• Journal of the Korea Institute of Military Science and Technology
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• v.19 no.3
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• pp.302-310
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• 2016

An underground ammunition facility requires less quantity distances than the aboveground counterpart. However, chamber blast doors which resist the high blast-pressures are necessary for prevention of the consecutive explosions when an accident explosion occurs at any chamber. This paper aims to propose an procedure for calculation of the design loads for the chamber blast doors. Modeling considerations are drawn through analyzing the influences of the geometrical shapes and mechanical properties of rocks on the propagation of pressure wave along with the tunnels. Additionally, the design loads for the chamber blast doors in a newly-built underground ammunition facility are calculated based on the proposed procedure.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.589-593
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• 2016

Microbial fuel cell (MFC) can produce electricity from oxidation-reduction of organic and inorganic matters by electrochemically active bacteria as catalyst. Stacked MFCs have been investigated for overcoming low electricity generation of single MFC. In this study, two-typed stacked-MFCs (submerged-flat and stand-falt) were operated according to electrode connection for optimal stacked technology of MFC. In case of submerged-flat MFC with all separator electrode assembly (SEA) sharing anode chamber, MFC with mixed-connection showed more voltage loss than MFC with single-connection method. And MFC stacked in parallel showed better voltage production than MFC stacked in series. In case of stand-flat MFC, voltage loss was bigger when SEAs sharing anodic chamber only were connected in series. Voltage loss was decreased when SEAs parallel connected SEAs sharing anodic chamber were connected in series.

• Geomechanics and Engineering
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• v.29 no.3
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• pp.321-329
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• 2022

Tunnel site where high water pressure is applied, such as subsea tunnel, generally selects the shield TBM (Tunnel Boring Machine) to maintain the tunnel excavation face. The shield TBM has cutters installed, and the cutters wear out during the process of excavation, so it should be checked and replaced regularly. This is called CHI (Cutterhead Intervention). The conventional CHI under high water pressure is very disadvantageous in terms of safety and economics because humans perform work in response to high water pressure and huge water inflow in the chamber. To overcome this disadvantage, this study proposes a new method to dramatically reduce water pressure and water ingress by injecting an appropriate grout solution into the front of the tunnel face through the shield TBM chamber, called New Face Grouting Method (NFGM). The tunnel model tests were performed to determine the characteristics, injection volume, and curing time of grout solution to be applied to the NFGM. Model test apparatus was composed of a pressure soil tank, a model shield TBM, a grout tank, and an air compressor to measure the amount of water inflow into the chamber. The model tests were conducted by changing the injection amount of the grout solution, the curing time after the grout injection, and the water/cement ratio of grout solution. From an economic point of view, the results showed that the injection volume of 1.0 L, curing time of 6 hours, and water/cement ratio of the grout solution between 1.5 and 2.0 are the most economical. It can be concluded that this study has presented a method to economically perform the CHI under the high water pressure.

• Journal of the Korean Geotechnical Society
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• v.25 no.11
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• pp.117-130
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• 2009

In this paper, a series of laboratory chamber tests were carried out to evaluate the applicability of a porous concrete pile fabricated with recycled aggregates (RAPP) for the soft ground improvement. While performing the laboratory chamber tests for the RAPP, the surface settlement, excess pore pressure and vertical stress distribution with time were compared with those of SCP provided by You (2003) under the same experimental condition. In addition, the experimental results were compared with the numerical simulation using ABAQUS in this study. The results show that the settlement reduction is significantly enhanced due to the stress-sharing mechanism between the RAPP and soil formation by stress concentration on the RAPP. Furthermore, the comparison of consolidation rate shows that the RAPP can accelerate consolidation as well, which behaves as a vertical drain.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.E
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• pp.1-17
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• 2000

In this study, the concentrations of particulate organic constituents of environmental tobacco smoke(ETS) were determined using an environmental smog chamber, where ETS is the sole source of target compounds. ETS was generated in a 30 ㎥ environmental chamber by a number of different cigarettes, including the Kentucky 1R4F reference cigarette and eight commercial brands. A total of 12 experimental runs was conducted, and target analytes included a group of ETS markers both in vapor and particulate phase and a class of polycylic aromatic hydrocarbos(PAHs) associated with ETS particles. The mass concentrations of PAH in ETS particles were also determined. The average contents of benzo(a) pyrene and benzo(a) anthracene in ETS particles for the commercial brands were 12.8 and 21.5$\mu\textrm{g}$/g, respectively, There values are all somewhat higher than those determined previously by other studies. Results form the chamber study are further used to estimate the average and variability of cigarette yields for target compounds associated with ETS. Finally, ratios of RSP to the surrogate standards of UVPM, FPM and solanesol were calculated for each sample. The average conversion factors factors for the eight commercial brands were 7.3, 38, and 41 for UVPM, EPM, and solanesol, respectively. The UVPM and FPM factors are in good agreement with the recently published values. Whereas there might be a substantial difference in the solanesol content among cigarettes produced in different countries, the variability is somewhat greater than those of UVPM and FPM, Unfortunately, comparison of the PAH yield data from this study with literature values was complicated by a lack of consistency in cigarette smoke generating methodology. Validation of the PAH yields was also difficult due to a lack of information on the ETS related PAH in the literature. From and engineering viewpoint , however, these data on the cigarette yields of ETS components may still provide useful information to studies on the mathematical modeling of indoor air quality management regarding tobacco smoke as a source of interest, or to studies on the assessment of human exposure to ETS.

• Journal of Korean Society for Atmospheric Environment
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• v.21 no.2
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• pp.191-204
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• 2005

Building and furnishing materials and consumer product are important sources of volatile organic compounds(VOCs) and other aldehydes in the indoor environment. Some available evidence indicates that VOCs can cause adverse health effects to the building occupants and contribute to some of the symptoms of what we call, 'Sick House Syndrome' in Korea. The aims of this study were to evaluate the efficiency of emission system and to investigate comparison of the emission characteristics of different building materials such as wall-papers, paints, and adhesives. The emission of VOCs from building materials were determined in the small chambers defining the temperature, relative humidity, and ventilation rate in this study. VOCs were sampled for 20 minutes using Tenax-TA tubes and analysed by GC-MS with thermal desorption. The stability of conditions for temperature and relative humidity in this small chamber system showed that the fluctuation of temperature was between 25.4$\pm$0.3$^{\circ}C$ and that of relative humidity was 50.2$\pm$0.6$\%$ under the airflow rate of 167 mL/min. The emission tests from building materials resulted in TVOC emission rates of 0.011 $\~$ 3.108 mg/m$^{2}$h after 7 days. The general wall-papers emitted toluene abundantly and the natural wall-papers mainly emitted n-butanol and a minor amount of alkanes compound such as n -tetradecane. The remainder consisted of toluene, m,p -xylene, and styrene. The paints mainly emitted toluene and the adhesives mainly emitted chloroform as well as toluene. As a result, this study is expected to suggest meaningful data for future studies in exposure control through selecting healthy building materials and for the establishment of guidelines for various building materials in Korea.

• Ecology and Resilient Infrastructure
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• v.8 no.2
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• pp.133-133
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• 2021

• Journal of Korean Society of Environmental Engineers
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• v.32 no.8
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• pp.739-746
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• 2010

The purposes of this study are 1) to develop an advanced chamber system within ${\pm}10%$ of air velocity at the particulate matter (PM) collection area, 2) to research theoretical characteristics of PM10 and PM2.5 samplers, 3) to assess the performance characteristics of PM10 and PM2.5 samplers through chamber experiments. The total six one-hour experiments were conducted using the cornstarch with an mass median aerodynamic diameter (MMAD) of $20\;{\mu}m$ and an geometric standard deviation of 2.0 at the two different air velocity conditions of 0.67 m/s and 2.15 m/s in the chamber. The aerosol samplers used in the present study are one APM PM10 and one PM2.5 samplers accordance with the US federal reference methods and specially designed three mini-volume aerosol samplers (two for PM10 and one for PM2.5). The overall results indicate that PM10 and PM2.5 mini-volume samplers need correction factors of 0.25 and 0.39 respectively when APM PM samplers considered as reference samplers and there is significant difference between two mini-volume aerosol samplers when a two-way analysis of variance is tested using the measured PM10 mass concentrations. The PM10 and PM2.5 samplers with the cutpoints and slopes (PM10: $10{\pm}0.5\;{\mu}m$ and $1.5{\pm}0.1$, PM2.5: $2.5{\pm}0.2\;{\mu}m$ and $1.3{\pm}0.03$) theoretically collect the ranges of 86~114% and 64~152% considering the cornstarch characteristics used in this research. Furthermore, the calculated mass concentrations of PM samplers are higher than the ideal mass concentrations when the airborne MMADs for the cornstarch used are smaller than the cutpoints of PM samplers and the PM samplers collected less PM in another case. The chamber experiment also showed that PM10 and PM2.5 samplers had the bigger collection ranges of 37~158% and 55~149% than the theocratical calculated mass concentration ranges and the relatively similar mass concentration ranges were measured at the air velocity of 2.15 m/s comparing with the 0.67 m/s.

• Journal of Radiation Protection and Research
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• v.28 no.3
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• pp.255-261
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• 2003

An environmental radiation monitoring system based on high pressurized ionization chamber has been used for on-line gamma monitoring surrounding the KAERI (Korea Atomic Energy Research Institute), which transmits the dose data measured from ion chamber on the site via radio frequency to a central processing computer and stores the transmitted real-time data. Although communication using radio frequency has several advantages such as effective and economical transmission, storage, and data process, there is one main disadvantage that data loss during transmission often happens because of unexpected communication problems. It is possible to restore the loss data by off-line such as floppy disk but the simultaneous process and display of current data as well as the backup data are very difficult in the present on-line system. In this work, a new electronic circuit board and the operation software applicable to the conventional environmental radiation monitoring system are developed and the automatical synchronization of the ion chamber unit and the central processing computer is carried out every day. This system is automatically able to restore the backup data within 34 hours without additional equipments and also display together the current data as well as the transmitted backup data after checking time flag.

• Korean Journal of Environmental Agriculture
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• v.29 no.4
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• pp.374-380
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• 2010

This experiment was carried out to investigate the effect of light qualities and lighting types provided by LED Chamber System which designed by Rural Development Administration on growth and development of Chrysanthemum (Dendranthema grandiflorum L., cv. 'Cheonsu') plantlet cultured in vitro. The explants of single-node cuttings were exposed to monochromic or mixture radiation of blue, red, or green under continuous and intermittent lighting for 42 days. The intermittent lighting of 20 sec. on and off per minute significantly stimulated shoot elongation with lower number of internodes compared with continuous lighting treatments. However, continuous blue, red, or green light gave greater dry weight comparing the intermittent lighting, and the lowest weight was recorded at the continuous fluorescent lamp. Otherwise, the plantlet growth in dry weight or leaf area was inhibited by the green light controlled at 50 times intermittence but internode elongation was significantly increased. These results showed that the plantlets were successfully grown under the LED Chamber System controlled with different light qualities and lighting types. Quantitative growth of the plantlets was improved under the shorter photoperiod with a intermittent lighting cycle compared with continuous lighting using fluorescent lamps. It is concluded that the growth and development of in vitro plantlets such as single-node cuttings can be achieved by the controlling of light quality or lighting type during the photoperiod per day with a lower electric cost compared with conventional continuous lighting system.