• The Journal of the Acoustical Society of Korea
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• v.20 no.2E
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• pp.30-45
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• 2001

This study considers the environmental factors affecting propagation loss and sonar performance in the continental regions of the East Coast Sea of Korea. Water mass distributions appear to change dramatically in a few weeks. Simple calculation with the case when the NKCW (North Korean Cold Water) develops shows that the difference in propagation loss may reach in the worst up to 10dB over range 5km. Another factor, an eddy, has typical dimensions of 100-200km in diameter and 150-200m in thickness. Employing a typical eddy and assuming frequency to be 100Hz, its effects on propagation loss appear to make lower the normal formation of convergence zones with which sonars are possible to detect long-range targets. The change of convergence zones may result in 10dB difference in received signals in a given depth. Thermal fronts also appear to be critical restrictions to operating sonars in shallow waters. Assuming frequency to be 200Hz, thermal fronts can make 10dB difference in propagation loss between with and without them over range 20km. An observation made in one site in the East Coast Sea of Korea reveals that internal waves may appear in near-inertial period and their spectra may exist in periods 2-17min. A simulation employing simple internal wave packets gives that they break convergence zones on the bottom, causing the performance degradation of FOM as much as 4dB in frequency 1kHz. An acoustic experiment, using fixed source and receiver at the same site, shows that the received signals fluctuate tremendously with time reaching up to 6.5dB in frequencies 1kHz or less. Ambient noises give negative effects directly on sonar performance. Measurements at some sites in the East Coast Sea of Korea suggest that the noise levels greatly fluctuate with time, for example noon and early morning, mainly due to ship traffics. The average difference in a day may reach 10dB in frequency 200Hz. Another experiment using an array of hydrophones gives that the spectrum levels of ambient noises are highly directional, their difference being as large as 10dB with vertical or horizontal angles. This fact strongly implies that we should obtain in-situ information of noise levels to estimate reasonable sonar performance. As one of non-stationary noise sources, an eel may give serious problems to sonar operation on or under the sea bottoms. Observed eel noises in a pier of water depth 14m appear to have duration time of about 0.4 seconds and frequency ranges of 0.2-2.8kHz. The 'song'of an eel increases ambient noise levels to average 2.16dB in the frequencies concerned, being large enough to degrade detection performance of the sonars on or below sediments. An experiment using hydrophones in water and sediment gives that sensitivity drops of 3-4dB are expected for the hydrophones laid in sediment at frequencies of 0.5-1.5kHz. The SNR difference between in water and in sediment, however, shows large fluctuations rather than stable patterns with the source-receiver ranges.

• IMMUNE NETWORK
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• v.3 no.4
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• pp.287-294
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• 2003

Background: In kidney transplantation, donor specific transfusion may induce tolerance as a result of some immune regulatory cells against the graft. In organ transplantation, the immune state arises from a relationship between the immunocompromised graft and the immunocompetent host. However, a reverse immunological situation exists between the graft and the host in hematopoietic stem cell transplantation (HSCT). In addition, early IL-2 injections after an allogeneic murine HSCT have been shown to prevent lethal graft versus host disease (GVHD) due to CD4+ cells. We investigated the induction of the regulatory CD4+CD25+ cells after a transfusion of irradiated recipient cells with IL-2 into a donor. Methods: The splenocytes (SP) were obtained from 6 week-old BALB/c mice ($H-2^d$) and irradiated as a single cell suspension. The donor mice (C3H/He, $H-2^k$) received $5{\times}10^6$ irradiated SP, and 5,000 IU IL-2 injected intraperitoneally on the day prior to HSCT. The CD4+CD25+ cell populations in SP treated C3H/He were analyzed. In order to determine the in vivo effect of CD4+CD25+ cells, the lethally irradiated BALB/c were transplanted with $1{\times}10^7$ donor BM and $5{\times}10^6$ CD4+CD25+ cells. The other recipient mice received either $1{\times}10^7$ donor BM with $5{\times}10^6$ CD4+ CD25- cells or the untreated SP. The survival and GVHD was assessed daily by a clinical scoring system. Results: In the MLR assay, BALB/c SP was used as a stimulator with C3H/He SP, as a responder, with or without treatment. The inhibition of proliferation was $30.0{\pm}13%$ compared to the control. In addition, the MLR with either the CD4+CD25+ or CD4+CD25- cells, which were isolated by MidiMacs, from the C3H/He SP treated with the recipient SP and IL-2 was evaluated. The donor SP treated with the recipient cells and IL-2 contained more CD4+CD25+ cells ($5.4{\pm}1.5%$) than the untreated mice SP ($1.4{\pm}0.3%$)(P<0.01). There was a profound inhibition in the CD4+CD25+ cells ($61.1{\pm}6.1%$), but a marked proliferation in the CD4+CD25- cells ($129.8{\pm}65.2%$). Mice in the CD4+CD25+ group showed low GVHD scores and a slow progression from the post-HSCT day 4 to day 9, but those in the control and CD4+CD25- groups had a high score and rapid progression (P<0.001). The probability of survival was 83.3% in the CD4+CD25+ group until post-HSC day 35 and all mice in the control and CD4+CD25- groups died on post-HSCT day 8 or 9 (P=0.0105). Conclusion: Donor graft engineering with irradiated recipient SP and IL-2 (recipient specific transfusion) can induce abundant regulatory CD4+CD25+ cells to prevent GVHD.

• Journal of dental hygiene science
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• v.9 no.1
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• pp.25-34
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• 2009

The present study purposed to survey dental hygiene students who will play important roles in guidance and to utilize the data as basic information for setting the direction of dental hygienists' efficient guidance for antismoking and developing antismoking education programs. For this purpose, a survey was conducted with 400 students at the Department of Dental Hygiene in Daejeon, Jollabuk-do and Jollanam-do during the period from May 19 to June 14 in 2008, and drew conclusions as follows: As to correlations among self-efficacy, smoking knowledge, and perception on guidance for antismoking, positive correlation was observed between self-efficacy and smoking knowledge (r=0.102), between self-efficacy and perception on guidance for antismoking (r=0.272), and between smoking knowledge and perception on guidance for antismoking (r=0.352). As to factors affecting perception on guidance for antismoking, the effect was high in order of perception on smoking, smoking knowledge, and self-efficacy. That is, perception on guidance for antismoking was more positive in those who thought that smoking must not be allowed, those with high smoking knowledge, and those with high self-efficacy. For dental hygienists' clinical activities for efficient prevention of smoking and guidance for antismoking, it is necessary to develop curriculums containing various practical contents.

• Journal of fish pathology
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• v.7 no.2
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• pp.161-171
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• 1994

In order to elucidate the outbreak mechanisms of a new disease which is characterized by an intense congestion in central venus sinuses(CVS) of gill filaments in cultured eel. these experiments were carried out; epidemically surveyed on the cultured eel farms in the vicinity of Kunsan city and experimentaliy outbreaked the disease in the stressful condition such as thermal and handling shock and innoculated the supernatant from the homogenate of naturally severe congested gill into eels and onto the monolayer of the CHSE-214. Although the frequency of congestion in eels of B, C, D and E farms were higher than in eels of A farms, the water qualities(stocked and cultured water) among farms were not a great difference. In eels of B, C, D and E farms, the values of haematocrit(Ht), haemoglobin(Hb), total protein(Tp), albumin(Alb), glucose(Glu), magnesium(Mg) were lower and the values of calcium(Ca), methemoglobin(Met-Hb), glutamic pyruvic transminase(GPT), glutamic oxalacetic transminase(GOT) higher than in eels of A farms. These valules have not related to the frequency of congestion. An intensive congestion and dilataton in CVS of gill filaments in experimentally handling-stressed eels produced similar histopathological changes to those observed in the spontaneously diseased eel, but not in eels experimentally injected with filtering contents. The cytopathic effect on the CHSE-214 was not observed. In stressed eels the congestion of gill was increased in relation to either the decrease ranges of water temperature or the incerase in accllimated times. And increase in Ht, Met-Hb, Alb, Glu, GOT and GPT and decrease in Mg, Hb and Tp were found, which had a close relationship to congestion of gill. Cortisol were increased according to the decrease ranges in acclimated water temperature. From these results, decrease in water temperature during selection placed eels upon the stressed condition, made increase in ionic strength in blood stream, and CVS was dilatated owing to the increased blood inflow.

• Journal of Environmental Science International
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• v.22 no.9
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• pp.1181-1186
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• 2013

Due to climate change, the occurrence of abnormal weather conditions has become more frequent, causing damage to vegetable crops grown in Korea. Hot pepper, Chinese cabbage and radish, the three most popular vegetables in Korea, are produced more in the field than in the greenhouse. It has been a trend that the time for field transplanting of seedlings is getting earlier and earlier as the spring temperatures keep rising. Seedlings transplanted too early in the spring take a longer time to resume the normal growth, because they are exposed to suboptimal temperature conditions. This study examined the influence of air temperature during seedling growth on the time required to reach the first fruit maturity and yield of hot pepper. Seedling plants of 'Super Manita' hot pepper was grown in temperatures $2.5^{\circ}C$ and $5.0^{\circ}C$ lower than the optimum temperature (determined by the average of temperatures for the past 5 years). Seedlings were transplanted into round plastic containers (30-cm diam., 45-cm height) and were placed in growth chambers in which the ambient temperature was controlled under natural sunlight. The growth of seedlings under lowered temperatures was reduced compared to the control. The mineral (K, Mg, P, N) concentrations in the leaf tissues were higher when plants were grown with the ambient temperature $2.5^{\circ}C$ lower than the optimum, regardless of changes in other growth parameters. Tissue calcium (Ca) concentration was the highest in the plants grown with optimum temperature. The carbohydrate to nitrogen (C/N) ratio, which was the highest (18.3) in the plants grown with optimum temperature, decreased concomitantly as the ambient temperature was lowered $2.5^{\circ}C$ and $5.0^{\circ}C$. The yield of the early harvested fruits was also reduced as the ambient temperature became lower. The first fruit harvest date for the plants grown with optimum temperature (June 27) was 13 days and 40 days, respectively, earlier than that in plants grown with $2.5^{\circ}C$ (July 10) and $5.0^{\circ}C$ (Aug 6) lower ambient temperatures. The fruit yield per plant for the optimum temperature (724 g) was the greatest compared to those grown with $2.5^{\circ}C$ (446 g) and $5.0^{\circ}C$ (236 g) lower temperatures. The result of this study suggests that the growers should be cautioned not to transplant their hot pepper seedlings too early into the field, since it may delay the time of first harvest eventually reducing total fruit yield.

• Journal of the korean academy of Pediatric Dentistry
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• v.35 no.4
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• pp.671-676
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• 2008

AgI/II of Streptococcus mutans(S. mutans) is an important virulence factor that contributes to the pathogenesis of S. mutans-induced dental caries. In oral cavity, salivary IgA antibodies act as safeguards against enormous challenges from oral bacteria. IgA antibodies inhibit adherence of cariogenic microorganisms to hard surfaces. Analysis of salivary IgA against AgI/II can be very useful diagnostic and powerful communication tools to the dental caries The purpose of this study was to investigate correlation between salivary AgI/II specific IgA and incidence of dental caries among children and young adults. Subjects consisted of 28 children and 18 adults. They were assigned to four groups : Group I deft index $\leq$3), Group II(deft index $\geq$4), Group III(DMFT index $\leq$3), Group IV(DMFT index $\geq$4) and they was divided two groups into caries resistant group and caries susceptible group. The study group were examined caries activity and their salivary IgA was evaluated by enzyme-linked immunosorbent assay. The results are as follows : 1. There was a positive correlation between the number of S. mutans and caries activity. 2. The titer of salivary IgA against the AgI/II was significantly higher in caries resistant group than caries susceptible group(p<0.01). 3. The titer of salivary IgA against the AgI/II in Group III was significantly higher than Group II(p<0.05).

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.3
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• pp.249-257
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• 2007

State of problem : The use of zirconium oxide all-ceramic material provides several advantages, including a high flexural strength(>1000MPa) and desirable optical properties, such as shading adaptation to the basic shades and a reduction in the layer thickness. Along with the strength of the materials, the cementation technique is also important to the clinical success of a restoration. Nevertheless, little information is available on the effect of different surface treatments on the bonding of zirconium high-crystalline ceramics and resin luting agents. Purpose : The aim of this study was to test the effects of surface treatments of zirconium on shear bond strengths between bovine teeth and a zirconia ceramic and evaluate differences among cements Material and methods : 54 sound bovine teeth extracted within a 1 months, were used. They were frozen in distilled water. These were rinsed by tap water to confirm that no granulation tissues have left. These were kept refrigerated at $4^{\circ}C$ until tested. Each tooth was placed horizontally at a plastic cylinder (diameter 20mm), and embedded in epoxy resin. Teeth were sectioned with diamond burs to expose dentin and grinded with #600 silicon carbide paper. To make sure there was no enamel left, each was observed under an optical microscope. 54 prefabricated zirconium oxide ceramic copings(Lava, 3M ESPE, USA) were assigned into 3 groups ; control, airborne-abraded with $110{\mu}m$ $Al_2O_3$ and scratched with diamond burs at 4 directions. They were cemented with a seating force of 10 ㎏ per tooth, using resin luting cement(Panavia $F^{(R)}$), resin cement(Superbond $C&B^{(R)}$), and resin modified GI cement(Rely X $Luting^{(R)}$). Those were thermocycled at $5^{\circ}C$ and $55^{\circ}C$ for 5000 cycles with a 30 second dwell time, and then shear bond strength was determined in a universal test machine(Model 4200, Instron Co., Canton, USA). The crosshead speed was 1 mm/min. The result was analyzed with one-way analysis of variance(ANOVA) and the Tukey test at a significance level of P<0.05. Results : Superbond $C&B^{(R)}$ at scratching with diamond burs showed the highest shear bond strength than others (p<.05). For Panavia $F^{(R)}$, groups of scratching and sandblasting showed significantly higher shear bond strength than control group(p<.05). For Rely X $Luting^{(R)}$, only between scratching & control group, significantly different shear bond strength was observed(p<.05). Conclusion : Within the limitation of this study, Superbond $C&B^{(R)}$ showed clinically acceptable shear bond between bovine teeth & zirconia ceramics regardless of surface treatments. For the surface treatment, scratching increased shear bond strength. Increase of shear bond strength by sandblasting with $110{\mu}m$ $Al_2O_3$ was not statistically different.

• Tuberculosis and Respiratory Diseases
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• v.43 no.1
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• pp.30-37
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• 1996

Background: The extraction methods of DNA from clinical samples are the major obstacle to use the PCR(polymerase Chain Reaction) in routine labortary for early detection of M. tuberculosis. We tried to improve the extraction method of DNA from sputum for establishment of the PCR in routine labortary by reducing the possibility of cross contamination and performing it easily and safely. Methods: We used the $InstaGene^{TM}$ DNA extraction kit(BioRad Co.) using Chelex 100 ion exchange resin for preparation of DNA. We compared InstaGene method in 100 cases of sputum from proteinase K method which is known as the most commonly used method for DNA purification(Experiment 1). And we compared InstaGene method in 98 cases of sputum from Microwave method developed by a company in Korea(Experiment 2). In experiment 1,245bps of IS6110 were amplified and then 188bps were amplified by nested PCR. In experiment 2,536bps in primary PCR and 276bps in nested PCR were amplified and analysed by agarose gel electrophoresis and EtBr staining. Results: When we chose AFB smear, culture, or AFB smear and culture as a standard test, PCR had low specificity and positive predictive value in both experiments. The InstaGene method has higher value in sensitivity and negative predictive value significantly than proteinase K method. The InstaGene method and the Microwave methods were similar in sensitivity, specificity, positive predictive value and negative predictive value. Conclusion: Even though both methods had lower possibility of cross contamination, shorter time requirement, simplicity, and economic advantages than Proteinase K method, the InstaGene method was a little simpler than the Microwave method. Therefore, in terms of usefulness in clinical application, the Instagene method seems to be the most useful method in DNA extraction for detection of M. tuberculosis using PCR. The reliability of this method will be clarified by further studies with enough clinical samples.

• Tuberculosis and Respiratory Diseases
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• v.52 no.3
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• pp.241-250
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• 2002

Background : Coal-worker's pneumoconiosis(CWP) is characterized by a chronic inflammatory lung reaction associated with macrophage accumulation in the alveolar spaces. CWP is usually divided into two stage : simple pneumoconiosis(SP) where there are a limited number of fibrotic lesions remain limited, with radiological opacities smaller than 1cm and progressive massive fibrosis(PMF), which is characterized by the development of a perifocal extensive fibrotic response of the lung and severe alterations in pulmonary function. In this study, the lymphocyte compartment and cytokine were evaluated by measuring the serum levels in the control, SP and PMF groups. Materials and Methods : The coal workers selected for this study were employees(patients?) of the Tae-Baek and Dong-Hae hospital. All were men, 45-76 years old and the mean duration of their exposure to coal dust was 23.2 years in the lymphocyte compartment and 24.3 years in the cytokine checked group. According to X-ray examination results, the patients were classified into either one of the SP, PMF categories. The normal controls examined were 26-70 years old men. The serum cytokine levels were estimated by using an end point enzyme immunoassay technique. Results : T lymphocyte, helper and suppressor T cells were highly related to pneumoconiosis in this study. A statistically significant decrease in the number of suppressor T lymphocytes was observed in the simple pneumoconiosis patients and at the same time, there was an increase in the lymphocyte index. Howevere, there was no statistically difference in the serum cytokines levels among the SP, PMF and control groups. Conclusion : T lymphocyte, helper T, and suppressor T cells may be highly related to the development of CWP compared to the control group particularly in the early stage of pneumoconiosis. The changes observed in the immunological system in patients with pneumoconiosis may lie at the bottom of the pathogenesis of fibrosis. Further study is needed to evaluate the lymphocyte compartment as a marker for pneumoconiosis development in the early stage.

• Korean Journal of Clinical Pharmacy
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• v.13 no.1
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• pp.29-39
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• 2003

Neurodegenerative disorders are associated with apoptosis as a causing factor or an inducer. On the other hand, it has been reported that epigallocatechin gallate (EUG), one of antioxidants and flavonoids, and z-VAD-fmk, a nonselective caspase inhibitor, suppress oxidative-radical-stress-induced apoptosis. However, it is not yet known what is the effects of EGCG and z-VAD-fmk on the apoptotic pathway is through phosphoinositide 3-kinase (PI3K), Akt and glycogen synthase kinase-3 (GSK-3) as well as mitochondria, caspase-3 and poly (ADP-ribose) polymerase (PARP). We investigated the effects of EGCG by using $H_2O_2$ treated N18D3 cells, mouse DRG hybrid neurons. Methods: Following 30 min $100\;{\mu}m\;H_2O_2$ exposure, the viability of N18D3 cells (not pretreated vs. EGCG or z-VAD-fmk pretreated) was evaluated by using MTT assay. The effect of EGCG on immunoreactivity (IR) of cytochrome c, caspase-3, PARP, PI3K/Akt and GSK-3 was examined by using Western blot, and was compared with that of z-Y4D-fmk. Results: EGCG or z-VAD-fmk pretreated N18D3 cells showed increased viability. Dose-dependent inhibition of caspase-3 activation accompanied by PARP cleavage were demonstrated by pretreatment of both agents. However, inhibition of cytochrome c release was only detected in EGCG pretreated N18D3 cells. On the pathway through PI3K/Akt and GSK-3, however, the result of Western blot in EGCG pretreated N18D3 cells showed decreased IR of Akt and GSK-3 and increased IR of p85a PI3K, phosphorylated Akt and GSK-3, and contrasted with that in z-VAD-fmk pretreated N18D3 cells showing no changes on each molecule. Conclusion: These data show that EGCG affects apoptotic pathway through upstream signal including PI3K/Akt and GSK-3 pathway as well as downstream signal including cytochrome c and caspase-3 pathway. Therefore, these results suggest that EGCG mediated activation of PI3K/Akt and inhibition GSK-B could be new potential therapeutic strategy for neurodegenerative diseases associated with oxidative injury.