• Journal of the korean academy of Pediatric Dentistry
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• v.23 no.3
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• pp.746-763
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• 1996

An alternative design to conventional class II cavity preparation for proximal carious lesions is the tunnel preparation. It preserves the marginal ridge intact, thus making it possible to maintain the natural contact relationship with the adjacent tooth and minimize tooth reduction. This in vitro study was purposed to evaluate the effect of the materials' elastic constants and shear-bond strength on the marginal ridge fracture resistance of teeth restored by the tunnel technique, and to find the materials of choice for tunnel restorations. $Resinomer^{(R)}$, $Ketac-silver^{(R)}$, $Miracle-Mix^{(R)}$, and Tytin were used as restorative material. The elastic constants of each restorative material were evaluated by ultrasonic pulse measurement. Young's modulus and bulk modulus of the restorative materials were evaluated in three specimens for each material type. The shear-bond strength of the restorative materials to the dentin surface was measured after thermocycling 400 times between 6 and $60^{\circ}C$, using ten specimens for each material type. For measuring marginal ridge strength, 60 sound extracted molar teeth were distributed into six groups by size. Sound molar teeth were used as a Control group and unfilled prepared teeth were grouped as Unrestored. Another four groups were named Resinomer group, Ketac-Silver group, Miracle Mix group, and Tytin group by type of restorative material. Tunnel cavity preparation was done with ' 1/2, 2, and 4 round burs in sequence. Initial access to proximal surface was made through an occlusal access preparation started at least 2mm from the marginal ridge, and the proximal opening was formed about 2.5mm below the marginal ridge. After restoration and thermocycling, marginal ridge strength was measured using a universal testing machine. The results were as follows: 1. The Young's modulus of $Tytin^{(R)}$ was 63.95 GPa, followed by $Ketac-Silver^{(R)}$ 27.60 GPa, $Miracle-mix^{(R)}$ 18.48 GPa, and $Resinomer^{(R)}$ 10.74 GPa showing significant differences between the groups(P<0.05). The bulk modulus of the materials showed the same order as Young's modulus. The value of $Tytin^{(R)}$ showed 59.57 GPa indicating that it will deform less than other materials under the same stress. It was followed by $Ketac-Silver^{(R)}$ 23.57 GPa, Miracle $Mix^{(R)}$ 12.50 GPa, and $Resinomer^{(R)}$ 11.60 GPa. 2. The Resinomer group had a shear-bond strength of 7.41 MPa which was significantly higher than those of the Ketac-Silver group (1.80 MPa) and the Miracle Mix group (2.84 MPa) (P<0.01). All the specimens of Tytin group detatched from the dentin surface during thermocycling. 3. The mean marginal ridge strength of the Unrestored group(46.14 kgf) was significantly lower than that of the Control group (84.24 kgf) (P<0.01). The marginal ridge strength of teeth restored by the tunnel technique was, in order, Ketac-Silver group 74.06 kgf, Miracle Mix group 73.36 kgf, Resinomer group 63.47 kgf, and Tytin group 58.76 kgf. The Ketac-Silver, Miracle Mix, and Resinomer groups showed no significant difference with the Control group (P>0.05), but the Tytin group showed significantly lower strength compared to the Control group(P<0.05). The results showed that the marginal ridge strength of the teeth restored by the tunnel technique was not significantly lower than that of sound teeth. They also demonstrated that the bonding strength of the restorative material to the tooth surface should be high and the modulus of elasticity should not be lower than that of the tooth in order to restore the marginal ridge strength to its natural condition.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.3 no.2
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• pp.129-136
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• 1970

As an attempt to determine if the morphological differences between the southern and western oysters are due simply to the local ecological factors or are based on their fundamental genetic nature, oyster seeds produced in 1968 at Tong-Young, Ye-Chun, and Ko-Hung on the south coast and at Kan-Wol-Do on the west coast were cross-transplanted during May of 1969 to compare their growth. The spats were placed in plastic baskets which permitted free water flow through and the baskets hung from a wooden rack located at a tidal zone of less than I hour exposure at a depth chosen to keep the baskets submerged in water at all times. Twice a month the growth of the spats were measured along with the air and water temperature and salinity. The early summer spats, which were $17-240\%$ larger, in size, than the late summer spats at the time of cross-transplantation, grew more slowly than the late summer spats when exposed to identical environmental conditions, shortening the initial gap to a $5-20\%$ level as the first year of the growth phase came to an end in December. The growth of the Kan-Wol-Do spats lagged considerably behind the southern spats at all localities tested, whereas there were no significant differences among the latter groups. This suggests that the morphological differences between southern and western Pacific oysters in Korea are a manifestation of genetic variety and that Pacific oysters cultured along the south coast are of an identical variety as they are commonly believed to be. The seasonal changes in temperature and salinity even during rainy season in both the southern and western coastal areas are well within the range suitable for successful spawning, and spat fall. However, since the results were based on twice-a-month measurements with no data covering the critical period before and after spawning, they can only serve to indicate at best the general pattern of changes in the environmental conditions of each growing area.

• Clinical and Experimental Pediatrics
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• v.53 no.2
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• pp.173-177
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• 2010

Purpose : Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen that causes nosocomial infection in NICU. It contributes to neonatal morbidity and mortality with variable complications. This study was conducted to identify the risk factors associated with complicated MRSA bacteremia in neonates. Methods : We reviewed the medical records of 44 neonates with positive blood culture for MRSA who were admitted to the NICU of Pusan National University Hospital from January 2002 to December 2007. We compared various factors of the complicated and uncomplicated MRSA bacteremia cases. Results : Of the 44 neonates, 31 were male and 13, female. The mean gestational age and birth weight were $33.2{\pm}4.9$ weeks and $1,859.9{\pm}962.2g$, respectively. Twenty-one of infants were treated with a mechanical ventilator during a mean of $8.8{\pm}13.8$ days. There were 13 cases of complicated and 31 cases of uncomplicated MRSA bacteremia. Between the 2 groups, we compared the following variables: gestational age, birth weight, ventilator use, umbilical catheter use and central catheter insertion, $O_2$ inhalation, first oral feeding day after birth, underlying disease, transfusion, and initial vancomycin use. The underlying disease and transfusion were the risk factors related to complicated MRSA bacteremia. Conclusion : Complicated MRSA bacteremia is related to underlying disease and transfusion. Since this was a retrospective study with a small sample size, it offered limited capacity to compare complicated and uncomplicated MRSA bacteremia. A prospective study with a larger population is needed to determine the exact characteristics of MRSA bacteremia in NICU.

• The korean journal of orthodontics
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• v.33 no.4 s.99
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• pp.307-317
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• 2003

Conventional osseointegrated titanium implants have many limitations; large size, limited location for placement of the implant, severity of the surgery, discomfort of initial healing, difficulty of oral hygiene and uncontrollable force direction. Recently titanium miniscrew and miniplate have been used for an alternative to conventional dental implant. But in relation to miniplate, miniscrew has disadvantages in that more potential inflammation, light orthodontic force application and limited orthodontic application. This study was conducted to evaluate the effectiveness of miniplate by observing the reactions of peri-implant tissues to early orthodontic and orthopedic loading of titanium miniplate. In four adult beagle dogs 10 miniplates were inserted into the alveolar bone using 20 osseointegrated titanium screws. 4 miniplates were placed in two dogs(dogA, B) and 6 miniplates in two dogs(dogC, D). In dogA, B miniplates were loaded with 200gm of force immediately after placement for 15 weeks. In dogc, D, miniplates were loaded with 400gm of force immediately after placement for 8 weeks. Miniplates of dogA were removed, dogA was healed for 4 weeks, and the area which was removed of miniscrew was examined. Following an observation period, the miniplates including miniscrews and the surrounding bone of dogB and dogC, D were removed, respectively. Undecalcified section along the long axis of miniscrews were made and the degree of osseointegration was examined under the light microscope. The results were as follows. 1. In the histologic features there was direct contact between bone and miniscrew in all groups except one, dogC control group. The loaded miniscrew demonstrated only a slight increase of the osseous proximaty when compared with unloaded miniscrew 2. There was no significant difference of the osseointegration of Peri-miniscrew surface between dogB and dogC, D. But dogB showed slightly more increased bone apposition than dogC, D 3. The gingiva overlapping the miniplate and miniscrew showed no inflammatory sign in clinical and histological aspects. 4. The impaled hard and soft tissues at the area which was removed of miniscrews showed good healing without inflammatory reaction. 5. The mobility showed slight increase in un-loaded miniplate but that was insignificant. Based on the results of this study, miniplate(C-tube) can be used as a firm osseous orthodontic and orthopedic anchorage unit immediately after insertion.

• KSBB Journal
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• v.15 no.2
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• pp.125-133
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• 2000

Specific carotenoids and astaxanthin biosynthesis power of Phaffia rhodozyma mutant 876, which was obtained after NTG a and UV treatments, was higher than those of the wild type by 40% and 50%, respectively. The mutant strain did not show t the catabolite repression even at 22% (w/v) glucose concentration. The optimum C{N ratio was 2.0, and the optimum t temperature and initial pH were $22^{\circ}C$ and 6.0, respectively. 80th cell growth and astaxanthin formation decreased drastically a as the fermentation temperature was increased over $22^{\circ}C$, whereas they were comparable in the pH range between 5.0 and 7 7.0. Inoculum size did not affect the final cell density nor the carotenoids biosynthesis, and 3%(v/v) was selected as optimal. H Higher dissolved oxygen concentration facilitated astaxanthin biosynthesis, and aeration rate of 1.0 v/0/m and agitation speed of 400 rpm were selected as optimum. The final cell dens때 of 43.3 g/L and the volumetric astaxanthin and carotenoids concentrations of 110.6 mg/L and 149.4 mg/L, respectively, were obtained. The specific carotenoids concentration was 3.45 m mg{g-yeast(dry). Yx/s and Yp/s values of 0.37 and 1.08 were obtained. The result of this study will provide basic information u useful for mass production of astaxanthin from P. rhodozyma fermentation.

• KSBB Journal
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• v.29 no.4
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• pp.285-296
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• 2014

Although the problems of the algal blooms have been world-widely observed in freshwater, estuary, and marine throughout the year, it is not yet certain what are the basic causes of such blooms. Consequently, it is very difficult to predict when and where algal blooms occur. The constituents of the Asian dust are in a good agreement with the elements required for the algal growth, which suggests some possible relationship between the algal blooms and the Asian dust. There have been frequently algal blooms in drinking water from rivers or lakes. However, there is no any algal blooms in upwelling waters where the Asian dust cannot penetrate into the soil due to its relatively weak settling velocity (size of particles, $4.5{\pm}1.5{\mu}m$), which implies the possible close relationship of the Asian dust with algal blooms. The present initiative study is thus intended firstly in Korea to illustrate such a relationship by reviewing typical previous studies along with 12 years of weekly iron profiles (2001~2012) and two slant culture experiments with the dissolved Asian dust. The result showed bacterial suspected colonies in the slant culture experiment that are qualitatively in a good agreement with the recent Japanese studies. Since the diatoms require cheap energy (8%) compared to other phytoplankton (100%) to synthesize their cell walls by silicate, the present results can be used to predict algal blooms by diatoms if the concentrations of iron and silicate are available during spring and fall. It can be postulated that the algal blooms occur only if the environmental factors such as light, nutrients, calm water surface layer, temperature, and pH are simultaneously satisfied with the requirements of the micronutrients of mineral ions supplied by the Asian dust as enzymatic cofactors for the rapid bio-synthesis of the macromolecules during algal blooms. Simple eco-friendly methods to regulate the algal blooms are suggested for the initial stage of blooming with limited area: 1) to cover up the water surface with black curtain and inhibit photosynthesis during the day time, 2) to blow air (20.9%) or pure oxygen into the bottom of the water and inhibit rubisco for carbon uptake and nitrate reductase for nitrogen uptake activities in algal growth during the night, 3) to eliminate the resting spores or cysts by suction of bottom sediments as deep as 5 cm to prevent the next year germinations.

• Restorative Dentistry and Endodontics
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• v.25 no.4
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• pp.561-574
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• 2000

Poly-P has been used to prevent decomposition of foods and has been shown to have inhibitory effect on the growth of gram positive bacteria. The purpose of this study was to evaluate the effect of poly-P on the growth of Porphyromonas endodontalis, a gram negative obligate anaerobic rod, endodontopathic bacterium. P. endodontalis ATCC 35406 was in BHI broth containing hemin and vitamin K with or without poly-P. Inhibitory effect of each poly-P which was added at the beginning(lag phase) or during(exponential phase) the culture, MIC(minimum inhibitory concentration) was determined by measuring the optical density of the bacterial cell at 540nm. Viable cell counts were measured to determined whether poly-P has a bactericidal effect. Leakage of intracellular nucleotides from P. endodontalis was determined at 260nm and morphological change of P. endodontalis was observed under the TEM(transmission electron microscope). Binding of 32P-labeled poly-P to P. endodontalis was examined. SDS-polyacrylamide gel electrophoresis and zymography were performed to observe the changes in protein and enzyme profiles of P. endodontalis, respectively. The results from this study were as follows : 1. The minimal inhibitory concentration(MIC) of poly-P to P. endodontalis appeared to be 0.04~0.05%. 2. Poly-P added to the P. endodontalis culture during the exponential phase of P. endodontalis was as much effective as poly-P added at the begining of the culture, suggesting that the antibacterial effect of poly-P is not much dependent on the initial inoculum size of P. endodontalis. 3. Poly-P are bactericidal to P. endodontalis, demonstrating the decrease of the viable cell counts. 4. Intracellular nucleotide release from the P. endodontalis, was not increased in the presence of poly-P and was not reversed by the addition of divalent cations like $Ca^{2+}$ and $Mg^{2-}$. 5. Under the TEM, it was observed that fine electro-dense materials were prominent in the poly-P grown P. endodontalis, appearing locally in the cell, and the materials were more abundant and more dispersed in the cell as the incubation time with poly-P increased. In addition, highly electron dense granules accumulated in many poly-P grown cells, most of which were atypical in their shape. 6. Binding of 32P-labeled poly-P to P. endodontalis appeared to be 32.8 and 45.5 and 53.4% at 30 minutes, 1 hours and 2 hours, respectively. 7. In the presence of poly-P. the synthesis of proteins with apparent molecular masses of 25, 27, 35, 45 was lost or drastically decreased whereas expression of a protein with an apparent molecular mass of 75 was elevated. 8. Proteolytic activity of P. endodontalis was decreased by poly-P. The overall results suggest that use of poly-P may affect the growth of P. endodontalis, and the anti-bacterial activity of poly-P seems largely bactericidal. Changes in shape, protein expression, and proteolytic activity of P. endodontalis by poly-P may be directly and indirectly attributed to the antibacterial effect of poly-P. Further studies will be needed to confirm the effect of poly-P.

• The Journal of Korean Orthopaedic Ultrasound Society
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• v.4 no.2
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• pp.77-83
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• 2011

Purpose: We compared with USG-guided steroid injection group and blind steroid injection group for the treatment of calcific tendinitis to evaluate the effectiveness of the treatment modalities. Materials and Methods: We reviewed two groups of calcific tendinitis treated with steroid injection and follow up upto 6 month after injection. Group I was blind injection for 88 patient with average age of 53years old and female gender in 77%. Group II was USG- guided injection for 102 patients with average age of 54years old and female gender in 85%. We compared follow up results according to age, gender, size of tendon involvement, initial VAS score, and phase of the calcific tendinitis between two groups. Results: At 6 month's follow up period, USG-guided injected group was more prevalent compared to blind injection group with 92%(94/102) and 72%(64/88) (P<0.05). In Group I, 77%(49/64) patients have improved symptom. And in Group II, 92%(86/94) patients have improved symptom in formative or resorptive phase. Despite of symptom improvement, calcium deposit is remained 47%(30/64) in Group I, and 20%(19/94) in Group II. Conclusion: Conservative treatment of Shoulder calcific tendinitis patients through USG-guided injection is more effective than Blind injection in pain relief & calcium decrease. The patients USG-guided injected group was more prevalent in follow up at outpatient clinic, throughout more accurate injection with improved confidence.

• Korean Journal of Environmental Biology
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• v.32 no.2
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• pp.138-152
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• 2014

The objective of the study survey was to determine the effect of marine sand extraction on community composition and rate of recolonization of the meiobenthos following cessation of mining activities. Because of meiobenthic distribution in nature, high abundance, intimate association with sediments, fast reproduction, benthic larva period, sensitivity to pollution and rapid life histories, meiobenthos are widely regarded as ideal organisms to study the potential ecological indicator of natural and anthropogenic stresses. The community structure of meiobenthos was studied at seven stations within sandy tidal and sub tidal zones in Jangbongdo in the Yellow Sea, Korea from Aug. 2006 to Dec. 2007. Meiobenthic samples were collected by three core samples, with a 3.6 cm in diameter, from each sediment sample taken with a Smith-McIntyre Grab. It was found that sand mining often causes complete removal of the sediment and the damage to the habitats of meiobenthos. This study in the effect showed that sand mining resulted in a reduction in total abundance and biomass of meiobenthos in mining area. The finding of this study further showed that initial restoration of abundance and biomass within one year of the cessation of sand mining.

• Radiation Oncology Journal
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• v.16 no.2
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• pp.185-194
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• 1998

Purpose : With the development of stereotactic immobilization systems capable of reliable serial repositioning, fractionated stereotactic radiation therapy (FSRT) offers the Potential for an improved treatment outcome by excellent dose delivery, and dose distribution characteristics with the favorable radiobiological properties of fractionated irradiation. We describe our initial experience using FSRT for the treatment of intracranial benign tumor. Materials and Methods : Between August 1995 and December 1996. 15 patients(7 males and 8 females aged 6-70 years) were treated with FSRT. The patients had the following diagnosis pituitary adenoma(10) including one patient who previously had received radiotherapy, craniopharyngioma (2), acoustic neurinoma (1), meningioma (2). Using the Gill-Thomas-Cosman relocatable head frame and multiple non-coplanar therapy, the daily dose of 2Gy was irradiated at 90% to 100% isodose surface of the isocenter The collimator sizes ranged from 26mm to 70mm. Results : In all patients except one follow-up lost, disease was well-controlled. Acute complication was negligible and no patient experienced cranial nerve neuropathies and radiation necrosis. In overall patient setup with scalp measurements, reproducibility was found to have mean of $1.1{\pm}0.6mm$ from the baseline reading. Conclusion : Relocatable stereotactic system for FSRT is highly reproducible and comfortable. Although the follow-up period was relatively short. FSRT is considered to be a safe and effective radiation technique as the treatment of intracranial tumor. But the fractionation schedule(fraction size, overall treatment time and total dose) still remains to be solved by further clinical trials.