• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.4
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• pp.374-381
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• 2021

Raman spectrometers are studied and developed for the military purposes because of their nondestructive inspection capability to capture unique spectral features induced by molecular structures of colorless and odorless chemical warfare agents(CWAs) in any phase. Raman spectrometers often suffer from random noise caused by their detector inherent noise, background signal, etc. Thus, reducing the random noise in a measured Raman spectrum can help detection algorithms to find spectral features of CWAs and effectively detect them. In this paper, we propose a denoising autoencoder for Raman spectra with a loss function for sample efficient learning using noisy dataset. We conduct experiments to compare its effect on the measured spectra and detection performance with several existing noise reduction algorithms. The experimental results show that the denoising autoencoder is the most effective noise reduction algorithm among existing noise reduction algorithms for Raman spectrum based standoff detection of CWAs.

• Journal of Korean Society for Atmospheric Environment
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• v.20 no.E2
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• pp.69-75
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• 2004

In this study, thin film gas sensor based on tin oxide was fabricated to examine its characteristics. Target gas is acetonitrile ($CH_3$CN) which is a blood simulant for the chemical warfare agent. Sensing materials are SnO$_2$ SnO$_2$/Pt, and Sn/Pt with thickness from 1000 to 3000 $\AA$. The sensor consists of a sensing electrode with inter-digit (IDT) type in front side and a heater in rear side. Resistance changes of sensing materials are monitored on real time basis using a data acquisition board with a 12-bit analog to digital converter. Sensitivities are measured at different operating temperatures also with different gas concentrations and film thickness. The high sensitivity is obtained for Sn (3000 $\AA$)/Pt (30 $\AA$) at 30$0^{\circ}C$ for 3 ppm. Response and recovery times were about 40 and 160 s, respectively. Repetition measurements showed very good results with $\pm$3% in full scale range.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.1
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• pp.122-128
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• 2014

Remote fourier transform infrared(FTIR) chemical imaging detection system allows detection and identification of gases in the atmosphere from long distances. In this paper, the appropriate field of view(FOV) of the FTIR imaging system was examined and the main performance of the system for the interferometer was described. For the determination of the FOV, simulations of gas dispersion range were performed with the NBC reporting and modeling software(NBC-RAMS) developed by ADD. As a result, minimum 192 mrad of FOV was required for the remote FTIR imaging system to visualize chemical warfare agents dispersed in several hundred meters. At the same time, 0.75 mrad of instantaneous field of view(IFOV) for a linear interferometer proper to take a FOV for the chemical agent imaging.

• Journal of the Korea Institute of Military Science and Technology
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• v.7 no.2 s.17
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• pp.81-87
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• 2004

Semiconductor thick film gas sensors based on tin oxide are fabricated and their gas response characteristics are examined for four simulant gases of chemical warfare agent (CWA)s. The sensing materials are prepared in three different sets. 1) The Pt or Pd $(1,\;2,\;3\;wt.\%)$ as catalyst is impregnated in the base material of $SnO_2$ by impregnation method.2) $Al_2O_3\;(0,\;4,\;12,\;20\;wt.\%),\;In_2O_3\;(1,\;2,\;3\;wt.\%),\;WO_3\;(1,\;2,\;3\;wt.\%),\;TiO_2\;(3,\;5,\;10\;wt.\%)$ or $SiO_2\;(3,\;5,\;10\;wt.\%)$ is added to $SnO_2$ by physical ball milling process. 3) ZnO $(1,\;2,\;3,\;4,\;5\;wt.\%)$ or $ZrO_2\;(1,\;3,\;5\;wt.\%)$ is added to $SnO_2$ by co-precipitation method. Surface morphology, particle size, and specific surface area of fabricated sensing films are performed by the SEM, XRD and BET respectively. Response characteristics are examined for simulant gases with temperature in the range 200 to $400^{\circ}C$, with different gas concentrations. These sensors have high sensitivities more than $50\%$ at 500ppb concentration for test gases and also have shown good repetition tests. Four sensing materials are selected with good sensitivity and stability and are fabricated as a sensor array A sensor array Identities among the four simulant gases through the principal component analysis (PCA). High sensitivity is acquired by using the semiconductor thick film gas sensors and four CWA gases are classified by using a sensor array through PCA.

• Applied Chemistry for Engineering
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• v.33 no.3
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• pp.296-301
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• 2022

Due to the fact that zirconium based metal-organic frameworks (Zr-MOFs), such as UiO-66, have a large specific surface area and excellent selective adsorption capacity, Zr-MOFs are gaining attention as materials that can provide protection from the attack of chemical warfare agents in battleground. However, most of the metal-organic frameworks have an issue of selective adsorption capacity degraded by water molecules when exposed to the atmosphere, because of the weak metal-organic ligand bonds and the presence of voids. Therefore, polydimethylsiloxane (PDMS), a representative hydrophobic polymer material, was coated on the surface of UiO-66 to enhance the sustainability of the diisopropyl methylphosphonate (DIMP) sorption capacity in the battleground condition. Through the analysis of surface structure and organic functional group distribution of PDMS coated UiO-66, silicon was confirmed to be evenly coated. The contact angle increased by over 30° for the PDMS coated UiO-66, indicating that the hydrophobicity was improved. In addition, both the UiO-66 and PDMS coated UiO-66 were used as adsorbents for DIMP, a similar chemical warfare agent, to investigate the durability of adsorption capacity in a high humidity environment. The PDMS coated UiO-66 showed higher durability of adsorption capacity for 20 days than that of pristine UiO-66.

• Korean Chemical Engineering Research
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• v.45 no.2
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• pp.172-177
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• 2007

The hydrolysis reaction of sarin(GB), one of the nerve agents was studied in aqueous sodium hydroxide(NaOH) solutions to find the experimental conditions which can convert GB into the less toxic compounds. 10 wt% of GB was added into the aqueous NaOH(2.05 eq) in a small-scale jacket-attached reactor connected to a circulator. The reaction rate constants were measured at three temperatures(50, 70 and $90^{\circ}C$) and the reaction times required to degrade the material to > 99% were calculated at different temperatures. In this study, 10 wt% of GB was degraded to 99.99% in 1.2hr at $90^{\circ}C$ by the aqueous NaOH solution. The major hydrolysate of GB was isopropyl methylphosphonate.

• Korean Chemical Engineering Research
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• v.45 no.3
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• pp.291-297
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• 2007

The hydrolysis reaction of sulfur mustard(HD, bis 2-chloroethylsulfide), one type of the blister agents was studied in water to find the operation conditions which can convert HD into less toxic compounds. The reaction was proceeded into two steps. First, 10~20 wt% of HD was hydrolyzed in water at $90^{\circ}C$ for 2 hr and aqueous sodium hydroxide solution(2.1 eq) was subsequently added to the reaction mixture at room temperature. The efficiency of HD hydrolysis at this experimental conditions was greater than 99.99% and the final degradation products of HD were 68 wt% of thiodiglycol, 8 wt% of 1,2-bis(2-hydroxyethylthio)ethane and 24 wt% of bis(2-hydroxyethylthioethyl)ether.

• 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.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.17
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• pp.7567-7573
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• 2015

Background: Catastrophic effects of mustard gas as a chemical warfare agent have always been a major problem for those exposed to this agent. In this meta-analysis it was tried to evaluate carcinogenesis, ocular, cutaneous and respiratory complications of mustard gas exposure among Iranians who had been exposed to this agent during the Iran-Iraq war. Materials and Methods: In this meta-analysis, the required data were collected using keywords "mustard gas", "sulfur mustard", "cancer", "neoplasm", "respiratory complications", "ocular complications", "lung disease", "chronic complication", "eye", "skin", "cutaneous complication", "carcinogenesis" and their combination with keywords "Iran", "Iranian", "prevalence", "mortality" and their Farsi equivalent terms from the databases of SID, Iranmedex, Magiran, Pubmed, Science Direct, Google Search engine, Gray Literature and Reference of References. To determine the prevalence of each complication and perform meta-analysis, CMA: 2 (Comprehensive Meta-Analysis) software with a randomized model was used. Results: Of the 542 articles found, 7 national articles, consistent with the aims of this study were selected. Meta-analysis of seven papers revealed that cancer risk, especially cancer of the respiratory system was elevated, so that the relative risk (RR) of cancer role of mustard gas was inconsistent from 2/1 to 4 in this survey. Also prevalence of delayed skin disorders due to sulfur mustard was 94.6%, pulmonary complications 94.5% and ocular complications 89.9%. The incidence of various cancers in victims exposed to mustard gas was 1.7% worldwide where the rate was 2.2% in Iranian victims of the Iraq-Iran war. Conclusions: Based on present study the prevalence of delayed mustard gas related cutaneous, pulmonary and ocular complications is above 90% and risk of carcinogenesis is higher in comparison to worldwide statistics. This may suggest need for long-term and persistent follow-up and rehabilitation procedures for populations exposed to this agent.

• English & American cultural studies
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• v.18 no.4
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• pp.1-31
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• 2018

It is needless to say that America's indiscriminate artillery and chemical attacks have worsened the conditions of Vietnam's tropical rain forests, causing war-torn combat troops and civilians to suffer more from the participation and aftermath of the Vietnam war. Around two decades after the Vietnam War, American and Vietnamese writers dealing with the destruction of the human and nature of the Vietnam War and the following traumatic experience commonly report the horrors of inhumane warfare, but some differences among them appear in the reception of the ecocide consciousness. For American writers who had been involuntarily involved or who had stayed in the back area as interpreters and counter-intelligence force, the Vietnam War was often a kind of exotic "addicted adventure" which their American hometown could not provide. But apart from overcoming postwar post-traumatic stress by writing of healing which was shared with American war writers, Vietnamese writers have been able to overcome the scars of war as the communal memorial, which Jonathan Shay emphasized as the necessary comforting ritual by community members showing the sign of honor and care. On the other hand, American war writers were on the side of "separate peace," as Jeong stressed, and the Vietnam War to them was more racist like the case of "body count." Nevertheless, it is fortunate that the hideous experience of war could turn them all into the creativity pool, just as the 5,000 square mile of bomb creators have been used as the postwar fish ponds.