• KOREAN JOURNAL OF CROP SCIENCE
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• v.37 no.1
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• pp.28-36
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• 1992

Fifty rice varieties were tested for alkali digestibility of milled rice grain at four different KOH levels, and twenty-four varieties selected were tested again for alkali digestibility at different degrading times and KOH levels. Gelatinization rate at several heating times and heating temperatures, and water absorption rate at 21$^{\circ}C$ and 77$^{\circ}C$ water temperatures were observed using rice samples of twenty-four varieties to clarify the relationship between alkali digestibility response, gelatinization rate and water absorption rate. Varietal difference of ADV in Japonica and Tongil tye rices was biggest at KOH 1.2%, but it was better to test at KOH 1.2% and 1.4% levels to know the exact alkali digestibility response of rice varieties. Rice varieties tested could be classified into three groups, low, intermediate and high, based on their alkali digestibility response at four KOH levels, and most of Korean cultivated rice varieties were belonged to intermediate or high ADV group. Varietal variation was also found in alkali degrading response at different soaking times in alkali solution. Low ADV varietal group showed higher gelatinization temperature and needed longer heating time for complete gelatinization compared with intermediate or high ADV group. Same trends was found between intermediate and high ADV groups, but varietal variation in the same ADV group was also found in gelatinization temperature and heating time needed for complete gelatinization of rice grain. Water absorption rate of low ADV group was lower than intermediate or high ADV group both at 21$^{\circ}C$ and 77$^{\circ}C$ water temperatures, and intermediate ADV group showed lower absorption rate than high ADV group only in initial water absorption stage at 21$^{\circ}C$.

• Food Science and Preservation
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• v.30 no.6
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• pp.969-982
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• 2023

This study evaluated the impact of blanching pak choi stems and leaves in various solutions (distilled water, 2% NaCl, and 2% citric acid) at 100℃ on their quality characteristics. The highest stem heating loss was observed in the sodium chloride solution (S-NB) at 15.10% (p<0.001), and the highest leaf heating loss was in L-NB at 11.44% (p<0.001). No significant variation was found in the moisture content of both stems and leaves. Relative to the control, the L value (lightness) of the stem decreased while the b value (yellowness) increased (p<0.05). In the leaves, the a value (redness/greenness) and b value increased in L-CB, whereas they decreased in other groups (p<0.05). S-NB exhibited the highest true retention (TR) of total polyphenol content (TPC) in stems (p<0.01) and the highest TR of total flavonoid content (TFC) as well (p<0.001). For leaves, the highest TR of TPC and TFC was in L-WB (p<0.001). In terms of antioxidant activity, S-NB in stems and L-WB in leaves showed the highest scavenging activity measured by DPPH and ABTS⁺ assays (p<0.001). Microorganisms were absent in all pretreatment groups but present in the control. The results suggest that blanching pak choi stems in 2% NaCl solution and leaves in water optimally preserves biologically active compounds and nutrients.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.6
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• pp.155-166
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• 2016

It is important to configure capacitance(C) of the capacitor and the induction coefficient(L) of the work coil on the resonant circuit design stage in order to induce heating on the object by a precise and constant frequency components in the electromagnetic induction heating equipment. Work coil conducts a direct induction heating according to heating point and area of the object which has a fixed heat factor so that work coil is designed to has fixed value. On the other hands, Capacitor should be designed to be changed in order to be the higher the utilization of the entire equipment. It is extracted the samples by variation of single electrode capacity from the selection stage of raw materials for capacity to the stage of process design for output of the high frequency LC resonance of 700kHz on 1000 VAC maximum voltage and current to $200I_{MAX}$. It is suggested fundamental experiment results in order to prove relation for the optimal design of HF-LC resonance conduction-cooled capacitor based on the response of frequency characteristics and results of output parameters according to variation of the capacitance size.

• Journal of the Korean Recycled Construction Resources Institute
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• v.8 no.3
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• pp.325-332
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• 2020

In the safety diagnosis of fire-damaged concrete structures, it is difficult to evaluate the strength and changes in materials due to high temperatures with the existing durability analysis method. In particular, the compressive strength of specimen with different damage levels by thickness is used as a representative value for reducing the compressive strength of the structural member. In this study, a heating experiment was performed with only top face heating and fully heating conditions at 400℃ to 800℃. After heating, splitting tensile test and color analysis were performed to sliced specimens with a thickness of 20mm accompanied by the compressive test of a fully heated specimen. As a result of the experiment, the compressive strength reduction rate calculated from the splitting tensile strength of every sliced specimen appeared to be within 10% of the fully heated specimen on aver age, and the hue value analysis showed consistent color values were observed by red at 400℃-600℃ and gray at 700℃ or above. It follows that the techniques proposed in this study are reasonably assessable to estimate heated temperature and residual compressive strength and damage depth of concrete.

• 한국신재생에너지학회:학술대회논문집
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• 2009.06a
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• pp.451-454
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• 2009

Production and application of biodiesel are expected to grow steadily in the coming years and thus output of its by-product, crude glycerin, will accordingly increase as well. In the present study, gasification of biodiesel by-product as a renewable energy was performed in an entrained flow gasifier to investigate the gasification performance with the operating conditions. Crude glycerin shows a high heating value of 6,000 kcal/kg and low ash and sulphur content. Gasification was conducted in a temperature range of $950\;{\sim}\;1500\;^{\circ}C$. The variation of syngas composition with excess air ratio of 0.17 ~ 0.7 for air or oxygen as a gasification agent was investigated. From the results, syngas heating value, carbon conversion and cold gas efficiency of more than $2500\;kcal/Nm^3$, 95% and 65% were achieved, respectively. The temperature dependency of syngas composition, carbon conversion, and cold gas efficiency shows a similar tendency to excess air ratio at the temperature corresponding to the excess air ratio. The $H_2/CO$ ratio of the product gas was varied from 1.25 to 0.7 with the excess air ratio and this gas composition was favorable for DME synthesis. The optimum excess air ratio for gasification of biodiesel by-product was evaluated to be an approximately 0.35 to 0.4. The present results indicate that crude glycerin can be utilized as a feedstock for gasification to make syngas.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.5
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• pp.535-540
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• 2003

Based on the monthly weather report of Korea Meteorological Administration (KMA) and daily sea surface temperature (SST) data from National Fisheries Research and Development Institute (NFRDl) (1991-2001), mean heat fluxes were estimated at the Gunsan harbor Net heat flux was transported from the air to the sea surface during March to early September, and it amounts to $125\;Wm^{-2}$ in average daily during May to June. During the middle of September to February, the transfer of net heat flux was conversed from the sea surface to the air with $-125\;Wm^{-2}$ in mininum value in October. Short wave radiation was ranged from 50 to $248\;Wm^{-2}$ showing maxima in April to June. Long wave radiation was ranged from 25 to $92\;Wm^{-2}$ with mininum value in June to July. Sensible heat flux denoting negative values in April to August was ranged from -30 to $72\;Wm^{-2}.$ Latent heat flux was ranged from 15 to $82\;Wm^{-2}$ with maxima in August to September. The phase of heat exchange was changed from cooling to heating in the end of February, and from heating to cooling In the beginning of September. The advective term of heat flux showed minima in April to June and maxima in November. The ratio of temperature variations was 1.37 in the sea surface process and the horizontal process by advection. This indicates that the main factor in variation of temperature at Gunsan harbor is the heat exchange process through the sea surface from the air.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.4
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• pp.463-470
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• 2014

Stealth technology of combat aircraft is most significant capability in recent air battlefield. As the detector of IR missiles is being developed, IR stealth capability which is evaluated by IR signature level become more important than it was in previous generation. Among IR signature of aircraft from various sources, aerodynamic heating dominates in long-wavelength IR spectrum of $8{\sim}12{\mu}m$. Skin temperature change by aerodynamic heating which is derived by effects of Mach number and structure. The 4th and 5th generation aircraft are selected for calculation of the skin temperature, and its height and velocity in numerical conditions are 10,000 m and Ma 0.9~1.9 respectively. Aircraft skin temperature is calculated by computing convection of fluid and conduction, convection and radiation of surface. As the aircraft accelerates to higher Mach number, maximum skin temperature increases more rapidly than average temperature and temperature distribution changes in more sharp, interactive ways. The 4th generation aircraft whose shape is more complex than that of the 5th generation aircraft have complicated temperature distribution. On the other hand, the 5th generation aircraft whose shape is relatively simple shows plain temperature distribution and lower skin temperature in terms of both average and maximum value.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.1371-1376
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• 2003

In the thermal power plant, the main steam temperature is typically regulated by the fuel flow rate and the spray flow rate, and the reheater steam temperature is regulated by the gas recirculation flow rate. However, Strictly maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature, the change of the dynamic characteristics in the reheater. Up to the present time, PID Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on tuning of the 2-DOF PID Controller on the DCS for steam temperature control using immune based multiobjective approach. The stable range of a 2-DOF parameter for only this system could be found for the start-up procedure and this parameter could be used for the tuning problem. Therefore tuning technique of multiobjective based on immune network algorithms in this paper can be used effectively in tuning 2-DOF PID controllers.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.885-890
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• 2004

Strictly maintaining the steam temperature can be difficult due to heating value variation to the fuel source, time delay changes in the main steam temperature, the change of the dynamic characteristics in the reheater. Up to the present time, PID Controller has been used to operate this system. However, it is very difficult to achieve an optimal PID gain with no experience, since the gain of the PID controller has to be manually tuned by trial and error. This paper focuses on tuning of the Controller with disturbance rejection for thermal power plant using immune based multiobjective approach. An ITSE(Integral of time weighted squared error) is used to decide performance of tuning results.

• Proceedings of the KSME Conference
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• 2001.06d
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• pp.732-737
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• 2001

The mathematical method was developed and numerical analyses were carried out with various parameters to provide substantial data for optimal design and operation of urban utility systems. The composition of systems and their specifications, such as co-generation system, heat pump system, incineration system and other heating and cooling system could be obtained through these analyses for various resource and energy requirements in urban area. As results the system constituents and operating characteristics, and their economic performances such as the value of objective function, initial and an operating costs were discussed for various load patterns. The effective system design method and the excepted effects of the several unused energy recovery systems were also briefly discussed with the variation of the buildings and facilities species and their capacities.