• The Journal of the Acoustical Society of Korea
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• v.39 no.6
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• pp.568-575
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• 2020

Ultrasound has been widely used in various industrial fields. One of challenging application areas is cooling microelectronics. Ultrasonic cooling systems can work with air, argon (Ar) and nitrogen (N₂) instead of conventional refrigerant such as freon gas, which can cause global warming. Furthermore, ultrasonic systems do not have moving parts, thus high durability can be obtained. So it is necessary to develop ultrasonic cooling systems due to environmental issues and durability points. In this paper, the design and fabrication processes are explained. When designing the system, a feasibility test was performed with a prototype cooler. Based on the result, finite element analysis with ANSYS software was performed. The predicted anti-resonance frequency for a piezoelectric actuator was 34.8 kHz, which was in good agreement with the experimental result of 34.6 kHz with 0.6% error. In addition, the predicted anti-resonance frequency for the ultrasonic waveguide was 39.4 kHz, which also agreed well with the experimental value of 39.8 kHz with 1.0% error. Based on these results, the developed ultrasonic waveguide might be applicable in microchip cooling.

• Informatization Policy
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• v.26 no.4
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• pp.62-84
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• 2019

The purpose of this study is to present improvement measures for youth activity policies that can change the youth activity programs, equipment and facility operation and leaders in order to cultivate youth capacities suitable for the intelligent information society. For this purpose, we conducted a literature study on the direction of youth activity policy changes with the forecasted social changes in the intelligence information society and an online survey and expert opinion surveys to identify how youth activity facilities are currently coping with the changes and to explore measures to improve youth activity policies. The research identified 17 policy tasks - 9 tasks for the program area, including 1) increase of intelligent information technology related programs, 2) increase of contents related to career resilience in career experience and training programs, and 3) systematic introduction and diffusion of STEAM and Maker education programs; 5 tasks for the equipment and facility operation area, including 1) strengthening cooperation network with external organizations related to the intelligent information technologies, 2) expansion of AR and VR technology application in activity program development, improvement and operation, and 3) big data building in the field of youth activities; and 3 tasks for the leaders area, including 1) extension of information provision on the intelligent information society to the leaders of the activity facilities, and 2) development of job models related to the intelligent information society and job training.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.24 no.2
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• pp.47-53
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• 2014

Three kinds of crystalline silicon have been used for the solar cell grade. First of all, single crystalline silicon is the main subject to enhance the production yield. Most of the efforts are focused on the control of the melt-crystal interface shape affected by the crystal-crucible rotation rate. The main subject in the multi-crystalline silicon ingot is the contamination control. Faster Ar gas flow above the melt surface will lower the carbon contamination in the crystal. And also, twin boundary electrically inactive is found to be more effective than grain boundary for the improvement of the MCLT. In the case of mono-like silicon material, propagation of the multi-crystalline silicon growing from the inner side crucible is the problem lowering the portion of the single crystalline part at the center of the ingot. Crystal growing apparatus giving higher cooling rate at the bottom and lower cooling rate at the side crucible was suggested as the optimum solution obtaining higher quality of the mono-like silicon ingot. Proper application of the seeds at the bottom of the crucible would be one of the solutions.

• Journal of Korean Medicine Rehabilitation
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• v.18 no.3
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• pp.51-65
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• 2008

Objectives : In order to investigate the effects of Soongijeseub-bang(Shunqichushi-fang)(here in after referred to SJB) on the obese gene and obese inhibitory, on C57BL/6 mice were induced by high fat diet. Methods : C57BL/6 mice were divided into three groups(normal, high fat diet with control, high fat diet with SJB extract) and fed for 15 weeks. And observed that, body weight change, final increase of body weight, the weight change of the adipocytes, the level change of ALT, AST, creatinine, total cholesterol, LDL-cholesterol, HDL-cholesterol, triglyceride, NEFA, glucose, the expression of ${\beta}3AR$, leptin, and $TNF-{\alpha}$ gene in primary adipocytes and adipocytes tissue. Results : The following results were obtained in this study. 1. SJB 500 mg/kg extract group showed considerable decrease in weight, the final increase of weight and the amount of adipocyte in weight. 2. All experimental group showed that the amount of ALT, AST, total cholesterol, LDL-cholesterol, triglyceride and NEFA were decreased considerably. SJB 500 mg/kg extract group showed the amount of HDL-cholesterol and leptin were increased considerably. 3. All experimental group showed that the revelation of ${\beta}3AR$ in primary adipose cell and 3T3-L1 cell were increased considerably, and that the revelation of leptin in primary adipose cell and 3T3-L1 cell were decreased considerably. SJB $100{\mu}{\ell}/m{\ell}$ extract group showed that the revelation of $TNF-{\alpha}$ were decreased considerably. 4. SJB 500 mg/kg extract group showed that the size of adipocyte in adipocytes tissue were decreased. 5. All experimental group showed that the adipose vacuoles in liver tissue were decreased considerably. Conclusions : Comparison of the results for this study showed that SJB is effective on obesity care and has obese-inhibitory effects in obese mouse induced by high fat diet. So it is respected that the clinical application of SJB can help the treatment of obesity.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.78-78
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• 2013

Recently, many platinoid metals like platinum and ruthenium have been used as an electrode of microelectronic devices because of their low resistivity and high work-function. However the material cost of Ru is very expensive and it usually takes long initial nucleation time on SiO2 during chemical deposition. Therefore many researchers have focused on how to enhance the initial growth rate on SiO2 surface. There are two methods to deposit Ru film with atomic layer deposition (ALD); the one is thermal ALD using dilute oxygen gas as a reactant, and the other is plasma enhanced ALD (PEALD) using NH3 plasma as a reactant. Generally, the film roughness of Ru film deposited by PEALD is smoother than that deposited by thermal ALD. However, the plasma is not favorable in the application of high aspect ratio structure. In this study, we used a bis(ethylcyclopentadienyl)ruthenium [Ru(EtCp)2] as a metal organic precursor for both thermal and plasma enhanced ALDs. In order to reduce initial nucleation time, we use several methods such as Ar plasma pre-treatment for PEALD and usage of sacrificial RuO2 under layer for thermal ALD. In case of PEALD, some of surface hydroxyls were removed from SiO2 substrate during the Ar plasma treatment. And relatively high surface nitrogen concentration after first NH3 plasma exposure step in ALD process was observed with in-situ Auger electron spectroscopy (AES). This means that surface amine filled the hydroxyl removed sites by the NH3 plasma. Surface amine played a role as a reduction site but not a nucleation site. Therefore, the precursor reduction was enhanced but the adhesion property was degraded. In case of thermal ALD, a Ru film was deposited from Ru precursors on the surface of RuO2 and the RuO2 film was reduced from RuO2/SiO2 interface to Ru during the deposition. The reduction process was controlled by oxygen partial pressure in ambient. Under high oxygen partial pressure, RuO2 was deposited on RuO2/SiO2, and under medium oxygen partial pressure, RuO2 was partially reduced and oxygen concentration in RuO2 film was decreased. Under low oxygen partial pressure, finally RuO2 was disappeared and about 3% of oxygen was remained. Usually rough surface was observed with longer initial nucleation time. However, the Ru deposited with reduction of RuO2 exhibits smooth surface and was deposited quickly because the sacrificial RuO2 has no initial nucleation time on SiO2 and played a role as a buffer layer between Ru and SiO2.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1315-1323
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• 2018

We studied the carbonization due to the annealing condition of waste coffee powder for application as an active anode material for lithium-ion batteries (LIBs). The coffee powder used as an active anode material for LIBs was obtained from coffee beans, not from a coffee shells. The waste coffee powder was dried in air and heat-treated in an $Ar/H_2$ atmosphere to obtain a pore-forming activated carbon powder. The specific capacity of the sample annealed at $700^{\circ}C$ was still 303 mAh/g after 1000 cycles at a current density of 1000 mA/g and with a coulombic efficiency of over 99.5%. The number of pores and the pore size of the waste coffee powder were increased due to chemical treatment with KOH, which had the some effect as an increased specific surface area. The waste coffee powder is considered to be a very promising active anode material because of both its excellent electrochemical properties due to enhanced carrier conduction and its being a cost effective resource for use in LIBs.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.4
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• pp.648-656
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• 2022

As environmental regulations such as the International Maritime Organization (IMO)'s strategy to reduce greenhouse gases(GHG) are strengthened, technology development such as eco-friendly ships and alternative fuels is expanding. As part of this, ship propulsion technology using energy reduction and wind propulsion technology is emerging, especially in shipping companies and shipbuilders. By securing wind propulsion technology and introducing empirical research into shipbuilding and shipping, a high value-added market using eco-friendly technology can be created. Moreover, by reducing the fuel consumption rate of operating ships, GHG can be reduced by 6-8%. Rotor Sail (RS) technology is to generate a hydrodynamic lift in the vertical direction of the cylinder when the circular cylinder rotates at a constant speed and passes through the fluid. This is called the Magnus effect, and this study attempted to propose a plan to increase propulsion efficiency through a numerical analysis study on turbulence flow characteristics around RS, a wind power assistance propulsion system installed on a ship. Therefore, C_L and C_D values according to SR and AR changes were derived as parameters that affect the aerodynamic force of the RS, and the flow characteristics around the rotor sail were compared according to EP application.

• Journal of the Korean Applied Science and Technology
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• v.38 no.6
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• pp.1370-1382
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• 2021

Previous studies have been conducted on domestic materials as a single extract. Research on complex mixtures for maximizing plant characteristics by individual extraction and potential interference with effects is insufficient. Therefore, this study confirmed the GC-MSD according to the extraction of essential oils for Agastache rugosa O. Kuntze(AR), Pinus densiflora Sieb. et Zuccarini(PD), Curcuma longa, Curcuma domestica(CC), Zingiber officinale Roscoe(ZR), Foeniculum vulgare Miller(FV), and Citrus medica L. var. sarcodactylis Swingle(CS). The cytotoxicity, antioxidant, and anti-inflammatory properties of the blending oil were confirmed to confirm its potential as a cosmetic material. As a result of analyzing GC-MSD aroma components, the main components were estragole of AR, à-Pinene for PD, Zingiberene for CC and ZR, Anethole from FV, and D-Limonene for CS. At a concentration of 100 uL/mL with no confirmed cytotoxicity, NO production was inhibited by 70.62%, DPPH radical scavenging activity was 64.03%, and ABTS radical scavenging activity was 89.55%. Through this, blended essential oil suggests the possibility of useful application as a raw material with antioxidant and anti-inflammatory effects in the cosmetic and food industries.

• Journal of Korea Water Resources Association
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• v.55 no.11
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• pp.877-886
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• 2022

This study was carried out to analyze how the flow and water quality of the Sangsa Lake (juam control basin) change according to future climate change and what countermeasures are needed. Aquatic Ecosystem Model) was used in conjunction. As climate change scenarios, RCP (Representative Concentration Pathways) 4.5 and RCP 8.5 scenarios of AR5 (5th Assessment Report) according to the Intergovernmental Panel on Climate Change (IPCC) were used. For the climate change scenario, detailed data on the Sangsa Lake basin were used by the Korea Meteorological Administration, and after being evaluated as a correction and verification process for the 10-year period from 2012 to 2021, the present, 2025-2036, 2045- The summer period from June to August and the winter period from December to February were analyzed separately for each year by dividing it into 2056 and 2075-2086. RCP 8.5 was higher than RCP 4.5 as an arithmetic mean for the flow rate of the watershed of the superior lake for the entire simulation period, and TN and TP also showed a tendency to be higher at RCP 4.5. However, in RCP 8.5, the outflow of pollutants decreased during the dry season and the outflow of pollutants increased during the summer, indicating that the annual pollutant outflow was concentrated during the flood season, and it is analyzed that countermeasures are needed.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.30-31
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• 2009

Early detection of schedule delay in field construction activities is vital to project management. It provides the opportunity to initiate remedial actions and increases the chance of controlling such overruns or minimizing their impacts. This entails project managers to design, implement, and maintain a systematic approach for progress monitoring to promptly identify, process and communicate discrepancies between actual and as-planned performances as early as possible. Despite importance, systematic implementation of progress monitoring is challenging: (1) Current progress monitoring is time-consuming as it needs extensive as-planned and as-built data collection; (2) The excessive amount of work required to be performed may cause human-errors and reduce the quality of manually collected data and since only an approximate visual inspection is usually performed, makes the collected data subjective; (3) Existing methods of progress monitoring are also non-systematic and may also create a time-lag between the time progress is reported and the time progress is actually accomplished; (4) Progress reports are visually complex, and do not reflect spatial aspects of construction; and (5) Current reporting methods increase the time required to describe and explain progress in coordination meetings and in turn could delay the decision making process. In summary, with current methods, it may be not be easy to understand the progress situation clearly and quickly. To overcome such inefficiencies, this research focuses on exploring application of unsorted daily progress photograph logs - available on any construction site - as well as IFC-based 4D models for progress monitoring. Our approach is based on computing, from the images themselves, the photographer's locations and orientations, along with a sparse 3D geometric representation of the as-built scene using daily progress photographs and superimposition of the reconstructed scene over the as-planned 4D model. Within such an environment, progress photographs are registered in the virtual as-planned environment, allowing a large unstructured collection of daily construction images to be interactively explored. In addition, sparse reconstructed scenes superimposed over 4D models allow site images to be geo-registered with the as-planned components and consequently, a location-based image processing technique to be implemented and progress data to be extracted automatically. The result of progress comparison study between as-planned and as-built performances can subsequently be visualized in the D4AR - 4D Augmented Reality - environment using a traffic light metaphor. In such an environment, project participants would be able to: 1) use the 4D as-planned model as a baseline for progress monitoring, compare it to daily construction photographs and study workspace logistics; 2) interactively and remotely explore registered construction photographs in a 3D environment; 3) analyze registered images and quantify as-built progress; 4) measure discrepancies between as-planned and as-built performances; and 5) visually represent progress discrepancies through superimposition of 4D as-planned models over progress photographs, make control decisions and effectively communicate those with project participants. We present our preliminary results on two ongoing construction projects and discuss implementation, perceived benefits and future potential enhancement of this new technology in construction, in all fronts of automatic data collection, processing and communication.