• ETRI Journal
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• v.38 no.4
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• pp.735-745
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• 2016

The Paris agreement at the 21st Conference of the Parties (COP21) emphasizes the reduction of greenhouse gas emissions and increase in energy consumption in all areas. Thus, an important aspect is energy saving in buildings where the lighting is a major component of the electrical energy consumption. This paper proposes a building energy management system employing visible light communication (VLC) based on LED lighting. The proposed management system has key characteristics including personalization and localization by utilizing such VLC advantages as secure communication through light and location-information transmission. Considering the efficient implementation of an energy-consumption adjustment using LED luminaires, this paper adopts variable pulse position modulation (VPPM) as a VLC modulation scheme with simple controllability of the dimming level that is capable of providing a full dimming range. This paper analyzes the VPPM performances according to variable dimming for several schemes, and proposes a VPPM demodulation architecture based on dimming-factor acquisition, which can obtain an improved performance compared to a 2PPM-based scheme. In addition, the effect of a dimming-factor acquisition error is analyzed, and a frame format for minimizing this error effect is proposed.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.794-799
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• 2015

To manage cell outage problem in indoor wireless communication systems, we should resolve the problem of abrupt network failure quickly. In this paper, we propose a near-optimal cell outage management (NoCOM) scheme to support seamless services to users. In consideration of system throughput, user fairness, and the guarantee of QoS simultaneously, the NoCOM scheme finds the solution of subchannel and power allocations using a non-convex optimization technique and allocates radio resources to users iteratively. Through intensive simulations, we verify the outstanding performances of the proposed NoCOM scheme with respect to the average cell capacity, user fairness, and computational complexity.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.15 no.8
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• pp.1743-1749
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• 2011

The multimedia data for video-on-demand(VOD) service has large, continuous and real time characteristics. The frequent disk I/O operations takes much time and decrease the system performance in multimedia services. Therefore the efficient buffer management is needed in order to reduce the disk accesses to multimedia data. This paper addresses how to increase the buffer hit ratio and the number of users in a multimedia service like VOD by increasing the utility of buffer. This paper also simulated various resource management algorithms and strategies and evaluated, compared and analyzed their performances.

• Journal of the Korea Society of Computer and Information
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• v.4 no.4
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• pp.199-208
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• 1999

The purpose of this study is to find a cause of economic performance differences among industries. For this purpose, several hypothesis are established and tested (1) Whether the firm's capability and performance are different among industries\ulcorner (2) Whether the firm's management resources affects the performance are different among industries\ulcorner (3) Whether the firm's performances are different between high performance group and low performance group in same industry\ulcorner The results of this study are (1) the level of firm's capability and performance are different and (2) the management resources which affect the performance are different according the industry. And (3) the management resources are different according to the firm's performance level in same industry.

• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.149-154
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• 2007

Now, in Korea, the performances of the building service equipment relay on the individual superintendent's share for the assessment of performance, fault detection, deterioration diagnosis of the building service equipment. As the result, very different quality of the performance or the durability of equipment is being obtained with his skill and effort and it is also not easy to assess that quality. This finally lead to the waste of labor force and the operating cost due to the high-cost, low-efficiency system. How to construct the N-BMS was considered to save energy, resource and to conserve performance of building service equipment. The FEMIS, facility, energy/environmental management & information system, for building service offer management process integrated with BAS, FMS and EMS and so on.

• The Journal of Asian Finance, Economics and Business
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• v.6 no.1
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• pp.205-215
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• 2019

Researchers have confirmed the relationship between ambidexterity learning and innovation performance, but according to the resource-based theory, the relationship between ambidexterity learning and innovation performance is also affected by the internal resources of the organization. Internal resources are an important factor affecting the transformation of learning outcomes into performance. In addition, few scholars have pointed out whether different types of learning have different effects on different types of innovation performance. This study collects data from 170 High-tech enterprises in Shandong, china, and discusses the effects of exploitative learning and explorative learning on management innovation performance and technological innovation performance. This study further examines the moderating role of slack resource on the relationship between ambidexterity learning and innovation performance. Results show that ambidexterity learning has positive effect on innovation performance. Compared with exploitative learning, explorative learning has a greater impact on management innovation performance; compared with explorative learning, exploitative learning has a greater impact on technological innovation performances. Slack resource has positive moderating role between the relationship of exploitative learning, explorative learning and technology innovation performance. But Slack resource has no moderating role between the relationship of exploitative learning, explorative learning and management innovation performance.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.19 no.3
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• pp.133-142
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• 2009

Although the average amount of spam users receive a day is statistically decreasing in Korea, they still complain of spam and insist there is a gap between the amount of spam users receive in reality and the amount of spam the users feel due to spam. This study analyzes the cause of the gap and suggests the way of complementing the traditional measure of the amount of spam receipt. In addition, we provide the conceptual framework of 'spam management index' that explains the overall spam counteract performances from the users' point of view. Especially, we develop the method of measuring 'spam stress' which can be used as an qualitative output element. Finally we apply the model in Korea to develop spam counteract policies.

• International conference on construction engineering and project management
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• 2009.05a
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• pp.550-557
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• 2009

The concepts of 'sustainable development', 'sustainable construction' and 'green building' have been elevated to priority levels in all types and phases of construction project development worldwide. Consultants and contractors are now required to seriously consider the impact of their operations on the natural environment and the society, and consequently adopt sustainable construction practices in the development process to minimize and mitigate the negative impacts of their activities. However, existing sustainability rating tools apply to the design, post-construction and operation phases of a building; no tool exists for the rating of the performance of the contractor or the project team at the construction phase. This study aimed to develop a model for evaluating the sustainability of construction operations, drawing on the global best practice standards on sustainability. Practical applications of the model were carried out through case studies to evaluate the performances of fifteen construction firms in New Zealand. The developed model and the outcomes of the case studies were presented, including potential areas of weaknesses, strengths, constraints to achievement or adoption of sustainable construction practices and areas for improvement in the operations of the firms. The successful application of the developed model in practice shows its usefulness and ease of application. It is therefore recommended for adoption as a simple but effective system for measuring and reporting on sustainability performance or sustainability of construction operations of firms in New Zealand and elsewhere.

• International Area Studies Review
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• v.22 no.2
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• pp.121-138
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• 2018

This study aims to suggest effective management performances of nonprofit arts organizations among competitive environment. To examine the factors which affect the performance of nonprofit performing arts organizations such as external environment, cultural capital, orchestra characters and government grants, this study analyzed the data of 990 tax forms of the US Internal Revenue Service(IRS) of the top 73 symphony orchestras and government sources in USA. Independent variables are measured as sponsorship amount which is the biggest part of orchestras' income, and ticket sales which is profit of inherent business purpose. As a result, the performance of the orchestra is affected positively by the income and influenced by the orchestras' characteristics including age, size, and conductor. Also government grants to the orchestras are essential for organizations to sustain their business. But, there are two different sides on these effects that small to medium groups are influenced by crowding in effect and bigger groups are more likely conducted by business overview. Lastly, cultural capital is no significant relationships to orchestras' management performances. This scope of the study is limited to American symphony orchestras; however, this study is significant in that empirical analysis on nonprofit performing arts organizations from an economic view point and contribute on other nonprofit arts organizations to develop their strategic plan for sustainable business.

• Management Science and Financial Engineering
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• v.20 no.1
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• pp.21-26
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• 2014

A lot of researches have been conducted to estimate the volatility smile effect shown in the option market. This paper proposes a method to approximate an implied volatility function, given noisy real market option data. To construct an implied volatility function, we use Gaussian Processes (GPs). Their output values are implied volatilities while moneyness values (the ratios of strike price to underlying asset price) and time to maturities are as their input values. To show the performances of our proposed method, we conduct experimental simulations with Korean Equity-Linked Warrant (ELW) market data as well as toy data.