• Nuclear Engineering and Technology
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• v.23 no.1
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• pp.56-65
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• 1991

The LOFT LOCE L2-3 was simulated using the RELAP5/MOD2 Cycle 36.04 code to assess its capability in predicting the thermal-hydraulic phenomena in LBLOCA of a PWR. The reactor vessel was simulated with two core channels and split downcomer modeling for a base case calculation using the frozen code. The result of the base calculation showed that the code predicted the hydraulic behavior, and the blowdown thermal response at high power region of the core reasonably and that the code had deficiencies in the critical How model during subcooled-two-phase transition period, in the CHF correlation at high mass flux and in the blowdown rewet criteria. An overprediction of coolant inventory due to the deficiencies yielded the poor prediction of reflood thermal response. Improvement of the code, RELAP5 / MOD2 Cycle 36.04, based on the sensitivity study increased the accuracy of the prediction of the rewet phenomena.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.1
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• pp.40-48
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• 2021

Through a series of bollard pull tests of a propeller in partially submerged condition, thrust, torque, and shaft excitation force of a conventional propeller model were measured using a six-component load cell. By variation of the Weber number and Reynolds number, a consistent towing tank model test condition was derived. The effects of propeller immersion depth on the ventilation behavior and change of force and moment acting onto the propeller shaft were investigated. The decrease in thrust owing to the inception of ventilation was confirmed, and a large degree of dispersion of the thrust and torque coefficients were also observed in the transition region where the blade tip was under the water surface. The shaft excitation force was derived from the force and moment onto the propeller shaft.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.12
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• pp.986-993
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• 2018

Lateral thrust jet has better maneuverability performance than the control surface like the conventional fin for attitude control or orbital transition of guided weapons. However, in the supersonic region, a jet interaction flow occurs due to the lateral thrust jet during flight, and a complicated flow structure is exhibited by the interaction of the shock wave, boundary layer flow, and the vortex flow. Especially, hit-to-kill interceptors require precise control and maneuvering, so it is necessary to analyze the effect of jet interaction flow. Conventional jet interaction analyses were performed under low altitude conditions, but there are not many cases in the case of medium altitude condition, which has different flow characteristics. In this study, jet interaction flow analysis is performed on the lateral jet controlled interceptor operating at medium altitude. Based on the results, the structural characteristics of the flow field and the changes of aerodynamic coefficient are analyzed.

• Journal of Broadcast Engineering
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• v.23 no.6
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• pp.824-835
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• 2018

In this study, the impact on the number of cable TV subscribers as well as the profit of cable TV has been examined, and the impact on enlarging the digital broadcast viewing rights of cable TV subscribers and viewers' welfare has also been examined. We investigated the trends in the number of analog and 8VSB subscribers and revenue of cable TV operators by region and analyzed based on changes in the number of channels provided by each operator. The results show that analog subscribers and digital subscribers are delaying their departure through 8VSB conversion, and VOD subscription fees and home shopping transmission fees have a significant impact on operating profit. Subscribers, as they switched over to 8VSB, have become able to view channels of various genres with clear picture quality for a same subscription fee, and the program providers could offer programs to more customers. The government's deregulation policy due to the changes in broadcasting environment led to the facilitation of digital conversion of Pay-TV and improvement of viewers' welfare.

• Korean Journal of Materials Research
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• v.29 no.9
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• pp.559-566
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• 2019

$Lu(Nb,Ta)O_4:Eu^{3+}$ powders are synthesized by a solid-state reaction process using LiCl and $Li_2SO_4$ fluxes. The photoluminescence (PL) excitation spectra of the synthesized powders consist of broad bands at approximately 270 nm and sharp peaks in the near ultraviolet region, which are assigned to the $Nb^{5+}-O^{2-}$ charge transfer of $[NbO_4]^{3-}$ niobates and the f-f transition of $Eu^{3+}$, respectively. The PL emission spectra exhibit red peaks assigned to the $^5D_0{\rightarrow}^7F_J$ transitions of $Eu^{3+}$. The strongest peak is obtained at 614 nm ($^5D_0{\rightarrow}^7F_2$), indicating that the $Eu^{3+}$ ions are incorporated into the $Lu^{3+}$ asymmetric sites. The addition of fluxes causes the increase in emission intensity, and $Li_2SO_4$ flux is more effective for enhancement in emission intensity than is LiCl flux. The substitution of $Ta^{5+}$ for $Nb^{5+}$ results in an increase or decrease in the emission intensity of $LuNb_{1-x}Ta_xO_4:Eu^{3+}$ powders, depending on amount and kind of flux. The findings are explained using particle morphology, modification of the $[NbO_4]^{3-}$ structure, formation of substructure of $LuTaO_4$, and change in the crystal field surrounding the $Eu^{3+}$ ions.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1821-1833
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• 2021

The gas-liquid counter-current flow limitation (CCFL) is closely related to efficient and safety operation of many equipment in industrial cycle. Air-water countercurrent flow experiments were performed in a tube with diameter of 25 mm to understand the triggering mechanism of CCFL. A parallel electrode probe was utilized to measure film thickness whereby the time domain and frequency domain characteristics of liquid film was obtained. The amplitude of the interface wave is small at low liquid flow rate while it becomes large at high liquid flow rate after being disturbed by the airflow. The spectral characteristic curve shows a peak-shaped distribution. The crest exists between 0 and 10 Hz and the amplitude decreases with the frequency increase. The analysis of visual observation and characteristic of film thickness indicate that two flooding mechanisms were identified at low and high liquid flow rate, respectively. At low liquid flow rate, the interfacial waves upward propagation is responsible for the formation of CCFL onset. While flooding at high liquid flow rate takes place as a direct consequence of the liquid bridging in tube due to the turbulent flow pattern. Moreover, it is believed that there is a transition region between the low and high liquid flow rate.

• 지역과문화
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• v.8 no.1
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• pp.25-53
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• 2021

Based on the assumption that understandings and practices have been shifted in accordance with the historical context, this study aims to propose future policies to localize cultural diversity. First, in this study, it is necessary for the concept of cultural diversity, which came from political struggles, to understand and practice cultural diversity in the historical context by analyzing the multilayer aspects of policy practices. Second, through the case study of Jeonlabuk-do, by reviewing the discrimination experienced by social minorities and the perception of professionals related to culture policies in the region, this study represents to understand and practice of cultural diversity in the multi-layed way, even in the local. Lastly, it suggests some specific future policies to be considered when implicating the policies of culture diversity in respond to the limits of current government policies, including: decentralization of policies, enhancing local policies, transition from 'politics of distribution' to 'politics of recognition', an interculturalist approach that promotes contact rather than separation

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.34-34
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• 2023

The Chah-Nimeh reservoirs, which are a sort of natural lakes located in the border of Iran and Afghanistan, are the main drinking and agricultural water resources of Sistan arid region. Considering the occurrence of intense seasonal wind, locally known as levar wind, this study aims to explore the possibility to provide a TSM (Total Suspended Matter) monitoring model of Chah-Nimeh reservoirs using multi-temporal satellite images and in-situ wind speed data. The results show that a strong correlation between TSM concentration and wind speed are present. The developed empirical model indicated high performance in retrieving spatiotemporal distribution of the TSM concentration with R²=0.98 and RMSE=0.92g/m³. Following this observation, we also consider a machine learning-based model to predicts the average TSM using only wind speed. We connect our in-situ wind speed data to the TSM data generated from the inversion of multi-temporal satellite imagery to train a neural network based mode l(Wind2TSM-Net). Examining Wind2TSM-Net model indicates this model can retrieve the TSM accurately utilizing only wind speed (R²=0.88 and RMSE=1.97g/m³). Moreover, this results of this study show tha the TSM concentration can be estimated using only in situ wind speed data independent of the satellite images. Specifically, such model can supply a temporally persistent means of monitoring TSM that is not limited by the temporal resolution of imagery or the cloud cover problem in the optical remote sensing.

• The Journal of Korean-Japanese National Studies
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• no.34
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• pp.5-40
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• 2018

This paper is to take note of national, social and economic movement, social & economic publicness of religion surrounding Yeonggwang, Joennam around 1910s. At first I would like to look at this period because regional society was in the middle of change of large transition before and after Japan's forced occupation of Korea in 1910s and March 1st Independence Movement in 1919. In particular we focus on spatially Yeonggwang in Joennam because this area is not only called as advent area of Buddhism earlier but also is unique regional culture and ideological topology where Donghak, Protestantism, Catholic, Institute of Won Buddhism and etc. Through casting light upon the above, it is expected to offer one clue for the question of internalizing value to be sought for in the national and social and economic movement by Korean religion around 1910 and public goods in the strategy and tactics to be selected and further publicness and practice lying in their awareness and behavior. In particular it is thought to have advanced the accumulation of case study of Yeonggwang in Joennam with representative 'place-ness' related to this. Along with this it is considered that our challenge is to restore and casting light again on common foundation of existence shape and publicness of various religions in the middle of national and social movement and economic movement in Yeonggwang of Joennam area. In other words, we expect that religions will continue individual efforts and common practices to urge social justice for historic and public value based on common good encompassing historic value, in other words, individual responsibility and social justice among social and economic conditions originated from Japanese colonial era.

• Journal of Ginseng Research
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• v.47 no.3
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• pp.440-447
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• 2023

Background: The human hair follicle undergoes cyclic phases-anagen, catagen, and telogen-throughout its lifetime. This cyclic transition has been studied as a target for treating hair loss. Recently, correlation between the inhibition of autophagy and acceleration of the catagen phase in human hair follicles was investigated. However, the role of autophagy in human dermal papilla cells (hDPCs), which is involved in the development and growth of hair follicles, is not known. We hypothesized that acceleration of hair catagen phase upon inhibition of autophagy is due to the downregulation of Wnt/β-catenin signaling in hDPCs, and that components of Panax ginseng extract can increase the autophagic flux in hDPCs. Methods: We generated an autophagy-inhibited condition using 3-methyladenine (3-MA), a specific autophagy inhibitor, and investigated the regulation of Wnt/β-catenin signaling using the luciferase reporter assay, qRT-PCR, and western blot analysis. In addition, cells were cotreated with ginsenoside Re and 3-MA and their roles in inhibiting autophagosome formation were investigated. Results: We found that the unstimulated anagen phase dermal papilla region expressed the autophagy marker, LC3. Transcription of Wnt-related genes and nuclear translocation of β-catenin were reduced after treatment of hDPCs with 3-MA. In addition, treatment with the combination of ginsenoside Re and 3-MA changed the Wnt activity and hair cycle by restoring autophagy. Conclusions: Our results suggest that autophagy inhibition in hDPCs accelerates the catagen phase by downregulating Wnt/β-catenin signaling. Furthermore, ginsenoside Re, which increased autophagy in hDPCs, could be useful for reducing hair loss caused by abnormal inhibition of autophagy.