• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.5
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• pp.630-636
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• 2020

This study reviewed camouflage techniques to reduce the visual detect-ability of aircraft. Visual camouflage can be defined as the process of making objects less visible. Aircraft visual camouflage delays detection of the aircraft position, speed, and flight direction. Multi-tone and counter-shaded schemes are generally adopted as camouflage patterns for close-air-support aircraft and air-superiority aircraft, respectively. Another study showed that the monotone scheme is also efficient when the hue and brightness of the camouflage color are controlled correctly. Active camouflage techniques for aircraft have been studied to increase the camouflage effectiveness. In particular, counter-illumination techniques using electroluminescence devices can minimize the difference in brightness between the aircraft and sky background. Active camouflage techniques are expected to enhance the survivability of low-altitude UAVs, which are vulnerable to visual detection.

• Journal of Science and Technology Studies
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• v.11 no.2
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• pp.31-66
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• 2011

The main issue in Korean debates over genetically modified (GM) foods have been government's responsibility to guarantee consumers' right-to-know and make informed choice. Counter-experts' critique over the current regulatory processes based upon substantial equivalence have not been widely publicized. Through interviews and textual analysis, this paper explored three groups' performances in Korean GM food controversies-regulatory scientists, civil society organizations, and counter-experts. Analytic focus was made upon how each of the groups interact with current GM food regulations. While making conflicts with regulatory scientists and their 'discourse of compliance with global standards,' counter-experts were excluded from regulatory processes. This article suggests that the processes and contexts in which counter-experts failed to form strong alliance with other groups need to be examined in order to further understand the specific contours of Korean GM food controversies.

• Journal of the Korean Electrochemical Society
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• v.11 no.1
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• pp.51-58
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• 2008

Many researches for effects of different flow configurations on performance of Proton Exchange Membrane Fuel Cell have extensively been done but the effects of flow direction at the same flow channel shape should be considered for optimal operation of fuel cell as well. In this paper a numerical computational methode for simulating entire reactive flow fields including anode and cathode flow has been developed and the effects of different flow direction at parallel flow was studied. Pressure drop along the flow channel and density distribution of reactant and products and water transport, ion conductivity across the membrane and I-V performance are compared in terms of flow directions(co-flow or counter-flow) using above numerical simulation method. The results show that the performance under counter-flow condition is superior to that under co-flow condition due to higher reactant and water transport resulting to higher ion conductivity of membrane.

• Korean Journal of Applied Biomechanics
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• v.27 no.1
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• pp.1-7
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• 2017

Objective: The purpose of this study was to analyze the relationship between ground reaction force (GRF) and attack time according to the position of hand segments during counter attack in Kendo. Method: The participants consisted of 10 kendo athletes (mean age: $21.50{\pm}1.95yr$, mean height: $175.58{\pm}5.02cm$, mean body weight: $70.96{\pm}9.47kg$) who performed standard head strikes (A) and counter attack with a preferred hand position of +10 cm (B), 0 cm (C), and -10 cm (D). One force-plate (AMTI-OR-7., USA) was used to collect GRF data at a sample rate of 1,000 Hz. The variables analyzed were the attack time, medial-lateral GRF, anterior-posterior GRF (AP GRF), peak vertical force (PVF), and loading rate. Results: The total attack time was shorter in types A and C than in types C and D. The AP GRF, PVF, and loading rate had significantly higher forces in types C and D than in types A and C. The attack time (bilateral and unilateral leg support and total) was positively correlated with the GRF variables (vertical GRF and loading rate) during the counter attack in Kendo (r = 0.779 [$R^2=0.607$], p < 0.001). Conclusion: The positions of the hand segments can be changed by various conditions of the opponent in Kendo competitions; however, the position preferred by an individual can promote the successful ratio of the counter attack.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.10
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• pp.1281-1292
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• 2001

Experiments were done for the comparison of performance and flow characteristics between a two -stage axial flow fan and a counter-rotating axial flow fan. Each stage of the two -stage axial flow fan used fur the present study has an eight bladed rotor and thirteen slater blades. The front and the rear rotor of the counter - rotating axial flow fan have eight blades each and are driven by coaxial counter ro latins shafts through a gearbox located between the rear rotor and the electric motor. Both of the two axial fan configurations have identical rotor blades and the same operating condition fur the one -to-one comparison of the two. Performance curves of the two configurations were obtained and compared by varying the blade pitch angles and axial gaps between the blade rows. The fan characteristic curves were obtained following the Korean Standard Testing Methods for Turbo Fans and Blowers (KS B 6311). The fa n flow characteristics were measured using a five-hole probe by a non-nulling method. The velocity profiles between the hub and tip of the fans were measured and analyzed at the particular operating condition s of peak efficiency, minimum and maximum pressure coefficients. The peak efficiency of the counter-rotating axial fan was improved about 2% respectively, compared with the two stage axial fan. At the minimum pressure coefficient point of the two stage axial fan, the fan inlet flow patterns show that axial velocity highly decreased in the vicinity of the blade tip region. Also, the reverse flow took place at the blade tip.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.24 no.4
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• pp.333-339
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• 2011

In this work, electrochemical characteristics and optical transmittance of carbon nanotubes (CNTs) counter electrodes which had different amount of CNTs in CNTs slurries were analyzed. Two-step heat treatment processes were applied to achieve well-fabricated CNTs electrode. Three sets of CNTs electrodes and dye-sensitized solar cells (DSSCs) with CNTs counter electrodes were prepared. As the amount of CNTs increased, sheet resistance of CNTs electrode decreased. CNTs electrode with low sheet resistance had low electrochemical impedance and fast redox reaction. On the other hand, in case of CNTs counter electrode with low density of CNTs, performance of the dye-sensitized solar cell was improved due to its high optical transmittance. We found that the transmittance of CNTs counter electrode influence the performance of dye-sensitized solar cells.

• Korean Journal of Veterinary Service
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• v.16 no.1
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• pp.1-10
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• 1993

Samples of bulk herd milk, foremilk, last milk (stripping) and individual cow sample were collected and their somatic cell number were counted with Fossomatic counter (FCC), Coulter counter(CC), direct microscopic somatic cell count(DMSCC) and Califormia mastitis test (CMT), The results were compared and summarized as follows : 1. Mean somatic cell counts of 120 bulk herd milk samples obtained by DMSCC, FCC and CC were 433,203, 481,213 and 676,245 respectively. 2. Mean somatic cell counts of 116 foremilk samples obtained by DMSCC, FCC and CC were 515,035, 611,845 and 725,051 respectively 3. Mean somatic cell counts of 87 last milk samples obtained by DMSCC, FCC and CC were 718,506, 839,874 and 1,041,160 respectively. 4. Mean somatic cell counts of 57 individual cow samples obtained by DMSCC, FCC and CC were 449,258, 491,018 and 521,315 respectively. 5. Mean somatic cell counts of all samples increased with the increasing CMT score, and the cell counts were higher by CC than by FCC. 6. The correlation coefficients between the somatic cell counts by CMT and CC were 0.926 in bulk herd milk, 0.707 in foremilk 0.688 in last milk and 0.675 in individual cow sample, respectively 7. The correlation coefficients between the somatic cell counts by CMT and FCC were 0. 945 in bulk herd milk, 0.705 in foremilk 0.694 in last milk and 0.727 in individual cow sample, respectively. 8. The correlation coefficients between the somatic cell counts by CC and FCC were 0.978 in bulk herd milk, 0.997 in foremilk 0.983 in last milk and 0.985 in individual cow sample, respectively.

• KIPS Transactions on Computer and Communication Systems
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• v.8 no.6
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• pp.151-158
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• 2019

FLUSH+RELOAD attack exposes the most serious security threat among cache side channel attacks due to its high resolution and low noise. This attack is exploited by a variety of malicious programs that attempt to leak sensitive information. In order to prevent such information leakage, it is necessary to detect FLUSH+RELOAD attack in real time. In this paper, we propose a novel run-time detection technique for FLUSH+RELOAD attack by utilizing PCM (Performance Counter Monitor) of processors. For this, we conducted four kinds of experiments to observe the variation of each counter value of PCM during the execution of the attack. As a result, we found that it is possible to detect the attack by exploiting three kinds of important factors. Then, we constructed a detection algorithm based on the experimental results. Our algorithm utilizes machine learning techniques including a logistic regression and ANN(Artificial Neural Network) to learn from different execution environments. Evaluation shows that the algorithm successfully detects all kinds of attacks with relatively low false rate.

• Journal of the Society of Disaster Information
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• v.15 no.1
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• pp.49-66
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• 2019

Purpose: This study aims to apply the counter terrorism policy in pertain to malicious drone abuse and the croweded public places in South Korea. And, to improve counter terrorism protection measure, this study suggests an adoptation of Anti UAV technology into counter terrorism related regulation. Method: Compared to nations' operations of counter terrorism prevention and protection activities with the South Korean gov, problems and limitations are suggested. Results: Anti UAV technology could not be applied for Multi-user facilities by any law due to the limitation, so that it is required to amend counte terrporism related policies and law. Conclusion: This study intends to identify various protection methods against UAV threats. To reduce the risk of UAV, the law of public safety and counter terrorism should be promoted and reinforced for the first.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.4
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• pp.588-594
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• 2021

SIMON, a lightweight block cipher developed by the US National Security Agency, is a family of block ciphers optimized for hardware implementation. It supports many kinds of standards to operate in various environments. The counter mode of operation is one of the operational modes. It provides to encrypt plaintext which is longer than the original size. The counter mode uses a constant(Nonce) and Counter value as an input value. Since Nonce is the identical for all blocks, so it always has same result when operates with other constant values. With this feature, it is possible to skip some instructions of round function by pre-computation. In general, the input value of SIMON is affected by the counter. However in an 8-bit environment, it is calculated in 8-bit units, so there is a part that can be pre-computed. In this paper, we focus the part that can be pre-calculated, and compare with previous works.