• Science of Emotion and Sensibility
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• v.14 no.3
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• pp.459-466
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• 2011

Sleep diseases such as snoring and sleep apnea are physically, mentally harmful and results serious health problems. Snoring, known as breathing noise, is caused by coupled oscillation of the airway when the air passes through the trachea, and sleep apnea is caused by upper airway blockage. In order to solve these problems, many attempts have been made to detect the snoring during sleep and alleviate it. In this study, a new sensing system and analysis algorithm were developed in order to detect snoring sounds correctly under various sleep environments. Two polyvinylidene fluoride (PVDF) vibration sensors were used inside the pillow. The first PVDF sensor detects vibration transmitted through skull caused by snoring. And the second PVDF sensor detects both snoring sounds and ambient noises. The signals of two sensors were acquired through the designed analog circuits, and analyzed for snoring detection. Ten volunteers were participated for the experiment under five different conditions. Data from two PVDF sensors were processed by the established analysis algorithm, and snoring sounds were compared to noises. The results indicated that the energy of snoring is 70% bigger than that of ambient noise, which proves effectiveness of sensing system and analysis algorithm. Further study would be continued for more wide clinical studies with various environment noises. Based on this study, development of anti-snore pillow and sleep monitoring system for comfort sleep could be developed.

• KIPS Transactions on Software and Data Engineering
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• v.8 no.12
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• pp.507-516
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• 2019

Costs invested in road maintenance and road development are on the rise. However, due to accidents such as portholes and ground subsidence, the risks to the drivers' safety and the material damage caused by accidents are also increasing. Following this trend, we have developed a system that determines road damage, according to the magnitude of vibration generated without directly intervening the driver when driving. In this paper, we implemented the system using a remote control car (RC car) simulator due to the limitation of the environment in which the actual vehicle is not available in the process of developing the system. In addition, we attached a vibration sensor and GPS sensor to the body of the RC car simulator to measure the vibration value and location information generated by the movement of the vehicle in real-time while driving, and transmitting the corresponding data to the server. In this way, we implemented a system that allows external users to check the damage of roads and the maintenance of the repaired roads based on data more easily than the existing systems. By using this system, we can perform early prediction of road breakage and pattern prediction based on the data. Further, for the RC car simulator, commercialization will be possible by combining it with business in other fields that require flatness.

• Journal of Environmental Science International
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• v.26 no.2
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• pp.231-238
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• 2017

Rapid industrial development has led to a serious problem of pollution in the industrial sector. With the increasing social need for environmental protection, research on air pollution prevention equipment for reducing pollutants in industrial processes is actively being undertaken. The deterioration of existent, installed facilities, their increased emission rates, and the strengthening of the effluent quality standards make complying with permissible emission standards difficult. In fact, installing new electric precipitators or complementing existent facilities is inevitable. The expansion and complementation of the installed electrical precipitators have led to improvements in dust collection efficiency, shorter working times, and lower costs. Because of its easy installation and simple manufacturing process, the production method with the discharge electrode of an electric precipitator is widely used. The following conclusions were reached by classifying discharge electrodes into four types based on the production method and mutually comparing them by their dust collection efficiency. None of the four types used in this study were damaged by impact. However, we were able to confirm some strain from the compression sites of both type A and type B. Both type B and type C are expected to have greater dust collection efficiencies than the other models due to their large vibration transmissibility. Moreover, the high vibrational energy is expected to cause rapping damage during its operation. Particularly, in the case of type B, some of the strain was found at the end of the compression site. The coupling schemes of both type C and type D are out of vibration transmissibility. On the other hand, the ability to maintain straightness and solidity of the side is regarded as outstanding and stable. Type D has outstanding on-site workability, considering the presence of locking, structural stability, and work conditions. From these experiments, we determined that type C is the most ideal connection method of discharge electrode, considering its construction period of renovation. Type C is inferior to type D with regard to on-site workability. However, type C has outstanding dedusting transmission with regard to the straightness, solidity maintenance, and vibration of shearing stress.

• Advances in nano research
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• v.10 no.2
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• pp.115-128
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• 2021

In this article, free vibration behavior of electro-magneto-thermo sandwich Timoshenko beam made of porous core and Graphene Platelet Reinforced Composite (GPLRC) in a thermal environment is investigated. The governing equations of motion are derived by using the modified strain gradient theory for micro structures and Hamilton's principle. The magneto electro are under linear function along the thickness that contains magnetic and electric constant potentials and a cosine function. The effects of material length scale parameters, temperature change, various distributions of porous, different distributions of graphene platelets and thickness ratio on the natural frequency of Timoshenko beam are analyzed. The results show that an increase in aspect ratio, the temperature change, and the thickness of GPL leads to reduce the natural frequency; while vice versa for porous coefficient, volume fractions and length of GPL. Moreover, the effect of different size-dependent theories such as CT, MCST and MSGT on the natural frequency is investigated. It reveals that MSGT and CT have most and lowest values of natural frequency, respectively, because MSGT leads to increase the stiffness of micro Timoshenko sandwich beam by considering three material length scale parameters. It is seen that by increasing porosity coefficient, the natural frequency increases because both stiffness and mass matrices decreases, but the effect of reduction of mass matrix is more than stiffness matrix. Considering the piezo magneto-electric layers lead to enhance the stiffness of a micro beam, thus the natural frequency increases. It can be seen that with increasing of the value of WGPL, the stiffness of microbeam increases. As a result, the value of natural frequency enhances. It is shown that in hc/h = 0.7, the natural frequency for WGPL = 0.05 is 8% and 14% less than its for WGPL = 0.06 and WGPL = 0.07, respectively. The results show that with an increment in the length and width of GPLs, the natural frequency increases because the stiffness of micro structures enhances and vice versa for thickness of GPLs. It can be seen that the natural frequency for aGPL = 25 ㎛ and hc/h = 0.6 is 0.3% and 1% more than the one for aGPL = 5 ㎛ and aGPL = 1 ㎛, respectively.

• Journal of Environmental Impact Assessment
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• v.4 no.1
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• pp.25-35
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• 1995

The objective of the study is to produce preferential impact assessment factors for Environmental Impact Assessment by considering regional features and public participation in the initial stages of EIA. In order to produce preferential impact assessment factors, the study was carried out through theoretical research and a survey of public awareness as a ways to reflect public participation based on theoretical research. The survey of public awareness was conducted in the form of an interview to review the impact which the construction of atomic power plants at Hyo-am village, Jang-an, Kyungsang Province and Bi-hak village, Suhsang-myon, Ulsan-Kun will have on the surrounding environment: to reflect public participation on deciding preferential assessment: and to determine the extent of alternatives of the proposed project. As the result of the study, the following were identified as preferential assessment factors in the settlement and surrounding areas cultivation marine products, change of temperature of seawater due to flow of warm water, land use(negative), noise vibration during construction, existing plants, erosion accumulation, influx of manpower for construction(negative), recreation landscaping during construction and operation, change in flow of transportation during construction, the quality of seawater during construction and operation were produced as preferential assessment factors in both settlement area and neighboring areas. In the settlement area, the educational environment(negative & positive) and positive aspects of the influx of manpower for construction were also identified as preferential assessment factors.

• Journal of Environmental Impact Assessment
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• v.4 no.3
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• pp.15-26
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• 1995

The objective of the study is to produce preferential impact assessment factors for Environmental Impact Assessment by considering regional features and public participation in the initial stages of EIA. In order to produce preferential impact assessment factor, the study was carried out through theoretical research and a survey of public awareness as way to reflect public participation based on theoretical research. The survey of public awareness was conducted in the form of an interview to review the impact which the construction of atomic power plants at Hyo-am village, Jang-an, Kyungsang Province and Bi-hak village, Suhsang-myon, Ulsan-Kun will have on the surrounding environment : to reflect public participation on deciding preferential assessment: and to determine the extent of alternatives of the proposed project. As the result of the study, the followings were identified as preferential assessment factors in the displacing settlement and surrounding areas: cultivation marine products, change of temperature of seawater due to flow of warm water, land use (negative), noise vibration during construction, existing vegetations, erosion sedimentation, influx of manpower for construction(negative), recreation landscaping during construction and operation, change in flow of transportation during construction, the quality of seawater during construction and operation were produced as preferential assessment factors in both displacing area and neighboring areas. In the displacing settlement area, the educational environment(negative & positive) and positive aspects of the influx of manpower for construction were also identified as preferential assessment factors.

• IEMEK Journal of Embedded Systems and Applications
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• v.10 no.4
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• pp.189-198
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• 2015

Most IoT-related approaches have tried to establish the relation by connecting the network between things. The proposed research will present how the pervasive interaction of eco-system formed by touching the objects between humans and things can be recognized on purpose. By collecting and sharing the detected patterns among all kinds of things, we can construct the environment which enables individualized interactions of different objects. To perform the aforementioned, we are going to utilize technical procedures such as event-driven signal processing, pattern matching for signal recognition, and hardware in the loop simulation. We will also aim to implement the prototype of sensor processor based on Arduino MCU, which can be integrated with system using Arduino-Matlab/Simulink hybrid-interoperation environment. In the experiment, we use piezo transducer to detect the vibration or vibrates the surface using acoustic wave, which has specific frequency spectrum and individualized signal shape in terms of time axis. The signal distortion in time and frequency domain is recorded into memory tracer within sensor processor to extract the meaningful pattern by comparing the stored with lookup table(LUT). In this paper, we will contribute the initial prototypes for the acoustic touch processor by using off-the-shelf MCU and the integrated framework based on Matlab/Simulink model to provide the individualization of the touch-sensing for the user on purpose.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.1
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• pp.83-90
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• 2015

The car ferry operating between the mainland and the island plays an important role on transportation of goods and passengers. Therefore, the improvement of efficiency and safety as well as economic factor are importantly considered in the development process of car ferry. Double-ended car ferry is already popularized because of its economic feasibility and convenience for passenger in Europe and developed countries, and the demand is booming in domestic. In this paper, dynamic characteristics of propeller shaft and strength in double-ended car ferry are analyzed using campbell diagram and modal analysis. Based on the analysis of dynamic characteristics, resonant phenomenon and critical speed are stable when occurring the propeller shaft vibration due to forward and reverse propeller shaft working.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3D
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• pp.189-196
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• 2012

South Korea has achieved economic development rapidly during last 50 years. However, such fast economic development with industrialization caused skyrocketing increase of automobiles. The increase of automobile has created various problems in the cities. Problems like traffic congestion and accident, environmental pollution, noise, and vibration have done human beings, who are the principal agents harm. They have made citizens understand how important Green transportation, especially pedestrian movement, is. Recently, installation of pedestrian facilities has been expanded. If walking facilities are incorrectly designed, they can create inconvenience, danger and the state of emergency due to the lack of safety and pleasant feelings. However, since the importance of the facility designs has been neglected due to the lack of understanding, it is hard to improve the facilities. Therefore, we need various studies of walking simulation in order to research the designs for pedestrians' safety and convenience. The objective of this study is to analyze the pedestrians' behavior and movement in a transfer subway station. The improvement of walking environment was made after chasing and analyzing the pedestrians' movement which is investigated in the actual field using SimWalk simulation program.

• International Journal of Aeronautical and Space Sciences
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• v.17 no.1
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• pp.37-44
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• 2016

Optical fiber temperature sensing systems have incomparable advantages over traditional electrical-cable-based monitoring systems. However, the fiber optic interrogators and sensors have often been rejected as a temperature monitoring technology in real-world industrial applications because of high cost and over-specification. This study proposes a multiplexed fiber optic temperature monitoring sensor system using an economical Optical Time-Domain Reflectometer (OTDR) and Hard-Polymer-Clad Fiber (HPCF). HPCF is a special optical fiber in which a hard polymer cladding made of fluoroacrylate acts as a protective coating for an inner silica core. An OTDR is an optical loss measurement system that provides optical loss and event distance measurement in real time. A temperature sensor array with the five sensor nodes at 10-m interval was economically and quickly made by locally stripping HPCF clad through photo-thermal and photo-chemical processes using a continuous/pulse hybrid-mode laser. The exposed cores created backscattering signals in the OTDR attenuation trace. It was demonstrated that the backscattering peaks were independently sensitive to temperature variation. Since the 1.5-mm-long exposed core showed a 5-m-wide backscattering peak, the OTDR with a spatial resolution of 40 mm allows for making a sensor node at every 5 m for independent multiplexing. The performance of the sensor node included an operating range of up to $120^{\circ}C$, a resolution of $0.59^{\circ}C$, and a temperature sensitivity of $-0.00967dB/^{\circ}C$. Temperature monitoring errors in the environment tests stood at $0.76^{\circ}C$ and $0.36^{\circ}C$ under the temperature variation of the unstrapped fiber region and the vibration of the sensor node. The small sensitivities to the environment and the economic feasibility of the highly multiplexed HPCF temperature monitoring sensor system will be important advantages for use as system-integrated temperature sensors.