• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.103-109
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• 2005

Airflow in the nasal cavity of a normal Korean adult is investigated experimentally by tomographic PIV measurement. Knowledge of airflow characteristics in nasal cavities is essential to understand the physiology and pathology aspects of nasal breathing. Several studies have utilized physical models of the healthy nasal cavity to investigate the relationship between nasal anatomy and airflow. All of these researches on nasal airflow are under the condition of constant flow-rate. In this study, nasal cavity flow with the physiological period is investigated by tomographic PIV, for the first time. A pumping system that can produce the periodic flow is created. Thanks to a new method for the model casting by a combination of the rapid prototyping and curing of clear silicone, a transparent rectangular box containing the complex nasal cavity can be made for PIV, The CBC PIV algorithm is used for analysis. Phase-averaged mean and RMS velocity distributions are obtained for inspirational and expiration nasal airflows. The comparison with the constant flow case is appreciated. There exist many flow patterns depending on each phase.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.4
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• pp.622-632
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• 1995

The present numerical study is aimed to investigate time-dependent characteristics of a two-dimensional lid-driven square cavity flow of three high Reynolds numbers, $7.5{\times}10^3$, $10^4$ and $3{\times}10^4$. A conservative convection term on irregular grids was adopted by renewing the MAC type difference schemes on regular grids. Relaxation of velocity and pressure is implemented by SOLA algorithm. In case of $Re=7.5{\times}10^3$, flow behavior converges to steady state after a transient period. But for $Re=10^4$, periodic unsteady sinusoidal fluctuation of local velocity and kinetic energy is found and continuous movements of small eddies in the secondary flow regions are also discovered. Random generation of eddies and their active migrating behavior are detected for $Re=3{\times}10^4$, resulting in complete unsteady and non-linear flow characteristics. And, an organized structure similar to a Moffat vortex is also observed from the time-mean flow patterns. Furthermore, a typoon-like vortex(TLV) appears intemittently and rotates along the separation regions and boundary layers.

• The Journal of the Acoustical Society of Korea
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• v.22 no.2
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• pp.104-112
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• 2003

The in-duct acoustical sources of fluid machines are often characterized by the source impedance and strength using the linear time-invariant model. However, negative resistances, which are physically unreasonable, have been found throughout various measurements of the source properties in IC-engines and compressors. In this paper, the effects of the time-varying nature of fluid machines on the source characteristics are studied analytically. For this purpose, the simple fluid machine consisting of a reciprocating piston and an exhaust is considered as representing a typical periodic, time-varying system and the equivalent circuits are analyzed. Simulated measurements using the analytic solutions show that the time-varying nature in the actual sources is one of the main causes of the negative source resistances. It is also found that, for the small magnitude of the time-varying component, the source radiates large acoustic power if the piston operates at twice the natural frequency of the static system. or integral submultiples of that rate.

• Journal of Multimedia Information System
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• v.6 no.4
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• pp.293-302
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• 2019

In the past, there was a theory that influenza wasn't transmitted directly from birds but was infected to humans via swains. Recently, molecular level research has progressed, and it was confirmed that the avian influenza virus can directly infected to human lung and intestinal epithelial cells. Three pandemicsin the past 100 years were also infected to humans directly from birds. In view of such scientific background, we are developing a method for screening sick birds by monitoring the physiological characteristics of birds in a contactless manner with sensors. Here, the movement of respiratory muscles and abdominal muscles under autonomic innervation was monitored using a magnet and Hall sensor sewn on the thoracic wall, and other multimedia devices. This paper presents and discusses the results of experiments involving continuous periodic noise discovered during flight experiments with a data logger mounted on a Japanese pheasant from 2012 to 2015. A brief summary is given as the below: 1. Magnet and Hall sensor sewn to the left and right chest walls, bipolar electrocardiograms between the thoracic walls, posterior thoracic air sac pressure, angular velocity sensors sewn on the back and hips, and optical reflection of LEDs (blue and green) from the skin of the hips allow observation of periodic vibrations(fasciculations) in the waves. No such analysis has been reported before. 2. These fasciculations are presumed to be derived from muscle to maintain and control air sac pressure. 3. Since each muscle fiber is spatially Gaussian distributed from the sympathetic nerve, the envelope is assumed to plot a Gaussian curve. 4. Since avian trunk muscles contract periodically at all time, we assume that the sympathetic nerve dominates in their control. 5. The technique of sewing a magnet to the thoracic wall and measuring the strength of the magnetic field with a Hall sensor can be applied to screen for early stage of avian influenza, with a sensor attached to the chicken enclosure.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.1
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• pp.38-46
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• 2011

The OPRoS (Open Platform for Robotic Service) framework provides uniform operating environment for service robots. As an OPRoS-based service robot has to support real-time as well as non-real-time applications, application of Windows NT kernel based operating system can be restrictive. On the other hand, various benefits such as rich library and device support and abundant developer pool can be enjoyed when service robots are built on Windows NT. The paper presents a user-mode component scheduler of OPRoS, which can provide near real-time scheduling service on Windows NT based on the restricted real-time features of Windows NT kernel. The component scheduler thread with the highest real-time priority in Windows NT system acquires CPU control. And then the component scheduler suspends and resumes each periodic component executors based on its priority and precedence dependency so that the component executors are scheduled in the preemptive manner. We show experiment analysis on the performance limitations of the proposed scheduling technique. The analysis and experimental results show that the proposed scheduler guarantees highly reliable timing down to the resolution of 10ms.

• Journal of the Korean Society of Costume
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• v.56 no.6 s.105
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• pp.1-15
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• 2006

The purpose of this study is to present a new viewpoint in look by closely examining fashion and look through the past, present, and future. Specifically, the concept of time is studied and fashion is considered based upon the concept of time, finally, looks in fashion related to time are analysed. For this study, the literature of retro, modern, contemporary, futuristic looks that express the past, present, and future, and the classic look, the popularity of which transcends the concept of time was considered focusing on 20th century women's fashion. Design characteristics of these looks were analyzed utilizing photographs of collection images. The results of the study are as follows: first, although the retro look of different periods regularly rotate and appear, they change and develop in new and various ways depending on the Periodic background of the time they appear in, and thus show simultaneously the cyclical and straight nature of time. Second, the modern look includes not only the moaning of time concept of the present, but also of interpreting anew the formal significance of modernism in the present. In other words, because it cyclically repeats the times of past modern periods, the look can be said to focus on the cyclical nature of time. Third, the contemporary look is a style that expresses current time most exactly as it exists, and it can be said to be the look in which current time is most vividly expressed. Fourth, the time concept in futuristic look is a subjective time that selectively accommodates and expresses the objective time of the future which has not yet come, and that can be the look's most important point. Last, the classic look possesses an objective value that transcends the concept of time, and it keeps returning, showing the cyclical nature of time. The closer this study came to the present, it could be seen that a look communicated more complex meanings, Influenced by periodic phases such as diversification, individualization, and eclecticism, and that while it could not be defined as any one look, various elements were expressed eclectically by being mixed and matched with each other, and it could utilize more natural forms, colors, and materials.

• Research in Community and Public Health Nursing
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• v.4 no.1
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• pp.14-24
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• 1993

The Purpose of this study was to explore the condition of periodic medical examination and the health care services of industries in order to offer some basic data on developing industrial nursing care. To achieve this goal a self - administered questionnaire (developed by the academic affairs of community health nursing) was provieded to the nurses in 56 industries from Dec. 10, 1992 to Jan. 20, 1993. The statistical computer package, SPSS, was used to manipulate the data along with T-test and ANOVA. The results were as follows : 1. General characteristics: The greater part of the industries were manufacturing company, and below 300 employees of industry were 55.4%. The shift system was mostly one shift(66.1%) and three shift(23.2%), and 50.0% them organized the Industrial Safety and Health Commitee. Average a number of employees was 631 person. 2. Periodic Medical Examination: Most of the workers were receiving periodic medical examination from the designated hospital (95.71%). From the about 12.89% were gone through a colse medical examination. In colse medical examination 58.41% were decided 'C' and 36.73% were decided 'D'. About 6.23% off those who had any clinical findings were work-time shortening(7.84%), work-transition(8.12%), recoverating at home. The majority of the workers receive the result of the periodic medical examination individually (78.5%). 3. Special medical examination: The rate of those who are receiving special medical examination were 76.82% and about 8.24% were decided 'C' and 1.23% were decided 'D' Those who had any health problems were receiving follow-up checking (9.10%) and medical treatment while working (15.04%). The health managers in the company can consult (85.7%) those who had any suspicious sign and symptoms of occupational disease. 4. Health care services: The average score of health care services were 17.57 point out of 28 point, and the score was lower in health assessment and environmental hygiene than medical diagnosis and health education. There were significant differences in environmental hygine (F=3.72, P=0.017), health care services(F=3.94, P=0.013) according to the size of the size of the industries The other's significancy is not shown by any type of industrial nurse. The level of health care services were higher in the wokers who had better health and showed no singificant differences(T=-0.73, P=0.470).

• 제어로봇시스템학회:학술대회논문집
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• 1997.10a
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• pp.309-312
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• 1997

The dynamic characteristics of a continuous MMA/MA free-radical solution copolymerization reactor were studied. A mathematical model was developed and kinetic parameters which had been estimated in the previous work were used. With this model, bifurcation diagrams were constructed with various parameters as the bifurcation parameter to predict the region of stable operating conditions and to enhance the controller performance. It was shown that the steady-state multiplicity existed over wide ranges of residence time and jacket inlet temperature. Periodic solution branches were found to emanated from Hopf bifurcation points. Under certain conditions isola was also observed, which would result in poor performance of feedback controllers.

• Architectural research
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• v.15 no.1
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• pp.25-33
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• 2013

The amount of construction waste increased to 176,447 ton/day in 2008 from 28,400 ton/day in 2000, a 6-fold increase in just 10 years. Such dramatic increase in the waste of concrete, asphalt concrete, wood and metals was due to demolition of old buildings as well as a great number of building redevelopment projects and hurried city industrialization. Many buildings targeted for demolition today were built in line with the government policy to provide affordable housing to citizens in the shortest time possible and consequently, said buildings underwent rapid deterioration and required periodic repairs and reconstruction. Based on the above, we predict that construction waste will continue to increase for the foreseeable future. In particular, due to limited availability of suitable space to construct apartments and residential buildings in the city, old buildings are being torn down to make space for new development, further increasing construction waste. In light of that, efforts to recycle as well as reduce generated waste are urgently required.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.197-198
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• 1998

We tested the capability of Pointwise Correlation Dimension(PD2), Approximate Entropy (ApEn) and LZ complexity, as alternative measures of a biological signal. For this purpose, we analyzed standard data and a healthy child's 24-hour heart rate variability. Our conclusion is as follows. First, PD2, ApEn and LZ complexity can be used for discerning chaotic attractor, white noise, and periodic signal. Second, these measures show different characteristics on day and night. Third, these measures can be used for detecting time-varying characteristics of biological signals.