• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.35 no.1
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• pp.18-23
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• 2022

Electrohydrodynamic jet (e-jet) printing, a type of direct contactless microfabrication technology, is a versatile fabrication process that enables a wide range of micro/nanopattern arrays by applying a strong electric field between the nozzle and the substrate. In general, the morphology and the thickness of polymers/quantum dot micropatterns show a systematic dependence on the diameter of the nozzle and the ink composition with a fully automated printing machine. The purpose of this report is to provide typical examples of e-jet printed micropatterns of polymers/quantum dots to explain the effect of each process variable on the result of experiments. Here, we demonstrate several operating conditions that allow high-resolution printing of layers of polymers/quantum dots with a precise control over thickness and submicron lateral resolution.

• The Journal of the Acoustical Society of Korea
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• v.29 no.8
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• pp.476-482
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• 2010

The ultrasonic transient fields and B-mode images of a point target which were simulated for a medical ultrasonic probe with a few defective piezo-elements were compared with those for a normal probe. The present study considered a 3.5 MHz linear array probe whose acoustic beam was formed by the 64 active elements of total 192 elements. The results showed that the maximum amplitude and -3 dB width of the acoustic fields by main-lobes decreased linearly as the defective element number increased from one to four. However, the depths of foci remained almost unchanged, and the pressure differences between main-lobes and side-lobes tended to decrease due to rise in pressures in side-lobes. Such changes in ultrasonic fields affected the B-mode images of point targets. So the artifacts were formed in the right and left side of the target, and the lateral spatial resolutions were decreased while the axial resolution was almost the same.

• Journal of the Korean Society of Radiology
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• v.15 no.4
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• pp.463-472
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• 2021

Demand for examinations using transvaginal transducer with high frequencies is increasing to observe pelvic organs in gynecological ultrasound tests. However, the quality control of the replacement probe in clinical trials is not properly implemented and the evaluation criteria have not been established. Therefore, 58 transvaginal transducers and 20 convex transducers were applied to the ATS-539 ultrasound phantom for 20 ultrasound devices currently in clinical use to obtain their respective images and measure them quantitatively and qualitatively. For quantitative measurements, vertical measurement, horizontal measurement, and focal zone and qualitative measurements, dead zone, axial·lateral resolution, sensitivity, functional resolution, gray scale·dynamic range were performed. Quantitative statistical analysis showed significant differences between the two transducers in the lateral measurement and local area (p<0.05). qualitative comparative analysis showed differences in sensitivity and functional resolution. This occurs due to the difference in frequency between transducers and the transducer's injection geometry. Based on the above experiments, the tolerance for horizontal measurement is raised to 10% (±8 mm), the tolerance for sensitivity is observed up to 6 cm deep, which is 12 cm deep,which is the level of the third quartile (75%). The permissible range of functional resolution is up to 6 (12 cm), 6 (12 cm), 11 (11 cm), 9 (9 cm), 6 (6 cm) target, which is the level of the third quartile (75%). It is considered reasonable to adjust the depth of targets in gray scale·dynamic range to measure at a depth of 2 cm, which is 50% of the depth of 4 cm. As above, the criteria for evaluating the quality of transvaginal transducer for use in the past have been proposed and it is expected that this study will be used as a basic data for the production of phantom exclusively for transvaginal transducer in the future.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.1
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• pp.1-10
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• 2010

A regional climate model (RCM) can be a powerful tool to enhance spatial resolution of climate and weather information (IPCC, 2001). In this study we conducted dynamical downscaling using Weather Research and Forecasting Model (WRF) as a RCM in order to obtain high resolution regional agroclimate indices over the Korean Peninsula. For the purpose of obtaining detailed high resolution agroclimate indices, we first reproduced regional weather for the period of March to June, 2002-2008 with dynamic downscaling method under given lateral boundary conditions from NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research) reanalysis data. Normally, numerical model results have shown biases against observational results due to the uncertainties in the modelis initial conditions, physical parameterizations and our physical understanding on nature. Hence in this study, by employing a statistical method, the systematic bias in the modelis results was estimated and corrected for better reproduction of climate on high resolution. As a result of the correction, the systematic bias of the model was properly corrected and the overall spatial patterns in the simulation were well reproduced, resulting in more fine-resolution climatic structures. Based on these results, the fine-resolution agro-climate indices were estimated and presented. Compared with the indices derived from observation, the simulated indices reproduced the major and detailed spatial distributions. Our research shows a possibility to simulate regional climate on high resolution and agro-climate indices by using a proper downscaling method with a dynamical weather forecast model and a statistical correction method to minimize the model bias.

• Journal of the korean academy of Pediatric Dentistry
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• v.45 no.1
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• pp.65-74
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• 2018

The aim of this study was to obtain the traceability of the software used to analyze lateral cephalometry and to calculate the uncertainty of the measurements. Furthermore, this study aimed to provide a basis for obtaining standard references for measurement values for orthodontic treatment in children. Cephalometric data were collected from 100 children diagnosed with class I malocclusion between the ages 6 to 13 years who visited the pediatric dentist at Seoul National University Dental Hospital. To ensure traceability, a phantom device was created. Correction values were calculated by measuring the length and angle of the phantom device using the software. Type A uncertainty was calculated by obtaining the standard deviation of cephalometric measurements of 100 persons and the standard error of repeated measurements. Determination of the type B uncertainty was induced by minimum resolution and the position of the head. Using these, the combined standard uncertainty was obtained and the expanded uncertainty was calculated. The results of this study confirm that the currently used software has high accuracy and reliability. Furthermore, the uncertainty of orthodontic measurements in Korean children aged 6 to 13 years was calculated, and distribution range for class I malocclusion with 95% confidence interval was suggested.

• Geophysics and Geophysical Exploration
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• v.14 no.2
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• pp.127-132
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• 2011

We acquired and interpreted more than 650 km of high-resolution seismic reflection profiles in the Hupo Basin, offshore east coast of Korea at $37^{\circ}N$ in the East Sea (Japan Sea) to image shallow and basement deformation. The seismic profiles reveal that the main depocenter of the Hupo Basin in the study area is bounded by the large offset Hupo Fault on the east and an antithetic fault on the west; however, the antithetic fault is much smaller both in horizontal extension and in vertical displacement than the Hupo Fault. Sediment infill in the Hupo Basin consists of syn-rift (late Oligocene. early Miocene) and post-rift (middle Miocene.Holocene) units. The Hupo Fault and other faults newly defined in the Hupo Basin strike dominantly north and show a sense of normal displacement. Considering that the East Sea has been subjected to compression since the middle Miocene, we interpret that these normal faults were created during continental rifting in late Oligocene to early Miocene times. We suggest that the current ENE direction of maximum principal compressive stress observed in and around the Korean peninsula associated with the motion of the Amurian Plate induces the faults in the Hupo Basin to have reverse and right-lateral, strike-slip motion, when reactivated. A recent earthquake positioned on the Hupo Fault indicates that in the study area and possibly further in the eastern Korean margin, earthquakes would occur on the faults created during continental rifting in the Tertiary.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.2187-2191
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• 2003

In this paper, a x/y-axis accelerometer is fabricated, using the SBM process on a <111> SOI wafer. This fabrication method solves the problem of the footing phenomenon in the conventional SOI process for improved manufacturability and performance. The roughened lower parts as well as the loose silicon fragments due to the footing phenomenon are removed by the alkaline lateral etching step of the SBM process. The fabricated accelerometer has a demodulated signal-to-noise ratio of 92 dB, when 40Hz, 5 g input acceleration is applied. The noise equivalent input acceleration resolution and bandwidth are $125.59\;{\mu}g$ and over 100 Hz, respectively. The acceleration random walk is $12.5\;{\mu}g/\sqrt{Hz}$. The output linearity is measured to be 1.2 % FSO(Full Scale Output) at 40 Hz, and the input range is over ${\pm}\;10g$.

• Journal of Sensor Science and Technology
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• v.18 no.1
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• pp.33-41
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• 2009

A multilevel acoustic Fresnel lens (MAFL) for the ultrasonic imaging transducer of which center frequency is approximately 5.MHz was newly designed and fabricated. The phase level of the lens was 64, and the focal length and the aperture width were 30.mm and 11.mm, respectively. The characteristics of impulse response, acoustic field and imaging performance of the transducer attached the lens were compared with the transducer attached a conventional refraction type acoustic lens (RAL). The results show that the center frequency, the loop sensitivity, and the focal depth of the MAFL transducer were higher or larger than those of the RAL transducer by approximately 0.2.MHz, 1.4.dB, and 2.mm, respectively. Consequently, it was shown that the brighter acoustic images with higher lateral resolution and the increased imaging performance for deep targets can be obtained by using the MAFL transducer.

• 한국정보디스플레이학회:학술대회논문집
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• 2005.07b
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• pp.1033-1034
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• 2005

High resolution 2.1” QVGA LTPS LCD (190ppi) having high aperture ratio of 65% could be successfully developed using state-of-the-art SLS technology and active/gate storage structure. Cost effective P-MOS 6-Mask structure was used. Full gate and transmission gate circuits are integrated in the panel. The high aperture ratio was obtained by using active/gate capacitance structure, which can reduce storage capacitance area. The aperture ratio was increased to 65% from 49% of conventional gate/data capacitance structure. The brightness was increased from 180cd to 270cd without any degradation of optical properties such as contrast ratio, flicker or crosstalk.

• Journal of Ginseng Research
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• v.20 no.1
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• pp.65-71
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• 1996

This study was undertaken to evaluate the automatic decision-making on the grading of 6-year-old fresh ginseng (Panax ginseng C.A. Meyer) by an image analyzer. The best input method for the 6-year-old fresh ginseng was under condition of a low resolution (128u 128 pixel) and illumination direction from bottom to up (light box). It was possible to identify the main root, lateral root, and rhizome of fresh ginseng by application of OPEN process in a function of an image analyzer. Finally, we developed the grade decision-making programs, GinP-1. The fitness rates for the fresh ginseng standards which were classified by experts were 94.6, 80.6, 81.5, and 100.0% for 1st, 2nd, 3rd, and 4th grade of fresh ginseng, respectively, and the total time of decision-making was about 4.3 seconds per one root. The decision-making time was reduced to 0.8 seconds per one root by enhancemeat of the Image analyzer, which was tested by the technical company of the image analyzer,'Carl Zeiss (Germany). As a result of this study, the automatic decision-making on the grade of fresh gin send by image analyzer seems to have high possibility.