• The Journal of Korean Academy of Prosthodontics
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• v.47 no.2
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• pp.222-231
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• 2009

Statements of the problem: Over the past decades, conventional complete dentures were used for various patients although they have incomplete function. Overdentures using dental implants could help the improvement of denture function. Purpose: The purpose of this study was to compare the strains of abutment and bone on implant overdenture between splinted and unsplinted type of prosthesis. Additionally, the strain values of parallel placed implant model and unparallel placed implant model were compared. Material and methods: Two acrylic resin model were prepared and two implants were placed at the canine positions in each model. In the first model, two implant were placed parallel. In the second model, two implants were placed with 10 degree labiolingual divergence. Two types of abutment were connected to the fixtures alternatively. One was splint type of Hader bar, the other was unsplint type of ball abutment. Overdentures were fabricated with corresponding attachment systems and seated on abutments. Strains of abutments and labial bone simulants were measured with electric resistance strain gauges when static load from 100 N to 200 N were applied to overdentures. Results: 1. Splinted type of overdentures using bar and clip showed higher absolute strain values. But the strain was compressive and the load was shared by two implants(P<.05). 2. Unsplinted type overdentures using ball and O-ring showed low absolute strain values(P<.05). 3. Labially inclined implant showed higher tensile strain values in unsplinted type of prosthesis than in splinted type of prosthesis. Lingually inclined implant showed rather low strain values under load(P<.05). 4. Non parallel implant model showed higher absolute strain values than parallel placed implant model comprehensively(P<.05).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.1 s.116
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• pp.62-75
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• 2007

This paper describes a shaped-beam antenna for increasing the antenna gain of a radiating element. The proposed antenna structure is composed of an exciting element and a multi-layered disk array structure(MDAS). The stack micro-strip patch elements were used as the exciter for effectively radiating the electromagnetic power to the MDAS over the broadband, and finite metallic disk array elements - which give the role of a director for shaping the antenna beam with the high gain - were finitely and periodically layered onto it. The efficient power coupling between the exciter and the MDAS should be carried out in such a way that the proposed antenna has a high gain characteristic. The design parameters of the exciter and the MDAS should be optimized together to meet the required specifications to meet the required specifications. In this study, a shaped-beam antenna with high gain was optimally designed under the operating conditions with a linear polarization and the frequency band of $9.6{\sim}10.4\;GHz$. Two methods constructed using thin dielectric film and dielectric foam materials respectively were also proposed in order to implement the MBAS of the antenna. In particular, through the computer simulation process, the electrical performance variations of the antenna with the MDAS realized by the thin dielectric film materials were shown according to the number of disk array elements in the stack layer. Two kinds of antenna breadboard with the MDAS realized with the thin dielectric film and dielectric foam materials were fabricated, but experimentation was conducted only on the antenna breadboard(Type 1) with the MDAS realized with the thin dielectric film materials according to the number of disk array elements in the stack layer in order to compare it with the electrical performance variations obtained during the simulation. The measured antenna gain performance was found to be in good agreement with the simulated one, and showed the periodicity of the antenna gain variations according to the stack layer number of the disk array elements. The electrical performance of the Type 1 antenna was measured at the center frequency of 10 GHz. As the disk away elements became the ten stacks, a maximum antenna gain of 15.65 dBi was obtained, and the measured return loss was not less than 11.4 dB within the operating band. Therefore, a 5 dB gain improvement of the Type 1 antenna can be obtained by the MDAS that is excited by the stack microstrip patch elements. As the disk array elements became the twelve stacks, the antenna gain of the Type 1 was measured to be 1.35 dB more than the antenna gain of the Type 2 by the outer dielectric ring effect, and the 3 dB beam widths measured from the two antenna breadboards were about $28^{\circ}$ and $36^{\circ}$ respectively.

• Applied Chemistry for Engineering
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• v.25 no.1
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• pp.78-83
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• 2014

In this research, we evaluated the performance and characteristics of carbon supported PtM (M = Ni and Y) alloy catalysts (PtM/Cs) synthesized by a modified polyol method. With the PtM/Cs employed as a catalyst for the oxygen reduction reaction (ORR) of cathodes in proton exchange membrane fuel cells (PEMFCs), their catalytic and ORR activities and electrical performance were investigated and compared with those of commercial Pt/C. Their particle sizes, particle distributions and electrochemically active surface areas (EAS) were measured by TEM and cyclic voltammetry (CV), while their ORR activity and electrical performance were explored using linear sweeping voltammetries with rotating disk electrodes and rotating ring-disk electrodes as well as PEMFC single cell tests. TEM and CV measurements show that PtM/Cs have the compatible particle size and EAS with Pt/C. When it comes to ORR activity, PtM/C showed the equivalent or better half-wave potential, kinetic current density, transferred electron number per oxygen molecule and $H_2O_2$ production(%) to or than commerical Pt/C. Based on results gained by the three electrode tests, when the PEMFC single cell tests were carried out, the current density measured at 0.6 V and maximum power density of PEMFC single cell adopting PtM/C catalysts were better than those adopting Pt/C catalyst. It is therefore concluded that PtM/C catalysts synthesized by modified polyol can result in the equivalent or better ORR catalytic capability and PEMFC performance to or than commercial Pt/C catalyst.

• The Korean Journal of Ecology
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• v.24 no.5
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• pp.281-288
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• 2001

The relationships between the growths of Abies koreana W. and climatic factors were analyzed by the use of tree-ring analysis at the subalpine belt of Mt. Halla National Park. The four cores were extracted from each 21 trees at north-facing slope (1,900m a.s.1.). The site chronology was established on the periods from 1912 to 1999. The growth of A. koreana was very poor, in particular in the years of 1982, 1988 and 1996. Simple correlation was employed to analyze the relationship between the growth of A. koreana and climatic factors. The result of simple correlation indicates that the growth of A. koreana represent positive correlations both with the mean temperatures of April and previous November, and the precipitation of previous December and January. The presence of large number of frost-damaged scars in the individual trees of A. koreana implies that local freezing temperature conditions at Mt. Halla have occurred in 1964, 1965 and 1966. The correlations between the fir chronology SOI(Southern Oscillation Index) of previous January, February and November were significantly positive. The growth ratio of A. koreana demonstrates that this species is sensitive to seasonal variations. As the winter temperature rises, the growth ratio of A. koreana decreases, on the other hand, the increase of autumn temperature accelerates the growth ratio of A. koreana. The growth decline of A. koreana was observed from 51 cores out of the 54 cores, and the overall growth declines have initiated at 1978, 1982 and 1988. Distinct growth decline of A. koreana in the range of 70% is noticed at 34 cores out of the 51 cores. The decline of, A. koreana growth appears to be related to the winter temperature which has increased since mid-1970s.

• Journal of the Korean Society of Marine Environment & Safety
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• v.15 no.4
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• pp.275-282
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• 2009

PAHs(Polycyclic Aromatic Hydrocarbons) compounds may enter into the marine environment in a number of ways, and PAHs in coastal area and estuary adjacent to urban area and industrial activities region are mainly introduced into marine environment via atmosphere or river. The field surveys to evaluate the pollution of PAHs in rivers of Jinhae bay were carried out in August, 2008. The water samples collected from seven main rivers and Deokdong WWTP(Waste water Treatment Plant) which lead to Jinhae bay. 16 PAHs which had been selected as priority pollutants by EPA were analyzed. The range and mean of dissolved Total PAHs concentrations in the rivers and Duckdong WWTP that lead to Jinhae bay were shown to be 9.79~128.25(mean 36.94)ng/L, while the range and mean of Total PAHs concentrations in SPM(Suspended Particulate Matter) were shown to be 1,81434~8,893.37(mean 4,657.73)${\mu}g$/kg dry wt. The dissolved Total PAHs and Total PAHs in SPM were shown to be high concentrations in the Semhocheon which leads to Masan bay that is the most polluted area of Jinhae bay, while those were shown to be low concentrations at rivers which lead to the west area of the bay. The ranges and means of the loading fluxes from rivers and Duckdong WWTP were calculated at 0.06~12.05(mean 1.86)g/day for dissolved Total PAHs and at 0.12~16.00(mean 2.41)g/day tor Total PAH in SPM. The loading flux of Total PAHs from Duckdong WWTP was shown to be the greatest, occupying more than 80% of Total loading flux from all rivers and WWTP to Jinhae bay. The composition patterns of PAHs compound by the number of benzene ring between dissolved PAHs and PAHs of SPM were different each other. Low molecuar weight PAHs of dissoloved compounds were in high concentration, while high molecular weight PAHs of SPM were in high concentration. These results were due to physical and chemical characteristics of PAHs and were similar to those of other studies. The total PAHs concentrations of dissolved and SPM in this study are lower than those of other studies. The extent of PAHs pollution appeared to be not serious in reverine waters of Jinhae bay.

• Korean Journal Plant Pathology
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• v.2 no.2
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• pp.107-113
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• 1986

Each of 48 monoconidial isolates of Colletotrichum gloeosporioides Penz. obtained from diseased fruits of pepper was classified into strain G or strain R based upon pathogenicity to green and red fruits, morphology of conidia, and cultural characteristics in potato dextrose agar. The strain G was designated for isolates to cause anthracnose symptoms both on green and red fruits. All isolates of the strain G produced conidia abundantly. but produced no perithecia and setae in PDA. Conidia of all isolates in the strain G were attenuated or round at one end. The optimum temperature for mycelial growth of strain G was $26-28^{\circ}C$. The mycelia of strain G in PDA appeared to be whitish when young, and turned to be dark in old culture. Symptoms on pepper fruits caused by the strain G were somewhat sunken to be circular to elliptical lesions. Yellowish conidial masse were observed at the center of lesions, and the lesions turned to irregular shape and to reddish brown color in the later stage of disease development. No setae were visible on the acervuli. The strain R was designated for isolates to cause anthracnose symptoms only on red fruits of pepper. All isolates of the strain R produce conidia, and perithecia of Glomerella cingulata (Stonem.) Spauld. & v. Sch. in PDA. Some isolates of the strain R produced setae in culture under fluorescent light. Conidia of all isolates in the strain R were round and blunt at the ends. The optimum temperature for mycelial growth of strain R was the same as that of strain G. The mycelial growth of strain R was faster than that of strain G in PDA. The mycelia of strain R in PDA appeared to be gray to dark. Symptoms on pepper fruits caused by the strain R were circular to irregular black ring-spots Short setae or no setae were visible on the acervuli.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.11
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• pp.1935-1944
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• 2000

This research was performed to investigate the effects of the location of recirculation port on the wastewater treatment efficiency of an anaerobic hybrid reactor consisted of a fluidized bed and a packed bed. The recirculation port was located either at the top of the packed bed (Reactor 2) or above the fluidized bed (Reactor 1). Media for the fluidized bed and the packed bed were granular activated carbon and Pall ring-type plastic media. respectively. At organic loading rates(OLR) up to $6.2kg\;COD/m^3-day$. Reactor 2 showed somewhat better performance than Reactor 1 with COD removal efficiencies of 85.0-95.2%. The COD removal efficiencies of the reactors drastically deteriorated at OLRs above $6.2kg\;COD/m^3-day$, and the tendency was more severe for Reactor 1 than for Reactor 2. Eventhough the two reactors showed similar effluent SS concentrations at OLRs below $3.6kg\;COD/m^3-day$, Reactor 2 showed higher effluent SS concentrations than Reactor 1 at OLRs above $5.3kg\;COD/m^3-day$. Reactor 2 was stabler than Reactor 1 with a methane production rate of $5.5kg\;COD/m^3$-day at the OLR of $13.3kg\;COD/m^3-day$. An abrupt increase in effluent volatile acid concentration was observed at the OLR of $6.2kg\;COD/m^3-day$ for Reactor 1 and $7.1kg\;COD/m^3-day$ for Reactor 2. and the increase was greater in Reactor 1. In conclusion. the range of OLR for adequate treatment in the hybrid reactor was determined according to the location of the internal recirculation port. It is more desirable for higher OLRs to locate the recirculation port at the top of the packed bed in order to utilize the whole volume of the reactor.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.2
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• pp.60-74
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• 2017

To facilitate prevention of highly pathogenic avian influenza (HPAI), a GIS is widely used for monitoring, investigating epidemics, managing HPAI-infected farms, and eradicating the disease. After the outbreak of foot-and-mouth disease in 2010 and 2011, the government of the Republic of Korea (ROK) established the GIS-based Korean Animal Health Integrated System (KAHIS) to avert livestock epidemics, including HPAI. However, the KAHIS is not sufficient for controlling HPAI outbreaks due to lack of responsibility in fieldwork, such as sterilization of HPAI-infected poultry farms and regions, control of infected animal movement, and implementation of an eradication strategy. An outbreak prediction model to support efficient HPAI control in the ROK is proposed here, constructed via analysis of HPAI outbreak patterns in the ROK. The results show that 82% of HPAI outbreaks occurred in Jeolla and Chungcheong Provinces. The density of poultry farms in these regions were $2.2{\pm}1.1/km^2$ and $4.2{\pm}5.6/km^2$, respectively. In addition, reared animal numbers ranged between 6,537 and 24,250 individuals in poultry farms located in HPAI outbreak regions. Following identification of poultry farms in HPAI outbreak regions, an HPAI outbreak prediction model was designed using factors such as the habitat range for migratory birds(HMB), freshwater system characteristics, and local road networks. Using these factors, poultry farms which reared 6,500-25,000 individuals were filtered and compared with number of farms actually affected by HPAI outbreaks in the ROK. The HPAI prediction model shows that 90.0% of the number of poultry farms and 54.8% of the locations of poultry farms overlapped between an actual HPAI outbreak poultry farms reported in 2014 and poultry farms estimated by HPAI outbreak prediction model in the present study. These results clearly show that the HPAI outbreak prediction model is applicable for estimating HPAI outbreak regions in ROK.

• Journal of Korean Ophthalmic Optics Society
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• v.21 no.3
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• pp.227-233
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• 2016

Purpose: On this study, we compared the relationship of dynamic stereoacuity according to the dominant eye, degree of dominant eye, and dominant agreement eye and hand. Methods: For 130 adults (male 70, female 60), mean age of $21.06{\pm}2.21years$ old, dominant eye, degree of dominant eye were measured by objective examination by using the diameter $3.8cm{\times}3.8cm$ thin ring, the dynamic stereoacuity were measured by three-rods test (iNT, Korea). Results: Dynamic stereoacuity according to the dominant eye was center dominant eye without dominance was $14.97{\pm}13.80sec$ of arc, right eye $22.10{\pm}20.01sec$ of arc, left eye $22.31{\pm}20.39sec$ of arc. Dynamic stereoacuity was better when there was no dominance, but the correlation of the dominant eye with dynamic stereoacuity was very low. When Dynamic stereoacuity was separated by in the Center, Mild, Strong, dynamic stereoacuity was $14.97{\pm}13.80sec$ of arc, $20.76{\pm}15.73sec$ of arc and $24.45{\pm}25.60sec$ of arc respectively. The dynamic stereoacuity results were worse when dominance was stonger. However dynamic stereoacuity was better than Center when the degree of dominant eye was rather strong in the dominant left eye. Dynamic stereoacuity according to the dominant eye and hand showed that right eye and hand was $22.63{\pm}20.54sec$ of arc, left eye and hand was $17.36{\pm}10.13sec$ of arc, right eye and left hand was $14.79{\pm}7.05sec$ of arc, left eye and right hand was $22.97{\pm}21.42sec$ of arc so dynamic stereoacuity was comparatively good when the dominant hand was left. Conculsions: Correlation between the dynamic stereoacuity according to the dominant eye, degree of dominant eye was low, however when degree of dominant eye was Center 14.97 sec of arc, Strong 24.45 sec of arc, the dynamic stereoacuity tended to worse when degree of dominant eye was strong. As a result, dominant eye, degree of dominant eye would have to be considered in a more comfortable binocular balance between prescribed for the wearer in binocular vision correction in binocular function such stereoacuity, sports vision training, presbyopia correction and mono vision.

• Journal of Korean Society of Forest Science
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• v.89 no.1
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• pp.77-84
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• 2000

In order to understand the chemical binding forms of Cd in terms of its binding strength in wood, the radial distribution of it through dendroanalysis and its different chemical fractions in trunk wood of mature red pine(Pinus densiflora L.) trees grown in a relatively unpolluted area, in Kangwon-Province, were examined. Total Cd concentration in stem wood was determined by dry digestion and $H_2O$ and 0.01 M solutions of citric acid, malic acid, $CaCl_2$, $MgCl_2$, $Na_2EDTA$ were used as extracting solutions for Cd. Extracting efficiencies of applied solutions were expressed as % of Cd concentration extracted by $Na_2EDTA$ which extracted all Cd instead of Cd total concentration. Total concentration of Cd decreased from the innermost rings near pith towards the the outermost rings near cambium. Especially through the transition zone this tendency was observed clearly. $H_2O$ was the least effective extractant of Cd, then extracting efficiency increased in the order $MgCl_2$ < $CaCl_2$ $Na_2EDTA$ (extracted all Cd). According to the radial position, extracting efficiency of Cd was ranging from 7 to 30% by $H_2O$ and even from 60 to 95% by citric acid. The Cd extracting efficiencies of $H_2O$ and organic acids increased continuously from the stem center to outermost annual rings, whereas salts showed somewhat different tendency, suddenly decreasing near the outermost ring. The results are discussed with regard to the different chemical binding forms of Cd and the mobility of Cd in wood and comparable with ones in previous studies on Pinus sylvestris and Quercus patraea. According to the results, usefulness of radial distribution pattern of Cd in pine tree trunks for retrosective biomonitoring is questioned.