• Journal of the Korean Crystal Growth and Crystal Technology
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• v.21 no.3
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• pp.99-104
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• 2011

A stoichiometric mixture of evaporating materials for $MgGa_2Se_4$ single crystal thin films was prepared from horizontal electric furnace. The crystal structure of these compounds has a rhombohedral structure with lattice constants $a_0=3.953\;{\AA}$, $c_0=38.890\;{\AA}$. To obtain the single crystal thin films, $MgGa_2Se_4$ mixed crystal was deposited on thoroughly etched semi-insulating GaAs(100) substrate by the Hot Wall Epitaxy (HWE) system. The source and substrate temperatures were $610^{\circ}C$ and $400^{\circ}C$, respectively. The crystalline structure of the single crystal thin films was investigated by the double crystal X-ray rocking curve and X-ray diffraction ${\omega}-2{\theta}$ scans. The carrier density and mobility of $MgGa_2Se_4$ single crystal thin films measured from Hall effect by van der Pauw method were $6.21{\times}10^{18}\;cm^{-3}$ and 248 $cm^2/v{\cdot}s$ at 293 K, respectively. The optical absorption of $MgGa_2Se_4$ single crystal thin films was investigated in the temperature range from 10 K to 293 K. The temperature dependence of the optical energy gap of the $MgGa_2Se_4$ obtained from the absorption spectra was well described by the Varshni's equation, $E_g(T)=E_g(0)-({\alpha}T^2/T+{\beta})$. The constants of Varshni's equation had the values of $E_g(0)=2.34\;eV$, ${\alpha}=8.81{\times}10^{-4}\;eV/K$ and ${\beta}=251\;K$, respectively.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.3
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• pp.175-194
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• 2014

This study attempts to identify the spatial distributions of Achnanthes convergens, and elucidate the environmental factors that affect the Periphyton diatom habitat. Data in 250 points of Nakdong river basin are collected between April(primary) and September(secondary) 2012, with the National Institute of Environmental Research's support. We define "clean area" over 10% of Achnanthes convergens appearance, and the others as "non-clean areas". Spatial statistics of Kriging, Hotspot, LISA are used in this study. Results show that 1) 56 points are identified as clean areas in the primary survey, while 41 points are discovered in the following survey; 2) using water quality variables, density of turbidity(clean $101.83{\mu}s/cm$; non-clean $598.48{\mu}s/cm$) and conductivity(clean 1.95 NTU; nonclear 5.58 NTU) are five-fold lower in clean-areas; 3) Habitat and Riparian Factors in Nakdong basin illustrate that natural sand bar, diversity of velocity, sediment condition, levee material, riverside land affect Achnanthes convergens; 4) Hotspots of Achnanthes convergens are located in watersheds, including upper Andong Dam, upper Imha dam, Wi-cheon, Miryang river, Nam river and Hwang river whereas mainstream/downstream of Nakdong river and Keumho river watershed are shown as coldspots.

• The Journal of Korean Academy of Prosthodontics
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• v.45 no.2
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• pp.169-181
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• 2007

Statement of problem: Titanium is well known as a proper metal for the dental restorations, because it has an excellent biocompatibility, resistance to corrosion, and mechanical property. However, adhesion between titanium and dental porcelains is related to the diffusion of oxygen to the reaction layers formed on cast-titanium surfaces during porcelain firing and those oxidized layers make the adhesion difficult to be formed. Many studies using mechanical, chemical and physical methods to enhance the titanium-ceramic adhesion have been actively performed. Purpose: This study meant to comparatively analyse the adhesion characteristics depending on different titanium surface coatings after coating the casts and wrought titanium surfaces with Au and TiN. Material and method: In this study, the titanium specimens (CP-Ti, Grade 2, Kobe still Co. Japan) were categorized into cast and wrought titanium. The wrought titanium was cast by using the MgO-based investment(Selevest CB, Selec). The cast and wrought titanium were treated with Au coating($ParaOne^{(R)}$., Gold Ion Sputter, Model PS-1200) and TiN coating(ATEC system, Korea) and the ultra low fusing dental porcelain was fused and fired onto the samples. Biaxial flection test was done on the fired samples and the porcelain was separated. The adhesion characteristics of porcelain and titanium after firing and the specimen surfaces before and after the porcelain fracture test were observed with SEM. The atomic percent of Si on all sample surfaces was comparatively analysed by EDS. In addition, the constituents of specimen surface layers after the porcelain fracture and the formed compound were evaluated by X-ray diffraction diagnosis. Result: The results of this study were obtained as follows : 1. The surface characteristics of cast and wrought titanium after surface treatment(Au, TiN, $Al_2O_3$ sandblasting) were similar and each cast and wrought titanium showed similar bonding characteristics. 2. Before and after the biaxial flection test, the highest atomic weight change of Si component was found in $Al_2O_3$ sandblasted wrought titanium(28.6at.% $\rightarrow$ 8.3at.%). On the other hand, the least change was seen in Au-Pd-In alloy(24.5at.% $\rightarrow$ 9.1at.%). 3. Much amount of Si components was uniformly distributed in Au and TiN coated titanium, but less amount of Si's was unevenly dispersed on Al2O3 sandblasting surfaces. 4. In X-ray diffraction diagnosis after porcelain debonding, we could see $Au_2Ti$ compound and TiN coating layers on Au and TiN coated surfaces and $TiO_2$, typical oxide of titanium, on all titanium surfaces. 5. Debonding of porcelain on cast and wrought titanium surface after the biaxial flection is considered as a result of adhesion deterioration between coating layers and titanium surfaces. We found that there are both adhesive failure and cohesive failure at the same time. Conclusion: These results showed that the titanium-ceramic adhesion could be improved by coating cast and wrought titanium surfaces with Au and TiN when making porcelain fused to metal crowns. In order to use porcelain fused to titanium clinically, it is considered that coating technique to enhance the bonding strength between coating kKlayers and titanium surfaces should be developed first.

• Journal of the Korean Society of Food Science and Nutrition
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• v.45 no.10
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• pp.1406-1413
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• 2016

This study was carried out to evaluate the toxicity of ethanolic extracts of Morus alba L. branch (ME). In the reverse mutation test, Salmonella Typhimurium TA98, TA100, TA1535, TA1357, and Escherichia coli WP2uvrA were used to estimate the mutagenic potential of ME. Sprague-Dawley rats were orally administered ME at levels of 1,250, 2,500, and 5,000 mg/kg for the single-dose toxicity test and 500, 1,000, and 2,000 mg/kg/d for the repeated-dose toxicity test for 28 consecutive days. As expected, reverse mutation was not detected at any concentration of ME, regardless of application of the metabolic activation system with or without S9 mix. In the single-dose toxicity test, ME caused neither significant visible signs of toxicity nor mortality in rats, and $LD_{50}$ was estimated to be over 5,000 mg/kg. In the repeated-dose toxicity test, ME administration at 500, 1,000, and 2,000 mg/kg for 28 days to male or female rats did not result in mortality. Similarly, no toxicologically significant treatment-related changes in body weight, food intake, or organ weights were noted. Several hematological and biochemical parameters in both genders showed significant differences, but these were within normal ranges. These results support the safe use of ME.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.4
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• pp.113-125
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• 1984

Water supply has been mainly dependent on the construction of the dams in Korea. It is difficult, however, to continue to construct dams for many reasons, such as the decrease of construction sites, the increase of construction costs, the compensation of residents in flooded areas, and the environmental effects. Water demands have increased and are expected to continue increasing due to the concentration of people in the cities, the rise of the living standard, and rapid industrial growth. It is acutely important to find countermeasures such as development of ground water, desalination, and recycling of waste water to cope with increasing water demands. Recycling waste water includes all means of supplying non-potable water for their respective usages with proper water quality which is not the same quality as potable water. The usages of the recycled water include toilet flushing, air conditioning, car washing, yard watering, road cleaning, park sprinkling, and fire fighting, etc. Raw water for recycling is obtained from drainage water from buildings, toilets, and cooling towers, treated waste water, polluted rivers, ground water, reinfall, etc. The water quantity must be considered as well as its quality in selecting raw water for the recycling. The types of recycling may be classified roughly into closed recycle systems and open recycle systems, which can be further subdivided into individual recycle systems, regional recycle systems and large scale recycle system. The treatment methods of wastewater combine biochemical and physiochemical methods. The former includes activated sludge treatment, bio-disc treatment, and contact aeration treatment, and the latter contains sedimentation, sand filtration, activated carbon adsorption, ozone treatment, chlorination, and membrane filter. The recycling patterns in other countries were investigated and the effects of the recycling were divided into direct and indirect effects. The problems of water reuse in recycle patterns were also studied. The problems include technological, sanitary, and operational problems as well as cost and legislative ones. The duties of installation and administrative organization, structural standards for reuse of water, maintenance and financial disposal were also studied.

• Progress in Medical Physics
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• v.18 no.3
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• pp.118-125
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• 2007

In this study we estimated a geometric correlation among digitally reconstructed radiographic image (DRRI), kV x-ray image (kVXI) from the On-Board Imager (OBI) and electric portal image (EPI). To verify geometric correspondence of DRRI, kVXI and EPI, specially designed phantom with indexed 6 ball bearings (BBs) were employed. After accurate setup of the phantom on a treatment couch using orthogonal EPIs, we acquired set of orthogonal kVXIs and EPIs then compared the absolute positions of the center of the BBs calculated at each phantom plane for kVXI and EPI respectively. We also checked matching result for obliquely incident beam (gantry angle of $315^{\circ}$) after 2D-2D matching provided by OBI application. A reference EPI obtained after initial setup of the phantom was compared with 10 series of EPIs acquired after each 2D-2D matching. Imaginary setup errors were generated from -5 mm to 5 mm at each couch motion direction. Calculated positions of all center positions of the BBs at three different images were agreed with the actual points within a millimeter and each other. Calculated center positions of the BBs from the reference and obtained EPIs after 2D-2D matching agreed within a millimeter. We could tentatively conclude that the OBI system was mechanically quite reliable for image guided radiation therapy (IGRT) purpose.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.482-489
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• 2012

Visual monitoring is hard to apply on fish because they are living in a water system. To overcome this problem, acoustic telemetry, which is effective for underwater monitoring, is often used for studying fish behaviors, such as movement distance, route and patterns. In this study, in order to monitor the movement pattern of Squaliobarbus curriculus (family Cyprinidae), we used acoustic telemetry and identified the home range and movement distances. A total of nine individuals were released at two different locations: one is at the estuary barrage (Sc1~3) and the other is at the lower part of Baekjae Weir (Sc4~9), located in Geum River. Approximately, a 70 km section from the estuary barrage was investigated. Fish, which were released at the estuary barrage, utilized up to 12.7 km upstream as home range from the release site. At the lower part of Baekjae Weir, most of the fish moved and stayed within a 7.2 km downstream area, except for Sc6, which moved 53.4 km (linear maximum distance from release site) downstream from the release site. Relatively small sized fish (Sc7~9) did not show any movement. Accumulated movement distance significantly correlated with the standard length of S. curriculus ($r_s$=0.715, p=0.03). Moreover, the standard length of moving fish was significantly larger than that of not moving fish (Mann-Whitney U test, p=0.024). Therefore, the movement distance of S. curriculus has been correlated with fish size; movement distance was increased with the standard fish length. Although the sample size of monitored fish was small, various meaningful data were collected by acoustic telemetry. Consequently, this technique could be a method available for effectively monitoring the behavior and ecology of native Korean and endemic species.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.444-452
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• 2012

We conducted a comprehensive monitoring for freshwater food web in a wetland system (Jangcheok Lake), from May to October, 2011. Monthly sampling for zooplankton, fish as well as organic matters, was implemented. In order to understand the food web structure and energy flow, we applied stable isotope analysis to the collected samples, based on ${\delta}^{13}C$ and ${\delta}^{15}N$ values of epiphytic particulate organic matter(EPOM) and particulate organic matter (POM), epiphytic and planktonic zooplankton, fish (Lepomis macrochirus). In the study site, epiphytic and planktonic zooplankton was 24 and 30 species, respectively, and coincidence species between epiphytic and planktonic zooplankton were 20 species. Epiphytic zooplankton were more abundant during the spring and early summer (May to July); however, planktonic zooplankton were more abundant during the autumn (September to October) season. Stable isotope analysis revealed that fish and epiphytic zooplankton had seasonal variations on their food sources. EPOM largely contributed epiphytic zooplankton in spring (May), but increasing contribution of POM in autumn (September) was detected. However, planktonic zooplankton depended on only POM in both seasons. Fish utilized both epiphytic and planktonic zooplankton, but small sized (1~3 cm), fish preferred epiphytic zooplankton, where as larger sized (4~7 cm) fish tended to consume planktonic zooplankton, and epiphytic zooplankton had important role in energy transfer. This pattern was clear when results of spring and autumn stable isotope analysis were compared. From the results of this study, we confirmed that wetlands ecosystem supported various epiphytic and planktonic zooplankton species, they depend on other food items, respectively. L. macrochirus also showed a difference of food source according to the body size, they depend on seasonal density change of zooplankton. In particular, epiphytic zooplankton was very important for growth and development of young fish in the spring.

• Journal of Life Science
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• v.22 no.6
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• pp.703-712
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• 2012

Adeno-associated virus (AAV) has been considered to be a very safe and efficient gene delivery system. However, the major obstacles to therapeutic usage of AAV have been to achieve highly efficient and reproducible production processes, and also to develop a reliable quantifying method of various serotypes with a simple protocol. We compared the efficiency of the conventional production protocol of AAV2 and adenovirus (Ad) co-infection to that of a new method containing AAV2 infection followed by pHelper transfection. We tested HEK293 and 293T, and further examined the time-dependent changes of AAV2 production. The new method of AAV2 and pHelper DNA gave about ten times higher production efficiency than that of the conventional protocol. The highest production efficiency in 293T was achieved as $1.61{\times}10^5$ virus genomes (v.g.)/cell by the new method of 10 MOI of AAV2 infection and 5 days post-infection. This protocol of the highest efficiency was then applied to produce various AAV serotypes and showed the efficiencies higher than $10^5$ v.g./cell. Next, we designed the universal PCR primers of highly conserved regions for various AAV serotypes to develop a simple and reliable titration method. The universal primers could amplify all the tested AAV serotypes with similar sensitivities by ten molecular copies. Therefore, this pair of universal primers can be further utilized to detect AAV contaminants in therapeutic adenoviral vectors.

• Journal of Animal Science and Technology
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• v.46 no.3
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• pp.459-468
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• 2004

An experiment was conducted to establish comparison of ventulation efficiency in an enclosed and conventional growing-finishing pig house. The main results of the experiment are as follows : In the established temperature was sustained at the level of summer 24.8${\sim}$29.1$^{\circ}C$, winter 17.9${\sim}$23.1$^{\circ}C$ during the experimental period of enclosed growing-finishing pig house, and conventional growing-finishing pig house was at the lovel of summer 24.7${\sim}$32.3$^{\circ}C$, winter 14.5${\sim}$18.2$^{\circ}C$ during the experimental period respectively. As for the results of dertimental gas(ammonia) concentration ratio analysis, while the conventional pig house sustained of summer 9.3${\sim}$16.9 mg/$\ell$ level, enclosed growing-finishing pig house sustained of summer 7.9${\sim}$16.1 mg/$\ell$, and the latter one is lower than that of the conventional growing-finishing pig house. Air flow rate on the floor level which is the low part of pen and the active area of pigs in the enclosed growing and finishing pig house during winter was measured at 0 to 0.87 m/s at the 0.01 to 2.73 m/s at the maximum ventilation efficiency. As for breeding pigs in summer, the pigs from the conventional pig house weighed 100.2kg, on the other hand, the pigs from enclosed growing-finishing pig house weighed 107.3 kg ; the differnce between the two kinds was about 7 kg. This was because the most adequate environment, which was not influenced by the exterior atmosphere, was offered to the pigs from enclosed growing-finishing pig house, and all of this could reduce pigs stress effectively.