• 한국지구물리탐사학회:학술대회논문집
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• 2004.06a
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• pp.3-17
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• 2004

Space-borne Earth observation technique is one of the most cost effective and rapidly advancing Earth science research tools today and the potential field and micro-wave radar applications have been leading the discipline. The traditional optical imaging systems including the well known Landsat, NOAA - AVHRR, SPOT, and IKONOS have steadily improved spatial imaging resolution but increasing cloud covers have the major deterrent. The new Earth observation satellites ENVISAT (launched on March 1 2002, specifically for Earth environment observation), ALOS (planned for launching in 2004 - 2005 period and ALOS stands for Advanced Land Observation Satellite), and RADARSAT-II (planned for launching in 2005) all have synthetic aperture radar (SAR) onboard, which all have partial or fully polarimetric imaging capabilities. These new types of polarimetric imaging radars with repeat orbit interferometric capabilities are opening up completely new possibilities in Earth system science research, in addition to the radar altimeter and scatterometer. The main advantage of a SAR system is the all weather imaging capability without Sun light and the newly developed interferometric capabilities, utilizing the phase information in SAR data further extends the observation capabilities of directional surface covers and neotectonic surface displacements. In addition, if one can utilize the newly available multiple frequency polarimetric information, the new generation of space-borne SAR systems is the future research tool for Earth observation and global environmental change monitoring. The potential field strength decreases as a function of the inverse square of the distance between the source and the observation point and geophysicists have traditionally been reluctant to make the potential field observation from any space-borne platforms. However, there have recently been a number of potential field missions such as ASTRID-2, Orsted, CHAMP, GRACE, GOCE. Of course these satellite sensors are most effective for low spatial resolution applications. For similar objects, AMPERE and NPOESS are being planned by the United States and France. The Earth science disciplines which utilize space-borne platforms most are the astronomy and atmospheric science. However in this talk we will focus our discussion on the solid Earth and physical oceanographic applications. The geodynamic applications actively being investigated from various space-borne platforms geological mapping, earthquake and volcano .elated tectonic deformation, generation of p.ecise digital elevation model (DEM), development of multi-temporal differential cross-track SAR interferometry, sea surface wind measurement, tidal flat geomorphology, sea surface wave dynamics, internal waves and high latitude cryogenics including sea ice problems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.10
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• pp.581-588
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• 2020

This study examined a brake pad wear compensation method for an Electro-Mechanical Brake (EMB) using the braking test device. A three-phase Interior Permanent Magnet Synchronous Motor (IPMSM) was applied to drive the actuator of an EMB. Current control, speed control, and position control were used to control the clamping force of the EMB. The wear compensation method was performed using a software algorithm that updates the motor model equation by comparing the motor output torque current with a reference current. In addition, a simple first-order motor model equation was applied to estimate the output clamping force. The operation time to the maximum clamping force increased within 0.1 seconds compared to the brake pad in its initial condition. The experiment verified that the reference operating time was within 0.5 seconds, and the maximum value of the clamping force was satisfied under the wear condition. The wear compensation method based on the software algorithm in this paper can be performed in the pre-departure test of rolling stock.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.77-77
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• 2017

Titanium and its alloys offer attractive properties in a variety of applications. These are widely used for the field of biomedical implants because of its good biocompatibility and high corrosion resistance. Titanium anodizing is often used in the metal finishing of products, especially those can be used in the medical devices with dense oxide surface. Based on SAE/AMS (Society of Automotive Engineers/Aerospace Material Specification) 2488D, it has the specification for industrial titanium anodizing that have three different types of titanium anodization as following: Type I is used as a coating for elevated temperature forming; Type II is used as an anti-galling coating without additional lubrication or as a pre-treatment for improving adherence of film lubricants; Type III is used as a treatment to produce a spectrum of surface colours on titanium. In this study, we have focused on Type II anodization for the medical (dental and orthopedic) application, the anodized surface was modified with gray color under alkaline electrolyte. The surface characteristics were analyzed with Focused Ion Beam (FIB), Scanning Electron Microscopy (SEM), surface roughness, Vickers hardness, three point bending test, biocompatibility, and corrosion (potentiodynamic) test. The Ti-6Al-4V alloy was used for specimen, the anodizing procedure was conducted in alkaline solution (NaOH based, pH>13). Applied voltage was range between 20 V to 40 V until the ampere to be zero. As results, the surface characteristics of anodic oxide layer were analyzed with SEM, the dissecting layer was fabricated with FIB method prior to analyze surface. The surface roughness was measured by arithmetic mean deviation of the roughness profile (Ra). The Vickers hardness was obtained with Vickers hardness tester, indentation was repeated for 5 times on each sample, and the three point bending property was verified by yield load values. In order to determine the corrosion resistance for the corrosion rate, the potentiodynamic test was performed for each specimen. The biological safety assessment was analyzed by cytotoxic and pyrogen test. Through FIB feature of anodic surfaces, the thickness of oxide layer was 1.1 um. The surface roughness, Vickers hardness, bending yield, and corrosion resistance of the anodized specimen were shown higher value than those of non-treated specimen. Also we could verify that there was no significant issues from cytotoxicity and pyrogen test.

• Journal of the Microelectronics and Packaging Society
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• v.7 no.3
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• pp.45-54
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• 2000

The effect of electropolishing far stamped leadframe on the removal of the edge burr and residual stress relief was examined. The present study showed that the electropolishing could be used for enhanced surface quality of stamped leadframes. The electropolishing was performed at the condition of 60% phosphoric acid electrolyte, 5 ampere of current and 3 cm electrode gap at $70^{\circ}C$ for 2 minutes for Alloy42 type leadframe, and $50^{\circ}C$ for 1.5 minutes for C-194 type leadframe. The FWHM values from X-ray diffraction showed that residual stress of electropolished leadframe recovered to the level of as-received raw materials and surface roughness measured by using AFM tuned out to be improved by 0.079 $\mu\textrm{m}$ and 0.014 $\mu\textrm{m}$ ($R_{rms}$) far alloy 42 and C-194 type leadframes, respectively. The plated thickness using XRF showed the improved uniformity in thickness variation by 0.4~0.5 $\mu\textrm{m}$ and grain growth, which is favorable for interface adhesion, was also observed from the bake test samples. We could certify dimensional stability of leadframe with inspection by means of 3D-topography and hardness measurements.

• Journal of the Korean Society of Marine Environment & Safety
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• v.21 no.6
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• pp.744-750
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• 2015

In this paper, development of mobile robot for the inspection of hull surface was mentioned. In the sea, it is difficult to proceed with the visual inspection of hull side and thus mobile robot for checking the status could be run with strap-on its surface. To do this, permanent magnet module to generate magnetic force between hull surface and mobile robot, and structure to minimize variance of the force under curvature circumstance were considered on the design. Based on the design, mobile robot with four NdFeB, four driving wheels and image aquisition module was applied. Load experiment to check the adhesive force, slip test during stop state and driving test to measure driving speed were executed. From the experiments 13 Kgf adhesive force was obtained and slip was not happened until 8 Kgf load on the inclined plate. Driving speed of mobile robot was measured at 0.82 m/s corresponding to 6.5 ampere. We confirmed the effectiveness of developed mobile robot by experiments to check its characteristics.

• Journal of the Korean Chemical Society
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• v.27 no.4
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• pp.279-286
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• 1983

An apparatus was made for the electrodeposition of alpha emitting actinide nuclides, $^{207}Bi$ and $^{210}Po$. The electrodeposition was made on a polished stainless steel plate cathode. The anode was made of platinum wire and to stir the solution. With the ammonium chloride as electrolyte initial pH = 4, chloride concentration = 0.6M and solution volume = 15ml, a current of 1.5 ampere(current density = 0.59A/$cm^2$) was flowed for 100 minutes for the quantitative recovery of electrodeposition and on average recovery of 98.3% was obtained within ${\pm}$0.7% uncertainty. Alpha spectrometry of the electrodeposited sample showed alpha peaks from $^{210}Po, ^{234}U$ and $^{239}Pu$ having energy resolution (FWHM) of 18.3, 21.8 and 36.0 keV respectively. The electrodeposition and alpha spectrometry for a natural uranium sample of domestic origin gave $^{238}U : ^{234}U = 1 : 6.1{\times}10^{-5}$ and for a neutron-irradiated uranium sample did $^{238}U : ^{239}Pu : ^{241}Am = 100 : 0.0263 : 5.20{times}10^{-5}$. The result of $^{238}U$ determination in the irradiated sample by electrodeposition-alpha spectrometry was in accord within ${\pm}1.6%$ of relative error with the results of solid fluorimetry and mass spectrometry. For $^{239}Pu$ the result of electrodeposition-alpha spectrometry was in accord within ${\pm}$4.0% of relative error with the results of anion exchange separation and the thenoyltrifluoroacetone(TTA) extraction both followed by alpha spectrometries.

• The Korean Journal of Applied Statistics
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• v.26 no.2
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• pp.335-347
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• 2013

There are various types of real world signals. For example, an electrocardiogram(ECG) represents myocardium activities (contraction and relaxation) according to the beating of the heart. ECG can be expressed as the fluctuation of ampere ratings over time. A signal is a composite of various types of signals. An orchestra (which boasts a beautiful melody) consists of a variety of instruments with a unique frequency; subsequently, each sound is combined to form a perfect harmony. Various research on how to to decompose mixed stationary signals have been conducted. In the case of non-stationary signals, there is a limitation to use methodologies for stationary signals. Huang et al. (1998) proposed empirical mode decomposition(EMD) to deal with non-stationarity. EMD provides a data-driven approach to decompose a signal into intrinsic mode functions according to local oscillation through the identification of local extrema. However, due to the repeating process in the construction of envelopes, EMD algorithm is not efficient and not robust to a noise, and its computational complexity tends to increase as the size of a signal grows. In this research, we propose a new method to extract a local oscillation embedded in a signal by utilizing the second derivative.

• Journal of the Korean Society of Radiology
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• v.10 no.2
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• pp.109-115
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• 2016

Despite of increasing the use of the digital imaging device in the radiology area, the setting on the optimal irradiation conditions are insufficient. In this study, the exposure dose and image quality by exposure condition of digital radiography device were compared. The exposure doses were obtained by adjusting the exposure condition as 5 steps respectively based on the exposure conditions that are currently used of CR and DR radiography devices. The acquired image has been assessed by 20 medical image professors using the assessment method of the Japanese Society for Tuberculosis Prevent. As a result, in the case of the CR system, the better image quality was obtained in the condition of 120 kVp and 1.5 mAs~2.4 mAs (quality score 91~95.5 points) than standard exposure condition(110 kVp, 3.2 mAs, 86 points). And exposure dose was evaluated as low with $61.3{\sim}98.4{\mu}Gy$ than standard condition($105.11{\mu}Gy$). In DR system, however, the image quality score was higher as 97~98.6 points in the lower tube voltage range (112 kVp, 2.4~3.2 mAs) condition than the standard exposure condition (125 kVp, 3.2 mAs, 91 points). In addition, the exposure dose was $61.5-77.2{\mu}Gy$ lower than standard condition($93{\mu}Gy$). In addition, the exposure dose was low as $61.5-77.2{\mu}Gy$ than standard condition($93{\mu}Gy$). With the results of this study, we confirmed that it is possible to reduce the patient exposure dose with the same image quality by adjusting the optimal exposure condition of digital device.

• Journal of Korean Society of Forest Science
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• v.23 no.1
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• pp.1-8
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• 1974

The seed quality testing for Korean white pine (Pinus koraiensis), their pre-germination and embryo growing process were investigated and the abnormal embryo groups were discriminated by the use of soft X-ray photograph. The study results were as follows ; 1. The embryo reflection was clearly observed for air dried seeds (moisture content was 6.3%) at 30 sec, stratificated seeds at 60 sec (moisture content 24.0-36.0%) and immature seed (moisture content 41.0-64.0%) at 90sec., then the photographing variation for soft X-ray was the radiographing distance at 42cm focus M, voltage 19.5 K.V.P. and Ampere 8 mA. By the above result, the radiographing time for discriminating the embryo reflection was increased by the increase of moisture content in the seeds. 2. The embryo reflection could be clearly observed from the last ten days of June and the embryo length ratio to endosperm length was growing to 65% at the first ten days of September. By the result obtained the soft X-ray photograph was thought to be effective method for the study of inner morphology of seeds. 3. The clear reflection seeds for embryo and endorsperm were observed to 69.7% and the seeds were practically germinated to 75.2% The difference in number between the discriminated seeds by the soft X-ray photograph and the practically germinated seeds was only 6%. According to this results, the soft X-ray photograph was thought to be a effective methods for the germination diagnosis in the shortest time and with the exactness comparatively. 4. Because of the possibility of clearness for observation of pre-germination process, the soft X-ray photograph could be used for the study on the physiology of seed germination. 5. The frequency of abnormal embryos was observed of total 4.4% and their types and subtypes could be classified into twenty groups. Among these groups, single abnormal embryo type was divided into eight subtypes and observed of 2.0 percent, twin embryo was six subtypes and 1.8 percent, triple embryo was five subtypes and 0.5 percent, and inverse type was 0.12 percent.