• Journal of the Korean Magnetics Society
• /
• v.21 no.6
• /
• pp.208-213
• /
• 2011

We calculated the EPR (electron paramagnetic resonance) line-shape function. The line-widths of a -doped single crystal was studied as a function of the temperature with 0.5 and 2 at. at a frequency of (X-band). The line-width decreases with increasing temperature, such temperature behavior of the line-width can indicate a motional narrowing of the spectrum, when impurity ions substitute for host ions in an off-center position, and thus there can be fast jumping of dipoles between several symmetrically equivalent configurations. Therefore, the present technique is considered to be more convenient to explain the resonant system as in the case of other optical transition problems.

• Journal of the Korea Convergence Society
• /
• v.12 no.4
• /
• pp.1-8
• /
• 2021

Currently, lithium-ion batteries are mainly used in energy storage equipment products including automobiles. This can be exposed to dangerous situations such as explosions in the event of incorrect battery management conditions that are overcharged or left in high temperature conditions. It also causes a situation battery cannot be used when it has been over discharged. Therefore, a system that manages the state of the battery is required. The battery management system aims to obtain optimum battery efficiency by accurately recognizing the state of the battery and keeping the voltage of each cell constant. In this paper, we develop a lithium-iron phosphate battery that has higher safety than a general lithium-ion battery. Then, in order to manage this, we try to develop the algorithm of the BMS module based on the Bluetooth communication using the MATLAB-SIMULINK.

• Ecology and Resilient Infrastructure
• /
• v.6 no.1
• /
• pp.12-22
• /
• 2019

This study investigated the spatial and temporal water circulation characteristics of Paldang Reservoir by continuous hydraulic and water temperature survey. Due to differences in water temperature and discharge pattern of Ipo Weir and Cheongpyeong Dam, the flow and temperature fluctuations were different in sections of Namhan River and Bukhan River in Paldang Reservoir. At the stratification period, the water temperature of the discharge of Ipo Weir was higher than that of the Cheongpyeong Dam. Therefore, in the surface layer of the downstream of Bukhan River, relatively high temperature water is located and back water phenomenon occurred, and convergence zone is formed. In the downstream section of Namhan River, low-temperature water was distributed in the middle and lower layers, and the upstream flow appeared to be difficult to mix with the surface layer.

• Applied Chemistry for Engineering
• /
• v.22 no.6
• /
• pp.658-663
• /
• 2011

The SNCR-SCR (selective non-catalytic reduction-selective catalytic reduction) hybrid system is an economical NOx removal system. In this study, the effect of the operating parameters of the SNCR-SCR hybrid system on NOx removal efficiency was investigated. When the SNCR reactor was operated at a temperature lower than the optimum temperature ($900{\sim}950^{\circ}C$), an additional NO removal is obtained basesd on the utilization of $NH_3$ slip. On the other hand, the SNCR reactor operated above the temperature resulted in no additional NO removal of SCR due to decomposition of $NH_3$. Therefore, the SNCR process should be operated at optimum temperature to obtain high NO removal efficiency and low $NH_3$ slip. Thus, it is important to adjust NSR (normalized stoichiometric ratio) so that $SR_{RES}$ can be maintained at an appropriate level.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.30 no.6
• /
• pp.215-219
• /
• 2020

After the specimen of A-site defect double Perovskite La1/3TaO3 single crystal was manufactured, the dielectric properties have been studied between the temperature range of 10 and 800 K. Under 500 K, a paraelectric behavior has been shown, and above 550 K, a dielectric anomaly and a thermal history of dielectric constant has been shown. An activation energy by measurement of ac-conductivity has been the largest with 1.83 eV in the areas below 560 K, 0.35 eV in the areas of 560~690 K, and 0.28 eV in the areas of high temperature above 690 K. From these results, it is assumed that in the areas below 500 K, La3+-ion and vacancy-site are arranged in disorder to maintain a paraelectric phase. And in the areas near 560 K with the highest activation energy, a dielectric anomaly is attributes to rearrangement of La3+-ion due to conduction to vacancy-site or jumping.

• Journal of the Microelectronics and Packaging Society
• /
• v.28 no.1
• /
• pp.67-71
• /
• 2021

In this study, graphene layer was grown on metal microwire using chemical vapor deposition. The difference of carbon solubility between copper and nickel resulted in the formation of mono-layer and multi-layer graphene were formed on the surfaces of copper and nickel microwires, respectively. During the growth of graphene at high temperature, copper and nickel were recrytallized and the grain size increased. The ampacity of graphene/copper microwire was improved by approximately 27%, 1.91×105 A/㎠, compared to pristine copper microwire. Similar to this behavior, the ampacity of multilayer graphene/nickel microwire was 4.41×104 A/㎠ which is about about 36% improved compared to the pure nickel microwire. The excellent electrical properties of graphene/metal composites are beneficial for supplying the electrical energy to the high-power electronic devices and equipment.

• Journal of the Society of Cosmetic Scientists of Korea
• /
• v.48 no.4
• /
• pp.385-392
• /
• 2022

In this study, keratin peptides were produced through high-temperature anaerobic fermentation of keratin, a protein contained in deer antler, with Fervidobacterium islandicum AW-1, and factors related to human hair, confirming the possibility of keratin peptides as cosmetic ingredients. As a result of the cytotoxicity and proliferation of deer antler fermented keratin peptide according to the concentration in the dermal papilla cell line, cytotoxicity was not observed and the cell proliferation effect was shown. For human dermal papilla cells, statistically significant increasing in growth factors according to the deer antler fermented keratin peptide was determined possiblity of effects on hair growth. Cosmetic products containing deer antler fermented keratin peptides were manufactured and skin safety and anti hair loss efficacy clinical tests were conducted. As a result, after 12 weeks of use, the total number of hairs statistically significant increased compared to before using the product and the difference in total number of hairs compared to the control group was found. In conclusion, we suggest that the possibility of fermented deer antler keratin peptide as a cosmeceutical ingredient as well as a health functional food material was confirmed.

• Journal of Adhesion and Interface
• /
• v.24 no.2
• /
• pp.60-63
• /
• 2023

The AlGaN/GaN heterostructure has high electron mobility due to the two-dimensional electron gas (2-DEG) layer, and has the characteristic of high breakdown voltage at high temperature due to its wide bandgap, making it a promising candidate for high-power and high-frequency electronic devices. Despite these advantages, there are factors that affect the reliability of various device properties such as current collapse. To address this issue, this paper used metal-organic chemical vapor deposition to continuously deposit AlGaN/GaN heterostructure and SiN passivation layer. Material and electrical properties of GaN HEMTs with/without SiN cap layer were analyzed, and based on the results, low-frequency noise characteristics of GaN HEMTs were measured to analyze the conduction mechanism model and the cause of defects within the channel.

• Clean Technology
• /
• v.16 no.1
• /
• pp.12-18
• /
• 2010

The object of the present study is to apply KF/MgO catalysts to remove sulfur dioxide from dibenzothiophene sulfone, a by-product of oxidative desulfurization. Potassium fluoride was deposited via an impregnation method on MgO. The effects KF loading and calcination on the characteristics of the KF/MgO catalysts were investigated through the BET surface area, XRF, XRD, and temperature-programmed desorption of $CO_2$. The catalytic performances of the samples were investigated during the decomposition of dibenzothiophene sulfone to biphenyl and sulfur dioxide gas. KF loaded on MgO prepared by the impregnation method showed high catalytic activities for the decomposition of dibenzothiophene sulfone. The higher activity of KF/MgO just dried at 373 K, avoiding the usual activation at high temperature, than that over the calcined catalyst is ascribed to increase of the amount of basic sites. The high basicity probably may be due to the coordinately unsaturated $F^-$. The simply dried 10 % KF/MgO catalyst, without the usual activation at high temperature, showed the optimal catalytic properties.

• Journal of Korean Society of Disaster and Security
• /
• v.15 no.4
• /
• pp.79-86
• /
• 2022

The National Park Service is making efforts to create a safe environment by installing rockfall prevention facilities (rockfall prevention nets, fences, and Piam tunnels) in areas at risk of falling rocks. However, the occurrence of falling rocks is increasing every year due to torrential rains caused by climate change, abnormal temperatures in winter, and aging of the ground, and the need to improve the existing rock risk area management plan has emerged. In this study, a pilot area at risk of falling rocks was selected for the Hwanggol district of Chiaksan National Park among Korean national parks, and rockfall analysis was performed using the Rockfall program, and monitoring was conducted by applying a countermeasure method combined with the measurement system to the pilot area. Through this, a rockfall management plan was proposed for continuous management and monitoring of rockfall.