• 한국물환경학회지
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• 제37권4호
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• pp.306-314
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• 2021

The application of organic fertilizer could be accompanied by potential hazards to soil and humans due to trace metals. Livestock manure compost·liquefied fertilizer is a well-established approach for the stabilization of nutrients and the reduction of pathogens and odors in manures, which can be evaluated as compost·liquefied. In this study, the livestock manure compost·liquefied fertilizers produced at 333 liquid manure public resource centers and liquid fertilizer distribution centers were collected from May to December 2019. The nutrient content (nitrogen, phosphorus, and potassium), physicochemical properties, and heavy metal content were investigated. The livestock manure compost·liquefied fertilizer was measured using a mechanical maturity measurement device. The organic matter, arsenic, cadmium, mercury, lead, chromium, copper, nickel, zinc, E. coli (O157:H7), Salmonella, etc. of the livestock manure compost·liquefied fertilizers were analyzed. The average heavy metal content in the livestock manure compost·liquefied fertilizer was as follows: Cr 2.9 mg/kg (0.2~8.7 mg/kg), Cu 20.4 mg/kg (1.6~74.1 mg/kg), Ni 1.3 mg/kg (0.4~4.2 mg/kg), and Zn 79.8 mg/kg (3.0~340.7 mg/kg). Although large-scale organic fertilizer plants and resources recycling centers produce good organic (liquid) fertilizers with proper components, it is necessary to standardize livestock manure compost·liquefied fertilizer in order to facilitate efforts to turn livestock manure into useful resources.

• 한국융합학회논문지
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• 제9권12호
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• pp.1-7
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• 2018

미소칩을 PCB상에 실장하는 장비에서 그 칩을 이동해주는 역할은 겐트리가 하고 있다. 그런데 겐트리의 기계적 한계 때문에 생산성을 증가시키는 것은 쉽지 않다. 따라서 본 논문에서는 생산성을 높일 수 있는 방법을 소프트웨어적으로 해결하고자 한다. 이를 위해 겐트리의 이동 시간을 단축함으로써 생산성을 향상시킬 수 있는 방법을 제시한다. 먼저, 현재 사용하고 있는 방법(stop-motion)에 대해 총 이동 시간을 계산해 보았다. 그리고 본 논문에서 제시하는 이동 시간 단축 방법(moving-motion)에 대해서도 총 이동 시간을 계산해 보았다. 이 방법은 카메라 앞에서 멈추지 않고 부품 검사를 함으로써 이동 시간을 줄이는 것이다. 그 결과 본 논문에서 제시한 방법이 16%의 시간을 단축하였음을 보여주었다. 향후에는 다른 타입에 대해서도 시간 계산 방법을 연구하는 것이다.

• 대한조선학회논문집
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• 제56권4호
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• pp.373-382
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• 2019

This paper shows numerical results for the estimation of the propulsor efficiency of Pre-Swirl Duct for 176k bulk carrier as well as its design method. Reynolds averaged Navier-Stokes equations have been solved and the k-epsilon model applied for the turbulent closure. The propeller rotating motion is determined using a sliding mesh technique. The design process is divided into each part of Pre-Swirl Duct, duct and Pre-Swirl Stator. The design of duct was performed first because it is located further upstream than Pre-Swirl Stator. The distribution of velocity through the duct was analyzed and applied for the design of Pre-Swirl Stator. The design variables of duct include duct angle, diameter, and chord length. Diameter, chord length, equivalent angle are considered when designing the Pre-Swirl Stator. Furthermore, a variable pitch angle stator is applied for the final model of Pre-Swirl Duct. The largest reduction rate of the delivered power in model scale is 7.6%. Streamlines, axial and tangential velocities under the condition that the Pre-Swirl Duct is installed were reviewed to verify its performance.

• 전기전자학회논문지
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• 제23권3호
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• pp.832-838
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• 2019

본 논문에서는 차세대 전력 반도체 소자인 4H-SiC MOSFET에 대해 연구하였다. 특히 3300V급에서 기존의 DMOSFET 구조보다 개선된 전기적 특성을 갖는 Semi-SuperJunction MOSFET 구조를 제안하였으며, TCAD 시뮬레이션을 통해 기존의 MOSFET과 전기적 특성을 비교 분석하였다. Semi-SJ MOSFET 구조는 부분적으로 SJ를 도입한 구조로, 2차원의 공핍 효과를 통해 전계 분포가 개선되며, 항복 전압이 증가한다. 항복 전압의 개선을 통해 얻은 이득으로, 높은 농도의 도핑이 가능하기 때문에 온 저항을 개선시킬 수 있다. 제안한 Semi-SJ MOSFET 구조는 DMOSFET보다 항복 전압이 8% 감소하지만, 온 저항이 80% 감소한다. 또한 DMOSFET 구조를 개선한 Current Spreading Layer(CSL)구조에 비해서도 온 저항이 44% 감소한다.

• 한국응급구조학회지
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• 제25권2호
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• pp.19-38
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• 2021

Purpose: This study aimed to investigate the relationship between emergency medical service accessibility in different regions and the sudden death rate in elderly patients with ischemic heart disease using data analysis techniques and suggest improvements in regional emergency medical services. Methods: The study collected data from the NEDIS database and Statistics Korea. Data on a total of 75,867 patients aged ≥65 years were reviewed among patients with ischemic heart disease who visited emergency medical institutions in 2018. Frequency analysis, chi-square test, multiple logistic regression analysis, and simple logistic regression analysis were performed using SPSS PC Window 25.0. Results: With an emergency medical resource per 100km², there was a concomitant reduction in the risk of death. There was a decrease in the death rate by 0.967, 0.970, 0.997, and 0.391 times with the increase in the presence of a fire department, an ambulance, a paramedic, and a regional medical center, respectively. Furthermore, a decrement in the death rate was witnessed 0.844, 0.825, and 0.975 times with the initiation of a local emergency medical center, a local emergency medical institution, and an angiography device, respectively(p <.001). Conclusion: To improve the accessibility of emergency medical services, the population and geometric area of the region should be considered essential factors when deploying emergency medical resources.

• 대한금속재료학회지
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• 제56권12호
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• pp.910-914
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• 2018

Since catalyst technology is one of the promising technologies to improve the working performance of next generation energy and electronic devices, many efforts have been made to develop various catalysts with high efficiency at a low cost. However, there are remaining challenges to be resolved in order to use the suggested catalytic materials, such as platinum (Pt), gold (Au), and palladium (Pd), due to their poor cost-effectiveness for device applications. In this study, to overcome these challenges, we suggest a useful method to increase the surface area of a noble metal catalyst material, resulting in a reduction of the total amount of catalyst usage. By employing block copolymer (BCP) self-assembly and nano-transfer printing (n-TP) processes, we successfully fabricated sub-20 nm Pt line and cross-bar patterns. Furthermore, we obtained a highly ordered Pt cross-bar pattern on a Ni thin film and a Pt-embedded Ni thin film, which can be used as hetero hybrid alloy catalyst structure. For a detailed analysis of the hybrid catalytic material, we used scanning electron microscope (SEM), transmission electron microscope (TEM) and energy-dispersive X-ray spectroscopy (EDS), which revealed a well-defined nanoporous Pt nanostructure on the Ni thin film. Based on these results, we expect that the successful hybridization of various catalytic nanostructures can be extended to other material systems and devices in the near future.

• The Korean Journal of Pain
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• 제34권3호
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• pp.304-314
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• 2021

Background: The study investigated virtual reality (VR) immersion in alleviating procedure-related pain in patients with chronic pain undergoing fluoroscopy-guided minimally-invasive intervention in a prone position at an outpatient clinic. Methods: In this prospective randomized controlled study, 38 patients undergoing lumbar sympathetic ganglion block were randomized into either the VR or the control group. In the VR group, procedure-related pain was controlled via infiltration of local anesthetics while watching a 30-minute VR hypnotic program. In the control group, the skin infiltration alone was used, with the VR device switched off. The primary endpoint was an 11-point score on the numerical rating scale, indicating procedure-related pain. Patients' satisfaction with pain control, anxiety levels, the need for additional local anesthetics during the procedure, hemodynamic stability, and any adverse events were assessed. Results: Procedure-related pain was significantly lower in the VR group (3.7 ± 1.4) than in the control group (5.5 ± 1.7; P = 0.002). Post-procedural anxiety was lower in the VR group than in the control group (P = 0.025), with a significant reduction from pre-procedural anxiety (P < 0.001). Although patients' satisfaction did not differ significantly (P = 0.158) between the groups, a higher number of patients required additional local anesthetics in the control group (n = 13) than in the VR group (n = 4; P = 0.001). No severe adverse events occurred in either group during the study. Conclusions: VR immersion can be safely used as a novel adjunct to reduce procedural pain and anxiety during fluoroscopic pain intervention.

• 대한의생명과학회지
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• 제27권2호
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• pp.99-104
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• 2021

Treatment techniques that affect homeostasis by non-invasive regulation in peripheral organs will advance disease research. Here, we demonstrate a non-invasive method of conditioning within an organ using a low-frequency stimulator superposition of alternating microcurrent wave in stages. It is first applied to the inflammatory response in H3N2-infected sinusitis mice. To check the progress of the treatment, mice were sacrificed every week for 3 weeks, nasal tissue was removed, and the inflammatory response was investigated through H & E staining. The low-frequency stimulation treatment group was found to alleviate the proliferation of epithelial cells and invasion of inflammatory cells compared to the control group as the passage of treatment time. The reduction of inflammatory cytokines in the nasal lavage fluid was observed in H3N2-infected sinusitis mice treated with of low-frequency stimulation using superposition of alternating microcurrent wave compared to H3N2-infected sinusitis mice after 3 weeks. These data demonstrate that low-frequency stimulation device in the form of using alternating current wave superposition on within organs provides a new method to regulate specific physiological functions. Therefore, it is necessary to prove the inhibitory effect of low-frequency stimulation using alternating current wave superposition on inflammatory diseases by various methods through further studies and clinical studies.

• 한국농공학회논문집
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• 제63권1호
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• pp.37-48
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• 2021

The automatic-spreader of bedding materials was developed to reduce labor cost, and to achieve successful biosecurity in duck houses. Algorithm of the device was designed to realize a concept of the automatic unmanned operation including entire processes such as loading and spreading of the bedding materials. From the field measurement, the relationship between the expected water content reduction and weight of bedding materials per unit area according to the operation condition of the devices was induced. In the case of the measurement of particulate matters during the process of spreading works, the results of using both conventional manual-spreader and automatic-spreader were exceeded the allowable limit of inhalable and respirable dust, respectively. But, workers using automatic-spreader could be free from harmful aero-condition because they did not stay inside the facility during the spreading works. In addition, from the Duck hepatitis virus PCR test, influence on pulmonary tissue of the duck was not found. It could be expected that the development of the automatic-spreader of bedding materials for duck house can contribute to the advancement of duck breeding facilities.

• 한국전문물리치료학회지
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• 제28권1호
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• pp.65-71
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• 2021

Background: The hamstring is a muscle that crosses two joints, that is the hip and knee, and its flexibility is an important indicator of physical health in its role in many activities of daily living such as sitting, walking, and running. Limited range of motion (ROM) due to hamstring tightness is strongly related to back pain and malfunction of the hip joint. High-frequency diathermy (HFD) therapy is known to be effective in relaxing the muscle and increasing ROM. Objects: To investigate the effects of HFD on active knee extension ROM and hamstring tone and stiffness in participants with hamstring tightness. Methods: Twenty-four participants with hamstring tightness were recruited, and the operational definition of hamstring tightness in this study was active knee extension ROM of below 160° at 90° hip flexion in the supine position. HFD was applied to the hamstring for 15 minutes using the WINBACK device. All participants were examined before and after the intervention, and the results were analyzed using a paired t-test. The outcome measures included knee extension ROM, the viscoelastic property of the hamstring, and peak torque for passive knee extension. Results: The active knee extension ROM significantly increased from 138.8° ± 9.9° (mean ± standard deviation) to 143.9° ± 10.4° after the intervention (p < 0.05), while viscoelastic property of the hamstring significantly decreased (p < 0.05). Also, the peak torque for knee extension significantly decreased (p < 0.05). Conclusion: Application of HFD for 15 minutes to tight hamstrings immediately improves the active ROM and reduces the tone, stiffness, and elasticity of the muscle. However, further experiments are required to examine the long-term effects of HFD on hamstring tightness including pain reduction, postural improvement around the pelvis and lower extremities, and enhanced functional movement.