• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.12
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• pp.1340-1350
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• 2009

The design and implementation of planar Active Phased Array Antenna System are described in this paper. This Antenna system operates at X-band with its bandwidth 10 % and dual polarization is realized using dual slot feeding microstrip patch antenna and SPDT(Single Pole Double Through) switch. Array Structure is $16\times16$ triangular lattice structure and each array is composed of TR(Transmit & Receive) module with more than 40 dBm power. Each TR module includes digital attenuator and phase shifter so that antenna beam can be electronically steered over a scan angle$({\pm}60^{\circ})$. Measurement of antenna pattern is conducted using a near field chamber and the results coincide with the expected beam pattern. From these results, it can be convinced that this antenna can be used with control of beam steering and beam shaping.

• Journal of Bio-Environment Control
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• v.9 no.4
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• pp.237-243
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• 2000

Agricultural machine is currently operated by man power in the greenhouse, which is oppressively hot and humid, and is for a farmer not to work in comfortable circumstances. In the future, agricultural machine will not have to operate by man power, but it will need do by unmanned power. In order to put into the automatic and unmanned operation of agricultural machine, this system was designed and built to move through the fixed path in the greenhouse. This system was composed of guiders(wires), a limit switch, an operating equipment, its software for automatizing a machine in the greenhouse. The guider was connected between the wall pillars, and the equipment was able to slide over the fixed path made of the guider, by rectilinear and rotational motion. A micro mouse was developed with a stepping motor to calculate on the success rate of its operation with the system As might be expected, this system with the micro mouse was moved the moved the paths with a success rate of 100% on the flat plane surface in our laboratory. However, on the sand plane or the other materials plane, the success rate was not better than 80%. If the micro mouse were well operated, the success rate was would be 100%. Based on the results of this research, this system would be expected to operate well on the path made of a simple wire.

• Journal of Broadcast Engineering
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• v.18 no.4
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• pp.572-588
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• 2013

In this paper, 4K-UHDTV or 8K-UHDTV and UHD-3DTV that the next generation broadcasting implementation and the possibility of direct receiving environment construction is analyzed on the terrestrial broadcasting. Particularly, we investigated the possibility by analyzing the previous and related works with regard to UHDTV transmission by DVB-T2 that is one of the best commercialized transmission mode. In order that the UHDTV broadcasting succeeds once again after completion of digital terrestrial switch over at the end of 2012, the ultra high resolution image transfer is important. However, the direct, the indoor and ubiquitous receiving environment is important in not only TV but also the personal type multimedia terminal in the sense of UHDTV service penetration. Therefore, in this paper, by using SFN and high error-correcting mode in DVB-T2 standard, the efficient frequency utilization and effective reception environment construction is illustrated. Particularly, SFN network constitution by 2 mutually different frequencies including the VHF bandwidth and UHF band, and etc. is shown. And the method that builds the free wireless receive environment by using SFN low power radio repeater and for home use gap filler is proposed. And the effect and frequency amount required are presented, when UHDTV broadcasting use 10MHz bandwidth.

• 전자공학회논문지 IE
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• v.46 no.4
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• pp.1-7
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• 2009

The final goal of ITS and ETC will be to improve the traffic efficiency and mobile safety without new road construction. DSRC system is emerging nowadays as a solution of them. China DSRC standard which was released in May 2007 has low bit rate, short message and simple MAC control. The DSRC system users want a long lifetime over 1 year with just one battery. In this paper, we propose the SoC of very low power consumption architecture. Several digital logic concept and analog power control logics were used for very low power consumption. The SoC operation mode and clock speed, operation voltage range, wakeup signal detector, analog comparator and Internal Voltage Regulator & External Power Switch were designed. We confirmed that the SoC power consumption is under 8.5mA@20Mhz, 0.9mA@1Mhz in active mode, and under 5uA in power down mode, by computer simulation. The design of SoC was finished on Aug. 2008, and fabricated on Nov. 2008 with $0.18{\mu}m$ CMOS process.

• Journal of Korea Port Economic Association
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• v.23 no.4
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• pp.196-215
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• 2007

The Representatives of Korea & India hold The Sixth negotiation for conclusion of Korean-India CEPA(Comprehensive Economic Partnership Agreement) at IFANS(Institute of Foreign Affairs & National Security) in Seoul at April 4, 2007. The latest, India is paid attention by the citizen of the world as the leading country that it lead the 21C's world economic with the China, India is called one of the BRICs and Chindia countries. Now, the concern of the citizen of world inclines huge potential energy of India. It is that time, we must change our concern from Chinas to India slowly. This paper put emphasis the point that we have to move switch over the focus of our study from to India, now.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.6
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• pp.617-624
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• 2015

This paper describes the development of a wearable robot to assist the elbow muscle for use by elderly workers in aging societies. Various previously developed wearable robots have drawbacks in terms of their price, portability, and slow recognition of the wearer's intention. In this paper, emphasis is placed on the following features to minimize these drawbacks. The first feature is that an actuator is attached only at the elbow joint that withstands the highest moment during arm motion to reduce the weight, volume, and price of the robot and increase its practicality. The second is that operation of the wearable robot is divided into two modes, a tracking mode and a muscle strengthening mode, and the robot can automatically switch between these modes by analyzing the wearer's intention through the brachial muscle strength measuring device developed in this study. The assistive performance of the developed wearable robot is experimentally verified by motion tracking experiments without an external load and muscle strengthening experiments with an external load. During the muscle strengthening experiments, the power of the muscle of the upper arm is measured by a commercial electromyography (EMG) sensor. Motion tracking performance at a speed of $120^{\circ}/s$ and muscle assistance of over 60 % were obtained using our robot.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.27 no.1
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• pp.60-68
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• 2016

This paper presents a 6~18 GHz 7-bit digital-controlled attenuator. The proposed attenuator is based on switched-T architecture, but no inductor is used for minimum chip size. The designed attenuator was fabricated using $0.18{\mu}m$ CMOS process, and characterized using on-wafer testing setup. The resolution(minimum attenuation step) and the maximum attenuation range of the attenuator were measured to be 0.22 dB and 28 dB, respectively. The measured RMS attenuation error and the RMS phase error for 6~18 GHz were less than 0.26 dB and $3.2^{\circ}$, respectively. The reference state insertion loss was less than 12.4 dB at 6~18 GHz. The measured input and output return losses were better than 9.4 dB over all frequencies and attenuation states. The chip size is $0.11mm^2$ excluding pads.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.29 no.8
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• pp.461-465
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• 2016

n-type silicon shows the better tolerance towards metal impurities with a higher minority carrier lifetime compared to p-type silicon substrate. Due to better lifetime stability as compared to p-type during illumination made the photovoltaic community to switch toward n-type wafers for high efficiency silicon solar cells. We fabricated the front electrode of the n-type solar cell with AgAl paste. The electrodes characteristics of the AgAl paste depend on the contact junction depth that is closely related to the firing temperature. Metal contact depth with p+ emitter, with optimized depth is important as it influence the resistance. In this study, we optimize the firing condition for the effective formation of the metal depth by varying the firing condition. The firing was carried out at temperatures below $670^{\circ}C$ with low contact depth and high contact resistance. It was noted that the contact resistance was reduced with the increase of firing temperature. The contact resistance of $5.99m{\Omega}cm^2$ was shown for the optimum firing temperature of $865^{\circ}C$. Over $900^{\circ}C$, contact junction is bonded to the Si through the emitter, resulting the contact resistance to shunt. we obtained photovoltaic parameter such as fill factor of 76.68%, short-circuit current of $40.2mA/cm^2$, open-circuit voltage of 620 mV and convert efficiency of 19.11%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.6
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• pp.1170-1174
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• 2009

Two frequency-reconfigurable antennas have been designed and combined in a space with limited volume, i.e., 40mm ${\times}$ 20mm ${\times}$ 6mm. Each antenna can be reconfigured to operate at different frequency bands depending on the state of an embedded switch, which is implemented using a PIN diode. The first antenna can be switched between 0.82GHz ${\sim}$ 0.96GHz band (GSM/ CDMA) and 1.7GHz ${\sim}$ 2.17GHz band (DCS/ PCS/ WCDMA), which are cellular bands. The second antenna can be switched between 3.4GHz ${\sim}$ 3.6GHz band (mWiMax) and 2.3GHz ${\sim}$ 2.5GHz, 5.15GHz ${\sim}$ 5.35GHz bands (WiBro/ WLAN 11a/b/g/n), which are connectivity bands. The proposed combined antenna operates both over cellular bands and connectivity bands concurrently. The choice of the operation bands is made independently by the states of the two switches.

• Quality Improvement in Health Care
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• v.9 no.2
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• pp.210-228
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• 2002

Background: The purpose of this research was to examine the fall incidence rate and its related factors of fall in inpatients. Methods: The data were collected from the 138 fall incident reports in one tertiary hospital in Seoul from April 1st 1999 to September 30th 2001. The Fall Incident Report Form was originally developed based on that of Massachusetts General Hospital revised in 1995. And this was modified for this survey by the collaborating work of QI team including researcher and department of nursing service of this particular hospital. The contents of Fall Incident Form were general characteristics of patient. factors related to fall. types and places of fall. circumstances, nursing interventions. and outcome. Results: 1) The incidence rate of fall was 0.08% of total discharged patients and 0.081 per 1000 patient-day. This incidence rate is much lower than that of several hospitals in USA. This finding might result from the different incidence report system of each hospital. 2) The characteristics of fall-prone patient were found as follows. They were mostly over 60 years old, in alert mental status, ambulatory with some assistance, and dependent on ambulatory device. The types of diseases related high incidence rate were cerebrovascular disease(3.2), hypertension(1.6), cardiovascular disease(1.4), diabetes(1.3) and liver disease(0.6). 3) The majority of fall events usually occurred m bed. bedside(walking or standing) and bathroom in patient room. Usually they were up on their own when they fell. And there were more falls of elderly occurred during night time than day or evening. 4) 63.8% of fall events resulted in physical injuries such as fracture and usually the patients had diagnostic procedures and some treatment(ex. suture) which caused additional cost to the patients and their families. 5) The found risk factors of fall were drugs(antihypertensive drug, diuretics) and environmental factors like too high bed height, long distance of bedside table and lamp switch, and slippery tile of bathroom floor. Conclusion: Considering these results, every medical and nursing staff should be aware of the risk factors of patients in hospital, and should intervene more actively the preventive managements, specially for the elderly patients during night. Therefore, it is recommended that the development of Fall Prevention Programs based on these results.