The seismic behaviors of the arch structure vary according to the rise-span ratio of the arch structure. In this study, the rise-span ratio (H/L) of the example arch structure was set to 1/4, 1/6, and 1/8. And the installation angle of the seismic isolator was set to 15°, 30°, 45°, 60° and 90°. The installation angles of the seismic isolator were set by analyzing the horizontal and vertical reaction forces according to the rise-span ratio of the arch structure. Due to the geometrical and dynamic characteristics of the arch structure, the lower the rise-span ratio, the greater the horizontal reaction force of the static load, but the smaller the horizontal reaction force of the dynamic load. And if the seismic isolator is installed in the direction of the resultant force of the reaction forces caused by the seismic load, the horizontal seismic response becomes small. Also, as the installation angle of the seismic isolator increases, the hysteresis behavior of the seismic isolator shows a plastic behavior, and residual deformation appears even after the seismic load is removed. In the design of seismic isolators for seismic response control of large space structures such as arch structures, horizontal and vertical reaction forces should be considered.

Extended PE double-walled pipe is a technology that hollow walled pipe widens hollow wall to the side extruded as a square and extrudes the form added with a stiffener of I-BEAM shape from the time of initial pressing out when producing existing double walled pipe. It can improve production speed 1.6 times faster. Plastic pipes used in study were PE pipe, especially HDPE pipe that is safe from reproduction of seaweed and bacteriomycota and can be used semi permanently as a few corrosion by corrosive substance existing in soil is made. The purpose of this study is to decrease production time and increase outputs by extending width of extruding side 1.5 times wider when producing PE double walled pipe through making existing double walled pipe into extended PE double wall. Also, it is aimed to develop an extended PE double-wall pipe that can eliminate causes of defect occurred by middle pipe wound around with drawing machine 90°when producing existing goods.

연안통발 어민에 대한 설문조사 결과, 통발 투하 및 인양 중 로프 걸림에 따른 전도사고가 42.1 %로 가장 높았고, 갑판에서 미 끄러짐과 통발 권양장치의 신체 협착사고가 각각 21.1 %를 차지하였다. 또한 가장 위험한 작업은 전체 조사대상의 53.2 %가 통발 인양과 정을 들었고, 어종선별 33.8 %, 통발 투하 9.1 % 순으로 응답하였다. 어민들은 통발 권양장치의 주요 개선 요구사항으로 응답자의 36.8 %와 31.6 %가 통발을 수중에서 작업갑판까지 수월하게 인양하는 방안과 통발 인양 시 로프 장력 극복과 슬립 방지 등 사고저감 방안을 언급하 였다. 본 연구에서 소형 통발어선 권양장치는 구동롤러와 로프 간의 적정한 접촉각을 통해 로프의 접촉면적과 마찰계수를 증가시킴으로 써 권양력을 높이는 것이다. 구동롤러와 로프 간의 접촉각이 1°, 5°, 9°, 14° 및 19°일 때 로프 장력은 각각의 접촉각에 따라 차이를 보였으 며, 9°일 때 가장 높은 392.62 kgf까지 측정되었다. 이러한 실험결과를 반영하여 시제품 권양장치를 제작하고 총 길이가 100 m인 로프에 4 m 간격으로 총 25개의 통발을 해상에 설치한 후 인양에 따른 로프 장력을 측정하였다. 그 결과, 로프 장력은 통발 인양작업 초기에 급격히 증가하여 가장 높은 31.89 kgf로 측정되었으며, 이후에는 크게 낮아졌다. 따라서 소형 통발어선 권양장치의 권양력은 인양작업 초기에 부 여되는 최대 로프 장력 값을 기준으로 설계하는 것이 타당하다.

The use of dampers is being considered a means to improve the seismic performance of buildings. It may take considerable time and effort to find an optimal design solution since repeated three-dimensional nonlinear time history analyses are required. Therefore, a preliminary design procedure for seismic retrofit using hysteretic dampers was proposed in this study. In the proposed procedure, the amount of retrofit (required number of dampers) is estimated from the capacity curve of the building before retrofit and allowable story drift of the building. In combining the capacity curves of the building and the dampers, the deformation demand for the dampers can be easily checked against their deformation capacity. The equations to transform the device displacement to roof displacement for the combination of capacity curves are developed. The proposed procedure was applied to the seismic retrofit design of sample buildings. The study found that the estimated capacity curve was very close to the actual capacity curve obtained from the pushover analysis, which can determine an appropriate configuration to meet the required seismic performance.

Pest control treatment was carried out using an unmanned automatic pesticide spraying system that can spray pesticides on crops while moving autonomously to control pests in vegetable greenhouse. As a result of examining the control effect on tomato and strawberry on thrips (Frankliniella occidentalis) and greenhouse whitefly (Trialeurodes vaporariorum) pests, 85.6% of yellow flower thrips were found in tomatoes and 87.5% in strawberries, and 81.7% (tomato) and 80.6% (strawberry) of greenhouse whitefly. In addition, the control effect according to the pesticide treatment method showed a control effect of 81.7% of the chemical spraying treatment by manpower and 83.9% of the automatic moving pesticide spraying treatment (F=22.1, p < 0.001). When comparing the control effect between the two treatment sections, there was no significance, but the automatic transfer spraying treatment showed a 2.2% higher effect. On the other hand, as a result of comparing the spraying time of the drug, the automatic unmanned control sprayer had a spraying time of 5 min/10a, which took about 25 min less than the conventional manpower spraying time of 25－30 min/10a. Based on these results, it was judged that the automatic transfer spraying method could be usefully used for efficient pest control in the facility greenhouse during the peak period of development.

Aluminum nitride having a dense hexagonal structure is used as a high-temperature material because of its excellent heat resistance and high mechanical strength; its excellent piezoelectric properties are also attracting attention. The structure and residual stress of AlN thin films formed on glass substrate using TFT sputtering system are examined by XRD. The deposition conditions are nitrogen gas pressures of 1 × 102, 6 × 103, and 3 × 103, substrate temperature of 523 K, and sputtering time of 120 min. The structure of the AlN thin film is columnar, having a c-axis, i.e., a <00·1> orientation, which is the normal direction of the glass substrate. An X-ray stress measurement method for crystalline thin films with orientation properties such as columnar structure is proposed and applied to the residual stress measurement of AlN thin films with orientation <00·1>. Strength of diffraction lines other than 00·2 diffraction is very weak. As a result of stress measurement using AlN powder sample as a comparative standard sample, tensile residual stress is obtained when the nitrogen gas pressure is low, but the gas pressure increases as the residual stress is shifts toward compression. At low gas pressure, the unit cell expands due to the incorporation of excess nitrogen atoms.

Purpose: This study aimed to understand the effect of extra-corporeal membrane oxygenation (ECMO) preparation education implemented with smart glasses in augmented reality on the performance ability, performance confidence, and educational satisfaction of clinical nurses. Method: The participants were clinical nurses at B hospital—27 in the experimental group and 25 in the control group. The measurement tools were performance ability (24 items), performance confidence (11 items), and educational satisfaction (9 items). The experimental group intervention used augmented reality with smart glasses, and the control group used video resources. The collected data were analyzed by t-test, x2-test, and ANCOVA using the SPSS Statistics for Windows, version 25.0. Results: The performance was significantly higher in the experimental group than in the control group (F = 104.83, p < .001). Performance confidence was considerably higher in the experimental group than in the control group (F = 2.09, p = .041). Finally, educational satisfaction was significantly higher in the experimental group than in the control group (F = 4.52, p < .001). Conclusion: It was confirmed that ECMO education implementing augmented reality with smart glasses is an effective method for improving performance ability, performance confidence, and educational satisfaction among clinical nurses.

본 연구의 목적은 60대의 대뇌에서 T1, T2, PD 이완 시간 값을 측정하여 연령별 특정 해부학적 구조물들의 이완 시간 의 평균값과 연령에 따른 이완 시간 변화의 관련성이 있는지 분석하고자 하였다. 60에서 69세까지 총 50명의 정상 뇌자기 공명영상검사자의 데이터를 Synthetic MR의 MAGiC을 이용하여 후향적으로 분석하였다. 대상 부위는 해마, 대뇌 부챗살, 측두엽 회백질, 시상, 뇌척수액이었다. 실험결과 해마, 대뇌 부챗살, 측두엽 회백질은 연령 변화에 따른 T1, T2, PD 이완 시간의 차이가 없었다(p>0.05). 하지만 시상에서는 PD 이완시간이 연령과의 상관성이 있었고(R2=0.112, p<0.05), 뇌척 수액에서는 T1 이완시간(R2=0.063, p<0.05)과 T2 이완시간(R2=0.061, p<0.05)에서 연령과의 상관성을 확인하였다. 추후 다양한 연령대의 대뇌 이완 시간을 측정하여 평균값의 비교 연구가 필요하고, 시상과 뇌척수액에서는 대규모 모집단 연구가 필요할 것이라 판단되며 이에 본 연구가 기초자료를 제공할 것이라 사료된다.

This paper considers the influence of internal heat exchanger and capillary tube on the efficiency of small refrigeration system using eco-friendly refrigerants such as R290, R600a, R1270, and R717. A refrigeration system using such internal heat exchanger and capillary tube may improve performance, but may degrade performance. Therefore, this paper used a mathematical model in a normal state to understand performance characteristics as to what change occurs when internal heat exchanger and capillary tube are attached to eco-friendly refrigerant based on R134a. In addition, the effects of operating conditions such as refrigerant flow rate, evaporation temperature, condensation temperature, subcooling degree internal heat exchanger length and capillary tube length were analyzed. The result showed that the evaporation temperature, condensation temperature, subcooling degree, internal heat exchanger length and capillary tube length had an effect on the refrigeration capacity and compression power. Therefore, it is necessary to design a refrigeration cycle using an eco-friendly refrigerant by grasping these effects in detail.

Scale and rust generation in water pipes is a common phenomenon when cast iron water pipes have been used for a long time. A physical water treatment device is known among various means for suppressing rust in a water pipe, and a zinc ionization device for putting zinc metal into a pipe and emitting the zinc cation into water is one of such devices. This research measured the amount of zinc ion generated, which is known to exhibit an effect of inhibiting rust and scale generation in a pipe, and examined the scale and rust inhibition effect of the ionization device installed for ground or building water supply. In the case of distilled water, the concentration of zinc ion increased by circulating water in the ionization device several times, and it was verified to be hundreds of μg/L, and in the case of discharging ground or tap water, it was verified to be tens of μg/L. In addition, a verification pipe was installed to confirm the change inside the pipe before and after installation of the zinc ionization device, and the internal condition of the pipe was observed 3 months to several years after installation. It was confirmed that the corrosion area of the surface of the pipe was no longer increased by installing a corrosion inhibitor, and if the pipe was already filled with corrosion products, the amount of corrosion products gradually decreased every year after installation. The phenomenon of fewer corrosion products could be interpreted as expanding the space in the pipe due to the corrosion product as Fe2O3 adhered to the inner surface of the pipe and turned into a smaller black Fe3O4. In addition, we found that scale such as CaCO3 together in the corrosion by-products gradually decreased with the attachment of the ionization device.

Automated Guided Vehicle (AGV) is commonly used in manufacturing plant, warehouse, distribution center, and terminal. AGV is self-driven vehicle used to transport material between workstations in the shop floor without the help of an operator, and AGV includes a material transfer system located on the top and driving system at the bottom to move the vehicle as desired. For navigation, AGV mostly uses lane paths, signal paths or signal beacons. Various predominant sensors are also used in the AGV. However, in the conventional AGV, there is a problem of not turning or damaging nearby objects or AGV in a narrow space. In this paper, a new driving system is proposed to move the vehicle in a narrow space. In the proposed driving system, two sets of the combined steering-drive unit are adopted to solve the above problem. A prototype of AGV with the new driving system is developed for the comparative analysis with the conventional AGV. In addition, the experimental result shows the improved performance of the new driving system in the maximum speed, braking distance and positioning precision tests.