• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.93-98
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• 2022

The purpose of this paper was to propose a method for improving the performance of the open-loop control of single-phase permanent magnet synchronous motor (SP-PMSM), based on a square wave voltage injection. Generally, the SP-PMSM driving systems cmprise a full-bridge inverter and asymmetric air-gap structure of magnetic circuit, because a zero torque occurs on the symmetrical air-gap. As a result, it cannot be started at a specific rotor position. Thus, it is possible to cause the start-up failure at an open-loop control for sensorless operation of SP-PMSM. In this paper, the method with square wave voltage injection considering the nonlinearity of the inverter is presented to resolve the problem. The effectiveness of the proposed algorithm is verified through several experiments.

• Journal of Korean Society of Steel Construction
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• v.25 no.3
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• pp.267-278
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• 2013

In this study, stiffened plates with open ribs are analyzed to estimate and formulate the local displacement and local moments according to square loading sizes. For the local behaviors of plates stiffened with rectangular and reverse T ribs, the ratio functions according to the dimensions of stiffened plates are obtained at each square loading size. Analytical results show that values of the basic stiffened plates are different but the ratio functions of each square loading size are similar and the difference of the ratio functions between rectangular ribs and reverse T ribs are small, so the ratio functions can be unified by integrating the loading sizes regardless of the rib type. The application of the unioned ratio functions to L type ribs and rectangular loading shows good accuracies. Therefore, the local behaviors of plates stiffened with open ribs can easily be obtained by using the unioned ratio functions proposed in this study.

• The Journal of Sustainable Design and Educational Environment Research
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• v.10 no.1
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• pp.1-9
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• 2011

In order to solve the current shortage of parking spaces, and redesign the main gate area of the U University, the research investigated some cases of other schools located in Seoul which actively constructed multi-purpose building structures. Those schools are considered to be good samples showing their efforts to fulfill the needs of more parking spaces in their campuses, and to cover with the growing needs of multi-functioned facilities accommodating services of academic affairs, reading room spaces, and amenities. With the investigation, the research finded out the current trends of campus developments from the sample schools, such as underground parking facilities connected with multi-purpose buildings along the main arteries of campuses. Following the trends the research thoroughly examined the present conditions of our school and tried to make some possible alternatives for the facilities. Under the conditions, the research suggested 1)to construct underground parking lots accepting around 1,000 cars under the ivory tower square located in front of University Administration Building, 2)to develop a big-scaled open square at the university main gate, and 3)to build a multi-purpose structure along the main street of the campus, which included administration services, studying spaces, and some commercial facilities.

• Wind and Structures
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• v.17 no.3
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• pp.245-262
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• 2013

The flow interaction between two identical neighboring twin square prisms in a staggered arrangement in an open terrain was investigated experimentally. The downwind prism was mounted on a rigid-aeroelastic setup in an open-terrain boundary layer flow to measure its acrosswind root-mean-square responses and aerodynamic damping ratios. By varying the relative location of the upwind prism and the Scruton number associated with the downwind prism, the acrosswind aeroelastic behavior of the downwind prism was analyzed and compared to that of an isolated one. Results showed that the acrosswind root-mean-square response of the downwind prism could be either suppressed or enhanced by the wake flow produced by the neighboring upwind prism. Besides the assessment of the wake effect of the downwind prism, finally, regressed relationships were presented to describe the variation of the aerodynamic damping ratio so as to predict its acrosswind fluctuating response numerically.

• Architectural research
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• v.9 no.1
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• pp.19-30
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• 2007

This study explores the issue of campus expansion of an urban university using an in-depth case study of New York University in New York City, USA. It investigates the physical pattern and development mechanism of the campus expansion process on a city grid structure. The three elements that characterize NYU's recent campus expansion, are (1) the university's commitment to building a student community around a public open space on a subway network, (2) four types of property acquisition and building development practiced by the university with private developers for space leasing, building renovation and development under changing local development circumstances, and (3) the city's initiative for attracting the private sector whose development activities influence the university's development dynamics. These findings suggest that the expansion planning of an urban university, due to its location in a city, should be placed on a local planning agenda, which can positively contribute to public goals through the collaborative engagement of the private and public sectors.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.115-124
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• 2007

The purpose of this study was to analyze the kinematics variables of upper limb joint during forehand stroke by swings patterns. Eight high school tennis players were chosen for the study, who have never been injured for last six months, in Busan. They performed horizontal swing and vertical swing that it was done each five consecutive trial in the condition of square, semi-open and open stance. It was filmed by 6 video camera and used with 3-dimensional motion analyzer system. The following kinematic variables were analyzed in relation to angle of joint(shoulder, elbow and wrist joint). The conclusion were as follow: 1. The angle of right shoulder joint represented all event that both swing were shown similar pattern in swing type and stance pattern. 2. All event in the angle of elbow joint had consistent with that except E2, horizontal and vertical swings in square stance. 3. All event in the angle of wrist joint was show to similar pattern except E2, horizontal and vertical swing in open stance.

• The Mathematical Education
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• v.43 no.3
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• pp.275-289
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• 2004

The purpose of the study is to investigate how children and preservice teachers would make a progress in solving the open-problems related to area. In knowledge-based information age, information inquiry, information construction, and problem solving are required. At the level of elementary school mathematics, area is mainly focused on the shape of polygon such as square, rectangle. However, the shape which we need to figure out at some point would not be always polygon-shape. With this perspective, many open-problems are introduced to children as well as preservice teacher. Then their responses are analyzed in terms of their logical thinking and their understanding of area. In order to make students improve their critical thinking and problem solving ability in real situation, the use of open problems could be one of the valuable methods to apply.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.6
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• pp.111-123
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• 2014

The city square is an important public open space for people. Being used for various activities, such as community gatherings, open markets, concerts, political rallies, and other events, many types of city squares are represented in a city. Nevertheless, most city squares are planned uniformly, lacking consideration for visitor behavior and use satisfaction. The study investigated the design factors and subcomponents influencing user satisfaction with different types of city squares. This study focused on the general city square in Seoul, including the grand public place (i.e. Gwanghwamun Square) and the neighborhood park (i.e. Geumbit Square). The data were analyzed using factor analysis, linear regression and fuzzy theory. The results of the study are as follows: first, five design factors of satisfaction with city squares are identified (Amenity, Usability, Spatial components, Culture, and Comfortableness). Second, Amenity, Comfortableness, and spatial components significantly affect user satisfaction with Gwanghwamun in that order. On the other hand, in Geumbit Square, Comfortableness, Amenity, Usability and Spatial components affect user satisfaction in a significant way, in that order. Third, cleanliness, a subcomponent of amenity, was ranked highest using the fuzzy theory function for satisfaction with Gwanghwamun Square. Otherwise, the prevalence of plants was ranked the highest on the Geumbit Square survey. The study compared design factors influencing satisfaction in the public grand place and the neighborhood park. The results have implications for designing and planning city squares to the satisfaction of their visitors.

• Explosives and Blasting
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• v.19 no.1
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• pp.71-84
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• 2001

Korean peninsula has the most mountainous areas such as mountains and hilly country, and it is surrounded by the sea on all sides but one. In this respect, a large scaled construction works have frequently been conducted. However, it is not easy to porform a large scale blasting work without giving any harm to houses or facilities nationwide. Therefore, blasting work becomes more closely related to maintenance thing due to the development of the downtown or a large structure for key facilities. Many researches on blast in the open space and tunnel blasting have been conducted. On the contrary, research on underwater blasting operations is comparatively scanty even though much more necessity of marine development is required. In this respect, this study aims to investigate the characteristics of underwater blasting operations and to make a comparative study with blast in the open space. As a result of examining into the characteristics during underwater blasting operations, the around oscillation in case of underwater blasting operations shows significantly low compared to that in case of blast in the open space, and this means that much more cautious altitude must be taken in designing underwater blasting operations compared to the design of blast In the open space. As a result of analysis on the difference between a square root and a cube root In the equation of estimating oscillations in the actual site, it is shown that it is shown to apply a square root for the estimation of oscillation at 60 meters in case of underwater blasting operations and at 22 meters case of general blast in the open space.

• Journal of the Korean Institute of Educational Facilities
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• v.19 no.3
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• pp.3-12
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• 2012

Owing to generalization of design competitions since 1990s, various design methods was tried in elementary middle high school design competitions. Therefore, to analyze design characteristics of elementary middle high school is very meaningful. In this context, this study is the most important purpose for analyzing layout plans and their trends in prizewinners of elementary middle high school design competitions and for furnishing basic datum for next school design. The result of this study is following : (1) The layout patterns of school buildings are classified into 12 types. (2) Entrance design is divided into 6 types(structure, column and wall, open, half structure, general, and mixed type). (3) Square design is grouped into 7 types. (4) Pedestrian mall is sorted out 6 types(straight lineal, curve, curve and square, straight lineal and curve, and straight lineal and curve and square type). (5) Entrance types of vehicle and pedestrian are classified into 4 types(parallel, ㅡ separation, ㄱ separation, and opposite separation type) Analysis shows that the best applying for layout patterns of school buildings is ㄷ type and ㅌ type, for entrance design is structure type, for square design is ${\square}$ type and ${\bigcirc}$ type, for pedestrian mall is straight lineal and square type, and for entrance types of vehicle and pedestrian is parallel type.