• International Journal of Highway Engineering
• /
• v.20 no.3
• /
• pp.59-64
• /
• 2018

PURPOSES : We propose a parameter-setting-free harmony-search (PSF-HS) algorithm to determine the individual sound power levels of noise sources in the cases of industrial or road noise environment. METHODS :In terms of using methods, we use PSF-HS algorithm because the optimization parameters cannot be fixed through finding the global minimum. RESULTS:We found that the main advantage of the PSF-HS heuristic algorithm is its ability to find the best global solution of individual sound power levels through a nonlinear complex function, even though the parameters of the original harmony-search (HS) algorithm are not fixed. In an industrial and road environment, high noise exposure is harmful, and can cause nonauditory effects that endanger worker and passenger safety. This study proposes the PSF-HS algorithm for determining the PWL of an individual machine (or vehicle), which is a useful technique for industrial (or road) engineers to identify the dominant noise source in the workplace (or road field testing case). CONCLUSIONS : This study focuses on providing an efficient method to determine sound power levels (PWLs) and the dominant noise source while multiple machines (or vehicles) are operating, for comparison with the results of previous research. This paper can extend the state-of-the-art in a heuristic search algorithm to determine the individual PWLs of machines as well as loud machines (or vehicles), based on the parameter-setting-free harmony-search (PSF-HS) algorithm. This algorithm can be applied into determining the dominant noise sources of several vehicles in the cases of road cross sections and congested housing complex.

• Explosives and Blasting
• /
• v.30 no.1
• /
• pp.37-51
• /
• 2012

In this case of "Seongnam~Yeoju double-lanes railroad construction", there were safety facilities which were concerned about damages from vibration and noise. In the project design stage, the rock-splitter method was designed to prevent them. The electronic blasting was considered to improve construction speed and economic value as an alternative tunnelling method, complying with the site's vibration criteria(cowhouse : 0.09cm/sec, residence : 0.2cm/sec). In the environment evaluation report of the eDev, tunnel electronic blasting systems, the blasting pollutions can be managed by the electronic blasting method. The results were successfully conducted with high speed construction without any damages to adjacent facilities.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.9
• /
• pp.238-247
• /
• 2014

The milking robot system is very important to detect correctly the teats position in the moving condition of cow. Also, the robot manipulator must control tracking the teat cup to the detected teat position. The presented milking robot is designed using the one point laser sensor for teat position detection. The teats of cow are detected by the laser scanning unit and the manipulator has the function of 3 axes moving control unit. The presented teat detection method and the electrical driving manipulator have the advantages of a simple, low cost and very quiet. The designed manipulator is realized by the totally electrical motor and servo poison control algorithm with velocity PID compensation. The presented robot is realized using the teat detection unit, 4 teat cups, 3 axes robot arm, 6 servo motors and automatic milking control line. The designed robot is experimented in the cow farm and is satisfied with the designed performance specification for milking robot manipulator.

• Journal of Environmental Health Sciences
• /
• v.37 no.2
• /
• pp.94-101
• /
• 2011

Objectives: The purpose of this study is to evaluate the noise exposures of firefighters according to their time-dependent activity patterns. Methods: Personal exposure levels were measured for six days and nights using noise dosimeters; three days and nights for on-duty tasks, the other days and nights for off-duty activities. Results: The total amount of time spent in the workplace was 13,677 min (67%), outside areas 4,833 min (23%), in transit 1,002 min (5%), and other indoor area 807 min (4%) during a working period. However, during off-days they spent 10,858 min (76%) at home, 1,382 min (10%) outdoors, 1,225 min (9%) other indoors, and 493 min (3%) in transit. As a result of individual exposure levels, TWA did not exceed 90 dBA of the occupational exposure limit for the majority of the firefighters, whereas the levels of Lmax were 119 dBA, which were higher than the noise levels of firefighters in USA. Sometimes during dispatching the levels of Lpeak exceeded the ACGIH exposure standard (140 dBC). The Leq levels in transit were higher than the levels in home and other indoors even though the activity time is short. Conclusions: This paper characterized the noise exposure patterns of firefighters in Korea. We suggest that special noise sources, including sirens and speaker phones, should be readjusted to reduce noise exposure.

• Journal of Environmental Health Sciences
• /
• v.43 no.3
• /
• pp.214-222
• /
• 2017

Objectives: A hospital is a complex building that serves many different purposes. The indoor environment in a hospital plays a major role in patient well-being and the work efficiency of the hospital staff. This study was conducted to evaluate overall comfort in two major hospitals over the course of one year. Methods: Various indoor environmental conditions were measured in two general hospitals for one year (April 2014 to April 2015). Monitoring alternated between the hospitals at one month per respective monitoring session. The indoor air temperature, relative humidity (RH), mean radiant temperature and air velocity were measured in order to calculate the predicted mean vote (PMV). Carbon dioxide concentration, noise level and illumination level were concurrently measured and applied to the overall IEQ acceptance model for the hospitals (IEQh). Results: The IEQh at the two general hospitals was different at five spaces within a building. The IEQh for summer and winter were significantly different. Real-time IEQh demonstrated that indoor comfort was affected by the hospital's operating hours due to operation of the HVAC system. The percentage of indoor comfort in the hospitals was higher using PMV than IEQh. Conclusion: IEQh in the hospitals was different at locations with different purposes. Indoor comfort assessment using IEQh was stricter than with PMV. Additional research is needed in order to optimize the IEQh model.

• Aerospace Engineering and Technology
• /
• v.8 no.1
• /
• pp.32-41
• /
• 2009

In this study, scale-down design of full-scale Korean Utility Helicopter (KUH) main rotor blade has been investigated. The scaled model system were designed for the measurement of aerodynamic performance, tip vortex and noise source. For the purpose of considering the same aerodynamic loads, the Mach-scale method has been applied. The Mach-scaled model has the same tip Mach number, and it also has the same normalized frequencies. That is, the Mach-scaled model is analogous to full-scale model in the view point of aerodynamics and structural dynamics. Aerodynamic scale-down process could be completed just by adjusting scaling dimensions and increasing rotating speed. In the field of structural dynamics, design process could be finished by confirming the rotating frequencies of the designed blade with the stiffness and inertial properties distributions produced by sectional design. In this study, small-scaled blade sectional design were performed by applying domestic composite prepregs and structural dynamic characteristics of designed model has been investigated.

• The Journal of the Acoustical Society of Korea
• /
• v.19 no.8
• /
• pp.78-83
• /
• 2000

Passive sonar system is designed to classify the underwater targets by analyzing and comparing the various acoustic characteristics such as signal strength, bandwidth, number of tonals and relationship of tonals from the extracted tonals and frequency lines. First of all the precise detection and extraction of signal frequency lines is of particular importance for enhancing the reliability of target classification. But, the narrowband frequency lines which are the line formed in spectrogram by a tonal of constant frequency in each frame can be detected weakly or discontinuously because of the variation of signal strength and transmission loss in the sea. Also, it is very difficult to detect and extract precisely the signal frequency lines by the complexity of impulsive ambient noise and signal components. In this paper, the automatic detection and extraction method that can detect and extract the signal components of frequency tines precisely are proposed. The proposed method can be applied under the bad conditions with weak signal strength and high ambient noise. It is confirmed by the simulation using real underwater target data.

• Journal of Sasang Constitutional Medicine
• /
• v.23 no.1
• /
• pp.33-43
• /
• 2011

1. Objectives: This study is aimed to develop the algorithm, which can help clinicians diagnose Soeumin's symptomology, based on the indexes such as dry mouth, water drinking, sweat, urine, appetite, digestion, and stool, etc. 2. Methods: This research analyzes the items of "Donguisusebowon(東醫壽世保元)" to reveal the inevitable and sequential indexes of Soeumin's symptomology diagnosis, in order of exterior-interior pattern differentiation, favorable-unfavorable pattern differentiation, and mild-severe-dangerous-urgent pattern differentiation. 3. Results and Conclusions: 1) 1st step: Soeumin's exterior pattern and interior pattern are differentiated in terms of heat and cold, respectively. Stool and digestion are used to confirm the difference. 2) 2nd step: The existence of sweat is used to find out that an exterior pattern is with or without favor, while the indexes of stool, dry mouth, and generalized pain are used to identify an interior pattern with or without favor. 3) 3rd step: The favorably exterior-heat pattern can be either mild or severe by the indexes of cold-heat, stool, tidal fever, and manic raving, panting and straight looking, while the unfavorably exterior-heat pattern can be either dangerous or urgent by the ones of cold-heat, stool, and urine. And, the favorably interior-cold pattern can be either mild or severe by the indexes of stuffiness and fullness, jaundice, and edema, while the unfavorably interior-cold pattern can be either mild or severe by the ones of vexation level.

• Journal of Korean Medical classics
• /
• v.33 no.3
• /
• pp.21-36
• /
• 2020

Objectives : This paper aims to understand the meaning of '少陰人 心之範圍' and to determine its clinical implication. Methods : First, the meaning of the verb '範圍' was examined in 『IChing·XiCi(周易·繫辭傳)』 from where it originated. Based on the findings, the meaning of '心之範圍' in the context of the nature and emotion[性情] of So-eumin as explained in the 『DongUisusebowon(東醫壽世保元)』 was further investigated. Moreover, the clinical significance of the observation of '心之範圍' in relation to determining prognosis was discussed in regards to 'visceral syncope[藏厥]' and 'exuberating yin separating yang[陰盛隔陽]' which come under the severe symptoms[危證] category in the disease pattern of So-eumin. Results : '範圍' as mentioned in 『IChing·XiCi(周易·繫辭傳)』 refers to the process of creating a framework that takes after the tendencies of the patterns of change of the external world that influences mankind. The objective of this process is to prepare for the excessiveness and insufficiency of the change that happens in the external world so as to ultimately protect all existences. The workings of '範圍' could be assumed on a personal level as well. As the nature and emotion of So-eumin is closely related to the purpose and object of '範圍', Yi Jema suggested that through observing whether the So-eumin exhibits '心之範圍' or not, that it could be determined whether his/her innate nature is being properly exercised or not. Conclusions : Whether one's agitation calms down or not even for a moment is the criteria for determining prognosis of the entire disease, while its calming-down relies on proper functioning of '心之範圍'. The way to determine this is through observation of the manifest attitude of the So-eumin. If the So-eumin displays a poised and autonomous[綽綽卓卓] attitude even for a moment, it could be understood as the '心之範圍' process being properly functioning, indicating the overall direction to be heading towards relief of the sense of instability, allowing for a positive outlook on treatment.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.25 no.9
• /
• pp.1157-1164
• /
• 2001

Centrifugal fans are widely used and the noise generated by these machines causes one of the most serious problems. In general, the centrifugal fan noise is often dominated by tones at BPF(blade passage frequency) and its higher harmonics. This is a consequence of the strong interaction between the flow discharged from the impeller and the cutoff in the casing. However, only a few research have been carried out on predicting the noise because of the difficulty in obtaining detailed information about the flow field and casing effects on noise radiation. The objective of this study is to understand the generation mechanism of sound and to develop a prediction method for the unsteady flow field and the acoustic pressure field of a centrifugal fan. We assume that the impeller rotates with a constant angular velocity and the flow field of the impeller is incompressible and inviscid. So, a discrete vortex method(DVM) is used to model the centrifugal fan and to calculate the flow field. The force of each element on the blade is calculated by the unsteady Bernoulli equation. Lowsons method is used to predict the acoustic source. In order to compare the experimental data, a centrifugal impeller and wedge introduced by Weidemann are used in the numerical calculation and the results are compared with the experimental data. Reasonable results are obtained not only for the peak frequencies but also for the amplitudes of the tonal.