• Economic and Environmental Geology
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• v.49 no.2
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• pp.105-120
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• 2016

Most of riverside in Korea, in case of application of water curtain cultivation (WCC) technique, has been inveterately suffering from the gradual drawdown of groundwater level and related shortage of water resources during the WCC peak time. We believe that the water resources issue in these riverside areas can be effectively solved when the interaction between groundwater and nearby surface water is well understood. To investigate the connection between stream and ground water, and the influence of stream water on the nearby aquifer, this study examined the water temperature and oxygen and hydrogen stable isotopic compositions. The study area is well-known strawberry field applying the WCC technique in Sangdae-ri, Gadeok-myon, Cheongju City, and the sampling was done from February 2012 through June 2014 for stream and ground water. Some groundwater wells near stream showed big temporal variations in water temperature, and their oxygen and hydrogen stable isotopes showed similar compositions to those of adjacent stream water. This indicates that the influence of stream water is highly reflected in the stable isotopic composition of groundwater. Four cross-sectional lines from stream to hillside were established in the study area to determine the spatial differences in water quality of wells. At the late stage of WCC in February to March, groundwater of wells in line with short cross-sectional length showed the narrow range of isotopic compositions; however, those in the long cross-sectional line showed a wide compositional range. It was shown that the influence of the stream water at the late WCC stage have reached to the distance of 160 to 165 m from stream line, which is equivalent to the whole length and one-third point in each short and long cross-sectional line, respectively. Therefore, the wide compositional range in the long cross-sectional lines was not only due to the influence of stream water, but apparently resulted from the change of relative impact of each groundwater supplying from two or more aquifers. In view of stable isotopic compositions, there seems to be three different aquifers in this study area, which is competing for dominance of water quality in wells at each period of WCC.

• Journal of the Korea Organic Resources Recycling Association
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• v.24 no.3
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• pp.23-33
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• 2016

The characteristics of ammonia generated from alkaline stabilization facilities was investigated which are for organic sewage sludge from wastewater treatment plants. The highest concentration of ammonia was found in mixing and curing process in alkaline stabilization facility and ammonia mainly showed a range of 87.78 ppm($66.62mg/m^3$) to 1,933 ppm($1,467.01mg/m^3$) by detection tube. This is presumed to occur because nitrogen oxides are converted into ammonia as the sewage sludge is mixed with lime. In some facilities, hydrogen sulfide and methyl mercaptan were detected in relatively high concentrations, but odor materials except ammonia were not detected in most of the facilities. The concentration of ammonia caused by process was generally high in the order of "mixing > curing > output > storage > drying > input." It was found that odor compounds are removed by wet absorption using sulfuric acid and sodium hypochlorite in the 5 alkaline stabilization facilities currently in operation. Each facility was designed to meet the concentration of after-treatment emission in 1 ppm($0.76mg/m^3$), 50 ppm($37.95mg/m^3$) or 100 ppm($75.89mg/m^3$), but no facility satisfied the design standard for their emssion limit. In case of ammonia, some workplaces in alkaline stabilization facilities exceeded the exposure limits established by the Ministry of Labor. It appears that proper ventilation should be provided for the safety of workers in future. No odor compound including ammonia was found by detection tubes in the border of the facilities, but trace amounts of odor compounds are expected to exist, given the current operational status of facilities.

• The Korean Journal of Pesticide Science
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• v.16 no.3
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• pp.217-221
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• 2012

This study was carried out to evaluate residual characteristics of tolclofos-methyl in ginseng and elucidate the reason for its high detection rate from fresh ginseng selling at markets. Seeds of ginseng were sowed after seed dressing with tolclofos-methyl and after a year of growth, the young seedlings were transplanted to field. They were then harvested annually until three-years of growth and the pesticide residue was analyzed in them. LOD and LOQ of the pesticide were 0.001 and 0.003 mg/kg, respectively. Recovery test was carried out to validate the analytical method for tolclofos-methyl in ginseng. The ginseng seedlings were fortified with the test pesticide at the level of LOQ, ten times of LOQ and maximum residue concentration of tolclofos-methyl. Its recovery ranged from 77.37 to 100.16%. Residual concentration of tolclofos-methyl in ginseng seedlings just before transplanting and two-year-old ginseng were from 7.58 to 8.05 and from 6.46 to 6.79 mg/kg, respectively. In case of three-year-old ginseng, it was found to be from 4.18 to 4.35 mg/kg. As a result of annual pesticide residue analysis, concentration of the pesticide was found to decrease time-coursely in ginseng. This may be due to decomposition and increasing of fresh weight of the ginseng during the cultivation periods of three years.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.29 no.4
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• pp.477-487
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• 2019

Objectives: Firefighters are known to be exposed to a variety of toxic substances, but little information is available on the exposure profile of firefighting activities. The aims of this study were to conduct exposure monitoring of toxic chemicals at fire scenes, to compare the concentrations of respective chemicals among firefighting tasks, and to assess the main factors influencing the concentrations of chemicals. Methods: Researchers performed sampling at firefighting scenes during four weeks in 2013. At the scene, we collected samples based on firefighters' own activities and examined the situation and scale of the accident. Collected samples were classified into three categories, including fire extinguishing and overhaul, and were analyzed in the laboratory according to respective analysis methods. Results: A total of fourteen fire activity events were surveyed: five fire extinguishing, six overhaul, and three fire investigations. Although no substance exceeded the ACGIH TLV, PAHs were detected in every sample. Naphthalene ranged from 0.24 to 279.13 mg/㎥ (median 49.6 mg/㎥) and benzo(a)pyrene was detected in one overhaul case at 10.85 ㎍/㎥. Benzene (0.01-12.2 ppm) was detected in every task and exceeded the ACGIH TLV. No significant difference in concentrations between tasks was shown. Conclusions: These results indicate that all firefighting tasks generated various hazardous combustion products, including possible carcinogens.

• Journal of Korean Society for Geospatial Information Science
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• v.22 no.3
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• pp.57-69
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• 2014

As of 2013, Korean population density is 505 persons per $1km^2$ and is ranked 3rd place in the most densely populated countries exception of city-states. It shows clearly the population is concentrated in the city area. To fulfil this urban concentration population demand, the enlargement and complexation of buildings, subway and other underground spaces connection tendency has been intensified, and it is need to construct the indoor spatial information DB as well as the accurate indoor surveying DB to promote people's safety and social welfare. In this study, Sadang station and Incheon National Airport were aimed for the construction of Wi-Fi AP location DB and RadioMap DB by collecting the indoor AP raw datas by using mobile device and those collected results were ran through the process of verification, supplementation, and analyzation. To evaluate the performance of constructed DB, 10 points in Incheon Airport- 3rd flr in block A, and 9 points in Sadang station-B1 were selected and calculated the estimated points and ran evaluation experiment using survey positioning error, which is distance between real position and the estimated position. The result shows that Incheon international airport's average and standard deviation was separately 17.81m, 17.79m and Sadang station's average and standard deviation was separately 22.64m, 23.74m. In Sadang station's case, the areas near the exit has low performance of surveying position due to fewer visible AP points than other areas. As total datas were examined except those position, it was verified that the user's location was mapping close position in surveying positioning by using constructed DB. It means that constructed DB contains correct Wi-Fi AP locations and radio wave patterns in object region, so it is considered that the indoor spatial information service based on constructed DB would be available.

• Food Science and Preservation
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• v.19 no.5
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• pp.783-791
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• 2012

The purpose of the study was to provide baseline information that could encourage consumers and establish the direction of development for sprouts and leafy vegetables. A survey on the consumption and preference for sprouts and leafy vegetables of 823 people over 20 years of age in Seoul and Gyeonggi province was conducted. The preference for sprouts was higher in men ($3.75{\pm}0.96$) than in women ($3.64{\pm}0.84$), whereas the preference for leafy vegetables was higher in women ($4.06{\pm}0.74$) than in men ($3.88{\pm}0.90$). Based on age, the respondents in their 40s or above had high preferences for sprouts and leaf vegetables due to the importance that they accorded to health and nutrition (p<0.01). The sprouts and leafy vegetables were purchased mainly for their high nutritional value. The purchase frequency of once a month or more for leafy vegetables (82.7%) was higher than that for sprouts (57.1%). The consumers purchased sprouts and leafy vegetables mainly from a large discount store. The respondents in their 20s showed the highest percentage of purchasing from a local store whereas the older ones showed a high preference for traditional markets. The reason for the choice of the place of purchase was convenience. The freshness and price were important factors in the consumption of sprouts and leafy vegetables. In the case of leafy vegetables, the consumers preferred to buy them using the conventional weight measurement system rather than in small packages. On the other hand, mixed small packages were preferred for sprouts. The purchase frequency was correlated with the preferences, need for improvement and purchase intent for sprouts and leafy vegetables. The aspects that require improvement for producing high-quality sprouts and leafy vegetables were the nutritional and functional properties. To increase the consumption of sprouts and leafy vegetables, there is need for variations and improvement of the quality and safety of the products.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.3
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• pp.392-400
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• 2011

The objectives of this study were to analyze environmental microbial contamination levels by sampling the surfaces of processing lines and equipment and to verify CCPs of the HACCP plan in a fresh-cut produce processing plant The level of airborne microorganisms in the processing plant was $10^1$ log CFU/plate/15min. Total plate counts and coliform groups of the processing facilities were 1~2 log CFU/100 $cm^2$. No E. coli or S. aureus were detected in the processing plant. However, total plate counts on the cutting board for raw materials and on the spin-dryer were $4.20{\pm}2.12$ log CFU/$cm^2$ and $4.57{\pm}0.92$ log CFU/$cm^2$, respectively. These levels were higher than the safe microbial level, and therefore, the chance of cross-contamination during processing was increased. According to the results of microbiological analyses, total aerobic bacteria and coliform groups of the samples were increased after the second washing and spin-drying steps, due to cross-contamination from the spin-dryer. Thus, an effective method that can be used for microbial control during the washing and drying steps is needed for microbial control in fresh-cut produce processing plants. The results of a verification study also suggest that modification of the HACCP plan is needed along with additional CPs, which were identified as a second washing, spin drying, and the cold storage of final products.

• Fire Science and Engineering
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• v.17 no.1
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• pp.8-20
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• 2003

Natural gas has been supplied through underground pipelines and valve stations as a new city gas in Seoul. In contrast to its handiness the natural gas has very substantial hazards due to fires and explosions occurring from careless treatments or malfunctions of the transporting system. The main objectives of this study are to identify major hazards and to perform risk assessments after assessing reliabilities of the composing units in dealing with typical pipeline networks. there-fore two method, fault tree analysis ;1nd event tree analysis, are used here. Random valve stations are selected and considered its situation in location. The value of small leakage, large rupture, and no supply of liquefied natural gas is estimated as that of top event. By this calculation the values of small leakage are 3.29 in I)C valve station, 1.41 in DS valve station, those of large rup-lure are $1.90Times10_{-2}$ in DC valve station, $2.32$\times$10^{-2}$ in DS valve station, and those of no supply of LNG to civil gas company are $2.33$\times$10 ^{-2}$ , $2.89$\times$10^{-2}$ in each valve station. And through minimal cut set we can find the parts that is important and should be more important in overall system. In DC valve station one line must be added between basic event 26,27 because the potential hazard of these parts is the highest value. If it is added the failure rate of no supply of LNG is reduced to one fourth. In DS valve station the failure rate of basic event 4 is 92eye of no supply of LNG. Therefore if the portion of this part is reduced (one line added) the total failure rate can be decreased to one tenth. This analytical study on the risk assessment is very useful to prepare emergency actions or procedures in case of gas accidents around underground pipeline networks and to establish a resolute gas safety management system for loss prevention in Seoul metropolitan area.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.345-350
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• 2012

To investigate the exposure and health risk assessment for the residents near the D-asbestos mine in Chungbuk, Korea. We analyzed asbestos in the 20 ambient air and 23 activity based samples near the mine. The airborne sample results are showed that 8 of 20 samples ranged between 0.0025 to 0.0029 f/cc (fiber per cubic centimeter) and the others were below the detection limit by phase contrast microscopy (PCM). In addition, asbestos fibers were under the detection limit or not being by transmission electron microscopy (TEM). Based on interview and survey targeting the local residents, we made the activity based sampling (ABS) scenarios fit to the conditions of field. At the same time, we calculated the excess lifetime cancer risk (ELCR) of these ABS scenarios according to the ELCR average value and 95% upper confidence limit (UCL). At the case of weed whacking, soil digging and sweeping yard scenario, 95% UCL of ELCR exceeded the $1{\times}10^{-4}$, acceptable risk range for exposure. Based on our study results, it is necessary safety measures such as risk communication, abatement or management of naturally occurring asbestos (NOA).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.7
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• pp.380-394
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• 2015

This article reviews the papers published in the Korean Journal of Air-Conditioning and Refrigeration Engineering during 2014. It is intended to understand the status of current research in the areas of heating, cooling, ventilation, sanitation, and indoor environments of buildings and plant facilities. Conclusions are as follows. (1) The research works on the thermal and fluid engineering have been reviewed as groups of heat and mass transfer, cooling and heating, and air-conditioning, the flow inside building rooms, and smoke control on fire. Research issues dealing with duct and pipe were reduced, but flows inside building rooms, and smoke controls were newly added in thermal and fluid engineering research area. (2) Research works on heat transfer area have been reviewed in the categories of heat transfer characteristics, pool boiling and condensing heat transfer and industrial heat exchangers. Researches on heat transfer characteristics included the results for thermal contact resistance measurement of metal interface, a fan coil with an oval-type heat exchanger, fouling characteristics of plate heat exchangers, effect of rib pitch in a two wall divergent channel, semi-empirical analysis in vertical mesoscale tubes, an integrated drying machine, microscale surface wrinkles, brazed plate heat exchangers, numerical analysis in printed circuit heat exchanger. In the area of pool boiling and condensing, non-uniform air flow, PCM applied thermal storage wall system, a new wavy cylindrical shape capsule, and HFC32/HFC152a mixtures on enhanced tubes, were actively studied. In the area of industrial heat exchangers, researches on solar water storage tank, effective design on the inserting part of refrigerator door gasket, impact of different boundary conditions in generating g-function, various construction of SCW type ground heat exchanger and a heat pump for closed cooling water heat recovery were performed. (3) In the field of refrigeration, various studies were carried out in the categories of refrigeration cycle, alternative refrigeration and modelling and controls including energy recoveries from industrial boilers and vehicles, improvement of dehumidification systems, novel defrost systems, fault diagnosis and optimum controls for heat pump systems. It is particularly notable that a substantial number of studies were dedicated for the development of air-conditioning and power recovery systems for electric vehicles in this year. (4) In building mechanical system research fields, seventeen studies were reported for achieving effective design of the mechanical systems, and also for maximizing the energy efficiency of buildings. The topics of the studies included energy performance, HVAC system, ventilation, and renewable energies, piping in the buildings. Proposed designs, performance performance tests using numerical methods and experiments provide useful information and key data which can improve the energy efficiency of the buildings. (5) The field of architectural environment was mostly focused on indoor environment and building energy. The main researches of indoor environment were related to the evaluation of work noise in tunnel construction and the simulation and development of a light-shelf system. The subjects of building energy were worked on the energy saving of office building applied with window blind and phase change material(PCM), a method of existing building energy simulation using energy audit data, the estimation of thermal consumption unit of apartment building and its case studies, dynamic window performance, a writing method of energy consumption report and energy estimation of apartment building using district heating system. The remained studies were related to the improvement of architectural engineering education system for plant engineering industry, estimating cooling and heating degree days for variable base temperature, a prediction method of underground temperature, the comfort control algorithm of car air conditioner, the smoke control performance evaluation of high-rise building, evaluation of thermal energy systems of bio safety laboratory and a development of measuring device of solar heat gain coefficient of fenestration system.