• Journal of Institute of Control, Robotics and Systems
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• v.21 no.7
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• pp.691-698
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• 2015

Inertial Navigation Systems (INS) are widely used as the main navigation device for aircraft. To get the initial attitude, the INS requires the initial alignment before navigation starts. An aircraft also needs an engine test procedure that causes some vibrations before flight. An INS can't be aligned in a vibration environment so the initial alignment is performed before the aircraft engine test. Therefore, the initial alignment time of an INS has been a major factor in limiting an aircraft's takeoff response time. In this paper, we designed an initial alignment algorithm that can be executed even in disturbances such as aircraft run-up. We demonstrated verification of the algorithm that is embedded on the real INS and testing methods to evaluate the alignment of the INS. We also analyzed the test results of the proposed initial alignment algorithm that is performed during a real aircraft run-up.

• Journal of the Korea Institute of Military Science and Technology
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• v.27 no.3
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• pp.387-394
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• 2024

This paper describes a progressive test and evaluation strategy for verification of Korean Fighter eXperimental (KF-X) AESA(Active Electronically Scanned Array) radar development. Three progressive stages of development test and evaluation were officially performed from simulated test conditions to actual operating conditions according to standards: radar function/performance and avionics integration. KF-X AESA radar development is repeatedly verified by progressive stages consisting of five tests: Roof-lab ground test, System Integration Laboratory(SIL) ground test, Flying Test Bed(FTB) test, KF-X ground test, and KF-X flight test. As a result, the risk factor decreases as stages and tests progress. Therefore, development test and evaluation of KF-X AESA radar are successfully performed at low development risk.

• Journal of Industrial Technology
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• v.18
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• pp.35-41
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• 1998

A watershed terrain factor is known to the very important in studies of a stream and a watershed. We have obtained the terrain factor in map directly or we have generated it in a digitalized map. In this study, DTED(Digital Terrain Elevation Data) offering in DMA(Defense Mapping Agency) was used to create a stream and a watershed and to extract the terrain factor. As comparison of the factors gererated in digitalized map the terrain factors extracted in DTED, DTED could be used to extract a terrain factor for a watershed management.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.15 no.3
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• pp.281-299
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• 2017

The inventory management of radionuclides is essential for the safe management of disposal facilities. In this study, we compared the activity of dry active waste predicted using the generated waste data and that measured for the accepted waste in the disposal facility. For very low level waste, the measured activity was higher than the predicted activity for $^{137}CS$, $^{90}Sr$, $^{99}Tc$ and $^{129}I$. In low level waste, the predicted activity was higher than the measured activity for all radionuclides. We also evaluated the variation in the predicted quantity and total activity of each level of dry active waste through a sensitivity analysis on a scaling factor. This result will contribute to the construction of a Safety Case and safe operation of disposal facilities.

• Korean Chemical Engineering Research
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• v.44 no.6
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• pp.636-643
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• 2006

Supercritical water oxidation of DMMP using continuous flow reactor was studied at temperature ranging from 440 to $540^{\circ}C$ and a fixed pressure of 242 bar. The range of residence times in the reactor was from 10 to 26 s, and oxygen excess value varied from -40 to 200%. Destruction efficiencies (DE) of DMMP were greater than 99.7% at $540^{\circ}C$, and increased as the DMMP concentrations were increased. DE of DMMP were significantly affected by oxygen concentration under stoichiometric amount, but showed little difference over stoichiometric amount. On the basis of 30 data with conversions greater than 85%, kinetic correlations for the DE of DMMP were developed. The pre-exponential factor was $(1.10{\pm}0.76){\times}10^6$, and the activation energy was $90.66{\pm}3.87kJ/mol$, and the reaction orders for DMMP and oxygen were $1.02{\pm}0.03$, $0.32{\pm}0.03$, respectively. The model predictions agreed well with the experimental data.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.2
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• pp.107-118
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• 2012

Objectives: This study examines the occurrence of disease resulting from low back pain and factors of working environment meaningfully influencing the occurrence of lumbago as well as analyzes '2nd Korean Working Condition Survey (KWCS)' conducted in 2010 so as to establish the prevention and improvement measures. Methods: The analysis method is that it is to compare the prevalence rate of low back pain according to working environment via odds ratio and to implement the test about the factors having the difference in working environment between low back pain group and normal group through weighted t-test. Results: As a result, it indicates that there is a meaningful difference for prevalence rate of low back pain according to age, status in employment and education level which are socio-demographical factors. The analysis in working hours shows that the period of work is a factor raising the prevalence rate of low back pain rather than weekly working hours. The analysis in the work risk factor indicates that the increase in prevalence rate of low back pain takes place to either workers with repetitive movement and continuously standing posture or those with heavy stress and emotional labour. Conclusions: Workers with low back pain have suffered from accident, depression, anxiety disorder and sleep. The factors in which the prevalence rate of low back pain decrease are to provide information on health and safety and working speed, and enough rest.

• Journal of Life Science
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• v.28 no.6
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• pp.738-744
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• 2018

Sasa quelpaertensis Nakai is a native Korean plant that grows only on Mt. Halla of Jeju Island. Its leaf is used for a popular bamboo tea due to its various health-promoting properties, and it has been increasingly used as food and cosmetic ingredients. To utilize the S. quelpaertensis leaf efficiently, the preparation method for phytochemical-rich extract (PRE) using the leaf's residue was previously reported, which was produced after hot water extraction. This study was undertaken to evaluate the anti-oxidant and anti-inflammatory potential of PRE and its solvent fractions. The ethyl acetate fraction of PRE (EPRE) showed higher DPPH, ABTS, and superoxide radical scavenging activities, and it effectively inhibited intracellular reactive oxygen species (ROS) and nitric oxide (NO) production in lipopolysaccharides (LPS)-stimulated RAW 264.7 cells. EPRE also induced the expression of heme oxygenase-1 (HO-1) by increasing the level of nuclear factor E2-related factor 2 (Nrf2) in a nuclear fraction. The inhibiting effect of EPRE on LPS-induced NO production was partially reversed by the HO-1 inhibitor (zinc protoporphyrin, ZPP), suggesting that HO-1 is involved in suppressing NO production. Taken together, the results suggest that EPRE has potential as a promising anti- oxidant and anti-inflammatory agent.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.34 no.1
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• pp.67-76
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• 2024

Objectives: Direct reading instruments (DRIs) are widely used by industrial hygienists and other experts for preliminary survey and identifying source locations in many industrial fields. Photoionization detectors (PIDs), which are a form of hand-held portable DRIs, have been used for a variety of airborne vaporized chemicals, especially evaporated hydrocarbon solvents. The benefits of PIDs are high sensitivity between each chemical, competitive price, and portability. With the goal of increasing the accuracy of logged PID concentrations, previous studies have performed tests for the assessment of single chemical compounds, not mixtures. The purpose of this preliminary study was to measure mixtures with a PID and charcoal tube at the same time and compare the accuracy between them. Methods: A chamber test was implemented with different mixtures of hydrocarbon chemicals (acetone, isopropyl alcohol, toluene, m-xylene) and levels in the range of 14 to 864 ppm. Three PIDs and charcoal tubes were connected to the chamber and measured the chemical mixtures simultaneously. A comparison of accuracy and the PID group of concentrations with manufacture correction factor (M_CF) and field correction factor (F_CF) applied was performed. Results: The accuracy of the PID concentrations data-logged from the PID did not meet the accuracy criteria except for the mixture level B and C logged from PID No. 2, which was 18% of all tests for meeting accuracy criteria. The mean and standard deviation (SD) of concentration (ppm) of the charcoal tube followed by each mixtures' level were 10.37±0.26, 155.33±5.28, 300.80±11.65, and 774.93±22.65, respectively. When applying F_CF into the PID concentrations, the accuracy increased by nearly 82%. However, in the case of M_CF, none met the accuracy criterion. Between the PID there were differences of logged concentrations. Conclusions: In this preliminary study, the concentration of a logged PID with F_CF applied was a better way to increase accuracy compared to applying M_CF. We suggest that additional research is necessary to consider environmental factors such as temperature and humidity.

• Journal of the Korean Society of Safety
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• v.35 no.2
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• pp.47-54
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• 2020

The purpose of this study is to determine whether the variables of the agency factors affected the number of occupational fatalities in the construction industry in order to determine whether there is a relationship between the number of occupational fatalities occurring at the construction sites and the agency. The considered agencies are KOSHA (Korea Occupational Safety and Health Agency) and MOEL (Ministry of Employment and Labor). The variables of two agency factors are classified as follows: the variables of two agency factors are the number of employees, budget amounts, technical support and guidance for construction sites of KOSHA, and the number of labor inspectors, the number of inspection and oversight workplace, the number of criminally punished construction sites and fines levied on them in the industrial accident prevention departments of Regional Employment and Labor Office. The multiple regression analysis was conducted to determine the effect of two agency factors on the total number of occupational fatalities in the construction industry. The policy implications derived from this study are that, in order to reduce the fatalities of construction sites by KOSHA, the appropriate level of increased budget for KOSHA must be secured every year. In addition, the amount of fines levied on construction sites by the labor inspector in the industrial accident prevention departments of Regional Employment and Labor Office reduces the occupational fatalities at the construction sites.

• Journal of the Korea Institute of Military Science and Technology
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• v.18 no.4
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• pp.387-394
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• 2015

We have recently developed a cost-effective and pouch-type chemical vapor sampler which consists of a selectively permeable high density polyethylene(HDPE) membrane, aluminum/nylon barrier film, and adsorbents. Since the sampler mimics the actual adsorption process that occurs when the skin is exposed to chemical vapors, it can be applied to man-in-simulant test(MIST) to determine the protective capability of individual protective ensembles for chemical warfare agents. In this study, we describe the manufacturing process of samplers and results for performance testing on MIST. Methyl salicylate(MeS) is used to simulate chemical agent vapor and the vapor sampler was used to monitor chemical concentration of MeS inside the protective suit system while worn. Values of protection factors(PF) were also analyzed to provide an indication of the protection level of the suit system evaluate by MIST. The results obtained by home-made samplers(ADD samplers) and commercially avaliable ones(Natick samplers) showed no significant differences.