• Journal of Korean Clinical Health Science
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• v.5 no.3
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• pp.943-952
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• 2017

Purpose: The purpose of this study was to investigate the effects of dental hygiene and students' academic achievement and their quality of life. Methods: A self administered questionnaire was used for third and fourth year dental hygienists which consisted of 423 female students. The data was analyzed using SPSS ver.19.0. Results: The results of this study are as follows(p<0.01). First, the effect of academic achievement on quality of life was found to affect an ideal life, life satisfaction and the quality of maintaining a happy life (p<0.05). The correlations between objective academic achievements and the quality of life of the subjects were correlated in all items (p<0.01, p<0.05). Conclusion: To summarize the above results, in order to improve the quality of life for dental hygienists and students, it is necessary to take various measures in order for students to maintain a sense of pride in their various departments and to be able to concentrate on their respective studies.

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.50 no.5
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• pp.247-254
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• 2001

Silent period(SP) is transient stops of muscle activity that are induced by mechanical or electrical stimulus and the duration of silent period is a important parameter that have been associated with symptoms of masticatory dysfunction. Muscle fatigue is induced by sustained muscular contractions. It is associated with the external manifestations as the inability to maintain a desired force output, muscular tremor, and localized pain. Muscle fatigue is a parameter that have been measured or monitored the deterioration of a performance of muscles. On the study of relationship between SP and masticatory muscle fatigue, Nagasawa suggested that SP increases up to 3 min. from the beginning of clenching when the subjects performed sustained contractions at 50% maximum clenching level. In this paper, in order to evaluate a relationship between SP and muscle fatigue, 10 SPs per 1 minute are measured at 10%, 20%, 50% maximum clenching level. We used the median frequency in order to quantify the degree of muscle fatigue. However, the results shows that the duration of silent period was not significantly affected by differing levels of muscle fatigue. Therefore, we suggest that the SP is not increased or decreased as the results of muscle fatigue, also the origin of the SP generation mechanism is discussed.

• Journal of Power System Engineering
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• v.5 no.3
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• pp.64-72
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• 2001

This paper describes an optimal design technology in a segment type vertical guide bearing for vertical rotating machinery. Segment type vertical guide bearings have widely used for vertical rotating machinery, however bearing problems, such as excessive vibration and temperature rise, frequently take place in the actual machine. Such excessive vibration magnitude and/or abnormal bearing metal temperature rise result in serious damage and economic losses. Thus the segment type vertical guide bearing should be designed to get optimal characteristics in order to maintain stable operation without bearing failure due to abnormal vibration and/or abnormal bearing metal temperature. The preload ratio is the most important parameter in designing the segment type vertical guide bearing. Because adjustment of the bearing preload by changing the bearing clearance could easily control both the bearing stiffness and the cooling effect. In the paper, the influence of the preload effects on the bearing metal temperature and the bearing stiffness has been investigated both theoretically and experimentally in order to find out an optimum preload ratio. Results show that the segment type vertical guide bearing has an optimum preload ratio at which the bearing stiffness reaches a masimum value while the bearing metal temperature is minimized.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1149-1158
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• 2002

An improved hydrostatic unit(HSU) model is proposed by considering the flow loss in order to analyze the power flow characteristics of a hydromechanical transmission(HMT) and a network analysis algorithm is presented to determine the torque and speed of each element of the HMT. To calculate the torque and flow loss of a pump and a motor in HSU, an effort and flow concept is introduced, which can be used to establish a torque and speed matrix in the network analysis. It is found from the network analysis that magnitude of the HSU stroke increases to maintain the same output speed in order to compensate the flow Boss in the HSU and the efficiency of the HMT shows the lowest value in the 1st speed since the HSU has the largest flow loss in the 1st speed and the flow loss decreases as the speed ratio upshifts.

• Journal of the Korean Society for Precision Engineering
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• v.23 no.3 s.180
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• pp.22-31
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• 2006

This paper introduces an approach to an ontology-based knowledge framework for product life cycle management (PLM). Participants in a product life cycle want to share comprehensive product knowledge without any ambiguity and heterogeneity. However, previous knowledge management approaches are limited in providing those aspects. Therefore, we suggest an ontology-based knowledge framework including knowledge maps, axioms and specific knowledge far domain. The bottom level, the axiom, specifies the semantics of concepts and relations of knowledge so that ambiguity of the semantics can be alleviated. The middle level is a product development knowledge map; it defines the concepts and the relations of the product domain common knowledge and guides engineers to process their engineering decisions. The middle level is then classified further into more detailed levels, such as generic product level, specific product level, product version level, and product item level for PLM. The top level is specialized knowledge fer a specific domain that gives the solution of a specific task or problem. It is classified into three knowledge types: expert knowledge, engineering function knowledge, and data-analysis-based knowledge. This proposed framework is based on ontology to accommodate a comprehensive range of unambiguous knowledge for PLM and is represented with first-order logic to maintain a uniform representation.

• The KSFM Journal of Fluid Machinery
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• v.2 no.2 s.3
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• pp.64-73
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• 1999

The three-dimensional numerical study of a water jet pump was carried out to investigate the relationship between performance and the geometric variables of nozzle space, area ratio, and throat length. Because of the complex geometry, the multiblock technique was adopted for numerical analysis and a special treatment for transferring data from each of the block interfaces was implemented in order to maintain the conserved properties. To validate the present code, flow passing through a square duct with a 90-deg bend was computed, our results show good accordance with other experimental and computational results. The numerical simulation was done with the flow of the water jet pump having a 180-deg bend in order to calculate the performance at different operating conditions. The performance of the water jet pump can be improved by study of parameters which clarify the relations between the geometric variables and the flow characteristics of vortex strength and location.

• Korean Journal of Environmental Agriculture
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• v.14 no.3
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• pp.351-373
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• 1995

The objective of this paper is to present relevant information and data from domestic and foreign references and to propose legal standards on pesticide residues in order to mitigate the pesticide contamination in the water environment. Among 200 pesticide ingredients in use in Korea, items necessary for standard setting were selected and theoretical residue limits were computed. The results are summarized as follows. In advanced countries, drinking water standards are established on the basis of health index ADI and water intake, whereas standards for surface water are established temporarily on the basis of different parameters, inconsistent with different countries. Pesticide residue limits applicable in Korea were proposed for 24 pesticides in drinking water(health basis) and for 25 pesticides in surface water(ecotoxicological basis), as selected by risk priority. It was recommended to accumulate scientific data by persistent research efforts in order to maintain the justification of the pesticide residue limits in water and relevant research topics to be undertaken in future were proposed.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1255-1262
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• 2009

The present study explained the phenomenon that low frequency oscillation is synchronized with discrete data obtained from a wide area system, and a sync search method. When a disturbance occurs in an power system, various controllers operate in order to maintain synchronization. If the system's damping is poor, low frequency oscillations continue for a long time and the oscillations are synchronized with one another at specific frequency. The present study estimated dominant modes, magnitude and phase of signals by applying parameter estimation methods to discrete signals obtained from an power system, and performed sync search among wide area signals by comparing the estimated data. Sync search was performed by selecting those with the same frequency and damping constant from dominant oscillation modes included in a large number of signals, and comparing their magnitude and phase. In addition, we defined sync indexes in order to indicate the degree of sync between areas in a wide area system. Furthermore, we proposed a wide area sync search method by normalizing mode magnitude in discrete data obtained from critical generator of the wide area. By applying the sync search method and sync indexes proposed in this study to two area systems, we demonstrated that sync scanning can be performed for discrete signals obtained from power systems.

• IE interfaces
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• v.12 no.4
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• pp.514-531
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• 1999

This paper deals with the design of the manufacturing information system which is able to respond rapidly to various requirements of customers in make-to-order environment. The system is required to maintain a consistent flow of information from the start to the end. For this, we adopt an approach based on Information Engineering (IE) methodology, which consists of four stages: planning, analysis, basic design, and detail design. The first is a planing stage which establishes a project goal and organizes a project team. In the second stage, current activities are analyzed and problems are defined. The basic design is accomplished in the third stage, where a project scope is defined and an overall feature of the new system is presented. And then, in the last stage, the operation plan of each subsystem is drawn up in detail and all subsystems are integrated. This study applies the methodology to the case of H company and focuses on designing forms which are easy-to-write, easy-to-understand, and field-oriented. These forms are interrelated and can be used for systematic analysis and design. By applying them to the system design, we have obtained effect of reducing cost and time.

• Journal of Korean Medical classics
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• v.30 no.4
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• pp.123-153
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• 2017

Objective : This paper attempts to analyze the curriculum of the modern Korean Medicine's higher education institutions and study their significance. Rather than conducting an in-depth pedagogical research, the paper attempts to summarize and provide a simple analysis on the subject matter due to the lack of the historical evidence of modern Korean Medicine. Method : General theses and academic papers along with daily publications before the Japanese colonial era, materials owned by Kyunghee University Korean Medicine History Museum, and history databases owned by the National Institute of Korean History and Kyujanggak were investigated Result : Upon studying the curriculum of Korean Medicine's higher education institutions, it could be concluded that the efforts to maintain the independence and professionalism of Korean Medicine in its relationship with the Western Medicine. It could also be discovered that the curriculum was improved through policy measures in order to raise the status of the practitioners and expand the scope of their practices. These higher education institutions has been continuously working to develop the Korean Medicine and raise the quality of curriculum, and their efforts were vital in the establishment of the Korean Medicine Doctor system. Conclusion : Systematic academic researches should be done on the curriculum of Korean Medicine's high education institutions in order to fulfill the objective of normalizing the Korean Medicine education and contributing to the growth of Korean Medicine.