• Journal of the Korea Society of Computer and Information
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• v.23 no.5
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• pp.9-14
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• 2018

For an efficient management of electricity market and power systems, accurate forecasts for electricity demand are essential. Since there are many factors, either known or unknown, determining the realized loads, it is difficult to forecast the demands with the past time series only. In this paper we perform a cluster analysis on electricity demand data collected from Jan. 2000 to Dec. 2017. Our purpose of clustering on electricity demand data is that each cluster is expected to consist of data whose latent variables are same or similar values. Then, if properly clustered, it is possible to develop an accurate forecasting model for each cluster separately. To validate the feasibility of this approach for building better forecasting models, we clustered data with t-SNE. To apply t-SNE to time series data effectively, we adopt the dynamic time warping as a similarity measure. From the result of experiments, we found that several clusters are well observed and each cluster can be interpreted as a mix of well-known factors such as trends, seasonality and holiday effects and other unknown factors. These findings can motivate the approaches which build forecasting models with respect to each cluster independently.

• The Journal of the Korea Contents Association
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• v.15 no.5
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• pp.498-506
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• 2015

As smart phone market has been rapidly saturated, wearable devices have been emerging as a new growth power in the post smart phone era. This study aims to comprehend the influential factors of purchasing intention of product features(perceived usefulness, perceived ease of use) and individual characteristics(innovation, fashion leadership, self-efficacy, concern for health) of wrist wearable device. The result shows that fashion leadership and health concern among consumers' individuality, and perceived usefulness and perceived usability among product features are proved to be significant factors. This means that both usefulness and usability have significant impacts on purchase intention of wearable device and product development should be made to enhance user experience.

• Spatial Information Research
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• v.16 no.1
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• pp.33-50
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• 2008

At present, the cadastral field, with the conversion into digital cadastral map management system, not the existing cadastral map management system, has gone through a lot of changes, such as the market opening of cadastral surveying and overseas launching of a cadastral field. Such an environmental change has brought on a lot of advantages, such as improvement in accuracy of surveying, efficient management system, and reinforcement of competitive power in cadastral surveying. However, the conversion into the advanced cadastral management system serves to relatively heightening the possibility of outflow of cadastral information and its technology in comparison with in the past. This research, with the aim to cope with indiscriminate outflow of cadastral technology, is aimed at suggesting the plan for the prevention of outflow of cadastral technique and its protection after examining and considering the contents of environmental changes in the currently going cadastral field.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.44 no.4 s.316
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• pp.21-27
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• 2007

Recently cluster system built from personal computers and network devices are easily and economically constructed. Rapid technological change discloses new processors on the market yielding cluster systems heterogeneity. A parallel system in heterogeneous environment needs work managers for utilizing the full power of the heterogeneous cluster system. In this paper, we compare MPI and Cilk in a heterogeneous cluster system in terms of performance and code complexity. Experimental results show that Cilk is better than MPI with small sizes of data transfers while MPI outperforms Cilk with big sizes of data transfers. Also, We find that Cilk requires less programming efforts to write a parallel program.

• Journal of Korea Game Society
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• v.11 no.6
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• pp.95-102
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• 2011

At present, with the rise of smart-phone market supported the Wi-Fi, smart-phone based network content has propagated rapidly. But, network content service is difficult in feature phone and multimedia device not supporting the Wi-Fi or supporting only the bluetooth. This paper was used the zigbee technology supporting low power, low cost, availability, multi channel, broadcasting compared to the bluetooth or Wi-Fi. It will provide a variable network game development by utilizing the zigbee technology. Also, it is provide the development of variable mobile network contents using the zigbee.

• Journal of Drive and Control
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• v.14 no.3
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• pp.8-17
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• 2017

With automobiles sharply increasing in numbers worldwide, we are faced with critical social issues such as traffic accidents, traffic jams, environmental pollution, and economic inefficiency. In response, research on ITS is promoted mainly by regions with advanced automotive industry such as the U.S., Europe, and Japan. While Korea is working on moving forward in the global market through developing and turning to global standards systems related to ASV (Advanced Safety Vehicle), the country is not fully prepared for such projects. The purpose of ACC (Adaptive Cruise Control) is to control a vehicle's longitudinal speed and distance and minimize driver workload. Such a system should be valuable in preventing accidents, as it reduces driver workload in the 21st-century world of telematics created by development of the automobile culture industry. In this light, the thesis presents a method to test and evaluate ACC system and a mathematical method to assess distance. For the proposed test and evaluation, theoretical values are tested with vehicle test and a database is acquired, by using vehicles equipped with an ACC system. Theoretical evaluation criteria for developing ACC system may be used and scenario-specific evaluation methods may find useful application through testing the formula proposed by comparing the database and mathematical method.

• Journal of the Korean housing association
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• v.21 no.4
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• pp.81-88
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• 2010

Recently, house demander's needs has diversified in the increasingly by the drastic change in the social environment, changes in family structure and population, the growing interest of living environment. So in the future, housing supply to respond to a variety of housing needs is absolutely necessary to differentiate. The purpose of this study is to analyze the lifestyle types of middle-aged married women with high purchasing power in the current housing market and propose the dwelling style by housing awareness and needs analysis. To collect the data, LOV survey method was used for 528 residents in Seoul and metropolitan area. The data analysis used SPSS PC 14.0 to find the frequency, chi-square, factor analysis, and cluster analysis. The results of analysis are as follows: First, the lifestyle was segmented into four groups such as Conservative goal-achieving lifestyle, Individual self-developing lifestyle, Positive self-trusting lifestyle, Outgoing trend-seeking lifestyle. Second, largely the dwelling style according to lifestyle types was divided into living room-kids room type and living room-kitchen type. Third, there were different preferences on the each type of housing space and the $\alpha$-space by different clusters.

• Journal of the Korean Solar Energy Society
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• v.31 no.6
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• pp.125-131
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• 2011

Recently, the application of renewable energy to building is steadily increasing in domestic due to the energy saving efforts around the world. Among the all, wind energy is one of the rising energy source because of its high technological maturity. Domestic wind power market has rapidly increased in recent years but the certification system for wind turbine has not been activated since it was introduced in 2009. Thus, this study aims to propose the improvement of certification system for wind turbine by comparing domestic certification system with international certification system. The result of this study are as follows. First, domestic certification system needs to be subdivided and established by systematic standards. Second, it is considered that education about rating standards is required to wind turbine makers to activate domestic certification system. Third, domestic certification agenciesand test agencies need to be unified and reduced.

• Journal of the Korean Professional Engineers Association
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• v.44 no.6
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• pp.40-44
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• 2011

Nuclear energy in Korea began in 1958, when the Korea's atomic energy act was formulated and the relevant organizations were founded. Since then, notwithstanding the two catastrophe like TMI and Chernobyl accident, Korea made a wise decision to expand the peaceful uses of the nuclear energy as well as to localize the essential nuclear design technology of fuel and nuclear steam supply system. This decision resulted in the success of export of nuclear power plants as well as research reactor in 2010s. The Korea's nuclear policy, which well utilized 'international crisis in nuclear business' as 'opportunity of Korea to get. nuclear technology', is believed nice policy as a role model of nuclear new-comer countries. Based upon the success story of localization of nuclear technology, Korea had an eye for a niche market, which was a basis of development of SMART, Korea-made integral PWR. The operation of a SMART plant can sufficiently provide not only electricity but also fresh water for 100,000 residents. Last two years, Korea's nuclear industry team led by the Korea Atomic Energy Research Institute completed the standard design of SMART and applied to the Korea's regulatory body for standard design approval. Now the Korea's licensing authority is reviewing the design with the relevant documents, and the design team is doing its best to realize its hope to get the approval by the end of this year. From next year, the SMART business including construction and export will be explored by the KEPCO consortium.

• International Journal of Fluid Machinery and Systems
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• v.3 no.4
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• pp.352-359
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• 2010

In recent years, the market has shown increasing interest in pump-turbines. The prompt availability of pumped storage plants and the benefits to the power system achieved by peak lopping, providing reserve capacity, and rapid response in frequency control are providing a growing advantage. In this context, there is a need to develop pumpturbines that can reliably withstand dynamic operation modes, fast changes of discharge rate by adjusting the variable diffuser vanes, as well as fast changes from pumping to turbine operation. In the first part of the present study, various flow patterns linked to operation of a pump-turbine system are discussed. In this context, pump and turbine modes are presented separately and different load cases are shown in each operating mode. In order to create modern, competitive pump-turbine designs, this study further explains what design challenges should be considered in defining the geometry of a pump-turbine impeller. The second part of the paper describes an innovative, staggered approach to impeller development, applied to a low head pump-turbine project. The first level of the process consists of optimization strategies based on evolutionary algorithms together with 3D in-viscid flow analysis. In the next stage, the hydraulic behavior of both pump mode and turbine mode is evaluated by solving the full 3D Navier-Stokes equations in combination with a robust turbulence model. Finally, the progress in hydraulic design is demonstrated by model test results that show a significant improvement in hydraulic performance compared to an existing reference design.