• Tuberculosis and Respiratory Diseases
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• v.43 no.6
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• pp.954-964
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• 1996

Background : The type of the infiltrating cells in al veolitis may be determined by the chemokines in the lesion. MIP-1 ${\alpha}$, a C-C type chemokine, stimulates proliferation and cytokine secretion from macrophages and induces early neutrophilic and later monocytic inflammation in vi vo. IL-8, a C-X-C type chemokine is known to attract neutrophils and T-lymphocytes. This study is performed to find out the relative role of two different chemokines in diffuse interstitial lung disease. Subject and Method : We measured the secretion of MIP- 1 ${\alpha}$ and IL-8 from alveolar macrophages(AM), and their level in BAL fluid of 26 patients with DILD (10 IPF, 4 collagen disease, 10 sarcoidosis, and 2 hypersensitivity pneumonitis) and 7 normal control. Result: IL-8 secretion was significantly increased in patients with DILD ($8.15{\pm}4.58$ ng/ml) than in normal ($1.10{\pm}0.93$ ng/ml, p=0.0003). Significant correlation was found between IL-8 secretion and total cell number in BAL fluid (r=0.484, p=0.0068), %(r=0.592, p=0.0004) and No. (r=0.516, p=0.0042) of lymphocyte, and % of AM (r=-0.505, 0.0032). MIP- 1 ${\alpha}$ secretion was also increased in DILD ($2.41{\pm}1.45$ ng/ml) compared to control ($0.63{\pm}0.30$ ng/ml, p=0.0031), and showed a tendency of correlation with total cell number (r=0.368, p=0.0456) and No. of alveolar macrophages (r=0.356, p=0.0579) in BAL fluid. The concentration of IL-8 in BAL fluid was significantly increased in the patients with DILD ($40.4{\pm}34.5$ pg/ml) compared to control ($3.90{\pm}2.47$ pg/ml, p=0.0094) and it showed a significant correlation with the total cell number (r=0.484, p=0.0068), %(r=-0.505, p=0.0032) of AM, and % (r=0.592, p=0.0004) and No. (r=0.516, p=0.0042) of lymphocyte in BAL fluid. But there was a no significant difference in MIP- 1 ${\alpha}$ concentration in BAL fluid between normal control group and the patients with DILD. Conclusion : From the above results, we concluded that AM of DILD releases increased amount of both IL-8 and MIP- 1 ${\alpha}$ but IL-8 has better correlation with the type of alveolitis.

• Journal of Global Scholars of Marketing Science
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• v.20 no.3
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• pp.269-277
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• 2010

Previous studies have shown that the most important factor affecting customer loyalty in the service industry is service quality. However, on the subject of whether service quality has a direct or indirect effect on customer loyalty, scholars' views apparently vary. Some studies suggest that service quality has a direct and fundamental influence on customer loyalty (Bai and Liu, 2002). However, others have shown that service quality not only directly affects customer loyalty, it also has an indirect impact on customer loyalty by influencing customer satisfaction and perceived value (Cronin, Brady, and Hult, 2000). Currently, there are few domestic articles that specifically address the relationship between service quality and customer loyalty in the mobile communication industry. Moreover, research has studied customer loyalty as a whole variable, rather than breaking it down further into multiple dimensions. Based on this analysis, this paper summarizes previous study results, establishes an effect mechanism model among service quality, customer satisfaction, and customer loyalty in the mobile communication industry, and presents a statistical test on model assumptions by using customer investigation data from Heilongjiang Mobile Company. It provides theoretical guidance for mobile service management based on the discussion of the hypothesis test results. For data collection, the sample comprised mobile users in Harbin city, and the survey was taken by random sampling. Out of a total of 300 questionnaires, 276 (92.9%) were recovered. After excluding invalid questionnaires, 249 remained, for an effective rate of 82.6 percent for the study. Cronbach's ${\alpha}$ coefficient was adapted to assess the scale reliability, and validity testing was conducted on the questionnaire from three aspects: content validity, construct validity. and convergent validity. The study tested for goodness of fit mainly from the absolute and relative fit indexes. From the hypothesis testing results, overall, four assumptions have not been supported. The ultimate affective relationship of service quality, customer satisfaction, and customer loyalty is demonstrated in Figure 2. On the whole, the service quality of the communication industry not only has a direct positive significant effect on customer loyalty, it also has an indirect positive significant effect on customer loyalty through service quality; the affective mechanism and extent of customer loyalty are different, and are influenced by each dimension of service quality. This study used the questionnaires of existing literature from home and abroad and tested them in empirical research, with all questions adapted to seven-point Likert scales. With the SERVQUAL scale of Parasuraman, Zeithaml, and Berry (1988), or PZB, as a reference point, service quality was divided into five dimensions-tangibility, reliability, responsiveness, assurance, and empathy-and the questions were simplified down to nineteen. The measurement of customer satisfaction was based mainly on Fornell (1992) and Wang and Han (2003), ending up with four questions. Based on the study’s three indicators of price tolerance, first choice, and complaint reaction were used to measure attitudinal loyalty, while repurchase intention, recommendation, and reputation measured behavioral loyalty. The collection and collation of literature data produced a model of the relationship among service quality, customer satisfaction, and customer loyalty in mobile communications, and China Mobile in the city of Harbin in Heilongjiang province was used for conducting an empirical test of the model and obtaining some useful conclusions. First, service quality in mobile communication is formed by the five factors mentioned earlier: tangibility, reliability, responsiveness, assurance, and empathy. On the basis of PZB SERVQUAL, the study designed a measurement scale of service quality for the mobile communications industry, and obtained these five factors through exploratory factor analysis. The factors fit basically with the five elements, indicating the concept of five elements of service quality for the mobile communications industry. Second, service quality in mobile communications has both direct and indirect positive effects on attitudinal loyalty, with the indirect effect being produced through the intermediary variable, customer satisfaction. There are also both direct and indirect positive effects on behavioral loyalty, with the indirect effect produced through two intermediary variables: customer satisfaction and attitudinal loyalty. This shows that better service quality and higher customer satisfaction will activate the attitudinal to service providers more active and show loyalty to service providers much easier. In addition, the effect mechanism of all dimensions of service quality on all dimensions of customer loyalty is different. Third, customer satisfaction plays a significant intermediary role among service quality and attitudinal and behavioral loyalty, indicating that improving service quality can boost customer satisfaction and make it easier for satisfied customers to become loyal customers. Moreover, attitudinal loyalty plays a significant intermediary role between service quality and behavioral loyalty, indicating that only attitudinally and behaviorally loyal customers are truly loyal customers. The research conclusions have some indications for Chinese telecom operators and others to upgrade their service quality. Two limitations to the study are also mentioned. First, all data were collected in the Heilongjiang area, so there might be a common method bias that skews the results. Second, the discussion addresses the relationship between service quality and customer loyalty, setting customer satisfaction as mediator, but does not consider other factors, like customer value and consumer features, This research will be continued in the future.

• Strategy21
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• s.46
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• pp.239-276
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• 2020

The failure of early economic sanctions aimed at hurting the overall economies of targeted states called for a more sophisticated design of economic sanctions. This paved way for the advent of 'smart sanctions,' which target the supporters of the regime instead of the public mass. Despite controversies over the effectiveness of economic sanctions as a coercive tool to change the behavior of a targeted state, the transformation from 'comprehensive sanctions' to 'smart sanctions' is gaining the status of a legitimate method to impose punishment on states that do not conform to international norms, the nonproliferation of weapons of mass destruction in this particular context of the paper. The five permanent members of the United Nations Security Council proved that it can come to an accord on imposing economic sanctions over adopting resolutions on waging military war with targeted states. The North Korean nuclear issue has been the biggest security threat to countries in the region, even for China out of fear that further developments of nuclear weapons in North Korea might lead to a 'domino-effect,' leading to nuclear proliferation in the Northeast Asia region. Economic sanctions had been adopted by the UNSC as early as 2006 after the first North Korean nuclear test and has continually strengthened sanctions measures at each stage of North Korean weapons development. While dubious of the effectiveness of early sanctions on North Korea, recent sanctions that limit North Korea's exports of coal and imports of oil seem to have an impact on the regime, inducing Kim Jong-un to commit to peaceful talks since 2018. The purpose of this paper is to add a variable to the factors determining the success of economic sanctions on North Korea: preventing North Korea's evasion efforts by conducting illegal transshipments at sea. I first analyze the cause of recent success in the economic sanctions that led Kim Jong-un to engage in talks and add the maritime element to the argument. There are three conditions for the success of the sanctions regime, and they are: (1) smart sanctions, targeting commodities and support groups (elites) vital to regime survival., (2) China's faithful participation in the sanctions regime, and finally, (3) preventing North Korea's maritime evasion efforts.

• KDI Journal of Economic Policy
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• v.14 no.2
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• pp.109-153
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• 1992

This paper estimates a translog cost function for the Korea's banking industry and derives various implications on the prospect for the Korean banking structure in the future based on the estimated efficiency indicators for the banking sector. The Korean banking industry is permitted to operate trust business to the full extent and the security business to a limited extent, while it is formally subjected to the strict, specialized banking system. Security underwriting and investment businesses are allowed in a very limited extent only for stocks and bonds of maturity longer than three year and only up to 100 percent of the bank paid-in capital. Until the end of 1991, the ceiling was only up to 25 percent of the total balance of the demand deposits. However, they are prohibited from the security brokerage business. While the in-house integration of security businesses with the traditional business of deposit and commercial lending is restrictively regulated as such, Korean banks can enter the security business by establishing subsidiaries in the industry. This paper, therefore, estimates the efficiency indicators as well as the cost functions, identifying the in-house integrated trust business and security investment business as important banking activities, for various cases where both the production and the intermediation function approaches in modelling the financial intermediaries are separately applied, and the banking businesses of deposit, lending and security investment as one group and the trust businesses as another group are separately and integrally analyzed. The estimation results of the efficiency indicators for various cases are summarized in Table 1 and Table 2. First, security businesses exhibit economies of scale but also economies of scope with traditional banking activities, which implies that in-house integration of the banking and security businesses may not be a nonoptimal banking structure. Therefore, this result further implies that the transformation of Korea's banking system from the current, specialized system to the universal banking system will not impede the improvement of the banking industry's efficiency. Second, the lending businesses turn out to be subjected to diseconomies of scale, while exhibiting unclear evidence for economies of scope. In sum, it implies potential efficiency gain of the continued in-house integration of the lending activity. Third, the continued integration of the trust businesses seems to contribute to improving the efficiency of the banking businesses, since the trust businesses exhibit economies of scope. Fourth, deposit services and fee-based activities, such as foreign exchange and credit card businesses, exhibit economies of scale but constant returns to scope, which implies, the possibility of separating those businesses from other banking and trust activities. The recent trend of the credit card business being operated separately from other banking activities by an independent identity in Korea as well as in the global banking market seems to be consistent with this finding. Then, how can the possibility of separating deposit services from the remaining activities be interpreted? If one insists a strict definition of commercial banking that is confined to deposit and commercial lending activities, separating the deposit service will suggest a resolution or a disappearance of banking, itself. Recently, however, there has been a suggestion that separating banks' deposit and lending activities by allowing a depository institution which specialize in deposit taking and investing deposit fund only in the safest securities such as government securities to administer the deposit activity will alleviate the risk of a bank run. This method, in turn, will help improve the safety of the payment system (Robert E. Litan, What should Banks Do? Washington, D.C., The Brookings Institution, 1987). In this context, the possibility of separating the deposit activity will imply that a new type of depository institution will arise naturally without contradicting the efficiency of the banking businesses, as the size of the banking market grows in the future. Moreover, it is also interesting to see additional evidences confirming this statement that deposit taking and security business are cost complementarity but deposit taking and lending businesses are cost substitute (see Table 2 for cost complementarity relationship in Korea's banking industry). Finally, it has been observed that the Korea's banking industry is lacking in the characteristics of natural monopoly. Therefore, it may not be optimal to encourage the merger and acquisition in the banking industry only for the purpose of improving the efficiency.

• The Journal of Natural Sciences
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• v.4
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• pp.103-142
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• 1991

These studies were carried out to select somatic hybrid using selectable marker genes of Nicotiana glauca transformed by NPTII gene and Solanum tuberosum transformed by T- DNA, and to study characteristics of transformant. The results are summarized as follows. 1. Crown gall tumors and hairy roots were formed on potato tuber disc infected by A. tumefaciens Ach5 and A. rhizogenes ATCC15834. These tumors and roots could be grown on the phytohormone free media. 2. Callus formation from hairy root was prompted on the medium containing 2, 4 D 2mg/I with casein hydrolysate lg/l. 3. The survival ratio of crown gall tumor callus derived from potato increased on the medium containing the activated charcoal 0. 5-2. 0mg/I because of the preventions on the other hand, hairy roots were necrosis on the same medium. 4. Callus derived from hairy root were excellently grown for a short time by suspension culture on liquid medium containing 2, 4-D 2mg/I and casein hydrolysate lg/l. 5. The binary vector pGA643 was mobilized from E. coli MC1000 into wild type Agrobacteriurn tumefaciens Ach5, A. tumefaciens $A_4T$ and disarmed A. tuniefaciens LBA4404 using a triparental mating method with E. ccli HB1O1/pRK2013. Transconjugants were obtained on the minimal media containing tetracycline and kanamycin. pGA643 vectors were confirmed by electrophoresis on 0.7% agarose gel. 6. Kanamycin resistant calli were selected on the media supplemented with 2, 4-D 0.5mg/1 and kanamycin $100\mug$/ml after co- cultivating with tobacco stem explants and A. tumefaciens LBA4404/pGA643, and selected calli propagated on the same medium. 7. The multiple shoots were regenerated from kanamycin resistant calli on the MS medium containing BA 2mg/l. 8. Leaf segments of transformed shoot were able to grow vigorusly on the medium supplemented with high concentration of kanamycin $1000\mug$/ml. 9. Kanamycin resistant shoots were rooting and elongated on medium containing kanamycin $100\mug$/ml, but normal shoot were not. 10. For the production of protoplast from potato calli transformed by T-DNA and mesophyll tissue transformed by NPTII gene, the former was isolated in the enzyme mixture of 2.0% celluase Onozuka R-10, 1.0% dricelase, 1.0% macerozyme. and 0.5M mannitol, the latter was isolated in the enzyme mixture 1.0% Celluase Onozuka R-10, 0.3% macerozyme, and 0.7M mannitol. 11. The optimal concentrationn of mannitol in the enzyme mixture for high protoplast yield was 0.8M at both transformed tobacco mesophyll and potato callus. The viabilities of protoplast were shown above 90%, respectively. 12. Both tobacco mesophyll and potato callus protoplasts were fused by using PEG solution. Cell walls were regenerated on hormone free media supplemented with kanamycin after 5 days, and colonies were observed after 4 weeks culture.

• Tuberculosis and Respiratory Diseases
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• v.44 no.3
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• pp.559-573
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• 1997

Background : Asthma causes recurrent episodes of wheezing, breathlessness, chest tightness, and cough. These symptoms are usually associated with widespread but variable airflow limitation that is partly reversible either spontaneously or with treatment. The inflammation also causes an associated increase in airway responsiveness to a variety of stimuli. Method : Of the 403 adult bronchial asthma patients enrolled from March 1992 to March 1994 in Allergy Clinics of Severance Hospital in Yonsei University, this study reviewed the 97 cases to evaluate the treatment effects and to analyse prognostic factors. The patients were classified to five groups according to treatment responses ; group 1 (non control group) : patients who were not controlled during following up, group 2 (high step treatment group) : patients who were controlled longer than 3 months by step 3 or 4 treatment of "Global initiative for asthma, Global strategy for asthma management and prevention" (NHLBI/WHO) with PFR(%) larger than 80%, group 3 (short term control group) : patients who were controlled less than 1 year by step 1 or 2 treatment of NHLBI/WHO, group 4 (intermediate term control group) : patients who were controlled for more than 1 year but less than 2 years by step 1 or 2 treatment of NHLBI/WHO, group 5 (long term control group) : patients who were controlled for more than 2 years by step 1 or 2 treatment of NHLBI/WHO. Especially the patients who were controlled more than 1 year with negatively converted methacholine test and no eosinophil in sputum were classified to methacholine negative conversion group. We reviewed patients' history, atopy score, total IgE, specific IgE, methacholine PC20 and peripheral blood eosinophil count, pulmonary function test, steroid doses and aggrevation numbers after treatment. Results : On analysis of 98 patients, 20 cases(20.6%) were classified to group 1, 26 cases(26.8%) to group 2, 23 cases(23.7%) to group 3, 15 cases(15.5%) to group 4, and 13 cases(13.4%) to groups 5. There were no differences of sex, asthma type, family history, smoking history, allergic rhinitis and aspirin allergy among the groups. In long term control group, asthma onset age was younger, symptom duration was shorter, and initial pulmonary function was better. The long term control group required lower amounts of oral steroid. had less aggrevation during first 3months after starting treatment and shorter duration from enrollment to control Atopy, allergic skin test, sputum and blood eosinophil, total IgE, nonspecific bronchial responsiveness was not significantly different among the groups. Seven out of 28 patients who were controlled more than 1 years showed negatively converted methachloine test and no eosinophils in the sputum. The mean control duration was $20.3{\pm}9.7$ months and relapse did not occur. Conclusion : Patients who had asthma of onset age younger, shorter symptom duration, better PFT, lower treatment initial steps, lower amounts of steroid needs and less aggravation numbers after starting treatment were classified in the long term control groups compared to the others.

• Tuberculosis and Respiratory Diseases
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• v.45 no.2
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• pp.380-387
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• 1998

Background: Minimal pressure support(PSmin) is a level of pressure support which offset the imposed work of breathing(WOBimp) developed by endotracheal tube and ventilator circuits in pressure support ventilation While the lower applied level of pressure support compared to PSmin could induce respiratory muscle fatigue, the higher level than PSmin could keep respiratory muscle rest resulting in prolongation of weaning period during weaning from mechanical ventilation PSmin has been usually applied in the level of 5~10 cm$H_2O$, but the accurate level of PSmin is difficult to be determinated in individual cases. PSmin is known to be calculated by using the equation of "PSmin = peak inspiratory flow rate during spontaneus ventilation$\times$total ventilatory system resistance", but correlation of calculated PSmin and measured PSmin has not been known. The objects of this study were firstly to assess whether customarily applied pressure support level of 5~10 cm$H_2O$ would be appropriate to offset the imposed work of breathing among the patients under weaning process, and secondly to estimate the correlation between the measured PSmin and calculated PSmin. Method : 1) Measurement of PSmin : Intratracheal pressure changes were measured through Hi-Lo jet tracheal tube (8mm in diameter, Mallinckroft, USA) by using pulmonary monitor(CP-100 pulmonary monitor, Bicore, USA), and then pressure support level of mechanical ventilator were increased until WOBimp was reached to 0.01 J/L or less. Measured PSmin was defined as the lowest pressure to make WOBimp 0.01 J/L or less. 2) Calculation of PSmin : Peak airway pressure(Ppeak), plateau airway pressure(Pplat) and mean inspiratory flow rate of the subjects were measured on volume control mode of mechanical ventilation after sedation. Spontaneous peak inspiratory flow rates were measured on CPAP mode(O cm$H_2O$). Thereafter PSmin was calculated by using the equation "PSmin = peak inspiratory flow rate$\times$R, R = (Ppeak-Pplat)/mean inspiratory flow rate during volume control mode on mechanical ventilation". Results: Sixteen patients who were considered as the candidate for weaning from mechanical ventilation were included in the study. Mean age was 64(${\pm}14$) years, and the mean of total ventilation times was 9(${\pm}4$) days. All patients except one were males. The measured PSmin of the subjects ranged 4.0~12.5cm$H_2O$ in 14 patients. The mean level of PSmin was 7.6(${\pm}2.5\;cmH_2O$) in measured PSmin, 8.6 (${\pm}3.25\;cmH_2O$) in calculated PSmin Correlation between the measured PSmin and the calculated PSmin is significantly high(n=9, r=0.88, p=0.002). The calculated PSmin show a tendancy to be higher than the corresponding measured PSmin in 8 out of 9 subjects(p=0.09). The ratio of measured PSmin/calculated PSmin was 0.81(${\pm}0.05$). Conclusion: Minimal pressure support levels were different in individual cases in the range from 4 to 12.5 cm$H_2O$. Because the equation-driven calculated PSmin showed a good correlation with measured PSmin, the application of equation-driven PSmin would be then appropriate compared with conventional application of 5~10 cm$H_2O$ in patients under difficult weaning process with pressure support ventilation.

• The Korean Journal of Nuclear Medicine
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• v.34 no.5
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• pp.418-425
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• 2000

Purpose: There is no established formula for estimating renal depths in Korean. As a result, we undertook this study to develop a new formula, and to apply this formula in the calculation of glomerular filtration rate (GFR). Materials and Methods: We measured the renal depth (RD) on the abdominal CT obtained in 300 adults (M:F: 167:133, mean age 50.9 years) without known renal diseases. The RDs measured by CT were compared with the estimated RDs based on the Tonnesen and Taylor equations. New formulas were derived from the measured RDs in 200 out of 300 patients based on several variables such as sex, age, weight, and height by multiple regression analysis. The RDs estimated from the new formulas were compared with the measured RDs in the remaining 100 patients as a control. In 48 patients who underwent Tc-99m DTPA renal scintigraphy, GFR was measured with three equations (new formula, Tonnesen and Taylor equations), respectively, and compared with each other. Results: The mean values of the RDs measured from CT were 6.9 cm for right kidney of the men (MRK), 6.7 cm for left kidney of the men (MLK), 6.7 cm for right kidney of the women (WRK), and 6.6 cm for left kidney of the women (WLK). The RDs estimated from Tonnesen equation were shorter than the ones measured from CT significantly. The newly derived formulas were 12.813 (weight/height)+0.002 (age)+ 2.264 for MRK, 15.344 (weight/height)+0.011 (age)+0.557 for MLK, 12.936 (weight/height)+ 0.014 (age)+1.462 for WRK and 13.488 (weight/height)+0.019 (age)+0.762 for WLK. The correlation coefficients of the RD measured from CT and estimated from the new formula were 0.529 in MRK, 0.729 in MLK, 0.601 in WRK, and 0.724 in WLK, respectively. The GFRs from the new formula were significantly higher than those from the Tonnesen equation significantly, which was the most similar to normal GFR values. Conclusion: We generated new formulas for estimating RD in Korean from the data by CT. By adopting these formulas, we expect that GFR can be measured by the Gates method accurately in Korean.

• Journal of Intelligence and Information Systems
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• v.23 no.3
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• pp.45-67
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• 2017

According to the Internet Usage Research performed in 2016, the number of internet users and the internet usage have been increasing. Smartphone, compared to the computer, is taking a more dominant role as an internet access device. As the number of smart devices have been increasing, some views that the demand on high-speed internet will decrease; however, Despite the increase in smart devices, the high-speed Internet market is expected to slightly increase for a while due to the speedup of Giga Internet and the growth of the IoT market. As the broadband Internet market saturates, telecom operators are over-competing to win new customers, but if they know the cause of customer exit, it is expected to reduce marketing costs by more effective marketing. In this study, we analyzed the relationship between the cancellation rates of telecommunication products and the factors affecting them by combining the data of 3 cities, Anyang, Gunpo, and Uiwang owned by a telecommunication company with the regional data from KOSIS(Korean Statistical Information Service). Especially, we focused on the assumption that the neighboring areas affect the distribution of the cancellation rates by coupling type, so we conducted spatial cluster analysis on the 3 types of cancellation rates of each region using the spatial analysis tool, SatScan, and analyzed the various relationships between the cancellation rates and the regional data. In the analysis phase, we first summarized the characteristics of the clusters derived by combining spatial information and the cancellation data. Next, based on the results of the cluster analysis, Variance analysis, Correlation analysis, and regression analysis were used to analyze the relationship between the cancellation rates data and regional data. Based on the results of analysis, we proposed appropriate marketing methods according to the region. Unlike previous studies on regional characteristics analysis, In this study has academic differentiation in that it performs clustering based on spatial information so that the regions with similar cancellation types on adjacent regions. In addition, there have been few studies considering the regional characteristics in the previous study on the determinants of subscription to high-speed Internet services, In this study, we tried to analyze the relationship between the clusters and the regional characteristics data, assuming that there are different factors depending on the region. In this study, we tried to get more efficient marketing method considering the characteristics of each region in the new subscription and customer management in high-speed internet. As a result of analysis of variance, it was confirmed that there were significant differences in regional characteristics among the clusters, Correlation analysis shows that there is a stronger correlation the clusters than all region. and Regression analysis was used to analyze the relationship between the cancellation rate and the regional characteristics. As a result, we found that there is a difference in the cancellation rate depending on the regional characteristics, and it is possible to target differentiated marketing each region. As the biggest limitation of this study and it was difficult to obtain enough data to carry out the analyze. In particular, it is difficult to find the variables that represent the regional characteristics in the Dong unit. In other words, most of the data was disclosed to the city rather than the Dong unit, so it was limited to analyze it in detail. The data such as income, card usage information and telecommunications company policies or characteristics that could affect its cause are not available at that time. The most urgent part for a more sophisticated analysis is to obtain the Dong unit data for the regional characteristics. Direction of the next studies be target marketing based on the results. It is also meaningful to analyze the effect of marketing by comparing and analyzing the difference of results before and after target marketing. It is also effective to use clusters based on new subscription data as well as cancellation data.

• Restorative Dentistry and Endodontics
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• v.32 no.3
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• pp.248-259
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• 2007

The aim of this research was to study the effect of intermittent polymerization on marginal adaptation by comparing the marginal adaptation of intermittently polymerized composite to that of continuously polymerized composite. The materials used for this study were Pyramid (Bisco Inc., Schaumburg, U.S.A.) and Heliomolar (Ivoclar Vivadent, Liechtenstein) . The experiment was carried out in class II MOD cavities prepared in 48 extracted human maxillary premolars. The samples were divided into 4 groups by light curing method: group 1- continuous curing (60s light on with no light off), group 2-intermittent curing (cycles of 3s with 2s light on & 1s light off for 90s); group 3- intermittent curing (cycles of 2s with 1s light on & 1s light off for 120s); group 4- intermittent curing (cycles of 3s with 1s light on & 2s light off for 180s). Consequently the total amount of light energy radiated was same in all the groups. Each specimen went through thermo-mechanical loading (TML) which consisted of mechanical loading (720,000 cycles, 5.0 kg) with a speed of 120 rpm for 100hours and thermocycling (6000 thermocycles of alternating water of $50^{\circ}C$ and $55^{\circ}C$). The continuous margin (CM) (%) of the total margin and regional margins, occlusal enamel (OE), vertical enamel (VE), and cervical enamel (CE) was measured before and after TML under a $\times200$ digital light microscope. Three-way ANOVA and Duncan's Multiple Range Test was performed at 95% level of confidence to test the effect of 3 variables on CM (%) of the total margin: light curing conditions, composite materials and effect of TML. In each group, One-way ANOVA and Duncan's Multiple Range Test was additionally performed to compare CM (%) of regions (OE, VE CE). The results indicated that all the three variables were statistically significant (p < 0.05). Before TML, in groups using Pyramid, groups 3 and 4 showed higher CM (%) than groups 1 and 2, and in groups using Heliomolar. groups 3 and 4 showed higher CM (%) than group 1 (p < 0.05). After TML, in both Pyramid and Heliomo)ar groups, group 3 showed higher CM (%) than group 1 (p < 0.05) CM (%) of the regions are significantly different in each group (p < 0.05). Before TML, no statistical difference was found between groups within the VE and CE region. In the OE region, group 4 of Pyramid showed higher CM (%) than group 2, and groups 2 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). After TML, no statistical difference was found among groups within the VE and CE region. In the OE region, group 3 of Pyramid showed higher CM (%) than groups 1 and 2, and groups 2,3 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). It was concluded that intermittent polymerization may be effective in reducing marginal gap formation.