• Journal of Fashion Business
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• v.21 no.4
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• pp.144-158
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• 2017

Fur garment has long been the conventional symbol for luxury, or conspicuous consumption. However, as fashion items began to diversify as part of overall fashion trend, fur items are now more about individual taste and style than just lavishness. Synthetic fur is especially emerging as a new promising fashion material, with a touch almost like natural fur at an affordable price. Along with the emergence of 'Vegan Fashion' trend, synthetic fur is establishing itself as a popular fashion textile. This study is an attempt to investigate subjective evaluation and physical properties of natural and synthetic furs, whose results will further serve as basic data in developing synthetic fur materials. Sensory and emotional evaluations are carried out on natural and artificial furs. For analysis, factors such as weight, thickness, air permeability, gloss and compressibility were surveyed to observe how they influence the physical properties. According to the subjective evaluation, natural and artificial fur samples do not differ in conspicuous ways in appearance. Experiments on physical properties, specifically warm/cool touch experiment, show that natural fur has a slightly higher warm sensation than artificial fur. Luster analysis by using a microscope revealed that there are subtle qualitative differences between natural and artificial fur. During the subjective evaluation, subjects found it hard to state distinct quantitative differences in luster. A survey as a means of assessing qualitative differences in gloss seems to be necessary to complement the evaluation. Results from this study will potentially serve as resources for diversification of fashion product designs using synthetic fur.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.6
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• pp.56-63
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• 2004

In this study, dynamic aeroelastic analyses of the canard with oscillating flap are conducted considering the effect of aerodynamic compressibility. The canard model considered herein is an all-movable type with a pitching axis on a canard-rotor-wing aircraft which was considered as one of the major UAV candidates under developing in Korea. The equivalent structural model is constructed based on the initial design data by the Korea smart UAV development center. Both the frequency and the time-domain aeroelastic analyses have been applied to practically conduct parametric studies on the effects of equivalent torsional stiffness. In the case of all-movable control surface with oscillating flap, the equivalent rotational stiffness of the pitch axes are important design parameters. The parametric results for the aeroelastic instability are practically presented.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.11
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• pp.6446-6451
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• 2014

Pneumatic motors are quite attractive for many applications because of their competitive price, light-weight, easy assembly, safety in hazardous areas as well as other features, such as a good force/weight ratio and operation in exceptionally harsh environments. In contrast to these advantages, pneumatic motors have limited use in applications, particularly those requiring a fast and precise response. These undesirable characteristics are due to the high compressibility of air and from the nonlinearities in pneumatic systems. This paper presents the sliding mode controller based on 3-loop(SMCB3L), which increases the load stiffness to control the rotation angle of a pneumatic motor. The characteristics for the step responses and load disturbances of the proposed controller were compared with the conventional PID controller. The experimental results showed that a properly designed SMCB3L is capable of high positioning accuracy within ${\pm}0.05mm$. Furthermore, the load stiffness of the SMCB3L can be improved 3.5 fold compared to that of PID controllers.

• Journal of the Korean Society of Propulsion Engineers
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• v.3 no.4
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• pp.58-66
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• 1999

The flow characteristics of supersonic ejectors is often subject to compressibility, unsteadiness and shock wave systems. The numerical works carried out thus far have been of one-dimensional analyses or some Computational Fluid Dynamics(CFD) which has been applied to only a very simplified configuration. For the design of effective ejector-pump systems the effects of secondary mass flow on the supersonic ejector flow should be fully understood. In the present work the supersonic ejector-pump flows with a secondary mass flow were simulated using CFD. A fully implicit finite volume scheme was applied to axisymmetric compressible Navier-Stokes equations. The standard two-equation turbulence model was employed to predict turbulent stresses. The results obtained showed that the flow characteristics of constant area mixing tube types were nearly independent of the secondary flow rate, but the flow fields of ejector system with the second-throat were strongly dependent on the secondary flow rate due to the effect of the back pressure near the primary nozzle exit.

• Journal of Advanced Navigation Technology
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• v.13 no.1
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• pp.11-18
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• 2009

As a marine leisure industry has being developed and demands for leisure culture have rapidly increased, the needs for services offering marine safety and related information are growing. Accordingly, in the study I developed the contents providing server to support this with ENC agent who presents geographical information of digitalized Electronic Nautical Chart satisfying with the standard(S-57) by International Hydrographic Organization and a web searching agent who builds a database by collecting marine-related information in order to provide a variety of realtime information such as weather, fishing and news. In addition, I designed and embodied network based mobile contents which can be presented on a WIPI(Wireless Internet Platform for Interoperability) based portable handset by receiving an ENC and other processed information from server. With the results produced by such experiments, I measured a compressibility corresponding to a image compression format of electronic nautical chart transmitted and analyzed the correlation between increase in packets of requested information and the cost.

• Korean Journal of Soil Science and Fertilizer
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• v.42 no.4
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• pp.239-248
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• 2009

In this investigation, we observed surface morphology and porosity of a macroporous adsorbent made of Na-bentonite and Ca-bentonite as structure formation materials and grounded waste paper as macropore forming material for the development of a permeable reactive barrier to remove heavy metals in groundwater. Therefore, we selected minerals having higher cation exchange capacity among 2:1 clay minerals and other industrial minerals because sintering can significantly influence cation exchange capacity, resulting in drastic decrease in removal of heavy metals. The results showed that the increasing sintering temperature drastically decreased CEC by less than 10 % of the indigenous CEC carried by the selected minerals. One axial compressibility test results showed that the highest value was obtained from 5% newspaper waste pulp for both structure formation materials of Na-bentonite and Ca-bentonite although there were not much difference in bulk density among treatments. The pore formation influenced by sintering temperature and period contributes removal of heavy metals passing through the sintered macroporous media having different water retention capacity.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.75-75
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• 2011

본 논문에서는 진동중인 교량 거더에 작용하는 풍하중을 산정하고 그에 따른 플러터 발생풍속을 예측하기 위하여 분산형 전산환경을 활용한 수치해석 연구를 수행하였다. 분산형 전산환경은 웹 포탈을 기반으로 수치해석 환경을 제공하는 수치풍동 시스템으로서, 전산유체역학(CFD : Computational Fluid Dynamics)에 대한 전문지식이 부족한 사용자들도 격자생성, 수치해석자를 이용한 계산, 가시화 등의 전 과정을 편리하게 수행할 수 있는 차세대 토목분야 연구 환경이다. 본 시스템은 그리드스피어(GfidSphere)를 기반으로 구성되었으며, 기본적으로 사용자 관리, 세션 관리, 그룹 관리, 레이아웃 관리 등을 제공하여 사용자가 포탈을 통해서 다양한 서비스를 쉽게 사용할 수 있는 환경을 구축하도록 도와준다. 수치해석을 위한 유체 지배방정식은 2차원 비정상 비압축성 RANS(Reynolds-Averaged Navier-Stokes) 방정식이며, pseudo compressibility 방법을 적용하였다. 비정상 유동장을 해석하기 위하여 이중시간 전진법(dual time stepping)을 사용하였으며, 수렴가속화를 위해 Multi-grid 기법을 적용하였다. 또한 난류 유동장 해석을 위해서 $k-{\omega}$ SST 난류 모델을 사용하였으며, 난류 천이 과정에서의 유동을 모사하기 위하여 Total stress limitation 방법을 적용하였다. 교량 거더의 연직과 회전방향의 2자유도 움직임을 모사하기 위하여 동적격자 기법을 도입하였다. 교량 거더 주변의 비정상 유동해석 결과를 통해, 거더 표면에서 떨어져나가는 크고 작은 와류의 영향으로 양력 및 모멘트 계수 그래프가 중첩된 진폭과 주기를 갖고 주기적으로 나타나는 것을 확인할 수 있었다. 또한 계산된 비정상 공기력을 적용한 2자유도 플러터 방정식을 통하여 플러터 발생풍속을 산정하였다. 최종적으로 본 연구에서 계산된 결과의 타당성을 검증하기 위하여 수치적으로 구한 플러터 발생풍속과 기존의 실험 및 수치해석 결과를 비교하였으며, 결과는 잘 일치하였다.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1983-1989
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• 2005

Industrial robots are powerful, extremely accurate multi-jointed systems, but they are heavy and highly rigid because of their mechanical structure and motorization. Therefore, sharing the robot working space with its environment is problematic. A novel pneumatic artificial muscle actuator (PAM actuator) has been regarded during the recent decades as an interesting alternative to hydraulic and electric actuators. Its main advantages are high strength and high power/weight ratio, low cost, compactness, ease of maintenance, cleanliness, readily available and cheap power source, inherent safety and mobility assistance to humans performing tasks. The PAM is undoubtedly the most promising artificial muscle for the actuation of new types of industrial robots such as Rubber Actuator and PAM manipulators. However, some limitations still exist, such as the air compressibility and the lack of damping ability of the actuator bring the dynamic delay of the pressure response and cause the oscillatory motion. In addition, the nonlinearities in the PAM manipulator still limit the controllability. Therefore, it is not easy to realize motion with high accuracy and high speed and with respect to various external inertia loads in order to realize a human-friendly therapy robot To overcome these problems a novel controller, which harmonizes a phase plane switching control method with conventional PID controller and the adaptabilities of neural network, is newly proposed. In order to realize satisfactory control performance a variable damper - Magneto-Rheological Brake (MRB) is equipped to the joint of the manipulator. Superb mixture of conventional PID controller and a phase plane switching control using neural network brings us a novel controller. This proposed controller is appropriate for a kind of plants with nonlinearity uncertainties and disturbances. The experiments were carried out in practical PAM manipulator and the effectiveness of the proposed control algorithm was demonstrated through experiments, which had proved that the stability of the manipulator can be improved greatly in a high gain control by using MRB with phase plane switching control using neural network and without regard for the changes of external inertia loads.

• Geotechnical Engineering
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• v.12 no.4
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• pp.131-144
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• 1996

In order to accelerate the rate of consolidation settlement and to gain a required shear strength for a given soft clay deposit, the preloadina technique combined with a vertical drainage system has been widely applied. Even if a sophisticated numerical analysis technique is applied to solve the consolidation behavior of drainage-installed soft deposits, the actual field behavior is often different from the behavior predicted in the design state due to several uncertainties involved in soil properties, numerical modelling, and measuring system. In this paper, two back-analysis schemes such hs simplex and BFGS methods have been implemented in an a Bisymmetric consolidation program, AXICON which considers the variation of compressibility and permeability during the consolidation process. Utilizing the program, one might be able to appropriately predict the subsequent consolidation behavior from the measured data in an early stage of consolidation of drainage-installed soft deposits.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.613-618
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• 2008

Because the flat dilatometer (DMT) is operated in appropriate strain level, it has been known as an adoptable in-situ tool to evaluate the compressibility of soils compare with other in-situ test tools, such as SPT and CPT. This study is concerned about prediction method of constrained modulus by DMT, and a series of DMT and consolidation tests are performed at Busan new-port, Yangsan and Noksan test sites. By comparing DMT results with lab tests, the suitability of constrained modulus correlation, which is suggested by Marchetti, is investigated in Busan clay and new correlation is suggested. In lab test result, the compression indices ($C_c$) of Busan clay are turned out to be 0.4~0.12, and the constrained moduli are found out 0.5MPa~3MPa and these are increase with depth. The predicted constrained moduli using Marchetti's correlation are turned out 0.5MPa~4MPa, and these are bigger than measured constrained moduli by lab tests. By analyzing lab test and DMT results, it is shown that the correlation coefficient ($R_M=M/E_D$) has a linear relationship with (1/$I_D$) in Busan.