• Journal of electromagnetic engineering and science
• /
• v.16 no.3
• /
• pp.143-149
• /
• 2016

This work presents a method used for designing a broadband class-E power amplifier that combines the two techniques of a nonlinear shunt capacitance and a low quality factor of a series resonator. The nonlinear shunt capacitance theory accurately extracts the value of class-E components. In addition, the quality factor of the series resonator was considered to obtain a wide bandwidth for the power amplifiers. The purpose of using this method was to produce a simple topology and a high efficiency, which are two outstanding features of a class-E power amplifier. The experimental results show that a design was created using from a 130 to 180 MHz frequency with a bandwidth of 32% and a peak measured power added efficiency of 84.8%. This prototype uses an MRF282SR1 MOSFET transistor at a 3-W output power level. Furthermore, a summary of the experimental results compared with other high-efficiency articles is provided to validate the advantages of this method.

• The KSFM Journal of Fluid Machinery
• /
• v.15 no.5
• /
• pp.37-41
• /
• 2012

High-efficiency and low-noise axial flow fan is developed by combining the FanDAS, a computerized axial fan design/performance analysis system, and CFD software(CFX). Based on fan design requirements, FanDAS conducts 3-D blade geometry design, quasi-3D flow/ performance analyses and noise evaluation by using through-flow analysis method and noise models for discrete frequency and broadband noise sources. Through the parametric studies of fan design variables using FandDAS, preliminary and baseline design is achieved for high efficiency and low noise fan, and then can be coupled with a CFD technique such as the CFX code for constructing final and optimized fan design. The FanDAS-CFX coupled system and its design procedure are applied to actual fan development practice. The FanDAS provides an optimized 3-D fan blade geometry, and its predictions on the performance and the noise level of designed fan are well agreed with actual test results.

• Journal of Power Electronics
• /
• v.6 no.1
• /
• pp.45-51
• /
• 2006

A new high efficiency phase shifted full bridge (PSFB) converter for the power sustaining module of a plasma display panel (PDP) is proposed in this paper. The proposed converter employs a voltage doubler rectifier without an output inductor. Since it has no output inductor, the voltage stresses of the secondary rectifier diodes can be clamped at the output voltage level. No dissipative resistor-capacitor (RC) snubber for rectifier diodes is needed. Therefore, high efficiency, as well as, a low noise output voltage can be realized. Due to the elimination of the large output inductor, it features a simple structure, lower cost, smaller mass and lighter weight. Furthermore, the proposed converter has wide zero voltage switching (ZVS) ranges with low current stresses of the primary switches. Also the resonance between the leakage inductor of the transformer and the capacitor of the voltage doubler cell reduces the current stresses of the rectifier diodes. In this paper, operational principles, an analysis of the proposed converter and experimental results are presented.

• Preventive Nutrition and Food Science
• /
• v.17 no.1
• /
• pp.29-35
• /
• 2012

This study investigated the heat level rating of several varieties of Korean red peppers. The chemical constitution of Korean red pepper samples were as follows: 0.54~290.15 mg% capsaicinoids, 79.22~139.09 ASTA value, and 16.76~29.92% free sugar content. The heat level of the Korean red pepper samples was evaluated by trained panelists and the correlation coefficient and F value (0.001%) of the panelist’s results were determined to be significant. In the principle component analysis (PCA), PC1 (capsaicinoids) and PC2 (free sugar) were shown to represent 31.98% and 25.77% of the total variance, respectively. The results of panelists trained for red pepper heat rating were evaluated using analysis of variance and correlation analysis. The trained panelists showed a high F value (p=0.05) and high correlation coefficient. A high correlation efficient of 0.84~0.93 for the test samples with a 40 Scoville heat unit (32,000 SHU red pepper powder) was reported in the sensory evaluation of the Korean red pepper heat level by a trained panel. However, the panel showed a low correlation efficiency of 0.70 $R^2$ when the 60 SHU test samples were included in the analysis.

• Journal of Korean Port Research
• /
• v.2 no.1
• /
• pp.75-106
• /
• 1988

As port transport system consists of subsystems such as navigation system, cargo handling system, storage system, inland transport system, and Management and Information system, the productivity of this system is determined by the minimum level of subsystem. From the viewpoint of elaborating the efficiency of integrated system, it is valuable to determine the optimal level of harbour tug boat which is the most important factor of navigation system. This paper treats the optimal amount of harbour tug boat by simulation, and applied to Pusan port. In the course of simulation, an emperical formula is introduced for determining the Horse Power (HP) of tug boat by the ship's gross tonnage (G/T) refering to the cases of various ports of other countries, that is ; $Y=9.96X^{0.6}+569$. X : The gross tonnage of vessel (G/T). Y : The Horse Power (HP) of tug boat. The results of the simulation are summarized as follows ; 1) In 1987, three or four low-powered harbour tug boats, five mid-powered harbour tug boats and four high-powered harbour tug boats are necessary in the mean level. But, five or seven low-powered harbour tug boats, ten mid-powered harbour tug boats and eight high-powered harbour tug boats are necessary lest delay should occur at all. 2) In 1992, 1lee or four low-powered harbour tug boats, six mid-powered harbour tug boats and seven high-powered harbour tug boats are estimated and be necessary in the mean level.

• Journal of IKEEE
• /
• v.18 no.4
• /
• pp.586-592
• /
• 2014

In this paper, high efficiency power management IC(PMIC) with DT-CMOS(Dynamic threshold voltage Complementary MOSFET) switching device is presented. PMIC is controlled PWM control method in order to have high power efficiency at high current level. The DT-CMOS switch with low on-resistance is designed to decrease conduction loss. The control parts in Buck converter, that is, PWM control circuit consist of a saw-tooth generator, a band-gap reference(BGR) circuit, an error amplifier, comparator circuit, compensation circuit, and control block. The saw-tooth generator is made to have 1.2MHz oscillation frequency and full range of output swing from supply voltage(3.3V) to ground. The comparator is designed with two stage OP amplifier. And the error amplifier has 70dB DC gain and $64^{\circ}$ phase margin. DC-DC converter, based on current mode PWM control circuits and low on-resistance switching device, achieved the high efficiency nearly 96% at 100mA output current. And Buck converter is designed along LDO in standby mode which fewer than 1mA for high efficiency. Also, this paper proposes two protection circuit in order to ensure the reliability.

• Journal of IKEEE
• /
• v.14 no.2
• /
• pp.90-97
• /
• 2010

The high efficiency power management IC(PMIC) with DTMOS(Dynamic Threshold voltage MOSFET) switching device and DTMOS Error Amplifier is presented in this paper. PMIC is controlled with PWM control method in order to have high power efficiency at high current level. Dynamic Threshold voltage CMOS(DT-CMOS) with low on-resistance is designed to decrease conduction loss. The control parts in Buck converter, that is, PWM control circuits consist of a saw-tooth generator, a band-gap reference circuit, an DT-CMOS error amplifier and a comparator circuit as a block. the proposed DT-CMOS Error Amplifier has 72dB DC gain and 83.5deg phase margin. also Error Amplifier that use DTMOS more than CMOS showed power consumption decrease of about 30%. DC-DC converter, based on Voltage-mode PWM control circuits and low on-resistance switching device is achieved the high efficiency near 96% at 100mA output current. And DC-DC converter is designed with Low Drop Out regulator(LDO regulator) in stand-by mode which fewer than 1mA for high efficiency.

• Journal of Nutrition and Health
• /
• v.22 no.6
• /
• pp.539-546
• /
• 1989

This study was carried out to investigate the effect of addition of cellulose in the diet on the metabolism in rat fed high and low level of zinc. The experimental animals were consisted of 24 male weaning rats of Sprague-Dawley strain(mean weight 72.3g), and they were devided into 4 groups of 6 rats and fed experimental diets for four weeks. Dietary zinc levels used were 10 ppm, and 300ppm and cellulose levels were 2.5% and 10% of diet by weight. Throughout the experimental period, feed consumption and body weight gain were measured and feed efficiency ratio was calculated. The weight of live, kidney and spleen were measured, and the contents of zinc in feces, urine, liver, kidney, spleen and serum were determined. The results obtained are summarized as following ; 1. Body weight gain in high zinc-adequate cellulose group was significantly higher than the other groups. Feed consumptions were significantly higher in high zinc groups and no significant difference was found with dietary cellulose levels. 2. Fecal zinc excretions of four groups were not different at the first week, but at the end of fourth week, high zinc groups experince significantly more zinc excretion than low zinc groups, and also high cellulose groups had higher zinc contents in the feces than the adequate ones within the same zinc levels(p<0.05). There was no significant difference in the urinary zinc excretion. 3. The weights of liver, kidney and spleen were heavier in the high zinc groups than the lower ones, and higher in the high cellulose groups(p<0.05). The liver zinc contents were significantly lower in the low zinc and high cellulose groups. However zinc contents in the kidney and serum were not influenced by dietary zinc level but by cellulouse level. High cellulose diet lowered serum and kidney zinc concentrations(p<0.05).

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.24 no.4
• /
• pp.502-509
• /
• 1995

In other to investigate the hypolipidemic effect of dry edible leaves on serum lipids, four kinds of powdered leaves(persimmom, mulberry, perilla, and soy bean) were added to experimental diets at the levels of 5%(w/w). The diets were fed to 30 male Sprague-Dawley rats, aged 4 weeks and weighing 60$\pm$5g, for 3 weeks. Food intake was the largest in Group 1(control), with 5% of cellulose powder, while food efficiency was the highest in Group 2(persimmon). Total cholesterol level in serum was lower in Group 5(soybean) and Group 4(perilla) than the other groups. In comparison with Group 1, HDL-cholesterol level was very high in Group 4 and atherogenic index was low in Groups 4 and 5. Free cholesterol level was the highest in Group 2, and was the lowest in Group 1. Both LDL and LDL-cholesterol levels were the lowest in Group 1, while they were very high in Groups 2 and 3(mulberry). Triglyceride level was the lowest in Group 4, and the highest in Group 1. Except Group 3, all groups had lower phospholipid level than Group 1. Compared with Group 1, calcium level in serum was low in Groups 3, 4 and 5, magenesium level was low in Groups 2, 3 and 5, phosphate level was high in Group 4, and iron level was exceptionally low in Groups 4 and 5. In conclusion, Group 4(perilla) and Group 5 (soybean) showed a favorable effect in atherogenic index and serum levels of various lipids.

• Preventive Nutrition and Food Science
• /
• v.13 no.2
• /
• pp.71-76
• /
• 2008

This study was performed to examine the effects of onion powder supplementation on lipid metabolism in male SD rats fed a high fat and high cholesterol diet. Experimental groups were control (C), high fat fed group (HF), high fat+onion powder intake (OP), high fat+quercetin intake (Q). The HF diet contained 1% cholesterol, 4% lard, 0.3% Na-taurocholate, and quercetin supplementation level was 0.1 g/kg diet. The OP group showed lower body weight gains compared to the control, while there was no significant difference in food efficiency ratio efficiency. When the proportion of fecal bile acids per total lipids was calculated, there was a significant decrease in the HF group compared to the control group, while the levels of the control group was same as that of the OP group. There was no significant difference between the HF and Q groups in bile acid/total lipid in feces. The amount of total cholesterol in liver increased significantly in HF group compared to the control group, while total cholesterol decreased significantly in the OP group compared to the HF group. There was a significant decrease in GOT (glutamic oxaloacetic transaminase) activity in OP and Q groups compared to the HF group. In conclusion, feeding onion powder to hyperlipidemic rates appeared to control weight gain, significantly lower the level of total cholesterol in the liver, and recover GOT activity. We also demonstrated that onion powder intake was more effective than quercetin intake.