A Design of Receiver Modem That Can Be Applied to Real-Time Target Change Guided Weapon
맹성재 Sung-jae Maeng , 이종혁 Jong-hyuk Lee , 김강산 Kang-san Kim
23(2) 97-103, 2019
맹성재 Sung-jae Maeng , 이종혁 Jong-hyuk Lee , 김강산 Kang-san Kim
DOI: JANT Vol.23(No.2) 97-103, 2019
In this paper, we designed and fabricated a receiving modem that can be applied to guided weapons can change real-time targets with little effect of fading. The designed modem consists of synchronous detector, timing error estimator, timing recovery, differential decoder and viterbi decoder, and it’s implemented in FPGA so that it can be redesigned and modified according to requirements. The modem board was directly converted from IF frequency to baseband and converted into digital data through ADC. It is confirmed that it is applicable to the guided weapons that changing real-time targets through simulations, measurements and test.
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A Difference Analysis on Visual Approach Accessibility of Airline Pilots Based on Flight Experience including Non-parametric Statistical Test
이근영 Gun-young Lee , 황재갑 Jae-kap Hwang , 장지승 Ji-seung Jang
23(2) 104-113, 2019
이근영 Gun-young Lee , 황재갑 Jae-kap Hwang , 장지승 Ji-seung Jang
DOI: JANT Vol.23(No.2) 104-113, 2019
There are keen competitions among the air operators to recruit competent pilots, which could be adversely affect the safe operation of aircraft. This study is aimed to identify the correlation between the flight experience of the pilot of the air transport operator and competency on visual approach operation. About 2,400 sets of flight training data of several pilots of an air transport operator was analysed for this study. The analysis showed that most captains were able to make stabilized visual approach regardless of his/her flight experience of any type of aircraft, while the first officers were able to make a stabilized visual approach with more than 1,500 hours of flight experience for each rated type of aircraft. This should be considered during making policies for the supply and demand of pilots for the safe operation of air transport.
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The Effect on Safety Perception with Ultra Light UAV Pilot`s Educational Environment Satisfaction : Including the DREEM Model
정형훈 Hyung-hoon Jung , 김기웅 Kee-woong Kim , 최연철 Youn-chul Choi
23(2) 114-124, 2019
정형훈 Hyung-hoon Jung , 김기웅 Kee-woong Kim , 최연철 Youn-chul Choi
DOI: JANT Vol.23(No.2) 114-124, 2019
The drone market, an unmanned aerial vehicle, is rapidly expanding and developing into an important area related to the huge changes in the traffic system of the future. With various technologies on the fourth industrial revolution, including drones, mentioned at the Davos Forum in January 2016, interest in drones is emerging as an explosive demand for national certificates. The number of drone pilots, which was only 400 in 2015, is continuing to surpass 17,000 as of 2018. Therefore, this study analyzed the safety perception of the pilots based on the DREEM (Dundee ready environmental assessment) model designed to evaluate the educational environment along with the current state of drone education in Korea. This led to the conclusion that the high level of satisfaction of the pilot with the educational environment contributes to the overall safety perception, including compliance with procedures.
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Underwater Guidance System for AUV using Optical Sensor Array
손현중 Hyeon-joong Son , 최형식 Hyeung-sik Choi , 강진일 Jin-il Kang , 서주노 Joo-no Sur , 정성훈 Seong-hoon Jeong , 김준영 Joon-young Kim
23(2) 125-133, 2019
손현중 Hyeon-joong Son , 최형식 Hyeung-sik Choi , 강진일 Jin-il Kang , 서주노 Joo-no Sur , 정성훈 Seong-hoon Jeong , 김준영 Joon-young Kim
DOI: JANT Vol.23(No.2) 125-133, 2019
In this paper, a new study was performed on the docking of AUV to docking station using light and light sensor system under the water. For this, a guiding system for AUV loading sensor system composed of lense, light sensor, signal processor, and processor and docking system with LED are proposed. An analysis on light sensor system and light-collecting lense to obtain accurate relative angle and measurement accuracy was performed. To prove this, the system was built and a basic experiment was performed. Finally, the feasibility of the developed docking system was verified the test in the water tank.
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Design of Multi-Mode Radar Signal Processor for UAV Detection
이승혁 Seunghyeok Lee , 정용철 Yongchul Jung , 정윤호 Yunho Jung
23(2) 134-141, 2019
이승혁 Seunghyeok Lee , 정용철 Yongchul Jung , 정윤호 Yunho Jung
DOI: JANT Vol.23(No.2) 134-141, 2019
Radar systems are divided into the pulse Doppler (PD) radar and the frequency modulated continuous wave (FMCW) radar depending on the transmission waveform. In particular, the PD radar is advantageous for long-range target detection, and the FMCW radar is suitable for short-range target detection. In this paper, we present design and implementation results for a multi-mode radar signal processor (RSP) that can support both PD and FMCW radar systems to detect unmanned aerial vehicles (UAVs) at short distances as well as long distances. The proposed radar signal processor can be implemented based on Altera Cyclone-IV FPGA with 19,623 logic elements, 9,759 registers, and 25,190,400 memory bits. The logic elements and registers of the proposed radar signal processor are reduced by approximately 43% and 30%, respectively, compared to the sum of logic elements and registers of the conventional PD radar and FMCW radar signal processor.
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Removal of Clutter from Doppler Radar Signal to Measure Accurate Muzzle Velocity
김형래 Hyoung-rae Kim
23(2) 142-150, 2019
김형래 Hyoung-rae Kim
DOI: JANT Vol.23(No.2) 142-150, 2019
Muzzle Velocity is one of the most important measurement items for evaluation of ammunition. The muzzle velocity is defined as the velocity when the projectile leaves the muzzle. Particularly, since the muzzle velocity is closely related to the performance of the propellant, precise measurement of muzzle velocity is required. Doppler radar is used to measure the muzzle velocity, but the quality of Doppler radar signal depends on the test site environment. In this paper, a method to remove the clutter that degrades the signal quality of Doppler radar by improving the structure of the test site and the signal processing method is suggested. For the application of the improved signal processing method, a program for acquiring Doppler radar 's raw Doppler data was created. Statistical verification of the velocity data obtained through the improvement of the test site structure and signal processing method proved that the proposed method is effective for the removal of clutter as compared with the existing method.
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Analysis of Ka Band Satellite Link Budgets and Earth Station G/T in Korea Rainfall Environ
최형재 Hyeong-jae Choi , 유경아 Kyoung-a You , 박대길 Dae-kil Park , 구경헌 Kyung Heon Koo
23(2) 151-157, 2019
최형재 Hyeong-jae Choi , 유경아 Kyoung-a You , 박대길 Dae-kil Park , 구경헌 Kyung Heon Koo
DOI: JANT Vol.23(No.2) 151-157, 2019
In geostationary satellite communications, which are widely used for broadcasting and communication, there is a path loss where the signal power on the path is largely reduced. It is important to consider rain attenuation when calculating link budget because the Ka band frequency is vulnerable to rain attenuation. In this study, rainfall trends were analyzed by using rainfall data from the year 2000 in four regions of Korea (Seoul, Incheon, Busan, Jeju) and the rainfall attenuation was calculated. This was used to analyse the satellite link budget and receiving performance for the down-link of the korea satellite COMS. In this study, the calculated G/T for the rainfall intensity of 0.5% per year using the rainfall data for 18 years increased by approximately 8.5 dBK-1 compared to the ITU's zone-K rain model, and decreased by approximately 1 dBK-1 compared to the precipitation data for 13 years from the TTA(Korea Telecommunications Technology Association). The results of this study can be used for the design of G/T in domestic-installed satellite ground station.
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Design of Web Content Update Algorithm to Reduce Communication Data Consumption using Service Worker and Hash
김현국 Hyun-gook Kim , 박진태 Jin-tae Park , 최문혁 Moon-hyuk Choi , 문일영 Il-young Moon
23(2) 158-165, 2019
김현국 Hyun-gook Kim , 박진태 Jin-tae Park , 최문혁 Moon-hyuk Choi , 문일영 Il-young Moon
DOI: JANT Vol.23(No.2) 158-165, 2019
The existing web page was downloaded and provided to the user every time the user requested the page. Therefore, if the same page is repeatedly requested by the user, only the download for the same resource is repeated. This is a factor that causes unnecessary consumption of data. We focus on reducing data consumption caused by unnecessary requests between users and servers, and improving content delivery speed. Therefore, in this paper, we propose a caching system and an algorithm that can reduce the data consumption while maintaining the latest cache by comparing the hash value using the hash function that can detect the change of the file requested by the user.
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Performance Analysis of 6.78MHz Current Mode Class D Power Amplifier According to Load Impedance Variation
고석현 Seok-hyeon Go , 박대길 Dae-kil Park , 구경헌 Kyung-heon Koo
23(2) 166-171, 2019
고석현 Seok-hyeon Go , 박대길 Dae-kil Park , 구경헌 Kyung-heon Koo
DOI: JANT Vol.23(No.2) 166-171, 2019
This paper has designed a current mode class D power amplifier to increase the transmission efficiency of a 6.78 MHz wireless power transfer (WPT) transmitter and to ensure stable characteristics even when the transmitting and receiving coil intervals change. By reducing the loss due to the parasitic capacitor component of the transistor, which limits the theoretical efficiency of the linear amplifier, this research has improved the efficiency of the power amplifier. The circuit design simulator was used to design the high efficiency amplifier, and the power output and efficiency characteristics according to the load impedance change have been simulated and verified. In the simulation, 42.1 dBm output and 95% efficiency was designed at DC bias 30 V. The power amplifier was fabricated and showed 91% efficiency at the output of 42.1 dBm (16 W). The transmitting and receiving coils were fabricated for wireless power transfer of the drone, and the maximum power added efficiency was 88% and the output power was 42.1 dBm ± 1.7 dB according to the load change causing from the coil intervals.
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Passive Device Library Implementation of LTCC Multilayer Board for Wireless Communications
조학래 Hak-rae Cho , 구경헌 Kyung Heon Koo
23(2) 172-178, 2019
조학래 Hak-rae Cho , 구경헌 Kyung Heon Koo
DOI: JANT Vol.23(No.2) 172-178, 2019
This paper has designed, fabricated, and analyzed the passive devices realized using low temperature co-fired ceramic (LTCC) multi layer substrates by dividing into the shrinkage process and the non-shrinkage process. Using two types of ceramic materials with dielectric constant 7 or 40, we have fabricated the same shape of various elements in 2 different processes and compared the characteristics. For the substrate of dielctric constant 40, compared with the shrinkage process which has 17% shrink in the X and Y directions with 36% shrink in the Z direction, the non-shrinkage process has 43% shrink in the Z direction without shrink in the X and Y directions, so high dimensional accuracy and surface flatness can be obtained. The inductances and capacitances of the fabricated elements are estimated from measurement using empirical analysis equations of parameters and implemented as a design library. Depending on the substrate and the process, the inductance and capacitance depending on the turn number of winding and unit area have been measured, and empirical polynomials are proposed to predict element values.
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Narrow-Band Analog Pre-Distortion Linearization Technique using UHF 400 MHz Band 20 W Power Amplifier
하정완 Jung-wan Ha , 김강산 Kang-san Kim , 김효종 Hyo-jong Kim
23(2) 179-185, 2019
하정완 Jung-wan Ha , 김강산 Kang-san Kim , 김효종 Hyo-jong Kim
DOI: JANT Vol.23(No.2) 179-185, 2019
In this paper, we have studied narrow-band analog pre-distortion linearization technique using UHF 400 MHz band 20 W power amplifier. The analog pre-distorter used the SC1894 radio frequency power amplifier linearizer(RFPAL) provided by MAXIM Corp and through the look-up table technique confirmed the intermodulation distortion(IMD) performance and the adjusted channel leakage ratio(ACLR) improvement for bandwidth below 1 MHz which does not operate on existing chips. In the 400 MHz (400 ~ 500 MHz) band, IMD performance and the ACLR improvement of up to 17.46 dB based on 1-channel offset and up to 16.6 dB based on 2-channel offset were confirmed. In the system requiring the same linearity, we confirmed power efficiency improvement of 12.41% at output power of over 40 W.
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Design of a Simple PCM Encoder Architecture Based on Programmable ROM
김건희 Geon-hee Kim , 진미현 Mi-hyun Jin , 김복기 Bok-ki Kim
23(2) 186-193, 2019
김건희 Geon-hee Kim , 진미현 Mi-hyun Jin , 김복기 Bok-ki Kim
DOI: JANT Vol.23(No.2) 186-193, 2019
This paper presents and implements a simple programmable PCM encoder structure uisng the commutation method. In the telemetry system, information is required to assign each data to the channel in order to generate a frame format the data acpuired from the sensor. In this case, when the number of state information is large or the data type is various, there is a necessity to input a large amount of information to each channel. However, the more the number of channels and data, the more probability the error will occur. Therefore, in this paper, the channel information is created using the program. And PCM encoder was implemented to store channel information in ROM. The proposed PCM encoder architecture reduces the likelihood of errors. And it can improve the development speed. The validity of proposed structure is proved by simulation.
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The Improvement of Disaster Safety Network using ICT Devices
홍성화 Sung-hwa Hong
23(2) 194-199, 2019
홍성화 Sung-hwa Hong
DOI: JANT Vol.23(No.2) 194-199, 2019
Natural disasters destroy decades of human effort and investments, thereby placing new demands on society for reconstruction and rehabilitation. In most case, the natural phenomena triggering the disasters are beyond human control. In order to solve the problems that the information resources can not be shared among disaster management sectors and their work is hard to be coordinated in city, an idea of application of ubiquitous sense network and ICT technology to model the architecture of the disaster prevention system based on the analysis of characteristics of disasters. The proposed algorithm simulated that it is possible to locate the terminal by linking the direction angle and the estimated position that can be confirmed at the time of stopping, even if the movement direction of the terminal does not move in a certain direction with only a smaller number of mobile base stations. We also confirmed that the proposed algorithms analyzed through simulation are more efficient than existing algorithms.
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Forklift Weight Measurement System using Anchor Bolt Type Strain Gauge Sensor
한치문 Chi-moon Han , 임춘식 Choon-sik Yim , 이성렬 Seong-real Lee
23(2) 200-206, 2019
한치문 Chi-moon Han , 임춘식 Choon-sik Yim , 이성렬 Seong-real Lee
DOI: JANT Vol.23(No.2) 200-206, 2019
The most frequent type of safety-accident in industry is the overturning of forklift . The leading cause of this accident is overload in forklift. Thus, it is needed to measure the weight on board of forklift. The most common method is based on load cell, and this method has the merit of high accuracy. However, high price is the disadvantage of this method. In this paper, we propose the new measurement system of the weight on board of forklift based on the strain gauge sensor, which has the disadvantage of low accuracy. The differentiation of the proposed system is that the shape of the strain gauge sensor customized for anchor bolt of forklift in order to improve the accuracy and durability. In system four strain gauge sensors are inserted into four anchor bolts. The test result shows that 1% error of measurement is obtained in the proposed anchor bolt type strain gauge sensors.
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Design of Crypto-processor for Internet-of-Things Applications
안재욱 Jae-uk Ahn , 최재혁 Jae-hyuk Choi , 하지웅 Ji-ung Ha , 정용철 Yongchul Jung , 정윤호 Yunho Jung
23(2) 207-213, 2019
안재욱 Jae-uk Ahn , 최재혁 Jae-hyuk Choi , 하지웅 Ji-ung Ha , 정용철 Yongchul Jung , 정윤호 Yunho Jung
DOI: JANT Vol.23(No.2) 207-213, 2019
Recently, the importance for internet of things (IoT) security has increased enormously and hardware-based compact chips are needed in IoT communication industries. In this paper, we propose low-complexity crypto-processor that unifies advanced encryption standard (AES), academy, research, institute, agency (ARIA), and CLEFIA protocols into one combined design. In the proposed crypto-processor, encryption and decryption processes are shared, and 128-bit round key generation process is combined. Moreover, the shared design has been minimized to be adapted in generic IoT devices and systems including lightweight IoT devices. The proposed crypto-processor was implemented in Verilog hardware description language (HDL) and synthesized to gate level circuit in 65nm CMOS process, which results in 11,080 gate counts. This demonstrates roughly 42% better than the aggregates of three algorithm implementations in the aspect of gate counts.
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Error Calibration of Initial Value of Weight Measuring Sensors with Different Feature of Forklift
한치문 Chi-moon Han , 임춘식 Choon-sik Yim , 이성렬 Seong-real Lee
23(2) 214-220, 2019
한치문 Chi-moon Han , 임춘식 Choon-sik Yim , 이성렬 Seong-real Lee
DOI: JANT Vol.23(No.2) 214-220, 2019
The calibration method of the initial value error obtained in the weight measurement through anchor bolt type strain gage sensor is proposed. The strain gauge sensor is developed for preventing the overturning of forklift, which is the most frequent type of safety-accident in industry. It was confirmed that the initial value error is caused from the physical and mechanical error of anchor bolt, and the environmental problem. Since the elimination of these causes falls outside the realm of this research, we find out the calibrated values based on all the causes, and we adjust the initial values of analog-to-digital convertor (ADC) module consisted of strain gauge sensor block using the calibrated values. We use the linear interpolation method for our calibration. We confirm that four sensor modules have the different under 5% between the real weight and the measured value in the experiment applied with the calibration of initial values. The low correlation between the real weights and ADC values is also improved through the proposed calibration.
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