• Journal of Korean Society of Environmental Engineers
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• v.31 no.11
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• pp.1033-1040
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• 2009

One thing to note in cyclone operation and design is to minimize the pressure drop with the enhancement of the efficiency of dust collection. This can be facilitated by the detailed resolution of complex fluid flow occurring inside a cyclone. To this end, the main objective of this study was to obtain the detailed fluid dynamics by the development of a reliable computation method and thereby to figure out the physics of dust collection mechanism for more extreme environment caused by high temperature and pressure condition. First of all, the computer program developed was evaluated against experimental result. That is, the numerical calculation predicts well the data of experimental pressure drop as a function of flow rate for the elevated pressure and temperature condition employed in this study. The increase of pressure and temperature generally affects significantly the collection efficiency of fine particle but the effect of pressure and temperature appears contrary each other. Therefore, the decrease of collection efficiency caused by the high operating temperature mainly due to the decrease of gaseous density can be remedied by increase of operating pressure. After the evaluation of the program, a series of parametric investigations are performed in terms of major cyclone design or operating parameters such as tangential velocity and vortex finder diameter for dusts of a certain range of particle diameters, etc. As expected, tangential velocity plays the most important effect on the collection efficiency. And the efficiency was not affected significantly by the change of the length of vortex finder but the diameter of vortex finder plays an important role for the enhancement of collection efficiency.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.304-314
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• 2020

This study examined the experiences of the suicide crisis and recovery process by elderly women living alone to identify the essential meaning and components of life as a life to live again. In addition, the recovery of the research participants, as well as the phenomenon of such changes in thought and life, were examined. The results of this study were as follows. Data analysis yielded four components, eight sub-components, and 16 semantic unit reductions. There were four components of suicide attempts and recovery experiences of elderly women. They were "disconnection and disqualification," "repeated hardships," "road of prosperity in trouble," and "generous tolerance." The essential topics of these components have emerged not as individual but as holistic and contextually connectable topics. Finally, to summarize the results, the essential semantic structure of the suicide attempt and recovery experience of elderly women living alone is a result of a dysfunctional social structure and environment, which has placed pressure on the life of research participants. As an alternative method to overcome, they tried to solve the problem through the extreme practice of suicide attempts, but positive energy to live again due to emotional recovery factors recognized through suicide failures have made it possible to cope with the difficult reality.

• Korean Journal of Microbiology
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• v.51 no.4
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• pp.427-434
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• 2015

Most of halophilic archaea are found in the various hypersaline environments including solar saltern, salt lake with very high salt concentration. The present study is about isolation and characterization of halphilic archaea from Gomso solar saltern known as a representative high salt environment in Korea. In order to isolate the halophilic archaea, we prepared and used high salt medium. Finally, total 7 strains obtained were tentatively identified based on comparative similarity analysis for 16S rRNA gene sequence and physiological traits. All halophilic archaea belonged to Haloruburm, Halogeometriucm, Halobacterium, and Haloarcula genera. These isolates were all Gram-staining negative, and growth was not observed using nitrate as an alternative electron acceptor under anaerobic conditions. In addition, all isolates required about 12-30% (w/v, NaCl) salt. This case study might provide basic information on microbial isolation technologies and related research in halophilic microorganisms from domestic halophilic environments, and contribute to obtaining useful indigenous halophilic archaea in a variety of extreme environmental conditions.

• Korean Journal of Microbiology
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• v.43 no.4
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• pp.250-255
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• 2007

The RecA protein of Deinococcus radiodurans is essential for the extreme radiation resistance of this organism. The central steps involved in recombinational DNA repair require DNA-dependent ATP hydrolysis by recA protein. Key feature of RecA protein-mediated activities is the interactions with ssDNA and dsDNA. The ssDNA is the site where RecA protein filament formation nucleates and where initiation of DNA strand exchange takes place. The effect of sequence heterogeneity of ssDNA was examined in this experiment. The rate of homopolymeric synthetic ssDNA-dependent ATP hydrolysis was constant or nearly so over a broader range of pHs. For poly(dT)-dependent ATP or dATP hydrolysis, rates were generally faster, with a broader optimum between pH 7.0 and 8.0. Activities of RecA protein were affected by the ionic environment. The ATPase activity was shown to have different sensitivity to anionic species. The presence of glutamate seemed to slimulate the hydrolytic activity. Dr RecA protein was shown to require $Mg^{2+}$ ion greater than 2 mM for binding to etheno ssDNA and the binding stoichiometry of 3 nucleotide for RecA protein monomer.

• Journal of Korean Society of Forest Science
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• v.103 no.4
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• pp.605-612
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• 2014

This study was conducted to predict the changes of yearly productive area distribution for Quercus mongolica under climate change scenarios. For this, site index equations by ecoprovinces were first developed using environmental factors. Using the large data set from both a digital forest site map and a climatic map, a total of 48 environmental factors including 19 climatic variables were regressed on site index to develop site index equations. Two climate change scenarios, RCP 4.5 and RCP 8.5, were then applied to the developed site index equations and the distribution of productive areas for Quercus mongolica were predicted from 2020 to 2100 years in 10-year intervals. The results from this study show that the distribution of productive areas for Quercus mongolica generally decreases as time passes. It was also found that the productive area distribution of Quercus mongolica is different over time under two climate change scenarios. The RCP 8.5 which is more extreme climate change scenario showed much more decreased distribution of productive areas than the RCP 4.5. It is expected that the study results on the amount and distribution of productive areas over time for Quercus mongolica under climate change scenarios could provide valuable information necessary for the policies of suitable species on a site.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.4
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• pp.307-313
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• 2016

When liquefied natural gas (LNG) is stored in a tank, it is necessary to maintain low temperature. It is very important that insulation techniques are applied to the LNG cargo because of this extreme environment. Hence, laminated wood, especially plywood, is widely used as the structural member and insulation material in LNG cargo containment systems (CCS). However, fracture of plywood has been reported recently, owing to sloshing effect. Therefore, it is necessary to increase the strength of the structural member for solving the problem. In this study, compressed wood, which is used as a support in LNG independent type B tanks, was considered as a substitute for plywood. Compression and bending tests were performed on compressed wood under ambient and cryogenic temperatures to estimate the mechanical behaviors and fracture characteristics. In addition, the direction normal to the laminates surface was considered as an experimental variable. Finally, the feasibility of using compressed wood for an LNG CCS was evaluated from the test results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2013.05a
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• pp.845-848
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• 2013

Due to intense climate changes and extreme weather conditions a noticeable decrease has been observed in the growth of certain plants. The indoor plant factories would have certain benefits including increase in crop yield, reduction in distribution cost, and maintains the healthy freshness level of the agricultural product. Recently, an artificial light source with optimum wavelength is spot lighted to fulfill the need of light for the indoor plant factories. The energy efficient light emitting diodes (LED) provide the essential light energy for the proper growth of indoor cultivated plants. This work focuses to utilize ubiquitous sensors network(USN) in providing suitable environment for the proper growth of agricultural product inside the indoor plant factory. The proposed system makes use of sensors and actuators, communicating each other through WPAN, ZigBee network. The proposed system obscured the traditional indoor plant factories with easy installation and wireless connectivity of the sensors and actuators along with eliminating the web of wires reducing the initial installation and maintenance cost.

• Atmosphere
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• v.25 no.4
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• pp.611-622
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• 2015

Heavy rainfall ($>30mm\;hr^{-1}$) over the Korean Peninsula is examined in order to understand thermo-dynamic characteristics of the atmosphere, using radiosonde observational data from seven upper-air observation stations during the last 17 years (1997~2013). A total of 82 heavy rainfall cases during the summer season (June-August) were selected for this study. The average values of thermo-dynamic indices of heavy rainfall events are Total Precipitable Water (TPW) = 60 mm, Convective Available Potential Energy (CAPE) = $850J\;kg^{-1}$, Convective Inhibition (CIN) = $15J\;kg^{-1}$, Storm Relative Helicity (SRH) = $160m^2s^{-2}$, and 0~3 km bulk wind shear = $5s^{-1}$. About 34% of the cases were associated with a Changma front; this pattern is more significant than other synoptic pressure patterns such as troughs (22%), migratory cyclones (15%), edges of high-pressure (12%), typhoons (11%), and low-pressure originating from Changma fronts (6%). The spatial distribution of thermo-dynamic conditions (CAPE and SRH) is similar to the range of thunderstorms over the United States, but extreme conditions (supercell thunderstorms and tornadoes) did not appear in the Korean Peninsula. Synoptic conditions, vertical buoyancy (CAPE, CIN), and wind parameters (SRH, shear) are shown to discriminate among the environments of the three types. The first type occurred with high CAPE and low wind shear by the edge of the high pressure pattern, but Second type is related to Changma front and typhoon, exhibiting low CAPE and high wind shear. The last type exhibited characteristics intermediate between the first and second types, such as moderate CAPE and wind shear near the migratory cyclone and trough.

• Korean Journal of Community Nutrition
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• v.12 no.3
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• pp.272-283
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• 2007

This study was performed to delineate the relationship between lifestyle and nutritional risk factors associated with hypertension in representative middle-aged Korean population. Hypertension in this study is defined as hypertensive ($SBP{\geq}140mmHg\;or\;DBP{\geq}90mmHg$) adults without recognition of a disease state before a health exam. With data from the 1998 and 2001 National Health and Nutritional Survey, nutrient intakes of 6,112 adults, 40-64 years of age were calculated using food composition database and matched with health examination records by individual ID. After excluding those with extreme intake values, the number of final subjects included in the analysis was 5,200 (male 2,458, female 2,742). Using logistic regression method, socio-demographic data, lifestyle factors, and nutrient intakes were analyzed. Risky factors for hypertension revealed in this study were age, sex, BMI over 23, waist circumference, alcohol intake of more than 16g (male) or 8g (female). Regarding nutrient intakes, the intakes of highest quartile for energy (${\geq}2363.0kcal$) and protein (${\geq}90.2g$) were significantly associated with higher risk of hypertension after adjusting for age, sex, and other socio-demographic factors (OR=1.312(1.046-1.711), OR=1.488(1.194-1.854), respectively)). Although high intakes of sodium (${\geq}6604.0mg$) and phosphorus seemed to be risk factors of hypertension also before energy adjustment (OR=1.278(1.034-1.581), OR=1.280(1.024-1.600), respectively), only high intakes of energy and protein remained significant after adjustment. This study revealed that modifying risky lifestyles and dietary patterns, especially high energy intake, high protein intake, and high alcohol drinking, in middle-aged Korean adults could result in a prevalence decrease and/or prevention of hypertension.

• Korean Journal of Ecology and Environment
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• v.50 no.1
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• pp.46-56
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• 2017

The Youngsan River estuary was physically changed by the construction of a sea embankment at near the mouth of estuary. Weirs were also constructed recently in the freshwater zone and it was reported that algal blooms occur more frequently. The freshwater introduced into saltwater zone from sluice gates of the embankment affects water quality but it has not been addressed that how the freshwater inputs influence the health of marine ecosystem. In this study, we used the data of water properties and phytoplankton communities collected at three stations for 4 days including before the freshwater discharge, during the discharge and after 1 and 2 days of discharge events. WQI(water quality index), TRIX (trophic status index) and P-IBI(phytoplankton index of biotic integrity) were used to evaluate the ecosystem health and long-term data were also utilized to determine the criteria for P-IBI. The results showed that grades of the ecosystem health assessed by the indices were low at the station near the gates and increased as downstream. However, the temporal pattern of grades was different depending on methods. Grades of WQI and TRIX decreased during the discharge and restored after the discharge whereas the grades of P-IBI decreased slightly even after the discharge. This suggests that P-IBI is more applicable to estuarine systems where experience extreme change of water properties than WQI and TRIX since P-IBI includes phytoplankton that can respond quickly to the change.