• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.229-235
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• 2011

This research aims todevelopa compression/absorption hybrid heat pump system using an $NH_3/H_2O$ as working fluid.The heatpump cycle is based on a combination of compression and absorption cycles. The cycle consists of two-stage compressors, absorbers, a desorber, a desuperheater, solution heat exchangers, a solution pump, a rectifier, and a liquid/vapor separator. The compression/absorption hybrid heat pump was designed to produce hot water above $90^{\circ}C$ using high-temperature glide during a two-phase heat transfer. Distinct characteristics of the nonlinear temperature profile should be considered to maximize the performance of the absorber. In this study, the performance of the absorber was investigated depending on the capacity, shape, and arrangementof the plate heat exchangers with regard tothe concentration and distribution at the inlet of the absorber.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.1
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• pp.53-60
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• 2011

In this study, an organic Rankine-cycle system using HFC-134a, which is a power cycle corresponding to a low-temperature heat source, such as that for geothermal power generation, was investigated from the view point of power optimization. In contrast to conventional approaches, the heat transfer and pressure drop characteristics of the working fluid within the heat exchangers were taken into account by using a discretized heat exchanger model. The inlet flow rates and temperatures of both the heat source and the heat sink were fixed. The total heat transfer area was fixed, whereas the heat-exchanger areas of the evaporator and the condenser were allocated to maximize the power output. The power was optimized on the basis of three design parameters. The optimal combination of parameters that can maximize power output was determined on the basis of the results of the study. The results also indicate that the evaporation process has to be optimized to increase the power output.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1367-1373
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• 2011

This research concerns the development of a compression/absorption high-temperature hybrid heat pump that uses a natural refrigerant mixture. Heat pumps based on the compression/absorption cycle offer various advantages over conventional heat pumps based on the vapor compression cycle, such as large temperature glide, temperature lift, flexible operating range, and capacity control. In this study, a lab-scale prototype hybrid heat pump was constructed with a two-stage compressor, absorber, desorber, desuperheater, solution heat exchanger, solution pump, liquid/vapor separator, and rectifier as the main components. The hybrid heat pump system operated at 10-kW-class heating capacity producing hot water whose temperature was more than $90^{\circ}C$ when the heat source and sink temperatures were $50^{\circ}C$. Experiments with various $NH_3/H_2O$ mass fractions and compressor/pump circulation ratios were performed on the system. From the study, the system performance was optimized at a specific $NH_3$ concentration.

• Korean Journal of Medicinal Crop Science
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• v.7 no.4
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• pp.288-295
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• 1999

This experiment was conducted to evaluate the appropriate nutrient solution for hydroponics in Angelica keiskei. The nutrient solutions used were Korean solution, Yamazaki solution, Netherlands solution and open field cultivation. The highest yield of Angelica keiskei was 4, 542kg/10a at Netherlands solution. 'The yield at Netherlands solution was increased about 139 percent, compared to that at open field cultivation. The highest germanium contents was 0. 35ppm at Korean solution. The contents increased 40 percent at Korean solution compare to that at open field cultivation.

• Applied Biological Chemistry
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• v.34 no.4
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• pp.373-378
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• 1991

The skin and fleshy substance on the net fiber of sponge-gourd fruit pressed mechanically was removed with 0.2% NaOH solution in $3{\sim}5$ hours. The treatment of 0.2% NaOH with 0.02% Monopol(non-ionogenic polyoxethylen derivative) as surfactnat and with 0.1% $Ca(OCl)_2$ as bleaching agent enhanced the effect to remove the fleshy substance and improve the quality of net fiber. Also, the wet hardness and tensile strength of net fiber were controlled by the crosslinkage of the fiber with glu tardialdehyde, glyoxal, and formalin, respectively. The net fiber was stable on the acid and alkaline solutions. Also the range of temperature to degradate the fiber was $338{\sim}385^{\circ}C$. These values indicated a fair stability. The improved net fiber can be used for raw material of bath, dish washing, oil and gas filter, and many kinds of decorations.

• Journal of Food Hygiene and Safety
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• v.23 no.4
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• pp.297-303
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• 2008

Naringin, major citrus flavonoids, has been identified to exert antioxidative, antidiabetic, and lipid lowering effects. In this study, we examined the effect of 0.2 g/kg, 0.5 g/kg naringin supplementation for 3 times/week for 5 weeks on lipid metabolism and antithrombotic capacity in rat. Eighteen five week-old Sprague Dawley(SD) female rats, which had initial body weights of $246{\pm}9g$, were randomly divided into three groups: Control (non naringin group); Low (0.2 g/kg naringin-supplemented group); High (0.5 g/kg naringin-supplemented group). Three groups of rats were supplemented with three experimental diets for 5 weeks and we investigated antithrombotic capacity before sacrifice. Naringin did not significantly alter the body weight gain, relative organ weight. However, the level of serum triglyceride, serum free fatty acid, serum total lipid and serum glucose levels were significantly lowered compared to those of control. The high group (0.5 g/kg naringin-supplemented group) was showed significantly increased bleeding time compared to control group. These results suggest that naringin supplemental diets reduces the level of hypertension, glycosuria and fatness on the female SD rats, when orally administered below the dosage 0.5 g/kg for 5 weeks.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.2
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• pp.78-84
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• 1993

In order to know the effect of sludge from water treatment plants un agricultural environment, an experiment of water treatment sludge application for Altari radish (Raphanus sativus L.) was carried out. And the results were as follows ; 1. The pH of water treatment sludge was 7.2, which was higher than that of the experimental soil. The exchangeable Ca content in the sludge was very high being 29me/100g sludge. So when the sludge was applied to the soil, amending effect for soil acidity was supposed. 2. With the application of the water treatment sludge to the soil, soil pH and organic matter content were increased. With the increase of the level of sludge application, contents of crude fiber and Ca in Altari radish were increased, white those of P and Mg tended to decrease. 3. The length of the root and the amount of fresh yield of the whole plant of radish tended to increase with the increase of sludge application, and this tendency was more evident on the infertile soil. From the above results, it was concluded that the fresh yield of Altari radish increased up to 75ton/ha sludge application on the fertile soil, but the yield decreased when higher levels of sludge was applied. While on the infertile soil, the yield increased up to the application of 300ton/ha, and the heavier application level did not adversely affect the yield of Altari radish.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.145-149
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• 1996

Depending on compost treatment the changes of radish morphology and soil physico-chemical properties were investigated in the sandy loam soil, pH of the soil was decreased and the contents of organic matter, total nitrogen, phosphate and cation exchange capacity was increased with increase of compost. Root weight and length were the lowest, but deficit rate was the highest(79.3%) in the treatment of 120Mg/ha of compost. The contents of chlorophyll and sugars were increased with increasing the amount of compost treatment, but the inorganics were scarcely changed. The nitrate content in radish root ranged from 10 to 120mg/kg in various treatments.

• Journal of Veterinary Clinics
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• v.31 no.3
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• pp.175-179
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• 2014

The purpose of this study was to determine and compare prostate size using ultrasound and computed tomography (CT). The prostate gland was evaluated in eight normal Beagle dogs. Length, depth, and width of the prostate gland were measured by ultrasound and volume of the prostate was obtained from the two ellipsoid formula (US1, US2). Height, length, width, area, and volume of the prostate gland were measured by CT. Ratios of prostatic height, length, and width to the sixth lumbar vertebral body length were calculated. There was no significant difference between the US1 and US2 method, and between US2 and CT method, respectively. The prostatic volume calculated by US1 method was significantly lower than those with CT (p=0.029). The Upper limits of ratios of prostate length, height, and width to the length of the sixth lumbar vertebra were 1.3, 1.1, and 1.7, respectively. Among these prostate dimensions, prostate length and height could be a useful index in estimating prostate size regardless of body weight.

• Journal of IKEEE
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• v.16 no.1
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• pp.28-33
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• 2012

Recently, with mobile devices increasing, as a variety of multimedia functions are needed, battery life is decreased. Accordingly the methods for extending the battery life has been proposed. In order to implement these methods, we have to know exactly the status of the battery, so we need a high resolution analog to digital converter(ADC). In case of the existing integrating sigma-delta ADC, it have not convert reset-time conversion cycle to function of resolution. Because of this reason, all digital values corresponding to the all number of bits will not be able to be expressed. To compensated this drawback, this paper propose that all digital values corresponding to the number of bits can be expressed without having to convert reset-time additional conversion cycle to function of resolution by using a up-down counter. The proposed circuit achieves improved SNDR compared to conventional converters simulation result. Also, this was designed for low power suitable for battery management systems and fabricated in 0.35um process.