• Preventive Nutrition and Food Science
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• v.10 no.1
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• pp.58-63
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• 2005

Commonly used spices in Korean cooking (red pepper powder, garlic, ginger) were evaluated for anti-obesity properties and effects on triglyceride (TG) and cholesterol in blood and adipose tissues in rats fed a high fat (20%) diet. SD rats were raised for four weeks on either a normal diet (ND, based on the AIN-93M diet), high fat diet (HFD, supplemented with 16% lard oil in the ND), or diets containing 5% red pepper powder (RPP), garlic or ginger. These spices significantly decreased weight gain compared to HFD, but garlic and ginger showed a greater effect on reducing weight gain than RPP. The weights of liver and epididymal and perirenal fat pads in garlic and ginger diet groups were lower than those of the HFD groups (p < 0.05). The garlic and ginger also decreased triglyceride and cholesterol contents in liver and epididymal and perirenal fat pad, reversing the higher levels seen in HFD. RPP, garlic and ginger supplemented diets were effective in lowering serum triglyceride and cholesterol levels (p< 0.05). These results indicated that garlic and ginger more effectively suppressed the effects of HFD on body fat gain and lipid values of adipose tissues and serum than RPP.

• ETRI Journal
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• v.16 no.4
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• pp.1-11
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• 1995

A GaAs power metal semiconductor field effect transistor (MESFET) operating at a voltage as low as 3.3V has been developed with the best performance for digital handheld phone. The device has been fabricated on an epitaxial layer with a low-high doped structure grown by molecular beam epitaxy. The MESFET, fabricated using $0.8{\mu}m$ design rule, showed a maximum drain current density of 330 mA/mm at $V_{gs}$ =0.5V and a gate-to-drain breakdown volt-age of 28 V. The MESFET tested at a 3.3 V drain bias and a 900 MHz operation frequency displayed an output power of 32.5-dBm and a power added efficiency of 68%. The associate power gain at 20 dBm input power and the linear gain were 12.5dB and 16.5dB, respectively. Two tone testing measured at 900.00MHz and 900.03MHz showed that a third-order intercept point is 49.5 dBm. The power MESFET developed in this work is expected to be useful as a power amplifying device for digital hand-held phone because the high linear gain can deliver a high power added efficiency in the linear operation region of output power and the high third-order intercept point can reduce the third-order intermodulation.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.11
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• pp.555-561
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• 2001

In this paper, the low power (1.5 W) solenoid-type magnetic thin-film transformers utilizing a $Ni_{81}Fe_{19)$ core material were designed and fabricated for 5 MHz-drive DC-DC converter application. The $20\mum$ thick copper films were used as the coils. The transformers fabricated in this work have the sizes of $3.08 mm\times25.5 mm\; and\; 6.15 mm\times12.75 mm.$ The optimum design of solenoid-type magnetic thin film transformers was performed utilizing the conventional equations, a Maxwell computer simulator (Ansoft HFSS V7.0 for PC), and parameters obtained from the magnetic properties of NiFe magnetic core materials. frequency characteristics of inductance, dc resistance (R), coupling factor (k) and gain of developed transformers were measured using HP4194A impedance and gain-phase analyzer. The fabricated transformers with the size of $6.15 mm\time12.75 mm$ exhibit the inductance of $0.83 \muH$, the dc resistance of $2.3\Omega$$\Omega$, the k of 0.91 and the gain of -1 dB at 5 MHz, which show the comparable results to those reported in the recent literatures. The measured high-frequency characteristics for the fabricated transformers agreed well with those obtained by theoretical calculations .

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1030-1039
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• 2006

A high power and high gain Doherty amplifier is designed by using embedded driver amplifiers in the final stage. The operational characteristics of a two-stage Doherty amplifier are analyzed, as a function of the two-stage peaking amplifier gate biases. The driver stages and final output stages are implemented using two single-ended MRF21045s and a single push-pull packaged MRF5P21180, respectively. This two-stage Doherty amplifier demonstrated 27 dB gain with a PAE of 23 % at 15 W average output power.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.4
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• pp.779-784
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• 2020

In this paper, we improved the high frequency noise characteristics of the previously proposed hearing aid circuits for presbycusis, and we designed and fabricated a stereo hearing aid module. The cause of high frequency noise, which occurs in some cases in the previous circuits under high gain conditions, was analyzed through simulations. Two mute switches were added to adjust each boosting gain for right and left ears more accurately by muting the sound of the other ear when adjusting the gain of one ear in the stereo hearing aid module.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1861-1868
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• 2016

In this paper, a three-phase AC-DC high step-up converter is developed for application to microscale wind-power generation systems. Such an AC-DC boost converter prossessess the property of the single-switch high step-up DC-DC structure. For power factor correction, the advanced half-stage converter is operated under the discontinuous conduction mode (DCM). Simulatanously, to achieve a high step-up voltage gain, the back half-stage functions in the continuous conduction mode (CCM). A high voltage gain can be obtained by use of an output-capacitor mass and a coupled inductor. Compared to the output voltage, the voltage stress is decreased on the switch. To lessen the conducting losses, a low rated voltage and small conductive resistance MOSFETs are adopted. In addition, the coupled inductor retrieves the leakage-inductor energy. The operation principle and steady-state behavior are analyzed, and a prototype hardware circuit is realized to verify the performance of the proposed converter.

• Food Science and Biotechnology
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• v.15 no.1
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• pp.70-76
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• 2006

Anti-obesity effect of biocellulose and diet formulation containing it was evaluated using obese rats. Thirty male Sprague-Dawlely (SD) rats were randomly assigned to high-fat diet group (CON), high-fat diet group containing 5% biocellulose (BIO), and high-fat diet group containing 5% dietary formulation (DF). After 10 weeks, body weight gains of BIO and DF groups were reduced by 15.1 and 6%, respectively, as compared with CON group. Epididymus, parirenal, and visceral fat pads of BIO and DF groups were lower than those of CON group. Weight of interscapular brown adipose tissues increased slightly in BIO group and significantly in DF group. Size of adipocyte in rats decreased in BIO and DF groups. Results indicate biocellulose-containing diet has anti-obesity effect by reducing body weight gain and white adipocytes depots in rats fed high-fat diet.

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.3
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• pp.189-194
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• 2002

This paper presents a state observer design for a class of MTMO nonlinear systems that has a block triangular structure. For this, the extension of the existing design for SISO triangular systems to MIMO cases is provided. Since the gain of the proposed observer. depends on a nonlinear part as well as a linear one of a system, it improves the transient performance of the high gain ob-server. Also, by using a generalized similarity transformation for the error dynamics, it is shown that order some boundedness condi-tion, the proposed observer guarantees the global exponential convergence of the estimation error. Finally, we will give a simulation example to show the validity of our design methodology.

• Journal of IKEEE
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• v.22 no.1
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• pp.121-126
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• 2018

This paper addresses the consensus problem for nonlinear multi-agent systems using observer based controller. In order to solve this problem, the high gain approach is combined with the previous low gain controller. Also, it is shown that the proposed observer based controller can always guarantee the consensus of nonlinear systems with lower triangular nonlinearity.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.69-71
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• 2004

DC servo motors have a defect that they need a periodical maintenance because of a brush commutation and also they have a difficulty at high speed operation. In this reason, the use of AC Servo motors are increasing these days. In this paper, a proposed neuro observer is applied to speed control of AC servo motor. The proposed observer complement a problem that occur from increase of gain of High-gain observer in proportion to the square number of observable state variables. And also, the proposed observer can tune the gain obtained by differentiating observational error automatically by using the backpropagation training method to stabilize the observational speed. The excellence and feasibility of the proposed observer is proved by making a comparison test between the proposed observer and the others applied to the same AC servo motor.