• 한국항해항만학회지
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• 제34권8호
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• pp.609-614
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• 2010

본 논문에서는 목포 대교와 통항 선박 사이의 충돌 확률 계산에 필요한 통계 변수 추정에 관해 기술했다. 먼저 목포대교 통항 선박들의 AIS(Automatic Identification System) 정보를 입수한 후, 선박들의 통항 궤적 분포를 분석하고, 목포대교 중심으로 부터의 이격 거리와 목포대교 통항시의 침로 및 속력 등에 대한 평균과 표준편차를 추정하였다. 궤적 분포 분석 결과, 이격 거리와 통항 침로에 대한 궤적 분포는 정규 분포 형태로 나타났고, 통항 속력 분포는 서로 다른 두 종류의 정규 분포 형태를 나타냈다. 그리고 궤적 분포와 이들의 정규 확률분포와의 상대 비교를 통해서 추정한 확률 변수 값의 유용성을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1994년도 하계학술대회 논문집 A
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• pp.419-421
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• 1994

A CRU (Customer Remote Unit) for KODAS(Korea Distribution Automatic System) is presented in the paper. This equipment works as a terminal unit for the Load Control and the AMR(Automatic Meter Reading). It is composed of control, drive, input, display, and communication parts. A CRU calculates and memorizes the active power, time-of-use, and demand by the pulse from watthour meter for AMR. It also transfers the data to Center Control System. It can measure current, voltage, and power factor by adding the simple circuit. For load control, It receives the necessary informations such as the load control periods, modes, and time intervals. It controls the load until the stopping commad comes. The system reliability has been proved using a prototype.

• 한국대기환경학회지
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• 제25권1호
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• pp.57-74
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• 2009

In order to clarify the vertical ozone distribution in planetary boundary layer of coastal area with complex terrain, an observation campaign was carried out around Gwangyang Bay with dense pollutant emission sources during two days from June, 4 2007. For this observation are Radiosonde, SODAR(SOnic Detection And Ranging) and Tethered ozone sonde were employed. The surface meteorological and photochemical observation data provided by AWS (Automatic Weather System) and AQMS (Air Quality Monitoring System) were also applied for analysis. Synoptic condition is strongly associated with lower level ozone distribution in complex terrain coastal area. Since mesoscale circulation induced by difference of characteristics of land and sea and orographic forcing is predominant under calm synoptic condition, vertical distribution of ozone is complicate and vertical ozone concentration greatly fluctuated. However in second day when synoptic influence become strong, ozone concentration in lower levels is vertically uniform regardless of observation level. This results in vertical observation indicates that vertical ozone distribution is often determined by synoptic condition and also affects surface ozone concentration.

• Journal of Computational Design and Engineering
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• 제1권1호
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• pp.48-54
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• 2014

In this paper, the authors propose a system for assisting mold designers of plastic parts. With a CAD model of a part, the system automatically determines the optimal ejecting direction of the part with minimum undercuts. Since plastic parts are generally very thin, many rib features are placed on the inner side of the part to give sufficient structural strength. Our system extracts the rib features from the CAD model of the part, and determines the possible ejecting directions based on the geometric properties of the features. The system then selects the optimal direction with minimum undercuts. Possible ejecting directions are represented as discrete points on a Gauss map. Our new point distribution method for the Gauss map is based on the concept of the architectural geodesic dome. A hierarchical structure is also introduced in the point distribution, with a higher level "rough" Gauss map with rather sparse point distribution and another lower level "fine" Gauss map with much denser point distribution. A system is implemented and computational experiments are performed. Our system requires less than 10 seconds to determine the optimal ejecting direction of a CAD model with more than 1 million polygons.

• KEPCO Journal on Electric Power and Energy
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• 제2권2호
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• pp.245-251
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• 2016

Despite the exponential throughput improvement in mobile communications systems, their ability to satisfy requirements of state-of-the-art and future applications of advanced metering infrastructure (AMI) is still under investigation. Challenges are mainly due to the inadequacy of third generation partnership project (3GPP) networks to support large amounts of devices simultaneously, while the number of AMI end-devices and the frequency of their data transmission increase with new AMI-based applications. In this introductory survey, innovative and future AMI applications and their communication requirements are first reviewed. Then, we identify challenges of 3GPP long term evolution (LTE) in enabling future AMI applications. More importantly, the latest improvements to LTE-A standard release 12 and 13 are reviewed and analyzed with regards to their potential to improve the quality of LTE-enabled AMI. It is found that 3GPP enhancements on machine type communications (MTC) standards will significantly enhance AMI communications. Beyond MTC specifications, non-MTC-specific enhancements such as carrier aggregation and multi-connectivity for user equipment will also contribute greatly to improving reliability and availability of AMI devices. The paper's focus is towards improved backhaul support for innovative and future AMI applications, beyond traditional automatic meter reading.

• 조명전기설비학회논문지
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• 제27권4호
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• pp.62-72
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• 2013

To operate an automatic picking system in distribution center with high precision and high dynamics, this paper presents a robust control scheme of a linear induction motor (LIM) using the mass estimation and disturbance force observer. The force disturbance which gives a direct influence on the control performance of LIM is estimated in real-time through the disturbance observer and compensated by a feedforward manner. To get a satisfactory performance even under the mass variation by reducing the disturbance force due to the mismatched mass during the speed transient such as the acceleration and deceleration periods, a mass estimation algorithm is proposed. A Simulink model for LIM is developed and the validity of the proposed scheme is verified through the comparative simulation studies using Matlab - Simulink.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 1999년도 추계 학술대회논문집
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• pp.108-114
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• 1999

In this paper. a new automatic multi=block grid generation technique for general 2D regions is introduced. According to this simple and robust method, the domain of interest is first triangulated by using Delaunay triangulation of boundary points, and then geometric information of those triangles is used to obtain block topology. Once block boundaries are obtained. structured grid for each block is generated such that grid lines have $C^0-continuity$ across inter-block boundaries. In the final step of the present method, an elliptic grid generation method is applied to smoothen grid distribution for each block and also to re-locale the inter-block boundaries, and eventually to achieve a globally smooth multi-block structured grid system with $C^1-continuity$.

• 전기학회논문지
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• 제57권10호
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• pp.1744-1751
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• 2008

This paper presents a monitor positioning algorithm to identify the power quality event source in the distribution system with distributed generations. This algorithm determines the appropriate number of monitors and their locations considering power system topology together with distributed generation. This paper summarizes the guidelines of monitor positioning into five principles and defines the weighting factors according to the principles. To evaluate the adequacy of monitor positioning results, ambiguity indices considering monitor location and system topology are proposed. The optimal number and locations of monitors are determined from optimization routine using the weighting factors and the monitor positioning results are evaluated in terms of ambiguity indices. The algorithm is applied to IEEE 13 bus test feeder and suggests the optimal number and locations of power quality monitors. The proposed approach can realize the expert's knowledge on monitor positioning into a sophisticated automatic computing algorithm.

• 한국인터넷방송통신학회논문지
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• 제14권5호
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• pp.95-102
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• 2014

본 논문에서는 스마트 LED 가로등을 위한 고속 전력선 통신 기반 자동제어 시스템을 제안한다. 제안된 자동제어 시스템은 고속 전력선 통신망을 이용하여 고속 통신 주파수 대역과 가로등 안정기 특성 분석 및 실시간 원격 제어가 가능하도록 전력선 모뎀부와 모니터링부, 가로등 제어부로 구성하였고, KS 도로조명기준의 조명등급 조건에 만족하도록 설계하였다. 제안된 자동제어 시스템은 기존 가로등 시스템의 비교 결과를 통해 PC를 사용하여 소비 전력을 쉽게 모니터링 하였다. 그 결과, LED 가로등 상태 검사 및 원격 제어를 통해 합리적 소비 전력의 유도에 의해 실시간 모니터링 및 관리를 위한 효율적인 운영의 가능성을 확인 하였다. 또한, 전력요금 절감 및 에너지 효율화, 가로등의 차별화/고급화에 대한 기대효과 향상을 증명하였다.

• 전기학회논문지
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• 제58권2호
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• pp.308-313
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• 2009

This paper presents a reliability analysis of S-bonds for AF track circuits, which detect train movement and transmit a speed control signal to the train. Field survey shows that S-bonds are exposed to very large vibrations transferred from rail, and suffer from frequent failures when they were installed on ballasted track. We collected the time-to-failure data of S-bonds from the maintenance field of Seoul metro line 2, and made a parametric approach to estimate the statistical distribution that fits the time-to-failure data. The analysis shows that S-bonds have time-to-failure characteristics described by Weibull distribution. The estimated shape parameter of Weibull distribution is 1.1, which means the distribution has constant failure rate characteristics like exponential distribution. The reliability function, hazard function, percentiles and mean lifetime are derived for maintenance support.