• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.4
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• pp.347-357
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• 2003

This paper describes on the suppression of sea clutter on marine radar display using a cell-averaging CFAR(constant false alarm rate) technique, and on the analysis of radar echo signal data in relation to the estimation of ARPA functions and the detection of the shadow effect in clutter returns. The echo signal was measured using a X -band radar, that is located on the Pukyong National University, with a horizontal beamwidth of $$3.9^{\circ}$$, a vertical beamwidth of $20^{\circ}$, pulsewidth of $0.8 {\mu}s$ and a transmitted peak power of 4 ㎾ The suppression performance of sea clutter was investigated for the probability of false alarm between $l0-^0.25;and; 10^-1.0$. Also the performance of cell averaging CFAR was compared with that of ideal fixed threshold. The motion vectors and trajectory of ships was extracted and the shadow effect in clutter returns was analyzed. The results obtained are summarized as follows；1. The ARPA plotting results and motion vectors for acquired targets extracted by analyzing the echo signal data were displayed on the PC based radar system and the continuous trajectory of ships was tracked in real time. 2. To suppress the sea clutter under noisy environment, a cell averaging CFAR processor having total CFAR window of 47 samples(20+20 reference cells, 3+3 guard cells and the cell under test) was designed. On a particular data set acquired at Suyong Man, Busan, Korea, when the probability of false alarm applied to the designed cell averaging CFAR processor was 10$^{-0}$.75/ the suppression performance of radar clutter was significantly improved. The results obtained suggest that the designed cell averaging CFAR processor was very effective in uniform clutter environments. 3. It is concluded that the cell averaging CF AR may be able to give a considerable improvement in suppression performance of uniform sea clutter compared to the ideal fixed threshold. 4. The effective height of target, that was estimated by analyzing the shadow effect in clutter returns for a number of range bins behind the target as seen from the radar antenna, was approximately 1.2 m and the information for this height can be used to extract the shape parameter of tracked target..

• Korean Journal of Ecology and Environment
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• v.39 no.2 s.116
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• pp.271-283
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• 2006

A systematic water quality survey was conducted in August, 2005 for a drinking water supply reservoir (the Jeolgol reseuoir located in an island), which is at an early stage of impoundment, to investigate the causes of water color deterioration of the reservoir and the clogging of filter beds of a water treatment plant. The reservoir shape was simple and its average depth was 5.5 m, increasing from upreservoir toward the downreservoir end near the dam. Dissolved oxygen (DO) and chloropllyll-a (chi-a) showed a large variation while water temperature had a smaller range. Transparency ranged from 0.6 to 0.9 m (average 0.7 m). The average value of turbidity was 9.3 NTU, ranging from 8.0 ${\sim}$ 12.1 NTU. The transparency and the turbidity appear to be affected by a combination of biological and non-biological factors. The poor transparency was explained by an increase of inorganic colloids and algal bloom in the reservoir. The blockage of the filter bed was attributed to the oversupply of phytoplanktons from the reservoir. The range and the average concentration of chi-a within the reservoir were 31.6 ${\sim}$ 258.9 ${\mu}g\;L^{-1}$, 123.6 ${\mu}g\;L^{-1}$ for the upper layer, and 17.0 ${\sim}$ 37.4 ${\mu}g\;L^{-1}$, 26.5 ${\mu}g\;L^{-1}$ for the bottom layer, respectively. A predominant species contributing the algal bloom was Dinophyceae, Peridinium bipes f. occultatum. The distribution of Peridinium spp. was correlated with chi-a concentrations. The standing crop of phytoplankton was highest in the upreservoir with $8.5\;{\times}\;103\;cells\;mL^{-1}$ and it decreased toward the downresevoir. Synedra of Bacillariophyceae and Microcystis aeruginosa of Cyanophyceae appeared to contribute to the algal bloom, although they are not dominated. It is mostly likely that sloped farmlands located in the watershed of the reservoir caused water quality problems because they may contain a significant amount of the nutrients originated from fertilizers. In addition, the aerators installed in the reservoir and a shortage of the inflowing water may be related to the poor water quality. A long-term monitoring and an integrated management plan for the water quality of the watersheds and the reservoir may be required to improve the water quality of the reservoir.

• Journal of Life Science
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• v.16 no.6
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• pp.1060-1065
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• 2006

Non-invasive evaluation of liver function in animal models remains a challenge. Hepatoscintigraphy provides information about changes in liver size and shape, and enables to understand general liver function. Futhermore it is readily used to diagnosis complications of liver transplantation like hepatitis, rejections and biliary complications. In this study, we investigated the usefulness of evaluating the liver function in miniature pigs with $^{99m}Tc-Tin$ colloid and $^{99m}Tc-DISIDA$ which are the most commonly used radiopharmaceuticals in human medicine. In result, $^{99m}Tc-Tin$ colloid was uptaked in lung, liver, gastric wall and kidney in miniature pigs. And $^{99m}Tc-DISIDA$ showed continuous uptake images of heart, lung, liver, gallbladder and duodenum, and it was similar to human's. Therefore we could conclude $^{99m}Tc-Tin$ colloid would not be suitable for evaluating hepatic function because of it's nonspecific affinity, however $^{99m}Tc-DISIDA$ scintigraphy would be an effective method for detecting hepatobiliary function in miniature pigs.

• Journal of the Korean Geographical Society
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• v.31 no.4
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• pp.685-698
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• 1996

Southern Louisiana has one of the largest Vitnamese refrgee neighborhoods after the mid-1970s. It is impressive that one of their adaptive strategies comes from their religious lives which are centered on either Catholicism or Buddhism. The Buddhism community, especially, exhibits an exotic symbolic system of value and attitude, and thus contributes to cultural diversity in the adopted country. The landscape of the Buddhist temple is a visible symbol to them that the host socirty accepts their maintenance of their own cultural identity and that they are also an integral part of American society. Their making-place and being-in-place procedures, although their culture is being transformed in the original shape, put an emphasis on interaction with the host xociety. These procedures have been facilitated by consolidating their identity as a minority group as well as by interacting with the host society. The on-going influx of foreign immigrant groups seems not to drive them to assimilate into the melting-pot society, but to contribute to contribute to the increase in the cultural diversity of the United States.

• The Journal of Korean Academy of Prosthodontics
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• v.23 no.1
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• pp.39-59
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• 1985

The purpose of this study was to investigate how gap distances of 0.13mm, 0.15mm, 0.20mm, and 0.30mm affects solder joint strength from gold alloys and nickel-chromium base alloys and to examine the composition of solder gold, the solder joint of gold alloys and nickel-chromium base alloys. The tensile test specimens were prepared in the split stainless steel mold with a half dumbbell shape 2.5mm in diameter and l2mm in length. 6 pairs of specimens of each gap distance group of gold alloys and nickel-chromium base alloys were made and 48 pairs of all specimens were soldered with solder gold of 666 fineness. All soldered specimens were machined to a uniform diameter and then a tensile load was applied at a cross-head speed of 0.10mm/min using Instron Universal Testing Machine, Model 1115. The fractured specimens at solder gold of solder joint fracture with each gap distance of 0.13mm, 0.15mm, 0.20mm, and 0.30mm were examined under the Scanning Electron Microscope, JSM-35c and the composition of solder gold, the solder joint of gold alloys and nickel-chromium base alloys was analyzed by Electron Probe Micro Analyzer. The results of this study were obtained as follows: 1. In case of soldering of gold alloys, the tensile strength between gold alloys showed $37.33{\pm}2.52kg/mm^2$ at 0.13, $39.14{\pm}3.35kg/mm^2$ at 0.15mm, $43.76{\pm}2.97kg/mm^2$ at 0.20mm, and $49.18{\pm}4.60kg/mm^2$ at 0.30mm. There was statistically significant difference at each gap distance, and so the greater increase of gap distance showed the greater tensile strength. 2. In case of soldering of nickel-chromium base alloys, the tensile strength between nickel-chromium base alloys showed $34.84{\pm}4.26kg/mm^2$ at 0.13mm, $37.25{\pm}2.49kg/mm^2$ at 0.15mm, $42.91{\pm}4.32kg/mm^2$ at 0.20mm, and $46.93{\pm}4.21kg/mm^2$ at 0.30mm. There was not statistically significant difference only between 0.13mm and 0.15mm and bet ween 0.20 mm and 0.30mm, but generally the greater increase of gap distance showed the greater tensile strength. 3. The greater increase of gap distance shoed less porosities in solder gold at solder joint fracture. 4. In solder gold Au, Cu, Ag, Zn, and Sn were composed and Au and Cu were mostly distributed uniformly. 5. In solder joints of solder gold and gold alloys Au, Cu, Ag, Zn, and Sn were composed in solder gold and Au, Cu, Ag, Pt, and Pd were composed in gold alloys. Au and Cu of solder gold and gold alloys were mostly distributed uniformly and the diffusion of other elements except Pt and Pd around the solder joint was not almost found. In solder joints of solder gold and nickel-chromium base alloys Au, Cu, Ag, Zn, and Sn were composed in solder gold and Ni, Cr, and Al were composed in nickel-chromium base alloys. Au and Cu of solder gold and Ni and Cr of nickel-chromium base alloys were mostly distributed uniformly and the diffusion of other elements except Cr around the solder joint was not almost found.

• The Journal of Korean Academy of Prosthodontics
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• v.50 no.2
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• pp.112-118
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• 2012

Purpose: The purpose of this study was to evaluate the difference in shear bonding strength between resin cements to dental materials when a universal primer (Monobond plus) was applied in place of a conventional primer. Materials and methods: Four groups of testing materials: gold alloy (Argedent Euro, n = 16), non precious metal (T-4, n = 20), zirconia (Cercon, n = 20) and glass ceramic (IPS e.max press, n = 20), were fabricated into discs, which were embedded in an acrylic resin matrix. The gold alloy specimens were airborne-particle abraded, 8 of the specimens were coated with Metal primer II, while the remaining 8 specimens were coated with Monobond plus. The non precious and zirconia specimen were airborne-particle abraded then, the control group received Alloy primer coating, while the other was coated with Monobond plus. Glass ceramic specimens were etched. 10 specimens were coated with Monobond-S and the remaining specimens were coated using Monobond plus. On top of the surface, Multilink N was polymerized in a disc shape. All of the specimens were thermal cycled before the shear bonding strength was measured. Statistical analysis was done with Two sample $t$-test or Mann-Whitney U test (${\alpha}$=.05). Results: There were no significant differences in bonding strength depending on the type of primer used in the gold alloy and glass ceramic groups ($P$>.05), however, the bonding strengths of resin cements to non precious metal and zirconia groups, were significantly higher when the alloy primer was used ($P$<.05). Conclusion: Within the limitations of this study, improvement of universal primers which can be applied to all types of restorations is recommended to precious metals and zirconia ceramics. But, the bond strengths of non precious metals and zirconia ceramics were significantly lower when compared to a 10-MDP primer. More research is needed to apply universal primers to all types of restorations.

• Korean Journal of Occupational Health Nursing
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• v.4
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• pp.5-29
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• 1995

Occupational health services in Korea have been operated as dual types : one is operated by occupational health care manager and the other is health care agency without their own personnel. The performance of occupational health service should be different due to the variety of characteristics of health care manager and workplace, qualification of health care manager. This study is to analyze performance of occupational health care services with a particular consideration of job performance shape and efficiency, based on comparing those two types of health care management to show on the basic data for the settlement of more qualitative health care management system at workplace. For this study, total 391 places in Seoul and Inchon city area ; 154 places (39.4%) managed by designated health care manager and 237 places (60.6%) by the agency with their commission are selected as research samples. Tools for data collection are questionnares that have been investigated during the period of 20 September 1993-20 December 1993. Those data are compared with percentiles, mean, standard deviation and B/C ratio using SPSS PC program. Conclusions observed from the tests and each comparison could be summerized as follows : 1. Occupational health care have been accomplished at workplaces with designated people than with agencies people, and coverage rate of the occupational health care services has differences, due to management types. The reason of these results is due to visit only one or two times monthly by the agencies, while their own health care manager obsess, at the workplaces all the times. 2. Most of the expense for environmental control of all health care services expenditures shows that there is almost no fundamental improvement because more expenses are needed for procuring personal protective equipment and measuring work environment instead of environmental improvement. 3. It is investigated how much the cost of occupational health care services needs per worker, and calculated how much the cost needs per service hour per worker. The results from this show that the cost of occupational health services at workplaces with their own managers used less than the cost of health care agencies, eventually the former gives better services with less cost than the latter. 4. Benefit/Cost ratio is also produced by total benefit/total cost. The result from the above way reads 4.57 as a whole, while their own manager having workplaces reads 4.82 and the agencies do l.56. Even if their own manager performing workplaces spent more cost, this system produces more benefit than the agencies management. 5. The B/C ratio for medical organization such as local clinic, health care center and pharmacy shows more than or equal to at the workplaces controlled by the agencies. It is inferred that benefit would be much less than the cost used, with so being inefficient. 6. It is assumed that the efficiency ratio of health education is equal to reduction rate of workers medical organization visit. Estimated reduction rate 5%, 10%, 15%, show that the efficiency ratio of health education have an effect on producing benefits. It is estimated that more benefit can be produced if more qualitative education will be provided for enhancing health care efficiency. 7. Results of this study cannot be generalized because there are large scale of deviation in case of workplaces with less than 300 full time workers, but B/C ratio reads 2.69 as a whole and 3.25 at workplaces with their own health care manager are higher than 1.63 at the workplaces manged by the agencies. Finally, all the benefit concerning health care services could not be quantified, measured and shown on the value of money. This is a reason that a considerable part of benefits are so underestimated. This is also thought that measurement tools should be developed for measuring benefits of health care services with a comprehensive quantification. in the future. It is also expected that efficiency of occupational health care services should be investigated using cost-effectiveness analysis.

• Journal of the Korean Magnetics Society
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• v.27 no.4
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• pp.123-128
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• 2017

The magnetic isotropy property from the magnetoresistance (MR) curve and magnetization (MH) loop for the PtMn based spin valve (SV) multilayer films fabricated with different the bottom structure after post-annealing treatment was investigated. The exchange biased coupling field ($H_{ex}$), coercivity ($H_c$), and MR ratio of Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/Ta(4 nm) SV multilayer film without antiferromagnetic PtMn layer are 0 Oe, 25 Oe, and 3.3 %, respectively. MR curve for the Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/PtMn(6 nm)/Ta(4 nm) SV multilayer film showed $H_{ex}=2Oe$, $H_c=316Oe$, and MR (%) = 4.4 % with one butterfly MR curve having by the effect of antiferromagnetic PtMn layer. MR curve for the dualtype Glass/Ta(10 nm)/CoFe(6 nm)/Cu(2.5 nm)/CoFe(3 nm)/PtMn(6 nm)/CoFe(3 nm)/Cu(2.5 nm)/CoFe(6 nm)/Ta(4 nm) SV multilayer film showed $H_c=37.5Oe$ and 386 Oe, MR = 3.5 % and 6.5 % with two butterfly MR curves and square-like hysteresis MH loops. The anisotropy property in CoFe spin valve-PtMn multilayer is neglected by the effects of a very small value of $H_{ex}$ and a very slightly shape magnetic anisotropy. This result is possible to explain the effect of magnetization configuration spin array of the bottom SV film and the top SV film of PtMn layer.

• 한국균학회소식:학술대회논문집
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• 2015.11a
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• pp.16-16
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• 2015

Ectomycorrhizal (ECM) mushrooms play a major role in plant growth promotion through symbiotic association with roots of forest trees. They also provide an economically important food resource to us and therefore they have been studied for their artificial cultivation for decades in Korea. We have secured bio-resources of ECM mushrooms from Korean forests and performed their physiological studies. To investigate the cultural characteristics, the fungi were cultured under different conditions (medium, temperature, pH of the medium, inorganic nitrogen source). More than 90% of total 160 strains grew on three solid media (potato dextrose agar, PDA; sabouraud dextrose agar, SDA; modified Melin-Norkrans medium, MMN). The rate of mycelial growth on malt extract agar (MEA) was lower than those of three media (PDA, SDA, MMN). None of the Tricholomataceae strains grew on MEA. Many strains of ECM mushrooms were able to grow at the temperature range of $15{\sim}25^{\circ}C$ on PDA, while they showed poor growth at $10^{\circ}C$ or $30^{\circ}C$. In particular, the growth rates of both Gomphaceae and Tricholomataceae were significantly lower at $10^{\circ}C$ than at $30^{\circ}C$. The optimal pH of many strains was pH 5.0 when they cultured in potato dextrose broth (PDB). Fifty-seven percent of tested strains grew well on medium containing ammonium source than nitrate source. Many strains of Tricholomataceae showed a notable growth on ammonium medium than nitrate medium. Twenty-three percent of strains preferred nitrate source than ammonium source for their mycelial growth. The production and activity of two enzymes (cellulase and laccase) by ECM fungi were also assayed on the enzyme screening media containing CMC or ABTS. Each strains exhibited different levels of enzymatic activities as well as enzyme production. The number of laccase-producing strains was less than that of cellulase-producing strains. We found that 77% of tested strains produced both cellulase and laccase, whereas 2% of strains did not produce any enzymes. The morphological characteristics of mycelial colony were also examined on four different solid media. Yellow was a dominant color in mycelial colony and followed by white and brown on all culture media. ECM mushrooms formed mycelial colonies with a single or multiple colors within a culture medium depending on the strains and culture media. The most common shape of mycelial colony was a circular form on all media tested. Other families except for Amanitaceae formed an irregular colony on MMN than PDA. All strains of Tricholomataceae did not form a filamentous colony on all media. The pigmentation of culture media by mycelial colonies was observed in more than 50% of strains tested on both PDA and SDA. The degree of pigmentation on PDA or SDA was higher than MMN and brown color was dominant than yellow color. The production of exudates from mycelial colony was higher on PDA than MMN. Brown exudates were mainly produced by many strains on PDA or SDA, whereas transparent exudates were mainly produced by strains on MMN. We observed the mycelial colonies with a single or multiple textures in just one culture plate. Wrinkled or uneven colony surfaces were remarkably observed in many strains on PDA or SDA, while an even colony surface was observed in many strains on MMN. Sixty percent of Tricholomaceae strains formed wrinkled surface on PDA. However, they did not form any wrinkle on MMN plate. Cottony texture was observed in mycelia colonies of many strains. Velvety texture was often observed in the mycelial colonies on SDA than PDA and accounted for 60% of Suillaceae strains on SDA.

• Journal of dental hygiene science
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• v.8 no.4
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• pp.233-239
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• 2008

The purpose of this study was to survey the knowledge and awareness of dental hygienists and dental hygiene students about hepatitis B in an attempt to lay the solid foundation for the prevention of hepatitis B and infection control, as dental hygienists were highly likely to be exposed to HBV during job performance. The findings of the study were as follows: 1. 32.5% of the dental hygienists and 15.6% of the dental hygiene students were aware of their own HBsAg and HBsAb states. The dental hygienists who were cognizant of the states statistically significantly outnumbered the dental hygiene students who were (p=.000). 2. As for vaccination against hepatitis B, 71.8% of the dental hygienists and 47.3 % of the dental hygiene students were inoculated against it. The dental hygienists who were vaccinated against it outnumbered the dental hygiene students who were, and the disparity between the two was statistically significant (p=.000). 3. In the event of those who were vaccinated against hepatitis B, the dental hygienists were better cognizant than the dental hygiene students of the right time for the vaccination, required vaccination frequency (three times) and confirmation of the formation of hepatitis B antibody (p=.000). 4. Regarding awareness of hepatitis B infection route, the dental hygienists knew significantly better than the dental hygiene students that hepatitis B might be infected via blood (p=.030), sexual relations (p=.000), contaminated needle sticks (p=.000), mothers with hepatitis B positive during delivery (p=.000), toothbrushes/razors (p=.000) and exchange of drinking cups (p=.000). 5. As to the relationship between health status and knowledge on hepatitis B infection route, the respondents who were in bad shape had the best knowledge about that, followed by those in an average state of health and healthy respondents. And the dental hygienists had a significantly better knowledge than the dental hygiene students (p=.001). 6. Just a small number of the dental hygienists and students knew about the hepatitis B-related past experiences of their families, and the gap between the two was insignificant.