• Atmosphere
• /
• v.32 no.4
• /
• pp.395-409
• /
• 2022

A new soil moisture initialization scheme is applied to the Korea Meteorological Administration (KMA) Global Seasonal forecasting system version 6 (GloSea6). It is designed to ingest the microwave soil moisture retrievals from Soil Moisture Active Passive (SMAP) radiometer using the Local Ensemble Transform Kalman Filter (LETKF). In this technical note, we describe the procedure of the newly-adopted initialization scheme, the change of soil moisture states by assimilation, and the forecast skill differences for the surface temperature and precipitation by GloSea6 simulation from two preliminary experiments. Based on a 4-year analysis experiment, the soil moisture from the land-surface model of current operational GloSea6 is found to be drier generally comparing to SMAP observation. LETKF data assimilation shows a tendency toward being wet globally, especially in arid area such as deserts and Tibetan Plateau. Also, it increases soil moisture analysis increments in most soil levels of wetness in land than current operation. The other experiment of GloSea6 forecast with application of the new initialization system for the heat wave case in 2020 summer shows that the memory of soil moisture anomalies obtained by the new initialization system is persistent throughout the entire forecast period of three months. However, averaged forecast improvements are not substantial and mixed over Eurasia during the period of forecast: forecast skill for the precipitation improved slightly but for the surface air temperature rather degraded. Our preliminary results suggest that additional elaborate developments in the soil moisture initialization are still required to improve overall forecast skills.

• Korean Journal of Metals and Materials
• /
• v.46 no.4
• /
• pp.209-216
• /
• 2008

Super austenitic stainless steels shows the high PRE (Pitting Resistance Equivalent) number and the good corrosion resistance. This work controlled the Co contents in Fe-31Cr-1.7Mo-27Ni-0.25N alloys to elucidate the effect of cobalt contents on the biocompatibility and corrosion resistance. Increasing Co contents, the hardness of the annealed alloys tends to be reduced. In aged alloys, cobalt decreased the increments of hardness by aging treatment. Cobalt decreased the critical pitting temperature (CPT) in 6% $FeCl_3$ + 1% HCl solution, but improved the anodic polarization behavior in Hanks' balanced salt solution and artificial saliva solution. Repassivation rate in artificial body solutions was improved by increasing cobalt contents, but didn't show the linear relationship to PRE number of the alloys. The experimental alloys showed the non-cytotoxicity because of its high corrosion resistance.

• Journal of Korea Planning Association
• /
• v.54 no.6
• /
• pp.68-79
• /
• 2019

The purpose of this study is to propose a transit accessibility analysis method based on temporal variability of travel time. In this study, transit accessibility was defined in three levels (in transit route, spot and region unit) to present findings from different spatial scopes. Recently, Jeju special self-governing province reorganized bus system of the island. To compare transit accessibility before and after transit policy implementation, the reorganized bus system of Jeju special self-governing province was selected as a case study. This study used General Transit Feed Specification (GTFS) data format as storage public transit information, and calculated travel time using ArcGIS GTFS networks analysis tools. In the analysis of individual transit route level, we found the 3 types of accessibility changes which is increments, no significant changes and reductions and these results come from transit route change (number of transfer, distance change) rather than changes of vehicle interval. We found increases of inflow and outflow speed in most target spots and overall transit accessibility has been substantially improved in Jeju island. This study implies that accounting for temporal variability of travel time in accessibility analysis can result in more useful and sophisticated accessibility information in decision-making processes.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.24 no.5
• /
• pp.623-629
• /
• 2020

In this paper, a multiple transmission communication system employing ranging based transmission timing adjustment capability is proposed. In addition, a decision feedback equalizer with the use of combinations of soft decision and hard decision adequate to the proposed multiple transmission communication system is also proposed. The proposed ranging based transmission timing adjustment capability makes the received signals from the multiple transmission points centered on the different symbol timing boundaries. The decision making method for the inputs to the proposed decision feedback equalizer is adaptively selected between soft decision and hard decision as per channel conditions like SNR. The performance of the proposed method had been analyzed through the simulation under the fading channel environments and compared with the previous methods. The simulation results showed performance improvement of the proposed method over the existing ones without noticeable increments in complexities.

• Journal of radiological science and technology
• /
• v.44 no.1
• /
• pp.39-46
• /
• 2021

This study confirmed the usefulness of the copper filter according to the mode change by comparing and analyzing the energy change according to the application of the copper filter and the change in effective dose and image quality according to the distance to the subject in the DR(Digital Radiography) system. The average energy increased when the copper filter was applied and the reduction rate by 50% of mAs was increased as the thickness of the copper filter increased according to the application of the 10 kVp rule in AEC mode. The effective dose decreased as the thickness increased when the copper filter was applied in AEC(Automatic Exposure Control) mode and manual mode according to the application of the 10 kVp rule, and the decrease rate decreased with increasing 10 kVp increments. As a result of analyzing the dicom images for AEC mode and manual mode with Image J. the PSNR(Peak Signal to Noise Ratio) values were approximate values of less than 30 dB for each mode and for each copper filter thickness. When the copper filter was applied, the average energy increased, so when the 10 kVp rule was applied, the mAs for each mode could be reduced, and the effective dose could also be reduced. However, as the distance and tube voltage increased, the reduction rate of mAs decreased, and the quality of the image was found to decrease when the copper filter was applied, but there was no difference in quality of the image when the copper filter thickness increased.

• Journal of Advanced Navigation Technology
• /
• v.24 no.6
• /
• pp.627-632
• /
• 2020

In this paper, we have studied a development of a humidity sensor using a microwave sensor based on a microstrip defected ground structure coated with polyvinyl alcohol. A high-sensitivity microwave sensor, which is sensitive to the changes in the permittivity of the material under test, is designed by adding an interdigital capacitor-shaped defected ground structure to the ground plane of a microstrip line. Polyvinyl alcohol, a polymer material whose permittivity varies depending on humidity, is coated with a thin thickness on the defected ground structure of the proposed microwave sensor, and the changes in the resonance frequency and magnitude of the transmission coefficient for the microwave sensor according to humidity are measured. When relative humidity increases from 40% to 80% in 10% increments at a temperature of 25 degrees using a temperature/humidity chamber, the resonant frequency of the transmission coefficient decreases from 1.475 GHz to 1.449 GHz, and the magnitude is increased from -32.90 dB to -25.67 dB.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.25 no.4
• /
• pp.565-571
• /
• 2021

In this paper, a compensation scheme of frequency selective IQ mismatch for high-performance radar systems based on commercial RFIC's is proposed. Besides, an optimization model and its solution based on the dimension reduction scheme using singular value decomposition are also proposed to design the optimal IQ mismatch compensation digital filter with complex coefficients. The performance of the proposed method had been analyzed through experiments using the IQ mismatch measurement and compensation system implemented on an FPGA board with a target RFIC and compared with the previous method. The experiment result showed a performance improvement of the proposed method over the existing one without noticeable increments in complexities. These performance analysis results showed that the limitation of using commercial RFIC's in high-performance radar systems due to the undesirable maximum SNR cap caused by their IQ mismatches could be overcome by employing the proposed method.

• Journal of Dairy Science and Biotechnology
• /
• v.40 no.3
• /
• pp.122-133
• /
• 2022

Radish (Raphanus sativus L.) has long been recognized as a source of nutrients and phytochemicals. It is well known that the antioxidant properties of radish contributed to its popularity in pharmaceuticals. For this reason, the radish extract aided in the recovery and prevention from diseases. Hence, in this study, the sensory evaluation assessment was conducted following addition of radish oil to almond milk, oat milk, and soy milk (nondairy products) and Kefir, yogurt, and cow milk (dairy products) at different concentrations (containing 0.5% increments from 0% up to 2%). According to the results obtained in this study, all samples containing 0.5% radish oil scored higher on the sensory evaluation scale than the control. It is also very valuable as it is the first study to investigate sensory evaluation assessment by incorporating radish oil into almond milk, oat milk, and soy milk (nondairy products) and kefir, yogurt, and cow milk (dairy products). Furthermore, the results of this study can be used as a foundation for developing future products using radish oil. Additional research on addition of plant-based essential oil to various foods should be conducted.

• Journal of Dairy Science and Biotechnology
• /
• v.40 no.2
• /
• pp.66-75
• /
• 2022

Aloe vera has several beneficial health effects as it interacts with probiotics and is also a source of prebiotics, antioxidants, and other bioactive materials. Thus, there has been increasing interest in the development of beverages containing Aloe vera. In this investigation, sensory qualities were estimated by fortifying oil isolated from Aloe vera in non-dairy and dairy products at different concentrations (fortified with 1% increments from 0% to 5%). Because of the strong aroma and strong yellow color of aloe oil, the sensory quality values estimated in this study were generally low. However, the samples fortified with 1% aloe oil exhibited the best sensory quality values compared with the control. Consequently, the results of this study are valuable as preliminary findings to determine the various sensory qualities of kefir fortified with aloe oil. To improve sensory qualities in the future, it is necessary to estimate the optimal lowering of the concentration of fortified aloe oil, and assess whether aloe oil exhibits various biofunctional activities at different concentrations.

• Journal of Dairy Science and Biotechnology
• /
• v.40 no.3
• /
• pp.110-121
• /
• 2022

The root of ginger (Zingiber officinale) contains gingerol, which is known to be responsible for its pharmacological activity. The essential oil extracted from ginger has been found to have various pharmacological effects. Thus, interest in the development of various beverages using ginger oil has recently increased. Therefore, in this study, the organoleptic quality assessment of cow milk, yogurt, kefir, soy milk, oat milk, and almond milk was conducted by supplementing them with oil extracted from ginger at various concentrations (supplemented with 0.5% increments from 0% up to 2%). A poor grade was obtained in the organoleptic quality evaluation, owing to the strong odor of ginger oil. However, when compared to that of the control, the samples supplemented with 0.5% ginger oil showed a good grade of organoleptic quality assessment. Therefore, this study is considered valuable as it is the first study to review the organoleptic quality assessment by supplementing milk, yogurt, kefir, soy milk, oat milk, and almond milk with ginger oil. Additionally, in order to improve organoleptic quality assessment, it is critical to estimate how much ginger oil supplementation concentration could be reduced and whether ginger oil exhibits various bio-activities at this concentration.