• Proceedings of the Korea Technical Association of the Pulp and Paper Industry Conference
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• 2010.04a
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• pp.227-227
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• 2010

기존 도공지 생산 공정에서 널리 사용되던 블레이드 도공방식을 대체할 수 있을 것으로 기대되는 커튼코팅 방식은 스크래치, 스트릭, 미스팅, 블레이드의 마모등을 발생시키지 않고 고고형분 도공이 가능하며 우수한 커버리지를 갖는 도공층을 형성시킬 수 있다는 장점을 갖고 있다. 뿐만 아니라 하나의 코팅 유닛에서 여러개의 도공층을 한번에 형성시킬 수 있어 설비투자비용 및 건조에너지, 공간활용도 절감 측면에서도 한층 유리하다. 커튼 코팅 방식에서 도공액의 유동은 도공액이 필름 형태로 사출되는 sheet forming zone, 도공액 커튼이 낙하하는 curtain flow zone, 도공액 커튼이 원지와 접촉하는 impingement zone으로 나뉜다. 커튼 코팅이 이루어지기 위해서는 sheet forming zone과 curtain flow zone에서 도공액이 얇은 막 상태를 안정적으로 유지하고 impingement zone에서는 고속으로 이송되는 도공원지에 의한 급격한 신장 조건에서 도공액 필름이 끊어지지 않고 유지되어야 한다. 이를 위해 유화제를 통해 동적 표면 장력을 낮초고 rheology modifier를 통해 점도 및 신장점도를 조절해 도공액의 커튼 안정성을 부여하는 연구가 보고된 바 있다. 도공액 제조시 바인더로 널리 사용되는 S/B 라텍스는 입도, 유리전이온도, 표면전하 등 그 특성을 달리하여 제조할 수 있으며 이러한 특성에 따라 도공액의 점도와 같은 유변특성이 변화하여 도공액의 커튼 안정성에 영향할 것으로 예상된다. 따라서 본 연구에서는 입자경과 유리전이온도, 카르복실화 정도 등을 달리한 다양한 S/B 라텍스를 사용하여 유변특성을 달리한 도공액을 제조하고 커튼 안정성의 변화를 살펴보고자 하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.44 no.7
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• pp.552-561
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• 2016

In this experimental study, the dynamic stability derivatives of a tailless lambda-shape UAV are estimated from time history data of aerodynamic moments measured from the internal balance while the test model is forced to oscillate at given frequencies and amplitudes. A 3-axis forced oscillation apparatus is designed to induce decoupled roll, yaw, pitch oscillations respectively. The results show that the roll damping derivatives remain stable at the entire range of angle of attack tested, whereas the pitch damping derivatives become unstable beyond $15^{\circ}$ angle of attack. The amplitude and frequency have little impact on roll damping derivatives while the smaller amplitude and frequency of oscillation improves the pitch stability. The yaw damping derivative values are fairly small as expected for a tailless configuration. The results indicate that the proposed methodology and test apparatus area valid for estimating the dynamic stability derivatives of a tailless UAV.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2001.05a
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• pp.313-319
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• 2001

본 연구는 시뮬레이터 실험에서 필수적으로 발생하는 Simulator Sickness(SS)를 평가하기 위하여 동적 시뮬레이터에서 일정한 속도(60km/h)로 1시간 주행했을 때 Simulator Sickness Questionnaire(SSQ)를 이용하여 주관적 Sickness를 평가하고 생리적 반응으로 심박 변동량(HRV)과 피부온도 및 피부저항을 측정하여 성별, Simulator 수준에 따라 비교 분석하였다. 분석 결과 동적 시뮬레이터에서 주행시 주관적인 Simulator Sickness는 안정에 비해 시간이 지남에 따라 45분까지 선형적으로 증가하여UT고, 여자와 sick군이 남자와 nonsick군에 비해 더 높았으며 sickness 수준간에서는 유의성이 나타났지만 남녀간의 유의한 차이는 없었다. 생리적 반응은 시간에 따른 변화는 없었으나 안정에 비해 R-R 간격의 감소, (LF+MF)/total 및 (LF+MF)/HF의 증가로부터 교감 신경이 활성화되었으며 피부온도의 감소와 피부저항의 증가로부터 긴장도가 커짐을 알 수 있었다. 주행 50분 이후는 HF/total가 감소하여 부교감 신경의 작용이 저하되는 것으로 나타났다.. 성별, sickness수준에 따라서는 남녀간에는 부분적으로 유의한 차이가 있었고 평균 R-R 간격에서만 sick군이 nonsick군보다 유의하게 낮았다.

• Journal of the Korean Society for Railway
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• v.15 no.2
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• pp.147-153
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• 2012

Precise estimation f a structure's dynamic characteristics is indispensable for ensuring stable dynamic response during life time especially for the structures which can experience resonance such as railway bridges. Especially, concrete track can change the modal properties of the railway bridge, through the contribution of stiffness as well as mass effects, generally only the mass effect is considered in dynamic analysis of the railway bridge. In this paper, static and dynamic behaviors of railway bridge with concrete track were investigated through experimental study. Also, numerical analysis was performed about considering only mass of concrete track and together with stiffness and mass of concrete track. These were compared with experiment value. Numerical analysis value considering together with stiffness and mass of concrete track was similar experiment value. Therefore, when dynamic analysis of railway bridge with concrete track is performed, the contribution of stiffness as well as mass effects for concrete track is considered.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.3
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• pp.310-316
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• 2016

We propose a novel contact-free transportation system in which an axial electrodynamic wheel is applied as an actuator. When the electrodynamic wheel is partially overlapped by a fixed conductive plate and rotates over it, three-axis magnetic forces are generated on the wheel. Among these forces, those in the gravitational direction and the lateral direction are inherently stable. Therefore, only the force in the longitudinal direction needs to be controlled to guarantee spatial stability of the wheel. The electrodynamic wheel consists of permanent magnets that are repeated and polarized periodically along the circumferential direction. The basic geometric configuration and the pole number of the wheel influence the stability margin of a transportation system, which would include several wheels. The overlap region between the wheel and the conductive plate is a dominant factor affecting the stiffness in the lateral direction. Therefore, sensitivity analysis for the major parameters of the wheel mechanism was performed using a finite element tool. The system was manufactured based on the obtained design values, and the passive stability of a moving object with the wheels was verified experimentally.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.5
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• pp.53-60
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• 2020

In this study, smart precast-in-place concrete, such as continuity with Precast any technology that can be the Application of Building Structures and railway stations, civil structures. After the same way in the field installation design based on the criteria railways and derived the right section, through the Static and Dynamic Response Analysis. Dynamic sensor and the triaxial acceleration measured by attaching the sensor acceleration response according to the extent of the damage of Precast Panel Structures and mode of Precast Structures, by comparing the data. Data for the stability and improvement of the uncertainty in along a railroad and Future of Precast Panel Structures of time to replace. This is to use this data as basic data on damage prediction.

• Proceedings of the KIEE Conference
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• 2008.04c
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• pp.13-15
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• 2008

본 논문은 대형(MW 급) LNG 전기추진선박 시스템의 동적 정적 특성에 대해 다룬다. 특히, 선박 항해시와 LNG Unloading시에 대해 전력조류해석(정특성 해석)으로 시스템 모델링의 타당성을 검증하였다. 아울러, LNG Unloading에 대한 Cargo Pump 기동시 시스템의 전압변동률 및 발전기의 주파수(속도)변화를 관찰하였으며, PID제어기로 구성된 발전기 Governor의 파라미터를 설계하기 위해 실제 항해시 발생할 수 있는 몇 가지 상황(발전기 및 추진전동기 Trip)의 과도안정도해석을 수행하였다. 따라서 전동기 기동해석 및 과도안정도해석(동특성 해석)으로 발전기 및 추진전동기의 전압안정성을 관찰하였다.

• Journal of the Korean Society for Railway
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• v.10 no.6
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• pp.701-708
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• 2007

A tilting train, which was developed to run the curve section without reducing the speed and compromising the riding quality, can improve the speed so as to reduce the travel time, compared to the existing trains. Then the force generated by the train operation to the track is in proportion to train operation speed, which means the track shall bear the increased force as much as the increase in train operation speed. Particularly, wheel load and lateral wheel load generated by train operation and distributed to the rail tend to cause the track to suffer the strain and furthermore the severe disaster such as derailment. To deal with such problem and ensure the train will run safety and stably, the tolerance in wheel load change, lateral wheel load and derailment coefficient was determined for quantitative evaluation of the train operation stability. In this study, derailment coefficient of inner and outer rail at existing curve section of tilting train was determined to evaluate the curve radius, possibility of acceleration and the need of rail improvement, which was then compared with the existing traditional train and high speed train. Conducting the quantitative evaluation of dynamic wheel load and lateral wheel load of each train, which was based on field survey, derailment coefficient and static & dynamic wheel load change, which serve the evaluation criteria of train operation stability, were determined for comparison with the standards, thereby analyzing the stability of the tilting train.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.75-81
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• 2006

In this study, the dynamic response of the umbilical cable in a deep-water unmanned underwater vehicle system was analyzed. In order to analyze the forces acting on the cable, the launcher and umbilical cable were modeled by the simple 1-D mass-spring system. Damping and dynamic analysis was carried out by a direct time integration scheme using the $Newmark-{\beta}$ method with inverse iteration procedure, considering the nonlinear drag forces acting on the launcher. The obtained results of the present study can be used for the design of connecting the structure of the launcher and cable of the UUV system.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.4
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• pp.463-468
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• 2007

Some network equipments made in Korea were exposed to severe earthquake in Japan several years ago. More than a hundred slim base transfer network stations had been seized with the severe earthquake at Nigata and it was reported that less than fifteen sets showed blackout by interruption of electricity, not by the structural failure. The purpose of this paper is to check the structural safety of the network equipments by performing table test, and the static and dynamic finite element analysis. For the dynamic test, the station weighing 200 kg was subjected to the Zone 3 earthquake loading of GR-63-CORE on the shaking table to obtain the dynamic responses to compare with the analysis results. It is shown that the FE analysis results are a little bit larger than that of the experimental values. And the sensitivity analysis and optimization for the natural frequency is performed and it is found that the first natural frequency is sensitive to small design change as shown in the results. And the dynamic response of optimized design is less than the original design.