• Transactions of the Korean Society of Pressure Vessels and Piping
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• v.12 no.1
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• pp.134-140
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• 2016

The Control Rod Assembly (CRA) controls the reactor power by adjusting its position in the reactor core during normal operation and should be quickly inserted into the reactor core by free drop under scram condition to shut down chain reactions. Therefore, the drop time of the CRA is one of important factors for the safety of the nuclear reactor and must be experimentally verified. This study presents the drop performance test of the CRA which has been conceptually designed for the Proto-type Generation IV Sodium-cooled Fast Reactor. During the test, the CRA was free dropped from a height of 1 m under different flow rate conditions and its drop time was measured. The results showed that the drop time of the CRA increased as the flow rate increased; the average drop times of the CRA were approximately 1.527 seconds, 1.599 seconds and 1.676 seconds at 0%, 100% and 200% of design flow rates, respectively.

• Journal of Technology Innovation
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• v.8 no.2
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• pp.97-117
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• 2000

TOEM strategy is widely used in Japan and Korea because of the diverse advantages such as cost sharing, technology transfer, equipment lease and base technology acquisition between parent company and OEM supplier. There are, however, some disadvantages that (1)OEM suppliers are likely to be reactive to environmental changes and (2) may have difficulty in building competitive position and long-term growth. When the parent company relocates its plant to foreign countries to achieve lower labor cost or to enhance value added this change will affect directly the OEM supplier's outcome. The parent company's divestiture from existing businesses will also affect the OEM supplier. For the OEM supplier to survive in face of these strategic changes it must enter the new countries with the parent company. Alternatively, the OEM supplier must actively diversify its technologies based on its core capabilities of existing product and process technologies and seek new business arenas. The strategy of aligning its businesses with the parent company's new business strategy allows the OEM supplier to share the new market while it requires the OEM supplier to develop core capabilities. In Korea many small and medium sized OEM suppliers are dependent on a few large companies. For the industry structure in Korea where industry concentration is extremely high OEM suppliers should move away from the past strategy, where they are dependent on the parent company's low profitability businesses. They should actively enter new businesses for which parent companies enter to achieve long-term growth.

• 한국해양학회지
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• v.23 no.3
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• pp.97-109
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• 1988

The wind stress and the wind-stress curl over the East Sea of Korea are computed from the ship-observed wind data by the FRDA. In order to emphasize the role of the wind in determining the upper-layer structure, rather persistent and strong winds are selected based on the wind-rose data. The monthly averaged wind stresses are comparable in size with the average value over the Japan Sea. But the monthly averaged magnitude of the wind-stress curl is very large compared to the one over the Japan Sea. This may be due to the spatial variation of the wind speeds influenced by the local orography. The wind-driven upper-layer thickness over the East Sea suggests that the site of deep upper layer indeed exists regardless of season but the position does not appear to be fixed. The convergence of warm surface water driven by the wind could be referred as the warm core.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.144-146
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• 2005

Dual electromagnetic sensor is used for sensing the weld line. The sensor consists of excitation and two sensing coil wound over the ferro-magnetic core. By using the dual sensor, the effect of noise is minimized. It is based on the generation of eddy currents in the welding plate by passing current through the excitation coil. The sensor can be used to track the butt joints having no gap between them, where a vision based sensor fails to track. Sensor sensitivity depends on the number of coil turns, frequency of excitation, distance of a sensor from the work piece, diameter of core, etc. The whole system consists of a sensor, a signal processing board, a motion controller and a personnel computer (PC). The raw sensor signal is processed using the signal processing board. It consists of amplification, rectification, filtering, averaging, offset adjustment, etc. Based on sensor data, the motion controller adjusts the position of a welding torch.

• Journal of The Korean Astronomical Society
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• v.31 no.2
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• pp.117-125
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• 1998

We have observed the 10-9 transitions of $HC_3N$ and its $^{13}C$ substitutes ($H^{13}CCCN,\;HC^{13}CCN$, and $HCC^{13}CN$), and the vibration ally excited 12-11 ($v_r=1$) $HC_3N$ transition toward the Sgr B2 molecular cloud. The observed $HC_3N$ emission shows an elongated shape around the Principal Cloud ($\~$4.5 pc in R.A. $\times$ 7.4 pc in Decl.). The optically thin $H^{13}CCCN$ line peaks around the (N) core and we derive the total column density $N(H^{13}CCCN) = 4 {\times}10^{13} cm^{-2}$ at this position. Toward the 2' N cloud which shows the peculiar chemistry, the $HC_3N$ lines show enhancements compared to the extended envelope. The shocks of the 2' N may have resulted in the enhancement of $HC_3N$. The hot component of $HC_3N$ is strongly concentrated around the (N) core and its HPW is $\~$0.9 pc in diameter. We derive the lower limit of the abundance ratio $N(HC_3N)/N(H^{13}CCCN)$ to be larger than 40 in most regions except the (M) and (N) cores. The fractionation processes of $^{13}C $at this region may not be as effective as previously reported.

• Nuclear Engineering and Technology
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• v.22 no.4
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• pp.371-379
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• 1990

The Xenon spatial oscillation may give rise to operational difficulties in a nuclear power plant. In this study, in order to investigate the Xenon instability for a PWR, the frequency-domain technique is adopted by using Generalized Nyquist Criterion, which is more general and suitable for the multi-input/multi-output system. Also linearized modal fluxes are obtained by a modal expansion. This model has been implemented to test the axial Xenon stability of YGN-1 unit against the changes in plant operating parameters ; power level, control rod position, and core average burnup. The results show that the increase of power level and the deeper insertion of control rod have the destabilizing effect, and that the burnup progress makes the core less stable. Also the results show that the overestimation due to modal interaction was found not to be significant.

• Journal of Korea Foundry Society
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• v.42 no.1
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• pp.61-66
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• 2022

Hydraulic units are important components of agricultural and construction machinery, and thus require high-quality castings. However, gas defects occurring inside the sand cores of the castings due to the resin used is a problem. This study therefore aimed to develop a casting simulation method that can clarify the gas defect positions. Gas defects are thought to be caused by gas generated after the molten metal fills up the mold cavity. The gas constant is the most effective factor for simulating this gas generated from sand cores. It is calculated by gas generating temperature and analysis of composition in the inert gas atmosphere modified according to the mold filling conditions of molten metal. It is assumed that gases generated from the inside of castings remain if the following formula is established. [Time of occurrence of gas generation] + [Time of occurrence of gas floating] > [Time of occurrence of casting surface solidification] The possibility of gas defects is evaluated by the time of occurrence of gas generation and gas floating calculated using the gas constant. The residual position of generated gases is decided by the closed loops indicating the final solidification location in the casting simulation. The above procedure enables us to suggest suitable casting designs with zero gas defects, without the need to repeat casting tests.

• Journal of Sensor Science and Technology
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• v.32 no.2
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• pp.67-74
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• 2023

A microfluidic paper-based analytical device (µPAD) is proposed for the selective detection of ammonia in water by using the modified Berthelot reagent and a fluidic channel consisting of hollow paper. The modified Berthelot reagents were uniformly dispersed in cyclohexane and then immobilized in a detection zone of the µPAD. The loading position of the reagents and the type of a sample flow channel were optimized to achieve a sensitive ammonia detection within a short analytical time. The NH₃ µPAD exhibits a linear colorimetric response to the concentration of ammonia dissolved in water in the range of 1-100 mg L^-1, and its limit-of-detection is 1.75 mg L^-1. In addition, the colorimetric response was not influenced by the addition of 100 mg L^-1 nitrogen containing compounds (sodium nitrate, sodium nitrite, uric acid, hydroxylamine, butylamine, diethylamine) or inorganic salts (NaCl, Na₂HPO₄), presenting the enough selectivity in the detection of water-dissolved ammonia against possible interferents.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.6
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• pp.367-373
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• 2023

600 MPa-grade deformed bar samples were manufactured by conventional hot rolling and subsequent Tempcore heat treatment processes. Considering the short-time water quenching step of the Tempcore process for hot-rolled steel, it is inevitable that the temperature profile of the deformed bar depends strongly on its position throughout the sample thickness. As a result, its microstructure can be easily divided into two regions, the surface and the core regions. The former is expected to have a fresh martensite microstructure under rapid cooling conditions, but self-tempering occurs due to the intense heat flow from the hot core region after the process. The latter is generally known to exhibit a mixed microstructure of ferrite and pearlite due to its slow cooling rate. In this study, detailed microstructural evolutions were examined through the thickness direction. The large variation of the microstructure through the thickness direction in the deformed bar samples is partly due to the easy carbon diffusion from the limited additions of alloying elements.

• Cartoon and Animation Studies
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• s.39
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• pp.393-412
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• 2015

See and feel the emotion recognition is the image of a person variously changed according to the environment, personal disposition. Thus, the image recognition has been focused on the emotional sensibilities computer you want to control the number studies. However, existing emotional computing model is numbered and the objective is clearly insufficient measurement conditions. Thus, through quantifiable image Emotion Recognition and emotion computing, is a study of the situation requires an objective assessment scheme. In this paper, the sensitivity was represented by numbered sizes quantified according to the image recognition calculation emotion. So apply the principal attributes of the color image emotion recognition as a configuration parameter. In addition, in calculating the color sensitivity by applying a digital computing focused research. Image color emotion computing research approach is the color of emotion attribute, brightness, and saturation reflects the weighted according to importance to the emotional scores. And free-degree by applying the sensitivity point to the image sensitivity formula (X), the tone (Y-axis) is calculated as a number system. There pleasure degree (X-axis), the tension and position the position of the image point that the sensitivity of the emotional coordinate crossing (Y-axis). Image color coordinates by applying the core emotional effect of Russell (Core Affect) is based on the 16 main representatives emotion. Thus, the image recognition sensitivity and compares the number size. Depending on the magnitude of the sensitivity scores demonstrate this sensitivity must change. Compare the way the images are divided up the top five of emotion recognition emotion emotions associated with 16 representatives, and representatives analyzed the concentrated emotion sizes. Future studies are needed emotional computing method of calculation to be more similar sensibility and human emotion recognition.