• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.12
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• pp.2410-2416
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• 2016

Recently, most countries in the world have pursued a denuclearization. So it has been of interest to increase to Nuclear weapon in such as North Korea's continued nuclear test. Pulsed gamma rays produced in the nuclear explosion and the space environment can give the big damage to the electronic device in a very short period of time. To confirm the extent of damage of these electronic devices, pulsed gamma irradiation facility that can occur in nuclear weapon or space environment are required. In this paper, we implemented the pulsed gamma-ray detection module and analyzed output of the irradiation test. We have experimented using an electron beam accelerator research facilities in Pohang Accelerator similar conditions to equip and Nuclear weapon. As a result, we confirmed that the pulsed gamma rays emitted by the gamma radiation and electron beam conversion device. The results of this paper will contribute to improve the reliability and accuracy of studies for utilizing pulsed gamma rays.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.12
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• pp.1166-1173
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• 2011

Electro-Mechanical Ignition Safety Device(EMISD) for solid rocket motor is designed and manufactured. The EMISD utilizes a true rotary solenoid for arming mechanism and an electric squib(initiator) for generating ignition energy. In order to prove the ignition capability of the EMISD, 10-cc Closed Bomb Test(CBT) is performed, which measures the pressure built by high temperature and high pressure gas generated by operating EMISD. The pressure built in the free volume of 10-cc closed bomb and the opening time of the ignition gas outlet are calculated using one dimensional gas dynamic model which is composed of the ideal gas equation and mass-energy conservation equation. Comparing the test result with model prediction, it is realized that the pressure built in the free volume of closed bomb due to the firing of EMISD, has the efficiency ratio of about 34%.

• The Bulletin of The Korean Astronomical Society
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• v.37 no.1
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• pp.90.2-90.2
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• 2012

Geosynchronous electron flux dropouts are most likely due to fast drift loss of the particles to the magnetopause (or equivalently, the "magnetopause shadowing effect"). A possible effect related to the drift loss is the radial diffusion of PSD due to gradient of PSD set by the drift loss effect at an outer L region. This possibly implies that the drift loss can affect the flux levels even inside the trapping boundary. We recently investigated the details of such diffusion process by solving the diffusion equation with a set of initial and boundary conditions set by the drift loss. Motivated by the simulation work, we have examined observationally the energy spectrum and pitch angle distribution near trapping boundary during the geosynchronous flux dropouts. For this work, we have first identified a list of geosynchronous flux dropout events for 2007-2010 from GOES satellite electron measurements and solar wind pressures observed by ACE satellite. We have then used the electron data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft measurements to investigate the particle fluxes. The five THEMIS spacecraft sufficiently cover the inner magnetospheric regions near the equatorial plane and thus provide us with data of much higher spatial resolution. In this paper, we report the results of our investigations on the energy spectrum and pitch angle distribution near trapping boundary during the geosynchronous flux dropout events and discuss implications on the effects of the drift loss on the flux levels at inner L regions.

• Korean Journal of Agricultural Science
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• v.11 no.1
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• pp.176-181
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• 1984

Linear free energy relation ship(LFER) on the insecticidal activity of O,O-diethylphenylphosphate (A) and 3,5-dimethylphenyl-O,O-diethylphosphate (B) derivatives were studied by EHT MO calculation method and regression analysis method. LFER between varying substituent constants and $pI_{50}$ constants of phosphates, (A) & (B) were calculated with applying Hammett, Okamoto-Brown, Taft and Swain-Lupton's DSP equations;percent resonance effect(R) and field effect(F) of (A) were %R=33.5 & %F=66.5 and also that of (B) were %R=2 & %F=98, respectively. On the basis of above findings, the insecticidal activities were similar for both (A) and (B), but (B) have larger field and inductive contribution than (A), due to the 3,5-dimethyl group of (B).

• Journal of Energy Engineering
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• v.5 no.1
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• pp.65-71
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• 1996

Decomposition reaction of methanol was conducted on Ni-Cu/SiO$_2$catalysts with several variables. Variables used in this study are S.V(Space Velocity), partial pressure of methanol, reaction temperature, and composition rate of Ni-Cu. The range of S.V is 10,000-30,000h$\^$-1/, the temperature range is 150-400$^{\circ}C$ and values of Cu/(Ni＋Cu) are 0, 0.25, 0.5, 0.75, and 1. Over Ni/SiO$_2$, and Ni-Cu/SiO$_2$, the conversion rate of decomposition reaction of methanol arrived at 100% with increasing of temperature. At this time the selectivity of CO on Ni/SiO$_2$, was suddenly decreased, but on Ni-Cu/SiO$_2$, it was still sustained highly. The main products of reaction were CO and H$_2$, and by-products were CO$_2$ and CH$_4$mainly.

• Phonetics and Speech Sciences
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• v.9 no.3
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• pp.75-83
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• 2017

The purpose of this study is to find clues to the risk of voice disorders in soprano students. The subjects of the study were 17 soprano students and 18 general students (women). The phonation of vowels /a/, /i/, and /u/ with C4 and F4 notes in each group were recorded. Then, only soprano students were made to record their classical vocalization containing vibrato. Formant, formant energy, bandwidth, VAI (vowel area index), VSA (vowel space area) and L/H ratio were analyzed. There was significant difference in F3 such that the singers' note was measured around 3 kHz which seems to be 400 Hz higher than one from general students. But, There was no significant difference in L/H ratio between soprano student and the general student. There was a significant difference in F3 in the comparison of the soprano students' two vocalization methods. Classical vocalization was measured at 200Hz higher than sustained phonation in F3. Vocal tract adjustment was made and vowel space changed, but there was no significant difference in F3 energy, which is the index of singers' formant according to the phonation method. The L/H ratio, which can be a direct indicator of vocal effort, has no difference in phonation method and is lowered in all phonation methods as the pitch increases. C4 and F4 pitches are lower than the singing range of the soprano. When the pitch changes, vocal effort increases like a general student which will be an indicator of the risk of vocalization. This will be a clue to the vocalization of the immature soprano student.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.24 no.1
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• pp.189-205
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• 2013

The purpose of this study is to describe the trends and contents of literature in green library and to suggest the research direction on green library. Earlier studies focus on the green library architecture and necessity, after then green library management studies have proliferated. Green library architecture studies have emphasized on 'energy and atmosphere' and 'indoor environmental quality' based upon 5 categories of LEED evaluation system. Green library management studies have focused on library resources recycling and utilizing energy through effective management of library collection. Based on the analysis of literature, five research directions are suggested, such as the number of libraries in an area, library shelf position and space, library space program, collection ratio for library storage, and user studies.

• Smart Structures and Systems
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• v.19 no.4
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• pp.341-350
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• 2017

Based on the super elastic properties of the shape memory alloy (SMA) and the inverse piezoelectric effect of piezoelectric (PZT) ceramics, a kind of hybrid semi-active control device was designed and made, its mechanical properties test was done under different frequency and different voltage. The local search ability of genetic algorithm is poor, which would fall into the defect of prematurity easily. A kind of adaptive immune memory cloning algorithm(AIMCA) was proposed based on the simulation of clone selection and immune memory process. It can adjust the mutation probability and clone scale adaptively through the way of introducing memory cell and antibody incentive degrees. And performance indicator based on the modal controllable degree was taken as antigen-antibody affinity function, the optimization analysis of damper layout in a space truss structure was done. The structural seismic response was analyzed by applying the neural network prediction model and T-S fuzzy logic. Results show that SMA and PZT friction composite damper has a good energy dissipation capacity and stable performance, the bigger voltage, the better energy dissipation ability. Compared with genetic algorithm, the adaptive immune memory clone algorithm overcomes the problem of prematurity effectively. Besides, it has stronger global searching ability, better population diversity and faster convergence speed, makes the damper has a better arrangement position in structural dampers optimization leading to the better damping effect.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.36 no.8
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• pp.935-943
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• 2012

In accidents involving the collision of railway vehicles, there is a risk that structural members might penetrate the cab frame of the railway vehicle in the space in which the driver or passengers are seated. To reduce this risk, worldwide, studies on the collision of railway vehicles are underway. In North America, the Code of Federal Regulations (CFR) was revised in 2010 to include crush criteria for a collision and the corner post in an end frame. In this study, a crush analysis and crush test for a collision post and a crash analysis for a rigid cylinder were performed according to the CFR. The analysis and test results were compared and reviewed. This study aims to determine the usefulness of crush analysis for developing various end frames, and to understand the crush and crash characteristics and review the accuracy of the analysis.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.5
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• pp.391-403
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• 2013

Propeller aircraft propelled by an electric propulsion system is gaining a renewed interest because of ever-increasing environmental concern on harmful emissions emitted from conventional jet engines and national energy security. Traditional aircraft sizing methods are not readily applicable to electric propulsion aircraft that utilize a variety of alternative energy sources and power generation systems. This study showcases an electric propulsion aircraft sizing exercise based on a generalized, power based sizing method. A general aviation aircraft is propelled by an electric propulsion system that comprises of a propeller, a high temperature super conducting motor, a Proton Exchange Membrance(PEM) fuel cell system fuelled with hydrogen, and power conditioning equipment. In order to assess the impact of technology progression, aircraft sizing was conducted for two different sets of technology assumptions for electric components, and the results were compared with conventional baseline aircraft.