• Journal of Mechanical Science and Technology
• /
• 제14권10호
• /
• pp.1051-1060
• /
• 2000

Linear cyclic systems (LCS's) are a class of systems whose dynamic behavior changes cyclically. Such cyclic behavior is ubiquitous in systems with fundamentally repetitive motions (e. g. all rotating machinery). Yet, the knowledge of the noise and vibration transmission paths in LCS's is quite limited due to the time-varying nature of their dynamics. The first part of this two-part paper derives a generic expression that describes how the noise and/or vibration are transmitted between two (or multiple) locations in the LCS's. An analysis via the Fourier series and Fourier transform (FT) plays a major role in deriving this expression that turns out to be transfer function dependent upon the cycle position of the system. The cyclic nature of the LCS' transfer functions is shown to generate a series of amplitude modulated input signals whose carrier frequencies are harmonic multiples of the LCS' fundamental frequency. Applicability of signal processing techniques used in the linear time-invariant systems (LTIS's to the general LCSs is also discussed. Then, a criterion is proposed to determine how well a LCS can be approximated as a LTIS. In Part II, experimental validation of the analyses carried out in Part I is provided.

• International Journal of Knowledge Content Development & Technology
• /
• 제10권2호
• /
• pp.7-18
• /
• 2020

Communication is a process involving a group of interrelated elements working together for the purpose of information transfer. This paper discusses information retrieval as a communication process in the 21st century library. The difficulties associated with access to recorded knowledge through bibliographic control devices have been exacerbated by the interposition of additional encoding processes in the library and further decoding by the users. In addition, the innovation of internet/web has revolutionized the means and mode of communication process in the library by flooding information seekers with information and creating an illusion of self-sufficiency in many users. With these changes in information seeking behaviour and pattern, a cybernetic approach to information retrieval has emerged emphasizing adaptive control mechanisms and feedback processes. This paper argues that libraries should strive to continuously remain relevant by keeping abreast with changes in the behavior of information users. To this end, this paper proposes apomediatic-cybernetic model of communication, which illustrates information retrieval processes for the 21st-century library.

• 한국산업융합학회 논문집
• /
• 제3권4호
• /
• pp.293-296
• /
• 2000

We have accumulated the knowledge of the phenomena of external nature under the gravity fields of the earth, but have not the data of the natural phenomena under the high or low gravity fields. It is necessary to research the phenomena of the combustion, heat transfer and the behavior of the living animals under the high or low gravity fields. This paper introduces the mysterious universe in high and low gravity fields from the experimental study by Arai et al.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2002년도 봄 학술발표회 논문집
• /
• pp.27-34
• /
• 2002

In the case of reinforced concrete structures, the knowledge of load transfer in the long-term behavior analysis considering construction sequence is very important. Even though long-term behavior of concrete structures has been widely studied, the studies on the time-dependent axial force variation of shore have been scarce to date. In order to investigate the shore behaviors under actual construction conditions, a three-story test frame was constructed on a construction site. The entire construction schedule for the test frame was made to follow the schedule of an actual three-story frame. To analyze the data collected from the test frame, an analysis method based on the Winkler foundation model was developed. This analysis method accurately Predicts the time-dependent behavior of shore. The analysis results coincide well with those obtained by the Midas GENw program

• 대한기계학회논문집B
• /
• 제22권1호
• /
• pp.1-11
• /
• 1998

For the analysis of phonon heat transfer within short time and spatial scales, conventional macroscopic heat conduction equations with jump boundary conditions are tried and the results are compared to those of equation of phonon radiative transport(EPRT), which is one of microscopic transport equation. In transient state the macroscopic temperatures show far different behavior from EPRT. In steady state the hyperbolic temperatures with temperature jump at the wall from time relaxation model agrees well with EPRT temperatures. Since EPRT is also an approximate form of microscopic transport equation and there are no experimental results to verify the proposed model in this study, we can not conclude whether the approaching method from this study is valid or not. To the authors' knowledge, there are no experimental results available which can be used to test the validity of these models. Such an experiment, while difficult to conduct, would be invaluable.

• Journal of Mechanical Science and Technology
• /
• 제19권6호
• /
• pp.1378-1389
• /
• 2005

This work provides the fundamental knowledge of energy transport characteristics during very short-pulse laser heating of semiconductors from a microscopic viewpoint. Based on the self-consistent hydrodynamic equations, in-situ interactions between carriers, optical phonons, and acoustic phonons are simulated to figure out energy transport mechanism during ultrafast pulse laser heating of a silicon substrate through the detailed information on the time and spatial evolutions of each temperature for carriers, longitudinal optical (LO) phonons, acoustic phonons. It is found that nonequilibrium between LO phonons and acoustic phonons should be considered for ultrafast pulse laser heating problem, two-peak structures become apparently present for the subpicosecond pulses because of the Auger heating. A substantial increase in carrier temperature is observed for lasers with a few picosecond pulse duration, whereas the temperature rise of acoustic and phonon temperatures is relatively small with decreasing laser pulse widths. A slight lagging behavior is observed due to the differences in relaxation times and heat capacities between two different phonons. Moreover, the laser fluence has a significant effect on the decaying rate of the Auger recombination.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.42.3-42
• /
• 2001

A human is an expert in manipulation. We have acquired skills to perform dexterous operations based upon knowledge and experience attained over a long period of time. It is important in robotics to understand these human skills, and utilize them to bring about better robot control and operation It is hoped that the neurocontroller can be trained and organized by simply presenting human teaching data, which implicate human intention, strategy and expertise. In designing a neurocontroller, we must determine the size of neurocontroller. Improper size may not only incur difficulties in training neural nets, e.g. no convergence, but also cause instability and erratic behavior in machines. Therefore, it is necessary to determine the proper size of neurocontroller for human control transfer. In this paper, a new pruning method is developed, based on the penalty-term methods. This method makes ...

• Nutrition Research and Practice
• /
• 제13권6호
• /
• pp.535-542
• /
• 2019

BACKGROUND/OBJECTIVES: Proper nutrition intake during pregnancy and lactation is very important to both mothers and babies. Pregnant women should maintain proper nutritional status to restore decreased physical strength due to pregnancy and childbirth and produce breastmilk for the growth and development of the baby. Recently, the number of Chinese people living in Korea has increased as the exchange between Korea and China becomes active. It is important to provide proper nutrition education for pregnant women of both countries considering cultural differences. SUBJECTS/METHODS: The subjects of this study were postpartum women in Gyeonggi, South Korea and Jinhua, China. The subjects were 20-45 years old less than six months after childbirth. A survey, using self-administered questionnaires, was conducted from October 2018 to January 2019. For data analysis, 221 Korean postpartum women (KPW) and 221 Chinese postpartum women (CPW) questionnaires were used. RESULTS: KPW had significantly higher nutritional knowledge score and dietary attitude score than CPW (P < 0.001). However, overall score for dietary habits was significantly higher in CPW compared to KPW (P < 0.001). In KPW, nutritional knowledge (P < 0.01) and dietary attitude (P < 0.001) had significantly positive correlations with dietary habits. The proportions of KPW and CPW who answered that they had experience of nutrition education were 28.5% and 80.1% (P < 0.001). The score for dietary habits was lower as the hours for watching TV and using mobile phone became longer in postpartum women of both countries, with significant differences in KPW (P < 0.001) and CPW (P < 0.05). In KPW, the score for dietary habits in postpartum women with exercise experience was significantly higher than that in postpartum women without exercise experience (P < 0.001). CONCLUSIONS: More pregnancy-related nutrition education should be provided and various and effective nutrition education programs, which not only transfer information but can be practiced in the actual life, should be developed.

• International Journal of Computer Science & Network Security
• /
• 제21권8호
• /
• pp.353-359
• /
• 2021

Information technology and the need for timely and effective communication during the Covid-19 have made most governments adopt technological approaches to provide their services. E-government services have been adopted by most governments especially in developed countries to quickly and effectively share information. This study discusses the reasons why governments in the Gulf region should develop a new model for information technology knowledge management practices. To achieve this, the author identified possible benefits of adopting information technology knowledge management practices and why most governments in the Gulf find it hard to adopt them. Knowledge management allows for learning, transfer as well as sharing of information between government organizations and citizens and with the development of technology, the effectiveness of electronic services can easily be achieved. Also, effective adoption of information technology can improve knowledge management with the help of techniques that enhance capture, storage, retrieval as well as sharing of information. The author used systematic literature review to select 28 journals and articles published post 2019. IEEE, Google Scholar and Science Direct were used to select potential studies from which 722 journals and articles were selected. Through screening and eligibility assessment, 21 articles were retained while the back and forward search had 7 more articles which were also included in the study. Using information gathered from these articles and journals a new conceptual model was developed to help improve information technology knowledge management for governments in the Gulf region to effectively deliver e-services during Covid-19. This model was developed based on the process of KM, Theory of Planned Behavior and Unified Theory of Acceptance and Use of Technology. Based on the developed model. From UTAUT model, performance expectancy, effort expectancy as well as social influence had a great impact.

• 한국콘텐츠학회논문지
• /
• 제16권10호
• /
• pp.255-266
• /
• 2016

치위생학과 학부모의 구강건강 대한 지식과 인식 및 태도는 치위생학과에 재학 중인 자녀를 통하여 상호영향을 주고받기 때문에 학교에서 실천하는 구강보건교육 시 학생들에게 단순한 지식을 전달하기보다는 태도 및 행동의 변화까지 유발시킬 수 있는 구강보건교육이 필요한 실정이다. 이에 본 연구는 치위생학과에 재학 중인 자녀를 둔 치위생학과 학부모의 구강건강지식 및 인식의 차이를 비교분석하고자 수행했다. 데이터 수집은 구글앱을 통한 설문지를 자가기입방식으로 확보하였으며, 분석은 SPSS Ver. 19.0을 사용하였다. 연구대상은 전국 치위생학과 저학년(1학년)과 고학년(4학년) 학부모로 총 200부를 최종 분석 하였다. 분석 결과, 자녀가 치위생학과에 재학함에 따른 영향은 고학년일수록 학부모에게 미치는 영향이 통계적으로 높았다. 자녀의 학년에 따른 학부모의 구강건강 지식 평균은 고학년의 학부모가 저학년의 학부모보다 구강건강 지식정도 및 인식정도가 더 높은 것으로 나타났다. 자녀를 통한 교육 여부와 영향 모두 고학년 학부모에서 저학년 학부모보다 통계적으로 유의하게 높게 나타났다. 따라서 자녀의 학년이 고학년일수록 그들의 지식과 습관화된 행동이 학부모의 구강건강지식 및 인식에 영향을 미친다는 것을 알 수 있다.