• Journal of the Korean Society of Marine Environment & Safety
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• v.19 no.6
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• pp.666-673
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• 2013

This paper proposes the performance evaluation test of attitude heading reference system (AHRS) suitable for small high speed autonomous underwater vehicle(AUV). Although IMU can provides the detail attitude information, it is sometime not suitable for small AUV with short operation time in view of price and the electrical power consumption. One of alternative for tactical grade IMU is the AHRS based micro-machined electro mechanical system(MEMS) which can overcome many problems that have inhibited the adoption of inertial system for small AUV such as cost and power consumption. A cost effective and small size AHRS which incorporates measurements from 3-axis MEMS gyroscopes, accelerometers, and 3-axis magnetometers has been developed to provide a complete attitude solution for AUV and the attitude calculation algorithm is derived based the coordinate transform equation and Kalman filter. The developed AHRS was validated through various performance tests as like the magnetometer calibration, operating experiments using land mobile vehicle and flight motion simulator (FMS). The test of magnetometer calibration shows the developed MEMS AHRS is robust to the external magent field change and the test with land vehicle proves the leveling error of developed MEMS AHRS is below $0.5^{\circ}/hr$. The results of FMS test shows the fact that AHRS provides the measurement with $0.5^{\circ}/hr$ error during 5 minutes operation time. These results of performance evaluation tests showed that the developed AHRS provides attitude information which error of roll and pitch are below $1^{\circ}$ and the error of yaw is below $5^{\circ}$ and satisfies the required specification. It is expected that developed AHRS can provide the precise attitude measurement under sea trial with real AUV.

• Journal of the Korean Society of Food Culture
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• v.3 no.2
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• pp.187-195
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• 1988

In accordance with the rapidly growing number of street food service without a registration, a study was undertaken to determine the present state of food service by the covered wagon bar, through an investigation in Jamwondong, around the south gate market and Kangnam subway station, in Seoul, between July 25th and August 25th of 1987. The survey was comprised of three parts: 1) foodservice operation in covered wagon, 2) personal and food handling hygiene, 3) food behaviors of customers. A total of 54 covered wagon bars, consisting of 51.8% mobile bars and 48.2% non-mobile bars, operating in the above three locations, were investigated. Survey results show non-mobile covered wagon bars to be more popular among persons in their thrities and fourties than among teens or the elderly; also among males than females; among company employees and college students than others. Seventy five percent of the mobile covered wagon bars served snack type foods and others served wine and foods for wine, in contrast to hundred percent of the non-mobile covered wagon bars served wine and foods for wine. The survey found many problems of hygiene, in method of food purchasing, menu planning, food preparation, dish washing treatment of leftovers and water supply, as well as personal hygiene. However, customers prefer the casual and popular atmosphere at the counter of the covered wagon bar. Finally, the study emphasizes a need for better operation of covered wagon bar, improvement of food stuff handling and the way of food services and personal hygiene. A change of the registration system from the illegal operation are urgently needed for better quality food services of covered wagon bars.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.1
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• pp.171-175
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• 2006

In this paper, we have developed a retrodirective active array operating in the 2 GHz LS band. The retrodirective array has the property of redirecting any electromagnetic wave back to the incoming direction without any priory informations. The system is integrated with phase conjugators and antenna array. Microwave phase conjugators can be implemented by microwave mixers. In this research, 2-port gate mixers using pHEMT and $1{\times}4$ monopole array have been used to achieve the retrodirectivity. The measured results have been compared with the theoretical prediction, and it has been shown that there exists a reasonable agreement between them. The monopole array can be used easily in many areas for simplicity and cost-effective property, and the retrodirective array developed in this research can be applied directly in the base station facilities for the wireless mobile communications. indoor wireless LAN and RFID transponders.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.5
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• pp.489-498
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• 2003

Recently to introduce new services of ultra-high speed wireless access and systems beyond the 3rd generation mobile communication, 5 GHz band has been highly interested. As a way of getting the required frequency, it is considered that microwave relay bands below 6 GHz, which shows a slow decrease in demand and less cost-effectiveness, should be moved to other bands above 6 GHz. In this paper, as a tool for analyzing microwave link design and its service quality, the outage prediction based upon Vigants & Barnett＇s model is reviewed. To show outage and availability calculation, simulations are performed for the operating 4 GHz radio sites, and some results and features regarding frequency movement to 6.7 as well as 8 GHz are also discussed in terms of diversity techniques, bit error rate, and availability As the results, it is confirmed that only the diversity techniques of space or space and frequency can satisfy the annual objective of availability irrespective of frequency movement.

• 한국HCI학회:학술대회논문집
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• 2009.02a
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• pp.785-790
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• 2009

Widgets are the instrument for representing user's character and embossing the value of blogs. The compound word of the Windows and Gadget the application, widgets are the functional program to displayed on the screen graphical user interface (GUI) tools as a kind of service that user want to see. On the operating system, the Web, and mobile area, widgets offer the delivery of information, convenience and efficiency. However widgets have been never gave satisfaction to user because it focused transmitting information and representing circumstance than fun. This study is for recognized fun elements that user feel interest and categorized fun elements each type of widgets. Fun elements of widget never been defined, we use fun elements on design and product area and emotional word that is representative of affectivity. And we make up an online questionnaire to blog users. The widget selected by popular degree among the domestic widgets and the Japanese widget. And the results of the questionnaire that 5-scales used based on user preferences to identify the elements that are fun.

• KIPS Transactions on Computer and Communication Systems
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• v.5 no.11
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• pp.379-384
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• 2016

NAND flash storage is widely used for computer systems, because of it has faster response time, lower power consumption, and larger capacity per unit area than hard disk. However, currently used I/O scheduler in the operating system is optimized for characteristics of the hard disk. Therefore, the conventional I/O scheduler includes the unnecessary overhead in the case of the NAND flash storage to be applied. Particularly, when the write requests performed intensively, garbage collection is performed intensively. So, it occurs the problem that the processing of the I/O request delay. In this paper, we propose the new I/O scheduler to solve the problem of garbage collection performs intensively, and to optimize for NAND flash storage. In the result of performance evaluation, proposed scheme shows an improvement the user responsiveness by reducing 1% of the average read response time and 78% of the maximum response time.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.17 no.6
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• pp.137-143
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• 2017

Facilities for pedestrian safety of the visually impaired are scarce on the walkway and crosswalk. Braille blocks are installed on the walkways and RF controlled signal lights and sound generators are installed on the crosswalk at the main intersection for the visually impaired. An RF remote control system using one frequency has a problem of simultaneously operating nearby signal lamps and sound generators at an intersection. In this paper, we develop the smart cane that uses a beacon to identify the signal lamp and sound generators installed on the crosswalk at intersections and to operate the signal lamps and sound generators in the direction of the walk by IR communication. The developed smart cane is able to provide the pedestrian navigation for the blind by interworking with mobile apps through Bluetooth communication.

• Journal of IKEEE
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• v.12 no.1
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• pp.1-7
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• 2008

With the recent development of portable system such as mobile communication and multimedia. Full adders are important components in applications such as digital signal processors and microprocessors. Thus It is important to improve the power dissipation and operating speed for designing a full adder. We propose a new adder with modified version of conventional Ratioed logic and Pass Transistor logic. The proposed adder has the advantages over the conventional CMOS, TGA, 14T logic. The delay time is improved by 13% comparing to the average value and PDP(Power Delay Product) is improved by 9% comparing to the average value. Layouts have been carried out using a 0.18um CMOS design rule for evaluation purposes. The physical design has been evaluated using HSPICE.

• Genomics & Informatics
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• v.8 no.1
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• pp.28-33
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• 2010

Increased exposure of human to RF fields has raised concerns for its potential adverse effects on our health. To address the biological effects of RF radiation, we used genome wide gene expression as the indicator. We exposed normal WI-38 human fibroblast cells to 1763 MHz mobile phone RF radiation at a specific absorption rate (SAR) of 60 W/kg with an operating cooling system for 24 h. There were no alterations in cell numbers or morphology after RF exposure. Through microarray analysis, we identified no differentially expressed genes (DEGs) at the 0.05 significance level after controlling for multiple testing errors with the Benjaminiochberg false discovery rate (BH FDR) method. Meanwhile, 82 genes were differentially expressed between RF-exposed cells and controls when the significance level was set at 0.01 without correction for multiple comparisons. We found that 24 genes (0.08% of the total genes examined) were changed by more than 1.5-fold on RF exposure. However, significant enrichment of any gene set or pathway was not observed from the functional annotation analysis. From these results, we did not find any evidence that non-thermal RF radiation at a 60-W/kg SAR significantly affects cell proliferation or gene expression in WI-38 cells.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12A
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• pp.1097-1104
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• 2010

This paper presents the signal-to-noise ratio (SNR) and signal-to-interference plus noise ratio (SINR) estimation based on A-Preamble of IEEE 802.16m IMT-Advanced WiMax system with simulation results. The downlink signal of IEEE 802.16m has two kinds of A-Preambles: the PA-Preamble and the SA-Preamble. This paper proposes the effective method of estimating SNR and SINR with A-Preambles, and also shows that this method can recognize the ICI(Inter-Carrier-Interference) occurrence due to doppler frequency. With the recognition of ICI, the mobile station can save the power by operating 1-tap equalizer in usual cases, and activating ICI mitigation module only when it perceives the ICI occurrence.