• Journal of Welding and Joining
• /
• v.15 no.1
• /
• pp.92-100
• /
• 1997

Weld repair of ASTM A-470 class 8 high pressure (HP) steam turbine rotor steel has been performed to extend the service life of older fossil units. Microhardness measurements were conducted across the weldment from unaffected base metal (BM) to weld metal (WM). The hardness of the BM was VHN 253, however it dropped up to VHN 227 at the heat affected zone (HAZ) close to unaffected BM for multipass SAW. This area of hardness drop is called "siftening zone" and has a width of 0.5-0.6mm. During creep rupture test, failure occurred around the softening zone and rupture time was 772.4hr at 19Ksi (132 Mpa) and 593.deg. C. Multipass MIG and TIG welding have been employed to reduce the softening zone width. The softening zone width for MIG was 0.3-0.4mm and for TIG was zero-0.4mm depending on heat inputs. However creep rupture time was decreased as softening zone width reduced. Creep rupture time also showed a close relationship with heat inputs in TIG process. The higher heat input, the longer rupture time. Most failure occurred at intercritical HAZ (ICHAZ), however rupture location was shifted to coarse grained HAZ (CGHAZ) as heat input decreased. The rupture surface showed tearing and dimple which indicated transgranular fracture. fracture.

• Journal of Aerospace System Engineering
• /
• v.11 no.4
• /
• pp.48-53
• /
• 2017

Liquid rocket engines (LREs) are very complex systems that include combustion chambers, turbopumps, gas generators, ducts and tubes, valves and etc. Most components of the LREs require higher than or equal to level 6 IT (ISO Tolerance). The components along with pipe line and/or tubing must dispose not to interfere each other. In addition, effectiveness of maintenance and service after assembling should be considered when the allocation of the components are determined. Especially at the stage of the development, tolerance accumulations or unpredictable errors may result in misalignment and/or mismatches at interfaces of the parts. Namely, it is the engine assembling process that many inherent risks are realized and crises or incidents occur. Therefore, a rapid reaction system should be prepared. In this research, 7 tonf class liquid rocket assembling process was studied and actual building steps were introduced.

• Journal of Engineering Education Research
• /
• v.9 no.4
• /
• pp.28-45
• /
• 2006

As society has changed to being more knowledge-based, it is indispensable that Internet usage is incorporated into education. Therefore, the e-learning system is being developed in order to provide a proper environment. However, many LCMS that were developed, currently are not based on SCORM, the world e-learning standard, nor KEM, the Korea Educational Metadata of Korea Education & Research Information Service(KERIS), and hence, it is difficult to share learning contents developed from such varied environments. National Science Museum, a non-educational institution, also provides the educational science exhibits in reality or in cyber space, which cannot be produced by elementary schools, and secondary schools. Consequently, new systems are necessary, whose modules should be divided into four, for example, 'teachers', 'learners', 'managers', and 'instructors', and be associated with each other so that they are able to integrate and manage such systems, and be used in school education as well. Therefore, in this study, more advanced LMS and LCMS, which are the web-portal sites used for a cyber science class at the National Science Museum, were designed and established. These sites were surely based on the KEM, and the SCORM.

• Journal of Korean society of Dental Hygiene
• /
• v.2 no.1
• /
• pp.63-83
• /
• 2002

The purpose of this study was to serve as a basis for more efficient dental hygienist human resources utilization and for determining some of the right directions for supplementary education for dental hygienists, by examining how they actually worked and what they thought of job-related things. The subjects in this study were 537 dental hygienists who participated in a seminar by the Korea Dental Hygienist Association. After a survey was conducted, the following findings were given: 1. 50.2% of the dental hygienists investigated completed legally required eight-class education. Those who worked in clinics took less supplementary education classes than the others in the other types of dental institutions. The main reason they didn't receive supplementary education was financial burden and uncooperative employers. 73.2% took supplementary education at the association or its branches. The association was most favored by those in clinical sector as a place that provides supplementary education, followed by its branch and university in the order named. And the dental hygienists in public health sector preferred university most, and the next best favored one was the association and its branch in the order named. Those in clinical sector hoped to acquire clinical information on patient management, implant or aesthetics, and the dental hygienists in public health sector wanted to learn about health administration, public oral health operations and oral health education, which were different from what those in clinical sector wanted. 2. Regarding the period of service, 492% had worked for three years or more. This fact suggested that their service term and average age continued to grow. And they thought they would decide the retirement time on their own. 3. The most common yearly income ranged from 12 million won to 16 million won(40.7%). For-those in clinics, yearly income was 14.36 million won, and that of the dental hygienists who had worked for less than 3 years was 12.90 million won. 4. The Korea Dental Hygienist Association was most required to protect the rights and interests of the members and offer new knowledge and technology. 5. The largest group of them were engaged in patient management, and this type of job also was the most favored one for them to do. The greatest number of the dental hygienists in public health sector were in charge of dental treatment. 6. Concerning their turnover rate, 492% had never changed their occupation. Specifically, 70.0% of the respondents who had worked for less than 3 years had have no experience to do that. The time constraints for self-development and conflicts with other workers were the cause of their turnover. Those in dental hospital and general hospital changed their occupation chiefly due to the lack of time for self-development, and for the dental hygienists in clinics, the conflicts with other workers were the main reason. The above-mentioned findings suggested that the way the dental hygienists looked at things was undergoing change. The service area made a difference to their preference for the type of supplementary education and institution in charge of it, as those in public health and clinical sectors had a different opinion. And the dental hygienists in clinical sector had a different opinion as well, according to service area, about salaries, reason of not taking supplementary education, preferred type of supplementary education, cause of turnover, and type of occupation to which they hoped to change employment. To utilize and supply human resources in a more stabilized manner, job description should be more segmented, standardized and classified clearly, and dental hygienists should be motivated to perform their substantial jobs, including oral disease prevention, oral prophylaxis and oral health education. To make it happen, it seems that dentists are required to have a clear understanding of dental hygienist job and to change the way they look at it.

• Korean Journal of Environmental Agriculture
• /
• v.39 no.1
• /
• pp.1-9
• /
• 2020

BACKGROUND: The aim of this study was to investigate the soil chemical properties and soil bacterial community of the cropping system for Cnidium officinale Makino. METHODS AND RESULTS: The bacterial community was analyzed for the relative abundance and principal coordinated analysis (PCoA analysis) by using by Illumina Miseq sequencing. The correlation analysis between soil chemical properties and soil bacterial community were analyzed by Spearman's rank correlation and DISTLM analysis. Soil bacterial community (phylum and class) showed two distinct clusters consisting of cluster 1 (first cropping) and cluster 2 (continuous cropping) from 2 different cultivation methods of Cnidium officinale Makino. PCoA and DISTLM analyses showed that soil pH and Ca significantly affected soil bacterial community in cultivation area of Cnidium officinale Makino. In addition, Spearman's rank correlation showed significant correlation between relative abundance (Acidobacteria and Actinobacteria) and soil factors (soil pH and Ca). CONCLUSION: The results of this study were considered to be important for determining the correlation between soil properties and soil bacterial community of the cropping method for Cnidium officinale Makino. Furthermore, the results will be helpful to investigate the cause of continuous cropping injury of the Cnidium officinale Makino by examining the changes of soil properties and soil bacterial communities.

• Journal of the Korean earth science society
• /
• v.45 no.3
• /
• pp.260-276
• /
• 2024

The purpose of this study is to explore whether pre-service teachers majoring in earth science improve their perception of computational thinking through STEAM classes focused on engineering-based wave power plants. The STEAM class involved designing the most efficient wave power plant model. The survey on computational thinking practices, developed from previous research, was administered to 15 Earth science pre-service teachers to gauge their understanding of computational thinking. Each group developed an efficient wave power plant model based on the scientific principal of turbine operation using waves. The activities included problem recognition (problem solving), coding (coding and programming), creating a wave power plant model using a 3D printer (design and create model), and evaluating the output to correct errors (debugging). The pre-service teachers showed a high level of recognition of computational thinking practices, particularly in "logical thinking," with the top five practices out of 14 averaging five points each. However, participants lacked a clear understanding of certain computational thinking practices such as abstraction, problem decomposition, and using bid data, with their comprehension of these decreasing after the STEAM lesson. Although there was a significant reduction in the misconception that computational thinking is "playing online games" (from 4.06 to 0.86), some participants still equated it with "thinking like a computer" and "using a computer to do calculations". The study found slight improvements in "problem solving" (3.73 to 4.33), "pattern recognition" (3.53 to 3.66), and "best tool selection" (4.26 to 4.66). To enhance computational thinking skills, a practice-oriented curriculum should be offered. Additional STEAM classes on diverse topics could lead to a significant improvement in computational thinking practices. Therefore, establishing an educational curriculum for multisituational learning is essential.

• Journal of the Korean Society of School Health
• /
• v.7 no.1
• /
• pp.9-28
• /
• 1994

This study is to investigate the status and problems in the anual physical examination in elementary & secondary schools. The study helps the introduction of health assessment. Two hundreds and forty nurse teachers of elementary & seconcary school in Seoul received in-service traomong fpr 20 daus frp, September 7 to September 27, 1992. Questionnaires were given to the 240 teachers and the number of collected questionnaire is 112. The result of the questionnaire analysis is like the following. First, the answered teachers aged 35~39, 36.6%; experience 6~10 years 37.5%; the number of class 31~40, 28.6%. Among the answered of the school doctors is practicioners. The doctors major subjects are 26.8% of internal medicine and 35.7% of surgery. Second, in elementary & secondary school nurse teachers received in-service training for the primary health assessment. And then 37.5% of schools practiced the health assessment. The term of the health assessment is largely a-year-length, occurately its rate of schools have practiced the assessment reaches 81.0%. The number of health assessment are consist of eyes, nose, ear, throat, skin, spine, heart and other abnormal regions and diseases all over the body. And 83.3% of the rate of the health assessment includes all these contents. The period of the health assessment is 7 to 28 days. Third, the physical examination conducted by school doctors is 91.0%. The method is various; one is 56.6% of the students who checked first by he nurse teacher. The number of 15.1% of the schools is directly checked by the school doctor. The invited medical doctors are divided into two categories. The number of general physician is 61.9%. Contrary to that school doctors are 38.1%. The contents of the medical examination is all the items printed on the medical examination sheet. To follow the medical examination sheet the number of school is 59.6%. Eyes, throat, skin and heart etc. partly medical examination is 40.4%. The rate of schools that used only stethoscope, tongue pressor as the medical instruments reaches 53.4% and 87.1% of elementary & secondary school give the invited doctors the allowance a nurse teachers conference decided. The number of 8.9% schools pay the doctors independent allowance. The medical examomatopm allowance is 200 to 250 won per capita. The rate is 56.1%. Forth, after the medical examination 72.1% of school sends letter to the parents to notice the result of the examination. The number of response from parent is 12.5%. The observation record in secondary school is 70.6% for junior, and 80.0% for senior respectively, and 65.5% is for the elementary school children. To conclude the regular physical examination in elementary & secondary school is very important. Because the students are in the stage of rapid growth and development. Early finding of the students diseases can help to cure with ease. In the light of public health the management of health program in the elementary & secondary school is of consequence.

• The Korean Journal of Community Living Science
• /
• v.18 no.2
• /
• pp.335-348
• /
• 2007

This study aimed to investigate how the current elementary school teachers think about nutrition education, how they are teaching, and what kind of problems have occurred. And this study was made to provide basic materials to be used for the effective nutrition education in the elementary school. The survey was done on 60 elementary school teachers and 570 elementary school students of the 5th and 6th grade in Gyeonggi Province by questionnaire and analyzed for the perception of nutrition education, current status of nutrition education, nutrition knowledge and cooking knowledge. The average scores of nutrition knowledge were 2.72 for male and 3.75 for female students out of full score of 5. The fifth grade students learned more nutrition education than the sixth grade ones in accordance with the different curricula. Nutrition education was taught as apart of other subjects(87%) and mainly done by lectures. For most of the students, information source of the nutrition education was the meal service(47.4%) and the most common one was the Internet that 38.1 % of the teachers used. Most of the students responded that nutrition education was necessary in the curriculum of elementary school for proper growth(36.2%), intelligence(25.9%), health(21.5%), and dieting(16.4%). The perception for the suitable teacher was in the order of nutrition specialist and dietician. And the right time of the related class was in the order of spare time everyday, a special activity time, and the meal service time. The important contents of nutrition education were in the order of proper eating habits, growth & nutrition, food hygiene and diseases. Nutrition problems of the elementary students were in the order of unbalanced diet, too much ingestion of processed and instant foods, lack of table manners, and child fatness and weakness. 80.0% of the teachers supported the early nutrition education and demanded it should begin when children are in kindergarten. The analysis showed that nutrition education should be taught by parents(29.4%), teachers(29.2%), and nutritionists(25.9%) and that family and school should cooperate closely. Main responses of the teachers to the children's problems were that they had too much instant food, did not eat in a variety, and had no manners in eating. Ironically, they thought malnutrition, fainting and growth stunt were not important nutrition related problems.

• Korean Journal of Veterinary Research
• /
• v.41 no.2
• /
• pp.177-188
• /
• 2001

Mastitis is one of the most significant cause of economic loss to the dairy industry. Especially, Staphylococcus aureus is a major contagious mastitis-causing pathogen in dairy cattle. Because of its high transmission rate and resistance to antibiotic therapy, staphylococcal mastitis presents a constant threat to the dairy industry. Staphylococcal enterotoxin C(SEC) produced by S aureus has been known as one of superantigens which are able to stimulate a large proportion of T lymphocytes independently of their antigenic specificity. In this experiment, we have conducted preliminary studies with mice and lactating cows to evaluate the immunogenicity and safety of the experimental vaccine consists of SEC mutant antigen on controlling the bovine mastitis associated with S aureus infections. The average value of somatic cell counts in quarter milk, isolation rate of S aureus were consistently decreased in SEC-SER vaccinated groups, whereas antibody titers were highly increased in SEC-SER vaccinated groups. Peripheral blood were also collected from the lactating cows to determine the proportion of leukocyte subpopulation associated with humoral immunity(HI) and cell mediated immunity(CMI). Proportion of leukocyte subpopulation expressing $BoCD2^+$(total T lymphocyte), $BoCD4^+$(T helper cell), $BoCD8^+$(T cytotoxic/suppressor cell) and NonT/NonB lymphocyte which are involved in CMI in SEC-SER vaccinated groups were decreased for the initial stage after first vaccination and then increased from ten weeks after first vaccination maintaining elevated level till 14 weeks after vaccination. In contrast, proportion of monocyte, MHC class II and B lymphocyte which are associated with the production of primary immune response in SEC-SER vaccinated groups were increased for the initial period and then decreased from ten weeks after first vaccination. We present evidence that vaccination of SEC-SER mutant antigen in lactating cows induced a significant proliferation of bovine T lymphocytes. These results suggest that SEC-SER mutant antigen used in this experiment might be one of potential immunogen in developing innovative vaccine against bovine IMI associated with S aureus. Additional challenge trials should be carried out to evaluate substantial protection against S aureus under the commercial farm conditions.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.16 no.6
• /
• pp.4031-4039
• /
• 2015

The problems related with blood supply shortage and the stability of blood transfusion are on the rise, as it is expected that the blood doners will decrease but the blood use amount for aged population will increase, owing to low birth and aged population increase. The purpose of this study is to analyze the hospital characteristics which affect patients receiving and non-receiving blood transfusion for the knee and hip total replacement arthroplasty. Data were collected from Health Insurance Review and Assessment Service's 2011 sample data, and 5,370 inpatients were abstracted from them. Logistic regression analysis was performed, using SPSS 20. Independent variables used are hospital characteristics variables and patient characteristics variables. Hospital characteristics variables are hospital type, ownership, residence and the number of usable beds, and patient characteristics variables are gender, age, severity, type of anesthesia, main diagnosis, whether or not of anemia and insurance class. At the result of this study, it was found that hospital type, region, gender, age, severity, main diagnosis and whether or not of anemia were the factors that mostly affected the blood transfusion for knee arthroplasty. And hospital type, residence, gender, age, severity, type of anesthesia and whether of not of anemia were the factors that mostly affected the blood transfusion for hip arthroplasty. In addition to that, it is expected that this research which analyzed the present state of blood transfusion and its influence factors are cost effective, and would make a good use of preliminary data for good quality of medical service.