• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.9
• /
• pp.82-90
• /
• 2014

In this paper, a couple of 4-channel differential transimpedance amplifier arrays are realized in a standard 0.18um CMOS technology for the applications of linear LADAR(laser detection and ranging) systems. Each array targets 1.25-Gb/s operations, where the current-mode chip consists of current-mirror input stage, a single-to-differential amplifier, and an output buffer. The input stage exploits the local feedback current-mirror configuration for low input resistance and low noise characteristics. Measurements demonstrate that each channel achieves $69-dB{\Omega}$ transimpedance gain, 2.2-GHz bandwidth, 21.5-pA/sqrt(Hz) average noise current spectral density (corresponding to the optical sensitivity of -20.5-dBm), and the 4-channel total power dissipation of 147.6-mW from a single 1.8-V supply. The measured eye-diagrams confirms wide and clear eye-openings for 1.25-Gb/s operations. Meanwhile, the voltage-mode chip consists of inverter input stage for low noise characteristics, a single-to-differential amplifier, and an output buffer. Test chips reveal that each channel achieves $73-dB{\Omega}$ transimpedance gain, 1.1-GHz bandwidth, 13.2-pA/sqrt(Hz) average noise current spectral density (corresponding to the optical sensitivity of -22.8-dBm), and the 4-channel total power dissipation of 138.4-mW from a single 1.8-V supply. The measured eye-diagrams confirms wide and clear eye-openings for 1.25-Gb/s operations.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.19 no.10
• /
• pp.1096-1103
• /
• 2008

This paper proposes an individual order predistortion linearizer using intermodulation distortion(IMD) generator for cancellation the third and the fifth IMD of power amplifier. The IMD generator for controlling the third and the fifth IMD consist of common Emitter amplifier and Schottky diode. These signals are generated by series feedback of Schottky diode to obtain the inverse AM/AM and AM/PM characteristics of power amplifier. The individual order predistorters are consisted of individual IMD generator, power splitter and combiner. The test results show that the third and the fifth IMD can be improved by a maximum 13.5 dB and 0.9 dB in case of CW 2-tone signals. Also, the Adjacent Channel Leakage Ratio(ACLR) can be improved 2.3 dB, 2.5 dB at ${\pm}0.885$ MHz, ${\pm}1.23$ MHz offset frequency for CD-MA IS-95 2FA signals.

• Journal of Astronomy and Space Sciences
• /
• v.24 no.1
• /
• pp.79-90
• /
• 2007

The AmonRa instrument, the primary payload of the international EARTHSHINE mission, is designed for measurement of deep space albedo from L1 halo orbit. We report the optical design, tolerance analysis and the optical performance of the breadborad AmonRa imaging channel instrument optimized for the mission science requirements. In particular, an advanced wavefront feedback process control technique was used for the instrumentation process including part fabrication, system alignment and integration. The measured performances for the complete breadboard system are the RMS 0.091 wave(test wavelength: 632.8 nm) in wavefront error, the ensquared energy of 61.7%($in\;14\;{\mu}m$) and the MTF of 35.3%(Nyquist frequency: $35.7\;mm^{-1}$) at the center field. These resulting optical system performances prove that the breadboard AmonRa instrument, as built, satisfies the science requirements of the EARTHSHINE mission.

• Journal of Navigation and Port Research
• /
• v.39 no.4
• /
• pp.293-297
• /
• 2015

Underwater acoustic communications has been limited use for military purposes in the past. However, the fields of underwater applications expend to detection, submarine and communication in recent. The excessive multipath encountered in underwater acoustic communication channel is creating inter symbol interference, which is limiting factor to achieve a high data rate and bit error rate performance. To improve the performance of a received signal in underwater communication, many researchers have been studied for channel coding scheme with excellent performance at low SNR. In this paper, we applied BCJR decoder based ( 2,1,7 ) convolution codes and to compensate for the distorted data induced by the multipath, we applying the turbo equalization method. Through the underwater experiment on the Gyeungcheun lake located in Mungyeng city, we confirmed that turbo equalization structure of BCJR has better performance than hard decision and soft decision of Viterbi decoding. We also confirmed that the error rate of decoder input is less than error rate of $10^{-1}$, all the data is decoded. We achieved sucess rate of 83% through the experiment.

• Journal of Technology Innovation
• /
• v.14 no.1
• /
• pp.227-254
• /
• 2006

Under the recent trend of telecommunications and broadcasting convergence, much more various forms of new convergence broadcasting services are being introduced than ever before. Owing to the unique advantages, new convergence broadcasting services are expected to bring drastic changes to the current broadcasting service market. In this research, we attempt to examine what kind of attributes critically affect the competition among new convergence broadcasting services, and how much competitive they will be, based on the quantitative information about consumer preferences for the important attributes of new convergence broadcasting services. Conjoint survey was used in order to obtain stated preference data of consumers. From the results, some implications are obtained as follows. First, even though new convergence broadcasting services have many unique advantages, still price is the most important for the consumers. Second, it is expected that considerable consumer valuation exists for the unique advantages of new convergence broadcasting services like mobility and dual-way interactivity, which will add the competitiveness of those services in the future. Third, since midterm advertising puts negative utility on consumers, broadcasting services with midterm advertising will not be preferred to those with neither advertising nor midterm advertising. Fourth, service coverage and the number of consumers using the same broadcasting service have a significant feedback effect on the competition between broadcasting services from the dynamic aspect. Lastly, the consumer preference can be affected by demographic variables like age and gender, and broadcasting service usage patterns such as channel switchover for escaping advertisement and frequency of using other recorded media. Main findings of our research might become useful information for both telecommunication and broadcasting companies, contents providers, advertisers, and policy and regulation makers to cope with the uncertain environment of telecommunication and broadcasting convergence.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.14 no.3
• /
• pp.781-793
• /
• 2010

Recently, owing to the development of ubiquitous sensor network and mobile communication technologies, many studies on healthcare system are being carried out. In this paper, we have designed and implemented a mobile u-Healthcare system based on sensor network. The u-Healthcare system is composed of three components: wireless sensor network at home, healthcare center located at remote site, and gateway which relays sensing physiological signals to healthcare center. In order to measure patient's physiological signal three sensors are used: three channel ECG sensor, pulse oximeter, and blood pressure sensor. Each sensor is mounted on a mote which can send gathered signal to the base node using Zigbee communication protocol. Once the base node receives physiological signal from each sensor, the client in the base node transfers the signal to the healthcare center. The received physiological signal at the healthcare center is analyzed and processed using various algorithms. The processed results are compared to the standard healthcare database and appropriate treatment including dietetics and exercise cure would be sent to the patient as feedback using SMS message or healthcare center web site. Each patient can check and manage one's health state every day using the healthcare system and gain a recovery under the treatments from minor health problems.

• Science of Emotion and Sensibility
• /
• v.12 no.3
• /
• pp.341-350
• /
• 2009

Archer's capability of attention and relaxation control during shooting process was evaluated using EEG technology. Attention and meditation algorithms were used to represent the levels of mental concentration and relaxation levels. Elite, mid-level, and novice archers were tested for short and long distance shootings in the archery field. Single channel EEG was recorded on the forehead (Fp1) during the shooting process, and attention and meditation levels were computed by real time. Four types of variations were defined based on the increasing and decreasing patterns of attention and meditation levels during shooting process. Elite archers showed increases in both attention and relaxation while mid-level archers showed increased attention but decreased relaxation. Elite archers also showed higher levels of attention at the release than mid-level and novice archers. Levels of attention and relaxation and their variation patterns were useful to categorize archers and to provide feedback in training.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.18 no.5
• /
• pp.1042-1050
• /
• 2014

The performance of underwater acoustic(UWA) communication system is sensitive to the Inter-Symbol Interference(ISI) due to delay spread develop of multipath signal propagation. And due to limited frequency using acoustic wave, UWA is a low transmission rate. Thus, it is necessary technique of Space-time code, equalizer and channel code to improve transmission speed and eliminate ISI. In this paper, UWA communication system were analyzed by simulation using these techniques. In the result of simulation, the proposed Turbo Equalization method based on layered Space Time Codes has improved performance compared to conventional UWA communication.

• The Journal of the Korea Contents Association
• /
• v.15 no.7
• /
• pp.181-192
• /
• 2015

Nonverbal immediacy plays a key role in interpersonal communication, inducing closeness and another interaction. This case study investigates the nonverbal behaviors in Human-Robot Interaction(HRI) focusing on immediacy, and how they affect perception of a robot. The results show that nonverbal immediacy, such as nodding and leaning forward, affect perceived interactivity. Nonverbal immediacy can be interpreted their meaning clearly when verbal feedback or other communication channel reinforcing them. Also, touch is found to affect come up with similar ones to the robot, because it is associated with concrete and discrete context. People tend to apply social rules to the robot, but they are more open to the unfamiliar robot compared to strangers. The findings in this study provide future HRI studies with heuristic implications by showing a direction and clarifying principles for composition of verbal and nonverbal expression.

• Molecules and Cells
• /
• v.19 no.2
• /
• pp.268-278
• /
• 2005

We investigated the effect of cytosolic and extracellular $Ca^{2+}$ on $Ca^{2+}$ signals in pancreatic acinar cells by measuring $Ca^{2+}$ concentration in the cytosol($[Ca^{2+}]_c$) and in the lumen of the ER($[Ca^{2+}]_{Lu}$). To control buffers and dye in the cytosol, a patch-clamp microelectrode was employed. Acetylcholine released $Ca^{2+}$ mainly from the basolateral ER-rich part of the cell. The rate of $Ca^{2+}$ release from the ER was highly sensitive to the buffering of $[Ca^{2+}]_c$ whereas ER $Ca^{2+}$ refilling was enhanced by supplying free $Ca^{2+}$ to the cytosol with $[Ca^{2+}]_c$ clamped at resting levels with a patch pipette containing 10 mM BAPTA and 2 mM $Ca^{2+}$. Elevation of extracellular $Ca^{2+}$ to 10 mM from 1 mM raised resting $[Ca^{2+}]_c$ slightly and often generated $[Ca^{2+}]_c$ oscillations in single or clustered cells. Although pancreatic acinar cells are reported to have extracellular $Ca^{2+}$-sensing receptors linked to phospholipase C that mobilize $Ca^{2+}$ from the ER, exposure of cells to 10 mM $Ca^{2+}$ did not decrease $[Ca^{2+}]_{Lu}$ but rather raised it. From these findings we conclude that 1) ER $Ca^{2+}$ release is strictly regulated by feedback inhibition of $[Ca^{2+}]_c$, 2) ER $Ca^{2+}$ refilling is determined by the rate of $Ca^{2+}$ influx and occurs mainly in the tiny subplasmalemmal spaces, 3) extracellular $Ca^{2+}$-induced $[Ca^{2+}]_c$ oscillations appear to be triggered not by activation of extracellular $Ca^{2+}$-sensing receptors but by the ER sensitised by elevated $[Ca^{2+}]_c$ and $[Ca^{2+}]_{Lu}$.