• Journal of the Microelectronics and Packaging Society
• /
• v.30 no.3
• /
• pp.20-34
• /
• 2023

Single or multi-layered two-dimensional (2D) materials, with thicknesses in the order of a few nanometers, have garnered substantial attention across diverse research domains owing to their distinct properties, including electrical conductivity, flexibility, and optical transparency. These materials are frequently subjected to repetitive mechanical actions in applications like electronic skin (E-Skin) and smart textiles. Moreover, they are often exposed to external factors like temperature, humidity, and pressure, which can lead to a deterioration in component durability and lifespan. Consequently, significant research efforts are directed towards developing self-healing properties in these components. Notably, recent investigations have revealed promising outcomes in the field of self-healing composite materials, with Ti₃Ci₂Ti_x MXene being a prominent component among the myriad of available 2D materials. In this paper, we aim to introduce various synthesis methods and characteristics of Ti₃Ci₂Ti_x MXene, followed by an exploration of self-healing application technologies based on Ti₃Ci₂Ti_x MXene.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.18 no.6
• /
• pp.1009-1014
• /
• 2023

Comprehensive observations of the Euler method and the Lagrangian method were performed in order to obtain high-resolution observation data in space and time for the complex environment of new city. The two radiosondes, which measure meteorological parameters using Lagrangian methods, produced air pressure, wind speed and wind direction. They were generally consistent with each other even if the observation points or times were different. The temperature measured by the sensor exposed to the air during the day was relatively high as the altitude increased due to the influence of solar radiation. The temporal difference in wind direction and speed was found in the comparison of Euler's wind profiler data with radiosonde data. When the wind field is horizontally in homogeneous, this result implies the need to consider the advection component to compare the data of the two observation methods. In this study, a method of using observation data at different times for each altitude section depending on the observation period of the Euler method is proposed to effectively compare the data of the two observation methods.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
• /
• v.16 no.6
• /
• pp.478-488
• /
• 2023

This paper investigates the naval application of laser communication as a potential replacement for traditional acoustic wave communication in underwater environments. We developed a laser transceiver using Arduino and MATLAB, conducting a water tank experiment to validate communication feasibility across diverse underwater conditions. In the first experiment, when transmitting data through a laser, the desired message was converted into data and transmitted, received, and confirmed to be converted into the correct message. In the second experiment, the operation of communication in underwater situations was confirmed, and in the third experiment, the intensity of light was measured using the CDS illuminance sensor module and the limits of laser communication were measured and confirmed in various underwater situations. Additionally, MATLAB code was employed to gather data on salinity, water temperature, and water depth for calculating turbidity. Optimal wavelength values (532nm, 633nm, 785nm, 1064nm) corresponding to calculated turbidity levels (5, 20, 55, 180) were determined and presented. The study then focuses on analyzing potential applications in naval tactical communication, remote sensing, and underwater drone control. Finally, we propose measures for overcoming current technological limitations and enhancing performance.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.44 no.1
• /
• pp.85-93
• /
• 2024

The monitoring of environmental information (e.g. noise, dust, vibration, temperature, humidity) is crucial to the safe and sustainable operation of a construction site. However, commercial sensors exhibit certain drawbacks when applied on-site. First, the installation cost is prohibitively high. Second, these sensors have been engineered without considering the rugged and harsh conditions of a construction site, resulting in error-prone sensing. Third, construction sites are compelled to allocate additional resources in terms of manpower, expenses, and physical spaces to accommodate individual sensors. This research developed an integrated sensing module to measure the environmental information in construction site. The sensing module slashes the installation cost to 3.3%, is robust enough to harsh and outdoor sites, and consolidates multiple sensors into a single unit. The sensing module also supports GPS, LTE, and real-time sensing. The evaluation showed remarkable results including 97.5% accuracy and 99.9% precision in noise measurement, an 89.7% accuracy in dust measurement, and a 93.5% reliability in data transmission. This research empowers the collection of substantial volumes and high-quality environmental data from construction sites, providing invaluable support to decision-making process. These encompass objective regulatory compliance checking, simulations of environmental data dispersion, and the development of environmental mitigation strategies.

• Korean Journal of Food Science and Technology
• /
• v.33 no.4
• /
• pp.427-436
• /
• 2001

The effects of storage form (paddy and milled rice) and storage period (1, 2, and 3 years) of rice at low temperature $(4^{\circ}C)$ on physicochemical properties of milled and cooked rice and sensory characteristics of cooked rice were investigated. The proximate compositions except moisture content of rice decreased as the storage period increased. Water binding capacity, solubility and swelling power of rice flour decreased with the extended storage period. In the amylogram, the initial pasting temperature, paste viscosity and breakdown of paddy rice flour slurry decreased after 2 years of storage. Moisture content of cooked rice increased while the amount of water evaporated during cooking decreased. These trends were obvious with the longer storage period. Lightness and yellowness of cooked rice were greatly changed after 3 years of storage, regardless of storage form. Texture profile analysis of cooked rice by Texture Analyzer revealed that hardness, fracturability, gumminess were gradually increased while adhesiveness decreased as the storage period of rice increased. A trained panel found that color intensity, intactness of grains, rancid flavor, rice bran flavor, wet cardboard flavor, hardness and chewiness of cooked rice increased with the longer storage period. However, glossiness, transparency, plumpness, puffed corn flavor, dairy flavor, boiled egg white flavor, sweet taste, adhesiveness to lips, smoothness and inner moisture decreased with the extended storage period up to 3 years. Instrumental hardness was highly correlated with sensory hardness.

• Journal of Sensor Science and Technology
• /
• v.11 no.1
• /
• pp.9-17
• /
• 2002

The forming conditions of X-ray storage phosrhors $BaFBr_{1-x}I_x:Eu^{2+}$, $Na^+$ have been investigated, and measured the PSL emission spectra and its intensity, fading characteristics and does dependence of the prepared phosphors. These characteristics were compared with those of commercial image plate (ST-III) obtained from Fuji Photo Film Co. The optimal preparing conditions of $BaFBr_{1-x}I_x:Eu^{2+}$, $Na^+$ Phosphor were 0.5 mol% of $EuF_3$, 4.0 mol% of NaF and composition ratio x=0.3, and the sintering temperature were $950^{\circ}C$ in $H_2$ atmosphere. When the composition ratio x was equal to 0, the spectral range of the luminescence of $BaFBr_{1-x}I_x:Eu^{2+}$, $Na^+$ phosphor was $365{\sim}420\;nm$, and its maximum luminescence intensity appeared at 390 nm. When composition ratio x was not equal to 0, the wavelength ranges and peak of the spectra were shifted to the longer wavelength with the growth of composition ratio x. A good linearity was shown between the PSL intensity and X-ray irradiation dose. The phosphor sample with x=0.3 exhibited better fading characteristics than that of other $BaFBr_{1-x}I_x:Eu^{2+}$ phosphor samples, and the fading characteristics of the PSL intensity at room temperature were shown poorer with increasing $I^-$ ion concentration. The lattice constant of the phosphor becomes larger with increasing the $I^-$ ion concentration.

• Journal of Sensor Science and Technology
• /
• v.10 no.1
• /
• pp.62-70
• /
• 2001

The ZnSe sample grown by chemical bath deposition (CBD) method were annealed in Ar gas at $45^{\circ}C$. Using extrapolation method of X-ray diffraction pattern, it was found to have zinc blend structure whose lattice parameter $a_o$ was $5.6687\;{\AA}$. From Hall effect, the mobility was likely to be decreased by impurity scattering at temperature range from 10 K to 150 K and by lattice scattering at temperature range from 150 K to 293 K. The band gap given by the transmission edge changed from $2.700{\underline{5}}\;eV$ at 293 K to $2.873{\underline{9}}\;eV$ at 10 K. Comparing photocurrent peak position with transmission edge, we could find that photocurrent peaks due to excition electrons from valence band, ${\Gamma}_8$ and ${\Gamma}_7$ and to conduction band ${\Gamma}_6$ were observed at photocurrent spectrum. From the photocurrent spectra by illumination of polarized light on the ZnSe thin film, we have found that values of spin orbit coupling splitting ${\Delta}so$ is $0.098{\underline{1}}\;eV$. From the PL spectra at 10K, the peaks corresponding to free bound excitons and D-A pair and a broad emission band due to SA is identified. The binding energy of the free excitons are determined to be $0.061{\underline{2}}\;eV$ and the dissipation energy of the donor -bound exciton and acceptor-bound exciton to be $0.017{\underline{2}}\;eV$, $0.031{\underline{0}}\;eV$, respectively.

• Korean Journal of Remote Sensing
• /
• v.14 no.1
• /
• pp.53-68
• /
• 1998

Observation of hydrometeors' behavior in the atmosphere is important to understand weather and climate. By conventional observations, we can get the distribution of water vapor at limited number of points on the earth. In this study, the precipitable water has been estimated from the split window channel data on GMS-5 based upon the technique developed by Chesters et al.(1983). To retrieve the precipitable water, water vapor absorption parameter depending on filter function of sensor has been derived using the regression analysis between the split window channel data and the radiosonde data observed at Osan, Pohang, Kwangiu and Cheju staions for 4 months. The air temperature of 700 hPa from the Global Spectral Model of Korea Meteorological Administration (GSM/KMA) has been used as mean air temperature for single layer radiation model. The retrieved precipitable water for the period from August 1996 through December 1996 are compared to radiosonde data. It is shown that the root mean square differences between radiosonde observations and the GMS-5 retrievals range from 0.65 g/$cm^2$ to 1.09 g/$cm^2$ with correlation coefficient of 0.46 on hourly basis. The monthly distribution of precipitable water from GMS-5 shows almost good representation in large scale. Precipitable water is produced 4 times a day at Korea Meteorological Administration in the form of grid point data with 0.5 degree lat./lon. resolution. The data can be used in the objective analysis for numerical weather prediction and to increase the accuracy of humidity analysis especially under clear sky condition. And also, the data is a useful complement to existing data set for climatological research. But it is necessary to get higher correlation between radiosonde observations and the GMS-5 retrievals for operational applications.

• Journal of Korean Society of Environmental Engineers
• /
• v.34 no.10
• /
• pp.656-663
• /
• 2012

After the construction of waterworks automatic meter reading with 15 mm diameter digital water mater with magnetoresistance sensor developed in this study at 96 households of apartment complexes located in Incheon-City B-Gu S-Dong, the feasibility of field application of waterworks automatic meter reading was evaluated. The field application of waterworks automatic meter reading was performed from July to December in 2011, and average reception rate was as low as 84.6% due to the instable wibro networks, the existence of communication blackout and temporary malfunction of router. After the extraction of 10 households with one to five residents out of 96 households by using stratified random sampling method and analysis of domestic water use, it was found that domestic water use was significant at August and showed a decreasing trend at September, followed by increase in domestic water use at November and decrease in domestic water use at December. This phenomenon should be attributed to weather factors (temperature, humidity, etc.), which significantly affected domestic water use. Similar trend in domestic water use in terms of weather factors was obtained in case of Liter per capita day of water use after the extraction of 30 households out of 96 households by using stratified random sampling method. After analysis of Liter per capita day for 96 households, single residents increases resulted in reduction of domestic water usage by about 14% of Liter per capita day. These results might be due to the fact that domestic water usage such as laundry, beverages, catering, cleaning, etc. should be required for even the household with one resident, whereas domestic water usage for those common utilization can be significantly saved for the household with more than one resident.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
• /
• v.21 no.1
• /
• pp.1-10
• /
• 2016

Currently available surface seawater partial pressure carbon dioxide ($pCO_2$) data sets in the East Sea are not enough to quantify statistically the carbon dioxide flux through the air-sea interface. To complement the scarcity of the $pCO_2$ measurements, we construct a neural network (NN) model based on satellite data to map $pCO_2$ for the areas, which were not observed. The NN model is constructed for the Ulleung Basin, where $pCO_2$ data are best available, to map and estimate the variability of $pCO_2$ based on in situ $pCO_2$ for the years from 2003 to 2012, and the sea surface temperature (SST) and chlorophyll data from the MODIS (Moderate-resolution Imaging Spectroradiometer) sensor of the Aqua satellite along with geographic information. The NN model was trained to achieve higher than 95% of a correlation between in situ and predicted $pCO_2$ values. The RMSE (root mean square error) of the NN model output was $19.2{\mu}atm$ and much less than the variability of in situ $pCO_2$. The variability of $pCO_2$ with respect to SST and chlorophyll shows a strong negative correlation with SST than chlorophyll. As SST decreases the variability of $pCO_2$ increases. When SST is lower than $15^{\circ}C$, $pCO_2$ variability is clearly affected by both SST and chlorophyll. In contrast when SST is higher than $15^{\circ}C$, the variability of $pCO_2$ is less sensitive to changes in SST and chlorophyll. The mean rate of the annual $pCO_2$ increase estimated by the NN model output in the Ulleung Basin is $0.8{\mu}atm\;yr^{-1}$ from 2003 to 2014. As NN model can successfully map $pCO_2$ data for the whole study area with a higher resolution and less RMSE compared to the previous studies, the NN model can be a potentially useful tool for the understanding of the carbon cycle in the East Sea, where accessibility is limited by the international affairs.