• Journal of Korean Society of Environmental Engineers
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• v.32 no.6
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• pp.563-580
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• 2010

In 2009 the Korea Ministry of Environment announced 'A Comprehensive Plan for the Improvement of Sewer Service in Rural Area' aiming at reduction of the sewer service gap between urban and rural areas as well as improvement in the residential environment of the rural area. According to the plan, the sewer system supply rate for the rural area is expected to reach up to 75% until 2015 with the budget of 4.7 trillion won (Korean currency). It is not certain, however, that the increase in the sewer system supply rate will accompany improvement of water quality in receiving water because several veiled problems that can occur in small-scale sewer treatment plants are poorly addressed in the plan. In this study, those issues for the small-scale sewer treatment plants and their solutions were discussed based on a case study in which we investigated 19 treatment facilities at two rural regions in Gyeonggi province. This study also included strategies useful for the plan. From the results of investigation, some problems, e.g., high hourly variations but low in flowrates and low mass loading were commonly identified. Although operation parameters in sewer treatment plants require to be modified depending on the mass loading, most of the plants were operated with the initial design parameters which causes the decrease of removal efficiency. In the intensive diagnosis, we arranged and applied solutions (e.g., flow equalization, air on/off time control, etc) to the two selected plants and found out improvement of effluent water quality, especially organic matters (COD and SS) and T-N with better denitrification performance.

• Science of Emotion and Sensibility
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• v.13 no.4
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• pp.721-732
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• 2010

As increasing of electrical device usage, social concerns about the possible effects of 60Hz electromagnetic fields (EMF) on human health have increased. The number of people with self-attributed electromagnetic hypersensitivity (EHS) who complain of subjective symptoms such as headache, insomnia etc. also increased. However, we don't know whether the EHS results from psychological factor or real perception to the electromagnetic field. In this study, we simultaneously investigated physiological changes(heart rate, respiration rate, heart rate variability, alpha and beta waves in EEG), subjective symptoms and perception accuracy to assess origins of subjective symptoms according to the EMF exposure. Experiment consists of real and sham sessions and 60Hz 12.5uT magnetic field was on(real) or off(sham) to 15 EHS and 16 nonEHS. As the results, EMF exposure did not have any effects on physiological parameters or subjective symptoms for both groups. There was also no evidence that EHS group perceived the EMFs correctly than the control group. Therefore, the origins of subjective symptoms is not the 60Hz magnetic field but psychological factors.

• Journal of the Korean association of regional geographers
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• v.7 no.4
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• pp.18-32
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• 2001

Korean society has frequently seen the conflicts between environmentally oriented ideology and development ideology which generally take shape as regional problems. An interesting example is the case of Paldang water resource protection area in Yangpyung-kun, Kyunggi Province. At the area, the rural residents are trying to take regional development by utilizing as much as natural resource in the region, and the central government is trying to make clean water sustained for the public interest of the whole people living within the supplying area of the water resource. Accordingly, the conflict is inevitable. It is the role of environmental movement group that makes us pay attention to this region. Under the present situation regarding environmental protection as a core keyword, the environmental protection groups tend to stand on the side of the central government. That is, those groups let the government consolidate its dominance discourse, which help the resistance discourse of the residents weakened. This basic structure of relationship sometimes touches off the situations of antagonistic confrontation. It is the group for organic fanning movement on the region that is playing a significant mediating role between the two. It has eased severe confrontation, and has persuaded the residents, expecially the farmers, to accept so-called win-win strategies which are related with various kind of organic fanning. The agriculture can be regarded as a win-win action because it is a way of fanning adapted to the protected natural environment. It is taking firm hold in this region as an alternative which can satisfy the ideology of 'sustainable development' or 'sustainability'. It could give us a kind of paradoxical confusion that the strategies of regional development of pro-environment are being carried out in the region where the residents are fighting against the government's strict control of natural environment. The example of this region, however, could show a significant direction for solving the continuous problem of conflict between environmental protection and regional development.

• Journal of Korean Society on Water Environment
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• v.23 no.6
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• pp.945-950
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• 2007

The stormwater runoff from paved area are highly polluted because of particulate materials as well as metals from various vehicular activities. The Division of Road Maintenance in Ministry of Construction and Transportation was recently developed the Guidelines of Environment-kindly Road Maintenance. It is actually requiring the BMP construction to control the nonpoint source pollution as based on the TMDL program. This research is carried out in order to define the characteristics of stormwater runoff from the toll-gate of highways since 2006, which is actually one of the main pollutant sources of paved areas. This monitoring is the first phase work for establishing the treatment facilities in the toll-gates. The one of the main characteristics from toll-gate runoff is the first flush phenomenon containing lots of sediments and metal compounds at the beginning of a storm event. Usually it is used to determine the size of treatment facilities and to calculate the reduced pollutant mass in the facility. The research results shows that the mean EMC vaules for heavy metals are determined to $274.3{\mu}g/L$ for Cd, $1,273.4{\mu}g/L$ for Cr, $1,822.0{\mu}g/L$ for Cu, $6,504.9{\mu}g/L$ for Fe, $14,930.3{\mu}g/L$ for Pb, and $714.1{\mu}g/L$ for Zn. Also the metal mass loadings from the toll-gates are calculated using EMC, watershed area and storm duration.

• Journal of the Korean Society for Nondestructive Testing
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• v.26 no.2
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• pp.99-107
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• 2006

Magnetic nondestructive testing is very useful far detecting a crack on the surface or near of the surface of the ferromagnetic materials. The distribution of the magnetic flux leakage (DMFL) on a specimen has to be obtained quantitatively to evaluate the crack. The magnetic camera is proposed to obtain the DMFL at the large lift-off. The magnetic camera consists of a magnetic source, magnetic lens, analog to digital converters (ADCs), interface, and computer. The magnetic leakage fields or the distorted magnetic fields from the object, which are concentrated on the magnetic lens, are converted to analog electrical signals tv arrayed small magnetic sensors. These analog signals are converted to digital signals by the ADCs, and are stored, imaged, and processed by the interface and computer. However the magnetic camera has limitations with respect to converting and switching speed, full range and resolution, direct memory access (DMA), temporary storage speed and volume because common ADCs were used. Improved techniques, such as those that introduce the operational amplifier (OP-Amp), amplify the signal, reduce the connection line, and use the low pass filter (LPF) to increase the signal to noise ratio are necessary. This paper proposes the exclusive embedded ADC including OP-Amp, LPF, microprocessor and DMA circuit for the magnetic camera to satisfy the conditions mentioned above.

• Korean Journal of Environmental Agriculture
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• v.18 no.3
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• pp.265-271
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• 1999

The direct seeding of seeds or the pellets of three native tree species (Pinus densiflora, Parthenocissus tricuspidata and Rhus chinensis) was tried on the rock cut-slope revegetation bed established by construction of mechanical excavation or erosion break with artificially enriched soil medium. The seed $pellet(1{\sim}2\;cubic\;cm)$ made by coating seeds(treated with proper previous pregermination treatments) with the mixture of peatmoss, clay, chemical absorbant(3.5:1.0:0.2, v/v) showed about twice better percent germination than the control seeds. The percent germination and the survival rate of the germinated seedlings were higher in the spring direct seeding than the summer or the fall. The soil medium containing the compost showed extremely low percent $germination(0{\sim}3%)$ which presumably attributed to the compost inducing damping-off disease. The survival rates were affected mainly by shading of natural herbaceous vegetation invading from outside to the revegetation bed. The planting of two year old container seedlings of P. densiflora and P. tricuspidata on August 2, 1998 was successful indicating that it could be an alternative revegetation method in case the summer direct seeding is unfavorable.

• Fire Science and Engineering
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• v.33 no.4
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• pp.112-120
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• 2019

Benzene is a class 4 hazardous material according to the Act on the Safety Control of Hazardous Substances. This study qualitatively evaluated the damage size of a "toxic" accident and "pool fire" accidents based on benzene in a virtual scenario of a fire and leakage accident during unloading at a port facility. The KORA program was used as an evaluation method, which is supported as a universal program by the National Institute of Chemical Safety. The range of damage effects of a benzene-induced fire and leakage accident was predicted. In the case of toxic damage range, the accident's damage effect range for the "worst case scenario" was reduced by up to 5.11% with a decrease in the size of the leakage hole. In the case of the leakage time, the damage effect range increased to 145.12% with a 10 min leakage time compared to that of a 5 min leakage time and went up to 20 min (212.29%) with a 20 min leakage time. In the case of pool-fire-induced damage, the damage effect range by radiant heat in the "worst case scenario" was 228.8 m in radius from the center of the handling facility. In the "alternative scenario," the damage effect range by radiant heat was reduced by up to 8.26% compared to that in the "worst case scenario" since the size of the leakage hole was decreased by reducing the cross-sectional area of the pipe.

• The Journal of Natural Sciences
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• v.6 no.1
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• pp.55-64
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• 1993

Experiments were conducted to study the effect of auxins and cultural factors on rooting characteristics in offshoots cutting of Aloe vera. The result obtained were as follows;1. Short offshoots(15-20cm) with rhizome had more roots than that of the removed rhizome, while long offshoots(25-30cm) without rhizome had more roots and heavier root dry weight than short offshoots with rhizome. The highest rooting ability occured when IBA treated 500mg per liter in short offshoots with rhizome, whereas long offshoots without rhizome showed higher rooting ability at the level of 1,000mg/l of IBA and 200mg/I of NAA2. Among three kinds of anxin treated, both IBA and NAA showed better rooting ability than ethychlozate. Root number, root length and root dry weight were higher at 10 min. dipping treatment of IBA 500mg/I for short off-shoots without rhizome and 10 min. dipping treatment of IBA 1,000mg/l for long offshoots with rhizome. Rooting ability of long offshoots was higher than that of short offshoots.3. In addition to IBA 1,000mg/l, 7-day dryness under shading condition increased root number and dry weight of root in offshoots without rhizome. Control treatment lengthened root by increasing drying period under the shading condition.4. The plain soil with mamure had not only higher root dofferentiation but higher root growth of offshoots cutting than the artificial soil.5. Rooting ability in offshoots cutting had a tendency increasing with decrease in shading percentage to natural. Black color poly ethylene film mulching had better rooting ablility than transparency poly ethlene film mulching in offshoots cutting.

• Korean Journal of Medicinal Crop Science
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• v.16 no.4
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• pp.207-210
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• 2008

It is very important factors to control optimal light transmission ratio and soil moisture content in order to produce good quality of ginseng seedling. To study the effect of light transmission ratio (LTR) and soil moisture content(SMC) on growth characteristics and yield of ginseng seedling, LTR was controlled by three level such as 21.2, 24.8% and 30.3%, and SMC was plotted by four level of 11.0%, 12.5%, 15.3% and 18.9% at the greenhouse. Chlorophyll content was gradually decreased in the low LTR (21.2%), while it was distinctly decreased by the decrease of SMC in excessively high LTR (30.3%). The decrease of SMC in the high LTR increased heat injury ratio distinctly, while heat injury ratio in the low LTR was only increased when SMC was very low such as 11.0%. All of fresh root weight per Kan (3.3$m^2$), root weight per plant, and the number of usable seedling were distinctly decreased by the increase of LTR and the decrease of SMC. Excessive increase of LTR in optimal SMC (18.9%) hadn't a great effect on the decrease of root weight, while root weight in low SMC was distinctly decreased by the increase of LTR. Ratio of rusty root was distinctly increased in the condition that both of LTR and SMC were high. Ratio of rusty root in the excessively high LTR was gradually fallen off by decrease of SMC, but its ratio in low SMC didn't changed distinctly by the decrease of SMC.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.325-330
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• 2004

Several kinds of low voltage cables have been used in nuclear power plants for the supply of electric power, supervision, and the propagation of control signals. These low voltage tables must be inspected for safe and stable operation of nuclear power plants. In particular, the degradation diagnosis to estimate the integrity of low voltage rabies has recently been emphasized according to the long use of nuclear power plants. In order to evaluate their degradation, the surrounding temperature, hardness of insulation material, elongation at breaking point (EAB), etc. have been used. However, the measurement of temperature or hardness is not useful because of the absence of quantitative criteria; the inspection of a sample requires turning off of the power plant power; and, the electrical inspection method is not sufficiently sensitive from the initial through the middle stage of degradation. In this research, based on the theory that the ultrasonic velocity changes with relation to the degradation of the material, we measured the ultrasonic velocity as low voltage cables were degraded. To this end, an ultrasonic degradation diagnosis device was developed and used to measure the ultrasonic velocity with the clothing on the cable, and it was confirmed that the ultrasonic velocity changes according to the degradation of low voltage cables. The low voltage cables used in nuclear power plants were degraded at an accelerated rate, and EAB was measured in a tensile test conducted after the measurement of ultrasonic velocity. With the increasing degradation degree, the ultrasonic velocity decreased, whose potential as a useful parameter for the quantitative degradation evaluation was thus confirmed.