• Journal of Korean Society of Occupational and Environmental Hygiene
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• 제18권4호
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• pp.262-270
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• 2008

This study was conducted to measure concentrations of particulate matter ($PM_{10}$, $PM_{2.5}$) and endotoxin in thirty public facilities (7 elderly-care facilities, 4 hypermarkets, 4 university hospitals, 7 child-care facilities, 4 subway stations and 4 bus terminals) from September 2004 to February 2007 in Seoul and Gyeonggi-do province. $PM_{10}$ or $PM_{2.5}$ was measured with glass fiber filter and mini volume air sampler for 6 to 8 hours in indoor and outdoor of the facilities and expressed as ${\mu}g/m^3$. After weighing the filter, endotoxin was analyzed by Limulus Ameobocyte Lysate method ($EU/m^3$). $PM_{10}$ in indoor air was higher (GM and GSD was 78.00 and $1.92\;{\mu}g/m^3$, respectively) than the outdoor air (GM and GSD was 60.70 and $2.23\;{\mu}g/m^3$, respectively, I/O=1.28). All measurements was not exceeded the national maintenance standard. Elderly-care and child-care facilities showed relatively higher concentrations ($83.27\;{\mu}g/m^3$ and $81.75\;{\mu}g/m^3$; I/O=2.01 and 1.19, respectively) than hypermarkets or university hospitals. The highest PM2.5 was seen in child-care facilities ($62.15\;{\mu}g/m^3$, I/O=2.42). The I/O of the endotoxin in the PM10 and the $PM_{2.5}$ was exceeded 1.0 (1.37 and 1.57, respectively). Indoor $PM_{10}$ was affected by user/day and humidity, and endotoxin in the PM10 was affected by temperature. In conclusion, elderly- and child-care facilities are high priority facilities to be improved indoor air quality.

• Korean Journal of Soil Science and Fertilizer
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• 제9권2호
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• pp.71-76
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• 1976

Field experiments were conducted to study the effect of amendments such as lime and organic matter for mulberry trees on the newly reclaimed sandy loam soil for three years. The results are summarized as follows. 1. Compared to the N.P.K check plot with treatments, leaf yield was increased by 20 to 80%. Leaf yield was higher in the order of NPK+magnesia lime < NPK+compost > NK+fused phosphate NPK+green manure > NPK+barley straw> NPKplot. 2. Mulberry leaf yield showed high significant positive correlation with total weight and volume of root, length and number of wattles and the content of CaO or MgO in leaf respectively. 3. It is known that dead part sympom of top branch during cold season is associated with unbalance magnesium to potassium in mulberry leaf. It is estimated that such symptom was deminished when the ratio of $K_2O/MgO$ in leaf becomes 6.0 or higher. 4. In establishing a mulberry field on hilly reclaimed soil, application of magnesium and calcium with compost was essential but higher amount of potassium fertilizer should be followed in order to prevent dead part symptom of top branch of mulberry trees.

• Radiation Oncology Journal
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• 제6권2호
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• pp.177-182
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• 1988

A retrospective analysis was peformed on 23 patients with pineal region tumors treated with radiation from 1979 through 1985 at the Department of Therapeutic Radiology, Seoul National University Hospital. Histologic confirmation was done in only one case by surgical removal, and in the remaining 22 patients, the diagnosis was based on clinical and radiological findings. The radiation volume was the primary tumor site in 1 case, whole brain in 14 cases, and the whole craniospinal axis En 8 cases. The overall 5 year survival was $71.5\%$. The 5 year survival was $69.3\%$ for whole brain treated group and $73.3\%$ for craniospinal axis treated group. The survival for the two groups did not differ significantly. In two cases sites of recurrence were detected, one in supratentorial area, and the other in the lung. The results from this retrospective analysis and the review of other reports indicate that routine use of prophylactic spinal irradiation is not warranted in pineal region tumor, and the craniospinal irradiation is recommended in cases with high risk for subarachnoid seeding such as positive CSF cytology, surgical removal or biopsy.

• Economic and Environmental Geology
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• 제39권6호
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• pp.711-717
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• 2006

In order to study gas hydrate, potential future energy resources, Korea Institute of Geoscience and Mineral Resources has conducted seismic reflection survey in the East Sea since 1997. one of evidence for presence of gas hydrate in seismic reflection data is a bottom simulating reflector (BSR). The BSR occurs at the interface between overlaying higher velocity, hydrate-bearing sediment and underlying lower velocity, free gas-bearing sediment. That is often characterized by large reflection coefficient and reflection polarity reverse to that of seafloor reflection. In order to apply depth migration to seismic reflection data. we need high performance computers and a parallelizing technique because of huge data volume and computation. Phase shift plus interpolation (PSPI) is a useful method for migration due to less computing time and computational efficiency. PSPI is intrinsically parallelizing characteristic in the frequency domain. We conducted conventional data processing for the gas hydrate data of the Ease Sea and then applied prestack depth migration using message-passing-interface PSPI (MPI_PSPI) that was parallelized by MPI local-area-multi-computer (MPI_LAM). Velocity model was made using the stack velocities after we had picked horizons on the stack image with in-house processing tool, Geobit. We could find the BSRs on the migrated stack section were about at SP 3555-4162 and two way travel time around 2,950 ms in time domain. In depth domain such BSRs appear at 6-17 km distance and 2.1 km depth from the seafloor. Since energy concentrated subsurface was well imaged we have to choose acquisition parameters suited for transmitting seismic energy to target area.

• Journal of Korean Society of Environmental Engineers
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• 제28권4호
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• pp.376-383
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• 2006

This study was undertaken to control sludge bulking and foaming problems at the biological nutrient removal processes. A sewage treatment plant(STP) had a severe sludge settling problem usually over 90% in 30 min settled sludge volume and 300 mL/g in SVI and also thick and heavy brown foam in the secondary clarifiers. Identification study shows that causative filament was Microthrix parvicella which has not been previously reported in Korea. According to the inspection of processes and other related parameters, excessive growth of this particular filament was associated with high SRT caused by lack of proper capacity in sludge treatment line. After providing an extension of the sludge treatment capability, the plant can decrease SRT by wasting more sludge from the processes and also decreasing SS concentration in recycled stream. Subsequently we were able to control growth of M. parvicella. The SVI value was reduced to half of those observed during the severe bulking, but also sludge blanket and its concentration in the clarifier became compact and dense. However, decrease in population of M. parvicella caused increase of total phosphorus concentration in the effluent.

• Environmental Analysis Health and Toxicology
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• 제20권4호통권51호
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• pp.375-383
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• 2005

염화제일철은 2004년 OECD SIDS 프로그램으로 한국에서 위해성평가가 수행된 대량생산 화학물질로 1998년 화학물질 유통량조사에 의하면 우리나라에서 연간 100,000톤이 생산되었다. 본 연구에서는 염화제일철의 인체 및 환경적 영향에 대한 독성잠재성을 평가하기 위하여 OECD테스트가이드라인에 따라 독성시험을 수행하였다. 인체영향을 확인하기 위한 급성경구독성시험과 급성경피독성시험에서 랫드의 반수치사량은 각각 300$\sim$2,000 mg/kg b.w.과 >2,000mg/kg b.w.이었다. 반복독성시험의 무유해용량 (NOAEL)은 수컷 랫드는 125mg/kg b.w./day, 암컷 랫드는 250mg/kg b.w./day였고, 생식 및 발생독성시험에서 무유해용량은 암수 랫드 모두 500mg/kg b.w./day로 관찰되었다. 약한 피부자극성을 보였으며, 안부식성 물질임이 관찰되었다. S. typhimurium과 E. coli 균주를 이용한 복귀돌연변이시험에서 최고 농도인 5,000$\mu$g/plate에서 유전독성을 보이지 않았으며, 마우스를 이용한 생체내 (in vivo)소핵시험에서도 최고 농도인 50mg/kg bw/day에서 소핵유발빈도의 증가를 보이지 않아 본 시험물질은 돌연변이 유발 물질이 아닌 것으로 평가되었다. 어류(Oryzis latipes), 물벼룩 (Daphnia magna), 조류 (Pseudokirchneriella subcapitata)를 이용한 수생생물에 대한 급성독성시험 결과, 96시간 Oryzias latires의 반수치사농도는 46.6 mg/L이었고, 48시간 Daphnia magna의 반수영향농도는 19.0 mg/L이었다. 또한 Pseudokirchneriella subcapitata의 72시간 반수영향농도는 성장률을 이용한 계산법으로 6.9mg/L이었으며, 면적계산법으로는 3.8mg/L의 성장저해가 관찰되었다. 어류와 조류의 경우는 부분적으로 pH의 변화에 따른 영향으로 평가할 수 있는데 어류시험에서 pH중성시험용액에서는 100mg/L이상의 독성값을 나타내었고, 조류에서는 농도 12mg/L이상에서 pH 7아래로 떨어짐을 확인할 수 있었다. 염화제일철은 생산 및 사용공정에서 작업자에게 흡입 혹은 피부로 노출될 가능성이 있으나 밀폐공간에서 사용되므로 노출이 적은 것으로 평가되었다. 3종의 수생생물의 독성결과로부터 염화제일철은 수생환경에서 중간정도의 해가 있으며, 우리나라에서는 직접적인 염화제일철의 소비자 노출은 없으나 환경중 노출이 우려됨에 따라 제19차 OECD대량생산화학물질 초기위해성평가회의에서 환경 분야에 대해서는 추가연구 후보물질로 권고되었고, 인체 분야에서는 인체에 대한 유해성과 사용 패턴을 고려하여 추가연구 우선순위가 낮은 물질로 권고되었다.

• Journal of Korean Society of Environmental Engineers
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• 제39권5호
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• pp.277-281
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• 2017

Lately rainfall characteristics that it rains a lot in a short space of time often occurs. Because of this meteorological phenomena, the flow rate and concentration of initial rainfall for runoff and combined sewer overflows are changed. In the case of this inlet fluctuation, the flotation method at high surface loading rate is suitable for water quality management. the flotation method is able to meet the removal rate requirements of water public zone in 5 to 10 min which is irelatively short period. For assessment and diagonision of flotation method, A/S ratio is applied until now. But unfortunately, this has some limits for evaluation standard for certification and assessment of technical diagnosis and operation. This is why there is different efficiency in the bubble distribution at the same A/S ratio. The velocity and time of floating is changed by the different bubble distributions. The floating time affects the plant volume because the time factor make size dicision. Therefore the charateristics of bubble distribution and floating time at the same A/S ratio is necessary to apply to evaluation standard for certification and assessment of technical diagnosis and operation. For generalization of the method in certification and assessment, the characteristics of bubble distribution was studied. Until recently, using the optical device and shooting live video, there are some analysis technology of the floating factors. But this kind of technology is influenced by the equipment. with this level of confidence about the results, it is difficult to apply to generalize. According this reasons, this study should be applied on experiment generalization of method about measurement of relation between bubble distribution and floating time.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• 제3권2호
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• pp.149-157
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• 2005

PFC(Perfluorocarbon) decontamination process is one of best methods to remove hot particulate adhered at inside surface of hot cell and surface of equipment in hot cell. It was necessary to develop a particulate filtration equipment to reuse PFC solution used on PFC decontamination due to its high cost and to minimize the volume of second wastewater. Contamination characteristics of hot particulate were investigated and then a filtration process was presented to remove hot particulate in PFC solution generated through PFC decontamination process. The removal efficiency of PVDF(Poly vinylidene fluoride), PP(Polypropylene), Ceramic(Al$_{2}$O$_{3}$ filter showed more than 95$\%$. The removal efficiency of PVDF filter was a little lower than those of other kiters at same pressure(3psi). A ceramic filter showed a higher removal efficiency with other filters, while a little lower flux rate than other filters. Due to inorganic composition, a ceramic filter was highly stable against radio nuclides in comparison with PVDF and PP membrane, which generate H$_{2}$ gas in e-radioactivity atmosphere. Therefore, the adoption of ceramic filter is estimated to be suitable for the real nitration process.

• Applied Biological Chemistry
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• 제37권4호
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• pp.303-309
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• 1994

To develop the treatment process of swine wastewater using Rhodopseudomonas palustris KK14 with high utilizable ability of organic acids, some operating conditions were investigated and optimized in flask-scale and laboratory-scale reactors. The optimal operating conditions in photosynthetic bacteria (PSB) reactor of semi-continuous type were obtained at HRT 6 day, 5% (v/v/day) seeding rate of PSB sludge and 10% (v/v/day) returning rate of PSB return sludge. Under the above operating condition, COD level of the wastewater (initial COD: 10 g/l) was reduced to about 1.7 g/l after 4 days treatment and MLSS was held constant at $4{\sim}5\;g$ per liter. In laboratory-scale process consisted of 5.2 l anaearobic digestion reactor and 15 l PSB reactor, the total removal rates of COD and BOD were increased to 95% and 96% by the continuous operation for 5.36 days, respectively, showing $3kg\;COD/m^3/day$ COD loading rate and 1.1 Kg COD/Kg MLSS/day sludge loading rate in PSB reactor. The offensive odor was considerably removed through the treatment process of swine wastewater.

• Analytical Science and Technology
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• 제18권1호
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• pp.59-65
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• 2005

When the low level radioactivity sample is measured, it is required to have many samples. For increase of the sample volume, a scattering and absorbing probability of the emitted gamma-ray in the sample are to be increased. In order to correct the self-absorption effect, the counting efficiency must be calibrated according to a geometrical condition and sample density. But, it is impossible to determine efficiency for counting sample using standard source with the same geometrical condition and density. In this study, the measuring efficiencies were determined with various counting containers and densities. In order to compare the self-absorption effect with the sample density in the various sample container, the variation of the counting efficiency with the densities was investigated by adding NaI, which has high solubility and density. Also, they were compared with Monte Carlo simulation. The self-absorption effect was found to be significant in the low energy region below 0.5 MeV.