• The Bulletin of The Korean Astronomical Society
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• v.42 no.2
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• pp.79.3-80
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• 2017

Molecular clouds are the sites of stellar birth. Turbulence is a natural phenomenon in molecular clouds, which largely determines the density and velocity fields. Additionally turbulent energy dissipation can affect the gas kinetic temperature via shocks. Turbulence thus controls the mode and tempo of star formation. However, despite its important role in star formation, the properties of turbulence remain poorly understood. As part of the Taeduk Radio Astronomy Observatory (TRAO) Key Science Program (KSP), "Mapping turbulent properties of star-forming molecular clouds down to the sonic scale (PI: Jeong-Eun Lee)", we have been mapping two star-forming clouds, the Orion A and the ${\rho}$ Ophiuchus molecular clouds in 3 sets of lines (13CO 1-0/C18O 1-0, HCN 1-0/HCO+ 1-0, and CS 2-1/N2H+ 1-0) using the TRAO 14-m telescope. We apply a Principal Component Analysis (PCA), which is an useful tool to represent turbulent power spectrum. We will present the preliminary results of our TRAO KSP toward two regions: OMC 1-4 in the Orion A cloud, and L1688 in the ${\rho}$ Ophiuchus cloud.

• Journal of The Korean Astronomical Society
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• v.39 no.4
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• pp.107-114
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• 2006

We conducted an analysis of a selected region from the FCRAO $^{12}CO$ Outer Galaxy Survey. The selected region is located between galactic longitude $117^{\circ}$ and $124^{\circ}$ with the velocity of -23 km $s^{-1}. Molecular clouds in this region show a peculiar velocity field, protruding from the Local Arm population. The selected region is divided into 7 clouds by spatial location. Though we were not able to identify the direct driving source for peculiar velocity of our target region, we find that there are several internal YSOs or star forming activities; there are many associated sources like an outflows, a high-mass protostellar candidate and $H_2O$ maser sources. We attribute the driving energy source to older generation of episodic star formation. Masses of main clouds(cloud 1-4) estimated using a conversion factor from $^{12}CO$ luminosity are larger than $10^4M_{\odot}$. Other components have a small mass as about $10^3M_{\odot}$. Among main clouds, cloud 2 and 4 seem to be marginally gravitational bound systems as their ratio of $M_{CO}$ to $M_{VIR}$ is about $2{\sim}3$, and the internal velocity dispersion is larger than the centroid velocity dispersion. Total mass estimated using a conversion factor from $^{12}CO$ luminosity is $7.9{\times}10^4M_{\odot}$.

• Journal of the Semiconductor & Display Technology
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• v.16 no.1
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• pp.22-28
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• 2017

The result of stripping process for the removal of the post etch/ash Photoresist (PR) residue on an aluminum patterned wafer by using supercritical $CO_2$ ($sc-CO_2$) mixture, was investigated by scanning of electron microscope (SEM) inspection of wafer, measuring the cloud points and visual observation of the state of $sc-CO_2$ mixtures. It was found that $sc-CO_2$ mixtures were made by mixing additives and $sc-CO_2$ should form homogeneous and transparent phase (HTP) in order to effectively and uniformly remove the post etch/ash PR residue on the aluminum patterned wafer using them. The additives were formulated by mixing and co-solvents like an amine compound and fluorosurfactants used as HTP agents, and the PR residue on the wafer were able to be rapidly and effectively removed using the $sc-CO_2$ mixture of HTP. The five kinds of additives were formulated by the recipe of mixing co-solvents and surfactants, which were able to remove PR residue on the wafer by mixing with $sc-CO_2$ at the stripping temperature range from 40 to $80^{\circ}C$. The five kinds of $sc-CO_2$ mixtures which were named as PR removers were made, which were able to form HTP within the above described stripping temperature. The cloud points of $sc-CO_2$ mixtures were measured to find correlation between them and HTP.

• Journal of Environmental Science International
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• v.16 no.3
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• pp.261-267
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• 2007

In this study, the Slab Ocean Model (SOM) is coupled with an Atmospheric General Circulation Model (AGCM) which developed in University of Kangnung based on the land surface model of Biosphere-Atmosphere Transfer Scheme (BATS). The purposes of this study are to understand radiative role of clouds considering of the atmospheric feedback, and to compare the Clouds Radiative Forcing (CRF) come from the analyses using the clear-cloud sky method and CGCM. The new CGCM was integrated by using two sets of the clouds with radiative role (EXP-A) and without radiative role (EXP-B). Clouds in this two cases show the negative effect $-26.0\;Wm^{-2}$ of difference of radiation budget at top of atmosphere (TOA). The annual global means radiation budget of this simulation at TOA is larger than the estimations ($-17.0 Wm^{-2}$) came from Earth Radiation Budget Experiment (ERBE). The work showed the surface negative effect with $-18.6 Wm^{-2}$ in the two different simulations of CRF. Otherwise, sensible heat flux in the simulation shows a great contribution with positive forcing of $+24.4 Wm^{-2}$. It is found that cooling effect to the surface temperature due to radiative role of clouds is about $7.5^{\circ}C$. From this study it could make an accurate of the different CRF estimation considering either feedback of EXP-B or not EXP-A under clear-sky and cloud-sky conditions respectively at TOA. This result clearly shows its difference of CRF $-11.1 Wm^{-2}$.

• Korean Journal of Remote Sensing
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• v.25 no.2
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• pp.193-203
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• 2009

Snow cover is one of the important parameters since it determines surface energy balance and its variation. To classify snow and cloud from satellite data is very important process when inferring land surface information. Generally, misclassified cloud and snow pixel can lead directly to error factor for retrieval of surface products from satellite data. Therefore, in this study, we perform algorithm for detecting snow cover area with remote sensing data. We just utilize visible reflectance, and infrared channels rather than using NDSI (Normalized Difference Snow Index) which is one of optimized methods to detect snow cover. Because COMS MI (Meteorological Imager) channels doesn't include near infra-red, which is used to produce NDSI. Detecting snow cover with visible channel is well performed over clear sky area, but it is difficult to discriminate snow cover from mixed cloudy pixels. To improve those detecting abilities, brightness temperature difference (BTD) between 11 and 3.7 is used for snow detection. BTD method shows improved results than using only visible channel.

• Journal of Korean Society for Quality Management
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• v.49 no.4
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• pp.551-567
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• 2021

Purpose: The purpose of this paper is to present implications by analyzing research trends on smart factories by text analysis and visual analysis(Comprehensive/ Fields / Years-based) which are big data analyses, by collecting data based on previous studies on smart factories. Methods: For the collection of analysis data, deep learning was used in the integrated search on the Academic Research Information Service (www.riss.kr) to search for "SMART FACTORY" and "Smart Factory" as search terms, and the titles and Korean abstracts were scrapped out of the extracted paper and they are organize into EXCEL. For the final step, 739 papers derived were analyzed using the Rx64 4.0.2 program and Rstudio using text mining, one of the big data analysis techniques, and Word Cloud for visualization. Results: The results of this study are as follows; Smart factory research slowed down from 2005 to 2014, but until 2019, research increased rapidly. According to the analysis by fields, smart factories were studied in the order of engineering, social science, and complex science. There were many 'engineering' fields in the early stages of smart factories, and research was expanded to 'social science'. In particular, since 2015, it has been studied in various disciplines such as 'complex studies'. Overall, in keyword analysis, the keywords such as 'technology', 'data', and 'analysis' are most likely to appear, and it was analyzed that there were some differences by fields and years. Conclusion: Government support and expert support for smart factories should be activated, and researches on technology-based strategies are needed. In the future, it is necessary to take various approaches to smart factories. If researches are conducted in consideration of the environment or energy, it is judged that bigger implications can be presented.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.6
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• pp.1105-1112
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• 2022

Field data monitoring systems such as renewable energy generation and smart farm integrated control are developing from PC and server to mobile first, and various wireless communication and application services have emerged with the development of IoT technology. Low-power wide-area networks are services optimized for low-power, low-capacity, and low-speed data transmission, and data collected in the field is transmitted to designated storage servers or cloud-based data platforms, enabling data monitoring. In this paper, we implement an IoT repeater that collects field data with a single device and transmits it to a wireless carrier cloud data flat using a low-power wide-area network, and a monitoring app using it. Using this, the system configuration is simpler, the cost of deployment and operation is lower, and effective data accumulation is possible.

• Journal of the Korea Institute of Building Construction
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• v.24 no.3
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• pp.319-329
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• 2024

This study examined domestic and international regulations concerning concrete unit weight, along with an evaluation of unit weight in concrete poured on construction sites. Fluctuations in unit weight were observed to correlate with concrete quality issues such as material separation, bleeding, and latency. A word cloud analysis, centered on the concept of concrete quality, further highlighted the significant influence of unit weight. Comparative analysis between Korea and Japan revealed few substantial differences in unit weight management and measurement techniques. However, calculation of concrete unit weight at delivery, using the unit volume mass method, indicated considerable variability among random on-site samples. Notably, the unit weight often exceeded the recommended standard. These findings emphasize the necessity for strict adherence to unit weight standards by all stakeholders involved in concrete production and construction, including ready-mix concrete (REMICON) producers, construction firms, and inspectors. To ensure consistent quality of cast concrete on-site, the establishment of a more comprehensive and practical system is recommended, incorporating measures such as on-site inspections.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2494-2499
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• 2007

Self-blast circuit breakers utilize the energy dissipated by the arc itself to create the required conditions for arc quenching during the current zero. The high-current simulation provides information about the mixing process of the hot PTFE cloud with $SF_6$ gas which is difficult to access for measurement. But it is also hard to simulate flow phenomenon because the flow in interrupter with high current, $SF_6$-PTFE mixture vapor and complex physical behavior including radiation, calculation of electric field. Using a commercial computational fluid dynamics(CFD) package, the conservation equation for the gas and temperature, velocity and electric fields within breaker can be solved. Results show good agreement between the predicted and measured pressure rise in the thermal chamber.

• Journal of The Korean Astronomical Society
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• v.38 no.2
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• pp.291-293
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• 2005

Using 13.7 m telescope of Qinghai station of NAO, PMO at Delin Ha, 43 IRAS sources were mapped with $^{13}CO\;J=1-0\;C^{18}O\;J=1-0$ and CO J=1-0. Each source has one or more cores. The distances of these cores range from 1 pc to several pc, and the masses from $10^2\;M_{\bigodot}$ to $10^5\;M_{\bigodot}$. High velocity outflows were detected. The mass, momentum and energy of these massive cores are larger than those of the low mass ones. With radio, IRAS, MSX data, stellar source distribution were investigated, and sourceless cores that deviate from infrared sources were identified. They are potential high mass star formation sites.