copper plate and ground lean beef resulted an difference of 25-30% because the food sample surface is not smooth as copper plate. Also, when h-values measured by ground lean beef were applicated to modified model, the accuracy of its results is very high as difference of about 8%.

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Development of Freezing Time Prediction Model and Thermo-physical Properties of Frozen Kimchi (김치 동결시의 물리적 특성 및 동결시간 예측 모델 개발)

  • 정진웅;김병삼;김종훈
    • Korean Journal of Food Preservation
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    • v.10 no.2
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    • pp.125-130
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    • 2003
  • This study was carried out to investigate the thermo-physical properties and design Freezing time prediction model from data of freezing test of Kimchi. Density of Kimchi were measured as 1001.9 ${\pm}$0.03 kg/㎥ at unfrozen state, 987.0 ${\pm}$0.07 kg/㎥ at frozen state and volume of the Kimchi expanded 4.67% at -l5$^{\circ}C$. Initial freezing point of Kimchi and seasoning were -4.0$^{\circ}C$ and -2.5$^{\circ}C$, respectively. Freezing ratio of Kimchi were estimated more than 50% at -5.0$^{\circ}C$, more than 75% at -l0$^{\circ}C$ and approximately 90% at -25$^{\circ}C$. To obtain equation for freezing time prediction of Kimchi, freezing time(Y) was regressed against the reciprocal( $X_3$) of difference of initial freezing point and freezing medium temperature, reciprocal( $X_4$) of surface heat transfer coefficient, the initial temperature( $X_1$) and thickness( $X_2$) of samples. As results of the multiple regression analysis, equations were obtained as follows. Y$_{kimchi}$=3.856 $X_1$+13982.8 $X_2$+8305.166 $X_3$+ 3559.181 $X_4$-639.189( $R^2$=0.9632). These equations shown better results than previous models, and the accuracy of its was very high as average absolute difference of about 10% in the difference between the fitted and experimental results.

Freezing Time Prediction of Foods by Multiple Regression Analysis (다중회귀분석에 의한 식품의 동결시간 예측)

  • Jeong, Jin-Woong;Kim, Jong-Hoon;Park, Noh-Hyun;Lee, Seung-Hyun;Kim, Young-Dong
    • Korean Journal of Food Science and Technology
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    • v.30 no.2
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    • pp.341-347
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    • 1998
  • To develop simple and accurate analytical method for freezing time prediction of beef and tylose under various freezing conditions, freezing time (Y) was regressed against the reciprocal $(X_3)$ of difference of initial freezing point and freezing medium temperature, reciprocal $(X_4)$ of surface heat transfer coefficient, the initial temperature $(X_1)$ and thickness $(X_2)$ of samples which should cover most situations arising in frozen food industry. As results of the multiple regression analysis, equations were obtained as follows. $Y_{tylose}=3.45X_1+7642.84X_2+4642.67X_3+2946.89X_4-431.33\;(R^2=0.9568)$ and $Y_{beef}=0.68X_1+7568.98X_2+2430.78X_3+3293.26X_4-299.00\;(R^2=0.9897)$. These equations offered better results than Plank, Nagaoka and Pham's models, shown in satisfactory agreement with models of Cleland & Earle and Hung & Thompson when were compared to previous models, and the accuracy of its was very high as average absolute difference of about 10% in the difference between the fitted and experimental results. Also, thermal diffusivities of beef and tylose were measured as $4.43{\times}10^{-4}m^2/hr$ and $4.39{\times}10^{-4}m^2/hr$ at $6{\sim}7^{\circ}C$, $2.42{\times}10^{-3}m^2/hr$ and $3.32{\times}10^{-3}m^2/hr$ at $-10{\sim}-12^{\circ}C$. Initial freezing points of beef and tylose were $-1.2^{\circ}C\;and\;-0.6^{\circ}C$, respectively. Surface heat transfer coefficients were estimated $20.57\;W/m^2^{\circ}C$ with no-packing, $16.11\;W/m^2^{\circ}C$ with wrap packing and $13.07\;W/m^2^{\circ}C$ with Al-foil packing, and the cooling rate of immersion freezing method was about 10 times faster than that of air blast freezing method.

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Case Studies on Freezing Rain over the Korean Peninsula Using KLAPS (KLAPS를 이용한 한반도 어는비 사례 연구)

  • Kwon, Hui-Nae;Byun, Hi-Ryong;Park, Chang-Kyun
    • Atmosphere
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    • v.25 no.3
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    • pp.389-405
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    • 2015
  • In this study, the occurrence circumstances of 3 cases (12 Jan 2006, 11 Jan 2008, 22 Feb 2009) when the freezing rain was observed at more than two observatories in a day with more than three times each observatory, were investigated. Following the advanced study about the same cases, we have tried to find more delicate differences in using the Korea Local Analysis and Prediction System (KLAPS; 5 km reanalysis data) that has the smallest grid scale at current situation. As results, three common characteristics are found: (1) Just before the occurrence of the freezing rain, the wind direction was consistently continuous and the wind speed was constant or gradually increased for at least 3 hr more. (2) Surface air temperature (Relative humidity) was respectively $3.08^{\circ}C$ (28.76%), $0.47^{\circ}C$ (50.07%) and $-3.60^{\circ}C$ (71.07%) 3 hr ago to break out the freezing rain. It means the freezing rain occurs in a wide range of atmospheric environments. However, the closer it got to the occurrence time of the freezing rain, the closer the surface air temperature was to $0^{\circ}C$, and the bigger the humidity of the surface air was. (3) The liquid precipitation formed in the upper atmosphere, met a cold advection bellower than 950 hPa level and suspected to be changed to the super-cooled condition.

The Service Life Prediction of Concrete with Crushed Sand in Condition of Freezing and Thawing (동결융해작용을 받는 부순모래 콘크리트의 수명예측)

  • Kang, Su-Tae;Ryu, Gum-Sung;Park, Jung-Jun;Lee, Jang-Hwa;Koh, Kyung-Taek
    • Proceedings of the Korea Concrete Institute Conference
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    • pp.739-742
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    • 2005
  • In this study, we predicted the service life against the freezing and thawing. as a result, we found that in the case of using the low quality crushed sand with high water-cement ratio, there is the possibility of deterioration. but in any other case, we concluded that there is no chance to deteriorate if we have the required air contents by using AE agent. we are going to improve the method to evaluate more exactly the durability of the concrete with crushed sand by acquiring data from the specimen which are exposed to field for long time.

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Study on the Development of Road Icing Forecast and Snow Detection System Using State Evaluation Algorithm of Multi Sensoring Method (복합 센서의 상태 판정 알고리즘을 적용한 노면결빙 예측 및 강설 감지 시스템 개발에 관한 연구)

  • Kim, Jong-Woo;Jung, Young-Woo;Nam, Jin-Won
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.17 no.5
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    • pp.113-121
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    • 2013
  • The road icing forecast and snow detection system using state evaluation algorithm of multi sensor optimizes snow melting system to control spread time and amount of chemical spread application This system operates integrated of contact/non-contact sensor and infrared camera. The state evaluation algorithm of the system evaluates road freezing danger condition and snowfall condition (snowfall intensity also) using acquired data such as temperature/humidity, moisture detection and result of image signal processing from field video footage. In the field experiment, it proved excellent and reliable evaluated result of snowfall state detection rate of 89% and wet state detection rate of 94%.