• Journal of Korea Foundry Society
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• v.41 no.3
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• pp.235-240
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• 2021

We present the effect of the critical cooling rate during rapid solidification on the nucleation of precipitates in an Fe₇₅B₁₃P₅Nb₂Hf₁C₄ (at.%) alloy. The thermophysical properties of the rapidly solidified Fe₇₅B₁₃P₅Nb₂Hf₁C₄ liquids, which were obtained at various cooling rates with various sizes of gas-atomized powder during a high-pressure inert gas-atomization process, were evaluated. The cooling rate of the small-particle powder (≤20 ㎛) was 8.4×10⁵ K/s, which was 13.5 times faster than that of the large-particle powder (20 to 45 mm; 6.2×10⁴ K/s) under an atomized temperature. A thermodynamic calculation model used to predict the nucleation of the precipitates was confirmed by the microstructural observation of MC-type carbide in the Fe₇₅B₁₃P₅Nb₂Hf₁C₄ alloy. The primary carbide phase was only formed in the large-particle gas-atomized powder obtained during solidification at a slow cooling rate compared to that of the small-particle powder.

• International Journal of Advanced Culture Technology
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• v.9 no.1
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• pp.16-21
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• 2021

As the average age of national veterans has increased from 69 years old(2011) to 71 years old(since 2015) over the past five years, the overall medical service cost of veterans has increased by about 20%. The main cause of this phenomenon is 'ultra-aging', which accounts for 67% of veterans, while the proportion of health insurance patients aged 70 or older is 9%. Therefore, it is judged that the analysis of the trend of use of medical services at veterans hospitals in each region that is in charge of severe medical services of national veterans can serve as an opportunity to seek countermeasures for the severe medical system of national veterans. First of all, based on the details of major medical expenses (hospitalization, outpatient, pharmaceutical expenses) by region for the last 10 years(2010-2019), data significance was performed through a chi-square test, and the Central Veterans Hospital and Non-Central Veterans Hospital using EXCEL. 'Expected frequency' was calculated by year. By applying the CHITEST(observation frequency, expected frequency) function again, the p-value(p<0.05) was calculated, and the profit bias of each region's veterans hospital could be determined. The specific research method is for the last 10 years(2010-2019) for state-sponsored patients_outpatient treatment income, state-sponsored patients_hospitalization income, exempt patients_outpatients at the Central Veterans Hospital, Busan Veterans Hospital, Gwangju Veterans Hospital, Daegu Veterans Hospital, and Daejeon Veterans Hospital. A one-way analysis of variance was conducted to verify the significance of the difference between group averages on the status of 5 medical revenues of veterans hospitals in each of the 5 regions, including medical treatment income, reduced patients_hospitalization income, and reduced patients_medicine expenses. It was found to be significant(p<0.05) at all levels, including region and type. Finally, the bias in the profit structure of regional veterans hospitals was the highest in 2017(p=0.0004) and the lowest in 2013(p=0.0349). In addition, in the profit structure of the Veterans Hospital, the year in which the'regional' variable worked the most was 2019, and the year with the least affected was 2010. The order of the former is Jungang(=31,674,713), Busan(=12,314,614), Gwangju(=11,957,038), Daegu(=10,168,015), and Daejeon(=6,991,034), and the order of the latter is Jungang(=57,868,791), and Busan(=19,183,194). Gwangju(=17,904,712), Daegu(=15,656,034), and Daejeon(=14,377,395). In conclusion, the profit bias of veterans hospitals repeatedly raced the lowest(p=0.01986) and highest(p=0.03499) for the past five years(2010-2014) year by year, with the 'regional' variable being the most in the veterans hospital's profit structure It was identified as a major influence factor. On the other hand, for the last 5 years (2015-2019), the influence factors of the'regional' variable every year were in 2015(p=0.02015), 2016(p=0.01741), 2017(p=0.00045), and 2018(p=0.00394). in 2019(p=0.00227), a significant difference was confirmed at a very low level.

• Journal of Korea Water Resources Association
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• v.55 no.1
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• pp.33-42
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• 2022

In this study, flow patterns in the ice-harbor fishway were analyzed according to fluctuations of the upstream water level, an increase of weir interval, and the presence or absence of orifices using a three-dimensional commercial numerical model, Flow-3D. In order to prove the suitability of the numerical simulation results, the flow velocity and flow rate at the exit of the fishway were observed using a 3D ultrasonic velocimetry on an actual ice-harbor fishway installed downstream of the Daegok bridge in Gyeongan-Cheon. Four types of turbulence modules can be selected for the Flow-3D model. As a result of verification with observation data, the RNG model best described the flow characteristics in the ice-harbor fishway. The velocity structure in the fishway according to fluctuations of the upstream water level was simulated. The results showed that the plunging flow and the streaming flow were mixed at the lowest water level. When the water level increased about 10 cm or more from the lowest water level, the plunging flow disappeared in all pools and only the streaming flow occurred. Contrary to expectations, even when the water level is rose a little, the flow simply occurred mainly on the streaming flow. If the interval between the weirs is increased, both the plunging flow and the streaming flow are showed continued even if the water level rises. In addition, compared to the case where there are no orifices at the bottom of the weirs, the plunging flow tends to be generated in several pools. It is necessary to prevent blocking orifices through active management so that various flow patterns in the fishway can be generated in multiple pools.

• Journal of the Korean earth science society
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• v.42 no.6
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• pp.700-716
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• 2021

This study is based on the importance of observation or exploration in contemporary scientific inquiry and the need to expand the learning materials of science inquiry. It aims to analyze students' characteristics of exploration in abduction by developing and applying an educational program using art materials. For this study, a program named "Scientist going to the museum" utilizing artistic materials such as Oriental and Western paintings, mythology, orchestral suite, and traditional houses, was developed and five middle school students participated. Students who found and explored interesting phenomena in the work were divided into three main groups depending on the characteristics of the exploration activity. Some students observed and described elements that could be connected to scientific concepts, while others mainly explored everyday elements that were relatively unrelated to such concepts. Moreover, another type of students explored the works based on their subjective evaluations. This study shows that learning materials that cannot be visually explored are not suitable for abductive activities that students' prior knowledge has a significant impact on their exploration, and that educational materials for earth science inquiry could be expanded. This study also provides an example of learning materials and methods, and that abduction may be utilized for learning astronomy.

• Korean Journal of Heritage: History & Science
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• v.55 no.1
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• pp.5-34
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• 2022

The purpose of this study is to investigate the unique contrasting landscape characteristics of imperial tombs of Qing dynasty by examining the characteristics of facility layout in which location, Feng shui, and siblings are harmonized with the 12 Qing Dynasty Hwanggyeongchim. Through literature surveys, field observation and interviews, videos and drawing comparison, and inductive contrast analysis, the contrasting landscape characteristics of imperial tombs in the Qing Dynasty were analyzed by classifying them into natural environment, location, Feng shui, and formal esthetics. As a result, the characteristics of the location type and the layout plan of the Qing dynasty imperial tombs were derived from the analysis of Feng shui shape, axis extension distance along the midaxial line, the width of the ridge, the formality of the facility layout according to the difference between the height of the starting point and the end point, the leftward direction of the tomb, and the space ratio of the 'entry space' - 'ritual space' - 'burial mound space', etc. In addition, it was possible to derive the facility arrangement characteristics of tombstones through the analysis of the types and the arrangement order of tombs facilities, as well as the distribution, quantity and types of stone figures, while also revealing some contrasting characteristics different from those of the Ming Dynasty. In addition, it was confirmed that the spatial division effect through the water system and the view effect of the view from the midaxial line and the vista are the representative view effect found in the Qing Dynasty imperial tombs along with the density contrast.

• Journal of Digestive Cancer Reports
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• v.9 no.1
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• pp.1-7
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• 2021

The length, the frequency, and the methods of surveillance for intraductal papillary mucinous neoplasm (IPMN) of the pancreas are still debating. According to the recent guidelines, IPMN is stratified into "high-risk stigmata" or absolute indication and "worrisome features" or relative indication as a guide in managing these patients, either those with resection of the lesion or those under surveillance. The risk of malignant transformation was quite low for branch duct-IPMNs without worrisome features or high risk stigmata. However, because the incidence rate of pancreatic cancer in these patients increase linearly with time, continued long-term surveillance is therefore important for patients with low-risk, as well as higher-risk, IPMN. Considering the high prevalence of malignancy, main duct-IPMN should be treated by surgical resection. Among patients with these type IPMNs, segmental dilatation of the main pancreatic duct without any mural nodules and larger than 10 mm of main pancreatic duct might not be immediately resected and need very careful examination and observation. The risk related to a major pancreatic resection must balance the risk of surveillance in patients with IPMN of the pancreas who have co-morbidity and are elderly.

• Journal of Dental Rehabilitation and Applied Science
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• v.38 no.3
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• pp.138-149
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• 2022

The clinical applicability of ceramics can be increased by analyzing the causes of fractures after fracture testing of dental ceramics. Fractography to analyze the cause of fracture of dental ceramics is being widely applied with the development of imaging technologies such as scanning electron microscopy. Setting the experimental conditions is important for accurate interpretation. The fractured specimens should be stored and cleaned to avoid contamination, and metal pretreatment is required for better observation. Depending on the type of fracture, there are dimple rupture, cleavage, and decohesive rupture mainly observed in metals, and fatigue fractures and conchoidal fractures observed in ceramics. In order to reproduce fatigue fracture in the laboratory, which is the main cause of fracture of ceramics, a dynamic loading for observing slow crack growth is essential, and the load conditions and number of loads must be appropriately set. A typical characteristic of a fracture surface of ceramic is a hackle, and the causes of fracture vary depending on the shape of hackle. Fractography is a useful method for in-depth understanding of fractures of dental ceramics, so it is necessary to follow the exact experimental procedure and interpret the results with caution.

• Journal of Digestive Cancer Research
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• v.3 no.1
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• pp.30-34
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• 2015

We report a case of a 55-year-old man who diagnosed with advanced gastric cancer (AGC), with A review of the literature. A 55-year old man was transferred to our hospital for further evaluation and treatment after being diagnosed with adenocarcinoma through endoscopic biopsy during a regular health examination. An abdominal computed tomography (CT) showed AGC, stage IIA (T3N3M0), while an endoscopic examination showed AGC, Borrmann type 2. The patient is currently under observation after undergoing radical subtotal gastrectomy with gastroduodenostomy and subsequent administration of oral chemotherapeutic agents. As an abdominal CT response assessment performed after surgery revealed new metastasis to the liver, the patient received palliative chemotherapy as progressive disease was suspected. After receiving chemotherapy in the order of FOLFOX (5-fluorouracil (5-FU)) + Leucovorin + Oxaliplatin), FOLFIRI (5-FU + Leucovorin + Irinotecan), EAP-II (Etoposide + Doxorubicin + Cisplatin), ELF (Etoposide + Leucovorin + 5-FU), TS-1 (Tegafur + Gimeracil) + Cisplatin, an abdominal CT response assessment showed progressive disease for which the regimen was altered to PFL (Paclitaxel + 5-FU + Leucovorin). The patient has currently completed his second cycle of chemotherapy and after an abdominal CT response assessment, further course of therapy will be decided.

• Resources Recycling
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• v.32 no.6
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• pp.10-17
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• 2023

Calcium silicate cement (CSC) is an environmentally sustainable, low-carbon cement and has garnered significant attention in recent studies. However, the pre-curing step required to activate the carbon dioxide reaction and to handle the sample. This study aimed to examine the viability of extending the application of CSC without pre-curing by enhancing initial strength by mixing calcium sulfoaluminate (CSA) fast-hardening cement into CSC. The investigation assessed changes in compression strength and Q-XRD mineral characteristics concerning variations in the mixing ratio of CSC and CSA fast-hardening cement within a carbon dioxide atmosphere. The compressive strength results indicated that the 3-day and 7-day strengths were 14.18 MPa and 22.98 MPa, respectively, under the 50% CSC condition, meeting the type 1 cement KS standard. Mineral characteristics analysis revealed an increase in calcite mineral, a byproduct of the carbon dioxide reaction, contributing to strength enhancement. Even after seven days, substantial quantities of unreacted rankinitene and pseudowollastonite were observed, as well as dicalcium silicate and yeelimite, which are hydrated minerals. This observation was confirmed the possibility of strength improvement after 7 days.

• Bangmulgwan gwa yeongu (The National Museum of Korea Journal)
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• v.1
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• pp.120-147
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• 2024

The inscribed bricks from the Tomb of Jang Mui are unique in many ways. First, there are nearly a hundred of them. Second, there are multiples bearing the same inscriptions. Third, their production methods, including type of firing, are diverse. Fourth, the forms of the bricks are inconsistent. Fifth, the positioning of the sides with inscriptions or stamped designs and those with no designs (as well as the vertical orientation of the inscriptions) are inconsistent. Sixth, most bricks bear inscriptions written reverseds. Seventh, white lime has been painted on the surfaces of the inscribed bricks. Despite these aspects, however, a comparison with Chinese inscribed bricks from the Weijin Dynasties reveals that the inscribed bricks from the Tomb of Jang Mui are indeed connected to their counterparts and provide important materials for forging a more holistic understanding of East Asian culture. Moreover, the understanding of the inscriptions as not just a series of Chinese characters, but as textual objects with characters stamped on them, a focus on how the inscribed bricks were placed inside the tomb, and the observation of them from viewers' perspectives can help clarify the significance of the inscribed bricks from the Tomb of Jang Mui.