• Journal of the Institute of Convergence Signal Processing
• /
• v.21 no.1
• /
• pp.21-28
• /
• 2020

In this paper, a new type of electric wheelbarrow is proposed and developed. The developed electric wheelbarrow is equipped with an attitude reference system(ARS) sensor, which consists of 3-axis acceleration sensor and 2-axis Gyro sensor so that it can estimate pitch angle and roll angle. When an operator tilts the wheelbarrow up and down, the pitch angle is detected. The sign of the pitch angle is interpreted as the operator's intention for moving the wheelbarrow forward or backward and the controller drives the wheel of the wheelbarrow with the velocity according to the magnitude of the detected pitch angle. A cargo box of the wheelbarrow is designed to rotate and is controlled to maintain level always, so an operator can handle the electric wheelbarrow easily and safely. The wheelbarrow consists of an in-wheel motor, a DC motor, motor drives, an ARS sensor considering economical use in industrial field. Three experiments are performed to verify the feasibility and stability of the electric wheelbarrow.

• Journal of the Korea Society of Computer and Information
• /
• v.14 no.11
• /
• pp.221-232
• /
• 2009

To purpose of the study was to analyze faculty utility of Web-Based course support system in Universities. Data were collected from log file in server computer, 5,023 faculties and 12,733 courses offered at spring semester of 2009 in the Metropolitan area S, K, D universities were analyzed. Specifically, frequency and percentile of faculties and courses using course management system were analyzed. In addition, the frequencies and percentiles of courses using sub-functions of course management system were analyzed and X2 test used to examine the difference of frequencies of faculties and courses using course system at using announcement, providing instructional material, public bulletin board and free board. Results were as follows. The 62.28% of faculties and 50.3% of courses have used Web-Based course support system. The results of Subfunction utility analysis showed the highest use as 80.4%. in providing instructional material. However, the use of announcement functions and online discussion was more or less low. Results imply that most of faculties and course are using course management system as supplementary system of off-line instruction.

• Journal of Advanced Marine Engineering and Technology
• /
• v.36 no.5
• /
• pp.635-644
• /
• 2012

In order to design a wave energy generating system, a 6-DOF analysis technique is applied to the three-Dimensional CFD analysis on of a floating body and the behavior is interpreted according to the nature of the incoming wave. A wave period of 5.5s & amplitude of 0.57m from Marado is chosen. 12 case of natural pitching period from 1.25 to 2.8s has been modeled. The relation between tuning factor & pitch angle for the waves generated is compared to analyze the effects of energy absorption variables, namely mass moment of inertia, angular velocity and angular acceleration. From the results obtained, we conclude that model L is the maximum power absorbed, 6kW approximately. A maximum pitch angle of 1.91 degree was attained by Model F, and the maximum displacement of nearly 0.7m was attained by Model L among models D, F and L.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.21 no.2
• /
• pp.7-14
• /
• 2021

By changing the bulky monolithic services architecture to a microservices-based architecture, industries are managing the rising complexity of Autonomous Vehicles. However, the underlying communication mechanisms for the utilization and distribution of these microservices are incapable of fulfilling the requirements of the futuristic AV, because of the stringent latency requirements along with intermittent and short-lived connectivity issues. This paper proposes to tackle these challenges by employing the revolutionary information-centric networking (ICN) paradigm as an underlying communication architecture. This paper argues that a microservice approach to building autonomous vehicle systems should utilize ICN to achieve effective service utilization, efficient distribution, and uniform service discovery. This research claims that the vision of an information-centric microservices will help to focus on research that can fill in current communication gaps preventing more effective, and lightweight autonomous vehicle services and communication protocols.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.18 no.11
• /
• pp.1217-1223
• /
• 2007

Advanced microwave absorbers for wide oblique incidence angles are required in many applications including wireless communication or vehicle identification in ITS(Intelligent Transport System) where 5.8 GHz DSRC(Dedicated Short Range Communication) system is applied. In this study, two-layered microwave absorber(with a laminate structure of dielectric/magnetic composites) has been designed for the achievement of low reflection coefficient over wide incidence angles at 5.8 GHz. Iron flake particles are used as the filler in the absorbing layer, and the magnetic composite sheet exhibits high magnetic loss due to ferromagnetic resonance in gigahertz frequencies. The surface layer of low dielectric constant containing small amount of carbon black is used as the impedance transformer. On the basis of transmission line theory, the reflection loss has been calculated for the two-layer structure with variation of incident angles for both TE(Transverse Electric) and TM(Transverse Magnetic) polarizations. At the optimum thickness of the composite layers, a low value of reflection loss(less than -10 dB) has been predicted for wide incidence angles up to $55^{\circ}$ which is in good agreement with the measured value determined by free-space measurement.

• 한국HCI학회:학술대회논문집
• /
• 2007.02a
• /
• pp.373-378
• /
• 2007

최근 들어 햅틱 분야는 디지털 콘텐츠를 만질 수 있게 촉감을 제공함으로써 의학, 교육, 군사, 엔터테인먼트, 방송 분야 등에서 널리 연구되고 있다. 그러나 햅틱 분야가 사용자에게 시청각 정보와 더불어 추가적인 촉감을 제공함으로써 보다 실감 있고 자연스러운 상호작용을 제공하는 등 여러 가지 장점을 가진 것에 비해 아직은 일반 사용자들에게 생소한 분야다. 그 이유 중 하나로 촉감 상호작용이 가능한 콘텐츠의 부재를 들 수 있다. 또한 최근에 가상환경(Virtual Environment, VR)에 관심이 증가 되고, 가상환경에 햅틱이라는 기술을 접목시키는 시도가 많이 일어나고 있어서, 촉감 모델링에 대한 욕구 또한 증대 되고 있다. 일반적으로 촉감 모델링은 Material properties를 가지고 있는 그래픽 모델들로 구성이 된다. 그래픽 모델링은 일반적인 모델링툴 (MAYA, 3D MAX, 기타 등)으로 할 수 있다. 하지만 촉감 관련된 촉감 모델들은 콘텐츠를 제작한 이후에 일일이 수작업으로 넣어 주어야 한다. 그래픽 모델링에서는 사용자가 직접 눈으로 확인 하면서 작업을 이루어 지기 때문에 직관적으로 이루어질 수 있다. 이와 비슷하게 촉감 모델링은 직관적인 모델링을 하기 위해서 사용자가 직접 촉감을 느껴 보면서 진행이 되어야 한다. 또한 그래픽 모델링과 촉감 모델링이 동시에 진행이 되지 않기 때문에 촉감 콘텐츠를 만드는데 시간이 많이 걸리게 되고 직관적이지 못하는 단점이 있다. 더 나아가서 이런 촉감 모델링을 포함한 모델링 높은 생산성을 위해서 신속히 이루어져야 한다. 이런 이유들 때문에 촉감 모델링을 위한 새로운 인터페이스가 필요하다. 본 논문에서는 촉감 상호작용이 가능한 촉감 콘텐츠를 직관적으로 생성하고 조작할 수 있게 하는 촉감 모델러를 기술한다. 촉감 모델러에서 사용자는 3 자유도 촉감 장치를 사용하여 3 차원의 콘텐츠 (정적 이거나 동적이거나 Deformation이 가능한 2D, 2.5D, 3D Scene)를 실시간으로 만져보면서 생성, 조작할 수 있는 촉감 사용자 인터페이스 (Haptic User Interface, HUI)를 통해서 콘텐츠의 표면 촉감 특성을 직관적으로 편집할 수 있다. 촉감 사용자인터페이스는 마우스로 조작하는 기존의 2 차원 그래픽 사용자 인터페이스를 포함하여 3 차원으로 사용자 인터페이스도 추가되어 있고 그 형태는 촉감 장치로 조작할 수 있는 버튼, 라디오버튼, 슬라이더, 조이스틱의 구성요소로 이루어져있다. 사용자는 각각의 구성요소를 조작하여 콘텐츠의 표면 촉감 특성 값을 바꾸고 촉감 사용자 인터페이스의 한 부분을 만져 그 촉감을 실시간으로 느껴봄으로써 직관적으로 특성 값을 정할 수 있다. 또한, XML 기반의 파일포맷을 제공함으로써 생성된 콘텐츠를 저장할 수 있고 저장된 콘텐츠를 불러오거나 다른 콘텐츠에 추가할 수 있다. 이러한 시스템은 햅틱이라는 분야를 잘 모르는 사람들도 직관적으로 촉감 모델링을 하는데 큰 도움을 줄 수 있을 것이다.

• Korean Journal of Optics and Photonics
• /
• v.11 no.6
• /
• pp.385-389
• /
• 2000

A phase-retardation function which was derived from Wigner distribution function (WDF) is used to increase a focal depth of a radially symmetric optical system. The WDF for one-dimensional signal is represented as a two-dimensional function of phasespace ($\chi,\zeta$), and a normalized irradiance is described as a form of the Strehl ratio (SR). The increase in the focal depth is accomplished by delivering a shearing tilt a that represents a characteristic of free space propagation with simple manipulation in the WDF space. In this paper we propose a method for evaluating the focal depth quantitatively by representing the phaseretardation function in terms of the focal depth term. In order to verify the validity of the proposed method, we compared the numerically analyzed result with that of J. Sochki's study. study.

• Aerospace Engineering and Technology
• /
• v.9 no.2
• /
• pp.168-175
• /
• 2010

During feeding oxidizer to the engine, vortices are occurred at lower dome of oxidizer tank inside by various working environments and external forces for liquid propellant feeding system of space launch vehicle. To eliminate the vortices or swirls Anti-Vortex Devices(AVD) shall be installed at inside lower oxidizer tank. Using the numerical analysis, we have confirmed the performance of AVD and analyzed the mass flow rate by feeding time and magnitudes of swirls on the free surface of oxidizer or exit surface according to the AVD number and length. Then we could derive the optimal design of the AVD number and length.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.15 no.3 s.96
• /
• pp.259-265
• /
• 2005

A two-degree-of-freedom out-of-plane model with contact stiffness is presented to describe dynamical interaction between the pad and disc of a disc brake system. It is assumed that the out-of-plane motion of the system depends on the friction force acting along the in-plane direction. Dynamic friction coefficient is modelled as a function of both in-plane relative velocity and out-of-plane normal force. When the friction coefficient depends only on the relative velocity, the contact stiffness has the role of negative stiffness. The results of stability analysis show that the stiffness of both pad and disc is equally important. Complex eigen value analysis is conducted for the case that the friction coefficient is also dependent on the normal force. The results further verify the importance of the stiffness. It has also been found that increasing the gradient of friction coefficient with respect to the normal force makes the system more unstable.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.19 no.9
• /
• pp.1692-1701
• /
• 1994

Macromodeling technology is useful to simulate and analyze the performance of new elements and complicated circuits or systems without any changes in today's general simulator, PSPICE. In this paper, Phase Locked Loop(PLL) is designed using macromodeling technique. The PLL macromodel has two basic sub-macromodels of the phase detector and the voltage controlled oscillator(VCO). The PLL macromodel has two open terminals for inserting RC low pass filter. The PLL macromodel is simulated using simulation parameters of LM565CN manufactured in the National company. At a free-running frequency, 2500Hz, upper lock range and lower capture range was 437Hz, 563Hz, respectively. Also, experimental results and simulation results of LM565CN PLL show good agreement.