• Journal of the Korean earth science society
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• v.36 no.7
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• pp.661-673
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• 2015

UBVI CCD photometry of the intermediate age open cluster NGC 7790 has been obtained using AZT-22 1.5 m telescope (f/7.74) at the Maidanak Astronomical Observatory in Uzbekistan. NGC 7790 contains three ${\delta}$ Cep variable stars including CEa Cas, CEb Cas, and CF Cas. PSF photometry was carried out using IRAF/DAOPHOT for all observations. The total number of stars observed both in V and I filter was 1008 and the limiting magnitude was $V{\approx}22$. To determine atmospheric extinction coefficients and photometric zero points, many blue and red standard stars as well as the standard stars in the celestial equator under various airmass were observed. Photometric data were transformed into the standard Johnson-Cousins' UBVI standard system. From the analysis of UBVI color-magnitude diagram and color-color diagram, the color excess in V and I filter [$E(B-V)=0.58{\pm}0.02$], the selective extinction ratio in V and I filter [$R_V{\equiv}A_V/E(B-V)=3.02{\pm}0.09$] and distance modulus ($V_0-M_V=12.65{\pm}0.10$) of the cluster were determined. The age of the cluster was estimated to be log $age=8.05{\pm}0.05$ [yr] based on the position of these three Cepheid variables in the color-magnitude diagram, the isochrone of the Geneva group ($Ekstr{\ddot{o}}m$ et al., 2012-Z=0.019), and the isochrone of the Padova group (Bressan et al., 2012-Z=0.014) were used to compare each other. Of them, the Geneva models that considered stellar rotation well described the position of ${\delta}$ Cepheid variables in the blue loop. Although they were well consistent with standard period-luminosity relation of ${\delta}$ Cepheid variables, three Cepheid variables in NGC 7790 were, on average, brighter by about 0.5 mag than the absolute magnitude estimated from the mean period-luminosity relation at a given period.

• Radiation Oncology Journal
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• v.18 no.2
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• pp.120-126
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• 2000

Purpose : Tumor hypoxia can be overcome with hypoxic cytotoxin. In mouse tumor, tirapazamine's efficacy of the potentiating radiation effect was tested by the tumor oxygenation status combined with hype facti on ated rad iotherapy .:The control and hypoxic mouse tumors we established by inoculation of RIF-1 tumor cells into the normal or previously irradiated back and thigh of C3H mice. When the tumors reached a proper size, both the control and hypoxic tumors were given hypefractionated treatments (8fractions/4 days) with saline (0.02 ml/g), tirapazamin (0.08 mM/0.02 ml/kg), irradiation (2.5 Gy), irradiation combined with tirapazamine given 30 minutes prior to each irradiation. The response was evaluated by the growth delay assay by measuring tumor size from day 0 (12 hrs prior to the first fractionation) to the day when the volume had 4-fold increase or cross sectional area had 2-fold increase. Results : Overall growth pattern showed that tirapazamine Potentiated radiation effect in back and thigh tumors grew in the normal and preirradiated tumor bed. With growth delay assay using reference point of initial tumor volume or cross sectional area, tirapazamine potentiated radiation effect 1.9 times for the control and 2.4 times for the hypoxic tumors in back, and 1.85 times for the control and 1.6 times for the hypoxic tumors. With reference of 4-fold increase of the initial volume or 2-fold increase of the cross sectional area, tirapazamine potentiated radiation effect 1.48 times for the control and 2.02 times for the hypxic tumors in back, and 1.85 times for the control and 1.6 times for the hypoxic tumors. Conclusions : Present result indicated that radiation response of hypoxic tumors was potentiated by tirapazamine in the back or thigh tumors grew in the control or preirradiated tumor bed, and potentiation of the hypoxic tumors was eDual to or greater than that of the control tumors in the back or thigh.

• The Korean Journal of Financial Management
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• v.24 no.1
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• pp.29-58
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• 2007

We develop a model to estimate the value of growth opportunities, which is based on the seminal papers of M&M(1961, 1963) and Lee(2006). Making use of the estimation model, we estimate a new proxy variable of the growth opportunities, other than the usual proxy variables such as quasi Tobin's Q, MBR, and so on. The new proxy variable of growth opportunities can represent a necessary condition to identify whether the increase in new investments are successful or not. The empirical findings on the growth opportunities during the IMF currency crisis period and the post-IMF period are as follows; First, the overall success rate of new investments is as low as 50%, that means only half of the listed firms were increasing new investments when they had the growth opportunities. Second, during the crisis, one third of the listed firms were experiencing negative growth opportunities. However, during the post-IMF period, the growth opportunities on new investments were turned to be positive due to the turnaround efforts of listed firms. Third, the value of intangible assets, which are resulting from the investment of R&D and human capital, are becoming more important than ever. It seems to be true that larger portions of the value of growth opportunities are coming from the intangible assets, not from the increases in new investments of the physical assets.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.3 no.2
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• pp.151-159
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• 2000

Purpose: Recently, a wide application of gastrofiberscopy in the pediatric group have revealed that nodular duodenitis is not an uncommon disease in children and is suspected to be associated with H. pylori infection. The aim of this retrospective study was to investigate the clinical and histopathologic features in children with nodular duodenitis, and to assess the correlations beween both. Methods: During a period of 5 years (Jan. 1995~Dec. 1999), we investigated clinical, endoscopic and histopathologic features of 39 consecutive patients diagnosed as having nodular duodenitis at Pediatric department of Seoul Red Cross Hospital. In 35 children with nodular duodenitis endoscopic biopsy specimens were stained with Hematoxylin & Eosin and Giemsa's stain, and were graded according to the criteria outlined by Triadafilopoulos, Whitehead et al., and Prieto et al.. Statistical analyses were performed with Graph PAD InStat. Results: The prevalence rate of nodular duodenitis was 17.1% and the most frequent chief complaint was abdominal pain (69.2%). Endoscopically grade 1 was the most common (45.7%) and nodular gastritis was coexistent in 28.3%. The most common histology of the duodenum was grade 2 (54.3%), and the most common histologic score of the stomach was 2 (42.9%). H. pylori was found in the duodenum in 37.1%, and in the stomach in 31.4%. The correlation coefficient between the endoscopic grade and the histologic grade of nodular duodenitis was 0.3983 (p=0.0178). And the correlation coefficient between the histologic grade and the grade of H. pylori colonization in the duodenum was 0.5154 (p=0.0018). Conclusion: There was significant correlation between the endoscopic grade and the histologic grade of nodular duodenitis, and was also significant correlation between the histologic grade and the grade of H. pylori colonization in the duodenum. Therfore H. pylori infection should be regarded as an etiologic factor of nodular duodenitis.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.5 no.1
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• pp.27-36
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• 2000

We investigated the phytoplankton community from June to September 1997 in the waters off Kohung, Korea where red tides dominated by harmful dinoflagellates had occurred from August to September or October since 1995. We took water samples five times from 5 depths at 6 or less stations in this study period. The most dominant harmful dinoflagellate during the red tide which had outbroken on August 24, 1997 was Gyrodinium impudicum, not Cochlodinium polykrikoides. On August 21 just before the harmful red tide occurred the abundance of G. impudicum at the inner bay station, 90cells $ml^{-1}$, was higher than that at the outer bay station. However, on August 27 just after the red tide had outbroken, the abundance of G. impudicum at the inner bay station did not increase, whereas that at the outer bay increased rapidly and reached to the maximum of 30,000 cells $ml^{-1}$. Instead, diatoms such as Skeleltonema costatum, Chaetoceros pseudocurvisetus, Pseudonitzschia pungens rapidly increased at the inner bay station where fresh water from lands has reached. The high abundance of diatoms might have inhibited the growth of red tide dinoflagellates at this station. The transport of already formed red tide patches from offshore areas, aggregation of scattered cells driven by physical forces, and/or competition between diatom and dinoflagellates might be responsible for this appearance of dense red tide patches at the outer bay station.

• Geophysics and Geophysical Exploration
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• v.20 no.4
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• pp.241-267
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• 2017

Since the liberation in 1945, Korean specialists in the field of geological science and mineral resources engineering have developed two disciplines through the cooperation and competition with each other. Specialists both in the geophysics and in the geophysical exploration, who share much, have developed their own fields deeper and broader. Since the late 1990s, specialists in both fields felt the need for an independent society to deal with their fields and discussed the establishment of such a society. In 1997, they discussed to establish a unified society which integrates both fields instead of separated societies. However, in 1998, the Korean Geophysical Society and the Korean Society of Exploration Geophysicists were separately established due to some practical problems. During 7 ~ 8 years since the establishment of the two societies, many members of the two societies intended that the two societies should integrate into a single comprehensive society based on the facts that many fields of each society are overlapped and naturally many members of one society are the members of the other society. The leaders of the two societies accepted these opinions also and began to discuss thoroughly the integration from 2005. Eventually, in 2007, the two societies successfully integrated and established the Korean Society of Earth and Exploration Geophysicists. The Korean Society of Earth and Exploration Geophysicists continues to cooperate and compete with other societies of geological science and mineral resources engineering in Korea and in circumpacific area including Asia, Oceania and Americas, contributing to the development of geophysics and geophysical exploration.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.1
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• pp.33-42
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• 2000

Adsorption onto the surfaces of solid particles is a well known phenomenon that causes the retardation effect of heavy metals in soils. For adequate remediation of soil and groundwater contamination, it is important to investigate the mobility of heavy metals that largely depends on pH conditions in the soil water since adsorption of heavy metals is pH-dependent. In this study, we investigated the transport of Zn ion under various pH conditions in a sandy soil by conducting batch and column tests. The batch test was performed using the standard procedure of equilibrating fine fractions collected from the soil with eleven different initial $ZnCl_2$ concentrations, and analysis of Zn ion in the equilibrated solutions using ICP-AES. The column test consisted of monitoring the concentrations of soil solutions exiting the soil column with time known as a breakthrough curve (BTC). We injected respectively $ZnCl_2$ and KCl solutions with the concentration of 10 g/L as a tracer in a square pulse type under three different pH conditions (7.7, 5.8, 4.1) and monitored the flux concentration at the exit boundary using an EC meter and ICP-AES. The resident concentration was also monitored at the 10cm-depth by Time Domain Reflectometry (TDR). The results of batch test showed that ion exchange process between Zn and other cations (Ca, Mg) was predominant. The retardation coefficients obtained from adsorption isotherms (Linear, Freundlich, Langmuir) resulted in the various values ranging from 1.2 to 614.1. No retardation effect but ion exchange was found for the BTCs under all pH conditions. This can be explained by the absence of other cations to desorb Zn ion from soil exchange sites under the conditions of ETC experiment imposing blank water as leachate in steady-state flow. As pH decreased, the peak concentration of Zn increased due to the competition of Zn with hydrogen ions ($H^+$) and the concentrations of other cations decreased. The peak concentration of Zn was increased by 12.7 times as pH decreased from 7.7 to 4.1.

• The korean journal of orthodontics
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• v.30 no.2 s.79
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• pp.175-183
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• 2000

The purpose of this study was to identify the compensatory adaptation of dentoalveolar structure according to the various skeletal relation through the statistical correlation between the anteroposterior, vertical skeletal and dentoalveolar relation. For this study, the sample were consisted of 101 adult subjects (51male and 50 female, mean age; male 23.6 years, female 21.5 years) who had good occlusion with the range of normal overjet and overbite and acceptable Angle's class I molar relationship which had not been related orthodontically The results were as follows : 1. Even though acceptable normal occlusion, the range of measurements which represent anteroposterior, vertical skeletal relation and dentoalveolar relation were very wide. 2. Upper and lower incisor axis were significantly correlated with anteroposterior skeletal relation, which means the mote lingual inclination of upper anterior teeth and the more labial inclination of lower anterior teeth according to the more anterior position of mandible to the maxilla (P<0.01). 3. Upper and 1ower anterior alveolar bone height was statistically correlated with the lower anterior vertical skeletal height. 4. Upper and 1ower alveolar bone height were not correlated with anteroposterior skeletal relation (P>0.05). 5. The correlation between the incisor axis and vertical skeletal was more closely related in upper anterior teeth than the lower anterior teeth. To summarize the above results, even though acceptable normal occlusion, skeletal and dentoalveolar relation was very widely ranged, and there were close relationship between the anteroposterior skeletal relation and the inclination of upper and lower anterior teeth and between the vertical skeletal relation and upper and lower anterior alveolar bone height. These finding can be concluded as compensatory adaptation to the different skeletal relationship.

• Progress in Medical Physics
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• v.11 no.1
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• pp.59-71
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• 2000

It is possible to obtain a fast CT scan during breath holding with spiral technique. But the risk of radiation is increased due to detailed and repeated scans. However, the limitation of X-ray doses is not fully specified on CT, yet. Therefore, the purpose of the present study is to define the limitation of X-ray doses on CT The CT unit was somatom plus 4. Alderson Rando phantom, Solenoid water phantom, TLD, and reader were used. For determining adequate position and size of organs, the measurement of distance(${\pm}$2mm) from the midline of vertebral body was performed in 40 women(20~40 years). On the brain scan for 8:8(8mm slice thickness, 8mm/sec movement velocity of the table) and 10:10(10mm slice thickness, 10mm/sec movement velocity of the table) methods, the absorption doses of exposed area of the 10:10 were slightly higher than those of 8:8. The doses of unexposed uterus were negligible on the brain scan for both 8:8 and 10:10. On the chest scan for 8:8, 8:10(8mm slice thickness, 10mm/sec movement velocity of the table), 10:10, 10:12(10mm slice thickness, 12mm/sec movement velocity of the table) and 10:15(10mm slice thickness, 15mm/sec movement velocity of the table) methods, 8:8 method of the absorption doses of exposure area was the most highest and 10:15 method was the most lowest. The absorption doses of 8:10 method was relatively lower than those of the other methods. In conclusion, the 8:10 method is the most suitable to give a low radiation burden to patient without distorting image quality.

• Journal of Korean society of Dental Hygiene
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• v.3 no.2
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• pp.127-141
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• 2003

The present study conducted a survey on the correlation between job satisfaction of dental hygienists and their workplace satisfaction and quality of life. A total of 249 surveys eligible among all the collected surveys were used in the analysis. The survey consisted of 61 items; 35 items were about self-evaluations of their satisfaction with their tasks, occupation, and workplace, as well as the degree of self-affirmation and their family-related satisfaction; the rests were 26 WHOQOL-BREF items investigating the quality of life. Collected data were processed using the SPSS Ver. 10.0 calculating the reliability with the frequency, percentage, and Cronbach's ${\alpha}$. Besides, one-way ANOVA and linear regression analysis examined the correlation between the variables. The conclusion is as follows: 1. By Age: Job satisfaction and family-related satisfaction were highest in the subjects aged 30 or older($3.5377{\pm}0.6891$ at pF0.05 and $4.1789{\pm}0.5431$ at pF0.05, respectively), though the differences were not statistically significant). Workplace satisfaction and self-affirmation were also highest in those aged 30 or order($3.5753{\pm}0.4210$ at pE0.05 and $3.9695{\pm}0.4616$ at pE0.05, respectively). The differences were statistically significant. Quality of life was also highest in those aged 30 or older($3.4095{\pm}0.3529$, pF0.05). 2. By Types of Dental Institutions: Job satisfaction and workplace satisfaction were highest in the subjects who worked at the dental department in a general hospital($3.7431{\pm}0.5940$ at pF0.05 and $3.6615{\pm}0.4602$ at pF0.05. respectively), though without statistical significance. Self-affirmation was highest in those working in university hospitals($3.773{\pm}0.7151$, pF0.05), while family-related satisfaction was highest, though without statistical significance, in those working at the dental department in general hospitals($4.2500{\pm}0.5528$, pF0.05), who also showed highest quality of life with statistical significance($3.4046{\pm}0.4155$, pE0.05). 3. By Years at Work: The subjects who had worked as a dental hygienist for 12 years or more showed highest satisfaction or scores in all the variables investigated: job satisfaction($3.9326{\pm}0.6673$, pE0.05): workplace satisfaction($3.8316{\pm}0.4342$, pE0.05): self-affirmation($4.2000{\pm}0.4551$, pE0.05); family-related satisfaction($4.3778{\pm}0.4692$, pF0.5): and quality of life($3.5235{\pm}0.4323$, pF0.05). All but quality of life showed a difference with statistical significance. 4. Correlation between Quality of Life and Overall Job Satisfaction: Quality of life doesn't have a correlation with the subjects' satisfaction with their occupation or with their self-affirmation, while it does have a correlation with workplace satisfaction and family-related satisfaction(F=15.983, Sig=0.000, $R^2$=0.209). Besides, workplace satisfaction has a significant correlation with all the variables: job satisfaction, self-affirmation, family-related satisfaction, and quality of life(F=38.563, Sig=0.000, $R^2$=0.389). The above result shows that workplace satisfaction has a high correlation with job satisfaction, self-affirmation, family-related satisfaction and with quality of life. Consequently, to enhance satisfaction of dental hygienists with their workplace, it would be important to promote their autonomy and make desirable wokplace environments so that they can work efficiently with pride for their job.