• 한국초전도ㆍ저온공학회논문지
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• 제21권3호
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• pp.27-31
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• 2019

Large grain YBCO bulk superconductors are fabricated by the top-seeded melt growth (TSMG) or top-seeded infiltration growth (TSIG) method. Both growth methods use at least one of $YBa_2Cu_3O_{7-{\delta}}$, $Y_2BaCuO_5$, $BaCuO_3$ pre-reacted precursor powders. However, the synthesis of the pre-reacted powders includes multiple calcination runs which are cost-bearing and time-consuming. In this work, we report the successful growth of single-domain YBCO bulk superconductors directly by using the powder compact that has been pressed from the mixture of $Y_2O_3$, $BaCuO_3$ and CuO powders without any intermediate grinding step. Single-domain YBCO bulk superconductor has been also prepared by using $Y_2O_3$, $BaO_2$ and CuO powders without intermediate grinding step. Investigations on the trapped magnetic field and microstructure of the melt-processed specimen show that the elimination of the repeated processes of calcinations and pulverization has hardly affected on the crystal growth and the magnetic properties of the grown YBCO bulk superconductors. However, it is thought that the presence of residual carbon affects on the size of Y211 particles in melt-processed YBCO bulk superconductor.

• 한국기계기술학회지
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• 제20권6호
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• pp.770-775
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• 2018

In this study, the characteristics of muscle relaxation were analyzed by the experimental and numerical method. A skin tissue was produced by imitational biological tissue using the agar powder, saline solution and sugar. The tissue was exposed to three types of wavelength-blue visible radiation(410 nm), red visible radiation(635 nm), and infrared ray(830 nm). The temperature results along the depth of tissue were measured according to the variation of light wavelength and irradiation time. The temperature change of the tissue shown up similar pattern regardless of the light wavelength kinds. The wavelength of infrared ray penetrated strongly into tissue between 3.2 mm and 11.4 mm. Also, the temperature change with the irradiation time was small, and the temperature value of the infrared ray was the largest. As a result, the muscle relaxation will occur mainly at the infrared wavelength.

• 임상간호연구
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• 제27권1호
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• pp.109-119
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• 2021

Purpose: The purpose of this study was to identify and analyze the characteristics of nurses' medication errors during three years. Methods: Retrospective survey study design was used to analyze medication errors by nurses among patient safety accidents. Data were collected for three years from January, 2017 to December, 2019. Data were analyzed using frequency, percentage, 𝑥²-test, and logistic regression with SPSS 26.0 program. Results: Of a total 677 medication errors, 40.6% were caused by nurses. Among the medication errors, near miss (n=154, 56.0%), intravenous bolus injection (n=170, 61.8%), wrong dose (n=102, 37.1%) and carelessness for repetitive work (n=98, 35.6%) were the most common. Medication errors differed by department, and nurses' career, and patient safety accident type. The results of the logistic regression analysis showed that the risk factors of adverse events were medication of fluids (OR=3.93, 95% CI: 1.26~12.27), insulin subcutaneous injection (OR=39.06, 95% CI: 4.58~333.18), and occurrence of extravasation/infiltration (OR=7.26, 95% CI: 1.85~28.53). Conclusion: The simplest and most effective way to prevent medication errors is to keep 5 right, and a differentiated education program according to department and nurse career is needed rather than general education programs. Hospital-level integrated interventions such as a medication barcode system or a team nursing method are also necessary.

• Nuclear Engineering and Technology
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• 제54권4호
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• pp.1161-1166
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• 2022

Green pitch coke with an average particle size of 2 mm was adopted as densifier and added to the raw materials of conventional A3-3 matrix graphite (MG) to prepare modified A3-3 matrix graphite (MMG) by the quasi-isostatic molding method. The structure, mechanical and thermal properties were assessed. Compared with MG, MMG had a more compact structure, and exhibited improved properties of higher mechanical strength, higher thermal conductivity and better molten salt barrier performance. Notably, under the same infiltration pressure of 5 atm, the fluoride salt occupation of MMG was only 0.26 wt%, whereas it was 15.82 wt% for MG. The densification effect of green pitch coke endowed MMG with improved properties for potential use in the spherical fuel elements of molten salt reactor.

• Geomechanics and Engineering
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• 제32권1호
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• pp.85-96
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• 2023

Microbially induced carbonate precipitation (MICP) is extensively discussed as a promising topic for ground stabilization. The practical effect of stabilizing the expansive soil is presented in this paper with a logical process from the bacterial activity to the treatment technology. Temperature, pH, shaking frequency, and inoculation amount are discussed to evaluate the bacterial activity. The physic-mechanic properties are also evaluated to discuss the effect of the MICP process on expansive soil. Results indicate that the MICP method achieves the mitigation of expansion. The treated soil has a low proportion of fine particles (< 5 ㎛), the plasticity index significantly decreases, and strength values improve much. MICP process has a significant cementation effect on the soil matrix. Moreover, the infiltration model test presents the coating effect on the topsoil. According to the relation between the CaCO₃ content and the treatment effect, the topsoil has better treatment than the deeper soil.

• Geomechanics and Engineering
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• 제33권2호
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• pp.155-165
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• 2023

Hurricane Katrina swept New Orleans, Louisiana, USA, in 2005, causing more than 1,000 fatalities and severe damage to the flood protection system. Recovery activities are complete, however, clarifying failure mechanisms and devising resilient and cost-effective retrofitting techniques for the flood protection system are still of utmost importance to enhance the general structural integrity of water retaining structures. This study presents extensive centrifuge test results to find various failure mechanisms and effective retrofitting techniques for a levee system. The result confirmed the rotational failure and translational failure mechanisms for the London Ave. Canal levee and 17^th St. Canal levee, respectively. In addition, it found that the floodwalls with fresh waterstop in their joints perform better than those with old/weathered waterstop by decreasing pore water pressure build-up in the levee. Structural caps placed on the top of the joints between I-walls could also prevent local failure by spreading the load to surrounding walls. At the same time, the self-sealing bentonite-sand mixture installed along the riverside of floodwalls could mitigate the failure of floodwalls by blocking the infiltration of seepage water into the gap formed between levee soils and floodwalls.

• Archives of Metallurgy and Materials
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• 제63권3호
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• pp.1485-1488
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• 2018

The effect of additives on the densification behavior and mechanical properties of pure and additive (Zr, B and Mg)-added silica ceramics were investigated for their application to the matrix phase of a silica fiber reinforced silica (SiO₂/SiO_2f) composite. The additives affected the rate of densification and crystallization (or transformation) of the amorphous silica. Among the compositions, pure silica ceramics sintered at 900℃ for 1 h showed the maximum flexural strength. Based on the results, SiO₂/SiO_2f was fabricated by a repeated vacuum-assisted infiltration method followed by the heat treatment at 900℃ for 1 h. The relative density of the composite was 78.2% with a flexural strength of 22.4 MPa. Fractography revealed that the composite was damaged by strong bonding at the fiber/matrix interface and the fracture of fiber.

• Toxicological Research
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• 제21권2호
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• pp.141-150
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• 2005

1,3-Dichloro-2-propanol (1,3-DCP) is known as chloride chemicals and causes severe hepatotoxic agent. The Ito cells and Kupffer's cells of the liver in the 5 old F344 Rats were exposed to 1,3-DCP gas chamber for 6 hours/ a day, 5 days/ a week, and 13 weeks, in the 0, 5, 20, 80 ppm, respectively. After then the body weights, liver weights, and relative liver weight to body weight were measured, and the hepatic tissues were prepared by the routine and Immunostain method, and observed by the LM, and EM. In the results, there were severe body weight decrease (p<0.05) in the 80 ppm of the male and female rats. The relative liver weights to the body weight were increased relate with exposed 1,3-DCP concentration (P<0.001). Inflammatory cells, infiltration was observed at the perivascular area in the 20 ppm exposed group, and bilirubin pigment infiltration, bile duct hyperplasia, inflammation hepatocytic necrosis, fibrosis were observed in the 80 ppm exposure group. In the 80 ppm exposure group, disarrangement of the endothelial cells, erythrocytes and hepatic cell fragment in the Disse space and numerous migration macrophages were observed in the necrotic area by EM observation. In the immunostained hepatic tissues positive stained ED1 cells were extremely increased (P<0.05) in central vein area, but ED2 was weakly positive immunostained in the 80 ppm exposed group. Immunostained desmin was observed in the Ito cell. It was no difference in the low and medium exposed group but it was typical increase in the necrotic area. In conclusion, These results suggest that NOAEL of 1,3-DCP may be 5 ppm in rats and the Immunostained of desmin, ED1 and ED2 positive cells activated in the inflammatory liver were related to the exposure volume and density. The increase of the Ito cells were related to the severe phagocytosis of the Kupffer's cells.

• 한국수자원학회논문집
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• 제50권5호
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• pp.303-313
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• 2017

우리나라에서는 도시 개발사업을 위한 환경영향평가를 실시하는데 있어 개발 전 중 후의 강우유출량을 분석하도록 규정하고 있다. 도시개발에 따른 수문학적 변화를 분석하고 대책을 수립하기 위해 수문모델이 사용되고 있으나 대부분의 경우 현장의 자료가 충분하지 않은 관계로 그 산정결과의 신뢰도가 문제될 수 있다. 본 연구에서는 대전의 관평천 일부유역에서 2015년 7월 부터 2016년 7월 까지 자동 모니터링 장치을 이용하고 또한 및 현장 측정을 통해 확보된 강우량 및 유출유량의 연속자료를 활용하여 SWMM을 이용하는 경우 강우 유출량 예측의 정확도를 제고하고자 하였다. 토양침투량 산정을 위해 대표적으로 사용되는 Curve Number 방법, Horton 방법 및 Green-Ampt 방법들을 사용한 경우에 대해서 투수지역과 불투수 지역에 대해 각각 최적의 Manning 조도계수와 지표면 저류깊이를 산정하여 제시하였다. 본 연구의 결과는 우리나라의 도시 유역에서 실측자료를 이용하여 강우 유출 모델을 보정하였다는 면에서 의미가 있다고 판단되며 추후 유역의 개발등의 상황에 대해는 강우 시 유출량 및 수질현상을 더욱 정확하게 예측하고 나아가서 향후의 유역 내 수문조건 변화 요인에 대한 영향을 분석하는 데 정확도를 향상시킬 수 있을 것으로 기대된다.

• Korean Journal of Acupuncture
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• 제25권2호
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• pp.159-177
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• 2008

Objectives : Crohn's disease is a severe chronic inflammation that is treated mainly by immunosuppression, which often has serious side effects. There is need to develop new therapeutic methods or drugs that have few side effects in order to treat this disease. Acupuncture with Moxi-tar at Cheonchu (ST25) has anti-inflammatory properties, but the mechanism of its anti-inflammatory actions is unclear. We investigated the protective effects and speculated the mechanisms of acupuncture with Moxi-tar at ST25 on trinitrobenzene sulfonic acid (TNBS) induced colitis in mice which is a well known Crohn's disease animal model. Methods : 5 % TNBS was treated at day 1 and day 7 into rectum of mice. To investigate therapeutic effects of acupuncture with Moxi-tar at ST25, acupuncture was carried out on day 3, and day 6. For the data analysis, we observed macroscopic and microscopic findings of the colon. Weight and width of the colon, degree of damage, changes of body weight, and myeloperoxygenase (MPO) activity were checked. For analysing protein expression, we carried out immunohistochemical staining and Western blot. For analysing mRNA expression, RT-PCR was carried out. Results : TNBS induced damages on the colon of mice, while acupuncture of Moxi-tar at ST25 suppressed TNBS mediated damages similar to those on the colons of mice in the control (not treated with TNBS) group. The average body weight of TNBS treated mice (77.4%) was decreased compared with that of the control mice (105%), and acupuncture with Moxi-tar at ST25 suppressed the loss of body weight caused by TNBS (from 77.4% to 95.3%). TNBS induced infiltration of immune cells in all layers of the colon while acupuncture with Moxi-tar at ST25 suppressed infiltration of immune cells caused by TNBS. Furthermore, acupunctured with Moxi-tar at ST25 suppressed macro-, micro- colonic damages caused by TNBS. Acupunctured with Moxi-tar at ST25 dramatically improved the clinical and histopathological symptoms such as the increase in weight of the distal colon and the MPO activity in TNBS-induced colitis. Acupuncture with Moxi-tar at ST25 down-regulated the nuclear transcription factor kappa B ($NF-{\kappa}B$) activity and suppressed tumor necrosis factor-a (TNF-${\alpha}$), interleukin-$1{\beta}$ (IL-1${\beta}$), and intracellular adhesion molecule-1 (ICAM-1) expressions caused by TNBS. Conclusions : Acupuncture with Moxi-tar at ST25 helps recovery from the TNBS-induced colonic damage by down-regulation of $NF-{\kappa}B$ activity and suppressing of TNF-${\alpha}$, IL-1${\beta}$, and ICAM-1 expressions. This may be an important method for the treatment of Crohn's disease.