• Tunnel and Underground Space
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• v.27 no.5
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• pp.324-332
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• 2017

In this paper, a numerical analysis of one-dimensional viscous fluid flow in a rock joint using UDEC code is performed to evaluate the effect of design parameters on injection performance. We consider injection pressure, fluid compressibility, time dependence of yield strength and viscosity of injected grout fluid, and mechanical deformation of joint as the design parameters, and penetration length and flow rate of injection are investigated as the injection performance. Numerical estimations of penetration length and flow rate were compared to analytical solution and were well comparable with each other. We showed that cumulative injection volume can be over-estimated by 1.2 times than the case that the time-dependent viscosity evolution is not considered. We also carried out a coupled fluid flow and mechanical deformation analysis and demonstrated that injection-induced joint opening may result in the increment of cumulative volume by 4.4 times of that from the flow only analysis in which joint aperture is kept constant.

• Journal of Korean Society on Water Environment
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• v.21 no.1
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• pp.29-33
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• 2005

In order to recycle the waste material and to develop the thickening unit of waste activated sludge from wastewater treatment facilities, the filtration bio-reactor equipped with a shadow mask filter module was employed for this work from which the operating properties and parameters were drawn. The sludge thickening and filtration unit is made of cylindrical acryl tank(12cm i.d. ${\times}$ 58cm height: working volume of 6L), where the flat-sheet type of shadow mask filter module(pore size: 220~250um, opening area: 34.8~39.6%) was installed and the effluent was withdrawn from the effluent port at the lowest point of the reactor, and the filtration was performed only by the hydraulic pressure. For evaluating the operating performance of this reactor, some parameters such as the solid-liquid separation of different biomass concentrations, the water quality of filtrate, the aeration cleaning time and the cleaning effect were investigated. Depending on the MLSS concentrations, the different time to withdraw 3L of filtrate was required in which the longer filtration time was necessary for the higher MLSS concentrations caused by the thicker formation of cake layer: 40 minutes for 5,000 mg/L, 70 minutes for 10,000 mg/L and 100 minutes for 15,000 mg/L, where the concentrations of SS were 8.9, 6.7 and 6.5 mg/L, respectively. Under the same operating conditions (the intensity of aeration cleaning: 80 L/min, MLSS: 10,000 mg/L), the proper aeration cleaning time was revealed 30 seconds, and the stable formation of cake layer was in the range of 10 to 15 minutes. Therefore, the shadow mask considered as a waste material can be of use as a filter material for the sludge thickening system.

• Journal of the Korean Institute of Intelligent Systems
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• v.20 no.1
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• pp.109-115
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• 2010

A main technology of opening and closing a sluice gate is accurate synchronous and position control for the two cylinders when they are moving with the sluice gate together over 10[m]. Since the supply flow and supply pressure of cylinders are not constant and a nonlinear friction force of the piston in cylinders exists, a difference will be made between the displacement of two cylinders. This difference causes the sluice gate to deform and abrade, and even it may be out of order. In order to solve this problem we design two kinds of fuzzy PI controllers. The former is for a position control of two cylinders, the latter is for their synchronous control. We show some simulation results compare the performance of fuzzy PI controller to the conventional PID controller.

• Journal of Cadastre & Land InformatiX
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• v.44 no.2
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• pp.59-72
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• 2014

In this paper the key drivers change for cadastral organizations have been presented according to the following aspects; Geo-ICT development including positioning technology, government's public organization innovation policy, cadastral market opening pressure and decreasing of cadastral survey work. It was confirmed that the role of cadastral organization has to be changed from the conducting cadastral survey organization to the spatial information provision organization. Eventually it should take a role to realize Spatially Enabled Society(SES) which is fundamental for national development and upgrading quality of life in the society. From the case study of international cadastral organization, cadastral organization should take core responsibility for the Nation Spatial Data Infrastructure(NSDI) and meeting the future costumers requirements through technical developments and organization's innovation efforts.

• The Journal of Engineering Geology
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• v.6 no.2
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• pp.59-64
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• 1996

Acoustic Emission(AE) signals are emitted by a sudden release of strain energy associated with material damage. A multi-channels of LeCroy system and piezoelectric pressure transducers are employed for AE measurement to investigate the roles of AE in the propagation of macro cracks as well as the characteris-tics of AE wave in occurrence, amplitude and dominant frequency with changes in macro loading modes. Deduced crack opening volume of micro cracks varied widely and implies that AE events could be caused by crystal dislocations on a small scale and grain boundary movements on a large scale. Amplitude of first arrival AE wave emitted during mode I test was approximately 3 times higher than those from mixed mode test, while the number of AE count in mode I test was only 25% of mixed mode. It may imply that the total energy required for generation of a given fracture surface is similar regardless in change of macroloading modes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.6
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• pp.613-619
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• 2016

A pneumatic control valve performs a major role in controlling the flow of a system or the level of a key tank in many power plants, and its performance should be guaranteed during the plant's lifetime. Its operation starts by supplying air to the pneumatic actuator or by exhausting the air from the actuator. To control the valve position, the amount of air supply or exhaust is adjusted by a control loop where various accessaries are equipped. In this paper, air leakage in the air supply line, changes in the valve packing force, and false adjustments of zero and the span of the positioner are simulated and analyzed using a 2-in pneumatic valve with a position control loop including an I/P converter and positioner, where the valve position is controlled within ${\pm}2%$ of the control pressure at 67% opening position.

• Journal of the Korean Society of Clothing and Textiles
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• v.34 no.2
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• pp.189-199
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• 2010

This study develops a coverall design for the body shape and movement of infants. This research analyzed these processes: 1. The current coverall styles preferred for infants. 2. The appropriate products for the real size, body shape, movement, and fit of infants. 3. The observations of the 6 months to 9 months movement and development of infants. 4. The design and creation of a new coverall base in this study, and to check the suitable test the developed coverall design for the infant. The result of this study are: A coverall for infants that lie or crawl on the floor must avoid opening in the center front and a gore has to be added at the crotch of the pants for the better movement of infants. These ways provide infants a neat appearance and easy movement. The test of developed designs shows that the developed coverall design covers the size gap of the trunk loop according to the growth of the infant and the movement of the legs; in addition it provides a positive aesthetic effect. The waistline in the developed coverall (a waistline that should exist lower than the body waistline of the infant) can reduce seam stress because the pressure of the seam line can be absorbed in a dipper. It is one of the suitable design points for infants lying prone all day long in this study.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.55-60
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• 2004

The paper describes measurement techniques for an acoustic transfer characteristic of ship's bridge stimulated by a whistle sound. The response sounds, according to the opening-shutting conditions of bridge doors for T／S ‘SAENURI’, are measured by B＆K 2260D equipment, and then extracted the frequency responses by B＆K 7830 software. To evaluate the measured transfer characteristic, the 128th order FIR (Finite Impulse Response) filters, containing the frequency characteristic, are constructed based on the frequency sampling-based design method. Using evaluation indexes with six scales, psychological assessments by five subjects are carried out with test sounds which are convolved source sound and FIR filters. As results of tests, the test sounds gives A／sub s／=3.3∼4.7 which means the psychological sense of 'it is almost similar sound as original ones in a real world', and thus it is cleary seen tint the proposed method can be suit for the measurement of an acoustic transfer characteristic of ship's bridg.

• The Journal of Engineering Geology
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• v.9 no.3
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• pp.227-241
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• 1999

Groundwater flow in a fractured rock mass is related to the geometric characteristics of the fracture system. The objective of this study aims to analyze the probabilistic density function of fracture properties md their relations to the hydraulic conductivity in volcanic rocks of the northern Yosu area. Fracture characteristics were investigated by core logging and acoustic televiewer logging in four boreholes and the hydraulic conductivity was obtained from the constant pressure injection and fall-off tests. The 303 fractures were grouped into three sets by their orientation and three fracture types by the degree of opening in aperture. As a result of the study, the hydraulic conductivity in the test section intersected by open and semi-open fractures, conductive fractures, and set 1 fractures was very high, while closed fractures did rarely affect the hydraulic conductivity. It was recognized that the hydraulic conductivity in a fractured rock mass was preferentially affected by the aperture size of conductive fractures and fracture intersection frequency and size, secondly.

• Journal of the korean academy of Pediatric Dentistry
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• v.25 no.2
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• pp.268-276
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• 1998

Dentigerous cyst is a cyst arising by a seperation of follicles from around the anatomical crown of an unerupted tooth within the jaws. The dentigerous cyst is seen during routine radiographic examination. It is detected radiographically as a sharply delineated, round or oval, unilocular, homogeneous, and radiolucent area within which there is the crown of an unerupted tooth. The histological appearance of the dentigerous cyst is usually attached to the tooth at the cementoenamel junction and the sac lined by a thin, regular. stratified squamous epithelium. The dentigerous cyst can be treated by two surgical procedures: enucleation or marsupialization. The size and location of the lesion usually dictates the surgical procedures. The marsupialization consists of the removal of only a portion of the wall of the cyst to make the remaining cystic lining continous with the oral mucosa. The cyst, deprived of its supporting hydrostatic pressure, gradually shrinks until it is obliterated. The marsupialization is the best way to conserve the tooth affected by a dentigerous cyst and to permit its eruption. especially in a young person. Main advantages of the marsupialization are its relative simplicity and its conservation with respect to adjacent important structures. In marsupialization technique, a plugger can be constructed, if necessary, to maintain the opening and prevent food debris from entering the cystic cavity. However, the disadvantage is the potentiality of leaving pathologic tissues. Therefore frequent recall appointments are advisable.