• Journal of IKEEE
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• v.24 no.2
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• pp.468-474
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• 2020

This paper describes the hardware implementation of SPECK, a lightweight block cipher algorithm developed for the security of applications with limited resources such as IoT and wireless sensor networks. The block cipher SPECK crypto-core supports 8 block/key sizes, and the internal data-path was designed with 16-bit for small gate counts. The final round key to be used for decryption is pre-generated through the key initialization process and stored with the initial key, enabling the encryption/decryption for consecutive blocks. It was also designed to process round operations and key scheduling independently to increase throughput. The hardware operation of the SPECK crypto-core was validated through FPGA verification, and it was implemented with 1,503 slices on the Virtex-5 FPGA device, and the maximum operating frequency was estimated to be 98 MHz. When it was synthesized with a 180 nm process, the maximum operating frequency was estimated to be 163 MHz, and the estimated throughput was in the range of 154 ~ 238 Mbps depending on the block/key sizes.

• Geophysics and Geophysical Exploration
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• v.8 no.2
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• pp.184-190
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• 2005

We have attempted to give some physical into the factors that control the response of subsurface target to plane wave excitation at VLF (very low frequency) frequencies. Although the VLF technique has some serious disadvantages, such as a lack of penetration depth and limited frequencies, its advantages are also extremely important to have made it by far the most popular electromagnetic technique in current use. In the magnetic-field measurement mode these lightweight, relatively low-priced tools allow us to survey large areas rapidly and inexpensively, to locate and roughly define subsurface electrical conductors. When used in the electric-field mode the technique is, in simple environments, capable of quantitative interpretation and once again the speed and relative cheapness of these devices makes them a natural 'first electromagnetic tool ' to use in reconnaissance mapping.

• Journal of IKEEE
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• v.22 no.3
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• pp.522-531
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• 2018

A public-key cryptography processor EC-RSA was designed, which integrates a 224-bit prime field elliptic curve cryptography (ECC) defined in the FIPS 186-2 as well as RSA with 2048-bit key length into a single hardware structure. A finite field arithmetic core used in both scalar multiplication for ECC and exponentiation for RSA was designed with 32-bit data-path. A lightweight implementation was achieved by an efficient hardware sharing of the finite field arithmetic core and internal memory for ECC and RSA operations. The EC-RSA processor was verified by FPGA implementation. It occupied 11,779 gate equivalents (GEs) and 14 kbit RAM synthesized with a 180-nm CMOS cell library and the estimated maximum clock frequency was 133 MHz. It takes 867,746 clock cycles for ECC scalar multiplication resulting in the estimated throughput of 34.3 kbps, and takes 26,149,013 clock cycles for RSA decryption resulting in the estimated throughput of 10.4 kbps.

• Journal of Advanced Navigation Technology
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• v.15 no.2
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• pp.181-188
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• 2011

A small UAVs(Unmaned Aerial Vehicles) have limited by the payload capacity which requires miniaturization of a navigation system. In this paper, the performance of the lightweight and small sized AHRS(Attitude Heading Reference System), which is self-developed, is evaluated at low acceleration environment. The designed AHRS adopts the commercial low-cost MEMS sensors. A quaternion-based attitude calculation method, which eliminates singularity with relatively simple algebra, is used. In an attitude correction algorithm, the Kalman filter is used with accelerometers and magnetometers combined. The fabricated AHRS is also evaluated with reference to a COTS(Commercial Off-The-Shelf) AHRS which reports a number of successful applications to a small UAVs. The test results show that the measurements from the fabricated AHRS provide proper attitude output data with acceptable amount of differences(horizontal axis 0.5$^{\circ}$, vertical axis 1.5$^{\circ}$) in test environment.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.5
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• pp.513-520
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• 2014

An unmanned aerial vehicle (UAV) should be designed to be as small and lightweight as possible to optimize the efficiency of changing the blade shape to enhance the aerodynamic performance, such as the thrust and power. In this study, a computational fluid dynamics (CFD) simulation of an unmanned multi-rotor aerial vehicle in hover mode was performed to explore the thrust performance in terms of the blade rotational speed and blade shape parameters (i.e., taper ratio and twist angle). The commercial ADINA-CFD program was used to generate the CFD data, and the results were compared with those obtained from blade element theory (BET). The results showed that changes in the blade shape clearly affect the aerodynamic thrust of a UAV rotor blade.

• Journal of Fashion Business
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• v.18 no.2
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• pp.148-165
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• 2014

The purpose of this study is to establish a theory about the necessary structure for knitwear design, and to propose it with the practical data through the actual development of a high value added knit structure. For this study, the market was conducted along with literature reviews on the existing studies and the relevant books about knit structures. The market research aimed at the products released in the spring/summer and fall/winter seasons of 2012-2013, focusing on brand for middle aged women. The utilization of the structure by item and the characteristics of knit design were studied. The research was conducted on S/S products in May and July, and F/W products in October and December. As a result of the market research, it was shown that the lightweight structures with permeability such as plain, lace, links and links, this is repeated and rib structure were frequently utilized during the S/S season, while double structures with good shape stability were greatly utilized during the F/W season. Also, during the F/W season, a cable structure and tubular jacquard that emphasized the volume or cubic effect were frequently used, and there were many jacquard structures where a change of color sense and motive were added. Concerning the knit structures development, the researcher designed the knit structure at the actual production site of the knit fashion. A total of 5 pieces of knit structures were developed by asking a professional for programming and knitting. To the developed structures, the study added a multi-gauged effect, herringbone transformation effect, 3-dimensional surface effect, color effects, geometric patterns, lace penetration effect, and soft surface effect in a water-drop shape. In addition, the structures had differences in the added values by mixing various structures and diversely expressing color sense on the knitting line. This study proposes the direction for 21st century knitwear product design, through the development of a high value added knit structure.

• Fashion & Textile Research Journal
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• v.18 no.2
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• pp.184-193
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• 2016

This study investigates the recognition and preference of functional textile material about outdoor clothing widely used in the current fashion market. The study targeted 216 males and females in their 20s to 50s who wear outdoor clothing as casual wear. To analyze data, frequency analysis, cross tabulation analysis and ANOVA were conducted with the SPSS 21.0 statistical package. The results are as follows. First, recognition of functional textile material of outdoor clothing showed that 20s was the lowest preference and all age groups preferred lightweight textile material. In information recognition of functional outdoor clothing, 40s showed the highest recognition, while 20s showed the lowest recognition. Second, 40s and 50s preferred functional material to 20s and 30s. In particular, 40s and 50s preferred clothing items with water vapor permeability & water repellent material to 20s and 30s. All age groups preferred insulation material jumpers, water vapor permeability & water repellent material jumpers and stretch pants. Third, reasons for purchasing functional material clothing was: design for the age group 20s and 30s versus health and function for the age group 40s and 50s. It is necessary to develop functional clothing products based on exact consumer information and preferences.

• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.1
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• pp.117-126
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• 2020

The area of facility horticulture in Korea is increasing rapidly, the single-span pipe house which uses galvanized steel pipe as the main rafters occupies 78.7% of the facility area. Lightweight structures such as the single-span pipe house are vulnerable to meteorological disasters such as strong winds, economic losses of the state, local governments and farmers are continuing as construction does not meet the design standards. In order to minimize economic losses in the horticultural specialty facilities sector, the Rural Development Administration has been operating the horticultural disaster resilient standard for horticultural specialty facilities since April 2007. The only standard for the pipe connector is the disaster resilient standard, there is no standard for the uplift capacity of the house pipe foundation and the research on it is also insufficient. The purpose of this study is to investigate the characteristics of uplift capacity according to the foundation type, compaction ratio and embedded depth through soil box test. The results of the maximum uplift capacity according to the type, compaction ratio and embedded depth can be used as the basic data for the basic design of the pipe house conforming to the disaster resilient standard. Due to the limitation of soil box test, it may be different from the behavior of pipe house installed on site. In the future, the field test and the actual pipe house should be made and supplemented by comparing this result with the field test values.

• Journal of the Korea institute for structural maintenance and inspection
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• v.16 no.4
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• pp.107-115
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• 2012

The present study evaluates the validity of different equations specified in code provisions and proposed by the existing researchers to predict the concrete tensile capacities (direct tensile strength, splitting tensile strength and modulus of rupture) using a comprehensible database including 361 lightweight concrete (LWC), 1,335 normal-weight concrete (NWC) and 221 heavy-weight concrete (HWC) specimens. Most of the equations express the concrete tensile strengths as a function of its compressive strength based on the limited NWC concrete test data. However, the present database shows that the concrete tensile capacities are significantly affected by its unit weight as well. As a result, the inconsistency between experiments and predictions by the different models increases when the concrete unit weight is below 2,100 kg/$m^3$ and concrete compressive strength is above 50 MPa. On the other hand, new models proposed by the present study considering the concrete unit weight predict the tensile strengths of concrete with more accuracy.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.6A
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• pp.399-408
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• 2011

Development of smart sensors for structural health monitoring and damage detection has been advanced remarkably in recent years. Nowadays fiber optic sensors, especially fiber Bragg grating (FBG) sensors, have attracted many researchers' interests for their attractive features, such as multiplexing capability, durability, lightweight, electromagnetic interference immunity. In this paper, a damage detection approach of jacket-type offshore structures by principal component analysis (PCA) technique using FBG sensors are presented. An experimental study for a tidal current power plant structure as one of the jacket-type offshore structures was conducted to investigate the feasibility of the proposed method for damage monitoring. It has been found that the PCA technique can efficiently eliminate environmental effects from measured data by FBG sensors, resulting more damage-sensitive features under various environmental variations.