• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.3
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• pp.33-42
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• 2003

This paper describes an efficient design of an asynchronous 16-bit divider using the NST (new Svoboda-Tung) algorithm. The divider is designed to reduce power consumption by using the asynchronous design scheme in which the division operation is performed only when it is requested. The divider consists of three blocks, i.e. pre-scale block, iteration step block, and on-the-fly converter block using asynchronous pipeline structure. The pre-scale block is designed using a new subtracter to have small area and high performance. The iteration step block consists of an asynchronous ring structure with 4 division steps for area reduction. In other to reduce hardware overhead, the part related to critical path is designed by a dual-rail circuit, and the other part is done by a single-rail circuit in the ring structure. The on-the-fly converter block is designed for high performance using the on-the-fly algorithm that enables parallel operation with iteration step block. The design results with 0.6${\mu}{\textrm}{m}$ CMOS process show that the divider consists of 12,956 transistors with 1,480 $\times$1,200${\mu}{\textrm}{m}$$^2$area and average-case delay is 41.7㎱.

• Journal of the Korean Society of Laryngology, Phoniatrics and Logopedics
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• v.16 no.1
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• pp.28-32
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• 2005

Background and Objectives : The most important two factors of the voice production are the respiratory function which is the power source of voice and the glottic closure that transform the air flow into sound signals. The purpose of this study was to investigate the differences between trained singers and untrained controls under varying intensity at a constant vocal pitch by simulataneous using the airway interruption method and electroglottography(EGG). Materials and Methods : Under two different intensity condition at a constant vocal pitch(/G/), 20(Male 10, Female 10) trained singers were studied. Mean flow rate(MFR), subglottic pressure(Psub) and intensity were measured with aerodynamic test using the Phonatory function analyzer. Closed quotients(CQ), jitter and shimmer were also investigated by electroglottography using Lx speech studio. These data were compared with that of normal controls. Results : MFR and Psub were increased on high intensity condition in all subject groups but there was no statistically significance. Statistically significant increasing of CQ. were observed in male trained singers on high intensity condition (untrained male : 51.31${\pm}$3.70%, trained male :55.52${\pm}$6.07%, p=.039). Shimmer percent, one of the phonatory stability parameters, was also decreased statistically in all subject groups(p<.001). Conclusion : The trained singers' phonation was more efficient than untrained singers. The result means that the trained singers can increase the loudness with little changing of mean flow rate, subglottic pressure but more increasing of glottic closed quotients.

• 전자공학회논문지 IE
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• v.43 no.3
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• pp.22-27
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• 2006

This paper presents the control system of high-efficiency automotive 35W metal-halide lamp ballast using the new control method and planar transformer. In this paper, the electronic ballast is designed so that digital control method by microcontroller can be applied to the electronic ballast for the lamp requirement and peripheral environment in order that metal-halide lamp, which has the complicated transient features, is to be applied to the automobile even if it has superior features in brightness, color rendering, light efficiency, and lifespan compared to the conventional halogen lamp. Also, the efficiency increase of the ballast is devised by being varied the switching frequency of Flyback Converter following the battery input voltage of the automobile. Being designed for high-frequency switching transformer of converter in planar form, reduction of loss, weight, overall size are realized and efficient power control in the automobile that had the limited energy and the limited space of battery is devised. The results of the proposed system is verified through various experiment results.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.1
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• pp.61-70
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• 2008

This paper presents the flexible MEMS transmitter based on flexible printed circuit board or FPCB, which can be transformed to arbitrary shape. The FPCB is suitable to fabricate light weight and small size modules with the help of its thin thickness. Moreover a module based on FPCB can be attached on the arbitrary curved surface due to its flexible enough to be lolled up like paper. In this paper, the flexible MEMS transmitter integrated on FPCB for a short-distance sensor network which is based on orthogonal frequency division multiplexing(OFDM) communication system is proposed. The active device of the proposed flexible MEMS transmitter is fabricated on InGaP/GaAs HBT process which has been used for power amplifier design to take advantages of high linear and high efficient characteristics. Moreover, the passive devices such as the filter and signal lines are integrated and fabricated on the FPCB board. The performance of the fabricated flexible MEMS transmitter is analyzed with EVM characteristics of the output signal.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.8
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• pp.1773-1779
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• 2015

Shore-to-sea visible light communication using color clustered multiple-input and multiple-output (MIMO) is presented. The proposed maritime visible light communication (MVLC) offers a low-cost, high-speed wireless link for shore-to-sea maritime communications. Each color cluster is comprised of 50 red, green and blue (RGB) light emitting diodes (LEDs) and is modulated using on-off-keying (OOK). Selection combining is performed at the receiver, producing diversity effect within that color cluster. In this paper, we employ sea states (wave height, wind speed, etc.) data from both Pierson-Moskowitz and JONSWAP spectrum models under atmospheric turbulence conditions. Based on the simulation model, the maritime link quality is analysed in terms of coverage distance and bit error rate performance. The results show that the proposed system provides an efficient MVLC, while satisfying International Association of Lighthouse Authorities (IALA) requirements for maritime buoyage system and also offering sufficient illumination from high power LEDs.

• Korean Chemical Engineering Research
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• v.58 no.1
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• pp.1-20
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• 2020

Development of efficient methods for clean energy production became a critical issue to improve the quality of human lives. Solar cells is considered as one of the alternative solutions to resolve the issue. Although Si-based solar cells are only popularly utilized for practical applications, high manufacturing cost is considered as a serious drawback for further versatile applications. Thus, different types of are being investigated aiming to replace the Si-based solar cells. Recently, perovskite solar cells (PSC) are considered as a potential replacement for Si-based solar cells due to their low production cost, high power conversion efficiency, light weight and possibility of flexible device fabrication. Thus, we have reviewed the challenges of PSC faced with practical application, particularly on stability.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.16 no.2
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• pp.151-155
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• 2016

In this paper, we present the LED dimming control system by using ADPCM (Adaptive Differential Pulse Code Modulation). This ADPCM apparatus accurately controls the LED current with high resolution reducing the RFI (radio frequency interference) due to the spreading out of the harmonics of current of pulses. Additionally, this makes it easier to increase the accuracy of control operation. This study introduces to make a digitally controlled circuit for controlling LED with high-energy efficient by adopting pulse current to LED. The LED current drive system we designed are two systems, the digitally-controlled unit and analog switching mode power supply unit, can be developed separately. The simulation shows the sigma delta modulation of digital to analog converter's output when the input level is 0.7. From this simulation, the output is approached to accurately 0.15% to target value with 510 pulses.

• Journal of the Institute of Electronics Engineers of Korea SP
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• v.44 no.5
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• pp.84-93
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• 2007

In this paper, a Radix-8 structure for high-speed FFT is propose. Main block of the proposed FFT structure is Radix-8 DIF(Decimation In Frequency) butterfly. Even throughput of the Radix-8 FFT is twice than that of the Radix-4 FFT, implementation area of the Radix-8 is larger than that of Radix-4 FFT. But, implementation area of the proposed Radix-8 FFT was reduced by using DA(Distributed Arithmetic) for multiplication. For comparison, the 64-point FFT was implemented using conventional Radix-4 butterfly and proposed Radix-8 butterfly, respectively. The Verilog-HDL coding results for the proposed FFT structure show 49.2% cell area increment comparison with those of the conventional Radix-4 FFT structure. Namely, to speed up twice, 49.2% of area cost is required. In case of same throughput, power consumption of the proposed structure is reduced by 25.4%. Due to its efficient processing scheme, the proposed FFT structure can be used in large size of FFT like OFDM Modem.

• Journal of Korean Medicine Rehabilitation
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• v.30 no.2
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• pp.67-75
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• 2020

Objectives SJ004 is a natural herbal medicine that contains Acyranthes japonica Nakai and Eucommia ulmoides Oliver traditionally used for joint and spinal diseases. This study aimed to establish an efficient method of extracting SJ004 to standardize using the yield, high-performance liquid chromatography (HPLC), and antioxidant assay. Methods SJ004 was extracted with distilled water, 70% and 100% of ethyl alcohol (EtOH). The method validation of 20-hydroxyecdysone and pinoresinol diglucoside was determined by HPLC-photo diode array and the content of SJ004 was calculated. The antioxidant activity of each extract was compared and measured using total flavonoids, total phenolic compounds, 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid), and ferric reducing antioxidant power according to the standard protocol. Results The yield was highest in pure water extract and lowest in 100% EtOH. But, the content of marker compounds indicating 20-hydroxyecdysone and pinoresinol diglucoside was highest in 100% EtOH extract. In the physiological activity measurement using antioxidant activity, 100% ethanol extract was highest. The limit of detection indicating 20-hydroxyecdysone and pinoresinol diglucoside were analyzed 0.33 ㎍/mL, 0.1616 ㎍/mL, and the limit of quantification were analyzed 1.01 ㎍/mL and 0.49 ㎍/mL respectively. Conclusions The experimental results showed that the extraction conditions have a significant effect on content of marker compounds and antioxidant activity. As a result of method validation, SJ004 was standardized by 20-hydroxyecdysone and pinoresinol diglucoside.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1139-1148
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• 2000

To treat and recycle a large quantity of converter slag. the milling properties of -14/ +24 mesh-sized slag has been considered. The optimal conditions in milling process were investigated for producing powder-type slag and the required consumption was derived for the economical grinding. The characteristics of milling processes were studied in the variation of the rotational speed, milling time, filling ratio of ball, and size and amount of feed. The grinding efficiency was also examined. The optimal rotational speed in this experimental condition was observed to be the value of 79% of critical speed. The extent of grinding was increased with increasing the grinding time. but the efficiency of milling was decreased with the time. 50% ball filling was shown to have the optimal grinding effect, and less amount and small-sized feed made the milling efficiency high. As the result, using Bond's equation, power required for efficient milling was considered and the highest value was observed in the condition of high grinding time and optimal rotational speed.