• Communications of Mathematical Education
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• v.26 no.1
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• pp.137-154
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• 2012

Approximation' is one of central conceptions in calculus. A basic conception for explaining 'approximation' is 'tangent', and 'tangent' is a 'line' with special condition. In this study, we will study pedagogically these mathematical knowledge on the ground of a viewpoint on the teaching of secondary geometry, and in connection with these we will suggest the teaching program and the chief end for the probable teaching. For this, we will examine point, line, circle, straight line, tangent line, approximation, and drive meaningfully mathematical knowledge for algebraic operation through the process translating from the above into analytic geometry. And we will construct the stream line of mathematical knowledge for approximation from a view of modern mathematics. This study help mathematics teachers to promote the pedagogical content knowledge, and to provide the basis for development of teaching model guiding the mathematical knowledge. Moreover, this study help students to recognize that mathematics is a systematic discipline and school mathematics are activities constructed under a fixed purpose.

• Korean Journal of Medicinal Crop Science
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• v.5 no.2
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• pp.154-161
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• 1997

The germination inhibitory effects of American ginseng (Panax quinquefolium Linne) pulp were discussed. The germination inhibitory effects of pulp juice were decreased in a concentration dependent manner. When the pulp juice was diluted 0 (original juice), 1, 2, 5, 10, 20, 50 and 100 times, the radicle lengths of the assay plant, Chinese cabbage (Brassica chinensis Linne), showed 0, 0.32, 0.72, 3.13, 4.83, 16.07, 16.73 and 23.50 mm, respectively (CK=25.98 mm). The pulp evidently inhibited the embryo growth in natural fruit. The longer was the duration that the pulp stayed around the seed, the longer was the time course needed for embryo getting free from the inhibitory effects of pulp. When the depulping was performed on the day 0, 15, 30 and 60 after harvest, the time courses needed for embryo extricating the residual inhibitory effects from pulp were 30, 75, 135 and 135 days, respectively. Moreover, if the pulp stayed around the seed with time, that would make the seed rotten ratio increase. When the pulp stayed around the seed for 0, 15, 30, 60 and 270 days, the seed rotten ratios were 5.47, 5.71, 19.05, 27.14 and 33.33%, respectively. Therefore, we concluded that the pulp could be included in the inhibitory components which made American ginseng seed get into dormancy.

• Korean Journal of Health Education and Promotion
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• v.19 no.2
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• pp.139-154
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• 2002

This study was conducted to examine to causes and symptoms of stress and factors influencing stress management of workers in beauty shops. 811 people who were working in the shops located in Daegu City and Kyungbuk Province were selected as subjects of this study. Data were collected from April 10, 2000 to July 10, 2000. The results of this study can be summarized as follows. According to general characteristics of the respondents, female was 90.8%. 42.1 % of them was in their twenties and 73.7% of them did not marry. 57.5% of the respondents grew up in big cities and 41.1% had no religion. 63.6% was graduated from junior colleges. 44.6% of them worked for below I year and 33.9% earned below four hundred and ninety thousand won per month. 55.8% of them was satisfied with their work aptitude, while 34.2% was not satisfied with it. In the case of satisfaction level with working environment, ‘common level’ was 46.3%, while 12.8% of them was unsatisfied with it. In the case of stress level by factors of stress related to working, male was higher (9.34 $\pm$ 2.38 points). Those who grew up in towns or villages and those who belonged to the middle class showed high stress level. Those who married and those who graduated from high school also displayed high stress level. It also appeared that monthly income influenced the stress level related to working.. The extent of stress level influencing physical causes appeared in order of health condition, education level, sex, satisfaction level with work aptitude, economic status, and working hours. The extent of stress level influencing whole organizational level appeared in order of satisfaction level with work aptitude, working hours, education level, health condition, and sex. The extent of stress factors influencing depressed feeling of stress symptom appeared in order of working hours, sex, amount of smoking, absence due to stress, age, health condition, and education level. The extent of influencing factors on active stress management appeared in order of satisfaction level with work aptitude, health condition, size of the shop, drinking, sex, and the number of day off. The extent of influencing factors on avoidable stress management appeared in order of age, absence due to stress, drinking, health condition, and sex.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.2
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• pp.154-162
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• 1992

This study was designed to investigate the antitumor effect and immunological activities of chitosan extracted from Solenocera prominetis toward on mire bearing sarcoma-180. The growth inhibition ratio of the chitosan toward sarcoma-180 showed at the highest level of 63.84% when chitosan were administrated at the concentration of 40mg/kg. The direct cytotoxic effect of chitosan was not observed in the mice bearing sar-roma-180 in vitro. In the effect of immunological activities, dose-dependent responses indicated by the increase of leucocyte, peritoneal exudate cell than that of control group when chitosan administered to the mice in the concentation of 30mg/kg and 40mg/kg. Also dose-dependent responses showed also by the increase of immunoorgans weights such as body weight, liver, spleen or thymus in the same concentration of 30mg/kg and 40mg/kg. Food pad swelling having the relationship with arthus reaction of antibody-mediated hypersensitivity and delayed type hypersensitivity was recovered the almost normal level. In the efforts of macrophge on phagocytes, there were not substantial differences in phagorytic and corrected phagocytic index. In the number of plaque forming cell(PFC), PFC on the 10$^{7}$ spleen cells were increased the levels of 18.88% and 31.83% when chitosan were adminstersd at the concentration of 30mg/kg and 40mg/kg.

• KSBB Journal
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• v.27 no.1
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• pp.67-74
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• 2012

In this study, the optimum conditions of fermentation were determined by isolating the microorganisms with the ability to bioconvert the Citrus peel flavonoid, and the effect of the fermented Citrus peel extract which was bioconverted on the oxidative damage of HIT-T15 cell was investigated. The Aureobasidium pullulans Y-12 was isolated and identified with the strains having bioconversion activity. The fermentation conditions for bioconversion activity were confirmed to be optimal when culturing for three days at $25^{\circ}C$, 150 rpm in a culture medium containing 5% Citrus peel power and 0.8% casitone. As a result of bioconversion, 32.8 mg/g and 21.5 mg/g of naringenin and hesperetin, which were aglycone flavones, were produced respectively. Also in the flavonoid content, it was confirmed that FCP produced 154.8 mg/g while CP produced 33.7 mg/g, thus producing more by approximately 4.6 times. As a result of treating FCP and CP after inducing the oxidative damage for HIT-T15 cell by treating the deoxy-D-ribose with $IC_{50}$ (38 mM) concentration, the surviving rate was recovered to 90% for FCP treatments in the 0.01 mg/mL concentration and for CP treatments in the 0.025 mg/mL concentration. Also in the insulin secretion rate, FCP treatments increased by 206% and CP treatments by 132% when treated in the 0.1 mg/mL concentration. As the bioconverted FCP can inhibit the oxidative damage of HIT-T15 cell in the low concentration, it was considered its usability as the functional material for prevention of the type 2 diabetes.

• Journal of Environmental Health Sciences
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• v.37 no.3
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• pp.182-192
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• 2011

Objectives: This study aims to identify the influential factors on the pulmonary function of targeted general residents in the areas surrounding Gwangyang Steel Mill. Methods: An PFT (Pulmonary Function Test) was conducted from May 2007 to November 2007 on 974 target residents (438 male, 536 female), including an exposed group (674 people) who resided within a radius of 5 km from Gwangyang Steel Mill in Gwangyang-si, Jeollanam-do and a control group (300 people) who resided outside a radius of 15 km. A survey related to personal characteristics, life habits, respiratory diseases and allergic symptoms, medical histories and living environments of the residents was also conducted to identify influential factors on pulmonary function. Results: As %$FEV_1$ and %FVC of the exposed group are 99.17% and 96.98%, respectively, and those of the control group are 105.47% and 101.91%, respectively, with the PFT values of the exposed group being lower than those of the control group (p<0.001), it turns out that the pollution in the industrial complex is likely to trigger a reduction in the pulmonary function of local residents. The odds ratio analysis result for asthma diagnosis history indicates that the odds ratios tend to be higher among surveyed residents who are living near above-average traffic volumes and are using beds, where it is statistically meaningful that especially the odds ratios are higher if the residences are closer to roads (p<0.01, CI=1.12-4.52). The factors that affect the FEV1 are identified as smoking, passive smoking, asthma diagnosis history, nasal congestion symptoms and allergic eye disease ($R^2$=0.154, p<0.001). The factors that affect the FVC are identified as smoking, passive smoking, asthma diagnosis history and allergic coryza ($R^2$=0.158, p<0.001). In addition, the analysis result for the relevance of air pollution levels to pulmonary function ($FEV_1$, FVC) shows that FEV1 and FVC tend to decrease as the concentration of $O_3$ increases. Conclusions: We believe that this study may provide preliminary data for the development of preventive measures for health effects on the residents and environmental health control measures for environmental pollution in the industrial complex area.

• The Journal of the Korean dental association
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• v.47 no.11
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• pp.750-757
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• 2009

Purpose : The purpose of this study is to evaluate the clinical availability of submentoplasty for esthethic improvement of the cervico-facial region of patients with obtuse chin-neck angle. Materials and methods : Case 1. We evaluate the changes of submental line length and chin-neck angle of 35-year-old woman with skeletal Class III and mandibular excess with excessive submental fat before and after surgery: Bilateral sagittal split ramus osteotomy(BSSRO) setback(5mm), Mandibular Angle Reduction, Reduction Malarplasty and Submentoplasty. In this case, It was done simultaneously with orthognathic surgery. Case 2. The changes of submental line length and chin-neck angle of 20-year-old man with skeletal class III and maxillary defiency were evaluated before surgery, at first surgery : Lefort I osteotomy(6mm posterior Impaction), BSSRO setback(9mm), Paranasal Augmentation and at second surgery: genioplasty(6mm advanced) with submentoplasty. In this case, submentoplasty and advancement genioplasty were done after 2 months post-operative periods. Results : Case 1. In case of the Skeletal Class III mandibular excess with submental fat deposit, It showed the improvement of submental angle and length of submental line after simultaneous submentoplasty. Submental angle is changed from $177^{\circ}$ (pre-op) to $151^{\circ}$ (post-op) and submental line length is changed from 8mm(pre-op) to 36mm(post-op). Case 2. The improvement of submental angle and length of submental line after delayed submentoplasty was aquired in case of the skeletal class III maxillary defiency. Submental angle is changed from $154^{\circ}$ (pre-op) to $161^{\circ}$ (first surgery) and to $153^{\circ}$ (second surgery) and submental line length is changed from 25mm(pre-op) to 19mm(first surgery) and to 23mm(second surgery). Conclusion : The results suggest that Submentoplasty is useful surgical procedure for esthethic improvement of the cervicofacial region of patients with obtuse chin-neck angle.

• 대한공업교육학회지
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• v.40 no.2
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• pp.130-154
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• 2015

The purpose of this study was to analyze the mechanical and metallurgical education (MME) teachers' job using the Developing a Curriculum (DACUM) methodology. To accomplish the purpose of this study, an MME teachers' job/occupational analysis was conducted in the following steps: "Planning the DACUM workshop," "Recruiting/Constructing the DACUM committee members," "Providing the DACUM orientation," "Holding the DACUM workshop," "Verifying the DACUM result," and "Refining the DACUM chart based on verification data." The DACUM job/occupational analysis was conducted by fifteen DACUM committee members in the DACUM workshop in January, 2015; moreover, the DACUM chart of the MME teachers was verified by the group of subject matter experts. The major findings of the study were as follows. First, this study defined the MME teachers who taught mechanical and metallurgical-related subjects to students with the secondary education teacher certification and performed work related to character education, career guidance, life guidance, and others in a specialized high school, the Meister high school. Second, this study determined 16 duties and 199 tasks for fulfilling the MME teachers' job; moreover, the study extracted the importance, difficulty, and frequency of each task and demand for the entry-level workforce. Third, this study provides the DACUM research chart based on the job/occupational analysis results of the MME teachers.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.2
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• pp.148-154
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• 2005

As the exciting point of each phase is determined by the position of rotor, the rotor's accurate position-information is needed for the Switched Reluctance Motor(SRM). When using an absolute-encoder or a resolver, to detect the location of rotor the initial starting is possible, as early sensing of rotor's location is possible. However, this is not appropriate, considering the economical efficiency, and in case of using the incremental-encoder, there's a problem at initial starting as it is not easy to track down the location of rotor at the very beginning. When using Hall-ICs, there's a fault, as it needs a special ring magnet. Considering the initial starting and economical efficiency, the optical sensor technique using a slotted-disk and an opto-interrupter is appropriate, however, this method needs three opto-interrupters and a slotted-disk when using the 6/4 pole SRM. Nevertheless, in this paper, it used only two optical sensors to operate 6/4 pole SRM and made the start up and also forward and reverse operation possible. By excluding the slotted-disc md shortening a optical sensor, it improved the convenience and economical efficiency of the production. Also, as the space for slotted-disc is no more needed, it was able to reduce the size of motor.

• KIPS Transactions on Computer and Communication Systems
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• v.7 no.6
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• pp.145-154
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• 2018

A loosely coupled message broker system is a popular method for integrating distributed software components. Especially, a distributed broker structure with multiple brokers with active-standby or active-active message replicas are used to enhance availability as well as message processing performance. However, there are problems in both active-standby and active-active replica structure. The active-standby has relatively low processing performance and The active-active structure requires a high synchronization overhead. In this paper, we propose an active-active structure of replicas to increase the availability of the brokers without compromising its high fault-tolerancy. In the proposed structure, standby replicas process the requests of the active replicas so that load balancing is achieved without additional brokers, while the distributed coordinators are used for the synchronization process to decrease the overhead. We formulated the overhead incurred when synchronizing messages among replicas, and the formulation was used to support the experiment results. From the experiment, we observed that replicas of the active-active structure show better performance than the active stand-by structure with increasing number of users.