• 한국대기환경학회지
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• 제25권4호
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• pp.264-274
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• 2009

Concentration of Air Quality Models (CMAQ) has a deep connection with emissions and wind fields. In particular the wind field is highly affected by local topography and plays an important role in transport and dispersion of contaminants from the pollution sources. The purpose of this study is to examine the impact of interpolation on Air quality model. This study was designed to evaluate enhancement of MM5 and CMAQ predictions by using Four Dimensional Data Assimilation (FDDA), the SONDE data and the national meteorological station and the MODerate resolution Imaging Spectroradiometer (MODIS). The alternative meteorological fields predicted with and without MODIS data were used to simulate spatial and temporal variations of ozone in combined with CMAQ on June 2006. The result of this study indicated that data assimilation using MODIS data provided an attractive method for generating realistic meteorological fields and dispersion fields of ozone in the Korea peninsular, because MODIS data in 10 km domain are grid horizontally and vertically. In order to ensure the success of Air quality model, it is necessary to FDDA using MODIS data.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 추계학술대회
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• pp.495-497
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• 2012

의료기기 소프트웨어 테스트 위험관리 적용 방안에 대해 연구하였다. 먼저 설문조사를 통해 의료기기 제조업체의 소프트웨어 밸리데이션 및 위험관리 현황을 분석하고 두 번째로 블랙박스 테스트와 화이트 박스 테스트를 비교하여 차이점을 분석하였다. 세 번째로 소프트웨어 분석 도구를 활용한 코드 분석 후 잠재적인 위해요인을 도출하고 이를 정량화 하였으며, 마지막으로 도출된 위해요인을 FMEA 기법을 이용하여 의료기기 위험관리 프로세스에 적용할 수 있도록 프레임워크를 구축하였다. 이를 통해 의료기기 품질관리(GMP) 업무 중 소프트웨어 밸리데이션 및 위험관리 프로세스를 구축하기 어려운 제조업체를 위한 업무 지원에 활용하고자 한다.

• 대한전기학회논문지:전력기술부문A
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• 제51권6호
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• pp.262-268
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• 2002

Preventive control has to solve two important problems. The first is fast and accurate severity assessment of instability originated from the occurrence of a dangerous contingency. The second is to choose an action able to stabilize it. In this paper we assess contingencies in power systems using PASF(Power Angle Shape Filtering) and control power systems by a generation rescheduling. The control action stabilize the whole set of harmful contingencies simultaneously. Note that conventional time-domain transient stability methods can hardly tackle preventive control. So, we study the preventive control using off-line method. The proposed method is applied to prevent and to correct loss of synchronism of all the generators in a operating systems data.

• Journal of Biosystems Engineering
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• 제17권4호
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• pp.354-362
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• 1992

This study was intended to examine feasibility of sizing and color grading of Fuji apple with black/white image processing system, to develop a device with which the whole surface of an apple could be captured by one camera, and to develop an algorithm for a high speed sorting. The results are summarized as follows : 1. The black/white image processing system used in this study showed a maximum error of 1.3% in area measurement with a reference figure while the focusing point of camera and location of the reference figure were changed within a certain range. 2. As the result of evaluating four automatic image segmentation algorithms with apple images, Histogram Clustering Method was the best in terms of computation time and accuracy. 3. The fast algorithm for analyzing size and coloration of apple was developed. 4. The whole surface of an apple could be captured in an image frame with two mirrors installed on the both sides of the sample. The total area of the image representing the whole surface showed a correlation of 0.995 with the weight of apple. 5. The gray level when a particular band pass filter was mounted on the camera showed high correlation with 'L' and 'a' values of Hunt color scale and could represent the coloration of apple.

• 동력기계공학회지
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• 제9권1호
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• pp.70-75
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• 2005

The damping property of Fe-12Cr-22Mn-X alloys has been investigated to develop high damping and high strength alloy. Particularly, the effect of the phase of austenite, alpha and epsilon martensite, which constitute the structure of the alloys Fe-12Cr-22Mn-X alloys, on the damping capacity at room temperature has been investigated. Various fraction of these phases were formed depending on the alloy element and cold work degree. The damping capacity is strongly affected by ${\varepsilon}$ martensite while the other phase, such as ${\alpha}'$ martensite, actually exhibit little effect on damping capacity. In case of Fe-12Cr-22Mn-3Co alloy, the large volume fraction of ${\varepsilon}$ martensite formed at about 30% cold rolling, and in case of Fe-12Cr-22Mn-1Ti alloy, formed at about 20% cold rolling and showed the highest damping capacity. Damping capacity showed higher value in Fe-12Cr-22Mn-1Ti alloy than one in Fe-12Cr-22Mn-3Co alloy.

• 한국소음진동공학회논문집
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• 제17권12호
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• pp.1246-1253
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• 2007

The recent issue of optical pickup actuators is to apply optical storage devices to mobile devices such as a cellular phone and PDA. It requires actuators to become smaller than conventional types. As the size becomes smaller, the magnetic force is reduced and the assembly of optical pickup actuators becomes more difficult. In addition, its dynamic characteristics are changed. In this paper, methods to improve magnetic forces and dynamic characteristics are suggested and the optimal result of the plate spring design is obtained. A diamond shape magnet and the fine pattern coil (FPC) are used to improve magnetic forces and damping elements are attached to decrease the peak magnitude of the mode instead of using structural damping, mostly for the purpose of improving the accuracy of the finite element simulation. To get more stable dynamic characteristics than conventional ones, a plate spring is applied to the optical pickup actuator and it is optimized with topology and parameter optimization to obtain the concept and the detail design, respectively.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2013년도 춘계학술대회 논문집
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• pp.60-64
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• 2013

Water injection pump produced the 1st oil well through the high pressure after the Deep water oil well drilling. After finish the work it is hard to produce only using itself pressure due to low pressure. Therefore it can be increased recovery factor through the injection seawater of high pressure. Is the key equipment used in the marine plant and it is developing at many industries. In this paper, Analyze changes in the natural frequency due to the stiffness of the bearing. Analyze the critical speed of the natural frequency due to the change of operation speed. And evaluate the Stability. And then analyze the displacement and clearance through the unbalance response this way has contributed to the reliability of the developing product. Through a mathematical analysis.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.366-366
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• 2009

후면접합 태양전지는 상용 태양전지의 수평전류 손실(lateral current loss) 이 없으며, 전면전극에 의해 발생하는 그림자 손실(shading loss) 줄인 고효율 태양전지의 하나이다. 생성된 반송자가 후면에 위치한 전극에서 수집되기 때문에 효율향상을 위해서는 불순물에 의한 재결합을 줄이는 것이 중요하다. 따라서 Gettering 은 높은 소수반송자 수명(life-time)을 가지는 고품위 실리콘 기판은 고효율 실리콘태양전지 제작을 위한 중요 요소 기술이다. 본 연구에서는 n-type c-Si 기판을 이용한 고효율 실리콘 이종접합 태양전지제작을 위해 external gettering 공정을 이용하여 고품위 실리콘 기판을 제작하였다. POC13 doping process 의 온도, 시간을 변화시킴으로써 이에 따른 변화를 관찰하였다. 주사전자현미경(SEM)를 통해 etch pit 을 확인 했으며,Four point probe 를 통해 면저항을 측정, 인(P)의 농도를 계산 하였다. 계산된 면저항을 통해 인(P)의 확산 깊이를 계산하였다. Iodine passivation 된 시편을 Qusi-steady state photoconductance (QSSPC)를 이용하여 소수반송자 수명을 측정함으로써 gettering 에 의한 bulk lifetime 향상 효과를 관찰하였다.

• 한국산업융합학회 논문집
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• 제12권2호
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• pp.91-97
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• 2009

The productivity and the precision machining are the major concerns of the machine tools, and the importance of those features will be even more emphasized with the needs of the modern industries. In this paper the dynamic properties of a lathe have been investigated through the frequency analysis test and the computer simulation to minimize the transmission of vibration generated during the machining process. The modifications have been applied to the original structure to suppress the vibration transmission and further for the structure to achieve less vibrations and higher precision machining. The result shows that the machine can have much less vibrations with simple design alterations for minor expenses, the result can also be readily applied to many similar machines for improved stability.

• 한국도로학회논문집
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• 제19권6호
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• pp.147-153
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• 2017

PURPOSES : This research aims to estimate the occurrence of hydroplaning on roads based on the road alignment types and rainfall intensity in Seoul. METHODS : Three types of data were used for estimation of hydroplaning in this study. The Inner Circulation Road (12.5 km) to the Bukbu Expressway (7.4 km) in Seoul was selected as the test road and data was collected for road information using a probe-vehicle. Precipitation was observed from Automatic Weather System in Seoul. These data were interpolated by applying Inverse Distance Weighted Methodology for hydroplaning estimation. Finally, the water depth information of the roads was observed using an RCM411 device. RESULTS : This study demonstrated that the cross slope with small-angle-tilt or vertical section with large-angle-tilt are the primary factors causing hydroplaning on the roads. The flow velocity on steep slope is high; however, large drainage lengths result in hydroplaning on the roads. CONCLUSIONS : This result can contribute towards the reduction of car accidents on rainy days. Furthermore, information regarding hydroplaning can be delivered to drivers more rapidly and precisely in the future.