• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.78-87
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• 2017

Recently, the quality of a product or system has becoming increasingly important as it means customer satisfaction. The function, which is recognized as a nature of this quality, means how it functions well so it is the closest to the customer satisfaction. On the other hand, it is becoming more important as safety is closely related to destruction or human injury from accidents for engineers who handle large-scaled structures, such as ships. This study analyzed the function using quality function development (QFD) and considering the function and safety, which are being recognized as important in the structure. In addition, the safety and the quality analysis method based on the customers' needs was analyzed using failure mode and influence analysis (FMEA). In addition, the supplementary materials that are important in terms of the aspect of safety and function for the quality enhancement of a hatchway system were determined by applying a bulk carrier and hatchway. As a result, there are commonly understood items in important supplementary materials and parts, which are determined individually in terms of function and safety, because they can enhance both the function and safety simultaneously. This study shows that designers can improve the quality of products and systems by enhancing these supplementary materials and parts with greater interest.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.4
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• pp.172-179
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• 2014

HEVC (High Efficiency Video Coding) fine-tuned many existing coding tools and adopted also many new coding techniques. As a result, HEVC has accomplished about 2 times of compression efficiency enhancement compared to the existing video coding standard of H.264/AVC. One of the newly adopted tools in HEVC is the transform skip scheme which performs quantization without transform. This technique improves coding efficiency especially with computer-generated images. However, the unavailability of global or local properties of general video signals demands encoder to decide whether performing transform or not for each TU (Transform Unit). The necessity of computing rate-distortion costs for this decision is one reason to increase encoder complexity. In this paper, a fast transform skip mode decision method is proposed, which is based on the fast decision of rate-distortion cost calculation for transform skip mode, by considering frequency characteristics of residual signal. The proposed method can reduce $4{\times}4$ TU encoding time by about 27.1% with only about 0.03% consequential decrement in BDBR.

• The Korean Journal of Pharmacology
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• v.30 no.1
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• pp.67-73
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• 1994

Na-Ca exchange transports calcium ion either into (reverse mode Na-Ca exchange) or out of the cell (forward mode Na-Ca exchange) according to the direction of driving force produced by the changes in ratio of intra- and extra-cellular Na concentrations. Thus, Na-Ca exchange is regarded as the regulator of myocardial contraction. However, the existence of reverse mode Na-Ca exchange and its role in myocardial contraction is still questioned. Present study was performed to identify the presence of reverse mode Na-Ca exchange and its possible involvement in the regulation of myocardial contraction in rat heart. Using the left atria of rat, contraction was induced by electrical field stimulation (EFS, 0.5 msec duration and supramaximal voltage). Changing of the stimulation frequencies from resting 4 Hz to 0.4, 1 or 8 Hz caused typical negative staircase effect in twitch tension, but $^{45}Ca$ uptake showed bimodal increase. When the stimulation frequency was abruptly changed from 4 Hz to 0.4 Hz the atrial twitch tension showed three phased-enhancement, that is, the initial rapid increase (the first phase) followed by rapid decrease (the second phase) and stabilization (the third phase). $^{45}Ca$ uptake was equivalent to tension, i.e. initial significant increase in first 30 second and then decrease. Benzamil treatment abolished the first phase of increase in a dose dependent manner from $10^{-5}\;to\;3{\times}10^{-4}M.$ Bay k 8644 $(3{\times}10^{-5}M)$ treatment enhanced the inotropy induced by frequency reduction and abolished the second and third phase decreases. Benzamil treatment also suppressed the contraction stimulated by Bay K 8644. Although the contraction at 4 Hz stimulation was completely abolished by verapamil $3{\times}10^{-5}\;M$ pretreatment, the contraction reappeared as soon as the stimulation frequency was changed into 0.4 or 1 Hz and interstingly,$^{45}Ca$ uptake were significantly higher than no treatment. From these results, it is concluded that reduction of stimulation frequency causes calcium influx by the reverse mode Na-Ca exchange, resulting in initial rapid increase of twitch tension. then it turns into forward mode exchange to efflux the calcium, resulting in decrease of the twitch tension in left atria of rat.

• Journal of the Korean Society for Nondestructive Testing
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• v.20 no.4
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• pp.314-321
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• 2000

A gap between a $Al_2O_3/Fe$ thermite and lower head vessel is formed in the lower-plenum arrested vessel attack(LAVA) experiment which is the 1st phase study of simulation of naturally arrested vessel attack in vessel(SONATA-IV). The gap measurement using a conventional ultrasonic method would be lack of a reliability due to the structure complexity and the metallurgical grain size change of the lower head HAZ occurred by a thermite $Al_2O_3/Fe$ melt or a $Al_2O_3$ melt at $2300^{\circ}C$. The grain echoes having false signals and lower S/N ratio signals are detected due to a multiple scattering, a mode conversion and an attenuation of a ultrasonic resulted from at the interface of increased grain size zone. In this test, the signals pattern was classified to understand the behavior of the ultrasonic in a multi-layer specimen of solid-liquid-solid of assuming that the thermite and the lower head vessel is immersed. The polarity threshold algorithm of frequency diversity gives us the enhancement about 6dB of the ratio S/N.

• Journal of Broadcast Engineering
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• v.13 no.4
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• pp.501-515
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• 2008

Recently, as users' requests for high quality mobile multimedia services are rapidly increasing and additional bandwidth can be provided by adopting the hierarchical modulation transmission technology, the research on the Advanced Terrestrial DMB (AT-DMB) service using the SVC (Scalable Video Coding) scheme is being actively studied. But, in order to realize a compatible video service and to accelerate the successful standardization and commercialization, it is necessary to simplify the compatible encoder structure. In this parer, we propose a fast mode decision method by constraining the redundant coding modes in the spatial scalable encoder that keeps the current T-DMB video in base layer. The proposed method is based on the statistical characteristics of each coding mode at both base and enhancement layers, inter-layer predictions, which are derived by investigating macroblock-layer coding modes of the spatial scalable encoder's functional structure. Through computer simulations, it is shown that a simplified encoder model that reduces the heavy computational burden can be found, while keeping the objective visual quality very high.

• Journal of Korean Society for Atmospheric Environment
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• v.23 no.6
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• pp.675-688
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• 2007

To characterize organic and elemental carbon (OC and EC), and water-soluble organic carbon (WSOC) contents, daily $PM_{2.5}$ measurements were performed in August 2006 (summer) and Jan $11{\sim}Feb$ 12 2007 (winter) at an urban site of Gwangju. Daily size-segregated aerosol samples were also collected for WSOC analysis. No clear seasonal variations in EC and WSOC concentrations were observed, while seasonal differences in OC concentration, and OC/EC and WSOC/EC ratios were shown. The WSOC/OC ratio showed higher value in summer (0.56) than in winter (0.40), reflecting the greater enhancement of secondary WSOC formation at the site in summer. Secondary WSOC concentrations estimated using EC tracer method were in the range $0.0{\sim}2.1\;{\mu}g/m^3$ (average $0.42\;{\mu}g/m^3$) and $0.0{\sim}1.1\;{\mu}g/m^3\;(0.24\;{\mu}g/m^3)$, respectively, accounting for $0{\sim}51.6%$ (average 16.8%) and $0{\sim}52.5%$ (average 13.1 %) of the measured WSOC concentrations in summer and winter. Sometimes higher WSOC/OC ratio in winter than that in summer could be attributed to two reasons. One is that the stable atmospheric condition often appears in winter, and the prolonged residence time would strengthen atmospheric oxidation of volatile organic compounds. The other is that decrease of ambient temperature in winter would enhance the condensation of volatile secondary WSOC on pre-existing aerosols. In summertime, atmospheric aerosols and WSOC concentrations showed bimodal size distributions, peaking at the size ranges $0.32{\sim}0.56\;{\mu}m$ (condensation mode) and $3.2{\sim}5.6\;{\mu}m$ (coarse mode), respectively. During the wintertime, atmospheric aerosols showed a bimodal character, while WSOC concentrations showed a unimodal pattern. Size distributions of atmospheric aerosols and WSOC with a peak in the size range $0.32{\sim}0.56\;{\mu}m$ were observed for most of the measurement periods. On January 17, however, atmospheric aerosols and WOSC exhibited size distributions with modal peaks in the size range $1.0{\sim}1.8\;{\mu}m$, suggesting that the aerosol particles collected on that day could be expected to be more aged, i.e, longer residence time, than the aerosols at other sampling periods.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.14 no.2
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• pp.169-178
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• 2016

The properties of wastes for melting need to be considered to minimize the maintenance of refractory and to discharge the molten slags smoothly from a plasma torch melter. When the nonflammable wastes from nuclear facilities such as concrete debris, glass, sand, etc., are melted, they become acid slags with low basicity since the chemical composition has much more acid oxides than basic oxides. A molten slag does not have good characteristics of discharge and is mainly responsible for the refractory erosion due to its low liquidity. In case of a stationary plasma torch melter with a slant tapping port on the wall, a fixed amount of molten slags remains inside of tapping hole as well as the melter inside after tapping out. Nonmetallic slags keep the temperature higher than melting point of metal because metallic slags located on the bottom of melter by specific gravity difference are simultaneously melted when dual mode plasma torch operates in transferred mode. In order to minimize the refractory erosion, the compatible refractories are selected considering the temperature inside the melter and the melting behavior of slags whether to contact or noncontact with molten slags. An acidic refractory shall not be installed in adjacent to a basic refractory for the resistibility against corrosion.

• Journal of Korea Society of Industrial Information Systems
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• v.21 no.1
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• pp.61-70
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• 2016

This paper describes a new PMU(parametric measurement unit) design technique for automatic test equipment(ATE). Only one DDA(differential difference amplifier) is used to force the test signals to DUT(device under test), while conventional design uses two or more amplifiers to force test signals. Since the proposed technique does not need extra amplifiers in feedback path, the proposed PMU inherently guarantees stable operation. Moreover, to measure the response signals from DUT, proposed technique also adopted only one DDA amplifier as an IA(instrument amplifier), while conventional IA uses 3 amplifiers and several resistors. The DDA adopted two rail-to-rail differential input stages to handle full-range differential signals. Gain enhancement technique is used in folded-cascode type DDA to get open loop gain of 100 dB. Proposed PMU design enables accurate and stable operation with smaller hardware and lower power consumption. This PMU is implemented with 0.18 um CMOS process and supply voltage is 1.8 V. Input ranges for each force mode are 0.25~1.55 V at voltage force and 0.9~0.935 V at current force mode.

• JSTS:Journal of Semiconductor Technology and Science
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• v.7 no.3
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• pp.196-208
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• 2007

An analytical model is proposed for an optically controlled Metal Semiconductor Field Effect Transistor (MESFET), known as Optical Field Effect Transistor (OPFET) considering the diffusion fabrication process. The electrical parameters such as threshold voltage, drain-source current, gate capacitances and switching response have been determined for the dark and various illuminated conditions. The Photovoltaic effect due to photogenerated carriers under illumination is shown to modulate the channel cross-section, which in turn significantly changes the threshold voltage, drainsource current, the gate capacitances and the device switching speed. The threshold voltage $V_T$ is reduced under optical illumination condition, which leads the device to change the device property from enhancement mode to depletion mode depending on photon impurity flux density. The resulting I-V characteristics show that the drain-source current IDS for different gate-source voltage $V_{gs}$ is significantly increased with optical illumination for photon flux densities of ${\Phi}=10^{15}\;and\;10^{17}/cm^2s$ compared to the dark condition. Further more, the drain-source current as a function of drain-source voltage $V_{DS}$ is evaluated to find the I-V characteristics for various pinch-off voltages $V_P$ for optimization of impurity flux density $Q_{Diff}$ by diffusion process. The resulting I-V characteristics also show that the diffusion process introduces less process-induced damage compared to ion implantation, which suffers from current reduction due to a large number of defects introduced by the ion implantation process. Further the results show significant increase in gate-source capacitance $C_{gs}$ and gate-drain capacitance $C_{gd}$ for optical illuminations, where the photo-induced voltage has a significant role on gate capacitances. The switching time ${\tau}$ of the OPFET device is computed for dark and illumination conditions. The switching time ${\tau}$ is greatly reduced by optical illumination and is also a function of device active layer thickness and corresponding impurity flux density $Q_{Diff}$. Thus it is shown that the diffusion process shows great potential for improvement of optoelectronic devices in quantum efficiency and other performance areas.

• Transactions of The Korea Fluid Power Systems Society
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• v.4 no.1
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• pp.18-24
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• 2007

The continuously variable transmission (CVT) of which speed ratio can change continuously in a fixed range has the benefits of low fuel consumption and exhaust gas because it enables the engine of a vehicle to operate in a high efficiency range regardless of vehicle speed. The speed ratio of belt type CVT is controlled by adjusting line pressure. The one of the line pressure control methods, mechanical-hydraulic control is usually adopting VDT's control method, in which the secondary solenoid valve has two functions both a regulator and a line pressure controller. However, this control method could not show the high performance of CVT with optimal driving capability because of the limitation of simple control algorithm, and it could not gain market share sufficiently in spite of the advantage of CVT with low fuel consumption. On the other hand, the electro-hydraulic control method gives the enhancement of power performance and low fuel consumption by implementing various driving mode using the proportional control or PWM control. The key of CVT technique is to develop a control algorithm of the electro-hydraulic solenoid valve in order to implement the speed ratio efficiently. In this paper, the line pressure control algorithm is proposed and the hydraulic system is controlled using metal belt type CVT test rig and the embedded ECU platform.