• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.20 no.8
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• pp.534-540
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• 2008

In this paper, the optimal bang-bang control problem of an air-conditioning system with slab thermal storage was formulated by gradient method. Furthermore, the numeric solution obtained by gradient method algorithm was compared with the analytic solution obtained on the basis of maximum principle. The control variable is changed uncontinuously at the start time of thermal storage operation in an analytic solution. On the other hand, it is showed as a continuous solution in a numeric solution. The numeric solution reproduces the analytic solution when a tolerance for convergence is applied severely. It is conceivable that gradient method is effective in the analysis of the optimal bang-bang control of the large-scale system like an air-conditioning system with slab thermal storage.

• Food Quality and Culture
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• v.3 no.2
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• pp.89-93
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• 2009

This study was conducted to investigate the effects of herbs (dill weed, fennel seed and rosemary) on color stability and lipid oxidation of ground pork patties during storage at $2^{\circ}C$ and $-20^{\circ}C$. Lipid oxidation was determined by the thiobarbituric acid reactive substances (TBARS) method. Fennel seed was identified as being the most effective ingredient in terms of meat redness (Hunter a-values) during storage at $2^{\circ}C$ (p<0.05). Patties treated with rosemary had lower Hunter a-values than control, and dill weed was the least beneficial in influencing meat redness, having significantly lower a-values than control patties. During frozen storage at $-20^{\circ}C$, no significant differences in a-values were observed between the control patties and those treated with fennel seed. Patties treated with rosemary had lower a-values than control and patties with dill weed had negative a-values throughout storage. The cooking process increased Hunter L-values and decreased a-values in all patty samples. TBARS values increased during storage. Rosemary displayed excellent antioxidative activity as evidenced by the completely inhibition of TBARS formation of cooked pork patties. Dill weed and fennel seed also exerted an intermediate but significant antioxidant effect during storage (p<0.05).

• Korean journal of food and cookery science
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• v.26 no.6
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• pp.821-830
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• 2010

This study was carried out to investigate the quality characteristics and storage of wet noodle with added Cheonnyuncho powder. Wet noodles were prepared at concentration of 1, 3, and 5%(w/w) of the fruit based on flour weight. Moisture content of the noodles with or without Cheonnyuncho powder was 34~36%. Ca, K, Mg, Fe, Mn and Zn contents of Cheonnyuncho noodle were increased at increasing concentrations of Cheonnyuncho powder. Cooked weight, volume, and water absorption decreased with increased fruit powder, whereas turbidity increased. For hunter's color values of noodles, L(lightness) and b(yellowness) values decreased with increasing concentration of Cheonnyuncho powder, whereas a(redness) value increased. For mechanical characteristics of the noodles, adhesiveness, cohesiveness, chewiness, elasticity, and brittleness of cooked noodle with Cheonnyuncho powder were lower than those of control. The pH of Cheonnyuncho noodle was lower than that of control during storage. Bacterial counts of wet noodle with 1% and 3% fruit powders were lower than those of the control and 5% fruit powder on the 8th day of storage at $5^{\circ}C$. From the sensory evaluation, texture, taste, and overall preference were not significantly different between the control and fruit group, but the color of 5% Cheonnyuncho noodle was significantly higher than that of control (p<0.05). In conclusion, the results of this study suggest that the addition of 1% and 3% Cheonnyuncho powder in combination with flour tended to improve antimicrobial effects during storage when compared to control.

• Journal of the East Asian Society of Dietary Life
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• v.10 no.5
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• pp.425-430
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• 2000

Physicochemical properties of Kochujang(OK) added onion powder (OK ) were Investigated duringstorage at 20"C The pH value of Kochujang tended to decrease by condition of storage. Initial pH value of OK was significantly lower than that of control, but the difference of pH value was getting smaller during the storage period. In the Process of 90 days storage period, the pH value of OK containing 8 and 10% of onion powder was higher than control. Salt content was lower in OK than in control as the onion content was higher No changes in salt content were observed during the storage process. Reducing sugar was higher in OK than in control, and Its concentration was increased with onion content. Amino acid nitrogen content which was slightly higher in OK than in control increased during 45 days of storage period and tended to decrease afterward. In the sensory attribute data of Kochujang after 3 months of storage period, OK had higher scores in sweetness, color, flavor, and overall acceptability than control, especially the OK with 10% onion powder had the highest scores.scores.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.3
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• pp.338-342
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• 2014

Energy storage is a key issue when integrating large amounts of intermittent and non-dispatchable renewable energy sources into electric power systems. To maintain the instantaneous power balance and to compensate for the influence of power fluctuations from renewable sources, flexible capability for power control is needed. Adjustable Speed Pumped Storage Power Generator is pumped storage unit that is adjustable for pump output adjustments as well as the highest efficiency operations because it has fast response time. In this paper we address the adjustable speed pumped storage power generator for frequency control against the intermittence of wind turbine output and calculate the appropriate capacity of adjustable speed pumped storage power generator.

• Journal of Biosystems Engineering
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• v.39 no.3
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• pp.194-204
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• 2014

Purpose: The aim of this study was to develop long-term storage technology for Chinese cabbage in order to extend the period of availability of freshly harvested products. The scope of the paper deals with the use of a cooler with a remote monitoring and control interface in conjunction with use of packaging film. Methods: A cooler with a real time monitoring system was designed as a low-temperature storage facility to control temperature and relative humidity (RH). The effects of storage in high-density polyethylene (HDPE) plastic boxes, 3% chitosan dipping solution, polypropylene film (PEF) with perforations, and mesh packaging bags on physiological responses were investigated. The optimal storage temperature and humidity for 120 days were below $0.5^{\circ}C$ and 90%, respectively. Physiological and biochemical features of cabbage quality were also analyzed: weight loss, texture, and sugar salinity, chlorophyll, reducing sugar, and vitamin C contents. Results: The cooler with a remote monitoring and control interface could be operated by an HMI program. A $0.5^{\circ}C$ temperature and 90% humidity could be remotely controlled within the cooler for 120 days. Postharvest freshness of Chinese cabbages could be maintained up to 120 days depending on the packaging method and operation of the remote monitoring system. In particular, wrapping the cabbages in PEF with perforations resulted in a less than a 5% deterioration in quality. This study provides evidence for efficient performance of plastic films in minimizing post-harvest deterioration and maintaining overall quality of cabbages stored under precise low-temperature conditions with remote monitoring and a control interface. Conclusions: Packaging with a modified plastic film and storage in a precisely controlled cooler with a remote monitoring and control interface could slow down the physiological factors that cause adverse quality changes and thereby increase the shelf life of Chinese cabbage.

• Transactions of the Korean Society of Automotive Engineers
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• v.23 no.4
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• pp.428-435
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• 2015

This paper presents the experimental study of cabin thermal comfort using a cold storage heat exchanger in a vehicle air-conditioning system. Recent vehicle-applied ISG functions for fuel economy and emission, but when vehicles stop, compressors in the air-conditioning system stop, and the cabin temperature sharply increases, making passengers feel thermal discomfort. This study conducts thermal comfort evaluation in the vehicle, which is applied to a cold storage system for the climate control wind tunnel test and the vehicle fleet road test with various airflow volume rates and ambient temperatures blowing to the cold storage heat exchanger. The experimental results, in the cold storage system, air discharge temperature is $3.1-4.2^{\circ}C$ lower than current air-conditioning system when the compressor stops and provides cold air for at least 38 extra seconds. In addition, the blowing airflow volume to the cold storage heat exchanger with various ambient temperature was examined for the control logic of the cold storage system, and in the results, the airflow volume rate is dominant over the outside temperature. For this study, a cold storage system is economically useful to keep the cabin at a thermally comfortable level during the short period when the engine stops in ISG vehicles.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.6
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• pp.820-827
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• 2014

Since a microgrid has renewable energy sources, imbalance between power supply and power demand occurs in the islanded mode. In order to solve the imbalance, several energy storage systems (ESSs) such as bettary energy storage system (BESS), EDLC (electric double layer capacitor), flywheel, and SMES (superconducting magnetic energy storage) are generally used. Especially, their electrical characteristics are different. For efficient use of them, a coordinated control scheme is required. In this paper, a coordinated control scheme for using a Lead-acid BESS, a Lithium BESS, and a EDLC is designed to efficient frequency control for a microgrid in the islanded mode. The coordinated frequency control strategy is designed based on their electrical characteristics. The feasibility of the proposed coordinated frequency control strategy is verified through the simulation.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2134-2141
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• 2014

This paper addresses on a wind power system with BESS(Battery Energy Storage System). The concerned system consists of four parts: the wind speed production model, the wind turbine model, configure capacity of the battery energy storage, battery model and control of the BESS. First of all, we produce wind speed by 4-component composite wind speed model. Secondly, the maximum available wind power is determined by analyzing the produced wind speed and the characteristic curve of wind power. Thirdly, we configure capacity of the BESS according to wind speed and characteristic curve of wind speed-power. Then, we propose a control strategy to track the power reference. Finally, some simulations have been demonstrated to visualize the feasibility of the proposed methodology.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1359-1361
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• 2003

This paper describes a remote monitoring system of temperature control for cold-storage of farm produce. In cold-storage, it is important that farm produces are stored as fresh. Unfortunately, when an operator goes out from the cold-storage, the temperature could be changed due to the various reasons, for an example, a valve of cooler is broken. The temperature change results in a serious problem of the quality of farm produce. To prevent the problem, the operator has to look to the current state of the temperature of the cold-storage, even he is in long away. Thus, the monitoring system to show the temperature is required to the operator who can move away. Therefore, this paper describes the remote monitoring system of the temperature. The proposed system is expected to help the operator's facilities, and the management of farm produce.