• Journal of Biosystems Engineering
• /
• v.2 no.1
• /
• pp.7-24
• /
• 1977

This paper is the forth and fifth one of the study on balanced type oscillating mole drainer. In the light of the results from previous reports about the model tests, some design criteria were established and a prototype machine was set up for experimental purpose. Motion characteristics and functionof the each parts of the machine were checked and analyzed. After that, performance tests of the prototype machine were carried out in thefield. Obtained results are summarized as follows ; 1. Ten centimeter of the bullet diameter was determined so as to be able to attach it to the tractors with capacity of 30 PS to 40 PS. 2. To maintain the balance between the moments of the front shank and rear shank, the oscillating amplitude of the rear bullet was determined to be larger than that of the front bullet. At the same time , the oscillating direction of the rear bullet was designed with the inclines of ten to thirty degrees. 3. An octagonal dynamo transduced was developed for measuring the compressive force of the upper link is measuring the draft force of the machine. Acceptable linear relationship between forces and strain responses from O.D.T. was obtained. 4. Analysing the balancing mechanism of the acting part of the machine , it was found that the total draft force of the machine was equal to the difference between the sum of the draft force produced from the right and left side bending moments of the lower drawber and the compressive force on the upper link. 5. There are acceptable linear relationship between the strain and twisting moment by driving shaft, and between strain and shank moment. Above results enable us to carry out the field experiment with prototype machine. 6. When the test machine was used in the field, it was possible to reduce the oscillating acceleration by forty percent in average as compared it with the single bullet mole drainer. 7. When the test machine was used under the oscillating condition, the dratt torce was reduced by 27 percent to 59 percent as compared it with the test machine under non-oscillating condition, while the draft force was increased by 7 percent to 20 percent as compared it with the mole drainer having oscillating single bullet. The reasoning behind this fact was considered as the resistance force due to the rear shank and bullet. 8. As the amplitude and frequency of the bullet were increased, the torque was increased accordingly. This tendency could be varied with the various characteristics of the given soils. And the larger frequency and amplitute, the more increasing oscil\ulcornerlating power but decreasing draft brce were needed, and draft force was increased as the velocity was increased.9. When the amplitude of the rear bullet was designed to be larger than that of the front bullet, the minimum value of the moment was lowered and oscillating acceleration was reduced. And when the oscillating direction of the rear bullet was declined back\ulcornerwards, oscillating acceleration was increased along with the increasing angle of decli\ulcornernation. When the test machine was operated in high speed, the difference between maximum moments and minimum ones became narrow. This varying magnitude of moments appeared on the moment oscillogram seems to be correlated to the oscillating acceleration and draft force. 10. From the analysis of variance, it was found that those factors such as frequency, amplitude, and operating velocity significantly affected in the oscillating acceleration, the draft resistance, the torque, the moment, and the total power required. And interaction between frequency and amplitude affected in the oscillating acceleration. 11. Within the given situation of this study, the most preferable operating conditions of the test machine were 7 Hz in oscillating frequency, 0.54 m/sec in operating velocity, and 39.1 mm in oscillating amplitude of front and rear bullets. However, it is necessary to select the proper frequency and magnitude of oscillation depending on the soil properties of the field in which the mole drainer is practiced by use of a bal1nced type oscillating mole drainer. 12. It is recommended that a comparative study of the mole drainers would be performed in the near future using two separate balanced oscillating bullet with the one which is operated by oscillating the movable bullet in a single cylinder or other balanced type which may be single oscillating bullet with spring, damper or balancing weight, and that of thing. To expand the applicability of the balanced type oscillating mole drainer in practical use, it is suggested to develop a new mechanism which perform mole drain with vinyl pipe or filling material such as rice hull.

• Journal of the Korean Society of School Health
• /
• v.1 no.2
• /
• pp.118-135
• /
• 1988

This study is designed to analyze the problems of health education in schools and explore the ways of enhancing health education from a historical perspective. It also shed light on the managerial aspect of health education (including medical-check-up for students disease management. school feeding and the health education law and its organization) as well as its educational aspect (including curriculum, teaching & learning, and wishes of teachers). At the same time it attempted to present the ways of resolving the problems in health education as identified her. Its major findings are as follows; I. Colculsion and Summary 1. Despite the importance of health education, the area remains relatively undeveloped. Students spend a greater part of their time in schools. Hence the government should develop a keener awareness of the importance of health education and invest more in it to ensure a healthy, comfortable life for students. 2. At the moment the outcomes of medical-check-up for students, which constitutes the mainstay of health education, are used only as statistical data to report to the relevant authorities. Needless to say they should be used to help improve the wellbeing of students. Specifically, nurse-teachers and home-room teachers should share the outcomes of medical-check-up to help the students wit shortcomings in growth or development or other physical handicaps more clearly recognize their problems and correct them if possible. 3. In the area of disease management, 62.6, 30.3 and 23.0 percent of primary, middle, and highschool students, respectively, were found to suffer from dental ailments. By contrast 2.2, 7.8, and 11.5 percent of primary, middle and highschool students suffered from visual disorders. The incidence of dental ailments decreases while that of visual impairments increases as students grow up. This signifies that students are under tremendous physical strain in their efforts to be admitted by schools of higher grade. Accordingly the relevant authorities should revise the current admission system as well as improve lighting system in classrooms. 4. Budget restraints have often been cited as a major bottleneck to the expansion of school feeding. Nevertheless it should be extended at least, to all primary schools even at the expense of parents to ensure the sound growth of children by improving their diet. 5. The existing health education law should be revised in such a way as to better meet the needs of schools. Also the manpower for health education should be strengthened. 6. Proper curriculum is essential to the effective implementation of health education. Hence it is necessary to remove those parts in the current health education curriculum that overlaps with other subjects. It is also necessary to make health education a compulsory course in teachers' college at the same time the teachers in charge of health education should be given an in-service training. 7. Currently health education is being taught as part of physical education, science, home economics or other courses. However these subjects tend to be overshadowed by English, mathematics, and other subjects which carry heavier weight in admission test. It is necessary among other things, to develop an educational plan specifying the course hours and teaching materials. 8. Health education is carried out by nurse-teachers or home-room teachers. In connection with health education, they expressed the hope that health education will be normalized with newly-developed teaching material, expanded opportunity for in-service training and increased budget, facilities and supply of manpower. These are the mainpoints that the decision-makers should take into account in the formation of future policy for health education. II. Recommendations for the Improvement of Health Education 1. Regular medical check-up for students, which now is the mainstay of health education, should be used as educational data in an appropriate manner. For instance the records of medical check-up could be transferred between schools. 2. School feeding should be expanded at least in primary schools at the expense of the government or even parents. It will help improve the physical wellbeing of youths and the diet for the people. 3. At the moment the health education law is only nominal. Hence the law should be revised in such a way as to ensure the physical wellbeing of students and faculty. 4. Health education should be made a compulsory course in teachers' college. Also the teachers in service should be offered training in health education. 5. The curriculum of health education should be revised. Also the course hours should be extended or readjusted to better meet the needs of students. 6. In the meantime the course hours should be strictly observed, while educational materials should be revised in no time. 7. The government should expand its investment in facilities, budget and personnel for health education in schools at all levels.

• Restorative Dentistry and Endodontics
• /
• v.34 no.4
• /
• pp.333-339
• /
• 2009

This study was done to determine if there is any difference in microleakage between experimental composite resins, in which various proportions of three component photoinitiators (Camphoroquinone, OPPI, Amine) were included. Four kinds of experimental composite resin were made by mixing 3.2% silanated barium glass (78 wt.%, average size; 1 ${\mu}m$) with each monomer system including variously proportioned photoinitiator systems used for photoinitiating BisGMA/BisEMA/TEGDMA monomer blend (37.5:37.5:25 wt.%). The weight percentage of each component were as follows (in sequence Camphoroquinone, OPPI, Amine): Group A - 0.5%, 0%, 1% / Group B - 2%, 0.2%, 2% / Group C - 0.2%, 1%, 0.2% / Group D - 1%, 1%, 2%. Each composite resin was used as a filling material for round class V cavities (diameter: 2/3 of mesiodistal width; depth: 1.5 mm) made on extracted human premolars and they were polymerized using curing light unit (XL 2500, 3M ESPE) for 40 s with an intensity of 600 mW/$cm^2$. Teeth were thermocycled fivehundred times between $50^{\circ}C$and $550^{\circ}C$for 30s at each temperature. Electrical conductivity (${\mu}A$) was recorded two times (just after thermocycling and after three-month storage in saline solution) by electrochemical method. Microleakage scores of each group according to evaluation time were as follows [Group: at first record / at second record; unit (${\mu}A$)]: A: 3.80 (0.69) / 13.22 (4.48), B: 3.42 (1.33) / 18.84 (5.53), C: 4.18 (2.55) / 28.08 (7.75), D: 4.12 (1.86) / 7.41 (3.41). Just after thermocycling, there was no difference in microleakage between groups, however, group C showed the largest score after three-month storage. Although there seems to be no difference in microleakage between groups just after thermocycling, composite resin with highly concentrated initiation system or classical design (Camphoroquinone and Amine system) would be more desirable for minimizing microleakage after three-month storage.

• Composites Research
• /
• v.36 no.1
• /
• pp.1-15
• /
• 2023

Demand for energy consumption reduction is increasing according to the development expectations of future mobility. Lightweight structural materials are known as a method to reduce greenhouse gas emissions and improve energy efficiency. In particular, fiber reinforced polymer composite (FRP) is attracting attention as a material that can replace existing metal alloys due to its excellent mechanical properties and light weight. In this paper, industrial applications and research trends of carbon fiber reinforced composites (CFRP, carbon FRP) and self-reinforced composites (SRC) were reviewed based on the reinforcement, polymer matrix, and manufacturing process. In order to overcome the expensive process cost and long manufacturing time of the epoxy resin-based autoclave method, which is mainly used in the aircraft field, mass production of CFRP-applied electric vehicles has been reported using a high-pressure resin transfer molding process including fast-curing epoxy. In addition, thermoplastic resin-based CFRP and interface enhancement methods to solve the recycling issue of carbon fiber composites were reviewed in terms of materials and processes. To form a perfect matrix-reinforcement interface, which is known as the major factor inducing the excellent mechanical properties of FRP, studies on SRC impregnated with the same matrix in polymer fibers have been reported. The physical and mechanical properties of SRC based on various thermoplastic polymers were reviewed in terms of polymer orientation and composite structure. In addition, a copolymer matrix strategy for extending the processing window of highly drawn polypropylene fiber-based SRC was discussed. The application of CFRP and SRC as lightweight structural materials can provide potential options for improving the energy efficiency of future mobility.

• Journal of Practical Engineering Education
• /
• v.15 no.1
• /
• pp.119-126
• /
• 2023

Today, in order to improve fuel efficiency and dynamic behavior of automobiles, an era of light weight and simplification of automobile parts is being formed. In order to simplify and design and manufacture the shape of the product, various components are integrated. For example, in order to commercialize three products into one product, product processing is occurring to a very narrow area. In the case of existing parts, precision die casting or casting production is used for processing convenience, and the multi-piece method requires a lot of processes and reduces the precision and strength of the parts. It is very advantageous to manufacture integrally to simplify the processing air and secure the strength of the parts, but if a deep and narrow pocket part needs to be processed, it cannot be processed with the equipment's own spindle. To solve a problem, research on cutting processing is being actively conducted, and multi-axis composite processing technology not only solves this problem. It has many advantages, such as being able to cut into composite shapes that have been difficult to flexibly cut through various processes with one machine tool so far. However, the reality is that expensive equipment increases manufacturing costs and lacks engineers who can operate the machine. In the five-axis cutting processing machine, when producing products with deep and narrow sections, the cycle time increases in product production due to the indirectness of tools, and many problems occur in processing. Therefore, dedicated machine tools and multi-axis composite machines should be used. Alternatively, an angle spindle may be used as a special tool capable of multi-axis composite machining of five or more axes in a three-axis machining center. Various and continuous studies are needed in areas such as processing vibration absorption, low heat generation and operational stability, excellent dimensional stability, and strength securing by using the angle spindle.

• Journal of the East Asian Society of Dietary Life
• /
• v.19 no.5
• /
• pp.703-712
• /
• 2009

The principal objective of this study was to supply basic material determine basic information regarding effective health promotion regimens for elderly women via a comparative survey of health status by aging age between elderly women (=70 y) and college women. The subject groups of elderly women (=70 y) and college women were selected and surveyed from March to October, 2008, in the Seoul area. The average age of the elderly women assessed in this study was $78.64{\pm}7.30$, the average height was $147.07{\pm}5.72$ cm, and the average weight was $50.47{\pm}7.44$ kg. As compared with college women, a higher percentage of elderly women ate breakfast regularly, but the elderly women also experienced difficulties in chewing due to dentures, and therefore ate their meals with large quantities of liquids, and usually ate their meals within 10 minutes. The majority of elderly women suffered from at least one disease, and the most common symptom reported was hypertension (25%). 52.2% of elderly women and 47.8% of college women reported that they exercised 1~2 times per week. They reported that their favorite exercise was light exercise, such as jogging and athletics (73.1%). As compared with college women, the smoking rate was lower among elderly women, but some of the elderly women were long-time smokers or alcoholics. The differences in red blood cells counts, Hb, hematocrit, and MCV of the between elderly women and college women were significant. In addition, but the MCH and MCHC were higher in elderly women compared with college women and the total cholesterol of elderly woman ($175.62{\pm}38.89$ mg/dL) was significantly lower compared with college woman ($186.13{\pm}28.19$ mg/dL). TG ($127.89{\pm}51.25$ mg/dL) and LDL-cholesterol ($120.51{\pm}32.88$ mg/dL) of elderly woman were significantly higher than TG ($79.71{\pm}40.9$ 6mg/dL) and LDL-cholesterol($103.78{\pm}22.94$ mg/dL) of college woman (p<0.05). The levels of HDL-cholesterol ($58.78{\pm}12.90$ mg/dL) in the college women was significantly higher than the HDLcholesterol levels ($48.17{\pm}13.79$ mg/dL) of the elderly women (p<0.05). Serum vitamin C levels in elderly women were significantly higher than those of college women (p<0.05), whereas no significant difference was detected between the two groups. Consequently, it can be concluded that the appropriate education programs for dietary habits and health promotion are necessary for a healthier life. Additionally, it is necessary for individuals to precisely determine precisely their own health status, and develop appropriate dietary programs for themselves.