• Geomechanics and Engineering
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• v.18 no.4
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• pp.439-448
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• 2019

The bearing capacity of roadside support is the key problem in gob-side entry retaining technology. To study the cooperative bearing characteristics of the roof-roadside support-floor along the gob-side entry retaining, a mechanical model of the composite structure of the roof-roadside support-floor was first established. A method for determining the structural parameters of gob-side entry retaining was then proposed. Based on this model, adaptability analysis of roadside support was carried out. The results showed that the reasonable width of the gob-side entry roadway was inversely proportional to the mining height, and directly proportional to the bearing strength of the roof and floor. And the reasonable width of the "flexible-hard" roadside support was directly proportional to its own strength, and inversely proportional to the width of the gob-side entry retaining. When determining the position and size of the roadside support along the gob-side entry retaining, the surrounding rock environment should be fully considered. Measured results from case study also show the rationality of the model and calculation method.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.8
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• pp.1565-1576
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• 2002

By way of driving a 2-way on/off solenoid hydraulic valve with a pulse width modulation (PWM) signal, control of the pressure in a certain volume is frequently used in various applications. However, the pressure built-up according to the duty ratio and carrier frequency of the PWM signal is not so well understood. In order to clarify the characteristics of 2-way valve hydraulic pressure control systems, in this paper two formula fur the mean and ripple of the load pressure were derived through theoretical analysis. And the accuracy of the derived formula were verified by comparison with the experimental test result. Generally 2-way valve systems are constructed as a bleed-off circuit, while 3-way valves are used as a control element in a meter-in circuit pressure control system. In a bleed-off circuit, the system supply pressure from a hydraulic power pack does not remain constant, but changes according to their external load. In turn, the relief valve in the hydraulic power pack reacts accordingly showing complicated dynamic behavior, which makes an analytical study difficult. In order to resolve the problem, simple but accurate empirical dynamic models fer a bleed-off system were used in the course of formula derivation. As the result, selection criteria for two major control parameters of the driving signal is established and the basic strategy to suppress the unnecessary pressure fluctuation can be provided for a hydraulic pressure control system using a 2-way on/off solenoid valve.

• 제어로봇시스템학회:학술대회논문집
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• 1988.10a
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• pp.289-294
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• 1988

This paper describes tbe design and implementation of the adaptive controller to maintain the glood weld quality in gas metal arc welding process. The weld torch travel speed and the surface temperature are taken, respectively, as an input and an output of the welding control system. Because of the very complex phenomena of the process, the input-output dynamic model was experimentally identified by AIC (Akiake Information Criterion). Based on the model structure, the explicit model reference adaptive controller is simulated in order to regulate the output tempernture to the desired level.

• 제어로봇시스템학회:학술대회논문집
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• 1992.10b
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• pp.30-35
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• 1992

Conflicting or inconsistent rules sometimes help us to represent the control actions of an expert more freely. Also, uncertainties about the control actions of the expert may render rules with conclusions whore membership functions have different width in their shapes. Conventional inference methods for FLC may not effectively handle such inconsistencies and/or rules containing such conclusions. In this paper, an effective inference method dealing with such If-Then rules is proposed.

• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.17-20
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• 2000

Usually, in many applications, high frequency resonant inverters are used, and the PAM(Pulse Amplitude Modulation), PFM(Pulse Frequency Modulation) or PWM(Pulse Width Modulation) techniques are used to control the output power of resonant inverters. In this paper, a new switching scheme is proposed as a PWM control method. With the proposed method, it can be obtained that unity output displacement factor under the variable resonant frequency. The detail algorithm of the proposed PWM switching scheme and its charicteristics are discussed. And the validity of the proposed method is confirmed with the experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.169-169
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• 2000

The modeling for the looper of a hot strip finishing mill to control the tension of the strip is presented. The looper is an arm pushing against the strip between stands in a tandem mill to keep the strip tension constant and to isolate the interactions of the adjacent stands. Tension is influenced by the difference in mass flow through the up stream and down-stream rolling stands. Tension is critical to strip quality, influencing width, gauge, and shape. This paper presents how looper angle and strip tension are controlled for a hot strip finishing mill.

• Atmosphere
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• v.27 no.4
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• pp.445-453
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• 2017

This study investigates turbulent flow around a square cylinder mounted on a flat surface at high Reynolds number using a large-eddy simulation (LES) model, particularly focusing on vortex streets behind the square cylinder. Total 9 simulation cases with different inflow wind directions, inflow wind speeds, and cylinder widths in the x- and y-directions are considered to examine the effects of inflow wind direction, speed, and cylinder widths on turbulent flow and vortex streets. In the control case, the inflow wind parallel to the x-direction has a maximum speed of $5m\;s^{-1}$ and the width and height of the cylinder are 50 m and 200 m, respectively. In all cases, down-drafts in front of the cylinder and updrafts, wakes, and vortex streets behind the cylinder appear. Low-speed flow below the cylinder height and high-speed flow above it are mixed behind the cylinder, resulting in strong negative vertical turbulent momentum flux at the boundary. Accordingly, the magnitude of the vertical turbulent momentum flux is the largest near the cylinder top. In the case of an inflow wind direction of $45^{\circ}$, the height of the boundary is lower than in other cases. As the inflow wind speed increases, the magnitude of the peak in the vertical profile of mean turbulent momentum flux increases due to the increase in speed difference between the low-speed and high-speed flows. As the cylinder width in the y-direction increases, the height of the boundary increases due to the enhanced updrafts near the top of the cylinder. In addition, the magnitude of the peak of the mean turbulent momentum flux increases because the low-speed flow region expands. Spectral analysis shows that the non-dimensional vortex generation frequency in the control case is 0.2 and that the cylinder width in the y-direction and the inflow wind direction affect the non-dimensional vortex generation frequency. The non-dimensional vortex generation frequency increases as the projected width of the cylinder normal to the inflow direction increases.

• Culinary science and hospitality research
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• v.18 no.1
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• pp.1-14
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• 2012

This study examines the physiochemical and quality properties of the bread added with soy fiber powder to promote the intake of soy fiber. For this study, the powder for making bread was mixed with soy fiber, wheat flour and SF-1450 and SF-1260 at the ratio of 0~12% each. The ratios of the edible fiber contained in the soy fiber power samples were 72.0% in the SF-1450 sample and 67.8% in the SF-1260 sample. The mixograph characteristics tended to be conspicuons in proportion to the amount of the soy fiber added at midline peak height, width at peak and, width at 8.00. The specific volume of the bread tended to decrease significantly as the amount of the soy fiber increased from 2 to 12%. In terms of crust chromaticity change, L-value increased more significantly in the samples added with 4 to 12% than the control. For a-value, SF-1450 in the samples with 6 to 12% and SF-1260 in the samples with 8 to 12% more significantly decreased than the control. For such characteristics of texture as hardness, SF-1450 in the samples with 10 to 12% and SF-1260 in the samples with 6 to 12% increased more than the control. As discussed above, the sensual characteristics of the white pan bread with soy fiber added tended to be worse as the amount of the additive increased, compared with the control samples. Summing up the results of the physico-chemical analysis and the overall acceptability, those samples with 2~4% of SF-1450 and 2% of SF-1260 were found excellent.

• Journal of Bio-Environment Control
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• v.20 no.2
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• pp.101-108
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• 2011

The small and medium sprayer has developed to spray well fruit trees and roadside trees with pesticides for pests control within 60 meters. This study was carried out to analyze and evaluate its performance using image processing. While it sprayed with pesticides on the area of 20m in width and 60m in length, it was experimented 5 places by 5m from 0 to 25m width and 6 places by 10m from 10 to 60m length. The experimental image data of each sheet on places were averaged after binarization process. According to the image data, it was sprayed on all working area. However, when sprayer moved 0.3m/s velocity, the place at 15m of width and 30m of length was sprayed more than any other sprayed area, but the place at 15m of width and 60m of length was sprayed less.

• Journal of Oral Medicine and Pain
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• v.18 no.2
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• pp.43-53
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• 1993

The aim of this study was to investigate the relationship between the presence or absence of anterior tooth contact and the changes in temporomandibular joint space. The study sample consisted of 32symptom-free dental students and 79 craniomandibular disorders patients with unilateral joint dysfunction. The two groups were categorized into control group or experimental group, respectively. Recordings of the number and distribution of occlusal contacts were made by T-Scan system. Transcranial radiographs were taken with using of accurad-100 head positioner. Measured items in transcranial radiographs were anterior, superior, posterior joint space and relative condylar position to deepest position of glenoid folla. According to the presence or absence of anterior tooth contact, each group was subdivided and compared with each other with respect to TM joint space. Data were processed and tested with SPSS/PC + package. The results of the study showed that the joint space in control group were wider than those of experimental group and the difference of the width of joint space was more remarkable in subjects with anterior contact between control group and experimental group. However, in same group whether the presence of anterior tooth contact could hardly affect the difference of the width of joint space. And anterior tooth contact in grouip are more frequent than in experimental group.