• Korea Journal of Hospital Management
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• v.15 no.4
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• pp.43-62
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• 2010

This study provides an evidence on the determinants of the profitability of university hospital by analyzing university hospital-level data set of hospital performance during the year 2007 (32 university hospitals in total). For the study, a multiple regression model is employed in which profitability index obtained from the DEA computations, operating margin to total asset and gross revenue are used as the dependent variables, and a number of hospital operating characteristics are chosen as the independent variables such as ownership type, location, bed size, period of establishment, bed occupancy rate, admission ratio of outpatients, patients per medical specialist, personnel cost per patient, liabilities to total assets, current ratio, fixed ratio, total asset turnover, medical assistance rate and public indicator. First, the results indicate that the bed occupancy rate and liabilities to total assets are positively and significantly associated with operating margin to total asset. Second, number of beds, the bed occupancy rate and number of patients per medical specialist are positively and significantly associated with operating margin to gross revenue. Third, the bed occupancy rate, number of patients per medical specialist, liabilities to total assets, total asset turnover are positively and significantly associated with profitability index revealed from DEA.

• Geomechanics and Engineering
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• v.2 no.4
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• pp.321-335
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• 2010

This article describes a laboratory research on stabilizing tropical peat using ordinary Portland cement (OPC) as a binding agent, and polypropylene and steel fibres as chemically inert additives. California bearing ratio (CBR) and unconfined compressive strength (UCS) tests were carried out to evaluate the increase in the strength of the stabilized samples compacted at their optimum moisture contents and air cured for up to 90 days. The results show that the UCS values of stabilized peat samples increased by as high as 748.8% by using OPC (5%), polypropylene fibres (0.15%), and steel fibres (2%). The CBR values of the samples stabilized with OPC (5%), polypropylene fibres (0.15%), and steel fibres (4%) showed an increase of as high as 122.7%. The stabilized samples showed a shrinkage in volume upon air curing and this shrinkage was measured by an index called, volume shrinkage index (VSI). The highest VSI recorded was 36.19% for peat without any additives; and the minimum was 0% for the sample containing 30% OPC, 0.15% polypropylene fibres and 2% steel fibres. The technique of stabilizing peat with OPC, polypropylene and fibres, coupled with air curing, appears to be cost-effective compared with other frequently used techniques.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2007.11a
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• pp.412-415
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• 2007

Recently advanced nations utilize evaluation system about LCC, and KOREA begin to introduce the system to reduce construction expense. And Introducing "Technical proposal type bid" that is new government construction order mode made needs for valuation of price to evaluate facilities LCC. These days LCC is evaluated by BTL and turnkey project in KOREA, but it is suffering from difficulty in evaluation. because evaluation element and standard are indefinite. In addition LCC evaluation of public construction business except BTL and turnkey is not consisting. Therefore, in this research we present LCC evaluation Index for systematic and objective evaluation.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.7
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• pp.542-549
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• 2002

Computer simulation is essential to design the suspension elements of railway vehicle. By computer simulation, engineers can assess the feasibility of given design variables and chance them to get a bettor design. Even though commercial simulation codes are used, the computational time and cost remains non-trivial. Therefore, malty researchers have used a mesa model made by sampling data through simulation. In this paper, four mesa-models for each index group such as ride comfort, derailment Quotient, unloading radio and stability index, are constructed by use of neural network. After these meta models are constructed, multi-objective optimization are achieved by using the differential evolution. This paper shows that the optimization of design variables using the neural network model is very efficient to solve the complex optimization Problem.

• Steel and Composite Structures
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• v.36 no.1
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• pp.31-45
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• 2020

The purpose of this study is to develop an effective iterative two-stage method (ITSM) for structural damage identification of offshore platform structures. In each iteration, a new damage index, Modal Energy-Based Damage Index (MEBI), is proposed to help effectively locate the potential damage elements in the first stage. Then, in the second stage, the beetle antenna search (BAS) algorithm is used to estimate the damage severity of these elements. Compared with the well-known particle swarm optimization (PSO) algorithm and genetic algorithm (GA), this algorithm has lower computational cost. A modal energy based objective function for the optimization process is proposed. Using numerical and experimental data, the efficiency and accuracy of the ITSM are studied. The effects of measurement noise and spatial incompleteness of mode shape are both considered. All the obtained results show that under these influences, the ITSM can accurately identify the true location and severity of damage. The results also show that the objective function based on modal energy is most suitable for the ITSM compared with that based on flexibility and weighted natural frequency-mode shape.

• Journal of Sensor Science and Technology
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• v.30 no.6
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• pp.415-419
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• 2021

We developed a highly accurate, yet inexpensive, refractive index (RI)-based soil moisture sensor. To detect the RI, a light guide was set with a light-emitting diode and photodiode. When the air fills the space between the soil particles, most of the incident light is reflected at the interface between the waveguide and the air because of the large RI difference. As the moisture of the soil increases, the macroscopic soil RI increases. This allows incident light to pass through the interface. The intensity of the light reaching the photodiode was simulated according to the change in the soil RI. Using the simulation results, we designed and manufactured a curved glass waveguide. We evaluated the performance of the RI-based soil sensor by comparing it with a commercially available, high-cost and high-performance time-domain reflectometer (TDR). Our sensor was 96% accurate, surpassing the costly TDR sensor.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2145-2157
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• 2018

Congestion Management (CM) is an attractive research area in the electrical power transmission with the power compensation abilities. Reconfiguration and the Flexible Alternating Current Transmission Systems (FACTS) devices utilization relieve the congestion in transmission lines. The lack of optimal power (real and reactive) usage with the better transfer capability and minimum cost is still challenging issue in the CM. The prediction of suitable place for the energy resources to control the power flow is the major requirement for power handling scenario. This paper proposes the novel optimization principle to select the best location for the energy resources to achieve the real-reactive power compensation. The parameters estimation and the selection of values with the best fitness through the Symmetrical Distance Travelling Optimization (SDTO) algorithm establishes the proper controlling of optimal power flow in the transmission lines. The modified fitness function formulation based on the bus parameters, index estimation correspond to the optimal reactive power usage enhances the power transfer capability with the minimum cost. The comparative analysis between the proposed method with the existing power management techniques regarding the parameters of power loss, cost value, load power and energy loss confirms the effectiveness of proposed work in the distributed renewable energy systems.

• Journal of Korea Spatial Information System Society
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• v.11 no.4
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• pp.85-88
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• 2009

In multimedia database systems, the nearest neighbor Query occurs frequently and requires the processing cost higher than other spatial Queries do. It needs the measurement of search distance that the number of searched nodes and the computation time in an index can be minimized for optimizing the cost of processing the nearest neighbor query. The circular location property of objects is considered to accurately select the nodes which will be searched in the nearest neighbor query. In this paper, we propose the processing method of nearest neighbor queries be considered a circular location property of object where the search space consists of a circular domain and show its characteristics. The proposed method uses the circular minimum distance and the circular optimal distance, the search measurement for optimizing the processing cost of nearest neighbor queries.

• The Korean Journal of Ecology
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• v.21 no.5_1
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• pp.409-418
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• 1998

A molel study was conducted to determine the optimal sample size for the analysis of the aquatic insect community in a stream reach of the Pangtae Creek, Kangwon-do in October 1995 and may 1996. The results showed that the required minimum sample size varied and depended on the purposes of the community analysis. Acoording to the Species: Area Curve method, at least 16 Surber samplings ($30{\times}30cm$) were required in a stream reach in each spring and fall survey. The species diversity index did not vary significantly as the sample size increased. Based on the coefficient of variation analysis, the minimum sample sizes of 10 were required in order to compare seasonal differences of the community in the study area. Considering the static community structure of aquatic insects, including both species numbers and individual numbers of aquatic insects, 11 and 7 samplings were optimal sizes for the fall and spring survey, respectively. We concluded that 12 Surber samplings from 3 riffle-pool sequences (4 samplings at each riffle-pool sequence) would be required in a stream reach (length 1 km) to obtain reliable as well as cost efficient data. Our model showed that the optimal sample size should be determined by interactions between minimum sample size, the degree of data reliability, and cost efficiency.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2002.04a
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• pp.39-43
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• 2002

IMF situation in Korean society in 1997 gave huge shock to all areas, such as politics, economy, and society which were covered by bubble economy. It has passed 4 years since IMF but it is continued to increase of consumer price index and depression of the society. Receiving an order in interior design become more and more tense competition domestically as well as internationally, due to the open of WTO. In order to achieve economic design of low cost-high design which pursues the power of competition in cost and quality, this study investigated specific methods for economic design and suggested the directions for economic design in interior design field. To suggest the directions of future interior design for economic design with the analysis of domestic and international cases for economic design. the following results are showed: According to the analysis of the cases, economic design is accomplished with the use of the materials. Interior designers should consider how they can use materials for economic design. Especially, use of cheap materials gives the reduction of the cost and the effects of differentiation of the spaces more. Therefore, experimentalism and knowledge of materials are needed and they should be more weighted as the method for achieving economic design,