• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.26 no.2
• /
• pp.239-250
• /
• 2022

LoRa is a physical layer technology designed to secure highly reliable long-range communication with introducing loco parentis tree network and chirp spreading spectrum. Since since a leaf can send message to more than one parents simultaneously with a single transmission in a region, packet delivery ratio increases logarithmically as the number of gateways increases. The delivery ratio, however, dramatically collapses even under loco parentis tree topology due to the limitations of ALOHA-like primitive MAC, . The proposed method is intended to exploit SDMA approach to reuse frequency in an area. With the view, TxPower of each sender for each message in a concurrent transmission is elaborately controlled to survive the collision at different gateway. Thus, the gain from the capture effect improves the capacity of resource-hungry Low Power and Wide Area Networks.

• Journal of East Asia Management
• /
• v.4 no.1
• /
• pp.1-22
• /
• 2023

This study conducted a big data analysis study through text mining and semantic network analysis to explore the perception of defense reform 2.0. The collected data were analyzed with the top 70 keywords as the appropriate range for network visualization. Through word frequency analysis, connection centrality analysis, and an N-gram analysis, we identified issues that received much attention such as troop reduction, shortening of military service period, dismantling of the border area unit, and returning wartime operational control. In particular, the results of clustering words through CONCOR analysis showed that there was a great interest in pursuing the technical group, concerns about military capacity reduction, and reorganization of manpower structure. The results of the analysis through text mining techniques are as follows. First, it was found that there was a lack of awareness about measures to reinforce the reduced troops while receiving much attention to the reduction of troops in Defense Reform 2.0. Second, it was found that it is necessary to actively communicate with the local community due to the deconstruction and movement of the border area units, such as the decrease of the population of the region and the collapse of the local commercial area. Third, it was judged that it is necessary to show substantial results through the promotion of barracks culture and the defense industry, which showed that there was less interest than military structure and defense operation from the people and the introduction of active policies. Through this study, we analyzed the public's interest in defense reform 2.0, which is a representative defense policy, and suggested a plan to draw support for national policy.

• Atmosphere
• /
• v.33 no.2
• /
• pp.125-154
• /
• 2023

Since the Korean Meteorological Society was organized in 1963, the climate dynamics fields have been made remarkable progress. Here, we documented the academic developments in the area of climate dynamics performed by members of Korean Meteorological Society, based on studies that have been published mainly in the Journal of Korean Meteorological Society, Atmosphere, and Asia-Pacific Journal of Atmospheric Sciences. In these journals, the fundamental principles of typical ocean-atmosphere climatic phenomena such as El Niño, Madden-Julian Oscillation, Pacific Decadal Oscillation, and Atlantic Multi-decadal Oscillation, their modeling, prediction, and its impact, are being conducted by members of Korean Meteorological Society. Recently, research has been expanded to almost all climatic factors including cryosphere and biosphere, as well as areas from a global perspective, not limited to one region. In addition, research using an artificial intelligence (AI), which can be called a cutting-edge field, has been actively conducted. In this paper, topics including intra-seasonal and Madden-Julian Oscillations, East Asian summer monsoon, El Niño-Southern Oscillation, mid-latitude and polar climate variations and some paleo climate and ecosystem studies, of which driving mechanism, modeling, prediction, and global impact, are particularly documented.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.20 no.1
• /
• pp.30-36
• /
• 1984

It is well known that the application of linear elastic fracture mechanics is inadequate to solve the large deformation fracture failures which occurr in ductile manner because of the large scale yielding due to the severe stress concentration in the region adjacent to the crack tip. The authors have been evolved a fracture model, the crack plane equilibrium model, for this kinds of elastic-plastic fracture problems in the previous report. In this report, the crack plane equilibrium model was compared with the Irwin's plastic zone corrected linear elastic fracture mechanics through theoretical comparisons and experimental results to examine the validity of the crack plane equilibrium model as an available tool for nonlinear fracture analysis. Through this study, the main results were reached as follows; Irwin's plastic zone corrected linear elastic fracture mechanics could be applicable only for small scale yielding problems as expected while the crack plane equilibrium model valid as a fracture model for large deformation fracture failure. However, the followings should be considered for the more precise evaluations of CPE model; 1) It is necessary to test more specimens which contain small cracks in the range of 2a/W<0.1. 2) It is important to detect the crack initiation point during the fracture test for determining an accurate fracture load. 3) Effects of specimen thickness in the fracture process zone should be examined.

• Korean Journal of Clinical Pharmacy
• /
• v.32 no.1
• /
• pp.13-19
• /
• 2022

Background: The use of combination therapy and fixed-dose combination therapy is increasing for the treatment of type 2 diabetes. Sodium glucose cotransporter-2 inhibitor (SGLT2i) is a drug class used in combination with metformin. Methods: Type 2 diabetes patients on SGLT2i/metformin combination therapy were extracted from the 2019 Health Insurance Review & Assessment Service-National Patients Sample. On July 1, 2019, SGLT2i and metformin fixed-dose combination (SGLT2i/metformin FDC) and two-pill combination (TPC) groups were identified, and a chi-square test and multiple logistic regression were performed. Results: Of total 2,992 patients, 1,077 (36%) were prescribed SGLT2i/metformin FDC and 1,915 (64%) were prescribed TPC. We found that the most common comorbidities were in the order of dyslipidemia, gastrointestinal disease, and hypertension. Multiple logistic regression analysis showed that the use of SGLT2i/metformin FDC was lower than TPC in patients with diabetic neuropathy (OR=0.76, p=0.008). Clinic (OR=2.09, p<0.001) and general hospital (OR=1.40, p=0.019) showed higher tendency to prescribe SGLT2i/metformin FDC compared to tertiary hospital. The tendency of prescribing SGLT2i/metformin FDC was lower in Kyeonggi (OR=0.79, p=0.037), Gyeongsang (OR=0.77, p=0.025) and Chungcheong (OR=0.68, p=0.007) than Seoul. Conclusion: Factors related to the use of SGLT2i/metformin FDC in patients with type 2 diabetes were complication, medical institution and region. The tendency to prescribe SGLT2i/metformin FDC was relatively higher in clinics than in tertiary general hospitals and in Seoul than in other regions.

• The Journal of the Acoustical Society of Korea
• /
• v.41 no.6
• /
• pp.680-690
• /
• 2022

Vibrations in the pipe system trigger fatigue-related issues and lead to fatal other problems caused by pipe damage. There are numerous studies to analyze and reduce the cause of pipe vibration, among which a small number of studies are being conducted on pipe vibration reduction using friction supports. The study of friction supports, however, focused only on predicting and evaluating the performance of the friction supports and seldomly considered the design perspective of the install location of the supports. Therefore, this study intends to suggest the optimization process for finding the best installation region of friction support to attenuate the vibration of entire piping system. The optimal position of the friction support is predicted only by linear analysis to guarantee optimization efficiency in the design process. The designed friction support location is verified by time domain analysis.

• Journal of Dental Rehabilitation and Applied Science
• /
• v.38 no.1
• /
• pp.26-33
• /
• 2022

Anterior tooth spacing is observed by pathological tooth movement (PTM), which is common in periodontal patients. And various occlusal factors contribute to PTM, especially in the maxillary anterior region, when there is excessive occlusal force, flaring due to position problem easily occurs. Teeth with loss of periodontal support tissue can secure stability when expanding the support area through intentional splinting, and change the occlusion when restored as a fixed prosthesis. After confirming the stable occlusion through the provisional prosthesis, it can be transferred to the final prosthesis through CAD-CAM. In this case, we present a long-term stable case through accurate diagnosis and treatment of the maxillary anterior teeth that have lost interdental contact.

• Journal of the Korean Electrochemical Society
• /
• v.8 no.1
• /
• pp.17-23
• /
• 2005

The electrochemical behaviors of polycrystalline silver electrodes in 8M KOH solutions containing $Bi_2O_3$ were studied under various conditions by cyclic voltammetry, potentiostatic and galvanostatic techniques as well as the morphology of the silver oxide structures by SEM. It was found that three new compounds comprising silver, bismuth, and oxygen as well as $Bi_2O_3$, $Ag_2O$ and AgO were formed during the electrochemical oxidation of silver. In addition, the potentiostatic current transients were characterized by the appearances of the first current peaks corresponding to the formation of silver oxides, and the second current peaks corresponding to the Ag-Bi-O compounds, indicating the presence of the nucleation and 3D growth mechanism, in the potential regions of $Ag_2O$ and AgO, respectively. Microscopic examinations showed that two types of silver (I) oxide morphologies are formed in the potential region of $Ag_2O$.

• Journal of the Korean Society of Industry Convergence
• /
• v.27 no.2_2
• /
• pp.475-485
• /
• 2024

In many regions of Korea, including the Four Major Rivers, the seriousness of the problem of algal blooms due to eutrophication of water quality is being raised.In this study, in order to solve these social problems, we manufactured a filter using natural mineral fusion (red illite, zeolite, germanium ceramic, selenium ceramic, carbon ceramic) and independently developed a tank system for green algae experiments to observe and determine the stages of change in water quality. In order to study ways to improve water quality through quantitative analysis, 1 ton of severely polluted green algae water from the Nak dong River region was stored in a water tank and exposed to ultraviolet rays in the same environment as the Nak dong River. Then, the same environment as the Nak dong River was created. The results were derived from a 5-week water quality test. The results of this experiment confirmed that green-colored cyano bacteria were significantly reduced just by the turbidity results. The results were obtained through a request to the Korea Testing & Research Institute located in Changwon-si, Gyeong sang nam-do. CI-(chlorine ion) and NH3-N(ammonia nitrogen) had the effect of saving every week. The device used in this study was made of natural minerals free of heavy metals that are harmless to the human body and nature through long-term consideration and exploration to kill and prevent various strains living in water. Green purification system using natural hydrogen generating mineral filter were effective a non-chemical and physical methods. The results of this study are one way to contribute to the serious problems caused by green algae in many countries, and will contribute to the water quality environment by preventing the waste of environmental resources, improving the health of the people, and increasing the ability to purify environmental water quality at home and abroad.

• Journal of Yeungnam Medical Science
• /
• v.41 no.2
• /
• pp.80-85
• /
• 2024

Background: This study aimed to compare and evaluate the marginal fit of nanocomposite computer-aided design/computer-aided manufacturing (CAD/CAM) inlays. Three types of nanocomposite CAD/CAM blocks (HASEM, VITA Enamic, and Lava Ultimate) were used as materials. Methods: Class II disto-occlusal inlay restorations were prepared on a typodont mandibular right first molar using diamond rotary instruments. The inlays were fabricated using CAD/CAM technology and evaluated using the silicone replica technique to measure marginal gaps at five locations on each inlay. The data were analyzed by two-way analysis of variance and Tukey post hoc tests (α=0.05). Results: There were no significant differences in the marginal gaps based on the type of nanocomposite CAD/CAM inlay used (p=0.209). However, there was a significant difference in the marginal gaps between the measurement regions. The gingival region consistently exhibited a larger marginal gap than the axial and occlusal regions (p<0.001). Conclusion: Within the limitations of this in vitro study, the measurement location significantly influenced the marginal fit of class II disto-occlusal inlay restorations. However, there were no significant differences in the marginal gaps among the different types of CAD/CAM blocks. Furthermore, the overall mean marginal fits of the class II disto-occlusal inlay restorations made with the three types of nanocomposite CAD/CAM blocks were within the clinically acceptable range.