• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제27권1호
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• pp.75-86
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• 2023

The angle of attack is highly sensitive to pitch point in the airfoil shape and the decline of pitch point value induces smaller angle of attack, which implies that airfoil profile possessing closer pitch point to the airfoil tip reacts more sensitively to upcoming wind. The method of conformal transformation functions is employed for airfoil profiles and airfoil surfaces are expressed with a trigonometric series form. Attack angle and ideal lift coefficient distributions are investigated for various airfoil profiles in wind turbine blade regarding conformal transformation and pitch point. The conformed angle function representing the surface angle of airfoil shape generates various attack angle distributions depending on the choice of surface angle function. Moreover, ideal attack angle and ideal lift coefficient are susceptible to the choice of airfoil profiles and uniform loading area. High ideal attack angle signifies high pliability to upcoming wind, and high ideal lift coefficient involves high possibility to generate larger electric energy. According to results obtained pitch point, airfoil shape, uniform loading area, and the conformed airfoil surface angle function are crucial factors in the determination of angle of attack.

• 전기학회논문지
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• 제58권4호
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• pp.671-678
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• 2009

This paper presents target operation voltage guidelines of each voltage control area considering both voltage stability and economical efficiency in real power system. EMS(Energy Management System) data, Real-time simulator, shows not only voltage level but lots of information about real power system. Also this paper performs optimal power flow calculation of three objective functions to propose the best target operation voltage. objective function of interchange power flow maximum and active power loss minimization stand for economical efficiency index and reactive power reserve maximum objective unction represents stability index. Then through simulation result using optimazation technique, the most effective objective function is chosen. To sum up, this paper divides voltage control area into twelve considering electric distance characteristics and estimate or voltage level by the passage of time of EMS peak data. And through optimization technique target operation voltage of each voltage control area is estimated and compare heir result. Then it is proposed that the best scenario to keep up voltage stability and maximize economical efficiency in real power system.

• 한국실내디자인학회논문집
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• 제15권5호
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• pp.209-220
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• 2006

The goal to establish one multipurpose senior center in one district of Seoul city has been nearly completed. However, since it is behind the schedule by about 6 years, nearly all senior centers are saturated currently. Therefore, additional foundation plan of senior centers is in progress. Also, the main function of the center has changed from health and leisure to various welfare programs that the elderly living in a community need. In order to supplement these problems, many existing senior centers are using center to the most through addition and change of rooms. To establish the direction of spatial plan at establishing senior centers according to the regional characteristics, 20 cases of Seoul multipurpose senior centers in operation were site surveyed and the results of spatial features by types established and changed corresponding to each condition were suggested as follows: 1. The types were classified according to the shape of floor plan, sectional planning, entry traffic line, linkage with attached facilities and addition method etc. by the characteristics of the elderly in multipurpose senior centers, program operation, linkage of spatial composition by the function, positional relation between centers, management and operation method, and center complication method etc. and the respective features were suggested. 2. By analyzing the gross floor area and the area of each room of senior centers, the features of area by types and the features of area by each detailed center were suggested.

• 대기
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• 제25권2호
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• pp.193-203
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• 2015

A large aperture scintillometer (LAS) was deployed with an optical path length of 2.1 km to estimate turbulent sensible heat flux (${\mathcal{Q}}_H$) over a highly heterogeneous urban area. Scintillation measurements were conducted during cold season in November and December 2013, and the daytime data of 14 days were used in the analysis after quality control processes. The LAS-derived ${\mathcal{Q}}_H$ show reasonable temporal variation ranging $20{\sim}160W\;m^{-2}$ in unstable atmospheric conditions, and well compare with the measured net radiation. The LAS footprint analysis suggests that ${\mathcal{Q}}_H$ can be relatively high when the newly built-up urban area has high source contribution of the turbulent flux in the study area ('northwesterly winds'). Sensitivity tests show that the LAS-derived ${\mathcal{Q}}_H$ are highly sensitive to non-dimensional similarity function for temperature structure function parameter, but relatively less sensitive to surface aerodynamic parameters and meteorological variables (temperature and wind speed). A lower Bowen ratio also has a significant influence on the flux estimation. Overall uncertainty of the estimated daytime ${\mathcal{Q}}_H$ is expected within about 20% at an upper limit for the analysis data. It is also found that stable atmospheric conditions can be poorly determined when the scintillometry technique is applied over the highly heterogeneous urban area.

• 한국음향학회지
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• 제25권3호
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• pp.101-106
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• 2006

본 연구에서는 그릴에 뚫려 있는 구멍이 마이크로스피커의 전체 임피던스에 미치는 영향에 대하여 조사하였다 이들에 대한 영향을 이론적으로 접근하기 위하여 그릴의 구멍을 열린 짧은 길이를 갖는 파이프시스템의 일종인 올피스로 취급하였다. 이에 대한 결과는 실험적으로 얻어진 특성과 매우 잘 일치하였다. 다시 말하면, 이들의 구멍크기가 작아지게 되면 구멍에 의한 음향임피던스가 매우 커지게 된다. 그 결과로써, 마이크로스피커의 전체 음향임피던스에 미치는 영향이 커지는 것을 알 수 있었다. 이처럼 그릴의 구멍크기가 작을수록 전체 임피던스에 미치는 영향이 커져서 마이크로 스피커 유닛에서 발생한 음향특성이 그릴의 사용으로 인하여 달라질 수 있게 된다.

• KIEAE Journal
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• 제10권2호
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• pp.9-18
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• 2010

As an aging population has increased vastly and nuclear families have been a dominating family type in modern Korean society, the numbers of the elderly who suffer Empty Nest Syndrome and LID (Loss Isolation Depression) syndrome have been accelerated. These syndromes involve psychological instability, melancholy, and lethargy. To make the elderly get out of this phenomenon and live actively, the scheme of converting their existing house into shared housing was set as a hypothetical solution in this study. This study sets out to find out responses of the elderly to alter their own house's function in housing improvement area. A Small Workshop Panel method was used and the elderly aged 55 years upwards took part and they own a detached house in a housing improvement area that is relatively large for the elderly or the elderly couple to live alone. Through the workshop, problems that the elderly have been experiencing within their houses were looked into and responses of the elderly on altering their house to shared housing by introducing developed schematic plans. Although, the first response was negative, positive responses from the house owners were carried out when a visual support i.e. developed shared housing plan was provided. The positive response was based on the fact that subsidies from the government on house renovation and tenants matching programs are supported as shared housing could provide home owners economical support with rents and help them to feel less lonely. This is a way of relieving the elderly from being neglected and supporting them to live and age actively in their later lives. Furthermore, by providing a visual media to the elder residents in housing improvement area, their greater understandings on the development and addressing their opinions were possible. Therefore, more tools that promote elder residents' participation are needed for future housing improvement projects and an aging society.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.302-303
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• 2011

Smart WAMAC (Wide Area Monitoring And Control) System, which supplements control function with the function of WAMS(Wide Area Monitoring System), is an intelligent system not only monitoring the wide area but controlling the power equipment according to defined procedure. This paper presents WAMAC system architecture for hierarchical Infra and considerations to design and implement.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.178-179
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• 2011

The exchange of information with legacy systems is a main issue in the era of SMARTGRID. Because WAMAC(Wide Area Monitoring and Control) system has monitoring function, as well as control function, it is very necessary for WAMAC to exchange data and information with SCADA(Supervisory Control and Data Acquisition) / EMS(Energy Management System). IEC 61970 CIM(Common Information Model) is an abstract model that represents all the major objects in an electric utility enterprise typically involved in utility operations. In this paper, a proposal that adopting CIM to WAMAC model be submitted so that the integration of various legacy system and application for itself be able to be flexible.

• 대한인간공학회지
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• 제17권3호
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• pp.71-80
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• 1998

This study proposed a method to apply certain fuzzy-related Quality control concepts to design customer-oriented products considering user requirements and information starting with the product development stage. This approach showed how to define the importance level of design elements and how to Quantify complex subjective perception of products using the fuzzy linguistic rating method and quality function deployment concepts. Using this approach, various customer requirements could be interpreted and reflected on the early design phase of a new product. To validate the proposed method, an experiment was conducted for designing the shape of the beeper using 14 subjects and 10 commercial beeper products. Front area, width/length ratio, thickness, curve variance, weight, and display area were selected as design elements of the beeper. The results showed that among design elements, front area and weight are significantly related with the subjective perception of the products. Consequently, this study indicates that customer decision on product selection could be made by quantification of user perception for beeper products.

• 한국IT서비스학회지
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• 제18권1호
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• pp.131-140
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• 2019

This study compares and analyzes the spatial distribution of people in two cities using location information in twitter data. The target cities were selected as Paris, a traditional tourist city, and Dubai, a tourist city that has recently attracted attention. The data was collected over 123 days in 2016 and 125 days in 2018. We compared the spatial distribution of two cities according to the two periods and residence status. In this study, we have found a hot place using a spatial statistical model called dart-shaped space division and estimated the urban area by reflecting the distribution of tweet population. And we visualized it as a CDF (cumulative distribution function) curve so that the distance between all the tweets' occurrence points and the city center point can be compared for different cities.