• Economic and Environmental Geology
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• v.45 no.3
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• pp.307-315
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• 2012

In this paper, a laboratory model test was conducted to evaluate grouting efficiency of ordinary portland cement(OPC) and micro cement used in MIS(Micro-Injection Process System). For this research, a injection equipment was developed for pressure permeation which can evenly simulate various grouting tests in a laboratory and suggested a standard for the production of the test specimen. Using the injection device, the laboratory injection tests of grouts were prepared with water/cement ratio of 1:1, 2:1, 3:1, 4:1, and 5:1. The analysis of injection test for pressure permeation showed that the efficiency of injection increases linearly as the water/cement ratio increases. Comparison of efficiency of the injection indicates that MIS with a relatively smaller average diameter shows more efficient injection than the OPC. In the low ratio of water/cement as 2:1~1:1, the injection efficiency of OPC was especially poor. Also, a nonlinear grout volume-injection time is represented by a hyperbolic model and grout volume predicted by hyperbolic model was compared with the value measured. From the comparison, it shows that the hyperbolic model has the potential of evaluating the efficiency of grouting.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.3
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• pp.694-702
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• 2017

In the case of an elevated railway station, structure borne noise and vibration due to structural limitations allow the load and vibration from railway vehicles to be directly transmitted to the station structure, resulting in an increase in the number of civil complaints from customers and staff of the station. The floating slab track system, which is well known as one of the solutions for reducing the noise and vibration from elevated railway stations, usually contains rubber mounts or rubber pads under the railway slab which act as a damper. These types of device have the disadvantage that is difficult to predetermine the exact stiffness and damping ratio under the nonlinear loads resulting from train services. In this study, an isolator with a friction type of wedge is introduced, which can be applied to floating slab track systems and to be designed with precisely the required stiffness. Furthermore, a comparative analysis of the stiffness between the designed and experimental values is carried out, while the damping ratio, which is closely related to the friction wedge blocks, is deduced according to the train load condition. The performance tests of the isolator were conducted in accordance with the DIN 45673-7 standard which includes both static and dynamic load tests. The load conditions for the performance tests are designed to conform to the DIN standard related to the weight of the train and rail track, in order to perform vertical and horizontal load tests, so as to ensure the secure structural safety of the railway. Also, by checking the change aspect of the friction coefficients of the friction elements according to the loading rate, the vibration reduction performance of the friction type isolator with variable loading rate conditions is examined.

• Korean Journal of Optics and Photonics
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• v.13 no.2
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• pp.146-150
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• 2002

1.55${\mu}{\textrm}{m}$ PnpN optical thyristor as a smart optical switch has potential applications in advanced optical communication systems. PnpP optical thyristors operating at 1.55${\mu}{\textrm}{m}$ are proposed and fabricated for the first time. In the optical thyristors, we employ InGaAs/InP multiple quantum well (MQW) for the active n- and p-layers. The thyristors show sufficiently nonlinear s-shape I-V characteristics and spontaneous emission. In the OFF-state, the device has a high-impedance up to switching voltage of 4.03(V). On the other hand, it has low-impedance and emits spontaneous light as a light-emitting diode in the ON-state voltage of 1.77(V), and switching voltage is changed under several light input conditions. It can be used as a header processor in optical asynchronous transfer mode (ATM), as a hard limiter in optical code division multiple access (CDMA) and as a wavelength converter in optical WDM systems.

• Progress in Medical Physics
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• v.19 no.3
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• pp.143-149
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• 2008

The aim of this study is to suggest the method for image enhancement of digital chest radiograph and evaluate clinically the quality of the resultant image. A nonlinear iterative filter was developed in order to reduce quantum noise preserving edge. Dynamic range was adjusted and adaptive image enhancement was performed based on the property of anatomic region and the degree of compatibility with neighboring pixels. The lung fields were enhanced appropriately to visualize effectively vascular tissue, bronchus and lung tissue with the desired mediastinum enhancement. Clinic evaluation was performed by three radiologists with at least 8 years experience. The anatomic regions of 11 in PA and 9 in Lateral were observed carefully in each 100 radiographs according to ITU (International Telecommunication Union) recommendation 500 protocol. The result showed the mean 3.4 between good and adequate. This means that the clinical utility of the image quality is enough. In this study, image enhancement was carried out considering image display device and human perceptual system to prevent the loss of useful anatomic information. In order to increase the diagnostic accuracy in digital radiograph, the continuous study on image enhancement is needed.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.41 no.12
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• pp.27-34
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• 2004

The study on the RF substrate circuit is necessary to model RF output characteristics of deep submicron MOSFETs below 0.2$\mum$ gate length that have bun commercialized by the recent development of Si submicron process. In this paper, direct extraction methods are developed to apply for a simple substrate resistance model as well as another substrate model with connecting resistance and capacitance in parallel. Using these extraction methods, better agreement with measured Y22-parameter up to 30 GHz is achieved for 0.15$\mum$ CMOS device by using the parallel RC substrate model rather than the simple resistance one, demonstrating the RF accuracy of the parallel model and extraction technique. Using this model, bias and gate length dependent curves of substrate parameters in the RF region are obtained by increasing drain voltage of 0 to 1.2V at deep submicron devices with various gate lengths of 0.11 to 0.5㎛ These new extraction data will greatly contribute to developing a scalable RF nonlinear substrate model.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.9-20
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• 2014

Steel intermediate moment frames (IMFs) have been generally used as seismic load resisting systems (SLRSs) of a building to provide resistances against strong ground shaking. However, most of low and mid-rise steel buildings in Korea were constructed during pre-seismic code era or before the introduction of well-organized current seismic codes. It has been recognized that the seismic performance of these steel IMFs is still questionable. In order to respond to such a question, this study quantitatively investigates the seismic capacities of steel IMFs. Prototype models are built according to the number of stories, the levels of elastic seismic design base shear and the ductilities of structural components. Also, the other prototype models employing hysteretic energy dissipating devices (HEDDs) are considered. The collapse mechanism and the seismic performance of the prototype models are then described based on the results obtained from nonlinear-static and incremental-dynamic analyses. The seismic performance of the prototype models is assessed from collapse margin ratio (CMR) and collapse probability. From the assessment, the prototype model representing new steel IMFs has enough seismic capacities while, the prototype models representing existing steel IMFs provide higher collapse probabilities. From the analytic results of the prototype models retrofitted with HEDDs, the HEDDs enhance the seismic performance and collapse capacity of the existing steel IMFs. This is due to the energy dissipating capacity of the HEDDs and the redistribution of plastic hinges.

• Journal of Biomedical Engineering Research
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• v.24 no.3
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• pp.183-192
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• 2003

A transformation methode of the chromaticity coordinates was proposed to calibrate the measured data obtained by a urine analysis system which implemented in our previous study. Generally. the reacted color of a reagent strip by urine analysis system often exhibit the color distortions due to nonlinear characteristics of the various devices that is the optic module mechanism. hardware, and surround circumstance. A color correction method for minimizing the color distortion play a few role in maintaining high accuracy and reproduction of the urine analysis system. In this work, we used the compensation method such as the shading correction, the characteristic curve extraction of RGB color by means of third order spline interpolation, and linear transformation using a reference color. In addition, 1931 CIE XYZ color space was used to compensate the color of the measured data by a standard reference system as colorimeter. A compensation matrix was obtained so that the output values of the urine analysis system is nearly equal to that of a standard reference system for identical color sample. Color correction obtained by a urine analysis system which implemented in our previous study exhibited a good color accuracy when it was compared with the reference data. Observed result from an experiments on ten items or a urinalysis strip that color difference or between two urine analysis system was 1.28.

• Journal of the Korean Electrochemical Society
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• v.2 no.1
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• pp.17-22
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• 1999

Since the use of porous silicon for microsensors and microactuators is in the euly stage of study, only several application devices, such as light-emitting diodes and chemical sensors have so far been demonstrated. In this paper we present an overview of the present status of porous silicon sensors and actuators research with special emphasis on the applications of chemical sensors and optical devices. The capacitive type porous silicon humidity sensors had a nonlinear capacitance-humidity characteristic and a good sensitivity at higher humidity above $40\%RH$. The porous silicon $n^+-p-n^+$ device showed a sharp increase in current when exposed to an ethanol vapor. The $p^+-PSi-n^+$ diode fabricated on porous silicon diaphragm exhibited an optical switching characteristic, opening up its utility as an optical sensor or switch. The photoluminescence (PL) spectrum, taken from porous silicon under 365 nm excitation, had a broad emission, peaked at -610 nm. The electroluminescence(EL) from ITO/PSi/In LED had a broader spectrum with a blue shifted peak at around 535nm than that of the PL.

• Korean Journal of Crystallography
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• v.4 no.2
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• pp.74-85
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• 1993

Single crystals of LiNbO3 have found extensive application in electro-optic and nonlinear optic devices. However, laser-induced refartive index inhomogeneities, which have been labeled opical damage impose limits on device optical damage in LiNbO3 is imporved if more than 4.5 rml% MgO is added to the melt The laser damage thrueshold increased as much as 100 times better then that of undoped crystals. The MgO doped cystal has thus been urterlsiv81y studied since then. In the study, Mgo:LiNbOs(MLA) single crystals dopsd with 0, 2.5, 5.0, 7.5, 10.0 mol% MgO have been grown by the czocrualski technique. The metls were prepared in the platinum crluible and 15∼20mm diameter crystals were grown with a length of 20∼30mm in a resitance heater. The growth rate was 2.5mm/hr, the rotation speed 15rpn. Before sawing MLN single crystals were annealed for 24 hours under atmosphere at a temperature of 1080℃. After sawing, we have found an annual ring cross section of MNA crystals only in the direction of perpendicilar to the c-axis. Nonuniform dispusion of MgO was pointed out that the cuties of the state of oxide were strongly affected by oxygen partial pressure in.

• Korean Journal of Optics and Photonics
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• v.18 no.1
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• pp.1-7
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• 2007

Filter colorimeters have a set of spectral bands for which spectral responsivity is the same as the color matching function defined by CIE (Commission Internationale de I'Eclairage). We have designed a set of color matching function filters denoted by $\bar{x}-filter,\;\bar{y}-filter,\;and\;\bar{z}-filter$. Because the $\bar{x}-function$ has two transmission bands, two $\bar{x}-filters$ are designed to cover the $\bar{x}-function$. To design the filters, we developed a nonlinear least square fit program which determines the thickness of the color glasses by minimizing its spectral mismatch value ($f{_1}'$) to below 3 %. The design has been validated by fabrication of the $\bar{y}-bar$ filter, of which $f{_1}'$ was measured to be 2.8 %. Considering a LCD flat panel display as a device under test, we have calculated the systematic error of the colorimetric measurement using the designed filters.