• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권6호
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• pp.286-290
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• 2003

The high temperature superconducting bulk can be used as the bearing of induction motors. This paper presents the fabrication and test results of an induction motor with superconducting bearings using HTS bulks. The bearing had eight hexahedron type YBCO bulks. Height, width and thickness of the HTS bulk were 30mm, 30mm and 10mm, respectively. Single phase induction motor was used to drive the shaft made of aluminum and the rotor of a conventional induction motor. To estimate the performance of the HTS bulk magnetic bearing, no load test, load test and Impact test were carried out. Load tests were performed by using air resistance caused by the shaft-mounted thin cylinder with buckets. Impact tests by axial direction and vertical direction impact showed that the vibration of the shaft gradually decayed. The induction motor with HTS bulk magnetic bearing rotated silently and smoothly throughout the tests. According to the test results, conventional bearings can be replaced with superconducting magnetic bearings made of HTS bulks.

• 한국재료학회지
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• 제33권6호
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• pp.251-256
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• 2023

This study aims to examine the correlation between microstructures and the mechanical properties of two high-strength API X70 linepipe steels with different specimen directions and Moaddition. The microstructure of the Mo-added steel has an irregularly shaped AF, GB matrix with pearlite because of the relatively large deformation in the non-recrystallization temperature region, while that of the Mo-free steel shows a PF matrix with bainitic microstructure. In the Mo-added steel, the M/A (martensite-austenite) in granular bainite (GB) and pearlite act as crack initiation sites with decreased upper shelf energy and an increased ductile to brittle transition temperature (DBTT). Regardless of Mo addition, all of the steels demonstrate higher strength and lower elongation in the T direction than in the L direction because of the short dislocation glide path and ease of pile-up at grain boundaries. In addition, the impact test specimens with T-L direction had a lower impact absorbed energy and higher DBTT than those with the L-T direction because the former exhibit shorter unit crack path compared to the latter.

• 환경영향평가
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• 제20권2호
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• pp.175-185
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• 2011

It is usual for energy consumption in accordance with facing and sitting direction of tower-type apartments to be calculated by the official statistics or computer simulation. Previous studies for energy consumption appear to be very limited due to the dependence on flat type of apartment. Acknowledging these constraints, an empirical study for a tower type apartment was conducted to demonstrate how a on-site indoor temperature measurement in spring can be used to assist in estimating the total energy consumption in terms of facing and sitting orientation specific settings. The results indicate that maximum temperature difference in spring was identified as $1.16^{\circ}C$ between south and eastern direction. It is known that raising $1^{\circ}C$ indoor temperature require 7% more energy consumption than normal. The $1.16^{\circ}C$ difference means that sitting direction of tower type apartment is a crucial explanatory variable as unit of analysis for energy consumption. It was demonstrated that the indoor temperature could be used effectively as an indicator to estimate energy consumption among various sitting direction of tower type apartments. It is anticipated that this research output could be used as a valuable reference to support more scientific and objective decision-making for facing and sitting orientation of tower type apartments.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 춘계학술대회 논문집
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• pp.83-84
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• 2010

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.269-274
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• 2004

The aims of this study were to Investigate the floor impact noise isolation performance of floating floor with isolation materials and propose the improvement direction of floor impact noise measurement method and evaluation classes using impact ball. Reduction of light-weight impact sound pressure level can be achieved by the finishing materials, such as vinyl finishing material and wooden flooring with isolation materials. Floor impact noise Isolation material which satisfy the properties of the floor impact noise isolation materials cause resonance in the low frequency band and worsen heavy-weight impact sound pressure level. Heavy-weight impact sound level can be reduced by using noise reduction flooring, ceiling and increase of slab thickness. Strong impact force in low frequency bang below 63Hz of bang machine is not similar to human impact source and causes some problem in evaluating heavy-weight impact noise but heavy-weight impact noise measurement and evolution using impact ball which is very similar to human impact is more reliable than bang machine. Correction value on the background noise and sensitivity of residents should be considered on the floor impact noise evaluation classes.

• 오토저널
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• 제15권3호
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• pp.111-119
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• 1993

In this study, the transient impact structural stress analysis of tracked vehicle structures under recoil impact load is investigated. ANSYS, ABAQUS Code are used for modelling and analytical procedures. The highest maximum Tresca stress occurs on race ring portion and its stress level is (.sigma.$_{T}$)$_{max}$ =20-40kgf/m $m^{2}$. The second highest stress occurs on upper plate of chassis and down plate of turret. The maximum stress level increases with loading direction and elevation angle. The results from liner static load analysis are very much different with impact analysis. Therefore, the practical solutions of structures under impact load can be obtained by only nonlinear transient impact analysis. The impact stress analysis of the steel vehicle structures is conducted. The maximum stress level is less than (.sigma.$_T/)$_{max}$m $m^{2}$. So, the design concept of steel structures can be adapted for new alternatives.s.s.s..s.

• Earthquakes and Structures
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• 제23권1호
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• pp.87-100
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• 2022

Limiting the displacement of seismic isolators causes a pounding phenomenon under severe earthquakes. Therefore, the ASCE 7-16 has provided minimum criteria for the design of the isolated building. In this research the seismic response of isolated buildings by Triple Friction Pendulum Isolator (TFPI) under the impact, expected, and unexpected mass eccentricity was evaluated. Also, the effect of different design parameters on the seismic behavior of structural and nonstructural elements was found. For this, a special steel moment frame structure with a surrounding moat wall was designed according to the criteria, by considering different response modification coefficients (RI), and 20% mass eccentricity in one direction. Then, different values of these parameters and the damping of the base isolation were evaluated. The results show that the structural elements have acceptable behavior after impact, but the nonstructural components are placed in a moderate damage range after impact and the used improved methods could not ameliorate the level of damage. The reduction in the RI and the enhancement of the isolator's damping are beneficial up to a certain point for improving the seismic response after impact. The moat wall reduces torque and maximum absolute acceleration (MAA) due to unexpected enhancement of mass eccentricity. However, drifts of some stories increase. Also, the difference between the response of story drift by expected and unexpected mass eccentricity is less. This indicates that the minimum requirement displacement according to ASCE 7-16 criteria lead to acceptable results under the unexpected enhancement of mass eccentricity.

• 대한기계학회논문집A
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• 제26권7호
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• pp.1438-1445
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• 2002

For robotic endoscope, some researchers suggest pneumatic actuators based on inchworm motion. But, the existing endoscopes have not been replaced completely because human intestine is very sensitive and susceptible to damage. We design and test a new locomotion of robotic endoscope that allows safe maneuverability in the human intestine. The actuating mechanism is composed of two solenoids at each side and a single permanent magnet. When the current direction is reversed, repulsive force and attractive at the opposition side propels permanent magnet. Impact force against robotic endoscope transfers momentum from moving magnet to endoscope capsule. The direction and moving speed of the actuator can be controlled by adjustment of impact force. Modeling and simulation experiments are carried out to predict the performance of the actuator. Simulations show that force profile of permanent magnet is the dominant factor for the characteristic of the actuator. The results of simulations are verified by comparing with the experimental results.

• 풍력에너지저널
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• 제14권3호
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• pp.69-82
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• 2023

Offshore wind farms (OWFs) should be promoted as part of global efforts to respond to climate change, and efforts to preserve biodiversity in terms of climate change adaptation should also be considered. However, the ecological status of marine birds related to OWFs on the Korean Peninsula, such as habitat and reproduction, are not well known. In this study, ecological reasons for the reproductive status of Black-tailed gulls in Korea and representation related to OWFs, the evaluation direction of marine birds related to OWFs was presented. In a review of the techniques for monitoring marine birds, it was confirmed that Korea also needs to provide basic status information on marine birds at the national level. In addition, this study analyzed the reproductive status and related research status of Black-tailed gulls, an important indicator and dominant species on the Korean Peninsula, in relation to marine development projects including OWFs. Furthermore, the direction of environmental impact assessment preparation and impact prediction for various development projects promoted in the ocean, such as OWFs, was considered.

• 한국자동차공학회논문집
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• 제18권1호
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• pp.51-57
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• 2010

In recent years, a large number of study for rear impact has been conducted and as a result of study, researchers proposed the neck injury criteria and test procedures. But many questions, related to injury criteria and dummy biomechanical levels, remain unresolved. In recently reports, rear impact motions of BioRIDIIg is not humanlike but better than other dummy(HybridIII, RID3d). So, in this paper, 4 times sled test would be done to find the substitutable neck injury criteria in BioRIDIIg. To review corelation trend with neck injury critera and head-neck movement, we compared with recently announced neck injury criteria(NIC, Nkm, T1 ect.) and head-neck X-direction movement in BioRIDIIg. Finally, we find the head-neck X-direction movement on head C.G to T1 point may be considerable as the additional neck injury criteria.