• Korean Journal of Child Studies
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• v.28 no.4
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• pp.51-71
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• 2007

Factors considered by mothers when choosing a kindergarten for their child were analyzed by mother's age, education level, and employment status. Questionnaires (Seo, 2002; Kim, 2001; Park, 1997) targeted 636 mothers of kindergarteners from 12 different kindergartens. Results were (1) in order of importance mothers considered : physical environment, tuition, humane environment, educational curriculum and program, and time spent for education. (2) Younger mothers considered the program of the kindergarten of more importance whereas older mothers considered the commuting method, size of kindergarten, and personality and competence of the principal and teachers of more importance. (3) College educated mothers considered curriculum and field trips to be important factors. (4) Employed mothers considered the importance of all day programs and hours of operation.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.645-656
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• 2008

The operation of express train on the Seoul Metropolitan Subway Network is centered on the Kyungbu and Kyungin lines and the short section between Dongducheon station and Ganyung station which is 20.7km long. It is true that the needs of many customers who want to reduce their commuting hours by express train is not satisfied. This paper proposes that the operation of express trains be enlarged to Sungbuk station on Kyungwon line which comes to 34.9 km long, and to Yangsu station from Youngsan station on Jungang line. The type of operation is mixed one with high and low speed trains, which operates express train by use of existing siding tracks without improving facilities such as extra building of sidings. This pragmatic study is to apply the goal of reducing running time as express train and to suggest the selection of appropriate stops, effectivenes analysis of express train operation and formation of train diagrams to actual operation.

• East Asian mathematical journal
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• v.38 no.5
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• pp.549-581
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• 2022

Let M be a semi-invariant submanifold with almost contact metric structure (𝜙, 𝜉, 𝜂, g) of codimension 3 in a complex space form M_n+1(c), c≠ 0. We denote by S and R_𝜉 be the Ricci tensor of M and the structure Jacobi operator in the direction of the structure vector 𝜉, respectively. Suppose that the third fundamental form t satisfies dt(X, Y) = 2𝜃g(𝜙X, Y) for a certain scalar 𝜃(≠ 2c) and any vector fields X and Y on M. In this paper, we prove that M satisfies R_𝜉S = SR_𝜉 and at the same time R_𝜉𝜙 = 𝜙R_𝜉, then M is a Hopf hypersurface of type (A) provided that the scalar curvature s of M holds s - 2(n - 1)c ≤ 0.

• Kyungpook Mathematical Journal
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• v.62 no.1
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• pp.133-166
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• 2022

Let M be a semi-invariant submanifold with almost contact metric structure (𝜙, 𝜉, 𝜂, g) of codimension 3 in a complex space form M_n+1(c) for c ≠ 0. We denote by S and R_𝜉 be the Ricci tensor of M and the structure Jacobi operator in the direction of the structure vector 𝜉, respectively. Suppose that the third fundamental form t satisfies dt(X, Y) = 2𝜃g(𝜙X, Y) for a certain scalar 𝜃 ≠ 2c and any vector fields X and Y on M. In this paper, we prove that if it satisfies R_𝜉𝜙 = 𝜙R_𝜉 and at the same time S𝜉 = g(S𝜉, 𝜉)𝜉, then M is a real hypersurface in M_n(c) (⊂ M_n+1(c)) provided that $\bar{r}-2(n-1)c{\leq}0$, where $\bar{r}$ denotes the scalar curvature of M.

• Journal of Advanced Marine Engineering and Technology
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• v.13 no.1
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• pp.57-68
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• 1989

This paper treats the analytical and experimental studies on the improvement of commutating circuit for the speed control of DC motor. A simple circuit composed of R, L and C elements is proposed here for switching off power SCR carrying the load current. The real important in this chopper circuit is to determine the reasonable values of commutating circuit constants. In this paper, the reasonable values of the commutating circuit constants are basically determined on a view point of commutating performances in the given circuit model and must satisfy the following conditions. The first, the peak commutating current should be larger than the anticipated maximum load current. The second, the circuit turn-off time (tc) must be longer than the SCR turn-off time (tq). The third, the resistor should be enough large to permit the current to be neglected in the analysis of the commutation circuit, as well as be enough small to permit to charge the capacity voltage (Ec) to the half the value of source voltage (E) before the next communication cycle is initiated. The last, the period of chopping signal must be the least possible multiple of the damping vibration period of commutating circuit. The improved chopper circuit used in the experiment under unloaded condition was composed to meet the reasonable conditions mentioned above, and a successful commuting performance was achieved without failure. Several types of microprocessor having a different value of CPU speed individually have been applied to the experiment under the loaded conditions. Also it shows that the faster the speed of CPU is, the more stable the commutation turns out.

• Journal of the Korean Professional Engineers Association
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• v.42 no.4
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• pp.45-50
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• 2009

The modal split structure of the Korea's transportation system has been dominated by road-oriented structure. The shortage of the inftrastructure to accommodate the rapidly increasing travel demand has brought about socio-economic losses such as severe traffic congestion and high logistic costs, and thereby weakened the competitiveness of the country. Highway transportation sector is more vulnerable to energy consumption comparing with railway sector since the highway sector is dependent mostly on fossil fuels for its energy source. In 2006 annual road cogestion costs in Korea reached 24.6 trillion won, with an average annual growth rate of 5.4%. The annual road congestion cost of intercity highways were 9.2 trillion won. As the new cities that recently developed are located far from Seoul area, the boundary of commuting in Seoul metropolitan area is extended. It makes passengers have longer trips with longer travel time, and the congestion problem to be more serious. In this regards, Gyeonggi Provincial Government proposed a deeper underground metropolitan express train system for the greater Metropolitan area. which is named as GTX. Gyeonggi Province suggested 3 key underground lines, based on the outcome of the feasibility study conducted by the Korea Society of Transportation, and submitted to the Ministry of Land Transportation and Maritime Affairs for its review. If the project is approved for construction and completed in 2016, the daily volume of surface traffic bound for Seoul will be reduced substantially and therefore the users will be benefitted for time savings by an annual amount of 2 trilion won every year.

• Journal of Digital Contents Society
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• v.18 no.1
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• pp.115-121
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• 2017

The Korea metropolitan areas have the largest of population density in OECD countries. Those people who use public transportation is facing many difficulties in commuting and going to school. There are many applications to help this situation. However, those applications inform a regular timetable and also offer a real-time alarm to user by user's passive action. In this paper, we design and implement the application that give the real-time traffic information and the arrival notification message about subway, bus and foot to user.

• Journal of the Korean Society for Railway
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• v.11 no.4
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• pp.417-423
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• 2008

Transportation planners are increasingly adopting policies aimed at changing travel choices made by general commuter. Theories on the relationship between high-speed technology and transport address changes in travel behavior of regional commuter due to alterations in the Kyung-Bu railroad transportation corridor. The purpose of this paper is to examine the relationships between travel behavior and high-speed technology. The KORAIL data allows us to explore the differences between travel characteristics that are usually hard to discern by guesswork. The effects of travel time were found to be significant in the full decisions that control for commuting KTX. Although many argue that transportation behavior cannot be changed, this paper demonstrates that about 4 years of behavioral data on KTX travel show otherwise. In this paper we explore several possibilities to fill in some of the gaps in our knowledge on the expansion of commuter belt.

• Journal of Korean Society of Rural Planning
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• v.26 no.4
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• pp.107-116
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• 2020

The purpose of this study is to analyze the characteristics of the 11 southeastern states in the United States by using regional characteristics variables and to classify the regions. First, 19 variables from four categories of population, society, industry-economy and urban service were selected and factor analysis were conducted, and the result showed five major factors of population, economic condition, job and commuting. Based on the following factor scores, a cluster analysis was conducted, and eight types of big city, medium-sized city, bed town, small town, urban hinterland, retirement town, and rural village were derived. These types of spatial distribution characteristics showed big cities were by different types of regions and they formed metropolitan areas. Each types of classified regions were located along the road network with hierarchy. The study focused on cases in the southeastern regions of the United States and can be used as a comparison with Korean cases. If the same research method is applied to Korea in the future, or if the time series of changes is tracked by analyzing different time points, it will greatly help identify the characteristics of urban and rural mixed areas.

• Land and Housing Review
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• v.11 no.1
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• pp.1-10
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• 2020

The purpose of this study is to identify the characteristics of residents for purchased public housing in Seoul, using empirical panel data. The scope of the study will be targeted at the Seoul, as of 2017. The research method includes literature review, statistical analysis, and spatial analysis using QGIS software program. The data used in the research is the Panel Survey of Public Housing in Seoul(2017). The main results of the research are briefly summarized as follows; Firstly, Living in a housing with an increased area compared to the previous housing. Secondly, they can live for a long time with low rent. The burden on housing costs is 71.8% in the case of the deposit. Thirdly, there is little concern about social stigma. Purchased public housing was found to be good in terms of stigmatization due to low-income clusters. Lastly, the accessibility in the city center was good condition. In particular, commuting time was 34.79 minutes on a one-way basis, saving about 4 minutes compared to other types of public housing.