• Journal of Advanced Marine Engineering and Technology
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• v.38 no.1
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• pp.64-69
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• 2014

There are 440V and 220V electric source in ship. A 440V source is used to drive the power system such as crane and winch on deck and pump in engine room, and a 220V source is used to drive the power source for residential zones, control devices in engine room. In this paper, we made single phase inverter system for grid connection with 220V source for ship, and analyzed THD(Total harmonic distortion) by variation of parameters of L-C low pass filter and deadtime of inverter switching.

• Journal of Pharmaceutical Investigation
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• v.40 no.spc
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• pp.113-118
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• 2010

Pharmaceutical technology has primarily focused on the development of the best dosage forms depending on the route of administration. The design of dosage forms is greatly influenced by the route of administration. Due to a variety of advantages such as avoidance of first-pass effect, abundant blood supply and easy access to the absorption site, the oral cavity has frequently been selected as a site for drug delivery. Since the oral cavity is relatively unique from the anatomical and physiological viewpoint, one should always consider these conditions when designing the drug delivery systems for the oral cavity. In this regard, the current review paper was prepared to summarize the essential features of the drug delivery systems utilized in the oral cavity, along with the introduction of various dosage forms developed to date.

• Journal of Advanced Navigation Technology
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• v.10 no.1
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• pp.20-25
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• 2006

In these days, OFDM(Orthogonal Frequency Division Multiplexing) is adopted to support high-speed data communication based on multi-path RF channel, but it has some weak point. One of those is that it has a higher PAR(peak-to-average power ratio) compared with single-carrier method. If some PAR of the transmitted signal is high, nonlinear amplitude distortion has occurred when it pass through the HPA(high power amplifier). There is a solution to prevent nonlinear distortion using higher peak power HPA, but it makes inefficiency and a cost problem. In this paper, we choose the SLM(Selected Mapping) scheme, which transmit the lowest PAR signal after OFDM symbol mapping, in various schemes reducing PAR for OFDM system. And we derived the performances of SLM method in fading channel through computer simulations.

• ETRI Journal
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• v.29 no.4
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• pp.421-429
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• 2007

This paper presents a direct-conversion CMOS transceiver for fully digital DS-UWB systems. The transceiver includes all of the radio building blocks, such as a T/R switch, a low noise amplifier, an I/Q demodulator, a low pass filter, a variable gain amplifier as a receiver, the same receiver blocks as a transmitter including a phase-locked loop (PLL), and a voltage controlled oscillator (VCO). A single-ended-to-differential converter is implemented in the down-conversion mixer and a differential-to-single-ended converter is implemented in the driver amplifier stage. The chip is fabricated on a 9.0 $mm^2$ die using standard 0.18 ${\mu}m$ CMOS technology and a 64-pin MicroLead Frame package. Experimental results show the total current consumption is 143 mA including the PLL and VCO. The chip has a 3.5 dB receiver gain flatness at the 660 MHz bandwidth. These results indicate that the architecture and circuits are adaptable to the implementation of a wideband, low-power, and high-speed wireless personal area network.

• Journal of the Korean Society for Precision Engineering
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• v.30 no.12
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• pp.1321-1325
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• 2013

In this paper, we proposed an air bearing stage with active magnetic preloads in vertical directions compensating motion errors and attenuating vibrations to improve dynamic characteristics. This preloaded design gives simpler configuration of the stage, and active control of preload can be used for compensating motion errors by feedforward method. To improve dynamic characteristics, vibration of the table is monitored by an accelerometer, and controlled by a DSP based digital controller with integrator and band pass filters for suppressing roll and pitch vibration modes. The modes were evaluated by measuring frequency response functions, and compared with compensated responses. This showed effective results for suppressing poorly damped regenerative vibration of air bearings.

• Journal of the Ergonomics Society of Korea
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• v.27 no.4
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• pp.95-101
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• 2008

This research is to develop PPG filtering method for respiration measurement in U-Health Care system. Respiration rate was determined by filtering PPG and analyzing its spectrum. Optimal filter of PPG has been selected to get respiration by testing 120 sets of experiment data using 700 filtering cases. As a result, 2nd order Bessel-filter that used band-pass cutoff frequency at 0.175~0.4Hz with second order was good at developing respiration signal. Respiration signal in time domain could be continuously analyzed by converting frequency domain using spectrum analysis. 24 seconds has been found to be optimal time duration of collecting PPG data for determining respiration. Therefore, this study was successful of getting not only heart activity but also respiration by only PPG. Minimal invasive measurement obtaining multi-bio information by one sensor can be expected to apply to U-Health Care and human computer interaction.

• Journal of Magnetics
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• v.10 no.4
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• pp.163-170
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• 2005

The RF integrated noise filters are fabricated by photolithography. The stack for the electromagnetic noise filters consists of the nano-granular ($Co_{41}Fe_{38}AI_{13}O_8$) soft magnetic film / $SiO_2$ / Cu transmission line / seed layer (Cu/Ti) / $SiO_2$-substrate. A good signal-attenuation feature along with a low signal-reflection feature is observed in the present filters. Especially in the noise filter incorporated with a $Co_{41}Fe_{38}AI_{13}O_8$ magnetic film with lateral dimensions of $2000{\mu}m$ wide, 15 mm long and $1{\mu}m$ thick, the maximum magnitude of signal attenuation reaches -55 dB, and the magnitude of signal reflection is below -10 dB in the overall frequency range. And this level of signal attenuation is much larger than that of a noise filter incorporated with a Fe magnetic film.

• ETRI Journal
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• v.46 no.2
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• pp.227-237
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• 2024

This study proposes a novel, conditionally applied neural network technique to reduce the overall peak-to-average power ratio (PAPR) of an orthogonal frequency division multiplexing (OFDM) system while maintaining an acceptable bit error rate (BER) level. The main purpose of the proposed scheme is to adjust only those subcarriers whose peaks exceed a given threshold. In this respect, the developed C-ANN algorithm suppresses only the peaks of the targeted subcarriers by slightly shifting the locations of their corresponding frequency samples without affecting their phase orientations. In turn, this achieves a reasonable system performance by sustaining a tolerable BER. For practical reasons and to cover a wide range of application scenarios, the threshold for the subcarrier peaks was chosen to be proportional to the saturation level of the nonlinear power amplifier used to pass the generated OFDM blocks. Consequently, the optimal values of the factor controlling the peak threshold were obtained that satisfy both reasonable PAPR reduction and acceptable BER levels. Furthermore, the proposed system does not require a recovery process at the receiver, thus making the computational process less complex. The simulation results show that the proposed system model performed satisfactorily, attaining both low PAPR and BER for specific application settings using comparatively fewer computations.

• Journal of Engineering Education Research
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• v.3 no.1
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• pp.12-20
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• 2000

In this paper, we are trying to explain an education method using the studio class where a lecturer can teach the theoretical approach for goals of theme, simulation for the theoretical results by using commercial CAD tools, and experiments for the simulation and design results. In order to apply the education skill using studio class to electrical engineering field efficiently, the theoretical approach, simulation procedure, and experiments should be coincided with each other. In this paper, the design procedure of low pass filter for undergraduate and graduate is chosen as an example of studio class In order to show the validity of the proposed education method. By considering the example, the efficiency of the method will be discussed.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 2000.11c
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• pp.578-585
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• 2000

Geometrical characteristics of fresh red pepper(Capsicum annuum L.) were measured and indexed to define some important geometrical characteristics, and malformation of body and fruit stalk which are necessary for the design of the equipments for cutting, spreading and alignment of red pepper in developing a fruit stalk remover of fresh red pepper. The effects of bending of body and fruit stalk on the equipments of cutting, spreading and alignment were studied. The maximum lengths of some parts of fresh red pepper were found to be 180 mm, 125 mm, 144 mm, 67 mm and 76 mm for the body, the bent part of body, the fruit stalk, the bent part and the straight part of fruit stalk, respectively. The fresh red pepper with bending indices more than 0.4 and 0.3 for the body and the fruit stalk, respectively, was defined to be malformed based on the result of cutting rate using cutting unit; while the other ones to be normal in shape. Based on this, among the total fresh red peppers tested, 47%, 40% and 20% were found malformed for the body, the fruit stalk, and for both of the body and the fruit stalk. Malformed red peppers were poorer in spreading and alignment than normal ones, and the processed quantity was decreased with increased feed rate. The required time for the malformed peppers to pass on the alignment plate inclined at 30 increased rapidly at 8.3 Hz with increased feed rate. For the fresh red peppers with average moisture content of 85%,w.b., the maximum tensile strength between fruit stalk and body was 88.1 N; the maximum cutting resistances were 92.1 N and 94.9 N for the fruit stalk-calyx joint and body, respectively. Average coefficients of static friction were 0.99, 0.62, 0.59 and OJ, respectively, for the surfaces of rubber, galvanized iron, acryl and plywood.