• Journal of the Korean Society of Safety
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• v.26 no.1
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• pp.1-7
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• 2011

When the pumps stopped in the operation by the power failure, the hydraulic transients take place in the sudden change of a velocity of pipe line. Each and every water hammer problem shows the critical stage to be greatly affected the facts of safety and reliability in case of power failure. The field tests of the water hammer executed at Cheong-Yang booster pump station having an air chamber. The effects were studied by both the practical experiments and the CFD(Computational Fluid Dynamics : Surge 2008). The result states that the system with water hammering protection equipment was much safer when power failure happens. The following data by a computational fluid dynamic analysis are to be shown below, securing the system stability and integrity. (1) With water hammering protection equipment. (1) Change of pressure : Up to $15.5\;kg/cm^2$ in contrary to estimating $16.88\;kg/cm^2$. (2) Change rate of water level : 52~33% in contrary to estimating 55~27%. (3) Note that the operational pressure of pump runs approx. 145 m, lowering 155 m of the regularity head of pump. (4) Note that the cycle of water hammering delays from 80 second to 100 second, together with easing the function of air value at the pneumatic lines. (2) Change of pressure without water hammering protection equipment : Approximate $22.86\;kg/cm^2$. The comprehensive result says that the computational fluid dynamics analysis would match well with the practical field-test. It was able to predict Max. or Min. water hammering time in a piping system. This study aims effectively to alleviate water hammering in a pipe line to be installed with air chamber at the pumping station and results in making the stability of pump system in the end.

• Research in Mathematical Education
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• v.11 no.4
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• pp.247-263
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• 2007

Problem solving takes place not only in mathematics classes but also in real-world. For this reason, a problem and the structure of problem solving, and the enhancing of success in problem solving is a subject which has been studied by any educators. In this direction, the aim of this study is that the strategy used by students in Turkey when solving oral problems and their achievements of choosing operations when solving oral problems has been researched. In the research, the students have been asked three types of questions made up groups of 5. In the first category, S-problems (standard problems not requiring to determine any strategy but can be easily solved with only the applications of arithmetical operations), in the second category, AS-SA problems (problems that can be solved with the key word of additive operation despite to its being a subtractive operation, and containing the key word of subtractive operation despite to its being an additive operation), and in the third category P-problems (problematic problem) take place. It is seen that students did not have so much difficulty in S-problems, mistakes were made in determining operations for problem solving because of memorizing certain essential concepts, and the succession rate of students is very low in P-problems. The reasons of these mistakes as a summary are given below: $\cdot$ Because of memorizing some certain key concepts about operations mistakes have been done in choosing operations. $\cdot$ Not giving place to problems which has no solution and with incomplete information in mathematics. $\cdot$ Thinking of students that every problem has a solution since they don't encounter every type of problems in mathematics classes and course books.

• Journal of the Korean Geotechnical Society
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• v.37 no.7
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• pp.35-42
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• 2021

An experimental study was carried out on kaolinite-sand mixtures with various proportions of kaolinite content. To investigate physical behaviour of mixtures, index properties and compaction test results were analysed in various aspects. Moreover, to clearly see the interaction between kaolinite and sand particles, the observational analysis through microscopic image analysis device was conducted. The test results showed that an increase in the amount of kaolinite could create a strong bonding structure which resulted in higher specific surface available for activities of kaolinite particles. Also, an increase in the amount of the kaolinite resulted in an increase in the percentage of water sorption. Then it could accelerate the occupation rate of water which tended to take up the space that would have been occupied by solid particles, and accordingly, resulted in the decreased maximum dry unit weight and increased initial void ratio. Based on the microscopic image analysis, the samples were individually classified into three types of mixture such as sand dominant, intermediate fine content, and fine dominant. In addition, the fine and coarse grains seem to interact well in the mixtures with the fine content ranging from 25 to 40%.

• Quality Improvement in Health Care
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• v.20 no.1
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• pp.76-88
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• 2014

Objectives: Parents of a premature baby feel a pressure on their baby's growth and they are highly in need for proper education. However, the lack of proper education can cause the difficulty of follow-up care and rehospitalization. Currently, methods of education among each nurse are based on verbal explanation and can be often different. Therfore, it is true that the psychological burden is great during education. Hence, by enforcing discharge education activities, we intend to provide information; induce participation of parents; promote the level of performance; standardize education program; and increase the job satisfaction of nurses. Methods: NICU conducted a questionnaire survey of the demand and satisfaction for discharge education among mothers that left hospital. And before and after the improvement activity, the satisfaction level of mothers and nurses were studied, and rehospitalization rate were analyzed. Results 1)The survey results of the satisfaction level of mothers towards education program as followes: The level of understanding of content, general babysitting, special situation, education method, and educator attitude showed statistically significant increase. 2)The survey results of the satisfaction level of nurses towards education program as followes: While, the need for education program decreased, the adequacy of education content and method, consistency of education, understanding of learner, and learner's performance increased. All the factors except for the need for education program and the adequacy of education content showed statistically significant difference. 3)Rehospitalization rate of premature babies decreased. According to analysis of the cause of rehospitalization, breast-feeding related apnea turned out to be the highest. Conclusion: Through QI, satisfaction of mothers and nurses improved more than 10%. And rehospitalization rate of premature babies decreased by the same amount as well. Therefore, with the help of the standardized discharge education program, mothers who is not easy to take care of after leaving hospital can be seen to significantly affect their healthy growth and development.

• Journal of the Ergonomics Society of Korea
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• v.35 no.6
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• pp.569-580
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• 2016

Objective: This study aims to identify the most effective keyboard layout in the area of performance for securing usability in a smart watch-using environment and to verify the usability of touch keyboard calibrated by hand. Background: It is necessary to understand the environmental characteristics in using the smart watch and to secure the usability of touch keyboard based on this understanding in order to take account of the users who use the touch screen in the extreme input conditions caused by the small screen of a smart watch. Method: 30 participants in this study were required to input characters using the QWERTY keyboard and 3x4 keypad (Naratgul, Chunjiin), which were familiar with them, in order to grasp the keyboard layout suitable in the smart watch- using environment; the performance (error rate, performance time) of this case was measured. In addition, 30 participants in this study were required to input the characters setting the QWERTY keyboard with calibrated touch area and the one with uncalibrated touch area, based on the characteristics of touch behavior, by finger typing the keyboard, with the performance (error rate and performance time) of this case measured. Results: QWERTY keyboard (93.3sec) is found to be 31.2% faster than Naratgul keyboard, a kind of 3x4 keypad, and 43.6% faster than Chunjiin keyboard, in the area of efficiency, in the results of the usability evaluation regarding the keyboard layout. QWERTY keyboard with calibrated touch area (7.5%) is found to be 23.5% improved compared to the QWERTY keyboard with uncalibrated touch area (9.8%) in the area of accuracy (error rate). The results of the usability evaluation regarding the QWERTY keyboard with touch area calibrated by finger typing the keyboard and QWERTY keyboard with calibrated touch area (80.7sec) is found to be 5.7% improved compared to QWERTY keyboard with uncalibrated touch area (85.6sec) in the area of efficiency (performance time). Conclusion: QWERTY keyboard is found to have an effective layout in the area of efficiency in the smart watch-using environment, and its improved usability is verified in the areas of accuracy and efficiency in the QWERTY keyboard with a touch area calibrated by finger typing the keyboard. Application: The results of this study may be used to set up the basic touch keyboard of the smart watch. The input usability is expected to secure the smart watch-using environment, which is an extreme input condition by applying QWERTY keyboard with touch area calibrated by finger typing the keyboard.

• Journal of agricultural medicine and community health
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• v.37 no.4
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• pp.233-245
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• 2012

Objectives: Understanding the predictor of immunization status in childhood is critical issue to improve National Immunization Program (NIP). The aims of this study were to verify the status of up-to-date or complete immunization coverage and to investigate its related factors. Methods: As of 2005, according to local residence registry data, there were 2,188 children who aged 12 to 35 months in Nonsan city, Korea. We conducted household survey for aged 12 to 35 months children, using questionnaires to obtain data on the status of immunization such as BCG, DTaP (diphtheria, tetanus, and pertussis), Polio, and MMR (mump, measles, rubella). Finally 1,472 participated in the survey. The operating definitions used in this study were following; "Complete immunization rate" refers to the rate of children who received all immunization within recommended age intervals fully "on-time"; "The 4:3:1 series" means status of receiving the fourth diphtheria-tetanus-pertussis (4 DTP), the third Polio (3 Polio), and the first measles-mumps-rubella (1 MMR) doses. Multivariate logistic regression analyses were used to determine factors affecting complete vaccination coverage of children. Results: Immunization rates of vaccine based on the vaccination card were from 92.7% to 96.4% except 4th DTaP (79.3%). Complete immunization rate of Korea NIP was 74.0% and that of the 4:3:1 series was 77.1%. A parent as primary caregiver (OR 0.59, 95% CI 0.39-0.87 at 19-35 months of children's age) and first-born children (OR 1.79, 95% CI 1.05-3.03 at 24-35 months of children's age) were significantly related to complete immunization coverage of Korea NIP. And a parent as primary care giver (OR 0.58, 95% CI 0.38-0.88 at 19-35 months of children's age) and first-born children (OR 1.94, 95% CI 1.21-3.14 at 19-35 months, OR 2.23, 95% CI 1.27-3.91 at 24-35 months of children's age) were significantly related to complete immunization rate of 4:3:1 series. Conclusions: Government should take actions to increase complete immunization rate. In particular, intervention on the secondary caregiver and non-first-born children should be needed.

• Journal of Korea Water Resources Association
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• v.51 no.1
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• pp.11-18
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• 2018

The climate change impacts on hydrological components and water balance in Jeju Island were evaluated using multiple climate models and watershed model, SWAT-K. To take into account the uncertainty of the future forecast data according to climate models, climate data of 9 GCMs were utilized as weather data of SWAT-K for future period (2010-2099). Using the modeling results of the past (1992-2013) and the future period, the hydrological changes of each year were analyzed and the precipitation, runoff, evapotranspiration and recharge were increasing. Compared with the past, the change in the runoff was the largest (up to 50% increase) and the evapotranspiration was relatively small (up to 11% increase). Monthly results show that the amount of evapotranspiration and the amount of recharge are greatly increased as the amount of precipitation increases in August and September, while the amount of evapotranspiration decreases in the same period. January and December showed the opposite tendency. As a result of analyzing future water balance changes, the ratio of runoff, evapotranspiration, and recharge to rainfall did not change much, but compared to the past, the runoff rate increased up to 4.3% in the RCP 8.5 scenario, while the evapotranspiration rate decreased by up to 3.5%. Based on the results of other researchers and this study, it is expected that rainfall and runoff will increase gradually in the future under the assumption of present climate change scenarios. Especially summer precipitation and runoff are expected to increase. As a result, the amount of groundwater recharge in Jeju Island will increase.

• Journal of Chest Surgery
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• v.21 no.6
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• pp.1020-1029
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• 1988

The authors evaluated 153 patients who had undergone cardiac valve replacement between October 1979 and July 1988. The results are as follows: l. Out of 153 patients, there were 56 males and 97 females ranging from 15 to 62 years of age with a mean of 37 years. 2. Isolated mitral valve replacement took place in 82 patients, aortic valve replacement[AVR] in 16, double valve replacement[DVR] in 34, AVR combined with open mitral commissurotomy in 19, and tricuspid valve replacement[TVR] was done in 2 patients. 3. 153 patients had 187 prosthetic valves replaced with Ionescu-Shiley valves[16], Carpentier-Edwards[36], Bjork-Shiley[19], St. Jude Medical[108], and Duromedics[8]. 4. Our of 98 patients with atrial fibrillation[ 64% of a total 153 patients ] during the preoperative period, 22 patients recovered NSR[ 22/98, NSR recovery rate 22.4%] after valvular surgery and remaining 76 patients revealed persisting atrial fibrillation[76/153, 49.7% ]. 5. Preoperative episodes of systemic arterial embolization were attained in 9 patients[9/153, 6% ], and left atrial thrombi were confirmed in 22 patients intraoperatively[ 22/153, 14% ]. Of these, only one patient, however, demonstrated the correspondence of preoperative embolization and intraoperative existence of LA thrombi. 6. With mechanical prostheses, anticoagulant therapy was begun 48 hours after operation with sodium warfarin[2.5-5.0mg/day], maintaining the prothrombin time between 16 and 18 seconds or 30 to 50% of control values and continued for life. With tissue prostheses, sodium warfarin was continued for 3 to 6 months and converted into buffered ASA[ 325 mg/day ] for one year. 7. The mean follow-up for the survivors was 30.1 months, with a range from 3 months to 9 years. All suspected or confirmed thromboembolic episodes counted as events and occurred in 4 patients[ 1.04%/patient-year] with mechanical valve replacement. No persistent paralysis or death was noted. Late complications have not yet occurred in the patients with isolated MVR and AVR. 8. There were remarkable structural failures of tissue valves in 3 patients[ 1.9%/patient-year ], while no instance of failure of a mechanical valve. 9. There were 10 operative early deaths[10/153, 6.5%] and 5 late deaths[5/153, 3.3%]. Consequently, overall mortality was 9.8%[ 15/153] during follow-up period. 10. We currently favor using the St. Jude Medical valve in all patients requiring valve replacement except in those who can not take warfarin anticoagulation.

• Journal of dental hygiene science
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• v.14 no.2
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• pp.183-190
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• 2014

The purpose of this study was to examine the smoking-related characteristics of health and non-health related majors and the relationship between the smoking dependence and oral health practice of college students. The subjects in this study were the college students who were selected by convenience sampling from four different universities in the city of Jeonju, North Jeolla Province. The answer sheets from 811 respondents were analyzed. The findings of the study were as follows: The rate of the smoker students whose major was related to health stood at 20.6 percent, and that of the smoker students whose major was not related to health stood at 29.4%. There were significant differences according to the track of their major (p<0.05). As for links between smoking dependence and a plan to quit smoking, 32.7% of the health-related majors who considered themselves to depend on smoking replied they would give up smoking if there would be a rise in cigarette price (p<0.005), and 37% of the nonhealth related majors who considered themselves to depend on smoking gave the same answer. Thus, the largest group of the students intended to quit smoking if there would be a rise in cigarette price, and there were statistically significant differences according to smoking dependence (p<0.05). Concerning connections between smoking dependence and actual oral health practice, the non-health related majors who didn't consider themselves to depend on smoking got 3.53 in the item whether they brushed their teeth twice or more a day (p<0.05). In conclusion, the development and implementation of systematic programs that are to teach students to stay away from or quit smoking and take care of their oral health regardless of their major are required to step up the oral health promotion of college students.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.29 no.3
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• pp.217-226
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• 2007

Purpose: Distraction osteogenesis is considered to take favorable effect on the TMJ and be beneficial to prevent the relapse after the mandibular advancement of Class II malocclusion patient. This is the report with literature review on the mandibular advancement in the patients showing preoperative condylar resorption and who need larger amount of advancement. Patients and method: Distraction osteogenesis using intraoral device was performed for three mandibular hypoplasia patients (one male and two females). All patients were adult over 18 years old. The patients showed condylar bony resorption preoperatively. The distraction was performed intraorally with modified SSRO. After 7 days of latency period, activation was performed at the rate of 1.0 mm/day with twice turn. The devices were removed after 4-8 month consolidation period. Results: Total advancement of mandible was average 13 mm. One patient showed openbite immediately after removal of distraction device. It took long time to guide the openbite with elastics. The comparison between cephalometries immediately after device removal and postoperative six month revealed average 3.4 mm relapse. This means that mandibular advancement with distraction osteogenesis needs overcorrection and elastic rehabilitation even after enough consolidation periods. Conclusion: Larger amount of mandibular advancement could be achieved with distraction osteogenesis in severe mandibular hypoplasia with condylar resorption. However, some relapse was found during the follow-up period and the over correction is considered to be needed. The effect of distraction osteogenesis seems to be investigated with long-term follow-up.