• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.360-367
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• 2003

Diamond-like carbon(DLC) films are considerable research interest because of their widespread applications as protective coatings in areas such as optical windows, magnetic storage disks, car parts, biomedical coatings and as micro-electromechanical devices(MEMs). DLC films were deposited on WC-Co by PECVD using Ar, $C_2H_4$ gas. Tribological tests were conducted using a ball-on-disk type tribometer in dry air. Three kinds of counter-bodies balls were used. The counter-bodies balls are SM45C, SUJ2 and $ZrO_2$(3.17mm in diameter). Wear rate of the samples were calculated after measuring the worn-out volume of the wear track. As results wear test, the higher hardness of counter-bodies, friction coefficient low. As result of XPS estimation, wear debris generated as an oxide lower the friction coefficient.

• 대한안전경영과학회지
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• 제12권4호
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• pp.81-86
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• 2010

Despite the importance of cycling postures during cycling performances, there has been a very little research investigating cycling postures and pedaling rate for particularly concerning domestic cyclists. The aim of this study was to analyze correlations and effects between cycling postures and pedaling rate in track cycling. Twelve male racing cyclists (six racing and university cyclists) participated in this research. For this study, seven infrared cameras (Qualisys ProReflex MCU-240s) were used for collecting data and these were processed via QTM (Qualisys Tracker Manager) software. It appeared that pedaling rate had correlations with regard to a shoulder angle (R=-.601) and displacement between shoulder joints(R= -.637), but a knee (R=-.601) and ankle angle (R=.667). Moreover, two multiple regression equations of pedaling rate for cycling postures were significant and R2 of the first order equation y (pedaling rate) = 0.039x (knee angle) - 1.068 was less than the second order equation y = 0.006x2 - 1.287x + 69.674. In conclusion, cycling postures affected the pedaling rate. Further study should be researched on postures in relation to air resistance in a wind tunnel.

• 대한전기학회논문지:시스템및제어부문D
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• 제55권9호
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• pp.401-408
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• 2006

In a multi-sensor multi-target tracking systems, the local sensors have the role of tracking the target and transferring the measurements to the fusion center. The measurements from the same target can arrive out of sequence called the out-of-sequence measurements(OOSMs). Out-of-sequence measurements can arise at the fusion center due to communication delay and varying preprocessing time for different sensor platforms. In general, the track fusion occurs to enhance the tracking performance of the sensors using the measurements from the sensors at the fusion center. The target informations can wive at the fusion center with the clutter informations in cluttered environment. In this paper, the OOSM update step with MPDA(Most Probable Data Association) is introduced and tested in several cases with the various clutter density through the Monte Carlo simulation. The performance of the MPDA with OOSM update step is compared with the existing NN, PDA, and PDA-AI for the air target tracking in cluttered and out-of-sequence measurement environment. Simulation results show that MPDA with the OOSM has compatible root mean square errors with out-of-sequence PDA-AI filter and the MPDA is sufficient to be used in out-of-sequence environment.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.2107-2115
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• 2018

Over recent years, high-concentration of particulate matters (e.g., a.k.a. fine dust) in South Korea has increasingly evoked considerable concerns about public health. It is intractable to track and report $PM_{10}$ measurements to the public on a real-time basis. Even worse, such records merely amount to averaged particulate concentration at particular regions. Under this circumstance, people are prone to being at risk at rapidly dispersing air pollution. To address this challenge, we attempt to build a predictive model via deep learning to the concentration of particulates ($PM_{10}$). The proposed method learns a binary decision rule on the basis of video sequences to predict whether the level of particulates ($PM_{10}$) in real time is harmful (>$80{\mu}g/m^3$) or not. To our best knowledge, no vision-based $PM_{10}$ measurement method has been proposed in atmosphere research. In experimental studies, the proposed model is found to outperform other existing algorithms in virtue of convolutional deep learning networks. In this regard, we suppose this vision based-predictive model has lucrative potentials to handle with upcoming challenges related to particulate measurement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.735-737
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• 2003

A superconducting motor consisting of high temperature superconducting (HTS) rotor and air-core stator is under development in Korea Electrotechnology Research Institute. HTS motor was designed for having the rated power of 100hp at 1800 rpm. HTS field winding is composed of sixteen HTS race track shaped coils wound with stainless steel-reinforced Bi-2223 tape conductor by react and wind fabrication method. Nomex Paper was used for electrical insulation. Each of four magnet pole assemblies was constructed with four double pancake sub-coils, mechanically stacked and electrically in series. Four magnet assemblies were fixed on an aluminum support structure to make effective heat transfer. Critical current (Ic) of HTS field winding was 41A but minimum Ic of sub-coils was 35A at 77K and self field. Joule heat generated in HTS field winding was 2.11W at 77K and 35A.

• Journal of Mechanical Science and Technology
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• 제20권2호
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• pp.242-250
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• 2006

Detailed structures of the counterflow flames formed for different inlet fluid temperatures and different amount of additives are studied numerically. The detailed chemical reactions are modeled by using the CHEMKIN-II code. The discrete ordinates method and the narrow band based WSGGM with a gray gas regrouping technique (WSGGM-RG) are applied for modeling the radiative transfer through non-homogeneous and non-isothermal combustion gas mixtures generated by the counterflow flames. The results compared with those obtained by using the SNB model show that the WSGGM-RG is very successful in modeling the counterflow flames with non-gray gas mixture. The numerical results also show that the addition of $CO_2\;or\;H_2O$ to the oxidant lowers the peak temperature and the NO concentration in flame. But preheat of fuel or oxidant raises the flame temperature and the NO production rates. $O_2$ enrichment also causes to raise the temperature distribution and the NO production in flame. And it is found that the $O_2$ enrichment and the fuel preheat were the major parameters in affecting the flame width.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.1075-1080
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• 2006

Purpose of this study is proposal of estimating method about window thermal performance that based on KS F 2278 'Test method of thermal resistance for windows and doors' due to material composition of PVC frame window. First step of this study is research of present state about material composition of PVC frame window. Second is selection of main effective elements about window thermal resistance. For example, composition of Glazing, Frame area ratio of total window area, frame width, opening type, area of heat transfer and so on. Third is multiple regression analysis about thermal performance of PVC frame window due to main effective elements. It produces equations of multiple regression analysis due to opening type. Case of sliding window is $Y=0.149+0.034X_g+0.248X_{far}$, 4track sliding is $Y=0.584+0.175X_g+1.355X_{far}-0.008X_{fw}$, Tilt & Turn window is $Y=-0.161+0.076X_g+0.576X_{far}+0.0008X_{fw}$.

• 전기전자학회논문지
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• 제23권2호
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• pp.747-750
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• 2019

웨어러블 디바이스는 일상생활에서 실질적으로 필수적이며 사용자들에게 편리하게 이용되고 건강관리와 의학 분야 등에 활용되고 있다. 전력분야에서 전원 배터리의 사용시간의 한계를 극복하고 효율적인 충전방법에 관한 많은 연구가 진행되고 있다. 무선전력전송은 전선을 사용하지 않고 무선으로 전기장을 부하에 전력을 전달하는 기술이다. 이 전송기술은 저 전력의 스마트폰에서부터 고 전력을 사용하는 철도 충전시스템까지 응용분야가 다양하다. 충전방식은 유도방법과 자기공진방법의 2 종류로 나누는데 자기공진주파수는 13.45 Mhz를 사용하였다. 본 연구에서는 전송효율을 측정 비교하기 위하여 2 종류의 하드웨어를 구현한 후 비교하는데 있다.

• 한국기계가공학회지
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• 제19권11호
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• pp.70-77
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• 2020

Vibratory bowl feeders are widely utilized to align and feed the parts stacked inside the bowl of a feeder. The electro-magnetic force of the electromagnet in a bowl feeder generates the excitation force for the bowl to vibrate in both the horizontal and vertical directions to continuously feed the parts on the track. The feed rate of the part depends on the associated displacement in each direction during the vibration. Therefore, the excitation force induced by the electromagnet should be estimated in advance to ensure the suitable design of the bowl feeder. In this study, a theoretical solution was developed to calculate the electro-magnetic force of the electromagnet for a bowl feeder. Using the proposed solution, the electro-magnetic forces corresponding to a variation in the input parameters of the electromagnet, such as the voltage, frequency, and air gap, could be obtained. The force values obtained using the theoretical solution exhibited a satisfactory agreement with the results obtained using the finite element method, thereby demonstrating the validity of the approach. Subsequently, the bowl displacements were analyzed using the motion equation for the bowl feeder when the theoretically obtained excitation force were applied to vibrate the feeder. The correlation between the vertical displacements of the bowl and input parameters of the electromagnet could be obtained.

• 천문학회보
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• 제46권2호
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• pp.78.1-78.1
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• 2021

A Lunar observatory not only provides ideas and experiences for space settlements from the Moon to Mars, but also puts the telescope in an optimal position to compete with space telescopes. Earth observation on the Moon's surface has the advantage of no atmospheric scattering or light pollution and is a stable fuel-free observation platform, allowing all longitude and latitude of the Earth to be observed for a month. Observing the entire globe with a single observation instrument, which has never been attempted before, and calculating the global albedo will significantly help predict the weather and climate change. Spectropolarimetric observations can reveal the physical and chemical properties of the Earth's atmosphere, track the global distribution and migration path of aerosols and air pollutants, and can also help detect very small space debris of which the risk has increased recently. In addition, the zodiacal light, which is difficult to observe from Earth, is very easy to observe from the lunar observatory, so it will be an opportunity to reveal the origin of the solar system and take a step closer to understanding the exoplanet system. In conclusion, building and developing a lunar observatory will be a groundbreaking study to become the world's leader that we have never tried before as a first step in expanding human experience and intelligence.