• Journal of Radiation Protection and Research
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• v.43 no.4
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• pp.160-169
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• 2018

Background: This study aims to develop an integrated optical system that can simultaneously or selectively measure the signals obtained from radioluminescence (RL), thermoluminescence (TL), and optically stimulated luminescence (OSL), which are luminescence phenomena of materials stimulated by radioactivity, heat, and light, respectively. The luminescence mechanism of various materials could be investigated using the glow curves of the luminescence materials. Materials and Methods: RL/TL/OSL integrated measuring system was equipped with a X-ray tube (50 kV, $200{\mu}A$) as an ionizing radiation source to irradiate the sample. The sample substrate was used as a heating source and was also designed to optically stimulate the sample material using various light sources, such as high luminous blue light emitting diode (LED) or laser. The system measured the luminescence intensity versus the amount of irradiation/stimulation on the sample for the purpose of measuring RL, TL and OSL sequentially or by selectively combining them. Optical filters were combined to minimize the interference of the stimulation light in the OSL signal. A long-pass filter (420 nm) was used for 470 nm LED, an ultraviolet-pass filter (260-390 nm) was used for detecting the luminescence of the sample by PM tube. Results and Discussion: The reliability of the system was evaluated using the RL/OSL characteristics of $Al_2O_3:C$ and the RL/TL characteristics of LiF:Mg,Cu,Si, which were used as dosimetry materials. The RL/OSL characteristics of $Al_2O_3:C$ showed relatively linear dose-response characteristics. The glow curve of LiF:Mg,Cu,Si also showed typical RL/OSL characteristics. Conclusion: The reliability of the proposed system was verified by sequentially measuring the RL characteristics of radiation as well as the TL and OSL characteristics by concurrent thermal and optical stimulations. In this study, we developed an integrated measurement system that measures the glow curves of RL/TL/OSL using universal USB-DAQs and the control program.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.34 no.6
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• pp.495-504
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• 2021

Energy Harvesting is a technology that can convert wasted energy such as vibration, heat, light, electromagnetic energy, etc. into usable electrical energy. Among them, vibration-based piezoelectric energy harvesting (PEH) has high energy conversion efficiency with a small volume; thus, it is expected to be used in various autonomous powering devices, such as implantable medical devices, wearable devices, and energy harvesting from road or automobiles. In this study, wasted vibration energy in an automobile is converted into electrical energy by high-power piezoelectric materials, and the generated electrical energy is found to be an auxiliary power source for the operation of wireless sensor nodes, LEDs, etc. inside an automobile. In order to properly install the PEH in an automobile, vibration characteristics includes frequency and amplitude at several positions in the automobile is monitored initially and the cantilever structured PEH was designed accordingly. The harvesting properties of fabricated PEH is characterized and installed into the engine part of the automobile, where the vibration amplitude is stable and strong. The feasibility of PEH is confirmed by operating electric components (LEDs) that can be used in practice.

• Journal of Powder Materials
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• v.15 no.3
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• pp.182-187
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• 2008

Carbon was known to be one of effective additives which can improve the flux pinning of $MgB_2$ at high magnetic fields. In this study, glycerin $(C_3H_8O_3)$ was selected as a chemical carbon source for the improvement of critical current density of $MgB_2$. In order to replace some of boron atoms by carbon atoms, the boron powder was heat-treated with liquid glycerin. The glycerin-treated boron powder was mixed with an appropriate amount of magnesium powder to $MgB_2$ composition and the powder pallets were heat treated at $650^{\circ}C\;and\;900^{\circ}C$ for 30 min in a flowing argon gas. It was found that the superconducting transition temperature $(T_c)$ of $Mg(B_{1-x}C_x)_2$ prepared using glycerin-treated boron powder was 36.6 K, which is slightly smaller than $T_c$(37.1 K) of undoped $MgB_2$. The critical current density $(J_c)$ of $Mg(B_{1-x}C_x)_2$ was higher than that of undoped $MgB_2$ and the $T_c$ improvement effect was more remarkable at higher magnetic fields. The $T_c$, decrease and $J_c$ increase associated with the glycerin treatment for boron powder was explained in terms of the carbon substitution to boron site.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.942-945
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• 2005

Micron-sized metal wires are widely used in industries such as filtration, catalyst and composite materials, etc. In the wire drawing process, the die that is used conventionally is an effective and, at the same time, sensitive component. However, a typical array of the dies has caused many problems in the wire drawing process, e.g., large frictional force on the interface between wire and the resulting high heat generation, precise adjustment of the dies, extended cooling system, die abrasion, etc.. Because of these problems, there have been many works that are aiming at improving the efficiency of wire drawing process by analyzing the die geometry and by applying advanced die material to prolong the die life or even at developing a dieless wire drawing system. This paper is dealing with developing a new wire drawing system that is applicable to reduce the wire drawing steps with high draw ratio. The new wire drawing system does not use the dies, but use the self-induced heater that works on the basis of the resonant phenomenon of wire material. The electromagnetic wave is the heating source. The results of the study on the diameter reduction and microwave flow analysis show that the heating effectiveness of the wire is influenced by the energy distribution in the microwave propagation chamber. We can obtain diameter-reduced wires by using microwave in the dieless drawing process. Microwave as a heating source is capable of producing wires without applying dies in wire drawing process.

• Journal of the Korean Society of Food Science and Nutrition
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• v.35 no.4
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• pp.416-421
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• 2006

Among the oriental medicine compounds, sulfur is known as a heat-generation material in a human body. Heat-generation reaction results in the consumption of energy source. Some oriental herbs are used to treat obesity and blood lipid composition. Therefore, we hypothesized that a sulfur containing oriental medicine compound, called as Hangbisan, could help weight loss of experimental rats. This study was designed to observe the change of weight of Sprague-Dawley (SD) rats that had been fed with high-fat diet containing 10% cellulose or Hangbisan for 9 weeks. Hangbisan affected the weight loss of rats as reducing the level of plasma cholesterol and triglyceride and increasing the level of HDL-cholesterol. Thus, this study revealed Hangbisan have an anti-obesity effect and a potential role for anti-obesity agent in the application of oriental medicine compounds.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.358-365
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• 2011

Recently, the LED(Light Emitting Diode) replacing incandescent light bulbs and fluorescent light has great attentions as a most promising candidate for the next generation lighting source due to its environment-friendly characteristics, long life and excellent efficiency. Moreover, since it is a semiconductor device which can convert the electric energy to visible light at a very high speed, it can also used as a communication device. Therefore, the VLC(Visible Light Communication) using the LED can perform the near field communication and lighting function at the same time without additional expenses. However, since the switching device of the conventional LED driver for VLC is operated in the linear region, there exist several drawbacks such as a poor power conversion efficiency and serious heat generation. On the other hand, since the proposed driver is operated in the on/off switching region, it features a higher efficiency and more improved heat generation. To verify the validity of the proposed LED driver, experimental results from a prototype of 20W rated LED driver applied to 3MHz bps broadcasting audio system are given.

• Korean Journal of Agricultural Science
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• v.40 no.4
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• pp.333-338
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• 2013

Sources of energy and rumen undegradable protein (RUP) have been used to meet nutrient requirements for high producing dairy cows. However studies for manipulation the levels of energy and RUP in diets have been mainly achieved using dairy cows at early-lactation period. The objective of this study thus, was to investigate the effects of different energy and rumen undegradable protein (RUP) levels on dry matter intake and milk yield in Holstein cows at mid-lactation period. Basal diet was prepared as TMR to meet nutrient requirements for dairy cows at mid-lactation according to NRC recommendation. Cows of control group (Con) were fed only basal diets while ground corn (0.5 kg/d), heat-treated soybean meal (0.5 kg/d), and their mixture (0.25 kg of each supplements/d) were added to diets for cows of treatment groups (T1, T2, and T3 respectively) to modulate the level of energy and RUP contents in diets. Addition of energy or RUP source in basal TMR did not affect in total DMI while TMR intake tended to be higher in Con compared to T3. Cows fed T3 diets tended to show increased milk yield and MUN content than those of Con. Cows for T2 as well as T3 had lower ADG (P<0.05) compared with those of Con. We concluded that the addition of RUP source in diets for dairy cows on mid-lactation period might cause the decrement of DMI and ADG.

• Journal of the Korean Society of Safety
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• v.24 no.3
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• pp.54-58
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• 2009

A substitute energy development has been required due to the exhaust of the fossil fuel and an environmental problem. Consequently, possible technologies producing hydrogen from water that does not release carbon is a very promising technology. Also, Iodine-Sulfur(IS) thermochemical water decomposition is one of the promising processes that are used to produce hydrogen efficiently using the high temperature gas-cooled reactor(HTGR) as an energy source that is possible to supply heat over 900$^{\circ}C$. In this study, to make a initiating events identification for the IS process, Master Logic Diagram(MLD) is used and 9 initiating events that cause a leakage of the chemical material are identified. Also, 6 events are identified among 9 initiating events above and are quantified using event tree.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.525-534
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• 2022

In this study, we investigated the applicability and optimal operating strategy of a closed-loop pressure retarded membrane distillation (PRMD) for brackish water desalination. For effective operation with net power generation, high temperature of heat source over 90 ℃ and feed flow rate at 0.6 kg/s are recommended. At 3 g/L of feed concentration, the average permeate flux and net energy density showed 8.04 kg/m²/hr and 2.56 W/m², respectively. The average permeate flux and net energy density were almost constant in the range of feed concentration from 1 to 3 g/L. Compared to the case with seawater feed, the PRMD with brackish water feed showed higher average permeate flux and net energy density. Thus, PRMD application using brackish water feed can be more effective than that using seawater feed in terms of power generation.

• The Journal of the Convergence on Culture Technology
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• v.10 no.1
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• pp.551-557
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• 2024

Hydrogen is a renewable energy source with various characteristics such as clean, carbon-free and high-energy, and is internationally recognized as a "future energy". With the rapid development of the hydrogen energy industry, more hydrogen infrastructure is needed to meet the demand for hydrogen. However, hydrogen infrastructure accidents have been occurring frequently, hindering the development of the hydrogen industry. HyRAM+, developed by Sandia National Laboratories, is a software toolkit that integrates data and methods related to hydrogen safety assessments for various storage applications, including hydrogen refueling stations. HyRAM+'s physics mode simulates hydrogen leak results depending on the hydrogen refueling station components, graphing gas plume dispersion, jet frame temperature and trajectory, and radiative heat flux. In this paper, hydrogen leakage data was extracted from a hydrogen refueling station in Samcheok, Gangwon-do, using HyRAM+ software. A hydrogen leakage simulator was developed using data extracted from HyRAM+. It was implemented as a dashboard that shows the data generated by the simulator using a database and Grafana.